CN103765018A

CN103765018A - Hydraulic pressure cylinder

Info

Publication number: CN103765018A
Application number: CN201280042046.9A
Authority: CN
Inventors: 中野智和
Original assignee: Kayaba Industry Co Ltd
Current assignee: KYB Corp
Priority date: 2011-09-06
Filing date: 2012-08-23
Publication date: 2014-04-30
Anticipated expiration: 2032-08-23
Also published as: JP5789456B2; WO2013035540A1; JP2013053718A; CN103765018B; KR101596176B1; KR20140050068A

Abstract

A hydraulic pressure cylinder is provided with a cushion mechanism which reduces the speed of the piston rod when the piston rod is near the end of stroke thereof relative to the cylinder tube. The cushion mechanism is provided with: a cushion bearing provided to the piston rod; a cushion cylinder surface into which the cushion bearing enters when the piston rod is near the end of stroke thereof; a cushion gap defined between the cushion cylinder surface and the cushion bearing and which throttles the flow of hydraulic fluid; a bypass path which conducts the hydraulic fluid which bypasses the cushion gap; and a resistor disposed in the bypass path. An orifice is formed in the resistor, and the orifice throttles the flow of hydraulic fluid passing through the bypass path.

Description

Fluid-pressure cylinder

Technical field

The present invention relates near the fluid-pressure cylinder that a kind of stroke end of the piston rod in cylinder barrel, piston rod is slowed down.

Background technique

The fluid-pressure cylinder (oil hydraulic cylinder) that is applied to hydraulic shovel etc. comprises near the damping mechanism that piston rod is slowed down by producing compensator or trimmer pressure the stroke end at piston rod.

JP8-61311A and JP11-230117A disclose a kind of damping mechanism, and this damping mechanism comprises buffering bearing, and this buffering bearing is formed on for dividing near the buffer gap that when piston rod is come stroke end, working fluid is passed through.The buffer sealing part (Sealing) having as the function of one-way valve is installed in the inner side of the buffering bearing by floating support.

If piston rod is come near stroke end, cushion bearing and enter the inner side of cylinder cap and divide formation buffer gap.Thus, working fluid flows out by the gap (throttling hole slot) of this buffer gap and buffer sealing part respectively, therefore, because the mobile resistance of working fluid produces compensator or trimmer pressure, thereby piston rod is slowed down.

Summary of the invention

But, in above-mentioned damping mechanism in the past, because the inner side at buffering bearing is provided with the special-purpose buffer sealing part corresponding with specification, therefore, cause the cost of product to rise and may on shock-absorbing capacity, produce deviation due to the size deviation in the gap (throttling hole slot) of buffer sealing part etc.

In addition, because the periphery at piston rod is formed with for holding the buffer sealing part groove of buffer sealing part, therefore, need to be to the piston rod processing of slotting.

The object of this invention is to provide a kind of buffer sealing part that do not use just can obtain the fluid-pressure cylinder of predetermined compensator or trimmer pressure.

According to certain mode of execution of the present invention, a kind of fluid-pressure cylinder is provided, this fluid-pressure cylinder is included near the damping mechanism that the stroke end with respect to cylinder barrel of piston rod, piston rod is slowed down, and damping mechanism comprises: buffering bearing, it is located at piston rod; Buffer cylinder face, buffering bearing is expert near Cheng Duan and is entered this buffer cylinder face; Buffer gap, its division is formed between buffer cylinder face and buffering bearing, and for working fluid mobile being carried out to throttling; Bypass path, it is for guiding the working fluid in bypass buffer gap; And damper, it is installed on bypass path; At damper, be formed with throttle orifice, this throttle orifice carries out throttling to the working fluid by bypass path mobile.

Referring to accompanying drawing, explain embodiments of the present invention, advantage of the present invention.

Accompanying drawing explanation

Fig. 1 is the sectional view of the oil hydraulic cylinder of embodiments of the present invention.

Fig. 2 A is the sectional view of the oil hydraulic cylinder after a part of Fig. 1 is amplified.

Fig. 2 B means the sectional view in the A-A cross section of Fig. 2 A.

The sectional view of the oil hydraulic cylinder of state when Fig. 3 means elongation work.

The sectional view of the oil hydraulic cylinder of state when Fig. 4 means contraction work.

Embodiment

Below, embodiments of the present invention are described with reference to the accompanying drawings.

Fig. 1 is the sectional view of the oil hydraulic cylinder 1 of embodiments of the present invention.Oil hydraulic cylinder 1 is for example used as the dipper cylinder of hydraulic shovel, by making oil hydraulic cylinder 1 work of stretching that the arm of hydraulic shovel is rotated.

Oil hydraulic cylinder (fluid-pressure cylinder) 1 comprises: the cylinder barrel 10 of tubular; Piston 20, it demarcates bar chamber 2 and end chamber 3 cylinder barrel 10 is interior; And piston rod 30, it is linked to piston 20.

Bar chamber 2 and end chamber 3 are communicated in not shown hydraulic power (working fluid pressure source), utilize the working hydraulic pressure (working fluid pressure) from this hydraulic power guiding to make piston rod 30 move up and stretch work in central axis O side.

In addition, can also use such as water-soluble replacement liquid etc. and replace oil and as working fluid.

Opening end at cylinder barrel 10 is provided with cylinder cap 40 cylindraceous, and piston rod 30 runs through this cylinder cap 40 in the mode that can slide.By the periphery screw section (outside thread) 41 of cylinder cap 40 is screwed togather and fastening cylinder cap 40 with interior all screw sections (internal thread) 12 of cylinder barrel 10.

Cylinder cap 40 has the cylinder cap embedding part 42 cylindraceous that is embedded in cylinder body inner peripheral surface 11.Peripheral part at cylinder cap embedding part 42 is provided with O type circle 9 and guard circle (Japanese: バッ Network アップリ Application グ) 19.

Interior perimembranous at cylinder cap 40 is separately installed with bearing 55, secondary Sealing 56, primary seal 57, dust seal 58, bar outer circumferential face 31 sliding contacts of these bearings 55, secondary sealing 56, primary seal 57, dust seal 58 and piston rod 30.By bearing 55 and 31 sliding contacts of bar outer circumferential face, piston rod 30 is supported in the mode of the central axis O direction parallel with cylinder barrel 10.

At cylinder cap 40, be formed with supply and discharge mouth 43, utilize this supply and discharge mouth 43 to divide and form supply and discharge path 5.Supply and discharge path 5 via be connected in cylinder barrel 10 pipe arrangement mouth 17 not shown hydraulic piping and be communicated with hydraulic power.

At cylinder cap 40, be formed with the planar cylinder cap inner peripheral surface 44 of cylinder interior week.One end of supply and discharge mouth 43, at these cylinder cap inner peripheral surface 44 openings, is divided and is formed supply and discharge path 5 between cylinder cap inner peripheral surface 44 and bar outer circumferential face 31.

In the inner side of cylinder barrel 10, holder 23 is installed.Holder 23 forms circular centered by central axis O.Holder 23 is embedded in cylinder body inner peripheral surface 11 side by side with the cylinder cap embedding part 42 of cylinder cap 40.Peripheral part at holder 23 is provided with O type circle 28 and guard circle 18.

Holder 23 has buffer cylinder face 24 as inner circumferential surface.The cylinder that buffer cylinder face 24 forms centered by central axis O is planar.

Holder 23 is connected and fixes with the cylinder cap end face 45 that is formed at the lower end of cylinder cap 40 by the conical surface 13 upper-end surface chimeric and this holder of its periphery tapering and cylinder body inner peripheral surface 11.

In addition, the fixation method about holder 23, is not limited thereto, for example, also can be fixed on by not shown bolt cylinder cap 40.In this case, needn't form the conical surface 13 at the internal surface of cylinder barrel 10.In addition, can also be integrally formed holder 23 at cylinder cap 40.

In Fig. 1, at piston rod 30, when mobile oil hydraulic cylinder 1 shrinks work downwards, the pressurized operation oil that self-hydraulic source is supplied with by hydraulic piping flows into bar chambers 2 by supply and discharge path 5.

On the other hand, in Fig. 1, when the oil hydraulic cylinder that is moved upward at piston rod 30 1 stretches work, in the trip process, the working oil of bar chamber 2 flows out to hydraulic power by supply and discharge path 5, supply and discharge mouth 43, hydraulic piping.

On oil hydraulic cylinder 1, be provided with damping mechanism 6, this damping mechanism 6 makes near piston rod 30 is come stroke end time piston rod 30 slow down.Fig. 1 represents that piston rod 30 is positioned at more forward than stroke end and is near state stroke end.

Damping mechanism 6 comprises the buffering bearing 60 cylindraceous that is installed on piston rod 30.If piston rod 30 is come near stroke end, cushion the inner side that bearing 60 enters holder 23, thereby divide, form buffer gap 4(with reference to Fig. 3 between buffering bearing 60 and holder 23).Utilize this buffer gap 4, the mobile resistance that applies to the working oil flowing out by supply and discharge path 5 from bar chamber 2, rises the pressure (following, to be called compensator or trimmer pressure) of bar chamber 2.If compensator or trimmer pressure rises, make piston rod 30 slow down.

Buffering bearing 60 has bearing outer circumferential face 61 as its outer circumferential face.The cylinder that bearing outer circumferential face 61 forms centered by central axis O is planar.The external diameter of bearing outer circumferential face 61 forms the internal diameter that is greater than the external diameter of bar outer circumferential face 31 and is less than buffer cylinder face 24.Buffer gap 4 is divided and is formed between bearing outer circumferential face 61 and buffer cylinder face 24.

At buffering bearing 60, be formed with the 62(of the circle of contact portion otch that the local cutting of bearing outer circumferential face 61 is formed).That is to say, circle of contact portion 62 is for being located at the recess of bearing outer circumferential face 61.The width of circle of contact portion 62 forms more and goes and become narrower to the below of Fig. 1.Thus, in buffer gap 4, utilize circle of contact portion 62 to divide the flow path cross sectional area and the piston rod 30 that form and reduce gradually accordingly near stroke end.The shape of the clearance of buffer gap 4 (gap width) and circle of contact portion 62 can be set according to the desired deceleration characteristic of damping mechanism 6.

Damping mechanism 6 comprises: bypass path 50, and it is for guiding the working oil in bypass buffer gap 4; And damper (adjustment screw) 63, it is installed on bypass path 50; The mobile throttle orifice 64 that carries out throttling forming the working oil by bypass path 50 at damper 63.

Bypass path 50 utilizes the bypass through hole 25 that runs through holder 23 to divide formation.Bypass through hole 25 extends setting substantially in parallel with central axis O, at the upper and lower end face of holder 23 difference opening.

Fig. 2 A is the sectional view after a part of Fig. 1 is amplified, and Fig. 2 B means the sectional view in the A-A cross section of Fig. 2 A.

The holder recess 26 that is formed with the upper-end surface depression of self-insurance gripping member 23 in the upper-end surface of holder 23, the upper end of bypass through hole 25 is at holder recess 26 openings.In addition, being not limited thereto, can be also holder recess 26 is not set and makes the upper end of bypass through hole 25 in the structure of the upper-end surface of holder 23 opening.

In the lower end of cylinder cap 40, be formed with the cylinder cap end face 45 with central axis O quadrature, the upper-end surface of holder 23 is connected to cylinder cap end face 45.

At cylinder cap end face 45, be formed with the bypass recess 46 of the discoid depression being centered by central axis O.The mode that bypass recess 46 stands facing each other mutually with the opening end of the holder recess 26 with holder 23 and bypass through hole 25 forms, and between the opening end of holder recess 26 and bypass through hole 25 and bypass recess 46, divides and forms bypass path 50.

When oil hydraulic cylinder 1 stretches work, if piston rod 30 is come near stroke end, as shown in arrow in Fig. 2 A, the working oil of bar chamber 2 flows out to hydraulic power by bypass path 50, supply and discharge path 5.

In the lower end surface of holder 23, be formed with notch 29.Thus, under the state at utmost extending at oil hydraulic cylinder 1, the upper-end surface 22 of piston 20 connects with the lower end surface of holder 23.Now, buffer gap 4 and bypass path 50 are communicated with bar chamber 2 via notch 29.

64 pairs of working oils mobile in bypass path 50 of throttle orifice apply resistance.Together therewith, the compensator or trimmer pressure of bar chamber 2 rises, and piston rod 30 is slowed down.The opening diameter of throttle orifice 64 and path-length can be set according to the desired deceleration characteristic of damping mechanism 6.

In bypass path 50, the working oil that has passed through throttle orifice 64 flows out to the gap between the holder recess 26 of holder 23 and the bypass recess 46 of cylinder cap 40, encounters the internal face of bypass recess 46 and turns to the direction towards central axis O.Thus, can prevent from causing producing noise because having passed through the jet flow of the working oil of throttle orifice 64.

Periphery at damper 63 cylindraceous is formed with periphery screw section (outside thread) 66.On the other hand, the bypass through hole 25 at holder 23 is formed with interior all screw sections 27.By the periphery screw section of damper 63 66 and interior all screw sections 27 of holder 23 are screwed togather to install damper 63.Because holder 23 is independent of cylinder cap 40, arrange, therefore, can easily to bypass through hole 25, carry out machining, and seek the cost of product.

At the interior Zhou Binglie of damper 63, be formed with throttle orifice 64 and hexagon ring 65.Damper 63 utilization is sticked in that the instrument (not shown) of hexagon ring 65 is fastening is fixed on interior all screw sections 27.

In addition, be not limited thereto, damper 63 can be also the structure of installing by being pressed into the bypass through hole 25 of holder 23.In addition, damper 63 is installed on the upper end portion of the bypass through hole 25 of holder 23, but is not limited thereto, and also can be installed on the underpart of bypass through hole 25.

In addition, can also be made as such structure: the through hole of dividing formation bypass path 50 at holder 23 forms edge and the roughly direction extension of quadrature of central axis O, and damper 63 is installed on this through hole.In this case, the opening end of through hole stands facing each other mutually with cylinder body inner peripheral surface 11, utilize cylinder body inner peripheral surface 11 by damper 63 engagings for not coming off.

From central axis O till divide to form length (radius of curvature) R1 of periphery wall portion of the bypass recess 46 of cylinder cap 40 and form and be less than from central axis O till the length R2 of the peripheral end of damper 63.As shown in Figure 2 B, a part for the cylinder cap end face 45 of cylinder cap 40 stands facing each other mutually with a part for damper 63.

Thus, even loosening and outstanding upward from bypass through hole 25 with the damper 63 that interior all screw sections 27 of holder 23 are screwed, a part for damper 63 also can connect with the cylinder cap end face 45 of cylinder cap 40, thereby can prevent that damper 63 is further outstanding upward.Under this state, bypass through hole 25 is connected with bypass recess 46.Thus, can prevent that the bypass through hole 25 of damper 63 self-insurance gripping members 23 from coming off, and, because bypass path 50 is not closed, therefore can maintain the work of damping mechanism 6.

Buffering bearing 60 with on radial direction and the mode between piston rod 30 with all gaps 7 in bearing be embedded in piston rod 30, and in the mode that can move with respect to piston rod 30 by floating support.In bearing, all gaps 7 are divided and are formed between the buffering inner peripheral surface 67 of bearing 60 and the end outer circumferential face 33 of piston rod 30.

Buffering bearing 60 with in central axis O direction and the mode between piston rod 30 with gap 8 be installed on piston rod 30.In the lower end surface of buffering bearing 60, be connected under the state of upper-end surface 22 of piston 20, gap 8 is divided and is formed between the buffering upper-end surface 68 of bearing 60 and the circular step portion 32 of piston rod 30.

Lower end surface at buffering bearing 60 is formed with notch 69.In the lower end surface of buffering bearing 60, be connected under the state of upper-end surface 22 of piston 20, notch 69 is communicated with all gaps 7 in bearing and bar chamber 2.

Fig. 3 means oil hydraulic cylinder 1 that piston rod 30 is moved upward as shown in hollow arrow when the work of stretching, extension and is near the sectional view of the state of piston rod 30 while coming stroke end.

If piston rod 30 is come near stroke end, by making to cushion the inner side that bearing 60 enters holder 23, thereby divide, form buffer gap 4 between buffering bearing 60 and holder 23.

The mobile resistance that applies of the 4 pairs of working oils that flow out to supply and discharge path 5 from bar chamber 2 in buffer gap, the compensator or trimmer pressure of bar chamber 2 rises.Together therewith, buffering bearing 60 is pressed upward, and the buffering upper-end surface of bearing 60 and the circular step portion 32 of piston rod 30 connect, and gap 8 is closed and will in bearing, between all gaps 7 and supply and discharge path 5, seals.

Thus, as shown by the arrows in Figure 3, the working oil of bar chamber 2 passes through buffer gap 4 and bypass path 50 respectively and flows out from supply and discharge path 5.The mobile resistance that applies of 64 pairs of the throttle orifices of buffer gap 4 and

bypass path

50,2 working oils that flow out from bar chamber, by making the compensator or trimmer pressure of bar chamber 2 increase, slows down piston rod 30.

Fig. 4 mean piston rod 30 as shown in hollow arrow downwards mobile oil hydraulic cylinder 1 when the work of contraction and be near the sectional view of the state of piston rod 30 while coming stroke end.

If pressurized operation oil self-hydraulic source is fed into supply and discharge path 5, cushioning bearing 60 is pressed downwards, the circular step portion 32 of piston rod 30 is left in the upper-end surface of buffering bearing 60, and divide and form gap 8 between buffering bearing 60 and piston rod 30, thereby make between the interior all gaps 7 of bearing and supply and discharge path 5 open-minded.

Thus, as shown by the arrows in Figure 4, the pressurized operation oil that is fed into supply and discharge path 5 flows into bar chamber 2 by all gaps 7, notch 69 in gap 8, bearing, and by buffer gap 4 and bypass path 50, flows into bar chamber 2 respectively.Because working oil so flows into bar chamber 2 via three streams, therefore, piston rod 30 promptly moves to shrinkage direction.

So, cushion near the function that bearing 60 seals all gaps 7 in bearing, opens on the other hand the one-way valve in all gaps 7 in bearing when contraction work when performance conduct is in the work of elongation stroke end.

Below, the main idea of present embodiment and effect, effect are described.

The oil hydraulic cylinder 1 of present embodiment comprises damping mechanism 6, and this damping mechanism 6 makes piston rod 30 slow down near the stroke end with respect to cylinder barrel 10 of piston rod 30.Damping mechanism 6 comprises: buffering bearing 60, and it is located at piston rod 30; Buffer cylinder face 24, buffering bearing 60 enters this buffer cylinder face 24 near stroke end; Buffer gap 4, its division is formed between this buffer cylinder face 24 and buffering bearing 60 and working fluid mobile is carried out to throttling; Bypass path 50, it is for guiding the working fluid of walking around this buffer gap 4; And damper 63, it is installed on this bypass path 50.At damper 63, be formed with the mobile throttle orifice 64 that carries out throttling to the working fluid by bypass path 50.

Thus, by change, be formed at shape, the size of the throttle orifice 64 of damper 63, can adjust the mobile resistance applying to the working oil by bypass path 50, can obtain predetermined compensator or trimmer pressure.

Because the damper 63 being installed on bypass path 50 is formed with throttle orifice 64, therefore, can divide form holder 23 sharing between the product of different size of bypass path 50, and can in the situation that the production code member that does not increase holder 23 only by changing the corresponding different specification of damper 63.In addition, compare with the situation that the holder 23 that forms bypass path 50 in division forms throttle orifices, can improve the machining accuracy of throttle orifice 64, can suppress the deviation of shock-absorbing capacity.

Owing to needn't buffer sealing part be installed in the inner side of buffering bearing 60 as installing in the past, therefore, the cost that can seek product declines, and can eliminate the deviation of the shock-absorbing capacity relevant to buffer sealing part.

Owing to needn't the periphery at piston rod 30 form the buffer sealing part groove of installing for buffer sealing part as installing in the past, therefore, can improve the intensity of piston rod 30.

In the present embodiment, damping mechanism 6 comprises: cylinder cap 40, and it is so that the mode supporting piston bar 30 that piston rod 30 can slide; And the holder 23 of ring-type, itself and cylinder cap 40 are installed on the inner side of cylinder barrel 10 side by side.Holder 23 has: buffer cylinder face 24; And bypass through hole 25, it is divided a part for formation bypass path 50 and damper 63 is installed.Cylinder cap 40 has: cylinder cap end face 45, and it stands facing each other mutually with the opening end of bypass through hole 25; And bypass recess 46, its depression is arranged at cylinder cap end face 45 and divides a part that forms bypass path 50; From central axis O, till divide to form the length R1 of the periphery wall portion of bypass recess 46, be made as the central axis O that is less than from piston rod 30 till the length R2 of the peripheral end of damper 63, therefore, can be by damper 63 engagings for not coming off from bypass through hole 25.

Thus, can prevent that the bypass through hole 25 of damper 63 self-insurance gripping members 23 from coming off, and, because bypass path 50 is not closed, therefore, can maintain the work of damping mechanism 6.

In addition, due to the holder 23 of damper 63 being installed, being independent of cylinder cap 40 and forming, therefore, by changing holder 23 and the damper 63 corresponding with desired deceleration characteristic, can easily adjust shock-absorbing capacity.

In the present embodiment, at cylinder cap 40, be formed with the cylinder cap end face 45 standing facing each other mutually with bypass through hole 25.

Thus, by adding holder 23 in the situation that do not change the basic shape of cylinder cap 40, can form damping mechanism 6, the cost that can suppress product rises.

In the present embodiment, damping mechanism 6 comprises: cylinder cap 40, and it is so that the mode supporting piston bar 30 that piston rod 30 can slide; And supply and discharge path 5, its division is formed between piston rod 30 and cylinder cap 40 and for supply and discharge working fluid.Buffering bearing 60 with and piston rod 30 between there is all gaps 7 in bearing mode floating support in piston rod 30.At buffering bearing 60 while entering the work of buffer cylinder face 24, in bearing, between all gaps 7 and supply and discharge path 5, be closed, on the other hand, open-minded between all gaps 7 and supply and discharge path 5 in bearing when cushioning the work that bearing 60 exits from buffer cylinder face 24.

Thus, because buffering bearing 60 is as by the one-way valve performance function of opening, sealing between all gaps 7 and supply and discharge path 5 in bearing, therefore, can when driving, fluid-pressure cylinder 1 promptly make piston rod 30 move.

Above, embodiments of the present invention have been described, but above-mentioned mode of execution is only a part that application examples of the present invention, its aim does not also lie in the concrete structure that technical scope of the present invention is defined in to above-mentioned mode of execution.

For example, the inner peripheral surface 67 of buffering bearing 60 and the end outer circumferential face of the piston rod 30 33 formation a plurality of annular slots (maze trough) that form all gaps 7 in bearing can divided.Thus, can to the interior mobile working fluid in all gaps 7 in bearing apply resistance and by buffering bearing 60 remain on the same axis of piston rod 30 on.

In addition, in the above-described embodiment, the situation that makes when the elongation work of oil hydraulic cylinder 1 piston rod slow down exemplified with damping mechanism, also can be made as near damping mechanism makes piston rod slow down when the contraction work of the oil hydraulic cylinder 1 structure stroke end at piston rod.

The application is based on the opinion of the Japanese Patent Application 2011-193792 to Japanese Patent Office application preference on September 6th, 2011, and the full content of this application is programmed in this specification by reference.

Claims

1. a fluid-pressure cylinder, it is included near the damping mechanism that the stroke end with respect to cylinder barrel of piston rod, piston rod is slowed down, and above-mentioned damping mechanism comprises:

Buffering bearing, it is located at above-mentioned piston rod;

Buffer cylinder face, above-mentioned buffering bearing is expert near Cheng Duan and is entered this buffer cylinder face;

Buffer gap, its division is formed between above-mentioned buffer cylinder face and above-mentioned buffering bearing, and for working fluid mobile being carried out to throttling;

Bypass path, it is for guiding the working fluid of walking around above-mentioned buffer gap; And

Damper, it is installed on above-mentioned bypass path;

At above-mentioned damper, be formed with throttle orifice, this throttle orifice carries out throttling to the working fluid by above-mentioned bypass path mobile.

2. fluid-pressure cylinder according to claim 1, wherein,

Above-mentioned damping mechanism comprises:

Cylinder cap, it is so that the mode that above-mentioned piston rod can slide supports this piston rod; And

The holder of ring-type, itself and above-mentioned cylinder cap are installed on the inner side of above-mentioned cylinder barrel side by side;

Above-mentioned holder has: above-mentioned buffer cylinder face; And bypass through hole, it is provided with above-mentioned damper, and this bypass through hole is divided a part that forms above-mentioned bypass path;

Above-mentioned cylinder cap has: cylinder cap end face, and it stands facing each other mutually with the opening end of above-mentioned bypass through hole; And bypass recess, it is formed at above-mentioned cylinder cap end face, and divides a part that forms above-mentioned bypass path;

From the central axis of above-mentioned piston rod, till divide the length of the periphery wall portion that forms above-mentioned bypass recess, form the central axis that is less than from above-mentioned piston rod till the length of the peripheral end of above-mentioned damper.

3. fluid-pressure cylinder according to claim 1, wherein,

Above-mentioned damping mechanism comprises:

Supply and discharge path, its division is formed between above-mentioned piston rod and above-mentioned cylinder cap, and for supply and discharge working fluid;

Above-mentioned buffering bearing with the mode floating support that there is all gaps in bearing between this buffering bearing and above-mentioned piston rod in above-mentioned piston rod,

When above-mentioned buffering bearing enters the work of above-mentioned buffer cylinder face, in above-mentioned bearing, between all gaps and above-mentioned supply and discharge path, seal, at above-mentioned buffering bearing, from above-mentioned buffer cylinder face, exit work time, open-minded between all gaps and above-mentioned supply and discharge path in above-mentioned bearing.