JP2010151301A - Damping force variable damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a damping force variable damper which can suppress an abrupt rise of a damping force when receiving a large input which is instantaneously inputted, and can improve ride comfortableness when riding over the large irregularity of a road face during traveling on an unfinished road or the like. <P>SOLUTION: The damping force variable damper 1 includes: a cylinder 2 filled with fluid therein; a piston rod 3 which is arranged so as to penetrate one end of the cylinder 2; a slide-moving piston 4 which is arranged so as to be relatively movable with respect to the piston rod 3 in the cylinder 2, and partitions the inside of the cylinder 2 into a first operation chamber 21 and a second operation chamber 22; a first communication passage 4a which is formed at the slide-moving piston 4, and makes the first operation chamber 21 and the second operation chamber 22 communicate with each other; a first leaf valve 41 which opens and closes the first communication passage 4a; and a piston displacement amount adjustment means 5 which adjusts the piston displacement amount of the slide-moving piston 4 according to the moving speed of the piston rod 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a damping force variable damper that is used in a vehicle suspension device and can vary a damping force.

FIG. 9 is a graph showing the relationship between damping force and piston speed in a conventional damping force variable damper.
In recent years, a mechanism for adjusting the damping force characteristic of a vehicle damper is desired in order to improve the riding comfort of the vehicle.
As shown in FIG. 9, a conventional damper for a vehicle has a large change in damping force in a region where the piston speed of the piston moving up and down in the cylinder is very low, and a damping force in a region where the piston speed is low and medium. There is known a damping force variable damper having a damping characteristic that changes the amount of noise (see, for example, Patent Document 1).

When the damping force variable damper is expanding and contracting in the very low speed range, only the outer periphery of the leaf valve is deflected and the hydraulic oil flows without compressing the spring, and the damping force depends on the opening of the leaf valve. Is occurring. For this reason, as shown in FIG. 9, the slope of the rise is large in the very low speed region.
After the low and medium speed range, a damping force is generated by opening the whole together with bending of the outer peripheral portion of the leaf valve while pushing and shrinking the spring. For this reason, as shown in FIG. 9, after the low to medium speed range, the rising slope when the damping force is generated is smaller than that at the very low speed, and the damping force characteristic is such that the increasing rate of the damping force is also reduced.

JP-A-9-291196 (Claim 1 and FIG. 1)

FIG. 10 is a graph showing the damping force characteristics of the damping force variable damper described in Patent Document 1. (a) shows the relationship between the piston speed and the damping force, and (b) shows the time vs. damping force. Show the relationship.
As shown in FIG. 10 (a), the damping force variable damper described in the above-mentioned Patent Document 1 has a smaller damping force when the piston speed is higher than when no spring is provided on the piston. The ride comfort is prevented from deteriorating.
However, the damping force variable damper of Patent Document 1 is proportional to the increase in piston speed when overcoming large unevenness when traveling on an undeveloped road with large unevenness on the road surface, as shown in FIG. 10 (b). As a result, the damping force suddenly increases, which causes a problem of deteriorating ride comfort performance.

  In the technique of Patent Document 1, since the damping force suddenly rises (that is, a large damping force is generated immediately when a large input is applied), a so-called “hardness” derived from the magnitude of the damping force appears in the damper. Therefore, there is a problem that ride comfort may be deteriorated.

  Therefore, the present invention has been invented to solve the above-mentioned problems, and when a large input that is instantaneously received is received when traveling over an uneven road surface while traveling on an undeveloped road or the like. Another object of the present invention is to provide a damping force variable damper capable of reducing a sudden increase in damping force and improving riding comfort.

  In order to solve the above-mentioned problem, the invention of a damping force variable damper according to claim 1 is a damping force variable damper used in a vehicle suspension device, which makes the damping force variable, and a cylinder filled with a fluid. And a piston rod provided so as to penetrate one end of the cylinder, a piston rod provided in the cylinder so as to be movable relative to the piston rod, and a first working chamber and a second working chamber inside the cylinder. A sliding piston that is partitioned into a first communicating passage that is formed in the sliding piston and communicates between the first working chamber and the second working chamber, and a valve that opens and closes the first communicating passage. And a piston displacement amount adjusting means for adjusting a piston displacement amount of the sliding piston in accordance with a moving speed of the piston rod.

  According to this configuration, the damping force variable damper includes the piston displacement amount adjusting means that can adjust the piston displacement amount of the sliding piston according to the moving speed of the piston rod, so that the vehicle has a large unevenness on the road surface. When a large input load is applied when overcoming such as, the piston displacement amount of the sliding piston can be set later with respect to the piston rod. For this reason, when the sliding piston slides, the flow rate of the fluid (hydraulic oil) passing through the first communication path can be reduced, and the rising of the damping force can be made smooth. As a result, when traveling on an undeveloped road or the like having large unevenness on the road surface, it is possible to reduce the sudden increase in damping force and improve the riding comfort.

  The invention of a variable damping force damper according to claim 2 is the variable damping force damper according to claim 1, wherein the piston rod communicates between the first working chamber and the second working chamber. A second communication path is arranged on the radially inner side of the sliding piston, and the piston displacement adjusting means is configured to adjust the first working chamber and the first by the second communication path according to the sliding state of the sliding piston. The communication state between two working chambers is adjusted.

  According to this configuration, the damping force variable damper includes a piston displacement amount adjusting unit that adjusts the communication state between the first working chamber and the second working chamber by the second communication path according to the sliding state of the sliding piston. It is possible to adjust so that the sliding piston slides and the second communication path is opened when a large input load is applied when the vehicle gets over a large unevenness on the road surface. Become. Thereby, the magnitude | size of the damping force after standing up can be reduced, and the riding comfort of a vehicle can be improved.

  The damping force variable damper according to a third aspect of the present invention is the damping force variable damper according to the second aspect, wherein the piston displacement amount adjusting means is supported by the sliding piston or the piston rod, and Urging means for urging the moving piston in the axial direction, and the sliding piston slides against the urging force of the urging means according to the moving speed of the piston rod; The area of the opening facing the first working chamber or the second working chamber is adjusted.

  According to such a configuration, the piston displacement amount adjusting means includes the biasing means that is supported by the sliding piston or the piston rod and biases the sliding piston in the axial direction. For this reason, when the piston rod moves with acceleration due to an external input load, the sliding piston tries to stay at the position so far, so that the urging means expands and contracts according to the acceleration. As a result, the positional relationship between the sliding piston and the piston rod as well as the positional relationship between the sliding piston and the opening is determined according to the amount of expansion and contraction of the urging means, and the first working chamber or The area of the opening facing the second working chamber can be adjusted. For this reason, the displacement of the damping force of the damping force variable damper can be made gentle to suppress the feeling of rigidity, and a comfortable riding comfort can be achieved.

  The invention of a damping force variable damper according to claim 4 is the damping force variable damper according to any one of claims 1 to 3, wherein the sliding piston and the valve are clamped in the axial direction. In addition, a sliding portion is provided that fits both from the inside in the radial direction and slides on the outer peripheral surface of the piston rod to open and close the second communication path.

According to such a configuration, the damping force variable damper can be assembled to the piston rod at a time with the sliding piston and the valve assembled, thereby reducing the number of assembling steps and improving the assembling performance. be able to.
In the sliding piston, the sliding part has a function of a sliding surface where the sliding piston and the piston rod are in sliding contact, a function of a valve body for opening and closing the second communication path, and an opening of the second communication path. Since the area can be adjusted, the number of parts can be reduced and the structure of the entire damper can be simplified.

  According to the damping force variable damper according to the present invention, the damping force rapidly increases when receiving a large input momentarily when traveling over a large unevenness on the road surface while traveling on an undeveloped road or the like. It is possible to improve the ride comfort.

It is principal part sectional drawing which shows the damping force variable damper which concerns on embodiment of this invention. It is a principal part expanded sectional view which shows the damping-force variable damper which concerns on embodiment of this invention. It is a principal part expansion perspective view which has a cross section which shows the damping-force variable damper which concerns on embodiment of this invention. It is an enlarged view which shows the shape of the 1st leaf valve before attaching to a damping-force variable damper, (a) is a top view, (b) is AA division | segmentation sectional drawing of (a). It is a figure which shows the action | operation of the damping force variable damper which concerns on embodiment of this invention, (a) is a principal part expanded sectional view which shows a state when the input load of a piston rod is small, (b) is the input load of a piston rod. It is a principal part expanded sectional view which shows a state when is large. It is a graph which shows the relationship between the damping force and piston speed, and time in the damping force variable damper which concerns on embodiment of this invention. It is a graph which shows the relationship between the damping force and time in the damping force variable damper which concerns on embodiment of this invention. It is an operation | movement figure which shows the modification of the damping force variable damper which concerns on embodiment of this invention, (a) is a principal part expanded sectional view which shows a state when the input load of a piston rod is small, (b) is a piston rod of a piston rod. It is a principal part expanded sectional view which shows a state when an input load is large. It is a graph which shows the relationship between the damping force and piston speed in the conventional damping force variable damper. It is a graph which shows the damping force characteristic of the damping force variable damper described in patent document 1, (a) shows the relationship between piston speed and damping force, (b) shows the relationship between time and damping force.

First, a damping force variable damper according to an embodiment of the present invention will be described with reference to FIGS.
Note that the damping force variable damper 1 according to the embodiment of the present invention changes in the vertical direction or the like depending on the installation state. Hereinafter, the case where the piston rod 3 is disposed on the upper side and the cylinder 2 is disposed on the lower side will be described as an example.

≪Configuration of damping force variable damper≫
A damping force variable damper 1 shown in FIG. 1 is used in a suspension device for a vehicle such as a motorcycle or a four-wheeled vehicle, and quickly damps up and down impacts and vibrations applied to the vehicle due to road surface unevenness while the vehicle is running. For this reason, the damping force can be made variable.
As shown in FIGS. 2 and 3, the variable damping force damper 1 includes a cylinder 2, a piston rod 3, a sliding piston 4, a first communication path 4a, a second communication path 3f, which will be described later, The third communication passage 4b, the first leaf valve 41, the second leaf valve 42, the sliding portion 43, the valve holding member 44, the piston displacement adjustment means 5, the biasing means 51, and the spring seat 6 And a fastening member 7. The damping force variable damper 1 has a vehicle body side mounting portion 3a (see FIG. 1) at the upper end portion of the piston rod 3 inserted into the cylinder 2 attached to the vehicle body, and an axle side mounting portion 2a at the lower end portion of the cylinder 2 (see FIG. 1). ) Is attached to the axle.

≪Cylinder configuration≫
The cylinder 2 is formed of a cylindrical body whose inside is filled with a fluid such as oil or a gas such as air and whose upper and lower ends are closed (see FIG. 1). The cylinder 2 is partitioned into two chambers, a first working chamber 21 and a second working chamber 22, by a sliding piston 4 slidably provided in the cylinder 2.

<Configuration of first working chamber and second working chamber>
As shown in FIGS. 2 and 3, the first working chamber 21 and the second working chamber 22 are formed on the upper side in the cylinder 2 with the sliding piston 4 interposed therebetween. Two working chambers 22 are formed below the sliding piston 4. The fluid flows from the second working chamber 22 to the first working chamber 21 via the first communication passage 4a described later when the first leaf valve 41 is opened by the displacement of the sliding piston 4. Further, when the slide bush 45 (sliding portion 43) having a valve function is lifted and the fluid is opened, the fluid flows from the second working chamber 22 through the second communication passage 3f to the first working chamber 21. To flow. Furthermore, when the second leaf valve 42 is opened, the fluid flows from the first working chamber 21 to the second working chamber 22 through the third communication passage 4b formed in the sliding piston 4. It has become.

≪Piston rod configuration≫
The piston rod 3 is disposed in a state where the upper side where the vehicle body side mounting portion 3a (see FIG. 1) is exposed from the cylinder 2, and the lower end side is disposed in the cylinder 2 through the upper end of the cylinder 2. 2 is installed so as to be movable up and down. At the lower end of the piston rod 3, a step part 3b, a small diameter part 3c, a male screw part 3d, an outer peripheral surface 3e, a second communication passage 3f, and openings 3g and 3h (see FIG. )) Is formed.

The step portion 3b is a portion where the spring seat 6 fitted on the small diameter portion 3c is abutted and locked, and is formed at the upper end of the small diameter portion 3c.
The small diameter portion 3c is a portion where the spring seat 6, the slide bush 45, and the urging means 51 are slidably fitted.
The male screw portion 3 d is a portion where the female screw portion of the fastening member 7 is screwed, and is formed at the lowermost end portion of the piston rod 3.

<Configuration of outer peripheral surface, second communication path and opening>
The outer peripheral surface 3e is the entire side surface of the piston rod 3, and includes the small diameter portion 3c and the like.
The second communication path 3f is a flow path formed in the small diameter portion 3c of the piston rod 3 and through which the fluid flows. The second communication path 3f is composed of, for example, a plurality of grooves formed on the outer peripheral surface 3e of the piston rod 3 in the axial direction. The second communication passage 3 f is a groove-like flow path for communicating between the first working chamber 21 and the second working chamber 22, and is formed on the radially inner side of the sliding piston 4.
The openings 3g and 3h (see FIG. 5B) are exposed portions of the second communication passage 3f that is opened and closed by the slide bush 45 of the sliding piston 4 fitted on the small diameter portion 3c. The opening 3g (see FIG. 5B) is a lower opening portion of the second communication passage 3f communicating with the second working chamber 22. The opening 3 h is an upper opening portion of the second communication passage 3 f that communicates with the first working chamber 21.

≪Sliding piston configuration≫
As shown in FIGS. 2 and 3, the sliding piston 4 is a piston that is slidably provided in the cylinder 2 so as to be relatively movable in the vertical direction while being guided with respect to the piston rod 3. The sliding piston 4 is formed in a thick, substantially disk shape, and has a plurality of first communication passages 4a, a plurality of third communication passages 4b, and one through hole 4c. The sliding piston 4 is provided with a first leaf valve 41 that opens and closes the first communication passage 4a on the first working chamber 21 side, and a second leaf valve that opens and closes the third communication passage 4b on the second working chamber 22 side. A leaf valve 42 is provided, a sliding portion 43 is fitted on the inner wall surface of the through hole 4c drilled in the center portion, and a piston ring 46 is fitted on the outer peripheral surface. The sliding piston 4 separates the inside of the cylinder 2 into a first working chamber 21 and a second working chamber 22.

  When the wheel bounces, the sliding piston 4 is pushed by the fluid in the lower second working chamber 22 by the sliding piston 4 and passes through the first communication path 4a and the second communication path 3f. The impact is absorbed by the orifice throttling effect when moving to the first working chamber 21 and the elasticity of the biasing means 51 to be described later. When the wheel rebounds, the sliding piston 4 is pressed by the fluid in the first working chamber 21 on the upper side in the cylinder 2 through the third communication passage 4b. The input is attenuated by the orifice throttling effect when moving to the second working chamber 22.

  The sliding piston 4 is fitted in the small diameter portion 3c of the piston rod 3 so as to be movable in the axial direction through a valve holding member 44 and a slide bush 45. The sliding piston 4 has a first operation between a spring seat 6 locked to a step 3b formed at the upper end of the small diameter portion 3c and a fastening member 7 fixed to the lower end of the small diameter portion 3c. The upper side facing the chamber 21 is always pressed by the biasing means 51, and the lower side facing the second working chamber 22 is always pressed by the reaction force of the spring force of the biasing means 51, so that the vertical movement is elastic. Is regulated.

<Configuration of the first communication passage>
The first communication path 4 a (communication path) is a flow path that is formed in the axial direction near the outer periphery of the sliding piston 4, and the upper open end is closed by the first leaf valve 41 in normal times. The first communication passage 4a opens the first leaf valve 41 so that the second working chamber 22 and the first working chamber 21 communicate with each other. It flows to the first working chamber 21 side through the one communication passage 4a.

<Configuration of the third communication passage>
The third communication path 4b (communication path) is a flow path that is drilled in the axial direction toward the center of the sliding piston 4, and the lower opening end is normally closed by the second leaf valve 42. Yes. In the third communication passage 4b, when the second leaf valve 42 is opened, the first working chamber 21 and the second working chamber 22 communicate with each other, and the fluid in the first working chamber 21 receives the first fluid. It flows to the second working chamber 22 side through the three communication passages 4b.

  4A and 4B are enlarged views showing the shape of the first leaf valve before being attached to the damping force variable damper. FIG. 4A is a plan view, and FIG. 4B is an AA exploded sectional view of FIG.

≪Configuration of first leaf valve≫
As shown in FIGS. 2 and 3, the first leaf valve 41 (valve) is a fluid that passes through the first communication passage 4 a from the second working chamber 22 side with respect to the spring force of the first leaf valve 41. This is a valve element that opens when the force in the direction of opening the first leaf valve 41 increases due to the pressure of. The first leaf valve 41 is a check valve that, when opened, allows the liquid in the second working chamber 22 to flow to the first working chamber 21 side through the first communication passage 4a. An opening end of the first communication passage 4 a on the first working chamber 21 side is a valve seat of the first leaf valve 41.
As shown in FIGS. 4A and 4B, the first leaf valve 41 has a plurality of insertion holes 41b arranged in the center and into which the valve holding member 44 is inserted, and a plurality of arrangements around the insertion holes 41b. The fluid flow hole 41a communicating with the third communication passage 4b is formed of a ring-shaped thin metal plate member. The first leaf valve 41 includes, for example, two large-diameter valve bodies 41c and 41d formed in a flat shape with an outer diameter substantially the same as the outer diameter of the sliding piston 4 (see FIGS. 2 and 3). And a medium-diameter valve body 41e formed in a flat shape having a smaller diameter than the large-diameter valve body 41c, and a small-diameter valve formed in a skirt shape (dish washer shape) having a smaller diameter and wider than the middle-diameter valve body 41e. The body 41f is overlapped.
As shown in FIGS. 2 and 3, the first leaf valve 41 is a small-diameter valve body having a spring property in a closing direction on an intermediate-diameter valve body 41 e superimposed on the large-diameter valve bodies 41 c and 41 d. 41f is overlapped, and is clamped and assembled in a state of being elastically deformed so as to be pressed flat against the valve seat surface 4d of the sliding piston 4 by the crimping portions 44a and 44b of the valve holding member 44. . For this reason, the 1st leaf valve 41 assembled | attached to the sliding piston 4 is equipped with the appropriate elastic force pressed to the side which obstruct | occludes the 1st communicating path 4a with the small diameter valve body 41f.

  Further, the first leaf valve 41 has an elasticity to automatically return to the closing direction by stacking a plurality of metal thin plate members in order to generate an appropriate elastic force (resistance force) in the liquid flow. (See FIG. 4B). The first leaf valve 41 is normally in a closed state in which the first communication passage 4a is closed by being pressed against the valve seat surface 4d of the sliding piston 4 by its elastic force. The first leaf valve 41 is provided with a fluid flow hole 41a that is arranged to communicate with the third communication passage 4b. The first leaf valve 41 and the second leaf valve 42, which will be described later, are configured so that the first leaf valve 41 is slidable by tightening the crimping portions 44a and 44b at both ends of the valve holding member 44 fitted on the shaft center side. 4 is fixed to the upper surface (valve seat surface 4 d), and the second leaf valve 42 is fixed to the lower surface of the sliding piston 4.

≪Second leaf valve structure≫
The second leaf valve 42 (valve) acts on the second leaf valve 42 by the pressure of the fluid from the side of the first working chamber 21 passing through the third communication passage 4b against the elastic force of the second leaf valve 42. When the working force increases, the valve is opened to allow the liquid in the first working chamber 21 to flow to the second working chamber 22 side through the third communication passage 4b. An opening end of the third communication passage 4b on the second working chamber 22 side is a valve seat of the second leaf valve 42.
In the second leaf valve 42, a metal thin plate member having a hole into which the valve holding member 44 is fitted is formed in the central portion, like the first leaf valve 41, an appropriate elastic force (resistance) In order to generate a force, a plurality of layers are assembled.
The second leaf valve 42 includes, for example, three medium-diameter valve bodies 42a, 42b, and 42c that are formed in a flat shape with an outer diameter large enough to close the open end of the third communication passage 4b. A small-diameter valve body 42d formed in a skirt shape (dish washer shape) having a smaller diameter and wider than the diameter valve bodies 42a, 42b, and 42c is overlapped.
In the second leaf valve 42, a small-diameter valve body 42d having a spring property is disposed under the medium-diameter valve bodies 42a, 42b, 42c so as to be closed, and caulking portions 44a, 44b of the valve holding member 44 are disposed. Thus, it is pressed and pressed against the lower surface of the sliding piston 4 so that it is elastically deformed so as to be flat. For this reason, the second leaf valve 42 assembled to the sliding piston 4 has an appropriate elastic force that automatically returns to the direction of closing the third communication passage 4b by the small-diameter valve body 42d. The valve is closed.

≪Configuration of sliding part≫
As shown in FIGS. 2 and 3, the sliding portion 43 is provided in the through hole 4 c of the sliding piston 4 to connect the sliding piston 4, the first leaf valve 41, and the second leaf valve 42 in the axial direction. And a slide bush 45 that functions as a valve body that slides on the outer peripheral surface 3e of the piston rod 3 to open and close the second communication passage 3f.

<Configuration of valve holding member>
The valve holding member 44 is a member for fixing the first leaf valve 41 and the second leaf valve 42 to the sliding piston 4 so as to be openable and closable with respect to the first communication passage 4a and the third communication passage 4b. The valve holding member 44 is made of a bobbin-shaped metal member having crimped portions 44a and 44b at both ends. The valve holding member 44 is fitted into the sliding piston 4, the first leaf valve 41, and the second leaf valve 42 from the radially inner side, and is bent at both ends outward and formed into a flange shape. The shaft portions of the first leaf valve 41 and the second leaf valve 42 are fixed to the sliding piston 4 by the fastening portions 44a and 44b. For this reason, the valve holding member 44 can be reduced in size by reducing the overall length of the sliding piston 4 in the axial direction.

The upper caulking portion 44a is curved when the first leaf valve 41 is opened by being pressed by the fluid and the communication hole 44c communicating with the third fluid passage 4b and the fluid flow hole 41a of the first leaf valve 41. As well as restricting the degree to which it is performed, a restricting portion 44d for adjusting the flow resistance of the liquid flowing in the first communication passage 4a and a spring receiving surface 44e for supporting the lower end of the urging means 51 are formed. ing.
The lower caulking portion 44b appropriately regulates the degree to which the second leaf valve 42 is bent when pressed by the fluid and opens the flow resistance of the liquid flowing in the third communication passage 4b. A regulating portion 44f for adjustment is formed. The restricting portion 44f is formed at the lower opening end of the third communication passage 4b so as to be separated by a slight gap.

<Configuration of slide bush>
The slide bush 45 is a cylindrical member that also functions as a sliding member having an inner peripheral surface that is fitted in the valve holding member 44 and slides in contact with the outer peripheral surface 3 e of the piston rod 3. The slide bush 45 is made of a material having a low sliding resistance such as a tetrafluoroethylene resin and a good sliding property. The slide bush 45 is interposed between the valve holding member 44 that moves integrally with the sliding piston 4 and the small-diameter portion 3c of the piston rod 3, so that the sliding resistance between them can be reduced. . When the slide bush 45 moves up and down with respect to the slide piston 4, the slide bush 45 also serves as a valve body that opens and closes by changing the openings of the openings 3g and 3h of the second communication passage 3f. The valve holding member 44 and the slide bush 45 may be formed from a single member.

<Configuration of piston ring>
The piston ring 46 is a substantially cylindrical member that is fixed to the outer peripheral surface of the sliding piston 4 and is in sliding contact with the inner peripheral surface of the cylinder 2. The piston ring 46 is a member for maintaining the airtightness and reducing the frictional resistance when the sliding piston 4 slides up and down in the cylinder 2 with the vibration of the vehicle.

≪Configuration of piston displacement adjustment means≫
As shown in FIGS. 2 and 3, the piston displacement amount adjusting means 5 is a device for continuously changing the damping force by adjusting the piston displacement amount of the sliding piston 4 according to the moving speed of the piston rod 3. It is. The piston displacement adjustment means 5 includes an urging means 51 described later, a sliding piston 4 having a first leaf valve 41, a first communication path 4a, the sliding portion 43, the second communication path 3f, a small diameter, and the like. A piston rod 3 having a portion 3c and the like, and is arranged between the first working chamber 21 and the second working chamber 22.
This piston displacement amount adjusting means 5 can adjust the communication state between the first working chamber 21 and the second working chamber 22 by the second communication passage 3 f according to the sliding state of the sliding piston 4. It has become. Further, the piston displacement amount adjusting means 5 is configured such that the sliding piston 4 slides against the urging force of the urging means 51 according to the moving speed of the piston rod 3, and the first working chamber of the second communication passage 3f. The area (opening) of the openings 3g, 3h facing the 21 or the second working chamber 22 can be adjusted.

<Configuration of biasing means>
2 and 3, the urging means 51 is an elastic member that presses the sliding piston 4 in the axial direction of the piston rod 3 in the direction opposite to the sliding direction, and is composed of, for example, a cylindrical coil spring. . The biasing means 51 is loosely fitted to the small diameter portion 3c of the piston rod 3 so that the upper end portion presses the spring seat 6 engaged with the stepped portion 3b of the piston rod 3 upward by a spring force. The lower end side is assembled in a state in which the upper caulking portion 44a of the valve holding member 44 is pressed downward. Since the biasing means 51 is interposed between the spring seat 6 on the upper side of the sliding piston 4 and the valve holding member 44, the biasing means 51 is compressed by the piston rod 3. The damping force when an input load in the direction is applied is variable.

<Configuration of spring seat>
The spring seat 6 is a spring receiver that supports the upper end portion of the biasing means 51, and is made of a substantially disk-shaped metal member that is externally fitted so as to contact the small diameter portion 3 c and the step portion 3 b of the piston rod 3. Become. The spring seat 6 is formed with a cylindrical portion 6a that is slidably fitted to the small diameter portion 3c and a flange portion 6b that contacts the step portion 3b and receives the upper end of the biasing means 51.

<Configuration of fastening member>
The fastening member 7 is a member for sandwiching the spring seat 6, the urging means 51, and the sliding piston 4 that are externally fitted to the small diameter portion 3c with the step portion 3b. The fastening member 7 also has a stopper function that suppresses the downward movement of the sliding piston 4 that performs the valve function of opening and closing the opening 3g of the second communication passage 3f. The fastening member 7 includes a nut that is screwed into the male thread portion 3d of the piston rod 3.

≪Operation of damping force variable damper≫
Next, the assembly and operation of the damping force variable damper according to the embodiment of the present invention will be described with reference mainly to FIGS.

  As shown in FIGS. 2 and 3, when the damping force variable damper 1 is assembled, the valve holding member 44 has a slide bush 45 fitted therein in advance and the upper caulking portion 44a is bent into a flange shape. Process it. The first leaf valve 41, the sliding piston 4 integrally formed with the piston ring 46, and the second leaf valve 42 are sequentially fitted into the valve holding member 44 from below, and the lower caulking portion 44b is caulked. Thereby, the first leaf valve 41 is fixed to the upper surface of the sliding piston 4 and the second leaf valve 42 is fixed to the lower surface.

  Next, the spring seat 6, the biasing means 51, and the sliding piston 4 are sequentially fitted from the lower side to the small diameter portion 3 c of the piston rod 3, and the female thread portion of the fastening member 7 is screwed to the male thread portion 3 d of the piston rod 3. To wear. Thereby, the assembly of the piston portion of the damping force variable damper 1 is completed.

Thus, the damping force variable damper 1 has a structure in which each component such as the sliding piston 4 is assembled to the piston rod 3 in the same axial direction and fastened with one fastening member 7. It can be easily assembled automatically by an automatic assembly machine.
The damping force variable damper 1 has only one sliding piston 4 as a piston for the damping force variable damper 1, so the number of parts and assembly man-hours are small, and the axial length of the sliding piston 4 is shortened. can do.
Further, since the first leaf valve 41 and the second leaf valve 42 are fixed by the caulking portions 44a and 44b of the valve holding member 44 formed by bending a metal plate member, the thickness of the sliding piston 4 is increased. The axial length can be shortened by reducing the thickness.

≪Operation of damping force variable damper≫
Next, the operation of the damping force variable damper 1 according to the embodiment of the present invention will be described with reference to FIGS.
5A and 5B are views showing the operation of the damping force variable damper according to the embodiment of the present invention. FIG. 5A is an enlarged cross-sectional view showing the main part when the input load of the piston rod is small, and FIG. 5B is the piston rod. It is a principal part expanded sectional view which shows a state when the input load of is large. FIG. 6 is a graph showing the relationship between damping force and piston speed and time in the damping force variable damper according to the embodiment of the present invention. FIG. 7 is a graph showing the relationship between damping force and time in the damping force variable damper according to the embodiment of the present invention.

≪Piston speed when piston rod input load is small≫
First, the state when the input load (displacement speed) in the downward direction of the piston rod 3 of the damping force variable damper 1 is small will be described with reference to FIGS.
As shown in FIG. 5A, when the downward input load of the piston rod 3 is small, the piston rod 3 has a small pressing force to compress the biasing means 51 with the spring seat 6 interposed therebetween. The biasing means 51 is compressed and does not reach the valve opening point at which the opening 3g of the second communication passage 3f of the piston displacement amount adjusting means 5 is opened.
For this reason, the pressing force (reaction force) by which the fluid in the second working chamber 22 presses the sliding piston 4 upward is also small, and the sliding piston 4 remains stopped with respect to the piston rod 3. In addition, the opening 3g on the first working chamber 21 side of the second communication passage 3f is closed.

  For this reason, the sliding piston 4 is slightly lowered together with the piston rod 3 to press the fluid on the second working chamber 22 side. The fluid on the second working chamber 22 side has a small reaction force with the amount of movement of the sliding piston 4 and is pressed with a weak pressing force upward to open the first leaf valve 41. The first leaf valve 41 is pressed by the reaction force of the fluid in the second working chamber 22 to open. When the first leaf valve 41 is opened, the fluid on the second working chamber 22 side moves upward in the first leaf valve 41 against the elastic force in the valve closing direction of the first leaf valve 41 itself. To the first working chamber 21 side.

  As a result, the damping force variable damper 1 has a small damping according to the input load of the piston rod 3 due to the flow path resistance when the fluid passes through the first leaf valve 41 as shown in the damping force characteristic curve A1 of FIG. Force is generated. In this case, the opening area (opening) of the valve seat portion of the first leaf valve 41 is restricted by the restricting portion 44f, and the flow rate of the fluid flowing therethrough is small. For this reason, since it takes time for the fluid on the second working chamber 22 side below the sliding piston 4 to flow and move to the first working chamber 21 side on the upper side, the piston speed of the sliding piston 4 is As shown in the piston speed characteristic curve B1 of FIG. 6, it is slowed by the flow resistance of the fluid.

≪Piston speed when piston rod input load is large≫
Next, referring to FIGS. 5B and 6, the input load (displacement speed) of the piston rod 3 of the damping force variable damper 1 is large, and the opening of the second communication path 3 f of the piston displacement amount adjusting means 5. The state when the valve opening point at which 3g opens will be described.
As shown in FIG. 5B, when the input load in the downward direction of the piston rod 3 is large (the moving speed is fast), the biasing means 51 is moved by moving the piston rod 3 and the spring seat 6 downward. As a result, the sliding piston 4 is pressed downward, and the pressure (reaction force) by which the fluid in the second working chamber 22 presses the sliding piston 4 upward increases. For this reason, when the reaction force by which the fluid in the second working chamber 22 presses the sliding piston 4 upward increases and overcomes the spring force of the urging means 51, the urging means 51 is compressed and the sliding piston is compressed. 4 rises with respect to the piston rod 3.

  Thus, the biasing means 51 of the piston displacement amount adjusting means 5 is compressed according to the sliding amount of the sliding piston 4 facing the piston rod 3, and the biasing force continuously changes (attenuation in FIG. 6). Force characteristic curves A1, A2). For this reason, the feeling of hardness at the time of a damping force characteristic change is suppressed, and riding comfort can be improved.

At this time, the first leaf valve 41 is pushed and bent by the fluid flowing through the first communication passage 4a, and the above-described valve open state is maintained. The upward pressing force (reaction force) of the fluid in the second working chamber 22 raises the sliding piston 4 relative to the piston rod 3 against the biasing means 51.
Then, the sliding piston 4 is separated from the fastening member 7, and the slide bush 45 that has closed the lower opening 3g of the second communication passage 3f opens the opening 3g to open the valve. The fluid in the second working chamber 22 is caused to flow toward the first working chamber 21 through the second communication passage 3f.
Further, as the sliding piston 4 slides with respect to the piston rod 3, the piston speed of the sliding piston 4 becomes slower than the moving speed of the piston rod 3 by the amount of sliding.

That is, when the sliding piston 4 slides upward due to the reaction force of the fluid, the fluid on the second working chamber 22 side flows to the first working chamber 21 side through the second communication path 3f. The valve flow rate of the fluid flowing upward in the first communication passage 4a of the sliding piston 4 instantaneously decreases. Along with this, the piston speed becomes slower than the moving speed of the piston rod 3.
For this reason, as shown in FIG. 6, the rising of the damping force changes gently so that the damping force characteristic curve A3 draws a gentle curve, so that the riding comfort can be improved.

  When the vehicle gets over a large unevenness on the road surface, a large input load exceeding a predetermined value (valve opening point for compressing the biasing means 51 to open the opening 3g) enters and the sliding piston 4 slides. In such a case, the flow rate of the fluid passing through the first communication path 4a can be instantaneously reduced by causing the fluid to flow through the second communication path 3f. For this reason, the sliding speed of the sliding piston 4 can be slowed with respect to the piston rod 3, and the rising of the damping force can be made smooth. As a result, it is possible to improve the ride comfort by reducing the piston speed and the damping force from rapidly increasing when the user gets over the unevenness while traveling on an undeveloped road having a large unevenness on the road surface.

  In this way, the damping force variable damper 1 opens the second communication path 3f according to the sliding state of the sliding piston 4 when a large input load is applied when the vehicle gets over a large unevenness on the road surface. By providing the piston displacement amount adjusting means 5 that adjusts the communication state between the first working chamber 21 and the second working chamber 22, the rising inclination can be reduced. For this reason, as shown in FIG. 7, the damping force characteristic curve C is a damping without a stepped feeling that draws a gentle curve as compared with the damping force characteristic curve D of the conventional damper as shown in Patent Document 1. It can be changed to force, and a step feeling can be reduced.

Further, the damping force variable damper 1 includes the urging means 51 that urges the sliding piston 4 in the axial direction to restrict the movement of the sliding piston 4, so that the amount of expansion and contraction of the urging means 51 is increased. The positional relationship between the sliding piston 4 and the piston rod 3 and the positional relationship between the sliding piston 4 and the opening 3g are determined. For this reason, by adjusting the area (opening) of the opening 3g facing the second working chamber 22 of the second communication passage 3f, the flow rate of fluid flowing through the opening 3g according to the degree of opening of the opening 3g, The flow resistance and piston displacement can be adjusted.
As a result, the displacement of the damping force of the damping force variable damper 1 can be made smooth to suppress a feeling of rigidity and to make the ride comfortable.

  As described above, the operation of the damping force variable damper 1 has been described by taking the compressed state of the piston rod 3 as an example. However, when the piston rod 3 is in the pulled state, the second leaf valve 42 is operated to adjust the damping force.

[Modification]
The present invention is not limited to the above-described embodiment, and various modifications and changes can be made within the scope of the technical idea. The present invention extends to these modifications and changes. Of course.
FIG. 8 is an operation diagram showing a modified example of the damping force variable damper according to the embodiment of the present invention, wherein (a) is an enlarged cross-sectional view of a main part showing a state when the input load of the piston rod is small, (b). These are the principal part expanded sectional views which show a state when the input load of a piston rod is large.

In the embodiment, as shown in FIGS. 2 and 3, as an example of the second communication passage 3 f formed in the piston rod 3, the groove-shaped second formed on the outer peripheral surface 3 e of the small diameter portion 3 c of the piston rod 3. Although it has been described that the communication path 3f is provided, the present invention is not limited to this.
As shown in FIGS. 8A and 8B, for example, the second communication passage 3i is formed in the piston rod 3 to have an E-shaped cross section, and has a lower horizontal hole-shaped opening 3j and an upper horizontal hole shape. The opening 3k may be communicated with a vertical hole-shaped communication hole 3m. That is, the second communication path 3i only needs to have the lower opening 3j and the upper opening 3k, and may be formed so as to pass through the inside of the piston rod 3.
In this case, as shown in FIG. 8A, the lower opening 3j is closed by the slide bush 45 of the sliding portion 43 of the sliding piston 4 during normal times and when the input load of the piston rod 3 is small. Then, as shown in FIG. 7B, when the input load of the piston rod 3 is large, it may be released.

  Moreover, the 1st leaf valve 41 and the 2nd leaf valve 42 should just have the appropriate elasticity which presses and closes the 1st communicating path 4a and the 2nd communicating path 4b with an appropriate pressing force, The shape The material and the like are not particularly limited.

DESCRIPTION OF SYMBOLS 1 Damping force variable damper 2 Cylinder 3 Piston rod 3e Outer peripheral surface 3f, 3i 2nd communicating path 3g, 3h, 3j, 3k Opening part 4 Sliding piston 4a 1st communicating path 4b 3rd communicating path 5 Piston displacement amount adjustment means 21 First working chamber 22 Second working chamber 41 First leaf valve (valve)
42 Second leaf valve (valve)
43 Sliding part 44 Valve holding member (sliding part)
45 Slide bush (sliding part)
51 Energizing means

Claims (4)

A damping force variable damper that is used in a vehicle suspension system and makes the damping force variable,
A cylinder filled with fluid,
A piston rod provided to penetrate one end of the cylinder;
A sliding piston provided inside the cylinder so as to be relatively movable with respect to the piston rod, and partitioning the inside of the cylinder into a first working chamber and a second working chamber;
A first communication passage formed in the sliding piston and communicating between the first working chamber and the second working chamber;
A valve for opening and closing the first communication path;
Piston displacement amount adjusting means for adjusting the piston displacement amount of the sliding piston according to the moving speed of the piston rod;
A damping force variable damper comprising: The piston rod has a second communication passage that communicates between the first working chamber and the second working chamber arranged on the radially inner side of the sliding piston,
The piston displacement amount adjusting means adjusts a communication state between the first working chamber and the second working chamber by the second communication path according to a sliding state of the sliding piston. The damping force variable damper according to claim 1. The piston displacement adjustment means is
An urging means supported by the sliding piston or the piston rod and urging the sliding piston in an axial direction;
The sliding piston slides against the urging force of the urging means according to the moving speed of the piston rod, and faces the first working chamber or the second working chamber of the second communication path. The damping force variable damper according to claim 2, wherein an area of the opening is adjusted. The sliding piston and the valve are clamped in the axial direction, the sliding piston and the valve are fitted from the inside in the radial direction, and a sliding portion that slides on the outer peripheral surface of the piston rod to open and close the second communication path is provided. The damping force variable damper according to any one of claims 1 to 3, wherein the damper is variable.

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