JP2016188676A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorber which inhibits occurrence of aeration and cavitation without providing a baffle plate in a reservoir.SOLUTION: An opening 41 formed on a side wall of a base shell 3 is disposed so as to be offset downward relative to a passage member 30. The structure allows a hydraulic fluid traveling from a chamber defined by a case 26 to a reservoir 4 to flow only in a downward direction. As a result, the structure allows jet flow from a damping force generating mechanism to be forcibly flowed in the downward direction to prevent a gas in the reservoir 4 from mixing into or dissolving into the hydraulic fluid and inhibit occurrence of cavitation and aeration.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a shock absorber that generates a damping force by controlling a flow of a working fluid with respect to a stroke of a piston rod.

  A cylindrical hydraulic shock absorber applied to a suspension device of a vehicle such as an automobile typically has a piston rod connected to a cylinder in which a working fluid is sealed as a working fluid. The damping force is generated by controlling the flow of the hydraulic fluid generated by the sliding of the piston in the cylinder accompanying the stroke of the stroke by a damping force generating mechanism constituted by an orifice, a disk valve and the like. As such a shock absorber, a reservoir filled with hydraulic fluid and gas is connected to the cylinder, and the volume change of the hydraulic fluid accompanying the volume change temperature in the cylinder due to the entry / exit of the piston rod is compressed into the gas in the reservoir. Some are configured to compensate by expansion.

  In the above-described shock absorber, when the gas in the reservoir is mixed as bubbles in the hydraulic fluid or dissolved in the hydraulic fluid, aeration or cavitation may occur and the damping force may become unstable. Therefore, a shock absorber in which a baffle plate is disposed in a reservoir has been put into practical use (see, for example, “Patent Document 1”). Such a shock absorber isolates the inlet of the hydraulic fluid from the damping force generation mechanism to the reservoir and the liquid level of the reservoir, and gently increases the flow area of the hydraulic fluid flowing into the reservoir from the damping force generation mechanism. It is possible to suppress the gas in the reservoir from being mixed as bubbles in the hydraulic fluid or being dissolved in the hydraulic fluid, and the occurrence of cavitation and aeration can be suppressed.

JP 2012-728574 A

However, there is a demand for improving productivity by preventing the occurrence of aeration and cavitation without providing a baffle plate in the reservoir.
Therefore, an object of the present invention is to provide a shock absorber capable of suppressing the occurrence of aeration and cavitation without providing a baffle plate in a reservoir and improving productivity.

  In order to solve the above-described problems, a shock absorber according to the present invention is a shock absorber attached between two members that can move relative to each other, and is a cylinder in which a working fluid is sealed, and is fitted in the cylinder. A piston, a piston rod having one end connected to the piston and the other end extending outside the cylinder, a base shell provided on the outer periphery of the cylinder, and formed between the cylinder and the base shell And a reservoir in which working fluid and gas are sealed, a separator tube that is fitted to the outer periphery of the cylinder to form an annular passage between the cylinder, and a side wall of the separator tube that is provided on the annular passage. A communicating opening; a damping force generating mechanism that generates a damping force by controlling a flow of a working fluid generated by movement of the piston; and a side wall of the base shell A cylindrical case that is attached and accommodates the damping force generation mechanism, and a passage member that penetrates into an opening formed in a side wall of the base shell and connects the damping force generation mechanism and the opening of the separator tube; The opening formed in the side wall of the base shell is arranged to be biased downward with respect to the passage member.

  According to the shock absorber according to the present invention, it is possible to provide a shock absorber capable of suppressing the occurrence of aeration and cavitation without providing a baffle plate in the reservoir and improving productivity.

It is sectional drawing by the uniaxial plane of the buffer in 1st Embodiment. It is an enlarged view of the principal part in FIG. 1, Comprising: It is a figure which shows only a cylinder, a base shell, a reservoir | reserver, a case, and a channel | path member especially. It is explanatory drawing of 1st Embodiment, Comprising: It is a front view of the opening especially formed in the side wall of a base shell. It is explanatory drawing of 2nd Embodiment, Comprising: It is a figure corresponding to FIG. 2 of 1st Embodiment. It is explanatory drawing of 2nd Embodiment, Comprising: It is a front view of the opening especially formed in the side wall of a base shell. It is explanatory drawing of 2nd Embodiment, Comprising: It is sectional drawing by the uniaxial plane of a part of base shell containing opening especially.

(First embodiment)
A first embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, the vertical direction in FIG. 1 is referred to as the vertical direction as it is.
As shown in FIG. 1, the shock absorber 1 is a cylindrical damping force adjustment type hydraulic shock absorber, and has a double-tube structure in which a base shell 3 is provided outside the cylinder 2. An annular reservoir 4 is formed between the cylinder 2 and the base shell 3. A piston 5 is slidably fitted into the cylinder 2, and the piston 5 divides the inside of the cylinder 2 into a cylinder upper chamber 2A and a cylinder lower chamber 2B.

  One end of a piston rod 6 is connected to the piston 5 by a nut 7. The other end side of the piston rod 6 passes through the cylinder upper chamber 2 </ b> A, is inserted into a rod guide 8 and an oil seal 9 attached to the upper ends of the cylinder 2 and the base shell 3, and extends to the outside of the cylinder 2. The piston 5 is provided with passages 11 and 12 for communicating between the cylinder upper chamber 2A and the cylinder lower chamber 2B. The passage 12 is provided with a check valve 13 that allows only working fluid to flow from the cylinder lower chamber 2B side to the cylinder upper chamber 2A side. A disk valve 14 is opened in the passage 11 when the pressure of the working fluid on the cylinder upper chamber 2A side reaches a predetermined pressure, and the pressure of the working fluid on the cylinder upper chamber 2A side is relieved to the cylinder lower chamber 2B side. Is provided.

  A base valve 10 that separates the cylinder lower chamber 2 </ b> B and the reservoir 4 is provided at the lower end of the cylinder 2. The base valve 10 is provided with passages 15 and 16 that allow the cylinder lower chamber 2B and the reservoir 4 to communicate with each other. The passage 15 is provided with a check valve 17 that allows only working fluid to flow from the reservoir 4 side to the cylinder lower chamber 2B side. Further, the passage 16 is provided with a disk valve 18 that opens when the pressure of the working fluid on the cylinder lower chamber 2B side reaches a predetermined pressure and relieves the pressure of the working fluid on the cylinder lower chamber 2B side to the reservoir 4 side. It is done. The cylinder 2 is filled with a working fluid as a working fluid, and the reservoir 4 is filled with a working fluid and a gas.

  A separator tube 20 is externally fitted to the cylinder 2 via seal members 19 at both upper and lower ends. An annular passage 21 is formed between the cylindrical side wall of the separator tube 20 and the side wall of the cylinder 2. The annular passage 21 is communicated with the cylinder upper chamber 2 </ b> A by a passage 22 provided in a side wall near the upper end portion of the cylinder 2. A branch pipe 23 having an opening communicating with the annular passage 21 is erected at a lower portion of the side wall of the separator tube 20. An opening 41 described later is provided on the side wall of the base shell 3. A damping force generating mechanism 25 is attached to the side wall of the base shell 3 so as to face the branch pipe 23 and the opening 41. In addition, the opening formed in the side wall of the separator tube 20 does not stand the branch pipe 23, that is, only the opening may be sufficient.

  The damping force generating mechanism 25 controls the pilot type (back pressure type) main valve 27 and the valve opening pressure of the main valve 27 in a cylindrical case 26 attached so as to cover the opening 41 of the base shell 3. A pilot valve 28 which is a solenoid-driven pressure control valve is provided. Further, on the downstream side of the pilot valve 28, a fail valve 29 that operates at the time of failure is provided. The main valve 27, the pilot valve 28 and the file valve 29 constitute a damping valve. A passage member 30 is connected to the branch pipe 23, and the working fluid introduced from the branch pipe 23 through the passage member 30 flows into the chamber 35 in the case 26 through the main valve 27, the pilot valve 28 and the fail valve 29. The hydraulic fluid in the chamber 35 flows to the reservoir 4 through the opening 33 of the bottom 26 </ b> A of the case 26 and the opening 41 of the base shell 3.

  At this time, before the main valve 27 is opened, the flow of hydraulic fluid is controlled by the pilot valve 28 to generate a damping force. When the main valve 27 is opened, the damping force is mainly generated by the main valve 27. . Further, part of the hydraulic fluid upstream of the pilot valve 28 is introduced into the back pressure chamber 32 at the back of the main valve 27, and the internal pressure acts in the valve closing direction of the main valve 27. Here, it is possible to adjust the damping force by adjusting the control pressure of the pilot valve 28 with the current supplied to the coil 40 of the solenoid via a lead wire (not shown). The internal pressure of the chamber 32 changes and the valve opening pressure and the opening degree of the main valve 27 can be adjusted. The fail valve 29 is closed when the coil 40 is de-energized, and restricts the flow of hydraulic fluid in place of the pilot valve 27 that is normally open, thereby preventing an excessive decrease in damping force. And maintain a moderate damping force.

  The case 26 is formed in a bottomed cylindrical shape, and an opening 33 is formed on the bottom portion 26A of the separator tube 20 having a diameter larger than that of the branch pipe 23 and arranged substantially coaxially with respect to the branch pipe 23. The The outer side of the bottom of the case 26 is curved along the outer peripheral surface of the base shell 3, and is fixed to the base shell 3 by fixing means such as welding. In the case 26, a passage member 30, a main body 36 provided with a main valve 27, a pilot pin 37 forming a pilot passage, and a pilot body 38 provided with a pilot bubble 28 are inserted in this order from the bottom side. The component is fixed to the opening 33 of the bottom portion 26 </ b> A of the case 26 by the solenoid assembly 39 that drives the pilot valve 28 being fixed to the case 26 by the nut 40.

  The passage member 30 has a cylindrical portion 30A (see FIG. 2) and a flange portion 30B (see FIG. 2) formed at one end of the cylindrical portion 30A. The passage member 30 is fixed by the cylindrical portion 30A being liquid-tightly fitted into the branch pipe 23 of the separator tube 20 and the flange portion 30B being sandwiched between the bottom portion 26A of the case 26 and the main body 36. The Thereby, the annular passage 21 is connected to the main valve 27, the pilot valve 28, and the fail valve 29 via the passage in the cylindrical portion 30 </ b> A of the passage member 30. A plurality of notches 34 extending from the opening 33 toward the case side wall are formed in the inner portion of the bottom portion 26 </ b> A of the case 26. The chamber 35 in the case 26 is communicated with the reservoir 4 through each notch 34, the opening 33, and the opening 41 formed in the side wall of the base shell 3.

With reference to FIG. 2 and FIG. 3, the opening 41 formed in the side wall of the base shell 3 mentioned above is demonstrated. FIG. 2 is an enlarged view of the main part in FIG. 1, and shows only the cylinder 2, the base shell 3, the reservoir 4, the case 26, and the passage member 30. FIG. 3 is a front view of the opening 41 formed in the side wall of the base shell 3. 3 indicates a circle formed by the outer periphery of the cylindrical portion 30A of the passage member 30. 3 indicates a circle formed by the opening 33 formed in the bottom 26A of the case 26. Further, C0 in FIG. 3 indicates a typical opening in a shock absorber with a baffle plate.
As in the description with reference to FIG. 1, the vertical direction in FIGS. 2 and 3 is referred to as the vertical direction as it is.

  As shown in FIG. 3, the opening 41 has a central angle in which a rough shape in a front view, that is, a rough shape of a figure projected on a uniaxial plane of the base shell 3 is larger than 90 ° and smaller than 180 °. It is formed into a fan shape. The opening 41 is arranged so that the fan shape formed by the opening 41 (hereinafter simply referred to as “fan shape”) is upside down, that is, the fan-shaped arc portion 42 is on the lower side. The opening 41 is formed with an R portion 45 at the intersection of the sectoral straight portion 43 and the straight portion 44. The radius of the R portion 45 is set substantially equal to the radius of the circle C30 formed by the passage member 30. In the opening 41, R portions 46 and 47 are also formed at the intersections between the fan-shaped arc portion 42 and the straight portions 43 and 44.

  The opening 41 is disposed so as to be biased downward with respect to the passage member 30. That is, the opening 41 is arranged such that the upper end position P41 is located below the upper end position P0 of the typical opening C0. Further, the opening 41 is disposed such that the upper end position P41 is located below the upper end position P33 of the opening 33 (C33) formed in the bottom 26A of the case 26. Further, the opening 41 is located with respect to the passage member 30 such that the distance between the upper portion of the cylindrical portion 30A of the passage member 30 is shorter than the distance between the lower portion of the cylindrical portion 30A of the passage member 30. Arranged, that is, close to the upper portion of the cylindrical portion 30A of the passage member 30.

In other words, the opening 41 has a gap (cross-sectional area in a front view) between the fan-shaped arc portion 42 and the lower portion of the cylindrical portion 30 </ b> A of the passage member 30. The reservoir 4 is sufficiently large with respect to a gap (cross-sectional area in front view) formed between the upper portion of the cylindrical portion 30A of the cylindrical portion 30A, that is, from the chamber 35 (see FIG. 1) defined by the case 26. It is sufficiently large so that the flow of the hydraulic fluid toward the lower side (base valve 10 side) is directed to the passage member 30.
As shown in FIG. 3, the opening 41 is disposed with respect to the case 26 and the passage member 30 so that the axes of the case 26 and the passage member 30 are orthogonal to the center of the sector-shaped string 48.

Next, the operation of the first embodiment will be described.
The shock absorber 1 has two members that can move relative to each other between the spring (vehicle body side) and the unsprung (wheel side) of the suspension device of the vehicle with the piston rod 6 side upward and the base valve 10 side downward. The coil 31 of the solenoid assembly 39 is connected to the controller.

  During the extension stroke of the piston rod 6, the check valve 13 of the piston 5 is closed by the movement of the piston 5 in the cylinder 2, and the cylinder upper chamber 2 </ b> A is pressurized before the disk valve 14 is opened. The liquid flows from the branch pipe 23 of the separator tube 20 to the passage member 30 of the damping force generation mechanism 25 via the passage 22 and the annular passage 21. The hydraulic fluid that has flowed into the passage member 30 flows into the chamber 35 defined by the case 26 via the main valve 27, the pilot valve 28, and the fail valve 29, and further, a notch 34 in the bottom 26 </ b> A of the case 26, and It flows into the reservoir 4 through an opening 41 formed in the side wall of the base shell 3.

  At this time, the hydraulic fluid corresponding to the movement of the piston 5 opens the check valve 17 of the base valve 10 and flows from the reservoir 4 into the cylinder lower chamber 2B. When the pressure in the cylinder upper chamber 2A reaches the valve opening pressure of the disk valve 14 of the piston 5, the disk valve 14 opens and the pressure in the cylinder upper chamber 2A is relieved to the cylinder lower chamber 2B. An excessive pressure rise in the upper chamber 2A is avoided.

  On the other hand, during the contraction stroke of the piston rod 6, the check valve 13 of the piston 5 is opened by the movement of the piston 5 in the cylinder 2, and the check valve 17 of the passage 15 of the base valve 10 is closed. Before the valve 18 is opened, the hydraulic fluid in the piston lower chamber 2B flows into the cylinder upper chamber 2A, and the hydraulic fluid as the piston rod 6 enters the cylinder 2 extends from the cylinder upper chamber 2A as described above. It flows into the reservoir 4 through the same route as that during the stroke. When the pressure in the cylinder lower chamber 2B reaches the valve opening pressure of the disk valve 18 of the base valve 10, the disk valve 18 is opened, and the pressure in the cylinder lower chamber 2B is relieved to the reservoir 4, thereby Prevent excessive pressure rise of 2B.

  Thus, during the expansion / contraction stroke of the piston rod 6, the damping force generation mechanism 25 generates a damping force by the pilot valve 28 before the main valve 27 is opened (piston speed low speed region), and the main valve 27 After opening the valve (on the high speed side of the piston speed), a damping force corresponding to the opening of the main valve 27 is generated. Then, it is possible to adjust the damping force by adjusting the control pressure of the pilot valve 28 by the energization current to the coil 31. As a result, the internal pressure of the back pressure chamber 32 changes and the main valve 27 is opened. The valve pressure and opening can be adjusted. Further, when the energization of the coil 31 is interrupted due to the stop of the vehicle due to a signal waiting or the like, or in the event of a failure, the fail valve 29 is closed. As a result, the flow of the hydraulic fluid can be limited in place of the pilot valve 27 that is normally open, and an excessive decrease in the damping force can be prevented to maintain an appropriate damping force.

According to the first embodiment, the opening 41 formed in the side wall of the base shell 3 is disposed so as to be biased downward with respect to the passage member 30, and between the opening 41 and the upper portion of the cylindrical portion 30 </ b> A of the passage member 30. The gap (cross-sectional area in front view) formed in is made narrower than the gap (cross-sectional area in front view) between the opening 41 and the lower portion of the cylindrical portion 30A of the passage member 30.
Thereby, during the expansion / contraction stroke of the piston rod 6, the working fluid flowing from the chamber 35 defined by the case 26 to the reservoir 4 side is allowed to flow only downward (base valve 10 side). It is possible to suppress the flow in the direction. As a result, the jet flow (hydraulic fluid) from the damping force generating mechanism 25 (see FIG. 1) can be forced to flow downward, and the gas in the reservoir 4 is mixed as bubbles in the hydraulic fluid or the hydraulic fluid. It is possible to prevent melting and cavitation and aeration.
Further, by making the upper end position P41 of the opening 41 lower than the upper end position P33 of the opening 33 formed in the bottom 26A of the case 26, the working fluid flowing from the upper part of the opening 33 to the reservoir 4 side can be obtained. Since it is configured to hit the side wall of the base shell 3 in the vicinity of the upper end position P41 of the opening 41, it is possible to more effectively prevent the jet flow (working fluid) from the damping force generation mechanism 25 from flowing upward.
In addition, since it is not necessary to provide a baffle plate in the reservoir 4, the addition of the baffle plate does not increase the part cost and the number of assembling steps, and in addition, the problem of poor assembly can be solved. And since the opening 41 can be processed only by remodeling the existing press die, it can be implemented easily.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to the accompanying drawings. In addition, about the component which is the same as that of the buffer 1 which concerns on 1st Embodiment mentioned above, or an equivalent component, the same name and code | symbol are provided, and detailed description is abbreviate | omitted. 5 indicates a circle formed by the outer periphery of the branch pipe 23 formed on the side wall of the separator tube 20. 5 indicates a ridge line between the outer peripheral surface of the base shell 3 and the outer peripheral surface of the case 26.
As shown in FIGS. 4 to 6, in the second embodiment, an opening 51 having a shape different from the opening 41 of the first embodiment is formed on the side wall of the base shell 3. Further, a burring portion 52 formed by raising a part (upper part) around the opening 51 inward (left side in FIG. 4) with respect to the side wall of the base shell 3 is provided on the side wall of the base shell 3.

  As shown in FIG. 4, the burring portion 52 extends from the upper portion of the bottom portion 26 </ b> A of the case 26 toward the distal end portion of the cylindrical portion 30 </ b> A of the passage member 30, in other words, the branch pipe 23 formed on the side wall of the separator tube 20. It is formed to extend. Further, the burring portion 52 is formed such that the inner peripheral edge of the tip, that is, the upper portion 53 (see FIGS. 5 and 6) of the opening 51 is in contact with the outer periphery C23 (see FIG. 5) of the branch pipe 23. Thereby, the burring portion 52 forms a wall surrounding the upper portion of the cylindrical portion 30 </ b> A of the passage member 30. As shown in FIG. 5, the lower portion 54 of the opening 51 is formed in the same shape as a typical opening C0 in a shock absorber provided with a baffle plate, that is, formed in an arc shape in front view, and the upper portion 53 of the opening 51. And the lower part 54 are smoothly continuous.

According to the second embodiment, the burring portion 52 is formed on the side wall of the base shell 3 by raising an upper portion (a part) around the opening 51 inward with respect to the side wall of the base shell 3, 52 and the upper portion of the cylindrical portion 30A of the passage member 30 are narrowed, and the chamber 35 defined by the case 26 during the expansion / contraction stroke of the piston rod 6 (see FIG. 1). ) To the reservoir 4 side, the flow of the hydraulic fluid along the upper portion of the cylindrical portion 30A of the passage member 30 can be guided downward (base valve 10 side) by the burring portion 52. .
Thereby, it is possible to forcibly flow (guide) the jet flow (hydraulic fluid) from the damping force generation mechanism 25 (see FIG. 1), and the gas in the reservoir 4 is bubbled into the hydraulic fluid. It is possible to prevent mixing or dissolution in the working fluid, and suppress the occurrence of cavitation and aeration.
In addition, since it is not necessary to provide a baffle plate in the reservoir 4, the addition of the baffle plate does not increase the part cost and the number of assembling steps, and in addition, the problem of poor assembly can be solved. And since the opening 51 and the burring part 52 can be processed only by remodeling the existing press type | mold, it can implement easily.

1 shock absorber, 2 cylinder, 3 base shell, 4 reservoir, 5 piston, 5 piston rod, 20 separator tube, 21 annular passage, 25 damping force generating mechanism, 26 case, 30 passage member, 41 opening

Claims (3)

A shock absorber mounted between two relatively movable members,
A cylinder in which a working fluid is sealed, a piston fitted in the cylinder, a piston rod having one end connected to the piston and the other end extending outside the cylinder, and an outer periphery of the cylinder A base shell formed between the cylinder and the base shell and filled with a working fluid and gas, and fitted into the outer periphery of the cylinder to form an annular passage between the cylinder and the cylinder. A separator tube, an opening provided in a side wall of the separator tube and communicating with the annular passage, a damping force generation mechanism that generates a damping force by controlling a flow of a working fluid generated by movement of the piston, and the base shell A cylindrical case that is attached to the side wall of the housing and accommodates the damping force generation mechanism, and penetrates into an opening formed in the side wall of the base shell Is provided with a passage member for connecting the opening of the separator tube and the damping force generating mechanism,
The shock absorber according to claim 1, wherein the opening formed in the side wall of the base shell is arranged to be biased downward with respect to the passage member.   A gap formed between the opening formed in the side wall of the base shell and the upper portion of the passage member is defined as a gap between the opening formed in the side wall of the base shell and the lower portion of the passage member. The shock absorber according to claim 1, wherein the shock absorber is narrower.   A burring portion raised to the inside with respect to the side wall of the base shell is formed at a position around the opening formed in the side wall of the base shell and facing the upper portion of the passage member. The shock absorber according to claim 1 or 2.

Images