JPH09257086A - Hydraulic buffering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a given cushion function as road vibration exerted on a vehicle is absorbed, perform lowering of a desired car height as the car height of a vehicle is regulatable, facilitate equipment to a vehicle without requiring variation of the design of a vehicle, and to optimize expectation of improvement of general purpose properties. SOLUTION: A buffer body S to absorb road vibration inputted to a vehicle and contract during the feed of an oil pressure from an oil pressure feed discharge source P and expand during discharge of a feed oil pressure is formed such that a cylinder body 1 of which the buffer body S consists is integrally provided with a cushion mechanism 10. When the cushion mechanism 10 is contracted due to the feed of an oil pressure by the buffer body S, lowering of a bump cushion 13 due to discharge of an oil pressure is practicable and during expansion due to discharge of an oil pressure by the buffer body S, the increase of the bump cushion 13 due to the feed of an oil pressure is practicable.

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, and more particularly to an improvement of a hydraulic shock absorber that forms a suspension structure in a vehicle together with a suspension spring.

[0002]

2. Description of the Related Art Conventionally, there have been various proposals for a hydraulic shock absorber that forms a suspension structure in a vehicle together with a suspension spring, but basically, it is constructed so as to be able to absorb road surface vibration acting on the vehicle. To be done.

On the other hand, in recent years, this type of hydraulic shock absorber has also been constructed so as to be able to adjust the vehicle height in a vehicle, but in that case, the vehicle height adjustment is within the range in which the suspension spring can expand and contract. Within, that is, within the range in which the hydraulic shock absorber can be expanded and contracted.

However, even if the vehicle is equipped with a hydraulic shock absorber capable of adjusting the vehicle height, the vehicle height is further adjusted depending on the vehicle type, that is, the vehicle height exceeds the range in which the hydraulic shock absorber is compressed most. It may be required to allow the descent.

As a means for responding to this request, for example,
Japanese Utility Model Application Laid-Open No. 3-52207 discloses a vehicle height adjusting device which is provided separately between a vehicle body side and an axle side of a vehicle and which is installed separately from a suspension unit which absorbs road surface vibrations. .

That is, the vehicle height adjusting device has a bump member arranged on the vehicle body side of the vehicle and a stopper member arranged on the axle side of the vehicle so as to face the bump member. The bump member is made of an elastic body having an oil chamber inside.

When oil is filled in the oil chamber in the bump member, which is an elastic body, the bump member functions as a cushion that collides with the stopper member near the most compression of the suspension unit, while the oil chamber When the bump member comes into contact with the stopper member in a state where the oil is discharged, the bump member can be crushed and the suspension unit can be further compressed, further reducing the vehicle height. It is supposed to be possible.

As a result, according to the vehicle height adjusting device proposed above, this is combined with the suspension unit, for example,
When equipped on a truck, etc., it is possible to further lower the vehicle height by putting the suspension unit in the most compressed state and compressing the vehicle height adjusting device, facilitating loading and unloading of luggage on the loading platform, etc. become.

[0009]

However, in the case of the vehicle height adjusting device proposed above, the following inconvenience is pointed out.

That is, the bump member in the vehicle height adjusting device is made of an elastic body having an oil chamber inside, and is designed to achieve a predetermined vehicle height drop due to crushing when the oil in the oil chamber is discharged. Therefore, when the elastic body is crushed, a so-called crushing margin remains, and even when the suspension unit is put in the most compressed state and the bump member is also compressed most, the crushing margin remains in the above state. Vehicle height reduction will be realized.

On the other hand, the bump member functions as a cushion when the internal oil chamber is filled with oil, but since the oil has no elasticity, it depends on the elasticity of the elastic body forming the bump member. It becomes a cushion function.

Therefore, the elastic body forming the bump member has a considerable thickness so that it can exert sufficient elasticity and is not easily broken by repeated crushing. Need to be set.

As a result, when the vehicle height adjusting device is embodied, it is necessary to form the bump member with an elastic body having a considerable thickness. Therefore, the bump member is generated at the time of the most compression of the bump member. There is a fear that the crushing cost will be considerably large.

In order to avoid the decrease in the vehicle height drop due to the remaining of the large crushing margin, the base end of the bump member or the stopper member is retracted to the vehicle body side or the axle side of the vehicle to which they are connected. Therefore, it is necessary to change the design on the vehicle body side or the axle side of the vehicle in order to equip the vehicle height adjusting device, and there is a danger that the versatility of the vehicle cannot be expected.

The present invention was devised from the above circumstances, and its purpose is not only to exhibit a predetermined cushion function while absorbing road surface vibration acting on the vehicle, but also to the vehicle. It is possible to adjust the vehicle height at the same time and to lower the vehicle height as desired, and
It is an object of the present invention to provide a hydraulic shock absorber that is suitable for expecting an improvement in its versatility by making it easy to equip a vehicle without requiring a design change in the vehicle.

[0016]

In order to achieve the above-mentioned object, the structure of the present invention has a cylinder body connected to an axle side of a vehicle, and a lower end side is inserted into the cylinder body so that the lower end side can be retracted and the upper end is A rod body connected to the vehicle body side of the vehicle,
And absorbs road surface vibration input to the vehicle, contracts when pressure oil is supplied to the cylinder body from an external hydraulic pressure supply / discharge source, and expands when pressure oil is discharged from the cylinder body. In a hydraulic shock absorber having a shock absorber main body formed so as to adjust the vehicle height in a vehicle, the shock absorber main body is provided with a sub-cylinder continuous with the outer periphery of the upper end of the cylinder body, and a sub-cylinder A piston that is slidably housed vertically in the rod body and defines a hydraulic chamber in the sub-cylinder; and a piston that is connected to the upper end of the piston and whose tip is connected to the upper end of the rod body. A bump mechanism that is opposed to the vehicle body is provided, and a cushion mechanism that includes a bump mechanism that supplies pressure oil into the cylinder body when the cushion mechanism operates by the operation of the hydraulic pressure supply / discharge source is used. Elimination When the hydraulic oil is discharged from the cylinder body by the operation of the hydraulic pressure supply / discharge source, the piston is lowered in the sub-cylinder, and the hydraulic oil is supplied from the hydraulic pressure supply / discharge source to the hydraulic chamber. It is assumed that the piston is formed so as to rise in the cylinder.

Further, it is preferable that the tip of the bump cushion is set so as to be located below the upper end of the cylinder body when the piston descends most in the sub-cylinder.

Further, specifically, while the hydraulic pressure supply / discharge source has a hydraulic pump, one passage communicating with the hydraulic pump is communicated with the cylinder body of the shock absorber body and the other passage is It is assumed that the sub-cylinder is connected to the hydraulic chamber.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the illustrated embodiments. A hydraulic shock absorber according to one embodiment of the present invention is basically as shown in FIG.
It has a shock absorber main body S which is communicated with an oil pressure supply / discharge source P arranged outside.

The shock absorber main body S has a cylinder body 1 connected to an axle side (not shown) of a vehicle (not shown), a lower end side of the cylinder body 1 which is insertably retractable, and an upper end of the vehicle body S. A rod body 2 connected to the vehicle body side (not shown), and the expansion and contraction of the rod body 2 absorbs road surface vibration input to the vehicle, and the hydraulic pressure supply / discharge source P into the cylinder body 1 is absorbed. It is formed so as to be contracted when the pressure oil is supplied from the cylinder and expanded when the pressure oil is discharged from the cylinder body 1 so that the vehicle height of the vehicle can be adjusted.

Incidentally, the shock absorber main body S may be arranged on each part of the four wheels of the vehicle, but if necessary, for example, in the case of a truck, it is arranged only on the left and right wheel parts on the rear wheel side. It may be done.

The hydraulic pressure supply / discharge source P may be independently provided for each shock absorber main body S, but preferably, in order to ensure so-called synchronism, the left and right shock absorber main bodies S are provided. On the other hand, it is preferable that one is provided, or one is provided for the shock absorber main body S of each part of the four wheels.

Here, the structure of the shock absorber main body S of the illustrated embodiment will be briefly described. The cylinder body 1 is a double cylinder type having an outer cylinder 4 on the outer peripheral side of the cylinder 3. A piston portion 5 connected to the lower end of the rod body 2 is slidably housed inside the cylinder 3, and the piston portion 5 divides an upper oil chamber R1 and a lower oil chamber R2 into the cylinder 3. ing.

A base valve portion 6 is disposed inside the lower end of the cylinder 3, and a pressure damping valve 6a disposed in the base valve portion 6 and a pressure check valve 6b arranged in parallel with the pressure damping valve 6a are disposed above the lower portion. The oil chamber R2 is communicated with the reservoir chamber R3 formed between the cylinder 3 and the outer cylinder 4.

The reservoir chamber R3 has a tank T in the hydraulic pressure supply / discharge source P via a relief valve 7 arranged outside.
And has a gas chamber R4 bounded by an oil surface (not shown).

By the way, the upper oil chamber R1 and the lower oil chamber R
In the illustrated embodiment, 2 are in principle communicated with each other via an oil passage 5a formed from the rod body 2 to the piston portion 5, but in the oil passage 5a, extension side damping is provided. The valves 5b and 5c, the extension side check valve 5d arranged in parallel with the valves 5b and 5c, and the switching valve 8 connected in series to these are arranged.

The extension side damping valve 5b has a damping action when the piston speed is in the low to low speed range, and the extension side damping valve 5c has a damping action when the piston speed is in the middle speed range or higher. In the illustrated embodiment, the extension side check valve 5d is arranged in parallel with the drawing,
Instead of this, as shown in FIG. 2, the extension damping valve 5c may be arranged in parallel with the drawing.

By the way, in the embodiment shown in FIG. 2, it is assumed that the piston portion 5 is formed with another oil passage 5e which connects the upper oil chamber R1 and the lower oil chamber R2 to each other. It is supposed that the compression side damping valve 5f is arranged so as to dampen the piston speed in the middle speed range or higher.

The compression side damping valve 5f causes a vacuum phenomenon or an aeration phenomenon due to insufficient suction of oil into the upper oil chamber R1 when the piston portion 5 descends at high speed in the cylinder 3 (see FIG. 1). It also functions as a relief valve that keeps it out.

In the illustrated embodiment, the switching valve 8 is of a hydraulic pilot type and has a communication position 8a which is a stationary state (state shown) maintained by the urging force of a spring (not shown). , A shut-off position 8b that is a switching state that is switched when the pilot hydraulic pressure is applied.
And, by making the oil passage 5a in the communication state when in the communication position 8a to enable the operation of the damping valves 5b and 5c, and in the cut-off position 8b, shutting off the oil passage 5a. Is set to state.

Of course, in the present invention, the switching valve 8 is also set to communicate the upper oil chamber R1 with the external hydraulic pressure supply source P when the switching valve 8 is in the shut-off position 8b.

That is, it is assumed that the rod body 2 has an oil passage 2a formed in the shaft core, and the oil passage 2a is connected to the switching valve 8 on the one hand and to the external passage L1 on the other hand. Is going to be.

The passage L1 is provided with a bidirectional hydraulic pump 20 as a hydraulic pump in a hydraulic pressure supply / discharge source P described later.
To the passage L1, that is, the oil passage 2 described above.
It is possible to supply the pressure oil into the cylinder body 1 and discharge the pressure oil from the inside of the cylinder body 1 via a.

The pilot oil pressure to the switching valve 8 is guided from the oil passage 2a communicating with the passage L1.

Therefore, in the shock absorber main body S,
When the piston portion 5 descends in the cylinder 3 with the switching valve 8 maintained in the communication position 8a, the oil in the lower oil chamber R2 flows into the upper oil chamber R1 via the extension side check valve 5d, and An amount of oil corresponding to the intrusion volume of the rod body 2 flows into the reservoir chamber R3 from the lower oil chamber R2 via the pressure side damping valve 6a, and at this time, the oil passes through the pressure side damping valve 6a. A predetermined compression side damping force will be generated.

When the piston portion 5 rises in the cylinder 3 while the switching valve 8 is maintained at the communication position 8a, the oil in the upper oil chamber R1 passes through the extension side damping valves 5b and 5c. The amount of oil that flows out to the lower oil chamber R2 and corresponds to the withdrawal volume of the rod body 2 that will be insufficient in the lower oil chamber R2 flows from the reservoir chamber R3 to the lower oil chamber R2 via the pressure side check valve 6b. The oil flows in and is replenished. At this time, the oil passes through the expansion side damping valves 5b and 5c, so that a predetermined expansion side damping force is generated.

In the embodiment shown in FIG. 2,
During the pressure side stroke in which the piston portion 5 descends in the cylinder 3, depending on the hydraulic pressure between the upper oil chamber R1 and the lower oil chamber R2, the oil in the lower oil chamber R2 is disposed in the piston portion 5 on the pressure side. It also passes through the damping valve 5f, so that the compression-side damping force is also generated at this time.

As a result, in the shock absorber main body S, when the running vehicle gets over the road surface protrusion, the road surface vibration input to the vehicle by expansion and contraction with the generation of damping force on the extension side and the compression side is generated. Will be absorbed.

On the other hand, when pressure oil is supplied from the hydraulic pressure supply / discharge source P to the oil passage 2a via the passage L1, the switching valve 8 is switched to the shut-off position 8b, and the hydraulic pressure supply / discharge is performed. The pressure oil from the source P is supplied to the upper oil chamber R1, the hydraulic pressure in the upper oil chamber R1 rises, and therefore the piston portion 5 descends in the cylinder 3, and the oil in the lower oil chamber R2 accumulates in the reservoir. It will flow into the chamber R3.

When the hydraulic pressure in the upper oil chamber R1 and the extension force of the suspension spring (not shown) balance, the lowering of the piston portion 5 in the cylinder 3 is stopped.

At this time, even if the drive of the hydraulic pressure supply / exhaust source P is stopped, the operating check valve O1 holds the internal pressure of the passage L1 and the oil passage 2a, and the switching valve 8 holds the shut-off position 8b so that the buffering is performed. The container main body S is maintained in a contracted state, and the vehicle height in the vehicle is maintained in a low vehicle height state.

In the above case, when the pressure in the reservoir chamber R3 becomes equal to or higher than the set pressure, the pressure oil from the reservoir chamber R3 is released to the tank T via the relief valve 7 arranged outside. And the buffer body S that is the reservoir chamber R3 side
The breakage of the seal and the like are prevented in advance.

Further, the switching valve 8 is in the shut-off position 8b.
When the hydraulic pressure supply / exhaust source P is driven in the reverse direction to discharge the pressure oil to the passage L2, the operating check valve O
1 is in the open valve state, and the pressure oil in the upper oil chamber R1 is transferred by the extension force of the suspension spring and the suction of the hydraulic pressure supply / discharge source P through the passage L1 and the oil passage 2a to the tank T of the hydraulic supply / discharge source P and the other side. In this state, the piston portion 5 rises in the cylinder 3.

At this time, the working oil from the reservoir chamber R3 flows into the lower oil chamber R2 via the pressure side check valve 6b as the lower oil chamber R2 expands.

The discharge of the pressure oil in the upper oil chamber R1 is stopped by the balance between the suspension spring and the vehicle weight. At this time, the switching valve 8 is in the communication position 8a.
And the shock absorber main body S is maintained in an extended state,
The vehicle height of the vehicle is maintained in a high vehicle height state.

By the way, in the present invention, the shock absorber main body S is supposed to have the cushion mechanism 10 integrally provided, which cushion mechanism 10 is shown in FIG.
As shown in FIG.
The bump cushion 13 is provided.

To describe briefly, the sub-cylinder 11 is integrally connected to the outer circumference of the upper end of the cylinder body 1. In the illustrated embodiment, the upper end of the outer cylinder 4 forming the cylinder body 1 is formed in an annular shape. It is said that they are continuously provided on the outer periphery in a so-called upper end opening manner.

The piston 12 is slidably housed in the sub-cylinder 11 so as to be slidable in the up-and-down direction, which is the direction in which the rod body 2 extends and retracts, and defines a hydraulic chamber R in the sub-cylinder 11. In the embodiment, the annular hydraulic chamber R is formed in an annular shape.

The hydraulic chamber R communicates with an external passage L2, and the passage L2 communicates with a bidirectional hydraulic pump 20 in a hydraulic pressure supply / discharge source P described later.

The bump cushion 13 is formed in an annular shape similar to the piston 12, the base end of which is connected to the upper end of the piston 12 by baking or the like, and the tip of which is connected to the upper end of the rod body 2. On the vehicle body side, that is, in the illustrated embodiment, it faces a stopper member 14 that is continuously provided on the upper end of the rod body 2 and is set as a vehicle body side member.

The bump cushion 13 is made of, for example, a so-called solid body such as rubber, and is set so that the whole can exhibit appropriate elasticity.

Further, in the present invention, when the piston 12 descends the most in the sub-cylinder 11, the tip of the bump cushion 13 is located below the cylinder body 1, that is, the upper end of the outer cylinder 4. Is set.

As described above, the tip end of the bump cushion 13 that has descended most is set to retract downward from the upper end of the cylinder body 1, so that when the shock absorber main body S is contracted most, in the illustrated embodiment, The stopper member 14 is brought into contact with the upper end of the cylinder body 1, so that a so-called contraction margin in the cushion mechanism 10, that is, an ineffective portion corresponding to a crushing margin in the bump member as the above-mentioned conventional example is generated. It is possible to realize complete contraction of the shock absorber main body S as it is set, without being concerned about it.

Therefore, in the cushion mechanism 10, when the hydraulic pressure is supplied to the hydraulic chamber R by the operation of the hydraulic pressure supply / exhaust source P, the piston 12 is raised in the sub-cylinder 11 to lift the bump cushion 13. When the hydraulic pressure in the hydraulic chamber R is discharged, the piston 12 is lowered in the sub-cylinder 11 and the bump cushion 13 is lowered.

The cushion mechanism 10 allows the stopper member 14 to contact the tip of the bump cushion 13 when the bump cushion 13 is in the raised state, and exerts a predetermined cushion function. When the bump cushion 13 is in the lowered state, the stopper member 14 is allowed to come into contact with the upper end of the cylinder body 1.

By the way, when the bump function of the bump cushion 13 is exerted, the bump cushion 1
Since 3 is made of a so-called solid type elastic body, not only it exhibits a necessary and sufficient cushioning function, but also when the bump cushion 13 descends to bring the stopper member 14 into contact with the upper end of the cylinder body 1. Since the tip of the bump cushion 13 is set so as to be located below the upper end of the cylinder body 1, the shock absorber main body S is completely contracted without fear of occurrence of a so-called contraction margin in the cushion mechanism 10. The state can be realized.

The cushion mechanism 10 is functionally formed as described above, but in the present invention, since the cushion mechanism 10 is integrally provided on the shock absorber body S, As compared with the conventional proposal in which the bump member is provided separately from the suspension unit, it is advantageous in terms of mountability in the vehicle, and also the contracted state of the shock absorber body S and the cushion are provided. Mechanism 1
The operating state of 0, that is, the lowered state of the bump cushion 13 with respect to the sub-cylinder 11 can be comparatively observed, and the operating state of the cushion mechanism 10 can be easily set.

Since the cushion mechanism 10 has the hydraulic chamber R defined by the piston 12 in the sub-cylinder 11, the hydraulic chamber R is formed in an annular shape on the outer periphery of the upper end of the cylinder body 1. Together with this, the oil reservoir can be secured, so to speak, and the tank T in the hydraulic pressure supply / discharge source P originally serving as a reservoir can be downsized.

On the other hand, the hydraulic pressure supply / discharge source P has a bidirectional hydraulic pump 20 as a hydraulic pump for selectively supplying hydraulic pressure to the passages L1 and L2 in the illustrated embodiment. The bidirectional hydraulic pump 20 sucks oil in the tank T through a check valve 22 by driving an electric motor 21 as a drive source and discharges the oil into the passages L1 and L2.

At this time, the hydraulic pressure set by the relief valve 23, that is, the oil pressure supplied to the upper oil chamber R1 in the cylinder body 1 forming the shock absorber main body S is supplied to the one passage L1, and the shock absorber main body R1 is supplied. A hydraulic pressure is supplied which allows the contraction of S.

In the other passage L2, the hydraulic pressure set by the throttle 24, that is, the cushion mechanism 1 is used.
The hydraulic pressure is supplied to the hydraulic chamber R in the sub-cylinder 11 that forms 0, and the hydraulic pressure that enables the piston 12 to rise in the sub-cylinder 11 is supplied.

In the illustrated embodiment, the operating check valves O1 and O2 are provided in the passages L1 and L2, respectively. The operating check valves O1 and O2 are operated by the hydraulic pressure from the bidirectional hydraulic pump 20. Is allowed to be supplied to the shock absorber body S side or the cushion mechanism 10 side, but is set so as to prevent the backflow thereof.

Then, each of the operation check valves O
1, O2 from the so-called opposite passage, ie,
One of the operating check valves O1 is connected to the other passage L.
2 and the other operated check valve O2
Is set so as to be in the open valve state by the pilot hydraulic pressure from one passage L1.

Therefore, in the hydraulic pressure supply / exhaust source P, the bidirectional hydraulic pump 20 is, for example, rotated in the normal direction so that the passage L1.
When the hydraulic pressure is supplied to the other side, that is, when the hydraulic pressure is supplied to the upper oil chamber R1 in the cylinder body 1 forming the shock absorber main body S to contract the shock absorber main body S, the other passage L2 is disposed. The operation check valve O2 is opened, and the hydraulic pressure in the hydraulic chamber R in the sub-cylinder 11 forming the cushion mechanism 10 is released, enabling the piston 12 to descend in the sub-cylinder 11. Will be done.

In the hydraulic pressure supply / discharge source P, when the bidirectional hydraulic pump 20 is reversed to supply the hydraulic pressure to the passage L2, that is, the hydraulic pressure is supplied to the hydraulic chamber R and the piston 12 is moved. When the sub-cylinder 11 is moved up, the operating check valve O1 provided in the passage L1 is opened, and the hydraulic pressure in the upper oil chamber R1 is released, so that the shock absorber main body S is extended. Will be possible.

From the above, the hydraulic pressure supply / discharge source P is, as shown in FIG. 3, replaced with the hydraulic pressure which the one-way hydraulic pump 25 discharges by driving the engine 26 as a drive source, instead of the embodiment shown in the figure. To the passage L by the solenoid switching valve 27.
It may be set to 1 or L2 so that it can be selectively supplied and discharged.

The solenoid switching valve 27 supplies the hydraulic pressure to the passage L1 and releases the hydraulic pressure to the passage L2 when the solenoid (not shown) is excited.
Similarly, a discharge position 27b that releases the hydraulic pressure in the passage L1 and supplies the hydraulic pressure to the passage L2, and a neutral position 27 that is a cut-off position where the excitation of the solenoid is released to stop the supply and discharge of the hydraulic pressure to the passage L1 or the passage L2.
It is set to a 3-position type having c and.

Therefore, in the case of this embodiment, the engine for running the vehicle is used as the drive source, and the engine 26 which should be originally used is compared with the embodiment shown in FIG. This is advantageous in that the electric motor 21 is not required to be used.

Further, in the case of this embodiment, since the solenoid switching valve 27 has the neutral position 27c as the shut-off position, the oil leak in the solenoid switching valve 27 portion and the one-way hydraulic pump 25 portion. If the above is effectively prevented, the operation check valve O1 provided in the passage L1 and the operation check valve O2 provided in the passage L2 may be omitted.

Further, in the embodiment shown in FIG. 3, the solenoid switching valve 27 may be replaced with the solenoid switching valve 28 shown in FIG.
In this case, the solenoid switching valve 28 is set to a two-position type having a supply position 28b which is a normal position maintained by the urging force of the spring 28a and an ejection position 28d which is switched when the solenoid 28c is excited. In the state where the one-way hydraulic pump 25 continuously operates, the passage L described above is irrespective of the presence or absence of oil leak in the one-way hydraulic pump 25 portion.
1, it is possible to omit the provision of the operate check valve O1, O2 into L2.

[0071]

As described above, according to the present invention, the cushion mechanism provided in the shock absorber main body lowers the bump cushion when the shock absorber main body contracts and raises the bump cushion when the shock absorber main body extends. When the bump cushion is in the raised state, the bump cushion is allowed to come into contact with the tip of the vehicle body side member to exert a predetermined cushion function, and the bump cushion is lowered. At a certain time, it is possible not only to allow the above-mentioned body side member to abut on the upper end of the cylinder body forming the shock absorber body and to make the shock absorber body contract, but also to lower the bump cushion to lower the vehicle body side. When the member is brought into contact with the upper end of the cylinder body, the tip of the bump cushion is set so as to be located below the upper end of the cylinder body. Without fear of so-called shrinkage allowance of development in cushion mechanism, the shock absorber perfect contracted state of the body, i.e., becomes possible to achieve a desired lowered position of the vehicle height of the vehicle.

Further, according to the present invention, since the cushion mechanism is integrally connected to the shock absorber main body, the cushion mechanism is provided separately from the shock absorber main body, compared to the case where the cushion mechanism is provided separately from the shock absorber main body. It becomes possible to compare and observe the contracted state of the shock absorber main body and the operating state of the cushion mechanism, that is, the descending state of the bump cushion with respect to the sub-cylinder. The operating state can be set easily.

Further, in the present invention, since the cushion mechanism has the hydraulic chamber defined by the piston in the sub-cylinder, the hydraulic chamber is formed in an annular shape on the outer periphery of the upper end of the cylinder body. In this case, it is possible to secure the oil reservoir, so to speak, and it is possible to reduce the size of the tank in the hydraulic pressure supply / discharge source that is originally the reservoir.

Further, in the present invention, the operation of the cushion mechanism is set so as to be automatically synchronized with the expansion / contraction operation of the shock absorber body, so that the operation of the cushion mechanism is controlled or Control such as synchronizing the operation with the expansion and contraction operation of the shock absorber main body is not required, and it is possible to omit the related equipment and to realize low-cost commercialization.

As a result, according to the present invention, not only the predetermined cushion function is exhibited while absorbing the road surface vibration acting on the vehicle, but also the vehicle height can be adjusted as desired while the vehicle height can be adjusted. In addition, there is an advantage that it can be easily installed in a vehicle without requiring a design change in the vehicle and is expected to improve its versatility.

[Brief description of drawings]

FIG. 1 is a diagram showing in principle a hydraulic shock absorber according to an embodiment of the present invention.

FIG. 2 is a partial view showing another embodiment of a part of the shock absorber main body which constitutes the hydraulic shock absorber of the present invention.

FIG. 3 is a partial view showing another embodiment of the hydraulic pressure supply / discharge source that constitutes the hydraulic shock absorber of the present invention.

FIG. 4 is a diagram showing another embodiment of a switching valve forming a hydraulic pressure supply / discharge source.

[Brief description of reference numerals]

 1 Cylinder Body 2 Rod Body 10 Cushion Mechanism 11 Sub-Cylinder 12 Piston 13 Bump Cushion 20 Bidirectional Hydraulic Pump as Hydraulic Pump 25 One-way Hydraulic Pump as Hydraulic Pump L1, L2 Passage P Hydraulic Supply / Discharge Source R Hydraulic Chamber R1 Upper Oil Chamber R2 Lower oil chamber S Shock absorber body

Claims (3)

[Claims] 1. A vehicle body comprising: a cylinder body connected to an axle side of a vehicle; and a rod body having a lower end side that is retractably inserted into the cylinder body and an upper end connected to a vehicle body side of the vehicle. Absorbs the road surface vibration input to the cylinder body, contracts when the pressure oil is supplied to the cylinder body from an external hydraulic pressure supply / discharge source, and expands when the pressure oil is discharged from the cylinder body to increase the vehicle height in the vehicle. In a hydraulic shock absorber having a shock absorber main body formed so as to be adjustable, a shock absorber main body is provided with a sub-cylinder continuously provided on an outer periphery of an upper end of a cylinder body, and a direction in which a rod body extends and retracts in the sub-cylinder. A piston vertically slidably accommodated to define a hydraulic chamber in the sub-cylinder, and a bump cushion that is connected to the upper end of the piston and has its tip facing the vehicle body side connected to the upper end of the rod body. And When the cushion mechanism supplies pressure oil into the cylinder body by the operation of the hydraulic pressure supply / discharge source, the pressure oil is discharged from the hydraulic chamber to move the piston in the sub-cylinder. At the same time as lowering the pressure oil, the pressure oil from the hydraulic pressure supply / discharge source is supplied to the hydraulic chamber when the pressure oil from the cylinder body is discharged by the operation of the hydraulic pressure supply / discharge source to raise the piston in the sub-cylinder. Hydraulic shock absorber characterized by being formed in 2. The hydraulic shock absorber according to claim 1, wherein the tip of the bump cushion is set to be located below the upper end of the cylinder body when the piston descends most in the sub-cylinder. 3. The hydraulic pressure supply / discharge source has a hydraulic pump, and one passage communicating with the hydraulic pump is communicated with the cylinder body of the shock absorber body and the other passage is hydraulic pressure within the sub-cylinder. The hydraulic shock absorber according to claim 1, which is connected to the chamber.