JP6643164B2 - Shock absorber - Google Patents

Description

  The present invention relates to a shock absorber, and more particularly to a shock absorber capable of setting a desired compression amount-reaction force characteristic.

  Conventionally, a shock absorber provided with a gas spring chamber (first gas chamber) having a function as a gas spring and provided between a vehicle body and a wheel (axle) has been known. For example, a shock absorber main body (hydraulic shock absorber) and an air spring that constantly urges the hydraulic shock absorber in the extension direction are provided. A shock absorber (suspension device) made of a gas sealed in an air chamber is disclosed (Patent Document 1).

  In the technique disclosed in Patent Literature 1, the volume expanding unit partitions the inside of a sub-cylinder formed inside the shock absorber main body into an air chamber and an auxiliary chamber by a movable partition. When the reaction force of the gas in the air chamber exceeds a predetermined value according to the increase in the compression amount of the shock absorber main body, the volume of the air chamber is expanded by moving the movable partition to the auxiliary chamber side. Thus, it is possible to suppress the reaction force of the air chamber from becoming excessive in the latter half of the compression stroke.

JP 2014-77452 A

  However, in the above-described conventional technique, since the volume expanding means is provided inside the shock absorber main body, the size of the shock absorber main body restricts the capacity of the auxiliary chamber. Therefore, the compression amount-reaction characteristic of the shock absorber may not be set to a desired characteristic.

  The present invention has been made to solve the above-described problem, and has as its object to provide a shock absorber capable of setting a desired compression amount-reaction force characteristic.

In order to achieve this object, a shock absorber according to claim 1 has a first end fixed to a vehicle body side, a second end fixed to an axle side, and a shock absorber main body for damping an impact. An expansion portion attached to the outside of the shock absorber main body and filled with gas therein; the shock absorber main body includes a first gas chamber in which gas is sealed, and a gas sealed in the first gas chamber. A piston that compresses when the first end and the second end approach each other, a cylinder that slides inside the piston, that is fixed to the first end, and that is fixed to the second end. A rod to which a piston is fixed , wherein the additional portion communicates with the first gas chamber, wherein a movable partition that slides inside the additional portion and an interior of the additional portion is defined by the movable partition; The inside of the extension part is partitioned by the first extension chamber to be A second expansion chamber formed on the opposite side to the first expansion chamber, and the movable partition moves toward the second expansion chamber with an increase in the pressure of the first gas chamber, The additional portion is attached to the second end, and is formed from the second end to the first end , and the first gas chamber is inside the cylinder and closer to the first end than the piston. And the rod includes a communication path that allows the first gas chamber and the first expansion chamber to communicate with each other.
Further, the shock absorber according to claim 2 has a first end fixed to the vehicle body side and a second end fixed to the axle side, and a shock absorber main body for damping an impact; The shock absorber main body includes a first gas chamber in which gas is sealed, and a gas in the first gas chamber and the first end and the first gas chamber. A piston that compresses when the two ends approach each other, a body-side tube formed from the first end toward the second end, and a second body that slides with respect to the body-side tube; An axle-side tube formed toward the first end, and the piston disposed inside the axle-side tube and the body-side tube, wherein the piston slides inside to form the first gas chamber therein. Cylinder, the cylinder, the axle side tube, and the wheel A second gas chamber which is formed between the side tube and which is filled with a gas, wherein the additional portion includes a movable partition that slides inside the additional portion, and a movable partition inside the additional portion. A first expansion chamber communicating with the first gas chamber, and a second expansion chamber formed by partitioning the inside of the expansion section by the movable partition and being formed on the opposite side of the first expansion chamber. Wherein the movable partition moves toward the second additional chamber with an increase in the pressure of the first gas chamber, and the additional portion is attached to the second end, and It is formed on the first end side.

According to the shock absorbers of the first and second aspects, the shock absorber main body for shock absorption is provided with the first end fixed to the vehicle body side and the second end fixed to the axle side approaching each other. The gas sealed in the gas chamber is compressed by the piston. The expansion portion, in which gas is sealed, has the inside of the expansion portion partitioned into a first expansion room and a second expansion room by a movable partition sliding inside the expansion portion. The first expansion chamber communicates with the first gas chamber, and a second expansion chamber is formed on the opposite side of the movable partition from the first expansion chamber. The movable partition moves to the second expansion chamber side as the pressure of the first gas chamber (first expansion chamber) increases. Since the additional portion is attached to the outside of the shock absorber main body, the restriction on the capacity of the second additional chamber can be eased, and the compression amount-reaction force characteristics of the shock absorber can be set to desired characteristics.

  Since the additional portion is attached to the second end of the shock absorber main body whose first end is fixed to the vehicle body side, a space on the vehicle body side can be secured. Since the additional portion attached to the second end of the shock absorber main body is formed from the second end to the first end side, it is possible to suppress the additional portion from contacting a road surface or the like. As a result, there is an effect that the expansion amount-reaction characteristic of the shock absorber can be set to a desired characteristic by the additional portion that can secure the space on the vehicle body side and suppress the contact of the additional portion with the road surface or the like.

It is sectional drawing of the shock absorber in one Embodiment of this invention. It is a partial expanded sectional view of a shock absorber. It is a graph which shows the compression amount-reaction force characteristic of a shock absorber.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. First, an overall configuration of a shock absorber 10 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a sectional view of a shock absorber 10 according to one embodiment of the present invention. FIG. 1 schematically shows the communication valve 47.

  As shown in FIG. 1, a shock absorber 10 is a shock absorber for connecting a vehicle body and an axle of a motorcycle (not shown) to absorb vibration from a road surface. On the other hand. The other (not shown) of the front fork is a hydraulic shock absorber incorporating a damping mechanism such as an oil damper. The shock absorber 10 includes a shock absorber main body 11 for shock absorption, and an additional portion 40 attached to the outside of the shock absorber main body 11. The shock absorber main body 11 has a first end 11a fixed to the vehicle body side and a second end 11b fixed to the axle side.

  The shock absorber main body 11 is formed from the first end 11a toward the second end 11b, and is formed from the second end 11b toward the first end 11a and inserted into the body side tube 20. The axle-side tube 30, the cylinder 12 disposed inside the body-side tube 20, the rod 13 disposed inside the axle-side tube 30 and inserted into the cylinder 12, and fixed to the rod 13. The piston includes a piston that slides in the cylinder in the axial direction, a rod guide fixed to the cylinder and into which a rod is inserted, and a rebound spring disposed between the piston and the rod guide. .

  The vehicle body side tube 20 is a cylindrical member whose upper end (the end on the first end 11a side) is closed by a cap 21 and is sealed on the inner peripheral surface on the lower end (the end on the second end 11b side). A ring 22 and a bush 23 are provided respectively. A seal ring (not shown) provided between the vehicle body side tube 20 and the cap 21 makes the gap between the inner peripheral surface on the upper end side of the vehicle body side tube 20 and the cap 21 airtight.

  The seal ring 22 is formed in an annular shape from rubber. Note that the seal rings 13b, 33a, 33b, and 34b, which will be described later, are configured in the same manner as the seal ring 22, and a description thereof will be omitted. The bush 23 is formed in an annular shape, and its inner peripheral surface is coated with a fluororesin.

  The cap 21 is a member fastened and fixed to the vehicle body side tube 20, and includes a first gas chamber adjustment unit 24 and a second gas chamber adjustment unit 25. The first gas chamber adjusting section 24 and the second gas chamber adjusting section 25 are provided in two through holes formed in the cap 21 respectively. The first gas chamber adjustment section 24 is an adjustment valve for adjusting the pressure (reaction force) of the first gas chamber C1 described later. The second gas chamber adjustment section 25 is an adjustment valve for adjusting the pressure of a second gas chamber C2 described later.

  The axle-side tube 30 is a cylindrical member whose lower end (the end on the second end 11b side) is closed by an axle-side fixing portion 31, and has an outer diameter substantially the same as the inner diameter of the body-side tube 20. It is formed. The axle-side tube 30 is slidable airtightly along the inner peripheral surface of the body-side tube 20 (the inner peripheral surfaces of the seal ring 22 and the bush 23).

  The axle-side fixing portion 31 penetrates the bracket 32 in which a connection hole 32 a for connecting the axle is formed, a bottom piece 33 attached to the lower end of the axle-side tube 30, and the axial direction of the axle-side tube 30. And a bottom bolt 34 attached to the through hole. The bracket 32 includes a cylindrical tube portion 32b into which the axle-side tube 30 is inserted, and the inner diameter of the tube portion 32b is formed to be substantially the same as the outer diameter of the axle-side tube 30. The axle-side tube 30 is inserted into the tubular portion 32b and fastened and fixed.

  The cylinder 12 is a cylindrical member having a smaller diameter than the axle-side tube 30. The upper end (the end on the first end 11 a side) is formed integrally with the cap 21, and the upper end is closed by the cap 21. The rod 13 is a tubular member having a smaller diameter than the cylinder 12, and a lower end (an end on the second end 11 b side) is fixed to a bottom bolt 34.

  The piston 14 is a cylindrical member fastened and fixed to the upper end of the rod 13 (the end on the first end 11a side). The piston 14 is provided with seal rings 14a, 14b and a bush 14c on the outer peripheral surface. The seal rings 14a and 14b are formed in an annular shape from rubber, and the tension (contact surface pressure) increases as the pressure of a first gas chamber C1 described later increases. The seal ring 14b is formed in an annular shape from rubber, and the tension force increases as the pressure of a second gas chamber C2 described later increases.

  The bush 14c is formed in an annular shape, and its outer peripheral surface is coated with a fluororesin. The outer diameter of the piston 14 (the outer diameter of the seal rings 14a, 14b and the bush 14c) is substantially the same as the inner diameter of the cylinder 12, so that the piston 14 can slide airtightly along the inner peripheral surface of the cylinder 12. .

  The rod guide 15 is a cylindrical member whose outer peripheral surface is fastened and fixed to the inner peripheral surface of the lower end (the end on the second end 11b side) of the cylinder 12. The rod guide 15 is provided with a bush 15a on the inner peripheral surface. The bush 15a is formed in an annular shape, and its inner peripheral surface is coated with a fluororesin. The inner diameter of the rod guide 15 (the inner diameter of the bush 15 a) is substantially the same as the outer diameter of the rod 13. Thereby, the rod 13 slides along the inner peripheral surface of the rod guide 15.

  The rebound spring 16 is a compression coil spring made of metal, and both ends contact the piston 14 and the rod guide 15. The piston 14 and the rod guide 15 are urged by the rebound spring 16 in a direction away from each other, that is, in a direction in which the shock absorber main body 11 is compressed (shortened).

  In the shock absorber main body 11, the interior of the cylinder 12 is vertically divided by a piston 14, a first gas chamber C1 is formed on the first end 11a side of the piston 14, and the second end 11b side of the piston 14 and the rod 13 A second gas chamber C2 is formed on the outer peripheral side of the first gas chamber. The piston 14 includes a communication hole 14d that allows the first gas chamber C1 to communicate with the communication passage 13a inside the rod 13. Thereby, the inside of the piston 14 becomes a part of the first gas chamber C1. Further, since the rod guide 15 and the rod 13 are not airtight (communicated), the space between the vehicle body side tube 20 and the axle side tube 30 and the cylinder 12 and the rod 13 is one of the second gas chamber C2. Department.

  A gas (for example, air) is sealed in the first gas chamber C1 and the second gas chamber C2, and the pressure in the first gas chamber C1 and the second gas chamber C2 urges the shock absorber main body 11 in the extending direction. Force is generated. The pressure in the second gas chamber C2 is set lower than the pressure in the first gas chamber C1. The state of the shock absorber main body 11 shown in FIG. 1 is in a neutral state in which the reaction force of the first gas chamber C1 and the second gas chamber C2 and the elastic force (reaction force) of the rebound spring 16 are balanced (the shock absorber main body 11 is located outside). No input has been received from the user).

  The vibration input to the shock absorber main body 11 in the axial direction of the shock absorber main body 11 is absorbed by the combined reaction force of the first gas chamber C1, the second gas chamber C2, and the rebound spring 16 (the shock absorber main body 11 has an impact). Buffer). As described above, the shock absorber main body 11 is formed as an air suspension in which a main shock effect is generated by the gas sealed inside (the first gas chamber C1 and the second gas chamber C2) (there is no oil pressure shock effect).

  Next, the axle-side fixing portion 31 and the additional portion 40 will be described with reference to FIG. FIG. 2 is a partially enlarged cross-sectional view of the shock absorber 10. In FIG. 2, the communication valve 47 is schematically illustrated by an outline and a symbol. As shown in FIG. 2, the bottom piece 33 of the axle-side fixing portion 31 includes a seal ring 33 a provided between the inner peripheral surface of the axle-side tube 30 and a seal ring 33 b provided between the bracket 32. Prepare. The bottom piece 33 makes the space between the axle-side tube 30 and the tubular portion 32b (the bracket 32) airtight by the seal rings 33a and 33b.

  The bottom bolt 34 has a lower end of the rod 13 fastened and fixed, and a communication hole 34a that opens to the outer peripheral surface of the bottom bolt 34 in communication with the communication passage 13a. The space between the rod 13 and the bottom bolt 34 is made airtight by a seal ring 13b provided on the outer peripheral surface at the lower end of the rod 13.

  A seal ring 34b is provided on the outer peripheral surface of the bottom bolt 34 so as to sandwich a portion opened on the outer peripheral surface of the communication hole 34a. This makes the space between the bottom bolt 34 and the bracket 32 airtight. The communication hole 34a has a portion extending in the axial direction of the rod 13, a portion extending radially from the center of the bottom bolt 34 in the direction perpendicular to the axis of the rod 13, and an outer peripheral surface of the bottom bolt 34 recessed in a groove shape in the circumferential direction. Are connected to each other.

  The additional portion 40 is a tank for increasing the volume of the first gas chamber C1, is attached to the second end 11b, and is formed from the second end 11b to the first end 11a. When the additional portion 40 is attached to the first end 11a, when attaching the shock absorber 10 (the shock absorber main body 11) to the vehicle body, the additional portion 40 interferes with the vehicle body, making it difficult to attach the shock absorber 10 to the vehicle body. Further, when the shock absorber 10 is attached to the vehicle body, the additional portion 40 protrudes from the vehicle body (near the steering wheel) and the space on the vehicle body side is narrowed, so that the additional portion 40 hinders the driver. In the present embodiment, since the additional portion 40 is attached to the second end 11b, it is possible to prevent the additional portion 40 from interfering with the attachment of the shock absorber 10 to the vehicle body and to make it difficult to attach the shock absorber 10 to the vehicle body. By securing a space on the vehicle body side, the additional portion 40 can be prevented from obstructing the driver.

  When the additional portion 40 attached to the second end 11b is formed so as to be separated from the first end 11a, the additional portion 40 may come into contact with a road surface or the like. In the present embodiment, since the additional portion 40 attached to the second end 11b is formed on the first end 11a side from the second end 11b, it is possible to suppress the additional portion 40 from contacting a road surface or the like.

  The extension portion 40 includes an extension body 41 integrated with the bracket 32, a tubular portion 42 attached to the extension body 41, and a movable partition 43 that slides inside the tubular portion 42. The additional main body 41 is a hollow part, and the inside communicates with the communication hole 34a. The extension main body 41 includes a hollow extending portion 41a that extends obliquely in a direction perpendicular to the axis of the shock absorber main body 11 so that the cylindrical portion 42 is separated from the shock absorber main body 11, and from the extending portion 41a to the first end 11a. And a hollow mounting portion 41b extending parallel to the shock absorber main body 11. An internal thread is provided on the inner peripheral surface of the upper end (the end on the first end 11a side) of the mounting portion 41b.

  The cylindrical portion 42 is a cylindrical member whose upper end (the end on the first end 11 a side) is closed by a cap 44. In the cylindrical portion 42, the inner diameter of the portion where the movable partition 43 slides is constant in the axial direction, the inner diameter of the cylindrical portion 42 is formed larger than the inner diameter of the cylinder 12, and is parallel to the shock absorber main body 11. Be placed. The tubular portion 42 includes a projecting portion 45 projecting inward from the inner peripheral surface of the lower end (the end on the second end 11b side). The outer diameter of the lower end of the cylindrical portion 42 is substantially the same as the inner diameter of the upper end of the mounting portion 41b, and a male screw is formed on the outer peripheral surface of the lower end. By fastening the external thread of the cylindrical portion 42 to the female screw of the mounting portion 41b, the cylindrical portion 42 can be exchangeably fixed to the mounting portion 41b (the additional main body portion 41). In addition, a seal ring (not shown) is provided between the outer peripheral surface of the cylindrical portion 42 and the inner peripheral surface of the mounting portion 41b, and an outer peripheral surface of the cylindrical portion 42 and an inner peripheral surface of the mounting portion 41b are provided. The space between them is sealed.

  The cap 44 is a member that is fastened and fixed to the cylindrical portion 42, and includes a second expansion chamber adjusting portion 46 provided in a through hole formed in the cap 44. The second expansion chamber adjustment section 46 is an adjustment valve for adjusting the pressure of a second expansion chamber C4 described later.

  The movable partition 43 is a columnar member in which the inner diameter and the outer diameter of the cylindrical portion 42 are formed to have substantially the same dimensions, and the outer diameter is formed larger than the outer diameter of the piston 14. The movable partition 43 is provided with seal rings 43 a and 43 b on the outer peripheral surface, and can slide in an airtight manner along the inner peripheral surface of the tubular portion 42. The seal ring 43a is formed in an annular shape from rubber, and the tension force increases as the pressure of a first additional chamber C3 described later increases. The seal ring 43b is formed in an annular shape from rubber, and the tension force increases as the pressure of the second additional chamber C4 described later increases.

  In the extension portion 40 (the extension main body portion 41 and the cylindrical portion 42), the inside of the extension portion 40 (the interior of the extension main body portion 41 and the cylindrical portion 42) is vertically divided by the movable partition 43, and is higher than the movable partition 43. A first extension room C3 is formed on the second end 11b side, and a second extension room C4 is formed on the first end 11a side of the movable partition 43. Since the first additional chamber C3 communicates with the first gas chamber C1 via the communication hole 34a, the first additional chamber C3 becomes a part of the first gas chamber C1.

  A communication valve 47 that sends gas from the first additional chamber C3 to the second gas chamber C2 when the pressure of the first additional chamber C3 (first gas chamber C1) exceeds a predetermined threshold is provided in the additional main body 41. The communication valve 47 has a member that closes a passage connecting the second gas chamber C2 (the inner peripheral surface of the axle-side tube 30) and the first additional chamber C3 (the inner peripheral surface of the mounting portion 41b), and a member that closes the first additional chamber C3 by a spring. And a relief valve for communicating between the second gas chamber C2 (low pressure side) and the first expansion chamber C3 (high pressure side) when the pressure of the first expansion chamber C3 exceeds the urging force of the spring. is there. Since the communication valve 47 is provided in the additional main body 41, that is, since the communication valve 47 is provided outside the shock absorber main body 11, adjustment of the urging force (threshold) of the spring of the communication valve 47 can be easily performed.

  In the neutral state of the shock absorber main body 11, gas (for example, air) is supplied to the second additional chamber C4 so that the pressure of the second additional chamber C4 is set higher than the pressures of the first gas chamber C1 and the first additional chamber C3. Is enclosed. As a result, the movable partition 43 is pushed toward the first extension chamber C3 (first gas chamber C1) and comes into contact with the overhang portion 45, and the movable partition 43 is moved by the overhang portion 45 toward the first extension chamber C3. Is limited.

  Returning to FIG. 1, the operation of the shock absorber 10 will be described. The shock absorber 10 (the shock absorber main body 11) has a first end 11a (a body side tube 20) and a second end 11b (the shock absorber 10 receives vibration from the axle side). The compression operation in which the axle-side tube 30) moves toward each other and the expansion operation in which the first end 11a and the second end 11b move away from each other are performed, thereby absorbing shock.

  During compression of the shock absorber 10, the volumes of the first gas chamber C1 and the second gas chamber C2 decrease, and the pressures (reaction forces) of the first gas chamber C1 and the second gas chamber C2 increase. Since the tightening force of the seal rings 14a and 14b can be increased as the pressures of the first gas chamber C1 and the second gas chamber C2 increase, even if the pressures of the first gas chamber C1 and the second gas chamber C2 increase. The airtightness of the first gas chamber C1 and the second gas chamber C2 can be ensured. If the pressure in the first gas chamber C1 and the pressure in the second gas chamber C2 are low, the frictional force between the seal rings 14a, 14b and the cylinder 12 can be reduced, and the wear of the seal rings 14a, 14b can be suppressed. Similarly, the seal rings 43a and 43b can also suppress the wear of the seal rings 43a and 43b while ensuring the airtightness of the first additional chamber C3 (first gas chamber C1) and the second additional chamber C4.

  The shock absorber 10 suppresses the reaction force of the first gas chamber C1 and the second gas chamber C2 urged in the extension direction in the initial stage of the compression operation by increasing (longening) the size of the rebound spring 16 to reduce the driver's pressure. The ride comfort can be improved. However, when the length of the rebound spring 16 is secured, the volume of the first gas chamber C1 (between the piston 14 in the cylinder 12 and the first end 11a) formed on the first end 11a side with the piston 14 as a boundary. Decrease.

  In the shock absorber 10, the first gas chamber C1 formed on the first end 11a side with the piston 14 as a boundary communicates with the communication passage 13a through a communication hole 14d, and the communication passage 13a communicates with the first additional chamber C3. By communicating with the hole 34a, the capacity of the first gas chamber C1 can be secured by the communication passage 13a and the first additional chamber C3. This makes it possible to compensate for the decrease in the volume of the first gas chamber C1 due to the increase in the size of the rebound spring 16 for improving the ride comfort of the driver.

  When the shock absorber 10 is compressed, the pressure of the first expansion chamber C3 which is a part of the first gas chamber C1 is reduced by the pressure receiving area of the movable partition 43 on the first expansion chamber C3 side (the pressure from the first expansion chamber C3 side). The first reaction force multiplied by the pressure receiving area on the second expansion chamber C4 side of the movable partition 43 (the area receiving the pressure from the second expansion chamber C4 side) multiplies the pressure in the second expansion chamber C4 by the first reaction force. When the value exceeds the sum of the second reaction force and the resistance between the movable partition 43 and the cylindrical portion 42 (the additional portion 40) (when the value exceeds a predetermined value C described later), the movable partition 43 Starts moving to the second extension room C4 side. The resistance force between the movable partition 43 and the cylindrical portion 42 includes a frictional force between the movable partition 43 (seal rings 43a, 43b) and the cylindrical portion 42, and a seal ring 43a for the cylindrical portion 42. , 43b due to adhesion or sticking.

  After the start of the movement of the movable partition 43, the movable partition 43 moves toward the second expansion chamber C4 with an increase in the pressure of the first gas chamber C1 (first expansion chamber C3). Thereby, the volume of the first gas chamber C1 (first expansion chamber C3) increases with an increase in the pressure of the first gas chamber C1.

  The larger the pressure receiving area of the movable partition 43 on the first expansion chamber C3 (first gas chamber C1) side, the greater the first reaction force with respect to the resistance between the movable partition 43 and the cylindrical portion 42. The movable partition 43 can be started to move by the low pressure of the first gas chamber C1. Therefore, the responsiveness of the movable partition 43 to an increase in the pressure of the first gas chamber C1 can be improved. In particular, since the outer diameter of the movable partition 43 is set to be larger than the outer diameter of the piston 14, that is, the pressure receiving area of the movable partition 43 on the first additional chamber C3 (first gas chamber C1) side is equal to the pressure receiving area of the piston 14. Since it is set to be larger than (the area receiving the pressure from the first gas chamber C1), the responsiveness of the movable partition 43 can be improved with respect to the responsiveness of the piston 14 (buffer 10).

  Further, as the pressure receiving area of the movable partition 43 on the side of the first additional chamber C3 with respect to the pressure receiving area of the piston 14 is larger, the amount of movement of the movable partition 43 due to the increase in the pressure of the first gas chamber C1 can be reduced, and The amount of increase in the volume of the first gas chamber C1 can be larger than the amount of movement of the partition 43. Accordingly, the acceleration of the movable partition 43 due to the increase in the pressure of the first gas chamber C1 can be reduced, so that the inertial force applied to the movable partition 43 during movement can be reduced, and the responsiveness of the movable partition 43 can be improved. In particular, the pressure receiving area of the movable partition 43 on the first extension chamber C3 side is set to be larger than the pressure receiving area of the piston 14 (the area receiving the pressure from the first gas chamber C1). The responsiveness of the movable partition 43 can be improved as compared with the case where the pressure receiving area is set to be equal to or smaller than the pressure receiving area of 14, and the responsiveness of the movable partition 43 can be improved with respect to the responsiveness of the piston 14 (the shock absorber 10).

  Here, the function of the movable partition 43 when the shock absorber 10 is compressed will be described with reference to FIG. FIG. 3 is a graph showing a compression amount-reaction force characteristic of the shock absorber 10. A graph A of the compression amount-reaction force characteristic of the shock absorber 10 is shown by a solid line, and a graph B of the compression amount-reaction force characteristic of the shock absorber having no movable partition 43 is shown by a broken line. In FIG. 3, the horizontal axis indicates the amount of compression from the neutral state of the shock absorber, and the vertical axis indicates the reaction force of the shock absorber.

  In general, the pressure (reaction force) of a gas increases quadratically as the compression amount increases. Therefore, as shown in FIG. 3, in the shock absorber having no movable partition 43 (graph B), the reaction force increases in a quadratic curve as the compression amount increases. That is, since the reaction force increases rapidly in the latter half of the compression operation, the riding comfort in the latter half of the compression operation deteriorates in the shock absorber having no movable partition 43.

  On the other hand, in the shock absorber 10 having the movable partition 43 (graph A), when the reaction force of the shock absorber 10 exceeds the predetermined value C (the second reaction force and the resistance between the movable partition 43 and the cylindrical portion 42). (When the first reaction force exceeds the value obtained by adding the force), the movable partition 43 starts moving and the volume of the first gas chamber C1 increases. The reaction force increases slowly. As a result, a sudden increase in the reaction force in the latter half of the compression operation can be suppressed, and the ride comfort of the driver can be improved.

  In the neutral state of the shock absorber 10, the predetermined value C is set to the second half of the compression operation (the right side in FIG. 3) as the pressure (reaction force) of the second additional chamber C4 is set higher by the second additional chamber adjusting section 46. (The timing of starting the movement of the movable partition 43 is delayed), and the increase of the reaction force after the predetermined value C can be suddenly (closer to the graph B). Therefore, the compression amount-reaction characteristic of the shock absorber 10 can be adjusted by adjusting the pressure of the second additional chamber C4 with respect to the pressure of the first gas chamber C1.

  Furthermore, since the cylindrical portion 42 is exchangeably fixed to the mounting portion 41b (the additional main body portion 41), the volume of the second additional chamber C4 of the cylindrical portion 42 can be exchanged for the cylindrical portion 42 having a different volume. As the volume of the second extension room C4 is larger, the increase in the reaction force after the predetermined value C can be made gradual (to be further away from the graph B) without changing the position of the predetermined value C. Therefore, the compression amount-reaction force characteristic of the shock absorber 10 can be adjusted by setting the volume of the second additional chamber C4. Therefore, by setting the pressure of the second additional chamber C4 and the volume of the second additional chamber C4, the compression amount-reaction characteristic of the shock absorber 10 can be set to a desired characteristic.

  To change the volume of the second extension room C4, the length of the second extension room C4 (the length of the cylindrical portion 42) is changed, and the inner diameter of the second extension room C4 (the cylindrical portion 42) is changed. (Inner diameter and outer diameter) may be changed. When changing the inner diameter of the second extension room C4, the outer diameter (pressure receiving area) of the movable partition 43 is also changed at the same time. As described above, as the movable partition 43 has a larger pressure receiving area, the responsiveness of the movable partition 43 can be improved. Therefore, when the volume of the second additional chamber C4 is reduced, the length of the second additional chamber C4 may be reduced. Preferably, when increasing the volume of the second extension room C4, it is preferable to increase the inner diameter of the second extension room C4.

  When the tubular portion 42 is replaced and is not attached to the additional main body 41 (removed from the additional main body 41), the movable partition 43 can be prevented from coming off from the inside of the tubular portion 42 by the overhanging portion 45. . Accordingly, the tubular portion 42 and the movable partition 43 to be replaced can be stored together and the replacement of the tubular portion 42 and the movable partition 43 can be facilitated.

  In the latter half of the compression operation of the shock absorber 10 (when the pressure of the first gas chamber exceeds a predetermined threshold), the communication valve 47 reduces the pressure of the first gas chamber C1 to suppress the reaction force of the shock absorber 10. it can. The communication valve 47 suppresses a sudden increase in the reaction force in the latter half of the compression operation, thereby improving the ride comfort of the driver.

  The combination of the suppression of the reaction force of the shock absorber 10 by the second expansion chamber C4 and the movable partition 43 and the suppression of the reaction force of the shock absorber 10 based on the pressure drop of the first gas chamber C1 by the communication valve 47 combine with each other. 10 can be set to desired characteristics. When the movable partition 43 becomes difficult to move with an increase in the pressure of the second additional chamber C4 (when the effect of suppressing the reaction force of the shock absorber 10 due to the movement of the movable partition 43 becomes small), the communication valve is opened. It is preferable that the pressure of the first gas chamber C1 is set to be reduced by 47. That is, it is preferable to set the communication valve 47 to reduce the pressure of the first gas chamber C1 with a compression amount larger than the predetermined value C (on the right side of FIG. 3 than the predetermined value C). Thus, a sudden increase in the reaction force of the shock absorber 10 can be suppressed until the latter half of the compression operation.

  According to the above-described shock absorber 10, since the additional portion 40 is attached to the outside of the shock absorber main body 11, the second expansion chamber C <b> 4 and the movable partition 43 are provided inside the shock absorber main body 11, so that the second expansion chamber C <b> 4 and the movable partition 43 are provided. Restrictions on the volume of the expansion chamber C4 and the pressure receiving area of the movable partition 43 can be eased. As a result, the compression amount-reaction characteristic of the shock absorber 10 can be set to a desired characteristic, and the responsiveness of the movable partition 43 can be improved by increasing the pressure receiving area of the movable partition 43. Further, since the additional portion 40 is attached to the outside of the shock absorber main body 11, the replacement of the tubular portion 42 can be facilitated.

  Further, since the extending portion 41a extends in a direction perpendicular to the axis of the shock absorber main body 11 so that the cylindrical portion 42 is separated from the shock absorber main body 11, the cylindrical portion 42 extending toward the first end 11a of the shock absorber main body 11 is provided. The distance from the shock absorber main body 11 can be secured. Since the restrictions on the dimension of the cylindrical portion 42 in the direction perpendicular to the axis can be further relaxed, the constraints on the volume of the second additional chamber C4 and the pressure receiving area of the movable partition 43 can be further relaxed. As a result, the compression amount-reaction force characteristic of the shock absorber 10 can be set to a desired characteristic, and the responsiveness of the movable partition 43 can be further improved by increasing the pressure receiving area of the movable partition 43.

  Since the communication path 13a is a part of the first gas chamber C1, the volume of the first gas chamber C1 can be increased by the volume of the communication path 13a. Thereby, the volume of the first gas chamber C1 with respect to the volume of the second expansion chamber C4 can be adjusted to set the compression amount-reaction characteristic of the shock absorber 10 to a desired characteristic.

  When the shock absorber 10 is compressed, the first gas chamber C1 and the second gas chamber C2 are each compressed, so that a reaction force due to the compression of the shock absorber 10 (a reaction force for urging the shock absorber 10 in a direction in which the shock absorber 10 extends) is reduced. The reaction force caused by the compression of the first gas chamber C1 and the reaction force caused by the compression of the second gas chamber C2 can be shared. As a result, the pressure of the first gas chamber C1 can be reduced, so that the pressure of the second additional chamber C4 for moving the movable partition 43 can be also reduced according to the pressure relationship with the first gas chamber C1.

  As the pressures in the first gas chamber C1 and the second expansion chamber C4 are lower, for example, the sealing rings 14a, 14b, 43a, 43b have a smaller tension force, or sealing members such as the sealing rings 14a, 14b, 43a, 43b. And the dimensional accuracy of the part to be hermetically sealed (between the cylindrical portion 42 and the cap 44) is reduced to simplify the hermetic structure of the first gas chamber C1 and the second expansion chamber C4. it can. As a result, the manufacture of the shock absorber 10 can be facilitated.

  The lower the pressures of the first gas chamber C1 (the first additional chamber C3) and the second additional chamber C4, the smaller the tightening force (contact surface pressure) of the seal rings 43a and 43b. , 43b due to adhesion or sticking. Since the pressures in the first gas chamber C1 (the first expansion chamber C3) and the second expansion chamber C4 are low, the first gas chamber C1 and the first gas chamber C1 formed by the seal rings 43a and 43b are small even if the sealing force of the seal rings 43a and 43b is small. The airtightness of the second extension room C4 can be ensured. As a result, the responsiveness of the movable partition 43 to an increase in the pressure of the first gas chamber C1 can be improved while maintaining the airtightness of the first gas chamber C1 and the second expansion chamber C4.

  Further, the lower the pressure of the first gas chamber C1 and the second expansion chamber C4, the easier it is to inject (enclose) gas into the first gas chamber C1 and the second expansion chamber C4. The pressure in the first gas chamber C1 and the pressure in the second expansion chamber C4 can be easily adjusted by the second expansion chamber adjusting section 46. Furthermore, when the pressure in the first gas chamber C1 and the second expansion chamber C4 is high, the compression amount-reaction force characteristics of the shock absorber 10 may vary. Since the pressures of the first gas chamber C1 and the second additional chamber C4 can be reduced by the second gas chamber C2, the compression amount-reaction characteristic of the shock absorber 10 can be stabilized.

  When mounting the shock absorber 10 on a motorcycle, the shock absorber 10 is often provided obliquely with respect to the road surface such that the connection hole 32a is located above and the extension portion 40 is located below. Since the extending portion 41a extends obliquely in a direction perpendicular to the axis of the shock absorber main body 11, the extending portion 41a extends downward from the second end 11b of the shock absorber main body 11 in a state where the shock absorber 10 is provided on the motorcycle. Projection can be suppressed. As a result, it is possible to suppress the extension portion 41a (the extension portion 40) from contacting a road surface or the like.

  As described above, the present invention has been described based on the above embodiments. However, the present invention is not limited to the above embodiments, and it is easy to make various modifications without departing from the spirit of the present invention. It can be inferred. The shapes and dimensions of the shock absorber main body 11 and the additional portion 40 are merely examples, and it is naturally possible to adopt various shapes and dimensions. For example, the body-side tube 20, the axle-side tube 30, and the tubular portion 42 may be formed in an elliptical tubular shape.

  In the above embodiment, the case where the shock absorber main body 11 is an air suspension has been described. However, the present invention is not limited to this. The hydraulic shock absorber having the first gas chamber which is compressed when the shock absorber is compressed is used as the shock absorber. Naturally, it can be a main body. However, when the shock absorber main body 11 is a hydraulic shock absorber, the gas enclosed therein is affected by heat generated when the shock absorber absorbs an impact, and the compression amount-reaction characteristic becomes unstable. There is. In the above-described embodiment, the shock absorber main body 11 is formed as an air suspension in which a main shock is generated by the gas sealed inside (the first gas chamber C1 and the second gas chamber C2) (there is no shock by hydraulic pressure). Therefore, the compression amount-reaction force characteristics can be stabilized.

  In the above embodiment, the columnar movable partition 43 slides inside the cylindrical portion 42 having a constant inner diameter in the axial direction (the pressure receiving area of the movable partition 43 on the first extension chamber C3 side and the movable Although the case where the pressure receiving area of the partition 43 is equal to the pressure receiving area of the second additional chamber C4) has been described, the present invention is not necessarily limited to this, and the second area of the movable partition is smaller than the pressure receiving area of the movable partition in the first additional chamber C3. Naturally, it is possible to configure so that the pressure receiving area on the extension room C4 side is increased. For example, a cylindrical large-diameter portion and a cylindrical small-diameter portion having a smaller diameter (for example, the same diameter as the inner diameter of the cylinder 12) than the large-diameter portion are provided in the cylindrical portion, and a cylindrical shape that slides in the large-diameter portion. By providing the movable partition with a large-diameter sliding portion and a cylindrical small-diameter sliding portion that slides in the small-diameter portion and has a smaller diameter (for example, the same diameter as the outer shape of the piston 14) than the large-diameter sliding portion, The pressure receiving area of the movable partition on the second extension room C4 side can be made larger than that on the first extension room C3 side. Relationship between the first reaction force and the second reaction force when the pressure receiving area of the movable partition on the first extension chamber C3 side is equal to the pressure receiving area of the movable partition on the second extension chamber C4 side (position of predetermined value C) Is maintained, the pressure of the second expansion chamber C4 can be reduced as compared with the case where the pressure receiving area of the movable partition on the first expansion chamber C3 side is equal to the pressure receiving area of the movable partition on the second expansion chamber C4 side. As a result, the airtight structure of the second extension room C4 can be simplified, and the manufacture of the shock absorber can be facilitated. Furthermore, by changing the pressure receiving area of the movable partition on the first extension chamber C3 side and the pressure receiving area of the movable partition on the second extension chamber C4 side, the relationship between the first reaction force and the second reaction force is changed. The position of the predetermined value C and the manner of increasing the reaction force after the predetermined value C can be appropriately set, and the compression amount-reaction force characteristic of the shock absorber can be adjusted.

  Further, it is possible to dispose a coil spring for urging the movable partition 43 toward the first additional chamber C3 between the cap 44 and the movable partition 43 (inside the second additional chamber C4). Since the second reaction force can be compensated for by the elastic force of the coil spring, the pressure in the second additional chamber C4 can be reduced. Further, the first reaction force and the second reaction force depend on the pressure receiving area of the movable partition 43, while the elastic force of the coil spring does not depend on the pressure receiving area of the movable partition 43. The reaction force after the predetermined value C can be gradually increased while moving the predetermined value C to the first half side (left side in FIG. 3) of the compression operation. As a result, the compression amount-reaction characteristic of the shock absorber can be adjusted.

  In the above embodiment, the case where the axle-side tube 30 is inserted into the inner periphery of the vehicle-body-side tube 20 has been described. However, the present invention is not limited to this. It is of course possible to insert. Further, the present invention is not limited to the case where the cylinder 12 is disposed inside the vehicle body side tube 20 and the rod 13 is disposed inside the axle side tube 30. It is possible to arrange the cylinder 12 inside. When the cylinder 12 is disposed inside the axle-side tube 30, the inside of the cylinder 12 (the first air chamber C1) and the first additional chamber C3 are communicated without passing through the communication passage 13a of the rod 13.

  In the above embodiment, the first gas chamber C1 (the first gas chamber C1 formed on the first end 11a side with respect to the piston 14) is provided through the communication hole 14d of the piston 14 fixed to the upper end of the rod 13. ) And the communication path 13a of the rod 13 have been described. However, the present invention is not limited to this, and the rod 13 penetrates the piston 14 to directly communicate the first gas chamber C1 and the communication path 13a. It is of course possible.

  In the above embodiment, the case where the communication valve 47 is provided in the additional main body 41 has been described. However, the present invention is not limited to this, and the position of the communication valve 47 can be set as appropriate. For example, it can be provided on the inner and outer peripheral surfaces of the cap 21, the rod 13, the bottom bolt 34, and the like.

  In the above embodiment, the case where the tubular portion 42 is exchangeably attached to the additional main body portion 41 (attachment portion 41b) has been described, but the present invention is not necessarily limited to this. For example, there is a case where the axle-side fixing portion 31 in which the extension portion 40 is integrated is exchangeably attached to the axle-side tube 30. Further, it is also possible to integrate the additional main body 41 and the cylindrical part 42, detachably attach the additional main body 41 to the bracket 32, and replaceably mount the additional main part 40 to the shock absorber main body 11.

  In the above embodiment, the case where the overhanging portion 45 is provided on the tubular portion 42 has been described. However, the present invention is not limited to this. It is naturally possible to provide the overhanging portion inside the additional main body 41. is there. In addition, the contact surface of the additional main body 41 that contacts the lower end surface of the cylindrical portion 42 is made to protrude with respect to the inner peripheral surface of the cylindrical portion 42, thereby forming a projecting portion on the contact surface of the additional main body 41. It is possible.

  In the above embodiment, the extension portion 41a that extends obliquely in the direction perpendicular to the axis of the shock absorber main body 11 has been described. However, the present invention is not necessarily limited to this. It is of course possible to provide an extension.

  Further, it is possible to dispose a coil spring for urging the vehicle body side tube 20 and the axle side tube 30 in the extending direction between the cylinder 12 and the axle side fixing part 31. Thereby, the reaction force of the first gas chamber C1 and the second gas chamber C2 can be supplemented by the elastic force of the coil spring.

REFERENCE SIGNS LIST 10 shock absorber 11 shock absorber main body 11a first end 11b second end 12 cylinder 13 rod 13a communication passage 14 piston 20 vehicle body side tube 30 axle side tube 40 additional portion 41a extended portion 42 cylindrical portion 43 movable partition 46 second additional portion Room adjusting part 47 Communication valve C1 First gas chamber C2 Second gas chamber C3 First expansion chamber C4 Second expansion chamber

Claims (5)

A shock absorber main body that has a first end fixed to the vehicle body side and a second end fixed to the axle side, and buffers an impact;
An additional part that is attached to the outside of the shock absorber main body and in which gas is sealed inside,
A first gas chamber in which a gas is sealed;
A piston that compresses the gas in the first gas chamber when the first end and the second end approach each other ;
A cylinder fixed to the first end, wherein the piston slides inside;
A rod fixed to the second end and fixed to the piston .
The extension portion, a movable partition that slides inside the extension portion,
A first expansion chamber communicating with the first gas chamber, wherein the interior of the expansion section is defined by the movable partition;
A second extension room formed by partitioning the interior of the extension portion by the movable partition and being formed on the opposite side of the first extension room;
The movable partition moves toward the second expansion chamber with an increase in the pressure of the first gas chamber,
The extension portion is attached to the second end, and is formed from the second end to the first end side ,
The first gas chamber is formed inside the cylinder and closer to the first end than the piston,
The rod is a shock absorber according to claim Rukoto a communication passage for communicating the first expansion chamber and the first gas chamber. A shock absorber main body that has a first end fixed to the vehicle body side and a second end fixed to the axle side, and buffers an impact;
An additional part that is attached to the outside of the shock absorber main body and in which gas is sealed inside,
A first gas chamber in which a gas is sealed;
A piston that compresses the gas in the first gas chamber when the first end and the second end approach each other ;
A body-side tube formed from the first end toward the second end;
An axle-side tube formed from the second end toward the first end, which slides on the body-side tube;
A cylinder disposed inside the axle-side tube and the vehicle-body-side tube, wherein the piston slides inside and the first gas chamber is formed therein;
A second gas chamber formed between the cylinder and the axle-side tube and the body-side tube, in which gas is sealed ;
The extension portion, a movable partition that slides inside the extension portion,
A first expansion chamber communicating with the first gas chamber, wherein the interior of the expansion section is defined by the movable partition;
A second extension room formed by partitioning the interior of the extension portion by the movable partition and being formed on the opposite side of the first extension room;
The movable partition moves toward the second expansion chamber with an increase in the pressure of the first gas chamber,
The buffer unit is attached to the second end and formed from the second end to the first end. 3. The shock absorber according to claim 2, further comprising a communication valve that sends gas from the first gas chamber to the second gas chamber when the pressure of the first gas chamber exceeds a predetermined threshold. 4. The shock absorber according to any one of claims 1 to 3 , wherein a pressure receiving area of the movable partition on the first expansion chamber side is set to be larger than a pressure receiving area of the piston. The shock absorber according to any one of claims 1 to 4, further comprising a second additional chamber adjusting unit that adjusts a pressure of the second additional chamber.

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