CN111946769A - Hydraulic buffer for automobile - Google Patents

Abstract

The invention discloses a hydraulic buffer for an automobile, which comprises a pipe body, a piston rod, a spring, a bearing, an oil inlet cavity and an oil return cavity, wherein the piston is arranged in the pipe body; the internal damping unit that is provided with of body, the damping unit is including fixing base in the body, be fixed with the cover body on the base, be fixed with on the cover body and extend the cover, and with the piston movive seal, the cover body is embedded to have the core, the core for the cover body has along body axial displacement's degree of freedom. The invention improves the shock absorption effect of the buffer, reduces the impact force generated when the spring reciprocates, improves the comfort, and simultaneously buffers the flow of oil through the design of the damping unit structure, so that the flow of oil is more stable, the damping stability is further improved, and the vibration caused by unstable oil flow is reduced.

Description

Hydraulic buffer for automobile

Technical Field

The invention relates to the technical field of buffers, in particular to a hydraulic buffer for an automobile.

Background

In order to increase the riding comfort of the automobile, the automobile shock absorber is an indispensable part in the automobile development. Hydraulic shock absorbers are widely used in automotive suspension systems. The principle is that when the frame and the axle do reciprocating relative motion and the piston reciprocates in the cylinder of the shock absorber, oil in the shell of the shock absorber repeatedly flows into another cavity from the cavity through narrow holes. At this time, the friction between the liquid and the inner wall and the internal friction of the liquid molecules form a damping force against the vibration.

Under general conditions, when the spring is extruded by external force, the spring can impact back in the direction of the force, and after the external acting force disappears, the spring can restore to the original shape immediately, at the moment, the automobile body shakes to a certain extent due to the influence of inertia, if no damping plays a role in the vibration, the automobile can fluctuate to a large extent after stones are crushed, and a driver and passengers can feel uncomfortable. The damping function is to slow down the compression and recovery rate of the spring, slowly reduce the rapid recovery effect, so that the spring does not generate large impact force when returning, and gradually adapt to the spring by a layer-by-layer weakening method.

Disclosure of Invention

In view of the technical deficiencies, the present invention provides a hydraulic buffer for an automobile, which improves the damping effect of the buffer, reduces the impact force generated when a spring reciprocates, improves the comfort, and simultaneously buffers the flow of oil through the design of a damping unit structure, so that the flow of oil is more stable, the stability of damping is further improved, and the vibration caused by unstable oil flow is reduced.

In order to solve the technical problems, the invention adopts the following technical scheme:

the invention provides a hydraulic buffer for an automobile, which comprises a pipe body, wherein a piston capable of reciprocating is arranged in the pipe body, the piston and the pipe body are in dynamic seal, a piston rod is fixed on the piston and extends out of the pipe body, a spring is arranged between the piston and the bottom of the pipe body, the piston is tightly propped against one end of the spring, when the piston rod is not subjected to external impact force, the piston is tightly propped against and fixed on a bearing in the pipe body, when the piston reciprocates, an oil return cavity is formed between the piston and the bearing, and a space where the spring is located is an oil inlet cavity;

a damping unit is arranged in the pipe body, the damping unit is embedded in the piston and is in dynamic seal with the piston, a displacement space for the piston to reciprocate is formed in the corresponding piston, the displacement space is communicated with the oil return cavity, and an oil inlet hole communicated with the displacement space is formed in the damping unit;

the damping unit comprises a base fixed in the tube body, a cylindrical sleeve body is fixed on the base, and an extension sleeve coaxial with the sleeve body is fixed on the sleeve body and is in dynamic seal with the piston;

a core body is embedded in the sleeve body, the core body is in a conical shape with one end being flared and the other end being closed, a taper hole for placing the core body is formed in the center of the corresponding sleeve body, the taper hole is a through hole, a gap is formed between the core body and the inner wall of the taper hole, a plurality of oil inlet holes which are uniformly distributed along the circumferential direction are formed in the side wall of the sleeve body, the oil inlet holes are communicated with the gap, and the axis of each oil inlet hole penetrates through the axis of the core body and is intersected with the axis of the core body;

preferably, the core has a degree of freedom of axial displacement along the pipe body with respect to the jacket body, and when the core is axially displaced with respect to the jacket body, a gap between the core and an inner wall of the tapered hole is changed.

Preferably, the flaring end of the core body is telescopically arranged in the base through an elastic body, and a cylindrical hole for displacing the core body is formed in the corresponding base.

Preferably, the cover body includes nested overcoat and endotheca together, just the overcoat with the endotheca is sealed, seted up the round annular on the periphery wall of endotheca, the overcoat with all seted up on the outer wall of endotheca the inlet port is located inlet port on the overcoat with be located the inlet port staggered arrangement on the endotheca, and all with the annular communicates with each other.

Preferably, the extension sleeve is fixed with the outer sleeve, and the outer diameter of the outer sleeve is the same as that of the extension sleeve.

Preferably, the cross section of the annular groove is conical with one end flaring and the other end closing, the flaring is close to the axis of the tube body, and the closing is far away from the axis of the tube body.

Preferably, the piston is provided with a plurality of oil return holes which are uniformly distributed, and the displacement space is communicated with the oil return cavity through the oil return holes.

Preferably, the piston is further provided with a plurality of one-way valve holes, one end of each one-way valve hole is communicated with one part of the oil return holes, and the other end of each one-way valve hole is communicated with the oil inlet cavity;

and a one-way valve is arranged in the one-way valve hole, when the piston moves towards the oil inlet cavity, the one-way valve is closed, and when the piston moves towards the oil return cavity, the one-way valve is opened.

Preferably, the bearing is provided with an annular space for placing pressure-accumulating sponge, and the annular space is communicated with the oil inlet cavity; an oil seal is also arranged between the bearing and the piston rod, and a sealing cover is fixed on the bearing;

the end part of the piston rod is fixed with a collided head, and a silencing sleeve is fixed on the collided head.

Preferably, a rear cover is fixed at the bottom of the pipe body, and an oil filling hole communicated with the oil inlet cavity is formed in the rear cover.

The invention has the beneficial effects that:

(1) the damping unit is arranged, so that the compression and recovery rate of the spring can be reduced, and the rapid compression and recovery effect is slowly reduced, so that the spring cannot generate large impact force during compression and return, and the comfort is improved;

(2) according to the damping unit, through a radial oil inlet mode, when oil flows to the core body with the conical structure, the oil can act on an inclined plane, namely acting force is generated on the inclined plane of the core body by the oil, and through the inclined plane action of the core body, the inclined plane can generate component force opposite to the movement direction of the oil, so that the impact force is reduced, the oil flows more stably, and the vibration caused by unstable oil flow is reduced, so that the damping unit is a first buffer;

(3) the core body in the damping unit has axial displacement, and the elastic body is arranged, so that the core body has the capacity of storing elastic potential energy in the axial direction, when the spring returns after being pressed, oil in the oil return cavity reversely flows into the oil inlet cavity, the oil return can be utilized to push the core body in a displacement space, the core body has the trend of axial displacement, meanwhile, the displacement of the core body increases the gap between the core body and the inner wall of the taper hole, the space for accommodating the oil in the gap is expanded, the vibration caused by unstable oil flow is reduced, and the oil return speed is improved, which is the second buffer;

(4) the sleeve body adopts a structure of the outer sleeve and the inner sleeve, the inner sleeve is provided with the annular groove with the cross section of one end flaring and the other end closing, and the annular groove is combined with the oil inlet holes which are uniformly distributed in the circumferential direction to form annular circumferential oil inlet, so that the impact force when the oil enters is further reduced, the oil can flow in the damping unit more stably, and the third buffer is realized;

(5) the damping unit has three kinds of buffering, so that the pressure of oil flowing is more stable due to the design of decompression buffering during oil flowing, the impact force in the oil flowing process is further reduced, the damping stability is improved, and the vibration caused by unstable oil flowing is reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a sectional view of a hydraulic shock absorber for an automobile according to embodiment 1 of the present invention;

FIG. 2 is a front view of a damper unit in embodiment 2;

FIG. 3 is an exploded view of FIG. 2;

FIG. 4 is a top view of FIG. 2;

FIG. 5 is a cross-sectional view taken along line A-A of FIG. 4;

FIG. 6 is an enlarged view of portion B of FIG. 5;

FIG. 7 is another structural schematic view of the core;

FIG. 8 is a force analysis of the oil and core as the spring compression piston moves downward;

FIG. 9 is a force analysis of the oil and core as the spring return piston moves upward.

Description of reference numerals:

1-tube, 2-piston, 21-oil return hole, 22-one-way valve hole;

30-sleeve body, 31-base, 32-inner sleeve, 321-ring groove, 33-outer sleeve, 34-core body, 35-extension sleeve, 36-wave spring, 301-oil inlet hole and 302-fixing hole;

4-spring, 5-piston rod, 51-collided head, 52-silencing cover, 6-bearing, 7-rear cover, 71-oil hole, 8-pressure-accumulating sponge, 9-oil seal and 91-sealing cover.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, the invention provides a hydraulic buffer for an automobile, which comprises a pipe body 1, wherein a piston 2 capable of reciprocating is arranged in the pipe body 1, the piston 2 is in dynamic seal with the pipe body 1, a piston rod 5 is fixed on the piston 2 and extends out of the pipe body 1, a crashing head 51 is fixed on the extending end part of the piston rod 5, and a silencing sleeve 52 is fixed on the crashing head 51;

a spring 4 is arranged between the piston 2 and the bottom of the pipe body 1, the piston 2 is tightly propped against one end of the spring 4, when the piston rod 5 is not subjected to external impact force, the piston 2 is tightly propped and fixed on a bearing 6 in the pipe body 1, when the piston 3 reciprocates, an oil return cavity is formed between the piston 3 and the bearing 6, and the space where the spring 4 is located is an oil inlet cavity; after the buffer is installed, the spring 4 needs to have a certain pretightening force, namely, the spring 4 is in a certain compression state and can refer to the pretightening force of the spring in the existing buffer;

a rear cover 7 is fixed at the bottom of the pipe body 1, and an oil filling hole 71 communicated with the oil inlet cavity is formed in the rear cover 7 and used for filling oil; in addition, an annular space for placing the pressure-accumulating sponge 8 is arranged on the bearing 6, and the annular space is communicated with the oil return cavity; an oil seal 9 is also arranged between the bearing 6 and the piston rod 5, and a sealing cover 91 is fixed on the bearing 6; the above structure is similar to the existing buffer structure, namely, the oil filling hole 71 is arranged on the rear cover 7 of the pipe body 1, and the pressure storage sponge 8, the oil seal 9 and the like are arranged on the bearing 6.

Example 1:

referring to fig. 1, in the solution of the present invention, a damping unit is disposed in the tube 1, the damping unit includes a base 31 fixed in the tube 1, a cylindrical sleeve 30 is fixed on the base 31, and an extension sleeve 35 coaxial with the sleeve 30 is fixed on the sleeve 30 and is dynamically sealed with the piston 2, that is, during the reciprocating stroke of the piston 2, the piston 2 is only dynamically sealed with the extension sleeve 35; the damping unit is embedded in the piston 2, a displacement space for the piston 2 to reciprocate is formed in the corresponding piston 2, the displacement space is communicated with the oil return cavity, and a plurality of oil inlet holes 301 which are uniformly distributed along the circumferential direction are formed in the side wall of the sleeve body 30, namely in the sectional view of fig. 1, the piston 2 is in a U-shaped structure;

the sleeve body 30 is internally embedded with the core body 34, the core body 34 is in a conical shape with one end flared and the other end closed, the center of the corresponding sleeve body 30 is provided with a taper hole for the core body 34 to be placed in, the taper hole is a through hole and a round table hole, namely, the sleeve body 30 penetrates through, a gap (shown as K in figure 6) is formed between the core body 34 and the inner wall of the taper hole, the oil inlet hole 301 is communicated with the gap, and the axis of the oil inlet hole 301 penetrates through the axis of the core body 34 and is intersected with the axis; in particular with regard to the conical configuration of the core 34, it may take two forms in this embodiment, namely:

one is as follows: as shown in the cross-sectional view of fig. 1, the cross section of the core 34 has an isosceles trapezoid structure, i.e., the outer peripheral wall of the core 34 is inclined, which corresponds to the outer peripheral wall of the truncated cone;

the second step is as follows: as shown in fig. 7, the outer peripheral wall of the first core 34 is a concave arc-shaped structure;

with both of the above-described configurations, the core 34 can be beveled, except that the slope of the first beveled surface is fixed, the slope of the second beveled surface is variable, and the slope variability can be used to differentiate the forces generated by the oil by the beveled surfaces of the core 34, as described in detail below.

In the present embodiment, the core 34 has a degree of freedom of axial displacement along the tube body 1 with respect to the jacket body 30, that is, the core 34 can be axially displaced on the base 31, as shown by + Y and-Y in fig. 8 and 9, and when the core 34 is displaced in the + Y direction with respect to the jacket body 30, the gap between the core 34 and the inner wall of the tapered hole increases, and when the core 34 is displaced in the-Y direction with respect to the jacket body 30, the gap between the core 34 and the inner wall of the tapered hole decreases, specifically:

as shown in fig. 5, in order to realize the axial displacement of the core 34, the flared end of the core 34 is telescopically arranged in the base 31 through an elastic body, and a cylindrical hole for displacing the core 34 is formed in the corresponding base 31; wherein, the elastic body is a wave spring 36; in addition, in consideration of the stability of the axial displacement of the core 34, the core is prevented from generating axial deviation, a cylinder extends out of the flaring end of the core, the cylinder is matched with the cylindrical hole and then moves in the cylindrical hole, and two ends of the wave spring 36 are respectively fixed with the cylinder and the cylindrical hole;

in addition, considering the comprehensive reason, the elasticity of the wave spring 36 needs to be reasonably set according to the actual situation, the elasticity is not too low so as to avoid frequent fluctuation caused by external vibration, and the wave spring can be set to be harder in the actual use process, so that the core body cannot fluctuate due to slight external vibration, the wave spring 36 generates certain deformation when the piston 2 generates sharp large displacement, and the action of the inclined surface and other structures of the core body 34 can be mainly used for buffering the gentle impact force; in addition, it is also necessary to avoid the core 34 from separating from the cylindrical hole, a limiting structure may be disposed on the base 31 to limit the core 34 from separating from the cylindrical hole, for example, a limiting ring may be nested on the core 34, the limiting ring is fixed on the base 31, and the inner diameter of the limiting ring is slightly smaller than the maximum outer diameter of the core 34.

Further, with reference to fig. 1, in order to communicate the displacement space with the oil return cavity, the piston 2 is provided with a plurality of oil return holes 21 uniformly distributed, and the displacement space is communicated with the oil return cavity through the oil return holes 21; the oil return holes 21 are arranged in two groups, the first group is directly arranged on the top wall of the displacement space, the second group is arranged on the side wall of the displacement space, and main buffering of oil is concentrated on the damping unit, so that buffering is not needed to be carried out on the oil return holes 21, and the oil can better flow into an oil return cavity due to the arrangement of the oil return holes 21;

in addition, considering that the speed of the buffer on the return stroke is generally higher, although the clearance between the core 34 and the taper hole is increased in the return stroke process to improve the oil return speed, because the elastic force of the wave spring 36 is set to be harder, in order to further improve the oil return speed, the piston 2 is also provided with a plurality of one-way valve holes 22, one end of each one-way valve hole 22 is communicated with the second group of oil return holes 21, and the other end of each one-way valve hole 22 is communicated with the oil inlet cavity; a one-way valve is arranged in the one-way valve hole 22, and is closed when the piston 2 displaces towards the oil inlet cavity and opened when the piston 2 displaces towards the oil return cavity; in this state, there are two routes of return oil, one of which flows into the oil inlet cavity through the second group of oil return holes 21, and the other group flows into the oil inlet cavity through the damping unit, and the flow of oil is also decomposed, so that the oil stability during oil return is improved.

Example 2:

in this embodiment, it is different from embodiment 1 only in that the sheath body 30 is formed by nesting the outer sheath 33 and the inner sheath 32, specifically:

as shown in fig. 3 and 5, the sleeve body 30 includes an outer sleeve 33 and an inner sleeve 32 which are nested together, the outer sleeve 33 and the inner sleeve 32 are sealed and fixed together, a plurality of uniform and respective fixing holes 302 are formed on the outer wall of the outer sleeve 33, the fixing holes 302 are counter bores, blind holes are correspondingly formed on the inner sleeve 32, the blind holes are threaded holes, and further, the fixation is realized through bolts;

the outer peripheral wall of the inner sleeve 32 is provided with a ring of ring grooves 321, and correspondingly, the outer walls of the outer sleeve 33 and the inner sleeve 32 are both provided with oil inlet holes 301, wherein the oil inlet holes 301 on the outer sleeve 33 and the oil inlet holes 301 on the inner sleeve 32 are arranged in a staggered manner, namely, are not coaxial and are both communicated with the ring grooves 321, but for the convenience of simultaneously seeing the oil inlet holes 301 on the outer sleeve 33 and the inner sleeve 32 in the same drawing, the oil inlet holes 301 on the outer sleeve 33 are shown by using broken lines in fig. 5, and actually, the oil inlet holes 301 on the outer sleeve 33 in fig. 5 cannot be seen;

the cross section of the ring groove 321 is in a conical shape with one end flared and the other end closed, the structure expands the accommodating space of the ring groove 321, the flared end is close to the axis of the tube body 1, and the closed end is far away from the axis of the tube body 1; wherein the extension sleeve 35 is fixed with the outer sleeve 33, and the outer diameter of the outer sleeve 33 is the same as that of the extension sleeve 35;

this kind of structure of annular 321 combines together with the inlet port 301 that is the circumference equipartition, when oil gets into, form annular circumference oil feed mode, and combine the mode that the buffer generally all is vertical placing, the transversal one end flaring of personally submitting that utilizes annular 321, the taper structure of other end binding off, when oil receives the impact and produces the torrent, annular oil feed can disperse partly oil on the one hand, the accommodation space of the structure formation of on the other hand taper can form the effect of similar buffering bag in its both sides, and then make the flow of oil more steady.

In the above embodiment, in order to show the technical solution of the present invention more clearly, as shown in fig. 8 and 9, a simple force analysis is performed on the inclined surface and the oil of the core 34 (without considering the self weight of the oil), where the inclined surface is the outer peripheral wall of the truncated cone, specifically as follows:

as shown in fig. 8, when the piston 2 is impacted, the oil flows and is directed horizontally to the core 34, and the oil can be simply modeled into a mass point, and the acting force on the core 34 is combined into a force F1 directed horizontally to the core 34, wherein F1 acts on the core 34, that is, the core 34 is subjected to a force F1;

for the oil stress, according to the acting force and the reacting force, after the oil is simulated into a mass point, the mass point is subjected to the reacting force F1 'of F1 to decompose F1', and the mass point can be divided into a component force F11 along the inclined plane direction of the core body 34 and a component force F12 perpendicular to the inclined plane, so that it can be seen that the oil is subjected to a force F11 opposite to the direction of flowing to the oil return cavity, and the flowing direction of the oil is further decomposed, so that the impact force of the oil is reduced, and finally, a first buffer effect is formed.

As shown in fig. 9, after the external force is removed after the piston 2 is impacted, the piston 2 returns quickly under the action of the spring 4, oil in the oil return cavity flows into the oil inlet cavity, at this time, the inclined surface of the core body 34 also receives the action of the oil, after the oil is simulated into mass points, the oil generates a vertical downward force F1 on the inclined surface of the core body 34, an axial force can be generated on the core body 34, the core body 34 has a tendency of generating axial displacement, and simultaneously, the displacement of the core body 34 increases a gap between the core body 34 and the inner wall of the conical hole, so that the space for accommodating the oil in the gap is expanded, the impact force of the oil is reduced, the oil return speed is increased, and a second buffer effect is finally formed; meanwhile, according to the acting force and the reacting force, the inclined surface has a force F1 ' opposite to the flow direction of the oil, and the force can be divided into a component F11 ' along the inclined surface of the core body 34, so that the oil is subjected to a force F11 ' opposite to the flow direction of the oil inlet cavity, certain obstruction is generated on the oil, the impact force of the oil is reduced, and finally, a first buffer effect is formed.

In addition, when the peripheral wall of the core 34 is in the shape of an inward concave arc, the force applied is the same as above, and the difference from the slope results in a certain difference in the direction and magnitude of the force, which will not be described in detail again.

In conclusion, after the piston 2 is impacted, the inclined surface of the core body 34 and the ring groove 321 are matched with each other to form a first buffer and a third buffer, so that the impact force during oil flowing is reduced, the damping stability is improved, and the vibration caused by unstable oil flowing is reduced;

after the external force is removed after the piston 2 is impacted, in the process that the piston 2 rapidly returns under the action of the spring 4, the degree of freedom of axial displacement of the core body 34 is combined with the inclined surface of the core body, and a first buffer and a second buffer can be formed, wherein the second buffer can reduce the impact force when oil flows, on the other hand, after the core body 34 moves downwards, the gap between the core body and the taper hole is increased, and the oil return speed is increased while the impact force of the oil is reduced.

When the shock absorber is used, the existing shock absorber installation mode of the shock absorber is the same, and it needs to be noted that the shock absorber provided by the invention is matched with the compression distance of the spring 4, the distance of the displacement space and the length of the extension sleeve 35 reasonably when in actual manufacturing, namely when the compression limit of the spring 4 is reached, the displacement space is also provided so that the extension sleeve 35 is not contacted with the top wall of the piston 2, and meanwhile, the piston 2 is not separated from the outer peripheral wall of the extension sleeve 35; also in the initial state of the damper (i.e., as shown in fig. 1), at least a portion of the piston 2 is in contact with the extension sleeve 35.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (10)

1. The utility model provides a hydraulic buffer for car, includes the body, be provided with the piston that can reciprocating motion in the body, the piston with the body movive seal, be fixed with the piston rod on the piston and extend to outside the body, the piston with set up the spring between the bottom of body, the piston supports tightly the one end of spring, when the piston rod does not receive external impact force, the piston supports tightly to be fixed on the bearing in the body, when the piston carries out reciprocating motion, the piston with form back oil cavity between the bearing, the space that the spring was located is into oil cavity, its characterized in that:

a damping unit is arranged in the pipe body, the damping unit is embedded in the piston and is in dynamic seal with the piston, a displacement space for the piston to reciprocate is formed in the corresponding piston, the displacement space is communicated with the oil return cavity, and an oil inlet hole communicated with the displacement space is formed in the damping unit;

the damping unit comprises a base fixed in the tube body, a cylindrical sleeve body is fixed on the base, and an extension sleeve coaxial with the sleeve body is fixed on the sleeve body and is in dynamic seal with the piston;

the cover body is embedded to have the core, the core is the taper of one end flaring, other end binding off, corresponds the confession has been seted up at the center of the cover body the taper hole that the core was put into, the taper hole is the through hole, the core with the clearance has between the inner wall of taper hole, set up a plurality of on the lateral wall of the cover body along circumference evenly distributed the inlet port, just the inlet port communicates with each other with this clearance, the axis of inlet port pass with the axis of core and rather than crossing.

2. The hydraulic damper as in claim 1, wherein said core has a degree of freedom of axial displacement along said tube relative to said housing, and wherein a clearance between said core and an inner wall of said tapered bore changes as said core is axially displaced relative to said housing.

3. The hydraulic buffer as defined in claim 2, wherein the flared end of said core is telescopically disposed in said base by an elastic body, and a cylindrical hole for displacing said core is formed in the corresponding base.

4. The hydraulic buffer as claimed in claim 2, wherein the sleeve body comprises an outer sleeve and an inner sleeve nested together, the outer sleeve and the inner sleeve are sealed, a ring of annular groove is formed on the outer peripheral wall of the inner sleeve, the outer sleeve and the outer wall of the inner sleeve are both provided with the oil inlet holes, and the oil inlet holes on the outer sleeve and the oil inlet holes on the inner sleeve are arranged in a staggered manner and are both communicated with the annular groove.

5. The hydraulic shock absorber as recited in claim 4, wherein said extension sleeve is fixed to said outer sleeve, and an outer diameter of said outer sleeve is the same as an outer diameter of said extension sleeve.

6. The hydraulic buffer as recited in claim 4, wherein said annular groove has a cross section that is tapered with a flared end and a closed end, wherein the flared end is closer to the axis of said tube and the closed end is farther from the axis of said tube.

7. The hydraulic buffer as claimed in claim 2 or 4, wherein said piston has a plurality of oil return holes uniformly distributed therein, and said displacement space is communicated with said oil return chamber through said oil return holes.

8. The hydraulic buffer as claimed in claim 7, wherein said piston is further provided with a plurality of one-way valve holes, one end of said one-way valve hole is communicated with a portion of said oil return holes, and the other end of said one-way valve hole is communicated with said oil inlet chamber;

and a one-way valve is arranged in the one-way valve hole, when the piston moves towards the oil inlet cavity, the one-way valve is closed, and when the piston moves towards the oil return cavity, the one-way valve is opened.

9. The hydraulic buffer as claimed in claim 1, wherein said bearing has an annular space for receiving a pressure-accumulating sponge therein, said annular space being in communication with said oil-feed chamber; an oil seal is also arranged between the bearing and the piston rod, and a sealing cover is fixed on the bearing;

the end part of the piston rod is fixed with a collided head, and a silencing sleeve is fixed on the collided head.

10. The hydraulic buffer as claimed in claim 1, wherein a rear cover is fixed to the bottom of the tube body, and the rear cover is provided with an oil hole communicating with the oil inlet chamber.

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