JPH07149134A - Suspension for four-wheel vehicle - Google Patents

Abstract

PURPOSE:To easily set the damping force, suppress the impact small at the time of single wheel run-over, and simplify the piping structure. CONSTITUTION:A pressure regulator 3 communicates with the right and left hydraulic cylinders 2 each having a throttled piston 6 via hydraulic paths 16, 17. A variable-flow control valve device 4 constituted of a throttle member 21 and a spool valve 22 is provided between both hydraulic paths 16, 17. The input section of a spool 33 is communicated with both hydraulic paths 16, 17 via the throttle member 21. The damping force at the time of rolling becomes the value added with the damping force of a throttle 9 and the throttle member 21, the operating condition of each throttle can be restricted, and it can be easily set. One throttle 9 is operated at the time of single wheel run-over, the impact can be suppressed small. Only one hydraulic path is required for each hydraulic cylinder, and the structure is simplified.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is used in automobiles and the like.
The present invention relates to a suspension system for a wheeled vehicle.

[0002]

2. Description of the Related Art Conventionally, as a suspension device for suppressing rolling of a vehicle body in a four-wheeled vehicle, for example, JP-A-63-22
There is one disclosed in Japanese Patent No. 2914.

The suspension device disclosed in this publication has hydraulic cylinders interposed between the left and right wheel sides and the vehicle body side,
The oil chamber of the left hydraulic cylinder and the oil chamber of the right hydraulic cylinder are made to communicate with each other via a communication pipe. The piston of each hydraulic cylinder was provided with a throttle so that the oil chambers on both sides of the piston were connected to each other.

The communication pipe connects the upper oil chamber of the left hydraulic cylinder (the oil chamber closer to the vehicle body than the piston) and the lower oil chamber of the right hydraulic cylinder (the oil chamber closer to the wheel than the piston) to the left hydraulic chamber. Two cylinders are provided to connect the lower oil chamber of the cylinder and the upper oil chamber of the right hydraulic cylinder, and a throttle is provided in each of the communication pipes.

That is, when the vehicle body is tilted and one of the left and right hydraulic cylinders is contracted, oil is pumped from the lower oil chamber of the contracted hydraulic cylinder to the upper oil chamber of the other hydraulic cylinder, and at the same time, the other hydraulic cylinder is contracted. Oil is pumped from the lower oil chamber of the hydraulic cylinder to the upper oil chamber of the hydraulic cylinder that contracts, which eventually causes both hydraulic cylinders to contract and the leaning of the vehicle body is suppressed. Then, the rolling action is attenuated by the oil passing through the throttle of the communication pipe.

[0006]

However, in the suspension configured as described above, in setting the damping performance, the damping performance at the throttle of the piston of each hydraulic cylinder and the damping performance at the throttle provided in each communicating pipe are set. It must be done in consideration of damping performance. Therefore, the setting was extremely complicated.

Further, even when only one of the left and right wheels gets over the projection on the road surface, the damping is performed with a large damping force as in the rolling damping operation described above, so that when the vehicle speed is high, There is also a problem that when a one-wheeled vehicle is overridden, an extremely large impact is applied to the vehicle body.

Further, there is a problem that the communication pipes are connected to the upper and lower oil chambers of each hydraulic cylinder, and the piping becomes complicated.

The present invention has been made to solve the above problems, and it is possible to easily set the damping force, to suppress the impact when one wheel is passed over, and to simplify the piping structure. An object of the present invention is to obtain a suspension system for a four-wheeled vehicle, which can be realized.

[0010]

In a suspension system for a four-wheel vehicle according to the present invention, the inside of a cylinder is divided into an upper oil chamber and a lower oil chamber by a piston with a throttle and one of a wheel side and a vehicle body side. A cylinder body connected to the other side and a piston connected to the other side, and a hydraulic cylinder interposed between the wheel side and the vehicle body side; and an oil chamber communicating with one of upper and lower oil chambers of the hydraulic cylinder, The oil chamber and the high pressure gas chamber are provided with a pressure adjusting cylinder defined by a free piston, and the hydraulic cylinders are mounted on two of the left and right of the four wheels to adjust the pressure for each hydraulic path of each hydraulic cylinder. A pressure cylinder is provided, the free pistons of the pressure regulating cylinders are integrally configured to interlock with each other, and the hydraulic paths are communicated with each other through a variable flow rate control valve device. Is formed by a throttle member and a spool valve that are interposed in parallel between both hydraulic paths, and the spool of this spool valve is biased to the open side by a spring and opens and closes the communication path between the hydraulic paths. With this structure, the input portion of this spool is connected to the hydraulic cylinder side via the throttle portion.

[0011]

When the two hydraulic cylinders expand and contract in the same direction, less oil passes through the throttle member of the variable flow control valve device, and the operation of the hydraulic cylinder is attenuated by the oil passing through the throttle of the piston of the hydraulic cylinder. . If the left and right hydraulic cylinders expand and contract in different directions due to rolling, etc., a pressure difference will occur between the hydraulic paths communicating with each hydraulic cylinder, making it difficult for the pressure regulating cylinder to communicate with the pressurizing side and the depressurizing side and to move the free piston. From the relationship
Oil flows from the high pressure side hydraulic path to the low pressure side hydraulic path via the variable flow control valve device. At this time, when the change in the hydraulic pressure due to rolling or the like is relatively gradual, hydraulic pressure is applied to the input portion of the spool from the high-pressure side hydraulic passage through the throttle portion of the variable flow rate control valve device, and the spool valve is closed. As a result, it is only the throttle member of the variable flow control valve device that connects the high-pressure side hydraulic path and the low-pressure side hydraulic path to each other, and the oil flows through this throttle member. That is, when there is a difference in the operating directions of the left and right hydraulic cylinders, damping force is obtained by the throttles in both hydraulic cylinders and the throttle member of the variable flow control valve device if the change in hydraulic pressure is gentle.

When either one of the left and right hydraulic cylinders rapidly contracts when only one wheel gets over a road surface protrusion, the hydraulic pressure in the hydraulic path communicating with this hydraulic cylinder is Depending on the difference between the compression side and the expansion side, the oil chamber in the communicating hydraulic cylinder becomes a positive pressure or a negative pressure with respect to the hydraulic path of the other hydraulic cylinder (which does not overhang the protrusion). Then, this pressure change becomes steeper than that at the time of rolling. In this way, when one hydraulic path changes pressure with respect to the other hydraulic path, oil flows from the high-pressure hydraulic path to the low-pressure hydraulic path via the variable flow control valve device in the same way as during rolling. However, since the change in hydraulic pressure is steep, the throttle portion interferes with the pressure, making it difficult for the pressure to propagate to the input portion of the spool, and the spool valve is held in the open state.
Oil flows through the communication passage of the spool valve. When the hydraulic path is connected to the oil chamber that is on the compression side when the hydraulic cylinder contracts, the hydraulic path that is communicated to the hydraulic cylinder on the one side that contracts when moving over is on the high pressure side, and vice versa. When the hydraulic path is communicated with the oil chamber on the extension side when passing over the wheels, the hydraulic path communicated with the other hydraulic cylinder (the one on which the projection is not overridden) is on the high pressure side.

Therefore, when passing over one wheel, less oil passes through the throttle member of the variable flow control valve device, so that the damping force can be obtained only by the throttles in the left and right hydraulic cylinders.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. FIG. 1 is a schematic configuration diagram of a suspension system for a four-wheel vehicle according to the present invention, FIG. 2 is a front view of a suspension system for a four-wheel vehicle according to the present invention, and FIG. 3 is a cross section showing a variable flow control valve device according to the present invention. FIG. 4, FIG. 4 is a cross-sectional view of the pressure regulating cylinder according to the present invention, and FIG. 5 is a graph showing the relationship between the piston speed and the damping force when the hydraulic cylinder contracts.

In these figures, 1 is 4 according to the present invention.
A suspension system for a wheeled vehicle is shown in which the suspension system 1 is mounted on the front wheel side. The suspension device 1 for a four-wheeled vehicle according to the present invention
The same configuration as in the present embodiment is also applied when the is mounted on the rear wheel side. In addition, in FIG. 1 and FIG. 2, other suspension device constituent members such as a link mechanism for supporting the front wheel so as to be vertically movable and a cushion spring are omitted.

As shown in FIG. 1, a suspension system 1 for a four-wheeled vehicle according to the present invention comprises left and right hydraulic cylinders 2, 2 and a pressure regulator 3, which is connected to the left and right hydraulic cylinders 2, 2. It is composed of the flow control valve device 4 and the like.

The left and right hydraulic cylinders 2, 2 have the same structure, and the inside of the cylinder body 5 filled with oil is divided by a piston 6 into an upper oil chamber 7 and a lower oil chamber 8. Further, the piston 6 has an upper oil chamber 7
And a lower oil chamber 8 are provided with a communication passage 6a, and a throttle 9 is provided in the communication passage 6a.

The hydraulic cylinder 2 connects the cylinder body 5 to the vehicle body (not shown) of the automobile, and the lower end portion of the piston rod 10 moves up and down with respect to the vehicle body together with front wheels such as front wheel suspension links. It is pivotally supported and is interposed between the vehicle body side and the front wheel side. It should be noted that the mounting direction of the hydraulic cylinder 2 can be reversed upside down from the case described above. In the present embodiment, an example is shown in which the hydraulic cylinder 2 located on the left side in FIG. 1 is mounted on the left front wheel side, and the hydraulic cylinder 2 located on the right side in FIG. 1 is mounted on the right front wheel side.

In the pressure regulating device 3, pressure regulating cylinders 11a are formed side by side in the cylinder body 11 with their axial directions parallel to each other, and a free piston 12 is movably fitted in each pressure regulating cylinder 11a. And free piston 1
One of the cylinder internal spaces partitioned by 2 is filled with high pressure gas to form a high pressure gas chamber 13, and the other cylinder internal space is filled with oil to form an oil chamber 14. Two oil chambers 14 are provided because the two pressure adjusting cylinders 11a are provided.

The two free pistons 12 and 12 are connected to each other via a connecting member 15, and are configured to move in the same direction at the same time and interlock with each other.

As described above, two oil chambers 1 are provided.
One of 4, 4 communicates with the upper oil chamber 7 of the left hydraulic cylinder 2 through the left hydraulic passage 16, and the other communicates with the upper oil chamber 7 of the right hydraulic cylinder 2 through the right hydraulic passage 17. . That is, the pressure adjusting cylinder 11a is provided for each hydraulic path of the hydraulic cylinder 2. Further, the hydraulic path 1 is provided in the upper oil chamber 7 on the compression side when the left and right hydraulic cylinders 2 contract.
The oil chamber 14 of each pressure regulating cylinder 11a
Are communicated with each other.

A variable flow control valve device 4 to be described later is interposed between the left and right hydraulic paths 16 and 17 which connect the respective oil chambers 14 to the left and right hydraulic cylinders 2 and 2.

When the suspension device 1 having the above-described structure is mounted on the vehicle body of an automobile, each member is formed as shown in FIGS. 2 and 3. 2 and 3, the same or similar members as those described in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted.

The hydraulic cylinder 2 shown in FIG. 2 is formed by inserting the lower portion of the cylinder body 5 into the outer cylinder 5a. The piston rod 10 is fixed to the outer cylinder 5a, and the outer cylinder 5a is configured to be pivotally supported at a portion that moves up and down together with the front wheel. The throttle 9 of the piston 6 of the hydraulic cylinder 2 has a conventionally known structure in which the opening of the communication passage 6a is closed by a leaf spring type check valve. In FIG. 2, the positions of the piston and the upper end of the outer cylinder when the hydraulic cylinder 2 is contracted most are shown by a chain double-dashed line A. FIG. 2 shows the hydraulic cylinder 2 in the most extended state.

The pressure adjusting device 3 is constructed by coaxially forming two pressure adjusting cylinders in one cylinder body 11. As shown in the detailed cross section of FIG. 4, the pressure adjusting device 3 has a bottom member 11b that closes the opening of the cylinder body 11 and has a cylindrical shape with a bottom, and a free piston is provided inside the bottom member 11b. 12 is inserted. Further, the bottom member 11b has a thin portion 11c formed at its tip end portion so as to have a smaller outer diameter. With the bottom member 11b attached to the cylinder body 11, the thin wall portion 11c and the inner peripheral surface of the cylinder body 11 are attached. And an oil chamber 14 is formed between the above and. The oil chamber 14 is provided between the inner bottom surface of the bottom member 11b and the free piston 12 in addition to being provided on the cylinder side portion described above.

The free piston 12 is formed in a bottomed cylindrical shape consisting of a small diameter portion fitted into the inner peripheral portion of the bottom member 11b and a large diameter portion fitted into the inner peripheral portion of the cylinder body 11. The outer diameter of the small diameter portion and the outer diameter of the large diameter portion are
Each oil chamber 1 when this free piston 12 moves
The volume increase and the volume decrease at 4 and 14 are set to be equal. The position of the free piston 12 when the volume of the oil chamber 14 becomes the maximum is shown by the chain double-dashed line B in FIG.
Indicated by.

A nipple 18 for communicating the oil chamber 14 with the left hydraulic passage 16 is attached to a portion of the cylinder body 11 corresponding to the oil chamber 14, and the bottom member 22b is provided with the nipple 18 at the bottom thereof. A nipple 18 for connecting the oil chamber 14 to the right hydraulic path 17 of the left and right hydraulic paths 16 and 17 is attached. In FIG. 4, reference numeral 20a is an O-ring and 20b is a piston ring.

In the pressure regulator 3 thus constructed, the hydraulic pressure in the left hydraulic passage 16 acts on the large diameter portion of the free piston 12 via the oil chamber 14 on the cylinder side, and the hydraulic pressure in the right hydraulic passage 17 is changed. Oil chamber 14 on the bottom side of the bottom member 11b
It acts on the small diameter part of the free piston 12 via the. That is, the bottom member 11b into which the small diameter portion of the free piston 12 is inserted and the cylinder body 11 into which the large diameter portion of the free piston 12 is inserted form a pressure adjusting cylinder for each hydraulic path.

Since the two oil chambers 14, 14 have a relationship in which the free piston 12 constitutes a part of the wall surface, the volume change amount in each oil chamber 14 is always equal.

The variable flow rate control valve device 4 has a structure in which the left and right hydraulic passages 16 and 17 communicate with each other on the upstream side of the pressure regulating device 3, and the hydraulic passages 16 and 17 are interposed in parallel with each other. Throttle member 21 and spool valve 22
It consists of and. The throttle member 22 includes a cylindrical case 23 having a bottom and a valve support member 2 that closes the opening of the case 23.
It is formed by screwing 4 together. The valve support member 2
4, a throttle body 25 that faces the inside of the case 23 and defines the inside of the case 23 into chambers A and B is attached, and two nipples 26 that communicate with the right hydraulic passage 17 are attached. In addition, in the A chamber, the diaphragm main body 25
Is the space on the bottom side, and chamber B is the space on the valve support member 24 side of the throttle body 25.

Further, the valve support member 24 is formed with communication passages 24a and 24b for communicating the oil passage in the nipple 26 with the chamber B in the case 23. With this configuration, both nipples 26
The internal oil passages are communicated with each other through the communication passage 24a, the B chamber, and the communication passage 24b. That is, the inside of the nipple 26, the communication passages 24 a and 24 b, and the B chamber constitute a part of the right hydraulic passage 17.

The throttle body 25 is formed with small holes 25a and 25b penetrating the diaphragm body 25, and a check valve 27 made of a leaf spring for closing an opening of the small hole 25a on the B chamber side, and a small hole. A check valve 28 made of a leaf spring for closing the opening on the side of the chamber A of 25b is provided. In the present embodiment, these check valves 27 and 28 are formed so that their spring characteristics are the same. This is to make the throttle amount equal when the oil flows from the A chamber to the B chamber and when the oil flows from the B chamber to the A chamber.
That is, as will be described later, when the vehicle body rolls or the like, the damping characteristics are the same regardless of whether the vehicle body is tilted in either the left or right direction.

A nipple 29 is provided on the bottom of the case 23.
Is attached to connect the chamber A in the case 23 to a communication pipe (not shown) connected to the nipple 29. The left hydraulic path 16 communicates with the nipple 29.

In the diaphragm member 21 thus constructed,
When the hydraulic pressure in the chamber A of the case 23 becomes higher than that in the chamber B, the hydraulic pressure is applied to the check valve 27 through the small hole 25a to open the check valve 27, and the oil passes from the chamber A through the small hole 25a to the chamber B. Will flow into. On the contrary, when the hydraulic pressure in the B chamber becomes higher than that in the A chamber, the check valve 28 is opened by the hydraulic pressure and the oil flows from the B chamber to the A chamber. That is, the throttle member 21 has a two-handed structure in which resistance is generated when the check valve 27 or the check valve 28 is opened and the oil flows between the A chamber and the B chamber.

Reference numeral 30 is an adjusting screw for finely adjusting the amount of throttle in the throttle body 25, and 31 is an O-ring interposed between the case 23 and the valve support member 24.

The spool valve 22 has a spool 32 built in a case 32 formed by connecting and fixing three divided case members, and a spool urging mechanism 34, needles 35 and 36, and a hydraulic path communicating nipple 37. ~ 4
It is formed by attaching 0. Spool 33 is case 3
2 has a structure in which it is movably fitted in a circular hole 32a at substantially the center along the axial direction, and ports 32b, 32c extending from the circular hole 32a to one side and the other side of the case 32 are opened and closed. . That is, as shown in FIG. 3, when the small diameter portion 33a of the spool 33 faces both the ports 32b and 32c, the spool valve 22 is opened, and
The spool valve 22 is closed when the spool 33 descends in the drawing as indicated by the chain double-dashed line and its large diameter portion 33b faces the port 32b. The port 32b communicates with the left hydraulic passage 16 through the nipple 37, and the port 32c communicates with the right hydraulic passage 17 through the nipple 38.

The spool urging mechanism 34 is arranged on the front side in the closing direction of the spool 33. The spool biasing mechanism 34 has a structure in which the compression coil spring 34a is brought into contact with the end surface of the spool 33 to bias the spool 33 in the opening direction. Reference numeral 34b is an adjusting bolt for adjusting the spring force of the compression coil spring 34a. By increasing the screwing amount of the adjusting bolt 34b into the case 32, the spring force is increased, and the spool 3
The force required to close 3 increases.

Further, at the shaft end portion of the spool 33 on the front side in the opening direction, two pins 4 as an input portion of the spool 33 are provided.
1, 42 are projected. Each of these pins 41 and 42 is formed in a rod shape having a circular cross section, and is fitted into the throttle passages 43 and 44 of the case 32. The throttle passage 43 communicates with the upper oil chamber 7 side from the connection portion with the throttle member 21 in the left hydraulic passage 16, and the throttle passage 44 communicates with the upper oil chamber 7 side with the connection portion with the throttle member 21 in the right hydraulic passage 17. Has been done.

The throttle passages 43 and 44 are
The tips of the needles 35 and 36 are facing, and the needle 3
The minimum passage cross-sectional area is increased or decreased by changing the amount of protrusion of 5, 36 into the passage. That is, the throttle passages 43 and 44 and the needles 35 and 36 constitute the throttle portion according to the present invention. Therefore, the input portion (pins 41, 42) of the spool 33 is communicated with the hydraulic cylinder side via the throttle portion. It should be noted that the larger the protrusion amount of the needles 35 and 36 into the passage, the smaller the minimum passage sectional area and the greater the throttling effect at the throttle portion. Therefore, the protrusion amount of the needles 35 and 36 into the passage is changed. By doing so, the degree of diaphragm can be adjusted.

The spool valve 22 constructed in this way is
In the open state shown in FIG. 3, the inner space of the nipple 37, the port 32b, the circular hole 32a, the port 32c and the nipple 3 are opened.
A communication passage that penetrates the spool valve 22 is formed by the internal space of the eight passages, and the left and right hydraulic passages 16 and 17 are communicated via this communication passage. Further, the throttle passage 43 or the throttle passage 4
4 becomes higher than the urging force of the spool urging mechanism 34, the pressure causes the pin 41 or the pin 4 to move.
Along with 2, the spool 33 is pushed downward in FIG. 3 and moved to the closed position as shown by the chain double-dashed line.

When the spool valve 22 is closed as described above, the left and right hydraulic paths 16 and 17 through the communication passages.
Communication between them will be cut off.

Next, the operation of the four-wheeled vehicle suspension system 1 according to the present invention having the above-described structure will be described. For example, when the left and right front wheels pass over a protrusion on the road and the left and right hydraulic cylinders 2 and 2 contract, oil is added to each hydraulic passage 1 by the amount of the piston rod 10 inserted into the cylinder body 5.
It flows to 6,17. Then, the oil flows into the oil chamber 14 of the pressure regulator 3 by a flow rate corresponding to the oil outflow. At this time, assuming that the hydraulic pressures in the hydraulic paths 16 and 17 are substantially equal to each other, the throttle member 2 is not affected by the open / close state of the spool valve 22 of the variable flow control valve device 4.
Since there is no pressure difference between the A chamber and the B chamber in 1 and the oil does not pass through the throttle body 25, substantially the entire amount of oil corresponding to the outflow portion flows into the pressure adjusting device 3.

The free piston 1 of the pressure regulator 3
The cylinder bodies 11 and 2 are arranged so that the high pressure gas is compressed by the hydraulic pressure applied from the nipples 18 and 19 side.
I will move inside.

That is, when pitching or bouncing occurs in the vehicle body and the left and right hydraulic cylinders 2 expand and contract in the same direction, vibrations of the vehicle body are damped mainly by resistance generated when oil passes through the throttle 9 in the hydraulic cylinder 2. To be done.

When the left hydraulic cylinder 2 is contracted and the right hydraulic cylinder 2 is extended by rolling the vehicle body to the right (when rolling occurs), the left and right hydraulic cylinders 2 communicated with each hydraulic cylinder 2 respectively. Since a pressure difference is generated between the hydraulic paths 16 and 17 and the pressure regulating device 3 communicates with the pressurizing side and the depressurizing side to make it difficult for the free piston 12 to move, the oil flows to the high pressure via the variable flow control valve device 4. From the left hydraulic path 16 to the right hydraulic path 17 having a low pressure.

During this rolling, the changes in the hydraulic pressure in the left and right hydraulic passages 16 and 17 are relatively gradual, so the throttle portion (throttle passage 43 and needle 35) of the variable flow rate control valve device 4 starts from the high-pressure left hydraulic passage 16. The oil pressure is applied to the pin 41 of the spool 33 via the
At, the spool valve 22 is closed by moving downward.
Therefore, only the throttle member 21 of the variable flow rate control valve device 4 connects the high-pressure left hydraulic passage 16 and the low-pressure right hydraulic passage 17 with each other, and the oil flows through the throttle member 21.

The oil flowing from the left hydraulic passage 16 into the throttle member 21 flows from the A chamber to the B chamber through the throttle body 25. Then, a majority of the oil outflow amount in the left hydraulic cylinder 2 passes through the throttle member 21 and the right hydraulic path 1
It will start flowing into 7. The oil flowing from the left hydraulic path 16 to the right hydraulic path 17 is distributed by the lube support member 24 of the throttle member 21 to the pressure regulator 3 side and the right hydraulic cylinder 2 side. At this time, the free piston 1 of the pressure regulator 3
2 moves in the cylinder body 11 according to the amount of oil flowing from the nipples 18 and 19.

That is, when the left and right hydraulic cylinders 2, 2 gently expand and contract in different directions due to rolling of the vehicle body, the resistance generated when oil passes through the throttle 9 in the hydraulic cylinder 2 and the throttle member 21. Vibration of the vehicle body is damped by the resistance generated when oil passes through the throttle body 25. It should be noted that this phenomenon similarly occurs regardless of whether the leaning direction of the vehicle body is left or right.

When, for example, the left hydraulic cylinder 2 is rapidly contracted when only one wheel gets over a projection on the road surface, the hydraulic pressure in the left hydraulic path 16 communicated with the left hydraulic cylinder 2 is changed to the right hydraulic path 17. Higher than This pressure increase becomes steep as compared with the case of the rolling. When the pressure in the left hydraulic passage 16 becomes higher than that in the right hydraulic passage 17, the high pressure left hydraulic passage 16 is reduced to the low pressure right hydraulic passage 1 in the same manner as during rolling.
Although oil tends to flow to the valve 7 through the variable flow control valve device 4, the change in hydraulic pressure is steep, so that the pin 41 of the spool 33 is hindered by the throttle portion and the hydraulic pressure is hard to be transmitted, so that the spool 33 moves. Spool valve 2 because it is difficult to move
2 is held open. That is, at this time, the oil flows through the communication passage of the spool valve 22.

The spool 33 is a compression coil spring 34.
Since it is biased to the open side by a, the amount of movement changes according to the pressure propagated through the throttle portion. That is,
For example, when the pressure in the left hydraulic path 16 increases, the higher the speed of pressure increase, the lower the pressure transmitted through the throttle portion, and the spool 33 becomes difficult to move and the spool valve 22 becomes difficult to close. Therefore, the opening of the spool valve 22 changes according to the speed at which the left or right hydraulic cylinder 2 contracts. The throttle amount in the throttle portion can be adjusted by the screwing amount of the needle 35 or 36 as described above.

Therefore, when passing over one wheel, the left and right hydraulic paths 16 are connected via the communication passage of the variable flow control valve device 4.
Since the oil circulates at 17 and less oil passes through the throttle member 21, the damping force is obtained only by the throttles 9 in the left and right hydraulic cylinders 2. Note that the above-mentioned phenomenon when passing over one wheel also occurs when the right side wheel passes over the protrusion.

Piston speed (hydraulic pressure rising speed) when the hydraulic cylinder 2 in the suspension system 1 for a four-wheel vehicle according to the present invention contracts
Fig. 5 shows the relationship between the damping force and the damping force. As shown in the figure, the damping force is relatively large when the piston speed is in the relatively low V ₁ range, and the damping force is relatively small when the piston speed is in the relatively high V ₂ range. Also, V
_In the range between ₁ and V _2, the damping force gradually decreases as the piston speed increases. This is because the spool 33 has moved to a position between the fully open position and the fully closed position.

According to the suspension device 1 thus constructed, when the left and right hydraulic cylinders 2, 2 operate in the same direction, a small amount of oil passes through the throttle member 21 of the variable flow rate control device 4 and the hydraulic cylinder 2 The operation is damped by the resistance created by the oil passing through the throttle 9 of the piston 6. When the two hydraulic cylinders 2, 2 expand and contract relatively slowly in different directions such as during rolling, the spool valve 22 closes and oil flows through the throttle member 21. At that time, the piston 6 of the hydraulic cylinder 2
The operation of the hydraulic cylinder 2 is attenuated by the resistance generated by the passage of oil through the throttle 9 and the throttle member 21 of the variable flow control valve device 4.

Further, when one of the left and right hydraulic cylinders is contracted, such as when one wheel is overridden, the left and right hydraulic paths 16, 16 are connected through the communication passage of the spool valve 22 while the spool valve 22 is kept open. Oil circulates between 17. Therefore, the operation of the hydraulic cylinder 2 when riding over one wheel is attenuated by the resistance generated by the oil passing through the throttle 9 of the piston 6.

Therefore, during rolling, a larger damping force is applied than when overriding one wheel, and when overriding one wheel, a small damping force obtained only by the throttle 9 in the hydraulic cylinder 2 contracted at that time is exerted. That is,
A large damping force can be obtained during rolling by combining a plurality of diaphragms. If the damping force may be small, only a part of the plurality of diaphragms will be used for damping. For this reason, it is possible to limit the conditions of use for the individual diaphragms, and it is possible to perform optimum settings for damping rolling, pitching or bouncing.

In this embodiment, the hydraulic passage 1 is provided in the upper oil chamber 7 which is on the compression side when the hydraulic cylinder 2 contracts.
An example in which 6 and 17 are connected is shown, but in FIG.
The hydraulic paths 16 and 17 may be connected to the lower oil chamber 8 on the extension side when the hydraulic cylinder 2 contracts, as shown in FIG. Even with this structure, the same effect as that of the above embodiment can be obtained. With such a configuration, the pressure of the hydraulic path communicating with the hydraulic cylinder 2 that contracts during rolling decreases with respect to the other hydraulic path, so the hydraulic pressure for pushing the spool 33 to the closing side is the other hydraulic path. (Hydraulic path communicating with the hydraulic cylinder that extends during rolling).

[0057]

As described above, in the suspension system for a four-wheel vehicle according to the present invention, the inside of the cylinder is divided into the upper oil chamber and the lower oil chamber by the piston with the throttle, and among the wheel side and the vehicle body side. It has a hydraulic cylinder that is connected between the wheel side and the vehicle body side, with a cylinder body connected to one side and a piston connected to the other side, and an oil chamber that communicates with one of the upper and lower oil chambers of this hydraulic cylinder. The oil chamber and the high-pressure gas chamber are provided with a pressure-regulating cylinder defined by a free piston, and the hydraulic cylinders are mounted on two of the left and right of four wheels, and the hydraulic cylinders are provided for each hydraulic path. A pressure regulating cylinder is provided, the free pistons of the respective pressure regulating cylinders are integrally configured to interlock with each other, and the hydraulic paths are communicated with each other through a variable flow rate control valve device. The valve device is composed of a throttle member and a spool valve which are interposed in parallel between the two hydraulic paths, and the spool of the spool valve is biased to the open side by a spring and a communication path between the hydraulic paths is formed. With the structure that opens and closes and the input part of this spool is connected to the hydraulic cylinder side through the throttle passage, when the left and right hydraulic cylinders expand and contract in the same direction, damping force is obtained only by the throttles in the left and right hydraulic cylinders. When the operating directions of the left and right hydraulic cylinders are different, damping force is obtained by the throttles in each hydraulic cylinder and the throttle member of the variable flow control valve device.
That is, when rolling, a larger damping force is applied than when passing over one wheel.

Therefore, when the operating directions of the two hydraulic cylinders are different, the damping force obtained by adding the damping force of the throttle member of the variable flow rate control device to the damping force of the throttle in the hydraulic cylinder acts, so that the damping force is increased or decreased. This can be done by combining a plurality of diaphragms. For this reason, it becomes possible to limit the use conditions of the respective diaphragms provided in the apparatus, which facilitates setting.

Further, when one wheel is passed over, a small damping force obtained only by the throttle in the hydraulic cylinder that is compressed at that time acts, so that the impact applied to the vehicle body at this time can be suppressed.

Furthermore, since only one hydraulic path is required to connect the hydraulic cylinder and the pressure adjusting cylinder to each hydraulic cylinder,
It also has the effect of simplifying piping.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a suspension system for a four-wheel vehicle according to the present invention.

FIG. 2 is a front view of a suspension system for a four-wheeled vehicle according to the present invention.

FIG. 3 is a sectional view showing a variable flow control valve device according to the present invention.

FIG. 4 is a sectional view of a pressure regulating cylinder according to the present invention.

FIG. 5 is a graph showing the relationship between piston speed and damping force when the hydraulic cylinder contracts.

[Explanation of symbols]

 1 Suspension device for four-wheeled vehicle 2 Hydraulic cylinder 3 Pressure regulator 4 Variable flow control valve device 5 Cylinder body 6 Piston 9 Throttle 11a Pressure regulating cylinder 12 Free piston 13 High pressure gas chamber 14 Oil chamber 16 Left hydraulic route 17 Right hydraulic route 21 Throttle member 22 Spool valve 25 Throttle body 33 Spool 34 Spool biasing mechanism 35 Needle 36 Needle 43 Throttle passage 44 Throttle passage

Claims (1)

[Claims] 1. An inside of a cylinder is defined by a piston with a throttle into an upper oil chamber and a lower oil chamber, and a cylinder body is connected to one of a wheel side and a vehicle body side and a piston is connected to the other side of the wheel side to a wheel side. A hydraulic cylinder interposed between the vehicle body side and an oil chamber communicating with one of upper and lower oil chambers of the hydraulic cylinder are provided, and the oil chamber and the high pressure gas chamber are defined by a free piston. A pressure adjusting cylinder is provided, and the hydraulic cylinders are mounted on two of the left and right of four wheels, and the pressure adjusting cylinder is provided for each hydraulic path of the hydraulic cylinder, and the free pistons of the pressure adjusting cylinders are interlocked with each other. To be integrated,
The hydraulic paths are communicated with each other via a variable flow rate control valve device, and the variable flow rate control valve device is constituted by a throttle member and a spool valve that are interposed in parallel between the hydraulic pressure paths, The spool of the spool valve has a structure in which it is biased to an open side by a spring and opens and closes a communication passage between hydraulic paths, and an input portion of the spool is connected to a hydraulic cylinder side through a throttle portion. Suspension device for four-wheeled vehicles.