TWI513910B - Fluid pressure cylinder - Google Patents

Description

Fluid pressure cylinder

The present invention relates to a fluid pressure cylinder that displaces a piston in an axial direction under the supply of a pressurized fluid.

Conventionally, a conveying means for a workpiece or the like is a fluid pressure cylinder having, for example, a piston that is displaced by the supply of a pressure fluid.

In recent years, such fluid pressure cylinders have had a need to reduce the consumption of pressure fluids used from the viewpoint of energy saving. In order to cope with such a demand, for example, in the fluid pressure cylinder disclosed in Japanese Laid-Open Patent Publication No. Hei 8-42511, the supply portion for supplying the pressure fluid and the two cylinder chambers are connected via the switching valve, and the piston is displaced in a certain direction. In the case, under the switching action of the switching valve, the pressure fluid is supplied from the pressure fluid supply source to the one cylinder chamber at a desired pressure, thereby displace the piston, thereby displacing the piston rod and being housed inside the cylinder. .

On the other hand, when the piston is displaced in the other direction, the pressure fluid of the one cylinder chamber is supplied to the other cylinder chamber by switching the switching valve, and the piston passes through the pressure receiving area with respect to the one cylinder chamber. The other end face of the aforementioned piston, which has a larger end face, is urged and displaced in the other direction. As such, it is common to use a pressurized fluid that is vented to the outside to displace the piston in the other direction to reduce the amount of pressure fluid consumed.

The fluid pressure cylinder as described above operates the piston and the piston rod under the supply of the pressurized fluid when the piston rod is housed inside the cylinder, and conversely, the piston rod protrudes from the cylinder. At the time of introduction, the piston and the piston rod are operated by the pressure fluid exhausted from one of the cylinder chambers. However, for example, when the workpiece is conveyed by the fluid pressure cylinder, it may be conveyed in a direction away from the cylinder tube by the pushing operation of the piston rod. In this case, the pressure of the pressure fluid when the piston is displaced toward the pressing side is the pressure fluid to be exhausted, and thus the thrust sufficient to push the aforementioned workpiece by the piston rod cannot be obtained. Therefore, although the fluid pressure cylinder can reduce the consumption of the pressure fluid, it is difficult to displace the workpiece or the like by the desired thrust.

SUMMARY OF THE INVENTION A general object of the present invention is to provide a fluid pressure cylinder which can reduce the consumption of a pressure fluid for displacing a piston to save energy, and can reliably and accurately displace the piston by a desired thrust.

The fluid pressure cylinder of the present invention comprises: a cylinder body having a plurality of ports for supplying a pressurized fluid; and a cylinder chamber capable of introducing the pressure fluid from the port; and being disposed inside the cylinder chamber so as to be free along an axial direction a piston that is displaced; a first rod that is coupled to one end surface side of the piston; and a second rod that is coupled to the other end surface side of the piston, and that supports the piston rod that is freely displaceable; a first pressure receiving surface formed on one end surface side of the piston and facing one of the cylinder chambers, and a second pressure receiving surface formed on the other end surface side of the piston and facing the other cylinder chamber, and having an area larger than the first pressure receiving surface Large second pressure receiving surface, When the pressure fluid is supplied to the one cylinder chamber, the piston and the second rod are displaced toward one side, and the piston and the first rod are supplied by supplying the pressure fluid of the one cylinder chamber to the other cylinder chamber. Displace toward the other side.

According to the invention, the piston constituting the fluid pressure cylinder includes a first pressure receiving surface facing the one cylinder chamber of the cylinder body and applying the pressure of the pressure fluid, and an area facing the other cylinder chamber with respect to the first receiving chamber The second pressure receiving surface having a large pressing surface is supplied to the one cylinder chamber by the pressure fluid, and the piston and the second rod are displaced toward the first pressure receiving surface on one side, and the one cylinder is displaced by the one side. The pressure fluid of the chamber is supplied to the other cylinder chamber to displace the piston and the first rod toward the other side.

Therefore, when the piston is returned to the other side, the pressure fluid presses the piston through the second pressure receiving surface having a large area, whereby the piston and the first rod can be reliably displaced toward the other side.

As a result, when the piston is displaced toward one side, the pressure fluid supplied from the pressure fluid supply source can be displaced by the desired pressing force, and the piston can be restored toward the other side. When the pressure fluid is again supplied to the other cylinder chamber, the consumption of the pressure fluid can be further reduced, and energy saving can be achieved.

The above objects, features, and advantages will be apparent from the description of the embodiments illustrated in the appended claims.

10‧‧‧ fluid pressure cylinder

12‧‧‧Cylinder tube

14‧‧‧1st end cap

16‧‧‧2nd end cap

18‧‧‧Piston

18a‧‧‧1st pressure surface

18b‧‧‧2nd pressure-receiving surface

20‧‧‧1st piston rod (1st rod)

22‧‧‧2nd piston rod (2nd rod)

24‧‧‧ cylinder bore

26‧‧‧Supply port

28‧‧‧Exhaust port

30a, 30b‧‧‧ piping

32‧‧‧Switching mechanism

34‧‧‧ card stop ring

36‧‧‧1st cylinder room

38‧‧‧2nd cylinder room

40‧‧‧1st hole

42‧‧‧2nd hole

44‧‧‧ bushing

46‧‧‧ rod liner

48‧‧‧ piston gasket

50‧‧‧through holes

52‧‧‧1

54‧‧‧Part 2

56‧‧‧ screw holes

58‧‧‧ Small Trails Department

60‧‧‧Great Path Department

62‧‧‧ Screw Department

64‧‧‧5-port solenoid valve

66‧‧‧Pressure fluid supply

68‧‧‧Supply piping

70‧‧‧1st port

72‧‧‧2nd port

74‧‧‧3rd port

76‧‧‧Port 4

78‧‧‧5th port

D, d1, d2‧‧‧ diameter

S1‧‧‧1st pressure area

S2‧‧‧2nd compression area

Fig. 1 is a cross-sectional view showing the entire fluid pressure cylinder according to an embodiment of the present invention.

Fig. 2 is an overall cross-sectional view showing a state in which the piston is displaced toward the first end cover side and is in an initial position in contact with the fluid pressure cylinder of Fig. 1 .

Fig. 3 is an overall cross-sectional view showing a state in which the piston is displaced toward the second end cover side and the position of the displacement end is abutted in the fluid pressure cylinder of Fig. 1 .

Fig. 4 is a circuit diagram of a fluid pressure cylinder including Fig. 1 for switching a supply state of a pressure fluid with respect to a supply state of the fluid pressure cylinder.

As shown in FIGS. 1 to 3, the fluid pressure cylinder 10 includes a cylindrical cylinder tube 12 and first and second end covers 14 and 16 attached to both end portions of the cylinder tube 12. The inside of the cylinder tube 12 is provided with a piston 18 that is freely displaceable, and first and second piston rods 20 and 22 that are coupled to the center of the piston 18. Further, the fluid pressure cylinder 10 is a double rod type in which a pair of first and second piston rods 20 and 22 are coupled to both end faces of the piston 18.

The cylinder tube 12 has, for example, a substantially rectangular cross section, and a cylinder bore 24 having a circular cross section is formed in the axial direction (arrows A and B). Further, the cylinder bore 24 is formed in the same cross-sectional shape along the axial direction of the cylinder tube 12.

Further, on the outer peripheral side of the cylinder tube 12, an opening port of the supply port 26 and the exhaust port 28 is formed at a position near one end portion and the other end portion, respectively. Further, as shown in FIG. 4, the supply port 26 and the exhaust port 28 are connected to the pipes 30a and 30b, respectively, and the switching mechanism 32 for switching the supply state of the pressure fluid is connected via the pipes 30a and 30b. Narrative).

The first and second end covers 14 and 16 are respectively attached to the inside of the cylinder bore 24 at one end portion and the other end portion of the cylinder tube 12, and are respectively engaged with the step of the cylinder bore 24 at a portion where the diameter is expanded outward in the radial direction. After the portion is engaged with the inner circumferential surface of the cylinder bore 24, the first and second end covers 14, 16 are fixed to the cylinder bore 24, respectively. Moreover, in the cylinder tube 12, between the first end cover 14 and the piston 18 A first cylinder chamber 36 that communicates with the supply port 26 is formed, and a second cylinder chamber 38 that communicates with the exhaust port 28 is formed between the second end cover 16 and the piston 18.

Further, first and second rod holes 40 and 42 penetrating in the axial direction are formed in the center portions of the first and second end covers 14 and 16, respectively, in the first and second rod holes 40 and 42. A bushing 44 and a rod spacer 46 are attached to the circumferential surface, respectively. Further, the first and second piston rods 20 and 22 are inserted into the first and second rod holes 40 and 42 respectively, and are supported by the bushings 44 so as to be freely displaceable along the axial direction while being rod-lined. The pad 46 is slidably prevented from leaking the pressure fluid between the first and second piston rods 20 and 22 and the first and second end covers 14 and 16, respectively.

The piston 18 is formed in, for example, a disk shape having a predetermined thickness, and the piston pad 48 is attached to the outer peripheral surface thereof via an annular groove. Further, the piston liner 48 is slidably attached to the inner circumferential surface of the cylinder bore 24 to prevent leakage of pressure fluid between the piston 18 and the cylinder tube 12.

Further, a through hole 50 penetrating in the axial direction (arrows A and B directions) is formed in the center portion of the piston 18, and the small diameter portion 58 to be described later for the second piston rod 22 is inserted, and the first end cover is formed. The first end portion 52 for engaging the first piston rod 20 is formed in a recessed end surface of the 14 side (arrow A direction). Further, the first stage portion 52 is formed to be expanded in diameter with respect to the through hole 50.

On the other hand, the other end surface of the piston 18 on the side of the second end cover 16 (in the direction of the arrow B) is formed with a second step 54 which is enlarged in diameter with respect to the through hole 50 and recessed at a predetermined depth, and is provided for The second piston rod 22 is engaged.

The first and second piston rods 20 and 22 are each formed of a linear shaft body, and are coupled to the coaxial body so as to sandwich the piston 18, and are provided in the first piston rod (first rod) 20 Forming the first end cover 14 side (arrow A direction), The second piston rod (second rod) 22 is formed on the second end cover 16 side (arrow B direction).

The first piston rod 20 is formed to have substantially the same diameter along the axial direction, and one end portion thereof is inserted into the first rod hole 40 of the first end cover 14 to be supported to be freely displaceable, and the other end portion is formed to be available for the first portion. The opening port of the screw hole 56 to which the screw portion 62 of the piston rod 22 is screwed is inserted into and engaged with the first step portion 52 of the piston 18.

The second piston rod 22 is a small diameter portion 58 formed at one end portion thereof and inserted through the through hole 50 of the piston 18, and a large diameter formed on the other end portion side and formed with a large diameter with respect to the small diameter portion 58. The portion 60 is configured such that the outer peripheral surface of the small diameter portion 58 has a screw portion 62 in which a spiral is drawn. Further, when the screw portion 62 is screwed into the screw hole 56 of the first piston rod 20 in a state of being inserted into the through hole 50 of the piston 18, the first piston rod 20 and the second piston rod 22 are caught. The pistons 18 are coupled to each other. At this time, since the first and second piston rods 20 and 22 are engaged with the piston 18 via the first and second step portions 52 and 54, they can be integrally coupled while being coaxial with each other.

Further, the large diameter portion 60 of the second piston rod 22 is such that one end portion thereof is engaged with the second step portion 54 of the piston 18, and the other end portion is inserted into the second rod hole 42 of the second end cover 16, This support can be freely displaced along the axis.

Further, the diameter d1 of the first piston rod 20 is formed to be large (d1>d2) with respect to the diameter d2 of the large diameter portion 60 of the second piston rod 22. Further, a first pressure receiving surface 18a is formed on one end surface of the piston 18 facing the first cylinder chamber 36, and a second pressure receiving surface 18b is formed on the other end surface of the piston 18 facing the second cylinder chamber 38. The second pressure receiving area S2 of the second pressure receiving surface 18b is formed to be large with respect to the first pressure receiving area S1 of the first pressure receiving surface 18a (S2>S1).

That is, the diameter d1 of the first piston rod 20 is relative to the second piston. Since the diameter d2 of the large diameter portion 60 of the rod 22 is set to be large, the first and second pressure receiving areas S1 and S2 which are different from the diameter D of the piston 18 are the second pressure receiving area S2 with respect to the first The pressed area S1 is large (D-d1 < D-d2).

Next, the switching mechanism 32 connected to the supply port 26 and the exhaust port 28 of the fluid pressure cylinder 10 will be described with reference to FIG.

The switching mechanism 32 is constituted by, for example, a five-port solenoid valve 64 that can switch the supply state of the pressure fluid to the supply port 26 and the exhaust port 28 of the fluid pressure cylinder 10 in accordance with a control signal from a controller (not shown). : a first port 70 connected to the pressure fluid supply source 66 via the supply pipe 68; a second port 72 connected to the exhaust port 28 of the cylinder tube 12; a third port 74 that blocks communication with the outside; and a pipe 30a via the pipe 30a The fourth port 76 to which the supply port 26 of the cylinder tube 12 is connected; and the fifth port 78 in an open state in communication with the outside. Further, in the OFF state in which the switching mechanism 32 does not output the control signal, by connecting the first port 70 to the fourth port 76, the pressure fluid from the pressure fluid supply source 66 is supplied to the supply port 26 by Connecting the second port 72 to the fifth port 78 forms an atmosphere open state in which the exhaust port 28 communicates with the outside.

On the other hand, when the switching mechanism 32 is switched to the ON state by a control signal from a controller (not shown), the pressure fluid is supplied from the pressure fluid supply source 66 by connecting the first port 70 to the third port 74. The supply of the fluid pressure cylinder 10 is blocked, and by connecting the second port 72 to the fourth port 76, the supply port 26 is in communication with the exhaust port 28. Further, the switching mechanism 32 is mounted, for example, on the upper surface of the cylinder tube 12 in which the supply port 26 and the opening port of the exhaust port 28 are formed.

The fluid pressure cylinder 10 of the embodiment of the present invention is basically as above The mode configuration will be described next with respect to its actions and effects. Here, the initial state will be described in the state in which the pressure fluid of the first cylinder chamber 36 supplies the pressure fluid to the second cylinder chamber 38 under the switching action of the switching mechanism 32, and as shown in FIG. 2 As shown in the figure, the piston 18 is displaced toward the first end cover 14 side (in the direction of the arrow A), and the second piston rod 22 is housed inside the cylinder tube 12.

In this initial state, by inputting a control signal to the switching mechanism 32 from a controller (not shown), the switching mechanism 32 switches to connect the first port 70 to the fourth port 76, thereby providing a pressure fluid supply source. 66 is in communication with the supply port 26, and the second port 72 is connected to the fifth port 78 to form an atmosphere open state that communicates with the outside. As a result, the pressurized fluid is supplied from the supply port 26 to the first cylinder chamber 36, and the piston 18 is displaced toward the second end cover 16 side (arrow B direction), thereby causing the first and second piston rods 20 to be displaced. 22 is displaced integrally. On the other hand, the pressure fluid remaining in the second cylinder chamber 38 is exhausted from the fifth port 78 to the outside through the exhaust port 28, the pipe 30b, and the second port 72.

As a result, the second piston rod 22 is displaced so as to gradually protrude outward with respect to the second end cover 16, and the first piston rod 20 is slowly housed in the cylinder tube by the first end cover 14. The internal displacement of the 12 way. Further, as shown in Fig. 3, the other end surface of the piston 18 abuts against the second end cover 16 to form a displacement end position, for example, by a conveying device coupled to the end portion of the second piston rod 22, the workpiece is It is transported to a predetermined location. In other words, since the fluid pressure cylinder 10 is displaced from the initial position to the displacement end position, the hydraulic pressure generated by the second piston rod 22 can be pushed out in the direction away from the fluid pressure cylinder 10 (arrow B direction). A workpiece not shown.

Moreover, in the case of using the first piston rod 20, due to the fluid pressure cylinder 10 is displaced from the initial position to the displacement end position, and the workpiece (not shown) can be conveyed toward the fluid cylinder 10 side (arrow B direction) by the tensile force generated by the first piston rod 20.

When the piston 18 is displaced toward the first end cover 14 (in the direction of the arrow A) and returned to the initial position, the control signal is output to the switching mechanism 32 by stopping the controller (not shown). The switching mechanism 32 is switched such that the first port 70 is connected to the third port 74, and the supply of the pressurized fluid from the pressurized fluid supply source 66 is blocked by the switching mechanism 32, and the second port 72 and the fourth port are made. The port 76 is connected and connected. Thereby, the pressure fluid in the first cylinder chamber 36 is supplied from the exhaust port 28 to the second cylinder chamber 38 through the supply port 26, the pipe 30a, and the switching mechanism 32. Further, in this case, the pressure of the pressure fluid remaining in the first cylinder chamber 36 is the same as the pressure of the pressure fluid supplied to the second cylinder chamber 38.

In the first and second cylinder chambers 36 and 38, the pressure receiving area of the piston 18 that is pressed by the pressure fluid is the second pressure receiving area of the second pressure receiving surface 18b on the second cylinder chamber 38 side. S2 is set to be larger than the first pressure receiving area S1 of the first pressure receiving surface 18a on the side of the first cylinder chamber 36. Therefore, the piston 18 is pressed toward the first end cover 14 side (arrow A direction). Since the pressing force is large, the piston 18 and the second piston rod 22 are displaced toward the first end cover 14 side (arrow A direction). Next, one end surface of the piston 18 abuts against the first end cover 14 to return to the initial position (see FIG. 2).

In this case, the pressing force applied to the piston 18 is the pressure fluid that is exhausted from the first cylinder chamber 36 to the second cylinder chamber 38, and therefore is smaller than the pressing force when the piston 18 is moved to the displacement end position. By. Therefore, in the fluid pressure cylinder 10, the pressing force when the piston 18 is displaced from the initial position to the displacement end position (pull When the workpiece is conveyed and returned from the displacement end position to the initial position, the workpiece is not conveyed, but only the displacement of the piston 18 using the pressurized fluid that is exhausted is performed.

As described above, in the present embodiment, in the fluid pressure cylinder 10 that displaces the piston 18 by the supply of the pressurized fluid, the first cylinder chamber 36 side to which the pressure fluid is supplied when the piston 18 is displaced toward the displacement end position is used. The first pressure receiving area S1 of the first pressure receiving surface 18a is set to be a second pressure receiving area of the second pressure receiving surface 18b on the second cylinder chamber 38 side where the pressure fluid is supplied when the piston 18 is returned to the initial position. S2 is small (S1 < S2). Therefore, when the piston 18 is displaced from the initial position to the displacement end position by the pressure fluid supplied to the first cylinder chamber 36, the piston 18 is directed toward the second end cover 16 by the desired pressing force (arrow B direction). The second piston rod 22 is pushed by the second piston rod 22 in a direction (arrow B direction) away from the second end cover 16 by a predetermined pressing force, and is displaced from the other. When the terminal position is restored to the initial position, the pressure fluid supplied to the first cylinder chamber 36 is supplied (exhausted) to the second cylinder chamber 38 by the switching action of the switching mechanism 32, whereby the first The area difference (S2-S1) between the pressure area S1 and the second pressure receiving area S2 is such that the piston 18 is pushed and displaced so as to return to the initial position.

As described above, when the piston 18 is returned to the initial position, the pressure fluid supplied to the first cylinder chamber 36 is not exhausted to the outside, but can be supplied to the second cylinder chamber 38 and used for displacement of the piston 18. As a result, when the piston 18 is displaced from the displacement end position to the initial position, the consumption of the pressure fluid can be further reduced as compared with the case where the pressure fluid is again supplied to the second cylinder chamber 38, and energy saving can be achieved.

In other words, in the piston 18, the difference in area is set by the first pressure receiving area S1 of the first pressure receiving surface 18a and the second pressure receiving area S2 of the second pressure receiving surface 18b. (S1 < S2), when a pressure fluid is supplied to the first and second cylinder chambers 36, 38, a pressure difference can be set to the pressing force of the pressing piston 18, and the piston 18 is biased toward the pressure by the pressure difference. The initial position side (arrow A direction) is displaced.

Further, since the fluid pressure cylinder 10 has a double rod type having the first piston rod 20 and the second piston rod 22 connected to one end surface and the other end surface of the piston 18, for example, when a workpiece (not shown) is conveyed, When the conveyance is performed by pushing in the direction away from the fluid pressure cylinder 10 (the direction of the arrow B), the second piston rod 22 displaced toward the pressing side by the pressure fluid from the pressure fluid supply source 66 can be used. The workpiece is pushed and thus conveyed with a desired pressing force (thrust) reliably and with high precision.

On the other hand, in the case where the workpiece is to be conveyed by stretching the workpiece toward the fluid pressure cylinder 10 side (arrow B direction), it is possible to be displaced toward the tensile side by the pressure fluid from the pressure fluid supply source 66. Since the piston rod 20 is stretched, it is conveyed reliably and with high precision with a desired tensile force (thrust).

In other words, by appropriately selecting one of the first and second piston rods 20 and 22 depending on the conveyance direction of the workpiece, it is not necessary to prepare a plurality of fluid pressure cylinders, and it is possible to reliably and accurately convey the desired thrust. Workpiece.

Further, the pressing force required to return the piston 18 from the displacement end position to the initial position may be such that the piston 18 can be displaced toward the initial position and displaced, and the displacement can be displaced more than the workpiece. The pushing force required to the aforementioned displacement end position is small. Therefore, the piston 18 can be sufficiently displaced toward the initial position by the pressure of the pressure fluid supplied (exhausted) from the first cylinder chamber 36 to the second cylinder chamber 38.

Furthermore, since the first and second piston rods 20 of different diameters can be utilized, Since the area difference (S2-S1) between the first pressure receiving area S1 and the second pressure receiving area S2 is set, the diameter of the first and second piston rods 20 and 22 can be changed, and the piston 18 can be freely set. The displacement speed (thrust) when the initial position is displaced toward the displacement end position, and the displacement speed (thrust) when the piston 18 is restored from the displacement end position toward the initial position. That is, the displacement speed (thrust) of the piston 18 can be freely set by replacing the other first piston rod 20 and the second piston rod 22 having different diameters.

Further, the fluid pressure cylinder of the present invention is not limited to the above embodiment, and of course, various configurations can be employed without departing from the gist of the present invention.

10‧‧‧ fluid pressure cylinder

12‧‧‧Cylinder tube

14‧‧‧1st end cap

16‧‧‧2nd end cap

18‧‧‧Piston

18a‧‧‧1st pressure surface

18b‧‧‧2nd pressure-receiving surface

20‧‧‧1st piston rod (1st rod)

22‧‧‧2nd piston rod (2nd rod)

24‧‧‧ cylinder bore

26‧‧‧Supply port

28‧‧‧Exhaust port

34‧‧‧ card stop ring

36‧‧‧1st cylinder room

38‧‧‧2nd cylinder room

40‧‧‧1st hole

42‧‧‧2nd hole

44‧‧‧ bushing

46‧‧‧ rod liner

48‧‧‧ piston gasket

50‧‧‧through holes

52‧‧‧1

54‧‧‧Part 2

56‧‧‧ screw holes

58‧‧‧ Small Trails Department

60‧‧‧Great Path Department

62‧‧‧ Screw Department

D, d1, d2‧‧‧ diameter

S1‧‧‧1st pressure area

S2‧‧‧2nd compression area

Claims (2)

A fluid pressure cylinder having: a plurality of ports (26, 28) having a supply of pressurized fluid, and a cylinder body (36, 38) for introducing a plurality of cylinders (36, 38) of the pressure fluid from the ports (26, 28) 12); a piston (18) that is displaceable in the axial direction inside the cylinder chamber (36, 38); a first rod (20) coupled to one end side of the piston (18), and a second rod (22) coupled to the other end surface side of the piston (20), and supporting the piston rod freely displaceable in the cylinder body (12); forming an axial direction at a central portion of the piston (18) a through hole (50) penetrating the screw portion (62) through which the through hole (50) is inserted into the end portion of the first rod (20) and the second rod (22), and the screw portion (62) a screw hole (56) that is screwed, wherein the first rod (20) and the second rod (22) are connected to each other while being coaxially held via the piston (18); a first pressure receiving surface facing the one cylinder chamber (36) on one end surface side of the piston (18), and a other end surface side of the piston (18) facing the other cylinder chamber (38), and having an area relatively In the first The second pressure receiving surface having a large pressing surface is supplied to the one cylinder chamber (36) by the pressure fluid, and the piston (18) and the second rod (22) are displaced toward one side by the one cylinder The pressure fluid of the chamber (36) is supplied to the other cylinder chamber (38), and the piston (18) and the first rod (20) are displaced toward the other side; the pressure fluid is a pressurized gas; at the aforementioned port (26) , 28) is connected with a switch for switching between the one cylinder chamber (36) and the other cylinder chamber (38) with five fluid inlet and outlet Valve (64). The fluid pressure cylinder according to claim 1, wherein the diameter of the first rod (20) is relatively larger than the diameter of the second rod (22).