JPH02179526A - Active movement type suspension - Google Patents

Abstract

PURPOSE:To improve the turning performance and turning stability by varying the longitudinal distribution ratio of the anti-roll moment by varying the gain for suppressing roll on the basis of the deviation between the detection value and the aimed value of slip angle and carrying out the feedback control for the car body slip angle. CONSTITUTION:The working pressure which is supplied from a fluid pressure feeding device B and supplied into a fluid pressure cylinder A interposed between a wheel and a car body is controlled by a pressure control valve C, and a working pressure sealing means D is interposed between the pressure control valve C and the fluid pressure feeding device B. The working pressure sealing device D is constituted so as to communication-operate when the feed pressure to the pressure control valve C becomes over a set value, and the timing for selecting the sealing means D from the cut-off state to the communication state is detected by a timing detecting means E. When the communication timing is detected, the variable coefficient is gradually increased with the lapse of time by a variable coefficient setting means F, and the pressure instruction value to the pressure control valve C is calculated by multiplying the variable coefficient by the output of an acceleration speed detector or estimator H by an instruction value calculating means G.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an active suspension for a vehicle, and in particular, it controls the vehicle body posture according to the acceleration acting on the vehicle, and also controls the height of the vehicle, i.e. This invention relates to an active suspension that can actively control vehicle height.

[Conventional technology]

Conventionally, this type of active suspension has been proposed, for example, in Japanese Patent Application Laid-Open No. 63-219408, which has already been proposed by the applicant of the present invention.
There are some that are listed in the publication.

This active suspension consists of a hydraulic cylinder placed on each wheel, a hydraulic supply device that supplies operating pressure to the hydraulic cylinder, and a pressure control valve that controls the operating pressure according to a command value from an attitude change control device. A check valve (fluid check means) is inserted on the supply side of the pressure control valve, and
On the return side, there is a pilot-operated check valve (fluid closing means) that closes the flow path only when the supply pressure of the hydraulic supply device falls below a predetermined pressure, and on the upstream side of this check valve, that is, a pressure control valve. A relief valve (pressure adjustment means) that maintains the pressure at a predetermined value is inserted in parallel.

Specifically, the attitude change control device uses a detector to detect the vehicle's lateral acceleration, longitudinal acceleration, vertical acceleration, etc., and based on these detected values, it issues a command value for each wheel in the direction of suppressing the attitude change. The pressure control valves are calculated separately and the calculated values are individually given to the corresponding pressure control valves. For this reason, the cylinder pressure of each hydraulic cylinder is controlled by the pressure control valve to generate a force that resists changes in attitude, thereby making it possible to suppress changes in attitude such as roll and pitch.

In addition, when the vehicle is running, the oil pressure supply device using the engine as a rotational drive source is driven, so the check function of the pilot-operated check valve is released and the return flow path is in communication, as described above. posture control becomes possible. However, when the vehicle comes to a standstill and the engine stops rotating, the discharge pressure of the hydraulic pump in the hydraulic pressure supply system immediately drops to zero, which acts as a bias to activate the check function of the pilot-operated check valve. As a result, the pressure control valve and the oil tank are cut off. Therefore, the pressure on the load side from the check valve through the hydraulic cylinder to the pilot-operated check valve is maintained at approximately the value just before the engine stopped, and this load-side pressure is The pressure is adjusted to a predetermined level by a relief valve. As a result, the vehicle body can maintain a vehicle height value corresponding to the enclosed load-side pressure even after the engine is stopped.

[Problem to be solved by the invention]

In the above conventional active suspension, when the engine is started again, the discharge pressure of the hydraulic pump increases, the pilot-operated check valve is turned on (check release), and each pressure control valve when attitude control is started. The command value V for this includes at least the sum of the neutral pressure command value V1 and the command value ■2 based on the detection value of each acceleration detector. Here, neutral pressure command value v
1, the vehicle body is supported by the spring force of the coil spring and the hydraulic cylinder pressure by constantly applying pressure to the hydraulic cylinder;
This is a command value that maintains the vehicle height at a certain level (for example, standard vehicle height), and when the engine is off, the cylinder is filled with pressure corresponding to this command value.

On the other hand, in the configuration of the conventional example, when performing vehicle height control, the command value V is obtained by further adding the vehicle height control command value v3, and the command value v3 is equal to the actual vehicle height value and the target vehicle height value. Even if there is a difference, the vehicle height control is performed by integral control from the initial value "zero", so the command value (3) at the start of the control is zero.

Therefore, when the vehicle starts, if each acceleration detector is not detecting acceleration, the pressure command value ■ = neutral pressure command value ■ 1, and this value is the same as the hydraulic cylinder sealing pressure before the start of control. Since the pressure command value is , is that posture system? There is no change in the vehicle body or vehicle height at the start of Ij (or attitude and vehicle body control).

However, given today's road conditions, it is common practice to stop on a slope or banked road surface, or to stop with one wheel resting on a step. In this case, a state may occur in which the acceleration detector is already outputting a certain value at the time of starting control, such as when the output changes when the power is turned on.

In such a case, in the conventional active suspension, the pressure command value V=V, +V! As a result, the vehicle body posture and vehicle height change due to command value ■2 at the same time as control starts.
There was an unresolved problem that the aircraft was changing and causing a sense of uneasiness to the passengers.

This invention improves these conventional unresolved problems, and even if the vehicle is not parked horizontally or there is a detection error in the acceleration detector at the time of starting control. , to prevent changes in the vehicle body posture and vehicle height even when acceleration is detected.
This is the L1 problem that we are trying to solve.

[Means to solve the problem]

In order to solve the above problem, the invention according to claim (1), as shown in FIG. A pressure control valve that controls the operating pressure from a fluid pressure supply device according to a pressure command value, and when the supply pressure to this pressure control valve falls below a set pressure, the pressure control valve and fluid pressure supply device and sealing the working pressure of the fluid pressure cylinder to the set pressure, and when the supply pressure exceeds the set value, communicating between the pressure control valve and the fluid pressure supply device. a pressure sealing means; a communication timing detection means for detecting a timing at which the operating pressure sealing means brings the pressure control valve and the fluid pressure supply device into communication from a cutoff state to a communication state; and detecting or estimating acceleration acting on the vehicle. an acceleration detector or estimator that maintains "0" before the communication timing detection means detects the communication timing;
variable coefficient setting means for setting a variable coefficient that gradually increases over time from "0" to "1" when communication timing is detected, and an output value of the acceleration detector or estimator multiplied by at least the variable coefficient. and command value calculation means for calculating a pressure command value including the pressure command value.

Further, the invention according to claim (2) provides that the acceleration detector or estimator includes at least two of a lateral acceleration detector or estimator, a longitudinal acceleration detector or estimator, and a vertical acceleration detector or estimator. consisting of a direction acceleration detector or estimator;
The command value calculation means is configured to multiply the output values of the acceleration detector or estimator in two directions by respective variable coefficients, and the variable coefficient setting means is configured to multiply each variable coefficient in the command value calculation means. The configuration is such that the increasing speed of the coefficients can be set individually.

Furthermore, the invention according to claim (3) provides a fluid pressure cylinder inserted between a vehicle body and a wheel, and a fluid pressure supply device supplied to this fluid pressure cylinder, as shown in FIG. 1(b). A pressure control valve that controls the operating pressure from the pressure control valve according to a pressure command value, and when the supply pressure to this pressure control valve falls below a set pressure, the pressure control valve and the fluid pressure supply device are cut off, and When the working pressure of the fluid pressure sill is enclosed in the set pressure, and the supply pressure exceeds the set value,
A working pressure sealing means for communicating between the pressure control valve and the fluid pressure supply device, and detecting a timing at which the working pressure sealing means brings the pressure control valve and the fluid pressure supply device into a communication state from a cutoff state to a communication state. a vehicle height detector that detects a vehicle height value; an acceleration detector or estimator that detects or estimates acceleration acting on the vehicle; and at least a variable coefficient for the output value of the acceleration detector or estimator. A command value that includes a first command value based on a value multiplied by , and a second command value based on integral control from an initial value "0" when there is a deviation between the detected value of the vehicle height detector and the target vehicle height value. a command value calculating means for outputting, the variable coefficient is maintained at "0" before the communication timing detecting means detects the communication timing, and changes from "0" to "when the communication timing is detected.
A coefficient that gradually increases over time up to 1, and
Variable coefficient setting means is provided for setting a coefficient such that a rate of change in the working pressure of the fluid pressure cylinder due to a change in the first command value is equal to or less than a rate of change in the working pressure due to a change in the second command value.

[Effect]

In the invention described in claim (1), when the vehicle stops and the drive of the fluid pressure supply device is stopped, the operating pressure sealing means shuts off between the pressure control valve and the fluid pressure supply device and closes the fluid pressure cylinder. Since the operating pressure is sealed at the set value, the predetermined vehicle height is maintained thereafter.

When the engine is driven from this stopped state to drive the fluid pressure supply device, the supply pressure increases. When the supply pressure to the pressure control valve reaches the set value or more, the operating pressure sealing means connects the pressure control valve and the fluid pressure supply device.
Since the shut-off state is returned to the communicating state, the sealing of the operating pressure is released. At this time, the transition to the communication state is detected by the communication timing detection means. Therefore, the variable coefficient setting means that had previously maintained the variable coefficient at "0"
Activated by the detection of transition to the communication state, the variable coefficient is changed to r□,
Gradually increase from 1 to 1.

Therefore, the command value calculation means calculates the pressure command value based on the value obtained by multiplying the detected acceleration value or estimated value by this gradually increasing variable coefficient, so the operating pressure of the fluid pressure cylinder according to this command value is calculated. Control is done slowly. Therefore, even if the vehicle is stopped on a slope etc. and a component due to gravitational acceleration is detected, or if the acceleration detector or estimator has an error output, the system will transition to a communication state and start attitude control. At this point, it is possible to accurately prevent situations such as sudden attitude control or sudden changes in vehicle height.

In addition, in the invention described in claim (2),
Acceleration can be detected or estimated in at least two directions, up and down, and the variable coefficients can be adjusted at individual increasing speeds. Therefore, different control sensitivities when transitioning to normal control can be set for each direction of the vehicle body.

Furthermore, in the invention described in claim (3), in addition to the invention described in claim (1), when the detected value of the vehicle height detector, that is, the actual vehicle height value is different from the target vehicle height value, the integral from the initial value "0" is Since the vehicle height control command value is also added, the vehicle height value can also be actively controlled. At this time, the variable coefficient is set from "0" to "1" so that the rate of change in the operating pressure of the fluid pressure cylinder related to the vehicle body posture is equal to or less than the rate of change in the operating pressure related to vehicle height control. This is done by absorbing all of the vehicle behavior at the start of control using vehicle height control.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

(First Embodiment) FIGS. 2 to 7 are diagrams showing a first embodiment of the present invention.

In Figure 2, l0FL, 1-OFR are the front wheels, 1
0RL and 10RR are rear wheels, 12 is a wheel side member, 14 is a vehicle body side member, and 16 is an active suspension.

Among these, the active suspension 16 is for each wheel 10FL.
Hydraulic cylinders 18FL to 18RR (fluid pressure cylinders) and coil springs 19FL to 19R are respectively inserted between the wheel side member 12 and the vehicle body side member 14 at the ~10RR position.
R, pressure control valves 2°FL to 20RR that individually control the operating pressures of the hydraulic cylinders 18FL to 18RR, and a hydraulic pressure supply device 22 (fluid pressure supply device) for this hydraulic system, and a hydraulic pressure supply bag W22. and each pressure control valve 20FL~
20RR, and an accumulator 25.25 for accumulating pressure provided between the flow path opening/closing part 23 and each of the pressure control valves 20FL to 20RR. . Furthermore, this active suspension 16
It is equipped with a detector group consisting of a lateral acceleration detector 26, a longitudinal acceleration detector 27, a vertical acceleration detector 28, vehicle height detectors 30FL to 30RR1, and an oil pressure detector 31, and a controller 32. Here, the vertical acceleration detector 28 is connected to each wheel 10.
It is desirable to provide it separately corresponding to FL-10RR.

Each of the hydraulic cylinders 18FL to 18RR has its cylinder tube 18a attached to the vehicle body side member 14 and its piston rod 18b attached to the wheel side member 12, respectively, and the cylinder tube 18a has a pressure chamber spaced apart from the piston 18c. is formed. This pressure chamber is located at the throttle valve 3.
4 to an accumulator 36 for absorbing hydraulic vibrations.

Note that each of the coil springs 19FL to 19RR has a relatively low spring constant and supports the static load of the vehicle body.

Moreover, each of the pressure control valves 20FL to 20RR has a well-known structure (for example, Japanese Patent Laid-Open No. 1983-1989-1) consisting of an electromagnetic spool valve.
295714), the supply boat and return boat of which are connected to the hydraulic supply device 22, and the output ports are connected to the pressure chambers of the hydraulic cylinders 18FL to 18RR, respectively. From the controller 32, each pressure control valve 2
A command value 1 consisting of an excitation current is supplied to each of the electromagnetic solenoids 0FL to 2OrlR. And each pressure control valve 20
As shown in FIG. 3, FL~20RR applies a pressure P proportional to the command value I to the hydraulic cylinder 18 from its output port.
Supplied to FL-18RH. That is, when the command value ■ is zero, a predetermined offset pressure P0 is output, and when the command value ■ increases in the positive or negative direction from this state, a pressure P that increases or decreases with a proportional gain of 1 is output. In addition, in FIG. 3, P□ is the line pressure of the hydraulic pressure supply device 22.

The concrete structure of the hydraulic pressure supply device 22 and the passage opening/closing section 23 is shown in FIG. 4. In the same figure, 4
Reference numeral 0 denotes a hydraulic pump, which is connected to the output shaft of an engine 41 as a rotational drive source, with its suction side connected to an oil tank 42 and its discharge side connected to a load side via a supply pipe 43.

The supply side piping 43 includes an accumulator 44 for absorbing pulsation.
is connected to the pump boat P of the 4-port electromagnetic switching valve 46 via a check valve 45 for preventing backflow. On the load side of this switching valve 46, one cylinder boat A is connected to the supply boat of each pressure control valve 20FL to 20RR through a piping 43, and another cylinder boat B is connected to each pressure control valve through a return side piping 43. Connected to return boats from 20FL to 20RR. Further, the tank port of the switching valve 46 connects to the oil tank 42 via a pipe 48 and an operated check valve (pilot operated check valve) 49.

Among these, the electromagnetic switching valve 46 has an electromagnetic solenoid 46a.
It is driven by turning on/off a switching control signal C3 of a predetermined value supplied from the controller 32. That is, when the switching control signal C3 is off, as shown in FIG. 4, the cylinder boats A and B are connected to the tank boat T via the throttle 46b, and only the pump boat P is cut off from the flow path. Furthermore, when the switching control signal C8 is on, the pump boat P and cylinder port A are placed in communication, and the tank port T and cylinder port B are placed in communication, so that each piping 43, 48 is placed in communication. .

The operating check valve 49 also includes a solenoid switching valve 46.
The supply pressure on the downstream side of the supply side is supplied as the pilot pressure PP, and in this embodiment, the check is performed when the pilot pressure PP is PP≧PH with respect to the neutral pressure PN (see Fig. 3). When the valve is released (the valve is opened), the return side piping 48 is brought into communication, and when P and <PN, a check is performed (the valve is closed) and the return side piping 48 is cut off.

In this embodiment, the operating check valve 49 and the check valve 45 constitute operating pressure sealing means.

The upstream side of the check valve 45 and the operated check valve 4
A relief valve 50 for setting line pressure is inserted between the downstream side of the valve 9 and the downstream side of the valve 9. Therefore, the hydraulic supply device 22
is relief valve 50. Accumulator 44. Hydraulic pump 40. and an oil tank 42 as main parts.

The discharge pressure of this hydraulic pressure supply device 22 is determined by the hydraulic pressure detector 31.
A hydraulic signal P corresponding to the discharge pressure is supplied to the controller 32.

On the other hand, the above-described lateral acceleration detector 26, longitudinal acceleration detector 27, and vertical acceleration detector 2 are each provided at predetermined positions on the vehicle body.
The acceleration in the longitudinal (vehicle body length) direction and the vertical direction is detected, and corresponding signals GV+cxl and G2 are output to the controller 32, respectively. In addition, vehicle height detector 30FL~3
0RR is composed of, for example, a potentiometer attached to the sprung and unsprung parts corresponding to each of the wheels 10FL to 10RR, and outputs a vehicle height signal H corresponding to the amount of relative displacement between the wheels and the vehicle body to the controller 32. do.

The controller 32 is constituted by a microcomputer as a main part, and contains a predetermined program including timer interrupt processing of the same cycle as shown in FIGS. 5 to 7.

Therefore, the controller 32 has a well-known configuration including an A/D converter, a D/A converter, a drive circuit, and the like.

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

First, the controller 32 attaches the key switch as an accessory.
When activated, a predetermined main program is executed, and the processes shown in FIGS. 5 to 7 are executed alternately at the same predetermined interrupt timing.

First, these processes will be explained.

At step (2) in FIG. 5, the arithmetic processing unit of the microcomputer reads the oil pressure detection signal P from the oil pressure detector 31, temporarily stores the value, and then proceeds to step (2). In step (2), the arithmetic processing device determines, based on the read value in step (2), that the engine 41 starts rotating, that is, the hydraulic pump 40 starts rotating, and that the discharge pressure from the hydraulic pressure supply device 22 reaches or exceeds the neutral pressure P. Determine whether or not.

If the judgment in step (2) is rNo, set the variable coefficient KAD (described later) to "0" and proceed to step (2), where the detection signal G of each acceleration detector 26 to 28 is
, -G. Next, the process moves to steps (■) to (■). Among these, in step (2), a command value 1v""Gv -Kv .KAtl is calculated for the read lateral acceleration Gy. Similarly, in step ■, I, L = GX - KX
-KAI), in step ■L = G, ・K2
・Calculate each KAD and set the command value 1. ．． Find 12.

Here, 2 for KV*KX* is the specified gain (fixed value), K
AD is a variable coefficient.

Next, the process moves to step (2), and command values 1c, .
, Ia are added and the process returns to the main program. Step ■
Then, the left and right wheels are calculated to have mutually opposite phases with respect to the command value IV, and the front and rear wheels are calculated to have mutually opposite phases with respect to the command value 1.

On the other hand, in the case of rYES in step (2), the process moves to step (2), and the time t elapsed from the point in time at which rYEsJ was determined, that is, the time when the discharge pressure of the hydraulic pressure supply device 22 reached the neutral pressure Ps, is determined. The variable coefficient KAD to be changed is set, and the process proceeds to step (2). That is, in step (2), while the elapsed time t is from zero to the predetermined time LI,
It increases with a constant slope of 1 from ap=O to Kae”l, and t
The variable coefficient KA is determined to maintain KAD=1 after 1.Next, the interrupt processing shown in FIG. 6 will be explained.

Steps ■ and ■ in Figure 6 are steps ■ in Figure 5.

This is the same as after (2), and if "NO" in step (2), the process returns to the main program, and if rYESJ, the process moves to step (2). In step (2), the vehicle height signal H for each wheel is read, the value is stored as the actual vehicle height value, and the process proceeds to step (2).

In step ■, the vehicle height deviation e on the front right side is set to the target vehicle height H0.
1.6=l(, -H is calculated for
It is determined whether et≦d, and if "NO", the process moves to step (2), and if "YES", the process moves to step (2).

In step ■, it is determined by flag processing whether or not the determination of rYEsJ in step ■ is the first time, and rYEsJ
If so, set the vehicle height adjustment variable a to "0" in step ■ and proceed to step ■; if "NO", proceed to step ■
performs vehicle height control using integral control. That is, in accordance with the vehicle height control direction, a vehicle height adjustment variable a is calculated by adding or subtracting a predetermined minute change width k to the vehicle height adjustment variable a whose initial value is zero, and the process proceeds to step (3).

In step (2), a pressure command value I□ is calculated by table lookup or the like according to the value of the variable a set at that time. Furthermore, in step [phase], the pressure command values rH for vehicle height control for the front, rear right, and rear left wheels are respectively determined by the same processing as in steps ① to ① described above, and the process returns to the main program.

Next, the timer interrupt processing shown in FIG. 7 will be explained.

In step 2 of the figure, the command values for each of the four wheels IG+ ... + IG for the acceleration determined in step 5 of Figure 5, and the vehicle height control command value IN determined in step 2 of Figure 6, 0,
..., read IIl. Next, in step (2), the read command value I is used as the command value (8) for commanding the neutral pressure PM.
G, I) I) are added for each wheel to obtain a total pressure command value I, respectively, and the process moves to step (2). In step (2), the pressure command value I is output to each pressure control valve 20FL to 20RR, and then the process returns to the main program. Next, the overall operation will be explained.

Now, the vehicle is parked on a slope that slopes in the longitudinal direction with the key switch turned off, and the electromagnetic switching valve 46 cuts off the connection between boats rP and AJ, and
-A-B, and the check function of the operating check valve 49 acts, so that the pressure control valves 20FL~
It is assumed that 20RR and hydraulic cylinders tspt to 18RR are sealed at neutral pressure PN. That is, hydraulic cylinder 1
The operating pressure in each of the pressure chambers 8FL to 18RH is a neutral pressure PM, and this pressure P8 causes the vehicle body to take a stopped position parallel to the slope and having a predetermined vehicle height.

In this stopped state, when the key switch is set to the accessory position, power is supplied from the battery to the electrical system of the active suspension 16, and the controller 32 also operates. Therefore, when the controller 32 executes the main program, it immediately turns on the switching control signal C3, connects the boats rP-AJ and rT-BJ of the electromagnetic switching valve 46 separately, and brings the pipes 43 and 48 into communication. As a result, the flow of hydraulic oil is possible.

Moreover, in parallel with this, each of the acceleration detectors 26 to 28, the vehicle height detectors 30FL to 30RR, and the oil pressure detector 31 also start detection. At this time, since the hydraulic pump 40 is in a non-driving state, the detection signal P of the oil pressure detector 31 is zero, and each detection signal H of the vehicle height detectors 30FL to 30RR has a value corresponding to the passenger getting into the vehicle, etc. . In addition, each acceleration detector 26
~28, although the longitudinal acceleration detector 27 and the vertical acceleration detector 28 should originally have a detected value of "0", due to the tilting of the vehicle body, each due to gravitational acceleration Values affected by the components will be erroneously detected.

However, since the process through steps ■ to ■ in FIG. 5 is executed and the variable coefficient CAD is set to "0", the four-wheeled vehicle body is Each command value T for control.

=O is forcibly calculated. Also, step ■ in Figure 6
, (2), the command value for vehicle height control IN=0, so the respective overall command values 1=1, . is set, and this command value I. is the pressure control valve 20FL~20
Each command is given to RH.

However, when the key switch is in the accessory position, the hydraulic pressure supply device 22 is not operating and the load side is sealed at neutral pressure PM, so no fluctuation in operating pressure occurs. That is, there is no change in the vehicle body posture or vehicle height.

From this state, when the key switch is further switched to the ignition position to start the engine, the hydraulic pump 40 rotates as the engine starts, and hydraulic pressure that rises sharply to a predetermined line pressure is supplied from the hydraulic pressure supply device 22. .

At this time, the hydraulic pressure from the hydraulic pressure supply device 22 is neutral pressure, PH
At the time t0 when the vehicle body attitude control and vehicle height control are started, and the hydraulic oil is transmitted to the load side via the check valve 45, the pilot pressure PP of the operating check valve 49 also becomes PP≧PN. , the check mechanism is released. As a result, the return side piping 49 is brought into communication, allowing free flow of hydraulic fluid.

On the other hand, in parallel with this, at time t0, the process of FIG. 5 passes through the gain adjustment routine of step
The variable coefficient KAD is gradually set larger from zero with the elapsed time, and at the time 10+t1, KAD
=1. In other words, the command value IX related to steps ■ and ■
, I2 gradually increases from zero to a value corresponding to the detected value G, , G2, which should originally be there, and along with this, the calculated value 1. is also temporarily increased from zero to a predetermined value. On the other hand, in the process shown in FIG. 6, step ■ is passed at time t0, and the command value ■□ changes from zero to vehicle height deviation e over time.
It increases slowly at a constant slope until the value becomes ≦O.

Therefore, the total pressure command value I commanded in the process shown in FIG. 7 is r=1 at time t0. After that, it gradually increases as time passes, and at time jo+t+, it reaches the normal value for attitude control, and even though the vehicle is stopped on a slope, the hydraulic cylinder 18FL on the upper side of the plate,
The working pressure of 18FR (or 18RL, 18RR) is gradually increased, and the hydraulic cylinders 18RL and 18RR on the upper side of the plate are
The operating pressure of 18RR (or 181'L, 1BPR) is gradually lowered. On the other hand, in vehicle height control, the vehicle height control end time is determined depending on the degree of vehicle height deviation e, and at the end time,
Each wheel almost reaches the target vehicle height H0.

Therefore, even when the engine is started to start the vehicle from parking on a slope, the vehicle body posture and vehicle height are gradually controlled, thereby preventing sudden changes in vehicle body posture and vehicle height as in the prior art.

Furthermore, after the time to+t+ has elapsed, the variable coefficient KAD=1 is maintained as described above, so normal attitude control is possible. In other words, the detected acceleration value Gy associated with driving,
Specified gain KV for GX and Gz.

Command value IV corresponding to the command value of K, , multiplied by 2, respectively
, 1. ．． I2 is calculated in the process shown in FIG.
It is given as appropriate from L to 18RR, and posture change is suppressed. On the other hand, if there is a change in the number of passengers, etc., the same slow vehicle height adjustment is performed through the process shown in FIG.

Then, stop the vehicle again and replace the key switch with the accessory.
By positioning the engine 41, the rotation of the engine 41 is stopped.
Along with this, the output pressure of the hydraulic pressure supply device 22 rapidly decreases to zero. Then, by turning off the key switch, the power supply to the controller 32 is also cut off, so the switching control signal C3 is turned off, and the electromagnetic switching valve 46 again cuts off the connection between ports rP-A and boat rT-A-BJ. communicate between. As a result, the pressure control valves 20FL to 20!
? ! ? The supply side and the return side are connected with almost zero flow path resistance, and the throttle 46b is inserted between these two and the tank 42 side, so the hydraulic oil accumulated in the Akinimulator 25° 25 is immediately reduced to pressure. It rapidly flows into the return side of the control valves 20FL to 20RH, raising the back pressure close to the supply pressure. After that, the tank 4 gradually passes through the throttle 46b.
Return to side 2 and reduce pressure. When this pressure drop falls below the neutral pressure PN, the operating check valve 49 starts checking, so that each hydraulic cylinder 18
The operating pressure of the FL-18RR is contained in the PM, and a predetermined vehicle height is maintained.

In this way, the electromagnetic switching valve 46 also has the function of creating back pressure, so even if the controller 32 fails and each command value I suddenly drops to zero, a so-called fail occurs, it can be quickly The neutral pressure P8 of the four wheels can be ensured. Therefore, it is possible to prevent the vehicle body from rapidly lowering when a failure occurs.

In the first embodiment, steps ■ to ■ in FIG. 5 and the process in FIG. 7 correspond to the command value calculation means, and step
, (2) and the oil pressure detector 31 constitute the communication timing detection means, and further, the processes (2) and (2) in FIG. 5 correspond to the variable coefficient setting means.

In the first embodiment, the case where the vehicle is parked on a slope inclined in the longitudinal direction is explained, but the same effect can be obtained even if the slope is further inclined laterally. . Furthermore, even if each of the acceleration detectors 26 to 28 is an AC type and there is an erroneous detection in which the detected value is not zero even though no acceleration is being applied, sudden changes in control start due to the detected value can be detected. Can be eliminated. These are described in Section 2.3 below.
The same applies to the embodiments.

(Second Embodiment) Next, a second embodiment of the present invention will be described in FIG.
This will be explained based on FIG. Since the hardware configuration of this second embodiment is the same as that of the first embodiment, the same reference numerals are used for the same components, and the explanation thereof will be omitted.
The same applies to the third embodiment described later).

The operation of this embodiment will be explained.

The controller 32 performs the processes shown in FIG. 8 (corresponding to FIG. 6), FIGS. 6 and 7 using timer interrupts of the same cycle.

First, the process shown in FIG. 8 will be explained at step ①.

The process (2) is the same as that in FIG. 5 of the first embodiment.

Therefore, in the case of "NO" in step ■, the variable coefficient KAn'+' for the lateral acceleration is set to 0 in step ■a, and the detection signal Gy of the lateral acceleration detector 26 is read in step ■a, and the value is memorized. Proceed to step (a). In step (a), the pressure command value IV for the lateral acceleration is set to I
Calculate as y=Gy·KVKAIIV. Here, K is a prescribed (fixed) gain.

In addition, while performing interrupt processing, if rYEsJ is determined in the step (■), the process proceeds to step (a) and it is determined whether the lateral acceleration G, stored immediately before, is GV≧A in step (a). do. A is a set value that can discriminate the magnitude of the generated lateral acceleration Gy. If rNOJ is determined in this judgment, the variable coefficient K AoV is set to "1" in step (a) as a value that does not require sudden change prevention, and then the process proceeds to step (a).

Furthermore, while proceeding with the interrupt processing, the step
In the case of rYESJ, it is determined that sudden change prevention is necessary because the value Gv of the lateral acceleration is relatively large, and the process moves to step (a). In this step ■, the computer becomes "0" at the time of the judgment, increases at a constant slope kv as time passes, and becomes "1" after t1 elapses, that is, the step
Set the variable coefficient KADV to be the same as the value set in pump (a). After this, the calculation in step (a) is performed.

On the other hand, longitudinal acceleration G8. Regarding the vertical acceleration G2, the following steps ■b to ■b are also processed.

The processing of steps ①C to ①C is similarly executed, and the command value lXlI2 is calculated by the processing of steps ②b and ①C. Here, the determinations in steps (2) b and (2) C are made based on the flag processing in step (2) a. Also, K.A.
lx, KAEI□ is longitudinal acceleration GX + vertical acceleration G
It is a variable coefficient for 2. Variable coefficient KADvh KA
The slopes kV and kXk2 with respect to nx*KAoz are set to different values. Furthermore, B.

C is a setting value having the same meaning as the setting value A described above.

Then, in step ① of Fig. 8, 4
Ring command value■. ,..., lG is the command value! .

It is calculated by adding up IX and I2 in the same way as in the first embodiment.

Furthermore, the vehicle height control is performed in the same manner as shown in FIG. 6 of the first embodiment, and the overall calculation of the entire pressure command value I is also carried out in the first embodiment.
This is similar to FIG. 7 showing the embodiment.

Next, the overall operation will be explained.

When the engine 41 is rotationally driven from the parked state, each acceleration G't*GK+02 due to the gravitational acceleration immediately before the discharge pressure of the hydraulic pressure supply device 22 reaches the neutral value P8 is shown in steps ■a and ■b in FIG. , ■stored in C. and,
These values GV+GX+G2 are compared with threshold values A, B, and C, respectively (steps ``a'', ``b'', and ``c'') to confirm the acceleration occurrence situation. As a result, one of the three has a darkness value of A,
B.

If the acceleration is equal to or lower than C, the outputs of the acceleration detectors 26 to 28 are small at the start of control for that acceleration;
Since the influence on the vehicle body posture and vehicle height is small, the variable coefficients KAoy, KADx, and KAD2 are set to "1", and normal control is performed quickly in steps ■a, ■b, and ■C). On the other hand, if acceleration equal to or greater than the dark values A, B, or C occurs in any direction, it is necessary to prevent sudden changes, and the variable coefficient is set to 0. .

Gradually change KAD, , KA, □ (step ■
a.

(b), (c), the same control as in the first embodiment is performed. Other operations are the same as in the first embodiment.

In the second embodiment, steps ■a, ■b, and ■C in FIG.
1■a, ■b, ■C1■, and the processes in FIG. 7 correspond to the command value calculation means, and the hydraulic pressure detector 31 and the processes in steps ■, ■a, ■b, and ■C in FIG. It constitutes a communication timing detection means, and steps ■a, ■b, and ■ in FIG.
C1 ■a, ■b.

(2) Processing in C corresponds to variable coefficient setting means.

Therefore, the second embodiment also provides the same effects as the first embodiment, and also provides the same effects as the first embodiment.
Parking road condition (slope, bank) and acceleration detector 26~
It is possible to determine the magnitude of the output error of 28 itself, and to prioritize and speed up the control speed for output errors that are unlikely to cause a sense of anxiety to the occupants. In addition, darkness values A, B, C and variable coefficients KADY I KAD are set for the horizontal direction, vertical direction, and vertical direction.
Since x l KAl12 can be set individually, detailed control such as varying the adjustment speed is possible.

(Third Embodiment) Next, a third embodiment of the present invention will be described in FIG. 9 and the above-mentioned sixth embodiment.
This will be explained based on FIG.

The controller 32 performs the processes shown in FIG. 9 (corresponding to FIG. 6), FIGS. 6 and 7 using timer interrupts of the same cycle.

First, the process shown in FIG. 9 will be explained at step ①.

The process (2) is the same as that in FIG. 5 of the first embodiment.

Therefore, when the judgment is "NO" in step ■, the variable coefficient Kao is set to 0 in step ■, and steps
Shift to processing. That is, in step (2), the lateral acceleration detection signal Gv is input, and the specified gain is multiplied by (fixed value) to obtain the command (11v.Similarly, in step (2)
In 5■, the command value 1. for the longitudinal and vertical acceleration detection signals G, , G. ,! , find.

Next, proceed to step ■, and add the command values Iv, IX, and 1g to each other in the same manner as step ■ in FIG.
After calculating L+'□+IRL, the process moves to step (■). In step ■, pressure command value IFII + IF
L+ IRR+ 'Calculate the maximum value in ILO and set that value as IN□.

Next, move to step ■ and reach the maximum value ■ of the pressure command value ^
is divided by the minute change width k of the command value in vehicle height control (see step ■ in Figure 6), and the number of output cycles (time) is calculated.
By calculating D and counting the number of cycles, "1" is obtained.
, and calculate the slight amplification g per one operation period of the variable coefficient KAD.

Here, the number of output cycles is the number of times required to absorb and correct the pressure adjustment speed corresponding to the maximum command value MAX with the adjustment speed of vehicle height control, and 1/D is calculated by D times. This is because the variable coefficient KAD is set to "1" after the output control.

Next, in step [phase], the calculated value I of step ■
FRI I FLI I R11l I RL
is multiplied by the variable coefficient KAD set at that time to obtain the first command value IG(F'R
)+ t61FL)l IG(R'lt)+I G (
RL) and then returns to the main program.

On the other hand, when rYE and sJ are determined in step (2), the process moves to step (2). In this step (2), the variable coefficient KAD is gradually increased by the slight amplification g set in step (2).

Next, the process moves to the above-mentioned step [phase] via steps @ to [phase]. Among these, steps @ to ■ are the same processes as steps ■ to ■, and step ■ is the same process as step ■.

Furthermore, vehicle height control is performed using the same process as in FIG. 6 of the first embodiment (in that case, each command value IH becomes the second command value), and the overall pressure command value I for the four wheels, ...
, ■ are also processed in the same way as in FIG.

Next, the overall operation will be explained.

After the engine 41 is rotated in the parked state, until the discharge pressure of the hydraulic pressure supply device 22 reaches the neutral pressure P1, the variable coefficient KAD is set to zero (step ■ in Fig. 9), and the pressure is adjusted to the detected acceleration value. Command value IFL+ IFL+
Find the slight amplification g of the variable coefficient KAI based on the maximum value INA in I□, IIIL and wait (step ■
~■). However, in this state. Since = 0,
Each first command value I becomes = 0 (step [phase] in the figure),
No attitude control is provided.

When P≧PN from this standby state, P = P sO
At this point in time, the variable coefficient is KAo-0, but as time passes, it is slightly increased by the g value, and Kao is set to 1 in the D-th interrupt process from the time when P=PN is determined (step 2 in the figure). The acceleration detectors 26 to 2 gradually increase in response to the increase in the variable coefficient KAI+- from 1 to 1.
The first command value I G (Fl) + 1 based on the detected value of 8
6 (FL) + I G (IIR) + I O□L,
is calculated (steps @~■, [phase] in the figure). However, the hydraulic cylinders 18FL to 18RR depend on each command value I6.
Since the change in operating pressure is the same as that caused by vehicle height control, all vehicle behavior at the start of control can be absorbed by vehicle height control, resulting in very smooth changes in vehicle height, and sudden changes in vehicle body posture can be avoided.

Other functions and effects are the same as in the 1.2 embodiment.

In the third embodiment, steps ① to ② in FIG.

[Phase], steps ■ to [phase] in FIG. 6, and the processing in FIG. 7 correspond to the command value calculation means, and step ■ in FIG. 9.

■, Processing of steps ■ and ■ in Fig. 6, and oil pressure detector 3
1 constitutes a communication timing detecting means, and the processes of steps ① to ② and ① in FIG. 9 correspond to the variable coefficient setting means.

In the third embodiment, the attitude control based on the detected acceleration value is performed at the same rate of change as the vehicle height control, but the invention as claimed in claim (3) is not limited to this, and the maximum Command value! □ By setting the change width k that divides 8 to be smaller than the value for vehicle height control, the attitude control based on the detected acceleration value becomes less than the speed of the vehicle height control, and the attitude control is completely absorbed into the vehicle height control. It can be done with

Further, in each of the embodiments described above, the acceleration in each direction is directly detected by the detectors 26 to 28, but the present invention is not necessarily limited to this. Based on the change speed, brake pedal speed, vehicle speed, and relative displacement between wheels and vehicle body, lateral around 9,
An estimator for estimating vertical acceleration may be provided (for example, see Japanese Patent Laid-Open No. 62-295714). On the other hand, the acceleration detector and estimator in each of the above embodiments may be used in only one direction or two directions.

Further, although the communication timing detection means in each of the embodiments described above is configured to include the oil pressure detector 31, it is not limited to this, and for example, the engine rotation speed may be detected, and this detection value may be a rotation corresponding to the neutral pressure P8. It may be configured such that such control is started when the number is reached.

Furthermore, in each of the above embodiments, the hydraulic cylinder 18F
Although the enclosing value of the operating pressure of L to 18RR is set to the neutral value PN, it may be another predetermined value. Further, the fluid pressure cylinder in the present invention may be a flow rate control type cylinder or a pneumatic cylinder in addition to those described above.

〔Effect of the invention〕

As explained above, the invention according to claim (1) is provided when the engine is driven from a stopped state at a predetermined vehicle height, the fluid pressure supply device is driven, and the supply pressure to the pressure control valve reaches the set value. , the pressure control valve and the fluid pressure supply device are switched from the previous cutoff state to the communication state, and the variable coefficient by which the acceleration output value is multiplied for a certain period from the time of the judgment is gradually changed from "0" to "1". Because the pressure command value is increased, the pressure command value will not suddenly rise to the value under normal control, but will increase gradually. Even if you start the engine when the engine is stopped on a road surface or in a position that requires estimation, or if there is an output error in the acceleration detector or estimator, sudden changes in the vehicle position or vehicle height can be eliminated, and the vehicle will slowly return to the specified position. This results in a controlled attitude and vehicle height, and as a result, it is possible to reliably eliminate the feeling of anxiety among the occupants due to such sudden changes.

Furthermore, in the invention as set forth in claim (2), since the variable coefficient described above can be set to an individual increase speed depending on the direction of the vehicle, it is possible to obtain finely controlled speeds depending on the direction of the vehicle.

Furthermore, in the invention described in claim (3), vehicle height control is performed in addition to the method described in claim (1), and
Since the attitude control based on the detected acceleration value or the estimated value is absorbed into the vehicle body control and gradually performed, it is possible to achieve the effect that the vehicle can transition to a normal control state with very smooth vehicle behavior as soon as the control is started.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are diagrams corresponding to the claims of this invention, respectively;
Fig. 2 is a configuration diagram showing the first embodiment, Fig. 3 is a graph showing the relationship between the command value and output pressure in the pressure control valve, and Fig. 4 shows the hydraulic pressure supply device and flow path opening/closing part of the first embodiment. 5 to 7 are flowcharts showing the processing procedure of the first embodiment, FIG. 8 is a flowchart showing a part of the processing procedure of the second embodiment of the present invention, and FIG. It is a flowchart which shows a part of processing procedure of 3rd Example of invention. In the figure, 12 is a wheel side member, 14 is a vehicle body side member, 16 is an active suspension, 18FL-18RR is a hydraulic cylinder as a fluid pressure cylinder, 20FL to 20RR are pressure control valves, and 22 is a hydraulic pressure as a fluid pressure supply device. feeding device,
26 is a lateral acceleration detector, 27 is a longitudinal acceleration detector, 28
30FL to 30RR are vehicle height detectors, 31 is an oil pressure detector, 32 is a controller, 45 is a check valve, and 49 is an operating check valve.

Claims (3)

[Claims] (1) A fluid pressure cylinder inserted between the vehicle body and the wheels,
A pressure control valve that controls the operating pressure from a fluid pressure supply device supplied to this fluid pressure cylinder according to a pressure command value, and when the supply pressure to this pressure control valve falls below a set pressure,
The pressure control valve and the fluid pressure supply device are shut off, and the working pressure of the fluid pressure cylinder is sealed to the set pressure, and when the supply pressure exceeds the set value, the pressure control valve and the fluid are closed. an operating pressure sealing means for communicating between the pressure control valve and the fluid pressure supply device; and a communication timing detection means for detecting a timing at which the operating pressure sealing means brings the pressure control valve and the fluid pressure supply device into communication from a blocked state to a communication state. , an acceleration detector or an estimator that detects or estimates acceleration acting on the vehicle, and the communication timing detection means maintains "0" before detecting the communication timing, and changes from "0" when the communication timing is detected. a variable coefficient setting means for setting a variable coefficient that gradually increases over time up to "1", and a command value for calculating a pressure command value including a value obtained by multiplying the output value of the acceleration detector or estimator by at least the variable coefficient; An active suspension characterized by comprising a calculation means. (2) The acceleration detector or estimator is an acceleration detector or estimator in at least two directions among a lateral acceleration detector or estimator, a longitudinal acceleration detector or estimator, and a vertical acceleration detector or estimator. The command value calculation means is configured to multiply the output values of the acceleration detector or estimator in at least two directions by respective variable coefficients, and the variable coefficient setting means multiplies each variable coefficient in the command value calculation means. The active suspension according to claim 1, wherein the rate of increase of the coefficient is individually set. (3) A fluid pressure cylinder inserted between the vehicle body and the wheels;
A pressure control valve that controls the operating pressure from a fluid pressure supply device supplied to this fluid pressure cylinder according to a pressure command value, and when the supply pressure to this pressure control valve falls below a set pressure,
The pressure control valve and the fluid pressure supply device are shut off, and the working pressure of the fluid pressure cylinder is sealed to the set pressure, and when the supply pressure exceeds the set value, the pressure control valve and the fluid are closed. an operating pressure sealing means for communicating between the pressure control valve and the fluid pressure supply device; and a communication timing detection means for detecting a timing at which the operating pressure sealing means brings the pressure control valve and the fluid pressure supply device into communication from a blocked state to a communication state. , a vehicle height detector that detects a vehicle height value, an acceleration detector or estimator that detects or estimates acceleration acting on the vehicle, and a value based on the output value of the acceleration detector or estimator multiplied by at least a variable coefficient. Command value calculating means for outputting a command value including a first command value and a second command value by integral control from an initial value "0" when there is a deviation between the detected value of the vehicle height detector and the target vehicle height value. The variable coefficient is maintained at "0" before the communication timing detecting means detects the communication timing, and gradually increases from "0" to "1" with time when the communication timing is detected. a variable coefficient setting means for setting a coefficient such that a rate of change in the working pressure of the fluid pressure cylinder due to a change in the first command value is equal to or less than a rate of change in the working pressure due to a change in the second command value; The active suspension is characterized by the following features: