Shock absorber

Abstract

To provide a shock absorber with excellent operability of a rotary valve.SOLUTION: A shock absorber A comprises a piston P moving forward and backward inside a cylinder S, and a rotary valve V movable forward and backward along an axial core X inside the piston P, rotatable around the axial core X, and nipped between a first spring b1 and a second spring b2 and held at a reference position along the axial core X. A first port p1, a second port p2, a first discharge part p11 and a second discharge part p21 are provided in the piston P. A first opening v1, a first window part w1, a second opening v2 and a second window part w2 are provided on the rotary valve V. A communication area between the first window part w1 and the first discharge part p11 or a communication area between the second window part w2 and the second discharge part p21 can be changed by rotation of the rotary valve V. A ball joint 3 and a spring receiver 5 are provided between the first spring b1 and the rotary valve V and between the second spring b2 and the rotary valve V.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The shock absorber of the present invention, for example, comprises a piston connected to a rod and capable of reciprocating movement inside a cylindrical cylinder, and a rotary valve inside the piston that is capable of reciprocating movement relative to the piston and rotatable about an axis via an operating rod, and by changing the rotational phase of the rotary valve, the movement characteristics of the rotary valve inside the piston can be changed, and further by changing the reciprocating movement characteristics of the piston, the damping force of the entire shock absorber can be optimally set. [Background technology]

[0002] Conventionally, such a shock absorber is disclosed, for example, in Patent Document 1 (see

[0010] to

[0017] and Figs. 1 to 3).

[0003] This shock absorber is a spool valve type shock absorber 10. It has a cylinder 12, a piston 14 that is fitted reciprocally into the cylinder and cooperates with the cylinder to form an upper cylinder chamber 20 and a lower cylinder chamber 22, and a damping force generator 16 that is supported by the piston within the cylinder.

[0004] An annular sliding portion 36 that slides against the cylinder is formed on the outer surface of the piston 14, and an opening 48 for the first extension stroke is formed on the side of this sliding portion facing the cylinder lower chamber 22, and an opening 50 for the first compression stroke is formed on the side of this sliding portion facing the cylinder upper chamber 20.

[0005] The damping force generator 16 includes a spool valve body 52 that reciprocates inside the piston 14. The spool valve body is pressed from both sides by a pair of compression coil springs 54, 56 and is normally stable in a predetermined position. An opening 66 for a second extension stroke and an opening 68 for a second compression stroke are formed in the wall of the spool valve body 52. ​​An internal passage 72 for an extension stroke is formed inside the spool valve body, and the spool valve body cooperates with the piston 14 to form an internal upper chamber 58 that is normally in communication with the cylinder upper chamber 20. An internal passage 74 for a compression stroke is formed inside the spool valve body, and the spool valve body cooperates with the piston 14 to form an internal lower chamber 60 that is normally in communication with the cylinder lower chamber 22.

[0006] During the extension stroke, the damping force generator 16 displaces the spool valve element in a direction approaching the cylinder lower chamber 22 due to the pressure difference between the cylinder upper chamber 20 and the cylinder lower chamber 22, and communicates with the cylinder upper chamber 20 and the cylinder lower chamber 22 via the first and second extension stroke openings 48, 66, the internal upper chamber 58, and the extension stroke internal passage 72. The flow resistance when the oil 32 passes through the first and second extension stroke openings 48, 66 generates a damping force during the extension stroke.

[0007] During the compression stroke, the spool valve element is displaced toward the upper cylinder chamber 20 due to the pressure difference between the upper cylinder chamber 20 and the lower cylinder chamber 22, communicating the upper cylinder chamber 20 and the lower cylinder chamber 22 through the first and second compression stroke openings 50, 68, the inner lower chamber 60, and the compression stroke inner passage 74. The flow resistance of the oil 32 as it passes through the first and second compression stroke openings 50, 68 generates a damping force during the compression stroke.

[0008] Furthermore, the damping force generating device 16 is configured such that, when the piston 14 is displaced relative to the cylinder 12, the spool valve body 52 is displaced due to the pressure difference between the cylinder upper chamber 20 and the cylinder lower chamber 22, thereby changing the overlap area of ​​the openings 48, 66 for the first and second extension strokes and the overlap area of ​​the openings 50, 68 for the first and second compression strokes.

[0009] When the piston does not displace relative to the cylinder and there is no difference in pressure between the cylinder upper chamber 20 and the cylinder lower chamber 22, the pressing forces of the pair of elastic bodies against the spool valve body become equal, and the spool valve body is located in a standard reciprocating position relative to the piston 14. Therefore, the spool valve body does not seat on the valve seat portion even when moving from a position other than the standard reciprocating position to the standard reciprocating position. In this way, the shock absorber of this configuration generates damping forces in the extension stroke and compression stroke by a single damping force generating device supported by the piston without generating seating noise.

[0010] In particular, in the shock absorber of this configuration, the spool (rotary valve) can be rotated via the actuator 90 and the output shaft 92, and by appropriately setting the rotational phase of the spool, it is possible to change, for example, the amount of overlap between the openings 48, 66 for the first and second extension strokes. As a result, the damping force of the shock absorber when the spool and piston reciprocate due to the pressure difference between the cylinder upper chamber 20 and the cylinder lower chamber 22 can be more optimally changed. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2020-180691 A Summary of the Invention [Problem to be solved by the invention]

[0012] In the above conventional shock absorber, the spool valve element 52 is rotated via an actuator 90 and an output shaft 92, and in order to facilitate this rotation, a spring seat member 80 and a thrust bearing 82 are provided between the spool valve element 52 and the compression coil spring 54. The pressing force of the compression coil spring 54 has a predetermined spring constant so that the spool valve element 52 and the piston 14 can respond to changes in hydraulic pressure accompanying the expansion and contraction of the suspension. Therefore, the thrust bearing 82 is intended to release the frictional force generated between the spool valve element 52 and the piston 14 when the compression coil spring 54 presses against the spool valve element 52.

[0013] However, since the thrust bearing 82 and the spring seat member 80 are disposed in face-to-face contact with the end face of the spool valve body 52, if the pressing direction of the compression coil spring 54 becomes different from the sliding direction of the spool valve body 52, the spool valve body 52 will receive a lateral force and be strongly pressed against the inner wall of the piston 14. As a result, the spool valve body 52 will malfunction, and the damping force adjustment function of the shock absorber will be impaired.

[0014] As described above, conventional shock absorbers still have problems to be solved, and there has been a demand for shock absorbers with excellent operability of the rotary valve. [Means for solving the problem]

[0015] (Features) The shock absorber according to the present invention has the following features: A cylindrical cylinder having an axis; a cylindrical piston connected to the rod and reciprocating along an inner wall of the cylinder, dividing the interior of the cylinder into a first outer chamber and a second outer chamber; a rotary valve having an operating rod reciprocating along the axis and rotatable around the axis within the piston, the operating rod being sandwiched between a first spring and a second spring and normally held at a reference position along the axis, and dividing the inside of the piston into a first inner chamber and a second inner chamber; The piston has: a first port communicating the first outer chamber with the first inner chamber; a second port communicating the second outer chamber with the second inner chamber; a first discharge portion formed at a portion of the piston along a circumferential direction so as to discharge the fluid in the first inner chamber to the second outer chamber; a second discharge portion formed in a portion of the piston along the circumferential direction so as to discharge the fluid in the second inner chamber to the first outer chamber; The rotary valve includes: A first opening communicating with the first internal chamber; a first window portion that communicates the first chamber with the first discharge portion when the rotary valve moves from the reference position toward the second chamber; A second opening communicating with the second internal chamber; a second window portion that communicates the second chamber with the second discharge portion by the rotary valve moving from the reference position toward the first chamber, a flow area between the first window portion and the first discharge portion, or a flow area between the second window portion and the second discharge portion, can be changed by rotating the rotary valve via the operating rod; Between the first spring and the rotary valve, and between the second spring and the rotary valve, there are provided a ball joint which rotates relative to the rotary valve, and a spring support which abuts freely against the ball joint and abuts against the first spring or the second spring.

[0016] (effect) By providing a ball joint and spring support between the rotary valve and the first spring as in this configuration, even if the direction of the biasing force applied by the first spring to the rotary valve is not parallel to the reciprocating direction of the rotary valve, the effect on the reciprocating movement and rotation of the rotary valve is reduced.

[0017] In other words, even if a pressing force is applied to one point on the spring bearing and the first spring is distorted, the disturbance in its posture is contained within the first spring. Because the first spring and the ball joint are freely rotatable, the posture of the first spring may be disturbed slightly, but there will be no significant change in the direction in which it presses the rotary valve via the ball joint. This means that the rotary valve can always be rotated smoothly via the operating rod, allowing for quick adjustment of the shock absorption characteristics of the shock absorber.

[0018] (Features) In the shock absorber according to the present invention, the first spring and the second spring are annular leaf springs, a rotating portion of the ball joint that rotates relative to the rotary valve; A first contact surface that is in contact with the spring bearing and can freely change its position, It is preferable that the spring bearing has a hole in the center through which the operating rod passes, a second abutment surface formed on one side surface and rotatably abutting against the first abutment surface, and an annular spring seat protruding from the outer circumferential edge portion of the other side surface and abutting against the first spring or the second spring.

[0019] (effect) In this configuration, the leaf spring, which is the first or second spring, abuts against a spring seat provided on the outer periphery of the spring receiver. With this configuration, the direction of the pressing force between the first or second spring and the rotary valve is optimal. In other words, if a leaf spring is used, there is little individual variation in its shape, and the leaf spring itself changes its posture little. If a coil spring or the like were used here, the shape of the abutting portion at the end of the coil spring would not be uniform in the circumferential direction. Therefore, when the coil spring is compressed, part of it tends to jump out to the side, making the pressing direction of the coil spring unstable. However, this tendency is less with a leaf spring.

[0020] Furthermore, when the leaf spring abuts against the spring seat provided on the outer periphery of the spring bearing, even if the leaf spring is tilted, the second abutment surface in the hole provided in the center of the spring bearing abuts against the ball joint. In this case, the position of the ball joint is constant regardless of the position of the spring bearing, so the direction in which the rotary valve is pushed via the ball joint is stabilized. As a result, the rotary valve does not come into a twisting relationship with the inner surface of the piston, and the rotary valve can be rotated by the operating rod very smoothly. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a side cross-sectional view showing a configuration of a shock absorber according to a first embodiment. [Diagram 2] FIG. 1 is a perspective view showing a main structure of a shock absorber according to a first embodiment; [Diagram 3] FIG. 1 is a perspective view showing an operating state of a main part of a shock absorber according to a first embodiment; [Figure 4] FIG. 1 is an explanatory diagram showing the function of a shock absorber according to a first embodiment; [Diagram 5] FIG. 1 is an explanatory diagram showing the damping effect of the shock absorber according to the first embodiment; [Figure 6] FIG. 1 is an explanatory diagram showing a driving mode of a rotary valve according to a first embodiment; [Figure 7] FIG. 11 is an explanatory diagram showing a main structure of a shock absorber according to a second embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] [First embodiment] (overview) Shock absorber A of this embodiment includes, for example, a cylindrical cylinder S equipped with a piston P that is connected to a rod 1 and capable of reciprocating motion, and a rotary valve V equipped inside the piston P that is capable of reciprocating motion relative to the piston P and that can rotate about an axis X via an operating rod a1. By changing the rotational phase of the rotary valve V with the actuator a, the communication state between the multiple openings formed in the piston P and the rotary valve V changes, and the reciprocating motion characteristics of the rotary valve V and the piston P are changed, so that the overall damping force of the shock absorber A is set to an optimal state.

[0023] In order for the shock absorber A to perform its intended function, the rotary valve V must be operated reliably. The present invention aims to obtain a shock absorber A that improves the operability and can reliably switch its operating mode according to the running conditions of the vehicle. Hereinafter, a shock absorber A according to a first embodiment of the present invention will be described with reference to Figs. 1 to 6.

[0024] Fig. 1 shows the overall configuration of shock absorber A, and Fig. 2 shows the structure of the main parts of shock absorber A. Fig. 2(a) is an external perspective view of piston P. Fig. 2(b) is an exploded perspective view of rotary valve V slidably and rotatably contained in piston P. Shock absorber A of the first embodiment includes cylindrical cylinder S having axis X, and cylindrical piston P connected to rod 1 and capable of reciprocating along the inner wall of cylinder S. The piston P divides the inside of cylinder S into a first outer chamber R1 and a second outer chamber R2.

[0025] The rotary valve V is capable of reciprocating along the axis X and rotatable around the axis X. The rotary valve V is sandwiched between a first spring b1 and a second spring b2, and is normally held at a reference position along the axis X. In addition, the rotary valve V divides the inside of the piston P into a first inner chamber r1 and a second inner chamber r2.

[0026] The rotary valve V is rotationally driven via an operating rod a1 by an actuator a attached to the piston P. In order to perform this rotationally driving smoothly and reliably, in this embodiment, a ball joint 3 that rotates relative to the rotary valve V is provided between the first spring b1 and the rotary valve V and between the second spring b2 and the rotary valve V. Furthermore, a spring receiver 5 that rotatably abuts against each other is provided between the ball joint 3 and the first spring b1 and between the ball joint 3 and the second spring b2. The functional effects of these configurations will be described later.

[0027] The piston P is provided with a first port p1 communicating between the first outer chamber R1 and the first inner chamber r1, and a second port p2 communicating between the second outer chamber R2 and the second inner chamber r2. A first discharge portion p11 that discharges the fluid in the first inner chamber r1 to the second outer chamber R2 is formed in a part of the piston P along the circumferential direction. Meanwhile, a first groove portion m1 is formed on the inner surface of the piston P, which is communicated with the first discharge portion p11 and is offset toward the second inner chamber r2 relative to the first discharge portion p11 and has a region offset in the circumferential direction relative to the first discharge portion p11.

[0028] Similarly, a second discharge portion p21 that discharges fluid from the second inner chamber r2 to the first outer chamber R1 is formed in a portion of the piston P along the circumferential direction, and a second groove portion m2 is formed on the inner surface of the piston P, the second discharge portion p21 being connected to the second discharge portion p21 and being offset toward the first inner chamber r1 more than the second discharge portion p21, and having a region that is offset in the circumferential direction relative to the second discharge portion p21.

[0029] As shown in Figures 1 and 2, the rotary valve V has a first opening v1 communicating with the first inner chamber r1, and a first window portion w1 that communicates the first inner chamber r1 with at least one of the first discharge portion p11 and the first groove portion m1 when the rotary valve V moves from the reference position toward the second inner chamber r2.

[0030] Furthermore, the rotary valve V is provided with a second opening v2 communicating with the second inner chamber r2, and a second window portion w2 that communicates the second inner chamber r2 with at least one of the second discharge portion p21 and the second groove portion m2 when the rotary valve V moves from the reference position toward the first inner chamber r1.

[0031] (Example of operation) 2 to 4 show an example of operation of the shock absorber A of this embodiment. The example shows an operation in which, while a vehicle is running on a road surface, for example, a wheel passes over a recess and the shock absorber A expands.

[0032] The rotary valve V is rotationally driven by the actuator a and the operating rod a1, and the opening direction of the first window w1 and the second window w2 changes, switching the setting of the shock absorber A to a soft setting or a hard setting. The shaft v3 of the rotary valve V and the operating rod a1 are capable of thrust movement, and are configured so that the rotational driving force of the actuator a is transmitted to the shaft v3 while moving relatively along the axis X.

[0033] In order to ensure such rotational operation of the rotary valve V, as shown in Figures 1 and 2(b), a ball joint 3 and a spring receiver 5 are provided between the first spring b1 and the second spring b2 and the rotary valve V. For simplicity, Figure 2(b) shows only the structure of the first spring b1 out of the first spring b1 and the second spring b2.

[0034] (Ball joint) The ball joint 3 has a spherical surface serving as a first abutment surface 31. The ball joint 3 is fitted into and positioned in a thrust bearing 41 serving as a rotating part 4 fixed to an end face of the rotary valve V. The thrust bearing 41 is positioned on the shaft part v3 via, for example, a sleeve 7. A conical surface serving as a second abutment surface 51 formed on the back surface of a hole 50 of a disk-shaped spring bearing 5 abuts against the first abutment surface 31, and the spring bearing 5 is freely rotatable relative to the first abutment surface 31.

[0035] The spring bearing 5 is a disk-shaped member with a side surface having a predetermined outer diameter so that it can reciprocate along the inner wall of the piston P. A communication hole 53 is provided in a part of the spring bearing 5, which communicates the first inner chamber r1 and the second inner chamber r2 of the rotary valve V with the vicinity of the upper surface of the rotary valve V, so that the rotation of the spring bearing 5 is not hindered. In addition, the side surface of the spring bearing 5 has a length along the direction of the axis X that is sufficient to prevent the rotary valve V from tilting and getting caught in the inner surface of the piston P when the spring bearing 5 slides inside the piston P together with the rotary valve V. Furthermore, the spring bearing 5 is provided at its outermost periphery with an annular spring seat 52 against which the first spring b1 or the second spring b2 abuts.

[0036] In this configuration, by providing a ball joint 3 and a spring support 5 between the rotary valve V and the first spring b1, even if the direction of the biasing force applied by the first spring b1 to the rotary valve V is not parallel to the reciprocating direction of the rotary valve V, the effect on the reciprocating movement and rotation of the rotary valve V is reduced.

[0037] In other words, even if a pressing force is applied to one point on the spring receiver 5 and the posture of the first spring b1 is disturbed, the disturbance in posture is contained within the first spring b1 alone. Because the first spring b1 and the ball joint 3 are freely rotatable, the posture of the first spring b1 is disturbed to some extent, but there is no significant change in the direction in which it presses the rotary valve V via the ball joint 3. Therefore, the rotary valve V can always be rotated smoothly via the operating rod a1, and the impact absorption characteristics of the shock absorber A can be quickly adjusted.

[0038] In this embodiment, the first spring b1 and the second spring b2 are umbrella-shaped disc springs as a plurality of leaf springs as shown in Fig. 1. In this embodiment, three disc springs are stacked in the same direction to form a set, and these four sets are stacked in alternating directions. A support ring 6 is interposed between each set.

[0039] Among these, the set of disc springs that contacts the spring bearing 5 contacts the spring seat 52 located at the outermost position of the spring bearing 5. With this configuration, the direction of the pressing force between the first spring b1 or the second spring b2 and the rotary valve V is optimal. In other words, as shown in FIG. 1, if four sets of disc springs are combined, there is little individual difference in the shape of each disc spring, and the position of the disc spring unit itself changes little. If a coil spring or the like were used here, the shape of the contact portion of the end of the coil spring would not necessarily be uniform along the circumferential direction. Therefore, when the coil spring is compressed, a part of it tends to jump out to the side, making the pressing direction of the coil spring unstable. However, this tendency is less with disc springs.

[0040] Furthermore, one set of disc springs facing the rotary valve V and the other set facing the bottom of the piston P on the opposite side abut against the spring retainer 5 or the piston P at the outermost periphery of the disc springs. Therefore, the four disc springs are less likely to change position inside the piston P, and the pressing direction is most stable. With this configuration, the pressing direction of the rotary valve V by the first spring b1 or the second spring b2 is most stable, and the rotary valve V or the spring retainer 5 will not get caught in the inner surface of the piston P and become locked. Therefore, not only is good sliding performance maintained between these components, but the rotary operation of the rotary valve V by the operating rod a1 is also extremely smooth.

[0041] In this embodiment, an umbrella-shaped disc spring is exemplified as the first spring b1 or the second spring b2, but a completely flat leaf spring can also be used. When a flat leaf spring is used, the installation volume along the pressing direction can be reduced compared to when an inclined disc spring is used. Even in this case, adjacent leaf springs are supported on the inside or outside by the support ring 6, so the same functional effect as the disc spring described above can be achieved.

[0042] (Software setting operation) When the rotary valve V is set to soft, if a wheel (not shown) enters the recess, the cylinder S is displaced downward, the volume of the first outer chamber R1 decreases, and the pressure increases. As a result, the hydraulic oil in the first outer chamber R1 enters the first inner chamber r1 through the first port p1, passes through the first opening v1, and enters the inside of the rotary valve V. This hydraulic oil presses the bottom surface of the rotary valve V, and the rotary valve V descends relative to the piston P.

[0043] Before the rotary valve V descends, the rotary valve V is held in a reference position inside the piston P by the first spring b1 and the second spring b2. In this position, the first window w1 and the second window w2 formed on the side of the rotary valve V face the inner surface of the piston P, and hydraulic oil does not flow out from here.

[0044] When the rotary valve V descends, the first window w1 communicates with the first discharge portion p11. As shown in FIG. 3, the first discharge portion p11 penetrates the wall of the piston P. In addition, a first groove m1 is provided on the inner peripheral surface of the piston P in a circumferential direction in a state where the first discharge portion p11 is communicated with. In the direction along the axis X of the piston P, the first groove m1 is deviated downward from the first discharge portion p11. Therefore, in the case of the soft setting, the first window w1 provided on the wall of the descended rotary valve V communicates with the first discharge portion p11 before the first groove m1. Incidentally, the first window w1' in FIG. 3 shows the position in the hard setting.

[0045] Fig. 4 shows the relationship between the first window w1 and the first groove m1 in this embodiment in comparison with a conventional shock absorber A. Fig. 4(a) shows the conventional configuration, in which the first discharge portion p11 with a soft setting is only provided in the range from 0 degrees to 120 degrees along the circumferential direction, and no opening is formed in the region of, for example, 120 degrees to 180 degrees. In contrast, Fig. 4(b) shows the configuration of this embodiment, in which the first groove m1 is provided over the entire circumference of the inner surface of the piston P, overlapping with the first discharge portion p11 provided over the range from 0 degrees to 120 degrees.

[0046] In FIG. 4(b), if the upper edge position of the first window portion w1 when the rotary valve V is in the reference position is the dotted line position, in the soft setting where the first window portion w1 is in a position between 60 degrees and 120 degrees, for example, when the rotary valve V moves downward by a distance L1, communication with the first discharge portion p11 begins and a damping effect is exerted.

[0047] On the other hand, in the hard setting where the first window w1 is located at a position between 120 degrees and 180 degrees, the first window w1 does not communicate with the first groove m1 unless the upper edge position of the first window w1 moves downward from the dotted line position by a distance of L2 or more, which delays the occurrence of the damping effect.

[0048] Incidentally, the generation mode of the damping force can be finely adjusted by adjusting the change in the overlap state between the first window w1 and the first discharge portion p11 or the change in the overlap state between the first window w1 and the first groove portion m1. To achieve this, for example, the upper edges of the first discharge portion p11 and the first groove portion m1 may be made straight, and the lower edge of the first window w1 may be made bent or curved as shown in FIG.

[0049] In the soft setting, until the first window w1 communicates with the first discharge portion p11, the rotary valve V descends inside the piston P against the biasing force of the second spring b2. As a result, the total volume of the first outer chamber R1 above the partition p3 provided on the outer circumferential surface of the piston P and the first inner chamber r1 inside the piston P that communicates through the first port p1 gradually increases with the descent of the rotary valve V. This state is the state s1 shown in Figure 5, where the pressure of the hydraulic oil gradually increases and the damping mechanism of the shock absorber A is exerted.

[0050] When the rotary valve V further descends, the first window w1 communicates with the first discharge part p11, and this communication part becomes an orifice, causing the hydraulic oil in the first inner chamber r1 to flow out through the first discharge part p11 into the second outer chamber R2. This state corresponds to the state after s1 in FIG. 5, and the angle of ascent of the dotted line becomes smaller.

[0051] The cross-sectional shape of the first window w1 is formed such that the lower edge is inclined as shown in Figures 3 to 5. In other words, the cross-sectional shape is configured so that the communication area with the first discharge portion p11 gradually increases as the rotary valve V descends. As a result, as shown in the region from s1 to s2 in Figure 5, the increase in damping force relative to the increase in the speed of the piston P is mitigated.

[0052] When the rotary valve V further descends and reaches the state s3 in Figure 5, the relationship between the descending distance of the first window portion w1 and the increase in opening area becomes linear, and the relationship between the speed of the piston P and the damping force becomes linear.

[0053] In this way, with the soft setting, the hydraulic oil in the first outer chamber R1 flows into the second outer chamber R2 relatively early when the piston P and the rotary valve V move, and a so-called soft damping effect can be achieved.

[0054] (Operation when hardware is set) Next, the operation of the shock absorber A in the hard setting is as follows. By the rotational drive of the actuator a and the operating rod a1, the first window w1 of the rotary valve V is set to a position different from the position of the first discharge part p11. In other words, when the rotary valve V descends, the first window w1 descends on the side of the first discharge part p11 and is set to a deeper position than the position where it communicates with the above-mentioned first discharge part p11, that is, to communicate with the first groove part m1. When the first discharge part p11 and the first groove part m1 communicate with each other, the working fluid in the first inner chamber r1 is discharged to the second outer chamber R2 through the first groove part m1 and the first discharge part p11.

[0055] With this setting, the degree of increase in the internal pressure of the first outer chamber R1 and the first inner chamber r1 increases when the rotary valve V descends. For example, as shown by the solid line in Fig. 5, in the state from h1 to h2, the first window portion w1 and the first groove portion m1 do not communicate with each other, and the pressure of the first outer chamber R1 and the first inner chamber r1 continues to rise.

[0056] After that, as shown in h3 of Fig. 5, the first window w1 communicates with the first groove m1 to form an orifice, and the hydraulic oil starts to flow out to the second outer chamber R2. As the rotary valve V subsequently descends, the communication area between the first window w1 and the first groove m1 gradually increases in proportion to the amount of movement of the piston P, and the increase in the damping force is mitigated. As the rotary valve V further descends, as shown in h4 of Fig. 5, when the increase in the communication area between the first window w1 and the first groove m1 in accordance with the descent of the rotary valve V becomes constant, the correlation between the speed of the piston P and the damping force becomes linear.

[0057] In this embodiment, as described above, the first groove m1 communicating with the first discharge portion p11 is formed on the inner surface of the piston P, and the first groove m1 has a region that is offset in the circumferential direction relative to the first discharge portion p11. In addition, by rotating the rotary valve V and setting the first window w1 to a phase that allows communication only with the first groove m1, the first window w1 can be communicated with the first groove m1 in a state where the pressure difference between the first outer chamber R1 and the second outer chamber R2 is larger. This delays the discharge of the fluid from the first inner chamber r1 to the second outer chamber R2, allowing a so-called stiff suspension setting to be achieved.

[0058] In addition, since the first window portion w1 communicates with the first groove portion m1, the pressure in the first inner chamber r1 is released, and this configuration exerts a function equivalent to that of a relief valve. In this case, there is no need to provide the rotary valve V with a relief valve of, for example, a valve type or a ball valve type, and the configuration of the rotary valve V can be simplified.

[0059] Furthermore, instead of providing the piston P with an additional opening in addition to the first discharge portion p11, the first groove portion m1 is simply formed on the inner surface of the piston P, and the fluid flowing through the first window portion w1 is discharged to the second outer chamber R2 via the first groove portion m1 and the first discharge portion p11. This prevents the strength of the piston P from decreasing, and makes it possible to obtain a simple and strong piston P.

[0060] As shown in FIG. 1 and FIG. 3, the first groove portion m1 and the second groove portion m2 in this embodiment are formed on the inner surface of the piston P around the axis X over the entire circumference.

[0061] With this configuration, the first groove m1 and the second groove m2 are formed on the inner surface of the cylindrical piston P, and therefore the forming process is relatively easy. In particular, by forming them around the entire circumference, it is not necessary to determine the positions of the start and end ends of the first groove m1 and the second groove m2, and it is possible to obtain a shock absorber A that is easier to form and is low cost.

[0062] Furthermore, when the vehicle goes over a protrusion, the cylinder S rises relative to the piston P, the pressure of the hydraulic oil in the second outer chamber R2 increases, and the hydraulic oil in the second outer chamber R2 is discharged into the first outer chamber R1 through the second port p2, the second opening v2, the second window portion w2, the second discharge portion p21, and the second groove portion m2.

[0063] [Rotary valve V drive mode] FIG. 6 shows an example of the manner in which the rotary valve V is driven when, for example, controlling the damping force of a vehicle.

[0064] The shock absorber A of this embodiment can be used for the active suspension of a vehicle. In the active suspension, there is a control method called skyhook control, in which the vehicle is moved while suspended in midair (skyhook) from a line temporarily set in the air, thereby making it possible to always stabilize the vehicle posture.

[0065] To perform this control, it is necessary to divide the vehicle's running state into cases where the body moves upward and downward, and to set the compression and extension characteristics of the suspension appropriately for each case. In this case, the period of the vertical movement of the body is about 1 Hz, and the period of the vertical movement of the wheels is about 12 Hz, and to increase the effectiveness of skyhook control, it is necessary to effectively damp the vertical movement of the wheels, which has a shorter period.

[0066] In the shock absorber A of this embodiment, the expansion and contraction oil passages are configured independently, and the rotation direction of the first window w1, which increases the communication area for the first discharge portion p11, and the rotation direction of the second window w2, which increases the communication area for the second discharge portion p21, are configured to be switched in opposite directions. As shown in Fig. 2(b), the installation positions of the first window w1 and the second window w2 differ by about 90 degrees along the circumferential direction, and the installation positions of the first discharge portion p11 and the second discharge portion p21 differ by about 30 degrees along the circumferential direction. As a result, if the rotary valve V is placed at the position V0 in Fig. 6, for example, as the reference position, the expansion damping force or the compression damping force can be hard-set by rotating the rotary valve V 30 degrees to the left and right from the reference position.

[0067] That is, in FIG. 6, when the rotary valve V rotates about 30 degrees clockwise from the reference position V0 to the V+ state, the first window w1 cannot communicate with the first outlet p11, resulting in a hard setting for the extension damping force. In addition, the second window w2 communicates with the second outlet p21 at the maximum area, resulting in a soft setting for the compression damping force. On the other hand, in FIG. 6, when the rotary valve V rotates about 30 degrees counterclockwise from the reference position V0 to the V- state, the first window w1 communicates with the first outlet p11 at the maximum area, resulting in a soft setting for the extension damping force, and the second window w2 cannot communicate with the second outlet p21, resulting in a hard setting for the compression damping force. The rotary valve V is rotated by the actuator a at a sufficient rotational speed.

[0068] In this configuration, the vertical movement of the vehicle body is monitored using a sensor (not shown), and the position of the rotary valve V is switched between the V+ state and the V- state in Figure 6 at 1 Hz control. For example, when the vehicle body is rising, switching to the V+ state sets the extension damping force to a hard setting and the compression damping force to a soft setting.

[0069] In other words, when the vehicle body is rising, the shock absorber A is made more likely to compress in order to release the force that tries to lift the vehicle body further. In other words, the compression damping force is set to soft. In this case, the extension damping force is set to hard by the rotation of the rotary valve V, but the weight of the wheels and other factors act effectively on the vehicle body to suppress the rise of the vehicle body.

[0070] On the other hand, when the vehicle body is descending, the shock absorber A is made more likely to expand in order to release the force that would further lower the vehicle body. In other words, the expansion damping force is set to a soft setting. In this case, the compression damping force is set to a hard setting by the rotation of the rotary valve V, but the upward thrust load of the wheels is effectively applied to the vehicle body, preventing the vehicle body from descending.

[0071] According to the configuration of this embodiment, when the shock absorber A expands and contracts at 12 Hz, the hydraulic oil inside the cylinder S receives an external force, which is instantly transmitted to the piston P and the rotary valve V. The rotary valve V, which is biased and supported by the first spring b1 and the second spring b2 relative to the piston P, can move immediately and can adequately respond to the so-called unsprung movement.

[0072] In this way, with the shock absorber A of this embodiment, skyhook control can be effectively performed for movements of the vehicle's unsprung mass over the entire frequency range.

[0073] [Another embodiment] 7(a) to 7(c) show another embodiment of the spring bearing 5. For ease of explanation, only the side of the first spring b1 is shown. The first spring b1 is a disc spring, as in the first embodiment. First, FIG. 7(a) shows an example in which the spring seat 52 at the outermost peripheral position of the spring bearing 5 is formed in a position close to the rotary valve V along the expansion and contraction direction of the first spring b1 relative to the second contact surface 51.

[0074] With this configuration, when the first spring b1 presses the spring bearing 5, the position of the spring seat 52 is located further in the pressing direction than the first contact surface 31 of the ball joint 3. Conversely, when the rotary valve V presses back the spring bearing 5 via the ball joint 3, the position of the first contact surface 31 is located further in the pressing direction than the spring seat 52. Therefore, no matter in which direction the spring bearing 5 moves, the posture of the spring bearing 5 is stable, and the frictional force generated between the spring bearing 5 and the inner surface of the piston P is reduced. With this configuration, there is no need to increase the axial length of the side surface so that the spring bearing 5 does not bite into the inner surface of the piston P, and the operation of the rotary valve V can be smoothed without enlarging the device.

[0075] Figure 7(b) shows an example in which the inclination direction of the first spring b1 is configured so that it approaches the spring holder 5 toward the center, and the first spring b1 abuts on the upper surface of the spring holder 5 on the inner side of the radial center position.

[0076] With this configuration, the position at which the first spring b1 applies a pressing force to the spring bearing 5 approaches the second contact surface 51 of the ball joint 3 along the radial direction. Therefore, even if the posture of the first spring b1 and the spring bearing 5 is disturbed, the moment of rotation of the spring bearing 5 about the second contact surface 51 as a fulcrum is reduced, and further disturbance of the posture of the spring bearing 5 is suppressed. Therefore, the posture of the rotary valve V is also stabilized, and the operation of the rotary valve V becomes smooth.

[0077] Furthermore, if the upper surface of the spring bearing 5 is configured to be flat, the first spring b1 presses the upper surface of the spring bearing 5 in the vertical direction, and no force component pressing the spring bearing 5 in the radial direction is generated. Therefore, the spring bearing 5 itself is not pressed against the inner surface of the piston P, and the rotary valve V and the spring bearing 5 can reciprocate smoothly.

[0078] FIG. 7(c) shows an example in which the upper surface of the spring bearing 5 is flat, and the first spring b1 abuts on the upper surface of the spring bearing 5 on the outer periphery side relative to the central position along the radius.

[0079] In this configuration, the contact position of the first spring b1 is reversed from the inside to the outside compared to the example in Fig. 7(b). With this configuration, the winding diameter of the first spring b1 can be secured to be large, and the first spring b1 is less likely to change in posture, such as tilting the pressing direction when it expands or contracts. As a result, lateral forces and rotational forces are less likely to be generated in the spring receiver 5 and the rotary valve V, and the movement of the spring receiver 5 and the rotary valve V becomes smoother. [Industrial Applicability]

[0080] The damping mechanism in the shock absorber A of the present invention has a piston P connected to a rod 1 and capable of reciprocating movement inside a cylindrical cylinder S, and has a rotary valve V inside the piston P that is capable of reciprocating movement relative to the piston P and can be rotatable around an axis X via an operating rod a1, and can be used in a wide variety of applications in which the movement characteristics of the rotary valve V inside the piston P can be changed by changing the rotational phase of the rotary valve V. [Explanation of symbols]

[0081] 1 Rod 3. Ball joint 31 First contact surface 4 Rotating section 5 Spring holder 50 hole 51 Second contact surface 52 Spring seat A. Shock absorber a Actuator a1 Operating rod b1 First spring b2 Second spring m1 First groove m2 2nd groove P piston p1 1st port p11 1st discharge section p2 Second port p21 2nd discharge section R1 1st outer room R2 2nd outer room r1 1st interior room r2 2nd interior room S cylinder V Rotary Valve v1 1st aperture v2 2nd aperture w1 First window w2 Second window X-axis center

Claims

1. A cylindrical cylinder having an axis; a cylindrical piston connected to the rod and reciprocating along an inner wall of the cylinder, the piston dividing the interior of the cylinder into a first outer chamber and a second outer chamber; a rotary valve having an operating rod reciprocating along the axis and rotatable around the axis within the piston, the operating rod being sandwiched between a first spring and a second spring and normally held at a reference position along the axis, and dividing the inside of the piston into a first inner chamber and a second inner chamber; The piston has: a first port communicating the first outer chamber with the first inner chamber; a second port communicating the second outer chamber with the second inner chamber; a first discharge portion formed at a portion of the piston along a circumferential direction so as to discharge the fluid in the first inner chamber to the second outer chamber; a second discharge portion formed in a portion of the piston along the circumferential direction so as to discharge the fluid in the second internal chamber to the first external chamber, The rotary valve includes: A first opening communicating with the first internal chamber; a first window portion that communicates the first chamber with the first discharge portion when the rotary valve moves from the reference position toward the second chamber; A second opening communicating with the second internal chamber; a second window portion that communicates the second chamber with the second discharge portion by the rotary valve moving from the reference position toward the first chamber, a flow area between the first window portion and the first discharge portion or a flow area between the second window portion and the second discharge portion can be changed by rotating the rotary valve via the operating rod, The shock absorber includes a ball joint between the first spring and the rotary valve, and between the second spring and the rotary valve, the ball joint rotating relative to the rotary valve, and a spring support rotatably contacting the ball joint and contacting the first spring or the second spring.

2. the first spring and the second spring are annular leaf springs, a rotating portion of the ball joint that rotates relative to the rotary valve; A first contact surface that is capable of freely changing its position by contacting the spring bearing, 2. The shock absorber as described in claim 1, wherein the spring bearing has a hole in the center through which the operating rod passes, a second abutment surface formed on one side surface and rotatably abutting the first abutment surface, and an annular spring seat protruding from the outer peripheral edge portion of the other side surface and abutting the first spring or the second spring.

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