JP2798282B2 - Height adjustment device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle height adjusting device for adjusting the height (vehicle height) of a vehicle, and in particular, a vehicle having a high center of gravity such as a one-box vehicle or a trailer. The present invention relates to a vehicle height adjusting device suitable for a vehicle.

[Conventional technology]

Conventionally, various types of height adjustment devices have been developed and used.
There is one described in 62-94411. According to this conventional device, when the detected vehicle speed exceeds a preset reference vehicle speed, the vehicle height is controlled to be automatically reduced, thereby ensuring running stability during high-speed running.

[Problems to be solved by the invention]

However, the vehicle height adjustment timing by such a conventional vehicle height adjustment device is performed only when the vehicle travels at a high speed and the vehicle speed detection value exceeds a predetermined reference value, and is independent of the load. , The loading load is large, and
If the vehicle speed detection value is slightly lower than the reference value and the vehicle travels in a medium speed state, the vehicle height reduction control is not performed. As a result, in vehicles with a high center of gravity such as one-box vehicles and trailers, There has been an unsolved problem that steering stability is reduced when turning such as when changing lanes.

The present invention is intended to improve the unresolved problem of such a conventional device, and even for a vehicle having a high center of gravity,
It can be controlled to an appropriate vehicle height value that matches the vehicle speed and load capacity,
It is an object to solve the problem to surely improve the steerability during turning.

[Means for solving the problem]

In order to solve the above problems, the present invention, as shown in FIG. 1, comprises an actuator interposed between a wheel and a vehicle body and capable of changing a stroke between a sprung and unsprung state, and an operation of the actuator as a command signal. An actuator driving unit that controls the vehicle speed according to the vehicle speed, and a vehicle speed adjustment unit that changes the command signal according to a detection value of the vehicle speed detection unit. When a vehicle speed detection value becomes equal to or more than a changeable vehicle speed reference, a vehicle height reduction control unit that provides a command signal for reducing the vehicle height value to the actuator driving unit is provided, and a load detection unit that detects a loaded load of the vehicle. Vehicle speed reference value changing means for changing the vehicle speed reference value according to the load detection value of the load detection means.

[Action]

The vehicle height reduction control means performs control to reduce the vehicle height value when the detected vehicle speed value exceeds the vehicle speed reference value, and the vehicle speed reference value is determined by the load detection means detected by the load detection means by the vehicle speed reference value changing means. It decreases as the detected value of the load increases. For this reason, as the vehicle travels with a larger load, the start point of the control for lowering the vehicle height is lower than in the traveling state with a smaller load. Therefore,
When a vehicle with a high center of gravity, such as a one-box vehicle, runs at high speed with a large load, the timing of shifting to a decrease in vehicle height is advanced.

〔Example〕

Hereinafter, one embodiment of the embodiment of the present invention will be described with reference to FIGS.
A description will be given based on the drawings. In this embodiment, the vehicle height adjusting device is implemented as a hydraulic suspension.

In FIG. 2, 2FL to 2RR indicate front left to rear right wheels, 4 indicates a wheel side member, and 6 indicates a vehicle body side member. A single rod as an actuator, a single-acting hydraulic cylinder 8FL (.about.8RR), and a coil spring 10FL (.about.10RR) supporting the vehicle body are provided between the wheel side member 4 and the vehicle body side member 6, respectively. Each of the hydraulic cylinders 8FL to 8RR is a cylinder tube
8a is connected to the wheel side member 4, the piston rod 8b is connected to the vehicle body side member 6, and the piston 8c separates the cylinder chamber R in the cylinder tube 8a.

The cylinder chamber R of the hydraulic cylinders 8FL to 8RR
The pipes 12 respectively reach the cylinder ports A of the electromagnetic directional control valves 16FL (（16RR) as actuator driving means to be described later via the variable throttle valves 14 individually.
Each of the variable throttle valves 14 has a well-known configuration in which the cross-sectional area of the flow path, that is, the damping force is switched in a plurality of (for example, three) stages by the rotation of the motor 18.
Control whereas signal S ₁ is supplied, a position sensor incorporated in the detecting the position of the shutter for varying the flow path cross-sectional area, and outputs the detection signal PC to the controller 20 from.

Further, first and second accumulators 22a and 22b functioning as gas springs are branched from a pipe 12 between each of the variable throttles 1 and the direction switching valve 16FL (up to 16RR). Of these,
Each branch path to the second accumulator 22b, 2-port, Yes by interposing a solenoid shutoff valve 24 of the normally closed type, open and close the branch passage by the control signal S ₂ supplied from the controller 20 to the solenoid 24A I can do it.

In the present embodiment, each of the electromagnetic directional control valves 16FL to 16RR is configured as a 3-port, 3-position spring center type,
Control signals S ₃ and S ₄ supplied from the controller 20 are supplied to both the solenoids 16A and 16B, respectively. Then, the switching valve 16FL~16RR, if the control signal S _3, S ₄ are both off, taking the pump port P, a tank port T, and a normal position to respectively block the cylinder port A, the signal
S ₃ is turned on, when S ₄ is off, taking the offset position communicating only pump port P and the cylinder port A,
Opposed to the signal S ₃ is turned off, if S ₄ is on, takes the offset position to communicate only cylinder port A and the tank port T.

In FIG. 2, reference numeral 26 denotes a hydraulic pressure supply device. The hydraulic supply device 26 includes a tandem hydraulic pump 28 that uses a vehicle engine as a rotational drive source, a reservoir tank 30 that stores oil,
At least a relief valve 32 for setting the line pressure and a check valve 34 are provided. Then, the discharge port of the hydraulic pressure supply device 26 passes through the supply side pipe 36 and the electromagnetic directional switching valves 16FL to 16FL
The drain port of the hydraulic pressure supply device 26 is connected to the pump port P of the RR, and the drain port of the hydraulic pressure supply device 26 is connected to the switching valve 16 FL via a drain side pipe 38.
.About.16RR are branched and connected to each tank port T, respectively.

Further, at the wheel positions 2FL to 2RR, vehicle height sensors 40FL to 40RR each constituted by, for example, a potentiometer are provided between the wheel side member 4 and the vehicle body side member 6, respectively. The vehicle height sensor 40FL~RR is unsprung, a vehicle height signal H _FL to H _RR made by the voltage signal corresponding to the relative spacing amount between the upper spring respectively detected, and supplies it to the controller 20.

Further, the hydraulic suspension of this embodiment is provided with a longitudinal acceleration sensor 42, a lateral acceleration sensor 44, and a vehicle speed sensor 46, and these detection signals, V, are also supplied to the controller 20 in the same manner. I have. Also, the pressure in the cylinder chamber R of the hydraulic cylinders 8FL to 8RR is
The detection signals P _{FL to} P _RR are supplied to the controller 20 respectively.

On the other hand, the controller 20 has a microcomputer mounted thereon, and has an A / D converter, a D / A converter, and a drive circuit on the input side and the output side as necessary. And
The controller 20 detects each detection signal,, V, H _{FL to} H _RR , P _FL
To P _RR, CP, ..., enter a CP, performs each operation according damping force of the suspension spring constant, the vehicle height adjustment based on a program stored in advance, the control signals S _1, ..., S _1, S ₂ ,…,
_{S 2, S 3, ...,} S 3, and S _4, ..., each motor 18, which is a damping force control actuator described above with S _4, the solenoid 24A is a gas spring constant switching actuator, and the switching valve 16FL~16R
It supplies to each solenoid 16A, 16B of R.

 Next, the operation of this embodiment will be described.

When the ignition switch is turned on, the controller 20 is also activated, whereby the controller 20 starts arithmetic processing according to a predetermined processing procedure. That is, the damping force and the gas spring constant control and the vehicle height adjustment control shown in FIG. 3 are performed by a timer interrupt at regular intervals during execution of the predetermined main program.

Among them, the damping force and the gas spring constant control are based on the detection signals of the longitudinal acceleration sensor 42, the lateral acceleration sensor 44 and the vehicle speed sensor 46, and V, and the predetermined roll condition is turned on, and the acceleration condition and the deceleration condition are controlled. Medium suspension characteristics (within damping force) when a certain value is exceeded
Or a control signal of a predetermined value to make it hard (large damping force)
S _1, ..., and outputs the S _1, the control signal S ₂ so as to the gas spring constant and large, ..., and turning off the S _2. Thus, in the roll generation state or the rapid acceleration / deceleration state, the damping force becomes medium or large, and the change in the body posture can be suppressed. On the other hand, when the vehicle state determined based on each detection signal and V does not satisfy the constant roll condition and acceleration / deceleration condition, the control signal S of a predetermined value is set to make the suspension characteristics soft (small damping force). _1, ..., and outputs the S _1, the control signal S ₂ so as to the gas spring constant and small, ..., turns on the S _2. This allows
Since the damping force is small, the transmission rate of vibration transmitted from the road surface to the vehicle body is small, and good riding comfort is maintained.

At this time, detection signals H _{FL to} H _{RR of} vehicle height sensors 40FL to 40RR are provided.
May be used to perform the rough road control and the bouncing control together.

On the other hand, in the vehicle height adjustment shown in FIG. 3, at that step, the controller 20 reads the detection signals P _{FL to} P _RR of the pressure sensors 47FL to 47RR respectively, temporarily stores the values as pressure values, and proceeds to the step. In this step, the controller 20 refers to the storage table stored in advance, and calculates the actual loading loads W _{FL to} W _RR by subtracting the weight of the vehicle body for each wheel. The storage table is set such that the load increases as the pressure values P _{FL to} P _RR increase. Next, move on to the step, and calculate the total load for each wheel.
The total load W is calculated by adding W _{FL to} W _RR .

Thereafter, the processing of steps 1 to 3 is performed to determine whether the load is small (for light load) or large (for heavy load), and the two vehicle speed reference values V _TH1 and V _TH2 are determined according to the determination result. adjust. That is, in step, the live load W is against a load threshold W _D to discriminate whether light product or intussusception determines W> W _D,
If “NO”, it is assumed that it is a light load, and “YE
If "S", it is determined that the product has been accumulated and the process proceeds to each step.

In this step, the first vehicle speed reference value V _TH1 is
Set V _1, the predetermined value V ₂ in the second vehicle speed reference value V _TH2 (<V _1: see FIG. 4)) is set. Thus, the vehicle speed reference value is
The reason for providing the second two values is to provide hysteresis when switching the vehicle height value. On the other hand, in the step, the first vehicle speed reference value V _TH1 is set to a predetermined value V ₁ ′, and the second
Predetermined value V ₂ to the vehicle speed reference value _{V TH2 '(<V 1'} : see FIG. 4))
Set. Here, in order to lower the vehicle height at a lower vehicle speed at the time of heavy loading than at the time of light loading, V ₁ ′ <V ₁ and V ₂ ′ <V ₂
Is set to

After the above step or after, the controller 20 shifts the processing to the step and outputs the detection signal V of the vehicle speed sensor 46.
And temporarily stores the value as a vehicle speed value. Next, in a step, the vehicle speed detection value V is set to a first vehicle speed reference value.
V _TH1 compared to, V <V _{if TH1} to be determined further second vehicle speed reference value of the vehicle speed detection value V proceeds to step V _TH2
Compare with As a result, if "NO", that is, V> V _TH2 ,
Since V _TH1 >V> V _TH2 , the control signal
After turning off both S ₃ and S ₄ and instructing or maintaining suspension of the vehicle height adjustment, the process returns to the main program.

On the other hand, if the determination in the above step is “YES”, that is, V ≦ V
_In the case of _TH2 , it is determined that the _vehicle is traveling at a low speed, and the process then proceeds to the processing of steps (1) to (4). That is, in the step, the controller 20 detects the detection signals H _FL of the vehicle height sensors 47FL to 47RR.
HH _RR are read, and their values are temporarily stored. Then, in the step, it is determined whether or not the vehicle height value H _FL (〜H _RR ) matches the target value H _N at the time of low speed, and if “NO”, the process proceeds to the step and the vehicle height values H _FL H _Each of _RR is the target value H _N
It is determined whether it is smaller than. Here, the target value H _N may be the target area having a dead zone.

If "YES" in step decision and proceeds to step, the controller 20 turns on the control signal S ₃ is supplied to the directional control valve 16FL (~16RR) to increase the vehicle height value, turns off the control signal S ₄ And The state of this control signal is held until the next interrupt processing. As a result, the switching valve 16
Since the pump port P of FL (up to 16RR) is connected to the cylinder port A, the pressure oil from the pump 28 is supplied to the hydraulic cylinder 8F.
L (〜8RR), the stroke of the cylinder 8FL (〜8RR) is extended at a predetermined speed determined by the degree of throttle of the variable throttle valve 14, and the vehicle height increases accordingly.

Also, if "NO" in step, the controller 20 turns off the control signal S ₃ is supplied to the directional control valve 16FL (~16RR) to reduce the vehicle height value in step,
A control signal S ₄ is turned on. Thereby, the switching valve 16FL (~
16RR) is connected to the cylinder port A, so that the oil of the hydraulic cylinder 8FL (up to 8RR)
The stroke of the cylinder 8FL (FL8RR) is reduced at a predetermined speed determined by the degree of throttle of the variable throttle valve 14, and the vehicle height is reduced accordingly.

After the command to increase or decrease the vehicle height is issued, the process returns to the main program, and the above-described vehicle height adjustment is repeated. When the determination of “YES” is made in the step, the process proceeds to the step.

On the other hand, in the above step, “YES”, that is, V ≧ V
If it is determined to be _TH1 , the following steps 1 to 3 are repeated. That is, the vehicle height values H _{FL to} H _RR are read in the step, and it is determined in the step whether the vehicle height value H _FL (（H _RR ) matches the target value _HL at the time of high speed, and in the case of “NO” Goes to step to determine whether each of the vehicle height values H _{FL to} H _RR is smaller than the target value _HL . Here, the target value H _L
May be a target area having a predetermined dead zone.

If "YES" in step decision and proceeds to step, the controller 20 turns on the control signal S ₃ is supplied to the directional control valve 16FL (~16RR) to increase the vehicle height value, turns off the control signal S ₄ And As a result, the vehicle height value increases at a predetermined speed in the same manner as in the processing of the step.

Also, if "NO" in step, the controller 20 turns off the control signal S ₃ is supplied to the electromagnetic direction switching valve 16FL (~16RR) to reduce the vehicle height value in step,
A control signal S ₄ is turned on. As a result, the vehicle height is reduced in the same manner as in the processing in the step.

After the command to increase or decrease the vehicle height is issued in this manner, the process returns to the main program, repeats the above-described vehicle height adjustment, and when the determination of “YES” is made in the step, proceeds to the step, After stopping the height adjustment as described above,
Return to the main program.

In the present embodiment, the above-described vehicle height adjustment control is repeated, and the reference value on which the vehicle height control is based is changed depending on whether the vehicle is lightly loaded or heavyly loaded. In other words, as shown in FIG. 4, when the vehicle height reference values V _TH1 and V _TH2 are set to be lower than when lightly stacked, the vehicle height reference values V _TH1 and V _TH2 are set lower than when lightly stacked. Therefore, a low vehicle height posture state required during heavy-duty and high-speed running is accurately performed. This allows
When traveling in a state of intussusception and medium / high speeds, it does not reduce the steering stability during steering and exerts an influence on the cruising speed as compared with the conventional case where the vehicle height is reduced only according to the increase in vehicle speed. The adverse effects can be reduced. Therefore, it is particularly advantageous in a vehicle having a high center of gravity such as a one-box vehicle or a trailer.

On the other hand, since a small amount of movement of the center of gravity by turning the vehicle speed V is small regions, ensuring a predetermined vehicle height H _N, it may eliminate interference with the road surface irregularities.

As described above, in the present embodiment, the vehicle speed sensor 46 and the processing of the step in FIG.
The processing of 47RR and the steps from FIG. 3 constitute the load detecting means. 3 correspond to the vehicle speed reference value changing means, and FIG.
Corresponds to the vehicle height reduction control means.

Incidentally, the actuator of the present invention is not necessarily limited to the one using the hydraulic cylinder described above, for example, a configuration using an air chamber exemplified in Japanese Patent Application Laid-Open No. 62-289417 already proposed by the present applicant. There may be.

Further, the vehicle height reduction control means and the vehicle speed reference value changing means in the present invention are not limited to the configuration in which each of the two states is controlled according to the vehicle speed or the magnitude of the load as described in the above embodiment. For example, a configuration may be adopted in which three or more control states are adopted according to the vehicle speed or the magnitude of the load, and the vehicle height may be adjusted more finely.

Further, contrary to the above embodiment, the reference value for lowering the vehicle height can be lowered as the load detection value becomes smaller. This makes it possible to improve the stability of a vehicle such as a one-box car, whose stability is likely to be impaired when receiving a crosswind at the time of light load.

〔The invention's effect〕

As described above, the present invention reduces the vehicle height value when the vehicle speed detection value becomes equal to or more than the changeable vehicle speed reference value, detects the loaded load of the vehicle, and determines the vehicle speed reference value according to the detected load value. The value is changed so that when the vehicle is traveling at high speed with a large load, the vehicle height decreases when the vehicle speed becomes higher than the vehicle speed reference value set lower than when the load is small. The timing of vehicle height reduction is faster than before,
Thereby, in particular, it is possible to surely improve the operability when the one-box vehicle or the trailer is stacked and the vehicle is traveling at a medium or high speed.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention, FIG. 2 is an overall block diagram showing an embodiment of the present invention, and FIG. 3 is a schematic diagram showing an example of a processing procedure of a vehicle height adjustment executed by a controller. FIG. 4 is a flowchart showing an example of the vehicle height adjustment which changes according to the load and the vehicle speed. In the figure, 2FL to 2RR are wheels, 4 is a wheel side member, 6 is a vehicle body side member, 8FL to 8RR is a hydraulic cylinder, 16FL to 16RR is an electromagnetic directional control valve, 20 is a controller, 46 is a vehicle speed sensor, and 47FL to 47RR.
Is a pressure sensor.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-58-183304 (JP, A) JP-A-2-106418 (JP, A) JP-A-63-125418 (JP, A) JP-A-63-125418 279914 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B60G 17/015

Claims (1)

(57) [Claims] An actuator interposed between a wheel and a vehicle body and capable of changing a stroke between a sprung and unsprung state;
A vehicle height adjustment comprising actuator driving means for controlling the operation of the actuator according to a command signal, and vehicle speed detecting means for detecting a vehicle speed, wherein the command signal is changed according to a detection value of the vehicle speed detecting means. In the apparatus, when a vehicle speed detection value of the vehicle speed detection means becomes equal to or more than a changeable vehicle speed reference value, a vehicle height reduction control means for giving a command signal to reduce the vehicle height value to the actuator driving means is provided, A vehicle height adjusting device comprising: a load detecting means for detecting a loaded load; and a vehicle speed reference value changing means for changing the vehicle speed reference value in accordance with the detected load value of the load detecting means.