JP6027514B2 - Shock absorber - Google Patents

Description

  The present invention relates to a shock absorber.

  The shock absorber is used for suppressing vibration in a vehicle, a device, a structure, or the like.

  For example, a shock absorber D3 referred to as a single cylinder shock absorber as shown in FIG. 7 includes a cylinder 1 and a hydraulic fluid chamber that is in sliding contact with the inner peripheral surface of the cylinder 1 and is filled with the hydraulic fluid. 2 and a free piston F partitioned into a gas chamber 4 in which gas is enclosed, a rod 3 that enters and exits the hydraulic fluid chamber 2 from one axial end of the cylinder 1, and a tip of the rod 3. A piston 6 that is in sliding contact with the inner peripheral surface of the cylinder 1 and divides the working fluid chamber 2 into an extension side chamber 20 and a pressure side chamber 21, a passage (not shown) that connects the extension side chamber 20 and the pressure side chamber 21, and an operation that passes through the passage. A damping valve (not shown) that provides resistance to the liquid.

  For this reason, when the cylinder 1 and the rod 3 move relative to each other in the axial direction by the input of vibration, the hydraulic fluid in one chamber (20 or 21) to be reduced passes through the passage and enters the other chamber (21 or 20). Since it moves, the shock absorber D3 generates a damping force due to the resistance of the damping valve when the hydraulic fluid passes through the passage. Further, when the rod 3 enters and exits the hydraulic fluid chamber 2, the volume of the hydraulic fluid chamber 2 does not change, although the volume of the rod 3 that has entered and exited and the internal volume of the cylinder 1 change. However, since the free piston F can move in the cylinder 1 in the axial direction while separating the hydraulic fluid chamber 2 and the air chamber 4, the volume of the air chamber 4 is changed, and the internal volume change of the cylinder 1 as the rod 3 enters and exits. Can be compensated for in the air chamber 4 (for example, Patent Document 1).

JP 11-153173 A

  When the air chamber 4 that compensates for the change in the internal volume of the cylinder 1 is partitioned by the free piston F as in the conventional shock absorber D3, an annular seal S such as an O-ring is generally provided on the outer periphery of the free piston F. It is. The outer diameter of the seal S is formed larger than the inner diameter of the cylinder 1 so as to have a tightening margin, and the seal S is slidably adhered to the inner peripheral surface of the cylinder 1 while being elastically deformed.

  When the tightening margin is increased, the airtightness is improved, but the sliding resistance between the cylinder 1 and the seal S is increased, and the free piston F is difficult to move. For this reason, for example, when the shock absorber D3 is compressed, the internal volume of the rod 3 entry volume integrating cylinder 1 is reduced. Therefore, it is preferable to rapidly retract the free piston F to reduce the air chamber 4 volume. The retraction of the free piston F is delayed due to the dynamic resistance, and the pressure in the pressure side chamber 21 increases instantaneously, so-called surge pressure is generated. Therefore, the desired damping force characteristic is not achieved, and the ride comfort of the vehicle is deteriorated.

  On the contrary, if the tightening margin is reduced, the surge pressure can be suppressed, but the airtightness is lowered, so that the gas is easily mixed in the working fluid. When gas is mixed in the hydraulic fluid, when one chamber (20 or 21) is pressurized by the piston 6, the gas mixed in the hydraulic fluid in this chamber is compressed and then the hydraulic fluid passes through a passage (not shown). Since it passes through and moves to the other chamber, the responsiveness of the generation of the damping force is lowered, and similarly, the ride comfort of the vehicle is deteriorated.

  That is, in the shock absorber D3 including the free piston F, there is a trade-off relationship between suppression of surge pressure and good response of generation of damping force, and it is difficult to achieve both of them. Accordingly, an object of the present invention is to provide a shock absorber capable of suppressing surge pressure and maintaining good response to generation of damping force.

  Means for solving the above problems include a cylinder, a hydraulic fluid chamber formed in the cylinder and filled with hydraulic fluid, a rod that enters and exits the hydraulic fluid chamber from one end in the axial direction of the cylinder, and a gas. Is provided with an ionic liquid that partitions the working fluid chamber and the air chamber in a shock absorber provided with an air chamber that compensates for the change in the cylinder volume corresponding to the volume of the rod that enters and exits the cylinder. .

  According to the shock absorber of the present invention, it is possible to suppress a surge pressure and to maintain a good response of generating a damping force.

It is the figure which showed in principle the buffer which concerns on one embodiment of this invention. It is the figure which showed in principle the modification of the buffer which concerns on one embodiment of this invention. It is the figure which showed in principle the buffer which concerns on other embodiment of this invention. It is the figure which showed in principle the 1st modification of the buffer which concerns on other embodiment of this invention. It is the figure which showed in principle the 2nd modification of the buffer which concerns on other embodiment of this invention. It is the figure which showed in principle the 3rd modification of the buffer which concerns on other embodiment of this invention. It is a longitudinal cross-sectional view of the conventional shock absorber.

  A shock absorber according to an embodiment of the present invention will be described below with reference to the drawings. The same reference numerals given throughout the several drawings indicate the same or corresponding parts. In FIG. 1 to FIG. 6, dots are marked in the portions where the ionic liquid is stored.

  As shown in FIG. 1, a shock absorber D1 according to the present embodiment includes a cylinder 1, a working fluid chamber 2 formed in the cylinder 1 and filled with working fluid, and one end of the cylinder 1 in the axial direction. A rod 3 that enters and exits the hydraulic fluid chamber 2 and an air chamber 4 that compensates for the volume change in the cylinder 1 corresponding to the volume of the rod 3 that enters and exits the cylinder 1 when gas is enclosed. An ionic liquid is provided to partition the chamber 2 and the air chamber 4. Reference numeral 5 in FIG. 1 denotes this ionic liquid layer.

  Hereinafter, in detail, the shock absorber D1 according to the present embodiment is a vertical shock absorber interposed between a vehicle body and a wheel in a vehicle such as an automobile or a two-wheeled vehicle, and has a predetermined damping force. Suppresses the impact caused by road surface unevenness from being transmitted to the vehicle body. In addition, the shock absorber according to the present invention may be used other than the vehicle.

  In the present embodiment, the shock absorber D1 is set upside down, and includes a cylindrical cylinder 1 in which end portions in the axial direction are arranged up and down, and an annular rod guide 10 that closes a lower opening of the cylinder 1. The bottom cap 11 that closes the upper opening of the cylinder 1, the rod 3 that is pivotally supported by the rod guide 10 and enters and exits the cylinder 1 from the lower end of the cylinder 1, and the inner periphery of the cylinder 1 that is held by the upper end of the rod 3 A piston 6 slidably in contact with the surface and a bottomed cylindrical cover 7 in which the rod 3 rises at the axial center and the cylinder 1 enters and exits are provided. Although not shown, a mounting portion for connecting the shock absorber D1 to the vehicle body side is fixed to the bottom cap 11, and a mounting portion for connecting the shock absorber D1 to the wheel side is fixed to the bottom portion of the cover 7. Since it is fixed, when an impact due to road surface unevenness is input, the cylinder 1 enters and exits the cover 7 and the rod 3 enters and exits the cylinder 1 and the shock absorber D1 expands and contracts.

  In the cylinder 1, a working fluid, an ionic liquid, and a gas are sealed. As the hydraulic fluid or gas, a well-known configuration can be adopted. In the present embodiment, the hydraulic fluid is an operation in which additives such as an antioxidant, an antifoaming agent, a friction modifier, etc. are added to the base oil. It is an oil called oil, and the gas is an inert gas such as nitrogen. An ionic liquid is a liquid composed only of ions and consisting of organic ions (cations or anions, both) and has a melting point near room temperature. In the present embodiment, an ionic liquid is used that has a specific gravity smaller than that of the working fluid, has a property of separating from the working fluid, and has a property of hardly dissolving the gas. For this reason, the ionic liquid is separated from the hydraulic fluid and stored in layers above the liquid level of the hydraulic fluid to form the ionic liquid layer 5 and the gas is enclosed above the liquid level 5a of the ionic liquid. Is done. In other words, according to the above configuration, the hydraulic fluid chamber 2 in which the hydraulic fluid is stored and the gas chamber 4 in which the gas is sealed are partitioned by the ionic liquid layer 5 and on the liquid surfaces 5a and 5b of the ionic liquid. Touch. The hydraulic fluid according to the present invention may be a liquid such as water or an aqueous solution, and the gas may be air. In addition, the ionic liquid according to the present invention uses various ionic liquids as long as it can be separated from the hydraulic fluid to form the ionic liquid layer 5 and partition the hydraulic fluid chamber 2 and the air chamber 4. It is possible.

  The hydraulic fluid chamber 2 filled with the hydraulic fluid is partitioned vertically by the piston 6, and is formed on the lower side of the piston 6 and through which the rod 3 penetrates, and on the upper side of the piston 6. The pressure surface chamber 21 is in contact with the ionic liquid. The extension side chamber 20 and the pressure side chamber 21 communicate with each other via an extension side passage 60 and a pressure side passage 61 formed in the piston 6. The extension side passage 60 is provided with an extension side damping valve V1 that allows the flow of hydraulic fluid from the extension side chamber 20 toward the compression side chamber 21 through the extension side passage 60 and prevents the flow in the opposite direction. On the other hand, the pressure side passage 61 is provided with a pressure side damping valve V2 that allows the flow of hydraulic fluid from the pressure side chamber 21 toward the extension side chamber 20 through the pressure side passage 61 and prevents the flow in the opposite direction.

  Hereinafter, the operation of the shock absorber D1 according to the present embodiment will be described.

  When the shock absorber D1 is extended when the cylinder 1 is withdrawn from the cover 7 and the rod 3 is withdrawn from the cylinder 1, the hydraulic fluid in the expansion side chamber 20 to be reduced is expanded into the pressure side chamber 21 that opens and expands the expansion side damping valve V1. Since it moves, shock absorber D1 generates extension side damping force resulting from resistance of extension side damping valve V1. Further, when the shock absorber D1 is extended, the internal volume of the rod 3 integral cylinder 1 retracted from the cylinder 1 increases, so that the ionic liquid layer 5 moves downward in FIG. 1 together with the liquid surface of the compression side chamber 20, The air chamber 4 expands.

  On the contrary, the expansion side chamber in which the hydraulic fluid in the compression side chamber 21 to be reduced opens the compression side damping valve V2 and expands when the shock absorber D1 in which the rod 3 enters the cover 1 and the rod 3 enters the cylinder 1 is compressed. Therefore, the shock absorber D1 generates a compression side damping force due to the resistance of the compression side damping valve V2. Further, when the shock absorber D1 is compressed, the internal volume of the rod 3 volume integrating cylinder 1 that has entered the cylinder 1 is reduced, so that the ionic liquid layer 5 moves upward in FIG. Chamber 4 is compressed.

  Hereinafter, the effect of the buffer D1 which concerns on this Embodiment is demonstrated.

  In the present embodiment, the specific gravity of the ionic liquid is set smaller than the specific gravity of the working fluid. Further, the rod 3 is inserted into the hydraulic fluid chamber 2 from the lower end of the cylinder 1 in which the axial end portions are arranged vertically.

  According to the above configuration, the shock absorber D1 is set upside down, and the ionic liquid separated from the hydraulic fluid is stored in a layered manner on the upper side of the hydraulic fluid, and the air chamber 4 is formed above the layer 5 of the ionic liquid. Therefore, it is easy to form the air chamber 4 in the cylinder 1. However, as described later, the specific gravity of the ionic liquid may be set larger than the specific gravity of the working fluid. Further, even when the specific gravity of the ionic liquid is set smaller than the specific gravity of the working fluid, the shock absorber D1 may be set upright, and an example of such a shock absorber is shown in FIG. The shock absorber D1 shown in FIG. 2 includes a tank 8 that is externally attached to the cylinder 1 and a passage 12 that allows the tank 8 and the cylinder 1 to communicate with each other. The hydraulic fluid can move between the cylinder 1 and the tank 8 through the passage 12, and an ionic liquid layer 5 is formed on the upper side of the hydraulic fluid in the tank 8. An air chamber 4 is formed on the upper side of 5a.

  Further, in the present embodiment, the shock absorber D1 includes the cylinder 1, the hydraulic fluid chamber 2 formed in the cylinder 1 and filled with the hydraulic fluid, and the hydraulic fluid chamber from one end of the cylinder 1 in the axial direction. A rod 3 that enters and exits 2 and an air chamber 4 that compensates for the volume change in the cylinder 1 corresponding to the volume of the rod 3 that enters and exits the cylinder 1 when gas is enclosed, and the hydraulic fluid chamber 2 and the air An ionic liquid that separates the chamber 4 is provided.

  According to the above configuration, even if the ionic liquid moves in the cylinder 1 or the tank 8, since the ionic liquid is made of liquid, it can move with little resistance to the cylinder 1 or the tank 8, and suppresses the surge pressure. be able to. In addition, since the ionic liquid is separated from the working liquid and has a property that it is difficult to dissolve the gas, the working liquid chamber 2 and the air chamber 4 can be partitioned by the ionic liquid, and the gas is mixed into the working liquid. Can be suppressed, and the responsiveness of the generation of damping force can be maintained well.

  Next, a shock absorber D2 according to another embodiment of the present invention will be described in detail. As shown in FIG. 3, the shock absorber D2 according to the present embodiment is a vertical shock absorber that is interposed between a vehicle body and wheels in a vehicle such as an automobile or a two-wheeled vehicle, as in the case of the first embodiment. And a predetermined damping force is generated to suppress an impact caused by road surface unevenness from being transmitted to the vehicle body.

  In the present embodiment, the shock absorber D <b> 2 is set upright, and has a cylindrical cylinder 1 in which axial ends are arranged vertically, and an annular rod guide 10 that closes the upper opening of the cylinder 1. A bottom cap 11 that closes the lower opening of the cylinder 1, a rod 3 that is pivotally supported by the rod guide 10 and enters and exits the cylinder 1 from the upper end of the cylinder 1, and is held by the lower end of the rod 3. And a piston 6 slidably in contact with the inner peripheral surface. Although not shown, a mounting portion for connecting the shock absorber D2 to the vehicle body side is fixed to the upper end portion of the rod 3, and a mounting portion for connecting the shock absorber D2 to the wheel side is fixed to the bottom cap 11. Therefore, when an impact due to road surface unevenness is input, the rod 3 enters and exits the cylinder 1 and the shock absorber D2 expands and contracts.

  In the cylinder 1, a working fluid, an ionic liquid, and a gas are sealed. Also in the present embodiment, the hydraulic fluid is an oil called hydraulic oil obtained by adding an additive such as an antioxidant, an antifoaming agent, or a friction modifier to the base oil, and the gas is inert such as nitrogen. Gas. Also in the present embodiment, the ionic liquid is separated from the hydraulic fluid and has a property that the gas is difficult to dissolve. However, unlike the exemplary embodiment, an ionic liquid having a larger specific gravity than the hydraulic fluid is used. ing. For this reason, the ionic liquid is separated from the working fluid and stored in layers in the lower side of the working fluid to form the ionic liquid layer 5 and the gas chamber 4 in which the gas is enclosed is the ionic liquid layer 5. It is defined in.

  Specifically, an annular plate-shaped partition body 9 that divides the ionic liquid layer 5 into the upper and lower sides of the air chamber 4 is fixed in the cylinder 1, and one end opens above the partition body 9. A communication passage 91 having the other end opened in the ionic liquid stored below the air chamber 4 is provided. In the present embodiment, the communication passage 91 is formed in a tubular shape, opens at the center of the partition wall body 9, and extends vertically from the partition body 9 to the lower side in FIG. 3. The air chamber 4 is formed on the outer periphery of the communication passage 91 from the upper side of the lower ionic liquid level 5 a to the partition wall 9. That is, also in the present embodiment, the working fluid chamber 2 in which the working fluid is stored and the gas chamber 4 in which the gas is sealed are partitioned by the ionic liquid layer 5 and the ionic liquid levels 5a and 5b. Is in contact with

  The hydraulic fluid chamber 2 filled with the hydraulic fluid is partitioned vertically by the piston 6 as in the embodiment, and is formed on the upper side of the piston 6 so that the rod 3 passes therethrough, and the piston 6. The pressure side chamber 21 is formed on the lower side and the lower liquid surface is in contact with the ionic liquid. The extension side chamber 20 and the pressure side chamber 21 communicate with each other via an extension side passage 60 and a pressure side passage 61 formed in the piston 6. The extension side passage 60 is provided with an extension side damping valve V1 that allows the flow of hydraulic fluid from the extension side chamber 20 toward the compression side chamber 21 through the extension side passage 60 and prevents the flow in the opposite direction. On the other hand, the pressure side passage 61 is provided with a pressure side damping valve V2 that allows the flow of hydraulic fluid from the pressure side chamber 21 toward the extension side chamber 20 through the pressure side passage 61 and prevents the flow in the opposite direction.

  Hereinafter, the operation of the shock absorber D2 according to the present embodiment will be described.

  At the time of expansion of the shock absorber D2 in which the rod 3 retreats from the cylinder 1, the hydraulic fluid in the expansion side chamber 20 to be contracted moves to the compression side chamber 21 that opens and expands the expansion side damping valve V1, so that the shock absorber D2 is expanded. An extension side damping force due to the resistance of the side damping valve V1 is generated. Further, when the shock absorber D2 is extended, the internal volume of the rod 3 integral cylinder 1 retracted from the cylinder 1 increases, so that the ionic liquid stored in the lower side of the air chamber 4 passes through the communication passage 91 and enters the partition wall 9 And the air chamber 4 is enlarged.

  On the contrary, when the shock absorber D2 in which the rod 3 enters the cylinder 1 is compressed, the hydraulic fluid in the compression side chamber 21 to be reduced moves to the expansion side chamber 20 that opens and expands the compression side damping valve V2, so that the shock absorber D2 is The pressure side damping force due to the resistance of the pressure side damping valve V2 is generated. Further, when the shock absorber D2 is compressed, the volume of the rod 3 integral cylinder 1 that has entered the cylinder 1 is reduced, so that the ionic liquid stored on the upper side of the partition wall 9 passes through the communication passage 91 and enters the air chamber 4. It moves to the lower side and the air chamber 4 is compressed.

  Hereinafter, the effect of the buffer D2 which concerns on this Embodiment is demonstrated.

  In the present embodiment, the air chamber 4 is formed in the cylinder 1, and the ionic liquid is stored on the upper side and the lower side of the air chamber 4. The shock absorber D2 includes a partition body 9 that partitions the air chamber 4 and an ionic liquid that is fixed in the cylinder 1 and stored on the upper side of the air chamber 4, and one end that opens to the upper side of the partition body 9 and the other end. Is provided with a communication passage 91 that opens into the ionic liquid stored below the air chamber 4.

  According to the above configuration, the specific gravity of the ionic liquid is set to be larger than the specific gravity of the working fluid, and even if the shock absorber D2 is set to the upright type, the volume change in the cylinder 1 is changed in the cylinder 1. It is possible to easily form the air chamber 4 that compensates for the above. In the present embodiment, the communication passage 91 is formed in a tubular shape and opens at the center of the partition wall body 9 and is arranged at the center of the cylinder 1. However, the configuration of the partition wall body 9 and the communication passage 91 is appropriately set. It is possible to change. For example, as shown in FIG. 4, the communication path 91 may be arranged close to the inner peripheral surface of the cylinder 1, and as shown in FIG. The cylindrical gap formed between the cylindrical portion 92a of the cup 92 and the cylinder 1 may be used as the communication path of the present invention, and the ceiling portion 92b of the cup 92 may be used as the partition wall of the present invention. .

  In the present embodiment, the specific gravity of the ionic liquid is set larger than the specific gravity of the working fluid. Further, the rod 3 is inserted into the hydraulic fluid chamber 2 from the upper end of the cylinder 1 in which the axial end portions are arranged vertically.

  According to the above configuration, the shock absorber D2 can be set upright, and the ionic liquid separated from the working fluid can be stored in a layered manner below the working fluid. In the present embodiment, the air chamber 4 is formed in the cylinder 1, but as shown in FIG. 6, a tank 8 externally attached to the cylinder 1 and a passage communicating the tank 8 and the cylinder 1. 12, the ionic liquid can move between the cylinder 1 and the tank 8 through the passage 12, and the air chamber 4 is formed above the liquid surface 5 a of the ionic liquid in the tank 8. Also good.

  In the present embodiment, the shock absorber D2 includes the cylinder 1, the hydraulic fluid chamber 2 formed in the cylinder 1 and filled with the hydraulic fluid, and the hydraulic fluid chamber from one end of the cylinder 1 in the axial direction. A rod 3 that enters and exits 2 and an air chamber 4 that compensates for the volume change in the cylinder 1 corresponding to the volume of the rod 3 that enters and exits the cylinder 1 when gas is enclosed, and the hydraulic fluid chamber 2 and the air An ionic liquid that separates the chamber 4 is provided.

  According to the above configuration, even if the ionic liquid moves in the cylinder 1 or the tank 8, since the ionic liquid is made of liquid, it can move with little resistance to the cylinder 1 or the tank 8 and suppress the surge pressure. be able to. In addition, since the ionic liquid is separated from the working liquid and has a property that it is difficult to dissolve the gas, the working liquid chamber 2 and the air chamber 4 can be partitioned by the ionic liquid, and the gas is mixed into the working liquid. Can be suppressed, and the responsiveness of the generation of damping force can be maintained well.

  Although preferred embodiments of the present invention have been described in detail above, it should be understood that modifications, variations and changes may be made without departing from the scope of the claims.

D1, D2 Buffer 1 Cylinder 2 Working fluid chamber 3 Rod 4 Air chamber 5 Ionic liquid layer 5a Ionic liquid level 8 Tank 9 Partition body 12 Path 91 Communication path

Claims (5)

A cylinder, a hydraulic fluid chamber formed in the cylinder and filled with a hydraulic fluid, a rod that enters and exits the hydraulic fluid chamber from one end in the axial direction of the cylinder, and the gas that is enclosed in and out of the cylinder. In a shock absorber comprising an air chamber that compensates for the change in volume in the cylinder corresponding to the rod volume,
A shock absorber comprising an ionic liquid that partitions the working fluid chamber and the air chamber. The specific gravity of the ionic liquid is set smaller than the specific gravity of the hydraulic fluid,
2. The shock absorber according to claim 1, wherein the rod is inserted into the hydraulic fluid chamber from a lower end of the cylinder in which end portions in an axial direction are vertically arranged. 3. The specific gravity of the ionic liquid is set larger than the specific gravity of the hydraulic fluid,
2. The shock absorber according to claim 1, wherein the rod is inserted into the hydraulic fluid chamber from an upper end of the cylinder in which end portions in the axial direction are arranged vertically. 3. The air chamber is formed in the cylinder, and the ionic liquid is stored on the upper side and the lower side of the air chamber,
A partition body that partitions the ionic liquid and the air chamber that is fixed in the cylinder and is stored on the upper side of the air chamber, one end that opens above the partition body, and the other end that is the lower side of the air chamber The shock absorber according to claim 3, further comprising: a communication path that opens into the ionic liquid stored in the buffer. A tank externally attached to the cylinder, and a passage communicating the tank and the cylinder,
The ionic liquid moves between the cylinder and the tank through the passage, and the air chamber is formed above the liquid surface of the ionic liquid stored in the tank. The shock absorber according to claim 3.

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