WO2022044832A1

WO2022044832A1 - Multi-stage fluid pressure cylinder

Info

Publication number: WO2022044832A1
Application number: PCT/JP2021/029751
Authority: WO
Inventors: 泰志船戸; 夏樹谷川
Original assignee: Ｋｙｂ株式会社
Priority date: 2020-08-24
Filing date: 2021-08-12
Publication date: 2022-03-03
Also published as: GB202303137D0; JP2022036744A; CN115956164A; JP7457605B2; GB2613727A

Abstract

This multi-stage fluid pressure cylinder (100) comprises a cylinder tube (10), a first rod assembly (30), a second rod assembly (40), and a snap ring (35) that is accommodated in an annular recess (30b) formed in the first rod assembly (30). At least one of the first rod assembly (30) and the second rod assembly (40) is provided with a communication passage (32c, 42d) that communicates, to an opposite-from-rod-side chamber (5), a gap (G1) that is delimited by the snap ring (35), an outer circumferential surface (42a) of a first inside piston section (42), and an inner circumferential surface (30a) of the first rod assembly (30) during a condition in which the snap ring (35) is accommodated in an accommodation recess (42c).

Description

Multi-stage fluid pressure cylinder

The present invention relates to a multi-stage fluid pressure cylinder.

JPH4-254005A includes a cylinder tube and an outer rod member provided with an outer piston portion at the end, which slides along the inner peripheral surface of the cylinder tube and divides the inside of the cylinder tube into a rod side chamber and an anti-rod side chamber. , An inner piston portion that slides along the inner peripheral surface of the outer rod member is provided at the end, and an inner rod member is provided on the inner peripheral surface of the outer rod member to limit the movement of the inner rod member in the contraction direction. A multi-stage fluid pressure cylinder with a snap ring is disclosed.

The inner piston portion of the multi-stage fluid pressure cylinder described in JPH4-254005A is formed with a housing recess for accommodating the inner diameter side of the snap ring when the inner rod member contracts. When the multi-stage fluid pressure cylinder having such a configuration is in the most contracted state and the working fluid is not supplied or discharged to the rod side chamber and the anti-rod side chamber, the multi-stage fluid pressure cylinder is forcibly extended. When an external force acts suddenly, the pressure in the anti-rod side chamber decreases, while the pressure in the rod side chamber increases. When the pressure in the rod side chamber becomes high in this way, the outer rod member is displaced in the extending direction together with the cylinder tube, so that the snap ring provided on the outer rod member is separated from the accommodating recess of the inner piston portion.

Then, when the snap ring separates from the accommodating recess and the volume of the gap defined by the outer peripheral surface of the inner piston portion, the inner peripheral surface of the outer rod member, and the snap ring rapidly increases, the pressure in the gap and around the accommodating recess is increased rapidly. Will be lower than the pressure in the anti-rod side chamber. When the pressure in the region facing the inner diameter side of the snap ring decreases in this way, a fluid force acting in the direction of reducing the diameter of the snap ring is generated on the inner diameter side of the snap ring against the elastic force of the snap ring acting in the diameter expansion direction. As a result, the outer diameter of the snap ring becomes smaller, and as a result, the snap ring may come off from the outer rod member.

The present invention aims to prevent the snap ring from coming off.

According to an aspect of the present invention, the multistage fluid pressure cylinder is a cylinder tube and an outer piston that slides along the inner peripheral surface of the cylinder tube and divides the inside of the cylinder tube into a rod side chamber and an anti-rod side chamber. A cylindrical outer rod member having a portion at the end, an inner rod member having an inner piston portion sliding along the inner peripheral surface of the outer rod member at the end, and the outer rod member. The inner piston portion is provided with a snap ring in which the outer diameter side is accommodated in the annular recess formed on the inner peripheral surface and restricts the movement of the inner rod member in the contraction direction, and the inner rod member is contracted in the inner piston portion. An accommodating recess for accommodating the inner diameter side of the snap ring is provided, and the snap ring is accommodated in the accommodating recess and abuts on the inner piston portion in at least one of the outer rod member and the inner rod member. The cylinder tube moves relative to the anti-rod side chamber or the outer rod member in a gap defined by the snap ring, the outer peripheral surface of the inner piston portion, and the inner peripheral surface of the outer rod member. By doing so, a communication passage is provided to communicate with the fluid chamber communicating with the anti-rod side chamber.

It is sectional drawing of the fluid pressure cylinder which concerns on embodiment of this invention, and is the figure which shows the maximum contraction state. It is sectional drawing which shows the fluid pressure cylinder which concerns on embodiment of this invention, and is the figure which shows the state which the 1st rod assembly is in an extension position, and the 2nd rod assembly and the 3rd rod assembly are in a contraction position. It is sectional drawing which shows the fluid pressure cylinder which concerns on embodiment of this invention, and shows the state which the 1st rod assembly and the 2nd rod assembly are in the extended position, and the 3rd rod assembly is in a contracted position. It is sectional drawing which shows the fluid pressure cylinder which concerns on embodiment of this invention, and is the figure which shows the most extended state. It is an enlarged view which showed the part A of FIG. 1 enlarged, and is the figure for demonstrating a conventional problem. It is a figure for demonstrating the conventional problem, and is the figure which showed the state following FIG. 5A. It is a figure for demonstrating the conventional problem, and is the figure which showed the state following FIG. 5B. It is an enlarged view which showed the part B of FIG. 1 enlarged. It is a figure which shows the 1st modification of the fluid pressure cylinder which concerns on embodiment of this invention, and is the figure which shows the part corresponding to FIG. It is a figure which shows the 2nd modification of the fluid pressure cylinder which concerns on embodiment of this invention, and is the figure which shows the part corresponding to FIG. It is a figure which shows the 3rd modification of the fluid pressure cylinder which concerns on embodiment of this invention, and is the figure which shows the part corresponding to FIG. It is a figure which shows the 4th modification of the fluid pressure cylinder which concerns on embodiment of this invention, and is the figure which shows the part corresponding to FIG.

Hereinafter, the multi-stage fluid pressure cylinder 100 according to the embodiment of the present invention will be described with reference to the drawings. Hereinafter, a case where the multi-stage hydraulic cylinder 100 is a multi-stage hydraulic cylinder 100 (hereinafter, simply referred to as “hydraulic cylinder 100”) that drives the hydraulic oil as a working fluid will be described.

As shown in FIG. 1, the hydraulic cylinder 100 includes a bottomed cylinder-shaped cylinder tube 10, a first rod assembly 30 as an outer rod member slidably inserted inside the cylinder tube 10, and a first rod. A second rod assembly 40 as an inner rod member slidably inserted inside the assembly 30 in the central axial direction of the cylinder tube 10 (hereinafter, simply referred to as "axial direction"), and a second rod assembly 40. A third rod assembly 50 as a second inner rod member that is slidably inserted in the inner direction in the axial direction is provided. Note that FIG. 1 is a cross-sectional view showing a state in which the hydraulic cylinder 100 is most contracted.

The hydraulic cylinder 100 is connected to the cylinder tube via a first mounting portion 61 provided at the bottom of the cylinder tube 10 and a second mounting portion 62 provided at the end of the third rod assembly 50 protruding from the cylinder tube 10. 10 is located on the upper side in the vertical direction, and the third rod assembly 50 is located on the lower side in the vertical direction, and is attached to the device to be driven. That is, the hydraulic cylinder 100 is attached to the drive target device so that the first attachment portion 61 is displaced in the substantially vertical direction, that is, in the vertical direction with respect to the second attachment portion 62. The direction in which the hydraulic cylinder 100 is attached is not limited to this, and the cylinder tube 10 may be attached so as to be located on the lower side in the vertical direction and the third rod assembly 50 on the upper side in the vertical direction. Further, the hydraulic cylinder 100 may be mounted on the drive target device so that the first mounting portion 61 is displaced along the horizontal direction with respect to the second mounting portion 62.

The first rod assembly 30 slides along the inner peripheral surface 10a of the cylinder tube 10 provided at one end of the cylindrical outer rod portion 31 and the outer rod portion 31, and the inside of the cylinder tube 10 is opposite to the rod side chamber 2. A cylindrical first support that is formed so as to project radially inward from the other end of the outer rod portion 31 and the annular outer piston portion 32 that is partitioned into the rod side chamber 5 and slidably supports the second rod assembly 40. It has a portion 33 and.

An annular recess 30b to which the first snap ring 35 as a snap ring is mounted is formed on the inner peripheral surface 30a on the outer piston portion 32 side of the first rod assembly 30. The first snap ring 35 is a metal wire rod formed in a substantially annular shape and having a circular cross-sectional shape, and has a joint portion (not shown) which is partially divided. The first snap ring 35 is inserted into the first rod assembly 30 in a reduced diameter state, and its outer diameter side is pressed against the inner peripheral surface 30a by the elastic force acting in the diameter expansion direction and fitted into the annular recess 30b. Is done. In the state where the first snap ring 35 is assembled to the first rod assembly 30 in this way, the inner diameter side of the first snap ring 35 is in a state of protruding inward in the radial direction from the inner peripheral surface 30a of the first rod assembly 30. Become. The first snap ring 35 is attached after the second rod assembly 40 is inserted into the first rod assembly 30.

The second rod assembly 40 has the same shape as the first rod assembly 30, and has a cylindrical first inner rod portion 41 inserted into the outer rod portion 31 and one end portion of the first inner rod portion 41. The annular first inner piston portion 42 as an inner piston portion that slides along the inner peripheral surface 30a of the first rod assembly 30 and the other end of the first inner rod portion 41 project radially inward. It has a cylindrical second support portion 43, which is formed of the rod assembly 50 and slidably supports the third rod assembly 50.

A second annular recess 40b to which the second snap ring 45 is mounted is formed on the inner peripheral surface 40a on the first inner piston portion 42 side of the second rod assembly 40. Like the first snap ring 35, the second snap ring 45 is a metal wire rod formed in a substantially annular shape and having a circular cross-sectional shape, and has a joint portion (not shown) which is partially divided. The second snap ring 45 is inserted into the second rod assembly 40 in a reduced diameter state, and its outer diameter side is pressed against the inner peripheral surface 40a by the elastic force acting in the diameter expansion direction, and the second annular recess 40b is used. It is fitted in. In the state where the second snap ring 45 is assembled to the second rod assembly 40 in this way, the inner diameter side of the second snap ring 45 protrudes radially inward from the inner peripheral surface 40a of the second rod assembly 40. Become. The second snap ring 45 is attached after the third rod assembly 50 is inserted into the second rod assembly 40.

The third rod assembly 50 is coupled to a second inner rod portion 51 inserted into the first inner rod portion 41 and one end of the second inner rod portion 51, and is connected along the inner peripheral surface 40a of the second rod assembly 40. It has an annular second inner piston portion 52 that slides. The second inner rod portion 51 and the second inner piston portion 52 are connected via bolts (not shown).

In this way, three rod members of the first rod assembly 30, the second rod assembly 40, and the third rod assembly 50 are inserted into the cylinder tube 10.

A cylinder head 11 that slidably supports the outer rod portion 31 of the first rod assembly 30 is provided at the opening of the cylinder tube 10, and the cylinder tube 10 opposes the

piston portions

32, 42, 52 in the axial direction. A recess 10b recessed toward the first mounting portion 61 is formed in the bottom portion of the above. The inner diameter of the recess 10b is set to be larger than the inner diameter of the outer piston portion 32 of the first rod assembly 30.

The maximum contraction position of the first rod assembly 30 inserted into the cylinder tube 10 is defined by the outer piston portion 32 abutting on the bottom of the cylinder tube 10, and the maximum extension position is the maximum extension position of the outer piston portion 32 on the cylinder head 11. Specified by abutment. The inner peripheral surface of the cylinder head 11 is shown to seal a gap between the inner peripheral surface of the cylinder head 11 and the outer peripheral surface of the outer rod portion 31 in order to prevent leakage of hydraulic oil to the outside. No sealing member is provided.

The maximum contraction position of the second rod assembly 40 inserted into the first rod assembly 30 is defined by the contact of the first inner piston portion 42 with the first snap ring 35 mounted on the first rod assembly 30. The extension position is defined by the first inner piston portion 42 coming into contact with the first support portion 33. The first snap ring 35 limits the movement of the second rod assembly 40 in the contraction direction, and when the hydraulic cylinder 100 contracts, the first rod assembly 30 falls off from the cylinder tube 10. Is being prevented.

Further, on the inner peripheral surface of the first support portion 33, in order to prevent leakage of hydraulic oil to the outside, between the inner peripheral surface of the first support portion 33 and the outer peripheral surface of the first inner rod portion 41. A sealing member (not shown) for sealing the gap is provided.

The maximum contraction position of the third rod assembly 50 inserted into the second rod assembly 40 is defined by the contact of the second inner piston portion 52 with the second snap ring 45 mounted on the second rod assembly 40, and is the most defined. The extension position is defined by the second inner piston portion 52 coming into contact with the second support portion 43. The second snap ring 45 limits the movement of the third rod assembly 50 in the contraction direction, and when the hydraulic cylinder 100 contracts, the second rod assembly 40 falls off from the cylinder tube 10. Is being prevented.

Further, on the inner peripheral surface of the second support portion 43, in order to prevent leakage of hydraulic oil to the outside, between the inner peripheral surface of the second support portion 43 and the outer peripheral surface of the second inner rod portion 51. A sealing member (not shown) for sealing the gap is provided. Further, on the inner peripheral surface of the second support portion 43, an annular recess 43a facing the opening of the communication hole 51b described later formed in the second inner rod portion 51 when the third rod assembly 50 is most extended is formed. Will be done. The annular recess 43a is formed so as to open into the second inner rod side chamber 4, which will be described later.

Further, in the cylinder tube 10 into which the first rod assembly 30, the second rod assembly 40 and the third rod assembly 50 having the above shapes are inserted, the cylinder tube 10, the cylinder head 11, the outer rod portion 31 and the outer piston portion 32 are inserted. The rod side chamber 2 partitioned by, the first inner rod side chamber 3 partitioned by the outer rod portion 31, the first support portion 33, the first inner rod portion 41, and the first inner piston portion 42, and the first inner rod portion. 41, the second inner rod side chamber 4 partitioned by the second support portion 43, the second inner rod portion 51 and the second inner piston portion 52, the cylinder tube 10, the outer piston portion 32, the first inner piston portion 42 and the first. 2 The anti-rod side chamber 5 partitioned by the inner piston portion 52 is formed.

A first seal member 34 is provided on the outer peripheral surface 32a of the outer piston portion 32 of the first rod assembly 30, and is passed through a gap between the outer peripheral surface 32a of the outer piston portion 32 and the inner peripheral surface 10a of the cylinder tube 10. The communication between the rod side chamber 2 and the anti-rod side chamber 5 is blocked by the first seal member 34.

Further, in the outer piston portion 32 of the first rod assembly 30, a plurality of supply / discharge ports 32b for supplying / discharging hydraulic oil to / from the rod side chamber 2 are formed so as to penetrate in the radial direction.

A second seal member 44 is provided on the outer peripheral surface 42a of the first inner piston portion 42 of the second rod assembly 40, and the outer peripheral surface 42a of the first inner piston portion 42 and the inner peripheral surface 30a of the first rod assembly 30 are provided. The communication between the first inner rod side chamber 3 and the anti-rod side chamber 5 through the gap between them is blocked by the second seal member 44.

Further, in the first inner piston portion 42 of the second rod assembly 40, a plurality of inner supply / discharge ports 42b for supplying / discharging hydraulic oil to / from the first inner rod side chamber 3 are formed so as to penetrate in the radial direction. ..

A third seal member 54 is provided on the outer peripheral surface 52a of the second inner piston portion 52 of the third rod assembly 50, and the outer peripheral surface 52a of the second inner piston portion 52 and the inner peripheral surface 40a of the second rod assembly 40 are provided. The communication between the second inner rod side chamber 4 and the anti-rod side chamber 5 through the gap between them is blocked by the third seal member 54.

The second inner rod portion 51 of the third rod assembly 50 has a supply / discharge passage 51a connected to an external device (not shown) for supplying / discharging hydraulic oil to the hydraulic cylinder 100, a supply / discharge passage 51a, and a second inner rod. A communication hole 51b that communicates with the side chamber 4 is formed. Further, the second inner rod portion 51 is formed with a connection passage 51c for connecting the passage 64 formed in the second attachment portion 62 and the supply / discharge passage 51a.

The supply / discharge passage 51a communicates with the second inner rod side chamber 4 through the communication hole 51b and also communicates with the first inner rod side chamber 3 through the inner supply / discharge port 42b and the communication hole 51b, and the supply / discharge port 32b and the inner supply / discharge port. It communicates with the rod side chamber 2 through the 42b and the communication hole 51b.

That is, the hydraulic oil is supplied to the rod side chamber 2, the first inner rod side chamber 3 and the second inner rod side chamber 4, and the hydraulic oil is discharged from the rod side chamber 2, the first inner rod side chamber 3 and the second inner rod side chamber 4. Is performed through the supply / discharge passage 51a formed in the second inner rod portion 51.

Further, the second inner rod portion 51 is provided with a pipe-shaped supply / discharge pipe 55 connected to an external device for supplying / discharging hydraulic oil to the hydraulic cylinder 100. The supply / discharge pipe 55 is incorporated in the second inner rod portion 51 so that one end faces the anti-rod side chamber 5 and opens. 2 It is joined to the inner rod portion 51. Further, the second inner rod portion 51 is formed with a connection passage 51d for connecting the passage 63 formed in the second attachment portion 62 and the other end side of the supply / discharge pipe 55.

As described above, since one end of the supply / discharge pipe 55 is provided so as to open in the anti-rod side chamber 5, the supply of the hydraulic oil to the anti-rod side chamber 5 and the discharge of the hydraulic oil from the anti-rod side chamber 5 can be performed. It will be done through the supply / discharge pipe 55.

Next, the operation of the hydraulic cylinder 100 will be described with reference to FIGS. 1 to 4. In the following, the case where the hydraulic cylinder 100 is mounted on the drive target device so that the first mounting portion 61 is located on the upper side in the vertical direction and the second mounting portion 62 is located on the lower side in the vertical direction. explain.

When the hydraulic cylinder 100 is extended, hydraulic oil is supplied to the anti-rod side chamber 5 from a hydraulic source such as a pump (not shown) through the supply / discharge pipe 55, and the rod side chamber 2, the first inner rod side chamber 3, and the second inner rod are supplied. The hydraulic oil in the side chamber 4 is discharged to a tank (not shown) through the supply / discharge passage 51a.

When the hydraulic cylinder 100 extends from the maximum contracted state shown in FIG. 1, hydraulic oil is supplied to the anti-rod side chamber 5 through the supply / discharge pipe 55. Here, the pressure receiving area that receives the pressure of the anti-rod side chamber 5 is the largest when the first rod assembly 30 is extended, and is the smallest when the third rod assembly 50 is extended. Therefore, when the hydraulic cylinder 100 is extended from the most contracted state, the cylinder tube 10 first moves relative to the first rod assembly 30. Specifically, as shown in FIG. 2, the cylinder tube 10 moves upward (upper side in FIG. 2) with respect to the first rod assembly 30. Since the recess 10b formed in the bottom of the cylinder tube 10 has an inner diameter larger than the inner diameter of the outer piston portion 32 of the first rod assembly 30, the pressure of the hydraulic oil guided to the anti-rod side chamber 5 is the recess. It acts on the outer piston portion 32 through 10b.

When the cylinder tube 10 moves relative to the first rod assembly 30, the hydraulic oil in the rod side chamber 2 is guided to the outside by the supply / discharge passage 51a through the supply / discharge port 32b, the inner supply / discharge port 42b, and the communication hole 51b. It is discharged.

Then, as shown in FIG. 2, the cylinder tube 10 is in a state in which the cylinder tube 10 is most extended with respect to the first rod assembly 30, that is, the cylinder tube 10 is in contact with the outer piston portion 32 of the first rod assembly 30. After moving upward, the cylinder tube 10 and the first rod assembly 30 move relative to the second rod assembly 40 due to the pressure of the anti-rod side chamber 5. Specifically, as shown in FIG. 3, the cylinder tube 10 and the first rod assembly 30 move upward (upper side in FIG. 3) with respect to the second rod assembly 40.

When the first rod assembly 30 moves relative to the second rod assembly 40, the hydraulic oil in the first inner rod side chamber 3 is guided to the outside through the inner supply / discharge port 42b and the communication hole 51b to the supply / discharge passage 51a. It is discharged.

Then, as shown in FIG. 3, the state in which the first rod assembly 30 is most extended with respect to the second rod assembly 40, that is, the first support portion 33 of the first rod assembly 30 is the first of the second rod assembly 40. When the cylinder tube 10 and the first rod assembly 30 have moved upward until they come into contact with the inner piston portion 42, next, the pressure of the anti-rod side chamber 5 causes the cylinder tube 10 to the third rod assembly 50. The first rod assembly 30 and the second rod assembly 40 will move relative to each other. Specifically, as shown in FIG. 4, the cylinder tube 10, the first rod assembly 30, and the second rod assembly 40 move upward (upper side in FIG. 4) with respect to the third rod assembly 50.

When the second rod assembly 40 moves relative to the third rod assembly 50, the hydraulic oil in the second inner rod side chamber 4 is guided to the supply / discharge passage 51a through the communication hole 51b and discharged to the outside.

Then, as shown in FIG. 4, the state in which the second rod assembly 40 is most extended with respect to the third rod assembly 50, that is, the second support portion 43 of the second rod assembly 40 is the second of the third rod assembly 50. When the cylinder tube 10, the first rod assembly 30, and the second rod assembly 40 move upward until they come into contact with the inner piston portion 52, the hydraulic cylinder 100 is in the fully extended state.

On the other hand, when the hydraulic cylinder 100 contracts, hydraulic oil is supplied from the hydraulic source to the rod side chamber 2, the first inner rod side chamber 3 and the second inner rod side chamber 4 through the supply / discharge passage 51a, and the anti-rod side chamber 5 The hydraulic oil is discharged to the tank through the supply / discharge pipe 55. The contraction operation of the hydraulic cylinder 100 may be due to the own weight of the drive target device connected to the first mounting portion 61. In this case, it is not necessary to supply hydraulic oil to the rod side chamber 2, the first inner rod side chamber 3 and the second inner rod side chamber 4, and the rod side chamber 2, the first inner rod side chamber 3 and the second inner rod side chamber 4 do not need to be supplied with hydraulic oil. Hydraulic oil will be sucked from the tank.

When the hydraulic cylinder 100 contracts from the fully extended state, first, the cylinder tube 10, the first rod assembly 30, and the second rod assembly 30 are changed from the state shown in FIG. 4 to the state shown in FIG. 3 with respect to the third rod assembly 50. The rod assembly 40 moves relative to each other, and then the cylinder tube 10 and the first rod assembly 30 move relative to the second rod assembly 40 from the state shown in FIG. 3 to the state shown in FIG. Further, the cylinder tube 10 moves relative to the first rod assembly 30 from the state shown in FIG. 2 to the state shown in FIG. 1, so that the hydraulic cylinder 100 is in the most contracted state.

As shown in FIG. 5A, the first inner piston portion 42 of the second rod assembly 40 of the hydraulic cylinder 100 having the above configuration has an inner diameter side of the first snap ring 35 in a state where the second rod assembly 40 is most contracted. A storage recess 42c for housing is provided. The accommodating recess 42c regulates the deformation of the first snap ring 35 in the radial direction, and the first inner piston portion 42 comes into contact with the first snap ring 35 when the second rod assembly 40 contracts. This is provided to prevent the first snap ring 35 from coming off the first rod assembly 30. Note that FIG. 5A is an enlarged view showing a portion surrounded by a broken line indicated by an arrow A in FIG. 1 showing the hydraulic cylinder 100 in the most contracted state.

Further, as shown in FIG. 5A, in a state where the first snap ring 35 is accommodated in the accommodating recess 42c and the first snap ring 35 is in contact with the first inner piston portion 42, the first snap ring 35 is sandwiched between them. On the side opposite to the rod side chamber 5, a gap G1 defined by the outer peripheral surface 42a of the first inner piston portion 42, the inner peripheral surface 30a of the first rod assembly 30, and the first snap ring 35 is formed.

Here, when the hydraulic cylinder 100 having the above configuration is in the most contracted state and the hydraulic oil is not supplied or discharged to the rod side chamber 2 and the anti-rod side chamber 5, the hydraulic cylinder 100 is forcibly extended. When an external force suddenly acts, the pressure in the room decreases because the hydraulic oil is not supplied in the anti-rod side chamber 5 where the volume expands, while the hydraulic oil is not discharged in the rod side chamber 2 where the volume decreases. The pressure rises.

When the pressure in the rod side chamber 2 becomes high in this way, the first rod assembly 30 is displaced in the extension direction together with the cylinder tube 10, and the first rod assembly 30 is displaced relative to the second rod assembly 40. Therefore, as shown in FIG. 5B, the first snap ring 35 provided in the first rod assembly 30 is separated from the accommodating recess 42c of the first inner piston portion 42.

As shown in FIG. 5B, when the first snap ring 35 is instantaneously separated from the accommodating recess 42c, the outer peripheral surface 42a of the first inner piston portion 42, the inner peripheral surface 30a of the first rod assembly 30, and the first snap ring 35 Since the volume of the gap G1 defined by the above is rapidly increased, the pressure in the gap G1 becomes lower than that of the anti-rod side chamber 5, and from the anti-rod side chamber 5 as shown by the arrow F in FIG. 5B to the gap G1. A flow of hydraulic oil is generated.

Then, the flow of the hydraulic oil from the anti-rod side chamber 5 to the gap G1 passes through a slight gap between the radial inside of the first snap ring 35 and the accommodating recess 42c, so that the so-called Venturi effect causes the flow of the hydraulic oil. 1 The pressure on the inner diameter side of the snap ring 35 drops significantly.

When the pressure in the region facing the inner diameter side of the first snap ring 35 decreases in this way, the flow acts in the direction of reducing the diameter of the first snap ring 35 against the elastic force of the first snap ring 35 acting in the diameter expansion direction. As the physical force is generated on the inner diameter side of the first snap ring 35, the outer diameter of the first snap ring 35 becomes smaller, and as a result, as shown in FIG. 5C, the outer diameter side of the first snap ring 35 is separated from the annular recess 30b. , The first snap ring 35 may come off from the first rod assembly 30.

On the other hand, in the hydraulic cylinder 100 of the present embodiment, as shown in FIG. 6, the outer peripheral surface 42a of the first inner piston portion 42, the inner peripheral surface 30a of the first rod assembly 30, and the first snap ring 35 are used. Through

holes

32c and 42d as communication passages communicating the defined gap G1 and the anti-rod side chamber 5 are provided in the first rod assembly 30 and the second rod assembly 40, respectively.

The through hole 32c provided as a continuous passage in the first rod assembly 30 is a cutting hole formed so that one end opens in the anti-rod side chamber 5 and the other end opens in the gap G1. A plurality of outer piston portions 32 are provided at intervals in the circumferential direction.

Similar to the through hole 32c, the through hole 42d provided in the second rod assembly 40 as a continuous passage is a cutting hole formed so that one end opens in the anti-rod side chamber 5 and the other end opens in the gap G1. , A plurality of the first inner piston portions 42 of the second rod assembly 40 are provided at intervals in the circumferential direction.

By communicating the gap G1 and the anti-rod side chamber 5 through the through

holes

32c and 42d in this way, even if the volume of the gap G1 rapidly increases as described above, the gap G1 and the anti-rod side chamber 5 are communicated with each other. Since it is suppressed that the pressure difference with 5 becomes large, the flow of hydraulic oil passing through the radial inside of the first snap ring 35 and flowing from the anti-rod side chamber 5 to the gap G1 becomes small.

Further, the hydraulic oil flows into the gap G1 not only from the radial inside of the first snap ring 35 and the accommodating recess 42c, but also from the anti-rod side chamber 5 through the through

holes

32c and 42d. The degree of decrease in pressure in the gap G1 is alleviated, and the pressure in the region facing the inner diameter side of the first snap ring 35 is suppressed from being extremely reduced.

As a result, it is suppressed that a fluid force acting in the direction of reducing the diameter of the first snap ring 35 is generated on the inner diameter side of the first snap ring 35 against the elastic force of the first snap ring 35 acting in the diameter expansion direction. As a result, it is possible to prevent the first snap ring 35 from coming off from the first rod assembly 30.

The through

holes

32c and 42d are provided in the first rod assembly 30 and the second rod assembly 40, respectively, but are provided in only one of the first rod assembly 30 and the second rod assembly 40. May be good.

Further, not only the first snap ring 35 but also the second snap ring 45 whose outer diameter side is housed in the second annular recess 40b and whose inner diameter side is housed in the second storage recess 52b is detached from the second rod assembly 40. In order to prevent this, as shown in FIG. 6, a second gap G2 defined by an outer peripheral surface 52a of the second inner piston portion 52, an inner peripheral surface 40a of the second rod assembly 40, and a second snap ring 45, The third rod assembly 50 may be provided with a through hole 52c as a communication passage that communicates with the anti-rod side chamber 5.

The through hole 52c provided as a continuous passage in the third rod assembly 50 is a cutting hole formed so that one end opens in the anti-rod side chamber 5 and the other end opens in the second gap G2, and the third rod assembly is formed. A plurality of second inner piston portions 52 of 50 are provided at intervals in the circumferential direction. Not only the third rod assembly 50 but also the second rod assembly 40 may be formed with a through hole which is a communication passage for communicating the second gap G2 and the anti-rod side chamber 5.

According to the above embodiment, the following effects are obtained.

In the hydraulic cylinder 100 having the above configuration, the gap G1 defined by the outer peripheral surface 42a of the first inner piston portion 42, the inner peripheral surface 30a of the first rod assembly 30, and the first snap ring 35, the anti-rod side chamber 5, and so on. Through

holes

32c and 42d are provided in at least one of the first rod assembly 30 and the second rod assembly 40.

By communicating the gap G1 and the anti-rod side chamber 5 through the through

holes

32c and 42d in this way, the hydraulic cylinder 100 is forcibly extended when the hydraulic cylinder 100 is in the most contracted state. Even if an external force suddenly acts, the first rod assembly 30 is displaced in the extension direction together with the cylinder tube 10, the first snap ring 35 is instantly separated from the accommodating recess 42c, and the volume of the gap G1 rapidly increases. It is suppressed that the pressure difference between the gap G1 and the anti-rod side chamber 5 becomes large.

As a result, the degree of decrease in pressure in the gap G1 is alleviated, and the pressure in the region facing the inner diameter side of the first snap ring 35 is suppressed from being extremely reduced, so that the first snap ring acting in the diameter expansion direction acts. It is suppressed that a fluid force acting in a direction of reducing the diameter of the first snap ring 35 against the elastic force of the 35 is generated on the inner diameter side of the first snap ring 35. As a result, it is possible to prevent the first snap ring 35 from coming off from the first rod assembly 30.

The following modifications are also within the scope of the present invention, and the configurations shown in the modifications may be combined with the configurations described in the above-described embodiments, or the configurations described in the following different modifications may be combined. Is also possible.

In the above embodiment, the communication passage is a through

hole

32c, 42d in which one end opens in the anti-rod side chamber 5 and the other end opens in the gap G1. Instead of this, the communication passage has a notch groove 32d or a first notch groove 32d formed by notching the inner peripheral surface 30a of the first rod assembly 30 along the axial direction as in the first modification shown in FIG. It may be a notch groove 42e formed by notching the outer peripheral surface 42a of the inner piston portion 42 along the axial direction. Note that FIG. 7 is a diagram showing a modified example of the above embodiment, and is a diagram showing a portion corresponding to FIG.

The notch groove 32d provided as a continuous passage in the first rod assembly 30 has a width of a predetermined size in the circumferential direction of the outer piston portion 32, and has an annular recess from the end surface of the first rod assembly 30 facing the anti-rod side chamber 5. It is a groove formed along the axial direction beyond 30b, and is provided in a plurality of grooves on the outer piston portion 32 of the first rod assembly 30 at intervals in the circumferential direction. Further, the depth of the notch groove 32d from the inner peripheral surface 30a of the first rod assembly 30 is formed deeper than that of the annular recess 30b. As described above, in the cross-sectional view shown in FIG. 7, by forming the notch groove 32d so as to surround the annular recess 30b, the anti-rod side chamber 5 and the gap G1 are always communicated with each other through the notch groove 32d.

The cutout groove 32d may not be formed to reach the end surface of the first rod assembly 30 facing the anti-rod side chamber 5 in the axial direction as long as the anti-rod side chamber 5 and the gap G1 can be communicated with each other. In order to facilitate workability, it is preferable that the first rod assembly 30 is formed by opening at the end face thereof as described above.

The notch groove 42e provided as a continuous passage in the second rod assembly 40 has a width of a predetermined size in the circumferential direction of the first inner piston portion 42, and is from the end surface of the second rod assembly 40 facing the anti-rod side chamber 5. It is a groove formed along the axial direction beyond the accommodating recess 42c, and a plurality of grooves are provided in the first inner piston portion 42 of the second rod assembly 40 at intervals in the circumferential direction. Further, the notch groove 42e opens at the outer peripheral surface 42a of the first inner piston portion 42 and the inner peripheral surface 40a of the second rod assembly 40 in the radial direction. As described above, in the cross-sectional view shown in FIG. 7, by forming the notch groove 42e so as to surround the accommodating recess 42c, the anti-rod side chamber 5 and the gap G1 are always communicated with each other through the notch groove 42e. The cutout groove 42e does not have to reach the inner peripheral surface 40a of the second rod assembly 40 in the radial direction as long as the anti-rod side chamber 5 and the gap G1 can communicate with each other.

As described above, even in the first modification, the gap G1 and the anti-rod side chamber 5 communicate with each other through the

notch grooves

32d and 42e, so that the first snap ring 35 is disengaged from the first rod assembly 30 as in the above embodiment. It can be prevented.

Further, also in the first modification, in order to prevent not only the first snap ring 35 but also the second snap ring 45 provided in the second rod assembly 40 from coming off, the second gap G2 and the anti-rod side chamber The third rod assembly 50 may be provided with a notch groove 52d which is a communication passage communicating with 5.

The notch groove 52d provided as a continuous passage in the third rod assembly 50 has a width of a predetermined size in the circumferential direction of the second inner piston portion 52, and is from the end surface of the third rod assembly 50 facing the anti-rod side chamber 5. It is a groove formed along the axial direction beyond the second accommodating recess 52b, and a plurality of grooves are provided in the second inner piston portion 52 of the third rod assembly 50 at intervals in the circumferential direction. Not only the third rod assembly 50 but also the second rod assembly 40 may be formed with a notched groove for communicating the second gap G2 and the anti-rod side chamber 5.

Further, in the above embodiment, the communication passages are through

holes

32c and 42d newly formed for the first rod assembly 30. Instead of this, as in the second modification shown in FIG. 8, the communication passage has a screw hole 32e or a second snap ring 45 into which a jig is screwed when the first snap ring 35 is removed from the first rod assembly 30. The screw hole 42f into which the jig is screwed when the rod assembly 40 is removed from the second rod assembly 40 may be used. Note that FIG. 8 is a diagram showing a modified example of the above embodiment, and is a diagram showing a portion corresponding to FIG.

The screw hole 32e formed as a continuous passage in the first rod assembly 30 has an annular recess having one end opened on the outer peripheral surface 32a of the outer piston portion 32 and the other end formed on the inner peripheral surface 30a of the first rod assembly 30. It is a female screw hole formed by penetrating the first rod assembly 30 in the radial direction so as to open at 30b, and a plurality of female screw holes are provided in the outer piston portion 32 of the first rod assembly 30 at intervals in the circumferential direction. The size of the female screw inner diameter of the screw hole 32e is set to be larger than the wire diameter of the first snap ring 35, that is, the width of the annular recess 30b in the axial direction. Therefore, the open end of the screw hole 32e opened on the inner peripheral surface 30a of the first rod assembly 30 is divided into two by the first snap ring 35 accommodated in the annular recess 30b, and one of them becomes the anti-rod side chamber 5. The other will open in the gap G1. Therefore, the anti-rod side chamber 5 and the gap G1 are always in communication with each other through the inside of the screw hole 32e.

The screw hole 42f formed as a communication passage in the second rod assembly 40 has one end opened on the outer peripheral surface 42a of the first inner piston portion 42 and the other end formed on the inner peripheral surface 40a of the second rod assembly 40. It is a female screw hole formed by penetrating the second rod assembly 40 in the radial direction so as to open in the second annular recess 40b, and is spaced apart from the first inner piston portion 42 of the second rod assembly 40 in the circumferential direction. Multiple installations are provided. The size of the female screw inner diameter of the screw hole 42f is set to be larger than the wire diameter of the second snap ring 45, that is, the width of the second annular recess 40b in the axial direction. Therefore, the open end of the screw hole 42f opened on the inner peripheral surface 40a of the second rod assembly 40 is divided into two by the second snap ring 45 accommodated in the second annular recess 40b, and one of them is the anti-rod side chamber. It opens at 5 and the other opens at the second gap G2. Since the screw hole 42f is also open on the outer peripheral surface 42a of the first inner piston portion 42 that defines the gap G1, the anti-rod side chamber 5 and the gap G1 are always in a state of being constantly passed through the inside of the screw hole 42f. Will be.

As described above, even in the second modification, the gap G1 and the anti-rod side chamber 5 communicate with each other through the screw holes 32e and 42f, so that the first snap ring 35 is disengaged from the first rod assembly 30 as in the above embodiment. It can be prevented. Further, by using the holes used for removing the snap rings 35 and 45 as the connecting passages such as the screw holes 32e and 42f, the manufacturing cost of the hydraulic cylinder 100 is reduced as compared with the case where the connecting passages are separately formed. can do.

Further, in the second modification, since the anti-rod side chamber 5 and the second gap G2 are always communicated with each other through the inside of the screw hole 42f, the second rod assembly 40 is provided as well as the first snap ring 35. 2 It is also possible to prevent the snap ring 45 from coming off.

In the second modification, the holes formed as the communication passages are the screw holes 32e and 42f, but instead of this, the communication passage has a size capable of communicating the gap G1 and the anti-rod side chamber 5. It may be a simple through hole having an inner diameter of a screw.

Specifically, when a through hole is provided in the first rod assembly 30 instead of the screw hole 32e, the size of the inner diameter of the through hole is the wire diameter of the first snap ring 35, that is, the annular recess 30b in the axial direction. It is set larger than the width. When a through hole is provided in the second rod assembly 40 instead of the screw hole 42f, the size of the inner diameter of the through hole is the wire diameter of the second snap ring 45, that is, the width of the second annular recess 40b in the axial direction. Is set larger than.

Such a through hole can be formed in any direction as long as one end is opened on the outer peripheral surface 32a and the other end is opened on the annular recess 30b, but the jig for removing the snap rings 35 and 45 can be formed. When a through hole is used as the insertion hole, it is preferable that the through hole is formed orthogonal to the axial direction and along the radial direction.

Further, in the above embodiment, the communication passage provided in the first rod assembly 30 is a single through hole 32c formed in the first rod assembly 30. Instead of this, the communication passage may be composed of a plurality of communication passages (32f, 32g) formed on the first rod assembly 30 as in the third modification shown in FIG. Note that FIG. 9 is a diagram showing a modified example of the above embodiment, and is a diagram showing a portion corresponding to FIG.

The through hole 32f provided as a continuous passage in the first rod assembly 30 is a cutting hole formed so that one end is opened on the outer peripheral surface 32a of the outer piston portion 32 and the other end is opened in the gap G1. A plurality of rod assemblies 30 are provided on the outer piston portion 32 at intervals in the circumferential direction. Further, the notch groove 32g provided as a continuous passage in the first rod assembly 30 is a groove formed on the end surface of the first rod assembly 30 facing the anti-rod side chamber 5, and is outside along the radial direction of the outer piston portion 32. It is formed up to the outer peripheral surface 32a of the piston portion 32. A plurality of notch grooves 32g are provided in the outer piston portion 32 of the first rod assembly 30 at intervals in the circumferential direction.

The through hole 32f and the notch groove 32g thus formed are gapped with the anti-rod side chamber 5 through the third gap G3 defined by the outer peripheral surface 32a of the outer piston portion 32 and the inner peripheral surface 10a of the cylinder tube 10. It will be a communication passage that always communicates with G1. As described above, even in the third modification, the gap G1 and the anti-rod side chamber 5 communicate with each other through the through hole 32f and the notch groove 32g. Therefore, as in the above embodiment, the first rod assembly 30 to the first snap ring It is possible to prevent the 35 from coming off.

Further, in the above embodiment, the communication passage provided in the first rod assembly 30 always communicates the anti-rod side chamber 5 and the gap G1. Instead, the communication passage is provided when the cylinder tube 10 moves slightly relative to the first rod assembly 30, that is, the inner peripheral surface 10a of the cylinder tube 10, as in the fourth modification shown in FIG. When the end surface 30c of the first rod assembly 30 that abuts on the stepped portion 10c formed between the recessed portion 10b and the recessed portion 10b is slightly separated from the stepped portion 10c, the anti-rod side chamber 5 and the gap G1 communicate with each other. May be good. Note that FIG. 10 is a diagram showing a modified example of the above embodiment, and is a diagram showing a portion corresponding to FIG.

The through hole 32h provided as a continuous passage in the first rod assembly 30 is a cutting hole formed so that one end opens on the outer peripheral surface 32a of the outer piston portion 32 and the other end opens in the gap G1. A plurality of rod assemblies 30 are provided on the outer piston portion 32 at intervals in the circumferential direction.

The through hole 32h formed in this way has the end face 30c and the step portion when the cylinder tube 10 moves relative to the first rod assembly 30 and the end surface 30c of the first rod assembly 30 is separated from the step portion 10c. The gap G1 is communicated with the third gap G3 as a fluid chamber communicating with the anti-rod side chamber 5 through the gap formed between the 10c and the 10c. That is, the through hole 32h has a gap formed between the end surface 30c and the step portion 10c, and a third gap G3 defined by the outer peripheral surface 32a of the outer piston portion 32 and the inner peripheral surface 10a of the cylinder tube 10. , The anti-rod side chamber 5 and the gap G1 are communicated with each other.

As described above, even in the fourth modification, the gap G1 and the anti-rod side chamber 5 communicate with each other through the through hole 32h, so that the first snap ring 35 can be removed from the first rod assembly 30 as in the above embodiment. Can be prevented.

Further, in the above embodiment, the cross-sectional shape of each

snap ring

35, 45 is circular. The cross-sectional shape of each of the snap rings 35 and 45 is not limited to a circular shape, and may be an elliptical shape or a rectangular shape.

Further, in the above embodiment, the hydraulic cylinder 100 is provided with three rod members (first rod assembly 30, second rod assembly 40, third rod assembly 50) overlapping in the cylinder tube 10 in the radial direction. It is a step type hydraulic cylinder 100. On the other hand, the hydraulic cylinder 100 may be a two-stage type in which two rod members are radially overlapped in the cylinder tube 10, or four or more rod members are radially overlapped. It may be provided in the above.

Hereinafter, the configurations, actions, and effects of the embodiments of the present invention will be collectively described.

The hydraulic cylinder 100 is provided with a cylinder tube 10 and an outer piston portion 32 at the end, which slides along the inner peripheral surface 10a of the cylinder tube 10 and divides the inside of the cylinder tube 10 into a rod side chamber 2 and an anti-rod side chamber 5. A cylindrical first rod assembly 30 and a second rod assembly 40 provided with a first inner piston portion 42 sliding along an inner peripheral surface 30a of the first rod assembly 30 at the end thereof, and a first rod assembly 40. The first inner piston portion 42 is provided with a snap ring 35 whose outer diameter side is accommodated in the annular recess 30b formed on the inner peripheral surface 30a of the rod assembly 30 and restricts the movement of the second rod assembly 40 in the contraction direction. Is provided with a housing recess 42c for accommodating the inner diameter side of the snap ring 35 when the second rod assembly 40 contracts, and the snap ring 35 is accommodated in at least one of the first rod assembly 30 and the second rod assembly 40. A gap G1 defined by the outer peripheral surface 42a of the snap ring 35, the first inner piston portion 42, and the inner peripheral surface 30a of the first rod assembly 30 in a state of being housed in the recess 42c and in contact with the first inner piston portion 42. (32c, 32d, 32e, 32f, 32g) that communicates with the third gap G3 that communicates with the anti-rod side chamber 5 by the cylinder tube 10 moving relative to the anti-rod side chamber 5 or the first rod assembly 30. , 32h, 42d, 42e, 42f).

In this configuration, the gap G1 defined by the outer peripheral surface 42a of the first inner piston portion 42, the inner peripheral surface 30a of the first rod assembly 30, and the first snap ring 35, and the anti-rod side chamber 5 or the anti-rod side chamber 5 Communication passages (32c, 32d, 32e, 32f, 32g, 32h, 42d, 42e, 42f) communicating with the third gap G3 to communicate with are provided on at least one of the first rod assembly 30 and the second rod assembly 40. Has been done.

In this way, the gap G1 and the anti-rod side chamber 5 are communicated with each other through a communication passage (32c, 32d, 32e, 32f, 32g, 42d, 42e, 42f), or the cylinder tube is connected to the first rod assembly 30. By communicating the third gap G3 and the gap G1 that communicate with the anti-rod side chamber 5 through the communication passage (32h) by the relative movement of the 10, the hydraulic pressure is applied when the hydraulic cylinder 100 is in the most contracted state. An external force that forcibly extends the cylinder 100 acts suddenly, the first rod assembly 30 is displaced together with the cylinder tube 10 in the extension direction, the first snap ring 35 is instantly separated from the accommodating recess 42c, and the gap G1. Even if the volume of the cylinder increases rapidly, it is suppressed that the pressure difference between the gap G1 and the anti-rod side chamber 5 increases.

Further, the communication passages are through

holes

32c and 42d formed in at least one of the first rod assembly 30 and the second rod assembly 40, and the through

holes

32c and 42d have one end opened in the anti-rod side chamber 5 and the other. The end opens in the gap G1.

In this configuration, the communication passage is a through

hole

32c, 42d formed so that one end opens in the anti-rod side chamber 5 and the other end opens in the gap G1. By using the through

holes

32c and 42d that can be easily formed in the first rod assembly 30 and the second rod assembly 40 as a communication passage for communicating the gap G1 and the anti-rod side chamber 5, the hydraulic cylinder It is possible to prevent the first snap ring 35 from coming off from the first rod assembly 30 without increasing the manufacturing cost of 100 so much.

Further, the continuous passage is a

notch groove

32d, 42e cut out along the axial direction in at least one of the inner peripheral surface 30a of the first rod assembly 30 and the outer peripheral surface 42a of the first inner piston portion 42.

In this configuration, the communication passages are notched

grooves

32d and 42e cut out along the axial direction in the inner peripheral surface 30a of the first rod assembly 30 and the outer peripheral surface 42a of the first inner piston portion 42. By using the notched

grooves

32d and 42e that can be easily formed in the first rod assembly 30 and the second rod assembly 40 as a communication passage for communicating the gap G1 and the anti-rod side chamber 5, the hydraulic cylinder It is possible to prevent the first snap ring 35 from coming off from the first rod assembly 30 without significantly increasing the manufacturing cost of the 100.

Further, the

notch grooves

32d and 42e are formed along the axial direction from at least one of the end face of the first rod assembly 30 and the end face of the second rod assembly 40 facing the anti-rod side chamber 5.

In this configuration, the

notch grooves

32d and 42e are formed along the axial direction from the end face of the first rod assembly 30 facing the anti-rod side chamber 5 and the end face of the second rod assembly 40. By forming

notch grooves

32d and 42e along the axial direction from the end surface of the first rod assembly 30 facing the anti-rod side chamber 5 and the end surface of the second rod assembly 40 in this way, the gap G1 and the anti-rod side chamber 5 are communicated with each other. Possible communication paths can be easily formed.

Further, the communication passage is a screw hole 32e in which one end is opened in the outer peripheral surface 32a of the outer piston portion 32 and the other end is opened in the annular recess 30b, and the female screw inner diameter of the screw hole 32e is the wire diameter of the snap ring 35. Greater than.

In this configuration, the communication passage is a screw hole 32e in which one end is opened in the outer peripheral surface 32a of the outer piston portion 32 and the other end is opened in the annular recess 30b. By using the screw hole 32e into which the jig is screwed when removing the snap ring 35 from the annular recess 30b as a continuous passage, the first rod assembly 30 to the first rod assembly 30 can be used without increasing the manufacturing cost of the hydraulic cylinder 100. 1 It is possible to prevent the snap ring 35 from coming off.

Further, the hydraulic cylinder 100 includes a third rod assembly 50 provided with a second inner piston portion 52 at the end thereof that slides along the inner peripheral surface 40a of the second rod assembly 40, and a second rod assembly 40. The second annular recess 40b formed on the peripheral surface 40a further includes a second snap ring 45 whose outer diameter side is accommodated and restricts the movement of the third rod assembly 50 in the contraction direction. 1 The screw hole 42f that opens on the outer peripheral surface 42a of the inner piston portion 42 and the other end opens in the second annular recess 40b, and the female screw inner diameter of the screw hole 42f is larger than the wire diameter of the second snap ring 45. ..

In this configuration, the communication passage is a screw hole 42f in which one end is opened in the outer peripheral surface 42a of the first inner piston portion 42 and the other end is opened in the second annular recess 40b. By using the screw hole 42f into which the jig is screwed when removing the second snap ring 45 from the second annular recess 40b as a continuous passage in this way, the first rod does not increase the manufacturing cost of the hydraulic cylinder 100. It is possible to prevent the first snap ring 35 from coming off from the assembly 30.

Although the embodiments of the present invention have been described above, the above embodiments are only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiments. do not have.

This application claims priority based on Japanese Patent Application No. 2020-141111 filed with the Japan Patent Office on August 24, 2020, and the entire contents of this application are incorporated herein by reference.

Claims

It is a multi-stage fluid pressure cylinder.
Cylinder tube and
A cylindrical outer rod member having an outer piston portion at the end that slides along the inner peripheral surface of the cylinder tube and divides the inside of the cylinder tube into a rod side chamber and an anti-rod side chamber.
An inner rod member having an inner piston portion that slides along the inner peripheral surface of the outer rod member at an end thereof, and an inner rod member.
The outer diameter side is accommodated in the annular recess formed on the inner peripheral surface of the outer rod member, and a snap ring that limits the movement of the inner rod member in the contraction direction is provided.
The inner piston portion is provided with a housing recess for accommodating the inner diameter side of the snap ring when the inner rod member contracts.
The snap ring, the outer peripheral surface of the inner piston portion, and the outer side of the snap ring, the outer peripheral surface of the inner piston portion, and the outer side of the inner rod member in a state where the snap ring is accommodated in the accommodating recess and is in contact with the inner piston portion in at least one of the outer rod member and the inner rod member. A communication passage that allows the gap defined by the inner peripheral surface of the rod member to communicate with the anti-rod side chamber or the fluid chamber communicating with the anti-rod side chamber by the relative movement of the cylinder tube with respect to the anti-rod side chamber or the outer rod member. A multi-stage fluid pressure cylinder provided with.
The multi-stage fluid pressure cylinder according to claim 1.
The communication passage is a through hole formed in at least one of the outer rod member and the inner rod member.
The through hole is a multi-stage fluid pressure cylinder in which one end opens in the anti-rod side chamber and the other end opens in the gap.
The multi-stage fluid pressure cylinder according to claim 1.
The communication passage is a multi-stage fluid pressure cylinder which is a notched groove cut along the axial direction in at least one of the inner peripheral surface of the outer rod member and the outer peripheral surface of the inner piston portion.
The multi-stage fluid pressure cylinder according to claim 3.
The notch groove is a multi-stage fluid pressure cylinder formed along the axial direction from at least one of the end surface of the outer rod member and the end surface of the inner rod member facing the anti-rod side chamber.
The multi-stage fluid pressure cylinder according to claim 1.
The communication passage is a screw hole having one end opened in the outer peripheral surface of the outer piston portion and the other end opening in the annular recess.
A multi-stage fluid pressure cylinder in which the inner diameter of the female screw of the screw hole is larger than the wire diameter of the snap ring.
The multi-stage fluid pressure cylinder according to claim 1.
A second inner rod member provided with a second inner piston portion that slides along the inner peripheral surface of the inner rod member at an end portion, and a second inner rod member.
A second snap ring whose outer diameter side is accommodated in the second annular recess formed on the inner peripheral surface of the inner rod member and restricts the movement of the second inner rod member in the contraction direction is further provided.
The communication passage is a screw hole having one end opened in the outer peripheral surface of the inner piston portion and the other end opening in the second annular recess.
The female screw inner diameter of the screw hole is a multi-stage fluid pressure cylinder larger than the wire diameter of the second snap ring.