JP2001165228A - Anti-roll type hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anti-roll type hydraulic shock absorber providing a sufficient changeover force in the case of using a pressure of a pneumatic source for the operation of a changeover valve. SOLUTION: The changeover valve DV is arranged in an oil channel L in a piston rod 1 so as to move vertically and provided with a poppet type valve element cutting out the oil channel in its lowering and communicating the oil channel in its raising. The poppet type valve element is energized in the raising direction by a return spring 33 at all times. A solenoid changeover valve CV is interposed between an actuator AR installed in the upper part of the piston rod and a fluid pressure source PS such as pneumatic pressure and oil pressure, the solenoid changeover valve is connected to or cut off from the fluid pressure source so that the actuator is vertically moved, and the poppet type valve element is raised or lowered via a push rod 31 interposed in a hollow hole of the piston rod to communicate the oil channel or cut off, thus becoming a buffer mode in communication with the oil channel and an expansion side oil lock mode in cutting off the oil channel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber for a vehicle for transporting passengers or luggage, and more particularly to an anti-roll hydraulic shock absorber suitable for preventing a tilt or a vertical movement of a vehicle body when loading or unloading passengers or luggage. Things.

[0002]

2. Description of the Related Art In order to improve the running stability of a vehicle, it is necessary to effectively suppress rolling, pitching, and the like of the running vehicle. For this reason, various attitude control devices have been proposed. I have.

Therefore, the applicant of the present application has previously filed Japanese Patent Application No.
No. 65143 proposes an anti-roll hydraulic shock absorber as shown in FIG.

This anti-roll type hydraulic shock absorber normally functions as a hydraulic shock absorber. However, when the vehicle attitude tends to tilt due to rolling, pitching, or the like, the anti-roll type hydraulic shock absorber is prevented from elongating to prevent the inclination from being caused. Can be.

First, the outline of the structure will be described with reference to the drawings. The anti-roll type hydraulic shock absorber includes a piston 102 connected to a piston rod 101 and provided with an extension damping valve 105, a switching valve 111, and the like. The upper chamber A and the lower chamber B are slidably guided in the cylinder 103 and are divided.

At the lower end of the cylinder 103, a pressure-side damping valve 108 and the like are disposed, and similarly partition a lower chamber B and a tank chamber C.

The electromagnetic switching valve CV is switched to a shut-off position on the right side in the figure (hereinafter, not shown in the upper, lower, left and right views in the figure), and the switching valve 111 is switched to the communication position 1 in FIG.
When 11a is selected, a buffer mode that functions as a hydraulic buffer is set.

When the piston 102 moves upward during the expansion stroke in this mode, the operating oil in the upper chamber A passes through the oil passage L and the switching valve 111, and flows through the expansion orifice 106 and the expansion damping valve 105. It flows out into the lower chamber B.

[0009] Hydraulic oil corresponding to the retreat volume insufficient due to the extension of the piston rod 101 is replenished from the tank chamber C to the lower chamber B via the pressure-side check valve 110. The combined value of the passage resistances of the expansion orifice 106 and the expansion damping valve 105 is the expansion damping force.

Conversely, when the piston 102 descends during the compression stroke, the lower chamber B is operated by the volume of the piston rod 101 excluding the replenishment of the expanding upper chamber A via the expansion check valve 107. The oil shunts through the pressure side orifice 109 and the pressure side damping valve 108 and flows out to the tank chamber C. The combined value of the passage resistances of the compression-side orifice 109 and the compression-side damping valve 108 is the compression-side damping force.

The switching valve 111 is caused to act as a pilot pressure 111e on the downstream side of the switching valve 111, which rises due to the damping force during both the expansion side and the compression side stroke, on the communication position 111a side of the switching valve 111, thereby performing switching. The valve 111 is urged in the valve opening direction to stably maintain the communication position 111a.

For example, air of a relatively low pressure is sealed in, for example, an air spring generally used for a passenger or luggage-carrying vehicle, and the deflection characteristic with respect to the loaded load is exponential as shown in FIG. When the load changes and the heavy load is loaded, the compression side sinking due to the impact input from the road surface is small.

Therefore, in practice, if only the extension side is in the oil lock state, the leaning of the vehicle body can be prevented, so that it is possible to operate as a normal hydraulic shock absorber in the compression stroke in this mode.

Next, a method for switching the switching valve 111 will be described. In the above-mentioned prior art, the switching valve 111 disposed on the piston portion is switched by adding or removing air pressure or hydraulic pressure to or from the hollow hole 101A of the piston rod 101 via the electromagnetic switching valve CV. As a pneumatic or hydraulic power source Ps, passenger or luggage transport vehicles generally have a pneumatic or hydraulic power source (for braking or power steering) and use it.

The specific structure of the switching valve 111 shown in principle in FIG. 3 is configured as shown in FIG. In the case of such a structure, the pneumatic or hydraulic pressure guided to the hollow hole 101A of the piston rod 101 via the electromagnetic switching valve CV causes the hollow hole 101 of the piston rod to be compressed.
A, a poppet-type valve element (hereinafter abbreviated as a valve element) 131, which is interposed in a valve chamber 101B formed at a lower portion of the valve member A, is pressed down against the repulsive force of the return spring 111d.
11 is switched to the cutoff position 111b.

In the extension side stroke in the shut-off position, even if the piston 102 connected to the piston rod 101 is about to extend, the passage of the upper chamber A is shut off by the switching valve 111 and the extension side check valve 107 so that the upper chamber A is closed. Becomes
This anti-roll type hydraulic shock absorber has a piston rod 101
This is a so-called extension-side oil lock mode in which the extension of oil is prevented.

[0017] In the above-mentioned extension side oil lock mode,
In the compression side stroke in which the piston rod 101 contracts, the compression side damping valve 108, the compression side orifice 109, and the extension side damping valve 107
Functions normally as a hydraulic shock absorber, but when the vehicle attitude tends to tilt due to rolling, pitching, or the like, the extension of the piston rod 101 is prevented, so that the inclination can be prevented from occurring.

The above-mentioned electromagnetic switching valve CV is driven by a controller CT which outputs a signal obtained by arithmetically processing signals from a load sensor w, a vehicle height sensor h, a speed sensor v, and the like, or outputs a signal according to a manual opening / closing signal m.

Conversely, when there is no output from the controller CT, the valve body 131 is pushed up by the reaction force of the return spring 111d, and the switching valve 111 is opened, so that a so-called buffer mode is set.

The return spring 111d is connected to the piston rod 10
Washer 1 held at its lower end by retaining ring 134
The lower end side is supported by 33 together with the valve seat 132, and urges the valve body 131 upward. Outer diameter da of guide portion 131B of valve body 131 and seat diameter d of valve seat 132
b is set to have the same diameter so that the switching force is not generated in the valve body 131 by the pressure of the upper chamber A.

The pilot 111c guided from the upper chamber A
Is applied to both sides of the large-diameter portion 131C of the valve body 131 shown in FIG. 4 so that the pressure of the upper chamber A at the time of closing the valve is applied so as to be in an equilibrium state. Therefore, the switching valve 111 can be freely switched even when the pressure in the upper chamber A becomes high in the extension side oil lock state.

The extension side damping valve is a thin disk 135, 136.
Is biased toward the lower end of the piston rod by a valve spring 137, and the thin disk 13 provided on the piston rod 101 side is
The notch 135A of No. 5 becomes the extension side orifice. Extension side damping valve consisting of thin disks 135 and 136 and notch 135A
The operation and effect of the extension orifice made of are similar to those of a general hydraulic shock absorber, and therefore detailed description is omitted.

[0023]

In the above prior art, pneumatic or hydraulic pressure is applied to a guide portion 131B of a valve body 131 interposed in a valve hole 101B provided in a piston rod 101, and a valve body is provided. The switching valve 131 is switched by pushing down the switch 131 downward against the reaction force of the return spring 111d. The valve 131 may be built into the piston rod 101. When using an air pressure source having a low pressure, it is difficult to secure a required pressure receiving area.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a sufficient switching force even when a low-pressure air pressure source is used for operating the switching valve. An anti-roll type hydraulic shock absorber is provided.

[0025]

According to the present invention, an upper chamber and a lower chamber defined by a piston connected to a piston rod connected to a vehicle body and slidably guided in a cylinder are formed in both chambers. When the switching valve disposed in the communicating oil passage is released, the piston rod is allowed to expand and contract by being communicated via the oil passage when the switching valve is released, and the oil passage is shut off when the switching valve is closed to extend the piston rod. An anti-roll type hydraulic shock absorber formed so as to prevent the occurrence of a shock is assumed.

In order to solve the problem, a means adopted in the present invention is that the switching valve is disposed in the oil passage in the piston rod so as to be movable up and down, shuts off the oil passage when descending, and closes the oil passage when rising. The poppet-type valve element is always urged in the upward direction by a return spring, and further includes an actuator mounted on the upper part of the piston rod and a fluid pressure source such as air pressure or hydraulic pressure. An electromagnetic switching valve is interposed between them, and the actuator is moved up and down by connecting or disconnecting the electromagnetic switching valve to or from a fluid pressure source, and the poppet is inserted through a push rod inserted in a hollow hole of a piston rod. The oil valve is communicated or shut off by raising or lowering the valve body of the mold so that the oil passage is in the buffer mode when the oil passage is in communication and the extension oil lock mode when the oil passage is shut off. .

The actuator is an electromagnetic switching valve which comprises a driving piston having a large pressure receiving area and a return spring, and is opened and closed by an output of a controller which has processed signals of various sensors such as a load sensor, and is connected to the fluid pressure source. Alternatively, if the vehicle is moved up and down by shutting off, the mode can be automatically switched according to a change in the vehicle condition.

If the actuator is moved up and down by connecting or disconnecting the fluid pressure source with an electromagnetic switching valve that is opened and closed by a manual switch operated by a driver, various sensors and controllers become unnecessary. Therefore, the cost associated with mode switching can be reduced.

The above-mentioned actuator is activated only when the vehicle is parked or stopped by using an operation signal of a parking brake (sensor) or the like, so that the extension side oil lock mode can be selected. The ride comfort of the vehicle can be improved.

Further, if a thrust transmission spring having a large spring constant is interposed between the push rod and the poppet type valve element, excessive thrust is prevented from being applied to the valve element when the oil passage is shut off. be able to.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An anti-roll hydraulic shock absorber according to the present invention has a switching valve DV, an expansion damping valve 11 and an expansion check valve 8 provided on a piston rod 1 as shown in a sectional model in FIG.
Are openably and closably disposed, and a piston 9 coupled to a lower portion of the piston rod 1 is slidably guided into the cylinder 2 and defines an upper chamber A and a lower chamber B. At the lower end of the cylinder 2, a compression side damping valve 42, a compression side check valve 4
1 is also provided, and also partitions a lower chamber B and a tank chamber C.

An actuator AR, which is driven by supplying and discharging air pressure or pressure from a hydraulic pressure source Ps via an electromagnetic switching valve CV, is mounted on the upper part of the piston rod 1. The electromagnetic switching valve CV is the same as the conventional one. Load sensor w,
It is driven by a controller CT which outputs an output obtained by arithmetically processing signals of a vehicle height sensor h, a speed sensor v, and the like, or a manual opening / closing signal m.

In the case of manual operation by the driver, by providing a manual switch S separately, it is possible to directly open and close the electromagnetic switching valve CV by omitting the sensors and the controller CT.

The thrust of the actuator AR is applied to a switching valve DV via a push rod 31 and a thrust transmission spring 32 to open and close the switching valve DV.

For example, air springs, which are generally used in passenger or luggage-cars, are filled with relatively low-pressure air, and the deflection characteristics with respect to the loading load are exponential as shown in FIG. When the load changes and the heavy load is loaded, the compression side sinking due to the impact input from the road surface is small.

Therefore, in practice, if only the extension side is in the oil lock state, the leaning of the vehicle body can be prevented, and therefore, it can be operated as a normal hydraulic shock absorber during the compression stroke in this mode.

Next, a specific structure of the anti-roll hydraulic shock absorber according to the present invention will be described based on the embodiment shown in FIG. First, an inner cap 22 on which seals 22A and 22B are mounted is screwed onto the upper part of the piston rod 1, and is further locked and locked by a lock nut 26.

An outer cap 23 is further screwed on the outer peripheral side of the inner cap 22, and an air chamber 21B is formed inside the outer cap 23. A driving piston 23 is vertically movably fitted on the inner peripheral side of the inner cap 22 on which the seal 22A is mounted, and is urged upward by a return spring 25 via a collar 24 inserted inside the driving piston 23. Outer cap 2
The actuator AR is formed in contact with the upper bottom of the actuator 3.

The bush 1C, 1C is vertically fixed to the hollow hole Ha at the upper part of the piston rod with the seal 1B interposed therebetween, and the bush 1C is also fixed to the hollow hole Hc side, and the lower end is provided with a cap. The push rod 31 to which 31A is connected is guided to be vertically movable. In the lower hollow hole He, a poppet-type valve element (hereinafter, abbreviated as a valve element) 34 having a seal 34C mounted on the outer peripheral side is guided to be vertically movable.

A hollow hole Hd having a smaller diameter than the hollow hole He is formed between the hollow holes Hc and He, and a bush 1D is fixed below the hollow hole Hd. A return spring 33 whose lower end is supported by the bush 1D is attached to the outer peripheral side of the small diameter portion 34A of the valve body 34, and the upper end is the valve body 34.
The valve body 34 is always urged upward by being supported by a cap 34F fixed to the small diameter portion 34B. The valve body 34 is provided with a communication hole 34E in the axial direction and a communication hole 34B orthogonal to the communication hole 34E to balance the upper and lower pressures of the valve body 34 and reduce the thrust when the valve body 34 is driven downward. I do.

The thrust transmission spring 32 inserted between the cap 31A connected to the lower end of the push rod 31 and the cap 34F connected to the upper end of the small diameter portion 34A of the valve body 34 has a high spring constant. In addition to transmitting the thrust of the push rod 31 to the valve body 34, it absorbs manufacturing errors in the axial direction of components inserted into the hollow hole of the piston rod 1. This part can be omitted if the axial dimensions of the push rod 31 and the valve body 34 can be properly managed.

A seat 1E with which the conical portion 34D of the valve body 34 abuts is fixed to the hollow hole Hf at the lower part of the piston rod, and an extension damping valve 1 for generating an extension damping force is provided below the seat 1E.
1 is fitted. The extension-side damping valve 11 has a piston 9
Is urged from the back by a valve spring 12 housed in a piston nut 10 which is connected to the piston rod 1.

A packing case 4 incorporating a seal 4A for shutting off outside air and a rod guide 5 for covering the upper part of the cylinder 2 are inserted into the piston rod 1 having the actuator AR mounted on the upper part. Is
The stopper 6 and the leaf spring 7, the extension-side check valve 8, and the piston 9 with the seal 9B mounted on the outer peripheral side are assembled. Finally, these parts are fastened to the lower spigot part with the piston nut 10 to form a piston rod assembly.

Next, the piston rod assembly is inserted into the cylinder 2 via the piston 9, and the upper part of the cylinder is covered with the rod guide 5, and the lower part of the cylinder 2 is covered with the case 16 accommodating the pressure-side damping valve and the like. To be a cylinder assembly. The cylinder assembly is inserted into the outer cylinder 3 in which predetermined hydraulic oil has been injected, and the packing case 4 is screwed onto the upper part of the outer cylinder 3 to form an anti-roll hydraulic shock absorber.

Next, the operation of the anti-roll hydraulic shock absorber according to the present invention will be described with reference to FIG. When the pressure of the air pressure source PS is guided to the inner air chamber 21B of the actuator AR connected to the upper part of the piston rod 1 by the electromagnetic switching valve CV connected to the port 21A of the outer cap 23, the pressure is increased. The drive piston 23 is attached to the inner peripheral side of the drive piston 23 so as to be vertically movable. The thrust obtained by multiplying the pressure receiving area by the pressure of the air pressure source PS overcomes the set load of the return spring 25, and the drive piston 23 moves downward. Is pushed down.

The actuator AR connected to the upper part of the piston rod 1 can freely set the pressure receiving area of the built-in drive piston 23 irrespective of the size of the piston rod 1, so that it is shared with the air pressure of the air spring. Even if the pressure of the air pressure source PS is low, a sufficient driving force can be obtained.

The collar 24 is fitted inside the drive piston 23, and the shaft 24A of the collar 24 is connected to the push rod 31, so that the thrust of the drive piston 23 is:
Through the push rod 31 and the cap 31A connected to the lower end thereof, the cap is transmitted to the thrust transmission spring 32 having a high spring constant, and the pressing force of the thrust transmission spring 32 is locked to the small diameter portion 34A. The valve body 34 is pushed downward by overcoming the set load of the return spring 33 via 34F.

As a result, while the lower end conical portion 34D of the valve body 34 abuts on the seat 1E, the seal 34C is attached to the fitting portion of the valve body 34 with the hollow hole. The space between the damping valves 11 is completely shut off.

In the extension stroke in which the switching valve DV, which is communicated or shut off by the vertical movement of the valve element 34, is switched to the shut-off position, even if the piston 9 attempts to extend, the upper chamber A extends with the switching valve DV. The passage is blocked by the side check valve 8 to be in a sealed state, and the anti-roll hydraulic shock absorber is in a so-called extension oil lock mode.

In the extension side oil lock mode,
In the compression side stroke in which the piston rod 1 is contracted, the compression side damping valve 42, the compression side orifice 41A, and the expansion side check valve 8 function normally and function as a hydraulic shock absorber, but the vehicle attitude tends to tilt due to rolling or pitching. At this time, the extension of the piston rod 1 is prevented, so that the inclination can be prevented.

In the compression stroke in this mode, the compression-side orifice 41A is provided independently of the expansion-side orifice 11B, so that the generated compression-side damping force can be set low. Even if the pressure acts on the switching valve DV via the extension side orifice 11B, the switching valve D
There is no fear that V will open.

Even if an excessively large shock input from the traveling road surface causes an abnormally large displacement and contraction speed, and the pressure in the lower chamber B becomes abnormally high and the switching valve DV opens, the compression stroke is terminated simultaneously. The pressure in the lower chamber B decreases, and the switching valve D
V immediately returns to the closed state.

The inner air chamber 2 of the outer cap 21 described above.
The supply and discharge of pressure to 1B are performed by an electromagnetic switching valve CV driven by an output of a controller CT which outputs an output obtained by arithmetically processing signals of a load sensor w, a vehicle height sensor h, a speed sensor v, etc., or a manual opening / closing signal m. Done.

In this case, an electromagnetic switching valve that is opened and closed by an output of a controller that has processed signals of various sensors such as a load sensor is automatically connected to or cut off from an air pressure source. Mode switching can be performed accurately.

In the case of manual operation by the driver, as shown in FIG. 1, by providing a manual switch S separately, the sensors and the controller CT are omitted and the electromagnetic switching valve C is directly operated.
V can be opened and closed. In this case, the actuator is communicated with the pneumatic pressure source or shut off by an electromagnetic switching valve that is opened and closed by a manual switch S operated by the driver.
The mode can be switched flexibly according to the judgment of the vehicle situation by the driver.

In the former case, when there is no output from the controller CT, the electromagnetic switching valve CV activates the inner air chamber 21.
Since B is opened to the atmosphere, the valve body 34 is
The drive piston 23 is pushed upward by the return spring 25, and the switching valve DV including the valve element 34, the return spring 33, and the seat 1E is opened, and a so-called buffer mode is set.

Next, the buffer mode will be described. When the piston rod 1 to which the piston 9 is connected rises in the expansion stroke in this mode, the hydraulic oil in the upper chamber A is guided to the expansion damping valve 11 through the communication hole 1A of the piston rod and the inside of the seat 1E.

When the thrust obtained by multiplying the pressure receiving area by the pressure exceeds the set load of the valve spring 12 for urging the extension side damping valve 11 from the back, the window 11A of the extension side damping valve 11 opens and the upper chamber A The hydraulic oil of the expansion side damping valve 11 and the expansion side orifice 11
B flows out of the piston nut 10 and flows into the lower chamber B through the communication hole 10A. At this time, the combined value of the passage resistance between the extension side damping valve 11 and the extension side orifice 11B becomes the extension side damping force.

The hydraulic oil corresponding to the withdrawal volume that is insufficient due to the extension of the piston rod 1 is supplied from the tank chamber C to the pressure-side check valve 41.
Is replenished to the lower chamber B.

Conversely, during the compression stroke, the piston rod 1
Lowers, the hydraulic oil in the lower chamber B corresponding to the intrusion volume of the piston rod 1 excluding the replenishment of the expanding upper chamber A via the expansion-side check valve 8 is reduced to the compression-side orifice 41A and the compression-side damping valve 42. And flows out to the tank chamber C. The combined value of the passage resistance of the compression-side orifice 41A and the compression-side damping valve 42 is the compression-side damping force.

Here, the running stability in the loaded state will be considered. When traveling in the extension-side oil lock mode of the above embodiment, there is no buffering action on the extension side, and the buffering action is insufficient against a large shock input from the traveling road surface, which may damage the load. There is. In order to prevent this, the extension side oil lock state may be made to appear only when the vehicle is parked or stopped when loading or unloading luggage.

More specifically, in addition to the signals from the load sensor w, the vehicle height sensor h, the vehicle speed sensor v, etc., the parking brake actuation signal p when the vehicle is parked or stopped is output in accordance with a processed output or the manual opening / closing signal m. By the controller CT (in the case of manual operation by the driver, by the manual switch S), the actuator AR is operated only when the vehicle is parked and stopped,
The anti-roll hydraulic shock absorber is switched to the extension side oil lock mode.

In this case, since there is no traveling in the oil lock state, traveling stability in the loaded state is improved, and damage to the cargo can be prevented.

In the above embodiment, the driving rod 23 having a large pressure receiving area built in the actuator AR provided on the upper part of the piston rod makes the push rod 3
The switching valve DV provided on the piston portion is actuated via 1 and the thrust transmission spring.

Therefore, even when the piston rod 1 has a small diameter and a small space, the driving piston 2 having a large pressure receiving area can be used.
With the thrust of 3, the passage from the upper chamber A to the lower chamber B is communicated or blocked, and the mode is switched to the buffer mode or the extension side oil lock mode, so that the mode switching can be reliably performed.

When the mode is switched from the buffer mode to the oil lock mode shown in FIG. 2, in order to ensure the switching, the driving piston 23 is moved longer than the stroke until the conical portion 34D of the valve body 34 comes into contact with the seat 1E. It is necessary to increase the operation stroke of the motor.

In the present invention, a thrust transmitting spring 32 having a high spring constant is interposed between the push rod 31 and the valve body 34 to absorb an axial manufacturing error of related parts. The large thrust of the cone 3
Since it does not directly apply to the contact portion between the 4D and the sheet 1E, the durability of the contact portion can be improved.

Further, since the electromagnetic switching valve CV for switching operation, the controller CT and the switching actuator having a large pressure receiving area are provided above the piston rod 1, they are mounted on the vehicle body side (above the spring of the suspension device). As a result, the unsprung weight is reduced and the ride comfort of the vehicle is improved. In addition, the vibration on the sprung part is smaller than that on the unsprung part, so that the vibration resistance can be reduced and the size and weight can be reduced. can do.

[0069]

According to the first aspect of the present invention, when the mode of the anti-roll type hydraulic shock absorber is switched using a relatively low pressure fluid pressure source shared with an air spring, the fluid pressure source and Since the actuator mounted on the upper part of the piston rod is interposed between the hydraulic shock absorber and the large driving force of the actuator, which is not limited by the size of the hydraulic shock absorber, the switching valve provided on the hydraulic shock absorber is pushed through the push rod. Can be activated.

Therefore, even when the piston rod has a small diameter and a small space, the driving force of the actuator can be increased, so that the passage from the upper chamber to the lower chamber can be communicated or blocked by the large driving force, so that the buffer mode or the extension side can be increased. Since the mode is switched to the oil lock mode, the mode can be switched reliably.

Next, according to the second aspect of the present invention, the main part of the actuator is constituted by the drive piston and the return spring, and is mounted on the upper part of the piston rod of the hydraulic shock absorber.
Even if the fluid pressure source is at a relatively low pressure, a large driving force can be obtained. The actuator is an electromagnetic switching valve that is opened and closed by an output of a controller that has processed and processed signals from various sensors such as a load sensor. The actuator is automatically connected to or disconnected from a fluid pressure source. Mode switching can be performed accurately.

Subsequently, according to the third aspect of the present invention, the actuator is an electromagnetic switching valve that is opened and closed by a manual switch operated by the driver, and is connected to or disconnected from the fluid pressure source. The mode can be switched flexibly according to the judgment of the situation.

According to the fourth aspect of the present invention, the actuator is operated only when the vehicle is parked and stopped to select the extension side oil lock mode by using an operation signal of a parking brake or the like. If possible, it will always be in the buffer mode when traveling, so it will have a sufficient buffering function even against large impacts from the traveling road surface, improving running stability in the loaded state and preventing damage to the load can do.

Further, according to the invention of claim 5, when switching from the buffer mode to the extension side oil lock mode,
A large thrust of the drive piston is applied between the valve body and the seat to insert a thrust transmission spring with a high spring constant between the push rod and the valve body to absorb manufacturing errors in the axial direction of related parts. Since it does not directly add to the contact portion, the durability of the contact portion can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional model diagram of an anti-roll hydraulic shock absorber according to the present invention.

FIG. 2 is a vertical sectional view of a main part of the anti-roll hydraulic shock absorber according to the present invention.

FIG. 3 is a vertical cross-sectional model diagram of an anti-roll hydraulic shock absorber according to the related art.

FIG. 4 is a longitudinal sectional view of a main part of an anti-roll hydraulic shock absorber according to the related art.

FIG. 5 is a characteristic diagram of a suspension spring used in the related art.

[Explanation of symbols]

 A upper chamber B lower chamber C tank chamber L oil passage S manual switch W load sensor AR actuator CT controller CV electromagnetic switching valve DV switching valve 1 piston rod 1A hollow hole in piston rod 2 cylinder 9 piston 23 drive piston 25 return spring 31 push Rod 32 Thrust transmission spring 33 Return spring 34 Poppet type valve

Claims (5)

[Claims] An upper chamber and a lower chamber defined by a piston coupled to a piston rod connected to a vehicle body and guided slidably in a cylinder are disposed in an oil passage communicating between the two chambers. When the switching valve is opened, it is communicated through the oil passage to allow the piston rod to expand and contract, and when the switching valve is closed, the oil passage is shut off to prevent the piston rod from extending. In the anti-roll type hydraulic shock absorber, a switching valve is disposed movably up and down in an oil passage in the piston rod, and shuts off the oil passage when descending, and communicates with the oil passage when rising. The poppet-type valve element is constantly urged in the upward direction by a return spring, and further includes an actuator mounted on the upper part of the piston rod and a fluid pressure source such as air pressure or hydraulic pressure. An electromagnetic switching valve is interposed therebetween, and the actuator is moved up and down by connecting or disconnecting the electromagnetic switching valve to or from a fluid pressure source, and the poppet is inserted through a push rod interposed in a hollow hole of a piston rod. An anti-roll type hydraulic shock absorber characterized by raising or lowering the valve body of the mold so as to communicate or shut off the oil passage, and to enter a buffer mode when the oil passage is communicated and an extension oil lock mode when the oil passage is shut off. vessel. 2. The actuator according to claim 1, wherein the actuator comprises a drive piston having a large pressure receiving area and a return spring. The actuator is an electromagnetic switching valve which is opened and closed by an output of a controller which has processed signals of various sensors such as a load sensor. The anti-roll hydraulic shock absorber according to claim 1, wherein the anti-roll hydraulic shock absorber is moved up and down by being connected to or disconnected from the anti-roll hydraulic shock absorber. 3. The actuator according to claim 1, wherein the actuator is an electromagnetic switching valve that is opened and closed by a manual switch operated by a driver, and is moved up and down by being connected to or disconnected from the fluid pressure source. Anti-roll type hydraulic shock absorber. 4. The actuator according to claim 1, wherein the actuator is operated only when the vehicle is parked or stopped by using an operation signal of a parking brake or the like, so that the extension side oil lock mode can be selected. The anti-roll hydraulic shock absorber according to claim 1. 5. The anti-roll hydraulic shock absorber according to claim 1, wherein a thrust transmission spring having a large spring constant is interposed between the push rod and the poppet type valve element.