JPH02182525A - Suspension device for car - Google Patents

Abstract

PURPOSE:To provide a high-speed control process by making the first control means provided on each wheel control the supply and discharge of fluid for the hydraulic cylinder of each wheel on displacement on the lower side of a spring, and the second control means output a correction signal based on the displacement on the upper side of the spring to the first control means. CONSTITUTION:The supply and discharge of fluid for hydraulic chambers 4, 5 of a hydraulic cylinder 3 installed between the upper and lower sides of a car spring is controlled to change the suspension characteristics of a car body. In this case, the car body is provided with detecting means 29, 23 for displacement on the upper and lower sides of the spring. In each of wheels 2F, 2R, the first control means 22 controls the supply and discharge of the fluid for the hydraulic chambers 4, 5 of each hydraulic cylinder 3 to reduce a load inputted into the lower side of the spring according to a signal issued from each detecting means 23 for displacement on the lower side of the spring. In addition to that, the second control means 25 outputs a correction signal to the first control means 22 22 to keep the attitude of a car body 1 constant on a signal issued from the detecting means 29 for displacement on the upper side of the spring.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention supplies and discharges fluid to and from fluid chambers of fluid cylinders installed between a vehicle body (spring mass) and each wheel (spring mass). The present invention relates to a suspension device that controls suspension characteristics, and particularly to measures for improving responsiveness of the control.

(Prior Art) Conventionally, as an example of a suspension system for this type of vehicle, as disclosed in Japanese Patent Publication No. 59-14365, a hydraulic cylinder is disposed between the vehicle body and each wheel, and A so-called hydropneumatic suspension device is known in which a gas spring is connected to the hydraulic cylinder so that the vertical load of the suspension is absorbed by the compressibility of the gas in the gas spring.

On the other hand, there is no gas spring connected to the cylinder, and a pressure source such as a pump is communicated with the fluid chamber of the cylinder via a fluid passage, and the supply and discharge of fluid to and from the cylinder fluid chamber is controlled in the middle of the fluid passage. A control valve is installed, and by controlling this control valve, fluid is supplied and discharged from the fluid chamber of each cylinder to change the suspension characteristics, thereby improving ride comfort and stabilizing the vehicle body posture. Active suspension devices are known.

(Problem to be Solved by the Invention) By the way, in the above-mentioned active suspension device, when the operation of the control valve corresponding to each wheel is controlled by the CPU, one control means having a built-in CPU is usually used, and the control means The control valves are controlled by outputting a control signal from the control valve to each control valve.

However, in this control method, signals for both the displacement on the vehicle spring and the displacement under the spring corresponding to each wheel are input to the control means, and the optimal control amount for each wheel is calculated based on both signals. A control procedure is adopted in which the control signal is determined by , and then the control signal is output to each control valve. For this reason, the control procedure in the control means becomes complicated, and the storage capacity also increases, resulting in the need for an expensive CPU, leading to an increase in costs.

Furthermore, since all arithmetic processing is performed by the CPU of one control means, it takes time for the control means to output control signals to each control valve, and there is a limit to high-speed control of the control valves.

Furthermore, in the event that an abnormality such as a failure occurs in the CPU of the control means, it will be impossible to supply and discharge fluid to and from the fluid chamber of the cylinder, so it is possible to avoid a complete stoppage of the suspension device's functions. do not have.

The present invention has been made in view of the above points, and its purpose is to make the control means function as a control means for stabilizing the posture of the vehicle body and a control means for the purpose of improving riding comfort. By dividing and providing multiple control means, the control procedure for each control means can be simplified and a low-cost CPU can be used. Also, by dividing the functions of each control means, high-speed control is possible, and when a failure occurs in the control means, But the aim is to ensure a minimum level of control over the active suspension system.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention, as shown in FIG. In a suspension device comprising an extendable fluid cylinder 3 and configured to change and adjust suspension characteristics by supplying and discharging fluid to and from a fluid chamber 4.5 of the fluid cylinder 3, there is provided a spring mass for detecting displacement on the spring. Displacement detection means 29 and unsprung displacement detection means 23 for detecting the displacement of the unsprung portion corresponding to each wheel 2F, 2R are provided.

Corresponding to each wheel 2F, 2R, a signal from the unsprung displacement detecting means 23 is sent to the fluid chambers 4, 5 of the fluid cylinder 3 of each wheel 2F, 2R so as to reduce the input load to the unsprung part. A plurality of first control means 22.22. ... will be established.

Furthermore, the first control means 2 is configured to maintain the posture of the vehicle body 1 constant based on a signal from the sprung mass displacement detection means 29.
2. 22. . . . is characterized in that one second control means 25 is provided for outputting a correction signal to each of them.

(Function) With the above configuration, in the present invention, each wheel 2 in the vehicle
The unsprung displacements of wheels F and 2R are detected by the unsprung displacement detecting means 23 corresponding to the wheels 2F and 2R, and the corresponding first control means 22 is actuated by the signal from each unsprung displacement detecting means 23. , the fluid chambers 4.5 of each fluid cylinder 3 so as to reduce the input load to the unsprung portion of each wheel 2F, 2R.
The supply and discharge of fluid to and from the pump are controlled.

On the other hand, the sprung mass displacement of the vehicle is detected by the sprung mass displacement detection means 29, and the second control means 25 is actuated by the output signal of this detection means 29, and the second control means 25 is operated to maintain the posture of the vehicle body 1 constant. 2 control means 25 to the first control means 2
2. 22. A correction signal is output to each of...

In this way, the first control means 22. 22. In each of the above, control is performed to reduce the input load to the unsprung portion of the wheels 2F, 2R based on the output of the corresponding unsprung displacement detecting means 23, and in the second control means 25, the input load to the unsprung portion of the wheels 2F, 2R is The first control means 2 sends a correction signal to keep the posture constant.
2, the control procedures for each of the control means 22 and 25 are simplified by dividing their roles, the storage capacity is also small, and a low-cost CPU can be used, thereby suppressing the increase in cost. be able to.

Further, by dividing the functions of each control means 22, 25, the time required to output a control signal is shortened, and therefore control can be executed at high speed.

Furthermore, basically, each wheel 2 is controlled by the first control means 22.
Since the supply and discharge of fluid to the fluid chambers 4.5 of the fluid cylinders 3 of F and 2R is controlled, even if an abnormality occurs in the second control means 25, the second control means 25 will The correction signal related to the stabilization of the vehicle body posture output to the control means 22 is only stopped. For this reason, the first control means 22
As long as no abnormality occurs, control for reducing the input load to the unsprung portion of the first control means 22 is ensured, and therefore active control of ride comfort can be ensured by this control.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.

FIG. 2 schematically shows the overall structure of a suspension device according to an embodiment of the present invention. In the figure, 1 is a vehicle body constituting a sprung portion of the vehicle, 2F is a front wheel, and 2R is a rear wheel. Each of these wheels 2F and 2R is supported by a wheel support member (not shown) such as an axle. The wheels 2F, 2R and the wheel support member constitute an unsprung portion.

The vehicle body 1, that is, the sprung portion, and each wheel 2F.

An extendable hydraulic cylinder 3 is installed between the unsprung portion including 2R. As shown in FIG. 3, each cylinder 3 includes a cylinder body 3a connected and fixed to the wheel support member (wheels 2F, 2R), and a cylinder body 3a that is reciprocatably fitted into the cylinder body 3a. The piston 3b partitions the inside of the piston 3a into upper and lower hydraulic chambers 4.5. A piston rod 3C extending upward is integrally connected to the piston 3b, and the upper end of the piston rod 3C is connected and fixed to the vehicle body 1 via a load sensor 21 for detecting the load applied to the suspension.

Further, the upper and lower hydraulic chambers 4.5 of each cylinder 3 are communicated via oil passages 6, 7, respectively, with an oil pump 8 and a reserve tank 9, which are driven by an on-vehicle engine (not shown). In the middle of the oil passage 6.7, supply and discharge of oil to and from the hydraulic chamber 4.5 of the cylinder 3 is controlled. The same number (4) of control valves 10 as wheels 2F and 2R
, 10°... are arranged. Each control valve 1
0 consists of a proportional solenoid valve having three switching positions, and by controlling the switching positions (PIDjtlJ control), supply and discharge of oil to and from the hydraulic chambers 4 and 5 of each cylinder 3 is controlled.

The operation of each of the control valves 10 is controlled by a CPU-incorporated sub-controller 22 provided corresponding to each wheel 2F, 2R. Each of the sub-controllers 22 receives the detection signal of the load sensor 21 and the wheel 2F.
, 2R corresponding to the sprung and unsprung stroke X (
A detection signal from a stroke sensor 23 that detects the expansion/contraction stroke of the cylinder 3 and a signal of vehicle speed V output from a vehicle speed sensor 24 are input. The stroke sensor 23 has a sensor main body 23a fixed to the vehicle body 1, and a movable part 23b slidably inserted into the main body 23a. The movable portion 23b is connected to the body 3a of the corresponding cylinder 3 via a rod 23c, and the expansion/contraction stroke of the cylinder 3 is detected by the displacement of the movable portion 23b that changes with the expansion/contraction movement of the cylinder 3. and,
In this embodiment, the stroke sensor 23 constitutes unsprung displacement detection means for detecting the displacement of the unsprung portion of each wheel 2p, 2R.

Furthermore, 25 is one main controller with a built-in CPU connected to each of the sub-controllers 22 so as to be able to send and receive signals. This main controller 25 receives a vehicle speed signal output from the vehicle speed sensor 24, a detection signal from a longitudinal g sensor 26 that detects the longitudinal acceleration gFR acting on the vehicle body 1 (spring upper part), and a detection signal in the horizontal direction as well. Detection signals from the left and right g sensors 27 that detect acceleration gRL, and vertical acceleration g acting on the unsprung portions of each wheel 2F, 2R.
Four unsprung g-sensors 28°28,...
・Detection signal is input. In this embodiment, the longitudinal g-sensor 26, the left-right g-sensor 27, and each unsprung g-sensor 28 constitute a sprung mass displacement detection means 29 for detecting the displacement of the vehicle body 1, which is a sprung mass.

Here, to explain the control regarding the supply and discharge of oil to and from the hydraulic chambers 4.5 of each cylinder 3, the control is basically load control based on the following equation 0.

Fr−F□ +K ・(H−x) +a −■a−
Ka φgFR+Kb 11gRL+Ka”gUD
...■F': Target load Fo: Static load; Coefficients Ka, kb, Kc corresponding to spring constants: Coefficient H: Reference vehicle height α: Correction amount In other words, this load control is based on static load FO and reference vehicle High H
is set, the actual stroke X is calculated based on the detected value of each stroke sensor 23, and the value K・(H-x), which is the difference between the reference vehicle height H and the actual stroke X multiplied by the coefficient K, and the static load are calculated. The total amount of FO and the correction amount α is set as the target load Fr, and the actual load detected by the load sensor 21 is the target load F.
The control valve 10 is switched and controlled so that oil is supplied to and discharged from the upper and lower hydraulic chambers 4.5 of the cylinder 3.

Then, the main controller 25 performs calculation to obtain the correction amount α shown in the above equation (2), and calculates the correction amount α.
A correction signal corresponding to the sub-controller 22 is output to each sub-controller 22. On the other hand, each subcontroller 22
Now, the correction signal from the main controller 25 is input, and control is performed based on the correction amount α based on the above equation 0.

Specifically, the procedure of signal processing performed in the CPU of the main controller 25 and each sub-controller 22 will be explained.
Processing is performed according to the flowchart shown in the figure. first,
After initialization in step S1 after the start, signals from each sensor 24, 26 to 28 are detected in step S2, and the process further proceeds to step S3 to calculate the correction amount α.

Since this correction amount α differs for each wheel 2F and 2R, its calculation is performed for each wheel 2F and 2R, for example. Then, in step S4, the wheel 2F.

A signal (correction signal) of the correction amount α every two days is output to each corresponding sub-controller 22. Furthermore, in step Ss, an operating state signal (for example, a constant pulse signal, etc.) indicating the normal operation of the main controller 25 is transmitted to each sub-controller 2.
After that, the process returns to step S2 and executes subsequent steps S3, S4+, and so on.

On the other hand, in each sub-controller 22, as shown in FIG. 5, after initialization in step S++,
In step S12, the control switching flag C is set to C-0, and the main controller abnormality flag I is set to I-0. The main controller abnormality flag I is used to identify abnormal operation of the main controller 25, such as runaway or failure, and is determined to be abnormal when it is I-1. In addition, the control switching flag C is used to execute normal load control using the above formula 0, and to set reference values such as static load F and reference vehicle height H when the vehicle is stopped (including extremely sluggish running states). This is used to identify whether stroke control is to be executed for the purpose of control, and when C-1, load control is executed. In addition, in the above stroke control, each control valve 1 is adjusted so that the actual stroke X becomes the reference vehicle height H.
0.

Then, in step S+3, signals from each sensor 21, 23, 24 are detected, and the process further proceeds to step S+4, where the correction amount a from the main controller 25 is input. Next, in step SI5, the operating state signal from the main controller 25 is input, and in step S+6, the main controller abnormality flag l is set! -1 or not. When the operating state signal is output from the main controller 25, this determination is NO, so step SI8
Proceed to. On the other hand, when the operating status signal is not output.

That is, since the flag I becomes 1-1 when the main controller 25 malfunctions, the correction amount α is set to α-0 in step S+7, and then the process proceeds to step 5lll. In this step S18, it is determined whether the control switching flag C is C-1, and when this determination is No (C-0), it is determined in step S+9 whether or not the vehicle speed V is higher than the first set value a. judge. When this determination is V≦a, that is, when the vehicle is stopped or running at an extremely low speed, the process proceeds to step 5ell, where the control switching flag C is set to C-0, and the stroke control state is entered at step S21.
After measuring reference values such as the static load FO and the reference vehicle height H in step S22, the process returns to step S13 and the subsequent steps S14. Repeat SIS,... Therefore, the static load F, reference vehicle height H, etc. are determined while the vehicle is stopped.

On the other hand, when the determination in steps S and g is YES for Via, it is determined that the vehicle is running in a normal state, and the process proceeds to step S24, where the control switching flag C is set to C-.
1 and the main controller abnormality flag I are set to 1-0, and the process proceeds to step S25 to enter a load control state based on the above equation 0, and then returns to step SI3.

Further, when it is determined that C■1 is YES in step St, the vehicle speed V is set to the second set value b in step S23.
(this set value is lower than the first set value a), and when this determination is YES that v<b, the process proceeds to step St, and when V≧b is NO, the process proceeds to step St. Each proceeds to S24. This step S1
8. S23. The flow of S2@ is to switch from load control to stroke control when the vehicle speed V falls below a second set value a, which is lower than the first set value a, when the vehicle stops from a running state. Control hunting is prevented by providing hysteresis in vehicle speed.

With the above configuration, in this embodiment, each wheel 2r-.

Each sub-controller 22 provided corresponding to 2R controls the stroke sensor 23 (unsprung displacement detection means).
A first control means is configured to control the supply and discharge of oil to the hydraulic chambers 4, 5 of the hydraulic cylinders 3 of each wheel 2F, 2R so as to reduce the input load to the unsprung portion by a signal from the first control means r#q. ing.

The main controller 25 also controls the sub-controller 22 to maintain the posture of the vehicle body 1 constant based on signals from the sprung mass displacement detection means 29 (front/rear g-sensor 26, left-right g-sensor 27, and each unsprung g-sensor 28). (1st
A second control means is configured to output a correction signal to each of the control means).

Next, the operation of the above embodiment will be explained.

When the vehicle is running, output signals from the front and rear g sensors 26, left and right g sensors 27, unsprung g sensors 28, and vehicle speed sensor 24 are input to the main controller 25. Then, the main controller 25 calculates a correction amount α from the longitudinal acceleration gFR, the lateral acceleration gRLs, the spring lowering acceleration gu mouth, and the vehicle speed V based on the above formula 0 for each wheel 2p, 2R.
The correction amount α is determined for each wheel 2F as a signal.

It is output to the sub-controller 22 corresponding to 2R. At the same time, an operating state signal indicating normal operation of the main controller 25 is also output from the main controller 25 to each sub-controller 22 .

On the other hand, each sub-controller 22 uses the correction amount α inputted as a signal from the main controller 25 and the static load F measured in the low position of the vehicle.

Based on the reference vehicle height H and the actual stroke X detected by the stroke sensor 23, the target load Fr is determined by the above equation 0. Further, the target load Fr is compared with the load detected by the load sensor 21 corresponding to each wheel 2F, 2R, and each control valve 10 is operated and controlled so that the detected load type becomes the target load Fr. Oil is supplied to and discharged from the pressure chamber 45 of No. 3.

In that case, the main controller 25 calculates the correction amount α, which is a part of the control formula (■), and the sub-controllers 22 corresponding to each wheel 2r:, 2R perform load control based on the control formula (■). Compared to the case where everything is done by one controller, the control procedure of the CPU of the main controller 25 and each sub-controller 22 is simplified, and the storage capacity thereof is also small, so that an inexpensive CPU can be used, thereby reducing costs. be able to. Moreover,
Since separate control is executed by both controllers 22.25, the control speed of each controller 22.25 becomes faster, and control can be performed at a correspondingly higher speed to improve control responsiveness.

When an abnormality such as runaway or failure occurs in the main controller 25, the operating state signal outputted from the main controller 25 to each sub-controller 2 is lost. Accordingly, in each sub-controller 22, the above-mentioned correction amount α is set to α-0, and the equation is substantially obtained by removing the correction term on the right side from the above-mentioned equation 0, Fr −F□ +K・(H−x) ・・・■
Load control is performed based on.

In that case, the correction amount α is mainly an element for suppressing changes in the attitude of the vehicle body 1 (spring portion), such as pitching during acceleration/deceleration, roll during cornering, and suppression of vehicle body vibration when road surface displacement is large. Therefore, with the control of the above formula 0, the active control regarding the ride comfort of the vehicle can be executed as is, and therefore, even when the main controller 25 is abnormal, it is possible to ensure a good ride comfort of the vehicle. .

(Effects of the Invention) As described above, according to the present invention, in the active suspension device that changes the suspension characteristics by supplying and discharging fluid to the fluid chamber of the fluid cylinder between the sprung portion and the unsprung portion of the vehicle, The displacement of the sprung mass and the displacement of the sprung mass of each wheel are respectively detected, and the first control means corresponding to each wheel controls the fluid flow of each wheel so as to reduce the input load to each sprung mass based on the displacement of the sprung mass. While controlling supply and discharge of fluid to the fluid chamber of the cylinder, one second control means sends a correction signal to each of the first control means so as to maintain a constant attitude of the vehicle body based on the sprung mass displacement. By outputting the output, it is possible to use an inexpensive CPU and execute control at high speed by dividing the functions of each control means, reducing costs and improving control responsiveness. Even when the control means is abnormal, the active control function regarding the ride comfort of the first control means can be ensured, and the ride comfort of the vehicle can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of the present invention. Figure 2 and the following drawings show embodiments of the present invention, Figure 2 is an explanatory diagram showing its overall configuration, Figure 3 is a system diagram showing the configuration of the control system, and Figure 4 is signal processing in the main controller. FIG. 5 is a flowchart showing the signal processing procedure in each sub-controller. 1... Vehicle body, 2F, 2R... Wheels, 3... Hydraulic cylinder (fluid cylinder), 4.5... Hydraulic chamber (fluid chamber), 10... Control valve, 21... Load sensor, 2
2... sub-controller (first control means), 23.
・・Stroke sensor (spring mass displacement detection means), 25・
...Main controller (second control means), 29...
・Spring mass displacement detection means. Representative Patent Attorney 1) Hiroshi (1 Mu Mizukesu) 1...Vehicle body, 2F, 2R...Wheels, 3...Hydraulic cylinder (fluid cylinder), 4.5...Hydraulic chamber (fluid) chamber), 10... control valve, 21... load sensor, 2
2... sub-controller (first control means), 23.
・・Stroke sensor (spring mass displacement detection means), 25・
...Main controller (second control means), 29...
・Spring mass displacement detection means. 4th [! 1 Figure 5

Claims (1)

[Claims] (1) A suspension device comprising an extendable fluid cylinder installed between the sprung and unsprung parts of a vehicle, and supplying and discharging fluid to and from the fluid chamber of the fluid cylinder to change and adjust suspension characteristics. , a sprung mass displacement detection means for detecting the displacement of the sprung mass, a sprung mass displacement detection means for detecting the displacement of the sprung mass corresponding to each wheel, and a sprung mass displacement detection means provided corresponding to each wheel; a plurality of first control means for controlling the supply and discharge of fluid to the fluid chamber of the fluid cylinder of each wheel so as to reduce the input load to the sprung mass according to signals from the sprung mass displacement detection means; 1. A suspension device for a vehicle, comprising one second control means for outputting a correction signal to each of the first control means so as to maintain a constant posture of the vehicle body according to the signal.