JP4868130B2 - Hydraulic shock absorber - Google Patents

Description

  The present invention relates to a hydraulic shock absorber provided with a check valve as a valve element of a damping force generating mechanism.

  A hydraulic shock absorber mounted on a suspension system of a vehicle such as an automobile has a damping that allows the damping force characteristics to be adjusted appropriately in order to improve riding comfort and handling stability according to the road surface condition, running condition, etc. There is a force adjustable hydraulic shock absorber.

  In general, a damping force adjusting type hydraulic shock absorber is slidably fitted with a piston connected to a piston rod in a cylinder filled with an oil liquid so as to slidably define the inside of the cylinder in two chambers. A main oil liquid passage and a bypass passage for communicating the two chambers are provided, a damping force generating mechanism including an orifice and a disk valve is provided in the main oil liquid passage, and a damping force adjusting valve for adjusting the passage area is provided in the bypass passage. It has a configuration provided.

  With this configuration, the damping passage is opened by the damping force adjusting valve to reduce the fluid flow resistance between the two chambers in the cylinder to reduce the damping force, and the bypass passage is closed to reduce the passage resistance between the two chambers. The damping force is increased by increasing. Thus, the damping force characteristic can be adjusted as appropriate by opening and closing the damping force adjustment valve.

  However, in the case where the damping force is adjusted only by the passage area of the bypass passage as described above, the damping force characteristics greatly change because the damping force depends on the orifice restriction of the oil passage in the low speed region of the piston speed. However, in the middle and high speed range of the piston speed, the damping force depends on the opening of the damping force generation mechanism (disk valve, etc.) of the main oil passage, so that the damping force characteristic cannot be changed greatly. .

Therefore, as described in Patent Document 1, for example, a back pressure chamber (pilot chamber) is formed at the back of the disk valve as a damping force generation mechanism for the main oil passage, and this back pressure chamber is connected to the fixed orifice through a fixed orifice. A pilot type damping force adjusting valve is proposed that communicates with the cylinder chamber upstream of the disc valve and communicates with the cylinder chamber downstream of the disc valve via a pilot control valve. .
JP 2003-166585 A

  According to this damping force adjusting type hydraulic shock absorber, the flow path between the two chambers in the cylinder is directly adjusted by the pilot control valve, and the pressure in the back pressure chamber is changed by the pressure loss generated by the pilot control valve. The valve opening pressure of the valve can be changed. As a result, both the orifice characteristic (the damping force is approximately proportional to the square of the piston speed) and the valve characteristic (the damping force is approximately proportional to the piston speed) can be adjusted, and the adjustment range of the damping force characteristic is widened. can do.

  However, when the pilot type damping force adjusting valves are provided on both the expansion side and the contraction side as in the damping force adjustment type hydraulic shock absorber described in Patent Document 1, the oil-liquid passages independent on the expansion side and the contraction side are provided. Therefore, the structure becomes complicated, the space for disposing each valve element of the damping force generating mechanism is greatly limited, and it is very difficult to reduce the size.

  The present invention has been made in view of the above points, simplifying the structure of a check valve used as a valve element of a damping force generating mechanism, improving assembly, downsizing, and manufacturing cost. It is an object of the present invention to provide a hydraulic shock absorber that can achieve reduction.

In order to solve the above-mentioned problem, the invention according to claim 1 includes a cylinder in which oil is sealed, a piston that is slidably fitted in the cylinder and defines the inside of the cylinder in two chambers , A piston rod having one end connected to the piston and the other end extending to the outside of the cylinder, an oil passage that directly communicates between the two chambers, and a damping force by controlling the flow of oil in the oil passage in the hydraulic shock absorber and a damping force generating mechanism including a main valve for generating,
The damping force generating mechanism includes a back pressure chamber that is formed on a back portion of the main valve and applies a back pressure to the main valve, an actuator having a plunger that moves by energizing the coil, and a plunger chamber that houses the plunger. And a valve chamber provided with a seat portion adjacent to the plunger chamber, and an internal pressure of the back pressure chamber that is connected to the plunger and passes through the sliding portion through the valve chamber and can be seated and detached from the seat portion. A poppet valve, and an oil passage having a check valve for letting the oil leaked from the valve chamber to the plunger chamber through the sliding portion into one chamber in the cylinder,
The oil passage having the check valve includes a valve bore having a circular bottom surface, a first oil passage having one end opened on the bottom surface of the valve bore, and a second oil passage having one end opened on the top surface facing the bottom surface of the valve bore. And a bottomed cylindrical valve member made of rubber sandwiched between the bottom surface and the top surface of the valve bore while the bottom portion abuts on the bottom surface of the valve bore and is fitted into the valve bore. The other end opening of the oil passage communicates with the cylinder, the other end opening of the first oil passage communicates with the plunger chamber, and the plunger is provided with a balance passage that balances the pressures at both ends. A communication passage is provided at the bottom of the member, and the first oil passage opens toward a position different from the communication passage on the bottom surface of the valve bore.
A hydraulic shock absorber according to a second aspect of the present invention is the hydraulic shock absorber according to the first aspect, wherein a gap is provided between the bottom surface of the valve bore and the bottom portion of the valve member, and the communication passage is formed at the bottom portion of the valve member. An annular seat portion that abuts the bottom surface of the valve bore protrudes from the periphery, and the first oil passage opens toward the outside of the seat portion.
A hydraulic shock absorber according to a third aspect of the present invention is characterized in that, in the configuration of the first or second aspect, a reinforcing member that restricts deformation of the bottom portion is provided at the bottom portion of the valve member.

According to the hydraulic shock absorber according to the first aspect of the present invention, the check valve is elastically deformed at the bottom of the valve member by the pressure of the oil liquid with respect to the flow of the oil liquid from the first oil path to the second oil path. The first oil passage and the second oil passage communicate with each other through the passage at the bottom of the valve member, and the flow is allowed. Further, with respect to the flow of the oil liquid from the second oil path to the first oil path, the bottom of the valve member abuts against the bottom surface of the valve bore by the pressure of the oil liquid to close the opening of the first passage, Block that flow.
According to the hydraulic shock absorber according to the invention of claim 2, by providing a gap between the bottom surface of the valve bore and the bottom portion of the valve member, the pressure receiving area with respect to the first oil passage at the bottom portion of the valve member increases. The check valve can be opened smoothly. Moreover, the sealing performance when the valve is closed can be improved by the seat portion.
According to the hydraulic shock absorber according to the invention of claim 3, since the deformation amount of the valve member at the time of the on-off valve can be limited by the reinforcing member, the durability of the valve member can be enhanced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, a hydraulic shock absorber 1 according to this embodiment is a single cylinder type hydraulic shock absorber, and has a rod guide (not shown) and an oil seal (see FIG. A free piston (not shown) is slidably fitted on the bottom side in the cylinder 2. The cylinder 2 is defined by a free piston in a gas chamber on the bottom side and an oil chamber on the other end side. The gas chamber is filled with high-pressure gas, and the oil chamber is filled with oil.

  A piston 3 is slidably fitted in the oil chamber of the cylinder 2, and the piston 3 defines an oil chamber into two chambers, a cylinder upper chamber 2A and a cylinder lower chamber 2B. The piston 3 has a tip end of a piston bolt 4 inserted therein and fixed by a nut 5. A substantially bottomed cylindrical case 6 is attached to the base end portion (upper part in the drawing) of the piston bolt 4. One end (lower side in the figure) of the piston rod 7 is connected to the bottom of the case 6, and the other end of the piston rod 7 is slidably and liquid-tightly inserted into the rod guide and the oil seal. It extends to the outside of the cylinder 2.

  The piston 3 is provided with an extension side oil passage 8 that opens to the cylinder upper chamber 2A side and a contraction side oil passage 9 that opens to the cylinder lower chamber 2B side. The lower end of the piston 3 is provided with an extension side damping valve 10 (a damping force generating mechanism) that controls the flow of the oil in the extension side oil passage 8, and the oil of the contraction side oil passage 9 is provided at the upper end. A compression-side damping valve 11 (a damping force generation mechanism) that controls the flow of the liquid is provided.

  The extension-side damping valve 10 is formed by an extension-side main valve 13 (disc valve) seated on a seat portion 12 formed on the lower end surface of the piston 3 and a valve member 14 attached to the piston bolt 4 by a nut 5. An extension-side back pressure chamber 15 formed at the back of the valve 13 is provided.

  A plurality of disks are stacked on the extension side main valve 13, and an extension side orifice passage 16 and an extension side that always connect the extension side oil passage 8 and the extension side back pressure chamber 15 by notches and openings provided in these discs. A contraction-side check valve 17 that allows only fluid to flow from the back pressure chamber 15 side to the extension-side oil passage 8 is formed. The internal pressure of the extension-side back pressure chamber 15 acts on the extension-side main valve 13 in the valve closing direction.

  The compression side damping valve 11 is a compression side main valve 19 (disc valve) seated on a seat portion 18 formed on the upper end surface of the piston 3 and a contraction formed on the back of the main valve 19 by the end of the piston bolt 4. The side back pressure chamber 20 is provided.

  Similar to the above-described expansion side main valve 13, a plurality of disks having openings, cutouts, and the like are stacked on the contraction side main valve 19, and the contraction side oil passage 9 and the contraction side back pressure chamber 20 always communicate with each other. An extension check valve 22 that allows only the flow of oil from the side orifice passage 21 and the compression side back pressure chamber 20 to the compression side oil passage 9 is formed, and the compression side back pressure chamber 20 The internal pressure acts on the contraction side main valve 19 in the valve closing direction.

  A valve chamber 23 is formed inside the piston bolt 4, and the valve chamber 23 is connected to the extension-side back pressure chamber 15 via an axial oil passage 24 extending along the axis of the tip of the piston bolt 4. It communicates with the contraction-side back pressure chamber 20 through a radial oil passage 25 that extends in a radially inclined manner. A poppet valve 26 is inserted into the valve chamber 23, and the poppet valve 26 is separated from and seated on a seat portion 27 formed in the valve chamber 23, whereby the axial oil passage 24 and the radial oil passage 25 are separated. The channel between them is opened and closed.

  The poppet valve 26 is connected to a plunger 29 of a solenoid actuator 28 provided in the case 6, and the opening and closing of the poppet valve 26 can be controlled by an energizing current to the coil 30 of the solenoid actuator 28. A lead wire 31 for energizing the coil 30 is inserted through the hollow piston rod 7 and extended to the outside. The plunger 29 is urged by a valve spring 32 in a direction to close the space between the axial oil passage 24 and the radial oil passage 25, and an adjustment screw 33 for adjusting the set load of the valve spring 32 is provided. Is provided. The plunger 29 is penetrated in the axial direction with a balance passage 34 for balancing the hydraulic pressure acting at both ends thereof.

  An oil passage 35 (second oil passage) is provided at the bottom of the case 6, and an oil passage communicating with the oil passage 35 is connected to the base 36 constituting the magnetic passage of the solenoid actuator 28 fitted in the case 6. 37 (first oil passage) is provided, and through these oil passages 35 and 36, the plunger chamber 29A for accommodating the plunger 29 and the cylinder upper chamber 2A are communicated. A check valve 38 is provided between the oil passage 35 and the oil passage 36. The check valve 38 prevents the flow of oil from the cylinder upper chamber 2A side to the plunger chamber 29A side, and restricts the flow of oil from the plunger chamber 29A side to the cylinder upper chamber 2A side through the orifice communication path 39 (communication path). ).

Next, the structure of the check valve 38 will be described with reference to FIGS.
As shown in FIG. 2, a valve bore 40 having a circular bottom surface is formed on the end surface of the base 36 that contacts the bottom surface of the case 6 at a portion facing the oil passage 35 of the case 6. One end of the oil passage 37 opens at the bottom surface of the valve bore 40, and one end of the oil passage 35 opens at the upper surface (the bottom surface of the case 6) facing the bottom surface of the valve bore 40. Are communicated with each other via a valve bore 40. The oil passage 37 of the base 36 is opened at a position offset by a predetermined distance from the center of the bottom of the valve bore 40. The valve bore 40 is fitted with a bottomed cylindrical valve member 41 made of an elastic body such as rubber, and an orifice communication passage 39 is provided at the center of the bottom of the valve member 41. The bottom of the valve member 41 is in close contact with the bottom surface of the valve bore 40 to close the opening of the oil passage 37, the outer peripheral surface of the cylindrical portion is in liquid-tight contact with the inner peripheral surface of the valve bore 40, and the opening The end on the side is in liquid-tight contact with the bottom surface of the case 6, that is, the top surface of the valve bore 40. Thereby, the cylindrical portion of the valve member 41 is held between the bottom surface and the top surface of the valve bore 40.

  The valve member 41 has a bottom at the bottom of the valve bore 40 due to the fluid pressure of the oil liquid flowing from the oil passage 35 side (cylinder upper chamber 2A side) to the oil passage 37 side (plunger chamber 29A side). 3 to close the opening of the oil passage 37 to block the flow, and the flow of the oil liquid from the oil passage 37 side to the oil passage 35 side is shown in FIG. As shown in the figure, the bottom part is elastically deformed and the central part is raised, thereby opening the oil passage 37 and allowing the flow through the orifice communication passage 39.

Next, the operation of the present embodiment configured as described above will be described.
During the extension stroke of the piston rod 7, the oil liquid on the cylinder upper chamber 2 </ b> A side is, before the extension main valve 13 is opened, the extension side oil passage 8, the extension side orifice passage 16, the extension side back pressure chamber 15, and the shaft. It flows to the cylinder lower chamber 2B through the directional oil passage 24, the valve chamber 23, the radial oil passage 25, the contraction side back pressure chamber 20, the extension side check valve 22 and the contraction side oil passage 9. When the pressure of the oil liquid on the cylinder upper chamber 2A side reaches the valve opening pressure of the extension main valve 13, the extension main valve 13 opens, and the oil liquid directly passes from the extension side oil passage 8 to the cylinder lower chamber 2B. Flows. Note that the change in volume in the cylinder 2 is compensated by compressing the high-pressure gas in the gas chamber by moving the free piston by the amount that the piston rod 7 has entered the cylinder 2.

  Then, by adjusting the energization current to the coil 30 of the solenoid actuator 28, the opening and closing of the poppet valve 26 is controlled to directly control the flow of the oil liquid between the axial oil passage 24 and the radial oil passage 25. Thus, the damping force can be adjusted. Thereby, since the internal pressure of the extension side back pressure chamber 15 is adjusted at the same time, the valve opening pressure of the extension side main valve 13 can be controlled.

  On the other hand, during the contraction stroke of the piston rod 7, the oil liquid on the cylinder lower chamber 2 </ b> B side is compressed before the contraction main valve 19 is opened. , Through the radial oil passage 25, the valve chamber 23, the axial oil passage 24, the extension-side back pressure chamber 15, the contraction-side check valve 17 and the extension-side oil passage 8, and flow into the cylinder upper chamber 2 </ b> A. When the pressure of the oil liquid on the cylinder lower chamber 2B side reaches the valve opening pressure of the contraction side main valve 19, the contraction side main valve 19 is opened, and the oil liquid directly passes from the contraction side oil passage 9 to the cylinder upper chamber 2A. Flows. The piston rod 7 is retreated from the inside of the cylinder 2 so that the free piston moves and the high-pressure gas in the gas chamber expands to compensate for the volume change in the cylinder 2.

  Then, as in the extension stroke, the opening and closing of the poppet valve 26 is controlled by adjusting the energization current to the coil 30 of the solenoid actuator 28, and the oil liquid between the radial oil passage 25 and the axial oil passage 24 is controlled. The flow can be directly controlled to adjust the damping force. Thereby, since the internal pressure of the compression side back pressure chamber 20 is adjusted at the same time, the valve opening pressure of the compression side main valve 19 can be controlled.

  In this way, the damping force on the expansion side and the contraction side can be adjusted by the common poppet valve 26, and at the same time, the expansion side and the contraction side main valve 13 by the internal pressure of the expansion side and the contraction side back pressure chambers 15, 20. , 19 can be adjusted, so that the adjustment range of the damping force characteristic can be widened. At this time, since the poppet valve 26 has different pressure receiving surfaces during the expansion stroke and during the contraction stroke, the damping force characteristics of the expansion stroke and the contraction stroke can be set as desired by appropriately setting these pressure receiving areas. Can be set to characteristics.

  At the downstream side of the poppet valve 26, the oil liquid flows through the compression side back pressure chamber 20, the expansion side check valve 22 and the compression side oil passage 9 of the compression side damping valve 11 during the expansion stroke. On the downstream side of the poppet valve 26, the oil liquid flows through the expansion-side back pressure chamber 15, the contraction-side check valve 17 and the expansion-side oil passage 8 of the expansion-side damping valve 10. Since the liquid flow path is partially shared, the structure can be simplified, the manufacturing cost can be reduced, and the durability and reliability can be increased. Further, with this simplification, the axial dimension of the piston can be reduced, so that a sufficient stroke can be secured as a hydraulic shock absorber.

  Further, during the extension stroke of the piston rod 7, the pressure of the oil on the cylinder upper chamber 2A side acts on the oil passage 35 of the case 6, but the check valve 38 is closed and the pressure is applied to the plunger chamber 29A. Stop acting. Thereby, it is possible to prevent the pressure in the plunger chamber 29 </ b> A from rising and prevent the force in the valve closing direction from acting on the poppet valve 26. Further, during the contraction stroke of the piston rod 7, the oil pressure in the contraction-side back pressure chamber 20 leaks from the sliding portion around the poppet valve 26 to the plunger chamber 29A and tries to increase the pressure in the plunger chamber 29A. However, when the check valve 38 is opened, the pressure can be released to the cylinder upper chamber 2 </ b> A side through the oil passages 35 and 37 and the orifice communication passage 39. Thereby, it is possible to prevent the pressure in the plunger chamber 29 </ b> A from rising and prevent the force in the valve closing direction from acting on the poppet valve 26. As the check valve 38 opens and closes in this way, an increase in the pressure in the plunger chamber 29A can be prevented, and a stable damping force can be generated.

  Further, even when air bubbles are generated in the plunger chamber 29A during manufacturing or maintenance of the hydraulic shock absorber 1, the check valve 38 is activated by the pressure in the plunger chamber 29A being increased to some extent by the operation of the hydraulic shock absorber 1. Since it opens, the bubbles in the plunger chamber 29A can be discharged through the oil passages 35 and 37 and the orifice communication passage 39, and aeration can be prevented and a stable damping force can be generated.

  Here, the check valve 38 has a simple structure, a small number of parts, excellent assemblability, low manufacturing cost, and low cost compared to a conventional check valve including a disc valve, a valve seat, a spring, and the like. Since it is compact, it turns out that it is a thing suitable for the non-return valve which comprises the valve element of a hydraulic shock absorber.

  Next, second and third embodiments of the present invention will be described with reference to FIGS. In the following description, the same parts as those in the first embodiment are denoted by the same reference numerals, and only different parts will be described in detail.

  As shown in FIG. 4, in the check valve 42 of the hydraulic shock absorber according to the second embodiment, a gap is provided between the bottom portion of the valve member 41 and the bottom surface of the valve bore 40, and the orifice connection at the bottom portion of the valve member 41 is provided. An annular sheet portion 43 protrudes around the passage 39. The front end portion of the seat portion 43 is in close contact with the bottom surface of the valve bore 40, and the oil passage 37 of the base 36 is opened toward the outer peripheral side of the seat portion 43.

  With this configuration, the pressure receiving area of the valve member 41 increases with respect to the oil pressure on the oil passage 37 side of the base 36, so that the valve opening pressure decreases and the check valve 42 opens smoothly. Can be valved. Further, the sealing performance when the valve is closed can be improved by the annular seat portion 43.

  As shown in FIG. 5, in the check valve 44 of the hydraulic shock absorber according to the third embodiment, a metal disc-shaped reinforcing member 45 having moderate elasticity is vulcanized inside the bottom of the valve member 41. It is fixed by bonding or the like. Thereby, the deformation amount of the valve member 41 at the time of an on-off valve can be restrict | limited, and durability of the valve member 41 can be improved. In addition, you may provide the reinforcement member 45 in the valve member 41 of the said 2nd Embodiment.

It is a longitudinal cross-sectional view of the principal part of the hydraulic shock absorber according to the first embodiment of the present invention. It is a longitudinal cross-sectional view which expands and shows the check valve of the hydraulic shock absorber shown in FIG. It is a longitudinal cross-sectional view which shows the state which the check valve shown in FIG. 2 opened It is a longitudinal cross-sectional view which expands and shows the check valve of the hydraulic buffer which concerns on 2nd Embodiment of this invention. In the longitudinal cross-sectional view which expands and shows the check valve of the hydraulic buffer which concerns on 3rd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Hydraulic buffer, 2 cylinder, 3 piston, 7 piston rod, 10 Extension side damping valve (damping force generation mechanism), 11 Contraction side damping valve (damping force generation mechanism), 38 Check valve, 35 Oil path (2nd Oil passage), 37 oil passage (first oil passage), 39 orifice communication passage (communication passage), 40 valve bore, 41 valve member

Claims (3)

A cylinder filled with oil, a piston slidably fitted in the cylinder and defining the inside of the cylinder in two chambers , one end connected to the piston, and the other end extending to the outside of the cylinder. hydraulic with the issued piston rod, an oil passage for directly communicated between the two chambers, a damping force generating mechanism including a main valve that generates and controls the flow damping force of the hydraulic fluid in the oil passage, the In the shock absorber,
The damping force generating mechanism includes a back pressure chamber that is formed on a back portion of the main valve and applies a back pressure to the main valve, an actuator having a plunger that moves by energizing the coil, and a plunger chamber that houses the plunger. And a valve chamber provided with a seat portion adjacent to the plunger chamber, and an internal pressure of the back pressure chamber that is connected to the plunger and passes through the sliding portion through the valve chamber and can be seated and detached from the seat portion. A poppet valve, and an oil passage having a check valve for letting the oil leaked from the valve chamber to the plunger chamber through the sliding portion into one chamber in the cylinder,
The oil passage having the check valve includes a valve bore having a circular bottom surface, a first oil passage having one end opened on the bottom surface of the valve bore, and a second oil passage having one end opened on the top surface facing the bottom surface of the valve bore. And a bottomed cylindrical valve member made of rubber sandwiched between the bottom surface and the top surface of the valve bore while the bottom portion abuts on the bottom surface of the valve bore and is fitted into the valve bore. The other end opening of the oil passage communicates with the cylinder, the other end opening of the first oil passage communicates with the plunger chamber, and the plunger is provided with a balance passage that balances the pressures at both ends. The hydraulic shock absorber according to claim 1, wherein a communication passage is provided at a bottom portion of the member, and the first oil passage opens toward a position different from the communication passage on a bottom surface of the valve bore. A gap is provided between the bottom surface of the valve bore and the bottom portion of the valve member, and an annular seat portion that contacts the bottom surface of the valve bore protrudes around the communication path at the bottom portion of the valve member, The hydraulic shock absorber according to claim 1, wherein the oil passage opens toward the outside of the seat portion.   The hydraulic shock absorber according to claim 1, wherein a reinforcing member that restricts deformation of the bottom portion is provided at a bottom portion of the valve member.

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