JP4491371B2 - Shock absorber - Google Patents

Description

  The present invention relates to an improvement of a shock absorber.

  Conventionally, this type of shock absorber is, for example, one that is interposed between a vehicle body side tube that constitutes a front fork and an axle side tube and is built in the front fork.

  This shock absorber is provided with a reservoir in order to compensate for the rod volume of liquid that enters or exits the cylinder that becomes excessive or insufficient in the cylinder when expanding or contracting.

  Specifically, this reservoir includes, for example, a main reservoir chamber partitioned by a valve body provided at one end of the cylinder, a sub reservoir chamber formed in a gap between the cylinder, the vehicle body side tube, and the axle side tube. It is configured with.

  Further, in the main reservoir chamber, a partition member constituted by an elastic partition body and a base body is partitioned with an air chamber and a liquid chamber communicating with the cylinder through a flow path provided in the valve body, The air chamber pressurizes the inside of the cylinder.

  In this shock absorber, even if the shock absorber expands and the pressure in the cylinder decreases, the pressure in the cylinder is maintained above a certain level by the spring action of the air chamber, and the shock absorber changes from expansion to compression. The compression side damping force is sufficiently generated.

  In addition, the pressure release passage that communicates the main reservoir chamber and the sub reservoir chamber is constituted by a through hole that communicates the sliding contact portion of the base body on the inner periphery of the housing and the outside of the housing. The pressure release flow path is closed by making the sliding contact surface of the base body face the open end of the base body.

In the case of this shock absorber, when the full stroke is made to the compression side, it is expected that the pressure in the cylinder will become a high pressure exceeding the allowable pressure. In such a case, the shock absorber is constituted by the elastic partition body and the base body. The partition member to be retreated in the axial direction with respect to the housing of the main reservoir chamber is opened, and the pressure release passage that has been closed by the base body is opened so that the liquid in the main reservoir chamber is allowed to escape to the sub-reservoir chamber. The pressure was not allowed to exceed the allowable pressure (see, for example, Patent Document 1).
JP 2004-360715 A (paragraph number 0037, FIG. 1)

  In the above-described shock absorber, it is desirable that the pressure release channel be formed only when the inside of the cylinder is at a high pressure. Since the path is closed, liquid leaks from between the housing and the base body into the sub-reservoir chamber, and it is difficult to keep the inside of the cylinder in a pressurized state as it is.

  Therefore, it is inevitably necessary to seal between the base body and the housing. With conventional shock absorbers, the number of shock absorber parts is increased, and there is a problem that precise processing is unavoidable. There was also a problem that the structure of the main reservoir chamber was complicated.

  Accordingly, the present invention has been developed to improve the above-described problems, and the object of the present invention is to reduce the number of parts of the shock absorber, facilitate processing, and simplify the structure of the main reservoir chamber. It is to make it.

To achieve the above object, the means of the present invention is a shock absorber provided with a reservoir that is interposed between a vehicle body side tube and an axle side tube and compensates for excess or deficiency of liquid in the cylinder , A cylindrical housing in which the reservoir includes a main reservoir chamber that communicates with the cylinder and a sub reservoir chamber that communicates with the main reservoir chamber via a passage, and the housing A buffer provided with a liquid chamber and an air chamber partitioned by a partition member housed therein, wherein the auxiliary reservoir chamber is formed in a space formed by the vehicle body side tube and the axle side tube on the outer peripheral side of the housing in the relief valve opens when the passage provided in the housing side which is located below the partition member, further liquid chamber internal pressure of the main reservoir chamber in the middle of the passage is equal to or more than the predetermined pressure Only, in which the relief valve is characterized in that is constituted by a valve body seated is energized the valve seat side the valve seat by the middle provided with a valve seat and biasing means of the passage.
In this case, it is preferable that the side part in the vicinity of the cylinder of the housing is formed thick and a passage is provided in the thick side part.
Similarly, the relief valve is embedded in a sphere that closes the passage from the outer side of the cylinder, an annular valve seat provided in the middle of the passage, a C-ring that urges the sphere in the valve seat direction, and a housing. It is preferable to include a pin that engages with the cut of the C ring and functions as a detent for the C ring.

According to the present invention, the relief valve that opens when the pressure in the cylinder becomes high and releases the pressure from the main reservoir chamber to the sub-reservoir chamber is provided by the sliding contact surface of the partition wall member like the conventional shock absorber. The passage that connects the chamber and the auxiliary reservoir chamber is not blocked, but it does not have a sliding contact part and does not leak liquid, so that there is no seal in the relief valve. Since the pressure can be maintained in a pressurized state, the number of parts of the shock absorber can be reduced as compared with the conventional one, and there is no harmful effect that precise processing is required, and the relief valve is independent of the partition wall member. Since it is provided, the structure of the main reservoir chamber is simplified and the processing cost is reduced.
Furthermore, since the passage is provided not on the top portion of the housing but on the side portion and below the elastic partition wall in the vicinity of the cylinder, a situation where the passage is unintentionally blocked by the elastic partition wall is avoided.

Embodiments of the present invention will be described below with reference to the drawings.
The shock absorber of the present invention is a shock absorber including a reservoir that is interposed between the vehicle body side tube 1 and the axle side tube and compensates for an excess or deficiency of liquid in the cylinder 2. A cylindrical housing 19 having a main reservoir chamber R1 communicated with the sub reservoir chamber R2 communicated with the main reservoir chamber R1 via the passage 30; A liquid chamber L and an air chamber G are defined by a partition member made of an elastic partition wall 20 accommodated in the housing 19, and the auxiliary reservoir chamber R 2 is on the outer peripheral side of the housing 19 and on the vehicle body side tube 1 and the axle side. It is formed in a space made up of tubes.
In the present invention, the relief passage is provided when the passage 30 is provided in the side portion of the housing located below the partition wall member, and further opens in the middle of the passage 30 when the liquid chamber pressure in the main reservoir chamber R1 exceeds a predetermined pressure. The valve 31 is provided, and the relief valve 31 is constituted by a valve seat 33 provided in the middle of the passage 30 and a valve body 32 that is urged toward the valve seat 33 by the urging means 34 and is seated on the valve seat 33. Yes.
This will be described in detail below.

  As shown in FIG. 1, the shock absorber D in one embodiment is interposed between a vehicle body side tube 1 constituting a front fork and an axle side tube (not shown) provided below in FIG.

  The axle side tube is slidably inserted into the vehicle body side tube 1 or the vehicle body side tube 1 is slidably inserted into the axle side tube, and the vehicle body side tube 1 and the axle side tube are inserted. The inside is sealed with an annular seal (not shown).

  The shock absorber D includes a cylinder 2, a piston (not shown) slidably inserted downward in FIG. 1 in the cylinder 2, one end connected to the piston, and the other end to the lower end of the axle side tube. A piston rod (not shown) to be connected, an upper chamber A defined by the piston in the cylinder 2, a lower chamber (not shown) arranged below the piston, a main reservoir chamber R1 and a sub reservoir chamber R2 constituting a reservoir. The cylinder 2 is filled with a liquid.

  As shown in the figure, the cylinder 2 is connected to the vehicle body side tube 1 by screwing the outer periphery of the upper end of the housing 19 of the cylindrical main reservoir chamber R1 connected to the upper end thereof to the inner periphery of the vehicle body side tube 1. Has been. The seal member 3 seals between the housing 19 and the vehicle body side tube 1.

  Further, a cap 4 that covers the opening end is screwed to the upper end opening end of the housing 19, and the cap 4 is formed in an annular shape with a concave portion that opens into the housing 19. On the inner peripheral side, a rod 5 that stands up inward of the housing 19 is screwed.

  The rod 5 is formed in a cylindrical shape, and is provided with a base valve member 10 that abuts on the inner periphery of the upper end of the cylinder 2 on the outer peripheral side of the tip that is the lower end in the figure. The inside of the housing 19 is partitioned from the inside of the housing 19, and the upper chamber A and the main reservoir chamber R1 are partitioned.

  Furthermore, a lower end opening end of the elastic partition wall 20 formed of rubber or the like and having a substantially cylindrical shape is fastened and fixed to the outer periphery of the side portion of the rod 5 by a fastening band 21.

  Further, the upper end of the elastic partition 20 in the drawing is housed in the recess of the cap 4 and is moved relative to the cap 4 by the donut plate 22 sandwiched between the lower end of the cap 4 and the step portion 5a of the rod 5. It is held on the outer peripheral side of the annular holder 23 that is disabled.

  Therefore, the main reservoir chamber R1 is partitioned into the liquid chamber L and the air chamber G by the elastic partition wall 20, and pressurized gas is sealed in the air chamber G. As described above, the gas chamber G and the liquid chamber L are partitioned to prevent the gas in the gas chamber G from being mixed into the liquid, thereby causing undesirable aeration and cavitation in the buffer D. Has been resolved.

  Further, the base valve member 10 includes flow paths 11 and 12 communicating with the upper chamber A and the liquid chamber L in the main reservoir chamber R1, and the liquid chamber in the upper chamber A and the main reservoir chamber R1 through the rod 5. A flow path 13 communicating with L is provided. The flow path 11 is provided with a damping force generating element 14 that provides resistance to the flow of liquid from the upper chamber A toward the liquid chamber L. The flow path 12 includes the upper chamber. A non-return valve 15 that blocks only the flow of liquid from A to the liquid chamber L is provided. Further, the flow path 13 generates a damping force that provides resistance to the flow of liquid from the upper chamber A to the liquid chamber L. Element 16 is provided.

  A poppet valve 6 is accommodated on the inner peripheral side of the rod 5, and the poppet valve 6 moves forward and backward in the axial direction by rotating a male screw 8 screwed into the inner periphery of the cap 4 with respect to the cap 4. As a result, the valve opening area is adjusted via the control rod 7, and the flow of liquid from the upper chamber A to the liquid chamber L via the passage 13 is blocked and the resistance given to the liquid flow. Can be changed. Incidentally, in the state shown in the figure, the male screw 8 is at the lowermost position, the poppet valve 6 is closed, and communication between the upper chamber A and the liquid chamber L is cut off.

  Therefore, the damping force generating elements 14 and 15 in the base valve member 10 generate a damping force when the shock absorber D is compressed, and change the compression side damping force by adjusting the valve opening term area of the poppet valve 6. Can be done.

  In addition, the above-described air chamber G basically has the shock absorber D as a result of the elastic partition wall 20 being bent and changing its volume due to the balance between the pressure in the liquid chamber L and the pressure in the air chamber G. While compensating for the volume of liquid in which the piston rod advances and retreats from the cylinder 2 which becomes excessive and insufficient in the cylinder 2 when expanding and contracting, the volume change due to the temperature change of the liquid in the shock absorber D is compensated. The pressure in the upper chamber A and the lower chamber is kept above a certain level by the spring action of the pressurized gas sealed in the chamber G, and the compression side damping force is sufficiently generated when the shock absorber D changes from expansion to compression. I have to.

  In turn, the sub-reservoir chamber R2 has a gap between the cylinder 2 and the vehicle body side tube 1 and the axle side tube, more specifically, a gap between the shock absorber D and the vehicle body side tube 1 and the axle side tube. The sub-reservoir chamber R2 is also filled with liquid, and although not shown, the lower end of the cylinder 2 is always placed in the liquid in the sub-reservoir chamber R2.

  The side portion 19a of the housing 19 in the vicinity of the cylinder 2 is formed thick, and a passage 30 that communicates the main reservoir chamber R1 and the sub reservoir chamber R2 is provided in the thick side portion 19a. A relief valve 31 that opens when the internal pressure of the liquid chamber L becomes equal to or higher than a predetermined pressure, specifically, the allowable pressure of the cylinder 2 is provided in the middle of the passage 30.

  Specifically, the relief valve 31 includes a sphere 32 that is a valve body that closes the passage 30 from the outer side of the cylinder 2, an annular valve seat 33 provided in the middle of the passage 30, and a sphere 32 in the valve seat direction. A C-ring 34 serving as an urging means for urging the pin, and a pin 35 which is embedded in the housing 19 and engages with a cut of the C-ring 34 to function as a detent of the C-ring 34, Further, the C-ring 34 is fitted in an annular groove 36 formed on the outer peripheral side of the housing 19 and communicating with the passage 30, and movement in the axial direction with respect to the housing 19 is restricted.

  By configuring the relief valve 31 in this way, it is possible to avoid an increase in the outer diameter of the housing 19, that is, an increase in the size of the shock absorber D, and it is easy to incorporate in the front fork. For example, it may be configured to include a valve seat provided in the middle of the passage 30, a valve body that is attached to and detached from the valve seat, and an urging means that urges the valve body in the valve seat direction. As another configuration, a poppet valve or the like can be employed.

  In the relief valve 31, when the pressure in the liquid chamber L becomes equal to or higher than a predetermined pressure, the liquid in the liquid chamber L presses the sphere 32 toward the outer side of the housing 19, thereby causing the C ring 34 to bend. Then, the spherical body 32 is separated from the valve seat 33, the blockage of the passage 30 is released, the valve is opened, and the liquid in the liquid chamber L is discharged to the sub reservoir chamber R2.

  Therefore, when the shock absorber D is fully stroked to the compression side and the pressure in the cylinder 2 is likely to become a high pressure exceeding the allowable pressure, the liquid in the liquid chamber L is opened to the sub reservoir chamber R2 by opening the relief valve 31. Since it is discharged, the pressure in the cylinder 2 does not exceed the allowable pressure.

  The relief valve 31 does not close the passage that connects the main reservoir chamber and the auxiliary reservoir chamber by the sliding contact surface of the partition wall member as in the conventional shock absorber, but does not include a sliding contact portion and is liquid. Since the inside of the cylinder can be maintained in a pressurized state without disposing a seal on the relief valve 31, the number of parts of the shock absorber can be reduced compared to the conventional one, and There is no adverse effect of being forced to perform precise processing, and since the relief valve 31 is provided independently of the partition member, the structure of the main reservoir chamber R1 is simplified and the processing cost is reduced.

Furthermore, since the passage 30 is provided below the elastic partition wall 20 that is not the top of the housing 19 but on the side, a situation in which the passage 30 is unintentionally blocked by the elastic partition wall 20 is avoided . Is Raniwa, in the case of this embodiment, even if the leakage of gas from the gas chamber G for some reason, and the housing 19 is connected to the vehicle body side tube 1, passage 30 is the cylinder 2 As is clear from the fact that the gas is exhausted from the housing 19 through the passage 30 as is clear from the fact that it is disposed below the air chamber G, the utility of the shock absorber D is improved. .

  Note that a free piston that is slidably inserted into the housing 19 can be used for partitioning the air chamber G and the liquid chamber L of the main reservoir chamber R1, but in the case of the shock absorber D, as described above. Further, by dividing the gas chamber G and the liquid chamber L by the elastic partition wall 20, there is an advantage that the smooth operation of the shock absorber D can be ensured without causing the occurrence of sliding resistance unlike the free piston.

  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 an expanded sectional view in the reservoir | reserver part of the buffer in one Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body side tube 2 Cylinder 4 Cap 5 Rod 6 Poppet valve 7 Control rod 8 Male screw 10 Base valve member 11,12,13 Flow path 14,16 Damping force generation element 19 Housing 20 Elastic partition 21 Tightening band 23 Holder 30 Passage 31 Relief valve 32 Sphere as valve body 33 Valve seat 34 C ring 35 as urging means Pin A Upper chamber D Buffer G Air chamber L Liquid chamber R1 Main reservoir chamber R2 Secondary reservoir chamber

Claims (3)

A shock absorber having a reservoir that is interposed between a vehicle body side tube and an axle side tube and compensates for excess or deficiency of liquid in the cylinder , the reservoir being connected to a main reservoir chamber communicated with the cylinder A sub-reservoir chamber communicated with the reservoir chamber via a passage, a main housing chamber provided in a cylinder end portion, and a liquid chamber defined by a partition member housed in the housing; And a sub-reservoir chamber in a shock absorber formed in a space formed by the vehicle body side tube and the axle side tube on the outer peripheral side of the housing, and the passage is positioned below the partition member. provided on the housing side, further provided a relief valve which opens when the liquid chamber pressure in the main reservoir chamber in the middle of the passage is equal to or greater than predetermined pressure, the relief valve is provided in the middle of the passage Shock absorber is characterized in that is constituted by a valve body seated is energized the valve seat side on the valve seat by the seat and biasing means. The shock absorber according to claim 1, wherein a side portion of the housing near the cylinder is formed thick, and a passage is provided in the thick side portion . The relief valve includes a sphere that closes the passage from the outside of the cylinder, an annular valve seat provided in the middle of the passage, a C-ring that urges the sphere in the valve seat direction, and a C-ring embedded in the housing. The shock absorber according to claim 1, further comprising a pin that engages with the cut and functions as a detent for the C-ring .

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