JP2011153661A - Damping force adjusting device of shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a damping force adjusting device of a shock absorber capable of securing good riding comfort of a vehicle and securing sure steering stability. <P>SOLUTION: This damping force adjusting device includes a valve member 61 moving according to a pressure difference on front and rear sides of a fixed throttle valve 50 between the fixed throttle valve 50 and a variable throttle valve 40 in a cylinder body 10, and a relief valve 60 constituted so that flow rate of working fluid may be rapidly increased according to an increase of a moving distance of the valve member 61. In the damping force adjusting device, a first flow passage P1 is formed to communicate with both sides of a piston 20 via the fixed throttle valve 50 and the variable throttle valve 40, and a second flow passage P2 is formed to communicate with both the sides of the piston 20 via the fixed throttle valve 50 and the relief valve 60. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a shock absorber damping force adjusting device, and more particularly to a damping force adjusting device for adjusting a damping force of a shock absorber mounted on a vehicle.

  In a general configuration of a shock absorber mounted on a vehicle, a piston is accommodated in a cylinder and a valve for damping force adjustment is provided. This valve can adjust the damping force generated by the piston because the damping force is determined uniquely with respect to the operating speed of the piston. Various types are known. For example, the following Patent Document 1 aims to “maintain an adjustment cost for controlling a valve with a variable damping force at an acceptable level” (paragraph [0004] of Patent Document 1). The cylinder is filled with a piston rod with a piston in the cylinder that is configured to be movable in the axial direction, and the piston is a damping damper that divides the cylinder into two working chambers and is pressure dependent. A vibration damper in which the damping force of the damping valve can be changed against the elastic force to the shut-off valve body by an actuator. In addition, an inflow valve having an inherent damping action is additionally provided, whereby the action of the variable damping valve is operatively overlapped with the inflow valve. It is described as determined by the "(same paragraph [0005]).

JP-A-10-61706

  In the device described in Patent Document 1, since the inflow valve having an inherent damping action is additionally arranged in the lateral direction with respect to the cylinder, particularly when mounted coaxially with the suspension coil spring. It is necessary to arrange so as not to interfere with the suspension coil spring, and a large mounting space is required.

  Further, in the apparatus described in Patent Document 1, the relief opening area for the working fluid (oil) is set to a linear correlation with the front-rear differential pressure. ) Increases the damping force. Therefore, when vibration with low frequency is suppressed, that is, when the number of steps with high damping force is selected, when the frequency of protrusions, steps, etc. is high, that is, when the input with a high piston speed is suddenly applied Causes a high damping force, resulting in poor ride comfort.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a shock absorber damping force adjusting device capable of ensuring a good riding comfort of a vehicle and ensuring reliable steering stability in a shock absorber damping force adjusting device. To do.

  In order to achieve the above object, the present invention comprises a cylinder body that contains a working fluid, a piston that slides within the cylinder body, and a piston rod that is connected to the piston, and is disposed within the cylinder body. In the damping force adjusting device of the shock absorber configured so that the working fluid on both sides of the piston communicates through the throttle valve and the variable throttle valve, between the fixed throttle valve and the variable throttle valve in the cylinder, A relief valve configured to have a valve member that moves in accordance with a pressure difference before and after the fixed throttle valve, and configured to rapidly increase a flow rate of the working fluid in accordance with an increase in a moving distance of the valve member; A first flow path that communicates both sides of the piston via the throttle valve and the variable throttle valve, and a second flow path that communicates both sides of the piston via the fixed throttle valve and the relief valve Form It is obtained by and.

  The relief valve includes a return spring that urges the valve member in the valve closing direction, and the valve member moves according to a pressure difference between the front and rear of the fixed throttle valve against the urging force of the return spring. And an irregularly shaped opening that increases the communication area of the valve member to the second flow path at an increasing rate exceeding a proportional relationship with respect to the moving distance of the valve member. The flow rate of the working fluid flowing in the two flow paths may be adjusted.

  The irregularly shaped opening may be, for example, a trapezoidal shape in front view, a front view shape having a contour portion of a multi-curve curve, or a portion in which the opening area increases in proportion to the axial movement distance from the initial position of the valve member. And it can be set as the shape of a front view which has a part where an opening area increases rapidly after that.

  The fixed throttle valve is disposed in a flow path formed in the piston and constituting a part of the first flow path, and the variable throttle valve is formed in the piston rod and the first throttle valve. It is good to arrange | position to the flow path which comprises a part of flow path. The relief valve can be formed integrally with the fixed throttle valve.

  Since this invention is comprised as mentioned above, there exist the following effects. In other words, in the damping device for adjusting the damping force of the shock absorber, the relief valve moves the valve member according to the pressure difference before and after the fixed throttle valve, and the flow rate of the working fluid is increased according to the increase of the moving distance. Since it increases rapidly, a stable damping force can be maintained without being affected by changes in the piston speed. For example, even when an input with a large change in piston speed is suddenly applied, the flow rate of the working fluid increases rapidly as the moving distance of the valve member increases, and the change in the damping force with respect to the piston speed can be reduced. Therefore, it is possible to ensure a good riding comfort and to ensure reliable steering stability.

  In addition, a fixed throttle valve, a variable throttle valve and a relief valve are housed in the cylinder of the shock absorber, and these have all the valve functions necessary for adjusting the damping force, so that it can be configured in a small size. Compared to the structure that is mounted laterally with respect to such a cylindrical body, particularly when the suspension coil spring and the shock absorber are arranged coaxially, it is possible to ensure good mountability. Furthermore, since the relief valve can be formed integrally with the fixed throttle valve, further miniaturization becomes possible.

It is sectional drawing which shows the structure of the damping-force adjustment apparatus which concerns on one Embodiment of this invention. It is a circuit diagram which shows the relationship between the variable throttle valve, fixed throttle valve, and relief valve which comprise the damping-force adjustment apparatus which concerns on one Embodiment of this invention. It is sectional drawing of the shock absorber containing the damping-force adjustment apparatus which concerns on one Embodiment of this invention. It is a front view which shows the relief valve part in the damping force adjustment apparatus which concerns on one Embodiment of this invention. It is a front view which shows the other example of the opening for relief valves in one Embodiment of this invention. It is a front view which shows the further another example of the opening for relief valves in one Embodiment of this invention. It is a perspective view which shows the front-end | tip part of the piston rod in one Embodiment of this invention. It is a perspective view which shows the valve member with which the control rod in one Embodiment of this invention and its front-end | tip part were mounted | worn. It is a principal sectional view showing the structure of the damping force adjusting device according to one embodiment of the present invention. It is sectional drawing of the AA line cross section in FIG. It is sectional drawing of the BB line cross section in FIG. It is sectional drawing of the CC line cross section in FIG. It is a graph which shows the adjustment example of the damping force by the damping force adjustment apparatus which concerns on one Embodiment of this invention compared with the adjustment example of the damping force by the damping force adjustment apparatus of a prior art. It is a graph which shows the damping force characteristic in the stroke where the flow direction of a working fluid is reverse regarding the example of damping force adjustment by the damping force adjustment apparatus which concerns on one Embodiment of this invention. It is sectional drawing which shows the structure of the damping-force adjustment apparatus which concerns on other embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 3 shows an overall configuration of a shock absorber according to an embodiment of the present invention, and FIG. 1 shows a portion constituting the damping force adjusting device. In the shock absorber 1 of this embodiment, as shown in FIG. 3, a cylinder 10 that contains a working fluid is composed of an inner cylinder 11 and an outer cylinder 12, and an annular chamber CC is formed therebetween. A piston 20 is slidably accommodated in the inner cylinder 11, and the inner cylinder 11 is separated into an upper chamber UC and a lower chamber LC via the piston 20. A flow path P0 communicating with the upper chamber UC is formed in the piston 20, and the working fluid in the upper chamber UC and the lower chamber LC on both sides of the piston 20 is the variable throttle valve 40 and the fixed throttle valve 50 shown in FIG. The flow rate is adjusted via the relief valve 60 and the leaf valves 71 and 72. The piston 20 is attached to the tip of a cylindrical piston rod 30, and a control rod 41 constituting a part of the variable throttle valve 40 is accommodated in the piston rod 30, and a motor M (see FIG. 3) and is supported rotatably about the shaft.

  As shown in FIG. 1, a spacer 81, a leaf valve 71, a piston 20, a valve body 21 and 22, a leaf valve 72 and a spacer 82 are supported at the tip of the piston rod 30, and these are fixed by a nut 83. Yes. The valve bodies 21 and 22 are positioned by pins 26. A valve hole 31 that opens at the tip and an opening 32 that communicates with the valve hole 31 are formed inside the tip of the piston rod 30. The valve bodies 21 and 22 are formed with a bottomed cylindrical valve hole 23 in parallel with the valve hole 31 of the piston rod 30. The upper part of the valve hole 23 opens and communicates with the flow path P 0 in the piston 20. Openings 24 and 25 are formed on the outer and inner surfaces of the valve body 21, respectively. Thereby, the valve hole 23 communicates with the lower chamber LC through the opening 24, communicates with the opening 32 of the piston rod 30 through the opening 25, and further communicates with the valve hole 31 through the variable throttle valve 40. It is configured as follows. A valve member 42 having a bottomed cylindrical shape is accommodated in the valve hole 31 of the piston rod 30, and a control rod 41 is fixed to the bottom portion of the valve rod 42. An irregularly shaped opening 43 is formed on the side surface of the valve member 42. It is formed at a position that can face the opening 32. Thus, the variable throttle valve 40 of the rotary valve mechanism is constituted by the opening 32 of the piston rod 30 shown in FIG. 7 and the valve member 42 of the control rod 41 shown in FIG.

  On the other hand, a fixed throttle valve 50 is provided in the upper opening of the valve hole 23 of the valve body 21. That is, a valve member 61 having a bottomed cylindrical shape constituting a relief valve 60 described later is accommodated in the valve hole 23, and an orifice (fixed throttle) is formed by an opening 62 formed in the bottom thereof. 60 is configured to function also as the fixed throttle valve 50.

  Further, a return spring 63 is accommodated in the valve hole 23 on the lower side of the valve member 61. With the return spring 63, an annular valve stopper 64 provided in the upper opening portion of the valve hole 23 is accommodated. The valve member 61 is urged in the direction in which the valve member 61 is pressed (valve closing direction). And the opening 24 formed in the side surface of the valve body 21 is increased by the valve member 61 at an increasing rate in which the opening area exceeds a proportional relationship with respect to the movement distance of the valve member 61 in the axial direction (vertical direction in FIG. 1). For example, as shown in FIG. 4, the opening 24 is formed in a trapezoidal shape when viewed from the front. Thus, the relief valve 60 of the present embodiment is configured by the opening 24, the valve member 61, and the return spring 63, and the flow rate of the working fluid flowing through the second flow path P2 is adjusted through the opening 24.

  The shape of the opening 24 of the valve body 21 is not limited to the trapezoidal shape shown in FIG. 4, but may be an opening 24a having a contoured shape of a double curve as shown in FIG. As shown in FIG. 6, the opening 24b having a front view shape having a portion in which the opening area increases in proportion to the axial movement distance from the initial position of the valve member 61 and a portion in which the opening area increases rapidly thereafter. Good.

  The variable throttle valve 40, the fixed throttle valve 50, and the relief valve 60 are in the relationship shown in FIG. 2, and as shown in FIGS. 1 and 2, both sides of the piston 20 via the fixed throttle valve 50 and the variable throttle valve 40 ( The first flow path P1 that communicates with the upper chamber UC and the lower chamber LC), and the second flow that communicates with both sides (the upper chamber UC and the lower chamber LC) of the piston 20 via the fixed throttle valve 50 and the relief valve 60. A path P2 is formed. Here, the opening degree of the relief valve 60 (opening area of the opening 24) is determined by the pressure difference before and after the fixed throttle valve 50 and the load (biasing force) of the return spring 63, and the pressure difference before and after the fixed throttle valve 50 is The flow rate of the working fluid passing through the fixed throttle valve 50 depends on the moving area of the piston 20, the opening degree of the variable throttle valve 40 and the relief valve 60 (determined by the opening area of the opening 62 and the flow rate of the working fluid passing therethrough. Open area).

  In order to make it easier to understand the structure of the damping force adjusting device according to the above embodiment, FIG. 9 shows a main cross-sectional view, FIG. 10 shows a cross section taken along line AA in FIG. FIG. 12 shows a cross section taken along the line CC in FIG. As is clear from these drawings, the flow path formed in the piston 20 is fixed between the flow path in which the upper chamber UC and the lower chamber LC on both sides of the piston 20 communicate with each other via the leaf valve 72. There is a flow path (P0) communicating with the throttle valve 50 and the relief valve 60. In FIG. 1, the former is indicated by a solid line and the latter is indicated by a broken line.

  With respect to an example of adjusting the damping force by the shock absorber damping force adjusting device having the above configuration, referring to FIG. 13 showing the damping force characteristic of the ascending stroke of the piston 20 on the rebound side, according to the prior art (for example, Patent Document 1). This will be described in comparison with an example of adjusting the damping force. First, since the relief opening area in the prior art changes with a linear function with respect to the stroke (movement distance) of the piston, the opening area of the flow path becomes insufficient due to a sudden change in the piston speed, and pressure loss appears in the damping force. As shown by a broken line in FIG. 13, the damping force changes suddenly. For this reason, for example, when there is a projection input during traveling, the piston speed (horizontal axis in FIG. 13) increases rapidly. At this time, the damping force (vertical axis in FIG. 13) also increases and the characteristics as a shock absorber are obtained. Since it becomes hard, the input is easily transmitted to the upper side of the spring (the vehicle body side), and the occupant feels the rigidity as a ride comfort.

  On the other hand, according to the relief valve 60 of this embodiment, the rate of increase in which the communication area with respect to the second flow path P2 exceeds the proportional relationship with respect to the axial movement distance of the valve member 61 (in this embodiment, a quadratic function). ), The pressure loss at the relief valve 60 can be reduced. As shown by the solid line in FIG. 13, the sudden change in the damping force accompanying the change in the moving speed of the piston 20 can be reduced. And a stable damping force can be maintained. For example, when the vehicle is in a traveling state in which vibration with low frequency is suppressed, that is, when the number of steps having a high damping force is selected, an input having a high frequency is suddenly added by a protrusion or the like, and the speed of the piston 20 rapidly increases. Even in this case, according to the present embodiment, since the damping force does not change suddenly, it is possible to appropriately solve the problem of deterioration in riding comfort due to the sudden increase in vibration transmission to the upper side of the spring. In FIG. 13, the upper solid line and the broken line FO indicate the characteristics when the variable throttle valve 40 is fully opened, and the lower solid line and the broken line FC indicate the characteristics when the variable throttle valve 40 is fully closed.

  Further, according to the present embodiment, as shown in FIG. 14, the flow direction of the working fluid corresponds to the opening area of the variable throttle valve 40 even in the reverse stroke of FIG. 1, that is, in the downward stroke of the piston 20. A variable range of damping force can be obtained. In FIG. 14, the upper solid line FC indicates the characteristic when the variable throttle valve 40 is fully closed, and the lower solid line FO indicates the characteristic when the variable throttle valve 40 is fully open.

  According to the above embodiment, the fixed throttle valve 50 is formed integrally with the relief valve 60, and the relief valve 60 is also configured to function as the fixed throttle valve 50. However, these are configured separately. One example is shown in FIG. In this embodiment, in FIG. 15, parts that are not directly related to the above-described embodiment are indicated by two-dot chain lines, and parts having substantially the same functions as the constituent parts shown in FIG. The same reference numerals are given and description thereof is omitted.

DESCRIPTION OF SYMBOLS 1 Shock absorber 10 Cylindrical body 20 Piston 21 and 22 Valve body 30 Piston rod 40 Variable throttle valve 41 Control rod 42 Valve member 50 Fixed throttle valve 60 Relief valve 61 Valve member 63 Return spring 71, 72 Leaf valve 81, 82 Spacer

Claims (4)

  A cylinder body that contains the working fluid, a piston that slides within the cylinder body, and a piston rod that is connected to the piston, and the piston of the piston via a fixed throttle valve and a variable throttle valve disposed in the cylinder body In the shock absorber damping force adjusting device configured so that the working fluids on both sides communicate with each other, according to a pressure difference between the fixed throttle valve and the variable throttle valve between the fixed throttle valve in the cylindrical body. A relief valve having a moving valve member and configured to rapidly increase the flow rate of the working fluid in accordance with an increase in a moving distance of the valve member; and the piston via the fixed throttle valve and the variable throttle valve And a second flow path that communicates with both sides of the piston via the fixed throttle valve and the relief valve. Saw Of the damping force adjusting device.   The relief valve includes a return spring that urges the valve member in the valve closing direction, and the valve member moves according to a pressure difference between the front and rear of the fixed throttle valve against the urging force of the return spring. And an irregularly shaped opening that increases the communication area of the valve member to the second flow path at an increasing rate exceeding a proportional relationship with respect to the moving distance of the valve member. 2. The shock absorber damping force adjusting device according to claim 1, wherein the flow rate of the working fluid flowing through the two flow paths is adjusted.   The fixed throttle valve is disposed in a flow path formed in the piston and constituting a part of the first flow path, and the variable throttle valve is formed in the piston rod and the first flow path. The damping force adjusting device for a shock absorber according to claim 1 or 2, wherein the damping force adjusting device is disposed in a flow path constituting a part of the shock absorber.   4. The shock absorber damping force adjusting device according to claim 3, wherein the relief valve is formed integrally with the fixed throttle valve.

Images