JP2021081025A - Buffer - Google Patents

Abstract

To provide a buffer capable of easily changing spring characteristic of a gas spring according to a stroke speed, as in a conventional buffer, it is difficult to change the spring characteristic of the gas spring according to the stroke speed as a liquid level cannot be adjusted during an operation of the buffer, through the desired spring characteristic is obtained by adjusting a compression ratio of a gas chamber constituting the gas spring by adjusting the liquid level of a liquid storage chamber.SOLUTION: A buffer is formed in an expandable/contractible tuber member T having an outer tube 1 and an inner tube 2, and includes a gas chamber G of which a volume is changed by expansion and contraction of the tube member T, and an auxiliary gas chamber g1 communicated to the gas chamber G through an orifice 6a.SELECTED DRAWING: Figure 1

Description

The present invention relates to improvements in shock absorbers.

Conventionally, for example, a shock absorber used for a front fork that suspends the front wheels of a motorcycle includes an outer tube, an inner tube that goes in and out of the outer tube, and a stretchable tube member, and the inside of the tube member. There is a shock absorber body which is arranged in the above and expands and contracts as the tube member expands and contracts, gives resistance to the flow of liquid generated during the expansion and contraction, and exerts the main damping force due to the resistance.

A liquid storage chamber is formed between the tube member of such a shock absorber and the shock absorber main body, and an air chamber in which liquid is stored in this liquid storage chamber and gas is sealed on the upper side of the liquid surface. Is formed. The volume of this air chamber changes according to the expansion and contraction of the tube member, and the gas spring is formed by having this air chamber. Then, this gas spring exerts a spring force according to the contraction amount of the tube member, that is, the stroke amount of the shock absorber.

Japanese Unexamined Patent Publication No. 2004-286197, paragraph [0051]

Here, assuming that the entire air chamber constituting the gas spring is a gas spring chamber, the spring characteristics (characteristics of the spring force with respect to the amount of compression) of the gas spring are determined by the compression ratio of the gas spring chamber, and in the above-mentioned conventional shock absorber. , The compression ratio can be adjusted by changing the liquid level position (liquid volume) of the liquid storage chamber. Therefore, in the conventional shock absorber, the liquid level of the liquid reservoir is adjusted so that the compression ratio of the gas spring chamber becomes a compression ratio that can realize the desired spring characteristics. The spring characteristics cannot be changed.

Therefore, an object of the present invention is to provide a shock absorber capable of changing the spring characteristics of a gas spring according to a stroke speed.

The shock absorber that solves the above problems includes a tube member that has an outer tube and an inner tube and can be expanded and contracted, an air chamber that is formed in the tube member and whose volume changes due to expansion and contraction of the tube member, and this air chamber. And an auxiliary air chamber that communicates through an orifice. According to this configuration, at least the air chamber becomes a gas spring chamber, and the gas spring composed of the gas spring chamber exerts a spring force according to the stroke amount of the shock absorber.

Further, according to the above configuration, when the stroke speed of the shock absorber is low, the gas moves relatively freely between the air chamber and the secondary air chamber through the orifice, so that the air chamber and the secondary air are relatively free to move. The room behaves like a series of rooms. Therefore, at low speeds, the portion (room) in which the air chamber and the secondary air chamber are substantially combined becomes the gas spring chamber. On the other hand, when the stroke speed of the shock absorber is high, the resistance when the gas passes through the orifice becomes large, and the air chamber and the secondary air chamber behave as if they are separate rooms. Therefore, at high speed, the auxiliary air chamber is substantially separated from the gas spring chamber, and the volume of the gas spring chamber is reduced by that amount.

As a result, the compression ratio of the gas spring chamber becomes larger at high speed than at low speed, and the spring characteristics of the gas spring change accordingly. Therefore, according to the above configuration, the spring characteristics of the gas spring are adjusted according to the stroke speed. Can be changed.

Further, the shock absorber includes a shock absorber body arranged in a tube member, and the shock absorber body has a cylinder and a rod which is inserted into the cylinder so as to be movable in the axial direction. The air chamber may be formed between the tube member and the shock absorber body while being interposed between the inner tube and the inner tube. When the present invention is applied to such a shock absorber, when the shock absorber tries to contract most while the stroke speed is high, a large spring force of the gas spring that resists the contraction can be obtained, so that the impact at the time of maximum contraction can be obtained. Can be relaxed.

Further, in the above shock absorber, the cylinder is connected to the tube arranged on the upper side of the outer tube and the inner tube, and the auxiliary air chamber is formed between the tubular housing and the cylinder arranged on the outer periphery of the cylinder. The orifice may be formed between them and the orifice may be opened to the side of the housing. In this way, the auxiliary air chamber is arranged in the tube member, so that the shock absorber can be miniaturized. Further, since the secondary air chamber can be arranged at the upper part in the tube member, even if the air chamber is formed above the liquid level of the liquid stored in the tube member, the air chamber and the secondary air chamber are separated by an orifice. Can be easily communicated. In addition, since the orifice opens to the side of the housing, it is possible to prevent the liquid in the tube member from entering the housing through the orifice.

Further, the shock absorber may be provided with a check valve that allows only the flow of fluid from the secondary air chamber to the air chamber. In this way, the orifice can be made one-sided. Furthermore, even if the liquid enters the secondary air chamber, the liquid that has entered the secondary air chamber can be discharged through the check valve.

Further, in the above shock absorber, an annular valve case portion located on the outer periphery of the cylinder and accommodating a check valve is provided at the lower end portion of the housing, and the valve case portion is arranged in double inside and outside. An inner cylinder portion and an outer cylinder portion and a connecting portion connecting the upper ends thereof are included, and a port that penetrates vertically through the connecting portion and leads to an auxiliary air chamber is formed, and a check valve is annular and the connecting portion is formed. It may be arranged between the inner cylinder portion and the outer cylinder portion protruding downward from the. In this way, when the check valve is opened, the liquid that has entered the secondary air chamber passes downward between the port and the inner cylinder and outer cylinder, so that the liquid that has entered the secondary air chamber Can be easily discharged.

Further, in the above shock absorber, the check valve may be urged in the opening direction by a spring. Even in this case, the liquid in the secondary air chamber is easily discharged.

According to the shock absorber according to the present invention, the spring characteristics of the gas spring can be changed according to the stroke speed.

It is a vertical cross-sectional view which showed the shock absorber which concerns on 1st Embodiment of this invention in a simplified manner. It is a vertical sectional view which showed a part of the shock absorber which concerns on 2nd Embodiment of this invention. It is an enlarged view which showed the part of FIG. 2 enlarged. It is explanatory drawing explaining the procedure of assembling the housing in the shock absorber which concerns on 2nd Embodiment of this invention.

Hereinafter, the shock absorber according to the embodiment of the present invention will be described with reference to the drawings. The same reference numerals, given throughout several drawings, indicate the same part (part) or the corresponding part (part).

<First Embodiment>
The shock absorber A1 according to the first embodiment of the present invention shown in FIG. 1 is used for a front fork that suspends the front wheels of a saddle-type vehicle such as a motorcycle. In the following description, "upper" and "lower" when the front fork including the shock absorber A1 is attached to the vehicle are simply referred to as "upper" and "lower" unless otherwise specified. Needless to say, the shock absorber according to the present invention may be used for vehicle suspensions other than the front fork, and the purpose of use of the shock absorber can be changed as appropriate.

As shown in FIG. 1, the shock absorber A1 according to the present embodiment includes an outer tube 1 and an inner tube 2 slidably inserted into the outer tube 1 in the axial direction. A telescopic tube member T is provided. The tube member T is an inverted type in the present embodiment, and is attached to the vehicle with the outer tube 1 facing upward on the vehicle body side and the inner tube 2 facing downward on the front wheel (wheel) side.

More specifically, a bracket (not shown) on the vehicle body side is attached to the outer circumference of the outer tube 1 which is the tube on the vehicle body side, and the steering shaft fixed to this bracket is rotatably supported in the head pipe of the vehicle body. Will be done. On the other hand, a wheel-side bracket 20 is attached to the lower end of the inner tube 2 serving as the wheel-side tube, and the bracket 20 is connected to the axle of the front wheel. In this way, the tube member T is interposed between the vehicle body and the axles of the front wheels.

Then, when the front wheels vibrate up and down as the vehicle travels on an uneven road surface, the inner tube 2 moves in and out of the outer tube 1 and the tube member T expands and contracts. The expansion and contraction of the tube member T in this way is also referred to as the expansion and contraction of the shock absorber A1 or the stroke. The tube member T is upright and may be attached to the vehicle with the outer tube 1 facing downward (wheel side) and the inner tube 2 facing upward (vehicle body side). In this way, the style of the tube member T and the mounting state on the vehicle can be changed as appropriate.

Subsequently, the upper end of the outer tube 1 which is the upper end of the tube member T is closed by the cap 10. On the other hand, the lower end of the inner tube 2 which is the lower end of the tube member T is closed by the bracket 20 on the wheel side. Further, an annular sealing member (not shown) that slides into the outer periphery of the inner tube 2 is attached to the lower end of the outer tube 1 to form a tubular gap between the overlapping portion of the outer tube 1 and the inner tube 2. The lower end of the is closed with the sealing member. In this way, the inside of the tube member T is sealed.

In the tube member T, a shock absorber main body D is housed in the central portion thereof along the axial direction, and a suspension spring Sm is housed between the shock absorber body D and the tube member T. A liquid storage chamber R is formed between the tube member T in which the suspension spring Sm is housed and the shock absorber main body D. In the liquid storage chamber R, a liquid such as hydraulic oil is stored, and an air chamber G in which a gas such as air is sealed is formed above the liquid surface r1.

The shock absorber body D includes a cylinder 3, a piston 4 movably inserted into the cylinder 3, and a piston rod 40 having one end connected to the piston 4 and the other end protruding outside the cylinder 3. And. The shock absorber main body D is an inverted type in the present embodiment, the cylinder 3 is arranged on the upper side (vehicle body side) of the piston rod 40, the upper end of the cylinder 3 is connected to the cap 10, and the shock absorber main body D protrudes to the outside of the cylinder 3. The lower end of the piston rod 40 is connected to the bracket 20 on the wheel side.

As described above, since the cap 10 is attached to the outer tube 1 and the bracket 20 on the wheel side is attached to the inner tube 2, the shock absorber body D is placed between the outer tube 1 and the inner tube 2. It can be said that it is being mediated. Then, when the shock absorber A1 in which the inner tube 2 moves in and out of the outer tube 1 expands and contracts, the piston rod 40 moves in and out of the cylinder 3 and the piston 4 moves up and down (axially) in the cylinder 3.

An annular rod guide 30 is attached to the lower end of the cylinder 3. The piston rod 40 is inserted inside the rod guide 30 so as to be movable in the axial direction, and enters and exits the cylinder 3 while being supported by the rod guide 30. Further, a valve case 5 is fixed inside the cylinder 3 and above the piston 4, and the space between the valve case 5 and the rod guide 30 is partitioned by the piston 4 into an extension side chamber L1 and a compression side chamber L2. ing.

The extension side chamber L1 and the compression side chamber L2 are each filled with a liquid such as hydraulic oil. The extension side chamber referred to here is the chamber of the two chambers partitioned by the piston in the cylinder of the shock absorber, which is compressed by the piston when the shock absorber is extended, and in the present embodiment, the piston 4 is used. Located on the lower side. On the other hand, the compression side chamber is the chamber that is compressed by the piston when the shock absorber contracts, out of the two chambers that are partitioned by the piston in the cylinder of the shock absorber. Located on the upper side.

The piston 4 is formed with an extension side passage 4a and a compression side passage 4b that communicate the extension side chamber L1 and the compression side chamber L2, and is attached with an extension side valve 41 and a compression side valve 42 that open and close each of them. The extension valve 41 is a damping element on the extension side and opens and closes the extension side passage 4a, and opens when the shock absorber A1 is extended to prevent the extension side passage 4a from flowing liquid from the extension side chamber L1 to the compression side chamber L2. give away. On the other hand, the compression side valve 42 is a pressure side check valve that opens and closes the compression side passage 4b and opens when the shock absorber A1 contracts to allow the compression side passage 4b to flow liquid from the compression side chamber L2 to the extension chamber L1.

Subsequently, the valve case 5 is attached to the tip of the holding rod 50 extending from the cap 10 into the cylinder 3. An annular free piston 31 is mounted between the holding rod 50 and the cylinder 3. The free piston 31 is inside the cylinder 3 and divides the valve case 5 and the cap 10 into a lower liquid chamber L3 and an upper spring accommodating chamber H. Then, the free piston 31 is urged downward, that is, toward the liquid chamber L3 by the urging spring 32 housed in the spring accommodating chamber H.

The liquid chamber L3 is partitioned from the compression side chamber L2 by a valve case 5, and the inside thereof is filled with the same liquid as the extension side chamber L1 and the compression side chamber L2. On the other hand, the spring accommodating chamber H accommodating the urging spring 32 is communicated with the air chamber G by the through hole 3a formed in the upper part of the cylinder 3, and the gas passes through the through hole 3a to form the spring accommodating chamber H. You can freely go back and forth between the air chamber G and the air chamber G. That is, the spring accommodating chamber H inside the cylinder 3 is a continuous chamber with the air chamber G outside the cylinder 3, and in the following description, these are collectively referred to as “air chamber G”.

The valve case 5 is formed with a suction passage 5a and a discharge passage 5b that communicate the compression side chamber L2 and the liquid chamber L3, and is provided with a suction valve 51 and a damping valve 52 that open and close each of them. The suction valve 51 is a check valve on the extension side, opens and closes the suction passage 5a, and opens when the shock absorber A1 is extended to allow the suction passage 5a to flow liquid from the liquid chamber L3 to the compression side chamber L2. On the other hand, the damping valve 52 is a damping element on the compression side and opens and closes the discharge passage 5b, and opens when the shock absorber A1 contracts to open the discharge passage 5b to resist the flow of liquid from the compression side chamber L2 to the liquid chamber L3. ..

According to the above configuration, when the shock absorber A1 in which the piston rod 40 exits the cylinder 3 is extended, the piston 4 moves downward in the cylinder 3 to compress the extension side chamber L1. Then, the liquid in the extension side chamber L1 opens the extension side valve 41 and moves to the compression side chamber L2 through the extension side passage 4a. A resistance is imparted to the flow of the liquid by the extension valve 41, and the shock absorber A1 exerts the main damping force on the extension side due to the resistance. Further, when the shock absorber A1 is extended, the suction valve 51 opens, and the liquid corresponding to the volume of the piston rod discharged from the cylinder 3 is supplied from the liquid chamber L3 to the compression side chamber L2 through the suction passage 5a. Then, the free piston 31 advances toward the liquid chamber L3 side according to the urging force of the urging spring 32.

On the contrary, when the shock absorber A1 in which the piston rod 40 enters the cylinder 3 contracts, the piston 4 moves upward in the cylinder 3 to compress the compression side chamber L2. Then, the liquid in the compression side chamber L2 opens the compression side valve 42 and moves to the extension side chamber L1 through the compression side passage 4b. Further, the liquid in the compression side chamber L2 opens the damping valve 52, and the liquid corresponding to the volume of the piston rod that has entered the cylinder 3 is discharged to the liquid chamber L3 through the discharge passage 5b. A resistance is provided by the damping valve 52 to the flow of the liquid, and the shock absorber A1 exerts the main damping force on the compression side due to the resistance. Further, when the liquid is discharged from the compression side chamber L2 to the liquid chamber L3 in this way, the free piston 31 retreats to the cap 10 side against the urging force of the urging spring 32.

As described above, the free piston 31 is urged downward (on the liquid chamber L3 side) by the urging spring 32, whereby the liquid chamber L3 is pressurized. The liquid chamber L3 communicates with the compression side chamber L2 via the passage of the valve case 5, and the compression side chamber L2 communicates with the extension chamber L1 through the passage of the piston 4, so that the urging spring 32 and the free piston 31 Pressurizes the entire liquid in the cylinder 3. In other words, the urging spring 32 and the free piston 31 form a pressurizing mechanism that pressurizes the liquid in the cylinder 3. Since the shock absorber A1 of the present embodiment includes the pressurizing mechanism, the rigidity of the liquid column in the cylinder 3 is increased, and the main damping force generation responsiveness is improved.

Further, in the shock absorber A1 of the present embodiment, when the amount of retreat of the free piston 31 in the direction of compressing the urging spring 32 becomes larger than a predetermined value, the liquid in the liquid chamber L3 is passed through the liquid passage hole 3a to the liquid storage chamber R. It is equipped with a relief mechanism that allows it to escape to. As a result, even when the shock absorber A1 is provided with a pressurizing mechanism for pressurizing the liquid in the cylinder 3, the pressure in the cylinder 3 is prevented from becoming excessive. Although the urging spring 32 shown in FIG. 1 is a coil spring, a mechanical spring other than the coil spring such as a disc spring or a leaf spring, or a gas spring may be used as the urging spring 32. Further, the relief mechanism may be omitted. In such a case, a bladder, bellows or the like may be used instead of the free piston to separate the gas and liquid.

Further, the valve structure of the shock absorber main body D can be changed as appropriate. For example, in the present embodiment, the compression side valve 42 provided in the compression side passage 4b is a check valve. However, the compression side valve 42 may be a damping element. Further, in FIG. 1, the damping element is a valve that opens and closes the passage. As this valve, various valves such as a leaf valve and a poppet valve can be used, of course, and the damping element may be a normally open type orifice or a combination of the orifice and the valve.

Further, the style of the shock absorber main body D can be changed as appropriate. For example, in the present embodiment, the shock absorber main body D is a single rod type, the piston rod 40 extends from one side of the piston 4 to the outside of the cylinder 3, and the liquid chamber L3 and the spring accommodating chamber H enter and exit the cylinder 3. It constitutes a reservoir chamber that compensates for the piston rod volume integral. The reservoir chamber is provided in the cylinder 3 and is separated from the compression side chamber L2 by the valve case 5. However, instead of the reservoir chamber, the volume of the piston rod that goes in and out of the cylinder may be compensated in the expandable gas chamber. In such a case, the valve case 5, the suction valve 51, and the damping valve 52 are omitted. it can.

Further, in the present embodiment, the shock absorber main body D is an inverted type, the cylinder 3 is arranged on the upper side (vehicle body side), and the piston rod 40 is arranged on the lower side (wheel side). However, the shock absorber body may be upright, the cylinder may be arranged on the lower side (wheel side), and the piston rod may be arranged on the upper side (vehicle body side). In such a case, the shock absorber body and the tube member may be arranged. The liquid storage chamber formed between the and may be used as a reservoir chamber. As described above, the reservoir chamber for compensating the volume of the piston rod entering and exiting the cylinder can be arranged inside or outside the cylinder, and may be further outside the tube member. The same applies to the case of volume compensation in the gas chamber.

Further, the shock absorber body may be a double-rod type, and the piston rods may extend from both sides of the piston to the outside of the cylinder. In such a case, the volume compensation itself of the piston rods entering and exiting the cylinder becomes unnecessary. Furthermore, the shock absorber body according to the present invention does not necessarily have to be a hydraulic shock absorber that exerts a damping force by giving resistance to the flow of liquid generated when the shock absorber expands and contracts, and utilizes frictional force, electromagnetic force, and the like. It may be one that exerts a damping force.

Subsequently, an annular lock piece 33 is provided at the lower end of the cylinder 3 inserted into the inner tube 2. Further, the bracket 20 on the wheel side, which functions as a bottom cap for closing the lower end of the tube member T, is provided with a tubular lock case 21 at a position facing the lock piece 33. The lock case 21 is located at a position lower than the liquid level r1 of the liquid storage chamber R, and is provided in a state of being immersed in the liquid.

Then, when the amount of contraction of the shock absorber A1 becomes large and the lower end of the cylinder 3 approaches the bracket 20 on the wheel side, the lock piece 33 is inserted into the lock case 21. Then, the inside and outside of the lock case 21 are partitioned by the lock piece 33, and the liquid is confined in the lock case 21, that is, the hydraulic pressure is locked. Due to the hydraulic pressure locking effect, the shock absorber A1 stops the contraction operation, and the impact at the time of the maximum contraction of the shock absorber A1 is alleviated.

As described above, in the present embodiment, the lock piece 33 and the lock case 21 form a hydraulic lock mechanism to alleviate the impact of the shock absorber A1 at the time of maximum contraction. The hydraulic lock mechanism of the present embodiment is arranged in the liquid storage chamber R, but the arrangement can be freely changed. For example, the hydraulic lock mechanism may be arranged in the cylinder 3. Further, in the present embodiment, the hydraulic lock mechanism is used to alleviate the impact of the shock absorber A1 at the time of maximum contraction, but it may be used to alleviate the impact at the time of maximum extension.

Subsequently, the suspension spring Sm housed in the liquid storage chamber R is a coil spring. The upper end of the suspension spring Sm is supported by a spring receiver 34 mounted on the outer circumference of the cylinder 3. On the other hand, the lower end of the suspension spring Sm is supported by the wheel-side bracket (bottom cap) 20 that closes the lower end of the inner tube 2. As described above, the suspension spring Sm is interposed between the cylinder 3 and the inner tube 2, and when the cylinder 3 moves in and out of the inner tube 2 when the shock absorber A1 expands and contracts, the suspension spring Sm expands and contracts and compresses. Demonstrates spring force according to the amount. Since the spring force of the suspension spring Sm urges the shock absorber A1 in the extension direction and acts in the direction of pushing up the vehicle body, the suspension spring Sm can elastically support the vehicle body.

Further, the air chamber G formed in the tube member T expands when the shock absorber A1 is extended and contracts when the shock absorber A1 contracts. As described above, the volume of the air chamber G changes with the expansion and contraction of the shock absorber A1, and the gas spring Se has the air chamber G. Similar to the suspension spring Sm, the spring force of the gas spring Se also urges the shock absorber A1 in the extension direction and acts in the direction of pushing up the vehicle body. As a result, in the present embodiment, the spring characteristics of the shock absorber A1 as a whole become the combined characteristics of the spring characteristics of the suspension spring Sm and the spring characteristics of the gas spring Se.

The spring characteristic of the suspension spring Sm is a linear characteristic, and has a characteristic that the spring force increases in proportion to the amount of compression. On the other hand, the spring characteristic of the gas spring Se is a non-linear characteristic, and has a characteristic that the amount of increase in spring force increases as the amount of compression increases. Assuming that the maximum extension time of the shock absorber A1 is the start point of the stroke and the maximum contraction time is the end point of the stroke, the spring characteristics of the shock absorber A1 as a whole are dominated by the characteristics of the suspension spring Sm from the early stage to the middle stage of the stroke. , The characteristics of the gas spring Se dominate at the end of the stroke.

As described above, in the present embodiment, the suspension spring Sm functions as a main spring that elastically supports the vehicle body, and the spring force at the end of the stroke can be supplemented by the gas spring Se. However, the suspension spring Sm may be abolished and the gas spring Se may be used as the main spring.

The spring receiver 34 is formed with a throttle hole 34a that resists the flow of the liquid, and the liquid passes through the throttle hole 34a in the latter half of the stroke of the shock absorber A1. As a result, in the latter half of the stroke of the shock absorber A1, a secondary damping force due to the resistance of the throttle hole 34a is generated, and this is added to the main damping force. Therefore, in the latter half of the stroke, the damping force of the shock absorber A1 as a whole becomes large, and the contraction speed of the shock absorber A1 can be reduced by the large damping force. The impact during contraction can be alleviated more reliably.

When the spring receiver 34 is used as a damping element for obtaining a stroke-dependent position-dependent secondary damping force as in the shock absorber A1 of the present embodiment, the gas spring Se is used as the main spring. Of course, the spring receiver (position-dependent damping element) 34 may be left even when the suspension spring Sm is omitted, such as when the suspension spring Sm is omitted. That is, the position-dependent damping element does not necessarily have to function as a spring receiver.

A tubular housing 6 is mounted on the outer periphery of the cylinder 3 above the spring receiver 34, and an auxiliary air chamber g1 is formed between the housing 6 and the cylinder 3. The housing 6 is formed with an orifice 6a that opens laterally at a position that is always above the liquid level r1. As a result, the auxiliary air chamber g1 and the air chamber G are always communicated with each other through the orifice 6a.

According to the above configuration, when the inner tube 2 exits from the outer tube 1 when the shock absorber A1 is extended, the volume of the air chamber G is expanded, and the pressure in the air chamber G is reduced, the gas in the auxiliary air chamber g1 is released. It goes to the air chamber G through the orifice 6a. On the contrary, when the inner tube 2 invades the outer tube 1 when the shock absorber A1 contracts, the volume of the air chamber G decreases, and the pressure in the air chamber G rises, the pressure in the air chamber G rises. The gas passes through the orifice 6a and goes to the auxiliary air chamber g1.

When the stroke speed is low (at low speed) when the shock absorber A1 expands and contracts, the flow rate of the gas passing through the orifice 6a is small, and the gas passes through the orifice 6a to pass through the orifice 6a to the air chamber G and the auxiliary air chamber. It can move to and from g1 without any resistance. Therefore, at low speed, the sub-air chamber g1 behaves like a continuous room with the air chamber G, so that the portion (room) where the air chamber G and the sub-air chamber g1 are combined is a gas spring of the substantial gas spring Se. It becomes a room.

On the other hand, when the stroke speed of the shock absorber A1 is high (at high speed), the flow rate of the gas passing through the orifice 6a increases, and the flow of gas passing between the air chamber G and the auxiliary air chamber g1 flows. It is blocked by the orifice 6a. Therefore, at high speed, the secondary air chamber g1 behaves like a room separated from the air chamber G, so that the secondary air chamber g1 is substantially separated from the gas spring chamber of the gas spring Se, and the gas spring chamber is substantially separated by that amount. The volume is reduced.

As a result, at high speed, the compression ratio of the gas spring chamber constituting the gas spring Se becomes larger than at low speed, and the spring characteristics of the gas spring Se change. More specifically, as the compression ratio of the gas spring chamber increases, the spring force of the gas spring Se generated at the end of the stroke becomes remarkably large. Therefore, in the shock absorber A1 of the present embodiment, a large spring force due to the gas spring Se can be obtained at the end of the stroke when the stroke speed is high. Then, since the contraction speed of the shock absorber A1 can be reduced by the large spring force of the gas spring Se, the impact at the time of maximum contraction of the shock absorber A1 can be further alleviated.

Hereinafter, the action and effect of the buffer A1 according to the present embodiment will be described.

The shock absorber A1 according to the present embodiment has an outer tube 1, an inner tube 2 slidably inserted into the outer tube 1 in the axial direction, and a stretchable tube member T, and the tube. It includes an air chamber G formed in the member T whose volume changes due to expansion and contraction of the tube member T, and an auxiliary air chamber g1 that communicates with the air chamber G via an orifice 6a. According to this configuration, at least the air chamber G becomes a gas spring chamber, and the gas spring Se formed by the gas spring chamber can exert a spring force according to the stroke amount of the shock absorber A1.

Further, according to the above configuration, when the stroke speed of the shock absorber A1 is low, the gas moves relatively freely between the air chamber G and the auxiliary air chamber g1 through the orifice 6a. It behaves like a series of gas spring chambers. However, when the shock absorber A1 stroke speed becomes high, the free movement of the gas through the orifice 6a is hindered, so that the secondary air chamber g1 is substantially separated from the gas spring chamber, and the volume of the gas spring chamber is increased accordingly. Decreases.

As described above, in the shock absorber A1, when the stroke speed is high, the volume of the gas spring chamber can be reduced and the compression ratio of the gas spring chamber can be increased as compared with the case where the stroke speed is low. The spring characteristics of the gas spring Se can be changed accordingly. In other words, according to the shock absorber A1, the spring characteristic of the gas spring Se can be made a velocity-dependent characteristic.

Further, according to the above configuration, when changing the spring characteristics of the gas spring Se according to the stroke speed, another air chamber is connected to the main air chamber G constituting the gas spring chamber of the gas spring Se via the orifice 6a. It is only necessary to communicate (secondary air chamber g1). Therefore, even if the spring characteristics of the gas spring Se are changed according to the stroke speed of the shock absorber A1, the configuration for that purpose can be simplified.

Further, the shock absorber A1 of the present embodiment includes a shock absorber body D arranged in the tube member T, and the shock absorber body D is inserted into the cylinder 3 and the cylinder 3 so as to be movable in the axial direction. A piston rod (rod) 40 is provided between the outer tube 1 and the inner tube 2, and an air chamber G is formed between the tube member T and its shock absorber body D. ..

According to the above configuration, the spring force of the gas spring Se having the air chamber G increases when the shock absorber A1 contracts. Then, as described above, when the auxiliary air chamber g1 is communicated with the air chamber G via the orifice 6a, the gas spring Se that resists the contraction when the shock absorber A1 tries to contract most while the stroke speed is high. Since a large spring force can be obtained, the impact at the time of maximum contraction can be alleviated.

Further, as in the present embodiment, the purpose is to accommodate the shock absorber body D in the tube member T so that the shock absorber body D exerts the main damping force and alleviates the impact at the time of maximum contraction. When a hydraulic lock mechanism having a lock piece 33 and a lock case 21 or a position-dependent damping element such as a spring receiver 34 is provided, these functions can be supplemented by the gas spring Se. The hydraulic lock mechanism and the like can be miniaturized or omitted.

In addition, the main damping force may be increased for the purpose of alleviating the impact of the shock absorber A1 at the time of maximum contraction, but if this is done, the pressure in the cylinder 3 becomes high and the load is increased. Becomes larger. On the other hand, if the gas spring Se can be used to alleviate the impact of the shock absorber A1 at the time of maximum contraction as in the present embodiment, it is not necessary to increase the main damping force, and the load on the cylinder 3 can be reduced. Can be reduced.

Further, in the shock absorber A1 of the present embodiment, the cylinder 3 of the shock absorber main body D is connected to the outer tube 1. The outer tube 1 is a tube arranged on the upper side of the outer tube 1 and the inner tube 2 constituting the tube member T, and is a tubular housing 6 on the outer periphery of the cylinder 3 connected to the outer tube 1. Is placed. Then, the auxiliary air chamber g1 is formed between the cylinder 3 and the housing 6, and the orifice 6a opens to the side of the housing 6.

As described above, in the present embodiment, since the auxiliary air chamber g1 is formed in the tube member T, the shock absorber A1 can be miniaturized. Further, since the housing 6 for partitioning the auxiliary air chamber g1 in the tube member T is arranged on the outer periphery of the cylinder 3 connected to the upper outer tube 1, the housing 6 can be arranged in the upper part in the tube member T. Therefore, even when the air chamber G is formed on the upper side of the liquid level r1 of the liquid stored in the tube member T as in the shock absorber A1 of the present embodiment, the air chamber G and the auxiliary air chamber are formed. It is easy to communicate with g1 via the orifice 6a.

Further, according to the above configuration, since the orifice 6a opens to the side of the housing 6, even when the liquid is stored in the tube member T, the liquid splashed up due to vibration or the like during vehicle running is the orifice 6a. It is possible to suppress the entry into the accessory air chamber g1. Further, even when the liquid in the cylinder 3 is discharged from the through hole 3a to the outside of the cylinder 3 by the relief mechanism, it is possible to prevent the liquid flowing down the outer circumference of the cylinder 3 from entering the auxiliary air chamber g1 from the orifice 6a. it can. In addition, it is possible to prevent the liquid that has entered the auxiliary air chamber g1 from blocking the orifice 6a.

However, the configuration of the housing 6 for partitioning the secondary air chamber g1 and the mounting target, and the arrangement of the secondary air chamber g1 and the orifice 6a are not limited to the above. For example, a bush may be mounted on the outer circumference of the housing 6, and the housing may be slidably contacted with the inner circumference of the inner tube via the bush. Further, the housing 6 does not necessarily have to be tubular, and may be attached to the inner tube 2 or the cap 10. Further, the secondary air chamber g1 may be arranged outside the tube member T, and the position of the orifice 6a can be changed according to the position of the secondary air chamber g1.

<Second embodiment>
Next, the shock absorber A2 according to the second embodiment of the present invention shown in FIG. 2 will be described. The basic configuration of the shock absorber A2 according to the present embodiment is the same as that of the shock absorber A1 of the first embodiment, and the shock absorber A2 of the present embodiment is the shock absorber of the first embodiment. In addition to the configuration of A1, it differs from the shock absorber A1 according to the first embodiment in that it includes a check valve 7 that allows only the flow of fluid from the auxiliary air chamber g1 to the air chamber G. Hereinafter, only the check valve 7 which is a difference and the peripheral structure thereof will be described in detail, and the common configuration will be designated by the same reference numerals and detailed description thereof will be omitted.

In the present embodiment, the housing 6A for partitioning the auxiliary air chamber g1 in the tube member T extends downward from the annular threaded portion 6b screwed to the outer periphery of the cylinder 3 and the outer peripheral portion of the threaded portion 6b. It has a cylinder portion 6c arranged with a gap between the cylinder portion 3 and an annular valve case portion 6d arranged so as to close the lower end of the cylinder portion 6c and accommodating the check valve 7. The gap formed between the cylinder 6c and the cylinder 3 is the secondary air chamber g1, and the orifice 6a formed in the cylinder 6c so as to open laterally provides the secondary air chamber g1 and the air chamber G. Is communicated.

Further, the space between the screw portion 6b and the cylinder 3 and the space between the valve case portion 6d and the cylinder 3 are sealed with O-rings 60 and 61. Further, as shown in FIG. 3, a step 6e is formed on the inner circumference of the valve case portion 6d and below the O-ring 61, and the inner diameter of the valve case portion 6d below the step 6e. Is larger than the inner diameter of the upper side. Then, the step 6e abuts on the snap ring 35 mounted on the outer circumference of the cylinder 3, whereby the housing 6A is positioned in the axial direction with respect to the cylinder 3.

The valve case portion 6d includes an inner cylinder portion 6f and an outer cylinder portion 6g arranged in an inner and outer double direction, and a connecting portion 6h connecting the upper ends thereof. A port 6i that opens into the auxiliary air chamber g1 is formed in the connecting portion 6h so as to penetrate vertically. Further, the inner diameter of the outer cylinder portion 6g protruding downward from the connecting portion 6h is larger on the lower side than on the upper side, and an annular seat surface 6j is formed at a portion where the inner diameter changes. A check valve 7 is inserted below the seat surface 6j in the outer cylinder portion 6g so as to be movable up and down. Further, a spring 8 for urging the check valve 7 downward is accommodated between the check valve 7 and the connecting portion 6h, and the outer cylinder of the check valve 7 is placed on the inner circumference of the lower end portion of the outer cylinder portion 6g. A stopper 9 that limits the amount of downward movement within the portion 6g is attached.

The spring 8 is a coil spring in the present embodiment, but may be a spring other than the coil spring such as a leaf spring, a leaf spring, or a disc spring. The stopper 9 is annular and is removed from the outer cylinder portion 6g by a snap ring 62 attached to the inner circumference of the lower end portion of the outer cylinder portion 6g. A communication hole 9a penetrating the upper and lower parts of the stopper 9 is formed, and gas and liquid (fluid) can freely move up and down the stopper 9 through the communication hole 9a.

The check valve 7 includes an annular spring receiver 7a with which the lower end of the spring 8 abuts, an annular valve head 7b that protrudes upward from the outer peripheral portion of the spring receiver 7a and can be detached and seated on the seat surface 6j, and a spring receiver. It has an annular guide portion 7c that projects downward from the inner peripheral portion of the 7a. As described above, the check valve 7 as a whole has an annular shape, and the inner circumference from the spring receiver 7a to the guide portion 7c is in sliding contact with the outer circumference of the inner cylinder portion 6f. On the other hand, the outer diameter of the check valve 7 is larger than the inner diameter of the portion of the outer cylinder portion 6g below the seat surface 6j, and an annular gap is formed between them. Then, the fluid can move freely in the gap.

According to the above configuration, when the check valve 7 receives the urging force of the spring 8 and moves downward, the guide portion 7c abuts on the stopper 9, and the check valve 7 further moves downward in the outer cylinder portion 6g. It disappears. In such a state, the valve head 7b of the check valve 7 is separated from the seat surface 6j and a gap is formed between them. In this way, the fact that the valve head 7b of the check valve 7 separates (separates) from the seat surface 6j is also referred to as the check valve 7 opening, and the check valve 7 is urged in the opening direction by the spring 8. It can be said that it is. When the check valve 7 is open, the fluid in the secondary air chamber g1 forms a gap between the port 6i, the valve head 7b and the seat surface 6j, the outer circumference of the check valve 7, and the stopper 9. It can move to the air chamber G through the communication hole 9a without any resistance.

On the other hand, when the check valve 7 receives the pressure in the air chamber G and the fluid force when the gas moves from the air chamber G to the auxiliary air chamber g1 and moves upward, the valve head 7b hits the seat surface 6j. , The space between them is closed. In this way, the fact that the valve head 7b of the check valve 7 comes into contact with (seats) the seat surface 6j is also referred to as closing the check valve 7, and when the check valve 7 is closed, it is referred to as the auxiliary air chamber g1. The air chamber G is communicated only through the orifice 6a.

Further, as described above, since the check valve 7 is urged in the opening direction by the spring 8, the check valve 7 opens when the pressure in the air chamber G decreases, and the port 6i is opened. Therefore, even if the liquid in the tube member T enters the secondary air chamber g1 from the orifice 6a or the like, the liquid in the secondary air chamber g1 is quickly discharged to the air chamber G side (liquid storage chamber R). Further, the spring 8 is a very weak spring, and when the pressure in the air chamber G rises, the check valve 7 closes quickly.

According to the above configuration, the volume of the air chamber G is expanded, and the check valve 7 is maintained in an open state when the shock absorber A2 in which the gas in the auxiliary air chamber g1 is directed toward the air chamber G is extended. As a result, when the shock absorber A2 is extended, the secondary air chamber g1 and the air chamber G are communicated with each other via the port 6i regardless of the stroke speed, and the secondary air chamber g1 and the air chamber G behave like a continuous room. ..

On the contrary, when the volume of the air chamber G is reduced and the shock absorber A2 in which the gas in the air chamber G is directed toward the auxiliary air chamber g1 contracts, the check valve 7 closes. As a result, when the shock absorber A1 contracts, the auxiliary air chamber g1 and the air chamber G communicate with each other only by the orifice 6a. Even when the shock absorber A2 is contracted, when the stroke speed is low, the gas can move from the air chamber G to the auxiliary air chamber g1 through the orifice 6a without any resistance, so that the secondary air is present. Room g1 behaves like a continuous room with air chamber G. On the other hand, when the stroke speed is high when the shock absorber A2 contracts, the flow of gas from the air chamber G to the auxiliary air chamber g1 is obstructed by the orifice 6a, so that the auxiliary air chamber g1 is partitioned from the air chamber G. Behaves like a room.

That is, in the shock absorber A2 of the present embodiment, the volume of the gas spring chamber constituting the gas spring Se is smaller when the stroke speed is high when the shock absorber A2 is contracted, as compared with the case where the stroke speed is low. The compression ratio becomes large. Therefore, in the shock absorber A2 of the present embodiment, the spring characteristics of the gas spring Se change according to the stroke speed only at the time of contraction. In other words, in the present embodiment, the spring characteristic of the gas spring Se at the time of contraction becomes a velocity-dependent characteristic.

Then, as described above, when the compression ratio of the gas spring chamber is increased, the spring force of the gas spring Se at the end of the stroke is remarkably increased. As a result, even in the shock absorber A2 of the present embodiment, a large spring force due to the gas spring Se can be obtained at the end of the stroke when the stroke speed is high. Then, since the contraction speed of the shock absorber A2 can be reduced by the large spring force generated by the gas spring Se, the impact at the time of maximum contraction of the shock absorber A2 is surely alleviated.

Subsequently, the procedure for assembling the housing 6A of the shock absorber A2 according to the present embodiment will be described.

As shown in FIG. 2, in the present embodiment, the cylinder 3 to which the housing 6A is mounted is screwed after the upper portion 3b and the lower portion 3c are separately formed, and is fixed by a nut 36. A thread groove 3d is formed on the outer periphery of the threaded portion of the upper portion 3b and the lower portion 3c of the cylinder 3.

When assembling the housing 6A to the outer periphery of the cylinder 3, the assembling worker first mounts the check valve 7, the spring 8, the stopper 9, and the O-rings 60 and 61 in advance as shown in FIG. 4A. The threaded portion 6b of the housing 6A is screwed into the threaded groove 3d of the cylinder 3. At this time, the housing 6A is screwed above the final mounting position to expose the groove portion 3e for mounting the snap ring 35 formed on the outer periphery of the cylinder 3.

Next, as shown in FIG. 4B, the assembly worker attaches the snap ring 35 to the groove 3e of the cylinder 3 exposed from the housing 6A, and then rotates and lowers the housing 6A to show that FIG. As shown in c), the step 6e formed on the inner circumference of the valve case portion 6d is pressed against the snap ring 35 mounted on the outer periphery of the cylinder 3. In this way, the housing 6A can be screwed into the cylinder 3 with an appropriate tightening torque applied.

However, the method of assembling the housing 6A to the cylinder 3 is not limited to the above, and can be changed as appropriate. For example, the housing 6A may be mounted on the outer periphery of the cylinder 3 by a method other than screwing, such as press fitting or sandwiching. Further, in the present embodiment, the upper portion 3b and the lower portion 3c of the cylinder 3 are separately formed and then screwed together, and the nut 36 is used to prevent them from loosening. However, the upper portion 3b and the lower portion 3c of the cylinder 3 are combined with each other. Of course, may be integrally formed.

Hereinafter, the action and effect of the shock absorber A2 according to the present embodiment will be described. It should be noted that the same configuration as the shock absorber A1 of the first embodiment has, of course, the same function and effect, and therefore detailed description thereof will be omitted here.

The shock absorber A2 according to the present embodiment includes a check valve 7 that allows only the flow of fluid from the auxiliary air chamber g1 to the air chamber G. According to this configuration, the orifice 6a is used as a one-sided effect, and resistance is given by the orifice 6a to the flow of gas from the air chamber G to the auxiliary air chamber g1. Further, even if the liquid enters the auxiliary air chamber g1, the liquid that has entered the auxiliary air chamber g1 can be discharged through the check valve 7.

Further, in the present embodiment, an annular valve case portion 6d located on the outer periphery of the cylinder 3 and accommodating the check valve 7 is provided at the lower end portion of the housing 6A. The valve case portion 6d includes an inner cylinder portion 6f and an outer cylinder portion 6g in which the inner and outer cylinders are double arranged, and a connecting portion 6h connecting the upper ends of the inner cylinder portion 6f and the outer cylinder portion 6g. Port 6i is formed in the port 6i, which penetrates vertically and leads to the secondary air chamber g1. The check valve 7 is annular and is arranged between the inner cylinder portion 6f and the outer cylinder portion 6g that protrude downward from the connecting portion 6h.

According to the above configuration, when the check valve 7 is opened, the liquid that has entered the auxiliary air chamber g1 passes through the port 6i and between the inner cylinder portion 6f and the outer cylinder portion 6g and escapes downward. The liquid that has entered the secondary air chamber g1 can be easily discharged. Further, in the present embodiment, since the shock absorber A2 includes the spring 8 for urging the check valve 7 in the opening direction, the liquid in the auxiliary air chamber g1 can be easily discharged from this as well. However, the spring 8 may be abolished and a spring for urging the check valve 7 in the closing direction may be provided, or the check valve 7 may be used as a leaf valve.

Further, also in the present embodiment, similarly to the first embodiment, a tubular shape is formed on the outer periphery of the cylinder 3 connected to the outer tube (the tube arranged on the upper side of the outer tube and the inner tube) 1. The housing 6A is arranged, the auxiliary air chamber g1 is formed between the cylinder 3 and the housing 6A, and the orifice 6a opens to the side of the housing 6A.

According to the above configuration, since the secondary air chamber g1 is arranged in the tube member T, the shock absorber A2 can be miniaturized. Further, since the auxiliary air chamber g1 can be arranged in the upper part in the tube member T, even when the air chamber G is formed on the upper side of the liquid surface of the liquid stored in the tube member T, the auxiliary air chamber G and the auxiliary air chamber G are formed. The air chamber g1 can be easily communicated with the orifice 6a. In addition, since the orifice 6a opens to the side of the housing 6A, it is possible to suppress the liquid in the tube member T from entering the auxiliary air chamber g1 from the orifice 6a, and the liquid entering the auxiliary air chamber g1 can be prevented from entering the orifice. It is possible to prevent the 6a from being blocked.

However, if the check valve 7 is provided as in the present embodiment and the liquid in the auxiliary air chamber g1 can be discharged, the orifice 6a may be formed in the check valve 7. Specifically, for example, a groove along the radial direction is formed in the valve head 7b or the seat surface 6j of the check valve 7 shown in FIG. 4, and the gap formed on the upper side of the check valve 7 by this groove is used as an orifice 6a. You may use it.

Although the preferred embodiments of the present invention have been described in detail above, modifications, modifications, and changes can be made as long as they do not deviate from the claims.

A ... shock absorber, D ... shock absorber body, T ... tube member, G ... air chamber, g1 ... secondary air chamber, 1 ... outer tube, 2 ... inner tube 3, 3 ... Cylinder, 40 ... Piston rod (rod), 6, 6A ... Housing, 6a ... orifice, 6d ... Valve case part, 6f ... Inner cylinder part, 6g ...・ Outer cylinder part, 6h ・ ・ ・ connecting part, 6i ・ ・ ・ port, 7 ・ ・ ・ check valve, 8 ・ ・ ・ spring

Claims (6)

A tube member that has an outer tube and an inner tube that is slidably inserted into the outer tube in the axial direction and is expandable and contractible.
An air chamber formed in the tube member and whose volume changes due to expansion and contraction of the tube member, and
A shock absorber comprising the air chamber and an auxiliary air chamber that communicates with each other through an orifice. A shock absorber body having a cylinder and a rod that is axially movably inserted into the cylinder and arranged in the tube member and interposed between the outer tube and the inner tube is provided. ,
The shock absorber according to claim 1, wherein the air chamber is formed between the tube member and the shock absorber body. The cylinder is connected to a tube arranged on the upper side of the outer tube and the inner tube.
The auxiliary air chamber is formed between a tubular housing arranged on the outer periphery of the cylinder and the cylinder.
The shock absorber according to claim 2, wherein the orifice opens to the side of the housing. The shock absorber according to any one of claims 1 to 3, further comprising a check valve that allows only the flow of fluid from the secondary air chamber to the air chamber. An annular valve case portion located on the outer periphery of the cylinder and accommodating the check valve is provided at the lower end portion of the housing.
The valve case portion includes an inner cylinder portion and an outer cylinder portion that are double arranged inside and outside, and a connecting portion that connects the inner cylinder portion and the upper end of the outer cylinder portion, and the connecting portion penetrates vertically. A port leading to the secondary air chamber is formed.
4. The check valve according to claim 3, wherein the check valve is annular and is arranged between the inner cylinder portion and the outer cylinder portion protruding downward from the connecting portion. Buffer. The shock absorber according to claim 4 or 5, wherein the check valve is urged in the opening direction by a spring.

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