WO2014054505A1

WO2014054505A1 - Hydraulic cylinder

Info

Publication number: WO2014054505A1
Application number: PCT/JP2013/076142
Authority: WO
Inventors: 和正兼松
Original assignee: Ｋｙｂエンジニアリングアンドサービス株式会社
Priority date: 2012-10-04
Filing date: 2013-09-26
Publication date: 2014-04-10
Also published as: CN104704248A; CN104704248B; KR20150047610A; KR101790852B1; JP6166881B2; JP2014074460A

Abstract

A single-acting hydraulic cylinder (1) is retracted by the pressure of operating liquid guided from a hydraulic pressure source to a rod-side chamber (6) which is one of the rod-side chamber (6) and a bottom-side chamber (5), which are separated by a piston (40). The single-acting hydraulic cylinder (1) is provided with: a cylinder tube (10) in which the piston (40) is received in a slidable manner and which has therein the rod-side chamber (6) and the bottom-side chamber (5); a piston rod (20) which is connected to the piston (40) and which protrudes to the outside from the cylinder tube (10); a tank chamber (7) which connects to the bottom-side chamber (5); a filling port (26) which is used to fill the bottom-side chamber (5) or the tank chamber (7) with a lubricating liquid from the outside; and a sealing section (14) for sealing the filling port (26).

Description

Hydraulic cylinder

The present invention relates to a single-acting hydraulic cylinder that is contracted by a pressurized hydraulic fluid introduced from an external hydraulic pressure source.

As a hydraulic cylinder disclosed in JP08-135609A as this type of single-acting hydraulic cylinder, the inside of the cylinder is partitioned into a second oil chamber and an air chamber by a main piston.

The second oil chamber is communicated with an external hydraulic pressure source via a pipe. The hydraulic cylinder contracts when the pressure of the hydraulic fluid guided to the second oil chamber is increased, while the hydraulic cylinder expands by an external force such as a spring when the pressure of the hydraulic fluid decreases.

The air chamber communicates with the outside through an air hole. During expansion and contraction of the hydraulic cylinder, outside air enters and exits the air chamber through the air hole.

In the hydraulic cylinder disclosed in JP08-135609A, since the air chamber communicates with the outside through the air hole, when the operation stop state continues for a long period of time, the air chamber dries and the air chamber operates. The liquid may be depleted. When the hydraulic fluid in the air chamber is depleted, internal rusting occurs, and the piston seal interposed in the main piston adheres to and adheres to the inner wall surface of the cylinder. When the piston seal sticks to the inner wall surface of the cylinder, there is a problem that the piston seal is deformed during re-operation and the sealing performance of the piston seal is impaired.

An object of the present invention is to prevent internal rusting and prevent a piston seal from adhering to and sticking to an inner wall surface of a cylinder tube in a single-acting hydraulic cylinder.

According to an aspect of the present invention, there is provided a single-acting hydraulic cylinder that is contracted and operated by pressure of hydraulic fluid guided from a hydraulic pressure source to a rod-side chamber among a rod-side chamber and a bottom-side chamber that are partitioned by a piston. A cylindrical cylinder tube that is slidably housed and has a bottom side chamber and a rod side chamber inside, a piston seal that is interposed in the piston and that is in sliding contact with the inner wall surface of the cylinder tube, and is connected to the piston and is connected to the outside from the cylinder tube. A piston rod protruding to the bottom, a tank chamber communicating with the bottom side chamber, a filling port for filling the bottom side chamber or the tank chamber with the lubricating liquid from the outside, and a sealing portion for sealing the filling port.

FIG. 1 is a cross-sectional view of a hydraulic cylinder according to a first embodiment of the present invention. FIG. 2 is a sectional view of a hydraulic cylinder according to a second embodiment of the present invention. FIG. 3 is a cross-sectional view of a hydraulic cylinder according to a third embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
A hydraulic cylinder (hydraulic cylinder) 1 shown in FIG. 1 is mounted on, for example, a work vehicle (not shown) for mowing, and is used as an actuator for raising and lowering a mowing machine (mowing rotor). In addition, it can utilize not only the actuator mounted in a work vehicle but the actuator provided in another machine and installation.

A mechanism (not shown) for raising and lowering the mower includes a vehicle body side arm connected to the vehicle body, a mower side arm rotatably connected to the vehicle body side arm to support the mower, and a mower side in the rotational direction in which the mower moves down. A spring 2 that biases the arm and a hydraulic cylinder 1 that drives the mower side arm in the rotational direction in which the mower moves up are provided.

The hydraulic cylinder 1 is connected between the vehicle body side arm and the mower side arm of the work vehicle. As the hydraulic cylinder 1 expands and contracts, the mower-side arm rotates and the mower moves up and down.

Hereinafter, the configuration of the hydraulic cylinder 1 will be described. The hydraulic cylinder 1 is a single-acting type that is contracted by the pressure of hydraulic fluid introduced from an external hydraulic pressure source, and is expanded by the spring force (external force) of the spring 2 when the pressure of the hydraulic fluid decreases. .

The hydraulic cylinder 1 includes a cylindrical cylinder tube 10 in which a piston 40 is slidably accommodated, and a piston rod 20 that protrudes from the cylinder tube 10 to the outside.

The bottom block 50 is coupled to one end of the cylinder tube 10. The bottom block 50 has an eye bracket portion 51 and is connected to the vehicle body side arm via a pin (not shown) inserted into the eye bracket portion 51.

The other end of the cylinder tube 10 is fitted with an annular cylinder head 60, and the piston rod 20 is slidably supported by the cylinder head 60.

An eye bracket portion 21 is formed at the tip of the piston rod 20. The piston rod 20 is connected to the mower arm via a pin (not shown) inserted into the eye bracket portion 21.

The piston 40 is fastened to the base end portion of the piston rod 20 inserted into the cylinder tube 10 via a nut 49. An O-ring 8 is interposed between the outer periphery of the proximal end of the piston rod 20 and the inner periphery of the piston 40. The O-ring 8 seals between the piston rod 20 and the piston 40.

The space inside the cylinder tube 10 is divided into a rod side chamber 6 and a bottom side chamber 5 by a piston 40. The rod side chamber 6 is a space between the cylinder tube 10 and the piston rod 20, and is defined between the piston 40 and the cylinder head 60. The bottom chamber 5 is a space inside the cylinder tube 10 and is defined between the piston 40 and the bottom block 50.

The cylinder tube 10 is formed of a metal such as steel.

A piston seal 41 is interposed on the outer periphery of the piston 40. When the piston seal 41 contacts the inner wall surface 11 of the cylinder tube 10, the space between the bottom side chamber 5 and the rod side chamber 6 is sealed.

The piston seal 41 is formed of a low friction resin material, but is not limited thereto, and a rubber O-ring or the like may be used.

A cylindrical bush (bearing) 61 is interposed on the inner periphery of the cylinder head 60. The piston rod 20 is slidably supported by the cylinder head 60 by the bush 61.

The main seal 62 and the dust seal 63 that are in sliding contact with the outer peripheral surface of the piston rod 20 are interposed on the inner periphery of the cylinder head 60. The main seal 62 seals between the cylinder head 60 and the piston rod 20, and the rod side chamber 6 is sealed from the outside. Further, the dust seal 63 prevents intrusion of dust and the like.

An annular port block 30 is joined to the outer periphery of the cylinder tube 10 in the middle in the axial direction by a weld 31. The port block 30 is formed with a supply / discharge port 32 for supplying / discharging the hydraulic fluid to / from the rod side chamber 6. A piping extending from a hydraulic pressure source (not shown) mounted on the work vehicle is connected to the supply / discharge port 32. The hydraulic fluid supplied and discharged by the hydraulic pressure source enters and exits the supply / discharge port 32 as indicated by arrows in the figure.

A cylindrical outer tube 35 is stretched between the port block 30 and the cylinder head 60. A supply / discharge passage 33 is defined as a cylindrical space between the outer tube 35 and the cylinder tube 10.

When the hydraulic fluid pressure led from the hydraulic pressure source rises, the hydraulic fluid passes from the supply / discharge port 32 through the supply / discharge passage 33 as shown by an arrow in the figure, and from the through hole 12 formed in the cylinder tube 10 to the rod side chamber 6. Supplied. Due to this hydraulic pressure, the piston rod 20 moves to the right in the drawing along the central axis O with respect to the cylinder tube 10, and the hydraulic cylinder 1 contracts. FIG. 1 shows a state where the hydraulic cylinder 1 is most contracted.

On the other hand, when the hydraulic pressure introduced from the hydraulic pressure source decreases, the piston rod 20 moves to the left in the drawing with respect to the cylinder tube 10 based on the urging force of the spring 2, and the hydraulic cylinder 1 extends. During the extension operation, the hydraulic fluid in the rod side chamber 6 is discharged to the hydraulic pressure source through the through hole 12, the supply / discharge passage 33, and the supply / discharge port 32, as indicated by arrows in the figure.

In the hydraulic cylinder 1, oil is used as the hydraulic fluid supplied and discharged from the hydraulic pressure source, but hydraulic fluid such as a water-soluble alternative fluid may be used instead of the oil.

One end of the outer tube 35 is fitted into the port block 30 and joined by the welded portion 34. The other end of the outer tube 35 is screwed into and coupled to the outer peripheral thread portion of the cylinder head 60.

O-ring 64 is interposed between the outer tube 35 and the cylinder head 60. The O-ring 64 seals between the outer tube 35 and the cylinder head 60, and the supply / discharge passage 33 is sealed from the outside.

A spiral spring engaging groove 36 is formed on the outer periphery of the outer tube 35. The spring 2 is formed in a coil shape, and one end of the spring 2 is connected to the outer tube 35 by being wound around a spiral spring engaging groove 36. The other end of the spring 2 is connected to the tip end side of the piston rod 20. The spring 2 urges the piston rod 20 in a direction to protrude from the cylinder tube 10 by the spring force.

The hydraulic cylinder 1 includes a tank tube 25 arranged around the cylinder tube 10 between the port block 30 and the bottom block 50. A tank chamber 7 is provided between the cylinder tube 10 and the tank tube 25.

The cylinder tube 10 is formed with a through hole 13 that communicates the bottom side chamber 5 and the tank chamber 7. As shown in FIG. 1, the through-hole 13 opens at a position where the piston rod 20 is not blocked by the piston 40 even when the piston rod 20 is at the stroke end and the hydraulic cylinder 1 is contracted most.

The tank chamber 7 is defined as a cylindrical space between the tank tube 25 and the cylinder tube 10. The bottom block 50 and the port block 30 serve as annular wall portions that define both axial ends of the tank chamber 7.

The volume ratio between the tank chamber 7 and the bottom side chamber 5 is arbitrarily set according to the allowable value of the pressure generated in the bottom side chamber 5 when the hydraulic cylinder 1 is expanded and contracted. The volume of the tank chamber 7 is determined by the inner diameter of the tank tube 25.

The bottom block 50 has an eye bracket part 51 connected to the vehicle body side arm and an annular flange part 52 protruding from around the eye bracket part 51.

A fitting recess 53 is formed at the center position in the radial direction on the end surface of the flange portion 52 of the bottom block 50. The cylinder tube 10 is fitted and fixed in the fitting recess 53.

A fitting recess 54 is formed on the end surface of the flange portion 52 of the bottom block 50 at the radially outer position. One end of the tank tube 25 is fitted into the fitting recess 54, and is joined by the weld 43. The other end of the tank tube 25 is fitted into a fitting recess 39 formed in the port block 30 and joined by a welded portion 42.

The hydraulic cylinder 1 includes a filling port 26 that passes through the tank tube 25 and opens into the tank chamber 7, and a sealing portion 14 that seals the filling port 26.

The sealing portion 14 includes a filling tube 15 coupled to the outer periphery of the tank tube 25 via a welding portion 16, a set screw 17 screwed into the filling tube 15, and a taper-shaped inner portion of the filling tube 15 by the set screw 17. And a ball 18 pressed against the peripheral surface. The filling tube 15 is formed with an air vent hole 19 that opens between the set screw 17 and the ball 18. The sealing unit 14 is not limited to the configuration described above, and may be a drain plug (plug) that is screwed into the filling port 26 of the tank tube 25, for example.

When the hydraulic cylinder 1 is manufactured, the tank chamber 7 is filled with a predetermined amount of lubricating liquid from the filling port 26. As this lubricating liquid, the same oil as the hydraulic fluid supplied to and discharged from the hydraulic pressure source to the hydraulic cylinder 1 is used. The lubricating liquid is not limited to this, and a lubricating liquid different from the working liquid may be used.

The manufactured hydraulic cylinder 1 is assembled together with the spring 2 between the vehicle body side arm and the mower side arm of the work vehicle.

When the hydraulic cylinder 1 is in the most contracted state shown in FIG. 1 during operation of the work vehicle, the mower-side arm rotates upward and the mower is held at the raised position.

When the hydraulic cylinder 1 is extended to bring the mower closer to the ground, the hydraulic pressure guided from the hydraulic pressure source to the rod side chamber 6 of the hydraulic cylinder 1 is lowered by the operation of the driver. As a result, the hydraulic cylinder 1 is extended by the spring force of the spring 2, and the hydraulic fluid in the rod side chamber 6 flows out to the hydraulic pressure source through the through hole 12, the supply / discharge passage 33 and the supply / discharge port 32.

Note that the hydraulic cylinder 1 is not limited to the spring force of the spring 2, and may be configured to extend by an external force such as gravity applied to the mower-side arm. When the gravity applied to the mower side arm is large, the spring force of the spring 2 may be configured to bias the mower side arm so as to rotate in the direction in which the mower moves up.

When the hydraulic cylinder 1 is contracted to move the mower away from the ground, the hydraulic fluid pressure guided from the hydraulic pressure source to the hydraulic cylinder 1 is increased by the driver's operation. As a result, the hydraulic fluid flows into the rod side chamber 6 through the supply / discharge port 32, the supply / discharge passage 33, and the through hole 12, and the hydraulic cylinder 1 contracts against the spring force of the spring 2.

Thus, when the hydraulic cylinder 1 expands and contracts, the lubricating liquid interposed in the bottom chamber 5 lubricates the sliding contact portion between the piston 40 and the inner wall surface 11 of the cylinder tube 10. Thereby, the piston 40 slides smoothly.

Since the bottom side chamber 5 is also sealed to the outside by the sealing portion 14, the pressure of the bottom side chamber 5 rises and falls as the piston 40 slides and the volume of the bottom side chamber 5 expands and contracts. Since the bottom side chamber 5 communicates with the tank chamber 7 through the through hole 13, the gas in the bottom side chamber 5 enters and exits the tank chamber 7 as the volume of the bottom side chamber 5 expands and contracts. For this reason, the pressure fluctuation produced in the bottom side chamber 5 is relieved. As a result, the hydraulic cylinder 1 is restrained from increasing the negative pressure generated in the bottom side chamber 5 during the extension operation, and can be smoothly extended by the spring force of the spring 2. Further, the hydraulic cylinder 1 is restrained from increasing the positive pressure generated in the bottom side chamber 5 during the contraction operation, and smoothly contracts by the pressure of the hydraulic fluid received by the piston 40.

When the filling port 26 is sealed by the sealing portion 14, the bottom side chamber 5 and the tank chamber 7 are sealed from the outside. For this reason, it is possible to prevent the bottom side chamber 5 from being dried and the internal lubricating liquid from being depleted, and it is possible to prevent moisture, dust and the like from entering the bottom side chamber 5 from the outside. Thereby, it is prevented that rust is generated on the inner wall surface 11 of the cylinder tube 10. For this reason, it is possible to prevent the piston seal 41 from adhering to and sticking to the inner wall surface 11 of the cylinder tube 10. Further, it is possible to eliminate the rust prevention treatment applied to the inner wall surface 11 of the cylinder tube 10. Further, the durability required for the piston seal 41 is kept low, and the selection range of the piston seal 41 can be expanded.

When storing the work vehicle, the hydraulic cylinder 1 is set in the most extended state, the central axis O is inclined with respect to the horizontal direction, and the bottom side chamber 5 is lower than the rod side chamber 6. In a state where the hydraulic cylinder 1 assumes this storage posture, the filling amount of the lubricating liquid is set so that at least a part of the piston seal 41 is immersed in the lubricating liquid interposed in the bottom side chamber 5.

Even when the work vehicle is stored for a long period of time, part of the piston seal 41 is immersed in the lubricating liquid, so that the piston seal 41 dries and adheres to the inner wall surface 11 of the cylinder tube 10. It can prevent sticking. Thereby, when the work vehicle is operated after being stored for a long period of time, it is possible to prevent the piston seal 41 from sticking to the inner wall surface 11 of the cylinder tube 10 and deforming. Further, the hydraulic fluid supplied to the rod side chamber 6 can be prevented from leaking to the bottom side chamber 5 via the piston seal 41.

As the hydraulic cylinder 1 expands and contracts during operation of the work vehicle and the piston 40 slides with respect to the cylinder tube 10, a slight leakage of hydraulic fluid moves from the rod side chamber 6 to the bottom side chamber 5. May occur. When such sliding leakage occurs, there is a possibility that the amount of the lubricating liquid present in the bottom side chamber 5 or the tank chamber 7 increases beyond the set amount. In this case, it is possible to open the filling port 26 through the sealing portion 14 during maintenance, and to discharge excess lubricating liquid to the outside through the filling port 26. Further, by slightly loosening the set screw 17, the ball 18 is separated from the tapered inner peripheral surface of the filling tube 15, and the air or lubricating liquid in the bottom side chamber 5 is discharged from the air vent hole 19 through the filling port 26. Can do.

Depending on the operating conditions of the hydraulic cylinder 1, the amount of lubricating fluid present in the bottom chamber 5 may be less than the set amount. In this case, at the time of maintenance, the filling port 26 is opened through the sealing portion 14, and the lubricating liquid is supplied to the tank chamber 7 from the outside through the filling port 26.

For example, when the lubricating fluid is replenished during maintenance, the hydraulic cylinder 1 is in a state (posture) in which the central axis O extends in the vertical direction and the piston rod 20 extends upward from the cylinder head 60 of the cylinder tube 10. Are arranged as follows. In that state, when the bottom side chamber 5 is filled with a set amount of lubricating liquid, the filling port 26 is opened at a position where the liquid level of the lubricating liquid reaches in the tank tube 25. That is, the filling port 26 is provided at a position where the liquid level of the lubricating liquid reaches when the bottom side chamber 5 is filled with a predetermined amount of lubricating liquid. As described above, the position where the filling port 26 of the tank tube 25 is opened depends on the posture that the hydraulic cylinder 1 takes when replenishing the lubricating liquid during maintenance (pre-set posture) and the filling amount of the lubricating liquid (preliminary). Set amount).

When replenishing the lubricating liquid from the filling port 26 at the time of maintenance, the operator replenishes the lubricating liquid from the filling port 26 in a state where the hydraulic cylinder 1 assumes a posture in which the central axis O extends in the vertical direction. The replenishment of the lubricating liquid is stopped at the time when it overflows from the tank chamber 7 and flows out of the filling port 26 or just before it overflows from the tank chamber 7. In this way, by adjusting the replenishment amount so that the liquid level of the lubricating liquid reaches the vicinity of the filling port 26, it is easy to fill the bottom side chamber 5 with the set amount of lubricating liquid.

For example, a large hydraulic cylinder provided in a forklift or the like can be provided with a check valve that returns the excess working fluid (lubricating fluid) in the bottom side chamber to the rod side chamber. However, in comparison with this, the small hydraulic cylinder 1 cannot secure a space for providing this check valve. In response to the fact that the hydraulic cylinder 1 does not have a valve means such as a check valve for supplying and discharging hydraulic fluid between the rod side chamber 6 and the bottom side chamber 5, a filling port 26 and a sealing portion 14 are provided. Yes. As a result, it is possible to enclose an appropriate amount of lubricating liquid in the bottom side chamber 5.

According to the above 1st Embodiment, there exist the following effects.

In the hydraulic cylinder 1, the sliding portion of the piston 40 is lubricated by the lubricating liquid filled in the bottom side chamber 5 from the filling port 26. By sealing the filling port 26 with the sealing part 14, the bottom side chamber 5 is sealed with respect to the outside. Thereby, it is possible to prevent the lubricating liquid from being exhausted and cause internal rusting, and it is possible to prevent the piston seal 41 from adhering to and sticking to the inner wall surface 11 of the cylinder tube 10. Further, it is possible to eliminate the rust prevention treatment applied to the inner wall surface 11 of the cylinder tube 10. Further, the durability required for the piston seal 41 is kept low, and the selection range of the piston seal 41 can be expanded.

The hydraulic cylinder 1 includes a tank tube 25 disposed around the cylinder tube 10, and the tank chamber 7 is provided between the cylinder tube 10 and the tank tube 25, so that the tank chamber can be changed by changing the inner diameter of the tank tube 25. The volume ratio between 7 and the bottom side chamber 5 can be arbitrarily set.

In the hydraulic cylinder 1, an annular port block 30 that guides hydraulic fluid supplied to and discharged from the rod side chamber 6 is coupled to the outer periphery of the cylinder tube 10, and an end of the tank tube 25 is coupled to the port block 30. For this reason, the tank chamber 7 can be provided in the space around the cylinder tube 10 adjacent to the port block 30, and the tank chamber 7 can prevent the hydraulic cylinder 1 from increasing in size.

In the hydraulic cylinder 1, the outer tube 35 that defines the supply / discharge passage 33 and the tank tube 25 that defines the tank chamber 7 are arranged around the cylinder tube 10 with the port block 30 interposed therebetween, and the hydraulic pressure is applied to the outer tube 35. A spring 2 that biases the cylinder 1 in the contracting direction is connected. For this reason, the spring 2 can be arrange | positioned along the outer tube 35, and it can suppress that an apparatus enlarges with the spring 2. FIG.

The hydraulic cylinder 1 includes a bottom block 50 that closes the opening end of the cylinder tube 10, and a flange 52 to which the end of the tank tube 25 is coupled is formed on the bottom block 50. For this reason, the bottom side chamber 5 and the tank chamber 7 can be defined by the common bottom block 50, and the increase in the number of parts which comprise the hydraulic cylinder 1 can be suppressed. Moreover, the rigidity of the bottom block 50 can be increased by connecting the tank tube 25 thicker than the cylinder tube 10 to the bottom block 50.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. Below, it demonstrates centering on a different point from the said 1st Embodiment, the same code | symbol is attached | subjected to the structure same as the hydraulic cylinder of the said 1st Embodiment, and description is abbreviate | omitted.

The hydraulic cylinder 1 according to the first embodiment has a configuration in which the flange portion 52 to which the end portion of the tank tube 25 is coupled to the bottom block 50 is formed. On the other hand, in the hydraulic cylinder 101 according to the second embodiment, an annular outer block 110 is coupled to the outer periphery of the cylinder tube 10 separately from the bottom block 150, and the end of the tank tube 125 is connected to the outer block 110. The hydraulic cylinder 1 according to the first embodiment is different from the hydraulic cylinder 1 according to the first embodiment in that the configurations are combined.

The end of the cylinder tube 10 is coupled to the outer periphery of the bottom block 150 by a welded portion 151. The bottom block 150 is connected to the vehicle body side arm via a pin (not shown).

The outer block 110 is coupled to the outer periphery of the cylinder tube 10 by the welded portion 109. The outer block 110 is formed in an annular shape having an L-shaped cross section so as not to block the through hole 13 opened at the end of the cylinder tube 10.

The outer tube 35 is stretched between the port block 130 and the cylinder head 60 and defines a supply / discharge passage 33 inside thereof.

The cylindrical tank tube 125 is stretched over the port block 130 and the outer block 110, and the tank chamber 7 is defined inside thereof.

One end of the tank tube 125 is fitted into a fitting recess 131 formed in the port block 130 via an O-ring 132. The other end of the tank tube 125 is fitted to the outer periphery of the outer block 110 via an O-ring 112.

An annular groove 113 is formed on the outer periphery of the outer block 110, and the tank tube 125 is prevented from coming off in the axial direction via a retaining ring 108 fitted in the annular groove 113.

The hydraulic cylinder 101 includes a filling port 126 that passes through the tank tube 125 and opens into the tank chamber 7, and a sealing portion 114 that seals the filling port 126.

The sealing portion 114 includes a filling tube 115 that is coupled to the outer periphery of the tank tube 125 via a welded portion 116, and a drain plug 117 that is screwed into the filling tube 115.

When the lubricating liquid is replenished during maintenance, the hydraulic cylinder 101 extends by a predetermined stroke, the central axis O is inclined at a predetermined angle with respect to the horizontal direction, and the bottom side chamber 5 becomes lower than the rod side chamber 6. Take a posture. In a state where the hydraulic cylinder 101 assumes this posture, when the bottom side chamber 5 is filled with a predetermined amount of lubricating liquid, the filling port 126 is opened at a position where the liquid level of the lubricating liquid reaches in the tank tube 125. . By changing the rotational position of the tank tube 125 with respect to the cylinder tube 10 and changing the height position of the filling port 126, the set value of the filling amount of the lubricating liquid can be changed.

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

In the hydraulic cylinder 101, the sliding portion of the piston 40 is lubricated by the lubricating liquid filled in the bottom side chamber 5 from the filling port 126. By sealing the filling port 126 with the sealing part 114, the bottom side chamber 5 is sealed with respect to the outside. Thereby, it is possible to prevent the lubricating liquid from being exhausted and cause internal rusting, and it is possible to prevent the piston seal 41 from adhering to and sticking to the inner wall surface 11 of the cylinder tube 10.

The hydraulic cylinder 101 includes an outer block 110 coupled to the outer periphery of the cylinder tube 10, and an end of the tank tube 125 is coupled to the outer block 110. For this reason, a tank chamber 7 having a predetermined capacity can be provided around the cylinder tube 10. Further, depending on the specifications, the tank chamber 7 can be eliminated by removing the retaining ring 108 and removing the tank tube 125.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. Below, it demonstrates centering on a different point from the said 1st Embodiment, the same code | symbol is attached | subjected to the structure same as the hydraulic cylinder of the said 1st Embodiment, and description is abbreviate | omitted.

In the hydraulic cylinder 1 according to the first embodiment, the tank chamber 7 is provided by the tank tube 25 disposed around the cylinder tube 10. On the other hand, in the hydraulic cylinder 201 according to the third embodiment, the first embodiment is that the piston rod 220 is formed in a hollow cylindrical shape and the tank chamber 207 is provided inside the piston rod 220. It is different from the hydraulic cylinder 1 according to the embodiment.

The hydraulic cylinder 201 includes a cylindrical cylinder tube 210 in which a piston 240 is slidably accommodated, and a piston rod 220 that protrudes from the cylinder tube 210 to the outside. An eye bracket portion 221 is formed at the tip of the piston rod 220, and the eye bracket portion 221 is connected to the mower side arm. An eye bracket portion 251 is formed at the base end portion of the cylinder tube 210, and the eye bracket portion 251 is connected to the vehicle body side arm. Around the cylinder tube 210, a spring (not shown) that urges the piston rod 220 in a direction protruding from the cylinder tube 210 is provided.

A piston 240 is provided at the base end of the piston rod 220 inserted into the cylinder tube 210. The space inside the cylinder tube 210 is partitioned into a rod side chamber 206 and a bottom side chamber 205 by a piston 240. A piston seal 241 is interposed on the outer periphery of the piston 240. When the piston seal 241 contacts the inner wall surface 211 of the cylinder tube 210, the space between the bottom side chamber 205 and the rod side chamber 206 is sealed.

A tank chamber 207 is defined inside the cylindrical piston rod 220. The base end of the piston rod 220 opens into the bottom side chamber 205. The tank chamber 207 and the bottom side chamber 205 communicate with each other via the base end (opening) of the piston rod 220.

The cylinder tube 210 is provided with a supply / discharge port 232 that opens to the rod side chamber 206. A piping extending from the hydraulic pressure source is connected to the supply / discharge port 232. The hydraulic fluid supplied and discharged by the hydraulic pressure source enters and exits the supply / discharge port 232 as indicated by arrows in the figure.

The cylinder tube 210 is provided with a filling port 226 that opens into the bottom chamber 205, and a sealing portion 214 that seals the filling port 226 is provided.

The sealing portion 214 includes a filling tube 215 coupled to the outer periphery of the cylinder tube 210 and a drain plug 217 that detachably closes the filling tube 215.

When the lubricating fluid is replenished during maintenance, the hydraulic cylinder 201 is extended by a predetermined stroke, its central axis O is inclined at a predetermined angle with respect to the horizontal direction, and the bottom side chamber 205 becomes lower than the rod side chamber 206. Take a posture. In a state where the hydraulic cylinder 201 assumes this posture, when the bottom side chamber 205 is filled with a predetermined amount of lubricating liquid, the filling port 226 is opened at a position where the liquid level of the lubricating liquid reaches in the cylinder tube 210. .

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

In the hydraulic cylinder 201, the sliding portion of the piston 240 is lubricated by the lubricating liquid filled in the bottom side chamber 205 from the filling port 226. By sealing the filling port 226 with the sealing portion 214, the bottom side chamber 205 is sealed from the outside. Thereby, it is possible to prevent the lubricating liquid from being exhausted and cause internal rusting, and it is possible to prevent the piston seal 241 from adhering to and sticking to the inner wall surface 211 of the cylinder tube 210.

In the hydraulic cylinder 201, the piston rod 220 is formed in a hollow cylindrical shape, and a tank chamber 207 is provided inside the piston rod 220. For this reason, compared with what a tank chamber is provided around a cylinder tube, size reduction and weight reduction are achieved.

The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

A tank container defining a tank chamber may be provided outside the cylinder tube, and the tank chamber inside the tank container and the bottom side chamber inside the cylinder tube may be communicated with each other via a pipe.

Claims

A single-acting hydraulic cylinder (1, 101, 201) that is contracted by the pressure of the hydraulic fluid guided from the hydraulic pressure source to the rod-side chamber among the rod-side chamber and the bottom-side chamber partitioned by the piston,
A cylindrical cylinder tube (10, 210) having a piston (40, 240) slidably housed therein and having the rod side chamber (6, 206) and the bottom side chamber (5, 205) therein;
Piston seals (41, 241) interposed between the pistons (40, 240) and slidably contacting the inner wall surfaces (11, 211) of the cylinder tubes (10, 210);
A piston rod (20, 220) connected to the piston (40, 240) and protruding outward from the cylinder tube (10, 210);
A tank chamber (7, 207) communicating with the bottom side chamber (5, 205);
A filling port (26, 126, 226) for filling the bottom side chamber (5, 205) or the tank chamber (7, 207) with a lubricating liquid from the outside;
A hydraulic cylinder (1, 101, 201) comprising a sealing portion (14, 114, 214) for sealing the filling port (26, 126, 226).
A hydraulic cylinder (1, 101) according to claim 1,
A tank tube (25, 125) disposed around the cylinder tube (10);
A hydraulic cylinder (1, 101) in which the tank chamber (7) is provided between the cylinder tube (10) and the tank tube (25, 125).
A hydraulic cylinder (1) according to claim 2,
An annular port block (30) for guiding hydraulic fluid supplied to and discharged from the rod side chamber (5) is coupled to the outer periphery of the cylinder tube (10),
A hydraulic cylinder (1) in which an end of the tank tube (25) is coupled to the port block (30).
A hydraulic cylinder (1) according to claim 3,
A bottom block (50) for closing the open end of the cylinder tube (10);
A hydraulic cylinder (1) in which a flange (52) is formed to which an end of the tank tube (25) is coupled to the bottom block (50).
A hydraulic cylinder (101) according to claim 3,
An annular outer block (110) coupled to the outer periphery of the cylinder tube (10);
A hydraulic cylinder (101) in which the tank tube (125) is stretched over the port block (130) and the outer block (110).
A hydraulic cylinder (201) according to claim 1,
The piston rod (220) is formed in a hollow cylindrical shape,
A hydraulic cylinder (201) in which the tank chamber (207) is provided inside the piston rod (220).
A hydraulic cylinder (1, 101, 201) according to any one of the preceding claims,
In the filling port (26, 126, 226), the posture of the hydraulic cylinder (1, 101, 201) is set so that the piston rod (20, 220) extends upward from the cylinder tube (10, 210). In this state, the hydraulic cylinder (1) provided at the position where the liquid level of the lubricating liquid reaches when the bottom side chamber (5, 205) or the tank chamber (7, 207) is filled with a predetermined amount of lubricating liquid. , 101, 201).