Fluid pressure cylinder

Abstract

To provide a fluid pressure cylinder for allowing easy positioning in the radial direction of a lock washer in assembling work.SOLUTION: The fluid pressure cylinder includes a cylinder tube 11 having a tube end face 17 at one end, a rod guide 14 threaded to the cylinder tube 11 and having a guide end face 35 opposed to the tube end face 17, and a lock washer 40 laid between the tube end face 17 and the guide end face 35 for preventing the looseness of the rod guide 14 relative to the cylinder tube 11 by caulking formed by plastic deformation, the rod guide 14 having a washer regulation part for restricting the displacement in the radial direction of the lock washer 40.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] As a prior art for fluid pressure cylinders, for example, a rotation prevention mechanism for a rod cover of a hydraulic cylinder disclosed in Patent Document 1 is known. In the rotation prevention mechanism for a rod cover of a hydraulic cylinder disclosed in Patent Document 1, a notch is formed in the flange of the rod cover, and a notch is formed in the end face of the opening side of the cylinder tube into which the rod cover is fitted. A metal link plate is interposed between the cylinder tube and the flange of the rod cover. Furthermore, a portion of the link plate is bent to engage with the notch on the cylinder tube side and the notch on the rod cover side. This prevents loosening due to rotation of the rod cover.

[0003] In this type of fluid pressure cylinder, as shown in FIG. 9, a cylinder tube 61 of a fluid pressure cylinder 60 and a rod guide 62 corresponding to a rod cover are threadedly engaged with each other, so that a female thread portion 63 is formed near the end of the cylinder tube 61. A male thread portion 64 that can be threadedly engaged with the female thread portion 63 is formed on the outer circumferential surface of the rod guide 62. Incidentally, when machining the male thread portion 64 of the rod guide 62, an annular recess 65 is formed near the end of the outer circumferential surface of the male thread portion 64. The annular recess 65 is a recess formed in the radial direction and is necessary to allow the tool used to machine the male thread portion 64 to escape during machining. A lock washer 66 serving as a rotation stopper is interposed between the cylinder tube 61 and the rod guide 62. A groove 67 corresponding to a notch is formed on the outer periphery of the rod guide 62. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 2-117404 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the fluid pressure cylinder shown in Figure 9 has a problem in that it is difficult to determine the radial position of the lock washer when bending it during assembly. Difficulty in determining the radial position makes it difficult to ensure a sufficient crimping margin when crimping a specific point on the lock washer, reducing the efficiency of the assembly work. While it is possible to make the positioning of the lock washer easier by increasing the outer diameter of the lock washer, a larger lock washer could easily interfere with other objects before the work could begin, potentially resulting in damage.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a fluid pressure cylinder that makes it possible to easily position a lock washer in the radial direction during assembly work. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a fluid pressure cylinder having a cylinder tube having a tube end face at one end, a rod guide that is screwed onto the cylinder tube and has a guide end face that faces the tube end face, and a lock washer that is interposed between the tube end face and the guide end face and prevents loosening of the rod guide relative to the cylinder tube by crimping formed by plastic deformation, wherein the rod guide has a washer restricting portion that restricts radial positional deviation of the lock washer.

[0008] In the present invention, the rod guide has a washer restricting portion that restricts radial displacement of the lock washer, making it difficult for the lock washer to be displaced in the radial direction during assembly of the fluid pressure cylinder, and facilitating radial positioning of the lock washer.

[0009] In the above-described fluid pressure cylinder, the washer restricting portion may be a protruding portion that protrudes from the guide end surface toward the cylinder tube and is capable of coming into contact with an inner peripheral surface of the lock washer. In this case, the washer restricting portion is a protrusion that protrudes from the guide end face of the rod guide toward the cylinder tube. The protrusion abuts against the inner circumferential surface of the lock washer, thereby restricting radial displacement of the lock washer. Furthermore, because the washer restricting portion is a protrusion that protrudes from the guide end face, the number of parts does not increase.

[0010] In the above-described fluid pressure cylinder, the outer diameter of the outer peripheral surface of the protrusion may be equal to or smaller than the inner diameter of the inner peripheral surface of the lock washer. In this case, the outer diameter of the outer peripheral surface of the protrusion is equal to or smaller than the inner diameter of the lock washer, so that the protrusion can be inserted into the lock washer.

[0011] In the above-described fluid pressure cylinder, the amount of protrusion of the protruding portion from the guide end surface may be smaller than the plate thickness of the lock washer. In this case, the amount of protrusion from the guide end face is smaller than the thickness of the lock washer, so the end face of the cylinder tube does not abut on the protrusion, allowing the rod guide and cylinder tube to clamp the lock washer in the axial direction, preventing the lock washer from loosening.

[0012] Furthermore, in the above-described fluid pressure cylinder, the rod guide may have a threaded hole formed through the rod guide in the axial direction, and the washer regulating portion may be a screw member that is threaded into the threaded hole and is capable of pressing the lock washer in the axial direction or abutting against the inner peripheral surface of the lock washer. In this case, the rod guide has a threaded hole formed axially through the rod guide, and the washer restricting portion is a screw member that is screwed into the threaded hole and can press the lock washer in the axial direction or abut against the inner peripheral surface of the lock washer, so there is no need to form a protrusion on the guide end face. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a fluid pressure cylinder that makes it easy to position a lock washer in the radial direction during assembly work. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a vertical cross-sectional view showing an overview of a hydraulic cylinder according to a first embodiment. [Figure 2] FIG. 1 is a front view of a hydraulic cylinder according to a first embodiment. [Figure 3] FIG. 3 is a view taken along the line AA in FIG. 2. [Figure 4] FIG. 3 is a view taken along the line BB in FIG. 2. [Figure 5] FIG. 1 is a perspective view showing a main part of a hydraulic cylinder according to a first embodiment. [Figure 6] FIG. 10 is a perspective view showing a main part of a hydraulic cylinder according to a second embodiment. [Figure 7] FIG. 5 is an enlarged longitudinal sectional view showing a main part of a hydraulic cylinder according to a second embodiment. [Figure 8] FIG. 10 is an enlarged longitudinal sectional view showing a main part of a hydraulic cylinder according to a modified example of the second embodiment. [Figure 9] FIG. 10 is an enlarged longitudinal sectional view showing a main part of a conventional fluid pressure cylinder. DETAILED DESCRIPTION OF THE INVENTION

[0015] (First embodiment) Hereinafter, a hydraulic cylinder as a fluid pressure cylinder according to a first embodiment will be described with reference to the drawings. The hydraulic cylinder of this embodiment is a double-acting hydraulic cylinder provided in a forklift, which is an industrial vehicle.

[0016] As shown in FIG. 1, the hydraulic cylinder 10 includes a cylinder tube 11, a piston 12, a piston rod 13, and a rod guide 14. The cylinder tube 11 includes a cylindrical cylinder tube main body 15 and an end cover 16 that closes the base end of the cylinder tube main body 15. As shown in FIGS. 3 and 4, a tube end face 17 that forms an opening is formed at the tip of the cylinder tube main body 15, opposite the base end. The tube end face 17 is an annular surface that is substantially perpendicular to the axial direction of the cylinder tube 11. The outer diameter of the tube end face 17 is smaller than the outer diameter of the cylinder tube main body 15. Therefore, a tube side tapered surface 18 that decreases in diameter from the outer peripheral surface of the cylinder tube main body 15 toward the tube end face 17 is formed between the tube end face 17 and the cylinder tube main body 15 (see FIG. 3). A pair of tube side grooves 19 having a radial depth are formed in the cylinder tube main body 15 in the circumferential direction (see FIG. 4). The tube side groove 19 is a groove formed across the tube side tapered surface 18 and the outer circumferential surface of the cylinder tube main body 15 in the axial direction.

[0017] A female thread portion 20 is formed on the inner peripheral surface of the cylinder tube main body 15 so as to extend in the axial direction from the tube end face 17. The female thread portion 20 is a thread portion for threadingly engaging the cylinder tube 11 and the rod guide 14. As shown in FIG. 1, a pair of support shaft portions 21 is provided on the outer peripheral surface of the cylinder tube main body 15. The support shaft portions 21 extend in a direction perpendicular to the axial direction, and the axial centers of the pair of support shaft portions 21 are aligned. The support shaft portions 21 are shaft portions for rotatably supporting the hydraulic cylinder 10 at the attachment location.

[0018] As shown in FIG. 1 , a cylindrical piston 12 is inserted into a cylinder tube 11. The piston 12 is capable of reciprocating within the cylinder tube 11. A plurality of piston seals 22 are attached to the outer circumferential surface of the piston 12, which slide against the inner circumferential surface of a cylinder tube main body 15. A through-hole 23 is formed in the center of the piston 12, penetrating it in the axial direction. A piston rod 13 is inserted through the through-hole 23. The piston rod 13 has a rod main body 24, an end portion 25 on the base end side of the rod main body 24, and a rod joint portion 26 formed at the tip end side. A through-hole 27 is formed in the rod joint portion 26. The end portion 25 of the piston rod 13 is fixed to the piston 12 by tightening a lock nut 28. A portion of the tip side of the rod main body 24 protrudes outside the cylinder tube 11, and the rod joint portion 26 protrudes outside the cylinder tube 11 regardless of the axial position of the piston 12 relative to the cylinder tube 11.

[0019] As shown in Fig. 1, a first oil chamber C1 and a second oil chamber C2 are defined within the cylinder tube 11. The first oil chamber C1 is defined by the piston 12, the cylinder tube main body 15, and the end cover 16. The second oil chamber C2 is defined by the piston 12, the rod guide 14, and the cylinder tube main body 15. The cylinder tube main body 15 is formed with a first supply / discharge port 15A for supplying / discharging hydraulic oil, which communicates with the first oil chamber C1. The cylinder tube main body 15 is also formed with a second supply / discharge port 15B for supplying / discharging hydraulic oil, which communicates with the second oil chamber C2.

[0020] The rod guide 14 closes the opening of the cylinder tube main body 15. The rod guide 14 has a cylindrical rod guide main body 29 inserted into the cylinder tube main body 15 and a flange 30 expanding radially from the end of the rod guide main body 29. A male thread 31 is formed on the outer circumferential surface of the rod guide main body 29. The male thread 31 is a threaded portion that threadably mates with the female thread 20 of the cylinder tube main body 15. A guide hole 32 is formed in the rod guide main body 29, penetrating it in the axial direction. The rod main body 24 is inserted into the guide hole 32. As shown in FIGS. 3 and 4 , an annular recess 33 is formed on the outer periphery of the rod guide main body 29. The annular recess 33 is a recess for allowing a tool to escape when forming the male thread 31 by machining, and is located between the male thread 31 and the flange 30. The outer circumferential surface formed by the annular recess 33 has a smaller diameter than the outer circumferential surface of the rod guide main body 29.

[0021] The flange portion 30 has a flange portion outer peripheral surface 34, a guide end surface 35, and a guide-side tapered surface 36. The outer diameter of the flange portion outer peripheral surface 34 is approximately the same as the outer diameter of the cylinder tube main body 15. The guide end surface 35 is a surface that faces the tube end surface 17 of the cylinder tube main body 15. The outer diameter of the guide end surface 35 is smaller than the outer diameter of the flange portion outer peripheral surface 34. Therefore, a guide-side tapered surface 36 is formed, the diameter of which decreases from the flange portion outer peripheral surface 34 toward the guide end surface 35.

[0022] As shown in Fig. 2, a pair of guide grooves 37 are formed in the circumferential direction of the flange portion 30. The guide groove 37 is formed by a first recess 38 that is shallowly recessed in an arc shape radially from the guide tapered surface 36, and a second recess 39 that is deeply recessed from the flange portion outer peripheral surface 34. The guide groove 37, together with the tube groove 19, is a groove for locally plastically deforming a lock washer 40, which will be described next. Note that for ease of explanation, Fig. 2 shows the rod main body 24 of the piston rod 13 in a cutaway view.

[0023] A lock washer 40 is interposed between the tube end face 17 and the guide end face 35. The lock washer 40 is an annular washer and is a member that prevents loosening of the threaded engagement of the rod guide 14 with the cylinder tube 11. The outer diameter D1 of the outer peripheral surface 41 of the lock washer 40 is approximately the same as the outer diameter of the cylinder tube main body 15. The inner diameter D2 of the inner peripheral surface 42 of the lock washer 40 is larger than the outer diameter of the rod guide main body 29 but smaller than the outer diameter of the cylinder tube main body 15. Of the pair of washer surfaces 43 of the lock washer 40, one washer surface 43 abuts against the tube end face 17, and the other washer surface 43 abuts against the guide end face 35.

[0024] During assembly, a tool (not shown) is driven between the flange portion 30 and the lock washer 40, causing the lock washer 40 to be locally bent and plastically deformed toward the tube side groove 19. As a result, as shown in FIG. 5 , a tube side crimping portion 44 is formed in the lock washer 40, and the tube side crimping portion 44 functions to prevent the lock washer 40 from rotating relative to the cylinder tube 11.

[0025] During assembly, a tool (not shown) is driven between the tube end face 17 and the lock washer 40, causing the lock washer 40 to be locally bent toward the guide-side groove 37 and plastically deformed. As a result, as shown in FIG. 5, a guide-side crimped portion 45 is formed in the lock washer 40, and the guide-side crimped portion 45 functions to prevent rotation with respect to the rod guide 14. The anti-rotation function of the tube-side crimped portion 44 and the guide-side crimped portion 45 prevents the rod guide 14 from loosening relative to the cylinder tube 11. Note that the lock washer 40 shown in FIGS. 3 and 4 is in a state before the tube-side crimped portion 44 and the guide-side crimped portion 45 are formed.

[0026] The hydraulic cylinder 10 of this embodiment has a washer restricting portion that restricts radial displacement of the lock washer 40. Specifically, the washer restricting portion is a protrusion 46 that protrudes from the guide end surface 35 toward the cylinder tube 11 (see FIGS. 3 and 4). The protrusion 46 of this embodiment is an annular portion formed in the circumferential direction, and is formed integrally with the rod guide main body 29. The protrusion 46 is formed together with the annular recess 33 by cutting.

[0027] As shown in FIG. 3 , the outer diameter D3 of the outer peripheral surface 47 of the protrusion 46 is set equal to or smaller than the inner diameter D2 (D2≧D3) so that the protrusion 46 can abut against the inner peripheral surface 42 of the lock washer 40. A smaller difference between the outer diameter D3 and the inner diameter D2 of the protrusion 46 is preferable because it reduces radial movement of the lock washer 40. The outer diameter D3 includes the upper limit of the design tolerance, and the inner diameter D2 includes the lower limit of the design tolerance. The protrusion 46 has a protruding end face 48 that faces the tube end face 17. The amount of protrusion from the guide end face 35 corresponds to the distance L from the guide end face 35 to the protruding end face 48 of the protrusion 46 in the axial direction. The distance L is set smaller than the plate thickness T of the lock washer 40 (T>L) so that the protrusion 46 does not abut against the tube end face 17. The distance L includes the upper limit of the design tolerance, and the inner diameter D2 includes the lower limit of the design tolerance.

[0028] Next, the assembly work of the hydraulic cylinder 10 of this embodiment will be described. When fixing the rod guide 14 to the cylinder tube 11 during the assembly work, the piston rod 13 to which the piston 12 is attached is inserted into the rod guide 14 and lock washer 40, and the piston 12 is then inserted into the cylinder tube 11. The male thread portion 31 of the rod guide 14 is threadedly engaged with the female thread portion 20 of the cylinder tube 11, and the rod guide 14 is screwed onto the cylinder tube 11. At this time, the lock washer 40 is interposed between the tube end face 17 and the guide end face 35, and is clamped between the rod guide 14 and the cylinder tube 11. The lock washer 40 is bent and plastically deformed at the positions of the tube groove 19 and the guide groove 37 using a tool, forming a tube-side crimping portion 44 and a guide-side crimping portion 45 in the lock washer 40 (see FIG. 5).

[0029] When a tool is used to plastically deform the lock washer 40 by bending it, the protrusions 46 restrict radial movement of the lock washer 40. This makes it easy to position the lock washer 40 in the radial direction, facilitating the work of plastically deforming the lock washer 40 using a tool. The formation of the tube-side crimping portion 44 and the guide-side crimping portion 45 on the lock washer 40 prevents the rod guide 14 from loosening relative to the cylinder tube 11.

[0030] The hydraulic cylinder 10 according to this embodiment has the following advantages. (1) The rod guide 14 has a washer restricting portion that restricts radial displacement of the lock washer 40. Therefore, the lock washer 40 is less likely to be displaced in the radial direction during the assembly work of the hydraulic cylinder 10, making it easier to position the lock washer 40 in the radial direction.

[0031] (2) The washer restricting portion is a protruding portion 46 that protrudes from the guide end surface 35 toward the cylinder tube 11 and can abut against the inner circumferential surface 42 of the lock washer 40. Therefore, the protruding portion 46 abuts against the inner circumferential surface 42 of the lock washer 40, thereby restricting radial displacement of the lock washer 40. Furthermore, because the washer restricting portion is a protruding portion 46 that protrudes from the guide end surface 35, the number of parts does not increase.

[0032] (3) The outer diameter D3 of the outer peripheral surface 47 of the protrusion 46 is equal to or smaller than the inner diameter D2 of the inner peripheral surface 42 of the lock washer 40, so the protrusion 46 can be inserted into the lock washer 40. Inserting the protrusion 46 into the lock washer 40 makes it easier to prevent the lock washer 40 from shifting radially. Furthermore, because the protrusion 46 is integrally formed with the rod guide main body 29, an increase in the number of parts is suppressed.

[0033] (4) The amount of protrusion (distance L) from the guide end face 35 of the protruding portion 46 to the protruding end face 48 is smaller than the axial thickness of the lock washer 40, so the tube end face 17 of the cylinder tube 11 does not come into contact with the protruding portion 46. As a result, the rod guide 14 and the cylinder tube 11 can clamp the lock washer 40 in the axial direction, and the lock washer 40 will not loosen.

[0034] (Second embodiment) Next, a hydraulic cylinder according to a second embodiment will be described. This embodiment differs from the first embodiment in the configuration of the washer restricting portion. In this embodiment, the same configuration as in the first embodiment will be referred to and the same reference numerals will be used.

[0035] As shown in Fig. 6, the rod guide 51 of the hydraulic cylinder 50 has a flange portion 30. As shown in Fig. 7, the flange portion 30 has a flange portion outer circumferential surface 34, a guide end surface 52, and a guide-side tapered surface 36. The guide end surface 52 faces the tube end surface 17 of the cylinder tube main body 15 and extends radially to the annular recess 33. Therefore, the guide end surface 52 does not have the protrusion 46 of the first embodiment.

[0036] The flange portion 30 is formed with a plurality of threaded holes 53 that penetrate in the axial direction from the end face of the rod guide 51 toward the guide end face 52. The threaded holes 53 are provided at positions facing the tube-side end face. In this embodiment, four threaded holes 53 are formed in the rod guide 51 at equal intervals in the circumferential direction. Set screws 54 serving as threaded members are threaded into the threaded holes 53. The set screws 54 are capable of abutting against the washer surface 43 and are capable of pressing the lock washer 40 in the axial direction.

[0037] During assembly of the hydraulic cylinder 50 of this embodiment, the setscrew 54 is threaded into the threaded hole 53 and brought into contact with the washer surface 43, and the lock washer 40 is then pressed axially against the tube end surface 17. As a result, the lock washer 40 is clamped between the setscrew 54 and the tube end surface 17, restricting radial movement. In other words, the threaded hole 53 and the setscrew 54 correspond to a washer restricting portion that restricts radial displacement of the lock washer 40.

[0038] This embodiment achieves the same effect as effect (1) of the first embodiment. Furthermore, according to this embodiment, rod guide 51 has threaded hole 53 formed to penetrate therethrough in the axial direction, and the washer restricting portion is set screw 54 that is threaded into threaded hole 53 and can press lock washer 40 in the axial direction. Therefore, there is no need to form protrusion 46 on guide end surface 52. Set screw 54 may be left in threaded hole 53 after tube-side crimping portion 44 and guide-side crimping portion 45 are formed on lock washer 40, or it may be removed.

[0039] (Variation) A modified example of the second embodiment will be described. As shown in Fig. 8, in a hydraulic cylinder 50, a threaded hole 53 may be formed axially penetrating from the end face of a rod guide 51 so that the threaded hole 53 is located radially inward of the inner peripheral surface 42 of the lock washer 40. A setscrew 54 is threaded into the threaded hole 53 and protrudes into the annular recess 33, thereby restricting radial movement of the lock washer 40. In this modified example, the washer restricting portion is the setscrew 54 that is threaded into the threaded hole 53 and can abut against the inner peripheral surface 42 of the lock washer 40, so there is no need to form a protrusion 46 on the guide end face 52.

[0040] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the spirit of the invention. For example, the following modifications may be made.

[0041] In the above embodiment, the fluid pressure cylinder is a double-acting hydraulic cylinder provided in a forklift, which is an industrial vehicle. However, the present invention is not limited to this. The fluid pressure cylinder may be a cylinder that operates using a fluid pressure other than hydraulic oil, such as a pneumatic cylinder that operates using air pressure. Furthermore, the fluid pressure cylinder may be a single-acting cylinder instead of a double-acting cylinder. In the second embodiment, the rod guide is formed with four threaded holes, but this is not limiting. The number of threaded holes may be, for example, three, as long as it is sufficient to reliably restrict radial movement of the lock washer. In the second embodiment, a set screw is used as the screw member of the washer restricting portion, but this is not limiting. The screw member may be, for example, a hexagon bolt, and any type of screw member may be used as long as it can press the lock washer in the axial direction or contact the inner circumferential surface of the lock washer. [Explanation of symbols]

[0042] 10, 50 Hydraulic cylinder 11 Cylinder tube 12 pistons 13 Piston rod 14, 51 Rod guide 15 Cylinder tube body 17 Tube end face 19 Tube gutter 29 Rod guide body 30 Flange 33 Annular recess 35, 52 Guide end face 37 Guide gutter 40 Lock washer 42 Inner surface 44 Tube side crimping part 45 Guide side crimping part 46 Protrusion (washer restriction part) 47 Outer surface 48 Protruding end face 53 screw hole 54 Set screw (screw member) D1 Outer diameter (lock washer) D2 Inner diameter (lock washer) D3 Outer diameter (protrusion) L distance T plate thickness

Claims

1. a cylinder tube having a tube end face at one end; a rod guide that is screwed onto the cylinder tube and has a guide end surface that faces the tube end surface; a lock washer interposed between the tube end surface and the guide end surface, the lock washer preventing loosening of the rod guide relative to the cylinder tube by crimping formed by plastic deformation, The fluid pressure cylinder according to claim 1, wherein the rod guide has a washer restricting portion that restricts radial displacement of the lock washer.

2. 2. The fluid pressure cylinder according to claim 1, wherein the washer restricting portion is a protruding portion that protrudes from the guide end surface toward the cylinder tube and is capable of abutting against an inner peripheral surface of the lock washer.

3. 3. The fluid pressure cylinder according to claim 2, wherein the outer diameter of the outer peripheral surface of the protrusion is equal to or smaller than the inner diameter of the inner peripheral surface of the lock washer.

4. 4. The fluid pressure cylinder according to claim 2, wherein the amount of protrusion from the guide end surface is smaller than the thickness of the lock washer.

5. The rod guide has a threaded hole formed to penetrate the rod guide in the axial direction, 2. The fluid pressure cylinder according to claim 1, wherein the washer restricting portion is a screw member that is threaded into the threaded hole and is capable of pressing the lock washer in the axial direction or abutting against an inner peripheral surface of the lock washer.

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