Balancer and balancer manufacturing method for manufacturing the balancer

Abstract

To provide a balancer capable of suppressing generation of rust at an end part of a cylinder .SOLUTION: A balancer 1A includes: a cylinder 2 having an opening part 5 in which an opening 4 is formed at an end part on one end side and that is filled with gas; a piston rod 3 internally inserted into the cylinder 2; a rod guide 9A disposed in the cylinder 2 to guide the piston rod 3; and a cylinder cap 8A that is mounted to the opening part 5 to come into contact with the rod guide 9A and on which the piston rod 3 slides. One end side of the cylinder 2 has a flange part 6 protruded from a peripheral edge of the cylinder 2 to the piston rod 3 side, and the flange part 6 has the opening part 5. The cylinder cap 8A has a connection part 25 located adjacent to an inner peripheral surface of the opening 4 formed on the opening part 5, and a bonding layer is provided at least between the inner peripheral surface and the connection part 25.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a balancer used for opening and closing a back door of a vehicle and a method for manufacturing the balancer. [Background technology]

[0002] Hatchback and minivan vehicles are provided with flip-up back doors, and a balancer such as a gas spring is provided to reduce the force required to open the back door. One example of a balancer used in a back door is the gas spring disclosed in FIG. 8 of Patent Document 1.

[0003] The gas spring disclosed in Patent Document 1 has a rod guide and a seal member at the opening of a cylindrical cylinder, and the piston rod is inserted into the cylinder via the rod guide and the seal member. The rod guide is fixed to the cylinder by bending the end of the cylinder inward and crimping it. Usually, the outer surface of the cylinder is painted to prevent rust. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 08-145103 Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the outer surface of the cylinder is painted to prevent rust, the paint on the end faces of the cylinder is prone to chipping and the paint can only be applied thinly, meaning that there is a risk of rust occurring when exposed to air.

[0006] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a balancer capable of suppressing the occurrence of rust at the ends of the cylinders, and a method for manufacturing such a balancer. [Means for solving the problem]

[0007] One aspect of the present invention is a balancer having a cylinder having an opening formed at an end on one side and filled with gas, a piston rod inserted into the cylinder, a rod guide disposed in the cylinder and guiding the piston rod, and a cylinder cap attached to the opening in contact with the rod guide and in which the piston rod slides, wherein one end of the cylinder has a flange portion extending from the periphery of the cylinder toward the piston rod, the flange portion having an opening, the cylinder cap having a connection portion adjacent to an inner circumferential surface of the opening formed in the opening, and an adhesive layer provided at least between the inner circumferential surface and the connection portion. Another aspect of the present invention is a balancer manufacturing method for manufacturing the balancer according to one aspect of the present invention. Effect of the Invention

[0008] According to the present invention, it is possible to provide a balancer that can suppress the occurrence of rust at the end of the cylinder, and a method for manufacturing such a balancer. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a vertical sectional view of a balancer according to a first embodiment. [Diagram 2] FIG. 2 is a vertical sectional view of a cylinder cap of the balancer according to the first embodiment. [Diagram 3] FIG. 11 is a vertical sectional view of a balancer according to a second embodiment. [Figure 4] FIG. 11 is a vertical sectional view of a balancer according to a third embodiment. [Diagram 5] FIG. 11 is a vertical sectional view of a balancer according to a fourth embodiment. [Figure 6] FIG. 13 is a vertical sectional view of a balancer according to a fifth embodiment. [Figure 7] FIG. 13 is a vertical sectional view of a balancer according to a sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a balancer and a method for manufacturing a balancer according to the present invention will be described with reference to the accompanying drawings.

[0011] FIG. 1 is a longitudinal cross-sectional view showing one end side of a part of a balancer 1A according to a first embodiment of the present invention in an axial cross-section. The balancer 1A is used to reduce the operating force required to open a hatchback or one-box vehicle that is provided with a flip-up back door. The balancer 1A has a cylinder 2 in which gas is sealed and a piston rod 3 inserted into the cylinder 2. In this embodiment, the central axis direction of the cylinder 2 in FIG. 1 is the "axial direction", the lower side of the cylinder 2 in FIG. 1 is the "one end side", and the upper side is the "other end side". The direction perpendicular to the axial direction of the cylinder 2 is the "radial direction". The inside side of the cylinder 2 is the "inner side", and the outside side of the cylinder 2 is the "outer side".

[0012] The cylinder 2 has an opening 5 with an opening 4 formed at one end, and the other end is closed to form a cylindrical shape. The one end of the cylinder 2 has a flange portion 6 formed by bending from the periphery of the cylinder 2 toward the piston rod 3 side, i.e., toward the central axis. Therefore, the flange portion 6 is structured to protrude from the periphery of the cylinder 2 toward the piston rod 3 side. The flange portion 6 is the end of the one end of the cylinder 2, the flange portion 6 has an opening 5, and the opening 4 is formed in the opening 5 of the flange portion 6. That is, the part of the flange portion 6 where the opening 4 is formed becomes the opening 5. The outer end surface of the flange portion 6 becomes the end surface of the one end of the cylinder 2, and the tip surface of the flange portion 6 on the central axis side becomes the inner peripheral surface of the opening 4. The cylinder 2 is made of a metal such as aluminum, and the outer peripheral surface of the cylinder 2 is painted for rust prevention. A piston (not shown) is provided at the other end of the piston rod 3, and when the piston is inserted inside the cylinder 2, it divides the rod chamber 7 side at one end side and the piston chamber side at the other end side. 1 does not show the other end of the cylinder 2. Also, the rod chamber 7 is shown, but the piston chamber is omitted.

[0013] The balancer 1A also includes a cylinder cap 8A attached to the opening 5 and on which the piston rod 3 slides, a rod guide 9A in contact with the cylinder cap 8A and guiding the piston rod 3, a seal ring 10 that seals the gap between the inner peripheral surface of the cylinder 2 and the outer peripheral surface of the piston rod 3, an oil cushion 11 as an impregnated member impregnated with oil, and a stopper 12 that suppresses the movement of the oil cushion 11 to the other end side, which are arranged in this order from a flange portion 6, which is an end portion on one end side of the cylinder 2, toward the other end side. The cylinder cap 8A is attached to the opening 5 and seals the opening 4 of the cylinder 2 in a state in which the piston rod 3 is inserted. Specifically, the cylinder cap 8A seals the gap between the inner peripheral surface of the opening 4 and the outer peripheral surface of the piston rod 3. When the cylinder cap 8A is attached to the opening 5 of the cylinder 2, the other end side of the cylinder cap 8A, i.e., the rod guide 9A side of the cylinder cap 8A, is inserted inside the cylinder 2, and one end side of the cylinder cap 8A, i.e., the side opposite the rod guide 9A side of the cylinder cap 8A, is exposed outside from the end face of the end of one end side of the cylinder 2.

[0014] The rod guide 9A, the seal ring 10, the oil cushion 11, and the stopper 12 are disposed inside the cylinder 2. One end face of the rod guide 9A contacts the other end face of the cylinder cap 8A, one end face of the seal ring 10 contacts the other end face of the rod guide 9A, one end face of the oil cushion 11 contacts the other end face of the seal ring 10, and one end face of the stopper 12 contacts the other end face of the oil cushion 11. An insertion hole for inserting the piston rod 3 is formed at the axial center of each of the cylinder cap 8A, the rod guide 9A, the seal ring 10, the oil cushion 11, and the stopper 12. The inside of the cylinder 2 is filled with oil to improve the sliding property between the inner peripheral surface of the cylinder 2 and the outer peripheral surface of the piston. The oil filled is a highly hydrophobic mineral oil or a synthetic oil such as polyalphaolefin. By using a highly hydrophobic oil, it is possible to prevent water from entering the inside of the cylinder 2 through the oil, and to prevent corrosion inside the cylinder 2.

[0015] The cylinder cap 8A will be described with reference to FIG. 2. FIG. 2 is a vertical cross-sectional view of the cylinder cap 8A, showing the shape of the cylinder cap 8A when it is not attached to the opening 5 of the cylinder 2. The two-dot chain line shown in FIG. 2 shows the end of one end side of the cylinder 2 including the flange portion 6 when the cylinder cap 8A is attached to the opening 5. The material of the cylinder cap 8A is a thermoplastic resin. The material of the rod guide 9A is a thermosetting resin, and the material of the cylinder cap 8A is a material that is softer than the material of the rod guide 9A. Examples of the material of the cylinder cap 8A include polyethylene, polyamide, and ABS. Examples of the material of the rod guide 9A include phenolic resin and epoxy resin.

[0016] The cylinder cap 8A has a conical section 20 with a tapered outer diameter that decreases toward the tip side, and a cylindrical rear end section 21 that is disposed on the other end side of the conical section 20 and is formed integrally with the conical section 20. A through hole 22 into which the piston rod 3 is inserted is formed in the axial center of the cylinder cap 8A. The diameter of the through hole 22 is determined so that an inner peripheral surface 23 of the through hole 22 can slide in close contact with the outer peripheral surface of the piston rod 3.

[0017] When the cylinder cap 8A is attached to the opening 5, a part of the cone portion 20 is elastically deformed, and the outer peripheral surface of a part of the cone portion 20 contacts the inner peripheral surface of the opening 4. Also, the rear end portion 21 is elastically deformed, and the outer peripheral surface of the rear end portion 21 contacts the inner peripheral surface of the cylinder 2. The cone portion 20 has a tip portion 24 exposed to the outside of the cylinder 2 when the cylinder cap 8A is attached to the opening 5, and a connection portion 25 that is elastically deformed and has an outer peripheral surface adjacent to the inner peripheral surface of the opening 4. That is, when the cylinder cap 8A is attached to the opening 5, the cylinder cap 8A has a tip portion 24 exposed to the outside of the cylinder 2, a connection portion 25 whose outer peripheral surface is adjacent to the inner peripheral surface of the opening 4, and a rear end portion 21 whose outer peripheral surface contacts the inner peripheral surface of the cylinder 2. The outer diameter dimension of the connection portion 25 when the cylinder cap 8A is not attached to the opening 5 is set to be larger than the inner diameter dimension of the opening 4. Therefore, when the cylinder cap 8A is attached to the opening 5, the outer peripheral surface of the connection part 25 is in close contact with and adjacent to the inner peripheral surface of the opening 4. The outer peripheral surface of the connection part 25 is fixed to the inner peripheral surface of the opening 4 with an adhesive, and an adhesive layer 26 is provided between the inner peripheral surface of the opening 4 and the outer peripheral surface of the connection part 25 (see FIG. 1).

[0018] The tip surface of flange portion 6, which is the inner surface of opening 4, is painted to prevent rust, but the paint is prone to chipping and can only be applied thinly, so there was a risk of rust occurring when it comes into contact with air. However, by providing adhesive layer 26 between the inner surface of opening 4 and the outer surface of connecting portion 25, it is possible to suppress the occurrence of rust on the tip surface of flange portion 6, which is the inner surface of opening 4.

[0019] In this embodiment, when the cylinder cap 8A is attached to the opening 5, the outer circumferential surface of the cone portion 20 on the other end side than the connection portion 25 contacts the inner end surface of the flange portion 6, which is the inner surface of the cylinder 2. Also, when the cylinder cap 8A is attached to the opening 5, the outer circumferential surface of the rear end portion 21 contacts the inner circumferential surface of the cylinder 2. However, the outer circumferential surface of the cone portion 20 on the other end side than the connection portion 25 and the outer circumferential surface of the rear end portion 21 are non-fixed portions that are not bonded and fixed to the inner surface of the cylinder 2 with an adhesive. Therefore, no adhesive layer 26 is provided between the outer circumferential surface of the cone portion 20 on the other end side than the connection portion 25 and the outer circumferential surface of the rear end portion 21 and the inner surface of the cylinder 2. If the outer peripheral surface of the rear end portion 21 is adhesively fixed to the inner peripheral surface of the cylinder 2, the rear end portion 21, which is made of a soft material, is less likely to deform because the rear end portion 21 is fixed to the inner peripheral surface of the cylinder 2, and as a result, when the piston moves toward one end of the cylinder 2 and hits the oil cushion 11, the rod guide 9A and the seal ring 10 may be damaged. However, in this embodiment, the outer peripheral surface of the conical portion 20 on the other end side than the connecting portion 25 and the outer peripheral surface of the rear end portion 21 are non-fixed portions that are not adhesively fixed to the inner peripheral surface of the cylinder 2 with an adhesive, so that even when the piston moves toward one end of the cylinder 2 and hits the oil cushion 11, damage to the rod guide 9A and the seal ring 10 can be suppressed.

[0020] The other end face of the rear end portion 21, which is the other end face of the cylinder cap 8A that contacts the one end face of the rod guide 9A, i.e., the end face of the cylinder cap 8A on the rod guide 9A side, has a recess 27 formed in a concave shape. The one end face of the rod guide 9A that contacts the other end face of the cylinder cap 8A, i.e., the end face of the rod guide 9A on the cylinder cap 8A side, has a protrusion 28 formed in a convex shape. The protrusion 28 of the rod guide 9A is fitted into the recess 27 of the cylinder cap 8A. The contact portions of the cylinder cap 8A and the rod guide 9A are joined by welding, adhesion, fitting, etc., and the cylinder cap 8A is fixed integrally to the rod guide 9A.

[0021] Since the rod guide 9A is made of a hard material and the cylinder cap 8A is made of a soft material, the cylinder cap 8A is fixed integrally to the rod guide 9A, thereby providing both a function of guiding the piston rod 3 and a mechanism for preventing the sealing performance of the seal ring 10 from being impaired by the inclusion of foreign matter such as sand grains. In particular, one end side of the cylinder cap 8A is formed in a conical shape, the inner peripheral surface 23 of the through hole 22 of the cylinder cap 8A is in close contact with the outer peripheral surface of the piston rod 3, and the outer diameter dimension of the connection part 25 of the cylinder cap 8A is set to be smaller than the inner diameter dimension of the opening 4, so that when the piston rod 3 slides on the cylinder cap 8A, foreign matter can be prevented from entering the inside of the cylinder 2, and gas leakage due to the inclusion of foreign matter can be prevented.

[0022] In this embodiment, the outer circumferential surface of the conical portion 20 on the other end side than the connection portion 25 and the outer circumferential surface of the rear end portion 21 are non-fixed portions that are not bonded and fixed with an adhesive, but are not necessarily limited to this. The outer circumferential surface of the conical portion 20 on the other end side than the connection portion 25 may be fixed to the inner end surface of the flange portion 6 with an adhesive. The outer circumferential surface of the conical portion 20 on the other end side than the connection portion 25 is in contact with the inner end surface of the flange portion 6 with an adhesive but is not in contact with the inner circumferential surface of the cylinder 2, so that deformation is possible, and even if the piston moves toward one end side of the cylinder 2 and hits the oil cushion 11, damage to the rod guide 9A and the seal ring 10 can be suppressed.

[0023] In this embodiment, the outer peripheral surface of the connection part 25 is fixed to the inner peripheral surface of the opening 4 with an adhesive, but the adhesive in this embodiment also includes, for example, a heat-sealed film that adheres and fixes the outer peripheral surface of the connection part 25 to the inner peripheral surface of the opening 4 by welding with heat. By using a heat-sealed film as an adhesive, the heat of the coating material when painting the cylinder 2 can be used to weld the heat-sealed film, thereby adhering and fixing the outer peripheral surface of the connection part 25 to the inner peripheral surface of the opening.

[0024] Next, a method for manufacturing the balancer 1A will be described. The balancer 1A is manufactured according to the following steps. (i) First step: Prepare a cylinder forming body for forming the cylinder 2, the cylinder forming body having an installation opening formed at one end before the flange portion 6 is bent and formed. (ii) Second step: Apply adhesive to a predetermined portion of the cylinder cap 8A. The predetermined portion of the cylinder cap 8A to which the adhesive is applied is a portion that corresponds to the outer peripheral surface of the connection portion 25 adjacent to the inner peripheral surface of the opening 4 when the cylinder cap 8A is attached to the opening 5. (iii) Third step: The piston rod 3, to which the cylinder cap 8A, rod guide 9A, seal ring 10, oil cushion 11 and stopper 12 are attached, is inserted into the cylinder former through the opening of the installation opening. (iv) Fourth step: Oil and gas are filled into the cylinder-formed body. The oil to be filled is a highly hydrophobic mineral oil or a synthetic oil such as polyalphaolefin. (v) Fifth step: One end of the cylinder forming body is bent toward the central axis, which is the piston rod 3 side, to form the flange portion 6, and the cylinder cap 8A is crimped and fixed. Since adhesive has been applied to a predetermined portion of the cylinder cap 8A in the first step, by bending one end of the cylinder forming body toward the central axis, which is the piston rod 3 side, and crimping it, the cylinder cap 8A is fixed to the tip surface of the flange portion 6 formed by bending, i.e., the inner circumferential surface of the opening 4, via the adhesive.

[0025] The balancer 1A according to this embodiment has an opening 5 with an opening 4 formed at an end on one end side, a cylinder 2 in which gas is sealed, a piston rod 3 inserted into the cylinder 2, a rod guide 9A arranged in the cylinder 2 to guide the piston rod 3, and a cylinder cap 8A attached to the opening 5 in contact with the rod guide 9A and in which the piston rod 3 slides. One end side of the cylinder 2 has a flange portion 6 that protrudes from the periphery of the cylinder 2 toward the piston rod 3 side, the flange portion 6 has an opening 5, and the cylinder cap 8A has a connection portion 25 adjacent to the inner circumferential surface of the opening 4 formed in the opening 5, and an adhesive layer is provided at least between the inner circumferential surface and the connection portion 25. This makes it possible to suppress the occurrence of rust on the tip surface of the flange portion 6, which is the inner circumferential surface of the opening 4.

[0026] Next, a balancer 1B according to a second embodiment will be described with reference to Fig. 3. The difference between the balancer 1B according to the second embodiment and the balancer 1A according to the first embodiment is that the configurations of the cylinder cap 8B and the rod guide 9B of the balancer 1B according to the second embodiment are different from the configurations of the cylinder cap 8A and the rod guide 9A of the balancer 1A according to the first embodiment, and there are no other differences. In the description of the cylinder cap 8B and the rod guide 9B of the balancer 1B according to the second embodiment, the same reference numerals are used for the configurations common to the cylinder cap 8A and the rod guide 9A of the balancer 1A according to the first embodiment, and the description of the common configurations will be omitted.

[0027] The cylinder cap 8B of the second embodiment differs from the cylinder cap 8A of the first embodiment in that it does not have a recess 27 at the rear end 21. The other configurations are the same as those of the cylinder cap 8A of the first embodiment. Therefore, the rod guide 9B of the second embodiment does not have a protrusion 28. An end face on one end side of the rod guide 9B contacts an end face on the other end side of the cylinder cap 8B, and the contact portions of the cylinder cap 8B and the rod guide 9B are joined by welding, adhesion, fitting, etc., and the cylinder cap 8B is fixed integrally to the rod guide 9B.

[0028] Like the cylinder cap 8A of the first embodiment, in the cylinder cap 8B of the second embodiment, the outer peripheral surface of the connection portion 25 is fixed to the inner peripheral surface of the opening 4 with an adhesive, and an adhesive layer 26 is provided between the inner peripheral surface of the opening 4 and the outer peripheral surface of the connection portion 25. The outer peripheral surface of the cone portion 20 on the other end side than the connection portion 25 and the outer peripheral surface of the rear end portion 21 are non-fixed portions that are not bonded or fixed with an adhesive.

[0029] Next, a balancer 1C according to a third embodiment will be described with reference to Fig. 4. The difference between the balancer 1C according to the third embodiment and the balancer 1A according to the first embodiment is that the configurations of the cylinder cap 8C and the rod guide 9C of the balancer 1C according to the third embodiment are different from the configurations of the cylinder cap 8A and the rod guide 9A of the balancer 1A according to the first embodiment, and there are no other differences. In the description of the cylinder cap 8C and the rod guide 9C of the balancer 1C according to the third embodiment, the same reference numerals are used for the configurations common to the cylinder cap 8A and the rod guide 9A of the balancer 1A according to the first embodiment, and the description of the common configurations will be omitted.

[0030] The cylinder cap 8C of the third embodiment differs from the cylinder cap 8A of the first embodiment in that it does not have a tip portion 24 exposed to the outside of the cylinder 2 when the cylinder cap 8C is attached to the opening 5 of the cylinder 2. Therefore, the end face of one end of the cylinder 2 and the end face of one end of the cylinder cap 8C are flush (flat). The rod guide 9C of the third embodiment also differs from the rod guide 9A of the first embodiment in that it does not have a protrusion 28. In the third embodiment, the entire rod guide 9C is inserted into the recess 27 of the cylinder cap 8C. The contact portion between the cylinder cap 8C and the rod guide 9C is joined by welding, adhesion, fitting, etc., and the cylinder cap 8C is fixed integrally to the rod guide 9C.

[0031] Like the cylinder cap 8A of the first embodiment, in the cylinder cap 8C of the third embodiment, the outer peripheral surface of the connection portion 25 is fixed to the inner peripheral surface of the opening 4 with an adhesive, and an adhesive layer 26 is provided between the inner peripheral surface of the opening 4 and the outer peripheral surface of the connection portion 25. The outer peripheral surface of the rear end portion 21 on the other end side than the connection portion 25 is a non-fixed portion that is not adhesively fixed with an adhesive.

[0032] Next, a balancer 1D according to a fourth embodiment will be described with reference to FIG. 5. The difference between the balancer 1D according to the fourth embodiment and the balancer 1A according to the first embodiment is that the configurations of the cylinder cap 8D and the rod guide 9D of the balancer 1D according to the fourth embodiment are different from the configurations of the cylinder cap 8A and the rod guide 9A of the balancer 1A according to the first embodiment, and other configurations are the same. In addition, the manufacturing method of the balancer 1D according to the fourth embodiment is different from the manufacturing method of the balancer 1A according to the first embodiment. In the description of the cylinder cap 8D and the rod guide 9D of the balancer 1D according to the fourth embodiment, the same reference numerals are used for the configurations common to the cylinder cap 8A and the rod guide 9A of the balancer 1A according to the first embodiment, and the description of the common configurations is omitted.

[0033] The cylinder cap 8D has a tip portion 24 exposed to the outside of the cylinder 2, a connection portion 25 in contact with the inner peripheral surface of the opening 4, and a rear end portion 21 in contact with the inner peripheral surface of the cylinder 2 when the cylinder cap 8D is attached to the opening 5. The tip portion 24 has an outer layer portion 29 that covers the end face on one end side of the cylinder 2 and the outer peripheral surface of the cylinder 2. The rear end portion 21 has a tapered portion 30 in which an edge portion formed by the end face on the other end side and the outer periphery is chamfered. The outer diameter of the rear end portion 21 is larger than the inner diameter of the opening 4, and is set to a dimension that allows it to be inserted into the opening 4 by elastic deformation. When the cylinder cap 8D is attached to the opening 5, the outer peripheral surface of the connection portion 25 is fixed to the inner peripheral surface of the opening 4 with an adhesive, and an adhesive layer 26 is provided between the inner peripheral surface of the opening 4 and the outer peripheral surface of the connection portion 25. The end face on one end side of the rod guide 9D has a recess formed in a concave shape, and the rear end portion 21 is fitted into the recess.

[0034] In the manufacturing method of the balancer 1A according to the first embodiment, in the third step, the piston rod 3 to which the cylinder cap 8A, rod guide 9A, seal ring 10, oil cushion 11 and stopper 12 are attached is inserted into the cylinder forming body, and in the fifth step, one end side of the cylinder forming body is bent from the periphery of the cylinder forming body toward the central axis side, which is the piston rod 3 side, and the cylinder cap 8A is crimped and fixed. On the other hand, in the manufacturing method of the balancer 1D according to the fourth embodiment, in the second step, the piston rod 3 to which the rod guide 9D, seal ring 10, oil cushion 11 and stopper 12 are attached is inserted into the cylinder forming body, but the cylinder cap 8D is not inserted into the cylinder forming body, which is different from the manufacturing method of the balancer 1A according to the first embodiment.

[0035] A method for manufacturing the balancer 1D of the fourth embodiment will be described below. The balancer 1D is manufactured according to the following steps. (i) First step: Prepare a cylinder forming body for forming the cylinder 2, the cylinder forming body having an installation opening formed at one end before the flange portion 6 is bent and formed. (ii) Second step: Apply adhesive to a predetermined portion of the cylinder cap 8D. The predetermined portion of the cylinder cap 8D to which the adhesive is applied is a portion that corresponds to the outer peripheral surface of the connection portion 25 that contacts the inner peripheral surface of the opening 4 when the cylinder cap 8D is attached to the opening 5 of the cylinder 2. (iii) Third step: The piston rod 3, to which the rod guide 9D, the seal ring 10, the oil cushion 11 and the stopper 12 are attached, is inserted into the cylinder former through the opening of the installation opening. (iv) Fourth step: Oil and gas are filled into the cylinder-formed body. The oil to be filled is a highly hydrophobic mineral oil or a synthetic oil such as polyalphaolefin. (v) Fifth step: One end of the cylinder forming body is bent toward the central axis side, which is the piston rod 3 side, to form a flange portion 6 so that an opening 4 is formed. (vi) Sixth step: The rear end 21 of the cylinder cap 8D is fitted into the opening 4 formed in the flange portion 6 that is formed by bending, thereby attaching the cylinder cap 8D to the opening 5.

[0036] Next, a balancer 1E according to a fifth embodiment will be described with reference to Fig. 6. The difference between the balancer 1E according to the fifth embodiment and the balancer 1D according to the fourth embodiment is that the configuration of the cylinder cap 8E of the balancer 1E according to the fifth embodiment is different from the configuration of the cylinder cap 8D of the balancer 1D according to the fourth embodiment, and there are no other differences in configuration. In the description of the cylinder cap 8E of the balancer 1E according to the fifth embodiment, the same reference numerals are used for configurations common to the cylinder cap 8E of the balancer 1D according to the fourth embodiment, and a description of the common configurations will be omitted.

[0037] In the cylinder cap 8D of the balancer 1D according to the fourth embodiment, the tip portion 24 has an outer layer portion 29 that covers one end face of the cylinder 2 and the outer circumferential surface of the cylinder 2, but the cylinder cap 8E of the balancer 1E according to the fifth embodiment does not have an outer layer portion 29. The other configurations are the same as those of the cylinder cap 8D of the balancer 1D according to the fourth embodiment.

[0038] Next, a balancer 1F according to a sixth embodiment will be described with reference to Fig. 7. The difference between the balancer 1F according to the sixth embodiment and the balancer 1E according to the fifth embodiment is that the configuration of the rod guide 9F of the balancer 1F according to the sixth embodiment is different from the configuration of the rod guide 9D of the balancer 1E according to the fifth embodiment, and there are no other differences in configuration. In the description of the balancer 1F according to the sixth embodiment, the same reference numerals are used for configurations common to the balancer 1E according to the fifth embodiment, and a description of the common configurations will be omitted.

[0039] In the balancer A of the first embodiment to the balancer 1E of the fifth embodiment, the contact portions between the cylinder caps 8A-8E and the rod guides 9A-9D are joined and fixed together by welding, adhesion, fitting, etc. However, in the balancer 1F of the sixth embodiment, the cylinder cap 8E and the rod guide 9F are not fixed together, and a space 31 is formed between the cylinder cap 8E and the rod guide 9F.

[0040] The rod guide 9F has an inner recess 32 formed in a concave shape between the end face on the cylinder cap 8E side, which is the end face on one end side of the rod guide 9F, and the inner circumferential surface. The inner recess 32 of the rod guide 9F forms a space 31 between the cylinder cap 8E and the rod guide 9F. The space 31 allows the cylinder cap 8F to deform toward the other end side, which is the rod guide 9F side, and when a foreign object is caught, the cylinder cap 8F comes off, making it possible to detect the caught foreign object.

[0041] Although the embodiment and its modified examples of the present invention have been described above, the present invention is not limited to the above-described embodiment and modified examples, and further modifications and changes are possible based on the technical concept of the present invention. [Explanation of symbols]

[0042] 1A…Balancer 1B…Balancer 1C…Balancer 1D…Balancer 1E…Balancer 1F…Balancer 2...Cylinder 3...Piston rod 4…Aperture 5…Opening 6...Flange section 7…Rod room 8A…Cylinder cap 8B…Cylinder cap 8C…Cylinder cap 8D…Cylinder cap 8E…Cylinder cap 8F…Cylinder cap 9A…Rod guide 9B…Rod guide 9C…Rod guide 9D…Rod guide 9F…Rod guide 10…Seal ring 11...Oil cushion 12...Stopper 20…Cone section 21...Rear end 22...Through hole 23…Inner peripheral surface 24...Tip 25…Connection 26...adhesive layer 27…Recess 28…Convex part 29…Outer layer part 30...Tapered section 31…Space 32…Inner recess

Claims

1. a cylinder having an opening formed at one end and filled with gas; A piston rod inserted into the cylinder; A rod guide disposed in the cylinder to guide the piston rod; a cylinder cap attached to the opening in contact with the rod guide, in which the piston rod slides; In a balancer having One end side of the cylinder has a flange portion that protrudes from a periphery of the cylinder toward the piston rod, and the flange portion has the opening, the cylinder cap has a connection portion formed in the opening and adjacent to an inner circumferential surface of the opening, A balancer comprising: an adhesive layer provided between at least the inner circumferential surface and the connecting portion.

2. The cylinder cap is fixed integrally to the rod guide, 2. The balancer according to claim 1, wherein the material of the cylinder cap is softer than the material of the rod guide.

3. The end surface of the cylinder cap on the rod guide side has a recess formed in a concave shape, The end surface of the rod guide on the cylinder cap side has a convex portion formed in a convex shape, 3. The balancer according to claim 2, wherein the protrusion is fitted into the recess.

4. the cylinder cap has a rear end portion that is disposed within the cylinder on the rod guide side of the connection portion when the cylinder cap is attached to the opening, 2. The balancer according to claim 1, wherein the rear end portion has an outer circumferential surface that contacts an inner circumferential surface of the cylinder, the outer circumferential surface being a non-fixed portion that is not adhesively fixed to the inner circumferential surface of the cylinder.

5. the cylinder cap has a front end portion exposed to the outside of the cylinder on the opposite side to the rear end portion of the connection portion when the cylinder cap is attached to the opening, 5. The balancer according to claim 4, wherein the tip portion is formed in a tapered shape such that an outer diameter thereof decreases toward one end.

6. A method for manufacturing the balancer according to any one of claims 1 to 5, comprising the steps of: a first step of preparing a cylinder forming body for forming the cylinder, the cylinder forming body having an assembly opening formed at one end side in a state before the flange portion is bent and formed; a second step of applying an adhesive to the connection portion of the cylinder cap; a third step of inserting the piston rod, to which the cylinder cap and the rod guide are attached, into the cylinder forming body through an opening of the installation opening; A fourth step of sealing oil and gas in the cylinder forming body; and a fifth step of forming the flange portion by bending one end side of the cylinder forming body toward the piston rod, and crimping and fixing the cylinder cap.

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