JP4535949B2 - Pneumatic shock absorber - Google Patents

Description

  The present invention relates to a shock absorber mounted on a vehicle or the like, and more particularly to an improvement of a pneumatic shock absorber that can be used as a suspension of a vehicle or the like.

  2. Description of the Related Art Conventionally, a pneumatic shock absorber includes a cylinder, a piston that is slidably inserted into the cylinder, and a rod that is movably inserted into the cylinder via the piston (for example, Patent Documents 1 and 2).

In this pneumatic shock absorber, a working chamber formed in a cylinder is divided into one chamber and the other chamber by a piston, gas is sealed as a working fluid in this working chamber, and when a damping force is generated, a hydraulic shock absorber and Similarly, one of the chambers or the other chamber is compressed with a piston so as to cause a difference between the one indoor pressure and the other indoor pressure.
JP 2004-132429 A JP 2004-132428 A

  Now, the pneumatic shock absorber as described above is a useful technique in that the weight of the shock absorber is reduced by using a gas as the working fluid, but there are the following problems.

  That is, when using a conventional pneumatic shock absorber as a vehicle suspension, it is necessary to secure a mounting length equivalent to that of a vehicle hydraulic shock absorber. It will be the same level.

  Then, as described above, the pneumatic shock absorber uses the working fluid as a gas, and the gas is rich in compressibility and has a small bulk elastic modulus. Therefore, the pneumatic shock absorber expands and contracts compared to a hydraulic shock absorber that uses working oil as the working fluid. The pressure increase in the one chamber or the other chamber to be compressed is delayed with respect to the volume change of the one chamber or the other chamber to be compressed at the time of operation.

  Therefore, the conventional pneumatic shock absorber has a problem that the generation of the required damping force is delayed as compared with the hydraulic shock absorber.

  Therefore, the present invention was devised to improve the above-described problems, and an object of the present invention is to provide a pneumatic shock absorber that does not delay the generation of damping force while ensuring the basic length. That is.

In order to achieve the above object, the means of the present invention includes a cylinder, a piston that is slidably inserted into the cylinder and that defines a working chamber formed in the cylinder into one chamber and the other chamber, and a piston. And a rod that is movably inserted into the cylinder, and is provided with a housing member that is housed in one or both of the one chamber and the other chamber and reduces the volume of the working chamber; and A gap is formed between the cylinder and the cylinder .
In this case, it is preferable that at least one accommodating member is provided in the vicinity of the piston on the outer periphery or the tip of the rod.
Similarly, at least one housing member may be fixed to the end side of the cylinder.

According to the pneumatic shock absorber of the present invention, the capacity of the working chamber can be reduced by the housing member. Therefore, even if the basic length is ensured to be mountable in the vehicle, the generation of the damping force is not delayed. .
Furthermore, since a gap is formed between the housing member and the cylinder, the flow of gas flowing between the one chamber and the other chamber during the expansion / contraction operation of the pneumatic shock absorber is not hindered.

  Further, in this pneumatic shock absorber, since the housing member is housed in the working chamber, the basic length is ensured and the delay in the generation of the damping force is avoided. Since it is not necessary to shorten the vertical length and further increase the vertical length of the rod, there is no need to design and manufacture a cylinder or rod as a special product for pneumatic shock absorbers. Since the rod can be used as it is, it is possible to reduce the cost of developing and manufacturing the pneumatic shock absorber.

  Therefore, in this pneumatic shock absorber, it is possible to secure the mountability in the vehicle and the riding comfort in the vehicle while reducing the cost.

  The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a schematic longitudinal sectional view of a pneumatic shock absorber. FIG. 2 is a schematic longitudinal sectional view of a pneumatic shock absorber according to a modification of the embodiment. FIG. 3 is a schematic longitudinal sectional view of a pneumatic shock absorber according to a modification of the embodiment. FIG. 4 is a schematic longitudinal sectional view of a pneumatic shock absorber according to another embodiment.

  As shown in FIG. 1, the pneumatic shock absorber K in one embodiment is divided into a cylinder 1 and a working chamber A formed in the cylinder 1 into a rod side chamber R1 that is one chamber and a piston side chamber R2 that is the other chamber. And a rod 3 that is movably inserted into the cylinder 1 via the piston 2.

  In the following, the cylinder 1 is formed in a cylindrical shape, and the upper and lower ends thereof are closed by the head member 5 and the bottom member 6, respectively, whereby the working chamber A is separated in the cylinder 1. Furthermore, the working chamber A is divided into a rod side chamber R1 and a piston side chamber R2 by a piston 2 slidably inserted into the cylinder 1.

  The piston 2 is connected to the rod 3 and is provided with passages 21 and 22 for communicating the rod-side chamber R1 and the piston-side chamber R2, and damping force generating elements 23 and 24 are provided in the middle of the passages 21 and 22. Is provided.

  Further, a check valve 25 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 21, and only a flow from the piston side chamber R2 to the rod side chamber R1 is provided in the middle of the passage 22. Is provided. Therefore, in the passage 21, the pneumatic shock absorber K is extended, that is, the passage of the fluid is allowed only when the rod 3 protrudes from the cylinder 1, and in the other passage 22, The fluid is allowed to pass only when the pneumatic shock absorber K is contracted, that is, when the rod 3 is moved into the cylinder 1.

  The damping force generating elements 23 and 24 are variable throttle valves as shown in the figure, and change the resistance applied to the fluid flow according to the expansion / contraction frequency and expansion / contraction speed of the pneumatic shock absorber K. Can be done. Note that the damping force generating elements 23 and 24 may be fixed throttle valves, leaf valves, or the like in addition to the variable throttle valves as long as they are suitable for a vehicle on which the pneumatic shock absorber K is mounted.

  An accommodation member M1 formed in an annular shape and accommodated in the rod-side chamber R1 is fixed on the outer periphery of the rod 3 and in the vicinity of the piston 2, and the accommodation member M1 is spaced from the cylinder 1 by a gap. Therefore, the diameter is smaller than the inner diameter of the cylinder 1.

  Therefore, a gap is formed between the housing member M1 and the cylinder 1, so that the flow of gas flowing between the rod side chamber R1 and the piston side chamber R2 during the expansion / contraction operation of the gap pneumatic shock absorber K is not hindered. . Here, considering the flow of the gas, a gap is not formed between the housing member M1 and the cylinder 1, and instead, the upper and lower ends thereof are set so that the gas flow can be allowed in the housing member M1. Although a communicating hole may be provided, in this case, since the processing cost of the accommodation member M1 increases and the sliding portion increases, a clearance is provided between the accommodation member M1 and the cylinder 1. It is more advantageous to place it.

In addition, as a material of the housing member M1, specifically, for example, metal or synthetic resin may be used. However, if possible, it is preferable to use a material whose volume change is small with respect to the pressure change in the rod side chamber R1. The interior may be hollow.
Further, the accommodating member M1 may be formed integrally with the rod 3 by expanding the outer periphery of the rod 3, but it is configured to be fixed to the outer periphery of the rod 3 as in the above embodiment. Since the rod 3 does not need to be a special product, it is possible to reduce the cost of manufacturing the pneumatic shock absorber in this respect as well.

  Further, since the housing member M1 is provided on the outer periphery of the rod 3 and in the vicinity of the piston 2, the influence of the housing member M1 on the stroke length of the pneumatic shock absorber is kept to a minimum.

  In turn, the head member 5 is formed in an annular shape, and on the inner peripheral side thereof is provided with a bearing 51 that pivotally supports the rod 3 and is provided with a recess 52 that opens from the upper end side.

  And the above-mentioned cylinder 1 is covered with the bottomed cylindrical outer cylinder 10 arrange | positioned on the outer side of the cylinder 1, The bottom member 6 is fitted by the bottom part of this outer cylinder 10, A sealing member 11 that holds an annular seal S on the inner peripheral side is fixed to the head member 5 at an opening end that is the upper end of the outer cylinder 10 in the figure.

  In the sealing member 11 described above, the axial length that is the vertical length in FIG. 1 is set shorter than the axial length that is the vertical length of the annular seal S, and the annular seal S is sealed. The stopper member 11 is held by the sealing member 11 so as to protrude from the lower end of the stopper member 11 toward the inside of the cylinder 1. In the above description, the sealing member 11 holds the annular seal S. However, the annular seal S may be welded to the sealing member 11 so as not to be separated.

  The lower end of the annular seal S protruding from the sealing member 11 is disposed in the recess 52 of the head member 5, and the oil storage chamber T is separated by the recess 52 and the sealing member 11.

  A rod 3 that protrudes from the cylinder 1 and is slidably inserted into the bearing 51 of the head member 5 is inserted on the inner peripheral side of the annular seal S. The annular seal S is inserted into the rod 3 with a predetermined compression force. It is press-contacted to the outer periphery.

  Therefore, the rod 3 passes through the oil storage chamber T, and this oil storage chamber T faces the sliding contact portion between the rod 3 and the annular seal S.

  Further, the oil storage chamber T is communicated with the rod side chamber R <b> 1 by a passage 53 provided in the head member 5, and is communicated with a gap B between the cylinder 1 and the outer cylinder 10 by a passage 54.

  Here, the end 53a of the passage 53 on the oil storage chamber T side opens from the side wall 52a of the recess 52, and the end 53a is positioned at least above the lowermost end of the annular seal S in the drawing. Is set to Further, a check valve 55 that allows only the flow of fluid from the oil storage chamber T to the rod side chamber R1 is provided in the middle of the passage 53.

  On the other hand, the bottom member 6 is provided with a passage 61 that connects the piston-side chamber R2 and the gap B. In the middle of the passage 61, a check that allows only the flow of fluid from the piston-side chamber R2 toward the gap B is provided. A valve 62 is provided.

  Therefore, the oil storage chamber T is communicated with the piston side chamber R2 via the passage 54, the gap B, and the passage 61 described above.

  Further, a protrusion 63 is provided at the upper end of the bottom member 6, and an accommodation member M <b> 2 that is accommodated in the piston side chamber R <b> 2 is provided at the tip of the protrusion 63. That is, the accommodating member M2 is provided on the end side of the cylinder 1 and has a diameter smaller than the inner diameter of the cylinder 1 so as to form a gap with the cylinder 1.

  Therefore, a gap is formed between the housing member M2 and the cylinder 1 so that the flow of gas passing through the passage 61 during the expansion / contraction operation of the gap pneumatic shock absorber K is not hindered.

  As the material of the housing member M2, specifically, for example, metal, synthetic resin, or the like may be used. However, if possible, the material having a small volume change with respect to the pressure change in the piston side chamber R2 is used. The interior may be hollow.

  The housing member M2 may be formed integrally with the bottom member 6. However, since the bottom member 6 does not need to be a special product by being configured to be fixed to the bottom member 6, the pneumatic member It is possible to reduce the cost of manufacturing the shock absorber.

  Further, since the housing member M2 is provided on the end side of the cylinder 1, the influence of the housing member M2 on the stroke length of the pneumatic shock absorber is kept to a minimum.

  In turn, the cylinder 1 is filled with working gas, the oil storage chamber T is filled with oil, and the oil level O of the oil in the oil storage chamber T is below the lowermost end of the annular seal S. In consideration of the fact that the oil does not fall down, the gap B is filled with a sufficient amount of oil.

  The rod side chamber R1 and the piston side chamber R2 are also filled with a small amount of oil. However, the oil filled in the rod side chamber R1 is used when the pneumatic shock absorber performs expansion and contraction for the first time. This is because the oil in the piston side chamber R2 prevents the oil level O in the oil storage chamber T from dropping when the pneumatic shock absorber is contracted.

  Next, the operation of the pneumatic shock absorber K configured as described above will be described. First, when the pneumatic shock absorber K 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 21. During this movement, the gas passes through the damping force generating element 23, 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, the volume in the working chamber A is reduced by the housing members M1, M2, and the pressure change in the working chamber A when the pneumatic shock absorber is extended is inversely proportional to the volume of the working chamber A. The pressure in the rod side chamber R1 rises more rapidly than in the state without M1 and M2, and the pressure in the piston side chamber R2 quickly decreases. Therefore, even if the lengths of the cylinder 1 and the rod 3 are equal to those of the hydraulic shock absorber, the pressure increase in the rod side chamber R1 and the pressure drop in the piston side chamber R2 are accelerated by the housing members M1 and M2, so that the damping force Similarly, the occurrence of is faster than the conventional pneumatic shock absorber.

  Further, since the oil in the rod side chamber R1 is heavier than the gas and accumulated in the opening of the passage 21, the oil also moves into the piston side chamber R2 together with the gas.

  The oil in the rod side chamber R1 has a role of lubricating between the cylinder 1 and the piston 2 as described above, but passes through the damping force generating element 23 ahead of the gas, so the rod side chamber R1. This will prompt a rapid increase in pressure.

  Subsequently, when the pneumatic shock absorber K 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 via the passage 22. . During this movement, since the gas passes through the damping force generating element 24, 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, the gas in the piston side chamber R <b> 2 flows into the oil storage chamber T through the passage 54, the gap B and the passage 61 due to the pressure increase in the piston side chamber R <b> 2.

  At this time, the volume in the working chamber A is reduced by the housing members M1, M2, and the pressure change in the working chamber A when the pneumatic shock absorber contracts is inversely proportional to the volume of the working chamber A. The pressure in the piston side chamber R2 rises more rapidly and the pressure in the rod side chamber R1 decreases more quickly than in the state without M1 and M2. Therefore, even if the length of the cylinder 1 or the rod 3 is equivalent to that of the hydraulic shock absorber, the pressure drop in the rod side chamber R1 and the pressure rise in the piston side chamber R2 are accelerated by the housing members M1 and M2, so that the damping force Similarly, the occurrence of is faster than the conventional pneumatic shock absorber.

  That is, in this pneumatic shock absorber K, the capacity of the working chamber A can be reduced by the accommodating members M1 and M2, so that the damping force is generated even if the basic length is ensured to be mountable on the vehicle. There is no delay.

  Further, in the present pneumatic shock absorber K, since the housing members M1 and M2 are housed in the working chamber A, the basic length is ensured and the generation delay of the damping force is avoided. Therefore, it is not necessary to shorten the vertical length of the cylinder 1 in the drawing and further increase the vertical length of the rod 3 in the drawing. Therefore, the cylinder 1 and the rod 3 are newly added as special products for the pneumatic shock absorber. Therefore, it is possible to reduce the cost of development and production of the pneumatic shock absorber because it is possible to use the cylinder and rod for the hydraulic shock absorber as they are.

  Therefore, in this pneumatic shock absorber K, it is possible to secure the mountability in the vehicle and the riding comfort in the vehicle while reducing the cost.

Further, when the housing members M1 and M2 described above are formed hollow, it is possible to reduce the weight of the pneumatic shock absorber K, and it is difficult to transmit the vibration of the unsprung member of the vehicle to the sprung member. It is possible to improve the ride comfort.
When the pneumatic shock absorber K is contracted, the oil in the piston side chamber R2 passes through the passage 61 ahead of the gas because the oil is heavier than the gas and accumulates in the opening of the passage 61. As a result, the pressure in the piston side chamber R2 is promptly increased.

  Since the oil storage chamber T is pressurized in the same manner as the piston side chamber R2, the oil level O of the oil in the oil storage chamber T rises, and the oil level O rises and the pressure in the oil storage chamber T rises. Accordingly, the oil in the oil storage chamber T passes through the passage 53 and flows into the rod side chamber R1 together with the gas. Here, since the opening position of the end portion 53a of the passage 53 is located above the lowermost end of the annular seal S, the oil storage chamber T even if the oil moves from the oil storage chamber T into the rod side chamber R1 as described above. The oil level O of the inner oil is always located above the lowermost end of the annular seal S, and the oil in the oil storage chamber T continues to maintain the lubrication of the sliding contact portion between the rod 3 and the annular seal S. .

  Therefore, even if the pneumatic shock absorber K repeatedly expands and contracts, the oil in the oil storage chamber T continues to maintain the lubrication of the sliding contact portion between the rod 3 and the annular seal S, and is formed upright. The sliding portion of the rod 3 of the pneumatic shock absorber K is surely lubricated.

  Further, by providing an oil storage chamber facing the sliding contact portion of the rod 3 and positioning the oil surface above the lowermost end of the sliding contact portion, the sliding portion can be reliably lubricated, so that the structure is complicated. Therefore, the pneumatic shock absorber can be made upright without significant cost increase.

  When the pneumatic shock absorber K continues to expand and contract, the oil in the pneumatic shock absorber K circulates through the rod side chamber R1, the piston side chamber R2, and the oil storage chamber T, and the sliding portion of the pneumatic shock absorber K, that is, The sliding portion between the cylinder 1 and the piston 2 and the sliding portion of the rod 3 and the annular seal S are continuously lubricated.

  That is, in this pneumatic shock absorber K, the oil circulation can prevent the oil in the rod side chamber R1 from being lost, and the sliding portion between the cylinder 1 and the piston 2 can be lubricated. In combination with the lubrication of the sliding portion, the pneumatic buffer K can be smoothly extended and contracted, the manual resistance can be reduced, and the riding comfort in the vehicle can be improved. The durability of K can be improved.

  In the above description, the accommodating member M1 is accommodated in the rod-side chamber R1 that is one chamber, and the accommodating member M2 is accommodated in the piston-side chamber R2 that is the other chamber. Like the pneumatic shock absorbers K2 and K3 in the modification of the embodiment, even if one of the housing members M1 and M2 is eliminated, the total volume in the rod side chamber R1 and the piston side chamber R2 can be reduced. However, as with the pneumatic shock absorber K of the above-described embodiment, the basic length can be ensured and the damping force can be generated promptly.

  In addition, in the pneumatic shock absorbers K1 and K2 in the other embodiments, only one housing member is required, so that the manufacturing cost of the pneumatic shock absorber can be further reduced.

  In the pneumatic shock absorber K2 shown in FIG. 3 in which only the housing member M2 is provided, the housing member M2 does not move with respect to the cylinder 1, and therefore interferes with the cylinder 1 during the expansion / contraction operation. There is no danger, and in this respect, there is no hindrance to the smooth telescopic operation of the pneumatic shock absorber K2.

  Further, as shown in the pneumatic shock absorber K3 in the other embodiment shown in FIG. 4, the housing member M3 is fixed to the tip of the rod 3 and housed in the piston side chamber R2, and the rod 3 is inserted. The housing member M4 may be fixed to the head member 5.

  In this case, in the housing member M3, consideration is given to not hindering the flow of gas flowing between the rod-side chamber R1 and the piston-side chamber R2, specifically, a consideration that a gap is formed between the housing member M3 and the cylinder 1. In addition, consideration is given not to block the passage 53 even in the housing member M4.

  Even with this configuration, the volume in the working chamber A is reduced, so that the basic length can be secured and the damping force can be generated promptly as in the case of the pneumatic shock absorber K in the embodiment. is there.

  Of course, it is possible that one of the housing members M3 and M4 may be eliminated. Even in such a case, the above-mentioned effect is not lost, and only one housing member is required. Manufacturing costs can be further reduced.

  Further, the housing member M3 of the pneumatic buffer K3 can be applied to the configuration of the pneumatic shock absorber K1, and the housing member M4 of the pneumatic buffer K3 is applied to the configuration of the pneumatic buffer K2. It is also possible. In addition, the pneumatic shock absorber described above is configured as a so-called single rod type shock absorber, but may be configured as a double rod type shock absorber, ensuring the above-described basic length. And the effect of prompt generation of damping force is not lost. Furthermore, the pneumatic shock absorber of the present embodiment employs a structure in which a small amount of oil is circulated to the one chamber, the other chamber and the oil storage chamber, particularly in consideration of lubrication of the sliding portion. The structure is not limited to this.

  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 a schematic longitudinal cross-sectional view of the pneumatic shock absorber in one embodiment. It is a schematic longitudinal cross-sectional view of the pneumatic shock absorber in the modification of one embodiment. It is a schematic longitudinal cross-sectional view of the pneumatic shock absorber in the modification of one embodiment. It is a schematic longitudinal cross-sectional view of the pneumatic shock absorber in other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 21,22,53,54,61 Passage 23,24 Damping force generation | occurrence | production element 25,26 Check valve 3 Rod 5 Head member 51 Bearing 52 Recessed part 53a End part 55,62 Check valve 6 Bottom member 10 outer cylinder 11 sealing member A working chamber B gap K, K1, K2, K3 pneumatic buffer M1, M2, M3, M4 storage member O oil level R1 of oil in oil storage chamber rod side chamber R2 as one chamber, other chamber Piston side chamber S Annular seal member T Oil storage chamber

Claims (3)

A cylinder, a piston that is slidably inserted into the cylinder and divides a working chamber formed in the cylinder into one chamber and the other chamber, and a rod that is slidably inserted into the cylinder via the piston. In the pneumatic shock absorber provided , a housing member that is housed in one or both of the one chamber and the other chamber to reduce the volume of the working chamber is provided , and a gap is formed between the housing member and the cylinder. Pneumatic shock absorber.     The pneumatic shock absorber according to claim 1, wherein the at least one housing member is provided in the vicinity of the piston on the outer periphery or the tip of the rod.     The pneumatic shock absorber according to claim 1, wherein at least one housing member is fixed to an end portion side of the cylinder.

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