JP5156859B2 - Pneumatic shock absorber - Google Patents

Description

The present invention relates to an improvement of a pneumatic shock absorber that can be used as a suspension for a vehicle or the like.

Conventionally, as a pneumatic shock absorber, a cylinder, a piston that is slidably inserted into the cylinder, and a rod that is movably inserted into the cylinder via the piston are formed in a so-called inverted type. Things are known.

This pneumatic shock absorber is used for vehicle suspension applications. In addition to communicating the rod-side chamber and the piston-side chamber in the passage of the piston portion, an outer cylinder is provided outside the cylinder so that the cylinder is located between the cylinder and the outer cylinder. The rod side chamber and the piston side chamber communicate with each other through a gap, and the oil in the cylinder is circulated between the piston side chamber and the rod side chamber in the manner of a pump by the expansion and contraction movement of the pneumatic shock absorber. The slidability of the sliding portion which is the contact portion between the contact portion and the rod and the sealing member provided at the lower end of the cylinder is ensured (for example, see Patent Documents 1 and 2).

JP 2004-132429 A JP 2004-132428 A

Now, in the pneumatic shock absorber as described above, even if a gas is used as a working fluid, it can be applied to a vehicle suspension by ensuring smooth slidability. However, it may be pointed out that there are the following problems. There is sex.

That is, in the conventional pneumatic buffer, the working fluid is a gas, and the gas can expand and contract. Therefore, no device for dealing with the volume change of the gas is provided, and the influence of the volume change of the gas is not provided. Therefore, it is impossible to prevent the rod reaction force from fluctuating and the vehicle height from rising or falling.

When a pneumatic shock absorber is used for vehicle suspension applications, the temperature of the gas in the cylinder becomes very high due to repeated expansion and contraction of the pneumatic shock absorber. And because it is very large, the vertical movement of the vehicle height due to the temperature change of the gas becomes remarkable.

In addition, when applying pneumatic shock absorbers to vehicle suspensions, four pneumatic shock absorbers are required even for passenger cars, and it is possible to assume that the rod reaction force of the four pneumatic shock absorbers will vary. There is also a risk that the vehicle rider feels uncomfortable or uncomfortable, and the riding comfort of the vehicle is impaired.

Therefore, the present invention has been developed to improve the above-described problems, and an object of the present invention is to provide a pneumatic shock absorber capable of improving the riding comfort in a vehicle. .

One of the problem-solving means of the present invention is a pneumatic buffer comprising a cylinder, a piston that divides the cylinder into a rod-side chamber and a piston-side chamber, and a rod that is movably inserted into the cylinder via the piston. In the container, a bottom member for closing the lower end of the cylinder, a protrusion standing at the upper end of the bottom member, and a volume change absorption mechanism for absorbing the volume change of the working gas are provided, and the volume change absorption mechanism is provided in the piston side chamber. A pressure chamber communicated through the passage; a throttle provided in the middle of the passage; and a variable mechanism for changing the volume of the pressure chamber, the passage through the bottom member and the upper end of the protrusion. It is characterized by being opened in the side chamber.

Similarly, another means operates in a pneumatic shock absorber comprising a cylinder, a piston that divides the cylinder into a rod side chamber and a piston side chamber, and a rod that is movably inserted into the cylinder via the piston. A volume change absorption mechanism that absorbs the volume change of gas is provided, and the volume change absorption mechanism changes the pressure chamber communicated with the piston side chamber via a passage, the throttle provided in the middle of the passage, and the volume of the pressure chamber. And a variable mechanism that allows the passage to pass through the inside of the rod and open into the piston side chamber.

According to the pneumatic shock absorber of the present invention, the heat generated when the working gas passes through the damping force generating element, the change in the outside air temperature, and the influence of the friction of the sliding portion due to repeated expansion and contraction over a long period of time. Even if the temperature of the working gas in the cylinder changes, the volume change absorption mechanism suppresses the pressure change in the cylinder due to the volume change caused by the temperature change of the working gas.

That is, the pressure change in the cylinder 1 due to the volume change of the working gas is suppressed by the volume change absorption mechanism, and the fluctuation of the rod reaction force of the pneumatic buffer A due to the volume change caused by the temperature change of the working gas. Can be relaxed by the volume change absorption mechanism.

Therefore, a situation in which the vehicle height rises and falls due to the temperature change of the working gas in the cylinder of the pneumatic shock absorber is prevented, and the vehicle occupant does not feel uncomfortable or uncomfortable without exerting a posture change on the vehicle body, Riding comfort in the vehicle can be improved.

According to the first aspect of the present invention, since the passage opens into the piston side chamber through the upper end of the protrusion, only the working gas can exchange the piston side chamber and the pressure chamber through the passage.

According to the second aspect of the present invention, since the passage passes through the rod and opens into the piston side chamber, only the working gas can be reliably exchanged with the piston side chamber R2 and the pressure chamber 51.

It is a schematic longitudinal cross-sectional view of the basic pneumatic shock absorber in a reference example. It is a schematic longitudinal cross-sectional view of the pneumatic shock absorber in the embodiment corresponding to the invention of claim 1. It is a schematic longitudinal cross-sectional view of the pneumatic shock absorber in an embodiment corresponding to the invention of claim 2. It is a schematic longitudinal cross-sectional view of the pneumatic shock absorber in another reference example. It is a schematic longitudinal cross-sectional view of the pneumatic shock absorber in another reference example. Similarly, it is a schematic longitudinal cross-sectional view of the pneumatic shock absorber in another reference example.

The invention according to each claim will be described below based on the reference examples and embodiments shown in the drawings.

FIG. 1 is a schematic longitudinal sectional view of a basic pneumatic shock absorber according to a reference example.

FIG. 2 is a schematic longitudinal sectional view of a pneumatic shock absorber according to one embodiment.

FIG. 3 is a schematic longitudinal sectional view of a pneumatic shock absorber according to another embodiment.

FIG. 4 is a schematic longitudinal sectional view of a pneumatic shock absorber according to another modification of another reference example.

FIG. 5 is a schematic longitudinal sectional view of a pneumatic shock absorber in another example of another modification of another reference example.

FIG. 6 is a schematic longitudinal sectional view of a pneumatic shock absorber according to another reference example.

As shown in FIG. 1, a basic pneumatic shock absorber A according to the reference example includes a cylinder 1, an outer cylinder 2 in which the cylinder 1 is accommodated, a rod side chamber R1 and a piston side chamber R2 in the cylinder 1. The piston 3 partitioned into the cylinder 1, the rod 4 movably inserted into the cylinder 1 via the piston 3, the volume change absorption mechanism 30, and the rod side chamber R 1 and the piston side chamber R 2 provided in the piston 3. Cylinders that are formed by gaps between the cylinders 1 and the outer cylinder 2 and that connect the rod-side chamber R1 and the piston-side chamber R2 by bypassing the passages 5 and 6 and forming the passages 5 and 6 that give resistance to the flow of gas that passes. An outer passage 7 is provided.

Hereinafter, the cylinder 1 will be described in detail. The upper and lower ends of the cylinder 1 are closed by the head member 8 and the bottom member 9 and filled with gas, respectively, and are disposed outside the cylinder 1. It is accommodated in a bottomed cylindrical outer cylinder 2 that covers the cylinder 1. In addition, in order to lubricate the sliding site | part of the pneumatic buffer A, the cylinder 1 is filled with a small amount of oil with gas.

The cylinder 1 is partitioned into a rod-side chamber R1 and a piston-side chamber R2 by a piston 3 that is slidably inserted. A rod 4 is connected to the upper end of the piston 3 in FIG. In addition, passages 5 and 6 communicating the rod side chamber R1 and the piston side chamber R2 are provided, and damping force generating elements 10 and 11 are provided in the middle of the passages 5 and 6, respectively.

Further, a check valve 12 that allows only a flow from the rod side chamber R1 to the piston side chamber R2 is provided in the middle of the passage 5, and only a flow from the piston side chamber R2 to the rod side chamber R1 is provided in the middle of the passage 6. Is provided. Accordingly, the passage 5 is a one-way passage that allows the passage of fluid only when the pneumatic shock absorber A extends, that is, when the rod 4 projects from the cylinder 1, and the other passage. 6, the pneumatic shock absorber A contracts, that is, it forms a one-way passage that allows the fluid to pass only when the rod 4 enters the cylinder 1.

The damping force generating elements 10 and 11 are variable throttle valves as shown in the figure, and change the resistance applied to the fluid flow according to the expansion / contraction frequency, expansion / contraction speed, etc. of the pneumatic shock absorber A. Can be done. The damping force generating elements 10 and 11 may be fixed throttle valves, leaf valves, or the like instead of variable throttle valves. When the damping force generating element gives the same resistance regardless of the gas flow direction, the piston passage is formed by one passage, and one damping force generating element is provided in the middle. In this case, the check valves 12 and 13 need not be provided.

Furthermore, a volume change absorption mechanism 30 is accommodated in the piston side chamber R2, and the volume change absorption mechanism 30 in this embodiment is a negative expansion body that negatively expands due to a temperature rise. As this negative expansion body, a substance having a negative linear expansion coefficient such as zirconium tungstate (ZrW ₂ O ₈ ) or silicon oxide (Li ₂ O—Al ₂ O ₃ —nSiO ₂ ) can be used. .

The volume change absorbing mechanism 30, which is a negative expansion body, is fixed to the piston 3 and accommodated in the piston side chamber R2 as shown in the figure. The volume change absorbing mechanism 30 that is a negative expansion body may be fixed to the bottom member 9 or the cylinder 1, and the volume change absorbing mechanism 30 is not provided in the piston side chamber R2, but in the rod side chamber R1. You may make it provide, You may make it provide the volume change absorption mechanism 30 which is a negative expansion body in both the rod side chamber R1 and the piston side chamber R2.

Subsequently, as shown in FIG. 1, the outer cylinder 2 is formed in a bottomed cylinder shape, and a cylinder outer passage 7 is formed in a gap between the outer cylinder 2 and the cylinder 1 to fill the cylinder. The outer passage 7 is filled with oil.

In turn, the head member 8 is formed in an annular shape and is fitted to the upper end of the cylinder 1 in FIG. 1, and has a bearing 14 that pivotally supports the rod 4 on its inner peripheral side and opens from the upper end side. A recess 15 is provided. Further, the head member 8 is provided with a flow path 16 that communicates the outer periphery with the recess 15 and a flow path 17 that communicates the lower end with the recess 15, and the opening end on the outer peripheral side of the flow path 16 is outside the cylinder. The opening end on the lower end side of the flow path 17 is opposed to the rod side chamber R1. That is, one end of the cylinder side passage 7 is communicated with the rod side chamber R <b> 1 through the flow path 16, the recess 15 and the flow path 17.

On the other hand, the bottom member 9 that closes the lower end in FIG. 1 of the cylinder 1 is formed in a disc shape and is fitted to the lower end in FIG. 1 of the cylinder 1, and includes a flow path 18 that communicates the upper end with the outer periphery. Configured. The opening end on the upper end side of the flow path 18 faces the piston side chamber R <b> 2, and the opening end on the outer peripheral side faces the cylinder outer passage 7. That is, the other end of the cylinder side passage 7 is communicated with the piston side chamber R <b> 2 via the flow path 18. Further, a check valve 19 that allows only a flow from the piston side chamber R2 to the rod side chamber R1 is provided in the middle of the flow path 18.

Then, the cylinder 1 closed at both ends by the head member 8 and the bottom member 9 configured as described above is inserted and accommodated in the outer cylinder 2, and the upper surface of the head member 8 in FIG. An annular sealing member 20 that holds an annular seal 21 that is in sliding contact is laminated, and an opening end that is the upper end of the outer cylinder 2 in the figure is swaged, and the sealing member 20, head member 8, cylinder 1, and bottom member 9. Is housed and fixed in the outer cylinder 2 and integrated.

In FIG. 1 in the sealing member 20 described above, the axial length that is the vertical length is set shorter than the axial length that is the vertical length of the seal 21 described above, and the seal 21 is sealed. It is held by the sealing member 20 so as to protrude from the lower end of the member 20 toward the inside of the cylinder 1. Although the sealing member 20 holds the seal 21 as described above, the seal 21 may be welded to the sealing member 20 so as not to be separated.

The lower end in FIG. 1 of the seal 21 protruding from the sealing member 20 is disposed in the recess 15 of the head member 8, and the oil storage chamber 22 is defined by the recess 15 and the sealing member 20. The chamber 22 is filled with oil. Therefore, the cylinder outer passage 7 is connected to the oil storage chamber 22 by the above-described flow path 16, whereby the cylinder outer passage 7 communicates the rod side chamber R 1 and the piston side chamber R 2 via the oil storage chamber 22.

Further, as described above, the rod 4 that protrudes from the cylinder 1 and is slidably inserted into the bearing 14 of the head member 8 is inserted on the inner peripheral side of the seal 21. The outer periphery of the rod 4 is pressed against the outer periphery of the rod 4 to seal the outer periphery of the rod 4. A seal (not shown) that seals between the outer periphery of the sealing member 20 and the outer cylinder 2 is provided on the outer peripheral side of the sealing member 20. The cylinder 2 is maintained in an airtight state.

As is apparent from the above description, the rod 4 penetrates the oil storage chamber 22, and the oil storage chamber 22 faces the sliding portion 23 between the rod 4 and the seal 21.

Here, the opening end 17a of the flow path 17 on the oil storage chamber 22 side is opened from the side wall portion 15a of the recess 15, and this opening end 17a is positioned at least above the lowermost end of the seal 21 in FIG. The oil level 24 of the oil filled in the oil storage chamber 22 is always kept in contact with the lower end of the seal 21.

That is, the working gas is sealed in the cylinder 1 and the oil is filled in the oil storage chamber 22 and the cylinder outer passage 7. In the reference example of FIG. In order to ensure the lubrication between them, it is considered that the oil level 24 of the oil in the oil storage chamber 22 does not fall below the lowermost end of the seal 21 depending on the position of the opening end 17a, and more. The excess oil is discharged to the rod side chamber R1, and further, even on the oil surface 25 of the oil in the cylinder outer passage 7, it is positioned above the opening end 16a of the flow path 16. Is set.

The rod side chamber R1 and the piston side chamber R2 are also filled with a small amount of oil, but the oil filled in the rod side chamber R1 is used when the pneumatic shock absorber A performs the expansion / contraction operation for the first time. The oil in the piston side chamber R2 is supplied prior to the gas into the cylinder outer passage 7 when the pneumatic shock absorber is contracted, and the oil in the oil storage chamber 22 is lubricated. Filled to prevent the oil level 24 from descending.

Next, the operation of the pneumatic shock absorber A configured as described above will be described. First, when the pneumatic shock absorber A is extended, the rod side chamber R1 is compressed and the piston side chamber R2 is expanded, so that the gas in the rod side chamber R1 moves into the piston side chamber R2 via the passage 5. During this movement, the gas passes through the damping force generating element 10, so that a pressure loss occurs and a damping force corresponding to the pressure difference between the rod side chamber R1 and the piston side chamber R2 is generated.

At this time, since the oil in the rod side chamber R1 is heavier than the gas and is accumulated in the opening of the passage 5, the oil also moves into the piston side chamber R2 together with the gas.

Subsequently, when the pneumatic shock absorber A is contracted, the piston side chamber R2 is compressed and the rod side chamber R1 is expanded, so that the gas in the piston side chamber R2 moves into the rod side chamber R1 through the passage 6. . During this movement, the gas passes through the damping force generating element 11, so that a pressure loss occurs and a damping force corresponding to the pressure difference between the rod side chamber R1 and the piston side chamber R2 is generated.

Further, due to the pressure increase in the piston side chamber R 2, the gas in the piston side chamber R 2 pushes open the check valve 19 and flows into the cylinder outer passage 7 through the flow path 18.

At this time, since the oil in the piston side chamber R2 is heavier than the gas and is accumulated in the opening of the flow path 18, the oil also moves to the cylinder outside passage 7 together with the gas.

Since the cylinder outer passage 7 and the oil storage chamber 22 are pressurized in the same manner as the piston side chamber R2, the oil in the cylinder outer passage 7 flows into the oil storage chamber 22, and further, the oil storage chamber 22 The oil level 24 of the inside oil will rise.

Then, the oil in the oil storage chamber 22 passes through the flow path 17 and flows into the rod side chamber R1 together with the gas by the rise of the oil surface 24 and the pressure increase in the oil storage chamber 22.

In the contraction stroke of the pneumatic shock absorber A, the gas sealed in the piston side chamber R2 passes through the passage 6 provided in the piston 3 and flows into the rod side chamber R1, as is apparent from the flow path 18, At least one of the cylinder outside passage 7, the passage 16 and the passage 17 gives a greater resistance to the flow of gas and oil than the damping force generating element 11, and this resistance is applied from the piston side chamber R2 to the passage 18 and outside the cylinder. A valve may be provided between the piston side chamber R2 and the flow path 18, the cylinder outside passage 7, the flow path 16 and the flow from the piston side chamber R2 to the rod side chamber R1 via the passage 7, the flow path 16 and the flow path 17. For example, the check valve 19 may be a leaf valve, or the flow of the flow path 18, the flow path 16, and the flow path 17 may be given by a pipe resistance between the flow path 17 and the rod side chamber R <b> 1. Road area Or fence, the annular cross-sectional area of the cylinder outside the passage 7 may be very small.

Moreover, since the opening position of the opening 17a of the flow path 17 is located above the lowermost end of the seal 21, even if the oil moves from the oil storage chamber 22 into the rod side chamber R1 as described above, The oil surface 24 of the oil is always located above the lowermost end of the seal 21, and the oil in the oil storage chamber 22 continues to maintain the lubrication of the sliding portion 23 between the rod 4 and the seal 21. The sliding portion between the rod 4 and the bearing 14 is continuously lubricated in the same manner.

Therefore, even if the pneumatic shock absorber A repeatedly expands and contracts, the oil in the oil storage chamber 22 maintains the lubrication of the sliding portion 23 between the rod 4 and the seal 21 and the sliding portion between the rod 4 and the bearing 14. As a result, the sliding portion 23 of the rod 4 and the sliding portion between the rod 4 and the bearing 14 of the pneumatic shock absorber A formed in an upright shape are surely lubricated. Smooth expansion and contraction operation of the container A is guaranteed, and the reliability of the pneumatic shock absorber A is improved.

Further, in the pneumatic shock absorber A in the reference example of FIG. 1, the oil storage chamber 22 facing the sliding portion of the rod 4 is provided, and the oil surface 24 is positioned above the lowermost end of the sliding portion 23, thereby Since the sliding portion 23 and the sliding portion between the rod 4 and the bearing 14 can be reliably lubricated, the structure is not complicated, and the pneumatic shock absorber can be correctly adjusted without a significant increase in cost. Can be vertical.

Further, as described above, since the sliding portion 23 of the rod 4 and the sliding portion between the rod 4 and the bearing 14 are reliably lubricated, the smooth expansion and contraction operation of the pneumatic shock absorber A is also guaranteed in this respect. As a result, the reliability of the pneumatic shock absorber A is improved and the wear resistance of the seal 21 is improved, so that the sealing performance of the pneumatic shock absorber A is also improved.

In the pneumatic shock absorber A, the heat generated when the working gas passes through the damping force generating element, the change in the outside air temperature, and the sliding portion 23 due to repeated expansion and contraction for a long time. 26, and the temperature of the working gas in the cylinder 1 changes due to the influence of friction of the sliding portion between the rod 4 and the bearing 14, but the pressure change in the cylinder 1 due to the volume change caused by the temperature change of the working gas. The volume change absorption mechanism 30 suppresses.

Here, in the case of this embodiment, the volume change absorption mechanism 30 is a negative expansion body, so that the volume of the working gas increases with respect to the temperature rise and decreases with respect to the temperature drop. When the temperature rises, the volume decreases, and when the temperature falls, the volume increases. The volume change is opposite to the volume change due to the temperature change of the working gas. That is, the pressure change in the cylinder 1 due to the volume change of the working gas is suppressed by the reverse volume change of the volume change absorption mechanism 30, and the pneumatic buffer due to the volume change caused by the temperature change of the working gas. The change in the rod reaction force of A can be mitigated by the volume change absorption mechanism 30.

Therefore, a situation in which the vehicle height is raised or lowered due to the temperature change of the working gas in the cylinder 1 of the pneumatic shock absorber A is prevented, and the vehicle occupant is given a sense of discomfort and discomfort without causing a change in the posture of the vehicle body. Therefore, the riding comfort in the vehicle can be improved.

Next, the pneumatic shock absorber A1 according to the embodiment of the present invention will be described.

As shown in FIG. 2, the pneumatic shock absorber A1 has a volume change absorption mechanism 31 different from the pneumatic shock absorber A according to the embodiment.

In the description of the pneumatic shock absorber A1 in this embodiment, the same members as those of the pneumatic shock absorber A of the above-described reference example of FIG. The detailed explanation will be omitted.

The volume change absorption mechanism 31 in the pneumatic shock absorber A1 according to this embodiment includes a pressure chamber 40 communicated with the piston side chamber R2 via the passage 32, a throttle 33 provided in the middle of the passage 32, and the pressure chamber 40. And a variable mechanism 41 that changes the volume.

The pressure chamber 40 is separated from the housing 42 by a free piston 43 that is slidably inserted into the housing 42, and the variable mechanism 41 separates the free piston 43 and the free piston 43 from the volume of the pressure chamber 40. And a spring 44 for biasing in a direction to reduce the angle. The spring 44 is set so as not to be in the most extended state or the most compressed state even if the volume of the working gas in the pneumatic buffer A1 changes within the temperature range where it is actually used.

Furthermore, the passage 32 is connected to the piston side chamber R2 via the bottom member 9, but the bottom end of the bottom member 9 is arranged so that the opening end thereof is disposed above the oil level of the oil stored in the piston side chamber R2. 2 is opened from the upper end of the protrusion 9a provided at the upper end, and only the working gas can exchange the piston-side chamber R2 and the pressure chamber 40 via the passage 32.

The throttle 33 is basically set so as to prevent the working gas in the cylinder 1 from moving to the pressure chamber 40 when the pneumatic shock absorber A1 expands and contracts while the vehicle is running. ing. Specifically, for example, the diaphragm 33 is set to function as a low-pass filter having a time constant of 10 seconds or more, and when the pneumatic shock absorber A1 vibrates at a stretching vibration frequency of about 0.016 Hz or more, It is set so that the movement of the working gas from the piston side chamber R2 to the pressure chamber 40 is significantly hindered.

Therefore, when the pneumatic shock absorber A1 expands and contracts during traveling of the vehicle, basically the movement of the working gas to the pressure chamber 40 is prevented and the inside of the cylinder 1 is made a substantially closed space. The vessel A1 can generate a sufficient damping force.

On the other hand, when the volume of the working gas changes due to a temperature change and there is a pressure fluctuation in the cylinder 1, the pressure fluctuation is very slow. It becomes possible to go back and forth between the chambers 40, and the volume change absorption mechanism 31 operates to balance the pressures of the cylinder 1 and the pressure chambers 40. That is, when the temperature of the working gas rises, the volume of the working gas expands and the pressure in the cylinder 1 rises. However, the free piston 43 is displaced upward in FIG. When the volume of 40 is increased and a part of the expanded working gas that is excessive in the cylinder 1 is absorbed until the pressure in the cylinder 1 and the pressure chamber 40 is balanced, the temperature of the working gas is decreased. The volume of the working gas contracts and the pressure in the cylinder 1 decreases. However, the free piston 43 is displaced downward in FIG. 2 with respect to the housing 42 and the volume of the pressure chamber 40 decreases. The working gas, which is insufficient in the cylinder 1 until the pressure of 40 is balanced, is supplied from the pressure chamber 40 into the cylinder 1.

Here, the spring constant of the spring 44 is preferably as small as possible. By setting the spring constant, the change in the urging force of the spring 44 even if the free piston 43 is displaced with respect to the housing 42 due to the temperature change of the working gas. Since the amount can be small, even if the volume of the working gas changes, the amount of pressure fluctuation in the cylinder 1 can be reduced.

As described above, in this pneumatic shock absorber A1, the temperature of the working gas in the cylinder 1 changes due to the influence of the friction of the sliding portions 23 and 26 due to the outside air temperature change and the expansion and contraction being repeated for a long time. Even so, the volume change absorption mechanism 31 suppresses the pressure change in the cylinder 1 due to the volume change caused by the temperature change of the working gas.

That is, the pressure change in the cylinder 1 due to the volume change of the working gas is suppressed by the volume change absorption mechanism 31, and the rod reaction force of the pneumatic shock absorber A1 due to the volume change caused by the temperature change of the working gas. The fluctuation can be mitigated by the volume change absorption mechanism 31.

Therefore, a situation in which the vehicle height is raised or lowered due to a change in the temperature of the working gas in the cylinder 1 of the pneumatic shock absorber A1 is prevented, and the vehicle occupant feels uncomfortable or uncomfortable without changing the posture of the vehicle body. Therefore, the riding comfort in the vehicle can be improved.

Although the volume change absorption mechanism 31 is connected to the piston side chamber R2 in the drawing, it may be connected to the rod side chamber R1 or to both the rod side chamber R1 and the piston side chamber R2. It may be. Further, when connected to the rod side chamber R1, the rod side chamber R1 and the pressure chamber 40 may be communicated with each other by providing a passage 32 in the head member 8 or the rod 4.

Further, the variable mechanism 41 includes the free piston 43 and the spring 44 that urges the free piston 43 in a direction to reduce the volume of the pressure chamber 40 as described above. 3, when the volume of the pressure chamber 51 is not changed like the pneumatic buffer A2 in the other embodiment shown in FIG. 3, the negative expansion body 52 is accommodated in the pressure chamber 51 to absorb the volume change. The mechanism 50 may be configured. In the pneumatic shock absorber A2 in another modification of the embodiment, the passage 53 provided with the throttle 33 and communicating the piston side chamber R2 and the pressure chamber 51 opens from the lower end of the piston 3. In this case, since one end of the passage 53 communicating with the piston side chamber R2 is opened from the lower end of the piston 3, it is ensured that only the working gas is passed. The piston side chamber R2 and the pressure chamber 51 can be exchanged with each other.

Even if the volume change absorption mechanism 50 is configured as described above, the pressure change in the cylinder 1 due to the volume change of the working gas is suppressed by the volume change absorption mechanism 50, which is caused by the temperature change of the working gas. The volume change absorbing mechanism 50 can mitigate fluctuations in the rod reaction force of the pneumatic shock absorber A2 due to the volume change.

Therefore, a situation in which the vehicle height is raised or lowered due to a change in the temperature of the working gas in the cylinder 1 of the pneumatic shock absorber A2 is prevented, and the vehicle occupant feels uncomfortable and uncomfortable without exerting a posture change on the vehicle body. Therefore, the riding comfort in the vehicle can be improved.

In forming the pressure chamber 51, as shown in FIG. 4, a cylinder 55 that covers the outer cylinder 2 is provided, and the pressure chamber 51 is formed by a gap between the outer cylinder 2 and the cylinder 55. Good. In this case, as shown in FIG. 4, if the pressure chamber 51 is connected to the piston side chamber R2, it is only necessary to provide the passage 53 in the bottom member 9, so that the connection passage protrudes outward. Further, in this case, the pressure chamber 51 is shaped to hold the cylinder 1 and the outer cylinder 2, and the temperature of the working gas in the cylinder 1 is transmitted to the negative expansion body 52 accommodated in the pressure chamber 51. It becomes easy to be done.

Therefore, by forming the pressure chamber 51 between the outer cylinder 2 and the cylinder 55 covering the outer cylinder 2, the temperature of the working gas in the cylinder 1 is transmitted to the negative expansion body 52 accommodated in the pressure chamber 51. As a result, the pressure change in the cylinder 1 due to the volume change of the working gas is suppressed by the volume change absorption mechanism 50 with good responsiveness, and the pneumatic buffer A2 ′ caused by the volume change caused by the temperature change of the working gas The change in the rod reaction force can be quickly mitigated by the volume change absorption mechanism 50.

In the reference example of FIG. 4 , since the outer cylinder 2 is provided, the cylinder 55 is provided outside the outer cylinder 2 to form the pressure chamber 51. However, the outer cylinder 2 is used for lubrication. Since it is provided to form a passage for circulating oil to the rod side chamber R1, the piston side chamber R2, and the oil storage chamber 22 and does not necessarily have to be an annular passage, for example, as shown in FIG. In the case where the oil storage chamber 22 is connected by the pipe 56, the outside of the cylinder 1 may be directly covered with the cylinder 55, and the pressure chamber 51 may be formed between the cylinder 1 and the cylinder 55. .

Further, in the pneumatic shock absorber A3 of another reference example, as shown in FIG. 6, a pressure chamber 51 ′ in which a negative expansion body 52 ′ having the same configuration as the volume change absorption mechanism 50 is accommodated, and the cylinder 1 It differs from the pneumatic shock absorber A2 of each of the embodiments described above in that the volume change absorption mechanism 70 is configured by connecting the rod side chamber R1 and the piston side chamber R2 defined therein so that the working gas circulates. .

In the pneumatic shock absorber A3 in this reference example, the rod side chamber R1 and the pressure chamber 51 ′ are communicated with each other through the passage 60, and the piston side chamber R2 and the pressure chamber 51 ′ are communicated with each other through the passage 61. A check valve 63 that allows only the flow of the working gas from the throttle 62 and the rod side chamber R1 to the pressure chamber 51 'is provided in the middle, and the throttle 64 and the pressure chamber 51' to the piston side chamber R2 in the middle of the passage 61. A check valve 65 that allows only the flow of the working gas is provided.

Basically, when the temperature of the working gas in the cylinder 1 decreases, the volume of the negative expansion body 52 ′ increases, the pressure in the pressure chamber 51 ′ increases, and the passage 61 passes through the pressure chamber 51 ′. The working gas flows into the piston side chamber R2. On the other hand, when the temperature of the working gas in the cylinder 1 rises, the volume of the negative expansion body 52 ′ decreases, the pressure in the pressure chamber 51 ′ decreases, and the pressure chamber 51 passes from the rod side chamber R 1 through the passage 60. The working gas flows into '.

Further, in this pneumatic shock absorber A3, in addition to the above, the pressure in the rod side chamber R1 rises during the extension operation, and becomes extremely small by the action of the throttle 62. While moving from the side chamber R 1 to the pressure chamber 51 ′, the pressure in the piston side chamber R 2 decreases, and the amount of working gas moves from the pressure chamber 51 ′ to the piston side chamber R 2 via the passage 61. Will do. That is, by repeating the expansion / contraction operation of the pneumatic shock absorber A3, the working gas circulates through the rod side chamber R1, the piston side chamber R2, and the pressure chamber 51 in order.

Therefore, the temperature change of the working gas in the cylinder 1 is easily transmitted to the pressure chamber 51 ′ by the circulation of the working gas due to the expansion / contraction operation of the pneumatic buffer A3, and the pressure change in the cylinder 1 due to the volume change of the working gas. Is suppressed by the volume change absorption mechanism 70 with high responsiveness, and the change in the rod reaction force of the pneumatic shock absorber A3 due to the volume change caused by the temperature change of the working gas is quickly mitigated by the volume change absorption mechanism 70. It becomes possible.

That is, a situation in which the vehicle height rises and falls due to the temperature change of the working gas in the cylinder 1 of the pneumatic shock absorber A3 is prevented, and the vehicle occupant feels uncomfortable and uncomfortable without exerting a posture change on the vehicle body. Therefore, the riding comfort in the vehicle can be improved.

Also, empty even in the pressure shock absorber A3, the configuration of the pressure chamber 51 'and the negative expansion member 52' definitive volume changes absorbing mechanism 70, pneumatic damper according to the embodiment of FIG. 2 in this reference example It goes without saying that the configuration of the pressure chamber 40 and the variable mechanism 41 of the volume change absorption mechanism 31 in A1 can be replaced.

Furthermore, in another modified example of the reference example described above, the directions of the check valve 63 and the check valve 65 may be reversed. That is, the check valve 63 is set so as to allow only the flow of working gas from the pressure chamber 51 ′ to the rod side chamber R1, and the check valve 65 is set only for the flow of working gas from the piston side chamber R2 to the pressure chamber 51 ′. It is possible to set so as to allow In this case, when the pneumatic shock absorber A3 is contracted, the pressure in the piston side chamber R2 rises, and a very small amount of working gas moves from the piston side chamber R2 to the pressure chamber 51 ′ via the passage 61. The pressure in R1 decreases, and a very small amount of working gas moves from the pressure chamber 51 ′ to the rod side chamber R1 via the passage 61. In this case, the expansion and contraction operation of the pneumatic shock absorber A3 is repeated. As a result, the working gas circulates through the rod-side chamber R1, the piston-side chamber R2, and the pressure chamber 51 in order, so that the temperature change of the working gas in the cylinder 1 is easily transmitted into the pressure chamber 51 ′.

The pneumatic shock absorber of the present invention is particularly suitable for vehicle suspension applications. However, even if the configuration of the pneumatic shock absorber of the present invention is embodied in addition to the vehicle shock absorber, the operational effects are not lost. Is natural.

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.

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Outer cylinder 3 Piston 4 Rod 5, 6 Path | pass as a piston path 7 Cylinder outer path 8 Head member 9 Bottom member 10, 11 Damping force generation element 12, 13, 19, 63, 65 Check valve 14 Bearing 15 Recess 15a Side wall portions 16, 17, 18 of the recesses Channels 16 a, 17 a Open end 20 of the channel Sealing member 21 Seal 22 Oil storage chamber 23 Rod and seal sliding portions 24, 25 Oil surface 26 Cylinder and piston sliding portion 30 , 31, 50, 70 Volume change absorption mechanism 40, 51, 51 ′ Pressure chamber 32, 53, 60, 61 Passage 33, 62, 64 Restriction 41 Variable mechanism 42 Housing 43 Free piston 44 Spring 52, 52 ′ Negative expansion body 55 Tube 56 Pipe A, A1, A2, A2 ', A3 Pneumatic shock absorber

Claims (6)

A bottom member that closes a lower end of a cylinder in a pneumatic shock absorber comprising a cylinder, a piston that divides the cylinder into a rod side chamber and a piston side chamber, and a rod that is movably inserted into the cylinder via the piston And a protrusion standing on the upper end of the bottom member, and a volume change absorption mechanism that absorbs the volume change of the working gas, the volume change absorption mechanism includes a pressure chamber communicated with the piston side chamber via a passage; An empty space comprising a throttle provided in the middle of the passage and a variable mechanism for changing the volume of the pressure chamber, wherein the passage is opened to the piston side chamber through the bottom member and the upper end of the protrusion. Pressure buffer. A pneumatic shock absorber comprising a cylinder, a piston that divides the inside of the cylinder into a rod-side chamber and a piston-side chamber, and a rod that is movably inserted into the cylinder through the piston absorbs volume changes of the working gas. A volume change absorption mechanism is provided, and the volume change absorption mechanism includes a pressure chamber communicated with the piston side chamber via a passage, a throttle provided in the middle of the passage, and a variable mechanism for changing the volume of the pressure chamber, The pneumatic shock absorber characterized in that the passage is opened through the inside of the rod to the piston side chamber. The pressure chamber is separated by a housing and a free piston that is slidably inserted into the housing, and the variable mechanism includes the free piston and a spring that urges the free piston in a direction that reduces the volume of the pressure chamber. The pneumatic shock absorber according to claim 1, wherein the pneumatic shock absorber is provided. The pneumatic shock absorber according to claim 1 or 2, wherein the pressure chamber is formed in an annular shape so as to cover an outer periphery of the cylinder. 5. The pneumatic shock absorber according to claim 1, wherein the variable mechanism includes a negative expansion body that is accommodated in the pressure chamber and negatively expands due to a temperature rise. 6. The pneumatic shock absorber according to claim 1, wherein the throttle is set so as to function as a low-pass filter having a time constant of 10 sec or more.

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