阅读说明：本技术 一种阻尼式气弹簧 (Damping type air spring ) 是由 董喜刚 董高通 胡托克 毛锡波 于 2021-09-18 设计创作，主要内容包括：本发明公开了一种阻尼式气弹簧,包括有缸筒、伸缩设于缸筒的活塞杆,活塞杆设有活塞组件,活塞组件包括活塞骨架、矩形圈、碗形圈、活塞平垫及活塞花垫,活塞骨架固定安装于活塞杆上；矩形圈和碗形圈均套设于活塞骨架上,活塞平垫与矩形圈相抵限位,活塞花垫与碗形圈相抵限位,碗形圈的外侧壁设置为柱面；缸筒的内壁沿缸筒的轴向开设有长条的细槽,细槽供缸筒内的气体流通。本发明具有以下优点和效果：本方案利用新机械结构,采用单碗形圈和矩形圈相配合的方式,在一定程度上可减小运动时与缸筒内壁之间的摩擦阻力,从而避免在启动时产生较大的静锁力,柱面可减小碗形圈向外扩张的程度,减小弹性回复力,从而减小启动力,更便于启动。(The invention discloses a damping type gas spring, which comprises a cylinder barrel and a piston rod arranged on the cylinder barrel in a telescopic mode, wherein the piston rod is provided with a piston assembly, the piston assembly comprises a piston framework, a rectangular ring, a bowl-shaped ring, a piston flat pad and a piston flower pad, and the piston framework is fixedly arranged on the piston rod; the rectangular ring and the bowl-shaped ring are sleeved on the piston framework, the piston flat pad abuts against the rectangular ring for limiting, the piston flower pad abuts against the bowl-shaped ring for limiting, and the outer side wall of the bowl-shaped ring is a cylindrical surface; the inner wall of the cylinder barrel is provided with a strip-shaped groove along the axial direction of the cylinder barrel, and the groove is used for gas circulation in the cylinder barrel. The invention has the following advantages and effects: the new mechanical structure of this scheme utilization adopts single bowl shape circle and rectangle circle matched with mode, can reduce the frictional resistance between the motion and the cylinder inner wall to a certain extent to avoid producing great quiet locking-force when starting, the cylinder can reduce the outside degree of expanding of bowl shape circle, reduces elastic restoring force, thereby reduces the starting force, the more convenient to start.)

1. The utility model provides a damping formula air spring, includes cylinder (1), flexible locating the piston rod (2) of cylinder (1), piston rod (2) are located one end in cylinder (1) is equipped with piston assembly, its characterized in that: the piston assembly comprises a piston framework (21), a rectangular ring (3), a bowl-shaped ring (4), a piston flat pad (5) and a piston flower pad (6), and the piston framework (21) is fixedly arranged on the piston rod (2); the rectangular ring (3) and the bowl-shaped ring (4) are sleeved on the piston framework (21), the piston flat pad (5) is arranged at one end of the piston framework (21), the piston flower pad (6) is arranged at the other end of the piston framework (21), the piston flat pad (5) abuts against the rectangular ring (3) for limiting, the piston flower pad (6) abuts against the bowl-shaped ring (4) for limiting, and the outer side wall of the bowl-shaped ring (4) is arranged to be a cylindrical surface; the inner wall of cylinder (1) is followed rectangular slot (14) has been seted up to the axial of cylinder (1), slot (14) supply the gas circulation in the cylinder (1).

2. A damped gas spring as set forth in claim 1, wherein: the end face of the bowl-shaped ring (4) is provided with a deformation groove (41).

3. A damped gas spring as set forth in claim 1, wherein: the lateral wall integrated into one piece of piston skeleton (21) has bulge loop (211), bulge loop (211) will rectangle circle (3) with bowl shape circle (4) separate mutually, rectangle circle (3) are located piston flat bed pad (5) with between bulge loop (211), bowl shape circle (4) are located piston flower fills up (6) with between bulge loop (211).

4. A damped gas spring as set forth in claim 3 wherein: the distance H1 formed between the piston flat pad (5) and the convex ring (211) is larger than the thickness a of the rectangular ring (3), and the distance H2 formed between the piston flower pad (6) and the convex ring (211) is larger than the thickness b of the bowl-shaped ring (4); the ratio of the thickness a of the rectangular ring (3) to the thickness b of the bowl-shaped ring (4) is a: b = 0.5-0.6: 1.

5. a damped gas spring as set forth in claim 2 wherein: deformation recess (41) are including seting up in middle part recess (411), the cross-section of bowl shape circle (4) terminal surface are trapezoidal periphery recess (412), middle part recess (411) with periphery recess (412) are linked together, periphery recess (412) are the flaring form from inside to outside along the axial.

6. A damped gas spring as set forth in claim 1, wherein: the cylinder barrel (1) comprises a front portion (11) and a rear portion (12), the inner diameter of the front portion (11) of the cylinder barrel (1) is smaller than that of the rear portion (12) of the cylinder barrel (1), a transition inclined plane (13) is formed between the front portion (11) and the rear portion (12), and the rear portion (12) of the cylinder barrel (1) is in an outward-expanding flaring shape relative to the front portion (11).

7. A damped gas spring as set forth in claim 1, wherein: three U-shaped gaps (61) are formed in the periphery of the piston flower pad (6), and the included angle alpha between every two adjacent gaps (61) is 120 degrees.

8. A damped gas spring as set forth in claim 3 wherein: the inner wall of bowl shape circle (4) is provided with ladder convex part (42), ladder convex part (42) form valley (422) including peak (421) between adjacent ladder convex part (42), peak (421) with be the line face contact between the lateral wall of piston skeleton (21), valley (422) with be formed with the clearance between the lateral wall of piston skeleton (21).

9. A damped gas spring as set forth in claim 1, wherein: the end part, close to the piston assembly, of the piston rod (2) is connected with a nut (7) in a threaded mode, the nut (7) is matched with the piston assembly in a blocking mode, and the nut (7) is fixed to the piston rod (2) in a spot welding mode.

10. A damped gas spring as set forth in claim 3 wherein: the bowl-shaped ring (4) and the side wall of the piston framework (21), the convex ring (211) and the inner wall of the cylinder barrel (1) and the rectangular ring (3) and the side wall of the piston framework (21) are all provided with damping flow channels for air flow to pass through.

Technical Field

The invention relates to the technical field of gas springs, in particular to a damping type gas spring.

Background

The gas spring is an industrial accessory which can play a role in supporting, buffering, braking, height adjustment, angle adjustment and the like. It is mainly composed of pressure cylinder, piston rod, piston, sealing guide sleeve, filler and joint. The principle is that inert gas or oil-gas mixture is filled in a closed pressure cylinder, the pressure in a cavity is several times or dozens of times higher than the atmospheric pressure, and the motion of a piston rod is realized by utilizing the pressure difference generated by the cross section area of the piston rod smaller than that of the piston. The window is commonly used for the window of a motor home, and mainly plays a supporting role in an opening state for the window.

The common damping type gas spring in the market mainly comprises two types, wherein one type is that a piston is provided with a positive bowl-shaped ring and a negative bowl-shaped ring (as shown in figure 1), the piston comprises a cylinder barrel 1 ', a piston rod 2 ' movably arranged in the cylinder barrel 1 ', a piston 3 ' is arranged on the piston rod 2 ', the piston 3 ' comprises two positive bowl-shaped rings 4 ', under the normal drawing and using state, the friction between the rubber bowl-shaped ring and the inner wall of the cylinder barrel is relatively small under the lubricating action of grease, when the rubber part is kept still (such as opening, closing and placing for several days), the rubber part expands and tends to deform outwards along the radial direction, so that the contact area between the rubber and the inner wall of the cylinder barrel is pressurized, the friction force is increased greatly, and then produce great static locking power for the user need vigorously operate and can stimulate, not only have and use the shortcoming of taking great effort, but also may cause the window to warp even damage.

The second is a gas spring with a step-type slot on the inner wall of the cylinder barrel, for example, the Chinese patent with the publication number of CN210889881U discloses a high-performance sectional damping gas spring, which comprises a cylinder body, a piston assembly, a piston rod and a plug, wherein the cylinder body is in a long barrel shape, the rear end of the cylinder body is sealed by the plug, a guide sleeve is arranged in the cylinder body, and the guide sleeve is fixed at the front end of the cylinder body; the piston assembly is in sliding sealing fit with the inner side wall of the cylinder body, the piston assembly is fixedly arranged at the rear end of the piston rod, the front end of the piston rod penetrates through the cylinder body and is in sliding sealing fit with the guide sleeve, and a plurality of side through grooves are formed in the inner side wall of the cylinder body and are axially arranged at intervals along the cylinder body; in the axial direction of the cylinder body, the length of each bypass groove is larger than that of the contact part of the piston assembly and the inner side wall of the cylinder body. In this way, the piston can stay at any position outside the tank during use. However, the above gas spring has the following disadvantages: 1. when the piston is positioned in the area outside the groove and stops, the problem of larger starting force can be caused by pulling the piston rod; 2. the piston is required to be in a use state during assembly, and when the piston is located at the minimum stroke, the piston must be located in the groove to prevent overlarge opening force, and when the piston is located at the maximum stroke, the piston must be located outside the groove to ensure larger supporting force, so that the assembly difficulty is larger, and the requirement on size precision is higher.

Disclosure of Invention

The invention aims to provide a damping type gas spring which has the effects of labor saving in use, convenience in starting and mounting and low requirement on dimensional precision.

The technical purpose of the invention is realized by the following technical scheme: a damping type air spring comprises a cylinder barrel and a piston rod which is telescopically arranged in the cylinder barrel, wherein a piston assembly is arranged at one end of the piston rod, which is positioned in the cylinder barrel, the piston assembly comprises a piston framework, a rectangular ring, a bowl-shaped ring, a piston flat pad and a piston flower pad, and the piston framework is fixedly arranged on the piston rod; the piston flat pad is arranged at the other end of the piston framework and abuts against the rectangular ring for limiting, the piston flower pad abuts against the bowl-shaped ring for limiting, and the outer side wall of the bowl-shaped ring is arranged to be a cylindrical surface; the inner wall of the cylinder barrel is provided with a strip-shaped groove along the axial direction of the cylinder barrel, and the groove is used for gas circulation in the cylinder barrel.

Through adopting above-mentioned technical scheme, when the relative cylinder of piston rod outwards pulls out to the cylinder, the piston skeleton drives the relative cylinder motion of rectangle circle and bowl shape circle above that, the air current in the cylinder realizes slow circulation through the slot, adopt single bowl shape circle and rectangle circle matched with mode, can reduce to a certain extent during the motion and the cylinder inner wall between the frictional resistance, thereby avoid producing great quiet locking power when starting, in addition, because bowl shape circle outer wall sets up to the cylinder, for the conical surface among the prior art, can reduce the bowl shape circle outwards expanded degree after the certain time of stewing, can reduce elastic restoring force to a certain extent, thereby reduce the starting force, be more convenient for start. By adopting the mode of the whole fine groove structure, the relative stop at any position can be ensured, and the difference between the inside and the outside of the groove does not exist, so that the starting force requirement is favorably reduced, the installation is convenient, the piston rod is not required to be installed at a specific position, the requirement on the size precision is lower, and the production cost is lower than that of the prior art.

The invention is further provided with: the end surface of the bowl-shaped ring is provided with a deformation groove.

Through adopting above-mentioned technical scheme, offer the deformation recess at the terminal surface of bowl shape circle, even under the longer condition of the time of stewing or bowl shape circle is because of external environment factor thermal expansion, when the piston rod drove the relative cylinder barrel motion of bowl shape circle, the bowl shape circle can be relatively to deformation in the deformation recess, and the deformation recess can be for it radially provides the space of deformation to reduce the friction area of contact between bowl shape circle and the cylinder barrel inner wall.

The invention is further provided with: the side wall of the piston framework is integrally formed with a convex ring, the convex ring separates a rectangular ring and a bowl-shaped ring, the rectangular ring is located between the piston flat pad and the convex ring, and the bowl-shaped ring is located between the piston patterned pad and the convex ring.

Through adopting above-mentioned technical scheme, the bulge loop makes piston assembly both can not mutual interference when the motion with rectangle circle and bowl shape circle phase separation, has better independence.

The invention is further provided with: the distance H1 formed between the piston flat pad and the convex ring is larger than the thickness a of the rectangular ring, and the distance H2 formed between the piston flower pad and the convex ring is larger than the thickness b of the bowl-shaped ring; the ratio of the thickness a of the rectangular ring to the thickness b of the bowl-shaped ring is a: b = 0.5-0.6: 1.

Through adopting above-mentioned technical scheme, because interval H1 is greater than rectangle circle thickness a, interval H2 is greater than bowl shape circle thickness b, so, can provide certain deformation clearance for rectangle circle and bowl shape circle in the axial.

The invention is further provided with: the deformation groove comprises a middle groove arranged on the end face of the bowl-shaped ring and a peripheral groove with a trapezoidal cross section, the middle groove is communicated with the peripheral groove, and the peripheral groove is in a flaring shape from inside to outside along the axial direction.

Through adopting above-mentioned technical scheme, because the periphery recess outwards is the flaring form, so, be close to flaring outer end department more in the axial, the deformability of bowl shape circle lateral wall is big more.

The invention is further provided with: the cylinder barrel comprises a front part and a rear part, the inner diameter of the front part of the cylinder barrel is smaller than that of the rear part of the cylinder barrel, a transition inclined plane is formed between the front part and the rear part, and the rear part of the cylinder barrel is in an outward expansion flaring shape relative to the front part.

Through adopting above-mentioned technical scheme, set up the rear portion of cylinder into flaring form, under initial condition, when piston assembly corresponds and is located the cylinder rear portion, because leave relatively great space between piston assembly and the cylinder inner wall for the air current changes the circulation, so more convenience of customers carries out opening and close operation of air spring, when the air spring was installed on the window, the window was when being close the closed region and opening the process, laborsaving effect was better.

The invention is further provided with: three U-shaped notches are formed in the periphery of the piston flower pad, and the included angle alpha between every two adjacent notches is 120 degrees.

The invention is further provided with: the inner wall of the bowl-shaped ring is provided with step convex parts, each step convex part comprises a peak, a valley is formed between every two adjacent step convex parts, the peaks are in line-surface contact with the side wall of the piston framework, and a gap is formed between each valley and the side wall of the piston framework.

Through adopting above-mentioned technical scheme, when the piston rod drove the motion of calathiform circle, calathiform circle outer wall and the friction of cylinder inner wall, certain deformation will take place outwards for produce certain gap between peak and the piston skeleton lateral wall, can supply the air current to pass through, when the piston rod was in the state of stewing, line surface contact formed between peak and the piston skeleton lateral wall was sealed, and the air current can't pass through, can realize stopping relatively, the process of stewing.

The invention is further provided with: the end part of the piston rod close to the piston assembly is in threaded connection with a nut, the nut and the piston assembly are in abutting fit, and the nut is fixed on the piston rod in a spot welding mode.

Through adopting above-mentioned technical scheme, the nut is fixed in on the piston rod through spot welding, and the fastness is higher, is difficult for droing.

The invention is further provided with: damping flow passages for air flow to pass through are arranged between the side walls of the bowl-shaped ring and the piston framework, between the inner walls of the convex ring and the cylinder barrel and between the side walls of the rectangular ring and the piston framework.

By adopting the technical scheme, when the piston rod drives the piston assembly to move, the damping flow channel can be used for a certain amount of air flow to slowly pass through.

In conclusion, the invention has the following beneficial effects:

1. in addition, because the outer wall of the bowl-shaped ring is arranged into a cylindrical surface, compared with a conical surface in the prior art, the bowl-shaped ring can reduce the outward expansion degree after standing for a certain time, and can reduce the elastic restoring force to a certain extent, thereby reducing the starting force and being more convenient to start;

2. by adopting the mode of the whole slot structure, the relative stop at any position can be ensured, and the difference between the inside and the outside of the slot does not exist, so that the requirement on starting force is favorably reduced, the installation is convenient, the piston rod is not required to be installed at a specific position, the requirement on size precision is lower, and the production cost is lower than that of the prior art;

3. the mode that the distance H1 is larger than the thickness a of the rectangular ring and the distance H2 is larger than the thickness b of the bowl-shaped ring is adopted, so that a certain deformation gap can be provided for the rectangular ring and the bowl-shaped ring in the axial direction;

4. the mode of flaring form is established to the rear portion that adopts the cylinder, and the convenience of customers carries out opening and close operation of air spring more, and when the air spring was installed on the window, the window was opening the process when being close the closed region, and laborsaving effect is better.

Drawings

Fig. 1 is a partial structural relationship sectional view of a gas spring in the prior art.

Fig. 2 is a partial structural sectional view of the embodiment.

FIG. 3 is a sectional view showing a partial structure of the piston rod and the piston assembly in the embodiment.

FIG. 4 is a sectional view showing the structural relationship of the bowl ring in the embodiment.

Fig. 5 is a cross-sectional view of the front portion of the cylinder tube in the embodiment.

FIG. 6 is a schematic structural diagram of the piston flower pad in the embodiment.

In the figure: 1', a cylinder barrel; 2', a piston rod; 3', a piston; 4', a bowl-shaped ring; 1. a cylinder barrel; 11. a front portion; 12. a rear portion; 13. a transition bevel; 14. a fine groove; 15. a rear joint; 2. a piston rod; 21. a piston skeleton; 211. a convex ring; 22. a front joint; 3. a rectangular ring; 4. a bowl-shaped ring; 41. a deformation groove; 411. a middle groove; 412. a peripheral groove; 42. a stepped convex portion; 421. a spike; 422. a valley; 5. a piston flat pad; 6. piston flower pad; 61. a notch; 7. and a nut.

Detailed Description

The invention will be further described with reference to the accompanying drawings. For convenience of explanation, the following "left" and "right" are both in the same direction as shown in fig. 2.

A damping type gas spring is shown in figures 2-3 and 6 and comprises a cylinder barrel 1 and a piston rod 2 which is telescopically arranged on the cylinder barrel 1, inert gas is filled in the cylinder barrel 1, a piston assembly is arranged at one end, located in the cylinder barrel 1, of the piston rod 2, a front connector 22 is arranged at the end portion, located outside the cylinder barrel 1, of the piston rod 2, a rear connector 15 is arranged at the tail end of the cylinder barrel 1, and the gas spring can be installed on external equipment through the front connector 22 and the rear connector 15. The piston assembly comprises a piston framework 21, a rectangular ring 3, a bowl-shaped ring 4, a piston flat pad 5 and a piston flower pad 6. Piston skeleton 21 fixed mounting is in the tail end of piston rod 2, piston skeleton 21 is located to rectangle circle 3 and bowl shape circle 4 all cover, piston skeleton 21's lateral wall integrated into one piece has bulge loop 211, bulge loop 211 separates rectangle circle 3 and bowl shape circle 4 mutually, piston flat pad 5 sets up in piston skeleton 21's left end, piston flower pad 6 sets up in piston skeleton 21's right-hand member, piston flat pad 5 and piston flower pad 6 all overlap locate on piston rod 2 and with the tip counterbalance cooperation of piston skeleton 21, piston flat pad 5 offsets spacingly with rectangle circle 3, piston flower pad 6 and bowl shape circle 4 spacing cooperation, rectangle circle 3 is located between piston flat pad 5 and the bulge loop 211, bowl shape circle 4 is located between piston flower pad 6 and the bulge loop 211, the breach 61 of three U-shaped is seted up to piston flower pad 6's periphery, contained angle alpha between the adjacent breach 61 is 120. The convex ring 211 separates the rectangular ring 3 and the bowl-shaped ring 4, so that the two piston assemblies cannot interfere with each other when moving, and the piston assemblies have better independence.

As shown in fig. 3-4, the outer side wall of the bowl-shaped ring 4 is a cylindrical surface, the right end surface of the bowl-shaped ring 4 is provided with a deformation groove 41, the deformation groove 41 includes a middle groove 411 provided on the end surface of the bowl-shaped ring 4 and a peripheral groove 412 with a trapezoidal cross section, the middle groove 411 is communicated with the peripheral groove 412, and the peripheral groove 412 is flared from inside to outside along the axial direction. Since the peripheral groove 412 flares outwardly, the deformation capacity of the side wall of the bowl-shaped ring 4 is greater the closer it is axially to the outer end of the flare.

As shown in FIG. 3, the distance H1 between the piston flat pad 5 and the convex ring 211 is larger than the thickness a of the rectangular ring 3, and the distance H2 between the piston flower pad 6 and the convex ring 211 is larger than the thickness b of the bowl-shaped ring 4. The ratio of the thickness a of the rectangular ring 3 to the thickness b of the bowl-shaped ring 4 is a: b = 0.5-0.6: 1, in the present embodiment, the thickness a is set to 1.6cm and the thickness b is set to 3 cm. Since the distance H1 is greater than the thickness a of the rectangular ring 3 and the distance H2 is greater than the thickness b of the bowl-shaped ring 4, a certain deformation gap can be provided for the rectangular ring 3 and the bowl-shaped ring 4 in the axial direction.

As shown in fig. 2 and 5, the cylinder tube 1 includes a front portion 11 and a rear portion 12, the front portion 11 of the cylinder tube 1 has an inner diameter smaller than that of the rear portion 12 of the cylinder tube 1, a transition slope 13 is formed between the front portion 11 and the rear portion 12, and the rear portion 12 of the cylinder tube 1 is flared outward with respect to the front portion 11. The inner wall of the front portion 11 of the cylinder tube 1 is opened with a long thin groove 14 along the axial direction of the cylinder tube 1, and the thin groove 14 is used for the gas circulation in the cylinder tube 1. Set up the rear portion 12 of cylinder 1 to the flaring form, under initial condition, when piston assembly corresponds and is located 1 rear portion 12 of cylinder, because leave relatively great space between piston assembly and the 1 inner wall of cylinder for the air current is changeed the circulation, so more convenience of customers carries out opening and close operation of air spring, when the air spring was installed on the window, the window was when being close the closed region and opening the process, laborsaving effect was better.

As shown in fig. 4, two step protrusions 42 are axially disposed on the inner wall of the bowl-shaped ring 4, each step protrusion 42 includes a peak 421, a valley 422 is formed between adjacent step protrusions 42, the peak 421 and the side wall of the piston frame 21 are in line-surface contact, and a gap is formed between the valley 422 and the side wall of the piston frame 21. The lateral wall of bowl shape circle 4 and piston skeleton 21, all be equipped with the damping runner that supplies the air current to pass through between the inner wall of bulge loop 211 and cylinder 1 and the lateral wall of rectangle circle 3 and piston skeleton 21, the external diameter of bulge loop 211 is less than the external diameter of bowl shape circle 4 and rectangle circle 3, make and to form the damping runner between bulge loop 211 outer wall and the cylinder 1 inner wall, when piston rod 2 drove piston assembly motion, produce the friction between the inner wall of bowl shape circle 4 outer wall and cylinder 1, certain deformation will outwards take place for bowl shape circle 4, make and produce certain gap between peak 421 and the piston skeleton 21 lateral wall, form the damping runner promptly, can supply a certain amount of air current to slowly pass through. When the piston rod 2 is in a standing state, the peak 421 contacts with the side wall of the piston skeleton 21 in a line-surface manner to form a seal, and air flow cannot pass through the seal, so that the relative standing and standing processes can be realized.

As shown in fig. 2 and 3, a nut 7 is connected to the tail end of the piston rod 2 in a threaded manner, the nut 7 is in abutting fit with the piston assembly, and the nut 7 is fixed to the piston rod 2 in a spot welding manner. The nut 7 is fixed on the piston rod 2 through spot welding, and is high in firmness and not easy to fall off.

The basic working principle of the invention is as follows: when the piston rod 2 is pulled out to the cylinder 1 outward relative to the cylinder 1, the piston skeleton 21 drives the rectangular ring 3 and the bowl-shaped ring 4 to move relative to the cylinder 1, the air flow in the cylinder 1 realizes slow circulation through the fine groove 14, the mode of matching the single bowl-shaped ring 4 with the rectangular ring 3 is adopted, the friction resistance between the inner wall of the cylinder 1 and the movement can be reduced to a certain extent, thereby avoiding generating larger static locking force when starting, in addition, because the outer wall of the bowl-shaped ring 4 is set to be a cylindrical surface, compared with the conical surface in the prior art, the degree of outward expansion of the bowl-shaped ring 4 after standing for a certain time can be reduced, the elastic restoring force can be reduced to a certain extent, thereby reducing the starting force, and being more convenient for starting. Set up deformation recess 41 at bowl shape circle 4's terminal surface, even under the longer condition of the time of stewing or bowl shape circle 4 is because of external environment factor thermal expansion, when piston rod 2 drove the relative cylinder 1 motion of bowl shape circle 4, bowl shape circle 4 can be to deformation in the deformation recess 41 relatively, and deformation recess 41 can be for it radially provides the space of deformation to reduce the frictional contact area between bowl shape circle 4 and the cylinder 1 inner wall.

By adopting the mode of the whole fine groove 14 structure, the relative stop at any position can be ensured, and the difference between the inside and the outside of the groove does not exist, so that the requirement on starting force is favorably reduced, the installation is convenient, the piston rod 2 is not required to be installed at a specific position, the requirement on size precision is lower, and the production cost is lower than that of the prior art.

The above description is only a preferred embodiment of the present invention, and all equivalent changes or modifications of the structure, characteristics and principles described in the present invention are included in the scope of the present invention.