JP2009255779A - Vehicle height adjustment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle height adjustment system capable of reducing the non-uniformness of pressure in right and left vehicle height adjustment actuators by a means different from a conventional vehicle height adjustment system. <P>SOLUTION: Vehicle height adjustment is performed in the order of a vehicle height corresponding to right and left front wheels, a vehicle height corresponding to a left rear wheel and a vehicle height corresponding to a right rear wheel. Regarding air springs corresponding to the respective wheels, the feeding of air and the discharge allowance of air are performed in the order, and a plurality of operations are repeated to adjust the vehicle height to a target vehicle height (S7-S11, S16-S20). Regarding the right rear air spring in which the feeding of air and the discharge allowance of air are finally performed, the additional feeding of air of a predetermined amount and discharge allowance are performed to reduce the non-uniformness of the internal pressure of the right and left rear air springs (S13, S22). The vehicle height corresponding to the left rear air spring for performing the feeding and discharge allowance of air are performed at the second from the last is controlled to the set vehicle height intentionally made different from the target vehicle height, the vehicle height corresponding to the right rear air spring is controlled to a target vehicle height, and the non-uniformness of the right and left internal pressures may be reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle height adjustment system, and in particular, among the vehicle height adjustment actuators provided corresponding to the left and right front wheels and the left and right rear wheels, alleviating pressure unevenness inside the left and right vehicle height adjustment actuators. It is about.

  The vehicle height adjustment system includes vehicle height adjustment actuators provided corresponding to the left and right front wheels and the left and right rear wheels of the vehicle. For example, in the vehicle height adjustment system described in Patent Document 1 below, the vehicle height adjustment actuator is configured by an air spring, air is supplied to each air spring, and discharge of air from the air spring is allowed. Thus, the vehicle height corresponding to the wheel is changed, and the change of the vehicle height corresponding to the change of the load acting on each wheel is allowed by the compression and extension of each air spring.

In the vehicle height adjustment system described in Patent Document 1, the vehicle height corresponding to the wheels is controlled to the target vehicle height without causing a situation in which rolling of the vehicle is likely to occur. The situation in which rolling of the vehicle is likely to occur occurs when the pressures of the left and right air springs are not uniform. Since the air spring has a spring constant corresponding to the internal pressure, if the left and right pressures are non-uniform, the left and right spring constants are non-uniform and rolls are likely to occur. This situation occurs because the vehicle height of the four wheels may coincide with the target vehicle height even if the shared load of the four wheels is not uniform. When vehicle height adjustment is performed for each wheel, if the vehicle height is increased for one of the left and right wheels, the vehicle height is also increased for the other wheel, and then the vehicle height is increased for that wheel. The target vehicle height will be reached. Therefore, if the shared load is smaller than the planned load, the spring constant becomes smaller and the left and right spring constants become uneven, the vehicle starts to run, and if the load sharing balance is lost, rolls will occur, In the vehicle height adjustment system described in Patent Document 1, a roll state in which a control threshold value used for determining whether or not the vehicle height has reached the target vehicle height for each wheel is generated on a spring of the vehicle. In addition, the spring constants of the four air springs are set to values that maintain a balance in which it is difficult to generate a roll in the vehicle while controlling the vehicle height to the target vehicle height.
Japanese Patent Laid-Open No. 10-309919

  The present invention has been made against the background of the above circumstances, and the unevenness of the pressure inside the left and right vehicle height adjustment actuators can be reduced by means different from the vehicle height adjustment system described in Patent Document 1. The issue is to provide a vehicle height adjustment system.

  The above-mentioned problems are (A) provided corresponding to each of the left and right front wheels and the left and right rear wheels of the vehicle, changing the vehicle height corresponding to each wheel as the working fluid is supplied and discharged, and acting on each wheel. Left front, right front, left rear, and right rear vehicle height adjustment actuators that allow changes in vehicle height in accordance with changes in load, and (B) supply fluid to these vehicle height adjustment actuators to adjust the vehicle height A control device of a vehicle height adjustment system including a fluid supply / discharge device allowing discharge of the working fluid from the actuator, and (C) a control device for controlling the fluid supply / discharge device, (a) the left and right front wheels and the left and right A vehicle that can detect the vehicle height corresponding to each of the rear wheels and that can individually detect the vehicle height corresponding to each of the left wheel and the right wheel for at least one of the left and right front wheels and the left and right rear wheels. A high detection device, and (b) the left and right front wheels and the left and right rear Supplying the working fluid to the vehicle height adjusting actuator corresponding to any one of the left wheel and the right wheel in a predetermined order lastly, The working fluid is discharged in a predetermined order in which the discharge of the working fluid from the vehicle height adjusting actuator corresponding to either the left wheel or the right wheel of either the front wheel or the left and right rear wheels ends. The vehicle height detected by the vehicle height detection device is controlled to the target vehicle height by performing at least one of the allowance, and the supply of the working fluid and the discharge of the working fluid in the predetermined order are permitted. Pressure in the at least one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators caused by at least one of It is solved by is intended to include the supply of a predetermined working fluid alleviating direction and the pressure differential relief type control unit for performing at least one additionally with allowable emission.

  The above problems are also (I) provided for each of the left and right front wheels and the left and right rear wheels of the vehicle, changing the vehicle height corresponding to each wheel as the working fluid is supplied and discharged, and for each wheel. Left front, right front, left rear, and right rear vehicle height adjustment actuators that allow changes in vehicle height in accordance with changes in applied load, and (II) supply working fluid to these vehicle height adjustment actuators A control device of a vehicle height adjustment system including a fluid supply / discharge device that allows the discharge of the working fluid from the adjustment actuator, and (III) a control device that controls the fluid supply / discharge device, (i) the left and right front wheels and the control device A vehicle that can detect the vehicle height corresponding to the left and right rear wheels, and can individually detect the vehicle height corresponding to each of the left wheel and the right wheel for at least one of the left and right front wheels and the left and right rear wheels. A high detection device; and (ii) the left front and right front vehicles Two or more pressure sensors for detecting the pressure in at least one of the height adjustment actuator and the left rear and right rear vehicle height adjustment actuators; and (iii) one of the left and right front wheels and the left and right rear wheels Supplying the working fluid to the vehicle height adjusting actuator corresponding to any one of the left wheel and the right wheel of the vehicle in a predetermined order, and the left and right front wheels and the left and right rear wheels. Permitting the discharge of the working fluid in a predetermined order in which the discharge of the working fluid from the vehicle height adjusting actuator corresponding to any one of the left wheel and the right wheel of By performing at least one, the vehicle height detected by the vehicle height detection device is controlled to the target vehicle height, and the left front and right front vehicles detected by the two or more pressure sensors are controlled. A pressure difference reduction type control unit that performs at least one of supply and discharge allowance of working fluid that reduces non-uniformity in pressure inside at least one of the adjustment actuator and the left rear and right rear vehicle height adjustment actuators; It is solved by including.

In the vehicle height adjustment system according to the present invention, it is desirable that the pressure difference reduction type control unit be operated both when the vehicle height is increased and when the vehicle height is decreased. It is possible to operate only in one of the cases of lowering, and in that case, an effect is obtained in one of them.
In addition, it is easy to include the sequential control unit and the additional control unit described in the next section as the pressure difference reduction type control unit, but supply of additional working fluid in the process of executing the control by the sequential control unit. It is also possible to perform at least one of discharge tolerance.
The above-mentioned “control the vehicle height to the target vehicle height” includes not only the control to the target vehicle height within the range of error, but also the left front and the right front depending on at least one of the additional supply of working fluid and the discharge allowance. The case where at least one vehicle height at the left rear and right rear slightly deviates from the target vehicle height is also included.
In addition, the above-mentioned “additionally performing at least one of supply and discharge permission of a predetermined working fluid” means, for example, when the vehicle height is increased, for example, the vehicle height adjusting actuator on the left rear (second from the last The working fluid is supplied to the vehicle height adjusting actuator that supplies the working fluid until the rear left vehicle height reaches the target vehicle height, and then the right rear vehicle height adjusting actuator (finally the working fluid supply). Compared with the case where the working fluid is supplied to the vehicle height adjusting actuator) until the right rear vehicle height reaches the target vehicle height, the working fluid supply to the right rear vehicle height adjusting actuator is increased. This means that when the vehicle height is lowered, the discharge tolerance of the working fluid from the right rear vehicle height adjustment actuator is increased.
According to a predetermined order in this system, the vehicle height adjustment is performed after one of the left and right front wheels and the left and right rear wheels, and the vehicle height corresponding to each of the left wheel and the right wheel is individually determined. Adjusted to Therefore, the change in the vehicle height corresponding to each of the left wheel and the right wheel affects each other, and causes an uneven pressure in each of the corresponding vehicle height adjustment actuators. By additionally performing at least one of supply of the determined working fluid and discharge allowance, the internal pressure non-uniformity is reduced (including elimination). Since the vehicle height adjustment is performed in a predetermined order, it is possible to know whether internal pressure non-uniformity occurs for the vehicle height adjusting actuators corresponding to the left and right wheels, and additional working fluid that reduces the pressure non-uniformity At least one of supply and discharge tolerance can be performed. Thereby, for example, the steering feeling and the vehicle behavior when steering is performed during traveling after the vehicle height adjustment is less likely to differ between left and right steering, and the vehicle stability is improved. Also, if the pressures inside the left and right vehicle height adjustment actuators are uneven, the balance that was maintained when the vehicle was stopped although the left and right shared loads were different, the vehicle was very short after the vehicle height adjustment. The vehicle may tilt while driving for a distance, and the vehicle may tilt and look worse.However, the reduction in pressure unevenness reduces the uneven load sharing on the left and right, reducing the deterioration in appearance due to vehicle tilting (resolved) Included).

  Another vehicle height adjustment system according to the present invention includes two or more pressure sensors, and controls the pressure in at least one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators. Because it is possible to detect and compare, additional supply or discharge of working fluid is performed while performing pressure detection and comparison, thereby reducing non-uniformity in internal pressure of left and right vehicle height adjustment actuators (including elimination) can do.

Aspects of the Invention

  In the following, the invention that is claimed to be claimable in the present application (hereinafter sometimes referred to as “claimable invention”. The claimable invention is at least the “present invention” to the invention described in the claims. Some aspects of the present invention, including subordinate concept inventions of the present invention, superordinate concepts of the present invention, and inventions of other concepts) will be exemplified and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is for the purpose of facilitating the understanding of the claimable invention, and is not intended to limit the combinations of the constituent elements constituting the claimable invention to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, the prior art, and the like. The added aspect and the aspect in which the constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention.

  In each of the following terms, (1) corresponds to claim 1, (2) corresponds to claim 2, (3) corresponds to claim 3, (5) corresponds to claim 4, (6) is in claim 5, (11) is in claim 6, (15) is in claim 7, (17) is in claim 8, (18) is in claim 9, Each corresponds.

(1) It is provided corresponding to each of the left and right front wheels and the left and right rear wheels of the vehicle, and changes the vehicle height corresponding to each wheel with the supply and discharge of the working fluid, and also changes the load acting on each wheel. Each front height, right front, left rear and right rear actuator for adjusting the vehicle height correspondingly,
A fluid supply / discharge device that supplies working fluid to the vehicle height adjusting actuators and allows discharge of the working fluid from the vehicle height adjusting actuators;
A vehicle height adjustment system including a control device for controlling the fluid supply / discharge device, wherein the control device comprises:
The vehicle height corresponding to each of the left and right front wheels and the left and right rear wheels can be detected, and for at least one of the left and right front wheels and the left and right rear wheels, the vehicle height corresponding to each of the left wheel and the right wheel is individually determined. A vehicle height detection device capable of detecting
The working fluid is supplied in a predetermined order in which the supply of the working fluid to the vehicle height adjusting actuator corresponding to any one of the left wheel and the right wheel of the left and right front wheels and the left and right rear wheels is the last. And the discharge of the working fluid from the vehicle height adjustment actuator corresponding to either one of the left wheel and the right wheel of the left and right front wheels and the left and right rear wheels is predetermined. The vehicle height detected by the vehicle height detection device is controlled to a target vehicle height by performing at least one of allowing discharge of the working fluid in order, and the working fluid in the predetermined order is controlled. At least one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators caused by at least one of supply and discharge of working fluid Vehicle height control system comprising a differential pressure relief type control unit for performing at least one additionally the supply and discharge allowable predetermined working fluid in a direction to reduce the uneven internal pressure.
(2) Supplying the working fluid to one of the two vehicle height adjusting actuators at a position where the vehicle height can be individually detected by the vehicle height detecting device and discharging the working fluid. The vehicle height adjustment system according to item (1), wherein at least one of the items is in the last order.
For any one of the left and right front wheels and the left and right rear wheels, one vehicle height sensor can be used for both the left wheel and the right wheel. In that case, the “predetermined order” of at least one of the supply and discharge allowance of the working fluid corresponds to one of the wheels on the side where one vehicle height sensor is used for both the left wheel and the right wheel. The vehicle height adjustment actuator may be the last order, but the vehicle height adjustment actuator corresponding to one of the wheels on the side where the dedicated vehicle height sensor is provided for each of the left wheel and the right wheel. It is desirable that the order be the last. Even when one vehicle height sensor is used for both the left wheel and the right wheel, the change in the output of one vehicle height sensor and the vehicle height at the position corresponding to the wheel where the supply or discharge of working fluid is permitted. Since there is a certain relationship between the change and the output of one vehicle height sensor when it is clear which of the left wheel and the right wheel is allowed to supply or discharge the working fluid, Based on this change, it is possible to know the change in the vehicle height at the position corresponding to the wheel to which the supply or discharge of the working fluid is permitted. Therefore, the “predetermined order” may be the order in which one vehicle height sensor is used for both the left wheel and the right wheel. It is desirable that the side where the dedicated vehicle height sensor is provided last is the vehicle height corresponding to the vehicle height adjustment actuator which is the last, so that the control can be accurately performed.
(3) The pressure difference reduction type control unit
The vehicle height detected by the vehicle height detection device by performing at least one of supplying the working fluid in the predetermined order and allowing the discharge of the working fluid in the predetermined order. Sequentially controlling the vehicle to the target vehicle height;
After the control by the sequential control unit, among the left front, right front, left rear and right rear vehicle height adjustment actuators, the left front and right front vehicle height adjustment actuators, An additional control unit that performs additional control in a direction that reduces non-uniformity of pressure in at least one of the left rear and right rear vehicle height adjusting actuators, and (1) or (2) Vehicle height adjustment system.
If the sequential control unit permits the supply and discharge of the working fluid in a predetermined order, the vehicle height adjustment actuator that increases the internal pressure and the vehicle height adjustment actuator that decreases the internal pressure are determined as a result. It is determined whether to allow additional supply or additional discharge of the working fluid to the high adjustment actuator. Further, if the execution time and the execution form (for example, whether or not to execute repeatedly) of the control by the sequential control unit are determined, the amount to which additional supply or additional discharge of the working fluid should be allowed is determined.
Therefore, by performing the additional control in this section, it is possible to at least reduce the pressure unevenness in the vehicle height adjusting actuator corresponding to the left wheel and the right wheel.
(4) The sequential control unit repeats supplying the working fluid in the predetermined order a plurality of times, and allowing the discharge of the working fluid in the predetermined order a plurality of times. The vehicle height adjustment system according to item (3), including a sequential control repeater that performs at least one of the following.
It is desirable that the control repeater sequentially operates at least when the vehicle height adjustment amount from the current vehicle height to the target vehicle height is large. Since the vehicle height adjustment by the sequential control unit can reduce the pressure difference generated in the left and right vehicle height adjustment actuators compared to the case where the same amount of vehicle height adjustment is performed at once as with the sequential control repeating unit. It is. However, the pressure difference between the left and right vehicle height adjusting actuators cannot be eliminated, and it is desirable to perform additional control according to the present invention.
(5) The sequential control unit simultaneously supplies at least one of supply and discharge allowance of the working fluid to one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators. And at least one of supplying and discharging the working fluid individually and sequentially to the other of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators; The vehicle height adjustment system according to item (3).
After performing at least one of the supply and discharge allowance of the working fluid to one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators, the left front and right front vehicle height adjustments are performed. If at least one of the supply of hydraulic fluid and the discharge allowance of the actuator and the other of the left rear and right rear vehicle height adjustment actuators are sequentially performed individually, the front and rear left and right vehicle heights simultaneously increase or decrease. Therefore, the vehicle height can be adjusted while avoiding hunting. In this case, the internal pressure is equal for the left and right vehicle height adjustment actuators in which at least one of the supply and discharge allowance of the working fluid is performed simultaneously, but the internal pressure is determined for the left and right vehicle height adjustment actuators that are performed individually. Since non-uniformity occurs, additional control is performed.
(6) The sequential control unit simultaneously supplies at least one of supply and discharge of working fluid to one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators. And at least one of supplying and discharging the working fluid individually and sequentially to the other of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators; The vehicle height adjustment system according to item (3), including a sequential control repeater that repeats a plurality of times.
If either the front or rear is allowed to supply or discharge working fluid to both the left and right vehicle height adjustment actuators at the same time, the difference in pressure in the left and right vehicle height adjustment actuators is eliminated or reduced. However, there may be a difference in vehicle height due to a difference in load or frictional resistance. On the other hand, if the supply or discharge of working fluid is allowed individually for the left and right vehicle height adjustment actuators on the other side of the front and rear, the left and right vehicle height difference can be reduced. It is inevitable that a difference occurs in the pressure in the vehicle height adjusting actuator. The effect of eliminating or reducing the pressure difference and reducing the vehicle height difference appears not only on the side where the working fluid is actually supplied or discharged (before or after) but also on the other side (after or before). Therefore, if the supply or discharge allowance of the working fluid at the same time on the left and right is repeated and the supply or discharge allowance on the left and right is repeated, the pressure difference and the vehicle height difference are avoided in both the left and right and front, and the comparison is made. A large amount of vehicle height can be adjusted. In addition, for example, when the right vehicle height adjustment actuator is supplied after the working fluid is supplied to the left vehicle height adjustment actuator, the left vehicle height increases slightly as the right vehicle height increases. If the control condition is set so that the increase amount falls within the control dead zone, the occurrence of hunting can be avoided.
However, the pressure difference between the left and right vehicle height adjusting actuators cannot be eliminated, and it is desirable to perform additional control according to the present invention. The same applies to the case where the working fluid is allowed to be discharged.
(7) The additional control unit may provide at least the supply of the working fluid and the discharge allowance of the working fluid to the vehicle height adjusting actuator in which at least one of the supply of the working fluid and the discharge allowance of the working fluid is performed last. The vehicle height adjustment system according to any one of (3) to (6), wherein the vehicle height adjustment system performs one of them.
(8) The vehicle height adjustment system according to (7), wherein the additional control unit supplies the working fluid to a vehicle height adjustment actuator that is supplied last with the working fluid.
(9) The vehicle height adjustment system according to (7), wherein the additional control unit allows discharge of the working fluid from a vehicle height adjustment actuator in which discharge of the working fluid is finally performed.
(10) The vehicle according to any one of (7) to (9), wherein the additional control unit performs at least one of supplying the working fluid and allowing discharge of the working fluid in a predetermined amount. High adjustment system.
The predetermined amount is set by, for example, time based on, for example, the loading conditions and structure of the vehicle. It may be set according to the pressure increase amount or the pressure decrease amount.
(11) Additional supply of the working fluid based on at least one of a vehicle height adjustment frequency and an adjustment time for one of the left front, right front, left rear, and right rear vehicle height adjustment actuators The vehicle height adjustment system according to any one of items (1) to (10), further including a vehicle height adjustment status-dependent amount changing unit that changes at least one of the amount of the hydraulic fluid and an additional discharge allowable amount of the working fluid .
When this item is subordinate to the item (10), the amount changing unit changes the “predetermined amount”.
The amount change may be always performed, or may be performed every time a certain condition such as the passage of a certain period is satisfied.
If at least one of the additional supply amount of the working fluid and the additional discharge allowance is inappropriate, the load shared by the four wheels is determined by the internal pressure of the left and right vehicle height adjustment actuators. Unlike the case of being equal, various situations resulting from it occur. For example, if one of the causes of non-uniformity in the internal pressure of the left and right vehicle height adjustment actuators is a variation in the friction coefficient of the components of the vehicle height adjustment actuator, the vehicle can be driven after the vehicle height change is completed. If a vibration or the like acts on the vehicle, the vehicle height adjustment actuator moves to generate a vehicle height that deviates from the target vehicle height, and vehicle height adjustment maintenance control is performed to maintain the vehicle height at the target vehicle height. The amount can be changed based on at least one of the frequency and the time required for adjustment. The same applies to the case where the secular change of the component of the vehicle height adjusting actuator is one of the causes of the pressure unevenness on the left and right. In addition, when the additional amount is set to an approximate amount from the beginning, the internal pressures of the left and right vehicle height adjusting actuators remain uneven, so it is desirable that the change by the amount changing unit in this section is performed.
In addition, since the deviation of the vehicle height from the target vehicle height causes the vehicle to tilt, the additional amount can also be changed by examining the posture of the vehicle when the vehicle travels after the vehicle height change is completed.
(12) The additional supply of the working fluid is performed based on at least one of a vehicle height adjustment frequency and an adjustment time for one of the left front, right front, left rear, and right rear vehicle height adjustment actuators. A vehicle according to any one of items (1) to (11), further including a vehicle height adjustment status dependence adequacy determination unit that determines whether or not the amount and the additional discharge allowable amount of the working fluid are appropriate or inappropriate. High adjustment system.
When this item is subordinate to the item (11), the amount changing unit changes the additional amount based on the determination result of the suitability determining unit. However, this is not indispensable, and the result of the suitability determination may be notified, and a person may take necessary measures such as changing the additional amount based on the notification.
(13) Additional supply of the working fluid is performed based on changes in the vehicle heights of the left front, right front, left rear, and right rear that occur when the vehicle is turned after the vehicle height change by the vehicle height adjustment system. The vehicle height adjustment system according to any one of (1) to (12), further including a turning state-dependent amount changing unit that changes at least one of an amount and an additional allowable discharge amount of the working fluid.
When the vehicle turns, the load applied to the front and rear wheels outside the turn increases due to centrifugal force, and the vehicle height decreases. When the vehicle turns, the load movement that occurs according to the turning direction and the change in the vehicle height are scheduled. If there is a change in the vehicle height that is against the plan, the pressure in any of the vehicle height adjustment actuators Therefore, the additional amount can be changed to an appropriate amount based on a change in the vehicle height that is against the schedule. For example, if the vehicle height of the right rear wheel is significantly lower than expected when turning left, the additional amount is increased so that the amount of working fluid supplied to the vehicle height adjustment actuator corresponding to the right rear wheel is increased.
For example, when the additional amount is set to an approximate amount from the beginning, the internal pressure of the left and right vehicle height adjustment actuators remains uneven, so the vehicle rolls when the vehicle height is turned after the vehicle height change is completed. The posture becomes abnormal, and the amount can be changed based on the abnormal posture.
(14) The additional supply of the working fluid is performed based on the changes in the vehicle heights of the left front, right front, left rear, and right rear that occur when the vehicle turns after the vehicle height change by the vehicle height adjustment system is completed. A vehicle height adjustment according to any one of items (1) to (13), further including a turning status dependence adequacy determination unit that determines whether or not the amount and the amount of additional discharge allowance for the working fluid are appropriate or inappropriate. system.
(15) It is provided corresponding to each of the left and right front wheels and the left and right rear wheels of the vehicle, and changes the vehicle height corresponding to each wheel in accordance with supply and discharge of the working fluid, and changes in the load acting on each wheel. Each front height, right front, left rear and right rear actuator for adjusting the vehicle height correspondingly,
A fluid supply / discharge device that supplies working fluid to the vehicle height adjusting actuators and allows discharge of the working fluid from the vehicle height adjusting actuators;
A vehicle height adjustment system including a control device for controlling the fluid supply / discharge device, wherein the control device comprises:
Vehicle heights corresponding to the left and right front wheels and the left and right rear wheels can be detected, and for at least one of the left and right front wheels and the left and right rear wheels, the vehicle height corresponding to each of the left wheel and the right wheel is individually determined. A vehicle height detection device capable of detection;
Two or more pressure sensors for detecting a pressure in at least one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators;
The working fluid is supplied in a predetermined order in which the supply of the working fluid to the vehicle height adjusting actuator corresponding to any one of the left wheel and the right wheel of the left and right front wheels and the left and right rear wheels is the last. And the discharge of the working fluid from the vehicle height adjustment actuator corresponding to either one of the left wheel and the right wheel of the left and right front wheels and the left and right rear wheels is predetermined. The vehicle height detected by the vehicle height detection device is controlled to a target vehicle height by performing at least one of allowing discharge of the working fluid in order, and detected by the two or more pressure sensors. Supply and discharge of working fluid for reducing non-uniform pressure in at least one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators Vehicle height control system comprising a differential pressure relief type control unit for performing at least one of the volumes.
(16) Supplying the working fluid to one of the two vehicle height adjustment actuators at a position where the vehicle height can be individually detected by the vehicle height detecting device and discharging the working fluid are permitted. The vehicle height adjustment system according to item (15), wherein at least one of the items is in the last order.
The explanation in paragraph (2) also applies to this paragraph.
(17) The pressure difference reducing control unit
The vehicle height detected by the vehicle height detection device by performing at least one of supplying the working fluid in the predetermined order and allowing the discharge of the working fluid in the predetermined order. A sequential control unit for controlling the vehicle to the target vehicle height,
The pressure in at least one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators detected by the two or more pressure sensors after the control by the sequential control unit. The vehicle height adjustment system according to item (15) or (16), further comprising: an additional control unit that performs at least one of supply and discharge permission of the working fluid that reduces non-uniformity.
After the vehicle height is controlled to the target vehicle height by the sequential control unit, the pressure difference caused by the vehicle height is detected by the two pressure sensors, and reduced (including cancellation) by executing at least one of supply of hydraulic fluid and discharge allowance. )
The features of the items (4) to (9) can also be applied to the vehicle height adjustment system of the item (17).
(18) The predetermined order is the last supply of the working fluid to the vehicle height adjustment actuator corresponding to one of the left wheel and the right wheel of the left and right front wheels and the left and right rear wheels. The order in which the supply of the working fluid to the vehicle height adjusting actuator corresponding to the other of the left wheel and the right wheel becomes the second from the last, and the left of either the left or right front wheel or the left or right rear wheel The working fluid is discharged from the vehicle height adjusting actuator corresponding to one of the wheel and the right wheel last, and the working fluid from the vehicle height adjusting actuator corresponding to the other of the left wheel and the right wheel is discharged. It is at least one of the order in which the discharge becomes the second from the last, and the pressure difference reduction type control unit performs the above operation until the vehicle height corresponding to the second vehicle height adjustment actuator from the last reaches the set vehicle height. Supplying at least one of dynamic fluid supply and discharge, performing at least one of supply and discharge of the working fluid such that a vehicle height corresponding to the last vehicle height adjustment actuator becomes the target vehicle height; and When the vehicle height corresponding to the last vehicle height adjustment actuator reaches the target vehicle height, the vehicle height that was the set vehicle height changes to the target vehicle height, and the two vehicles The vehicle height adjustment system according to item (1), including a simultaneous target vehicle height attainment type control unit set so that pressures in the high adjustment actuator are equal to each other.
In the vehicle height adjustment system of this section, for example, as the working fluid is supplied to the last vehicle height adjustment actuator, the internal pressure of the vehicle height adjustment actuator increases and the vehicle corresponding to the vehicle height adjustment actuator Although the height increases, the vehicle height corresponding to the vehicle height adjusting actuator to which the working fluid has been supplied second to last increases from the set vehicle height, and the pressure inside the vehicle height adjusting actuator decreases accordingly. . The vehicle height corresponding to the last vehicle height adjustment actuator reaches the target vehicle height, and at the same time, the vehicle height that was the set vehicle height increases to the target vehicle height, and the loads on the left and right wheels are the same. As long as the pressures in the vehicle height adjusting actuator controlled last and second from the last are equal to each other. Such a set vehicle height exists, and this set vehicle height can be obtained in advance by experiments or calculations. However, individual vehicles may have individual differences due to differences in friction coefficient or the load on the left and right wheels may not be uniform. In order to ensure that the vehicle heights corresponding to the vehicle heights are equal to each other with high accuracy and the pressures inside these vehicle height adjustment actuators accurately correspond to the respective loads, the appropriate vehicle height is learned for each vehicle. It is effective.
The same applies to the case where the discharge of the working fluid from each vehicle height adjusting actuator is permitted in order to reduce the vehicle height.
The aspect of this section is an aspect of the invention according to the section (1) that additionally performs at least one of a predetermined supply and discharge permission of the working fluid. The supply or discharge allowance of the working fluid to the vehicle height adjustment actuator to be controlled is stopped before the vehicle height corresponding to the vehicle height adjustment actuator reaches the target vehicle height, that is, a certain amount of vehicle height adjustment is withheld. The vehicle height adjustment in which the vehicle height adjustment actuator is the target vehicle height due to the change in vehicle height associated with the supply or discharge of working fluid to the vehicle height adjustment actuator to be controlled last, and the pressure in the vehicle height adjustment actuator is finally controlled. It can be considered that the pressure is equal to the pressure in the actuator. In this sense, the simultaneous target vehicle height attainment type control unit in this section can also be referred to as a stand-alone control unit.
The features described in the items (2) and (5) can also be applied to the vehicle height adjustment system of this item.
According to the vehicle height adjustment system described in this section, it is possible to reduce unevenness in the internal pressures of the left and right vehicle height adjustment actuators to an allowable error range without making the vehicle height higher than the target vehicle height.
For example, if additional working fluid is supplied for the last vehicle height adjustment actuator after the vehicle height corresponding to each of the four wheels is raised to the target vehicle height, the vehicle height adjustment actuator is supported. The vehicle height to be increased is further increased from the target vehicle height. On the other hand, in the present vehicle height adjustment system, the internal pressure non-uniformity can be reduced to an error range without making the vehicle height higher than the target vehicle height. The same applies when the target vehicle height is lowered.
(19) The pressure difference reduction type control unit includes a repetitive control unit that performs at least one of supplying and discharging permission of the working fluid to each of the plurality of vehicle height adjusting actuators in a plurality of times, and The vehicle height adjustment system according to item (18), wherein the part that performs the control at least the last time of the repetitive control unit is the simultaneous target vehicle height attainment type control unit.
It is possible to make all the parts that adjust the vehicle height every time by the repetitive control unit be the simultaneous target vehicle height attainment type control part, or only the part that performs the vehicle height adjustment at least partly including the last time It is also possible to be a vehicle height attainment type control unit. In any case, at least the final vehicle height adjustment amount is larger than the difference between the set vehicle height and the target vehicle height, and the set vehicle height is always set within the range of the final vehicle height adjustment amount. Made possible.
(20) at least one pressure sensor for detecting a pressure in at least one of the plurality of vehicle height adjusting actuators;
A set vehicle height propriety determination unit that determines whether the set vehicle height is appropriate based on a detection result of the pressure sensor each time the simultaneous target vehicle height attainment type control unit performs vehicle height adjustment for one time (18). Or the vehicle height adjustment system as described in the item (19).
Since the internal pressures of the plurality of vehicle height adjusting actuators influence each other, the suitability of the set vehicle height can be determined by detecting the internal pressure of any of the vehicle height adjusting actuators. However, if a pressure sensor is provided to detect the pressure inside at least one of the vehicle height adjustment actuator that is the last of the supply and discharge allowance of the working fluid and the vehicle height adjustment actuator that is the second from the last, The accuracy of determining the suitability of the set vehicle height is improved.
In the vehicle height adjustment system of this section, it is desirable to provide a detected pressure-dependent set vehicle height changing unit in addition to or instead of the set vehicle height suitability determining unit. For example, when the set vehicle height is inappropriate, the detected pressure-dependent set vehicle height changing unit changes the set vehicle height at the next vehicle height adjustment to an appropriate vehicle height based on the detection result of the pressure sensor. If the pressure difference mitigation type control unit includes a repeat control unit and the set vehicle height at the time of adjusting the vehicle height of the previous round is inappropriate among the multiple iterations, the next cycle The set vehicle height can be changed.
(21) A turning situation in which the set vehicle height is changed based on changes in the left front, right front, left rear, and right rear vehicle heights that occur when the vehicle is turned after the vehicle height change by the vehicle height adjustment system. The vehicle height adjustment system according to any one of items (18) to (20), including a dependence setting vehicle height change unit.
(22) A vehicle that changes the set vehicle height based on at least one of a vehicle height adjustment frequency and an adjustment time for one of the left front, right front, left rear, and right rear vehicle height adjustment actuators. The vehicle height adjustment system according to any one of items (18) to (21), including a vehicle height change unit that is set based on a high adjustment status.
(23) two or more pressure sensors for detecting a pressure in at least one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators;
Item (18) or (18), wherein the two or more pressure sensors include a detected pressure-based set vehicle height changing unit that changes the set vehicle height based on a pressure value detected after the control by the simultaneous target vehicle height attainment type control unit. The vehicle height adjustment system according to item 19).
If the internal pressures of the left and right vehicle height adjustment actuators detected by two or more pressure sensors are uneven even though simultaneous target vehicle height achievement control is performed, the set vehicle height is inappropriate. As you can see, the set vehicle height can be adjusted.
The feature described in the item (21) or (22) is also applicable to the vehicle height adjustment system of this item.
(24) The vehicle height adjusting actuator uses air as a working fluid, and the fluid supply / discharge device supplies air and allows air to be discharged. The vehicle height adjustment system described in Crab.
(25) The vehicle height adjustment actuator includes a hydraulic cylinder that uses liquid as a working fluid, and an accumulator that is connected to the hydraulic cylinder and accumulates the liquid under pressure, and the fluid supply / discharge device supplies the liquid The vehicle height adjustment system according to any one of items (1) to (23), which allows liquid to be discharged.

  Several embodiments of the claimable invention will now be described in detail with reference to the drawings. In addition to the following examples, the claimable invention can be practiced in various modifications based on the knowledge of those skilled in the art, including the aspects described in the above [Aspect of the Invention] section. .

  FIG. 1 shows a vehicle height adjustment system as an embodiment of the claimable invention. In the vehicle height adjustment system, air as a vehicle height adjustment actuator is provided between a vehicle body 22 and a wheel holding device 20 that holds the left front wheel 10, the right front wheel 12, the left rear wheel 14, and the right rear wheel 16, respectively. Springs 34, 36, 38, 40 are provided. In this system, the vehicle height adjusting actuator uses air as the working fluid, and is provided corresponding to the left front wheel 10, the right front wheel 12, the left rear wheel 14, and the right rear wheel 16 as necessary. The air springs 34, 36, 38, 40 are referred to as a left front air spring 34, a right front air spring 36, a left rear air spring 38, and a right rear air spring 40. Further, shock absorbers 44, 46, 48, 50 as damping devices and suspensions (not shown) corresponding to the left front wheel 10, the right front wheel 12, the left rear wheel 14, and the right rear wheel 16 in parallel with the air springs 34 to 40, respectively. A spring is provided.

  In the shock absorbers 44 to 50, the cylinder body 52 is connected to the wheel holding device 20, and the piston rod 54 is connected to the vehicle body 22. In the present embodiment, the air springs 34 to 40 and the shock absorbers 44 to 50 are provided coaxially. The air springs 34 to 40 are air that is provided so as not to move relative to the chamber 60 fixed to the vehicle body 22, the diaphragm 62 fixed to the chamber 60, and the cylinder body 52 of the shock absorbers 44 to 50, respectively. And an air chamber 66 as a fluid pressure chamber. The air piston 64 is moved relative to the chamber 60 with the relative movement in the vertical direction between the wheel holding device 20 and the vehicle body 22.

  When the load applied to the wheels is the same, the vehicle height is higher when the amount of air present in the air chamber 66 is large than when the amount is small. When the amount of air is large, the volume of the air chamber 66 increases when the air pressure, temperature, etc. are the same as compared with the case where the amount of air is small, and the distance between the wheel holding device 20 and the vehicle body 22 increases for that wheel. Vehicle height increases. In the air springs 34 to 40, since the volume of the air chamber 66 is suppressed from increasing in the lateral direction, the shock absorbers 44 to 50 are extended by supplying air, and the wheel holding device 20 and the vehicle body are expanded. The distance between the vehicle 22 and the vehicle height is increased. Further, the upper end surface 68 of the cylinder main body 52 that cannot move relative to the wheel holding device 20 in the vertical direction comes into contact with the vehicle body 22 and the stopper 69 that cannot move relative to the vertical direction, so that the wheel holding device 20 and the vehicle body 22 approach each other. A limit is defined.

  Each of the shock absorbers 44 to 46 has an adjustable damping characteristic, and is controlled by a damping characteristic control motor 70 so that the flow path of the communication path provided in each piston (not shown) of the shock absorbers 44 to 50 is provided. The area is controlled and the attenuation characteristic is controlled.

  The air chambers 66 of the air springs 34 to 40 are connected to an air supply / discharge device 80 as a fluid supply / discharge device via individual flow paths 71, 72, 74, 76 and a common passage 78, respectively. The air supply / discharge device 80 includes an air supply device 82, an exhaust valve 84 as a discharge valve, and an individual control valve device 86. The air supply device 82 includes a compressor 90, a high-pressure tank 92, and the like. The compressor 90 includes a pump 100, a pump motor 102, a discharge valve 104, a suction valve 106, and the like. By operating the pump motor 102, air is sucked from the atmosphere via the filter 108 and the suction valve 106, pressurized, and discharged. It discharges through. In the present embodiment, air discharged from the compressor 90 is stored in the high-pressure tank 92. The pump motor 102 is controlled so that the pressure of the air stored in the high-pressure tank 92 is within the set range. The air pressure in the high-pressure tank 92 is detected by an air pressure sensor 110 as a fluid pressure sensor. A high pressure tank valve 112 is provided between the high pressure tank 92 and the common passage 78. The high-pressure tank valve 112 is a normally closed valve that can be opened and closed by controlling the supply current to the solenoid.

  In the common passage 78, a dryer 120, a flow restriction device 122, and the like are provided. The flow restriction device 122 includes a throttle 126 and a relief valve 128 provided in parallel with each other. The relief valve 128 prevents the flow of air from the air springs 34 to 40 to the compressor 90 side. However, when the pressure on the compressor 90 side becomes higher than the set pressure by the air springs 34 to 40 side, the air spring 34 from the compressor 90 side. The air flow to the 40 side is allowed, and the air is supplied to the air chamber 66. Further, the throttle 126 suppresses the air flow in the common passage 78.

  The exhaust valve 84 is provided between the dryer 120 and the compressor 90 in the common passage 78. In the present system, the exhaust valve 84 is a normally closed electromagnetic on-off valve that is opened and closed by controlling the current supplied to the solenoid. When the exhaust valve 84 is opened, the air springs 34 to 40 are allowed to discharge air from the air chamber 66, and the air discharged from the air chamber 66 is discharged to the atmosphere via the exhaust valve 84, and the vehicle height. Is lowered. The air discharged from the air chamber 66 is discharged to the atmosphere through the throttle 126 and the exhaust valve 84, and a rapid decrease in the pressure of the air chamber 66 is suppressed. In addition, since the air which flowed out from the air chamber 66 is discharged | emitted to air | atmosphere via the dryer 120, the water | moisture content in a dryer can be discharge | released in that case.

  The individual control valve device 86 includes individual control valves 130, 132, 134, 136 provided in the individual passages 71, 72, 74, 76, respectively. These individual control valves 130 to 136 are normally closed valves that can be opened and closed by controlling the supply current to the solenoid, and the supply of air to the air chambers 66 of the air springs 34 to 40 is controlled by opening and closing the individual control valves 130 to 136. And discharge tolerance can be individually controlled.

  As described above, the compressor 90, the exhaust valve 84, the dryer 120, the flow restriction device 122, and the high-pressure tank 92 are provided in series in the common passage 78, and the air chamber 66 is provided on the high-pressure tank 92 side of the air supply / discharge device 80. Connected. An air pressure sensor 110 as a fluid pressure sensor is provided between the high pressure tank 92 side of the air supply / discharge device 80 and the air springs 34 to 40 (individual control valves 130 to 136). It is located in the vicinity of 92 and can be used for detecting the air pressure of the high-pressure tank.

  As shown in FIG. 1, the vehicle height adjustment system is provided with a vehicle height adjustment ECU (electronic control unit) 200 to constitute a control device. The vehicle height adjustment ECU 200 mainly includes a computer including an execution unit 202, a storage unit 204, an input / output unit 206, and the like. An air pressure sensor 110, vehicle height sensors 210 to 216, a vehicle height changeover switch 220, a vehicle speed sensor 222 for detecting the traveling speed of the vehicle, and the like are connected to the input / output unit 206, and an exhaust valve 84 and a high pressure tank valve 112 are connected. The solenoids of the individual control valves 130 to 136, the pump motor 102, the damping characteristic control motor 70, the target vehicle height display lamp 224, etc. are connected via a drive circuit (not shown).

  Vehicle height sensors 210 to 216 are provided for each of the wheels 10, 12, 14, and 16 and detect vehicle heights corresponding to the left front wheels 10 and 12 and the left and right rear wheels 14 and 16, respectively. In this system, the vehicle height sensors 210 to 216 constitute a vehicle height detection device, and vehicle heights corresponding to the left and right front wheels 10 and 12 and the left and right rear wheels 14 and 16 are individually detected.

  The vehicle height changeover switch 220 is a switch operated by the driver, and is operated when the target vehicle height is selected and changed. In the present system, the vehicle height changeover switch 220 is used to instruct the vehicle height to increase and decrease one step at a time, so that the target vehicle height can be set in multiple steps, for example, one of low, normal, and high. Can be switched to. The target vehicle height is a predetermined height set in advance, is set by operating the vehicle height changeover switch 220, and the input target vehicle height is stored in a target vehicle height memory provided in the storage unit 204. Further, when the target vehicle height display lamp 224 is turned on, the selected target vehicle height is displayed. Further, the storage unit 204 stores a main program (not shown), a vehicle height adjustment program at the time of target vehicle height switching shown in a flowchart in FIG.

  In the present vehicle height adjustment system, the vehicle height adjustment is performed such that the vehicle height corresponding to each of the four wheels becomes the target vehicle height set by the occupant. Therefore, when the vehicle height changeover switch 220 is operated and the target vehicle height is changed, the vehicle height corresponding to all four wheels is controlled to be the target vehicle height. Further, after adjusting the vehicle height by switching the target vehicle height, the target vehicle height maintenance control is performed so that the vehicle height corresponding to each of the four wheels is maintained at the target vehicle height. The vehicle height adjustment and target vehicle height maintenance control by switching the target vehicle height is normally performed in a state in which the vehicle height does not change. For example, when the vehicle is stopped, traveling straight, when not braking, This is done when traveling.

  The vehicle height adjustment at the time of the target vehicle height switching is performed in a predetermined order for the vehicle heights corresponding to the left and right front wheels 10 and 12 and the left and right rear wheels 14 and 16, respectively, when raising or lowering the vehicle height. And the vehicle height is increased or decreased in a predetermined order by repeating the increase or decrease a plurality of times. In this system, the vehicle height adjustment is performed simultaneously for the left and right front vehicle heights corresponding to the left and right front wheels 10 and 12, and the left rear vehicle height and the right rear vehicle height corresponding to the left and right rear wheels 14 and 16, respectively. The vehicle height is performed individually one after another. Specifically, the supply of air to the air chamber 66 and the discharge of air from the air chamber 66 are first performed simultaneously on the left front air spring 34 and the right front air 36, and then to the left rear air spring 38. For the right rear air spring 40. Air supply to the air spring 40 corresponding to the right rear wheel 16 that is one of the left and right wheels that can individually detect the vehicle height is performed in the order in which the allowance for exhaustion is last, and a plurality of air supplies in this order are performed. Repeated times. In this embodiment, in order to simplify the description, it is assumed that the vehicle height corresponding to each of the four wheels is the same regardless of which of the low, normal and high is the target vehicle height.

  Further, in this system, when the target vehicle height is increased, the air supply to the air springs 34 to 40 is repeated a plurality of times, and the vehicle height corresponding to the air springs 34 to 40 is controlled to the target vehicle height. Of the air springs 34 to 40, when additional air supply is performed to the right rear air spring 40 which is the last air supply to be performed and the target vehicle height is lowered, the air from the air springs 34 to 40 is used. After the discharge allowance is repeated a plurality of times and the vehicle heights corresponding to the air springs 34 to 40 are respectively controlled to the target vehicle height, additional air discharge allowance is performed on the right rear air spring 40. In this way, in order to distinguish the target vehicle height at each time when the air supply or discharge allowance is repeatedly performed a plurality of times from the target vehicle height that should be referred to as the final target vehicle height, it is referred to as a divided target vehicle height. I will do it.

  When the vehicle height is raised or lowered in the order of the left and right front wheels 10 and 12, the left rear wheel 14 and the right rear wheel 16, the vehicle height can be raised or lowered in several steps up to the target vehicle height. Although the difference in the air pressure between the left and right air springs 38 and 40 is small compared with the case where the pressure is increased or decreased at a time, the difference remains. When the vehicle height corresponding to the left rear wheel 14 is raised, the vehicle height corresponding to the right rear wheel 16 and the left front wheel 10 is also raised, so that the vehicle height corresponding to the right rear wheel 16 is raised to the divided target vehicle height. The vehicle height increase amount due to the operation of the right rear air spring 40 is smaller than the difference between the current vehicle height and the divided target vehicle height at the start of vehicle height adjustment for the entire vehicle. The amount of air supplied to the air chamber 66 of the air spring 40 in order to raise the vehicle height of the right rear wheel 16 to the division target vehicle height is small, and the left rear air spring 38 Since the air springs 38 and 40 of the right side support the load evenly, the pressure in the air chamber 66 of the right rear air spring 40 is correspondingly increased. The pressure of the air spring 66 is lower than this, and the supply of air to the air spring 40 is also reduced from this point, and the air pressure of the left and right rear air springs 38, 40 becomes uneven.

  If air is supplied simultaneously to the left and right front air springs 34 and 36, then the left rear air spring 38 and finally the right rear air spring 40, the difference in internal pressure between the left and right front air springs 34 and 36 will be described. The reduction or reduction of air also appears in the left and right rear air springs 38 and 40, and the reduction in the difference between the left and right rear vehicle heights also appears in the left and right front vehicle heights. Air supply is repeated in this order. For example, a relatively large amount of vehicle height adjustment can be performed while avoiding an increase in the pressure difference and the vehicle height difference both before and after the left and right. However, the pressure difference in the left and right rear air springs 38 and 40 cannot be eliminated, and the vehicle height raising control is repeatedly executed to control each vehicle height to the target vehicle height. Is further supplied to reduce unevenness in the air pressures of the left and right air springs 38 and 40, and to reduce the vehicle body inclination and the like due to a change in the load sharing balance of the wheels.

  When the vehicle height is lowered, the vehicle height is also lowered for the right rear wheel 16 due to the discharge of air from the left rear air spring 38, and accordingly, the amount of air from the right rear air spring 40 is reduced accordingly. Less emissions are required. Further, the discharge of air from the left rear air spring 38 causes the right rear air spring 40 to support a larger load than when the left and right rear air springs 38 and 40 support the load evenly. Therefore, if the air discharge from the left rear air spring 38 is not performed much, the split target vehicle height is not reached, so the amount of air discharged from the left rear air spring 38 increases, and the right rear air spring The amount of air discharged from the spring 40 is reduced. Eventually, the internal pressure of the right rear air spring 40 becomes higher than that of the left rear air spring 38, and pressure unevenness occurs between the left and right rear air springs 38, 40.

  When the vehicle height is lowered, the air is repeatedly discharged in the order of the left and right front air springs 34, 36, the left rear air spring 38, and the right rear air spring 40 in the same manner as when the vehicle height is raised. For example, a relatively large amount of vehicle height adjustment can be performed while avoiding an increase in pressure difference and vehicle height difference both before and after the left and right. The difference cannot be eliminated. Therefore, after the vehicle height reduction control to each divided target vehicle height is repeatedly executed and each vehicle height is controlled to the target vehicle height (final target vehicle height), additional air discharge permission is performed on the right rear air spring 40. As a result, the internal pressure of the right rear air spring 40 is reduced, and the uneven pressure on the left and right sides is reduced. In this system, if the right rear vehicle height is controlled to the final target vehicle height, the supply or discharge allowance of the working fluid is further performed, and the amount of these is increased to additionally supply or discharge the working fluid. That is.

Based on the vehicle height adjustment program at the time of target vehicle height switching shown in FIG. 2, vehicle height adjustment when the target vehicle height is switched will be described.
In step 1 of the vehicle height adjustment program at the time of target vehicle height switching (hereinafter abbreviated as S1, the same applies to other steps), it is determined whether or not the flag F1 is set to 1. The flag F1 is set to 1 to indicate that adjustment for raising the vehicle height is performed. If the flag F1 is reset to 0, the determination result of S1 is NO, S2 is executed, and it is determined whether or not the flag F2 is set to 1. The flag F2 is set to 1 to indicate that control for reducing the vehicle height is performed.

  If the flag F2 is reset to 0, the determination result of S2 is NO, S3 is executed, and it is determined whether or not the target vehicle height can be switched. In this system, this determination is based on the target vehicle height currently selected by the operation of the vehicle height changeover switch 220 and the vehicle height stored in the target vehicle height memory. This is performed depending on whether or not the target vehicle height selected by the operation is different. If the currently selected target vehicle height is the same as the previously selected target vehicle height and the target vehicle height cannot be switched, the determination result in S3 is NO and the execution of the program ends.

  If the currently selected target vehicle height is different from the previously selected target vehicle height and the target vehicle height is switched, the determination result in S3 is YES and S4 is executed to increase the vehicle height. A determination is made whether or not. This determination is made based on whether or not the target vehicle height that is currently stored in the target vehicle height memory is higher than the target vehicle height that is currently selected by operating the vehicle height changeover switch 220. If the vehicle height is to be raised, the determination result in S4 is YES, S5 is executed, and the flag F1 is set.

  Next, S6 is executed, and the repetition control count C1 is set. In order to set the vehicle height to the target vehicle height, the vehicle height is raised in a plurality of times, so the number of times is set. In this system, the repeated control count C <b> 1 is preset according to the vehicle height switching mode and stored in the storage unit 204. In this system, there are three types of target vehicle heights: high, normal, and low, and there are three vehicle height switching modes when raising the vehicle height: low to normal, low to high, and normal to high. The number of times of repeated control C1 is set to a larger number as the vehicle height adjustment amount, which is the difference between the current vehicle height (target vehicle height before switching) and the target vehicle height after switching, is increased. It is made the same between the modes, and the repetitive control count C1 is read based on the vehicle height switching mode. The vehicle height switching mode can be determined from the previously selected target vehicle height stored in the target vehicle height memory and the currently selected target vehicle height.

  In S6, a divided target vehicle height that is a target vehicle height for each control that is repeatedly performed is set. By dividing the vehicle height adjustment amount by the number of times of repeated control C1, one vehicle height adjustment amount is obtained, and by adding the value obtained by multiplying the vehicle height adjustment amount by the vehicle height adjustment number C to the current vehicle height. , C-th division target vehicle height is obtained. The vehicle height adjustment number C is a value that is incremented by 1 from 1 to the number of repeated control times C1, and the C1 divided target vehicle height becomes the target vehicle height selected by operating the vehicle height changeover switch 220.

  In S6, an additional supply amount of air for additional air supply performed after repeated air supply is further read out. In this system, the additional supply amount is set according to the air supply time, and is set in advance according to the vehicle height switching mode and stored in the storage unit 204 in consideration of the vehicle loading conditions and the like. In S6, the additional air supply amount is read in accordance with the vehicle height switching mode. Furthermore, the final target vehicle height, which is the target vehicle height set by operating the vehicle height changeover switch 220, is stored in place of the target vehicle height currently stored in the target vehicle height memory.

  Then, after the count value C of the counter that counts the number of times of repeated control is incremented by 1 in S7, S8 is executed, and the vehicle height adjustment is performed for the left and right front wheels 10,12. The vehicle height adjustment is performed in common for the left and right front wheels 10 and 12, the individual control valves 130 and 132 are opened, and air is simultaneously supplied from the air supply device 82 to the air chambers 66 of the air springs 34 and 36. . Since the vehicle heights corresponding to the left and right front wheels 10 and 12 are individually detected by the vehicle height sensors 210 and 212, the average value of the vehicle heights corresponding to the left and right front wheels 10 and 12 is calculated. It is determined whether or not the vehicle has reached the division target vehicle height set for the first vehicle height increase control. Air is supplied until the average value of the detected vehicle heights of the vehicle height sensors 210 and 212 is raised to the first divided target vehicle height, and then the individual control valves 130 and 132 are closed.

  Next, S9 is executed, and the vehicle height is adjusted for the left rear wheel 14. The individual control valve 134 is opened, and air is supplied from the air supply device 82 to the air chamber 66 of the left rear air spring 38. This supply of air is performed until the vehicle height detected by the vehicle height sensor 214 reaches the first divided target vehicle height, and after rising, the individual control valve 134 is closed. After the vehicle height adjustment for the left rear wheel 14, S10 is executed, and the vehicle height adjustment is performed for the right rear wheel 16. The individual control valve 136 is opened, and air is supplied from the air supply device 82 to the air chamber 66 of the right rear air spring 40. Also for the right rear wheel 16, air is supplied to the air chamber 66 until the vehicle height detected by the vehicle height sensor 216 reaches the first division target vehicle height, and after rising to the first division target vehicle height, The individual control valve 136 is closed. Then, S11 is executed, and it is determined whether or not the count value C is equal to or greater than the number of repeated controls C1 set in S6. This determination is NO until the vehicle height increase control is performed C1 times, and the execution of the program ends.

  Since the flag F1 is set, the next time S1 is executed, the determination result is YES, S2 to S6 are skipped, the steps after S7 are executed, the left and right front wheels 10, 12, left rear wheel 14. In order of the right rear wheel 16, the corresponding vehicle height is raised to the divided target vehicle height set for each time. S1, S7 to S11 are repeatedly executed until the vehicle height increase control count reaches the repeat control count C1. If the vehicle height increase control count reaches the repetitive control count C1 and the vehicle height corresponding to each of the four wheels is raised to the final target vehicle height, the determination result in S11 is YES, S12 is executed, and the count is performed. The value C is reset to 0 and the flag F1 is reset.

  And S13 is performed and additional supply control of air is performed about the air spring in which supply of air was performed last among the four air springs 34-40, and right rear air spring 40 here. The individual control valve 136 is opened, and the additional air supply time read in S6, the air is supplied from the air supply device 82 to the air chamber 66 of the right rear air spring 40, and the set additional air supply After the elapse of time, the individual control valve 136 is closed. As described above, when air is additionally supplied to the right rear air spring 40 which is finally supplied, the internal pressure of the left and right rear air springs 38 and 40 is conventionally changed to that shown in FIG. As shown in FIG. 4 (a), it is unequal as shown in FIG. Since the load shared before and after the vehicle is different, the internal pressures of the left and right front air springs 34 and 36 and the left and right rear air springs 38 and 40 are different.

  When the reduction of the target vehicle height is instructed by the operation of the vehicle height changeover switch 220 by the occupant, the determination result of S4 is NO and S14 is executed, and after the flag F2 is set, S15 is executed. The Even when the target vehicle height is lowered, the discharge of air from the air springs 34 to 40 is performed in a preset order, and is repeatedly performed a plurality of times. Therefore, the repeated control number C2 set according to the vehicle height switching mode is read from the storage unit 204, and the division target vehicle height for each time is set. The number of times of repeated control C2 is set to a larger number as the vehicle height adjustment amount, which is the difference between the current vehicle height (vehicle height before switching) and the vehicle height after switching, is larger. To be the same. Further, an additional air discharge allowable amount, here, an additional air discharge allowable time is read out. There are three types of vehicle height switching modes for reducing the vehicle height: high to normal, high to low, and normal to low. Depending on the vehicle height adjustment amount for each vehicle height switching mode, the number of repeated controls C2 and additional Air discharge allowable time is set and stored. Further, the target vehicle height selected by operating the vehicle height changeover switch 220, and the final target vehicle height is stored in place of the target vehicle height currently stored in the target vehicle height memory.

  Then, after S16 is executed and the count value C of the counter is increased by 1, S17 to S19 are executed, and the vehicle height lowering control is sequentially performed for the left and right front wheels 10, 12, the left rear wheel 14, and the right rear wheel 16. Done. For the left and right front wheels 10 and 12, the individual control valves 130 and 132 are simultaneously opened, the exhaust valve 84 is opened, and the discharge of air from the air chamber 66 of the air springs 12 and 14 is allowed, and is discharged to the atmosphere. As a result, the vehicle height is reduced. When the average value of the vehicle heights corresponding to the left and right front wheels 10 and 12 detected by the vehicle height sensors 210 and 212 reaches the divided target vehicle height for the first control, the individual control valves 130 and 132 are closed, Next, S18 is performed and vehicle height reduction control is performed for the left rear wheel 14. After execution of the vehicle height reduction control for the left rear wheel 14, S19 is executed, and vehicle height reduction control for the right rear wheel 16 is performed.

  S1, S2, and S16 to S20 are repeatedly executed until the vehicle height reduction control is performed C2 times that is the number of times of repeated control. If the vehicle height lowering control is performed C2 times and the vehicle height corresponding to each of the four wheels is lowered to the final target vehicle height, the determination result of S20 becomes YES, S21 is executed, and the count value C Is reset to 0, and the flag F2 is reset. Then, S22 is executed, and additional vehicle height reduction control is performed for the right rear wheel 16. The individual control valve 136 and the exhaust valve 84 are opened, and the discharge of air from the air chamber 66 of the right rear air spring 40 is allowed. After the set time read in S15, the individual control valve 136 and The exhaust valve 84 is closed and the additional control ends.

The maintenance of the vehicle height after the target vehicle height is switched will be described.
After the target vehicle height is switched, the target vehicle height maintenance program shown in FIG. 3 is executed for each of the four wheels so that the vehicle height is maintained at the target vehicle height. The maintenance of the target vehicle height for one of the four wheels, for example, the left front wheel 10 will be described.

  In S31 of the target vehicle height maintenance program, it is determined whether or not the absolute value of the difference between the current vehicle height detected by the vehicle height sensor 210 and the target vehicle height is greater than or equal to a set value. It is determined whether or not the deviation of the current vehicle height from the target vehicle height is large. If the absolute value of the difference is smaller than the set value, the determination result in S31 is NO and the execution of the program ends.

  If the deviation of the current vehicle height from the target vehicle height is large and the absolute value of the difference between the current vehicle height and the target vehicle height is greater than or equal to the set value, the determination result in S31 is YES and S32 is executed, and the current vehicle height is executed. Whether or not is lower than the target vehicle height is determined. If the current vehicle height is lower than the target vehicle height, the determination result in S32 is YES, S33 is executed, and vehicle height increase control is performed. The individual control valve 130 is opened, and air is supplied from the air supply device 82 to the air chamber 66 of the air spring 34. The control of S33 is performed until the absolute value of the difference between the current vehicle height and the target vehicle height becomes smaller than the set value, and when the absolute value of the difference becomes smaller than the set value, the individual control valve 130 is closed, and the vehicle The high climb control ends.

  On the other hand, if the current vehicle height is higher than the target vehicle height, the determination result in S32 is NO, S34 is executed, and the vehicle height is reduced. The individual control valve 130 is opened and the exhaust valve 84 is opened, so that air flows out from the air chamber 66 of the air spring 34 to the atmosphere. The vehicle height reduction control in S34 is performed until the absolute value of the difference between the current vehicle height and the target vehicle height becomes smaller than the set value, and when the absolute value of the difference becomes smaller than the set value, the individual control valve 130 is closed. The vehicle height lowering control is terminated.

  As is apparent from the above description, in the present system, the portion of the vehicle height adjustment ECU 200 that executes S7 to S11 and S16 to S20 constitutes a sequential control unit and a sequential control repetition unit, and a portion that executes S13 and S22. Constitutes an additional control unit, and these constitute a pressure difference reduction type control unit. Moreover, the part which performs S31-S34 of vehicle height adjustment ECU200 comprises the target vehicle height maintenance part.

The non-uniformity in the internal pressure of the vehicle height adjusting actuator for the left and right wheels may be reduced (including cancellation) based on the detection of the internal pressure by the pressure sensor. The embodiment will be described with reference to FIGS. In addition, about the component which performs the same effect | action as the component of the vehicle height adjustment system of the said Example, the same code | symbol is attached | subjected, a corresponding relationship is shown, and description is abbreviate | omitted.
In the vehicle height adjustment system of this embodiment, as shown in FIG. 5, a pressure sensor for detecting the pressure of each air chamber 66 of air springs 38, 40 provided corresponding to each of the left and right rear wheels 14, 16 is provided. 250 and 252 are provided. These pressure sensors 250 and 252 are provided in the individual passages 74 and 76, respectively, and independently detect the pressures of the air chambers 66 of the air springs 38 and 40 and input detection signals to the vehicle height adjustment ECU 200. .

  In the present vehicle height adjustment system, the vehicle height adjustment at the time of target vehicle height switching is performed according to the program shown in FIG. S41 to S52 and S54 to S61 of this program are performed in the same manner as S1 to S12 and S14 to S21 of the vehicle height adjustment program at the time of target vehicle height switching in the above embodiment. For example, when the target vehicle height is increased, the vehicle height increase control is performed for the set number of times, and then S53 is executed. Based on the air pressure detected by the pressure sensors 250 and 252, the left and right Control is performed so that the air pressures of the air springs 38 and 40 of the rear wheels 14 and 16 are equalized.

  When the vehicle height raising control is performed in the order of left front, right front, left rear, and right rear, the internal pressure of the right rear air spring 40 is lower than that of the left rear air spring 38, so the individual control valve 136 is opened. Then, air is supplied from the air supply device 82 to the air chamber 66 of the right rear air spring 40. Then, the pressures of the air chambers 66 of the air springs 38 and 40 detected by the pressure sensors 250 and 252 are read, and it is determined whether or not the absolute value of the difference is equal to or less than a set value. A determination is made as to whether or not the pressures in the air chambers 66 of the air springs 38 and 40 are substantially equal. Air is supplied to the air chamber 66 of the air spring 40 until the absolute value of the difference becomes equal to or less than the set value. When the absolute value of the difference becomes equal to or less than the set value, the individual control valve 136 is closed and the additional air supply ends. Be made.

When the target vehicle height is lowered, the vehicle height lowering control is performed a set number of times, and then S62 is executed, and the air chambers 66 of the air springs 38, 40 detected by the pressure sensors 250, 252 are executed. Based on the pressure, additional air discharge permission control is performed on the right rear wheel 16. When the vehicle height reduction control is performed in the order of left front, right front, left rear, and right rear, the internal pressure of the right rear air spring 40 becomes higher than that of the left rear air spring 38. Therefore, the individual control valve 136 and the exhaust valve 84 are opened, and the discharge of air from the air chamber 66 of the air spring 40 is allowed, and the pressure of each air chamber 66 of the air springs 38 and 40 is controlled. If the absolute value of the difference is less than or equal to the set value, the individual control valve 136 and the exhaust valve 84 are closed, and the additional air discharge allowance control is terminated.
As is apparent from the above description, in the present embodiment, the portions of the vehicle height adjustment ECU 200 that execute S47 to S51 and S56 to S60 constitute a sequential control unit and a sequential control repetition unit, and execute S53 and S62. The parts constitute an additional control unit, and these constitute a pressure difference reduction type control unit.

  The predetermined amount of additional supply of working fluid and the amount of additional discharge allowance may be varied. The embodiment will be described with reference to FIGS. The vehicle height adjustment system is configured in the same manner as the vehicle height adjustment system shown in FIG. 1 of the above embodiment except for the portion related to the vehicle height adjustment control, and the same reference numerals are given to the components having the same functions. Is used for explanation.

  In the present vehicle height adjustment system, the target vehicle height is switched, for example, in the same manner as the vehicle height adjustment system of the embodiment shown in FIGS. 1 to 4, and the vehicle height corresponding to each of the four wheels is changed to the target vehicle height. After the change, additional supply of air to the right rear air spring 40 and allowance for additional discharge reduce the uneven pressure inside the right and left rear air springs 38, 40 both when the vehicle height rises and when the vehicle height falls. To be done. Further, the additional supply amount of air as the working fluid and the additional discharge allowance amount are inappropriate based on the history of the target vehicle height maintenance adjustment for maintaining the vehicle height corresponding to each of the four wheels at the target vehicle height. Will be changed. Therefore, when the target vehicle height maintenance adjustment is performed, the content of the maintenance adjustment is stored with time in the target vehicle height maintenance adjustment history memory in association with the switching mode of the target vehicle height. The target vehicle height maintenance adjustment history memory is provided with a memory that stores a maintenance adjustment history when the target vehicle height is switched upward, and a memory that stores a maintenance adjustment history when the target vehicle height is switched. The switching mode of the target vehicle height is which target vehicle height is changed to which target vehicle height, such as switching from low to normal. The content of the maintenance adjustment is, for example, the wheel on which the maintenance adjustment has been performed and the time required for the adjustment. The direction of maintenance adjustment, that is, whether the vehicle height is raised or lowered, is performed in the same direction for the same wheel with respect to one switching of the target vehicle height. In addition, when a maintenance adjustment is performed for a plurality of wheels or a maintenance adjustment is performed a plurality of times for the same wheel in response to a single switching of the target vehicle height, they are all associated with a switching mode of the target vehicle height. And stored in the target vehicle height maintenance history memory.

  In this system, when there is a wheel whose target vehicle height maintenance adjustment rate is equal to or higher than the set rate, the additional air supply amount or the additional discharge allowable amount is changed. The maintenance adjustment rate is a ratio of the number of switching operations for which maintenance adjustment has been performed among the number of times of switching of the target vehicle height. When the maintenance adjustment is performed once or more for the same wheel for one change of the target vehicle height, it is counted that the maintenance adjustment is performed once, and the maintenance adjustment is performed at least once for a plurality of wheels. When it is performed, it is counted that the maintenance adjustment is performed once for each wheel. It can be determined from the contents of the target vehicle height maintenance adjustment history memory whether or not the maintenance adjustment has been performed for the change of the target vehicle height.

  In order to change the additional supply amount of air or the allowable additional discharge amount, the vehicle height adjustment program at the time of target vehicle height switching is configured as shown in FIG. This program is configured in substantially the same manner as the vehicle height adjustment program at the time of target vehicle height switching shown in FIG. 2 of the above-described embodiment, and in S76 and S85, as in S6 and S15, respectively, the number of repeated control operations C1 and C2 The target vehicle height switching mode is stored in the target vehicle height switching mode memory provided in the storage unit 204. Further, in S83, in addition to performing additional air supply control to the right rear air spring 40, the number of vehicle height increase switching is counted. The count value of the vehicle height increase switching number counter provided in the storage unit 204 is incremented by 1, and the number of times of switching to the side where the target vehicle height is increased is counted. In S83, the travel distance of the vehicle is further read and stored in the travel distance memory at the time of target vehicle height switching provided in the storage unit 204. The travel distance at the end of the vehicle height adjustment is stored. A measured value of a travel distance measuring device (not shown) connected to the vehicle height adjustment ECU 200 is read to obtain the travel distance of the vehicle. In S92, in addition to performing additional air discharge allowance control on the right rear air spring 40, the count value of the vehicle height lowering switching number counter provided in the storage unit 204 is incremented by 1, and the target vehicle height is increased. The number of times of switching to the lower side is counted, and the travel distance of the vehicle is stored in the travel distance memory when the target vehicle height is switched.

The target vehicle height maintenance control will be described based on the programs shown in FIGS. This program is executed for each of the four wheels.
In S101 of the target vehicle height maintenance program shown in FIG. 8, it is determined whether or not the target vehicle height has been switched from low to normal. This determination is made based on the target vehicle height switching mode stored in the target vehicle height switching mode memory. If the vehicle is switched from low to normal, the determination result in S101 is YES and S102 is executed. After the target vehicle height is switched, it is determined whether or not the vehicle has traveled more than the set distance. This determination is made based on whether or not the difference between the travel distance of the vehicle when S102 is executed and the travel distance stored in the travel distance memory at the time of target vehicle height switching is greater than or equal to the set difference. The determination result in S102 is NO until the difference becomes equal to or greater than the set difference, and the execution of the program ends.

  If the vehicle travels more than the set distance after the target vehicle height is switched, the determination result in S102 is YES and the steps after S103 are executed, so that the vehicle height is maintained at the target vehicle height. S103 to S106 are executed in the same manner as S31 to S34 of the vehicle height adjustment maintenance program shown in FIG. For example, if the absolute value of the difference between the target vehicle height and the current vehicle height is greater than or equal to the set value and the current vehicle height is lower than the target vehicle height, S105 is executed to perform vehicle height increase control, and the current vehicle height is controlled. The height is raised. Then, S107 is executed, and the maintenance adjustment contents are stored in the target vehicle height maintenance adjustment history memory at the time of the target vehicle height increase side switching in association with the switching mode of the target vehicle height. The time required for the maintenance adjustment is measured when the control is executed in S105 or S106.

  When the target vehicle height is switched from normal to high, the determination result of S101 is NO, the determination result of S108 is YES, S109 to S114 are executed in the same manner as S102 to 107, and if necessary, the vehicle High maintenance adjustment control is performed. If the target vehicle height is switched from low to high, the determination results in S101 and S108 are NO, the determination result in S115 is YES, and S116 to S121 are executed in the same manner as S102 to S107. Further, at the time of switching to the side for reducing the target vehicle height, as shown in FIG. 9, when the target vehicle height is switched from high to normal, from normal to low, or from high to low, S123 to S128, respectively. , S130 to S135 and S136 to S141 are executed so that the current vehicle height is maintained at the target vehicle height, and the maintenance adjustment content is associated with the target vehicle height switching mode and the target vehicle height lowering side switching target. It is stored in the vehicle height maintenance adjustment history memory.

The change of the additional adjustment amount, that is, the change of the additional air supply amount and the additional air discharge allowable amount is performed according to the program shown in FIG.
When the target vehicle height is switched to the side where the vehicle height is increased, and the additional air supply amount is changed for the vehicle height switching, first, the additional air supply amount is increased. Although a change is necessary, if the vehicle height maintenance adjustment rate is reduced, it is estimated that the pressure non-uniformity has been improved, and the additional air supply amount is increased by a smaller amount than the previous time. Further, if the pressure non-uniformity is not improved, it is estimated that the direction of change of the additional air supply amount is reverse, and the additional air supply amount is twice the increase amount of the additional air supply amount. Reduced. Thereby, the pressure non-uniformity is improved, but if the change is still necessary, the additional air supply amount is decreased by an amount smaller than the increase amount of the additional air supply amount.
If the vehicle height corresponding to one wheel is adjusted, the vehicle height corresponding to the other wheels also changes, so that the pre-set additional air supply amount is inappropriate, causing pressure non-uniformity, thereby causing the target vehicle If the vehicle height deviates from the height, it is appropriate to increase or decrease the additional air supply amount so as not to cause the deviation. I do not know easily. Therefore, first, the additional air supply amount is increased, and further increased or decreased depending on the result.
The same applies to the case where the target vehicle height is switched to the side where the vehicle height is lowered, and additional air discharge allowance is performed for the vehicle height switch, and the change is first made by increasing the additional air discharge allowance. Is done from. In this embodiment, the change amount of the additional air supply amount and the change amount of the additional discharge allowance amount are the same regardless of the vehicle height switching mode. You may make it differ according to an aspect.

  First, in S151, it is determined whether or not the target vehicle height has been switched to the rising side a set number of times. This determination is made based on whether or not the count value of the vehicle height increase switching number counter is a set number. If it has not been executed for the set number of times, the determination result in S151 is NO and S164 is executed to determine whether or not switching to the target vehicle height lowering side has been performed for the set number of times. This determination is made based on whether or not the count value of the vehicle height decrease switching number counter is a set number. If it has not been executed the set number of times, the determination result in S164 is NO and the execution of the program ends.

  If switching for increasing the target vehicle height is performed a set number of times, the determination result in S151 is YES, S152 is executed, and it is determined whether or not there is a wheel whose vehicle height maintenance adjustment rate is equal to or higher than the set rate. Done. Based on the contents of the target vehicle height maintenance adjustment history memory at the time of target vehicle height increase side switching, of the set number of vehicle height increase switching, the wheel for which vehicle height maintenance adjustment has been performed is performed for switching more than the preset number of times. If not, the determination result in S152 is NO, S163 is executed, the vehicle height increase switching number counter is reset to 0, and the vehicle height increase side switching target vehicle height maintenance adjustment history The history stored in the memory is deleted. This setting rate is set low if it is easy to change the additional air supply amount, and is set high if it is difficult to change it.

  If there is a wheel whose vehicle height maintenance adjustment rate is equal to or higher than the set rate, the determination result in S152 is YES, the steps after S153 are executed, and the additional supply amount of air is changed. In S153, when the target vehicle height is switched to the rising side the previous number of times, there is a wheel whose vehicle height adjustment maintenance rate is equal to or higher than the set rate, and additional air supply when the amount is changed. A determination is made whether the amount has been increased. This determination is made based on whether or not the flag FU is set. The flag FU is set in the step of increasing the additional air supply amount, and indicates that the additional air supply amount has been increased. If the additional air supply amount was not increased last time and the flag FU was reset, whether the determination result of S153 was NO and S154 was executed, was the additional air supply amount decreased the last time? A determination is made whether or not. This determination is made based on whether or not the flag FD is set. The flag FD is set in the step of reducing the additional air supply amount, and indicates that the additional air supply amount has been reduced.

  If the additional air supply amount has not been reduced at the time of the previous steps after S153, the determination result in S154 is NO, S155 is executed, and the additional air supply amount is increased. In the present embodiment, the additional air supply amount is set based on the vehicle height maintenance adjustment time. The average value of the adjustment time required for maintaining the vehicle height is calculated at least once for the wheel having the highest vehicle height maintenance adjustment rate. The longer the average adjustment time is, the more additional air supply amount is set. For example, the average adjustment required time for maintaining the vehicle height is divided into a plurality of stages, and additional supply amount change data in which the increase amount of the additional supply amount of air is associated with each stage is preset and stored in the storage unit 204. It has been. In this system, the additional air supply amount is set according to time, the change amount is also set according to time, and the increase amount is added to the additional supply amount of air stored in the storage unit 204 and changed. The additional supply amount of air is set according to the vehicle height switching mode, and each additional supply amount of air is increased and changed. The same applies to the case where the additional supply amount of air is reduced. The increase amount is stored in the change history memory as a change history. In S155, the flag FU is also set. Then, S156 is executed, the vehicle height increase switching number counter is reset, and the vehicle height increase side switching target vehicle height maintenance adjustment history is deleted. The highest vehicle height maintenance adjustment rate is stored in the change history memory and left.

  If the additional air supply amount is increased, the increased amount of air is additionally supplied to the right rear air spring 16 when the next switching to increase the target vehicle height is performed. After that, if switching for raising the target vehicle height is performed a set number of times, the determination result in S151 is YES and S152 is performed. If the vehicle height maintenance adjustment becomes unnecessary due to the increase in the additional supply amount of air, or if the vehicle height maintenance adjustment is performed, if the adjustment rate is lower than the set rate, the determination result in S152 is NO and S163 is executed. The

  Even if the additional supply amount of air is increased, if there is a wheel whose vehicle height maintenance adjustment rate exceeds the set rate, the determination result in S152 is YES and S153 is executed. Since the additional supply amount of air was increased last time, the flag FU is set, the determination result in S153 is YES, S157 is executed, and uneven pressure in the air springs 38, 40 on the left and right is improved. A determination is made whether or not the This determination is made based on whether or not the highest vehicle height maintenance adjustment rate is lower than the highest vehicle height maintenance adjustment rate last time. It does not matter whether the wheel having the highest vehicle height maintenance adjustment rate is the same as the previous time and this time. If the vehicle height maintenance adjustment rate is lower than the previous time, the determination result in S157 is YES, S158 is executed, and the additional supply amount of air is increased. The decrease in the vehicle height maintenance adjustment rate means that the increase in the additional supply amount of air is correct as a direction to improve the left and right pressure unevenness, but the vehicle height maintenance adjustment rate is still higher than the set rate, Again, the additional supply of air is increased. However, since the increase in the additional supply amount is the second time, the increase amount is made smaller than the first time. The increase amount is set based on an average value of at least one maintenance adjustment time performed on the wheel having the highest vehicle height maintenance adjustment rate. When this increase amount is larger than the first increase amount, Is reduced. For example, the first increase amount is an amount corresponding to a decrease in the vehicle height maintenance adjustment rate, or an amount reduced. The set increase amount is added to the additional supply amount of air stored in the storage unit 204, and the additional supply amount is changed. Further, the increase amount is stored in the storage unit 204 as a change history. Then, S156 is executed and the execution of the program ends. In this way, if the additional supply amount of air is increased again, and the uneven pressure on the left and right is eliminated, the determination result of S152 becomes NO and S163 is executed, and the additional supply amount of air is changed. It will not be done.

  On the other hand, if the additional supply amount of air is increased, but the pressure unevenness of the left and right air springs 38 and 40 is not improved and the maintenance adjustment rate does not change or increases, the determination result of S157 is NO. S159 is executed, and the additional supply amount of air stored in the storage unit 204 is decreased. The fact that the maintenance adjustment rate has not decreased means that the direction of change of the additional air supply amount is wrong, and conversely, the additional air supply amount is decreased. The amount of decrease is, for example, twice the amount of increase in the additional supply amount performed immediately before. By canceling the previously increased amount, the additional supply amount is decreased, and the decrease amount is stored in the storage unit 204 as a change history. In addition, the flag FU is reset and the flag FD is set to indicate that the additional supply amount is decreased. Then, S156 is executed and the execution of the program ends.

  If the vehicle height maintenance adjustment rate decreases due to the decrease in the additional supply amount and becomes smaller than the set rate, the determination result in S152 becomes NO when the target vehicle height is subsequently switched to the rising side for the set number of times. . Further, if the vehicle height maintenance adjustment rate is equal to or higher than the set rate, but has decreased from the previous time, the determination result of S151 and S152 is YES, the determination result of S153 is NO, and the determination result of S154 and S160 is YES. S161 is executed, and the additional supply amount of air is decreased again. This decrease amount is set to an amount smaller than the increase amount of the additional air supply amount in S155. If the pressure unevenness of the left and right rear air springs 38, 40 is thereby reduced, the next time S152 is executed, the determination result is NO and S163 is executed.

  On the other hand, if the pressure non-uniformity is not improved even if the additional supply amount of air is decreased, the determination result in S160 is NO and S162 is executed, so that the additional supply amount is increased. Here, since the additional supply amount of air is once increased, then decreased, and then increased again, the increase amount is, for example, smaller than the initial increase amount before the decrease.

  The case where the target vehicle height is switched for the set number of times on the side for increasing the target vehicle height has been described above. However, when the set number of times is performed on the side for decreasing the target vehicle height, the determination result of S164 is performed. Becomes YES and the steps from S165 onward are executed. In this case, if there is a wheel whose vehicle height maintenance adjustment rate is equal to or higher than the set rate, the additional air discharge allowance is changed. In the same way as when the target vehicle height is switched to the side where the target vehicle height is increased, this change is made by first increasing the allowable additional discharge amount and further increasing or decreasing it according to the result. Is done.

  As is clear from the above description, in this embodiment, the portion of the vehicle height adjustment ECU 200 that executes S152 and S165 is based on the vehicle height adjustment frequency for one of the four air springs 34 to 40. An adjustment frequency-dependent adequacy determination unit, which is a vehicle height adjustment status-dependent adequacy determination unit that determines whether or not the additional supply amount of air and the allowable additional discharge amount are appropriate, is configured. S158, S159, S161, S162, S171, S172, S174 The portion that executes S175 changes the vehicle height adjustment status-dependent amount that changes the additional supply amount of air and the allowable additional discharge amount based on the time required for adjusting the vehicle height for one of the four air springs 34-40. It constitutes a part for adjusting the amount of time required for adjustment.

Changes in at least one of the additional amount of working fluid supply and the additional discharge allowance may be made based on changes in the vehicle heights of the left front, right front, left rear, and right rear that occur during driving. Good. The embodiment will be described with reference to FIGS.
In the present system, the vehicle height adjustment at the time of target vehicle height switching is performed, for example, according to a program configured similarly to the vehicle height adjustment program at the time of target vehicle height switching shown in FIG. When the additional air supply control is executed for the rear air spring 40, the target vehicle height increase switch flag is set and the target vehicle height decrease switch flag is reset, and the travel distance of the vehicle at the end of the additional air supply control is performed. Is stored in the mileage memory. In S202, which is a step corresponding to S22, when additional air discharge allowance control is executed for the right rear air spring 40, the target vehicle height decrease switch flag is set and the target vehicle height increase switch flag is reset. In addition, the vehicle travel distance at the end of the additional air discharge allowance control is stored in the travel distance memory.

  Then, in S211 of the additional adjustment amount changing program shown in FIG. 12, it is determined whether or not the vehicle height adjustment for increasing the target vehicle height has been performed. In this determination, the target vehicle height increase switching flag is set. It is done based on whether or not. If switching to increase the target vehicle height has not been performed and the target vehicle height increase switching flag has not been set, the determination result in S211 is NO, S222 is executed, and the target vehicle height decrease switching flag is set. A determination is made whether or not. If switching to lower the target vehicle height has not been performed, the determination result in S222 is NO and the execution of the program ends.

  If the vehicle height adjustment for increasing the target vehicle height is performed, the determination result in S211 is YES and S212 is executed. After the vehicle height adjustment, it is determined whether or not the vehicle has traveled more than the set distance. Is called. This determination is made based on the difference between the travel distance of the vehicle at the time of execution of S212 and the travel distance at the end of the vehicle height adjustment and at the time of the execution of S193 until the difference becomes equal to or greater than the set distance. The determination result is NO and the execution of the program ends.

  After the vehicle height adjustment by switching the target vehicle height, if the vehicle has traveled more than the set distance, the determination result in S212 is YES and S213 is executed to determine whether the set time has elapsed. This set time is set to a short time. Until the set time elapses, the determination result in S213 is NO and the execution of the program ends. If the set time elapses, the determination result in S213 is YES and S214 is executed, and the vehicle height detected by the vehicle height sensors 210 to 216 is read for each of the four wheels. Then, S215 is executed, and it is determined whether or not the posture of the vehicle is normal based on the vehicle height read in S214. For example, if at least one of the vehicle heights corresponding to four wheels has an absolute value that exceeds the set difference and is abnormally high or abnormally low, the vehicle is tilted. It is assumed that the vehicle posture is abnormal. If the vehicle posture is abnormal, the determination result in S215 is NO and S216 is executed, and occurrence of the posture abnormality is counted by the vehicle posture abnormality number counter. In addition, the timer for measuring the elapse of the set time in S213 is reset to 0, and S217 is executed. If the vehicle heights corresponding to the four wheels are all within the set range with respect to the target vehicle height and the vehicle posture is normal, the determination result in S215 is YES and S217 is executed. If the setting difference for determining whether or not the vehicle posture is normal is set small, it is easy to determine that the vehicle posture is abnormal, and if it is set large, it is difficult to determine abnormal. Therefore, the setting difference is set depending on whether or not the vehicle posture is easily determined to be abnormal.

  In S217, the count value C of the vehicle posture determination number counter is incremented by 1, and after the vehicle posture determination number is counted, S218 is executed to determine whether or not the count value C is equal to or greater than the set number C3. Done. This determination is NO until the vehicle attitude determination is performed C3 times, and the execution of the program ends. Each time the set time elapses, the vehicle heights corresponding to the four wheels are read to determine whether or not the vehicle posture is normal. If there is an abnormality in the posture, the occurrence of the posture abnormality is counted. (S213-S216).

  If the vehicle attitude determination is performed C3 times, the determination result in S218 is YES, S219 is executed, and it is determined whether or not the additional supply amount of air is appropriate. This determination is performed based on, for example, whether or not the rate of the number of times that the posture of the vehicle is determined to be abnormal with respect to the set number of times C3 is greater than or equal to the set rate. The supply amount is appropriate, the determination result in S219 is YES, S220 is executed, the target vehicle height increase switching flag is reset, and the vehicle posture determination number counter and the vehicle posture abnormality number counter are reset to zero. Execution of the program ends.

  On the other hand, if the vehicle posture abnormality occurrence rate during traveling is equal to or greater than the set rate, the additional air supply amount is inappropriate, the determination result in S219 is NO, S221 is executed, and the additional air supply amount is Be changed. If this set rate is set high, it is difficult to determine that the additional supply amount of air is inappropriate, and if it is set low, it is likely to be determined inappropriate. Therefore, if the vehicle posture abnormality due to sudden reasons such as changes in vehicle height due to unevenness of the road surface is eliminated and the additional supply amount of air is not easily performed, the setting rate is increased, If the vehicle attitude is abnormal even a little, the set rate is lowered if the additional supply amount of air is to be performed. This setting rate and the setting difference for determining whether or not the vehicle posture in S215 is normal are related to each other. For example, if the setting difference is set to be small and the vehicle posture is easily determined to be abnormal. By increasing the setting rate, if there is a possibility that the vehicle posture is abnormal, it will be abnormal, but the additional supply amount of air will not be changed excessively, but should be performed as necessary Is possible.

  The change of the additional air supply amount in S221 is performed, for example, in the same manner as when changing the amount based on the change maintenance adjustment history. First, the additional air supply amount is increased, and the additional air supply time is increased. Be made. This increase amount is set in advance according to the abnormality occurrence rate, for example, and is increased as the abnormality occurrence rate is higher. In the present system, the increase amount is constant regardless of the vehicle height switching mode, and the additional supply amount of air stored in the storage unit 204 is increased by the increase amount.

  In S221, the change mode of the additional air supply time is also stored in the change history memory. For example, the abnormality occurrence rate (number of abnormality occurrences), the change mode (increase or decrease) of the additional supply amount of air, and the change amount (increase or decrease) are stored. Then, when the vehicle height adjustment for increasing the target vehicle height is performed next, when the abnormality occurrence rate becomes high again, the additional supply amount of air is changed while referring to the change history. For example, if the abnormality occurrence rate is equal to or higher than the set rate, but is lower than the previous time, the additional supply amount of air can be further increased. At this time, since the abnormality occurrence rate is lower than the previous time, the increase amount is made smaller than the previous time.

  On the other hand, if the abnormality occurrence rate is increased, the increase in the additional air supply amount is incorrect, and the additional air supply amount is decreased. For example, the next additional air supply amount is an amount that is twice as much as the previous additional air supply amount or a reduced amount. As a result, after the vehicle height adjustment for increasing the target vehicle height is performed next, the abnormality occurrence rate is equal to or higher than the set rate, but if it is lower than the previous time, the additional air supply amount is further reduced. In this way, by changing the additional air supply amount according to the attitude of the vehicle, the pressure unevenness of the left and right air springs is reduced, and the abnormality occurrence rate becomes lower than the set rate, and the additional air supply amount is changed. Will no longer be performed.

When the vehicle height adjustment for decreasing the target vehicle height is performed, the determination result in S211 is NO, the determination result in S222 is YES, and the steps after S223 are executed to perform the vehicle height adjustment to increase the target vehicle height. As in the case where the vehicle is adjusted, after the vehicle height is adjusted, a determination is made whether or not the vehicle posture is normal based on the vehicle height of each of the four wheels while the vehicle has traveled more than the set distance. If the abnormality occurrence rate is equal to or higher than the set rate, the discharge allowable amount of air from the right rear air spring 40 is changed. This change is also performed, for example, by changing the air discharge allowable amount and changing the change amount and the change direction based on the result, similarly to the change of the additional air supply amount.
As is apparent from the above description, in this system, the part that executes S219 and S230 of the vehicle height adjustment ECU 200 constitutes a running vehicle posture-dependent suitability determining unit, and the part that executes S221 and S232 is a running vehicle. It constitutes a posture-dependent amount changing unit.

The change in at least one of the amount of additional supply of working fluid and the amount of additional discharge allowance is the vehicle height at the front left, front right, left rear and right rear that occurs when the vehicle turns after the end of the vehicle height change. May be performed based on the change of The embodiment will be described with reference to FIG.
In this system, the vehicle height adjustment at the time of target vehicle height switching is performed by a program configured in the same manner as the program shown in FIG. However, the vehicle height travel distance is not stored in the steps corresponding to S193 and S202. In the additional adjustment amount changing program shown in FIG. 13, if the vehicle height adjustment for increasing the target vehicle height is performed and the target vehicle height increase switching flag is set, the determination result in S241 is YES and S242 is executed. Then, it is determined whether or not the vehicle is in a steady turn. This determination is performed based on, for example, whether or not the yaw rate detected by the yaw rate sensor is equal to or greater than a set value. The set value is set to such a magnitude that rolling of the vehicle in which a large turning state (side force generation state) is detected to some extent and the vehicle roll posture is correctly determined is generated. . Although not shown, the yaw rate sensor is connected to the vehicle height adjustment ECU 200, detects the yaw rate, and inputs it to the vehicle height adjustment ECU 200. If the vehicle is not in a steady turn, the determination result in S242 is NO and execution of the program ends.

  If the vehicle is in a steady turn, the determination result in S242 is YES, S243 is executed, and the vehicle height corresponding to each of the four wheels detected by the vehicle height sensors 210-216 is read. Then, S244 is executed, and it is determined whether or not the roll posture of the vehicle at the time of turning is normal based on the front left, right front, left rear, and right rear vehicle heights. At the time of turning, the vehicle body is tilted due to the load movement and assumes a rolled posture. Therefore, in S244, it is determined whether or not the vehicle is normally rolled. This determination is made based on the ratio of the difference between the front right vehicle height and the rear right vehicle height with respect to the rolling amount of the vehicle body.If this ratio is within the set range, the roll posture is normal and the vehicle is out of range. If there is, it is considered abnormal. If the setting range is set narrow, it is easy to determine that the roll posture is abnormal, and if it is set wide, it is difficult to determine abnormal. Accordingly, the setting range is set depending on whether the roll posture is easily determined to be abnormal. The rolling amount of the vehicle body is obtained, for example, based on the difference between the average value of the left front vehicle height and the left rear vehicle height and the average value of the right front vehicle height and the right rear vehicle height, or obtained based on the lateral acceleration. It is done. If the roll posture of the vehicle is abnormal, the determination result in S244 is NO and S245 is executed. After the turning direction, the content of the abnormality, and the ratio are stored in the vehicle posture abnormality memory, S246 is executed. . If the roll posture of the vehicle is normal, the determination result in S244 is YES, S245 is skipped, and S246 is executed.

  In S246, the count value of the counter is incremented by 1, and the number of times of vehicle turning performed after the vehicle ascent adjustment is counted. Then, S247 is executed, and the number of times of vehicle turning when the target vehicle height is increased is switched over the set number of times C4. It is determined whether or not. The determination result in S247 is NO until the number of vehicle turns reaches the set number C4, and the execution of the program ends.

  If the number of vehicle turns reaches the set number C4, the determination result in S247 is YES, S248 is executed, and it is determined whether the additional supply amount of air is appropriate. In this system, this determination is made based on whether or not the ratio of the number of occurrences of the vehicle posture abnormality with respect to the number of vehicle turns is equal to or higher than the set rate. The number of occurrences of vehicle posture abnormality can be determined based on the contents stored in the vehicle posture abnormality memory. In S245, the number of occurrences of abnormality may be counted by a counter. If the abnormality occurrence rate is lower than the set rate, the additional supply amount of air is appropriate, the determination result in S248 is YES, S249 is executed, the target vehicle height increase switching flag and counter are reset, and the vehicle attitude Abnormal memory is cleared. As a result, the determination result in S241 is NO and the additional supply amount of air is not changed until the vehicle height adjustment for increasing the target vehicle height is performed next time. On the other hand, if the abnormality occurrence rate is equal to or higher than the set rate, the determination result in S248 is NO, S250 is executed, and the additional air supply amount is changed.

  The setting rate for determining whether or not the additional air supply amount is appropriate is less likely to be determined inappropriate if it is set high, and more likely to be determined inappropriate if it is set low. Therefore, when the roll posture is abnormal due to sudden reasons such as the inclination of the vehicle body due to road surface unevenness, or when the judgment result of whether the vehicle roll posture is normal or not changes frequently, air is added If the supply amount is not easily performed, the setting rate is increased. If the roll posture is even abnormal even a little, if the additional supply amount of air is to be performed, the setting rate is Lowered. This setting rate and the setting range for determining whether or not the vehicle roll posture is normal in S244 are related to each other. For example, the setting range is set to be narrow and the vehicle roll posture is easily determined to be abnormal. If there is a possibility that the vehicle roll posture may be abnormal by increasing the setting rate, the additional supply amount of air is not excessively performed but is performed as necessary. It becomes possible to do so.

  The change in the additional air supply amount is performed based on the abnormality content stored in the vehicle posture abnormality memory.For example, an abnormality has occurred during a left turn, and the right front vehicle height and the right rear vehicle height However, if the right rear vehicle height is higher, it is estimated that the pressure of the right rear air spring 40 is high, and the additional air supply amount is reduced. In a state where an abnormality occurs when turning left, an abnormality also occurs when turning right, and the front left vehicle height is usually higher than the left rear vehicle height. Further, when an abnormality occurs when turning left and the front right vehicle height is higher, the pressure of the right rear air spring 40 is estimated to be low, and the additional air supply amount is increased. The change amount of the additional air supply amount is set based on the ratio of the difference between the right front vehicle height and the right rear vehicle height with respect to the rolling amount of the vehicle body. Here, the average value of each ratio in the case of at least one case where the roll posture of the vehicle is determined to be abnormal in S244 is obtained, and the amount of change is increased as the average value increases. When the air supply amount is increased, the change amount is added to the current air supply amount, and when the air supply amount is decreased, the change amount is subtracted from the current air supply amount. Then, S249 is executed and the execution of the program ends. The amount of change in the additional air supply amount is created, for example, such that the average value of the ratio is divided into a plurality of stages, and the amount of change increases as the average value of the ratio increases, and is associated with the stage of the average value of the ratio Thus, additional air supply amount change amount data is created. The amount of change is common to the three types of switching modes of the target vehicle height. However, the amount of change may vary depending on the target vehicle height switching mode. The change amount of the set vehicle height may be obtained by calculation based on the average value of the ratios.

  If the vehicle height adjustment for reducing the target vehicle height is performed, the target vehicle height decrease switching flag is set, so that the determination result of S241 is NO, the determination result of S251 is YES, and steps S252 and below are executed, It is determined whether or not an abnormality has occurred in the roll posture during steady turning of the vehicle, and the additional air discharge allowance is changed when the abnormality occurrence rate is high. For example, if the right rear vehicle height is higher than the right front vehicle height, it is estimated that the pressure of the right rear air spring 40 is high, and the additional discharge allowable amount of air is increased. Further, if the right rear vehicle height is lower than the right front vehicle height, the allowable additional discharge amount of air is reduced. Also in this case, the additional discharge allowable amount of air is acquired based on the average value of the ratio.

  In the present system, the part for executing S242 and S252 of the vehicle height adjustment ECU 200 and the yaw rate sensor constitute a vehicle steady turning detection part, and the part for executing S248 and S258 constitutes a turning situation dependence propriety judging part, S250, The part which performs S260 comprises the turning condition dependence amount change part. The steady turning of the vehicle may be detected based on the lateral acceleration detected by the lateral acceleration sensor instead of the yaw rate sensor.

  Note that the determination in S248 of the additional adjustment amount changing program shown in FIG. 13 may be omitted. In S244, the setting range for determining whether or not the vehicle roll posture is normal is widened, and the vehicle roll posture abnormality determination is strictly performed. If it is determined that the additional supply amount of air is inappropriate, the change may be made.

  The predetermined order is that the supply of the working fluid to the vehicle height adjustment actuator corresponding to either the left wheel or the right wheel of either the left or right front wheel or the left or right rear wheel is the last. The order in which the working fluid is supplied from the last to the vehicle height adjustment actuator corresponding to the other of the right wheel and the right wheel, and either the left wheel or the right wheel of either the left or right front wheel or the left or right rear wheel The order of discharge of the working fluid from the vehicle height adjusting actuator corresponding to one is the last, and the discharge of the working fluid from the vehicle height adjusting actuator corresponding to the other of the left wheel and the right wheel is the second from the last. In the case of at least one of the above, the pressure unevenness of the left and right vehicle height adjustment actuators is that the vehicle height adjustment actuator in which at least one of the supply and discharge allowance of the working fluid is performed second from the last among the four wheels. The vehicle height corresponding to the eta, may be is reduced (including eliminating) by adjusting intentionally set vehicle height that is different from the target vehicle height.

In this case, when switching to a higher target vehicle height, when the vehicle height corresponding to the vehicle height adjustment actuator to which the working fluid is supplied last is raised to the target vehicle height, the interior of the vehicle height adjustment actuator The working fluid is such that the vehicle height corresponding to the vehicle height adjusting actuator for which the working fluid is supplied second from the last is the target pressure, and the vehicle height corresponding to the last vehicle height adjusting actuator is the pressure. As a result, the higher operating pressure is the additional supply of the working fluid, and when lowering the vehicle height, the discharge of the working fluid is allowed last. When the vehicle height corresponding to the vehicle height adjustment actuator is lowered to the target vehicle height, the internal pressure of the vehicle height adjustment actuator is allowed to discharge the working fluid second from the end. As a result, the vehicle height corresponding to the high adjustment actuator is also lower compared to the case where the discharge of working fluid is permitted so that the vehicle height corresponding to the vehicle height adjustment actuator that is performed at the end is the target vehicle height. This is to additionally allow discharge of the working fluid. The embodiment will be described with reference to FIG.
In this system, the vehicle height adjustment at the time of target vehicle height switching is performed according to the program shown in FIG. 14, and when the target vehicle height is switched, the supply or discharge allowance of the working fluid to the air springs 34 to 40 is in a preset order Here, the left and right front air springs 34 and 36, the left rear air spring 38, and the right rear air spring 40 are performed in this order, and the supply or discharge permission of the working fluid in this order is repeated a plurality of times.

  S281 to S285 of the target vehicle height switching time vehicle height adjustment program are executed in the same manner as S1 to S5 of the program shown in FIG. In S286, the repeated control count C1 is read in accordance with the vehicle height switching mode, and the divided target vehicle height for each control is set for each of the front left and right and the rear right. For the left rear, one control is performed based on a value obtained by dividing the set vehicle height, which should be referred to as the final set vehicle height set lower than the final target vehicle height, by the number of times of repeated control C1. A divided set vehicle height, which is a set vehicle height for each, is set. The final set vehicle height corresponds to the vehicle corresponding to the air spring 38 at the same time as the vehicle height corresponding to the right rear air spring 40 to which the air is supplied last increases among the four air springs 34 to 40 to the final target vehicle height. As long as the vehicle height is high and the vehicle height controlled to the final set vehicle height increases to the final target vehicle height, and the loads on the left wheel 14 and the right wheel 16 are the same, the last and last second air Is set at a height at which the pressures in the air springs 38 and 40 are equal to each other, and the divided set vehicle height and the divided target vehicle height have the same relationship as the final set vehicle height and the final target vehicle height. can get. The final set vehicle height is set for each of the three types of vehicle height switching modes at the time of target vehicle height switching that increases the vehicle height. For example, when the vehicle height is increased in advance, the vehicle height is determined from the final target vehicle height. Low and stored as a set vehicle height when the vehicle height is increased in a set vehicle height memory in association with the vehicle height switching mode. The amount of vehicle height increase every time when raising the vehicle height to the target vehicle height is the same between vehicle height switching modes, and the amount of vehicle height increase every time when the vehicle height is raised to the set vehicle height is also The vehicle height switching mode is the same. Further, in S286, the target vehicle height (final target vehicle height) selected by operating the vehicle height changeover switch 220 is stored in the memory.

  Next, the steps after S287 are executed, and the vehicle height is increased by the set division target vehicle height for the left and right front and the right rear, and the vehicle height is increased for the left rear wheel 14 by the division set vehicle height. Therefore, each time the vehicle height adjustment is performed in the number of times of repeated control C1, the right rear vehicle height is raised to the division target vehicle height, and at the same time, the left rear vehicle height is changed from the division set vehicle height. If the vehicle height is raised and the vehicle height raising control is repeatedly performed C1, the left rear vehicle height and the right rear vehicle height are raised to the final target vehicle height, and the inside of the left and right air springs 38, 40 Are equal to each other. Then, the determination result in S291 is YES, and the counter and the flag F1 are reset in S292.

When the target vehicle height is switched to the side where the vehicle height is lowered, in S294, the repeated control count C2 is read in accordance with the target vehicle height switching mode, and divided for each of the left and right front and right rear. A target vehicle height is set, and a divided target vehicle height is set for the left rear. When the target vehicle height (final target vehicle height) is lowered, the final set vehicle height is set higher than the final target vehicle height, and the divided set vehicle height for each time is set higher than the target divided vehicle height. The final set vehicle height is set for each of the three types of vehicle height switching modes at the time of target vehicle height switching that reduces the vehicle height. By each vehicle height reduction control, the left rear vehicle height is lowered to the divided set vehicle height by permitting air discharge from the left rear air spring 38, but the right rear vehicle height is lowered to the divided target vehicle height. At the same time, the left rear vehicle height that has been lowered to the split set vehicle height is further lowered to reach the split target vehicle height. If the vehicle height reduction control is performed C2 times, the left and right rear vehicle heights all reach the final target vehicle height, and the internal pressures of the left and right air springs 38 and 40 become equal to each other.
As is apparent from the above description, in this system, the portion of the vehicle height control ECU 200 that executes S258 to S291, S295 to S299 constitutes a repetitive control unit, and the vehicle height adjustment is performed each time by the repetitive control unit. All constitute a simultaneous target vehicle height achievement type control unit, and these constitute a pressure difference reduction type control unit.

The set vehicle height that is intentionally different from the target vehicle height may be changed. The embodiment will be described based on the set vehicle height changing program shown in FIG.
In the present embodiment, the set vehicle height is changed when the roll posture of the vehicle at the time of steady turning performed after completion of the vehicle height change by switching the target vehicle height is abnormal. Therefore, the set vehicle height changing program shown in FIG. 15 is executed. The vehicle height adjustment at the time of target vehicle height switching is performed, for example, according to a program similar to the program shown in FIG. 14, but in this embodiment, in addition to resetting the counter and the flag F1, in the step corresponding to S292, The target vehicle height increase switch flag and the target vehicle height decrease switch flag are reset, and in the step corresponding to S300, in addition to resetting the counter and flag F2, the target vehicle height decrease switch flag is set and the target vehicle height is set. The rising switch flag is reset. When the vehicle height change for switching the target vehicle height to the higher side is performed, S311 to S318 of the set vehicle height change program are executed in the same manner as S241 to S248 of the additional adjustment amount change program shown in FIG. The If the occurrence rate of the vehicle roll posture abnormality during turning is equal to or greater than the set rate, S320 is executed, and the set vehicle height at the next vehicle height adjustment is changed to an appropriate vehicle height.

  For example, if an abnormality occurs when turning left and the vehicle height on the right rear is lower than the vehicle height on the right front, it is estimated that the pressure of the right rear air spring 40 is low, the set vehicle height is changed to a lower value, If the rear vehicle height is higher than the right front vehicle height, it is estimated that the pressure of the right rear air spring 40 is high, and the set vehicle height is changed to be high. If the set vehicle height is changed to a lower value, the amount of air supplied to the left rear air spring 38 is decreased to increase the left rear vehicle height to the set vehicle height, while the right rear vehicle height is increased to the target vehicle height. Therefore, the amount of air supplied to the right rear air spring 40 is increased, and the left and right pressure unevenness is reduced. If the set vehicle height is changed to a higher value, the amount of air supplied to increase the left rear vehicle height to the set vehicle height increases, while the right rear vehicle height is supplied to increase to the target vehicle height. The amount of air is reduced, and the left and right pressure unevenness is reduced.

  The amount of change in the set vehicle height is, for example, based on the average value of the ratios of the difference between the vehicle heights before and after the right with respect to the rolling amount of the vehicle body at least once when the vehicle roll posture is determined to be abnormal. It is set and stored in the storage unit 204 as set vehicle height change amount data. When the set vehicle height is lowered, it is subtracted from the currently set vehicle height and added when it is raised. For example, the average value of the ratio is divided into a plurality of stages, and the amount of change is created so as to increase as the average value of the ratio increases, and the set vehicle height change amount data is created in association with the stage of the average value of the ratio. Is done. In this embodiment, the set vehicle height change amount data is theoretically created so as to eliminate the left and right pressure unevenness. Further, the change amount is common to the three vehicle height switching modes of the target vehicle height, and the set vehicle height set for each switching mode is changed. However, the amount of change may vary depending on the target vehicle height switching mode. The change amount of the set vehicle height may be obtained by calculation based on the average value of the ratios.

When the vehicle height adjustment for switching the target vehicle height to the lower side is performed, the set vehicle height change program S311, S321 to S328 is executed in the same manner as the additional adjustment amount change program S241, S251 to S258 shown in FIG. When the abnormality occurrence rate of the roll posture of the vehicle during turning is equal to or higher than the set rate, S330 is executed and the set vehicle height is changed. For example, if the right rear vehicle height is higher than the right front vehicle height, it is estimated that the pressure of the right rear air spring 40 is high, and the set vehicle height is changed to be high. As a result, the allowable discharge amount of air from the left rear air spring 38 when reducing the left rear vehicle height to the set vehicle height is reduced, while the right rear air when reducing the right rear vehicle height to the target vehicle height. The allowable discharge amount of air from the spring 40 is increased, and the left and right pressure unevenness is reduced. If the right rear vehicle height is lower than the right front vehicle height, it is estimated that the pressure of the right rear air spring 40 is lower, and the set vehicle height is changed to be lower. The amount of change is acquired based on the average value of the ratio as in the vehicle height adjustment when the target vehicle height is switched to the higher side, and is the same as the vehicle height change when the vehicle height is changed to switch the target vehicle height to the higher side. Obtained based on quantity data.
As is apparent from the above description, in the present embodiment, the portion of the vehicle height adjustment ECU 200 that executes S318 and S328 constitutes the turning situation-based set vehicle height suitability determination unit, and the portion that executes S320 and S330 turns. It constitutes a situation-dependent setting vehicle height changing section.

The set vehicle height may be changed based on the detection of the internal pressure of the left and right vehicle height adjustment actuators. The embodiment will be described based on the additional adjustment amount changing program shown in FIG.
Although not shown in the drawings, the system of this embodiment is configured in the same manner as the vehicle height adjustment system shown in FIG. The set vehicle height is changed by controlling the vehicle height corresponding to each of the four wheels to the target vehicle height, and then detecting the internal pressures of the left and right air springs 38 and 40 by the pressure sensors 250 and 252 respectively. Based on. Therefore, when the target vehicle height is switched to the higher side, S341 to S352 of the target vehicle height switching vehicle height adjustment program are the same as S281 to S292 of the target vehicle height switching vehicle height adjustment program shown in FIG. The air supply to the four air springs 34 to 40 is repeatedly performed C1 and the counter and the flag F1 are reset. Then, S353 is executed, and the detected values of the two pressure sensors 250 and 252 are detected. It is read and a determination is made as to whether or not the pressures inside the left and right air springs 38, 40 are uneven. This determination is made based on whether or not the absolute value of the difference between the two pressure detection values is greater than or equal to the set value. If the absolute value of the difference is smaller than the set value, the determination result in S313 is NO and the program is executed. Execution ends.

  If the absolute value of the difference between the two pressure detection values is greater than or equal to the set value, the determination result in S353 is YES, S354 is executed, and the set vehicle height is changed. This change is made based on the respective internal pressures of the left and right rear air springs 38, 40. If the pressure of the right rear air spring 40 is higher, the set vehicle height is changed higher, and if lower, The set vehicle height is changed low. As a result, the amount of air supplied to the left and right rear air springs 38 and 40 is changed as in the case of the embodiment described with reference to FIG. 15, and the left and right pressure unevenness is reduced.

  The change amount of the set vehicle height is set in advance according to, for example, the absolute value of the difference between the left and right pressures, and is stored in the storage unit 204 as set vehicle height change amount data. In this embodiment, the set vehicle height change amount data is theoretically created so as to eliminate the left and right pressure unevenness. For example, the absolute value of the difference between the left and right pressures is divided into multiple stages, and the amount of change set so as to increase as the absolute value of the difference increases is associated with the stage of the absolute value of the difference to change the set vehicle height Quantity data has been created. When the set vehicle height is increased, the change amount is added to the current set vehicle height, and when the set vehicle height is decreased, the change amount is subtracted. In this embodiment, the set vehicle height change amount data is theoretically created so as to eliminate the left and right pressure unevenness. The change amount is common to the three types of switching modes of the target vehicle height. The amount of change may vary depending on the target vehicle height switching mode. Further, the change amount may be obtained by calculation based on the absolute value of the difference between the left and right pressures and may be a continuously changing amount.

  When the target vehicle height is switched to the lower side, the vehicle height adjustment program S341 to S344, S355 to S362 at the time of target vehicle height switching is replaced with S281 to S284 of the vehicle height adjustment program at the time of target vehicle height switching shown in FIG. After being executed in the same manner as S293 to S300, S363 is executed, and the internal pressures of the left and right air springs 38 and 40 detected by the two pressure sensors 250 and 252 are read and the absolute value of the difference between them is read. It is determined whether or not is greater than the set difference. If the absolute value of the difference is greater than or equal to the set difference, the determination result in S363 is YES, S364 is executed, and the set vehicle height is changed.

When the target vehicle height is switched to the lower side, if the pressure of the right rear air spring 40 is higher, the set vehicle height is changed higher, and if the pressure of the right rear air spring 40 is lower, the setting is made. Vehicle height is changed low. As a result, similarly to the embodiment described with reference to FIG. 15, the allowable discharge amount of air from the left and right rear air springs 38 and 40 is changed, and the left and right pressure unevenness is reduced. The change amount of the set vehicle height is set in advance according to the absolute value of the difference between the left and right pressures. In this system, it is acquired by the same set vehicle height change amount data as when switching to the higher target vehicle height. Is done.
As is apparent from the above description, in the present system, the part that executes S353 and S363 of the vehicle height adjustment ECU 200 constitutes the detected pressure-dependent set vehicle height suitability determining unit, and the part that executes S354 and S364 is the detected pressure. It constitutes a reliance setting vehicle height changing section.

The vehicle height adjustment actuator may include a hydraulic cylinder that uses liquid as a working fluid. The embodiment will be described with reference to FIG.
In this vehicle height adjustment system, suspension cylinders 314, 316, 318, and 320 are provided between the wheel holding device 310 that holds the front, rear, left, and right wheels 300, 302, 304, and 306 and the vehicle body 312, respectively. It is provided with a spring. Each of the suspension cylinders 314 to 320 is composed of a hydraulic cylinder and has the same structure. The housing 321, the piston 322 fitted to the housing 321 so as to be movable in the axial direction, and the piston rod 324, respectively. The piston rod 324 is connected to the wheel holding device 310 and the housing 321 is connected to the vehicle body 312 so as not to move relative to each other in the vertical direction. The piston 322 is provided with a communication path 330 that communicates the two liquid chambers 326 and 328 partitioned by the piston 322, and the communication path 330 is provided with a throttle. The throttle generates a damping force corresponding to the relative moving speed of the piston 322 relative to the housing 321 (the flow rate of the working fluid flowing through the throttle). The suspension cylinder 314 functions as a shock absorber.

  Individual passages 340, 342, 344, and 346 are connected to the liquid chambers 326 of the suspension cylinders 314, 316, 318, and 320, respectively. An accumulator 350 and an accumulator 352 are connected in parallel to each of the individual passages 340, 342, 344, 346 corresponding to each of the suspension cylinders 314, 316, 318, 320. A spring constant switching valve 354 is provided between the suspension cylinder 314 and the accumulator 352, respectively.

  Each of the accumulators 350 and 352 has a function as a spring, and includes, for example, a housing and a partition member that partitions the inside of the housing, and the individual passages 340 and 342 are provided in one volume change chamber of the partition member. , 344, 346 are connected to each other and an elastic body is provided in the other volume change chamber, and the volume of the other volume change chamber decreases due to an increase in the volume of the one volume change chamber. Can generate an elastic force. The accumulators 350 and 352 can be a bellows type, a bladder type, a piston type, or the like.

  The housing 321 is moved up and down with respect to the piston 322 by changing the height of the vehicle 321 by allowing the hydraulic fluid to be supplied to the liquid chamber 326 of the suspension cylinders 314, 316, 318, and 320 and allowing the hydraulic fluid to be discharged from the liquid chamber 326. . Further, the hydraulic fluid flows out from the liquid chamber 326 to the accumulators 350 and 352, and the hydraulic fluid flows from the accumulators 350 and 352 into the liquid chamber 326 in response to changes in loads acting on the wheels 300, 302, 304, and 306. Changes in vehicle height are allowed. In this embodiment, the accumulator 350 has a larger spring constant than the accumulator 352, but the accumulator 352 functions in the same manner as the accumulator 350 when the spring constant switching valve 354 is opened. In this system, the suspension cylinders 314, 316, 318, and 320 constitute vehicle height adjustment actuators 360, 362, 364, and 366 together with accumulators 350 and 352, respectively. The spring constant switching valve 354 is a normally open electromagnetic opening / closing valve, and the spring constant is switched by the control of the spring constant switching valve 354.

  A variable throttle 370 is provided in each of the individual passages 340, 342, 344, and 346. As described above, the hydraulic fluid flows in and out in the liquid chamber 326 by the vertical movement of the wheel holding device 310 relative to the vehicle body 312. In this case, the individual passages 340, 342, 344, and 346 are caused by the variable throttle 370. By controlling the flow path area, the damping force generated in the suspension cylinder 314 is controlled.

This vehicle height adjustment system includes a hydraulic fluid supply / discharge device 374 as a fluid supply / discharge device. The hydraulic fluid supply / discharge device 374 includes a high pressure source 376, a reservoir 378 as a low pressure source, an individual control valve device 380, and the like.
The high-pressure source 376 includes a pump device 386 having a pump 382 and a pump motor 384, a pressure accumulator 388, and the like. The pump device 386, the pressure accumulator 388, and the like are provided in the control passage 390. The hydraulic fluid in the reservoir 378 is pumped up and discharged by the pump 382 and is stored in a pressure-accumulating accumulator 388 in a pressurized state. The accumulator for pressure accumulation 388 is connected to the control passage 390 via a pressure accumulation control valve 400 which is a normally closed electromagnetic on-off valve. A hydraulic pressure source pressure sensor 402 is provided in the control passage 390. The hydraulic pressure source pressure sensor 402 can detect the discharge pressure of the pump 382 and the accumulator pressure of the accumulator for pressure accumulation 388.

A check valve 404 and a silencing accumulator 406 are provided on the discharge side of the pump 382 in the control passage 390. An outflow passage 408 connecting the high pressure side and the low pressure side of the pump 382 is provided, and an outflow control valve 409 that is a normally closed electromagnetic on-off valve is provided in the outflow passage 408.
The outflow control valve 409 can be a mechanical on-off valve. For example, a pilot-type on-off valve that uses the discharge pressure of the pump 382 as a pilot pressure is closed when the discharge pressure is increased by the operation of the pump 382, and is opened in other cases.

  The individual control valve device 380 includes individual control valves 410, 412, 414, 416 provided in the individual passages 340, 342, 344, 346. The individual passages 340, 342, 344 and 346 are connected to the control passage 390 in parallel with each other. That is, the suspension cylinders 314, 316, 318, and 320 are connected to the control passage 390 by the individual passages 340, 342, 344, and 346, respectively. These individual control valves 410, 412, 414, and 416 are normally closed electromagnetic on-off valves. By individually controlling the individual control valves 410, 412, 414, and 416, the wheels 300, 302, 304, and 306 are controlled. In each, the vehicle height which is a relative position in the vertical direction between the wheels 300, 302, 304, and 306 and portions corresponding to the wheels of the vehicle body 312 (portions where the suspension cylinders 314, 316, 318, and 320 are connected) is determined. It can be controlled independently.

  This vehicle suspension system is controlled by a vehicle height adjustment ECU (electronic control unit) 420 mainly composed of a computer. The vehicle height adjustment ECU 420 includes an execution unit 422, a storage unit 424, an input / output unit 426, and the like. The input / output unit 426 includes a coil of a spring constant switching valve 354 and a variable throttle 370, and a hydraulic fluid supply / discharge device 374 (accumulation pressure). The control valve 400, the individual control valves 410, 412, 414, 416, the coil of the outflow control valve 400, the pump motor 384, etc.) are connected via a drive circuit (not shown). The input / output unit 426 is also provided corresponding to the hydraulic pressure source pressure sensor 402 and the front, rear, left and right wheels 300, 302, 304, 306, and detects vehicle height sensors 430, 432, 434, 436. , A vehicle speed sensor 438, a vehicle height changeover switch 440, and the like are connected to each other, and a target vehicle height display lamp 442 is connected.

  In the vehicle height adjustment system, the target vehicle height is selected by the operation of the vehicle height changeover switch 440 by the occupant, and is controlled so that the vehicle height becomes the target vehicle height. In order to increase the vehicle height, the pressure accumulation control valve 400 is opened, and the individual control valve corresponding to the vehicle height to be increased is opened. The hydraulic fluid is supplied and the housing 321 is extended. When the actual vehicle height detected by the vehicle height sensor reaches the target vehicle height, the individual control valve is closed and the pressure accumulation control valve 400 is closed. Further, the pump device 386 is operated, and the hydraulic fluid discharged from the pump 382 can be supplied to the suspension cylinder together with the hydraulic fluid supplied from the pressure accumulator 388.

  When the vehicle height is lowered, the individual control valve corresponding to the vehicle height to be lowered is opened, and the outflow control valve 409 is opened, so that the hydraulic fluid from the suspension cylinder fluid chamber 326 to the reservoir 378 is discharged. Outflow is allowed and the housing 321 is contracted. When the actual vehicle height detected by the vehicle height sensor reaches the target vehicle height, the individual control valve is closed, and then the outflow control valve 409 is closed.

  In the present vehicle height adjustment system, the vehicle height adjustment is performed in the same manner as when the working fluid is air. For example, any of the vehicle height adjustment systems of the embodiments shown in FIGS. 1 to 4 and FIGS. The vehicle height is adjusted while reducing (including eliminating) the uneven pressure in the liquid chamber 326 of the suspension cylinders 318 and 320 at the left and right rear. Further, if the vehicle height adjustment system is provided with, for example, a pressure sensor for detecting the pressure in each of the liquid chambers 326 of the left and right suspension cylinders 318 and 320, the embodiments shown in FIGS. 5, 6 and 16, respectively. Similar to the vehicle height adjustment system of the example, the vehicle height adjustment can be performed while reducing (including eliminating) the pressure unevenness on the left and right.

  When the set vehicle height is intentionally different from the target vehicle height, the change may be performed based on at least one of the vehicle height adjustment frequency and the adjustment required time. For example, as in the embodiment shown in FIGS. 7 to 10, the set vehicle height is changed based on the history of vehicle height maintenance adjustment performed after vehicle height switching.

  The vehicle height corresponding to each of the four wheels may be different from each other even if the target vehicle height level is the same. For example, when the target vehicle height levels are three types of low, normal, and high, the vehicle heights of the left and right front wheels and the left and right rear wheels are different from each other for each target vehicle height.

  Further, the target vehicle height may be switched automatically by an automatic switching device.

  Further, at least one of supply and discharge of the working fluid is performed until the vehicle height corresponding to the penultimate vehicle height adjustment actuator reaches the set vehicle height, and the vehicle height corresponding to the last vehicle height adjustment actuator is targeted. When at least one of supply and discharge of working fluid is performed so that the vehicle height is reached, the vehicle height corresponding to the second vehicle height adjustment actuator from the end is adjusted to the set vehicle height all at once, and the last vehicle height adjustment The vehicle height corresponding to the actuator may be adjusted to the target vehicle height all at once. When at least one of the supply and discharge of the working fluid is performed in a plurality of times, the set vehicle height may be set for the last vehicle height adjustment, and a part of the plurality of times, The set vehicle height may be set for a plurality of vehicle height adjustments.

It is a circuit diagram which shows the vehicle height adjustment system which is one Example. It is a flowchart which shows the vehicle height adjustment program at the time of the target vehicle height switching memorize | stored in the memory | storage part of the vehicle height adjustment ECU of the said vehicle height adjustment system. It is a flowchart which shows the target vehicle height maintenance program memorize | stored in the said memory | storage part. Changes in the internal pressure of the left and right air springs and the left and right and left and right air in the conventional vehicle height adjustment system when switching to increase the target vehicle height is performed by executing the vehicle height adjustment program when the target vehicle height is switched. It is a graph which shows the change of the internal pressure of a spring. It is a circuit diagram which shows the vehicle height adjustment system which is another Example. It is a flowchart which shows the vehicle height adjustment program at the time of target vehicle height switching memorize | stored in the memory | storage part of vehicle height adjustment ECU of the vehicle height adjustment system shown in FIG. It is a flowchart which shows the vehicle height adjustment program at the time of the target vehicle height switching memorize | stored in the memory | storage part of the vehicle height adjustment ECU of the vehicle height adjustment system which is another Example. It is a flowchart which shows a part of target vehicle height maintenance program memorize | stored in the memory | storage part with the vehicle height adjustment program at the time of the target vehicle height switch shown in FIG. It is a flowchart which shows the remainder of the target vehicle height maintenance program shown in FIG. It is a flowchart which shows the additional adjustment amount change program memorize | stored in the memory | storage part with the vehicle height adjustment program at the time of target vehicle height switching shown in FIG. It is a flowchart which shows the vehicle height adjustment program at the time of the target vehicle height switching memorize | stored in the memory | storage part of the vehicle height adjustment ECU of the vehicle height adjustment system which is another Example. It is a flowchart which shows the additional adjustment amount change program memorize | stored in the memory | storage part with the vehicle height adjustment program at the time of target vehicle height switching shown in FIG. It is a flowchart which shows the additional adjustment amount change program memorize | stored in the memory | storage part of the vehicle height adjustment ECU of the vehicle height adjustment system which is another Example. It is a flowchart which shows the vehicle height adjustment program at the time of the target vehicle height switching memorize | stored in the memory | storage part of the vehicle height adjustment ECU of the vehicle height adjustment system which is another Example. It is a flowchart which shows the setting vehicle height change program memorize | stored in the memory | storage part of the vehicle height adjustment ECU of the vehicle height adjustment system which is another Example. It is a flowchart which shows the vehicle height adjustment program at the time of the target vehicle height switching memorize | stored in the memory | storage part of the vehicle height adjustment ECU of the vehicle height adjustment system which is another Example. It is a circuit diagram which shows the vehicle height adjustment system which is another Example.

Explanation of symbols

  10: Left front wheel 12: Right front wheel 14: Left rear wheel 16: Right rear wheel 34, 36, 38, 40: Air spring 80: Air supply / discharge device 200: Vehicle height adjustment ECU 210, 212, 214, 216: Vehicle height Sensors 250, 252: Pressure sensor 300: Left front wheel 302: Right front wheel 304: Left rear wheel 306: Right rear wheel 314, 316, 318, 320: Suspension cylinder 350, 352: Accumulator 360, 362, 364, 366: Vehicle height Adjustment actuator 374: Hydraulic fluid supply / discharge device 420: Vehicle height adjustment ECU 430, 432, 434, 436: Vehicle height sensor

Claims (9)

A vehicle that is provided corresponding to each of the left and right front wheels and the left and right rear wheels of the vehicle, changes the vehicle height corresponding to each wheel as the working fluid is supplied and discharged, and responds to changes in the load acting on each wheel. Each front height, right front, left rear and right rear vehicle height adjustment actuators that allow height changes,
A fluid supply / discharge device that supplies working fluid to the vehicle height adjusting actuators and allows discharge of the working fluid from the vehicle height adjusting actuators;
A vehicle height adjustment system including a control device for controlling the fluid supply / discharge device, wherein the control device comprises:
The vehicle height corresponding to each of the left and right front wheels and the left and right rear wheels can be detected, and for at least one of the left and right front wheels and the left and right rear wheels, the vehicle height corresponding to each of the left wheel and the right wheel is individually determined. A vehicle height detection device capable of detecting
The working fluid is supplied in a predetermined order in which the supply of the working fluid to the vehicle height adjusting actuator corresponding to any one of the left wheel and the right wheel of the left and right front wheels and the left and right rear wheels is the last. And the discharge of the working fluid from the vehicle height adjustment actuator corresponding to either one of the left wheel and the right wheel of the left and right front wheels and the left and right rear wheels is predetermined. The vehicle height detected by the vehicle height detection device is controlled to a target vehicle height by performing at least one of allowing discharge of the working fluid in order, and the working fluid in the predetermined order is controlled. At least one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators caused by at least one of supply and discharge of working fluid Vehicle height control system comprising a differential pressure relief type control unit for performing at least one additionally the supply and discharge allowable predetermined working fluid in a direction to reduce the uneven internal pressure.   The predetermined order is at least one of supply of working fluid to one of the two vehicle height adjusting actuators at a position where the vehicle height can be individually detected by the vehicle height detecting device and discharge permission of the working fluid. The vehicle height adjustment system according to claim 1, wherein the order is the last order. The pressure difference reduction type control unit is
The vehicle height detected by the vehicle height detection device by performing at least one of supplying the working fluid in the predetermined order and allowing the discharge of the working fluid in the predetermined order. Sequentially controlling the vehicle to the target vehicle height;
After the control by the sequential control unit, among the left front, right front, left rear and right rear vehicle height adjustment actuators, the left front and right front vehicle height adjustment actuators, The vehicle height adjustment system according to claim 1, further comprising: an additional control unit that performs additional control in a direction that reduces unevenness of pressure in at least one of the left rear and right rear vehicle height adjustment actuators. .   The sequential control unit simultaneously performs at least one of supply and discharge of working fluid to one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators; Performing at least one of supply and discharge of working fluid individually and sequentially to the other of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators. The vehicle height adjustment system according to claim 3.   The sequential control unit simultaneously performs at least one of supply and discharge of working fluid to one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators; Performing at least one of supplying and discharging the working fluid separately to the other of the left front and right front vehicle height adjusting actuators and the left rear and right rear vehicle height adjusting actuators a plurality of times. The vehicle height adjustment system according to claim 3, comprising a sequential control repeater that is repeatedly performed.   The amount of additional supply of the working fluid based on at least one of a vehicle height adjustment frequency and an adjustment time for one of the left front, right front, left rear, and right rear vehicle height adjustment actuators; The vehicle height adjusting system according to any one of claims 1 to 5, further comprising an amount changing unit that changes at least one of the working fluid and the discharge allowable amount. A vehicle that is provided corresponding to each of the left and right front wheels and the left and right rear wheels of the vehicle, changes the vehicle height corresponding to each wheel as the working fluid is supplied and discharged, and responds to changes in the load acting on each wheel. Each front height, right front, left rear and right rear vehicle height adjustment actuators that allow height changes,
A fluid supply / discharge device that supplies working fluid to the vehicle height adjusting actuators and allows discharge of the working fluid from the vehicle height adjusting actuators;
A vehicle height adjustment system including a control device for controlling the fluid supply / discharge device, wherein the control device comprises:
Vehicle heights corresponding to the left and right front wheels and the left and right rear wheels can be detected, and for at least one of the left and right front wheels and the left and right rear wheels, the vehicle height corresponding to each of the left wheel and the right wheel is individually determined. A vehicle height detection device capable of detection;
Two or more pressure sensors for detecting a pressure in at least one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators;
The working fluid is supplied in a predetermined order in which the supply of the working fluid to the vehicle height adjusting actuator corresponding to any one of the left wheel and the right wheel of the left and right front wheels and the left and right rear wheels is the last. And the discharge of the working fluid from the vehicle height adjustment actuator corresponding to either one of the left wheel and the right wheel of the left and right front wheels and the left and right rear wheels is predetermined. The vehicle height detected by the vehicle height detection device is controlled to a target vehicle height by performing at least one of allowing discharge of the working fluid in order, and detected by the two or more pressure sensors. Supply and discharge of working fluid for reducing non-uniform pressure in at least one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators Vehicle height control system comprising a differential pressure relief type control unit for performing at least one of the volumes. The pressure difference reduction type control unit is
The vehicle height detected by the vehicle height detection device by performing at least one of supplying the working fluid in the predetermined order and allowing the discharge of the working fluid in the predetermined order. A sequential control unit for controlling the vehicle to the target vehicle height,
The pressure in at least one of the left front and right front vehicle height adjustment actuators and the left rear and right rear vehicle height adjustment actuators detected by the two or more pressure sensors after the control by the sequential control unit. The vehicle height adjustment system according to claim 7, further comprising: an additional control unit that performs at least one of supply of the working fluid and discharge allowance that reduce the unevenness of the vehicle.   The predetermined order is the last supply of the working fluid to the vehicle height adjustment actuator corresponding to any one of the left wheel and the right wheel of the left and right front wheels and the left and right rear wheels, The order in which the working fluid supply to the vehicle height adjusting actuator corresponding to the other of the left wheel and the right wheel is the second from the last, and the left wheel and the right of either the left or right front wheel or the left or right rear wheel The discharge of the working fluid from the vehicle height adjustment actuator corresponding to one of the wheels is the last, and the discharge of the working fluid from the vehicle height adjustment actuator corresponding to the other of the left wheel and the right wheel is the last. And the pressure difference reducing control unit is configured to perform the operation fluid until the vehicle height corresponding to the second vehicle height adjustment actuator from the last reaches a set vehicle height. At least one of supply and discharge, at least one of supply and discharge of the working fluid so that the vehicle height corresponding to the last vehicle height adjustment actuator becomes the target vehicle height, and the set vehicle When the vehicle height corresponding to the last vehicle height adjustment actuator reaches the target vehicle height, the vehicle height that was the set vehicle height changes to the target vehicle height, and the two vehicle height adjustment actuators The vehicle height adjustment system according to claim 1, further comprising a simultaneous target vehicle height attainment type control unit set so that the internal pressures thereof are equal to each other.

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