JP2017115968A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorber capable of widening a regulation width of a damping force.SOLUTION: A shock absorber includes: a cylinder 4 in which an actuation liquid is enclosed; a piston 6 which is inserted so as to be slidable in a cylinder 4 and divides an inner part into two chambers; a piston rod 10 which is connected to the piston 6 and, at the same time, is extended to an external part of the cylinder 4; channels 6A, 6B along which the actuation liquid is circulated from one side chamber in the cylinder 4 toward the other side chamber by movement of the piston 6; a damping valve 8 which regulates flow of the actuation liquid produced by sliding of the piston 6 and generates a damping force; a back pressure chamber 9 which actuates an inner pressure to the damping valve 8 in a valve-closing direction; and a back pressure chamber regulation mechanism 20 which can regulate a pressure in the back pressure chamber 9 from an external part. Therein, the back pressure chamber regulation mechanism 20 is composed of a rod inner channel 10A provided in the piston rod 10 and a free piston 21 which is provided in the middle of the rod inner channel 10A and can regulate the pressure of the back pressure chamber 9.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a shock absorber suitable for use in buffering vibrations of a vehicle such as an automobile.

  A vehicle such as an automobile includes a shock absorber between a vehicle body and wheels. This shock absorber alleviates vibrations generated during travel (see, for example, Patent Document 1). In this type of conventional shock absorber, for example, a back pressure chamber is formed on the back side of a disk valve provided in a piston, and a part of the hydraulic pressure in a cylinder is introduced into the back pressure chamber, whereby the disk valve The valve opening characteristic can be made variable according to the pressure in the back pressure chamber.

JP 2005-344911 A (Patent No. 4318080)

  By the way, in the prior art, since a part of the hydraulic pressure in the cylinder is introduced into the back pressure chamber, there is a problem that it is difficult to widen the adjustment range of the damping force. An object of the present invention is to provide a shock absorber capable of widening the adjustment range of the damping force.

  In order to solve the above-described problem, a shock absorber according to the present invention includes a cylinder in which a working liquid is sealed, a piston that is slidably fitted in the cylinder, and divides the cylinder into two chambers, A piston rod connected to the piston and extending to the outside of the cylinder; a passage through which the working liquid flows from one chamber in the cylinder to the other chamber by movement of the piston; and provided in the passage A damping valve that restricts a flow of the working liquid generated by sliding of the piston to generate a damping force; a back pressure chamber that applies an internal pressure to the damping valve in a valve closing direction; A back pressure chamber adjusting mechanism capable of adjusting pressure from the outside, and the back pressure chamber adjusting mechanism is slidable in the rod inner passage provided in the piston rod and in the rod inner passage. And the back adjustable free piston the pressure in the pressure chamber is provided with inlet consists, to the rod passage, the working gas for pressure adjustment from the outside of the free piston is configured to be supplied.

  According to the present invention, the adjustment range of the damping force can be widened.

It is a longitudinal section showing a buffer by a 1st embodiment. It is a longitudinal cross-sectional view of the principal part expansion which expands and shows the back pressure chamber adjustment mechanism etc. which were provided in the piston rod in FIG. It is a longitudinal cross-sectional view which shows the shock absorber applied to the air suspension apparatus by 2nd Embodiment.

  Hereinafter, a shock absorber according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3 of the accompanying drawings. In the following description, for example, one side or one end side in the axial direction is referred to as “upper side” or “upper end side”, and the other side or other end side in the axial direction is described as “lower side” or “lower end side”. And

  Here, FIG. 1 and FIG. 2 show a first embodiment of the present invention. In FIG. 1, a bottomed cylindrical outer cylinder 1 forms an outer shell of a shock absorber. The outer cylinder 1 is closed by welding the bottom cap 2 at the lower end side, which is one end side, and is open at the upper end side, which is the other end side. In addition, a plurality of caulking portions 1 </ b> A that are bent radially inward are provided at the upper end portion of the outer cylinder 1.

  The upper end side opening of the outer cylinder 1 is closed by a lid 3. The lid 3 is formed of an annular flat plate, and is provided on the upper end (opening end) side of the outer cylinder 1 and located on the radially outer side of a piston rod 10 (rod member 11) described later. The outer diameter side of the lid 3 is fixed to the outer cylinder 1 by a caulking portion 1A in contact with a rod guide 18 described later. On the other hand, a rod seal 19 to be described later for sealing the outer peripheral side of the piston rod 10 is provided on the inner diameter side of the lid 3.

  The inner cylinder 4 constitutes a double cylinder type cylinder together with the outer cylinder 1. The inner cylinder 4 is provided coaxially in the outer cylinder 1 and has a lower end fitted and attached to an outer peripheral side of a bottom valve 5 described later. The inner cylinder 4 defines an annular reservoir chamber A between itself and the outer cylinder 1, and gas is sealed in the reservoir chamber A together with a working liquid (hereinafter referred to as oil liquid). This gas may be atmospheric pressure air or compressed nitrogen gas. The bottom valve 5 is located on the lower end side of the inner cylinder 4 and is provided between the bottom cap 2 and the inner cylinder 4.

  The piston 6 is slidably inserted into (inserted into) the inner cylinder 4. The piston 6 divides or defines the inside of the inner cylinder 4 into two chambers (that is, a bottom side oil chamber B and a rod side oil chamber C). In the piston 6, oil passages 6A and 6B are formed as a plurality of passages through which the bottom side oil chamber B and the rod side oil chamber C can communicate. In these oil passages 6A and 6B, the working liquid (oil liquid) flows from one chamber to the other chamber among the oil chambers A and B in the inner cylinder 4 (cylinder) by the movement of the piston 6. It constitutes a passage that allows this.

  On the upper side surface of the piston 6, a disk valve 7 constituting a reduction-side damping valve is provided. The disk valve 7 on the reduction side is an oil liquid that flows through the oil passage 6A of the piston 6 when the piston 6 slides downward along the inner cylinder 4 during the reduction stroke of the piston rod 10 described later (that is, A predetermined damping force is generated by applying a resistance force to the oil liquid flowing in the oil passage 6A from the bottom side oil chamber B to the rod side oil chamber C.

  A disc valve 8 that constitutes an extension-side damping valve is provided on the lower surface of the piston 6. When the piston 6 slides upward along the inner cylinder 4 during the extension stroke of the piston rod 10, the extension-side disc valve 8 is a fluid that flows through the oil passage 6 </ b> B of the piston 6 (that is, the rod side). A predetermined damping force is generated by applying a resistance force to the oil fluid flowing in the oil passage 6B from the oil chamber C toward the bottom oil chamber B.

  Here, a back pressure chamber 9 is formed on the back side of the extension-side disc valve 8 by a back pressure chamber forming body 15 or the like which will be described later. The back pressure chamber 9 applies an internal pressure in the valve closing direction to the extension-side disk valve 8. For this reason, the opening side disk valve 8 is variably controlled according to the pressure in the back pressure chamber 9 (that is, the liquid chamber 23) as will be described later.

  The piston rod 10 extends in the inner cylinder 4 in the axial direction. The piston rod 10 is composed of a total of three members including a rod member 11, a relay member 12, and a piston support member 13. The rod member 11 is configured as a long member whose lower end is inserted into the inner cylinder 4 and whose upper end extends (projects) to the outside of the outer cylinder 1 via a rod guide 18, a lid 3, and the like which will be described later. Yes. The piston support member 13 is attached to the lower end side of the rod member 11 via a cylindrical relay member 12 and is configured as a short member that supports the piston 6.

  On the lower end side of the rod member 11, a screw hole portion 11A into which the upper end side (male screw portion 12B) of the relay member 12 is screwed is formed. Further, the rod member 11 is formed with a vent hole 11B composed of an axial hole extending in the axial direction to the position of the screw hole portion 11A. The ventilation hole 11 </ b> B constitutes a ventilation path for supplying and discharging a working gas described later to the gas chamber 22 in the relay member 12.

  The relay member 12 of the piston rod 10 is formed as a stepped cylindrical joint member, and its upper and lower ends are connected to the rod member 11 and the piston support member 13. The relay member 12 is formed with a sliding hole 12 </ b> A into which a later-described free piston 21 is slidably fitted in the inner peripheral side of the intermediate portion in the length direction (upward and downward directions). On the upper end side of the relay member 12, a male screw portion 12B that is screwed into the screw hole portion 11A of the rod member 11 is provided, and the center side of the male screw portion 12B is always in communication with the vent hole 11B of the rod member 11. A communication hole 12C is formed. The communication hole 12 </ b> C constitutes an in-rod passage 10 </ b> A together with the sliding hole 12 </ b> A for the free piston 21 and the vent hole 11 </ b> B of the rod member 11.

  The piston support member 13 has a large-diameter boss portion 13A fixed to the lower end side of the relay member 12 (that is, the opening end side below the sliding hole 12) by means of screwing or the like, and the boss It includes a small-diameter rod portion 13B that protrudes downward from the boss portion 13A so as to be coaxial with the portion 13A and is connected to the outer peripheral side of the piston 6 in an inserted state. A nut 14 is screwed to the lower end side of the rod portion 13B. The nut 14 prevents the piston 6, the disk valves 7, 8 and the back pressure chamber forming body 15 from being removed from the rod portion 13B of the piston support member 13. , It is fixed in a non-rotating state.

  Further, the piston support member 13 has a liquid hole 13C extending in the axial direction from the boss portion 13A to the midway position of the rod portion 13B, and the liquid hole 13C extending in the radial direction of the liquid hole 13C communicates with the back pressure chamber 9. A radial hole 13D is provided. The liquid hole 13C and the radial hole 13D of the piston support member 13 are always filled with an oil liquid, and constitute a communication path that constantly connects a liquid chamber 23 described later to the back pressure chamber 9.

  As shown in FIG. 2, the back pressure chamber forming body 15 is provided so as to sandwich the extension-side disc valve 8 between the lower surface of the piston 6. The back pressure chamber forming body 15 is disposed on the back side of the disc valve 8 and is formed as a shallow bottomed cylindrical body, and an elastic seal that is fitted to the opening side of the back case 16 with a tightening margin. And a valve member 17 that has a back pressure chamber 9 between the rear case 16 and the rear case 16. The valve member 17 acts on the disk valve 8 with the pressure in the back pressure chamber 9 (pressure in the valve closing direction) so as to press the disk valve 8 on the extension side toward the lower surface (valve seat) of the piston 6. It is something to be made.

  The elastic seal 17A of the valve member 17 is made of a ring-shaped elastic body that is fixed to a disk that is integral with or separate from the disk valve 8 on the extension side by means of vulcanization, baking, or the like. The inner back pressure chamber 9 is liquid-tightly sealed with respect to the outer bottom oil chamber B. When a separate disk is used, the disk may be configured to contact the disk valve 8 from the back side.

  A rod guide 18 for guiding the piston rod 10 in the axial direction is provided on the upper end side of the inner cylinder 4. The rod guide 18 is formed in a stepped cylindrical shape, for example, by performing molding processing, cutting processing, or the like on a metal material, a hard resin material, or the like. The rod guide 18 is provided to be fitted to the upper end side of the outer cylinder 1, and the upper portion of the inner cylinder 4 is positioned at the center of the outer cylinder 1 in this state. The rod guide 18 constitutes a support structure that supports the lid 3 from the lower side (inside the outer cylinder 1) when the lid 3 is caulked and fixed from the outside to the upper end side of the outer cylinder 1 by the caulking portion 1A. .

  A rod seal 19 is provided on the inner diameter side of the lid 3. The rod seal 19 is made of an elastic material such as nitrile rubber. The rod seal 19 seals between the lid 3 and the piston rod 10 by sliding contact with the outer peripheral surface of the piston rod 10. The oil liquid sealed in the inner cylinder 4 is suppressed or prevented by the rod seal 19 from leaking to the outside from the rod guide 18 side when the piston rod 10 (rod member 11) expands and contracts.

  Next, the back pressure chamber adjusting mechanism 20 capable of adjusting the pressure in the back pressure chamber 9 from the outside will be described.

  The back pressure chamber adjusting mechanism 20 is slidably inserted into a rod inner passage 10A provided in the piston rod 10 and in the middle of the rod inner passage 10A (that is, in the sliding hole 12A of the relay member 12). And a free piston 21 as a movable partition that adjusts the pressure in the back pressure chamber 9 according to the pressure of the working gas.

  The rod inner passage 10A of the piston rod 10 includes a vent hole 11B of the rod member 11, a sliding hole 12A of the relay member 12, a communication hole 12C, and the like. The free piston 21 is provided by being inserted into the sliding hole 12A of the relay member 12, and the inside of the sliding hole 12A is defined by an upper gas chamber 22 and a lower liquid chamber 23. A first spring 24 that constantly biases the free piston 21 toward the liquid chamber 23 is disposed in the gas chamber 22. In the liquid chamber 23, the 2nd spring 25 which always urges | biases the free piston 21 toward the gas chamber 22 side is arrange | positioned.

  Here, the first and second springs 24 and 25 compensate for the stable displacement of the free piston 21 in the axial direction (up and down) in the sliding hole 12A of the relay member 12. . The liquid chamber 23 of the back pressure chamber adjusting mechanism 20 always communicates with the back pressure chamber 9 on the back pressure chamber forming body 15 side through the liquid hole 13C and the radial hole 13D of the piston support member 13, and these are preliminarily connected to the oil liquid. It is in a state filled with (working liquid). For this reason, the liquid chamber 23 and the back pressure chamber 9 of the back pressure chamber adjusting mechanism 20 are maintained in a substantially equal pressure state.

  In this way, the liquid chamber 23 always filled with the oil liquid has, for example, the first spring 24 and a spring member having a spring force larger than that of the second spring 25 in order to suppress the generation of bubbles and the like inside. It is good to comprise using (biasing member). The working liquid is a highly incompressible fluid compared to the working gas. For this reason, the second spring 25 provided in the liquid chamber 23 may be omitted depending on circumstances.

  The gas chamber 22 of the back pressure chamber adjusting mechanism 20 is always in communication with the communication hole 12C of the relay member 12 and the vent hole 11B of the rod member 11, and the vent hole 11B of the rod member 11 is connected to the external pipe 31 shown in FIG. Has been. For this reason, working gas is supplied into the gas chamber 22 of the back pressure chamber adjusting mechanism 20 from the external pipe 31 side as described later. As a result, the back pressure chamber adjusting mechanism 20 changes the pressure in the gas chamber 22 in accordance with the supply and discharge of the working gas, and the free piston 21 moves along with the pressure in the liquid chamber 23 (that is, in the back pressure chamber 9). ) Is changed according to the pressure in the gas chamber 22.

  For this reason, the back pressure chamber adjusting mechanism 20 increases the pressure in the back pressure chamber 9 as the pressure of the working gas supplied from the outside increases, and increases the back pressure as the pressure of the working gas decreases. The pressure in the back pressure chamber 9 is adjusted so as to reduce the pressure in the pressure chamber 9. The pressure in the back pressure chamber 9 is adjusted by, for example, a bending allowance when the elastic seal 17A of the valve member 17 is elastically (flexed).

  A rebound stopper 26 is provided on the rod member 11 of the piston rod 10 so as to be displaceable via a rebound spring 27, and the lower end side of the rebound spring 27 is supported from below by a spring receiver 28. The rebound stopper 26 can buffer the impact at the stroke end in the extension stroke by elastically bending and deforming the rebound spring 27 when the piston rod 10 is fully extended.

  A bump rubber receiver 29 is provided at the upper end of the outer cylinder 1 so as to cover the lid 3 from above. The bump rubber receiver 29 cushions an impact at the stroke end during the reduction stroke of the piston rod 10, so that a bump rubber (not shown) provided on the protruding end side of the rod member 11 is brought into contact in an elastically deformed state. Is. On the other hand, a mounting bracket 30 for mounting the shock absorber on the wheel side (not shown) of the vehicle is provided on the lower end side of the outer cylinder 1.

  When the shock absorber is configured as an air suspension device, the air chamber 46 is connected to the protruding end of the piston rod 10 (rod member 11) and the outer cylinder 1 using, for example, a rubber tube 45 described later shown in FIG. Can be formed between. And it is good also as a structure which adjusts vehicle height by absorbing and discharging gas, such as compressed air, in the air chamber 46, and extending or contracting the piston rod 10. FIG.

  Next, a system configuration for supplying / exhausting working gas to / from the back pressure chamber adjusting mechanism 20 will be described.

  The external pipe 31 shown in FIG. 1 has one end connected to the supply / discharge control valve 32 and the other end connected to the vent 11 </ b> B of the rod member 11. The supply / exhaust control valve 32 is composed of, for example, a directional control valve at a 3-port 3-position, and the exhaust port 33 is opened to the atmosphere. On the other hand, the supply / exhaust control valve 32 is connected to the pressurized air source 34 on the supply port side. The pressurized air source 34 is constituted by a gas tank in which a gas such as dry air is stored in a compressed state. It is also possible to connect the exhaust port 33 of the supply / discharge control valve 32 to, for example, a low-pressure tank (not shown) and collect the low-pressure dry gas and temporarily store it.

  When the supply / discharge control valve 32 is switched from the neutral position (A) to the switching position (B), the compressed gas (that is, working gas) in the dry state is supplied from the pressure source 34 via the external pipe 31 and the rod passage 10A. The gas is supplied into the gas chamber 22 of the back pressure chamber adjusting mechanism 20. On the other hand, when the supply / discharge control valve 32 is switched from the neutral position (A) to the switching position (C), the working gas is exhausted from the gas chamber 22 of the back pressure chamber adjusting mechanism 20 through the rod internal passage 10A and the external pipe 31. It is discharged to the port 33 side.

  When the supply / discharge control valve 32 is returned to the neutral position (A), the supply / exhaust of the working gas to the gas chamber 22 of the back pressure chamber adjusting mechanism 20 is stopped (shut off), and the pressure in the gas chamber 22 (that is, The pressure in the liquid chamber 23 and the back pressure chamber 9) is maintained at a desired pressure state. The pressurized air source 34 is not limited to the gas tank, and may be constituted by a compressor such as an air compressor. In this case, for example, a dryer (not shown) that dries the compressed gas in the middle of the external pipe 31 or the like. )) Etc. should be arranged.

  The shock absorber according to the first embodiment has the above-described configuration, and the operation thereof will be described next.

  First, when the shock absorber is assembled to the vehicle, the protruding end side of the piston rod 10 (rod member 11) is attached to the vehicle body side, and the lower end side of the outer cylinder 1 is attached to the axle side via the attachment bracket 30. As a result, when vibration is generated while the vehicle is running, the piston rod 10 is expanded and contracted, and a damping force is generated by the disk valves 7 and 8 of the piston 6 to attenuate the vibration at this time.

  That is, when the piston rod 10 is in the reduction stroke, the pressure in the bottom side oil chamber B is higher than that in the rod side oil chamber C. Then, it circulates into the rod side oil chamber C through the disc valve 7 and generates a damping force. Then, an amount of oil corresponding to the volume of the piston rod 10 entering the inner cylinder 4 flows from the bottom side oil chamber B into the reservoir chamber A via the bottom valve 5, and in the reservoir chamber A The gas enclosed inside is compressed to absorb the ingress volume of the piston rod 10.

  On the other hand, when the piston rod 10 is in the extension stroke, the pressure in the rod-side oil chamber C is higher than that in the bottom-side oil chamber B. Then, it circulates into the bottom side oil chamber B through the disk valve 8, and a damping force is generated. An amount of oil corresponding to the advancing volume of the piston rod 10 that has advanced from the inner cylinder 4 flows into the bottom-side oil chamber B from the reservoir chamber A through the bottom valve 5.

  Here, the extension-side disc valve 8 has a back pressure chamber 9 formed on the back side by a back pressure chamber forming body 15. The pressure in the back pressure chamber 9 is variably adjusted by a back pressure chamber adjusting mechanism 20 provided in the piston rod 10. The back pressure chamber adjusting mechanism 20 is provided in a rod passage 10A provided in the piston rod 10 and slidably inserted in the rod passage 10A, and the pressure in the back pressure chamber 9 is changed to a working gas. And a free piston 21 that adjusts according to the pressure of the. The free piston 21 is provided by being inserted into the sliding hole 12A of the relay member 12, and the sliding hole 12A is defined by an upper gas chamber 22 and a lower liquid chamber 23.

  The working gas is supplied / exhausted into / from the gas chamber 22 of the back pressure chamber adjusting mechanism 20 via an external pressure source 34 via the supply / discharge control valve 32, the external pipe 31, the rod internal passage 10A, and the like. That is, when the supply / discharge control valve 32 is switched from the neutral position (A) to the switching position (B), the working gas is supplied into the gas chamber 22 of the back pressure chamber adjusting mechanism 20, and the pressure in the gas chamber 22 is To rise.

  On the other hand, when the supply / discharge control valve 32 is switched from the neutral position (A) to the switching position (C), the working gas is discharged from the gas chamber 22 of the back pressure chamber adjustment mechanism 20 to the outside. The pressure drops. As a result, the back pressure chamber adjusting mechanism 20 changes the pressure in the gas chamber 22 in accordance with the supply and discharge of the working gas, and the free piston 21 moves along with the pressure in the liquid chamber 23 (that is, in the back pressure chamber 9). ) Is changed according to the pressure in the gas chamber 22.

  For this reason, the back pressure chamber adjusting mechanism 20 increases the pressure in the back pressure chamber 9 as the pressure of the working gas supplied from the outside increases, and increases the back pressure as the pressure of the working gas decreases. The pressure of the back pressure chamber 9 can be adjusted so as to reduce the pressure in the pressure chamber 9. As a result, the opening-side pressure of the extension-side disc valve 8 is variably controlled as the pressure in the back-pressure chamber 9 changes, whereby the extension-side damping force is changed to the pressure in the back-pressure chamber 9. It can be variably adjusted accordingly.

  Thus, according to the first embodiment, the back pressure chamber 9 in which the internal pressure in the valve closing direction is applied to the extension-side disk valve 8 constituting the damping valve is provided on the lower surface side of the piston 6. The formed body 15 is used. The piston rod 10 includes a rod internal passage 10A provided in the piston rod 10 and a free piston 21 that is slidably inserted in the rod internal passage 10A and capable of adjusting the pressure in the back pressure chamber 9. A back pressure chamber adjusting mechanism 20 is provided. The back pressure chamber adjusting mechanism 20 supplies / discharges working gas for pressure adjustment from the outside of the free piston 21 to the in-rod passage 10 </ b> A (that is, inside the vent hole 11 </ b> B and the gas chamber 22) by, for example, the supply / discharge control valve 32. It is configured.

  By adopting such a configuration, by changing the working gas (gas pressure) from the outside, for example, the damping force characteristic (ie, damping force is controlled by controlling the hydraulic pressure of the damper) by the disk valve 8 on the extension side is adjusted. be able to. That is, the pressure of the back pressure chamber 9 can be adjusted according to the pressure of the working gas supplied and discharged from the outside, and the opening side pressure of the disk valve 8 on the extension side changes as the pressure in the back pressure chamber 9 changes. Since it changes, the damping force on the extension side can be variably adjusted according to the pressure in the back pressure chamber 9. In this case, the reduction-side damping force can be variably adjusted according to the pressure in the back pressure chamber by adopting a similar configuration for the reduction-side disk valve 7.

  Further, the gas pressure control of the working gas can be configured to control the spring characteristics and the damping force suitable for the vehicle behavior in real time by the control logic. For example, the damping force can be changed to an appropriate value by adding the gas pressure control of the working gas as a plus function to the vehicle height adjustment function employed in the current air suspension device. In this case, for example, when the vehicle height is low, control such as a high damping force is possible.

  Therefore, according to the first embodiment, for example, the tuning range of the generated damping force can be widened by adjusting the pressure of the oil liquid guided to the back pressure chamber 9 according to the pressure of the working gas. . Moreover, by combining with the current air suspension device, not only the vehicle height adjustment and the air spring constant but also the damping force control can be performed simultaneously by the working gas supplied from the pressure source 34 (for example, compressor) provided outside. It becomes possible. For example, unlike a semi-active suspension, since a large current is not required, a cheaper system is possible.

  Next, FIG. 3 shows a second embodiment. The feature of this embodiment is that the shock absorber is applied to an air suspension device. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  Here, on the projecting end side of the piston rod 10 (rod member 11), an anti-vibration mounting bracket 41, a covered cylindrical canister 42, a bump rubber 43, and the like are provided. The protruding end side of the piston rod 10 is attached to the vehicle body side of the vehicle by a plurality of bolts 41 </ b> A provided on the mounting bracket 41.

  The bump rubber 43 provided on the protruding end side of the rod member 11 abuts (collises) with the bump rubber receiver 29 on the outer cylinder 1 side in the upward and downward directions when the piston rod 10 is fully contracted. At this time, the bump rubber 43 is elastically deformed to reduce an impact when the bump rubber 43 collides with the bump rubber receiver 29.

  A bottomed cylindrical air piston 44 is provided on the outer peripheral side of the outer cylinder 1 so as to face the canister 42 in the upward and downward directions. The air piston 44 is attached so as to be displaced integrally with the outer cylinder 1. On the other hand, the covered cylindrical canister 42 is attached to the protruding end side of the rod member 11 so as to be displaced integrally (moved upward and downward) with the piston rod 10.

  A cylindrical rubber tube 45 made of an elastic rubber material is provided between the canister 42 and the air piston 44. The rubber tube 45 made of a cylindrical body is formed by folding the middle portion in the length direction into a U-shaped cross section. The upper end side of the rubber tube 45 is fixed in an airtight state to the lower end (opening end) side of the canister 42, and the lower end side is fixed in an airtight state to the upper end side of the rubber tube 45, thereby defining an air chamber 46 inside. It is made. The air chamber 46 operates as an air spring, and the piston rod 10 is always urged in the extending direction by the air spring.

  That is, in the air chamber 46, for example, dry compressed air is supplied and discharged from the outside, and the rubber tube 45 is elastically deformed accordingly, whereby the air chamber 46 is expanded or contracted. When the air chamber 46 is expanded, the piston rod 10 largely protrudes upward from the outer cylinder 1, and thereby the vehicle height of the vehicle is adjusted to be high. When the air chamber 46 is reduced, the piston rod 10 is reduced into the outer cylinder 1 (inner cylinder 4), thereby adjusting the vehicle height to be lower.

  A bellows-like protective cover 47 is disposed outside the rubber tube 45 in the radial direction. The protective cover 47 surrounds the rubber tube 45 from the outside, thereby preventing the stepping stones from the outside from striking the rubber tube 45 and preventing the rubber tube 45 from being damaged or damaged.

  Thus, also in the second embodiment configured as described above, the rod internal passage 10A (ie, in the vent hole 11B and the gas chamber 22) from the outside of the free piston 21 as in the first embodiment. By supplying and discharging the working gas for pressure adjustment, for example, the pressure of the oil liquid guided to the back pressure chamber 9 can be adjusted according to the pressure of the working gas, and the tuning range of the generated damping force can be widened. it can.

  In particular, in the second embodiment, a shock absorber is combined with an air suspension device as shown in FIG. For this reason, by supplying / exhausting compressed air to / from the air chamber 46 and / or the rod internal passage 10A (ventilation hole 11B) from an external compressor (not shown) or the pressure source 34 shown in FIG. Not only high adjustment and air spring constant but also damping force can be controlled at the same time.

  In this case, the pressure of the working gas supplied / exhausted from the outside of the free piston 21 to the in-rod passage 10A (that is, in the vent hole 11B and the gas chamber 22) and the pressure in the air chamber 46 are controlled to be different from each other. It is good also as composition to do. For this reason, it can be set as the structure which controls the spring characteristic and damping force suitable for a vehicle behavior by control logic in real time.

  In the first embodiment, the case where the working gas supply / exhaust control valve 32 is constituted by a directional control valve at a 3-port 3-position as shown in FIG. 1 has been described as an example. However, the present invention is not limited to this. For example, the supply and discharge of the working gas may be controlled using a plurality of solenoid valves or the like.

  In the first embodiment, a shock absorber using a multi-cylinder cylinder including the outer cylinder 1 and the inner cylinder 4 has been described as an example. However, the present invention is not limited to this, and may be applied to a shock absorber composed of, for example, a single cylinder. This is the same for the second embodiment.

  In each of the above embodiments, the shock absorber used as the air suspension device has been described as an example. However, the present invention is not limited to this, and a suspension spring made of, for example, a coil spring or the like may be provided between the protruding end of the piston rod and the cylinder, and the piston rod may be constantly urged in the extending direction by the suspension spring.

  Furthermore, in each embodiment, the shock absorber attached to vehicles, such as a motor vehicle, was mentioned as an example and demonstrated. However, the present invention is not limited to this. For example, the present invention may be applied to a shock absorber used in various machines, structures, buildings, and the like that serve as vibration sources.

1 outer cylinder 2 bottom cap 3 lid 4 inner cylinder (cylinder)
6 Piston 6A, 6B Oil passage (passage)
7 Reduced disc valve (attenuation valve)
8 Disc valve on the extension side (damping valve)
9 Back pressure chamber 10 Piston rod 10A Rod passage 18 Rod guide 20 Back pressure chamber adjustment mechanism 21 Free piston 22 Gas chamber 23 Liquid chamber A Reservoir chamber B Bottom side oil chamber C Rod side oil chamber

Claims (2)

A cylinder filled with working fluid;
A piston that is slidably fitted in the cylinder and divides the cylinder into two chambers;
A piston rod connected to the piston and extending outside the cylinder;
A passage through which the working liquid flows from one chamber in the cylinder to the other chamber by the movement of the piston;
A damping valve that is provided in the passage and restricts a flow of the working liquid generated by sliding of the piston to generate a damping force;
A back pressure chamber that applies an internal pressure to the damping valve in the valve closing direction; and
A back pressure chamber adjusting mechanism capable of adjusting the pressure in the back pressure chamber from the outside,
The back pressure chamber adjusting mechanism includes a rod inner passage provided in the piston rod, a free piston that is slidably inserted in the rod inner passage and is capable of adjusting the pressure of the back pressure chamber, Consists of
The shock absorber according to claim 1, wherein a working gas for pressure adjustment is supplied to the passage in the rod from the outside of the free piston.   The back pressure chamber adjusting mechanism increases the pressure in the back pressure chamber as the pressure of the working gas supplied from the outside increases, and increases the pressure in the back pressure chamber as the pressure of the working gas decreases. The shock absorber according to claim 1, wherein the shock absorber is configured to reduce pressure.

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