JP4939505B2 - Shock absorber - Google Patents

Description

  The present invention relates to a shock absorber.

  In a conventional shock absorber, for example, a cylinder, a rod inserted into the cylinder, a piston provided in the middle of the rod and defining two pressure chambers in the cylinder, and extended to the cylinder And a reservoir that is formed in a cylindrical extension and into which one end of the rod is inserted.

According to this double rod type shock absorber, the pressure chamber and the reservoir are communicated with each other through the gap between the rod and the bearing member that guides the rod, and the volume change due to the change in the hydraulic oil temperature is compensated by the reservoir. (For example, refer to Patent Document 1).
Japanese Patent Laying-Open No. 2004-270902 (FIG. 1)

  In such a shock absorber, as described above, the rod is inserted into the reservoir, and the pressure in the air chamber always acts on the rod, and this extends the shock absorber as a rod reaction force. In addition, since the rod changes the volume of the air chamber in the reservoir during expansion and contraction of the shock absorber, the rod reaction force changes.

  Therefore, when such a shock absorber is applied to a vehicle, the rod reaction force not only affects the vehicle height, but also affects the ride comfort in the vehicle, so the pressure in the air chamber is necessarily limited. It cannot be set freely.

  In other words, there is no degree of freedom in setting the pressure in the air chamber, in other words, there is no degree of freedom in setting the damping force generated by the shock absorber and the response. There is a possibility that the optimum setting for the ride comfort in the vehicle cannot be performed.

  In addition, since the reservoir in which one end side of the rod appears and disappears only in the extended portion, when the rod diameter is increased, it is necessary to take care such as lengthening the extended portion to ensure the reservoir volume, A shock absorber will become long and the mounting property to the narrow space between a vehicle body and an axle will deteriorate.

  Accordingly, the present invention has been developed to improve the above-described problems, and the object of the present invention is to improve the riding comfort in the vehicle and to deteriorate the mounting property in the vehicle. There is no shock absorber.

  In order to achieve the above object, the means for solving the problems of the present invention includes a cylinder, a rod movably inserted into the cylinder, an intermediate portion of the rod, and slidably inserted into the cylinder. In a shock absorber provided with a piston that separates two pressure chambers and set in a double rod type, a cylindrical member that covers the cylinder and forms a first annular gap between the cylinder and one end of a rod protruding from the cylinder An inner cylinder provided on the outer circumference of the outer cylinder, an outer cylinder that covers the inner cylinder and forms a second annular gap between the inner cylinder, and an annular free piston that is in sliding contact with the outer circumference of the inner cylinder and the inner circumference of the outer cylinder. The second annular gap is partitioned into an air chamber and a space by a free piston, and a liquid chamber is formed by communicating the first annular gap and the space, and the liquid chamber is disposed on the upper side. Flow from pressure chamber to liquid chamber to pressure chamber Communicated with via a one-way passage to permit only, characterized in that communicate with each other through a throttle passage that provides resistance to flow through to the pressure chamber disposed on the lower side.

  According to the shock absorber of the present invention, the air chamber that pressurizes the inside of the cylinder is formed between the inner cylinder and the outer cylinder that are disposed on the outer periphery of one end of the rod. Not.

  Therefore, according to this shock absorber, since the pressure in the air chamber does not act on the rod, the pressure in the air chamber that pressurizes the cylinder can be freely set without being restricted by the setting of the pressure in the air chamber. The damping force generated by the shock absorber and the degree of freedom in setting the responsiveness are dramatically increased, and the pressure in the air chamber can be set to be optimal for the ride comfort in the vehicle. Can be improved.

  The pressure in the air chamber can be applied to the seal member that seals the outer periphery of the rod via the pressure chamber, and the frictional force between the rod and the seal member can be tuned by setting the pressure in the air chamber. In particular, by increasing the frictional force between the rod and the seal member, the frictional force is superimposed on the damping force generated by the shock absorber, and the piston speed when the piston moves relative to the cylinder. It is possible to increase the damping force when the vehicle is low and to firmly suppress the behavior of rolling, pitching, squat, etc. of the vehicle body.

  Even if the diameter of the rod must be increased, the liquid chamber is also formed on the outer periphery of the cylinder so that the rod does not appear and disappear. Therefore, the liquid chamber is not affected by the diameter of the rod. The entire volume of the chamber and the air chamber can be secured, the overall length of the shock absorber is not increased, and the mounting property on the vehicle is not deteriorated.

  The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view of a shock absorber according to an embodiment.

  As shown in FIG. 1, a shock absorber D according to an embodiment is provided in a cylinder 1, a rod 2 that is movably inserted into the cylinder 1, and an intermediate portion of the rod 2 and slides in the cylinder 1. A piston 3 that is freely inserted and separates the two pressure chambers R1 and R2, a cylinder member 4 that covers the cylinder 1 and forms a first annular gap N1 between the cylinder 1 and a rod that protrudes from the cylinder 1 2, the outer cylinder 6 provided on the outer periphery of the one end 2 a, the outer cylinder 6 that covers the inner cylinder 5 and forms the second annular gap N 2 between the inner cylinder 5, the outer periphery of the inner cylinder 5, and the outer cylinder 6 An annular free piston 7 slidably in contact with the inner periphery, an air chamber G and a space A partitioned by the free piston 7 in the second annular gap N2, and the first annular gap N1 and the space A are communicated with each other. The liquid chamber L and the liquid chamber L are arranged on the upper side A one-way passage 8 communicating with the force chamber R1 and allowing only a flow from the pressure chamber R1 toward the liquid chamber L, and a resistance to the flow passing through the liquid chamber L to the pressure chamber R2 disposed on the lower side. And a throttle passage 9 for providing

  Hereinafter, each member will be described in detail. The cylinder 1 is closed at its upper and lower ends by rod guides 10 and 11 each having an annular shape, and the cylinder 1 is separated by a piston 3 slidably inserted into the cylinder 1. Two pressure chambers R1 and R2 are partitioned, and these pressure chambers are filled with a liquid such as hydraulic oil.

  The piston 3 has an annular shape and is attached to the middle of a rod 2 that is movably inserted into the cylinder 1, and has ports 3a and 3b that communicate the pressure chamber R1 and the pressure chamber R2.

  A leaf valve Va that opens and closes the port 3a is stacked and attached to an intermediate portion of the rod 2 above the piston 3 in FIG. 1, and a leaf valve Vb that opens and closes the port 3b is located below the piston 3 in FIG. Are stacked and attached to an intermediate portion of the rod 2.

  Furthermore, one end 2a of the rod 2 which is the lower end in FIG. 1 is inserted into a cylindrical bearing 13 which is fixed inside the annular rod guide 11 which closes the lower end in FIG. The other end 2b of the rod 2 that is the upper end in FIG. 1 is inserted into a cylindrical bearing 12 that is fixed to the inside of an annular rod guide 10 that closes the upper end in FIG. It protrudes outside.

  Note that the one end 2a of the rod 2 is not connected to the vehicle body or axle to be controlled, and no axial force is applied, so that it may be hollow for the purpose of weight reduction.

  A cylinder member 4 is provided outside the cylinder 1 so as to cover the cylinder 1 and form a first annular gap N1 between the cylinder 1 and the cylinder member 4 in the upper end in FIG. A rod guide 10 disposed on the upper side is fitted and fixed to the periphery.

  A seal ring 14 is interposed between the cylindrical member 4 and the rod guide 10, and a cover 16 is screwed onto the cylindrical member 4 in a state where the sealing member 15 is stacked above the rod guide 10. It is fixed, and the seal member 15 seals between the other end 2b of the rod 2 and the rod guide 10, and the upper ends of the cylinder member 4 and the cylinder 1 are sealed.

  The rod guide 10 includes a fitting portion 10a that fits into the cylinder 1 at the lower end, a step portion 10b is formed on the outer periphery, and a communication path 10c that communicates from the lower end of the fitting portion 10a to the step portion 10b. It has. The communication passage 10c is opened and closed by an annular plate 23 that functions as a check valve that is sandwiched between the step portion 10c of the rod guide 10 and the upper end of the cylinder 1 in FIG. When the pressure in the pressure chamber R1 increases and reaches a predetermined valve opening pressure, the annular plate 23 bends to connect the communication passage 10c to the liquid chamber L formed between the cylinder 1 and the cylindrical member 4. The bubbles mixed in the pressure chamber R1 can be refluxed to the liquid chamber L. That is, in this embodiment, the one-way passage 8 is formed by the communication passage 10 c and the annular plate 23.

  Note that a lip portion 15a that is in sliding contact with the outer periphery of the other end 2b of the rod 2 is provided on the inner periphery of the seal member 15, and this lip portion 15a is provided on the seal member 15 side of the rod guide 10 and is continuously connected. It faces a recess 10d that leads to the middle of the passage 10c, and is pressed against the outer periphery of the other end 2b of the rod 2 by the pressure in the pressure chamber R1.

  Further, the upper end of the outer cylinder 6 is fitted to the inner periphery of the lower end in FIG. 1 of the cylindrical member 4, and the lower end of the cylindrical member 4 is welded to the outer periphery of the outer cylinder 6. 6 is integrated.

  The outer cylinder 6 is formed with a thick portion 6a having a small intermediate inner diameter, and an inner cylinder 5 disposed on the outer periphery of one end 2a of the rod 2 is formed on the inner periphery of the thick portion 6a. It is designed to be screwed. Further, a rod guide 11 fitted to the lower end of the cylinder 1 is fitted to the inner periphery of the upper end of the outer cylinder 6, and between the thick portion 6 a and the rod guide 11, one end of the rod guide 11 and the rod 2. A seal member 17 for sealing between 2a is interposed. A seal ring 24 is interposed between the rod guide 11 and the outer cylinder 6 to seal between the rod guide 11 and the outer cylinder 6.

  The rod guide 11 has a fitting portion 11a fitted to the cylinder 1 at the upper end, a step portion 11b is formed on the outer periphery, and a throttle passage 9 that leads from the upper end of the fitting portion 11a to the step portion 11b. ing. The throttle passage 9 communicates the pressure chamber R2 disposed on the lower side to the first annular gap N1, and provides resistance to the flow of liquid passing therethrough.

  Note that a lip portion 17a that is in sliding contact with the outer periphery of one end 2a of the rod 2 is provided on the inner periphery of the seal member 17, and this lip portion 17a is provided on the seal member 17 side of the rod guide 11 and is a pressure chamber. It faces the recess 11c that leads to R2, and is pressed against the outer periphery of one end 2a of the rod 2 by the pressure in the pressure chamber R2.

  In turn, the inner cylinder 5 is provided with a flange 5 a that is in contact with the inner periphery of the outer cylinder 6 on the outer periphery of the end opposite to the cylinder, which is the lower end in FIG. 1, and between the outer cylinder 6 and the inner cylinder 5. The second annular gap N2 formed in the closed space is closed by the thick portion 6a of the outer cylinder 6 and the flange 5a. Further, seal rings 18 and 19 are interposed between the outer periphery of the flange 5a and the outer cylinder 6 and between the thick portion 6a of the outer cylinder 6 and the inner cylinder 5, respectively. And the inner cylinder 5 are tightly sealed.

  In this second annular gap N2, an annular free piston 7 slidably inserted into the outer circumference of the inner cylinder 5 and the inner circumference of the outer cylinder 6 is slidably inserted, and the second annular gap N2 is shown in FIG. 1 is divided into an air chamber G in which the middle and lower gas is enclosed and an upper space A in FIG. 1, and gas is injected into the air chamber G through an injection hole 5b that penetrates the flange 5a up and down in FIG. The air chamber G can be sealed by closing the injection hole 5b with a plug 20 screwed into the injection hole 5b.

  The lower end of the outer cylinder 6 is configured so that a cap 21 having an attachment portion 22 capable of attaching the shock absorber D to the vehicle is attached by screw fastening. When adjustment of the air pressure in the air chamber G is necessary The cap 21 can be removed and the plug 20 can be easily accessed.

  In the case of this embodiment, the cap 21 is screwed to the lower end of the outer cylinder 6 to functionally form a part of the outer cylinder 6 and protects the rod 2 from flying objects, rain, and dust. Therefore, the outer cylinder 6 and the cylindrical portion of the cap 21 cover the entire stroke range of the one end 2a of the rod 2, but the outer cylinder 6 covers the entire stroke range of the one end 2a of the rod 2. It may be. If the rod 2 does not need to be protected, the outer cylinder 6 does not cover the entire stroke range of the one end 2a of the rod 2, and the lengths of the inner cylinder 5 and the outer cylinder 6 are set to the air chamber G and the liquid chamber. You may make it set to the length which can form a part of L.

  Further, the inside of the inner cylinder 5 is closed by the cap 21, and when the shock absorber D expands and contracts, the one end 2a of the rod 2 enters and exits into the inner cylinder 5 which is a closed space, and the atmospheric pressure in the inner cylinder 5 The air pressure in the inner cylinder 5 acts on the rod 2, but the inner cylinder 5 fluctuates on the basis of the atmospheric pressure without being pressurized and sealed. Since the impact on the damping force generated by the shock absorber D is small because it does not become large, there is no particular problem, but the cap 21 or the outer cylinder 6 is moved into the inner cylinder 5 so that the inner cylinder 5 is not sealed. A communicating hole may be provided so that the inner cylinder 5 does not act as a gas spring so as to eliminate the influence on the damping force.

  Returning, when the upper end of the outer cylinder 6 is fitted to the inner periphery of the cylindrical member 4, the rod guide 11 is clamped and fixed between the cylinder 1 and the thick part 6a. In this state, the lower end of the cylindrical member 4 is thick. It is arrange | positioned at the outer periphery of the part 6a, and the welding site | part of the cylinder member 4 and the outer cylinder 6 becomes an outer periphery of the thick part 6a where the influence of a welding distortion does not arise easily to an inner peripheral side.

  As described above, the rod guide 11 is fitted to one end of the cylinder 1 and fitted to the inner circumference of the outer cylinder 6 that holds the inner cylinder 5 by fitting to the inner circumference of the cylindrical member 4. Therefore, the rod guide 11, the inner cylinder 5, the outer cylinder 6, and the rod 2 supported by the rod guide 11 are assembled on the basis of the cylinder 1, and each cylinder 1 is aligned in the radial direction. As a result, smooth expansion and contraction of the assembled shock absorber D is ensured.

  Furthermore, the outer cylinder 6 has a through-hole 6b that opens from the outer periphery of the thick-walled portion 6a and communicates with the lower end of the thick-walled portion 6a, and a vertical groove that communicates from the upper-end outer periphery to the outer peripheral opening of the thick-walled portion 6a. 6c, and when the upper end of the outer cylinder 6 is fitted to the inner periphery of the lower end of the cylindrical member 4 as described above, the first annular gap N1 and the lower end of the thick part 6a are passed through the vertical groove 6c and the through hole 6b. The space A facing is communicated. The space A and the first annular gap N1 are filled with the same liquid as in the pressure chambers R1 and R2, and a liquid chamber L is formed by the space A and the first annular gap N1.

  Accordingly, the liquid chamber L causes the internal pressure to act on the pressures of the pressure chambers R1 and R2 via the throttle passage 9, and the shock absorber D is configured as a double rod type. Since there is no overall volume change in the chambers R1 and R2, basically no volume compensation is performed when the piston is operated, and the volume change of the liquid in each of the pressure chambers R1 and R2 due to the temperature change is basically in the liquid chamber L. It compensates by absorbing the volume change of gas.

  When the piston 3 moves upward in FIG. 1 with respect to the cylinder 1 and extends, the shock absorber D leaves a flow of liquid that moves from the pressure chamber R1 to the pressure chamber R2 via the port 3b. When the valve Vb applies a resistance to generate a damping force and, conversely, when the piston 3 moves downward in FIG. 1 with respect to the cylinder 1 and performs a compression operation, the pressure chamber R2 is moved to the pressure chamber R1 through the port 3a. The leaf valve Va provides resistance to the moving liquid flow to generate a damping force.

  Thus, according to the buffer D comprised, since the air chamber G which pressurizes the inside of the cylinder 1 is formed between the inner cylinder 5 and the outer cylinder 6 arrange | positioned on the outer periphery of the end 2a of the rod 2. The thrust due to the pressure in the air chamber G is not applied to the rod 2.

  Therefore, according to this shock absorber D, the pressure in the air chamber G does not act on the rod 2, so that the setting of the pressure in the air chamber G is not limited, and the inside of the air chamber G that pressurizes the inside of the cylinder 1. Can be set freely, the degree of freedom in setting the damping force and response of the shock absorber D is greatly increased, and the pressure in the air chamber G is set to be optimal for the ride comfort in the vehicle. And the ride comfort in the vehicle can be dramatically improved.

  The pressure in the air chamber G can be applied to the seal members 15 and 17 that seal the outer periphery of the rod 2 via the pressure chambers R1 and R2, and the rod 2 and the seal member are set by setting the pressure in the air chamber G. 15 and 17 can be tuned. Particularly, the damping force generated by the shock absorber D can be increased by increasing the frictional force between the rod 2 and the seal members 15 and 17. By superimposing frictional force on the cylinder, the damping force when the piston 3 moves with respect to the cylinder 1 is low, and the damping force can be increased, and the behavior of rolling, pitching, squat, etc. of the vehicle body can be suppressed firmly. It becomes like this.

  Further, even if the diameter of the rod 2 has to be increased, the liquid chamber L is also formed on the outer peripheral side of the cylinder 1 so that the rod 2 does not appear and disappear, so that the diameter of the rod 2 is affected. Thus, the entire volume of the liquid chamber L and the air chamber G can be secured without receiving, and the total length of the shock absorber D is not increased, and the mounting property to the vehicle is not deteriorated.

  Furthermore, since the shock absorber D can be connected to the vehicle body and axle of the vehicle via the outer cylinder 6 extended from the cylinder member 4, it is possible to avoid the lateral force and the axial force from acting directly on the cylinder 1. At the same time, by covering the stroke range of the one end 2a of the rod 2 with the outer cylinder 6, the smooth sliding surface on the outer periphery of the rod 2 can be protected from flying stones, mud and the like.

  Further, in the case of this embodiment, since the open end of the outer cylinder 6 is closed by the cap 21, it is possible to reliably prevent stepping stones, mud and the like from directly interfering with the rod 2, and the rod 2 is reliably protected. It becomes.

  Furthermore, in the case of this embodiment, the pressure chamber R1 arranged on the upper side is communicated with the one-way passage 8 allowing only the flow from the pressure chamber R1 to the liquid chamber L to the liquid chamber L. Therefore, the bubbles mixed in the pressure chamber R1 can be discharged to the liquid chamber L, and a situation where the bubbles adversely affect the generated damping force of the shock absorber D can be avoided. In addition, since the annular plate 23 is used in the configuration of the one-way passage 8, the configuration is simple, the valve opening pressure is easily set, and the metal is used for the material, which is stable for a long period of time. The valve opening pressure can be maintained.

  In the above description, the shock absorber D is a so-called upright type in which the cylinder 1 is installed on the axle side. However, the one-way passage is provided so as to communicate the pressure chamber R2 and the liquid chamber L. If so, it is possible to adopt a so-called inverted type in which the other end 2b of the rod 2 is attached to the axle side. Moreover, you may make it form the cylindrical member 4 and the outer cylinder 6 with a single pipe.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

It is a longitudinal cross-sectional view of the shock absorber in one embodiment.

Explanation of symbols

1 cylinder 2 rod 2a rod one end 2b rod other end 3 piston 3a, 3b piston port 4 cylinder member 5 inner cylinder 5a inner cylinder flange 5b inner cylinder injection hole 6 outer cylinder 6a thicker part 6b outer cylinder outer Through hole 6c in the cylinder Vertical groove 7 in the outer cylinder 7 Free piston 8 One-way passage 9 Restriction passage 10, 11 Rod guide 10a, 11a Fitting portion 10b, 11b in the rod guide Step portion 10c in the rod guide Communication passage 10d in the rod guide 11c Recesses 12 and 13 in rod guide Bearings 14, 18, 19, and 24 Seal rings 15 and 17 Seal members 15a and 17a Lip portion 16 in seal member Cover 20 Plug 21 Cap 22 Cap attachment portion 23 Annular plate A Space D Buffer G Air chamber L liquid N1 first annular gap N2 second annular gap R1, R2 pressure chambers Va, Vb leaf valve

Claims (5)

A double rod type comprising a cylinder, a rod that is movably inserted into the cylinder, and a piston that is slidably inserted into the cylinder and that separates the two pressure chambers. In the shock absorber to be set, a cylinder member that covers the cylinder and forms a first annular gap with the cylinder, an inner cylinder provided on the outer periphery of one end of the rod protruding from the cylinder, and an inner cylinder that covers the inner cylinder An outer cylinder that forms a second annular gap between the outer cylinder and an annular free piston that is in sliding contact with the outer circumference of the inner cylinder and the inner circumference of the outer cylinder. While the first annular gap and the above space communicate with each other to form a liquid chamber, the liquid chamber is allowed to flow only from the pressure chamber to the liquid chamber to the pressure chamber disposed on the upper side. While communicating through the passage Shock absorber, characterized in that communicate with each other through a throttle passage that provides resistance to flow through to the pressure chamber disposed on the lower side. The shock absorber according to claim 1, wherein the outer cylinder covers a stroke range of one end of the rod. An annular rod guide that is fitted to one end of the cylinder and pivotally supports the rod is provided, and an outer cylinder is provided with a thick portion that holds the inner cylinder in the middle, and is fitted to the inner periphery of the end of the cylinder member. The shock absorber according to claim 1 or 2, wherein the shock absorber is fitted to an inner periphery of an end portion of the outer cylinder. The shock absorber according to claim 3, wherein the rod guide is clamped and fixed between a thick portion of the outer cylinder and the cylinder. A flange is provided at the end of the inner cylinder on the opposite side of the cylinder that abuts the inner circumference of the outer cylinder and closes the second annular gap in cooperation with the thick part, and gas is injected into the air chamber through the flange. The shock absorber according to claim 3 or 4, wherein an injection hole is provided.

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