JP2017003019A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorber capable of improving the degree of freedom in changing spring characteristics. SOLUTION: A rod 2 movably inserted into a cylinder 1, a cylindrical first chamber member 40 connected to the rod 2, and an outer periphery of the first chamber member 40 connected to the rod 2 are provided. Between the first chamber member 40 and the second chamber member 41, a mounting position is provided between the cylindrical second chamber member 41 and the first chamber member 40 and the second chamber member 41 so as to be changeable in the axial direction. A movable partition wall 44 that divides an outer peripheral space k1 formed between the rod side chamber k10 and the cylinder side chamber k11, and an inner peripheral space k2 formed between the first chamber member 40 and the rod 2 and the rod side chamber k10. And a first air chamber G1 that is enlarged and reduced by relative movement between the cylinder 1 and the rod 2. [Selection] Figure 2

Description

  The present invention relates to a shock absorber.

  The shock absorber is used as a rear cushion unit that supports a rear wheel of a straddle-type vehicle such as a two-wheeled vehicle or a three-wheeled vehicle. Among such rear cushion units, there is a pneumatic spring type rear cushion unit that has a gas spring and elastically supports the vehicle body using the elastic force of gas (for example, Patent Document 1).

JP 2001-501155 A, FIGS.

  The rear shock absorber described in JP-T-2001-501155 includes a tubular upper tubular member and a lower tubular member that are slidable in a mutually nested manner, and a piston rod that is connected to the upper tubular member and enters and exits the lower tubular member. And a first chamber formed between the piston rod and the upper tubular member, a second chamber formed between overlapping portions of the upper tubular member and the lower tubular member, and an outer periphery of the lower tubular member And a compressor piston that partitions the first and second chambers. And gas is enclosed in a 1st chamber and it functions as a positive spring which urges a rear shock absorber in the extension direction. In addition, gas is also sealed in the second chamber to function as a negative spring that biases the rear shock absorber in the contraction direction.

  According to such a configuration, the spring characteristics of the entire apparatus can be changed not only by adjusting the pressure in the first chamber but also by adjusting the pressure in the second chamber. And in the rear shock absorber described in JP-T-2001-501155, a valve is provided at the end of the upper tubular member, and the spring characteristics can be changed by supplying and discharging gas to and from the second chamber.

  However, the conventional rear shock absorber cannot adjust the maximum volume and the minimum volume of the air chamber functioning as a gas spring like the first and second chambers. Therefore, the spring characteristics of the gas spring can only be changed by supplying and discharging gas to the air chamber, and the degree of freedom in changing the spring characteristics is low.

  Then, this invention makes it a subject to provide the buffer which can improve the change freedom degree of a spring characteristic.

  In the invention according to claim 1, which solves the above-mentioned problem, the first chamber member and the second chamber member that are connected to the rod that moves in the axial direction in the cylinder and is arranged inside and outside double, and the first chamber member An outer peripheral space formed between the first chamber member and the second chamber member is provided between the first chamber member and the second chamber member. A movable partition wall, an inner circumferential space formed between the first chamber member and the rod, and the rod side chamber are configured to expand and contract by relative movement of the cylinder and the rod. Room. For this reason, if the position of the movable partition is changed, the maximum volume and the minimum volume of the air chamber can be changed. Further, when combined with a gas supply / discharge valve, that is, an air valve or the like, not only the supply / discharge of gas to / from the air chamber but also the maximum volume and the minimum volume of the air chamber can be changed.

  According to a second aspect of the present invention for solving the above-mentioned problem, a first chamber member and a second chamber member which are connected to a rod moving in the axial direction in a cylinder and arranged in an inner and outer double manner, and the first chamber member A sealing member that is connected to the outer periphery of the cylinder and is attached to the cylinder, is in sliding contact with the inner periphery of the first chamber member, and is formed between the sealing member and the cylinder outer space. A piston that divides an inner circumferential space formed between one chamber member and the rod, and a mounting position between the first chamber member and the second chamber member that can be changed in the axial direction. A movable partition that divides an outer peripheral space formed between the first chamber member and the second chamber member into a rod side chamber and a cylinder side chamber; the cylinder outer space; and the cylinder side chamber. And an air chamber to be made. For this reason, if the position of the movable partition is changed, the maximum volume and the minimum volume of the air chamber can be changed. Further, when combined with a gas supply / discharge valve, that is, an air valve or the like, not only the supply / discharge of gas to / from the air chamber but also the maximum volume and the minimum volume of the air chamber can be changed.

  According to a third aspect of the invention, there is provided the structure of the first aspect, a sealing member connected to the first chamber member and slidably in contact with the outer periphery of the cylinder, and the first member attached to the cylinder and the first member. A piston that slidably contacts the inner periphery of the chamber member and that is formed between the sealing member and the cylinder outer space and the inner peripheral space, the cylinder outer space, and the cylinder side chamber are configured. A second air chamber. For this reason, if the position of the movable partition is changed, both the maximum volume and the minimum volume of the air chamber and the maximum volume and the minimum volume of the second air chamber can be changed simultaneously.

  According to a fourth aspect of the present invention, the structure according to any one of the first to third aspects of the present invention is provided, and three or more annular grooves along the circumferential direction are provided on the outer periphery of the first chamber member in the axial direction. It is provided side by side. And the said movable partition is pinched | interposed and positioned by a pair of snap ring which fits in any two of the said annular grooves. Since it is easy to form an annular groove at any position in the axial direction on the outer periphery of the first chamber member, the degree of freedom in selecting the position where the movable partition wall is provided is improved. Moreover, since the process which forms an annular groove is easy and can use a general purpose snap ring, even if it provides a movable partition so that the position of an axial direction can be changed, cost can be reduced.

  According to a fifth aspect of the present invention, an annular insertion comprising the configuration according to the second or third aspect and wherein the sealing member is inserted between the first chamber member and the second chamber member. And a cylindrical portion that is continuous with the insertion portion, and a sliding portion that extends from the end of the cylindrical portion on the side opposite to the first chamber member to the inner peripheral side and is in sliding contact with the outer periphery of the cylinder. . Since the cylindrical portion is thick for the purpose of supporting the sliding portion, a gas supply / discharge valve can be attached using the cylindrical portion.

  According to the shock absorber of the present invention, the degree of freedom in changing the spring characteristics can be improved.

It is the side view which simplified and showed the vehicle carrying the rear cushion unit which is a buffer which concerns on 1st embodiment of this invention. It is the longitudinal section showing concretely the rear cushion unit which is a buffer concerning a 1st embodiment of the present invention. (A) is a left half sectional view showing the piston part of FIG. 2 in an enlarged manner, and (b) is a right half sectional view showing a state in which the rear cushion unit is slightly contracted from (a).

  Embodiments of the present invention will be described below with reference to the drawings. The same reference numerals used throughout the several drawings indicate the same parts.

  As shown in FIG. 1, a shock absorber according to an embodiment of the present invention is a rear cushion unit R mounted on a motorcycle, and swings at a frame F that is a skeleton of the vehicle body and a rear portion of the frame F. It is connected freely and is interposed between the swing arm A that supports the rear wheel W. Although FIG. 1 schematically shows a state in which the rear cushion unit R is mounted on a motorcycle, the rear cushion unit R according to the present invention may be mounted on a tricycle or other saddle riding type vehicle. Further, the rear cushion unit R may be attached to any position by any method as long as the rear cushion unit R can mitigate the impact caused by the road surface unevenness inputted to the rear wheel W.

  As shown in FIG. 2, the rear cushion unit R includes a shock absorber body D having a cylinder 1 and a rod 2 that enters and exits the cylinder 1, and is connected to the rod 2. The cylinder member T which forms the chamber G1 and forms the second air chamber G2 on the outer periphery of the cylinder 2 and a pair of brackets B1 and B2 provided at one end and the other end of the shock absorber body D are provided. The upper bracket B1 in FIG. 2 is screwed into the upper end portion in FIG. 2 of the rod 2 protruding from the cylinder 1, and is connected to the swing arm A. The other lower bracket B2 in FIG. 2 is provided at the bottom of the cylinder 1 and connected to the frame F. When an impact due to road surface unevenness is input to the rear wheel W, the rod 2 enters and exits the cylinder 1 and the rear cushion unit R expands and contracts.

  In the present embodiment, the rod 2 is connected to the wheel side and the cylinder 1 is connected to the vehicle body side so that the rear cushion unit R is an inverted type. In the mounted state, the rod 2 of the rear cushion unit R is used. Extends below the cylinder 1. However, the rod 2 may be connected to the vehicle body side, and the cylinder 1 may be connected to the wheel side so that the rear cushion unit R becomes an upright type.

  The shock absorber main body D includes the cylinder 1 and the rod 2 described above, an annular rod guide 10 that is provided at the upper end of the cylinder 1 in FIG. A piston 20 that is movably inserted and is attached to the lower end of the rod 2 in FIG. 2, a tank 3 that is provided side by side with the cylinder 1 outside the cylinder 1, and a base valve that partitions the cylinder 1 and the tank 3. 11 and a free piston 30 slidably inserted into the tank 3.

  The cylinder 1 has a bottomed cylindrical shape. In the cylinder 1, an extension side chamber L1 on the rod 2 side and a pressure side chamber L2 on the piston 20 side defined by the piston 20 are formed. Further, a liquid chamber L3 and a gas chamber G3 defined by a free piston 30 are formed in the tank 3, and the pressure side chamber L2 and the liquid chamber L3 are defined by a base valve 11. The extension side chamber L1, the pressure side chamber L2, and the liquid chamber L3 are filled with hydraulic oil, and the gas chamber G3 is filled with air. Although not shown, the tank 3 is provided with an air valve for supplying and discharging air to and from the gas chamber G3 so that the pressure in the gas chamber G3 can be adjusted.

  As shown in FIG. 3, the rod guide 10 provided at the upper end portion in FIG. 2 of the cylinder 1 includes a bolt portion 10a screwed into the cylinder 1, and a cylinder having an outer diameter larger than the outer diameter of the bolt portion 10a. 1 has a flange portion 10b projecting outside. An O-ring 12 is provided on the outer periphery of the flange portion 10b so as to be in sliding contact with the inner peripheral surface of the first chamber member 40 in the cylindrical member T and to block between the rod guide 10 and the first chamber member 40. Therefore, in the present embodiment, the flange portion 10b can partition the inner circumferential space k2 that can be formed on the outer periphery of the rod 2 and the outer cylinder space k3 that can be formed on the outer periphery of the cylinder 1. In other words, in the present embodiment, the space partition piston (air piston) is the flange portion 10b that is seamlessly integrated with the rod guide 10 and is a part of the rod guide 10, so that the rear cushion unit R The number of parts and assembly man-hours can be reduced. However, the air piston does not move in the axial direction with respect to the cylinder 1 and only needs to be able to partition the first air chamber G1 and the second air chamber G2. Therefore, the air piston can be integrated with the cylinder 1 seamlessly, or the air piston can be formed separately from the rod guide 10 and the cylinder 1 and connected to the cylinder 1 or the rod guide 10 by fitting, welding, bonding, or the like. May be.

  An O-ring 13 and a U-packing 14 that close the outer periphery of the rod 2 are provided on the inner periphery of the rod guide 10. The O-ring 13 prevents the air in the first air chamber G1 from entering the cylinder 1, and the U-packing 14 prevents the hydraulic oil in the cylinder 1 from flowing out to the first air chamber G1 side. Yes. An annular bush 15 is provided between the O-ring 13 and the U-packing 14 so that the rod 2 can slide smoothly with respect to the rod guide 10. Further, O-rings 17 and 18 are provided on the outer periphery of the rod guide 10 to block the space between the cylinder 1 and the rod guide 10 and to cover the outer periphery of the cylinder 1 with the cylindrical sliding pipe 16 and the rod guide. 10 is closed.

  The piston 20 that divides the inside of the cylinder 1 into an extension side chamber L1 and a pressure side chamber L2 is formed with an extension side channel 20a and a pressure side channel 20b that communicate the extension side chamber L1 and the pressure side chamber L2. An extension side leaf valve V1 that opens and closes the outlet of the extension side flow path 20a is stacked on the lower end of the piston 20 in FIG. A pressure-side leaf valve V2 that opens and closes the outlet of the pressure-side channel 20b is stacked on the upper end of the other piston 20 in FIG. The extension-side leaf valve V1 and the compression-side leaf valve V2 are both annular plates, and are fixed to the tip of the rod 2 together with the piston 20 by a piston nut 22, and are allowed to bend on the outer peripheral side. Therefore, the expansion-side leaf valve V1 can open the expansion-side flow path 20a when bent under the pressure of the expansion-side chamber L1, and the compression-side leaf valve V2 opens the compression-side flow path 20b when bent under the pressure of the compression side chamber L2. it can.

  Further, the base valve 11 that divides the inside of the cylinder 1 and the inside of the tank 3 includes a suction passage 11a and a discharge passage 11b that communicate the pressure side chamber L2 and the liquid chamber L3 as indicated by a hydraulic symbol in FIG. Prepare. The suction flow path 11a is provided with a check valve V3, which allows only the flow of hydraulic oil from the liquid chamber L3 to the pressure side chamber L2 through the suction flow path 11a. The other discharge channel 11b is provided with a damping valve V4, which allows only the flow of hydraulic oil from the pressure side chamber L2 to the liquid chamber L3 through the discharge channel 11b and provides resistance to the flow.

  According to the above configuration, when the rear cushion unit R extends, the rod 2 moves upward in FIG. 2 with respect to the cylinder 1, and the piston 20 moves in the cylinder 1 upward in FIG. Is compressed, and the compression side chamber L2 expands.

  Then, the pressure in the expansion side chamber L1 to be compressed rises, and the hydraulic oil in the expansion side chamber L1 pushes open the expansion side leaf valve V1, passes through the expansion side flow path 20a, and moves to the compression side chamber L2. In the cylinder 1, there is insufficient hydraulic oil for the retracted rod volume, but the check valve V3 is opened, and hydraulic oil commensurate with the shortage is supplied from the liquid chamber L3 to the pressure side chamber L2 through the suction passage 11a. The Since resistance is given by the extension side leaf valve V1 with respect to the flow of the hydraulic fluid which goes to the compression side chamber L2 from the extension side chamber L1, the pressure of the extension side chamber L1 rises. On the other hand, the pressure side chamber L2 is supplied with hydraulic oil from the liquid chamber L3, so that it becomes substantially equal to the pressure in the tank 3. Therefore, a differential pressure is generated in the pressures of the extension side chamber L1 and the pressure side chamber L2, and this differential pressure acts on the piston 20 so that the shock absorber body D exhibits a damping force that hinders the extension operation of the rear cushion unit R.

  On the contrary, when the rear cushion unit R contracts, the rod 2 moves downward in FIG. 2 with respect to the cylinder 1, the piston 20 moves downward in FIG. 2 in the cylinder 1, and the compression side chamber L2 is compressed. The extension side chamber L1 expands.

  Then, the pressure in the pressure side chamber L2 to be compressed rises, and the hydraulic oil in the pressure side chamber L2 pushes open the pressure side leaf valve V2, passes through the pressure side flow path 20b, and moves to the extension side chamber L1. In the cylinder 1, the hydraulic oil for the volume of the rod that has entered becomes excessive, but the excess hydraulic oil pushes the damping valve V4 open, passes through the discharge passage 11b, and is discharged from the pressure side chamber L2 to the liquid chamber L3. . In this way, resistance is given by the pressure side leaf valve V2 and the damping valve V4 to the flow of hydraulic fluid from the pressure side chamber L2 toward the expansion side chamber L1 and the liquid chamber L3, and thus the pressure in the pressure side chamber L2 increases. On the other hand, the pressure in the expansion side chamber L1 which expands falls. Therefore, a differential pressure is generated between the pressure side chamber L2 and the extension side chamber L1, and this differential pressure acts on the piston 20, so that the shock absorber body D exhibits a damping force that prevents the rear cushion unit R from contracting.

  The structure of the shock absorber body D is not limited to the above, and can be changed as appropriate. For example, in the present embodiment, hydraulic oil is used as the fluid for generating the damping force, but other fluids may be used. Further, the gas sealed in the gas chamber G3 can be changed as appropriate. Further, the gas valve G3 may be pressurized and the base valve 11 may be discarded. Alternatively, the cylinder 1 and the tank 3 may be connected and integrated in the axial direction, and the tank 3 that is separate from the cylinder 1 as in the present embodiment may be discarded. Further, although the liquid chamber L3 and the gas chamber G3 are partitioned by the free piston 30, a bladder, a bellows, or the like may be used for the partition. Alternatively, the cylinder 1 may be doubled inside and outside, the liquid chamber L3 and the gas chamber G3 may be provided between them, and the shock absorber body D may be a double cylinder type. Alternatively, the rod 2 may be penetrated through both the extension side chamber L1 and the compression side chamber L2 to form a double rod type.

  Subsequently, as shown in FIG. 2, the cylindrical member T that forms the first air chamber G1 and the second air chamber G2 on the outer periphery of the shock absorber body D has a cylindrical first chamber member 40 and a second chamber member 41. And a double cylindrical portion 4 that is double inside and outside, a chamber holder 5 that closes the upper opening in FIG. 2 of the double cylindrical portion 4, and a sealing member that closes the lower opening in FIG. 6. The chamber holder 5 includes an annular top portion 5 a having a hole (not shown) through which the rod 2 can be inserted, and extends downward from the outer periphery of the top portion 5 a in FIG. 2 to form a first chamber member 40 and a second chamber member 41. And an annular insertion portion 5b inserted therebetween.

  Further, as shown in FIG. 3, the sealing member 6 includes an annular insertion portion 6a inserted between the first chamber member 40 and the second chamber member 41, and a lower portion in FIG. 3 from the insertion portion 6a. An extending cylinder portion 6b and an annular reduced diameter portion 6c projecting inward from the lower end in FIG. 3 of the cylinder portion 6b are provided. On the inner periphery of the reduced diameter portion 6 c, annular seals 42 and 43 are provided that are in sliding contact with the outer peripheral surface of the sliding pipe 16 and block between the sliding pipe 16 and the sealing member 6. That is, in the present embodiment, the reduced diameter portion 6 c functions as a sliding portion that is in sliding contact with the outer periphery of the cylinder 1 via the sliding pipe 16.

  As shown in FIGS. 2 and 3, the second chamber member 41 constituting the double tube portion 4 has its upper end portion in FIG. 2 screwed to the outer periphery of the insertion portion 5 b in the chamber holder 5, and the lower end portion in FIG. The sealing member 6 is screwed onto the outer periphery of the insertion portion 6a (FIG. 3). The other first chamber member 40 has an upper end portion in FIG. 2 inserted into the insertion portion 5b and a lower end portion in FIG. 2 inserted into the insertion portion 6a (FIG. 3). It is sandwiched between the top portion 5a and a step formed at the end of the insertion portion 6a of the sealing member 6. For this reason, the 1st chamber member 40, the 2nd chamber member 41, the chamber holder 5, and the sealing member 6 are integrated as the cylinder member T. FIG. Moreover, since the top part 5a of the chamber holder 5 is fitted to the outer periphery of the lower end part in FIG. 2 of the bracket B1, the cylindrical member T can move in the axial direction with respect to the cylinder 1 together with the rod 2.

  An annular movable partition wall 44 that can adjust the axial position is provided between the first chamber member 40 and the second chamber member 41. An outer peripheral space k1 formed between the first chamber member 40 and the second chamber member 41 by the movable partition 44 is partitioned into an upper rod side chamber k10 in FIG. 2 and a lower cylinder side chamber k11 in FIG. As shown in FIG. 3, an O-ring 45 that closes the space between the movable partition wall 44 and the second chamber member 41 is provided on the outer periphery of the movable partition wall 44. An O-ring 46 that closes the space between the one chamber member 40 is provided.

  Further, as shown in FIG. 2, a groove 5 c that forms a gap between the inner surface of the chamber holder 5 and the first chamber member 40 is provided between the rod 2 and the first chamber member 40. The inner circumferential space k2 that can be formed communicates with the rod side chamber k10 through the gap. Then, air is sealed in the inner circumferential space k2 and the rod side chamber k10, and the first air chamber G1 is configured by a space obtained by combining the inner circumferential space k2 and the rod side chamber k10.

  Further, as shown in FIG. 3, on the outer periphery of the sliding pipe 16 surrounding the cylinder 1, the flange portion 10 b of the rod guide 10, the first chamber member 40, the cylindrical portion 6 b of the sealing member 6, and the reduced diameter. A cylinder outer space k3 surrounded by the portion 6c is formed. A groove 6d that forms a gap with the first chamber member 40 is provided on the inner surface of the sealing member 6, and the cylinder outside space k3 and the cylinder side chamber k11 communicate with each other through the gap. And the 2nd air chamber G2 is comprised by the space which match | combined the cylinder outside space k3 and the cylinder side chamber k11.

  In the present embodiment, the outer peripheral space k1 is communicated with the inner peripheral space k2 and the outer cylinder space k3 by utilizing the gap formed between the first chamber member 40 by the grooves 5c and 6d. The communication method is not limited to the above, and can be changed as appropriate.

  As shown in FIGS. 2 and 3, between the top portion 5 a and the rod 2 in the chamber holder 5, between the insertion portion 5 b and the second chamber member 41, and between the insertion portion 6 a and the second chamber member 41 in the sealing member 6. Are closed by O-rings (not shown). Further, as described above, the space between the rod 2 and the rod guide 10 and the space between the rod guide 10 and the sliding pipe 16 are closed by the O-rings 13 and 18. Is closed by O-rings 45 and 46. Further, the space between the first chamber member 40 and the flange portion 10b is closed by the O-ring 12 that is in sliding contact with the inner peripheral surface of the first chamber member 40, and the space between the sliding pipe 16 and the reduced diameter portion 6c is slid. The moving pipe 16 is closed by seals 42 and 43 that are in sliding contact with the outer peripheral surface. Therefore, the air in the first air chamber G1 and the second air chamber G2 does not leak into the outside air or the cylinder 1, and the first air chamber G1 and the second air chamber G2 can be divided into airtight spaces, respectively. . Thus, in the present embodiment, since both the first air chamber G1 and the second air chamber G2 extend to the outer peripheral space k1 formed on the outer periphery of the first chamber member 40, the first air chamber The volume of G1 and the 2nd air chamber G2 can be enlarged.

  According to the above configuration, the first air chamber G1 is expanded in the direction in which the volume of the first air chamber G1 is expanded by the elastic force of the air enclosed therein, that is, in the direction in which the rear cushion unit R is extended. It functions as an energizing main spring S1. The other second air chamber G2 is biased in the direction of expanding the volume of the second air chamber G2, that is, in the direction of contracting the rear cushion unit R, by the elastic force of the air enclosed therein. Function as.

  When the rear cushion unit R extends, the cylinder member T moves upward in FIG. 2 with respect to the cylinder 1 together with the rod 2, so that the volume of the first air chamber G1 is increased and the second air chamber G2 is expanded. The volume is reduced. For this reason, the elastic force of the main spring S1 decreases and the elastic force of the balance spring S2 increases. As a result of this extension operation, the elastic force of the rear cushion unit R as a whole decreases. On the contrary, when the rear cushion unit R contracts, the cylinder member T moves together with the rod 2 downward in FIG. 2 with respect to the cylinder 1, so that the volume of the first air chamber G1 is reduced and the second air chamber G2 is reduced. Is enlarged (FIG. 3B). For this reason, the elastic force of the main spring S1 increases and the elastic force of the balance spring S2 decreases. And by this contraction operation, the elastic force of the rear cushion unit R as a whole increases. Thus, the rear cushion unit R elastically supports the vehicle body by the elastic force of the air springs in the first air chamber G1 and the second air chamber G2, and exhibits an elastic force corresponding to the stroke amount of the rear cushion unit R.

  Further, in the present embodiment, the rear cushion unit R includes a main spring S1 and a balance spring S2 whose urging directions are reversed. Therefore, the spring characteristic of the entire rear cushion unit R is a combination of the spring characteristic of the main spring S1 and the spring characteristic of the balance spring S2, thereby improving the riding comfort of the vehicle. More specifically, although the vehicle body can be elastically supported only by the main spring S1, the spring characteristic of the rear cushion unit as a whole becomes the characteristic of only the main spring S1, and becomes a non-linear characteristic peculiar to the air spring. . Therefore, if the spring characteristics of the rear cushion unit are set in accordance with the desired characteristics in the second half of the stroke, the elastic force in the first half of the stroke, particularly in the vicinity of the maximum extension, may be excessive and the riding comfort may be deteriorated. Therefore, as in the present embodiment, when the balance spring S2 is added, the rear cushion unit R can be helped to contract near the maximum extension position, and the riding comfort of the vehicle can be improved. In particular, the urging force acting in the extension direction by the main spring S1 when the rear cushion unit R is at its maximum extension is canceled by the balance spring S2, and the combined characteristics of the main spring S1 and the balance spring S2 are proportional to the stroke amount. It is preferable to approximate the characteristics of the coil spring.

  The spring characteristic of the rear cushion unit R is that air is supplied to and discharged from the first air chamber G1, air is supplied to and discharged from the second air chamber G2, and the volumes of the first air chamber G1 and the second air chamber G2 are changed. Can be changed. Specifically, as shown in FIG. 2, a first air passage 7 communicating with the first air chamber G1 is formed from the side of the bracket B1 to the side of the rod 2. An air valve 70 is provided at the outside air side end of the first air passage 7, and air can be supplied to and discharged from the first air chamber G <b> 1 via the air valve 70. Since the bracket B1 to which the air valve 70 is attached is a part used to attach the rear cushion unit R to the vehicle, the air valve 70 is difficult to hide by the frame F or a peripheral part of the prime mover held by the frame F. Therefore, even when the rear cushion unit R is attached to the vehicle, the air valve 70 can be easily accessed and cannot be made inaccessible. Therefore, it is possible to prevent the pressure adjustment in the first air chamber G1 using the air valve 70 from being disabled. If air can be supplied to and discharged from the first air chamber G1, the position where the first air passage 7 is provided and the position where the air valve 70 is provided can be changed as appropriate.

  Further, the first air chamber G1 side opening of the first air passage 7 faces the inner peripheral surface of the cylindrical bump cushion 9 attached to the chamber holder 5. The bump cushion 9 is a rubber member having elasticity. The bump cushion 9 abuts against the rod guide 10 when the rear cushion unit R is most compressed and elastically deforms to relieve the impact during the maximum compression. Further, the bump cushion 9 has an inner diameter gradually reduced downward in FIG. 2, and a reduced diameter portion 9 a that is a lower end portion in FIG. 2 is in contact with the outer periphery of the rod 2. The upper end portion in FIG. 2 of the other bump cushion 9 is fitted into an annular groove 6 d formed in the top portion 5 a of the chamber holder 5.

  According to the above configuration, the air that enters and exits the first air chamber G1 through the first air passage 7 passes through the gap between the bump cushion 9 and the chamber holder 5, or pushes and expands the reduced diameter portion 9a. It passes through a gap on the outer periphery. Since these gaps are narrow, it is possible to prevent a large amount of air in the first air chamber G1 from being discharged in a short time. The bump cushion 9 may be a coil spring, and the position where the bump cushion 9 is provided can be changed as appropriate. Further, the bump cushion 9 may be eliminated if consideration is given so that the riding comfort is not significantly deteriorated by the impact of the rear cushion unit R when it is most compressed.

  Subsequently, the sealing member 6 is formed with a second air passage 8 that obliquely penetrates the cylindrical portion 6b and communicates with the second air chamber G2. The second air passage 8 is provided with an air valve 80, through which air can be supplied to and discharged from the second air chamber G2. The sealing member 6 is a member having high strength against bending for the purpose of supporting the reduced diameter portion 6c functioning as a sliding portion, and is thick. Therefore, the sealing member 6 is suitable for mounting the air valve 80. However, if air can be supplied to and discharged from the second air chamber G2, the configuration of the sealing member 6, the position where the second air passage 8 is provided, and the position where the air valve 80 is provided can be changed as appropriate.

  Subsequently, as shown in FIG. 3, on the outer periphery of the first chamber member 40, annular grooves along the circumferential direction are formed side by side in the axial direction (annular grooves 40a, 40b, 40c, 40d, 40e). The movable partition wall 44 is sandwiched between a pair of snap rings 47 and 48 that fit into two annular grooves 40b and 40c adjacent in the vertical direction in FIG. Both of these snap rings 47 and 48 are arc-shaped (C-shaped) rings having a cut, and when the diameter is expanded to widen the cut, the snap rings 47 and 48 try to return to the original shape due to their own elasticity. The inner diameters of the snap rings 47 and 48 in the natural state are smaller than the outer diameters of the first chamber member 40 other than the annular grooves 40a to 40e. Therefore, when the snap rings 47 and 48 are fitted into any of the annular grooves 40a to 40e, the axial movement with respect to the first chamber member 40 is restricted.

  Further, when the snap rings 47 and 48 are attached to the first chamber member 40, the outer diameters of the snap rings 47 and 48 are larger than the inner diameter of the movable partition wall 44. Therefore, when the snap rings 47 and 48 are fitted on both sides of the movable partition wall 44 in the axial direction, the movement of the movable partition wall 44 in the axial direction with respect to the first chamber member 40 is restricted. As shown in FIG. 3, when the movable partition 44 and the snap rings 47 and 48 on both upper and lower sides are in contact with each other, the generation of abnormal noise when the movable partition 44 and the snap rings 47 and 48 are in contact is prevented. it can. However, the distance between the upper and lower snap rings 47 and 48 may be wider than the wall thickness of the movable partition wall 44, and the movable partition wall 44 may move somewhat in the axial direction. That is, the state in which the movable partition wall 44 is positioned includes a state in which the movement limit of the movable partition wall 44 on both sides in the axial direction is determined within a narrow range, and includes only a state in which the movable partition wall 44 cannot move in the axial direction at all in the outer circumferential space k1. It is not limited.

  Further, in the present embodiment, five annular grooves 40a to 40e are provided, so that any two annular grooves are selected from these five annular grooves 40a to 40e, and the snap rings 47 and 48 can be attached. Since the position of the movable partition 44 in the outer circumferential space k1 is determined by the pair of snap rings 47 and 48, the axial position of the movable partition 44 can be changed by changing the annular grooves 40a to 40e to be selected. FIG. 3 shows a state in which the movable partition 44 is positioned by a pair of snap rings 47 and 48 fitted into the second and third annular grooves 40b and 40c from the top. However, for example, the snap rings 47 and 48 may be fitted into the first and second annular grooves 40a and 40b from the top in FIG. 3, and the movable partition wall 44 may be positioned therebetween. When the change is made in this way, the maximum volume and the minimum volume of the first air chamber G1 and the second air chamber G2 after the change are compared with those before the change. The maximum volume and the minimum volume of the second air chamber G2 are expanded.

  Thus, in the present embodiment, not only the supply / discharge of air to / from the first air chamber G1 and the second air chamber G2, but also the maximum volume and the minimum volume of the first air chamber G1 and the second air chamber G2. Since it can be changed, the degree of freedom in changing the spring characteristics of the rear cushion unit R can be improved. In the present embodiment, when the position of the movable partition 44 is changed to increase the volume of the first air chamber G1, the volume of the second air chamber G2 is decreased, and conversely, the volume of the first air chamber G1 is decreased. When the volume is decreased, the volume of the second air chamber G2 is increased. Further, as described above, the first air chamber G1 and the second air chamber G2 extend to the outer peripheral space k1 and have a large volume, so that one volume of the first air chamber G1 and the second air chamber G2 is optimized. When set, the other volume may become excessive. Therefore, if another movable partition is added in addition to the movable partition 44, the movable partition 44 is replaced with a movable partition having a different axial length, or oil is put into the excessive air chamber, The volume of both the first air chamber G1 and the second air chamber G2 can be set optimally.

  Further, in the present embodiment, the first air chamber G1 extends to the outer peripheral space k1, and the volume of the first air chamber G1 is increased as compared with the case where the first air chamber G1 includes only the inner peripheral space k2. it can. For example, the axial length of the first chamber member 40 may be increased to increase the volume of the first air chamber G1, but in this case, the rear cushion unit R is bulky in the axial direction, and the rear cushion unit The mountability of R may be deteriorated. For this reason, as described above, it is preferable to expand the first air chamber G1 to the outer peripheral side of the first chamber member 40 to ensure the volume of the first air chamber G1.

  Further, in the present embodiment, the second air chamber G2 extends to the outer peripheral space k1, and the volume of the second air chamber G2 can be increased as compared with the case where the second air chamber G2 consists only of the cylinder outer space k3. . For example, the axial length of the cylindrical portion 6b of the sealing member 6 may be increased to increase the volume of the second air chamber G2, but in this case, the stroke length of the rear cushion unit R cannot be secured. There is a fear. More specifically, when the side-by-side tank 3 and the end of the cylinder 1 (the lower end in FIG. 2) are connected as in the present embodiment, the connecting portion lowers the sealing member 6 in FIG. Movement is restricted. Therefore, if the cylindrical portion 6b is extended to increase the axial length of the sealing member 6, the distance between the sealing member 6 and the connecting portion is shortened, so that the stroke length may be shortened. For this reason, as above-mentioned, it is preferable to expand the 2nd air chamber G2 to the outer peripheral side of the 1st chamber member 40, and to ensure the volume of the 2nd air chamber G2.

  In the present embodiment, air is sealed in the first air chamber G1 and the second air chamber G2, respectively, but the first air chamber G1 or the second air chamber G2 uses the elastic force of gas. If the gas spring (pneumatic spring) can be configured, the gas to be used can be changed as appropriate. The gas may be the same as or different from the gas in the gas chamber G3. In the present embodiment, since the main spring S1 and the balance spring S2 are both air springs, the rear cushion unit R can be reduced in weight, but the balance spring S2 may be replaced with a coil spring.

  In the present embodiment, a sliding pipe 16 is provided on the outer periphery of the cylinder 1 so that the sealing member 6 is not directly brought into sliding contact with the cylinder 1, and the sealing member 6 is interposed via the sliding pipe 16. In contact with the outer periphery of the cylinder 1. Therefore, only the inner peripheral surface of the cylinder 1 needs to be a sliding smooth surface, and the outer peripheral surface can be left as a rough surface, so that the machining of the cylinder 1 can be facilitated. However, the outer peripheral surface of the cylinder 1 may be a smooth surface, and the sliding portion may be in direct sliding contact with the outer periphery of the cylinder 1.

  Hereinafter, functions and effects of the rear cushion unit R according to the present embodiment will be described.

  In the present embodiment, the sealing member 6 includes an annular insertion portion 6a inserted between the first chamber member 40 and the second chamber member 41, a cylindrical portion 6b connected to the insertion portion 6a, and a cylindrical portion 6b. 3 has a reduced diameter portion (sliding portion) 6c extending from the lower end portion (end portion on the side opposite to the first chamber member) to the inner peripheral side and slidably contacting the outer periphery of the cylinder 1. Since the cylindrical portion 6b is thick for the purpose of supporting the reduced diameter portion (sliding portion) 6c, air (gas) is supplied to and discharged from the second air chamber (second air chamber) G2 to the cylindrical portion 6b. Air valve can be installed.

  However, when it is not necessary to adjust the pressure in the second air chamber (second air chamber) G2, the pressure in the second air chamber (second air chamber) G2 is changed only by changing the volume, or the balance is adjusted. When the spring S2 is a coil spring and the second air chamber (second air chamber) G2 is not allowed to function as an air spring, the cylindrical portion 6b may be eliminated and the first chamber member 40 may be extended. The configuration of the member 6 can be changed as appropriate.

  Moreover, in this Embodiment, the annular groove 40a-40e along the circumferential direction is provided in the outer periphery of the 1st chamber member 40 along with the 3 or more row | line | column in the axial direction. The movable partition wall 44 is positioned by being sandwiched between a pair of snap rings 47 and 48 that are fitted into any two of the annular grooves 40a to 40e. Since the annular grooves 40a to 40e are easily formed on the outer periphery of the first chamber member 40 at any position in the axial direction, the degree of freedom in selecting the position where the movable partition wall 44 is provided is improved. Moreover, since the process which forms the annular grooves 40a-40e is easy and can use the general purpose snap rings 47 and 48, even if it provides the movable partition 44 so that the position of an axial direction can be changed, cost can be reduced.

  In the present embodiment, five annular grooves 40a to 40e are provided, but the axial position of the movable partition wall 44 can be changed as long as the number is three or more. The method for changing the position of the movable partition wall 44 in the axial direction is not limited to the above. For example, the position of the movable partition wall 44 in the axial direction is changed by a method other than the annular grooves 40a to 40e and the snap rings 47 and 48. May be.

  In the present embodiment, the rear cushion unit (buffer) R is connected to the first chamber 40 and is in sliding contact with the outer periphery of the cylinder 1, and the first chamber member 40 is attached to the cylinder 1. A flange portion (piston) 10b that slidably contacts the inner periphery of the cylinder and is formed between the sealing member 6 and a cylinder outer space k3 and an inner peripheral space k2, and a cylinder outer space k3 and a cylinder side chamber k11. A second air chamber (second air chamber) G2. Further, the inner circumferential space k2 constitutes a first air chamber (air chamber) G1 together with the rod side chamber k10, and the rod side chamber k10 and the cylinder side chamber k11 are partitioned by the movable partition wall 44. Therefore, when the axial position of the movable partition 44 is changed, both the maximum volume and the minimum volume of the first air chamber (air chamber) G1 and the maximum volume and the minimum volume of the second air chamber (second air chamber) G2 are both. Can be changed at the same time.

  However, when there is no need to change the volume of the second air chamber (second air chamber) G2, the volume change of the second air chamber (second air chamber) G2 is the amount of oil stored in the cylinder outer space k3. When changing, or when the second air chamber (second air chamber) G2 does not function as an air spring, such as when the balance spring S2 is a coil spring, the communication between the cylinder side chamber k11 and the cylinder outer space k3 is cut off. However, only the volume of the first air chamber (air chamber) G1 may be changed by the movable partition wall 44. Further, when the volume change of the first air chamber (air chamber) G1 is not necessary, or when the volume change of the first air chamber (air chamber) G1 is changed by the amount of oil stored in the inner circumferential space k2. May block the communication between the rod side chamber k10 and the inner circumferential space k2 and change only the volume of the second air chamber (second air chamber) G2 with the movable partition wall 44.

  In the present embodiment, the rear cushion unit R includes a cylinder 1, a rod 2 that is movably inserted into the cylinder 1, a cylindrical first chamber member 40 that is connected to the rod 2, and a rod 2. A cylindrical second chamber member 41 connected to the outer periphery of the first chamber member 40, a sealing member 6 connected to the first chamber 40 and slidably contacting the outer periphery of the cylinder 1, and the cylinder 1. A cylinder outer space k3 formed between the sealing member 6 in sliding contact with the inner periphery of the first chamber member 40 and an inner peripheral space k2 formed between the first chamber member 40 and the rod 2. The first chamber member 40 and the second chamber member 4 are provided so that the mounting position can be changed in the axial direction between the partitioning flange portion (piston) 10b and the first chamber member 40 and the second chamber member 41. A second air chamber (air chamber) configured to include a movable partition wall 44 that divides the outer peripheral space k1 formed between the rod-side chamber k10 and the cylinder-side chamber k11, a cylinder outer space k3, and the cylinder-side chamber k11. ) G2.

  For this reason, when the movable partition 44 is moved in the axial direction, the maximum volume and the minimum volume of the second air chamber (air chamber) G2 constituting the air spring (gas spring) can be changed. Furthermore, when combined with a gas supply / discharge valve such as the air valve 80 as in the present embodiment, not only the supply / discharge of air (gas) to / from the second air chamber (air chamber) G2, but also the second air The maximum volume and the minimum volume of the chamber (air chamber) G2 can be changed. Therefore, the degree of freedom in changing the spring characteristics of the rear cushion unit R can be improved. In addition, when the volume of the second air chamber (air chamber) G2 is reduced, it can be realized by providing a partition wall or putting oil in the cylinder outer space k3. However, when expanding the volume of the second air chamber (air chamber) G2, if the cylinder outer space k3 is extended downward in FIGS. 2 and 3, the stroke length may not be secured. Therefore, it is preferable to extend the second air chamber (air chamber) G2 to the outer peripheral space k1 to secure the volume of the second air chamber (air chamber) G2.

  In the present embodiment, the rear cushion unit R includes the cylinder 1, the rod 2 that is movably inserted into the cylinder 1, the cylindrical first chamber member 40 that is connected to the rod 2, and the rod 40. Between the first chamber member 40 and the second chamber member 41 so that the mounting position can be changed in the axial direction. A movable partition wall 44 that divides an outer peripheral space k1 formed between the first chamber member 40 and the second chamber member 41 into a rod side chamber k10 and a cylinder side chamber k11, and between the first chamber member 40 and the rod 2. And a first air chamber (air chamber) G1 which is configured to have an inner circumferential space k2 and a rod side chamber k10 which are enlarged and reduced by relative movement between the cylinder 1 and the rod 2.

  For this reason, when the movable partition wall 44 is moved in the axial direction, the maximum volume and the minimum volume of the first air chamber (air chamber) G1 constituting the air spring (gas spring) can be changed. Further, when combined with a gas supply / discharge valve such as the air valve 70 as in the present embodiment, not only the supply / discharge of air (gas) to / from the first air chamber (air chamber) G1, but also the first air The maximum volume and the minimum volume of the chamber (air chamber) G1 can be changed. Therefore, the degree of freedom in changing the spring characteristics of the rear cushion unit R can be improved. In addition, when the volume of the first air chamber (air chamber) G1 is reduced, it can be realized by putting oil into the inner circumferential space k2. However, when the volume of the first air chamber (air chamber) G1 is increased, if the inner circumferential space k2 is extended upward in FIGS. 2 and 3, the rear cushion unit R may be bulky in the axial direction and deteriorate the mounting property. There is. Therefore, it is preferable to extend the first air chamber (air chamber) G1 to the outer peripheral space k1 to secure the volume of the first air chamber (air chamber) G1.

  In the present embodiment, the first chamber member 40 and the second chamber member 41 are connected to the rod 2 via the chamber holder 5, but may be directly connected to the rod 2. The connected state includes both a case where they are directly connected and a case where they are indirectly connected, and may be either.

  The preferred embodiments of the present invention have been described above in detail, but modifications, changes and modifications can be made without departing from the scope of the claims.

G1 ... first air chamber (air chamber), G2 ... second air chamber ((second) air chamber), k1 ... outer peripheral space, k2 ... inner peripheral space, k3 ... Space outside the cylinder, k10 ... rod side chamber, k11 ... cylinder side chamber, R ... rear cushion unit (buffer), 1 ... cylinder, 2 ... rod, 6 ... sealing member, 6a ... insertion part, 6b ... cylindrical part, 6c ... reduced diameter part (sliding part), 10b ... flange part (piston), 40 ... first chamber member, 40a, 40b, 40c, 40d, 40e ... annular groove, 41 ... second chamber member, 44 ... movable partition, 47, 48 ... snap ring

Claims (5)

A cylinder,
A rod movably inserted into the cylinder;
A cylindrical first chamber member connected to the rod;
A cylindrical second chamber member connected to the rod and provided on the outer periphery of the first chamber member;
A mounting position is provided between the first chamber member and the second chamber member so that the mounting position can be changed in the axial direction, and an outer peripheral space formed between the first chamber member and the second chamber member is a rod. A movable partition partitioning into a side chamber and a cylinder side chamber;
An inner space formed between the first chamber member and the rod and the rod side chamber, and an air chamber that expands and contracts by relative movement between the cylinder and the rod. A shock absorber characterized by. A cylinder,
A rod movably inserted into the cylinder;
A cylindrical first chamber member connected to the rod;
A cylindrical second chamber member connected to the rod and provided on the outer periphery of the first chamber member;
A sealing member connected to the first chamber member and slidably contacting the outer periphery of the cylinder;
A cylinder outer space that is attached to the cylinder and is in sliding contact with the inner periphery of the first chamber member and formed between the sealing member and an inner space formed between the first chamber member and the rod. A piston that partitions the surrounding space;
A mounting position is provided between the first chamber member and the second chamber member so that the mounting position can be changed in the axial direction, and an outer peripheral space formed between the first chamber member and the second chamber member is a rod. A movable partition partitioning into a side chamber and a cylinder side chamber;
A shock absorber comprising: an air chamber configured to include the outside-cylinder space and the cylinder-side chamber. A sealing member connected to the first chamber member and slidably contacting the outer periphery of the cylinder;
A piston that is attached to the cylinder and slidably contacts the inner periphery of the first chamber member, and defines a cylinder outer space and the inner peripheral space formed between the sealing member, and
The shock absorber according to claim 1, further comprising a second air chamber configured to include the outside-cylinder space and the cylinder-side chamber. On the outer periphery of the first chamber member, three or more annular grooves are provided in the axial direction along the circumferential direction,
The shock absorber according to any one of claims 1 to 3, wherein the movable partition wall is positioned by being sandwiched between a pair of snap rings that fit into any two of the annular grooves. The sealing member includes an annular insertion portion inserted between the first chamber member and the second chamber member, a cylindrical portion connected to the insertion portion, and an anti-first chamber member side of the cylindrical portion. 4. The shock absorber according to claim 2, further comprising a sliding portion that extends from an end portion toward an inner peripheral side and is in sliding contact with the outer periphery of the cylinder.

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