Fluid Pressure Cylinder Unit

Abstract

To facilitate the handling of a fluid pressure cylinder unit.SOLUTION: A fluid pressure cylinder unit 101 includes a lift cylinder 100 having a piston rod 10 which is provided reciprocatively in a cylinder tube 1 for partitioning the inside of the cylinder tube 1 into a rod chamber 2 and a bottom chamber 3, and driving a fork 80, a supply / discharge passage 20 connected to the bottom chamber 3, and a buffer 40 connected to the supply / discharge passage 20, the buffer 40 having a cylinder 41, a piston 51 provided reciprocatively in the cylinder 41 for partitioning the inside of the cylinder 41 into a first pressure chamber 43 and a second pressure chamber 42, a communication path 60 communicating between the first pressure chamber 43 and the second pressure chamber 42, and a spring 70 for energizing the piston 51 in a direction where the first pressure chamber 43 is shrunk, the bottom chamber 3 communicating with the first pressure chamber 43 or the second pressure chamber 42 through the supply / discharge passage 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a vehicle (forklift) that includes a vehicle body, a loading section supported on the vehicle body and capable of loading cargo, a lift cylinder for raising and lowering the loading section, and an accumulator that can communicate with the lift cylinder. The accumulator suppresses fluctuations in pressure in the chamber by introducing and accumulating fluid when pressure in the chamber of the lift cylinder increases, and by releasing the accumulated fluid when pressure in the chamber decreases. In this way, sudden pressure changes in the chamber are suppressed, thereby suppressing up and down vibration of the cargo loaded on the loading section. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-172516 Summary of the Invention [Problem to be solved by the invention]

[0004] In the lift cylinder described in Patent Document 1, high-pressure gas is sealed in an accumulator connected to the lift cylinder. Because high-pressure gas is subject to legal restrictions, it is not easy to transport the accumulator containing the high-pressure gas, or to transport and use the gas cylinder containing the high-pressure gas sealed in the accumulator. Therefore, the lift cylinder described in Patent Document 1 is difficult to handle.

[0005] The present invention has been made in consideration of the above problems, and has an object to make it easier to handle a fluid pressure cylinder unit. [Means for solving the problem]

[0006] The present invention is a fluid pressure cylinder unit comprising: a fluid pressure cylinder having a cylinder tube, a piston rod reciprocatably provided within the cylinder tube and dividing the interior of the cylinder tube into a rod chamber and a bottom chamber, and configured to drive a driven object; a supply / discharge passage connected to the bottom chamber and for supplying working fluid to the bottom chamber or discharging working fluid from the bottom chamber; and a shock absorber connected to the supply / discharge passage, wherein the shock absorber has a cylinder, a piston reciprocally provided within the cylinder and dividing the interior of the cylinder into a first pressure chamber and a second pressure chamber, a communication passage communicating between the first pressure chamber and the second pressure chamber, and an urging member urging the piston in a direction in which the first pressure chamber contracts, The shock absorber operates only by the flow of working fluid through the supply and discharge passages, The bottom chamber is characterized by being in communication with the first pressure chamber or the second pressure chamber through a supply / discharge passage.

[0007] In this invention, when an impact is applied to the driven object, the bottom chamber becomes highly pressurized, and the first pressure chamber communicating with the bottom chamber becomes highly pressurized. As a result, working fluid moves between the first pressure chamber and the second pressure chamber through the communicating passage, causing the piston of the shock absorber to move, changing the volume of the bottom chamber. This absorbs the impact applied to the driven object. In this way, the fluid pressure cylinder unit is easy to handle because the impact applied to the driven object is absorbed by the shock absorber rather than by an accumulator filled with high-pressure gas.

[0008] Furthermore, the present invention is characterized in that the communication passage has a throttle portion that applies resistance to the flow of the working fluid.

[0009] In this invention, the throttle portion exerts a damping force, so that the impact applied to the driven object is more effectively absorbed.

[0010] In addition, the present invention is characterized in that the shock absorber has a rod with a piston connected to its tip and reciprocally movable within a cylinder, and the rod is provided in the second pressure chamber.

[0011] In this invention, the pressure-receiving areas of the piston facing the first pressure chamber and the second pressure chamber are different due to the rod, which makes it easier for the piston to move in response to pressure changes in the first pressure chamber and the second pressure chamber, and more effectively absorbs shocks applied to the driven object.

[0012] The present invention is also characterized in that the shock absorber is provided in a fluid pressure cylinder.

[0013] In this invention, the fluid pressure cylinder unit can be made compact. [Effects of the Invention]

[0014] According to the present invention, the fluid pressure cylinder unit can be easily handled. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a circuit diagram of a fluid pressure cylinder unit according to the embodiment of the present invention. [Figure 2] FIG. 2 is a front view of the fluid pressure cylinder unit according to the embodiment of the present invention. [Figure 3] 10A and 10B are schematic diagrams showing how shock is absorbed by a shock absorber. [Figure 4] FIG. 10 is a circuit diagram of a fluid pressure cylinder unit according to a first modified example of the embodiment of the present invention. [Figure 5] FIG. 10 is a circuit diagram of a fluid pressure cylinder unit according to a second modified example of the embodiment of the present invention. [Figure 6] FIG. 10 is a circuit diagram of a fluid pressure cylinder unit according to a third modified example of the embodiment of the present invention. [Figure 7] FIG. 10 is a circuit diagram of a fluid pressure cylinder unit according to a fourth modified example of the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] 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. In this embodiment, the fluid pressure cylinder is a lift cylinder 100 that drives (lifts and lowers) forks 80, which are the driving targets of a forklift, and a case will be described in which a pair of lift cylinders 100 are provided.

[0017] The lift cylinder 100 is a single-acting hydraulic cylinder. As shown in Figure 1, the lift cylinder 100 has a cylinder tube 1 and a piston rod 10 that is reciprocally movable within the cylinder tube 1 and divides the interior of the cylinder tube 1 into a rod chamber 2 and a bottom chamber 3.

[0018] The piston rod 10 has a piston 11 slidably mounted along the inner circumferential surface of the cylinder tube 1, and a rod 12 having one end connected to the piston 11 and the other end extending out of the cylinder tube 1 for reciprocating motion. The rod chamber 2 is filled with a gas such as air. The gas flows in and out of the rod chamber 2, or is compressed or expanded, according to the movement of the piston rod 10. Hydraulic oil as a working fluid is supplied to and discharged from the bottom chamber 3 through a supply / discharge passage 20, which will be described later. Note that fluids other than hydraulic oil, such as water or a water-soluble substitute, may also be used as the working fluid.

[0019] The fluid pressure cylinder unit 101 includes a supply / discharge passage 20 connected to the bottom chamber 3, and a shock absorber 40 connected to the supply / discharge passage 20. For example, when a forklift travels over an uneven road surface, an impact is applied to the forks 80, which may cause the load placed on the forks 80 to collapse. The shock absorber 40 is intended to absorb the impact applied to the forks 80 from the road surface.

[0020] The supply and discharge passage 20 is connected to both bottom chambers 3 of the pair of lift cylinders 100. The supply and discharge passage 20 has a hydraulic hose 21 (see FIG. 2) and a joint 22 (see FIG. 2), and is connected to a pump (not shown) or a tank (not shown) via a selector valve (not shown). In other words, the supply and discharge passage 20 supplies hydraulic oil to the bottom chamber 3 or discharges hydraulic oil from the bottom chamber 3. In the lift cylinder 100, the piston rod 10 reciprocates as hydraulic oil is supplied to and discharged from the bottom chamber 3 through the supply and discharge passage 20. Specifically, when hydraulic oil is supplied from the pump to the bottom chamber 3, the piston rod 10 moves upward (upward in FIG. 1), and the lift cylinder 100 extends, thereby lifting the forks 80 and the load placed on the forks 80. When hydraulic oil is discharged from the bottom chamber 3 into the tank due to the weight of the forks 80, the load, and the piston rod 10, the piston rod 10 moves downward (toward the bottom in FIG. 1), the lift cylinder 100 contracts, and the forks 80 and the load descend. The pair of lift cylinders 100 extend and contract synchronously.

[0021] The shock absorber 40 is provided between a pair of lift cylinders 100 (see FIG. 2). The shock absorber 40 includes a cylinder 41, a piston rod 50 that is provided reciprocally within the cylinder 41 and divides the interior of the cylinder 41 into a first pressure chamber 43 and a second pressure chamber 42, a communication passage 60 that connects the first pressure chamber 43 and the second pressure chamber 42, and a spring 70 as a biasing member that biases the piston rod 50 in a direction that contracts the first pressure chamber 43. In this embodiment, the shock absorber 40 is formed separately from the lift cylinder 100, and as shown in FIG. 2, the shock absorber 40 and the lift cylinder 100 are connected to the supply / discharge passage 20 and provided adjacent to each other side by side.

[0022] The piston rod 50 includes a piston 51 reciprocatingly disposed within the cylinder 41 and dividing the interior of the cylinder 41 into a first pressure chamber 43 and a second pressure chamber 42, and a rod 52 connected to the piston 51 at its tip and reciprocatingly disposed within the cylinder 41. In this embodiment, the rod 52 is disposed in the second pressure chamber 42 and extends outside the cylinder 41, with the second pressure chamber 42 being located above the first pressure chamber 43. In other words, in this embodiment, the second pressure chamber 42 is disposed on the rod 52 side. The supply / discharge passage 20 communicates with the first pressure chamber 43. In other words, the bottom chamber 3 of the lift cylinder 100 communicates with the first pressure chamber 43 through the supply / discharge passage 20. A communication passage 60 axially penetrates the piston 51 and communicates between the first pressure chamber 43 and the second pressure chamber 42. The communication passage 60 has an orifice 61 as a throttle portion that imparts resistance to the flow of hydraulic oil. Therefore, resistance is applied by the orifice 61 to the hydraulic oil moving between the first pressure chamber 43 and the second pressure chamber 42 through the communication passage 60. The spring 70 is provided in the second pressure chamber 42 so as to surround the rod 52 inside the second pressure chamber 42.

[0023] Next, the operation of the shock absorber 40 to absorb the shock applied to the fork 80 will be described in detail, mainly with reference to Fig. 3. Fig. 3 is a schematic diagram showing the operation of the shock absorber 40 to absorb the shock applied to the fork 80.

[0024] FIG. 3(a) shows a state in which the lift cylinder 100 is lifting the forks 80 while the vehicle is traveling, but before an impact is applied to the forks 80. In this state, the weight of the forks 80 and the load itself exerts pressure on the bottom chamber 3 of the lift cylinder 100 via the piston rod 10. Because the bottom chamber 3 is connected to the first pressure chamber 43 of the shock absorber 40 through the supply / discharge passage 20, the piston 51 of the shock absorber 40 moves upward and floats above the bottom surface of the cylinder 41. At this time, in the shock absorber 40, the load due to the pressure in the first pressure chamber 43 is in balance with the resultant force of the load due to the pressure in the second pressure chamber 42 and the biasing force of the spring 70. In this state, the spring 70 has a compression margin.

[0025] For example, when a forklift travels over an uneven road surface, an impact force F is applied to the fork 80 as shown in Figure 3(b). This causes a downward force to act on the piston rod 10 of the lift cylinder 100 via the fork 80, causing the pressure in the bottom chamber 3 and the first pressure chamber 43 of the shock absorber 40, which communicates with the bottom chamber 3, to rise, creating a pressure difference between the second pressure chamber 42 and the first pressure chamber 43 of the shock absorber 40. At this point, there is almost no movement of hydraulic oil, so the piston rod 10 does not move, and neither does the piston rod 50 of the shock absorber 40.

[0026] When the pressure in the first pressure chamber 43 of the shock absorber 40 increases and the load due to the pressure in the first pressure chamber 43 exceeds the combined force of the load due to the pressure in the second pressure chamber 42 and the biasing force of the spring 70, hydraulic oil in the second pressure chamber 42 moves through the communication passage 60 and the orifice 61 to the first pressure chamber 43, as shown by arrow A in FIG. 3(c), causing the piston rod 50 to move upward and the shock absorber 40 to extend. As a result, the first pressure chamber 43 expands and the pressure decreases, so hydraulic oil is guided from the bottom chamber 3 of the lift cylinder 100 to the first pressure chamber 43 through the supply / discharge passage 20. As shown by arrow B in FIG. 3(c), the piston rod 10 moves downward and the bottom chamber 3 contracts. As the lift cylinder 100 contracts in this manner, the impact applied to the fork 80 is absorbed. Note that the movement of the piston rod 10 of the lift cylinder 100 and the piston rod 50 of the shock absorber 40 is exaggerated in FIG. 3.

[0027] The amount of movement of the piston rod 10 corresponds to the amount of movement of the piston rod 50. Specifically, the bottom chamber 3 shrinks by an amount corresponding to the volume of the piston rod 50 withdrawn from the cylinder 41, causing the piston rod 10 to move. In other words, the greater the amount of movement of the piston rod 50, the greater the amount of movement of the piston rod 10, and therefore the easier it is to absorb an impact on the fork 80. When an impact on the fork 80 is absorbed, the hydraulic oil in the second pressure chamber 42 moves to the first pressure chamber 43 through the orifice 61, and a damping force is exerted by the orifice 61, so that the impact on the fork 80 is absorbed while being damped.

[0028] After absorbing the impact, the pressure in the bottom chamber 3 of the lift cylinder 100 and the first pressure chamber 43 of the shock absorber 40 decreases. Then, the piston rod 50 of the shock absorber 40 moves downward due to the biasing force of the spring 70, and the first pressure chamber 43 contracts. As a result, hydraulic oil is guided from the first pressure chamber 43 through the supply / discharge passage 20 to the bottom chamber 3 of the lift cylinder 100, the piston rod 10 moves upward, the bottom chamber 3 expands, and the lift cylinder 100 extends, returning to the state shown in Figure 3(a). When another impact is applied to the fork 80, the above operations shown in Figures 3(a)-(c) are repeated.

[0029] Here, it is conceivable that the fluid pressure cylinder unit 101 uses an accumulator filled with high-pressure gas instead of the shock absorber 40 to absorb the impact applied to the fork 80. However, due to legal restrictions on high-pressure gas, it is not easy to transport an accumulator filled with high-pressure gas, and it is also difficult to transport and use a gas cylinder for the high-pressure gas to be sealed in the accumulator, and there is also the problem that government approval is required. Therefore, such a fluid pressure cylinder unit 101 is difficult to handle.

[0030] In contrast to this, in the fluid pressure cylinder unit 101 of this embodiment, as described above, the shock absorber 40 absorbs the impact on the fork 80, rather than the accumulator filled with high-pressure gas. Therefore, the fluid pressure cylinder unit 101 is easy to handle.

[0031] Furthermore, the communication passage 60 has an orifice 61 that provides resistance to the flow of hydraulic oil, thereby exerting a damping force. Specifically, when the piston rod 50 of the shock absorber 40 moves upward and the pressure in the second pressure chamber 42 increases, the orifice 61 provides resistance to the hydraulic oil moving from the second pressure chamber 42 to the first pressure chamber 43 through the communication passage 60, thereby attenuating the impact. This allows the orifice 61 to absorb the impact while attenuating the impact, thereby more effectively absorbing the impact. Furthermore, when the shock absorber 40 absorbs the impact on the fork 80, the shock absorber 40 repeatedly extends and contracts, causing the piston rod 50 to repeatedly reciprocate. This in turn causes the piston rod 10 of the lift cylinder 100 to repeatedly reciprocate, which could potentially cause the fork 80 to vibrate. However, the reciprocating motion of the piston rod 50 is damped by the orifice 61, thereby suppressing the vibration of the fork 80.

[0032] Furthermore, by providing the rod 52 of the shock absorber 40 in the second pressure chamber 42, the pressure-receiving areas of the piston 51 facing the first pressure chamber 43 and the second pressure chamber 42 are different. Specifically, the pressure-receiving area of ​​the piston 51 facing the first pressure chamber 43 is larger than the pressure-receiving area facing the second pressure chamber 42 by the cross-sectional area of ​​the rod 52. This makes it easier for the piston 51 to move in response to pressure changes in the first pressure chamber 43 and the second pressure chamber 42, increasing the amount of movement of the piston 51. This increases the amount of movement of the piston rod 10 of the lift cylinder 100, and more effectively absorbs impacts applied to the fork 80.

[0033] In addition, since the shock absorber 40 is connected to the supply / discharge passage 20, it can be attached as an attachment to the existing lift cylinder 100. Therefore, it can be easily replaced with an accumulator, making it easy to handle.

[0034] Furthermore, the shock absorber 40 is provided alongside the lift cylinder 100 in the supply / discharge passage 20. Therefore, the fluid pressure cylinder unit 101 can be made compact.

[0035] The strength (spring constant) of the spring 70 is set, for example, so that when an impact is applied to the fork 80, the bottom chamber 3 of the lift cylinder 100 contracts and the piston 51 moves to an amount that can absorb the impact.

[0036] According to the above embodiment, the following advantageous effects are achieved.

[0037] In the fluid pressure cylinder unit 101, when an impact is applied to the fork 80, the bottom chamber 3 becomes highly pressurized, and the first pressure chamber 43, which is in communication with the bottom chamber 3, becomes highly pressurized. As a result, hydraulic oil moves between the first pressure chamber 43 and the second pressure chamber 42 through the communication passage 60, and the piston 51 of the shock absorber 40 moves, thereby contracting the bottom chamber 3. This absorbs the impact applied to the fork 80. In this way, in the fluid pressure cylinder unit 101, the impact applied to the fork 80 is absorbed by the shock absorber 40 rather than by an accumulator filled with high-pressure gas, making it easy to handle.

[0038] 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 example with the configuration described in the above embodiment, or to combine the configurations described in the different modified examples below.

[0039] <Variation 1> In the above embodiment, the bottom chamber 3 of the lift cylinder 100 communicates with the first pressure chamber 43 through the supply / discharge passage 20. However, as shown in FIG. 4 , the bottom chamber 3 may communicate with the second pressure chamber 42 through the supply / discharge passage 20. When an impact force F is applied to the fork 80, the pressure in the bottom chamber 3 and the second pressure chamber 42 communicating with the bottom chamber 3 increases, and accordingly, the pressure in the first pressure chamber 43 communicating with the second pressure chamber 42 also increases. When the load due to the pressure in the first pressure chamber 43 exceeds the resultant force of the load due to the pressure in the second pressure chamber 42 and the biasing force of the spring 70, hydraulic oil in the second pressure chamber 42 moves to the first pressure chamber 43 through the communication passage 60 and the orifice 61, moving the piston rod 50 upward and extending the shock absorber 40. Then, hydraulic oil is guided from the second pressure chamber 42 to the bottom chamber 3 through the supply / discharge passage 20, expanding the bottom chamber 3 and extending the lift cylinder 100, thereby absorbing the impact applied to the fork 80. After the shock is absorbed, the piston rod 50 moves downward due to the decrease in pressure in the first pressure chamber 43 and the biasing force of the spring 70, and the shock absorber 40 contracts.

[0040] In the above embodiment and this modified example, rod 52 is provided to extend in the direction (upward in FIGS. 1 and 4) in which piston 51 moves first when an impact is applied to fork 80. In other words, rod 52 is provided so that the pressure-receiving area of ​​piston 51 in the direction in which piston 51 moves first when an impact is applied to fork 80 (toward second pressure chamber 42) is reduced, making it easier for piston 51 to move.

[0041] <Variation 2> In the above embodiment, the inside of the cylinder 41 of the shock absorber 40 is divided by the piston 51 into a first pressure chamber 43 and a second pressure chamber 42. In addition, as shown in FIG. 5 , the second pressure chamber 42 may be divided by the rod 52 into a third pressure chamber 42a and a fourth pressure chamber 42b. The third pressure chamber 42a is divided by the piston 51, the outer circumferential surface of the rod 52, and the cylinder 41, and communicates with a tank (not shown) or the atmosphere through a passage (not shown). The fourth pressure chamber 42b is divided by the end surface of the rod 52 and the cylinder 41. In this configuration, the communication passage 60 connects the first pressure chamber 43 and the fourth pressure chamber 42b, and the spring 70 is provided in the fourth pressure chamber 42b and biases the piston 51 in a direction that contracts the first pressure chamber 43. This configuration also achieves the same effects as the above embodiment.

[0042] <Variation 3> In the above embodiment, the piston 51 is formed in a disk shape. However, this is not limiting, and the piston 51 may be formed in a concave shape as shown in FIG. 6. In this configuration, the base end (upper end in FIG. 6) of the rod 52 is fixed to a device or the like, and the tip end (lower end in FIG. 6) is provided in the concave portion of the piston 51. The second pressure chamber 42 is defined by the concave portion of the piston 51 and the tip end of the rod 52. Even with this configuration, the same effects as those of the above embodiment can be achieved.

[0043] <Variation 4> In the above embodiment, the shock absorber 40 is provided separately from the lift cylinder 100. In contrast, in a fluid pressure cylinder unit 401 according to Modification 4, as shown in FIG. 7 , the shock absorber 40 is provided inside the piston rod 310 of the lift cylinder 400. Specifically, a cylinder 41 of the shock absorber 40 is provided as a space inside the piston rod 310, and a piston rod 50 and a spring 70 are provided inside the cylinder 41. In addition, the supply / discharge passage 20 has a first supply / discharge passage 20a connected to the bottom chamber 3 of the lift cylinder 100 and a second supply / discharge passage 20b connecting the bottom chamber 3 with the first pressure chamber 43 of the shock absorber 40. Through the supply / discharge passage 20, hydraulic oil is supplied to the bottom chamber 3 or discharged from the bottom chamber 3.

[0044] In this configuration, when an impact force F is applied to the fork 80, the pressure in the bottom chamber 3 and the first pressure chamber 43 communicating with the bottom chamber 3 increases, and when the load due to the pressure in the first pressure chamber 43 exceeds the resultant force of the load due to the pressure in the second pressure chamber 42 and the biasing force of the spring 70, the hydraulic oil in the second pressure chamber 42 moves to the first pressure chamber 43 through the communicating passage 60 and the orifice 61, and the piston rod 50 of the shock absorber 40 moves upward. Then, hydraulic oil is guided from the bottom chamber 3 to the first pressure chamber 43 through the second supply / discharge passage 20b, the bottom chamber 3 contracts, and the lift cylinder 100 contracts, absorbing the impact applied to the fork 80. By providing the shock absorber 40 inside the piston rod 310 in this way, the fluid pressure cylinder unit 401 can be made compact.

[0045] The shock absorber 40 may also be provided inside the cylinder tube 1 of the lift cylinder 100. Specifically, the shock absorber 40 may be provided on the bottom chamber 3 side inside the cylinder tube 1 of the lift cylinder 100. The shock absorber 40 is provided upside down from the orientation shown in FIGS. 1 and 7 so that the first pressure chamber 43 communicates with the bottom chamber 3. The supply / discharge passage 20 has a first supply / discharge passage 20a connected to the bottom chamber 3 of the lift cylinder 100 and a second supply / discharge passage 20b communicating between the bottom chamber 3 and the first pressure chamber 43, and the supply / discharge passage 20 supplies hydraulic oil to the bottom chamber 3 or discharges hydraulic oil from the bottom chamber 3. Even with this configuration, the fluid pressure cylinder unit 401 can be made compact.

[0046] <Variation 5> In the above embodiment, the communication passage 60 has the orifice 61 that provides resistance to the flow of hydraulic oil, and the damping force is exerted by the orifice 61. However, the orifice 61 is not an essential component, and the communication passage 60 does not need to have the orifice 61 as long as the shock absorber 40 can absorb the impact. Also, a relief valve may be provided instead of the orifice 61.

[0047] <Variation 6> In the above embodiment, the communication passage 60 is provided in the piston 51, and the spring 70 is provided in the second pressure chamber 42. However, the present invention is not limited to this, and the communication passage 60 may be provided in the cylinder 41 or outside the cylinder 41 as long as it provides communication between the first pressure chamber 43 and the second pressure chamber 42. Furthermore, the spring 70 may be provided somewhere other than the second pressure chamber 42 or outside the cylinder 41 as long as it biases the piston 51 in the direction that contracts the first pressure chamber 43. For example, the spring 70 may be provided in the first pressure chamber 43 in a state extended beyond its natural length.

[0048] <Variation 7> In the above embodiment, the piston 51 is provided with the communication passage 60 having the orifice 61. In addition to this, the piston 51 may be provided with a passage having a check valve that allows the flow of hydraulic oil only from the first pressure chamber 43 to the second pressure chamber 42.

[0049] <Variation 8> In the above embodiment, the fluid pressure cylinder is a lift cylinder 100 that raises and lowers the forks 80 of a forklift. However, the fluid pressure cylinder is not limited to this, and may be a cylinder mounted on industrial machinery other than a forklift. The fluid pressure cylinder may also be a double-rod cylinder. One or more fluid pressure cylinders may be provided in the fluid pressure cylinder unit 101.

[0050] The configuration, operation, and effects of the embodiment of the present invention configured as above will be described below.

[0051] The fluid pressure cylinder unit 101, 401 includes a lift cylinder 100, 400 as a fluid pressure cylinder having a cylinder tube 1, a piston rod 10, 310 that is reciprocatably provided within the cylinder tube 1 and divides the interior of the cylinder tube 1 into a rod chamber 2 and a bottom chamber 3, and that drives a fork 80 as a driven object, a supply and discharge passage 20 that is connected to the bottom chamber 3 and supplies working fluid to the bottom chamber 3 or discharges working fluid from the bottom chamber 3, and a shock absorber 40 connected to the supply and discharge passage 20, and the shock absorber 40 includes a cylinder 41, a piston 51 that is reciprocatably provided within the cylinder 41 and divides the interior of the cylinder 41 into a first pressure chamber 43 and a second pressure chamber 42, a communicating passage 60 that communicates between the first pressure chamber 43 and the second pressure chamber 42, and a spring 70 as a biasing member that biases the piston 51 in a direction that contracts the first pressure chamber 43, and the bottom chamber 3 is in communication with the first pressure chamber 43 or the second pressure chamber 42 through the supply and discharge passage 20.

[0052] In this configuration, when an impact is applied to the fork 80, the bottom chamber 3 becomes highly pressurized, and the first pressure chamber 43, which is in communication with the bottom chamber 3, becomes highly pressurized. As a result, working fluid moves between the first pressure chamber 43 and the second pressure chamber 42 through the communication passage 60, and the piston 51 of the shock absorber 40 moves, changing the volume of the bottom chamber 3. This absorbs the impact applied to the fork 80. In this way, in the fluid pressure cylinder units 101, 401, the shock applied to the fork 80 is absorbed by the shock absorber 40 rather than by an accumulator filled with high-pressure gas, making them easy to handle.

[0053] In the fluid pressure cylinder units 101 and 401, the communication passage 60 has an orifice 61 as a throttle portion that applies resistance to the flow of the working fluid.

[0054] In this configuration, the orifice 61 exerts a damping force, so that the shock applied to the fork 80 is absorbed more effectively.

[0055] In the fluid pressure cylinder units 101 and 401, the shock absorber 40 has a rod 52 with a piston 51 connected to the tip thereof and provided reciprocally within the cylinder 41, and the rod 52 is provided in the second pressure chamber .

[0056] In this configuration, the pressure-receiving areas of the piston 51 facing the first pressure chamber 43 and the second pressure chamber 42 differ due to the rod 52. This makes it easier for the piston 51 to move in response to pressure changes in the first pressure chamber 43 and the second pressure chamber 42, and impacts applied to the fork 80 are absorbed more effectively.

[0057] In addition, in the fluid pressure cylinder unit 401 , the shock absorber 40 is provided inside the lift cylinder 400 .

[0058] With this configuration, the fluid pressure cylinder unit 401 can be made compact.

[0059] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments. [Explanation of symbols]

[0060] 1...cylinder tube, 2...rod chamber, 3...bottom chamber, 10,310...piston rod, 20...supply / discharge passage, 40...shock absorber, 41...cylinder, 42...second pressure chamber, 43...first pressure chamber, 51...piston, 52...rod, 60...communicating passage, 61...orifice (throttling portion), 70...spring (urging member), 80...fork (driven object), 100,400...lift cylinder (fluid pressure cylinder), 101,401...fluid pressure cylinder unit

Claims

1. A fluid pressure cylinder unit, a fluid pressure cylinder having a cylinder tube and a piston rod reciprocally disposed within the cylinder tube and dividing the interior of the cylinder tube into a rod chamber and a bottom chamber, the fluid pressure cylinder driving an object to be driven; a supply / discharge passage connected to the bottom chamber for supplying a working fluid to the bottom chamber or discharging a working fluid from the bottom chamber; a shock absorber connected to the supply / discharge passage, The buffer comprises: A cylinder; a piston that is reciprocally disposed within the cylinder and divides the interior of the cylinder into a first pressure chamber and a second pressure chamber; a communication passage that communicates the first pressure chamber with the second pressure chamber; a biasing member that biases the piston in a direction that reduces the size of the first pressure chamber, the shock absorber is actuated only by the flow of the working fluid through the supply and discharge passage, The bottom chamber is a fluid pressure cylinder unit that communicates with the first pressure chamber or the second pressure chamber through the supply / discharge passage.

2. 2. The fluid pressure cylinder unit according to claim 1, 10. A fluid pressure cylinder unit, wherein the communication passage has a throttle portion that applies resistance to the flow of the working fluid.

3. 2. The fluid pressure cylinder unit according to claim 1, the shock absorber has a rod, the piston being connected to a tip thereof, and the rod being reciprocally movable within the cylinder; The fluid pressure cylinder unit is characterized in that the rod is provided in the second pressure chamber.

4. 2. The fluid pressure cylinder unit according to claim 1, The fluid pressure cylinder unit is characterized in that the shock absorber is provided inside the fluid pressure cylinder.

5. A fluid pressure cylinder unit as described in claim 1, The communication passage passes through the piston and communicates the first pressure chamber with the second pressure chamber.

6. A fluid pressure cylinder unit as described in claim 1, The shock absorber is a fluid pressure cylinder unit provided adjacent to the fluid pressure cylinder.

Images