Linear motion damper

Abstract

To provide a linear motion damper which can inhibit pressure rise caused by temperature rise.SOLUTION: A linear motion damper includes: a cylinder 3 for forming a pressure chamber 11; a piston 5 which is installed in the cylinder 3, defines the pressure chamber 11, and may move forward or backward relative to the defined pressure chamber 11; a piston rod 7 which is provided coaxially with the piston 5, protrudes to the outside of the cylinder 3, and moves in conjunction with the forward and backward movement; a flange part 33 which is provided at the piston rod 7 and disposed facing the piston 5 in a direction of the forward and rearward movement; a seal attachment part 35 which is included in an outer periphery of the piston rod 7 between the piston 5 and the flange part 33 and has a circular shape; a seal ring 9 which is attached to the seal attachment part 35 in a fitting manner and makes a seal between the cylinder 3 and the piston 5; a movable space part 37 which enables relative movement of the seal ring 9 in a direction of the forward and backward movement between the piston 5 and the flange part 33; and a communication part 39 which allows the pressure chamber 11 to communicate with the outside of the cylinder 3 through the movable space part 37 in a state where the piston 5 retreats relative to the pressure chamber 11 and the flange part 33 abuts on the cylinder 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat-resistant direct-acting damper. [Background technology]

[0002] A conventional linear damper is a damper device described in Patent Document 1. In this damper device, a seal ring is housed in a seal housing formed in a piston. The seal housing is formed by a second restricting portion on the first chamber side and a first restricting portion on the second chamber side, and the second restricting portion has a notch.

[0003] When the transmission part is pulled by the opening movement of the opening / closing body, the seal ring is maintained in its normal state in contact with the second restrictor by the movement of the piston. At this time, the first chamber becomes negative pressure due to the increase in volume, generating resistance. This causes the opening / closing body to open slowly. The negative pressure in the first chamber is also released by the orifice formed in the cap.

[0004] On the other hand, if the opening and closing body is opened suddenly and the negative pressure in the first chamber becomes too high, the force pulling the stone back increases, and the opening and closing body that was opened suddenly is returned in the closing direction.

[0005] At this time, part of the seal ring enters the notch in the second restricting portion, and air from the second chamber enters the first chamber through the gap between the second restricting portion and the seal ring, thereby eliminating the negative pressure in the first chamber, stopping the piston from retracting and releasing the closing movement of the opening / closing body that was suddenly opened.

[0006] In other words, it prevents a sudden increase in negative pressure in the first chamber and allows the opening and closing body to open suddenly.

[0007] However, this sudden increase in negative pressure is resolved by the force acting on the seal ring when the piston is returned to the first chamber by the negative pressure, and there was a problem that this could not be resolved when the pressure in the first chamber increased due to a rise in temperature. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2022-69167 Summary of the Invention [Problem to be solved by the invention]

[0009] The problem to be solved is that the pressure increase caused by the temperature increase could not be suppressed. [Means for solving the problem]

[0010] a piston rod that is coaxial with the piston and protrudes outside the cylinder so as to move in conjunction with the piston's forward and backward movement; a flange that is attached to the piston rod and faces the piston in the direction of forward and backward movement; a circular seal mounting portion that is attached to the outer periphery of the piston rod between the piston and the flange; a seal ring that is fitted into the seal mounting portion and provides a seal between the cylinder and the piston; a movable space that allows the seal ring to move relatively in the direction of forward and backward movement between the piston and the flange; and a communication portion that connects the pressure chamber to the outside of the cylinder via the movable space when the piston retracts relative to the pressure chamber and the flange abuts against the cylinder. [Effects of the Invention]

[0011] Because the linear damper of the present invention has the above-mentioned configuration, when the piston moves back relative to the pressure chamber and the flange abuts against the cylinder, the communication portion can connect the pressure chamber to the outside of the cylinder via the movable space portion. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view of a linear damper according to a first embodiment when the damper is extended. [Figure 2] Fig. 2(A) is a cross-sectional view of the linear damper of Fig. 1 in an extended state. Fig. 2(B) is a cross-sectional view taken along line BB in Fig. 2(A). Fig. 2(C) is an end view of the linear damper of Fig. 2(A). [Figure 3] FIG. 3 is a cross-sectional view of a main part of the linear damper of FIG. 1 when extended. [Figure 4] FIG. 4 is a cross-sectional view of a main part of the linear damper of FIG. 1 when it is contracted. [Figure 5] FIG. 10 is a cross-sectional view of a main part of the linear damper when it is extended according to the second embodiment. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 7 is a cross-sectional view of a main part of the linear damper according to the third embodiment when the linear damper is extended. [Figure 8] FIG. 8 is a cross-sectional view of a main part of the linear damper according to the fourth embodiment when the linear damper is extended. [Figure 9] FIG. 9 is a cross-sectional view of a main part of the linear damper according to the fifth embodiment when the linear damper is extended. [Figure 10] FIG. 10 is an end view of the linear damper of FIG. [Figure 11] FIG. 11 is a cross-sectional view of a main part of the linear damper when it is extended according to the sixth embodiment. [Figure 12] FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. [Figure 13] FIG. 13 is a cross-sectional view of a main part of the linear damper according to the seventh embodiment when the linear damper is extended. [Figure 14] FIG. 14 is a cross-sectional view of a main part of the linear damper according to the eighth embodiment when the linear damper is extended. [Figure 15] FIG. 15 is a cross-sectional view of a main part of the linear damper according to the ninth embodiment when the linear damper is extended. [Figure 16] FIG. 16 is a cross-sectional view of a main part of the linear damper according to the tenth embodiment when the linear damper is extended. [Figure 17] FIG. 17 is a cross-sectional view of a main part of the linear damper according to the eleventh embodiment when the linear damper is extended. [Figure 18] FIG. 18 is a cross-sectional view taken along the line XVIII-XVIII in FIG. [Figure 19] FIG. 19 is a cross-sectional view of a main part of a linear damper according to a twelfth embodiment when the linear damper is extended. [Figure 20] FIG. 20 is an end view of the linear damper of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention achieves the object of making it possible to suppress a pressure increase due to a temperature increase as follows.

[0014] In order to make it possible to suppress a pressure increase due to a temperature increase, the piston is realized in a form including a cylinder for forming a pressure chamber, a piston that is housed in the cylinder and that partitions the pressure chamber and is movable toward and away from the partitioned pressure chamber, a piston rod that is coaxial with the piston and protrudes outside the cylinder and is linked to the forward and backward movement, a flange that is attached to the piston rod and positioned opposite the direction of the forward and backward movement of the piston, a circular seal mounting portion that is attached to the outer periphery of the piston rod between the piston and the flange, a seal ring that is fitted into and attached to provide a seal between the cylinder and the piston, a movable space portion that allows the seal ring to move relatively in the direction of the forward and backward movement between the piston and the flange, and a communication portion that connects the pressure chamber to the outside of the cylinder via the movable space portion when the piston retracts relative to the pressure chamber and the flange abuts against the cylinder.

[0015] The cylinder has a step portion that stops the movement of the seal ring when the seal ring moves within the movable space portion due to the internal pressure of the pressure chamber, thereby maintaining a gap between the seal ring and the flange portion, and the communication portion has a passage between the inner circumference of the seal ring and the piston rod, and the passage is realized in a form that connects the pressure chamber to the outside of the cylinder via the movable space portion.

[0016] The communication portion includes a passage that communicates the inside and outside of the cylinder, and the passage is realized in a form that communicates the movable space portion with the outside between the piston and the seal ring. [Example]

[0017] [Linear damper] FIG. 1 is a cross-sectional view of a linear damper according to a first embodiment when it is extended. FIG. 2(A) is a cross-sectional view of the linear damper of FIG. 1 when it is extended. FIG. 2(B) is a cross-sectional view taken along line BB in FIG. 2(A). FIG. 2(C) is an end view of the linear damper of FIG. 2(A). FIG. 3 is a cross-sectional view of a main part of the linear damper of FIG. 1 when it is extended. FIG. 4 is a cross-sectional view of a main part of the linear damper of FIG. 1 when it is contracted.

[0018] 1 and 2, the linear damper 1 of the first embodiment is configured as an air damper. However, the linear damper 1 can also be configured as an oil damper or the like.

[0019] The direct-acting damper 1 includes a cylinder 3, a piston 5, a piston rod 7, and a seal ring 9.

[0020] The cylinder 3 forms a pressure chamber 11, and a cap 15 is fitted into one end of a cylindrical portion 13 to seal it. On the cap 15 side, which is the one end of the cylindrical portion 13, grooves 17 are formed on the inner circumferential surface. The grooves 17 are formed along the axial direction and are arranged at 120° intervals in the circumferential direction.

[0021] A step 19 is formed on the other end side of the cylindrical portion 13. The step 19 provides the inner circumferential surface of the cylindrical portion 13 with a first inner circumferential surface 13a and a second inner circumferential surface 13b. The first inner circumferential surface 13a is for forming the pressure chamber 11. The second inner circumferential surface 13b is formed with a slightly smaller diameter than the first inner circumferential surface 13a.

[0022] An end wall 21 is formed at the other end of the cylindrical portion 13. The end wall 21 is formed integrally with the cylindrical portion 13. A tapered portion 23 that tapers in the axial direction toward the inside of the cylindrical portion 13 is formed at the axial center of the end wall 21. The axial center of the axial center of the end wall 21 refers to the axial center of the linear damper 1, and the axial direction refers to the stroke direction along the axial center of the linear damper 1.

[0023] A rod guide 25 that protrudes outward from the cylindrical portion 13 is integrally formed at the axial center of the end wall 21 and extends therefrom. The rod guide 25 is formed with a diameter smaller than the diameter of the cylindrical portion 13. The rod guide 25 has grooves 27 formed on its inner peripheral surface. The grooves 27 are formed along the axial direction and are arranged at 120° intervals in the circumferential direction. The outer ends of the grooves 27 in the axial direction communicate with the outside of the rod guide 25. The inner ends of the grooves 27 in the axial direction communicate with the tapered portion 23.

[0024] The piston 5 is installed inside the cylinder 3 together with a seal ring 9, defines the pressure chamber 11 relative to the first inner circumferential surface 13a, and is configured to be movable toward and away from the defined pressure chamber 11. The piston 5 is configured to include a head portion 29 and a spring seal receiving portion 31. The head portion 29 is formed to have a smaller diameter than the spring seal receiving portion 31, and the outer periphery of the spring seal receiving portion 31 is formed to have a slightly smaller diameter than the first inner circumferential surface 13a of the cylinder 3. A return spring 32 is interposed between the cap portion 15 and the spring seal receiving portion 31.

[0025] A first receiving surface 31a is formed in the spring seal receiving portion 31. A groove 31ab is formed in the first receiving surface 31a in the radial direction. The radial direction means the radial direction of the cylinder 3.

[0026] The piston rod 7 is provided coaxially with the piston 5, passes through a rod guide 25, and protrudes to the outside of the cylinder 3, and is configured to move in conjunction with the forward and backward movement of the piston 5.

[0027] A flange 33 is formed integrally with the piston rod 7. The flange 33 is disposed opposite the spring seal receiving portion 31 of the piston 5. The outer periphery of the flange 33 is formed to have a diameter slightly smaller than the second inner circumferential surface 13b of the cylinder 3. The flange 33 is formed with a second receiving surface 33a that faces the first inner circumferential surface 13a. The flange 33 is formed with a contact surface 33b on the end wall 21 side, and a radial groove 33ba is formed in the contact surface 33b.

[0028] Between the spring seal receiving portion 31 and the flange 33 of the piston 5, a circumferential seal mounting portion 35 is formed on the outer periphery of the piston rod 7. A seal ring 9 is fitted and attached to the seal mounting portion 35. The seal ring 9 has a cross-sectional shape with a lip, and is configured to provide a seal between the cylinder 3 and the piston 5.

[0029] The space between the piston 5 and the flange 33 is formed to be larger than the axial width of the seal ring 9. Therefore, the space between the piston 5 and the flange 33 is configured as a movable space 37. The movable space 37 is configured to allow the seal ring 9 to move relatively between the piston 5 and the flange 33 with respect to the seal mounting portion 35 in the direction of the piston 5's forward and backward movement.

[0030] Between the piston 5 and the flange 33, the piston rod 7 is formed as a D-cut portion 7a. The D-cut portion 7a forms a passage between the inner periphery of the seal ring 9 and the piston rod 7, which communicates with the movable space 37. This passage communicates the pressure chamber 11 with the outside of the cylinder 3 via the movable space 37.

[0031] Therefore, when the piston 5, including the passage, moves back relative to the pressure chamber 11 and the flange portion 33 abuts against the end wall 21 of the cylinder 3, a communication portion 39 is formed that connects the pressure chamber 11 to the outside of the cylinder 3 via the movable space portion 37.

[0032] Communication with the outside through the communicating portion 39 is achieved through the passage between the first inner circumferential surface 13a of the cylinder 3 and the outer periphery of the spring seal receiving portion 31, the passage formed by the groove 31ab of the spring seal receiving portion 31 or the groove 31ab and the movable space portion 37, the passage between the D-cut portion 7a and the inner periphery of the seal ring 9, the passage within the movable space portion 37 between the second receiving surface 33a of the flange portion 33 and the seal ring 9, the passage between the second inner circumferential surface 13b of the cylinder 3 and the outer periphery of the flange portion 33, the passage formed by the groove 33ba between the abutment surface 33b of the flange portion 33 and the end wall 21, the tapered portion 23, and the recessed rib portion 27.

[0033] The formation of passages between the spring seal receiving portion 31 and the flange 33 and the seal ring 9 is achieved by the seal ring 9 moving within the movable space portion 37 due to the internal pressure of the pressure chamber 11. This movement causes the step portion 19 to stop the movement of the seal ring 9, maintaining a gap between the spring seal receiving portion 31 and the flange 33.

[0034] [Action and effect] 1 and 3, a temperature rise causes the pressure in the pressure chamber 11 to exceed the design range, and the piston 5 moves due to the internal pressure, causing the flange 33 to abut against the end wall 21 at the abutment surface 33b.

[0035] At this time, the internal pressure also causes the seal ring 9 to move toward the flange 33 within the movable space 37, but along the way, the outer periphery of the seal ring 9 engages with the step 19, maintaining a gap between the seal ring 9 and the flange 33.

[0036] Therefore, the rising pressure in the pressure chamber 11 escapes from the outer end of the rod guide 25 through the passage between the first inner surface 13a of the cylinder 3 and the outer periphery of the spring seal receiving portion 31, which constitutes the communicating portion 39, the groove 31ab of the spring seal receiving portion 31 or the passage formed by the groove 31ab and the movable space portion 37, the passage between the D-cut portion 7a and the inner periphery of the seal ring 9, the passage within the movable space portion 37 between the second receiving surface 33a of the flange portion 33 and the seal ring 9, the passage between the second inner surface 13b of the cylinder 3 and the outer periphery of the flange portion 33, the passage formed by the groove 33ba between the abutment surface 33b of the flange portion 33 and the end wall 21, the tapered portion 23, and the groove portion 27.

[0037] Therefore, even when the temperature rises, the damping characteristics can be maintained the same as at room temperature.

[0038] As shown in Figures 2 and 4, during the advancement operation in which the piston rod strokes from the extended state to the retracted state, the spring seal receiving portion 31 bends the return spring 32, while the piston 5 and seal ring 9 compress the pressure chamber 11, and a drag force acts on the piston rod 7.

[0039] During this stroke, the seal ring 9 moves while being pressed by the flange portion 33. Resistance is high in the area where the seal ring 9 is in close contact with the first inner circumferential surface 13a of the cylinder 3, and when the seal ring 9 reaches the groove portion 17, the air in the pressure chamber 11 passes through the groove portion 17 and moves toward the piston rod 7. The moved air escapes to the outside of the cylinder 3 through the tapered portion 23 and the groove portion 27.

[0040] Therefore, the drag acting on the piston rod 7 weakens at the end of the stroke when the piston 5 advances due to the piston rod contraction.

[0041] 2 to the extended state of the piston rod shown in FIGS. 1 and 3, the spring seal receiving portion 31 moves while pressing the seal ring 9 as the piston 5 moves toward the end wall 21.

[0042] Due to this movement, the pressure inside the compression chamber 11 tends to become negative in the range where the seal ring 9 is in close contact with the first inner circumferential surface 13a.

[0043] At this time, positive pressure passes from the end of the rod guide 25 through the groove portion 27, the tapered portion 23, the gap between the second inner circumferential surface 13b of the cylinder 3 and the outer periphery of the flange portion 33, the movable space portion 37 between the flange portion 33 and the seal ring 9, the gap between the D-cut portion 7a and the inner periphery of the seal ring 9, the groove 31ab of the spring seal receiving portion 31, and the gap between the first inner circumferential surface 13a of the cylinder 3 and the outer periphery of the spring seal receiving portion 31, and enters the compression chamber 11, thereby weakening or eliminating the force acting in the retracting direction even when the piston rod 7 is suddenly extended.

[0044] If this direct-acting damper is attached to, for example, various types of doors, and the piston rod 7 extends when the door is opened, even if the temperature rises above the set value, the internal pressure of the compression chamber 11 is released as described above, and the closing operation of the door is not hindered or can be suppressed.

[0045] When the door is suddenly opened, the negative pressure in the compression chamber 11 can be eliminated or alleviated as described above, and the return of pressure due to the negative pressure of the opened door can be eliminated or suppressed. [Example]

[0046] Fig. 5 is a cross-sectional view of a main part of a linear damper according to a second embodiment when the linear damper is extended. Fig. 6 is a cross-sectional view taken along the line VI-VI in Fig. 5. The basic configuration is the same as that of the first embodiment, and the same or corresponding components are designated by the same reference numerals, and redundant explanations will be omitted.

[0047] 5 and 6, the linear damper 1 of the second embodiment has a through-hole 41 provided on the end wall 21 side of the cylinder 3. The through-hole 41 penetrates the end wall 21 and is formed to extend to the step portion 19 via the second inner circumferential surface 13b.

[0048] Therefore, in this embodiment 2, the through-hole 41 constitutes a part of the passage of the communication part 39 in place of the groove part 27 of the embodiment 1, and the same effect can be achieved. Moreover, since the through-hole 41 of the embodiment 2 is not related to the guide of the piston rod 7, it can be made shorter as a passage and have a relatively larger opening area compared to the groove part 27 of the embodiment 1, and it is possible to perform smoother pressure release.

[0049] In addition, the second embodiment can also achieve the same effects as the first embodiment. [Example]

[0050] 7 is a cross-sectional view of a main part of a linear damper when extended according to Example 3. The basic configuration is the same as that of Example 1, and the same or corresponding components are denoted by the same reference numerals, and redundant explanations will be omitted.

[0051] 7, the linear damper 1 of the third embodiment has a through hole 43 provided on the end wall 21 side of the cylinder 3. The through hole 43 passes through the cylinder 3 in the radial direction on the end wall 21 side, and the second inner circumferential surface 13b is open to the outside of the cylinder 3.

[0052] Therefore, in this embodiment 3, the through hole 43 constitutes a part of the passage of the communication part 39 in place of the tapered part 23 and the grooved rib part 27 of the embodiment 1, and the same operational effect can be achieved. Furthermore, since the through hole 43 of the embodiment 3 is not related to guiding the piston rod 7, it is possible to make it shorter as a passage compared to the grooved rib part 27 of the embodiment 1, and to increase the number of the through holes, thereby relatively increasing the opening area, and thereby enabling smoother pressure release.

[0053] In addition, the third embodiment can also achieve the same effects as the first embodiment. [Example]

[0054] 8 is a cross-sectional view of a main part of a linear damper when extended according to Example 4. The basic configuration is the same as that of Example 1, and the same or corresponding components are denoted by the same reference numerals, and redundant explanations will be omitted.

[0055] As shown in FIG. 8, in the linear damper 1 of the fourth embodiment, an O-ring 9 is used instead of the lipped seal ring 9 of the first embodiment.

[0056] Therefore, in the fourth embodiment, the same effects as those in the first embodiment can be achieved. [Example]

[0057] Fig. 9 is a cross-sectional view of a main part of a linear damper when extended according to Example 5. Fig. 10 is an end view of the linear damper of Fig. 9. The basic configuration is the same as that of Example 1, and the same or corresponding components are designated by the same reference numerals, and redundant explanations will be omitted.

[0058] As shown in FIGS. 9 and 10, in the linear damper 1 of the fifth embodiment, a through-hole 45 is formed in the rod guide 25 and the tapered portion 23 by the D-cut of the piston rod 7, and the tapered portion 23 is opened to the outside of the cylinder 3.

[0059] Therefore, in this embodiment 5, the through-hole 45 constitutes a part of the passage of the communication part 39 in place of the groove part 27 in the embodiment 1, and the same effect can be achieved. Moreover, the through-hole 45 in the embodiment 5 can be formed by a D-cut of the piston rod 7, and is easy to manufacture.

[0060] In addition, the fifth embodiment can also achieve the same effects as the first embodiment. [Example]

[0061] Fig. 11 is a cross-sectional view of a main part of a linear damper according to a sixth embodiment when the linear damper is extended. Fig. 12 is a cross-sectional view taken along line XII-XII in Fig. 11. The basic configuration is the same as that of the first embodiment, and the same or corresponding components are designated by the same reference numerals, and redundant explanations will be omitted.

[0062] As shown in Figures 11 and 12, the linear damper 1 of Example 6 has a cylinder 3 with a three-stage structure, and the third stage is used to form a passage that constitutes part of the communication section 39. In other words, a third stage 47 is formed adjacent to the end wall 21. A pair of grooves 47a is formed on the axial inner surface of this stage 47. The grooves 47a extend from the second inner circumferential surface 13b to the tapered section 23.

[0063] Therefore, in the sixth embodiment, the pair of grooves 47a constitute part of the passage of the communication portion 39 in place of the grooves 33ba of the contact surface 33b in the first embodiment, and the same effects can be achieved.

[0064] In addition, the sixth embodiment can also achieve the same effects as the first embodiment. [Example]

[0065] 13 is a cross-sectional view of a main part of a linear damper when extended according to Example 7. The basic configuration is the same as that of Example 1, and the same or corresponding components are denoted by the same reference numerals, and redundant explanations will be omitted.

[0066] As shown in FIG. 13 , in the linear damper 1 of Example 7, the communication portion 39 is provided with a through hole 49 as a passage that connects the inside and outside of the cylinder 3. The through hole 49 is formed in the cylinder 3 between the piston 5 and the seal ring 9. The through hole 49 penetrates the cylinder 3 radially from the inside to the outside. In Example 7, there is no part corresponding to the step portion 19 of Example 1, and the inner surface of the cylinder 3 is formed by the first inner circumferential surface 13a up to the end wall 21. The outer periphery of the flange portion 33 has a set gap with respect to the first inner circumferential surface 13a.

[0067] When the piston 5 retracts relative to the pressure chamber 11 and the contact surface 33b of the flange 33 abuts against the end wall 21 of the cylinder 3, the seal ring 9 moves due to the pressure in the pressure chamber 11 and comes into close contact with the second receiving surface 33a of the flange 33. Due to this close contact, the gap between the flange 33 and the first inner circumferential surface 13a is sealed by the seal ring 9, unlike in the first embodiment. At this time, the through hole 49 is positioned corresponding to the gap between the piston 5 and the seal ring 9.

[0068] Therefore, in Example 7, the through hole 49 forms part of the passage of the communicating portion 39 in place of the passage between the D-cut portion 7a and the inner circumference of the seal ring 9 in Example 1, the passage in the movable space portion 37 between the second receiving surface 33a of the flange portion 33 and the seal ring 9, the passage between the second inner circumference surface 13b of the cylinder 3 and the outer circumference of the flange portion 33, the passage by the groove 33ba between the abutment surface 33b of the flange portion 33 and the end wall 21, the tapered portion 23, and the groove portion 27, and can achieve the same effects.

[0069] In the seventh embodiment, a through-hole 51 is formed in the end wall 21 instead of the passage formed by the groove 33ba between the contact surface 33b of the flange 33 and the end wall 21, the tapered portion 23, and the recessed streak portion 27 of the first embodiment.

[0070] Therefore, when the pressure chamber 11 becomes negative pressure, positive pressure enters through the through-hole 51, and similarly to the first embodiment, the force acting in the retracting direction can be weakened or eliminated even when the piston rod 7 is suddenly extended.

[0071] In addition, the seventh embodiment can also achieve the same effects as the first embodiment. [Example]

[0072] 14 is a cross-sectional view of a main part of a linear damper when extended according to Example 8. The basic configuration is the same as that of Example 1, and the same or corresponding components are denoted by the same reference numerals, and redundant explanations will be omitted.

[0073] 14, the linear damper 1 of Example 8 includes an enlarged inner circumferential surface 53, which forms a passage for the communication portion 39 to communicate between the inside and outside of the cylinder 3. The enlarged inner circumferential surface 53 is formed in the radial direction between the first inner circumferential surface 13a and the end wall 21 in the axial direction, and the inner periphery of the cylinder 3 is enlarged beyond the first inner circumferential surface 13a.

[0074] The piston 5 retracts relative to the pressure chamber 11, causing the contact surface 33b of the flange 33 to abut against the end wall 21 of the cylinder 3. In this abutting state, when the seal ring 9 moves due to the pressure in the pressure chamber 11 or the like, it comes into close contact with the second receiving surface 33a of the flange 33. In this state, the seal ring 9 is no longer in close contact with the first inner circumferential surface 13a and is positioned within the expanded inner circumferential surface 53.

[0075] Therefore, in this embodiment 8, the passage between the enlarged inner peripheral surface 53 and the outer periphery of the seal ring 9 constitutes part of the passage of the communicating portion 39, instead of the passage between the D-cut portion 7a and the inner periphery of the seal ring 9 in embodiment 1, and can achieve the same effect.

[0076] In addition, the eighth embodiment can also achieve the same effects as the first embodiment. [Example]

[0077] 15 is a cross-sectional view of a main part of a linear damper when extended according to Example 9. The basic configuration is the same as that of Example 1, and the same or corresponding components are denoted by the same reference numerals, and redundant explanations will be omitted.

[0078] 15, the linear damper 1 of Example 9 has a through hole 55 formed in the flange portion 33. The through hole 55 allows the movable space portion 37 and the tapered portion 23 to communicate with each other.

[0079] Therefore, in this embodiment 5, the through hole 55 forms part of the passage of the communicating portion 39, replacing the passage between the second inner surface 13b of the cylinder 3 and the outer periphery of the flange portion 33 in embodiment 1, and the passage formed by the groove 33ba between the abutment surface 33b of the flange portion 33 and the end wall 21, and can achieve the same functional effect.

[0080] In addition, the ninth embodiment can also achieve the same effects as the first embodiment. [Example]

[0081] 16 is a cross-sectional view of a main part of a linear damper when extended according to Example 10. The basic configuration is the same as that of Example 1, and the same or corresponding components are designated by the same reference numerals, and redundant explanations will be omitted.

[0082] As shown in Figure 16, the linear damper 1 of Example 10 has a piston rod 7 composed of a first rod portion 7Aa equipped with a flange portion 33 and a D-cut portion 7a, etc., and a second rod portion 7Ab that fits into a rod guide 25. The second rod portion 7Ab is porous and is formed, for example, from a sintered porous resin. The first rod portion 7Aa and the second rod portion 7Ab are integrally joined by fitting together using axially concave and convex portions.

[0083] When the first rod portion 7Aa and the second rod portion 7Ab are coupled together, the end face of the second rod portion 7Ab abuts against the abutment surface 33b and groove 33ba of the flange portion 33. When the flange portion 33 abuts against the end wall 21, the inner end of the second rod portion 7A is substantially flush with the inner surface of the end wall 21.

[0084] Therefore, in this fifth embodiment as well, the porous second rod portion 7Ab constitutes part of the passage of the communication portion 39 in place of the groove portion 27 in the first embodiment, and the same effects can be achieved.

[0085] In addition, the tenth embodiment can also achieve the same effects as the first embodiment. [Example]

[0086] Fig. 17 is a cross-sectional view of a main part of the linear damper when it is extended according to the eleventh embodiment. Fig. 18 is a cross-sectional view taken along the line XVIII-XVIII in Fig. 17. The basic configuration is the same as that of the first embodiment, and the same or corresponding components are designated by the same reference numerals, and redundant explanations will be omitted.

[0087] 17 and 18, the linear damper 1 of the eleventh embodiment has a plate member 57 set on the inner surface of the end wall 21. A slit 57a is formed in the plate member 57. The flange 33 does not have a groove 33ba.

[0088] Therefore, in this eleventh embodiment, the slit 57a of the plate member 57 constitutes part of the passage of the communication portion 39 in place of the groove 33ba of the flange portion 33 in the first embodiment, and the same effects can be achieved.

[0089] In addition, the eleventh embodiment can also achieve the same effects as the first embodiment. [Example]

[0090] Fig. 19 is a cross-sectional view of a main part of a linear damper when extended according to Example 12. Fig. 20 is an end view of the linear damper of Fig. 19. The basic configuration is the same as that of Example 1, and the same or corresponding components are designated by the same reference numerals, and redundant explanations will be omitted.

[0091] As shown in Figures 19 and 20, the linear damper 1 of Example 12 has a through-hole 59 in the shoulder portion on the end wall 21 side of the cylinder 3. The through-hole 59 penetrates the cylinder 3 from the inside to the outside. In Example 12, there is no part corresponding to the step 19 of Example 1, and the inner surface of the cylinder 3 is formed by the first inner circumferential surface 13a all the way to the end wall 21. The outer periphery of the flange 33 has a set gap with respect to the first inner circumferential surface 13a.

[0092] When the piston 5 retracts relative to the pressure chamber 11 and the contact surface 33b of the flange 33 abuts against the end wall 21 of the cylinder 3, the seal ring 9 moves due to the pressure in the pressure chamber 11 or the like, and comes into close contact with the second receiving surface 33a of the flange 33. Due to this close contact, the gap between the flange 33 and the first inner circumferential surface 13a is sealed by the seal ring 9, unlike in the first embodiment. At this time, one end of the through portion 59 is positioned between the piston 5 and the seal ring 9.

[0093] Therefore, in Example 12, the passage between the D-cut portion 7a and the inner circumference of the seal ring 9 in Example 1, the passage within the movable space portion 37 between the second receiving surface 33a of the flange portion 33 and the seal ring 9, the passage between the second inner circumference surface 13b of the cylinder 3 and the outer circumference of the flange portion 33, the passage by the groove 33ba between the abutment surface 33b of the flange portion 33 and the end wall 21, the tapered portion 23, and the groove portion 27 are replaced by the through portion 59 to form part of the passage of the communicating portion 39, and similar effects can be achieved.

[0094] Furthermore, in Example 12, as in Example 7, a through portion 51 is formed in the end wall 21 instead of the passage formed by the groove 33ba between the abutment surface 33b of the flange portion 33 and the end wall 21, the tapered portion 23, and the groove portion 27 of Example 1.

[0095] Therefore, when the pressure chamber 11 becomes negative pressure, positive pressure enters through the through-hole 51, and similarly to the first embodiment, the force acting in the retracting direction can be weakened or eliminated even when the piston rod 7 is suddenly extended.

[0096] In addition, the twelfth embodiment can also achieve the same effects as the first embodiment. [Explanation of symbols]

[0097] 1. Linear damper 3 cylinders 5 pistons 7 Piston rod 7Aa First rod part 7Ab Second rod part (passage) 7a D-cut section 9 Seal ring 11 Pressure Chamber 13a First inner surface 13b Second inner peripheral surface 19 Step section 21 End Wall 23 Tapered section 25 Rod guide 27 Concave part (passage) 29 heads 31 Spring seal receiving part 31a 1st receiving surface 31ab groove (passage) 32 Return spring 33 Tsuba 33a 2nd receiving surface 33b Contact surface 33ba groove (passage) 35 Seal mounting part 37 Movable space part 39 Communication section 41 Passageway 43 Through hole (passage) 45 Passageway 47 Step part 47a Groove (passage) 49 Through hole (passage) 51 Passageway 53 Enlarged inner surface (passageway) 55 Passageway 57 Board material 57a Slit (passageway) 59 Passageway

Claims

1. a cylinder for forming a pressure chamber; a piston that is housed in the cylinder and defines the pressure chamber and is movable toward and away from the defined pressure chamber; a piston rod that is provided coaxially with the piston and protrudes outside the cylinder and moves in conjunction with the forward and backward movement; a flange portion provided on the piston rod and arranged opposite to the piston in the direction of the forward and backward movement; a circumferential seal mounting portion provided on the outer periphery of the piston rod between the piston and the flange; a seal ring that is fitted and attached to the seal attachment portion to provide a seal between the cylinder and the piston; a movable space portion that allows the seal ring to move relatively between the piston and the flange portion in the direction of the forward and backward movement; a communication portion that communicates the pressure chamber with the outside of the cylinder via the movable space portion in a state in which the piston retracts relative to the pressure chamber and the flange abuts against the cylinder; Direct acting damper equipped with

2. The linear damper of claim 1, the cylinder includes a step portion that stops the movement of the seal ring when the seal ring moves within the movable space portion due to the internal pressure of the pressure chamber, thereby maintaining a gap between the seal ring and the flange portion; the communication portion has a passage between an inner periphery of the seal ring and the piston rod, the passage communicates the pressure chamber with the outside of the cylinder via the movable space portion; Direct acting damper.

3. The linear damper of claim 1, the communication portion includes a passage that communicates the inside and outside of the cylinder, The passage connects the movable space between the piston and the seal ring to the outside. Direct acting damper.

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