JPH053678U - Variable damping force buffer - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a damping force variable type shock absorber capable of sufficiently reducing the damping force in the soft range in the medium / high piston speed range. A valve body 2 provided by defining a chamber filled with a fluid into two chambers, and a damping force generation that generates a damping force by limiting the flow of the fluid between the defined two chambers. Means 9, a bypass H that bypasses the damping force generating means 9 and connects the two chambers, and a hollow portion 12a that is displaceably provided in the middle of the bypass H and constitutes a part of the bypass H. A damping force variable shock absorber, comprising: an adjuster 12 that is formed in a tubular shape having and that forms a variable throttle portion N that changes the flow passage cross-sectional area of the bypass passage H based on displacement. An axial slit 12d that forms a part of the bypass passage H together with the hollow portion 12a is formed on the peripheral wall of the groove 12.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a shock absorber that is suitable for use in a vehicle suspension and that can change damping force characteristics.

[0002]

[Prior Art]

 As a conventional damping force type shock absorber, for example, one disclosed in Japanese Utility Model Laid-Open No. 60-2035 is known.

This conventional damping force variable type shock absorber has a piston, which is slidably defined in two chambers in a cylinder filled with a fluid, and a fluid between the two chambers, which are defined. A damping valve that generates a damping force by limiting the flow of flow and a midway of a bypass path that bypasses the damping valve and connects the two chambers, and forms a part of the bypass path. And a regulator having a variable throttle portion that changes the flow passage cross-sectional area of the bypass passage by rotation of the variable throttle portion. The flow passage cross-sectional area of the bypass passage is changed by opening and closing the section, and thereby the damping force range is changed to the hard range (high damping force characteristic) and the soft range (low damping force characteristic). It was

[0004]

[Problems to be solved by the device]

 However, in such a conventional variable damping force type shock absorber, as described above, the maximum flow passage cross-sectional area of the bypass passage is limited by the inner diameter of the hollow portion of the adjuster, and therefore, in particular, per unit time. In the medium and high piston velocity range where the fluid flow rate of the vehicle increases, the damping force in the soft range cannot be sufficiently reduced, and thus there is a problem that the riding comfort of the vehicle is deteriorated.

The present invention has been made by paying attention to the conventional problems as described above, and the damping force variable type shock absorber capable of sufficiently reducing the damping force in the soft range in the medium and high piston speed ranges. The purpose is to provide a vessel.

[0006]

[Means for Solving the Problems]

 In the present invention, the above-mentioned object is achieved by forming an axial slit that forms a part of the bypass passage together with the hollow portion on the peripheral wall of the tubular adjuster.

That is, in the damping force variable shock absorber of the present invention, the fluid filled chamber is divided into two chambers, and the fluid flow between the two chambers is defined. Damping force generating means for generating a damping force by limiting, a bypass path that bypasses the damping force generating means and connects the two chambers, and a displaceable part in the middle of the bypass path. A damping force changeable shock absorber, which is formed in a tubular shape having a hollow portion that forms a variable throttle portion that changes a flow passage cross-sectional area of a bypass passage based on displacement, and an adjuster. A means in which an axial slit that forms a part of the bypass passage together with the hollow portion is formed on the peripheral wall of the adjuster.

[0008]

[Action]

 In the damping force variable type shock absorber of the present invention, when the throttle opening of the variable throttle portion is closed by the movement of the adjuster, the damping force of the hard range (high damping force characteristic) is generated by the damping force generating means and the throttle opening is performed. When the degree is opened, the bypass passage can be distributed and a soft range (reduced damping force) damping force is generated.

Further, in the case of the soft range, since the flow passage cross-sectional area of the bypass passage in the adjuster is determined by the total cross-sectional area of the hollow portion and the slit, only the cross-sectional integral of the slit per unit time in the bypass passage. The amount of fluid that can be flowed through is increased, and as a result, a sufficiently low damping force can be obtained even in the medium / high piston speed range.

[0010]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the configuration of the embodiment will be described. In describing the embodiments, an example in which the present idea is applied to both the expansion side and the compression side will be described.

FIG. 1 is a cross-sectional view showing a main part of a damping force variable type shock absorber according to an embodiment of the present invention, in which 1 denotes a cylindrical cylinder. This cylinder 1 is divided into an upper chamber A and a lower chamber B by a piston (valve body) 2 which is slidably mounted, and both chambers A and B are filled with fluid such as oil.

The piston 2 is attached to the tip small diameter portion 3a of the piston rod 3, that is, the retainer 4, washer 5a, check valve 6, check body 7, washer 5b are attached to the tip small diameter portion 3a. A compression side damping valve (damping force generating means) 8, a piston 2, an extension side damping valve (damping force generating means) 9, a washer 5c, and a retainer 10 are sequentially mounted, and finally a nut 11 is used for fastening.

In addition, the piston rod 3 has a through hole 3f formed in the shaft core portion thereof, and the first port 3b and the second port are sequentially arranged from the top in a state of penetrating the peripheral wall thereof in the diameter direction. A port 3c, a third port 3d and a fourth port 3e are provided. Each of the ports 3b, 3c, 3d, 3e is formed in twos facing each other in the diameter direction. The first port 3b, the second port 3c, and the fourth port 3e are formed so as to overlap each other in the vertical direction, and the third port 3d is close to 90 ° in the circumferential direction with the other ports 3b, 3c, 3e. It is formed at a position where the phases are shifted (see FIGS. 2, 3, 4, and 5).

The check body 7 is formed with an annular groove 7b which is opened and closed by the check valve 6, and the annular groove 7b communicates with the first port 3b.

Further, the upper end surface of the piston 2 on the upper chamber A side is provided with four pressure side annular grooves 2b which are communicated with the lower chamber B through the pressure side communication holes 2e and which are opened and closed by the pressure side damping valve 8. A pressure side communication groove 2c extending from the inner circumference to the outer circumference of the piston 2 is formed (see FIG. 2), and an inner circumference annular groove 2d is formed in the upper portion of the inner circumference of the piston 2.

On the other hand, on the lower end surface of the piston 2 on the lower chamber B side, four extension-side inner grooves 2f communicated with the upper chamber A via the extension-side communication holes 2k, and the extension-side inner grooves 2f. An extension side outer groove 2g formed on the outer side and communicating with the inner circumference of the piston 2 is formed, and an inner peripheral annular groove 2n is formed on the lower inner circumference of the piston 2. The expansion side damping valve 9 is formed by stacking a small-diameter valve 9b under a large-diameter valve 9a, and the large-diameter valve 9a is formed so as to open with the outer periphery of the small-diameter valve 9b as a fulcrum. The valve 9b is formed so as to open together with the large-diameter valve 9a by using the outer periphery of the washer 5c as a fulcrum, that is, the expansion side damping valve 9 has a rigidity that opens and closes the expansion side outer groove 2g. The rigidity is set lower than the rigidity of the portion that opens and closes the extension side inner groove 2f.

Further, in the through hole 3 f of the piston rod 3, an adjuster 12 is rotatably provided while being sandwiched between an annular upper bush 13 and a lower bush 14. The adjuster 12 is formed in a cylindrical shape having an inner hollow portion 12a whose lower end communicates with the lower chamber B at the axial center portion thereof, and the peripheral wall thereof has the first port 3b and the hollow portion. A lateral hole 12b communicating with 12a, a vertical groove 12c communicating with the second port 3c and the fourth port 3e, and a slit 12d communicating with the third port 3d and the hollow portion 12a are formed. That is, the pressure side variable throttle portion L is formed by the first port 3b and the lateral hole 12b, the extension side variable throttle portion M is formed by the second port 3c, the vertical groove 12c, and the fourth port 3e, and the third port 3d. A variable expansion diaphragm portion (variable diaphragm portion) N is formed by the slit 12d.

The slit 12d is formed to be longer than the lower end of the vertical groove 12c, and the lower end large diameter portion 12e is formed at the lower end of the hollow portion 12a so as to partially overlap the lower end of the slit 12d. There is. The central hole 14a of the lower bush 14 and the central hole 16a of the thrust washer 16 interposed between the lower bush 14 and the adjuster 12 have the same large diameter as the lower large diameter portion 12e. Has been formed. That is, the flow passage cross-sectional area in the adjuster 12 including the hollow portion 12a is expanded by the total cross-sectional integral of the two slits 12d and 12d, and this expanded flow passage cross-sectional area is increased by the lower end large diameter portion 12e and the thrust. It is maintained up to the lower chamber B by the enlarged cross-sectional area of the central hole 16a of the washer 16 and the central hole 14a of the lower bush 14.

The rotation of the adjuster 12 is performed by the control rod 15, which extends through the through hole 3f of the piston rod 3 to the upper end. It is adapted to be rotated by an actuator provided on the vehicle body mounting portion of the outer piston rod 3.

Therefore, based on the rotation of the adjuster 12, as shown in FIGS. 4 (a) and 5 (a), the expansion side variable throttle section M, the compression side variable throttle section L, and the expansion pressure variable throttle section L are adjusted. A high damping position in which the throttle portion N is fully closed, and, as shown in FIGS. 4B and 5B, the expansion side variable throttle portion M and the compression side variable throttle portion L are opened, and the expansion pressure variable throttle portion N is opened. As shown in Fig. 4 (c) and Fig. 5 (c), the middle damping position with the valve fully closed is used, and as shown in Figs. It can be displaced to the damping position. The pressure side variable throttle portion L and the expansion pressure variable throttle portion N are provided separately in the vertical direction, but they are shown in the same position in FIG.

In the embodiment of the present invention, because of the above-mentioned configuration, there are three flow paths shown in the figure as flow paths through which the fluid can flow. That is, the expansion-side first flow path D reaching the lower chamber B by opening the inner and outer peripheral portions of the expansion-side damping valve 9. An expansion-side second flow path F having a first bypass passage within the scope of the claims, which bypasses the inner side of the expansion-side damping valve 9 and reaches the outer peripheral portion of the expansion-side damping valve 9 as the expansion-side second damping valve. It is a flow path that passes through the slit 12d and the hollow portion 12a via the variable expansion throttle portion N, and further passes through the lower end large diameter portion 12e of the hollow portion 12a to reach the lower chamber B. A pressure-expansion bypass flow path H as a second expansion-side bypass path that bypasses the flow path. The above three channels.

On the other hand, there are three flow paths shown in the figure as paths through which the fluid can flow in the pressure stroke. Immediately, the pressure side first flow path E, which is a flow path that opens the pressure side damping valve 8 and reaches the upper chamber A. A pressure-side second flow path G having a pressure-side first bypass passage that bypasses the pressure-side damping valve 8 and passes through the pressure-side variable throttle portion L to reach the check valve 6. The pressure-expansion bypass flow passage H as a pressure-side second bypass passage that bypasses both the compression-side damping valves 6 and 8 and passes through the compression-expansion variable throttle unit N. The above three flow paths.

Next, the operation of the embodiment will be described.

(A) High Damping Force Control When high damping force characteristics are used, as shown in FIGS. 4 (a) and 5 (a), the expansion side variable throttle M, the compression side variable throttle L and the expansion All the diaphragms of the variable diaphragm part N are closed.

In this case, during the extension stroke, the fluid flows through the extension-side first flow path D, and the damping force having the velocity 2/3 power characteristic is serially connected at two locations, the inner side portion and the outer peripheral portion of the extension-side damping valve 9. As a result, a linear characteristic with a constant rate of change is suppressed by suppressing a decrease in the rate of change in the high speed range, and a high damping as shown by a on the extension side in FIG. 6 which is a damping force characteristic diagram. Take force characteristics.

On the other hand, during the pressure stroke, the fluid flows through the pressure-side first flow path E, and in the pressure-side damping valve 9, a damping force having a high damping force characteristic indicated by a on the pressure side in FIG. 6 is generated.

(B) At the time of controlling the medium damping force When controlling to the medium damping force, the adjuster 12 is set to the expansion side variable throttle portion M and the pressure side as shown in FIGS. 4 (b) and 5 (b). The opening degree of the variable throttle portion L is changed to rotate the variable throttle portion L in the displacement region of the middle damping force position that allows the expansion side second flow path F and the compression side second flow path G to flow.

In this case, at the time of the extension stroke, in the low piston velocity range, the flow rate is generated in the extension-side second flow passage F, and the velocity-square characteristic damping force is generated in the extension-side variable throttle portion M, and it is in direct line therewith. At the outer peripheral portion of the extension side damping valve 9, a low damping force of speed 2/3 power is generated. That is, the change rate of the characteristic that the rate of change increases with increasing speed (speed square characteristic) and conversely the characteristic that the rate of change decreases with increasing speed (speed 2/3 characteristic) The increase and decrease are canceled out, and a linear characteristic is obtained. Further, in the high piston velocity range, the inner portion of the expansion side damping valve 9 is opened to generate a flow rate in the expansion side first flow path D, and the linear characteristic as described above is obtained. Incidentally, the characteristics when the expansion side variable throttle M is opened, that is, the characteristics in a predetermined displacement region are shown by b to f on the expansion side in FIG.

On the other hand, the pressure-side second flow passage G can flow even during the pressure stroke, and in the low piston velocity range, the fluid flows only through the pressure-side second flow passage G, and the pressure-side variable throttle portion L attenuates the velocity square characteristic. Power is generated. Further, in the high piston velocity range, a flow rate is generated in the pressure side first flow path E, and the pressure side damping valve 8 opens. The characteristics at this time are shown by the characteristics b to f on the pressure side in FIG.

(C) During low damping force control When controlling to a low damping force, the adjuster 12 is applied to both variable throttle parts L and M as shown in FIGS. The opening of the variable throttle portion N is changed to rotate the variable throttle portion N in the displacement region of the low damping force position that allows the expansion bypass passage H to flow.

In this case, during the extension stroke, in the low piston velocity range, the damping force of the velocity square characteristic is generated in the extension side variable throttle portion N through the extension pressure bypass flow passage H, and in the medium piston velocity range, The linear characteristic described above is obtained by flowing through the second side flow passage F, and the linear characteristic described above is obtained by flowing through the first extension flow passage D in the high piston speed range. It is to be noted that these characteristics are shown by g to p on the extension side in FIG. 6, and of these, p is a state in which the second variable diaphragm portion is fully opened.

On the other hand, during the pressure stroke, in the low piston speed range, the damping force of the velocity squared characteristic is generated in the variable expansion throttle passage N through the expansion pressure bypass flow passage H, and in the middle piston speed range, the pressure side first The flow is generated in the two flow paths G and the above-described linear characteristic is obtained, and in the high piston velocity range, the flow is generated in the pressure side first flow path E, and the linear characteristic as described above is obtained.

As explained above, according to the damping force variable type shock absorber of the embodiment of the present invention, the two walls forming a part of the expansion pressure bypass flow passage H together with the hollow portion 12a are formed on the peripheral wall of the adjuster 12. By forming the axial slits 12d and 12d, the maximum flow passage cross-sectional area of the expansion by-pass flow passage H in the adjuster 12 is expanded by the total cross-section integral of both slits 12d and 12d, whereby the unit time per unit time is increased. It has the characteristic that the soft range damping force in the middle and high piston speed range can be made sufficiently low as the fluid flowable volume increases.

Further, according to the shock absorber of the embodiment of the present invention, as shown in the damping force characteristic diagram of FIG. 6, even if the variable width is wide, a linear characteristic in which the change rate does not largely change can be obtained. The effect is obtained. Further, on the extension side, the inside and outside of the extension side damping valve 9 are used to configure the first damping valve with high damping force and the second damping valve with low damping force, so that both damping valves are set separately. It can be made more compact than.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and there are design changes and the like within the scope not departing from the gist of the present invention. Even included in the present invention. For example, in the embodiment, the case where the present invention is applied to both the extension / compression side and the stroke side is shown, but it may be applied to only one of them. Further, in the embodiment, the piston is shown as the valve body, but it can be applied to other things such as a base that defines a chamber inside the cylinder and a reservoir chamber outside the cylinder. Further, in the embodiment, the case where the adjuster is rotated and slid is shown, but it may be slid in the axial direction or a combination of rotation and slide.

[0037]

[Effect of the device]

 As described above, in the variable damping force type shock absorber of the present invention, since the axial wall that forms a part of the bypass passage together with the hollow portion is formed in the peripheral wall of the adjuster, the maximum flow rate of the bypass passage is increased. The road cross-sectional area can be expanded by the cross-sectional integral of the axial slit, which increases the fluid flow capacity per unit time, and the damping force in the soft range in the medium and high piston speed range is sufficiently low. The effect of being able to do it is obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part of a damping force variable type shock absorber according to an embodiment of the present invention (I-I cross section in FIGS. 2 and 3).

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

4 (a), (b), and (c) are explanatory views showing displacement of the adjuster.

5 (a), (b), and (c) are explanatory diagrams showing displacement of the adjuster.

FIG. 6 is a characteristic diagram of damping force with respect to piston speed in the embodiment.

[Explanation of symbols]

 A Upper chamber B Lower chamber H Extension pressure bypass passage (bypass passage) M Extension side variable throttle section (damping force generating means) N Extension pressure variable throttle section (variable throttle section) 2 Piston (valve body) 9 Extension side damping valve (Damping force generating means) 12 Adjuster 12a Hollow part 12d Slit

Claims (1)

[Claims for utility model registration] Claims: 1. A valve body provided by defining a chamber filled with fluid into two chambers, and limiting the flow of fluid between the two chambers defined. Damping force generating means for generating a damping force, a bypass path that bypasses the damping force generating means and communicates the two chambers, and a displaceable portion provided in the middle of the bypass path to form a part of the bypass path. A damping force variable shock absorber, which is formed in a tubular shape having a hollow portion, and which includes a regulator that forms a variable throttle portion that changes a flow passage cross-sectional area of a bypass passage based on displacement. A damping force variable type shock absorber, wherein an axial slit that forms a part of the bypass passage together with a hollow portion is formed on the peripheral wall of the shock absorber.