JPH02127113A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To make it possible to adjust the floor height to the height approximate to an aimed value by stopping the output after actnating a drivesystem for a calculated time necessary for each of suspension mechanisms at the time when the difference between a detected value of the floor height and the aimed value exceeds an allowable range restraining an influence of external disturbance at the time of stopping the floor height adjustment output. CONSTITUTION:When the average floor height detection value during a time T exceeds the allowable range of an aimed value while a vehicle is running, for even one of respective suspension mechanism main bodies 10 an output time T necessary to get rid of the floor height difference in the main bodies 10 is calculated and a drive system 52 corresponding to the suspension mechanism main bodies 10 is actuated only for the time T. Namely, when the floor height is too large, a solenoid valve 56 for lowering is opened to extract a part of oil from the main bodies 10, and when the floor height is too small, a solenoid valve 55 for raising is opened to supply oil to the main bodies 10. Consequently, when the specifit output time T passes, the output to the drive system 52 is stopped to maintain the floor height. Accordingly, even if the influence of external disturbance is added during the adjustment of the floor height, it is possible to return the floor height to the floor height aimed value in the same way in the case of no external disturbance after getting rid of the external disturbance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle suspension system having a vehicle height adjustment function capable of adjusting the height of a vehicle body.

[Conventional technology]

Several vehicle suspension systems having a vehicle height adjustment function have been proposed in the past. An example of this type of suspension system is a suspension system in which the vehicle height can be controlled by pumping oil or gas into and out of a suspension mechanism body that is filled with a fluid such as oil or gas. In this device, the vehicle height is constantly monitored by a vehicle height detection means such as a vehicle height sensor, and when the detected value exceeds the allowable range of a desired vehicle height target value, the above fluid is introduced into and taken out from the suspension mechanism body. This allows the target vehicle height to be maintained.

By the way, a running vehicle constantly moves up and down due to the unevenness of the road surface. For this reason, it is desirable to determine the actual vehicle height by taking the average value of the output signal from the vehicle height sensor over a certain period of time.

From this point of view, the vehicle height adjustment logic of the suspension system previously proposed by the present inventors (see Japanese Patent Laid-Open No. 82-8807), as shown in FIG. Calculate the moving average of vehicle height detection values over a long period of time tl (for example, 20 seconds or more), compare this average value with the vehicle height target value, and adjust the vehicle height when the vehicle height difference exceeds a predetermined tolerance range. I am trying to start outputting. When stopping the vehicle height adjustment output, the moving average value over a relatively short period of time tz (for example, within 5 seconds) is compared with the vehicle height target value, so that the adjusted vehicle height comes as close to the target value as possible. We are taking this into account.

[Problems to be Solved by the Invention] In the suspension system of the above-mentioned prior art, vehicles with relatively high spring constants are not affected by disturbances such as rolls and dives, but vehicles with low spring constants Furthermore, the deviation between the actual vehicle height and the target value could become large due to the influence of external disturbances. In other words, as shown in Figure 7, when the output during vehicle height adjustment and a disturbance overlap, the vehicle height adjustment output apparently stops as it reaches the vehicle height target value above, and then the disturbance occurs. If the problem is resolved, the vehicle height will deviate from the target value.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a suspension system that can control the height close to a target value by suppressing the influence of disturbance when stopping the vehicle height adjustment output.

[Means for Solving the Problems] In order to achieve the above object, the present inventor has invented a suspension device which contains a fluid such as oil or gas inside and is capable of expanding and contracting in the axial direction according to the amount of the fluid. A vehicle suspension system that includes a plurality of suspension mechanism bodies provided for each wheel, a drive system that can feed fluid into and out of these suspension mechanism bodies, and vehicle height detection means that detects the vehicle height value of each wheel. In this step, the vehicle height value or vehicle height average value for each wheel detected by the vehicle height detection means is compared with a vehicle height target value to calculate the difference therebetween, and when this vehicle height difference exceeds an allowable range, The output time required for each suspension mechanism body to eliminate the above vehicle height difference is calculated based on the reference operating speed specific to each suspension mechanism body determined in advance, and the output time for each suspension mechanism body is calculated for this output time. The present invention is characterized in that it includes a logic circuit that operates the drive system corresponding to the drive system and then stops the output to the drive system.

[Operation] When the vehicle is in a running state, the logic circuit compares the actual vehicle height value of each wheel detected by the vehicle height detection means with the vehicle height target value and calculates the difference. If this vehicle height difference exceeds the allowable range, the output time required for each suspension mechanism body is calculated based on the predetermined operating speed unique to each suspension mechanism body. After the drive system corresponding to the suspension mechanism main body is operated for this output time, the output to the drive system is stopped.

After the above logic circuit starts outputting vehicle height adjustment,
The suspension mechanism main body is driven for an output time calculated according to the vehicle height difference so as to approach the vehicle height target value without relying on a detection signal from a vehicle height sensor or the like that is affected by external disturbances.

[Example] An example of the present invention will be described below with reference to FIGS. 1 to 5.

As shown in FIG. 2, a total of four suspension mechanism bodies 10 are provided for each of the front, rear, left and right wheels. As shown in FIG. 3, each suspension mechanism main body 10 includes a main cylinder mechanism 11 and a subchamber 12. The main cylinder mechanism 11 includes a cylinder 1 having an oil chamber 15 inside.
6, and a hollow rod 17 inserted movably in the axial direction of the cylinder 16. A shaft seal portion 18 is provided on the upper end side of the cylinder 16 in the drawing. cylinder 1
An attachment part 20 provided at the lower part of the wheel 6 is connected to a member on the wheel side.

Damping force generation mechanism 2 provided at the lower end side of the rod 17 in the drawing
2 includes a piston-like portion 23 and a variable orifice 24. The variable orifice 24 is configured such that the cross-sectional area of the flow path, that is, the damping force, can be changed by changing the rotational position of a valve 26 rotated by a motor 25 with a speed reducer.

Inside the rod 17, there is an oil circulation section 27 along the axial direction.
The flow section 27 can communicate with the oil chamber 15 via the variable orifice 24. A mounting portion 28 provided at the upper end of the rod 17 is connected to a member on the vehicle body side (not shown).

The subchamber 12 consists of a housing 31, an inner cylinder 32 provided inside the housing 31, a bellows-shaped partition member 33, etc., and the inside of the partition member 33 is connected to the oil chamber 3.
Used as 5. This oil chamber 35 communicates with the circulation portion 27 of the rod 17 via an oil passage 36. The space between the partition member 33 and the housing 31 is used as an air chamber 37, and this air chamber 37 is filled with an inert gas such as nitrogen.

The bellows-like partition portion 33 expands and contracts in the axial direction in response to changes in the volume of the air chamber 37. 38 is a bellows cap. This sub-chamber 12 may be integrally assembled immediately beside the main cylinder mechanism 11, or may be located at a different position from the main cylinder mechanism 11.

The pressure of the gas sealed in the air chamber 37 is controlled by the oil chamber 35 and the oil passage 36.
Since the rod 17 acts on the oil chamber 15 through the cylinder 16, the rod 17 is urged in the direction of protruding from the cylinder 16. The gas in the air chamber 37 is sealed at a pressure high enough to support the load of the vehicle body. When the rod 17 moves relative to the cylinder 16 in the axial direction, oil according to the pushing amount of the rod 17 flows between the oil chambers 15 and 35 via the oil passage 36, and the volume of the air chamber 37 changes accordingly. At the same time, the partition member 33 expands and contracts in the axial direction.

As shown in FIG. 2, each suspension mechanism main body 10 has hydraulic piping 41. ．． A hydraulic pump 51 is connected to valve assemblies 46, 47, 48, 49 for vehicle height adjustment via 42, 43, 44. These valve assemblies 46 to 49, hydraulic pump 51, etc. constitute a fluid drive system 52. 53
is a drain pipe, and this drain pipe 53 collects oil leaking from the shaft seal portion 18 of the suspension mechanism main body 10 into a tank 54. The valve assemblies 46 to 49 have the same construction and each includes a solenoid valve 55 for raising the vehicle height and a solenoid valve 56 for lowering the vehicle height.

Further, a vehicle height sensor 61 (see FIG. 4) is provided as means for detecting the vehicle height value for each wheel. The vehicle height sensor 61 is connected to a control device 62 using a microcomputer or the like. The control device 62 is configured to send opening/closing control signals to the electromagnetic valves 55, 56 of the valve assemblies 46-49 described above. Furthermore, a logic circuit 63 and a correction logic circuit 64 as shown in FIG. 1 are programmed into this control device 62. 65 in FIG. 4 is a vehicle height setting device.

Next, the operation of the suspension system having the above configuration will be explained.

The vehicle height value detected by the vehicle height sensor 61 is taken into the control device 62 at predetermined intervals (for example, every 0.2 seconds).

Different data processing is performed when the vehicle is parked and when the vehicle is running.

When the vehicle is parked, the vehicle height detection average value over a relatively short period of time (for example, one second) is compared with the vehicle height target value. The vehicle height target value can be input in advance using the setter 65. When the average value detected at each time exceeds the allowable range of the vehicle height target value, the control device 62 immediately sends a vehicle height adjustment output signal to the drive system 52, and if the vehicle height is too high, the lowering electromagnetic The valve 56 is opened and the suspension mechanism main body 10
A portion of the oil is drained from the oil chambers 15, 35, and when the vehicle height is too low, the lifting solenoid valve 55 is opened to supply oil to the suspension mechanism main body 10. In this way, the vehicle height adjustment output is continued in each suspension mechanism main body 10 until the detected average value matches the vehicle height target value. While the vehicle is parked, there is no influence of disturbances due to unevenness of the road surface, so there is no problem in determining when to stop the vehicle height adjustment output based on the detection signal from the vehicle height sensor 61.

While the vehicle is running, the vehicle height is controlled via a logic circuit 63 shown in FIG. 1 because of the influence of disturbances (roll, dive, etc.). In other words, while driving, the average vehicle height detection value over a relatively long period of time t (for example, 50 seconds or more) is compared with the target value, and when the difference exceeds the allowable range, the vehicle height difference is required to be resolved. The output time T is calculated.

If the vehicle height difference is within the allowable range, the average over time is calculated again and the comparison with the target value is repeated. Note that if the vehicle height sensor 61 is an analog output type, it is also possible to directly determine the vehicle height sensor value after passing it through a low-pass filter. However, in the following explanation, a case will be described in which the determination is made based on the average value.

Vehicle height: The output time T required for A adjustment is
depends on the specific actuation speed. In other words, the suspension mechanism body 1
0 indicates that when either one of the electromagnetic valves 55 or 56 is opened, oil is supplied to or discharged from the suspension mechanism main body 10, thereby raising or lowering the oil, and the ability to supply and discharge oil by the drive system 52 is Since it is limited, the operating speed will vary depending on the load conditions applied to the suspension mechanism main body 10, etc. Further, the operating speed also differs depending on whether the number of suspension mechanism bodies 10 to be adjusted is one or more, and there is also a difference depending on whether the vehicle height is being raised or lowered. For this reason, based on the reference operating speed that has been measured in advance under predetermined load conditions for each suspension mechanism main body 10,
The output time T necessary for adjusting the vehicle height for each suspension mechanism main body 10 is calculated.

Specifically, there is a difference in the operating speed of each suspension mechanism body 10 between the front wheels and the rear wheels due to the difference in load sharing, and moreover, the operating speed when raising the left and right suspension mechanism bodies 10°10 of the pair of left and right wheels at the same time is different. is half the operating speed when only one side, left or right, is raised.

When it is necessary to raise the vehicle height of both the front wheels and the rear wheels, sequence control is performed to first raise the vehicle height of the rear wheels, and then to raise the vehicle height of the front wheels. The left and right wheels are raised at the same time. Therefore, if the reference actuation speed when raising only one side of the front wheels is vl, the actuation speed when raising both the left and right front wheels simultaneously is vl/2. Furthermore, if the operating speed when raising only one side of the rear wheel is v2, then the speed when raising both left and right rear wheels simultaneously is v2/2.

This value also applies when it is necessary to raise the vehicle height of both the front and rear wheels. Further, when lowering the vehicle height, the lowering speed of the front wheels is V3 both on the left and right sides at the same time and on one side, and the lowering speed of the rear wheels is V4 on both the left and right sides simultaneously and on one side. In this way, the data of the operating speed V, ~v4 for each wheel is set in advance by actual measurement. The load conditions when determining these reference operating speeds are as follows: When ascending, the vehicle is empty (with no load), and when descending, the vehicle is loaded, which is descending rapidly. To prevent excessive adjustment amount during adjustment.

The reference operating speed for each suspension mechanism main body 10 is determined as described above, and while the vehicle is running, each suspension mechanism main body 10
When even one of the vehicle height detection average values during time t exceeds the allowable range of the target value, the output time T required to eliminate the vehicle height difference in the suspension mechanism main body 10 is calculated, and the output time T is calculated. The drive system 5 corresponding to the suspension mechanism main body 10 by T
2 is operated. That is, when the vehicle height is too high, the lowering solenoid valve 5°6 is opened to drain some of the oil from the suspension mechanism main body 10, and when the vehicle height is too low, the ascending solenoid valve 55 is opened. As a result, oil is supplied to the suspension mechanism main body 10. In this way, after the predetermined output time T has elapsed, the output to the drive system 52 is stopped, and the vehicle height is maintained. After the vehicle height adjustment output is completed, the average value of the time t is again taken and compared with the vehicle height target value, and the process is repeated.

In this way, the logic circuit 63 in the control device 62
is calculated based on the reference operating speeds v1 to V4 specific to each suspension mechanism main body 10, without relying on the detection signal from the vehicle height sensor 61, which is susceptible to disturbances after the vehicle height adjustment output has started. By operating the drive system 52 for the specified output time T, the vehicle height is brought closer to the target value.
As shown in FIG. 5, even if the influence of a disturbance is applied during vehicle height adjustment, after the disturbance is resolved, the vehicle height can be returned to the vehicle height target value as in the case without the disturbance.

In the logic circuit 63 of this embodiment, a correction logic circuit 6 for correcting the reference operating speed V] to V4 is provided.
4 may be incorporated. This correction logic circuit 64 determines the vehicle height value after the last vehicle height adjustment performed from parking to driving state after determining the above-mentioned initial reference speeds V1 to V4, or the vehicle height per predetermined time. A new reference operating speed is calculated based on the average value and the output time required for the vehicle height adjustment, and this reference speed is used as the reference speed for the next vehicle height adjustment.

Alternatively, the first vehicle height adjustment may be performed at the initial reference speed V as described above.
Adjust the vehicle height based on 1 to V4, and from the second time onwards, the vehicle height value after the previous vehicle height adjustment or the average vehicle height value per predetermined time and the output time required for the vehicle height adjustment are also calculated. A new 2! The semi-operating speed is calculated, and the average value of this new reference speed and the reference speed used for the previous vehicle height adjustment is set as the reference speed V, ~V for the next vehicle height adjustment.
Use as 4. In this way, even if the new reference speed deviates from the actual operating speed for some reason, the influence of the error can be reduced because the data from the previous adjustment is taken into account. By employing such correction logic, the operating speed, which changes depending on various load conditions, temperature conditions, etc., can be successively updated to the optimum speed.

In the embodiment described above, the sub-chamber 12 is provided with an air chamber 37, but in carrying out the present invention, the main cylinder mechanism 11 may have an air chamber and an oil chamber built-in, or two
Two or more sub-chambers 12 may be connected in a switchable manner.

[Effects of the Invention] According to the present invention, the vehicle height can be brought close to a desired target value without being influenced by disturbances such as roll or dive that occur during the output of vehicle height adjustment.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the present invention, FIG. 1 is a flowchart showing the logic of vehicle height adjustment, FIG. 2 is a hydraulic system diagram showing an outline of the structure of the suspension system, and FIG. 4 is a schematic diagram showing the relationship between the control device and the drive system, etc., FIG. 5 is a diagram showing the relationship between the target value and the detected vehicle height value, and FIG. 6 is the conventional FIG. 7 is a diagram showing the relationship between the target value and the detected vehicle height value in a suspension system, and FIG. 7 is a diagram showing the relationship between the target value and the detected vehicle height value when a disturbance is applied in a conventional suspension system. 10... Suspension mechanism body, 15... Oil chamber, 16...
cylinder, 17... rod, 33... partition member,
35... Oil chamber, 37... Air chamber, 46, 47, 48.
49... Valve assembly, 52... Drive system, 55...
・Solenoid valve for raising vehicle height, 56... Solenoid valve for lowering vehicle height, 6
DESCRIPTION OF SYMBOLS 1... Vehicle height detection means, 2... Control device, 3... Logic circuit, 64... Logic circuit for correction|amendment.

Claims (2)

[Claims] (1) A plurality of suspension mechanism bodies that contain fluid inside and can expand and contract in the axial direction according to the amount of fluid, and are provided for each wheel, and a drive system that can put fluid in and out of each of these suspension mechanism bodies. , a vehicle suspension system comprising a vehicle height detection means for detecting a vehicle height value for each wheel, the vehicle height value for each wheel detected by the vehicle height detection means or the vehicle height average value per predetermined time is detected by the vehicle height detection means for each wheel. The vehicle height is compared with the target vehicle height value and the difference is calculated, and when this vehicle height difference exceeds the allowable range, the vehicle height is adjusted based on the standard operating speed unique to each suspension mechanism determined in advance. A logic circuit that calculates the output time required for each suspension mechanism body to eliminate the difference, operates the drive system corresponding to the suspension mechanism body for this output time, and then stops the output to the drive system. A vehicle suspension system comprising: (2) Calculate a new standard operating speed based on the vehicle height value after vehicle height adjustment or the vehicle height average value per predetermined time based on the output time required for the vehicle height adjustment, and combine this new operating speed with the previous 2. The vehicle suspension system according to claim 1, further comprising a correction logic circuit that uses an average value of the reference operating speed used for vehicle height adjustment as the reference operating speed for the next vehicle height adjustment.