JP4898596B2 - Pneumatic shock absorber - Google Patents

Description

  The present invention relates to a pneumatic shock absorber, and more particularly to an improvement of a pneumatic shock absorber that can be used in a suspension device of a vehicle such as an automobile or an industrial vehicle.

  Conventionally, as this kind of pneumatic shock absorber, those of various structures can be exemplified, but as the pneumatic shock absorber used in a vehicle suspension device, the one shown in Patent Document 1 is exemplified. Can do.

  The pneumatic shock absorber includes a cylinder, a piston slidably inserted into the cylinder, a piston rod movably inserted into the cylinder via the piston, and a damping force provided to the piston. Department.

In this pneumatic shock absorber, a relief valve that opens the flow path when the frequency of the input vibration is high is provided to prevent the damping force in the high frequency region from increasing. .
JP 2000-104778 A (page 3, right column, line 41 to page 4, left column, line 22; FIGS. 2 and 3)

  Since the pneumatic shock absorber configured as described above uses a working medium as a gas, it is lighter than a hydraulic shock absorber that also uses working oil as the working medium, and does not use any working oil. Also friendly.

  Further, since no aeration is caused because no hydraulic oil is used, a predetermined damping force can be accurately generated, and this is very effective as a shock absorber. When used in a suspension device, the following problems may occur.

  That is, when a vehicle using a pneumatic shock absorber as a suspension device gets over a step while driving, vibrations applied to the pneumatic shock absorber when the tire gets over the step generate air column resonance sound inside the pneumatic shock absorber. .

  This air column resonance sound is a phenomenon peculiar to a pneumatic shock absorber that occurs because the cylinder is not filled with hydraulic oil, and it does not occur when using a hydraulic shock absorber. Air column resonance may be heard as an unpleasant harsh sound by the passenger.

  Accordingly, an object of the present invention is to provide a pneumatic shock absorber having a structure capable of reducing air column resonance sound that may be heard as an unpleasant harsh sound for passengers.

To achieve the above object, one aspect of the present invention, the cylinder and a piston for partitioning the inside the cylinder to the rod side chamber and the piston side chamber, a piston which is movably inserted into through the piston into the cylinder In a pneumatic shock absorber provided with a rod, a passage provided in the piston and communicating with the rod side chamber and the piston side chamber, and a damping force generation portion provided in the middle of the passage, and in which gas is sealed in the cylinder, A sound absorbing member is provided in the rod side chamber, and the sound absorbing member is composed of a main body and a small-diameter protruding portion having a smaller diameter than the main body integrally connected to the main body, and the small-diameter protruding portion is not blocked by the flow path. It is arranged on the upper surface of the piston .

Similarly, other means include a bottomed cylindrical outer cylinder, a cylinder disposed inside the outer cylinder, a reservoir chamber formed between the cylinder and the outer cylinder, a rod side chamber and a piston in the cylinder. A piston that is partitioned into a side chamber, a piston rod that is movably inserted into the cylinder via the piston, a passage that is provided in the piston and communicates with the rod side chamber and the piston side chamber, and is provided in the middle of the passage. A damping force generation unit, a communication path communicating the reservoir chamber and the piston side chamber, and a connection path connecting the reservoir chamber and the rod side chamber, and injecting lubricating oil into the piston side chamber and the reservoir chamber, in pneumatic damper encapsulating gas in the cylinder, the sound absorbing member provided on one or both of the rod side chamber and the piston side chamber, a body of the sound-absorbing member A small-diameter protruding portion having a smaller diameter than the main body integrally connected to the main body, and the small-diameter protruding portion on the upper surface of the piston or the bottom surface of the cylinder so as not to block the flow path or the communication path. It is characterized by having been arranged.

  According to the present invention, since the sound absorbing member is provided in one or both of the rod side chamber and the piston side chamber, the air column resonance generated in the cylinder can be absorbed and the noise level can be reduced.

  For this reason, for example, in an operating state used for a vehicle suspension device, even if an air column resonance sound is generated inside the pneumatic shock absorber due to vibration applied when a tire disposed on the axle side crosses a step on the road surface. Since the sound absorbing member absorbs the air column resonance sound, the noise level can be reduced.

  Therefore, it is possible to reliably prevent the air column resonance sound from being heard as an unpleasant harsh sound by the passenger, and provide only a good riding comfort for the passenger.

  Hereinafter, an embodiment in which the present invention is embodied in a pneumatic shock absorber used in a suspension device for an automobile will be described with reference to the drawings.

  As shown in FIG. 1, the pneumatic shock absorber 1 of the present embodiment includes a bottomed cylindrical outer cylinder 2, a cylinder 3 disposed concentrically inside the outer cylinder 2, A reservoir chamber R formed between the outer cylinders 2, a piston 5 that divides the inside of the cylinder 3 into a rod side chamber 40 and a piston side chamber 50, and a piston rod 6 that is movably inserted into the cylinder 3 via the piston 5. A passage provided in the piston 5 for communicating the rod side chamber 40 and the piston side chamber 50, a damping force generating portion provided in the passage, a communication passage 9 for communicating the reservoir chamber R and the piston side chamber 50, Similarly, a connecting path for connecting the reservoir chamber R and the rod side chamber 40 is provided, the lubricating oil O is injected into the piston side chamber 50 and the reservoir chamber R, and a gas G is sealed in the cylinder 3. The head side chamber 40 and the piston side chamber 50 has the sound absorbing member is provided in the present invention.

  More specifically, a rod guide 12 for guiding the piston rod 6 is provided at the opening end of the cylinder 3 that is the inner periphery of the upper end of the outer cylinder 2, and an oil seal 13 is mounted on the upper surface of the rod guide 12. Is placed.

  The outer cylinder 2, the oil seal 13, the rod guide 12 and the cylinder 3 are integrally crimped and fixed by bending the upper end of the outer cylinder 2 inward.

  The oil seal 13 includes an annular insert metal 14 and an annular inner peripheral lip 15 integrally formed on the inner peripheral side of the insert metal 14. The inner peripheral lip 15 is not shown, but is a piston rod. 6 is sealed in the cylinder 3 with a dust lip that slidably contacts the outer peripheral surface of the cylinder 6 to prevent dust from entering from the atmosphere side, and a lubricating oil O that is slidably contacted with the outer peripheral surface of the piston rod 6 and from a storage recess 18 described later. And an oil lip that prevents the gas G from leaking to the atmosphere side.

  The rod guide 12 is formed in a columnar shape having a guide hole 17 for guiding the piston rod 6 at the center, and a storage recess 18 for storing lubricating oil O is formed at the center of the upper surface. .

  A reservoir chamber side connection path 19 communicating with the reservoir chamber R and a rod side chamber side connection path 20 communicating with the rod side chamber 40 are connected to the storage recess 18 so that the lubricating oil O in the reservoir chamber R is stored. It flows out to the rod side chamber 40 through the recess 18.

  In addition, lubricating oil O is stored in the storage recess 18 up to the position where the lower end of the inner peripheral lip 15 is immersed, preventing oil film breakage between the inner peripheral lip 15 and the piston rod 6, and the inner peripheral lip. The connection position of the rod side chamber side connection path 20 with respect to the storage recess 18 is determined so that excess lubricating oil O accumulated up to the upper side of the lower end of 15 flows out to the rod side chamber 40.

  The piston 5 is provided at the lower end of the piston rod 6, and a pressure side communication passage 21 and an extension side communication passage 22 as the passages communicating the rod side chamber 40 and the piston side chamber 50 are respectively provided on the outer peripheral side of the upper surface thereof. It is drilled toward the bottom surface.

  In the middle of the pressure side communication passage 21, only the pressure side damping valve 23 as a damping force generating portion and the flow of the gas G and the lubricating oil O from the piston side chamber 50 to the rod side chamber 40 above the pressure side damping valve 23 are allowed. A compression-side check valve 24 is provided, and an expansion-side damping valve 25 as a damping force generation unit is provided in the middle of the expansion-side communication passage 22 and from the rod-side chamber 40 below the expansion-side damping valve 25. An extension-side check valve 26 that allows only the flow of gas G and lubricating oil O toward the piston-side chamber 50 is provided.

  The extension side and compression side damping valves 25 and 23 serving as the damping force generating section can employ various damping force generating structures such as orifices and leaf valves.

  Although not shown, it is preferable to provide a bush or the like on the outer periphery of the piston 5 to ensure slidability and airtightness with the inner peripheral surface of the cylinder 3.

  The sound absorbing member provided in the rod side chamber 40 is a rod side chamber side foam 28 formed by foaming synthetic rubber in an open cell state, and is formed in a substantially cylindrical shape having an insertion hole 28a therein. The foamed body is placed on the upper surface of the piston 5 by press-fitting the piston rod 6 in 28a.

  Further, a small-diameter protruding portion 29 is provided in a portion of the rod side chamber side foam 28 facing the upper surface of the piston 5, and when the rod side chamber side foam 28 is placed on the piston 5 upper surface, the foam 28. However, the pressure side communication path 21 and the extension side communication path 22 are not blocked.

  A valve case 31 constituting the bottom of the cylinder 3 is provided at the lower end of the cylinder 3. The valve case 31 is formed with the communication passage 9 for communicating the reservoir chamber R and the piston side chamber 50. A case-side check valve 32 that allows only the flow of gas O and lubricating oil G from the piston-side chamber 50 toward the reservoir chamber R is provided in the middle of the communication passage 9.

  A sound absorbing member provided in the piston side chamber 50 of the present invention is provided on the upper surface of the valve case 31, and this sound absorbing member is a piston side chamber side foam 33 formed by foaming synthetic rubber in an open cell state. The whole is formed in a substantially cylindrical shape, and the lower end thereof is fixed to the upper surface of the valve case 31 by fixing means such as joining and fitting.

  Further, a small-diameter protruding portion 34 is provided at a portion fixed to the upper surface of the valve case 31 of the piston-side chamber-side foam 33, and when the lower end of the piston-side chamber-side foam 33 is fixed to the upper surface of the valve case 31. The foam 33 does not block the communication path 9. A gas G is sealed in the rod side chamber 40, the piston side chamber 50, and the reservoir chamber R, and lubricating oil O is injected into the piston side chamber 50 and the reservoir chamber R.

  The pneumatic shock absorber configured as described above, for example, attaches the rod side eye 35 provided at the tip of the piston rod 6 to the vehicle body side and attaches the cylinder side eye 36 provided at the lower end of the cylinder 3 to the axle side. In this way, it is incorporated into the suspension device of an automobile.

  Next, the operation will be described. When the piston rod 6 retreats from the cylinder 3, that is, when the pneumatic shock absorber 1 extends, the gas sealed in the rod side chamber 40 is expanded by the piston 5. While passing through the side communication path 22 and flowing into the piston side chamber 50, an extension side damping force is generated by the extension side damping valve 25 provided in the middle of the extension side communication path 22.

  When the piston rod 6 enters the cylinder 3, that is, when the pneumatic shock absorber 1 contracts, the gas G enclosed in the piston side chamber 50 passes through the pressure side communication passage 21 provided in the piston 6. The pressure side damping force is generated by the pressure side damping valve 23 provided in the middle of the pressure side communication passage 21.

  At this time, surplus lubricating oil O accumulated in the storage recess 18 flows out to the rod side chamber 40 via the rod side chamber side connection path 20 and adheres to the sliding contact portion between the piston 5 and the cylinder 3 to provide slidability. Improve.

  Further, the lubricating oil O injected into the rod side chamber 40 passes through the communication path 9 provided in the valve case 31 and flows into the reservoir chamber R, and then passes through the reservoir chamber side connection path 19 provided in the rod guide 12. To the storage recess 18.

  In the contraction process of the pneumatic shock absorber 1, the gas G enclosed in the piston side chamber 50 passes through the pressure side communication passage 21 provided in the piston 5 and flows into the rod side chamber 40, as is apparent from the drawing. At least one of the passage 9, the reservoir chamber R, the reservoir chamber side connection path 19, and the rod side chamber side connection path 20 gives a greater resistance to the flow of the gas G and the lubricating oil O than the compression side damping valve 23. A valve may be provided between the piston side chamber 50 and the rod side chamber 40 via the reservoir chamber R, or a pipe resistance between the piston side chamber 50 and the rod side chamber 40 via the reservoir chamber R may be provided. Specifically, for example, the case side check valve 32 may be a leaf valve, or the flow passage areas of the communication passage 9, the reservoir chamber side connection passage 19, and the rod side chamber side connection passage 20 may be reduced. Kushitari, the cross-sectional area of the annular reservoir chamber R may be very small.

  Returning to the operation state of the pneumatic shock absorber 1 described above, when the tire arranged on the axle side gets over the road step and the vibration is applied to the pneumatic shock absorber 1, the air pressure inside the pneumatic shock absorber 1 is reduced. Column resonance is generated.

  At this time, the rod side chamber 40 and the piston side chamber 50 are provided with rod side and piston side foams 28 and 33 as sound absorbing members in the cylinder 3, respectively. The resonance level is absorbed and the noise level is reduced.

  Therefore, it is possible to reliably prevent the air column resonance sound from being heard as an unpleasant harsh sound by the passenger, and to provide only a good ride comfort for the passenger.

  Further, since the open-celled rod side and piston-side foams 28 and 33 in which bubbles are connected to each other are used as the sound absorbing member, the surface area is increased, and the sound absorbing property is improved accordingly.

  Further, since the foams 28 and 33 are provided in the rod side chamber 40 and the piston side chamber 50, respectively, in addition to the sound absorbing action, the impact can be reduced when the piston rod 6 is fully extended or retracted. This is particularly effective when used in a suspension apparatus.

  In addition, this invention is not limited to the said embodiment, For example, it can also be changed as follows.

  1) In the present embodiment, the rod side chamber side and the piston side chamber side foams 28 and 33 as the sound absorbing members are provided in both the rod side chamber 40 and the piston side chamber 50. However, the present invention is not limited to this. You may provide only in any one of the rod side chamber 40 and the piston side chamber 50. FIG.

  2) In the present embodiment, the rod-side chamber-side foam 28 is formed in a substantially cylindrical shape having an insertion hole 28a therein, and the piston rod 6 is press-fitted into the insertion hole 28a. 28 is placed on the upper surface of the piston 5, but the present invention is not limited to this. The rod side foam 28 is formed in an annular shape and directly fixed to the piston 5 or directly to the rod guide 12. Also good.

  3) In the present embodiment, the piston-side chamber-side foam 33 is formed in a columnar shape and directly fixed to the valve case 31. However, the present invention is not limited to this, and the piston 5 is located on the piston-side chamber 50 side. You may make it fix directly to a lower surface.

  4) In the present embodiment, a foamed body in which synthetic rubber is foamed in an open cell state is used as the sound absorbing member. However, the present invention is not limited to this, and has a material and structure that can efficiently absorb sound. Anything can be used.

  5) In the present embodiment, an open cell foam in which bubbles are connected is used as the absorbing member. However, the present invention is not limited to this, and the sound absorbing ability is somewhat reduced, but the bubbles are connected. No closed cell foam may be used.

  6) In the present embodiment, a so-called double cylinder type pneumatic shock absorber having the outer cylinder 2 on the outside of the cylinder 3 is embodied. Of course, it may be embodied in a so-called single cylinder type hydraulic shock absorber that does not have the cylinder 2.

It is sectional drawing which shows one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic shock absorber 2 Outer cylinder 3 Cylinder 5 Piston 6 Piston rod 9 Communication path 19 Reservoir chamber side connection path (connection path)
20 Rod side chamber side connection path (connection path)
21 Pressure side passage (passage)
22 Stretch side communication passage (passage)
23 Pressure-side damping valve (damping force generator)
25 Extension side damping valve (Damping force generator)
28 Rod side chamber side foam (sound absorbing member)
28a Insertion hole 33 Piston side chamber side foam (sound absorbing member)
40 Rod side chamber 50 Piston side chamber G Gas O Lubricating oil R Reservoir chamber

Claims (5)

A cylinder, a piston for partitioning the inside the cylinder to the rod side chamber and the piston side chamber, and a piston rod which is movably inserted into through the piston into the cylinder, the rod side chamber and the piston side chamber provided on the piston A pneumatic shock absorber provided with a communicating passage and a damping force generating portion provided in the middle of the passage, and in which a gas is sealed in the cylinder , a sound absorbing member is provided in the rod side chamber, and the sound absorbing member is attached to the main body and the main body. A pneumatic buffer comprising: a small-diameter projecting portion having a smaller diameter than the main body integrally connected to the main body, and the small-diameter projecting portion disposed on the upper surface of the piston so as not to block the flow path. vessel. A bottomed cylindrical outer cylinder, a cylinder disposed inside the outer cylinder, a reservoir chamber formed between the cylinder and the outer cylinder, a piston that divides the cylinder into a rod side chamber and a piston side chamber, A piston rod movably inserted into the cylinder via a piston, a passage provided in the piston and communicating with the rod side chamber and the piston side chamber, a damping force generator provided in the middle of the passage, A communication path that connects the reservoir chamber and the piston side chamber and a connection path that similarly connects the reservoir chamber and the rod side chamber. in pneumatic shock absorber to one or both of the rod side chamber and the piston side chamber provided a sound-absorbing member, integrally connected to the sound-absorbing member to the body and the body Which was composed of a small diameter small diameter protruding portion from the main body, characterized in that the small diameter protruding portions were placed at the bottom the upper surface of the upper surface or the cylinder of the piston so as not to block the flow path or the communicating path Pneumatic shock absorber. The pneumatic shock absorber according to claim 1 or 2, wherein the sound absorbing member is a foam formed by foaming synthetic rubber in an open cell state. The pneumatic shock absorber according to claim 1 or 2, wherein the sound absorbing member is formed in a cylindrical shape having an insertion hole therein, and is provided in the rod side chamber by press-fitting the piston rod into the insertion hole. The pneumatic shock absorber according to claim 1 or 2, wherein the sound absorbing member is formed in a cylindrical shape, and is provided in the piston side chamber by fixing a lower end of the sound absorbing member to the cylinder bottom.

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