JP2007118769A - Suspension system of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sense a defective operation of a control cylinder in a suspension system of a vehicle. <P>SOLUTION: When a vehicle is determined in a steady turning condition based on a steering angle and speed of the vehicle read in S1 (S2), an amount of standard liquid pressure variation of respective liquid chambers of four suspension cylinders in the steady turning condition is acquired (S3). The actual liquid pressure is read for the liquid chamber of each suspension cylinder in S4; and in S5, it is determined whether the actual amount of liquid pressure variation lies within an allowable range or not with respect to the amount of standard liquid pressure variation. If not within the allowable range, an alarm is issued (S6) alarming defective operation in the control cylinder. Defective operation of the control cylinder can be detected based on a liquid pressure variation in the suspension cylinder in case of riding of a wheel on a projection on the road surface, or in case of adjusting a vehicle height by a certain amount for one wheel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention controls four suspension cylinders provided between four wheels on the front, rear, left and right sides of the vehicle and the vehicle body, and operates by receiving the fluid pressures of the four fluid chambers to which the fluid chambers of the suspension cylinders are respectively connected. The present invention relates to a vehicle suspension system including a control cylinder provided with a piston, and particularly to detection of a malfunction of the control cylinder.

The vehicle suspension system including the four suspension cylinders and the control cylinder is described in, for example, Patent Document 1 and Patent Document 2 below. Various methods are known for connecting the liquid chambers of the four suspension cylinders and the four liquid chambers of the control cylinder, including those described in Patent Documents 1 and 2, and how to connect them. Depending on the function of the control cylinder. However, once the connection method is determined, the function of the control cylinder is determined. As a result, the state of the four suspension cylinders and the causes of the change (for example, the force acting on the vehicle body and wheels, the working fluid to the suspension cylinder) Supply / discharge etc.). That is how the control cylinder works.
JP 2004-322755 A U.S. Pat. No. 30,240,37

However, if the control cylinder is in a malfunctioning state, that is, if the control piston does not operate or does not operate properly even if it operates, there is a relationship between the above causes and changes in the state of the four suspension cylinders. The vehicle suspension system does not function as designed, and the vehicle suspension system does not perform its original function. The control piston can move freely in the axial direction within the housing of the control cylinder. However, the control piston may not move for some reason or may not move smoothly. Disappear. Ideally, the control piston should be located in the axial center of the housing, but it could move to one end of the operable area as the operation was repeated. In one direction, the control piston cannot move, and the control cylinder becomes defective. It is desirable to detect such a malfunction of the control cylinder as early as possible, issue an alarm to the driver to prompt repair, or change the vehicle running control.
However, since the control piston cannot be seen from the outside of the control cylinder, it cannot be visually confirmed whether or not it is operating well.
The present invention has been made under the circumstances described above, and includes four suspension cylinders provided between the front and rear, left and right four wheels of the vehicle and the vehicle body, and four fluid chambers connected to the suspension cylinders, respectively. In a vehicle suspension system including a control cylinder having a control piston that operates by receiving the hydraulic pressure of a liquid chamber, it is an object to enable detection of a malfunction of the control cylinder.

  In order to solve the above problems, the present invention provides a vehicle suspension system including the above four suspension cylinders and a control cylinder in the event of occurrence of a state change cause that causes a change in the state of the four suspension cylinders. Based on the fact that the change that occurs in the state of the suspension cylinder differs depending on whether the control cylinder operates normally or not, a control cylinder malfunction detection device that detects malfunction of the control cylinder is provided. Features.

Effects and effects of the invention

  As described above, if the operation of the control cylinder becomes defective, the relationship between the cause of the change in the state of the four suspension cylinders, such as the force acting on the vehicle body and the wheels, and the actual state change is that the operation of the control cylinder is normal. It is different from the case. Therefore, if a control cylinder malfunction detection device that detects malfunction of the control cylinder based on this fact is provided, it is possible to easily detect malfunctions of the control piston that are not visible, and to alert the driver. It is possible to prompt repair and change the vehicle running control.

Aspects of the Invention

  In the following, the invention that is claimed to be claimable in the present application (hereinafter 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, or inventions of different concepts) will be illustrated 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 examples, etc., and as long as the interpretation is followed, a mode in which other components are added to the mode of each section. In addition, an aspect in which 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, (4) corresponds to claim 4, (9) corresponds to claim 5, (12) corresponds to claim 6, (14) corresponds to claim 7, (15) corresponds to claim 8, and (16) corresponds to claim 9. To do.

(1) Four suspension cylinders provided between the front and rear, left and right four wheels of the vehicle and the vehicle body, and a control piston that operates by receiving the fluid pressures of the four fluid chambers to which the fluid chambers of the suspension cylinders are respectively connected. A vehicle suspension system including a control cylinder with
When a cause of a state change that causes a change in the state of the four suspension cylinders occurs, a change that occurs in the state of the four suspension cylinders depends on whether the control cylinder operates normally or does not operate normally. A vehicle suspension system comprising a control cylinder malfunction detection device that detects malfunction of the control cylinder based on differences.
(2) The control cylinder malfunction detection device is
A state change cause detection unit for detecting occurrence of the state change cause;
An actual state detection unit for detecting an actual state that is an actual state of the four suspension cylinders;
An operation failure determination unit that determines that the operation of the control cylinder is defective when the actual state detected by the actual state detection unit and the state change cause detected by the state change cause detection unit do not correspond to each other; The vehicle suspension system according to item (1), including:
The state change cause detection unit detects the occurrence of the state change cause, and the actual state detection unit detects the actual state of the four suspension cylinders. Then, the operation failure determination unit determines that the operation of the control cylinder is defective when the detected cause of the state change does not correspond to the actual state. There are various causes of the state change, but particularly effective ones are described in the following sections.
(3) The actual state detection unit includes a hydraulic pressure detection unit that detects the hydraulic pressure of each of the fluid chambers of the four suspension cylinders as the actual state, and the malfunction determination unit is A hydraulic pressure-dependent operation failure determination unit that determines that the operation of the control cylinder is defective when the detected cause of the state change and the hydraulic pressure detected by the hydraulic pressure detection unit do not correspond to each other; The vehicle suspension system according to (2).
If the operation of the control cylinder becomes defective, the fluid pressures in the fluid chambers of the four suspension cylinders at the time of occurrence of the state change become different from the state in which the control cylinder operates satisfactorily. In other words, the state change cause detected by the state change cause detection device and the fluid pressure detected by the fluid pressure detection device correspond to each other, that is, they do not correspond to each other as designed. Become. Therefore, the operation failure determination unit can determine that the operation of the control cylinder is defective based on the fact.
Although the state change cause detection unit, the hydraulic pressure detection unit, and the operation failure determination unit can be provided exclusively for operation failure detection of the control cylinder, many of these devices are already mounted on the vehicle for other purposes. Therefore, they can be used, and in this case, the present invention can be implemented at low cost.
(4) The state change cause detection unit includes a steady turning state detection unit that detects, as the state change cause, that the vehicle body is in a steady turning state in which the posture of the vehicle body is stable when the vehicle turns. Includes a steady-turn determination unit that determines that the control cylinder is malfunctioning when the detected hydraulic pressure by the hydraulic pressure detection unit and the detected steady-turn state detected by the steady-turn state detector do not correspond to each other (3 The vehicle suspension system according to item).
When the vehicle shifts from the straight traveling state to the turning state, the load applied to the suspension cylinder changes, and the fluid pressure in the fluid chamber of the suspension cylinder changes. This change occurs even during the transition from the straight running state to the turning state, but in the steady turning state and the stable posture of the vehicle body, as long as the control cylinder operates satisfactorily, the vehicle body posture remains steady turning. The posture is determined by the turning radius and the vehicle speed in the state, and the relationship between the fluid pressures of the fluid chambers of the four suspension cylinders is also constant. Therefore, while the control cylinder operates satisfactorily, the posture of the vehicle body estimated from the steady turning state of the vehicle and the relationship between the fluid pressures of the fluid chambers of the four suspension cylinders correspond to each other. However, if the operation of the control cylinder becomes defective, the relationship between the posture of the vehicle body estimated from the turning state of the vehicle and the fluid pressure in the suspension cylinder fluid chamber does not correspond to each other. Therefore, when the two do not correspond to each other, the operation of the control cylinder can be regarded as defective. However, the “posture of the vehicle body estimated from the turning state of the vehicle” in the state where the control cylinder does not operate normally is not the same as the actual posture, and a stable posture in the turning state is determined when determining the malfunction. It is not always necessary to estimate actually, and the relationship between the steady turning state in the state where the operation of the control cylinder is good and the fluid pressure in each fluid chamber of the control cylinder is obtained in advance by calculation or measurement, and the relationship If the actual relationship deviates more than the set state (amount or ratio) from the above, the operation of the control cylinder may be defective. In addition, when the malfunction determination unit determines malfunction based on the hydraulic pressure level of each fluid chamber of the suspension cylinder, the steady rotation state detection unit is set as a quantity representing the steady rotation state. Although it is necessary to detect the magnitude of acceleration and yaw rate, it is assumed that the determination unit at the time of steady turning is to determine malfunction due to the ratio of the fluid pressures of the fluid chambers of two or more suspension cylinders. For example, the steady turning state detection unit can detect that the steady turning state itself is present.
(5) The steady turning state detection unit detects a traveling state of the vehicle, and a traveling state detection unit that acquires the steady turning state based on the traveling state detected by the traveling state detection unit. And the vehicle suspension system according to item (4).
(6) The travel state detection unit includes a steering angle acquisition unit that acquires a steering angle of the vehicle and a vehicle speed acquisition unit that acquires a vehicle speed that is a travel speed of the vehicle, and the travel state dependence acquisition unit The vehicle suspension system according to (5), further including a steering angle / vehicle speed dependence acquisition unit that acquires the steady turning state based on the steering angle and the vehicle speed acquired by the angle acquisition unit and the vehicle speed acquisition unit.
(7) The travel state detection unit includes at least one of a lateral acceleration acquisition unit that acquires lateral acceleration of the vehicle and a yaw rate acquisition unit that acquires the yaw rate of the vehicle, and the travel state dependence acquisition unit includes at least The vehicle suspension system according to (5) or (6), further including a lateral acceleration / yaw rate dependence acquisition unit that acquires the steady turning state based on at least one of the lateral acceleration and yaw rate acquired by one.
(8) The vehicle suspension system includes a vehicle height adjusting device that adjusts a vehicle height corresponding to each of the four wheels by supplying and discharging hydraulic fluid to and from the four suspension cylinders. The vehicle suspension system according to any one of the items.
The vehicle height is a relative height between each of the four wheels and a portion corresponding to each of the four wheels of the vehicle body.
(9) The vehicle suspension system includes a vehicle height adjustment device that adjusts a vehicle height corresponding to each of the four wheels by supplying and discharging hydraulic fluid to and from the four suspension cylinders, and the state change cause detection unit includes , A partial vehicle height adjustment detection unit for detecting that the vehicle height adjustment device has supplied and discharged hydraulic fluid to and from the suspension cylinder corresponding to a part of the four wheels, and a partial vehicle height adjustment detection thereof A partial vehicle height adjustment-induced posture change estimation unit that estimates a change in posture of the vehicle body corresponding to the partial vehicle height adjustment as a cause of the state change in response to detection of partial vehicle height adjustment by the unit, and The operation failure determination unit determines that the operation of the control cylinder is defective when the detected hydraulic pressure of the hydraulic pressure detection unit and the estimated partial vehicle height adjustment-induced posture change do not correspond to each other. Including the vehicle height adjustment judgment part Vehicle suspension system according to any misalignment.
If the vehicle height adjustment device supplies and discharges hydraulic fluid to and from the suspension cylinder corresponding to a part of the four wheels, the posture of the vehicle body changes, and accordingly, the fluid pressure in each fluid chamber of the four suspension cylinders also changes. Change. This change in the hydraulic pressure differs depending on whether the operation of the control cylinder is good or bad. Therefore, the malfunction determination unit determines whether the hydraulic pressure detected by the hydraulic pressure detection unit corresponds to the partial vehicle height adjustment-induced posture change estimated by the partial vehicle height adjustment-induced posture change estimation unit. It is possible to determine whether or not the operation is defective. Also in this aspect, the posture change estimation unit due to part of the vehicle height adjustment does not necessarily estimate the posture change amount itself, but estimates that the posture change more than the set amount will occur, or is caused by the posture change. The fluid pressure in the fluid chamber of the suspension cylinder (at least one of the four suspension cylinders) or a change in the fluid pressure may be estimated. Further, the vehicle height adjustment in this section may increase or decrease the vehicle height.
(10) The operation failure determination unit includes a one-wheel vehicle height adjustment control unit that causes the vehicle height adjustment device to perform a predetermined amount of vehicle height adjustment on one of the four wheels. The vehicle suspension system according to (9), wherein the adjustment detection unit includes a single-wheel vehicle height adjustment detection unit that detects execution of the single-wheel vehicle height control by the single-wheel vehicle height adjustment control unit.
If the one-wheel vehicle height adjustment control unit causes the vehicle height adjustment device to adjust the vehicle height by a predetermined amount for one of the four wheels, the posture of the vehicle body changes, and each liquid in the four suspension cylinders changes. The chamber hydraulic pressure changes. This change in hydraulic pressure differs depending on whether the operation of the control cylinder is good or not, but the difference between the two increases as the “predetermined amount of vehicle height adjustment” increases. Therefore, the “predetermined amount of vehicle height adjustment” may use a single adjustment when the vehicle height adjustment for each wheel is sequentially performed in the normal vehicle height adjustment. Sometimes it is desirable to have a larger one-wheel vehicle height adjustment dedicated to detecting malfunctions.
(11) The state change cause detection unit is based on three or more vehicle height detection devices that detect vehicle heights in at least three locations of the vehicle body, and at least three vehicle heights detected by the vehicle height detection devices. Vehicle height dependency acquisition unit for acquiring the change in posture of the vehicle body as the cause of the state change, and the vehicle suspension system according to any one of items (3) to (7), (9), (10) .
The features of this section can also be adopted in the vehicle suspension system of section (2).
(12) When the operation failure determination unit does not correspond to the posture change acquired by the vehicle height dependence acquisition unit and the hydraulic pressure detected by the hydraulic pressure detection unit when the vehicle is in a stopped state The vehicle suspension system according to item (11), further including an operation failure determination unit for stopping when determining operation failure of the control cylinder.
Even when the vehicle is stopped, the control piston may move from the position before the occurrence (control cylinder is activated) due to, for example, passengers getting on and off, loading or unloading of luggage, etc. In this case, if the control cylinder operates satisfactorily, a certain relationship is established between the posture acquired by the vehicle height dependence acquisition unit and the hydraulic pressure detected by the hydraulic pressure detection device while the vehicle is stopped. However, if the operation of the control cylinder is defective, the relationship is lost. The posture and hydraulic pressure do not correspond. Therefore, the malfunction determination unit determines that the posture and the fluid pressure do not correspond to each other (for example, the difference between the fluid pressure corresponding to the posture detected when the operation of the control cylinder is good and the fluid pressure actually detected). Is greater than the set amount or set ratio, or when the posture estimated from the detected hydraulic pressure and the posture obtained by the vehicle height dependence acquisition unit differ by more than the set state) It can be determined that it is defective.
(13) Two or more vehicle height detection devices, wherein the state change cause detection unit detects a vehicle height corresponding to each of at least two of the four wheels, and among the at least two wheels by the vehicle height detection device. When a change greater than the set amount of the vehicle height corresponding to one wheel of the vehicle is detected, a one-wheel vehicle that acquires a change in posture due to a change in one-wheel vehicle corresponding to the change in vehicle height as the cause of the state change The vehicle suspension system according to any one of items (3) to (7) and (9) to (12), including a posture change acquisition unit during high change.
Also in this section, it is not indispensable that the posture change acquisition unit at the time of changing the single-wheel vehicle height actually acquires the single-wheel vehicle height change-induced posture change amount. For example, the vehicle height corresponding to at least one wheel different from the one wheel in which the change in the vehicle height more than the set amount is detected is estimated, or is generated according to the posture change amount due to the change in the one-wheel vehicle height exceeding the set amount. It is only necessary to estimate the fluid pressure in the fluid chamber of at least one suspension cylinder corresponding to the posture change. In the latter case, the “one suspension cylinder” may be the suspension cylinder itself corresponding to one wheel in which a change of the vehicle height or more is detected, or may be another suspension cylinder.
(14) The operation failure determination unit corresponds to the hydraulic pressure detected by the hydraulic pressure detection unit and the posture change caused by the one-wheel vehicle height change acquired by the posture change acquisition unit during the one-wheel vehicle height change. The vehicle suspension system according to item (13), including a one-wheel vehicle height change determination unit that determines that the operation of the control cylinder is defective when the control cylinder is not operated.
If the control cylinder operates satisfactorily, if one of the four wheels rides on a protrusion on the road surface or falls into a recess, the vehicle height corresponding to that wheel changes by more than a set amount. The suspension cylinder corresponding to the one wheel expands and contracts, the hydraulic fluid flows into and out of the fluid chamber of the suspension cylinder, and the control piston moves. On the other hand, when the operation of the control cylinder is defective, the flow of hydraulic fluid in the suspension cylinder is limited, and the state of the hydraulic pressure change of the four suspension cylinders is different from the case where the operation of the control cylinder is good. . Based on this fact, the malfunction detection device detects that the control cylinder is malfunctioning.
The suspension cylinder corresponding to “one wheel in which a change in the vehicle height or more of the set amount is detected” and the suspension cylinder corresponding to the hydraulic pressure used in the malfunction determination unit may be the same or different. There may be. In the latter case, the suspension cylinder in the position where the largest hydraulic pressure change occurs in a state where the operation of the control cylinder is good with respect to “one wheel in which a change of the vehicle height or more is detected” is detected. It is desirable to be. Further, the hydraulic pressure used in the malfunction determination unit may be the hydraulic pressure of the liquid chambers of the plurality of suspension cylinders, or the difference or ratio of the hydraulic pressures of the two liquid chambers.
(15) The vehicle suspension system includes a hydraulic fluid supply / discharge device common to the four suspension cylinders, and four individual on-off valves provided between the hydraulic fluid supply / discharge device and each of the four suspension cylinders. And a vehicle height adjustment control unit that adjusts the vehicle height corresponding to each of the four wheels by controlling the four individual on-off valves and the hydraulic fluid supply / discharge device, and the fluid pressure detection unit Is provided between the four individual on-off valves and the hydraulic fluid supply / discharge device in common with the four individual on-off valves, and shuts off the communication between the four individual on-off valves and the hydraulic fluid supply / discharge device. A hydraulic pressure sensor provided in common between the four individual on-off valves between the shut-off means and the four individual on-off valves, and the four individual on-off valves in a state in which the shut-off means is kept in the shut-off state. The four suspension series are opened and closed sequentially by the hydraulic pressure sensor. To (3) no claim and a liquid pressure detection control unit for sequentially detecting the liquid pressure of the liquid chamber of Da (7) section (9) term to (14) vehicle suspension system according to any one of Items.
According to the invention of this section, the hydraulic pressures of the fluid chambers of the four suspension cylinders can be detected by one hydraulic pressure sensor by using the blocking means that is often provided in the vehicle height adjusting device. As the shut-off means, an on-off valve such as an electromagnetic on-off valve is suitable, but it is not limited to this.
(16) The vehicle suspension system includes a vehicle height adjustment device that adjusts a vehicle height corresponding to each of the four wheels by supplying and discharging hydraulic fluid to and from the four suspension cylinders, and the control cylinder malfunctions. The detection device
An openable and closable plug provided corresponding to one of the four suspension cylinders;
A stop state detector for detecting that the vehicle is in a stop state;
A liquid that causes the vehicle height adjusting device to set the liquid pressures of all the four suspension cylinders to atmospheric pressure on the condition that at least the stop state detection unit detects that the vehicle is in a stopped state. A pressure release control unit;
After the hydraulic pressure is released by the hydraulic pressure elimination control unit, the hydraulic pressure of one suspension cylinder different from the suspension cylinder provided with the plug is provided to the vehicle height adjusting device. The vehicle suspension system according to any one of items (1) to (15), further including a hydraulic pressure increase control unit for increasing.
In a state where the hydraulic pressure elimination control unit sets the hydraulic pressures of all the fluid chambers of the four suspension cylinders to the atmospheric pressure, the operator corresponds to one fluid chamber of the suspension cylinders (the fluid chamber itself or the fluid chamber and Loosen the plug provided at the communicating part. Thereafter, the hydraulic pressure increase control unit increases the hydraulic pressure of one of the four suspension cylinders. If the control cylinder operates satisfactorily according to the increase in the hydraulic pressure, the hydraulic fluid flows into the fluid chamber of the suspension cylinder where the plug is loosened, and the hydraulic fluid flows out from the plug. The operator can determine whether the control cylinder is operating well or malfunctioning by observing the outflow state of the hydraulic fluid. Therefore, the suspension cylinder in which the hydraulic pressure is increased is a suspension cylinder in a relative position where the hydraulic fluid flows into the fluid chamber of the suspension cylinder in which the plug is loosened if the fluid pressure in the fluid chamber is increased. It is necessary to be. It is desirable that the hydraulic pressure increase control unit increases the hydraulic pressure by a set amount. Further, two or more sets of “one of the four suspension cylinders” and “one suspension cylinder different from the suspension cylinder provided with the plug” may be provided.
(17) Furthermore,
A plug opening instruction unit for instructing to open the plug after the hydraulic pressure is released by the hydraulic pressure elimination control unit;
A plug opening detection unit that detects that the plug has been opened in response to a plug opening instruction by the plug opening instruction unit, and the hydraulic pressure increase control unit responds to detection of plug opening by the plug opening detection unit. The vehicle suspension system according to item (16), wherein the hydraulic pressure is increased.
As the above-mentioned “plug opening instruction unit”, a speaker instructing by voice or a display instructing by display is desirable, but a buzzer or a lamp may be used. It should be noted that the plug should be opened in accordance with instructions from the buzzer or lamp in a manual or the like. The “plug open detection unit” includes a sensor that outputs different signals depending on whether the plug is opened or closed, or an input device that includes an operation member that is operated by an operator after the plug is opened. Can be adopted.

  Hereinafter, embodiments of the claimable invention will be described 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 suspension system as an embodiment of the claimable invention. In this vehicle suspension system, as shown in FIG. 1, suspension cylinders 10FL are respectively provided between the wheel holding devices 6FL, FR, RL, RR for holding the front, rear, left and right wheels 4FL, FR, RL, RR and the vehicle body 8. , FR, RL, RR are provided together with a suspension spring (not shown). The suspension cylinders 10FL, FR, RL, RR are actuated by hydraulic fluid. Hereinafter, when it is necessary to distinguish the suspension cylinder 10 or the like, it is used with symbols FL, FR, RL, and RR representing wheel positions, and when there is no need to distinguish between them, they are used without a symbol.
The suspension cylinders 10FL, FR, RL, and RR have the same structure, and each includes a housing 11, a piston 12 fitted inside the housing 11 so as to be relatively movable, and a piston rod 14. The rod 14 is connected to the wheel holding device 6 and the housing 11 is connected to the vehicle body 8 so as not to move relative to each other in the vertical direction. The piston 12 is provided with a communication path 20 that communicates the two liquid chambers 16 and 18 partitioned by the piston 12, and the communication path 20 is provided with a throttle. The throttle generates a damping force corresponding to the relative moving speed of the piston 12 with respect to the housing 11 (the flow rate of the working fluid flowing through the throttle). The suspension cylinder 10 functions as a shock absorber.

  Individual passages 22FL, FR, RL, and RR are connected to the liquid chambers 16 of the suspension cylinders 10FL, FR, RL, and RR, respectively. In each of the individual passages 22FL, FR, RL, RR, the accumulators 24FL, FR, RL, RR and the accumulators 26FL, FR, RL, RR and the accumulators 26FL, FR, RL, RR are connected in parallel to each other corresponding to each of the suspension cylinders 10FL, FR, RL, RR. And are connected. Further, spring constant switching valves 28FL, FR, RL, and RR are provided between the suspension cylinders 10FL, FR, RL, and RR and the accumulators 26FL, FR, RL, and RR, respectively.

Each of these accumulators 24 and 26 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 passage 22 communicates with one volume change chamber of the partition member. The other volume change chamber is provided with an elastic body, and the volume of the other volume change chamber decreases due to the increase in the volume of the one volume change chamber, thereby generating an elastic force. Can be. The accumulators 24 and 26 can be bellows type, bladder type, piston type, or the like.
In this embodiment, the accumulator 24 has a larger spring constant than the accumulator 26. Hereinafter, the accumulator 24 is referred to as a high-pressure accumulator, and the accumulator 26 is referred to as a low-pressure accumulator. In this embodiment, the spring constant switching valve 28 is a seating valve, and is opened and closed by seating / separating a valve seat (not shown). The spring constant switching valve 28 is a normally open electromagnetic opening / closing valve, and the spring constant is switched by the control of the spring constant switching valve 28.

  The individual passages 22FL, FR, RL, and RR are provided with variable throttles 30FL, FR, RL, and RR, respectively. As described above, the hydraulic fluid flows in and out in the liquid chamber 16 by the vertical movement of the wheel holding devices 6FL, FR, RL, and RR relative to the vehicle body 8. In this case, the individual passage 22 is provided by the variable throttle 30. By controlling the flow path area, the damping force generated in the suspension cylinder 10 is controlled. In the present embodiment, a damping force adjusting mechanism is configured by the variable diaphragm 30 and the like.

  Each of the suspension cylinders 10FL, FR, RL, RR is connected to the control cylinder 48 via individual passages 22FL, FR, RL, RR. The control cylinder 48 includes a piston assembly 50 formed by connecting three pistons, and a cylinder housing 51 that accommodates the piston assembly 50 in a liquid-tight and slidable manner. The piston assembly 50 includes, in order from the right side in FIG. 1, a first piston 52, a second piston 53, and a third piston 54, and the first piston 52 and the second piston 53, and the second piston 53 and the third piston 54. Are connected in series by connecting rods 56 and 58, respectively.

The cylinder housing 51 includes a stepped cylinder bore having a large-diameter portion and a small-diameter portion, and four liquid chambers are formed in the housing 51 by fitting the piston assembly 50 into the cylinder bore. . The second piston 53 is fitted to the large diameter portion of the cylinder bore, and the first piston 52 and the third piston 54 are fitted to the small diameter portion, respectively. Therefore, the diameters of the first piston 54 and the third piston 54 are smaller than the diameter of the second piston 53. The diameters of the first piston 52 and the third piston 54 are the same.
The opposite side of the first piston 52 from the second piston 53 is the first liquid chamber 60, the first piston 52 and the second piston 53 are between the second liquid chamber 61, and the second piston 53 and the third piston 54. Is the third liquid chamber 62, and the third piston 54 is the fourth liquid chamber 63 on the opposite side of the second piston 53. In the first piston 52, the first liquid chamber 60 side is an outer pressure receiving surface 65, and the second liquid chamber 61 side is an inner pressure receiving surface 66. Further, in the second piston 53, the second liquid chamber 61 side is the inner pressure receiving surface 67, the third liquid chamber 63 side is the inner pressure receiving surface 68, and in the third piston 54, the third liquid chamber 62 side is the inner pressure receiving surface. A surface 69 is formed, and the fourth liquid chamber 63 side is an outer pressure receiving surface 70.

The outer pressure receiving surface 65 receives the fluid pressure of the fluid chamber 16 of the suspension cylinder 10FR of the right front wheel 4FR communicating with the first fluid chamber 60 (hereinafter referred to as the fluid pressure of the suspension cylinder), and the outer pressure receiving surface 70 is left. The hydraulic pressure of the suspension cylinder 10FL of the front wheel 4FL is received. In the present embodiment, the diameters of the first piston 52 and the third piston 54 are equal, and the pressure receiving areas of the outer pressure receiving surface 65 and the outer pressure receiving surface 70 are also equal.
Further, the suspension cylinder 10RL of the left rear wheel 4RL is connected to the second liquid chamber 61 formed between the first piston 52 and the second piston 53 adjacent to each other by the individual passage 22RL, and they are opposed to each other. The inner pressure receiving surface 66 of the first piston 52 and the inner pressure receiving surface 67 of the second piston 53 receive the hydraulic pressure of the suspension cylinder 10RL of the left rear wheel 4RL. The force that the hydraulic pressure acting on the second liquid chamber 61 applies to the first piston 52 having the smaller diameter of the two pistons is the inner pressure receiving force of the first piston 52 of the inner pressure receiving surface 67 of the second piston 53 having the larger diameter. The force applied to the portion of the pressure receiving area equal to the surface 66 is offset. Therefore, the effective pressure receiving area with respect to the fluid pressure of the second fluid chamber 61 of the piston assembly 50 is a size obtained by subtracting the pressure receiving area of the inner pressure receiving surface 66 of the first piston 52 from the pressure receiving area of the inner pressure receiving surface 67 of the second piston 53. It becomes. Similarly, the suspension cylinder 10RR of the right rear wheel 4RR is connected to the third liquid chamber 62 by the individual passage 22RR, and the effective pressure receiving area with respect to the liquid pressure of the third liquid chamber 62 of the piston assembly 50 is the second pressure chamber. The pressure receiving area of the inner pressure receiving surface 68 of the piston 53 is subtracted from the pressure receiving area of the inner pressure receiving surface 68 of the third piston 54. That is, the force expressed by the product of the hydraulic pressure of the second liquid chamber 61 and the third liquid chamber 62 and the above-described effective pressure receiving area acts on the piston assembly 50, respectively.

  As described above, since the diameter of the first piston 52 and the diameter of the third piston 54 are equal, the effective pressure receiving area for the second liquid chamber 61 and the effective pressure receiving area for the third liquid chamber 62 of the piston assembly 50 are also equal. . Furthermore, in the present embodiment, the pressure receiving area for the first liquid chamber 60 and the fourth liquid chamber 63 is smaller than the effective pressure receiving area for the second liquid chamber 61 and the third liquid chamber 62 of the piston assembly 50. The diameter of the second piston 53 is determined.

The vehicle suspension system is provided with a vehicle height adjusting device 74. The vehicle height adjusting device 74 includes a high pressure source 76, a reservoir 78 as a low pressure source, an individual control valve device 80, and the like.
The high-pressure source 76 includes a pump device 84 having a pump 81 and a pump motor 82, a pressure accumulator 86, and the like. The pump device 84, the pressure accumulator 86, and the like are provided in the control passage 88. The hydraulic fluid in the reservoir 78 is pumped up and discharged by the pump 81 and stored in a pressure-accumulating accumulator 86 in a pressurized state. The accumulator 86 for pressure accumulation is connected to the control passage 88 via a pressure accumulation control valve 90 that is a normally closed electromagnetic on-off valve. A hydraulic pressure source pressure sensor 92 is provided in the control passage 88. According to the hydraulic pressure source pressure sensor 92, the discharge pressure of the pump 81 and the accumulator pressure of the accumulator 86 can be detected.
A check valve 94 and a silencing accumulator 96 are provided on the discharge side of the pump 81 in the control passage 88. An outflow passage 104 that connects the high pressure side and the low pressure side of the pump 81 is provided, and an outflow control valve 106 that is a normally closed electromagnetic on-off valve is provided in the outflow passage 104.

  The outflow control valve 106 can be a mechanical on-off valve. For example, a pilot-type on-off valve that uses the discharge pressure of the pump 81 as a pilot pressure is set to a closed state when the discharge pressure increases due to the operation of the pump 81, and is set to an open state in other cases.

The individual control valve device 80 includes individual control valves 110FL, FR, RL, RR provided in the individual control passages 108FL, FR, RL, RR. The individual control paths 108FL, FR, RL, and RR are paths that connect the control path 88 and the individual paths 22FL, FR, RL, and RR, respectively. The suspension cylinder 10 and the control passage 88 are connected to each other by the individual control passage 108 and the individual passage 22. In the control passage 88, a common on-off valve 130 is provided in common between the four individual control valves 110 between the hydraulic pressure source 120 constituted by the high pressure source 76, the reservoir 78, and the like and the individual control valve 110. ing. Further, a hydraulic pressure sensor 132 is provided in common to the four individual control valves 110 between the common on-off valve 130 and the four individual control valves 110.
These individual control valves 110FL, FR, RL, RR, and common on-off valve 130 are normally closed electromagnetic on-off valves, and individually control the individual control valves 110FL, FR, RL, RR when the common on-off valve 130 is open. Thus, in each of the wheels 4FL, FR, RL, RR, the wheel holding device 6FL, FR, RL, RR and the corresponding part of the vehicle body 8 (the part corresponding to the suspension cylinders 10FL, FR, RL, RR) The vehicle height, which is the distance between, can be controlled independently.

  This vehicle suspension system is controlled by a suspension ECU 200 mainly composed of a computer. The suspension ECU 200 includes an execution unit, a storage unit, an input / output unit, and the like. The input / output unit includes a coil of the spring constant switching valve 28 and the variable throttle 30, and a vehicle height adjusting device 74 (control valve 90 for pressure accumulation, individual control). A valve 110, a common on-off valve 130, a coil of the outflow control valve 106, a pump motor 81, and the like) are connected via a drive circuit (not shown). Also connected to the input / output section are a fluid source pressure sensor 92, a vehicle height sensor 220 provided for each of the front, rear, left and right wheels, respectively for detecting the vehicle height, a traveling state detecting device 222 for detecting the traveling state of the vehicle, etc. In addition, a notification device 226 is connected.

The traveling state detection device 222 detects the traveling state of the vehicle, and in this embodiment, includes a steering angle sensor that detects the steering angle of the vehicle and a vehicle speed sensor that detects the traveling speed of the vehicle. Alternatively, the traveling state detection device 222 includes at least one of a longitudinal acceleration sensor that detects a braking / driving state (deceleration / acceleration state), a lateral acceleration sensor that detects a turning state, and a traveling speed sensor. It can also be used. The turning state can also be detected by a yaw rate sensor.
The notification device 226 may include at least one of a display that displays information on a screen, a speaker that emits sound, a buzzer, a lamp, and the like.

  The storage unit stores various programs such as a control cylinder malfunction detection routine represented by the flowchart of FIG.

The operation of the vehicle suspension system configured as described above will be described.
In the control cylinder 48, the piston assembly 50 is represented by the product of the force corresponding to the hydraulic pressure of the suspension cylinder 10 provided on each wheel (each hydraulic pressure and the effective pressure receiving area of the pressure receiving surface corresponding to them). In the stationary state, they are balanced.
When the distance between the wheel holding device 6 and the vehicle body 8 increases on the front side of the vehicle and decreases on the rear side (for example, when the vehicle accelerates rapidly), the left and right front wheels 4FL, 4FR suspension cylinders The hydraulic pressure of 10FL and 10FR is reduced, and the hydraulic pressure of the suspension cylinders 10RL and 10RR of the left and right rear wheels 4RL and 4RR is increased. Therefore, the hydraulic pressure acting on the outer pressure receiving surfaces 65 and 70 of the first piston 52 and the third piston 54 is reduced, and the hydraulic pressure acting on the inner pressure receiving surfaces 67 and 68 of the second piston 52 is increased. In this case, since the balance of the forces acting on the piston assembly 50 does not change, the piston assembly 50 does not move, and the suspension cylinders 10 are equal to being independent of each other, resulting in a large damping force. Is generated, and the pitching of the vehicle is effectively suppressed.

When rolling on the vehicle body, for example, when the distance between the wheel holding device 6 and the vehicle body 8 increases on the left side of the vehicle and decreases on the right side (for example, when turning left), the left front wheel 4FL, the left rear wheel 4RL The hydraulic pressures of the suspension cylinders 10FL and 10RL are reduced, and the hydraulic pressures of the suspension cylinders 10FR and 10RR of the right front wheel 4FR and the right rear wheel 4RR are increased. Accordingly, the hydraulic pressure acting on the outer pressure receiving surface 70 of the third piston 54 and the inner pressure receiving surface 67 of the second piston 53 is reduced, and the outer pressure receiving surface 65 of the first piston 52 and the inner pressure receiving surface 68 of the second piston 53 are reduced. The fluid pressure acting on the fluid increases. For simplification, if the balance of the forces acting on the piston assembly 50 does not change even during rolling, the suspension cylinders 10 are almost independent from each other (in extreme terms, the control cylinder 48). And a large damping force is generated in each of the suspension cylinders 10 with the movement of the piston assembly 50, and the rolling is effectively suppressed.
However, in the present embodiment, as described above, the pressure receiving area for the first liquid chamber 60 and the fourth liquid chamber 63 is greater than the effective pressure receiving area for the second liquid chamber 61 and the third liquid chamber 62 of the piston assembly 50. Therefore, the piston assembly 50 moves from the fourth fluid chamber 63 toward the first fluid chamber 60 (to the right in FIG. 1) in accordance with the fluid pressure change, and the suspension cylinder of the right front wheel 4FR. 10FR is less likely to contract than the suspension cylinder 10RR of the right rear wheel 4RR, and the suspension cylinder 10FL of the left front wheel 4FL is less likely to extend than the suspension cylinder 10RL of the left rear wheel 4RL. Rolling is suppressed while the roll rigidity on the front wheel side is increased relative to the roll rigidity on the rear wheel side.

  When an input is applied to one of the front, rear, left, and right wheels from the road surface, for example, a force is applied to reduce the distance between the wheel holding device 6 and the vehicle body 8 to the suspension cylinder 10FL provided on the left front wheel 4FL. (For example, when the left front wheel FL rides on the road bump) or a force that moves them in the same phase to the wheels on the diagonal position of the vehicle body 8, such as the suspension cylinders 10FL, 10RR with the wheel holding device 6 and the vehicle body 8 When a force for reducing the interval is applied, the hydraulic pressures of the suspension cylinders 10FL and 10RR are increased, and the hydraulic pressures of the suspension cylinders 10FR and 10RL are decreased. Accordingly, the hydraulic pressure acting on the outer pressure receiving surface 70 of the third piston 54 and the inner pressure receiving surface 68 of the second piston 52 increases, and the inner pressure receiving surface 67 of the second piston 52 and the outer pressure receiving surface of the first piston 52 are increased. The hydraulic pressure acting on 65 is lowered, the balance of force is broken in the piston assembly 50, and it moves to the right in FIG. As a result, the volumes of the fourth liquid chamber 63 and the third liquid chamber 62 are increased, and the volumes of the second liquid chamber 61 and the first liquid chamber 60 are decreased. Accordingly, the hydraulic fluid flows out from the suspension cylinders 10FL and 10RR and flows into the suspension cylinders 10FR and 10RL, as if the two suspension cylinders 10FL and 10RR and the two suspension cylinders 10FR and 10RL are communicated with each other via the control cylinder 48. Therefore, the suspension cylinders 10FL and 10RR are easily contracted and the suspension cylinders 10FL and 10RR are easily allowed to extend. So-called articulation becomes easy.

In the vehicle suspension system, the vehicle height corresponding to the four wheels 4 is controlled by the vehicle height adjusting device 74.
For example, when the vehicle height, which is the distance between the wheel holding device 6FL and the portion corresponding to the left front wheel 4FL of the vehicle body 8, is increased for the left front wheel 4FL, the pressure accumulation control valve 90 and the common on-off valve 130 are opened. At the same time, the individual control valve 110FL is opened, and the hydraulic fluid is supplied from the pressure accumulator 86 to the suspension cylinder 10FL. When the actual vehicle height reaches the target value, the common on-off valve 130, the individual control valve 110FL, and the pressure accumulation control valve 90 are closed. Further, the pump device 84 is operated, and the hydraulic fluid discharged from the pump 81 can be supplied to the suspension cylinder 10FL.

  When lowering the vehicle height, the common on-off valve 130 and the individual control valve 110FL are opened, and the outflow control valve 106 is opened, so that the hydraulic fluid flows out from the suspension cylinder 10FL to the reservoir 78. When the actual vehicle height reaches the target value, the common on-off valve 130, the individual control valve 110FL, and the outflow control valve 106 are closed.

Furthermore, in this vehicle suspension system, it is detected whether the control cylinder 48 is operating satisfactorily.
The control cylinder malfunction detection routine shown in the flowchart of FIG. 3 is executed at predetermined time intervals. In step 1 (hereinafter abbreviated as S1. The same applies to other steps), the steering angle detected by the steering angle sensor and the vehicle speed detected by the vehicle speed sensor are read. In S2, it is determined whether or not the vehicle is in a steady turning state based on the steering angle and the vehicle speed. If the vehicle is not in a steady turning state and the determination in S2 is NO, one execution of this routine ends. If the vehicle is in a steady turning state and the determination in S2 is YES, the standard hydraulic pressure change amount of each fluid chamber of the four suspension cylinders 10 in the steady turning state is acquired in S3. The suspension ECU 200 includes a plurality of standard turning states in which the control cylinder 48 operates satisfactorily and a plurality of standard turning amounts corresponding to each of the four suspension cylinders 10 corresponding to each of the steady turning states. The relationship with the hydraulic pressure change amount is acquired and stored in advance by actual measurement, and the standard hydraulic pressure change amount in each steady turning state is acquired from the above relationship. However, the standard hydraulic pressure change amount of each fluid chamber of the four suspension cylinders 10 in each steady turning state may be obtained by calculation and stored in the storage unit.

  In S4, the actual fluid pressures in the fluid chambers of the four suspension cylinders 10 are read. The fluid pressures in the fluid chambers of the four suspension cylinders 10 are acquired as follows. With the common on-off valve 130 kept closed, the four individual control valves 110 are sequentially opened and closed, whereby the hydraulic pressures in the respective liquid chambers of the four suspension cylinders 10 are sequentially detected by the hydraulic pressure sensor 132. Based on the actual fluid pressures in the respective fluid chambers of the four suspension cylinders 10 thus detected, the actual fluid pressure change amounts in the fluid chambers of the four suspension cylinders 10 are acquired.

  In S5, the standard hydraulic pressure change obtained for each of the four fluid chambers of the four suspension cylinders 10 in S3 is compared with the actual hydraulic pressure change, and whether the actual hydraulic pressure change is within the allowable range. It is determined whether or not. If the determination in S5 is NO, there is a high possibility that a malfunction of the control cylinder 48 has occurred, and therefore an alarm is issued by the notification device 226 in S6. The alarm can be at least one of displaying the fact on the display and activating sound or light. If the determination in S5 is YES, the control cylinder 48 is operating well, and one execution of this routine is completed.

  According to the present embodiment, it is possible to detect whether or not the control cylinder 48 that cannot be visually confirmed is operating well. If the operation is defective, the driver can be repaired by issuing an alarm. it can. Moreover, since the hydraulic pressure of each fluid chamber of the four suspension cylinders 10 can be detected by one hydraulic pressure sensor 132, the cost reduction effect can also be obtained.

In this embodiment, the piston assembly 50 constitutes a control piston. Further, the steering angle sensor of the traveling state detection device 222 and the portion of the suspension ECU 200 that reads the steering angle of S1 in the control cylinder operation failure detection routine of FIG. A sensor and the part which reads the vehicle speed of said S1 comprise the vehicle speed acquisition part. Further, the portion of the suspension ECU 200 that executes S2 constitutes a steering angle / vehicle speed dependence acquisition unit. In this embodiment, the steering angle acquisition unit and the vehicle speed acquisition unit constitute a traveling state detection unit, and the traveling state detection unit constitutes a traveling state dependency acquisition unit together with the steering angle / vehicle speed dependency acquisition unit. Yes. The steady turning state detection unit is an aspect of the state change cause detection unit, and includes the traveling state detection unit and the traveling state dependence acquisition unit. The portion of the suspension ECU 200 that executes S4 constitutes a hydraulic pressure detection unit that is a real state detection unit, and the portion that executes S5 and S6 is a kind of hydraulic pressure-dependent operation failure determination unit that is an operation failure determination unit. The determination unit is configured. The state change cause detection unit, the actual state detection unit, and the operation failure determination unit constitute a control cylinder operation failure detection device.
The high pressure source 76 including the pump device 84, the reservoir 78, and the like of the vehicle height adjusting device 74 constitute a hydraulic fluid supply / discharge device, the individual control valve 110 constitutes an individual open / close valve, and the hydraulic fluid supply / discharge device in the suspension ECU 200. And the part which controls an individual on-off valve comprises the vehicle height adjustment control part. Further, the common on-off valve 130 constitutes a shut-off means, and the portion that controls the common on-off valve 130, the individual control valve 110, and the hydraulic pressure sensor 132 in the suspension ECU 200 constitutes a hydraulic pressure detection control unit. The blocking means, the hydraulic pressure sensor 132, and the hydraulic pressure detection control unit constitute a hydraulic pressure detection unit.

In addition, in other words, the ratio of the hydraulic pressure change amounts of at least two liquid chambers of the four suspension cylinders 10 due to the change from the straight traveling state to the steady turning state, or the liquid in the at least two liquid chambers in the steady turning state. It is also possible to detect a malfunction of the control cylinder based on the pressure ratio.
For example, the actual change in hydraulic pressure of the suspension cylinder 10 on the front wheel side (for example, the front side outside the turn) and the rear wheel side (for example, the front side on the outside of the turn) accompanying the transition from the straight traveling state to the steady turning state in a state where the operation of the control cylinder 48 is normal. For example, a standard ratio that is a ratio of the actual hydraulic pressure change amount of the suspension cylinder 10 of the rear wheel of the turning outer side) is acquired in advance by experiment or measurement, and is stored in the storage unit of the suspension ECU 200. Then, S3 in the above embodiment is a step of reading the standard ratio stored in the storage unit, while S5 is the front wheel side calculated from the fluid pressures of the fluid chambers of the four suspension cylinders 10 read in S4. The ratio of the actual hydraulic pressure change amount of the suspension cylinder 10 between the rear wheel side and the rear wheel side is compared with the standard ratio, and the actual hydraulic pressure change ratio is different from the standard ratio by a set amount or a set ratio or more. In addition, it is determined that the operation of the control cylinder 48 is abnormal.

  Alternatively, the ratio of the actual hydraulic pressure of the suspension cylinder 10 between the turning inner side and the outer turning side on the front wheel side in the steady turning state and the ratio of the actual hydraulic pressure of the suspension cylinder 10 between the inner turning side and the outer turning side on the rear wheel side. A certain standard ratio is acquired in advance by experiment or measurement, and is stored in the storage unit of the suspension ECU 200. Then, S3 in the above embodiment is a step of reading the standard ratio stored in the storage unit, while S5 is the front wheel side calculated from the fluid pressures of the fluid chambers of the four suspension cylinders 10 read in S4. When the ratio of the actual hydraulic pressure of the suspension cylinder 10 to the rear wheel side is compared with the standard ratio, and the actual hydraulic pressure ratio is different from the standard ratio by a set amount or a set ratio, the control cylinder It can also be determined that the operation of 48 is abnormal.

  Furthermore, it is a ratio between the actual hydraulic pressure of the suspension cylinder 10 on the front wheel side (for example, the front side on the outer side of the turn) and the actual hydraulic pressure of the suspension cylinder 10 on the rear wheel side (for example, the rear wheel on the outer side of the turn) in the steady turning state. The standard ratio is acquired in advance by experiment or measurement, and is stored in the storage unit of the suspension ECU 200. Then, S3 in the above embodiment is a step of reading the standard ratio stored in the storage unit, while S5 is the front wheel side calculated from the fluid pressures of the fluid chambers of the four suspension cylinders 10 read in S4. When the ratio of the actual hydraulic pressure of the suspension cylinder 10 to the rear wheel side is compared with the standard ratio, and the actual hydraulic pressure ratio is different from the standard ratio by a set amount or a set ratio, the control cylinder It can also be determined that the operation of 48 is abnormal.

  FIG. 4 shows a control cylinder operation failure detection routine in a vehicle suspension system as another embodiment. The configuration of the entire vehicle suspension system can be the same as that shown in FIG. The control cylinder operation failure detection routine shown in FIG. 4 is executed at predetermined time intervals. In S10, vehicle heights corresponding to the four wheels 4 detected by the vehicle height sensor 220 are read. In S11, for one of the four wheels 4, it is determined whether or not a change of a set amount or more is detected in the vehicle height corresponding to the one wheel. If the determination in S11 is NO, one execution of this routine ends. If YES, the standard hydraulic pressure change amount of each fluid chamber of the four suspension cylinders 10 is acquired in S12. In the suspension ECU 200, the relationship between the vehicle height of the four wheels and the standard hydraulic pressure change amount that is the hydraulic pressure change amount of each liquid chamber of the corresponding four suspension cylinders 10 in a state where the operation of the control cylinder 48 is good. Is obtained and stored by actual measurement, and the standard hydraulic pressure change amount of each fluid chamber of the four suspension cylinders 10 is obtained from the above relationship. However, the standard hydraulic pressure change amount of each liquid chamber of the four suspension cylinders 10 may be obtained by calculation.

In S13, the actual fluid pressures in the fluid chambers of the four suspension cylinders 10 are read. The actual hydraulic pressure is acquired in the same manner as in the embodiment shown in FIGS. Based on the actual hydraulic pressures in the respective fluid chambers of the four suspension cylinders 10 thus detected, the actual hydraulic pressure change amount is acquired.
Then, in S14, the standard hydraulic pressure change amount of the fluid chamber of the suspension cylinder 10 acquired in S12 is compared with the actual hydraulic pressure change amount, and whether or not the actual hydraulic pressure change amount is within an allowable range. Determined. For example, whether or not the difference between the standard hydraulic pressure change amount and the actual hydraulic pressure change amount in the fluid chamber of the suspension cylinder 10 corresponding to one wheel in which a vehicle height change equal to or greater than the set amount is detected in S11 is equal to or greater than the set amount Is determined. However, the amount of change in the hydraulic pressure of a wheel other than one wheel in which a change in vehicle height greater than the set amount is detected and the change in the hydraulic pressure in the fluid chamber of the suspension cylinder 10 is the largest is the change in the standard hydraulic pressure in the fluid chamber. The standard hydraulic pressure change amount and the actual hydraulic pressure change amount of each liquid chamber of the suspension cylinder 10 corresponding to a plurality of wheels may be compared with each other. If the actual fluid pressure change amount in the fluid chamber of the suspension cylinder 10 is different from the standard fluid pressure change amount exceeding the allowable range, there is a high possibility that the control cylinder 48 has malfunctioned. Be emitted. If the determination in S14 is YES, the control cylinder 48 is operating normally, and one execution of this routine ends.

  In this embodiment, when a vehicle height change of more than a set amount occurs due to a vehicle riding on a road surface protrusion or dropping into a road surface recess, that wheel is handled. When the actual fluid pressure change amount in the fluid chamber of the suspension cylinder 10 is different from the expected amount, the malfunction of the control cylinder 48 can be detected.

  In this embodiment, the vehicle height sensor 220 constitutes a vehicle height detection device, and the portion that executes S10 to S12 in the control cylinder operation failure detection routine of the suspension ECU 200 constitutes a one-wheel vehicle height change posture change acquisition unit. Yes. The state change cause detection unit according to the present invention includes the vehicle height detection device and the one-wheel vehicle height change posture change acquisition unit. Further, the portion of the suspension ECU 200 that executes S13 constitutes a hydraulic pressure detection unit, and the portion that executes S14 constitutes a one-wheel vehicle height change determination unit that is a kind of operation failure determination unit.

FIG. 5 shows a vehicle height adjustment routine executed in a vehicle suspension system as still another embodiment. About the structure of the whole vehicle suspension system, it shall be the same as the Example shown in FIG. The vehicle height adjustment routine is executed when the vehicle is stopped.
In S20, the vehicle height corresponding to the four wheels 4 detected by the vehicle height sensor 220 is read. In step S21, a preset set vehicle height is read. For example, when the vehicle has an input device for instructing that the vehicle height should be adjusted in multiple stages such as low, medium, and high, or an input device that can continuously indicate the desired vehicle height. It has an automatic setting unit that automatically sets an appropriate vehicle height according to the road surface condition and the running state of the vehicle (traveling speed, steering state, vehicle body and wheel vibration state, etc.). In some cases, the currently set vehicle height information is read. Subsequently, in S22, the set vehicle height is compared with the actual vehicle height to determine whether or not the vehicle height adjustment is necessary. If the actual vehicle height is not within the allowable range with respect to the set vehicle height and vehicle height adjustment (either vehicle height increase or vehicle height decrease) is necessary, the determination in S22 is YES, and in S23 It is then determined whether it is necessary to detect a control cylinder malfunction. In the present embodiment, it is determined that it is necessary to detect a control cylinder malfunction if the condition that a set period or more has elapsed from the date and time when the previous control cylinder malfunction was detected. The detection of the control cylinder malfunction may be performed when the vehicle is started for the first time in a day, or when it is instructed by an input operation by the driver. You may make it do. If the detection of the control cylinder malfunction is unnecessary, the determination in S23 is NO, and normal vehicle height adjustment is performed in S24. Since normal vehicle height adjustment is known, the description thereof is omitted here.

  If it is necessary to detect a malfunction of the control cylinder, the vehicle height corresponding to a predetermined one of the four wheels 4 (or any one of the wheels) may be changed by a set amount in S25. The set amount is larger than the amount of vehicle height adjustment that is executed alternately for the front wheel side and the rear wheel side in normal vehicle height adjustment, or the amount of vehicle height adjustment that is sequentially executed for each wheel. It is determined in advance as an adjustment amount exclusively for detection of control cylinder operation failure. In S26, the standard hydraulic pressure change amounts of the respective fluid chambers of the four suspension cylinders 10 are acquired. Similar to the embodiment shown in FIG. 4, the vehicle height of the four wheels stored in advance in the suspension ECU 200 in a state where the operation of the control cylinder 48 is good, and the liquid chambers of the corresponding four suspension cylinders 10 are stored. From the relationship with the standard fluid pressure variation, the standard fluid pressure variation of each fluid chamber of the four suspension cylinders 10 is acquired. In addition, when the vehicle height adjustment of the adjustment amount dedicated to the detection of the control cylinder operation failure is performed, the suspension cylinder in which the largest hydraulic pressure difference occurs between the state in which the control cylinder operates well and the state in which the operation failure occurs It is also possible to acquire the standard hydraulic pressure change amount only for.

Subsequently, in S27, the actual hydraulic pressures in the liquid chambers of the four suspension cylinders 10 detected by the hydraulic pressure sensor 132 are read. In S28, the standard hydraulic pressure change amount is compared with the actual hydraulic pressure change amount for each of the plurality of suspension cylinders 10, and the actual hydraulic pressure change amount is within an allowable range with respect to the standard hydraulic pressure change amount. It is determined whether or not.
Of the four wheels, one wheel whose set amount has been changed (one wheel having the largest vehicle height change) or any other wheel that has the largest hydraulic pressure change corresponds to that wheel. It is also possible to determine whether or not the actual fluid pressure change amount in the fluid chamber of the suspension cylinder 10 is within the allowable range of the standard fluid pressure change amount. Alternatively, as described in the embodiment of FIGS. 1 and 3, it is determined whether or not the ratio of the actual fluid pressure change amounts of the fluid chambers of the plurality of suspension cylinders 10 is within an allowable range including the set ratio. It may be performed.

  If the actual hydraulic pressure change amount of the fluid chambers of the four suspension cylinders 10 is different from the standard hydraulic pressure change amount beyond the allowable range, it is highly possible that the control cylinder 48 has malfunctioned. An alarm is issued at. If the determination in S28 is YES, it is determined that the control cylinder 48 is operating normally, S29 is skipped, and S30 and subsequent steps are executed. In S30, the date and time when the control cylinder operation failure was determined is stored in the storage unit of the suspension ECU 200 together with the determination result. Subsequently, in S31, the routine proceeds to normal vehicle height adjustment.

  In this embodiment, when it is necessary to adjust the vehicle height, first, the set amount of the vehicle height is changed for only one wheel, and the actual fluid pressure change amount of the fluid chambers of the plurality of suspension cylinders 10 is scheduled. If it is detected that the control cylinder 48 is different, the malfunction of the control cylinder 48 is detected.

  In the present embodiment, the portion that executes S25 in the vehicle height adjustment routine of the suspension ECU 200 constitutes the single-wheel vehicle height adjustment control unit, and the portion that detects the execution of the single-wheel vehicle height control by the vehicle height sensor 220 is a part of the vehicle. A one-wheel vehicle height adjustment detection unit as a height adjustment detection unit is configured. In addition, the part that executes S26 of the suspension ECU 200 partially constitutes a vehicle height adjustment-induced posture change estimation unit, the part that executes S27 constitutes a hydraulic pressure detection unit, and the part that executes S28 (when the vehicle is stopped) ) A partial vehicle height adjustment determination unit which is an operation failure determination unit is configured.

  FIG. 6 shows a control cylinder operation failure detection routine executed in a vehicle suspension system as another embodiment. About the structure of the whole vehicle suspension system, it shall be the same as the Example shown in FIG. In S40, it is determined whether or not the control cylinder operation failure detection is necessary. In this embodiment, it is executed when instructed by the operation of the input device by the operator or driver of the maintenance shop. The detection of the control cylinder malfunction may be performed when a set period has elapsed from the date and time when the previous control cylinder malfunction detection was performed, or the engine etc. When the operation of the drive source is started, it may be determined that it is necessary to detect a malfunction of the control cylinder.

  If the detection of the control cylinder operation failure is unnecessary, the determination in S40 is NO and one execution of this routine is completed. If it is necessary to detect a malfunction of the control cylinder, the determination in S40 is YES, and in S41, it is determined whether or not the vehicle is stopped based on the detection by the traveling state detection device 222. If the determination in S41 is NO, one execution of this routine ends. If the vehicle is stopped, the determination in S41 is YES, and in S42, all the fluid chambers of the four suspension cylinders 10 are set to atmospheric pressure, and in S43, any one of the four suspension cylinders 10 is suspended. The operator is instructed to open a plug provided corresponding to the liquid chamber of the cylinder 10 by voice or a screen display by the notification device 226. In S44, it is determined whether or not the plug is actually opened. The vehicle suspension system is provided with a plug open / close sensor for detecting the opening / closing of the plug. If the sensor detects that the plug is opened, the determination in S44 is YES, and S45. The control is performed to increase the hydraulic pressure in the liquid chamber of the suspension cylinder 10 which is determined in advance by a set amount. The predetermined suspension cylinder 10 has a relative positional relationship in which the working fluid flows into the fluid chamber of the suspension cylinder 10 with the plug opened when the fluid pressure in the fluid chamber is increased by a set amount. Cylinder 10 is selected. If the control cylinder 48 is operating well, the operator can confirm that hydraulic fluid flows out from the plug of the suspension cylinder 10. However, when the outflow of hydraulic fluid from the plug cannot be confirmed, it is detected that the control cylinder 48 has malfunctioned.

  In S47, the notification device 226 instructs the operator to close the opened plug. If the determination in step S44 is NO because the plug is not opened, it is determined in step S46 whether or not detection of control cylinder operation failure is to be stopped. If the detection of the control cylinder malfunction is not stopped, the process returns to S44 and waits for the plug to be opened. If the determination in S46 is YES, such as when the operator inputs a stop of detection of control cylinder malfunction by the input device, S47 is executed. In S48, it is determined whether or not the plug is closed. If it is not determined that the plug is closed by the detection of the plug open / close sensor, the process waits until the plug is closed. If the plug is closed, the vehicle height is adjusted in S49.

  According to the present embodiment, whether the operation of the control cylinder 48 is good or bad by the operator confirming the outflow state of the hydraulic fluid from the loosened plug of the suspension cylinder 10 as described above. Is detected.

  In the present embodiment, the part that executes S41 of the control cylinder operation failure detection routine of the running state detection device 222 and the suspension ECU 200 constitutes the stop state detection unit. Further, the portion of the suspension ECU 200 that executes S42 and the vehicle height adjusting device 74 (particularly the reservoir 78, the individual control valve device 80, etc.) constitute a hydraulic pressure elimination control unit, and the portion that executes S45 and the vehicle height adjusting device 74 ( In particular, the high pressure source 76, the individual control valve device 80, etc.) constitute a hydraulic pressure increase control unit. Further, the portion of the suspension ECU 200 that executes S43 constitutes a plug opening support portion, and the portion that executes S44 of the routine and the plug open / close sensor constitutes a plug opening detection portion.

FIG. 7 shows a center cylinder malfunction detection routine executed in a vehicle suspension system as another embodiment. This routine is also repeatedly executed at regular intervals. About the structure of the whole vehicle suspension system, it shall be the same as the Example shown in FIG.
In S60, it is determined whether or not the vehicle is stopped. In S61, it is determined whether or not the vehicle height is being adjusted. If the determination result of S60 is NO and the determination result of S61 is YES, this is not suitable for detecting the malfunction of the control cylinder by this routine. Therefore, in S62, the flag is turned off, the memory for storing the hydraulic pressure of the suspension cylinder is cleared, etc. Then, an end process is performed and one execution of this routine is ended.

  On the other hand, if the determination result in S60 is YES and the determination result in S61 is NO, it is determined in S63 whether or not the flag is ON. However, the flag is OFF in the initial setting (not shown). The result is initially NO, and it is determined in S64 whether or not the vehicle height has changed. The vehicle height changes when the vehicle is stopped and the vehicle height is not adjusted when an occupant gets on or off or loads and unloads the baggage. If the determination result is NO, the four suspension cylinders at S65 The fluid pressures in the ten fluid chambers and the corresponding vehicle heights are read and stored. If YES, the flag is turned on in S66. After that, the determination result in S63 is YES, so S64 and S66 are bypassed and S67 is executed. It is determined whether or not the vehicle height change amount after the flag is turned on has reached a set amount or more. This determination is based on the absolute value of the vehicle height change amount, which is the difference between the vehicle height corresponding to the four suspension cylinders 10 stored in S65 immediately before the flag is turned ON and the vehicle height read when S67 is executed. This is performed depending on whether at least one of the items exceeds the set amount.

  If the result of the determination is NO, one execution of this routine ends. If YES, the actual amount of change in the hydraulic pressures of the four suspension cylinders 10 is acquired in S68. This acquisition is performed by subtracting the hydraulic pressure read during execution of S68 from the hydraulic pressure of the suspension cylinder 10 stored in S65 immediately before the flag is turned on. Subsequently, in S69, the standard hydraulic pressure change amounts of the four suspension cylinders 10 are acquired. Assuming that the control cylinder 48 is normal, this acquisition is performed by calculating the amount of change in hydraulic pressure that should occur corresponding to the amount of change in vehicle height of the four suspension cylinders 10 calculated in S67. . Then, in S70, it is determined whether or not the four actual hydraulic pressure changes acquired in S68 are within an allowable range with respect to the four standard hydraulic pressure changes acquired in S69. If there is something outside the allowable range, the determination result in S70 is NO, and in S71, an alarm is given to the effect that an abnormal operation has occurred in the control cylinder 48.

According to the present embodiment, the malfunction of the control cylinder 48 is detected particularly well when the load on the left and right sides changes greatly while the vehicle is stopped.
In this embodiment, four vehicle height sensors 220 provided corresponding to each of the four suspension cylinders 10 constitute a vehicle height detection device, and control cylinder operation failure detection routines S63 to S68 of the suspension ECU 200 are executed. The part to perform constitutes a vehicle height-based acquisition unit that acquires a change in the posture of the vehicle body based on the vehicle heights at four locations, and the part that executes S69 and S70 constitutes a malfunction determination unit during stoppage.

In the vehicle suspension system of FIG. 1, the hydraulic pressure sensor 132 is provided in common between the common on-off valve 130 and the four individual control valves 110, so that each of the four suspension cylinders 10 is provided by one hydraulic pressure sensor 132. Instead of this, the hydraulic pressure sensor for detecting the hydraulic pressure in each of the four suspension cylinders 10 is provided as shown in FIG. It is good also as a structure. In the present embodiment, the same components as those in the vehicle suspension system shown in FIG. 1 are denoted by the same reference numerals, and only different portions will be described. As shown in FIG. 2, each of the individual passages 22FL, FR, RL, and RR has the hydraulic pressure of the individual passages 22FL, FR, RL, and RR corresponding to each of the suspension cylinders 10FL, FR, RL, and RR. A passage hydraulic pressure sensor 250 for detecting each is provided.
In the vehicle suspension system configured as shown in FIG. 2, at least one of the routines shown in FIGS. 3, 4, 5, 6, and 7 can be executed.

It is a figure showing the whole vehicle suspension system which is one example of claimable invention. It is a figure which shows the whole vehicle suspension system which is another Example. 3 is a flowchart showing a control cylinder operation failure detection routine stored in a suspension ECU of the vehicle suspension system shown in FIG. 1. It is a flowchart showing the control cylinder operation defect detection routine memorize | stored in suspension ECU of the vehicle suspension system which is another Example. It is a flowchart showing the vehicle height adjustment routine memorize | stored in suspension ECU of the vehicle suspension system which is another Example. It is a flowchart showing the control cylinder operation defect detection routine memorize | stored in suspension ECU of the vehicle suspension system which is another Example. It is a flowchart showing the control cylinder operation defect detection routine memorize | stored in suspension ECU of the vehicle suspension system which is another Example.

Explanation of symbols

  4: Wheel 8: Car body 10: Suspension cylinder 48: Control cylinder 50: Piston assembly 74: Vehicle height adjustment device 76: High pressure source 78: Reservoir 80: Individual control valve device 110: Individual control valve 130: Common on-off valve 132: Fluid pressure sensor 200: Suspension ECU 220: Vehicle height sensor 222: Traveling state detection device 250: Passage fluid pressure sensor

Claims (9)

There are four suspension cylinders provided between the front and rear, left and right four wheels of the vehicle and the vehicle body, and a control piston that operates by receiving the fluid pressure of the four fluid chambers to which the fluid chambers of the suspension cylinders are respectively connected. A vehicle suspension system including a control cylinder,
When a cause of a state change that causes a change in the state of the four suspension cylinders occurs, a change that occurs in the state of the four suspension cylinders depends on whether the control cylinder operates normally or does not operate normally. A vehicle suspension system comprising a control cylinder malfunction detection device that detects malfunction of the control cylinder based on differences. The control cylinder malfunction detection device is
A state change cause detection unit for detecting occurrence of the state change cause;
An actual state detection unit for detecting an actual state that is an actual state of the four suspension cylinders;
An operation failure determination unit that determines that the operation of the control cylinder is defective when the actual state detected by the actual state detection unit and the state change cause detected by the state change cause detection unit do not correspond to each other; The vehicle suspension system according to claim 1, comprising:   The actual state detection unit includes a hydraulic pressure detection unit that detects the hydraulic pressure of each of the fluid chambers of the four suspension cylinders as the actual state, and the malfunction determination unit is detected by the state change cause detection unit. A hydraulic pressure-dependent operation failure determination unit that determines that the operation of the control cylinder is defective when the cause of the state change and the hydraulic pressure detected by the hydraulic pressure detection unit do not correspond to each other. Item 3. The vehicle suspension system according to Item 2.   The state change cause detection unit includes a steady turning state detection unit that detects that the vehicle body is in a steady turning state in which the posture of the vehicle body is stable during turning of the vehicle as the state change cause. 4. The stationary turning determination unit according to claim 3, further comprising: a steady turning determination unit that determines that the control cylinder is malfunctioning when a detected hydraulic pressure detected by a hydraulic pressure detection unit and a detected steady turning state detected by the steady turning state detection unit do not correspond to each other. Vehicle suspension system.   The vehicle suspension system includes a vehicle height adjustment device that adjusts a vehicle height corresponding to each of the four wheels by supplying and discharging hydraulic fluid to and from the four suspension cylinders, and the state change cause detection unit includes the vehicle The height adjustment device detects that the hydraulic fluid has been supplied / discharged to / from the suspension cylinder corresponding to a part of the four wheels, and the vehicle height adjustment detection unit includes a part of the vehicle height adjustment detection unit. A partial vehicle height adjustment-induced posture change estimation unit that estimates a change in the posture of the vehicle body corresponding to the partial vehicle height adjustment as a cause of the state change in response to detection of the partial vehicle height adjustment, and the malfunction The partial vehicle height adjustment in which the determination unit determines that the operation of the control cylinder is defective when the detected hydraulic pressure of the hydraulic pressure detection unit and the estimated partial change in height due to the partial vehicle height do not correspond to each other The time determination part is included in Claim 3 or 4 Vehicle suspension system.   The state change cause detection unit detects three or more vehicle height detection devices that detect vehicle heights in at least three locations of the vehicle body, and the vehicle body based on vehicle heights detected by the vehicle height detection devices. A vehicle height-based acquisition unit that acquires the change in posture of the vehicle as the cause of the state change, and the operation failure determination unit acquires the posture acquired by the vehicle height-based acquisition unit when the vehicle is in a stopped state. The vehicle suspension according to any one of claims 3 to 5, further comprising a stop operation failure determination unit that determines operation failure of the control cylinder when the change and the fluid pressure detected by the fluid pressure detection unit do not correspond to each other. system.   The state change cause detection unit detects two or more vehicle height detection devices that detect vehicle heights corresponding to at least two of the four wheels, and one of the at least two wheels by the vehicle height detection device. When a change greater than the set amount of the vehicle height corresponding to the vehicle height is detected, the change in posture due to the change in the single wheel vehicle height, which corresponds to the change in vehicle height, is acquired as the cause of the state change. The one-wheel vehicle height change acquired by the hydraulic pressure detected by the hydraulic pressure detection unit and the posture change acquisition unit at the time of the one-wheel vehicle height change. The vehicle suspension system according to any one of claims 3 to 6, further comprising a one-wheel vehicle height change determination unit that determines that the operation of the control cylinder is defective when the caused posture change does not correspond to each other.   The vehicle suspension system includes a hydraulic fluid supply / discharge device common to the four suspension cylinders, four individual on-off valves provided between the hydraulic fluid supply / discharge device and each of the four suspension cylinders, A vehicle height adjustment control unit that adjusts the vehicle height corresponding to each of the four wheels by controlling the four individual on-off valves and the hydraulic fluid supply / discharge device, and the hydraulic pressure detection unit includes: A shut-off means provided between the four individual on-off valves and the hydraulic fluid supply / discharge device in common to the four individual on-off valves to shut off communication between the four individual on-off valves and the hydraulic fluid supply / discharge device; A hydraulic pressure sensor provided in common between the four individual on-off valves between the shut-off means and the four individual on-off valves, and sequentially opening and closing the four individual on-off valves while keeping the shut-off means in the shut-off state. , The fluid of the four suspension cylinders to the hydraulic pressure sensor Vehicle suspension system according to any one of claims 3 to 7 and a a hydraulic sequential hydraulic pressure to the detection output control unit. The vehicle suspension system includes a vehicle height adjustment device that adjusts a vehicle height corresponding to each of the four wheels by supplying and discharging hydraulic fluid to and from the four suspension cylinders, and the control cylinder operation failure detection device includes: ,
An openable and closable plug provided corresponding to one of the four suspension cylinders;
A stop state detector for detecting that the vehicle is in a stop state;
A liquid that causes the vehicle height adjusting device to set the liquid pressures of all the four suspension cylinders to atmospheric pressure on the condition that at least the stop state detection unit detects that the vehicle is in a stopped state. A pressure release control unit;
After the hydraulic pressure is released by the hydraulic pressure elimination control unit, the hydraulic pressure of one suspension cylinder different from the suspension cylinder provided with the plug is provided to the vehicle height adjusting device. The vehicle suspension system according to claim 1, further comprising a hydraulic pressure increase control unit that increases a set amount.

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