JP2024058876A - shock absorber - Google Patents

Abstract

[Problem] To provide a shock absorber having an excellent damping function, which is provided with a simple rotary valve and a strong piston. [Solution] A shock absorber A in which a piston P is provided inside a cylinder S, a rotary valve V is provided inside the piston P, the piston P is provided with a first port p1 and a second port p2 communicating between the inside and the outside, a first discharge portion p11 that discharges a fluid in a first inner chamber r1 to a second outer chamber R2, a first groove m1 that communicates with the first discharge portion p11, a second discharge portion p21 that discharges a fluid in the second inner chamber r2 to the first outer chamber R1, and a second groove m2 that communicates with the second discharge portion p21, and the rotary valve V is provided with a first window w1 that communicates the first inner chamber r1 with the first discharge portion p11 or the first groove m1, and a second window w2 that communicates the second inner chamber r2 with the second discharge portion p21 or the second groove m2. [Selected Figure] Figure 1

Description

The present invention relates to a shock absorber that includes, for example, a cylindrical cylinder, a piston connected to a rod so as to be able to reciprocate along the inner wall of the cylinder while dividing the interior of the cylinder into a first outer chamber and a second outer chamber, and a rotary valve that is reciprocally movable and rotatable around the axis of the cylinder, is sandwiched between a first spring and a second spring and is normally held at a reference position along the axis, and divides the interior of the piston into a first inner chamber and a second inner chamber, and further includes an actuator that is attached to the piston and has an operating rod that rotates the rotary valve.

Conventionally, an example of such a shock absorber is shown in Patent Document 1 (see [0010] to [0017] and Figures 1 to 3).

This shock absorber is a spool valve type shock absorber 10. It has a cylinder 12, a piston 14 that fits 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 generating device 16 that is supported by the piston inside the cylinder.

The outer surface of the piston 14 is formed with an annular sliding portion 36 that slides against the cylinder, 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 the cylinder upper chamber 20.

The damping force generator 16 is equipped with 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 always stable in a predetermined position. An opening 66 for the second extension stroke and an opening 68 for the second compression stroke are formed in the wall of the spool valve body 52. An internal passage 72 for the 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 always in communication with the cylinder upper chamber 20. An internal passage 74 for the 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 always in communication with the cylinder lower chamber 22.

During the extension stroke, the damping force generating device 16 displaces the spool valve body 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.

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, and the upper cylinder chamber 20 and the lower cylinder chamber 22 are connected to each other via the first and second compression stroke openings 50, 68, the lower internal chamber 60, and the internal passage 74 for the compression stroke. The flow resistance when the oil 32 passes through the first and second compression stroke openings 50, 68 generates a damping force during the compression stroke.

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, 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.

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 the same, and the spool valve body is located in a standard reciprocating position relative to the piston 14. Therefore, even when the spool valve body moves from a position other than the standard reciprocating position to the standard reciprocating position, it does not seat on the valve seat portion. In this way, the shock absorber of this configuration generates damping forces during the extension stroke and compression stroke without generating seating noise by a single damping force generating device supported by the piston.

In particular, in a shock absorber of this configuration, the spool (rotary valve) can be rotated, 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 can be more optimally changed by the pressure difference between the upper cylinder chamber 20 and the lower cylinder chamber 22.

JP 2020-180691 A

In the conventional shock absorber described above, the spool valve body 52 is rotated by an electromagnetic rotary actuator 90 to adjust the overlap area of the openings 48 and 66 for the first and second extension strokes, and the overlap area of the openings 50 and 68 for the first and second compression strokes. For example, the smaller the overlap area of the openings 48 and 66, the higher the throttling effect on the oil 32 passing through the openings, and the better the function as an orifice for the extension stroke. This allows the damping effect during the extension stroke to be set to hard. On the other hand, by increasing the overlap area of the openings 48 and 66, the damping effect can be set to soft.

However, the conventional shock absorbers described above do not have a relief function in case the piston moves significantly. Therefore, if the damping effect of the shock absorber is set to be hard, the ride comfort of the vehicle in which it is installed may be significantly deteriorated.

To improve this, for example, it is possible to provide a relief valve that functions when the piston moves a specified amount. In that case, the relief valve would be housed inside the rotary valve, but even if the relief valve were made compact, the structure would be complex and measures would be required to prevent the generation of vibrations, noise, etc. As a result, it is difficult to obtain a shock absorber with a rational structure.

As such, conventional shock absorbers still have issues that need to be resolved, and there was a demand for a shock absorber with a simple rotary valve design, a strong piston, and excellent damping capabilities.

(Characteristics)
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, the piston dividing the interior of the cylinder into a first outer chamber and a second outer chamber;
a rotary valve provided inside the piston so as to be reciprocable along the axis and rotatable around the axis, 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; and an actuator provided alongside the piston, the actuator having an operating rod for rotationally driving the rotary valve,
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 first groove portion formed on an inner surface of the piston, the first groove portion communicating with the first discharge portion, being offset toward the second inner chamber relative to the first discharge portion, and having a region offset in the circumferential direction relative to the first discharge portion;
a second discharge portion formed at a portion of the piston along a circumferential direction so as to discharge the fluid in the second inner chamber to the first outer chamber;
a second groove portion formed on an inner surface of the piston, the second groove portion communicating with the second discharge portion and offset toward the first inner chamber relative to the second discharge portion, and the second groove portion having a region offset in the circumferential direction relative to the second discharge portion;
The rotary valve includes:
A first opening communicating with the first internal chamber;
a first window portion that communicates the first inner chamber with at least one of the first discharge portion and the first groove portion when the rotary valve moves from the reference position toward the second inner chamber;
A second opening communicating with the second internal chamber;
A second window portion is provided, which connects the second inner chamber to at least one of the second discharge portion and the second groove portion when the rotary valve moves from the reference position toward the first inner chamber.

(effect)
In the case of this configuration, for example, when focusing on the installation positions of the first discharge portion and the first groove, the position where the first window portion of the rotary valve communicates with the first discharge portion or the first groove portion is set so that the first groove portion is set on the side of the second inner chamber of the piston. Therefore, by rotating the rotary valve and setting the first window portion to a phase where it can communicate only with the first groove portion, the first window portion communicates with the first groove portion when the pressure difference between the first chamber and the second chamber is larger. This delays the discharge of fluid from the first inner chamber to the second outer chamber, making it possible to set a so-called stiff suspension.

In addition, since the first window portion communicates with the first groove portion, the pressure in the first inner chamber is released, and the configuration performs the same function as a relief valve. In this case, there is no need to provide the rotary valve with a relief valve, for example, a valve type or ball valve type, and the configuration of the rotary valve can be simplified.

Furthermore, instead of providing the piston with an additional opening in addition to the first discharge section, the first groove section is simply formed on the inner surface of the piston, and the fluid discharged from the first window section reaches the second outer chamber via the first groove section and the first discharge section. This prevents the strength of the piston from decreasing, and makes it possible to obtain a simple and strong piston.

(Characteristics)
In the shock absorber according to the present invention, the first groove portion and the second groove portion may be formed over the entire circumference around the axis.

(effect)
Since the first and second grooves are formed on the inner surface of the cylindrical piston, the forming process is relatively easy. In particular, when the grooves are formed around the entire circumference, there is no need to determine the positions of the start and end of the grooves. This makes it possible to obtain a shock absorber that is easier to form and is low cost.

(Characteristics)
In the shock absorber of the present invention, it is advantageous that the first discharge portion and the first groove portion, and the second discharge portion and the second groove portion are spaced apart along the axis, and that a first bottom hole communicating the second inner chamber and the second outer chamber is provided at the bottom of the first groove portion, and a second bottom hole communicating the first inner chamber and the first outer chamber is provided at the bottom of the second groove portion.

(effect)
As in this configuration, by separating the first groove portion from the first discharge portion and separating the second groove portion from the second discharge portion, the pressure conditions under which the so-called relief valve function is exerted can be set more freely.

FIG. 1 is a side cross-sectional view showing a configuration of a shock absorber according to a first embodiment. FIG. 1 is a perspective view showing a main structure of a shock absorber according to a first embodiment; FIG. 1 is a perspective view showing an operating state of a main part of a shock absorber according to a first embodiment; FIG. 1 is an explanatory diagram showing a function of a shock absorber according to a first embodiment; FIG. 1 is an explanatory diagram showing the damping effect of the shock absorber according to the first embodiment; FIG. 1 is an explanatory diagram showing a driving mode of a rotary valve according to a first embodiment; FIG. 11 is an explanatory diagram showing a main structure of a shock absorber according to a second embodiment;

First Embodiment
(overview)
A shock absorber A according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG.

Figure 1 shows the overall configuration of shock absorber A, and Figure 2 shows the structure of the main parts of shock absorber A.

Specifically, the shock absorber A of the first embodiment includes a cylindrical cylinder S having an axis X, and a cylindrical piston P connected to a rod 1 and capable of reciprocating along the inner wall of the cylinder S. The piston P divides the inside of the cylinder S into a first outer chamber R1 and a second outer chamber R2.

A rotary valve V is provided inside the piston P. 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. The rotary valve V also divides the inside of the piston P into a first inner chamber r1 and a second inner chamber r2.

The rotary valve V is rotated by an actuator a attached to the piston P via an operating rod a1.

The piston P is provided with a first port p1 that communicates between the first outer chamber R1 and the first inner chamber r1, and a second port p2 that communicates 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 portion 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 communicates with the first discharge portion p11 and is offset toward the second inner chamber r2 from the first discharge portion p11, and has a region that is offset in the circumferential direction relative to the first discharge portion p11.

Similarly, a second discharge portion p21 that discharges the fluid in 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, which is connected to the second discharge portion p21 and is offset toward the first inner chamber r1 relative to the second discharge portion p21, and has an area that is offset in the circumferential direction relative to the second discharge portion p21.

As shown in Figures 1 and 2, the rotary valve V has a first opening v1 that communicates 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.

Furthermore, the rotary valve V is provided with a second opening v2 that communicates 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.

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

The rotary valve V is driven to rotate by the actuator a and the operating rod a1, changing the opening direction of the first window w1 and the second window w2, and switching the setting of the shock absorber A between a soft setting and 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.

First, the soft setting will be explained. When 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 via the first port p1, passes through the first opening v1, and enters the inside of the rotary valve V. This hydraulic oil presses against the bottom surface of the rotary valve V, and the rotary valve V descends relative to the piston P.

Before the rotary valve V descends, it 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.

When the rotary valve V descends, the first window w1 communicates with the first discharge portion p11. As shown in FIG. 3, this first discharge portion p11 penetrates the wall of the piston P. In addition, a first groove m1 is provided on the inner surface of the piston P, which is continuous in the circumferential direction and communicates with the first discharge portion p11. In the direction along the axis X of the piston P, the first groove m1 is offset downward from the first discharge portion p11. Therefore, when the soft setting is selected, 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 indicates the position when the hard setting is selected.

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

In FIG. 4(b), if the upper edge of the first window portion w1 is at the dotted line position when the rotary valve V is in the reference position, in the software setting where the first window portion w1 is at 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 exhaust portion p11 is initiated, and a damping effect is exerted.

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

The generation of the damping force can be finely adjusted by adjusting the overlap state change between the first window portion w1 and the first discharge portion p11, or the overlap state change between the first window portion 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 can be made straight, and the lower edge of the first window portion w1 can be made bent or curved as shown in FIG. 4.

Until the first window portion w1 communicates with the first discharge portion p11 in the soft setting, 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 portion p3 provided on the outer circumferential surface of the piston P and the first inner chamber r1 inside the piston P that communicates via the first port p1 gradually increases as the rotary valve V descends. 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.

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

The cross-sectional shape of the first window portion w1 is formed with an inclined lower edge as shown in Figures 3 to 5. In other words, it 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 is mitigated in response to an increase in the speed of the piston P.

When the rotary valve V descends further 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.

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 rotary valve V move, providing what is known as a soft damping effect.

Next, the operation of the shock absorber A in the hard setting is as follows. By rotating 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 to 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 via the first groove part m1 and the first discharge part p11.

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 Figure 5, in the state from h1 to h2, the first window portion w1 and the first groove portion m1 do not communicate, and the pressure in the first outer chamber R1 and the first inner chamber r1 continues to rise.

After that, as shown in h3 of FIG. 5, the first window portion w1 communicates with the first groove portion m1 to form an orifice, and the hydraulic oil begins to flow into the second outer chamber R2. As the rotary valve V subsequently descends, the communication area between the first window portion w1 and the first groove portion m1 gradually increases in proportion to the amount of movement of the piston P, and the increase in 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 portion w1 and the first groove portion m1 in response to the descent of the rotary valve V becomes constant, the correlation between the speed of the piston P and the damping force becomes linear.

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

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 performs the same function as 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 ball valve type, and the configuration of the rotary valve V can be simplified.

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.

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

With this configuration, the first groove m1 and the second groove m2 are formed on the inner surface of the cylindrical piston P, so 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 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 less expensive.

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 via the second port p2, the second opening v2, the second window portion w2, the second discharge portion p21, and the second groove portion m2.

[Rotary valve driving 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.

The shock absorber A of this embodiment can be used for the active suspension of a vehicle. In active suspension, there is a control method called skyhook control, which is a method of constantly stabilizing the vehicle posture by moving the vehicle while suspended in midair (skyhook) on a hypothetical line.

To achieve this control, the vehicle's running state must be divided into cases where the body moves upward and cases where it moves downward, and the compression and extension characteristics of the suspension must be set appropriately for each case. In this case, the period of the body's up and down movement is approximately 1 Hz, and the period of the wheels' up and down movement is approximately 12 Hz. To increase the effectiveness of skyhook control, it is necessary to effectively damp the up and down movement of the wheels, which has a shorter period.

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 portion w1, which increases the communication area for the first discharge portion p11, and the rotation direction of the second window portion 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, the installation positions of the first window portion w1 and the second window portion 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.

In other words, 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 discharge portion p11, resulting in a hard setting for the extension damping force. In addition, the second window w2 communicates with the second discharge portion 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 discharge portion 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 discharge portion 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.

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 with 1 Hz control. For example, when the vehicle body is rising, switching to the V+ state results in the extension damping force being set to hard and the compression damping force being set to soft.

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 would raise the vehicle body even further. In other words, the compression damping force is set to a soft setting. In this case, the extension damping force is set to a hard setting due to the rotation of the rotary valve V, but the weight of the wheels and other factors act effectively on the vehicle body, suppressing the rise of the vehicle body.

On the other hand, when the vehicle body is descending, the shock absorber A is made more likely to expand and deform 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 due to the rotation of the rotary valve V, but the upward thrust load of the wheels and other factors are effectively applied to the vehicle body, preventing the vehicle body from descending.

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 supported by the first spring b1 and the second spring b2 against the piston P, can move immediately and can fully respond to the so-called unsprung movement.

In this way, shock absorber A of this embodiment can effectively perform skyhook control for the movement of the vehicle's unsprung mass over the entire frequency range.

Second Embodiment
7 shows a second embodiment of the shock absorber A. Here, the positional relationship between the first discharge portion p11 and the first groove portion m1 is shown. They are spaced apart along the axis X, and a first bottom hole p4 that connects the second inner chamber r2 and the second outer chamber R2 is provided at the bottom of the first groove portion m1.

Although not shown in the figure, the second discharge portion p21 and the second groove portion m2 are also spaced apart along the axis X, and a second bottom hole p5 is provided at the bottom of the second groove portion m2, connecting the first inner chamber r1 and the first outer chamber R1.

As in this configuration, by separating the first groove portion m1 from the first discharge portion p11 and separating the second groove portion m2 from the second discharge portion p21, the pressure conditions under which the so-called relief valve function is exerted can be set more freely.

The damping mechanism in the shock absorber of the present invention can be widely used in which a rotary valve rotates inside a piston and the damping force setting can be changed.

1 Rod A Shock absorber a Actuator a1 Operating rod b1 First spring b2 Second spring m1 First groove m2 Second groove P Piston p1 First port p11 First discharge portion p2 Second port p21 Second discharge portion p4 First bottom hole p5 Second bottom hole R1 First outer chamber R2 Second outer chamber r1 First inner chamber r2 Second inner chamber S Cylinder V Rotary valve v1 First opening v2 Second opening w1 First window w2 Second window X Axis

Claims (3)

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 provided inside the piston so as to be reciprocable along the axis and rotatable around the axis, 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; and an actuator provided alongside the piston, the actuator having an operating rod for rotationally driving the rotary valve,
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 first groove portion formed on an inner surface of the piston, the first groove portion communicating with the first discharge portion, being offset toward the second inner chamber relative to the first discharge portion, and having a region offset in the circumferential direction relative to the first discharge portion;
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;
a second groove portion formed on an inner surface of the piston, the second groove portion communicating with the second discharge portion and offset toward the first inner chamber relative to the second discharge portion, and the second groove portion having a region offset in the circumferential direction relative to the second discharge portion;
The rotary valve includes:
A first opening communicating with the first internal chamber;
a first window portion that communicates the first inner chamber with at least one of the first discharge portion and the first groove portion when the rotary valve moves from the reference position toward the second inner chamber;
A second opening communicating with the second internal chamber;
a second window portion that connects the second inner chamber to at least one of the second discharge portion and the second groove portion when the rotary valve moves from the reference position toward the first inner chamber. The shock absorber according to claim 1, wherein the first groove portion and the second groove portion are formed around the entire circumference of the axis. The shock absorber according to claim 1, wherein the first discharge portion and the first groove portion, and the second discharge portion and the second groove portion are spaced apart along the axis, the bottom of the first groove portion is provided with a first bottom hole that connects the second inner chamber and the second outer chamber, and the bottom of the second groove portion is provided with a second bottom hole that connects the first inner chamber and the first outer chamber.

Images