JPH0452085Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention relates to the improvement of hydroneumatic suspension. Specifically, when adjusting the height of the vehicle while driving, the wheels move up and down according to the unevenness of the road surface. Regarding measures to improve controllability when

(Prior Art) Conventionally, as a hydroneumatic suspension, as disclosed in, for example, Japanese Utility Model Application Publication No. 57-19112, a damper consisting of a cylinder device that absorbs the vertical vibration of a wheel and a hydraulic pressure of the damper have been used. A vehicle is known that is equipped with an accumulator that communicates with a chamber and performs a spring action to adjust the vehicle height.

(Problem to be solved by the invention) By the way, in the above-mentioned hydroneumatic suspension, when adjusting the vehicle height upward, the switching valve of the hydraulic circuit is switched to the oil supply position, and then the oil pump is turned off. The hydraulic pressure is divided by a diversion valve and supplied to four cylinder devices corresponding to the front, rear, left and right wheels, thereby raising the piston rod and adjusting the vehicle height.

However, when the vehicle height is adjusted to increase while the vehicle is running, when one wheel vibrates up and down in response to unevenness on the road surface, the corresponding cylinder device suddenly bumps and the oil pump discharges. Therefore, the circuit pressure flows back to the diverter valve and prevents the hydraulic pressure from acting on the cylinder device corresponding to the other wheel. , a problem arises in that the vehicle height adjustment function for other wheels stops. Furthermore, the flow divider valve may be damaged due to the backflow of circuit pressure to the flow divider valve. Furthermore, in order to prevent the circuit pressure from flowing backward, it is necessary to set the pump relief pressure correspondingly higher, but in this case, the oil pump becomes larger.

The present invention was developed in view of the above, and its purpose is to prevent the high circuit pressure generated due to the vertical vibration of the wheels from flowing back to the diverter valve. The hydraulic pressure is reliably applied to the cylinder device corresponding to the wheel of the vehicle, ensuring the vehicle height adjustment function, preventing damage to the diverter valve due to backflow of high circuit pressure, and reducing pump relief pressure. The objective is to reduce the size of the oil pump by setting the oil pump at a low value.

(Means for Solving the Problem) In order to achieve the above object, the solution means of the present invention is a hydroneumatic suspension, in which a fluid actuator that moves a piston rod up and down by supplying and discharging fluid is attached to each wheel. a plurality of suspensions, a pump that supplies hydraulic pressure to each of the fluid actuators, and a hydraulic circuit that communicates the pump and the fluid actuator, and the hydraulic circuit is connected to a common oil passage and a common oil passage. a first branch oil passage for the front wheels and the rear wheel which branches from the front wheel and supplies hydraulic pressure independently to the fluid actuator of the front wheel and the fluid actuator of the rear wheel; and the first branch oil passage for the front wheel and the rear wheel respectively; It is composed of a second branch oil path for the left wheel and a right wheel that further branches from the road and supplies hydraulic pressure independently to the fluid actuators of the left and right wheels. Further, a first diversion valve is arranged at a branch part from the common oil passage to each first branch oil passage, and a second flow division valve is arranged at a branch part from the first branch oil passage to each second branch oil passage. At the same time, a first switching valve that switches the supply and discharge of the working hydraulic pressure to the fluid actuator is arranged in each second branch oil passage downstream of the second branch valve. A check valve is provided for each second branch oil passage between the second diverter valve and the first switching valve to completely prevent hydraulic pressure from the fluid actuator side from acting on the second diverter valve. At the same time, a tank passage communicating with the tank is connected via a second switching valve on the fluid actuator side downstream of the check valve.

(Function) With the above configuration, in the present invention, when adjusting the vehicle height while driving, the wheels vibrate up and down according to the unevenness of the road surface, causing the fluid actuator to bump, which causes a high circuit in the fluid actuator. When pressure is generated, this high circuit pressure passes through the first switching valve to the second switching valve.
Although the flow flows backward through the branch passage, it is blocked by the check valve before reaching the second flow divider valve, so that the high circuit pressure is prevented from flowing back to the second flow divider valve, and the oil pressure from the oil pump is reduced. Fluid actuators corresponding to other wheels are reliably supplied from the second flow divider valve.

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

Figures 1 and 2 show a hydroneumatic suspension system, where 1 is the vehicle body, 2 is the wheel,
2a is a wheel support member that rotatably supports the wheel 2. The lower end of the wheel support member 2a is connected to the frame 1a of the vehicle body 1 via the lower arm 3, and the upper end of the wheel support member 2a is connected to the frame 1a of the vehicle body 1 via the lower arm 3. The lower arm 3 is connected to the vehicle body 1 via a strut 4 that serves as a fluid actuator for adjusting vehicle height, and the lower arm 3 regulates the movement of the wheel 2 in the vehicle width direction, and also dampens the vertical vibration of the wheel 2. A suspension A is constructed in which strut 4 absorbs water.

Reference numeral 5 denotes an oil pump that supplies hydraulic pressure to the strut 4 (fluid actuator), and the oil pump 5 is connected to an engine 7 via a drive belt 6, and follows the rotation of the engine 7. and is driven.

Furthermore, 10 is a hydraulic circuit that communicates the oil pump 5 with four struts 4 (only one strut is shown) on the front, rear, left and right sides. The hydraulic circuit 10 includes a common oil passage 11 to which hydraulic pressure discharged from the oil pump 5 is supplied, and a first oil passage branching from the common oil passage 11.
Front wheel side oil passage 12 and rear wheel side oil passage 13 as branch oil passages, and left wheel side oil passage 15 and right wheel side oil passage 1 as second branch oil passages branching from the front wheel side oil passage 12.
6, and a left wheel side oil passage and a right wheel side oil passage (not shown) as a second branch oil passage branching from the rear wheel side oil passage 13, and each of these four branch oil passages has a corresponding one. Strut 4... is connected in communication,
The branch oil passages 15, 16... are configured to supply hydraulic pressure to the corresponding struts 4.

Further, the common oil passage 11 is connected to the branching point between the common oil passage 11 and the two oil passages 12 and 13 on the front wheel side and the rear wheel side that branch from this.
Front and rear flow divider valve 14 as a first flow divider valve connected to 3
is arranged, and the front and rear flow dividing valves 14 are connected to the common oil passage 11.
It has a function of dividing the hydraulic pressure so that the flow rate flowing from the hydraulic pressure to the branch oil passages 12 and 13 on the front wheel side and the rear wheel side is equally divided into two.

Similarly, at the branch point between the front wheel side oil passage 12 and the two left wheel side oil passages 15 and right wheel side oil passage 16 that branch from there, the front wheel side oil passage 12 is connected to the branch oil passages 15 and 16.
Left and right flow divider valve 17 as a second flow divider valve connected to 6
is arranged, and the left and right flow dividing valve 17 is connected to the front wheel side oil passage 1.
2 to the left wheel side and right wheel side branch oil passages 15, 16
It has the function of dividing the hydraulic pressure so that the flow rate flowing through the two is equally divided into two.

Since the configuration of each branch oil passage is the same, the hydraulic circuit 10 will be mainly described with reference to the system for supplying and discharging the working hydraulic pressure to the strut 4 of the right front wheel. That is, in the middle of the right wheel side oil passage 16, an accumulator 18 that performs a spring action is connected in parallel. The accumulator 18 is connected to the right wheel side oil passage 1.
6 and an oil chamber 18a communicating with the oil chamber 18.
It is provided with a gas chamber 18b in which nitrogen gas or the like is sealed inside, facing the gas chamber 18b, and performs a spring action due to the compressive elasticity of the sealed gas.

In addition, a check is installed in the left wheel side oil passage 15 and the right wheel side oil passage 16 to throttle the oil passages 15 and 16, respectively, on the downstream side of the left and right flow divider valve 17 and on the upstream side of the connection point of the accumulator 18. Slot valves 20 and 21 with valves and electromagnetic leveling valves 22 and 23 as first switching valves that open and close the oil passages 15 and 16 are interposed.

As a feature of the present invention, the left wheel side oil passage 15
And the right wheel side oil passage 16 has a leveling valve 2 downstream of the left and right flow dividing valve 17, respectively.
On the upstream sides of 2 and 23, check valves 39 and
40 is connected to allow only the supply of working hydraulic pressure to the strut 4 and to completely prevent hydraulic pressure from the strut 4 side from acting on the left and right flow dividing valves 17.

In addition, the left wheel side oil passage 15 and the right wheel side oil passage 16
Tank passages 24 and 25 are connected to the strut 4 side downstream of the check valves 39 and 40 and upstream of the throttle valves 20 and 21, respectively, and the tank oil passages 24 and 25 are connected to the tank 26.
is open to the public. Furthermore, each tank oil passage 24,
25 includes an electromagnetic unload valve 27 as a second switching valve that opens and closes the oil passages 24 and 25, respectively.
28 are interposed. When the vehicle height rises, the unload valves 27 and 28 are moved to the cutoff position 27.
By positioning the leveling valves 22, 23 at the communicating positions 22b, 23b, the oil pressure from the oil pump 5 is transferred to the check valves 20a, 20 of the throttle valves 20, 21.
1a to the strut 4 to quickly raise the vehicle height by the upward movement of the piston rod 4a, while when maintaining a predetermined vehicle height, the leveling valves 22 and 23 are positioned at the cutoff positions 22a and 23a, and the unloading valve is By positioning 27 and 28 at communication positions 27b and 28b,
The supply and discharge of hydraulic pressure to and from the strut 4 is stopped to maintain a predetermined vehicle height, and the hydraulic pressure from the oil pump 5 is transferred to the tank 26 via tank oil passages 24 and 25.
unload to. Also, when lowering the vehicle height, the leveling valves 22 and 23 are moved to the communicating positions 22b and 23.
b and unload valve 27,2.
8 to the communication positions 27b, 28b, the hydraulic pressure of the strut 4 is throttled by the throttle valves 20, 21 while the tank oil passages 24, 25
The vehicle height is gradually lowered by discharging the fuel into the tank 26 through the tank 26.

In addition, 30 is a manual operation switch for adjusting vehicle height that outputs or stops a manual vehicle height up command signal as a vehicle height adjustment signal every time it is pressed, 31 is a vehicle height sensor that detects the vehicle height, 32 is a steering angle sensor that detects a steering angle, and 33 is a vehicle speed sensor that detects vehicle speed. Further, 34 is a controller for adjusting the vehicle height, and the controller 34 includes:
The manual vehicle height up command signal (manual vehicle height adjustment signal) from the manual operation switch 30 and the vehicle height adjustment signals of the vehicle height signal, steering angle signal, and vehicle speed signal from the three sensors 31 to 33 are transmitted. The vehicle height change signal (i.e. vehicle height up
signal and vehicle height down signal) to the leveling valves 22, 23 and unloading valves 27, 2.
8 to control the operation of each valve to position it in the shutoff position or the communication position.

Therefore, in the above embodiment, when adjusting the height of the vehicle while the vehicle is running, the oil pressure from the oil pump 5 is discharged to the common oil passage 11 and then the hydraulic pressure is discharged to the front and rear flow dividing valves 14.
The water is divided by the left and right flow divider valve 17 and supplied to the strut 4 for the right wheel via the right side oil passage 16. At this time, for example, when the right wheel 2 moves up and down depending on the unevenness of the road surface, The strut 4 may bump and a circuit pressure higher than the pump discharge pressure may be generated in the right wheel oil passage 16. This high circuit pressure flows back through the right wheel side oil passage 16 via the leveling valve 23 and the throttle valve 21.

However, since the above-mentioned high circuit pressure is prevented from flowing backward by the check valve 40 immediately downstream of the left and right flow divider valve 17, the oil pressure from the oil pump 5 is transmitted from the front and rear flow divider valve 14 to the rear wheel side oil passage 13 to the left and right flow. In addition to being smoothly supplied to the rear wheel strut, the left and right flow dividing valves 17
The oil is also supplied to the left front wheel strut through the left wheel side oil passage 15, thereby ensuring a good vehicle height adjustment function for the left and right rear wheels and the left front wheel.

Moreover, the left and right flow dividing valve 17 by the check valve 40 is
By preventing backflow of high circuit pressure to the left and right flow divider valves 17
In addition, since there is no need to adjust the pump relief pressure to account for the increase in circuit pressure as in the conventional case, the pump relief pressure can be set lower by that amount, and the oil pump 5 can be made smaller.

(Effects of the invention) As explained above, according to the hydroneumatic suspension of the invention, when adjusting the vehicle height while driving, the oil pump discharge pressure generated due to the vertical movement of the wheels can be increased. Since the backflow of high circuit pressure is prevented by a check valve connected directly downstream of the diversion valve in the hydraulic circuit, the hydraulic diversion function of the diversion valve is maintained and the vehicle height can be adjusted for wheels that do not move up and down. Good functionality can be ensured and reliability can be improved. Moreover, damage to the flow dividing valve can be prevented, and the pump relief pressure can be set low, making it possible to downsize the oil pump.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic block diagram showing the overall configuration, and FIG. 2 is a hydraulic circuit diagram of the main parts of the hydroneumatic suspension. 4...Strut (fluid actuator), 4
a... Piston rod, A... Suspension,
5...Oil pump, 10...Hydraulic circuit, 12...
...Front wheel side oil path (first branch oil path), 13...Rear wheel side oil path (first branch oil path), 14...Front and rear flow diversion valve (first flow diversion valve), 15...Left wheel side oil path ( 2nd branch oilway), 16...Right wheel side oilway (2nd branch oilway), 17
...Left and right flow divider valve (second flow divider valve), 22, 23...
Leveling valve (first switching valve), 27, 28...
...Unload valve (second switching valve), 39, 40
……non-return valve.

Claims (1)

[Scope of utility model registration request] A plurality of suspensions each having a fluid actuator for each wheel that moves a piston rod up and down by supplying and discharging fluid, a pump that supplies hydraulic pressure to each of the fluid actuators, and hydraulic pressure that communicates the pump and the fluid actuator. The hydraulic circuit includes a common oil passage, and a first oil pressure circuit for the front wheels and the rear wheel that branches from the common oil passage and supplies hydraulic pressure independently to the front wheel fluid actuator and the rear wheel fluid actuator. A branch oil passage, and a second branch oil passage for the left wheel and the right wheel that further branches from the first branch oil passage for the front wheels and the rear wheel and independently supplies hydraulic pressure to the fluid actuators of the left and right wheels. Further, a first diversion valve is provided at the branch portion from the common oil passage to each of the first branch oil passages, and a second distribution valve is provided at a branch portion from the first branch oil passage to each of the second branch oil passages. and each second valve on the downstream side of the second flow divider valve.
A first switching valve for switching the supply and discharge of working hydraulic pressure to and from the fluid actuator is arranged in each of the branch oil passages, and a first switching valve that switches supply and discharge of hydraulic pressure to and from the fluid actuator is arranged in each of the second branch oil passages between the second branch valve and the first switching valve from the fluid actuator side. A check valve that completely prevents the hydraulic pressure from acting on the second flow divider valve is disposed, and a tank passage communicating with the tank via the second switching valve is provided on the fluid actuator side downstream of the check valve. A hydroneumatic suspension characterized by being connected.