JPH06135216A - Vehicle suspension - Google Patents

Abstract

PURPOSE:To make followability to a vehicle wheel excellent in the case of an oil pressure type suspension by making the area of an orifice that is fitted between pressure oil chambers and conducts damping operation, variable in fact. CONSTITUTION:The upper part cylinder portion of a main body 1 is divided into a gas chamber 3 and an oil pressure chamber 4 by means of a free piston 2, and the oil pressure chamber 4 and the second oil pressure chamber 5 of the lower part cylinder portion are connected to each other by means of two passages 8, 12, and an orifice 81 is fitted to the passage 8, and a poppet valve 11 is interveniently furnished at the passage 12, and the opening/closing control of the poppet valve 11 is carried out by means of a second servo valve 15 in opposition to the movement speed of a connection rod 7. By this, the same effect as the one in which the area of the orifice 81 is made variable, is obtained, and followability to the up and down displacement of a vehicle becomes excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension device which is interposed between a vehicle body of a vehicle and a wheel-side member such as an axle and is used to reduce impact and vibration of the vehicle.

[0002]

2. Description of the Related Art Generally, in order to reduce the impact on the vehicle body and the shaking of the vehicle body between the vehicle body and the axle,
For example, a gas spring type suspension device as shown in FIG. 5 is provided. In FIG. 5, reference numeral 1 indicates a main body,
A free piston 2 is slidably mounted in the closed upper cylinder portion 1a of the main body 1 by packings 2a and 2b while keeping airtightness. Reference numeral 3 denotes a gas chamber above the free piston 2 in the upper cylinder portion 1a, and a gas such as high-pressure nitrogen gas is sealed in this gas chamber 3. Code 31
Is a valve for sealing gas in the gas chamber 3, and reference numeral 4 is a hydraulic chamber below the free piston 2 in the upper cylinder portion 1a.

A lower cylinder portion 1b is formed below the valve block portion 1A existing below the hydraulic chamber 4 of the main body 1, and a hydraulic piston 6 is slidably and airtightly mounted on the lower cylinder portion 1b. A second hydraulic chamber 5 is formed above 6. The hydraulic chambers 4 and 5 are filled with oil. Reference numerals 6a and 6b denote packings for maintaining oil tightness, and 7 denotes a connecting rod. The connecting rod 7 is a spherical body of a spherical bearing 71 and is fitted in a spherical bearing formed in the hydraulic piston 6. Reference numerals 101 and 72 denote bearings, which are provided on the main body 1 and the connecting rod 7, respectively. Usually, a vehicle body (not shown) is coupled to the bearing 101 via a pin (not shown), and the bearing 72 is directly or indirectly attached to a wheel shaft or a wheel shaft in the case of a crawler vehicle via a lever.

The hydraulic chambers 4 and 5 are connected by a communication passage 8, and an orifice 81 is provided above the communication passage 8. Further, the hydraulic chambers 4 and 5 are connected by a passage 20 provided with a check valve 21 on the way. In operation, when a wheel is pushed up due to unevenness of the road surface, the movement of the wheel pushes up the hydraulic piston 6 via the connecting rod 7. Therefore, the oil in the second hydraulic chamber 5 flows into the hydraulic chamber 4 from the communication passage 8 through the orifice 81, and further moves the free piston 2 upward to compress the gas in the gas chamber 3. At this time, the pressure of the gas rises, so that the gas eventually functions as a spring.
It should be noted that when the wheel is pushed up significantly, the check valve 21 is also opened, and the oil reaches the upper side through the passage 20 as well. As a result of this thrusting up, although there is a buffering effect as a spring, the pressure of the gas in the gas chamber 3 rises, so the vehicle body still sways. Even if the road surface is flat thereafter, the swaying remains, but since the orifice 81 is provided, a damping action is exerted, and this swaying is soon to be attenuated.

[0005]

In the conventional suspension system,
As described above, it has a function of alleviating the impact from the road surface, but the presence of the orifice provided for swaying the vehicle body prevents the movement of oil from the second hydraulic chamber 5 to the hydraulic chamber 4 at the time of thrusting up. The desired effect cannot be obtained. However, if the orifice is enlarged, the desired damping effect cannot be expected. Further, the check valve 21 is opened at the time of a violent push-up to reduce the impact, but the check valve 21 is closed when the wheel is fitted in the recess, that is, when the hydraulic chamber 5 is expanded, and therefore the presence of the orifice. In addition, the oil in the hydraulic chamber 4 cannot quickly return to the second hydraulic chamber 5, the extension of the suspension device is hindered, the road surface may jump, and the riding comfort is eventually hindered. There is. The present invention is intended to solve such a problem, and in the suspension device having the above-described configuration, the orifice for giving damping is practically a variable area type, and further, the oil supply in the suspension device is performed from the outside. It is an object of the present invention to provide a vehicle suspension system that enables the removal and removal.

[0006]

In order to achieve the above-mentioned object, a vehicle suspension system according to a first aspect of the present invention is a vehicle suspension system in which the upper end portion is attached to the vehicle and is sealed inside. Of the upper cylinder part and the lower cylinder part of the lower opening type, and the upper part for dividing the inside of the upper cylinder part into an upper gas chamber filled with gas and a lower hydraulic chamber. A free piston slidably and airtightly mounted on the cylinder part, and slidable on the lower cylinder part so as to form a second hydraulic chamber communicating with the hydraulic chamber via a communication passage inside the lower cylinder part. An airtightly mounted hydraulic piston, a connecting rod having an upper end pivotally attached to the hydraulic piston and a lower end extending below the main body to be attached to a wheel side member of the vehicle, and the communication passage. An external hydraulic source is connected to the second hydraulic chamber and has an attached orifice, and between the hydraulic source and the second hydraulic chamber to maintain the hydraulic pressure of the second hydraulic chamber at a predetermined value. A feature of the present invention is that a servo valve is provided for controlling the flow of pressure oil.

The vehicle suspension system according to claim 2 is
In a suspension system of a vehicle, a main body having an upper end attached to the vehicle and a sealed upper cylinder section and a lower opening lower cylinder section formed therein, and a gas filled in the upper cylinder section. A free piston slidably and airtightly mounted on the upper cylinder part so as to be divided into an upper gas chamber and a lower hydraulic chamber, and a communication passage to the hydraulic chamber inside the lower cylinder part. And a hydraulic piston slidably and airtightly mounted on the lower cylinder portion to form a second hydraulic chamber communicating with each other, and an upper end portion pivotally attached to the hydraulic piston and a lower end portion extending below the main body. A second communication passage is provided, which has a connecting rod that is taken out and attached to the wheel-side member of the vehicle, and an orifice attached to the communication passage, and that connects the hydraulic chamber and the second hydraulic chamber. Both are provided with a poppet valve in the second communication passage, and a second servo for controlling the opening degree of the poppet valve corresponding to the moving speed of the wheel side member so as to favorably follow the road surface of the wheel side member. It is characterized in that a valve is provided.

[0008]

In the vehicle suspension system of the present invention described above, the opening of the poppet valve is increased and the area of the orifice is increased when the vehicle is pushed up significantly from the road surface or when a wheel is about to enter a large recess. The action of the wheel is performed, which makes it possible to make the wheel follow the road surface well and reduce the vibration of the vehicle body. Furthermore, when the thrust from the road surface is severe, the oil in the suspension system is drained, and when the wheels are about to enter a large recess, the oil is supplied.
In addition, the impact can be greatly reduced and the riding comfort can be improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle suspension system according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view of essential parts, FIG. 2 is a hydraulic circuit diagram of a servo valve, and FIG. 3 is a second servo valve. FIG. 4 is a schematic diagram of the hydraulic system of FIG. 4, and FIG. 4 is a hydraulic circuit diagram of the second servo valve. 1 to 4, the same reference numerals as those in FIG. 5 indicate almost the same members. The main body 1 in the vehicle suspension system of this embodiment also has a closed upper cylinder portion 1a and a lower end opening lower cylinder portion 1b, and the upper cylinder portion 1a has the same structure as the main body 1 in the conventional example of FIG. A free piston 2 is slidably and airtightly mounted, and a hydraulic piston 6 having a connecting rod 7 that extends below the main body 1 and is attached to a wheel side member is slidably and airtightly mounted on the lower cylinder portion 1b. ing.

Further, the inside of the upper cylinder portion 1a is divided by a free piston 2 into an upper gas chamber 3 and a lower hydraulic chamber 4, and the lower cylinder portion 1a communicates with the hydraulic chamber 4 via a communication passage 8. A second hydraulic chamber 5 is formed by a hydraulic piston 6. An orifice 81 is attached to the communication passage 8. Furthermore, a servo valve 10 is attached to one side surface of the valve block 1A, and the hydraulic pressure of the communication passage 8 is introduced into the servo valve 10 via the passage 9. Further, a passage 12 connected to the hydraulic chamber 5 and a passage 13 connected to the hydraulic chamber 4 are formed in the valve block 1A, and a poppet valve 11 that opens and closes between the passages is slidably attached to the valve block 1A. .

Reference numeral 14 indicates a back pressure chamber of the poppet valve 11, and a return spring 11 for the poppet valve 11 is provided in the back pressure chamber 14. A slit 112 parallel to the valve axis is formed in the poppet valve 11, and this slit forms a passage in the poppet valve 11.
The passage 12 and the back pressure chamber 14 are connected via 11a. Since the slit 112 is formed across the fitting edge of the poppet valve 11 to the main body 1, when the poppet valve 11 is lifted (moved to the left in FIG. 1), the passage 12 and the back pressure chamber 14 are connected. The area will increase. Reference numeral 15 denotes a second servo valve attached to the other side surface of the valve block 1A, and the second servo valve 15 and the back pressure chamber 14 are connected by a passage 16. Reference numeral 17 denotes a pressure sensor, which measures the pressure in the second hydraulic chamber 5 via the passage 8.

Next, in FIG. 2, reference numeral 102 is a hydraulic pressure source,
Reference numeral 19 indicates a drain tank, and reference numeral 17A indicates a controller, and pressure control is executed by this hydraulic circuit. That is, the hydraulic pressure of the second hydraulic chamber 5 detected by the pressure sensor 17 is compared with the set value in the controller 17A, and the servo valve 10 is driven according to the difference. Actually, when the detected pressure is lower than the set value, the servo valve 10 is opened downward.
As a result, the hydraulic pressure of the hydraulic power source 102 is guided into the suspension system via the passage 9. Conversely, when the detected pressure is higher than the set value, the servo valve 10 is opened upward. As a result, oil is returned from the suspension device to the drain tank 19.

Next, referring to FIGS. 3 and 4, the second servo valve 15 will be described.
In FIG. 3, reference numeral 18 indicates a speed sensor and reference numeral 18A indicates a controller. The speed sensor 18 detects the operating speed of the suspension device, that is, the moving speed of the connecting rod 7. The value detected by the speed sensor 18 is compared with the set value by the controller 18A, and the second servo valve is detected according to the difference. 15 is driven. Actually, when the absolute value of the difference is large, the second servo valve 18 moves downward and the back pressure chamber 14 is connected to the drain tank 19.

Next, the operation will be described. First, for example, when a wheel is pushed up due to the unevenness of the road surface, the movement of the wheel pushes up the hydraulic piston 6 via the connecting rod 7 as in the conventional case. Therefore, the oil in the second hydraulic chamber 5 flows into the hydraulic chamber 4 from the communication passage 8 through the orifice 81, further moves the free piston 2 upward, and compresses the gas in the gas chamber 3. At this time, the pressure of the gas rises, but the pressure of the second hydraulic chamber 5 also rises. This becomes the output value of the pressure sensor 17 and is compared with the set value in the controller 17A, and the servo valve 10 moves upward depending on the difference. As a result, oil is returned from the suspension device to the drain tank 19. Therefore, the push-up of the vehicle body is reduced. When the wheel plunges into the recess, the hydraulic pressure drops and the servo valve 10 moves downward. As a result, the hydraulic pressure is guided from the hydraulic pressure source 102 to the second hydraulic chamber 5, and the wheels follow the road surface. As a result, the vibration of the vehicle body is reduced. Although the sway remains after the unevenness has passed, since the orifice 81 is present, the sway is attenuated and the sway is soon attenuated.

Next, when the wheel encounters a convex portion or a concave portion and the speed sensor 18 detects a large speed, the second servo valve 15 opens downward according to the size, and the back pressure chamber 14 opens the drain tank. Tied to 19. As a result, the pressure in the back pressure chamber 14 decreases, and the poppet valve 11 opens. When the poppet valve 11 opens, the communication area connecting the passage 12 communicated with the slit 112 and the back pressure chamber 14 increases. As a result, the flow of oil from the passage 12 to the back pressure chamber 14 increases, and the pressure in the back pressure chamber 14 becomes a certain value due to the throttling action of the second servo valve 15. Therefore, the poppet valve 11 stops at a position where the hydraulic pressure from the right side, the hydraulic pressure of the back pressure chamber 14 and the force of the return spring 111 are balanced. This second
When the opening degree of the servo valve 15 is small, the pressure of the back pressure chamber 14 is high, and when the opening degree of the second servo valve 15 is large, the pressure of the back pressure chamber 14 is low.

By the way, when the speed sensor 18 detects a large speed, the second servo valve 15 opens greatly, and the poppet valve 11 also opens greatly. When the poppet valve 11 opens wide,
The resistance of the flow from the second hydraulic chamber 5 to the hydraulic chamber 4 is reduced, and the thrust of the vehicle body is reduced. And poppet valve 11
Since the orifice and the orifice 81 are arranged in parallel, the same operation and effect as in the case where the orifice area is actually variable can be obtained. Further, since the slit 112 formed in the poppet valve 11 acts to increase the communication area connecting the passage 12 and the back pressure chamber 14 almost in proportion to the increase in the opening degree of the poppet valve 11, The flow can be delicately controlled, which can further improve the riding comfort.

[0017]

As described in detail above, according to the vehicle suspension system of the present invention, the following effects and advantages can be obtained. (1) The servo valve has the function of draining the oil in the suspension system when the vehicle is pushing up strongly from the road surface, and supplying the oil when the wheels are trying to enter a large recess, so the impact is greatly reduced. You can (2) When the thrust from the road surface is severe due to the second servo valve, or when the wheel is about to enter a large recess, the area of the orifice is substantially increased to make the wheel follow the road surface better and the body shakes. Can be reduced, and as a result, ride comfort can be improved.

[Brief description of drawings]

FIG. 1 is a side sectional view of a main part of a vehicle suspension device as an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram of the servo valve.

FIG. 3 is a schematic diagram of a hydraulic system of the second servo valve.

FIG. 4 is a hydraulic circuit diagram of the second servo valve.

FIG. 5 is a side sectional view of a main part of a conventional vehicle suspension system.

[Explanation of symbols]

 1 main body 1a upper cylinder part 1b lower cylinder part 2 free piston 3 gas chamber 4 hydraulic chamber 5 second hydraulic chamber 6 hydraulic piston 7 connecting rod 8 connecting passage 9 oil passage 10 servo valve 11 poppet valve 12,13 passage 14 back pressure Chamber 15 Second servo valve 31 Valve 111 Return spring 112 Slit

Claims (2)

[Claims] 1. In a suspension system for a vehicle, a main body having an upper end portion attached to the vehicle and a sealed upper cylinder portion and a lower end opening lower cylinder portion formed therein, and an upper cylinder portion. A free piston slidably and airtightly mounted on the upper cylinder part so as to divide the interior into an upper gas chamber in which gas is enclosed and a lower hydraulic chamber, and the hydraulic chamber inside the lower cylinder part. A hydraulic piston slidably and airtightly mounted on the lower cylinder portion to form a second hydraulic chamber communicating with the lower hydraulic cylinder, and an upper end of the hydraulic piston is pivotally attached to the hydraulic piston and a lower end of the hydraulic piston is An external hydraulic source is connected to the second hydraulic chamber, the connecting rod extending downward from the main body and attached to the vehicle wheel side member, and the orifice attached to the communication passage. Further, in order to keep the hydraulic pressure in the second hydraulic chamber at a predetermined value, a servo valve for controlling the flow of hydraulic oil between the hydraulic source and the second hydraulic chamber in response to the change in hydraulic pressure in the second hydraulic chamber. A vehicle suspension system comprising: 2. In a suspension system for a vehicle, a main body having an upper end portion attached to the vehicle and having a sealed upper cylinder portion and a lower end opening lower cylinder portion formed therein, and the upper cylinder portion. A free piston slidably and airtightly mounted on the upper cylinder part so as to divide the interior into an upper gas chamber in which gas is enclosed and a lower hydraulic chamber, and the hydraulic chamber inside the lower cylinder part. A hydraulic piston slidably and airtightly mounted on the lower cylinder portion to form a second hydraulic chamber communicating with the lower hydraulic cylinder, and an upper end of the hydraulic piston is pivotally attached to the hydraulic piston and a lower end of the hydraulic piston is A second communication passage that extends below the main body and has a connecting rod that is attached to the wheel-side member of the vehicle, and an orifice that is attached to the communication passage, and that communicates the hydraulic chamber with the second hydraulic chamber. Is provided and a poppet valve is provided in the second communication passage, and the opening degree of the poppet valve is controlled in accordance with the moving speed of the wheel side member in order to favorably follow the road surface of the wheel side member. A vehicle suspension system characterized in that a second servo valve is provided.