Fluid pressure cylinder unit

Abstract

A fluid pressure cylinder unit (101, 201, 301, 401) is provided with: a lift cylinder (100, 400) having a cylinder tube (1) and a piston rod (10, 310); a tank (40, 340) having a gas chamber (41) that can be filled with a gas and a liquid chamber (42) that can be filled with a liquid; and a first passage (30) that connects the first chamber and the gas chamber (41) of the tank (40, 340), fills the first chamber with gas, and causes the piston rod (10, 310) to reciprocate by supplying and discharging the operating fluid to the second chamber, the first passage (30) being provided with a check valve (50) that only allows the gas to flow from the first chamber to the gas chamber (41) of the tank (40, 340).

Description

Technical Field

[0001] The invention relates to a fluid pressure cylinder unit. Background Art

[0002] In Japanese Patent Laid-Open JP2016-176566A, a fluid pressure cylinder is disclosed, which has: a bottomed cylinder having an opening at one end; a rod inserted into the cylinder; a piston connected to the top of the rod and dividing the cylinder into a rod side chamber for gas filling and a bottom side chamber for supplying and discharging working fluid. Gas is filled into the rod side chamber, and working fluid is supplied and discharged into the bottom side chamber. The fluid pressure cylinder is extended by the working hydraulic pressure guided from the hydraulic source to the bottom side chamber. Summary of the invention

[0003] When the fluid pressure cylinder described in Japanese Patent Laid-Open No. JP2016-176566A is extended, the gas in the rod side chamber is pressurized and discharged to a fluid tank, etc. This high-pressure gas is simply discharged to a fluid tank, etc., and is not effectively utilized.

[0004] An object of the present invention is to efficiently and flexibly move high-pressure gas discharged from a first chamber of a fluid pressure cylinder.

[0005] According to one embodiment of the present invention, a fluid pressure cylinder unit comprises: a fluid pressure cylinder having a cylinder barrel and a piston rod, wherein the piston rod is arranged in the cylinder barrel and can reciprocate in the cylinder barrel, and divides the cylinder barrel into a first chamber and a second chamber; a storage tank having an air chamber that can be filled with gas and a liquid chamber that can be filled with liquid; a first passage that connects the first chamber and the air chamber of the storage tank, fills the first chamber with gas, and reciprocates the piston rod by supplying and discharging working fluid to the second chamber, and a valve is provided on the first passage that only allows gas to flow from the first chamber to the air chamber of the storage tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a circuit diagram of a fluid pressure cylinder unit according to an embodiment of the present invention.

[0007] Figure 2 It is a diagram showing the operation of the fluid pressure cylinder unit and the state of filling the tank with gas according to the embodiment of the present invention.

[0008] Figure 3 This is a circuit diagram of a fluid pressure cylinder unit according to Modification 1 of the embodiment of the present invention.

[0009] Figure 4 This is a circuit diagram of a fluid pressure cylinder unit according to Modification 2 of the embodiment of the present invention.

[0010] Figure 5 This is a circuit diagram of a fluid pressure cylinder unit according to Modification 3 of the embodiment of the present invention. DETAILED DESCRIPTION

[0011] A fluid pressure cylinder unit 101 according to an embodiment of the present invention will be described with reference to the drawings. The fluid pressure cylinder unit 101 includes a fluid pressure cylinder and a tank 40 connected to the fluid pressure cylinder. In this embodiment, a case where the fluid pressure cylinder is a lift cylinder 100 for raising and lowering the forks of a forklift will be described.

[0012] The lifting cylinder 100 is a single-acting hydraulic cylinder. Figure 1 As shown, the lifting cylinder 100 comprises: a cylinder barrel 1; a piston rod 10, which is arranged in the cylinder barrel 1 and can reciprocate in the cylinder barrel 1, and divides the cylinder barrel 1 into a rod side chamber 2 as a first chamber and a rod opposite side chamber 3 as a second chamber; a first passage 30, which is connected to the rod side chamber 2; and a main passage 20, which is connected to the rod opposite side chamber 3.

[0013] The piston rod 10 includes: a piston 11, which is arranged to slide freely along the inner circumferential surface of the cylinder 1; and a rod 12, one end of which is connected to the piston 11 and the other end of which extends to the outside of the cylinder 1 and reciprocates. The rod side chamber 2 is filled with a gas such as air. In addition, "filling" includes the case where the rod side chamber 2 is actively filled with gas using a gas cylinder, etc., and the case where gas is mixed into the rod side chamber 2 during the assembly of the lifting cylinder 100. The gas is discharged from the rod side chamber 2 through the first passage 30. The working oil as the working fluid is supplied to the opposite side chamber 3 of the rod through the main passage 20. In addition, as the working fluid, liquids such as water other than the working oil can also be used.

[0014] A switching valve (not shown) is provided on the main passage 20. By switching the switching valve, the main passage 20 is connected to a pump (not shown) or a fluid tank (not shown). In the lift cylinder 100, the hydraulic oil is supplied and discharged to the rod-opposite chamber 3 via the main passage 20, so that the piston rod 10 reciprocates. Specifically, when the hydraulic oil is supplied from the hydraulic source to the rod-opposite chamber 3, the piston rod 10 moves upward ( Figure 1 When the hydraulic oil is discharged from the rod opposite side chamber 3 to the fluid box due to the weight of the fork, the cargo, and the piston rod 10, the piston rod 10 moves downward (upper side). Figure 1 The lower side of the fork moves, the lifting cylinder 100 contracts, and the fork and the cargo are lowered.

[0015] In addition, the storage tank 40 has an air chamber 41 that can be filled with gas and a liquid chamber 42 that can be filled with liquid. The storage tank 40 is set independently of the lifting cylinder 100. In addition, the air chamber 41 and the liquid chamber 42 can also be divided by a partition member such as a free piston and an air bag. The air chamber 41 is connected to the first passage 30, and the liquid chamber 42 is connected to the branch passage 21 branched from the main passage 20. In this way, the rod side chamber 2 and the air chamber 41 are connected via the first passage 30, and the rod opposite side chamber 3 and the liquid chamber 42 are connected via the main passage 20 and the branch passage 21. On the first passage 30, a check valve 50 is provided as a valve that only allows gas to flow from the rod side chamber 2 to the air chamber 41 of the storage tank 40. In addition, a solenoid valve, a manual valve, etc. can also be provided instead of the check valve 50. In addition, the rod opposite side chamber 3 and the liquid chamber 42 can also be connected via a passage arranged in parallel with the main passage 20.

[0016] The hydraulic cylinder unit 101 of the present embodiment is assembled by connecting the lift cylinder 100 and the tank 40 under the atmosphere. Before the lift cylinder 100 and the tank 40 are connected, the air chamber 41 of the tank 40 is at atmospheric pressure and is not filled with high-pressure gas. The air chamber 41 of the tank 40 is filled with high-pressure gas by the initial operation of the lift cylinder 100 after the lift cylinder 100 and the tank 40 are connected.

[0017] Next, the filling of the gas chamber 41 of the tank 40 with the high-pressure gas will be described in detail.

[0018] Figure 2 (a)~ Figure 2 (c) is a diagram showing the initial operation of the lift cylinder 100. Figure 2 (a) shows the state before the initial operation of the lift cylinder 100 (in other words, immediately after the lift cylinder 100 is connected to the tank 40). In this state, the lift cylinder 100 is in the most contracted state due to the dead weight of the piston rod 10. The rod side chamber 2 and the air chamber 41 of the tank 40 are at atmospheric pressure, and the air chamber 41 is not filled with high-pressure gas.

[0019] like Figure 2 As shown in (b), the initial operation of the lift cylinder 100 is performed by supplying hydraulic oil from the hydraulic source to the rod-side chamber 3 via the main passage 20, and extending the lift cylinder 100 (specifically, the maximum extension). As a result, the gas in the rod-side chamber 2 is pressurized, as shown in FIG. Figure 2 As shown by the arrow on the right side of (b), the gas is guided to the gas chamber 41 of the reservoir 40 via the first passage 30 and the check valve 50. The gas chamber 41 is filled with high-pressure gas until the pressure in the gas chamber 41 reaches the set pressure.

[0020] Then, when the hydraulic oil is discharged from the opposite-rod side chamber 3, Figure 2As shown in (c), the lift cylinder 100 is most retracted due to the deadweight of the piston rod 10, and the initial operation of the lift cylinder 100 is completed. Figure 2 Compared with the state shown in (b), the volume of the rod side chamber 2 increases, thereby reducing the pressure in the rod side chamber 2. However, since the check valve 50 is provided on the first passage 30, the gas filled in the gas chamber 41 of the tank 40 is not guided to the rod side chamber 2 via the first passage 30. As a result, the pressure in the gas chamber 41 of the tank 40 is maintained at the set pressure. Figure 2 (a)- Figure 2 The operation (c) may be performed before or after the fluid pressure cylinder unit 101 is mounted on the forklift. Figure 2 (a)- Figure 2 The operation (c) can also be performed when the lift cylinder 100 is tested for operation and when the air in the rod-opposite side chamber 3 is extracted. In addition, when an electromagnetic valve, a manual valve, etc. are provided instead of the check valve 50, the following structure is sufficient, that is, when the lift cylinder 100 is extended, the rod-side chamber 2 and the air chamber 41 of the tank 40 are connected via the first passage 30, and when the lift cylinder 100 is contracted, the connection between the rod-side chamber 2 and the air chamber 41 of the tank 40 is cut off. Even in this structure, the electromagnetic valve, the manual valve, etc. can only allow the gas to flow from the rod-side chamber 2 to the air chamber 41 of the tank 40.

[0021] In the normal operation of the lift cylinder 100 in which the fluid pressure cylinder unit 101 is mounted on a forklift and the cargo is transported and loaded and unloaded, the pressure in the rod side chamber 2 is lower than the pressure in the air chamber 41 of the tank 40 until the lift cylinder 100 reaches the most extended state. However, the pressure in the air chamber 41 of the tank 40 is maintained by the check valve 50. When the lift cylinder 100 reaches the most extended state, the pressure in the rod side chamber 2 is equal to the pressure in the air chamber 41 of the tank 40. Figure 2 (b) is the same as the state shown in FIG. 1 and is equal to the pressure in the air chamber 41 of the tank 40. Thus, in the normal operation of the lift cylinder 100, the gas in the rod side chamber 2 is not guided to the air chamber 41 of the tank 40. That is, in the fluid pressure cylinder unit 101, after the lift cylinder 100 is connected to the tank 40, the gas in the rod side chamber 2 is pressurized and filled into the air chamber 41 of the tank 40 only when the lift cylinder 100 is initially extended (specifically, the maximum extension).

[0022] In this way, in the lift cylinder 100, in the initial operation of the lift cylinder 100, when the lift cylinder 100 is extended, the gas filled in the rod side chamber 2 is pressurized and guided to be filled in the gas chamber 41 of the reservoir 40 via the first passage 30 and the check valve 50. Thereby, the high-pressure gas discharged from the rod side chamber 2 can be effectively and flexibly used as the gas filled in the gas chamber 41 of the reservoir 40.

[0023] In addition, the storage tank 40 first fills the air chamber 41 with high-pressure gas at the initial operation of the lifting cylinder 100, and therefore, the high-pressure gas is not filled into the air chamber 41 before the operation of the lifting cylinder 100. Therefore, the storage tank 40 can be handled safely and easily. In addition, when the storage tank 40 is transported, it can be transported safely and easily. In addition, the gas in the cylinder side chamber 2 is pressurized and filled into the air chamber 41 of the storage tank 40, and therefore, it is not necessary to use a gas cylinder or the like in order to fill the high-pressure gas into the air chamber 41. Therefore, compared with the case of using a gas cylinder or the like, the storage tank 40 can be handled safely and easily, and the manufacturing cost is reduced.

[0024] In addition, in the fluid pressure cylinder unit 101, the opposite-rod side chamber 3 and the liquid chamber 42 of the tank 40 are connected via the main passage 20 and the branch passage 21, so that the pressure fluctuations in the main passage 20 and the opposite-rod side chamber 3 are absorbed by the tank 40. Therefore, during the transportation of cargo by the forklift, even if an impact from the road surface, for example, acts on the lift cylinder 100, the vibration of the cargo can be absorbed by the tank 40. Thus, the cargo can be prevented from collapsing during transportation.

[0025] According to the above-described embodiment, the following effects are achieved.

[0026] In the lift cylinder 100, when the lift cylinder 100 is extended, the gas filled in the rod side chamber 2 is pressurized and guided to the gas chamber 41 of the reservoir 40 through the first passage 30 and the check valve 50 to be filled. Thereby, the high-pressure gas discharged from the rod side chamber 2 can be effectively and flexibly used as the gas filled in the gas chamber 41 of the reservoir 40.

[0027] In the lift cylinder 100, the anti-rod side chamber 3 and the liquid chamber 42 of the reservoir 40 are communicated with each other through the main passage 20. Thus, the reservoir 40 can absorb vibration of the object driven by the lift cylinder 100, that is, the cargo or the like.

[0028] In the fluid pressure cylinder unit 101, after the lift cylinder 100 is connected to the tank 40, the gas chamber 41 of the tank 40 is filled with high-pressure gas for the first time at the initial operation of the lift cylinder 100. Therefore, the high-pressure gas is not filled into the gas chamber 41 before the operation of the lift cylinder 100. Therefore, the tank 40 can be handled safely and easily. In addition, when the tank 40 is transported, it can be transported safely and easily.

[0029] The following modified examples are also within the scope of the present invention, and it is possible to combine the configuration shown in the modified examples with the configuration described in the above embodiment, or to combine the configurations described in the following different modified examples with each other.

[0030] <Variation 1>

[0031] In the above embodiment, the fluid pressure cylinder unit 101 includes the first passage 30 that connects the rod side chamber 2 and the air chamber 41 of the reservoir 40. Figure 3 As shown, the fluid pressure cylinder unit 201 according to the first modification includes a second passage 31 connected between the rod side chamber 2 and the check valve 50 in the first passage 30 and communicating with the atmosphere.

[0032] The second passage 31 is connected to the atmosphere via the filter 60. A check valve 51 is provided on the second passage 31 to allow only gas to flow from the atmosphere to the first passage 30. Thus, when the pressure in the rod side chamber 2 and the first passage 30 decreases (specifically, decreases compared to the atmospheric pressure) during the contraction of the lift cylinder 100, the gas is supplied to the rod side chamber 2 and the first passage 30 via the filter 60, the second passage 31, and the check valve 51. Thus, whenever the lift cylinder 100 is extended, the gas in the rod side chamber 2 can be repeatedly filled into the air chamber 41 of the tank 40. Thus, a decrease in the pressure in the air chamber 41 is prevented.

[0033] In addition, the fluid pressure cylinder unit 201 is provided with a third passage 32 connected between the rod side chamber 2 and the check valve 50 in the first passage 30. The third passage 32 is connected to the atmosphere via a silencer 61. A relief valve 52 is provided on the third passage 32, which opens when the pressure of the first passage 30 reaches a preset pressure. When the relief valve 52 opens, the gas in the rod side chamber 2 and the first passage 30 is discharged to the atmosphere via the third passage 32 and the silencer 61. The pressure at which the relief valve 52 opens is set, for example, to be equal to the set pressure of the tank 40. Thus, the pressure in the rod side chamber 2 and the first passage 30 is not greater than the set pressure of the tank 40. In other words, the situation in which the gas is filled into the air chamber 41 of the tank 40 at a pressure higher than the set pressure during the operation of the lift cylinder 100 is prevented, and the situation in which the pressure in the air chamber 41 becomes higher than the set pressure is prevented.

[0034] In addition, the third passage 32 may be connected to the fluid tank instead of the atmosphere. In addition, the second passage 31 and the third passage 32 do not need to be provided on both sides, and only one side may be provided. In addition, the filter 60 and the muffler 61 are not essential and may not be provided.

[0035] <Variation 2>

[0036] In the above embodiment, the rod-side chamber 3 of the fluid pressure cylinder unit 101 and the liquid chamber 42 of the reservoir 40 are connected via the main passage 20 and the branch passage 21. Figure 4As shown, in the liquid pressure cylinder unit 301, the rod-opposite side chamber 3 and the liquid chamber 42 of the tank 40 are not connected, and the liquid chamber 42 of the tank 40 is connected to a device (not shown) different from the lift cylinder 100 via the passage 221. Even with this structure, the high-pressure gas discharged from the rod-side chamber 2 can be effectively and flexibly used as the gas filled in the gas chamber 41 of the tank 40. In addition, the vibration of other devices connected to the tank 40 can be absorbed by the tank 40.

[0037] <Variation 3>

[0038] In the above embodiment, the reservoir 40 is provided independently of the lift cylinder 100. In contrast, in the fluid pressure cylinder unit 401 according to the third modification, the reservoir 40 is provided inside the piston rod 10. Specifically, Figure 5 As shown, the reservoir 340 has a free piston 43 as a dividing member for dividing the air chamber 41 and the liquid chamber 42, and the first passage 30, the check valve 50, the free piston 43, and the passage 321 for connecting the rod-opposite side chamber 3 and the liquid chamber 42 are provided in the piston rod 310. Even with this structure, when the hydraulic oil is supplied from the hydraulic source to the rod-opposite side chamber 3 to extend the lift cylinder 400, the gas in the rod-side chamber 2 is pressurized and guided to the air chamber 41 of the reservoir 340 through the first passage 30 and the check valve 50 to be filled. In addition, since the rod-opposite side chamber 3 and the liquid chamber 42 of the reservoir 340 are connected through the passage 321, the pressure fluctuations in the main passage 20 and the rod-opposite side chamber 3 are absorbed by the reservoir 340, and the cargo can be prevented from collapsing during the transportation of the cargo. In this way, the reservoir 340 is provided in the piston rod 310, so that the fluid pressure cylinder unit 401 can be made compact.

[0039] <Variation 4>

[0040] In the above-mentioned embodiment, the fluid pressure cylinder unit 101 connects the rod side chamber 2 and the air chamber 41 in such a manner that gas is filled into the rod side chamber 2. In addition, the rod opposite side chamber 3 and the liquid chamber 42 are connected, and working oil is supplied and discharged to the rod opposite side chamber 3. Without being limited to this, the fluid pressure cylinder unit 101 may also be configured as follows, that is, gas is filled into the rod opposite side chamber 3, the rod opposite side chamber 3 and the air chamber 41 are connected, the rod side chamber 2 and the liquid chamber 42 are connected, and working oil is supplied and discharged to the rod side chamber 2. In this structure, after the lifting cylinder 100 is connected to the tank 40, the gas in the rod opposite side chamber 3 is pressurized and filled into the air chamber 41 of the tank 40 only when the lifting cylinder 100 is initially contracted (specifically, the most contracted). In addition, the fluid pressure cylinder unit 101 may also be configured as follows. Figure 1 The orientation shown is reversed up and down and is used.

[0041] <Variant 5>

[0042] In the above embodiment, the fluid pressure cylinder is described as a lift cylinder 100 for raising and lowering the forks of a forklift. This is not limited to this, and the fluid pressure cylinder may be a cylinder other than the cylinder mounted on the forklift as long as the gas is filled into one of the rod side chamber 2 and the rod opposite side chamber 3, and the working fluid is supplied and discharged to the other side, so that the piston rod 10 reciprocates. In addition, the fluid pressure cylinder may also be a two-rod type cylinder.

[0043] The structure, function, and effect of the embodiment of the present invention configured as above will be summarized and described.

[0044] The fluid pressure cylinder unit 101, 201, 301, 401 comprises: a lifting cylinder 100, 400 as a fluid pressure cylinder, which has a cylinder barrel 1 and a piston rod 10, 310, wherein the piston rod 10, 310 is arranged in the cylinder barrel 1 and can reciprocate in the cylinder barrel 1, and divides the cylinder barrel 1 into a first chamber and a second chamber; a storage tank 40, 240, which has an air chamber 41 that can be filled with gas and a liquid chamber 42 that can be filled with liquid; a first passage 30, which connects the first chamber with the air chamber 41 of the storage tank 40, 340, fills the first chamber with gas, and supplies and discharges working fluid to the second chamber, thereby causing the piston rod 10, 310 to reciprocate, and on the first passage 30, a check valve 50 is provided as a valve that only allows gas to flow from the first chamber to the air chamber 41 of the storage tank 40, 340.

[0045] In this structure, when the lift cylinder 100, 400 is extended, the gas filled in the first chamber is pressurized and guided to the gas chamber 41 of the tank 40, 340 through the first passage 30 and the check valve 50 to be filled. Thereby, the high-pressure gas discharged from the first chamber can be effectively and flexibly used as the gas filled in the gas chamber 41 of the tank 40, 340.

[0046] In addition, in the fluid pressure cylinder unit 101 , 201 , 401 , the second chamber and the liquid chamber 42 of the tank 40 , 340 communicate with each other.

[0047] In this structure, the second chamber communicates with the liquid chamber 42 of the reservoir 40, 340. Thus, the reservoir 40, 340 can absorb vibration of the object driven by the lift cylinder 100, 400.

[0048] The fluid pressure cylinder unit 201 also includes a second passage 31 connected between the first chamber in the first passage 30 and the check valve 50 and communicating with the atmosphere. The second passage 31 is provided with a check valve 51 that only allows gas to flow from the atmosphere to the first passage 30 .

[0049] In this structure, a decrease in the pressure in the gas chamber 41 of the tank 40 is prevented.

[0050] The fluid pressure cylinder unit 201 also includes a third passage 32 connected between the first chamber in the first passage 30 and the check valve 50 . The third passage 32 is provided with a relief valve 52 that opens when the pressure in the first passage 30 reaches a preset pressure.

[0051] In this structure, the pressure in the gas chamber 41 of the storage tank 40 is prevented from becoming higher than a predetermined pressure.

[0052] In the fluid pressure cylinder unit 401 , the reservoir 340 further includes a free piston 43 as a partitioning member that partitions the air chamber 41 and the liquid chamber 42 , and the first passage 30 , the check valve 50 , and the free piston 43 are provided in the piston rod 310 .

[0053] In this structure, the fluid pressure cylinder unit 401 can be made compact.

[0054] In addition, in the fluid pressure cylinder unit 101, 201, 301, 401, after the lifting cylinder 100, 400 is connected to the tank 40, 340, when the lifting cylinder 100, 400 is initially extended or contracted, the gas in the first chamber is pressurized and filled into the air chamber 41 of the tank 40, 340.

[0055] In this structure, the high-pressure gas may not be filled into the gas chamber 41 before the operation of the lift cylinder 100 or 400. Therefore, the storage tank 40 or 340 can be handled safely and easily.

[0056] Although the embodiments of the present invention have been described above, the above embodiments merely represent a part of application examples of the present invention and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0057] This application claims priority based on Japanese Patent Application No. 2022-177559 filed with the Japan Patent Office on November 4, 2022, and all the contents of the application are incorporated into this specification by reference.

Claims

1. A fluid pressure cylinder unit, wherein: have: A fluid pressure cylinder having a cylinder barrel and a piston rod, wherein the piston rod is disposed in the cylinder barrel and can reciprocate in the cylinder barrel and divides the cylinder barrel into a first chamber and a second chamber; A storage tank having a gas chamber that can be filled with gas and a liquid chamber that can be filled with liquid; a first passage connecting the first chamber and the gas chamber of the storage tank, filling the first chamber with gas, The piston rod is reciprocated by supplying and discharging working fluid to the second chamber. The first passage is provided with a valve that allows only gas to flow from the first chamber to the gas chamber of the tank.

2. The fluid pressure cylinder unit according to claim 1, wherein: The second chamber is in communication with the liquid chamber of the storage tank.

3. The fluid pressure cylinder unit according to claim 1, wherein: further comprising a second passage connected to the first passage between the first chamber and the valve and communicating with the atmosphere, The second passage is provided with a check valve that allows only gas to flow from the atmosphere to the first passage.

4. The fluid pressure cylinder unit according to claim 1, wherein: further comprising a third passage connected between the first chamber and the valve in the first passage, The third passage is provided with a relief valve that opens when the pressure in the first passage reaches a preset pressure.

5. The fluid pressure cylinder unit according to claim 1, wherein: The storage tank further comprises a partitioning member for partitioning the gas chamber and the liquid chamber. The first passage, the valve, and the partitioning member are provided in the piston rod.

6. The fluid pressure cylinder unit according to claim 1, wherein: After the fluid pressure cylinder is connected to the storage tank, when the fluid pressure cylinder is initially extended or contracted, the gas in the first chamber is pressurized and filled into the gas chamber of the storage tank.

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