JP2020143682A - Damper - Google Patents

Abstract

To provide a damper capable of increasing the adjustable range of damping force when a piston speed is in a medium-high speed range, and of improving riding comfort when mounted on a vehicle.SOLUTION: A damper A includes a hard side damping element FH for giving a resistance to the flow of liquid moving between an extension side chamber L1 and a pressure side chamber L2, a solenoid valve V capable of changing the opening area of a bypass passage B bypassing the hard side damping element FH and communicating the extension side chamber L1 with the pressure side chamber L2, a soft side damping element FS provided in the bypass passage B in series with the solenoid valve V, and a tank T connected to a lower pressure side out of the extension side chamber L1 and the pressure side chamber L2 with a low pressure priority valve 6, the hard side damping element FH including an orifice 22, and hard leaf valves 20, 21 provided in parallel thereto, the soft side damping element FS including an orifice 52 having an opening area larger than that of the orifice 22.SELECTED DRAWING: Figure 4

Description

The present invention relates to improvements in shock absorbers.

Conventionally, a liquid such as hydraulic oil is stored in a shock absorber, and a damping element gives resistance to the flow of the liquid generated when the piston moves in the cylinder, and a damping force caused by the resistance is given. There is something that demonstrates.

The damping element is configured with, for example, an orifice and a leaf valve provided in parallel with the orifice. When the piston speed is in the low speed range and the differential pressure between the upstream side and the downstream side of the damping element is less than the valve opening pressure of the leaf valve, the liquid passes only through the orifice. On the other hand, when the piston speed is in the medium to high speed range and the differential pressure is equal to or higher than the valve opening pressure of the leaf valve, the liquid passes through the leaf valve.

Therefore, the damping force characteristic with respect to the piston speed of the shock absorber (hereinafter referred to as "damping force characteristic") is based on the orifice characteristic proportional to the square of the piston speed peculiar to the orifice when the leaf valve is opened. , The valve characteristics change to be proportional to the piston speed peculiar to leaf valves.

Further, in the shock absorber, for the purpose of adjusting the generated damping force, a bypass path that bypasses the damping element and a needle valve that adjusts the opening area of the bypass path are provided, or a damping element is provided. A pilot valve for controlling the back pressure of the constituent leaf valves may be provided (for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 2010-7758 Japanese Unexamined Patent Publication No. 2014-156858

For example, in the shock absorber provided with the needle valve described in Japanese Patent Application Laid-Open No. 2010-7758, when the needle valve is driven to increase the opening area of the bypass path, the flow rate of the liquid passing through the damping element decreases. The damping force becomes smaller (soft mode in FIG. 7). On the contrary, when the opening area of the bypass path is reduced, the flow rate of the liquid passing through the damping element increases and the damping force generated increases (hard mode in FIG. 7).

The adjustment of the damping force by such a needle valve is mainly used for adjusting the magnitude of the damping force when the piston speed is in the low speed range. When the opening area of the bypass path is adjusted by the needle valve, the damping force when the piston speed is in the medium-high speed range is adjusted to some extent, but it is difficult to increase the adjustment range.

On the other hand, in the shock absorber provided with the pilot valve described in Japanese Patent Application Laid-Open No. 2014-156858, when the valve opening pressure of the pilot valve is lowered and the back pressure of the leaf valve is reduced, the valve opening pressure of the leaf valve is lowered. The damping force generated is reduced (soft mode in FIG. 8). On the contrary, when the valve opening pressure of the pilot valve is increased and the back pressure of the leaf valve is increased, the valve opening pressure of the leaf valve is increased and the damping force generated is increased (hard mode in FIG. 8).

In this way, when the back pressure of the leaf valve is controlled to change the valve opening pressure, the adjustment range of the damping force when the piston speed is in the medium-high speed range can be increased. However, in this case, the characteristic line showing the damping force characteristic in the medium and high speed range shifts up and down without changing its inclination. Therefore, especially in the hard mode, the characteristic line when shifting from the low speed range to the medium and high speed range. The slope of is changed rapidly. For this reason, when the shock absorber is mounted on the vehicle, it may give a sense of discomfort to the occupants and lead to deterioration of riding comfort.

Therefore, an object of the present invention is to provide a shock absorber that can solve these problems, increase the adjustment range of the damping force when the piston speed is in the medium to high speed range, and improve the riding comfort when mounted on a vehicle. And.

A shock absorber that solves the above problems includes a hard side damping element that resists the flow of liquid moving between the extension side chamber and the compression side chamber, which are partitioned by a piston that is movably inserted into the cylinder, and a hard side damping element. A solenoid valve that can change the opening area of the bypass path that bypasses the element and connects the extension side chamber and the compression side chamber, a soft side damping element provided in series with the solenoid valve in the bypass path, and a low pressure priority valve to the extension side chamber. It is equipped with a tank connected to the low pressure side of the compression side chamber. The hard side damping element is configured to have an orifice and a leaf valve provided in parallel with the orifice, and the soft side damping element is configured to have a large diameter orifice having a larger opening area than the orifice.

According to the above configuration, the damping force generated by the shock absorber has an orifice characteristic peculiar to the orifice when the piston speed is in the low speed range, and is peculiar to the leaf valve when the piston speed is in the medium to high speed range. It becomes the valve characteristic of. Then, if the opening area of the bypass path is changed by the solenoid valve, the distribution ratio of the flow rate passing through each of the hard side damping element and the soft side damping element in the liquid moving between the extension side chamber and the compression side chamber changes. Therefore, both the damping coefficient when the piston speed is in the low speed range and the damping coefficient when the piston speed is in the medium and high speed range can be freely set, and the adjustment range of the generated damping force can be increased.

Furthermore, in the soft mode in which the distribution ratio of the liquid passing through the soft side damping element is increased, both the damping coefficient when the piston speed is in the low speed range and the damping coefficient when the piston speed is in the medium and high speed range can be reduced. On the contrary, in the hard mode in which the distribution ratio of the liquid passing through the soft damping element is reduced, both the damping coefficient when the piston speed is in the low speed range and the damping coefficient when the piston speed is in the medium and high speed range can be increased. As a result, when the damping force characteristic changes from the orifice characteristic in the low speed range to the valve characteristic in the medium and high speed range, the change in the slope of the characteristic line can be made gentle in any mode, and thus the buffer according to the present invention. When the vessel is mounted on the vehicle, the ride quality of the vehicle can be improved.

Further, the shock absorber may be configured to have a leaf valve in which the soft side damping element is provided in parallel with the large diameter orifice. As a result, even if a valve with high valve rigidity is adopted as the leaf valve of the damping element on the hard side, the damping force in the soft mode does not become excessive. Therefore, the adjustment range of the damping force when the piston speed is in the medium to high speed range can be further increased.

Further, in the above shock absorber, a tubular holder in which a port for connecting a solenoid valve to a bypass path is formed, a spool that is reciprocally inserted into the holder to open and close the port, and a spool in the moving direction of the spool. It may have an urging spring that urges the spool to one side and a solenoid that applies a thrust in the direction opposite to the urging force of the urging spring to the spool. By doing so, the opening degree of the solenoid valve can be easily increased without increasing the stroke amount of the spool serving as the valve body of the solenoid valve, so that the adjustment width of the opening area of the bypass path can be easily increased. Further, the degree of freedom in setting the relationship between the opening degree of the solenoid valve and the amount of energization can be increased.

Further, in the above shock absorber, as the leaf valve of the damping element on the hard side, the hard leaf valve on the extension side that gives resistance to the flow of the liquid from the extension side chamber to the compression side chamber and the liquid flow from the compression side chamber to the extension side chamber are used. A hard leaf valve on the compression side that gives resistance is provided, and as a leaf valve for the soft side damping element, a soft leaf valve on the extension side that gives resistance to the flow of liquid from the extension side chamber to the compression side chamber in the bypass path and a bypass path are provided. A soft leaf valve on the compression side that resists the flow of liquid from the compression side chamber to the extension chamber may be provided. In this way, when the piston speed is in the medium-high speed range, the adjustment range of the damping force on both sides of the extension force can be increased.

Further, in the above-mentioned shock absorber, the ports on the extension side where the unidirectional flow of the liquid from the extension side chamber to the compression side chamber is allowed and the port on the compression side where the unidirectional flow of the liquid from the compression side chamber to the compression side chamber is allowed. When a port is provided and the amount of electricity supplied to the solenoid valve is increased, the opening degree of one of the extension side port and the compression side port increases, and the opening degree of the other port decreases. It may be set. In this way, when the damping force of one of the extension side and the compression side is adjusted to be high, the damping force of the other is automatically adjusted to be low, and when the shock absorber is mounted on the vehicle, the vehicle The height can be induced to be higher or lower.

Also, in the shock absorber, the port may allow bidirectional flow of liquid. In this way, a member for making the port one-way is not required, so that the solenoid valve configuration can be simplified and miniaturized.

Further, in the shock absorber, the spool and the low pressure priority valve may move along a straight line orthogonal to the central axis passing through the center of the piston rod. In this way, when the shock absorber is mounted on the vehicle, it is possible to prevent the spool and the low pressure priority valve from being vibrated in the moving direction due to the vibration during the running of the vehicle.

Further, the shock absorber may include a housing and a sub-cylinder provided in the housing to accommodate a soft-side damping element, and a low-pressure priority valve may be provided between the housing and the sub-cylinder. In this way, it is possible to prevent the housing from becoming long in the axial direction.

Further, in the above shock absorber, the housing may be integrated with the cylinder. In this way, it is not necessary to connect the housing and the cylinder with a hose, so that it is possible to prevent an unintended damping force from being generated due to resistance when the liquid passes through the hose. Furthermore, since the hose can be omitted, the cost can be reduced.

According to the shock absorber according to the present invention, the adjustment range of the damping force when the piston speed is in the medium-high speed range can be increased, and the riding comfort when mounted on a vehicle can be improved.

It is a front view which showed the shock absorber which concerns on one Embodiment of this invention by partially cutout. It is a partially enlarged vertical sectional view which showed the damping force adjustment part of the shock absorber which concerns on one Embodiment of this invention in an enlarged manner. It is a vertical cross-sectional view which showed the part of FIG. 2 enlarged. It is a hydraulic circuit diagram of the shock absorber which concerns on one Embodiment of this invention. It is a damping force characteristic diagram which showed the characteristic of the damping force with respect to the piston speed of the shock absorber which concerns on one Embodiment of this invention. It is a hydraulic circuit diagram which showed the modification of the shock absorber which concerns on one Embodiment of this invention. It is a damping force characteristic diagram which showed the characteristic of the damping force with respect to the piston speed of the shock absorber provided with the conventional needle valve. It is a damping force characteristic diagram which showed the characteristic of the damping force with respect to the piston speed of the shock absorber provided with the conventional pilot valve.

The shock absorber according to the embodiment of the present invention will be described below with reference to the drawings. The same reference numerals, given throughout several drawings, indicate the same or corresponding parts. Further, the shock absorber according to the embodiment of the present invention is used for a rear cushion device for suspending the rear wheels of a saddle-type vehicle. In the following description, the top and bottom with the shock absorber attached to the vehicle are simply referred to as "top" and "bottom" unless otherwise specified.

As shown in FIG. 1, the shock absorber A according to the embodiment of the present invention includes an outer shell 10 and a retractable shock absorber main body D having a piston rod 3 that goes in and out of the outer shell 10. A suspension spring S provided on the outer periphery of the shock absorber main body D, a damping force adjusting portion E provided integrally with the shock absorber main body D, and a tank T connected to the damping force adjusting portion E with a hose are provided. ing.

Further, the shock absorber A is an inverted type, and the piston rod 3 projects downward from the outer shell 10. A bracket 30 on the axle side is provided at the lower end of the piston rod 3. The bracket 30 is connected to a swing arm that is swingably connected to the vehicle body. Since the rear wheels are rotatably supported by the swing arm, it can be said that the piston rod 3 is connected to the axles of the rear wheels.

On the other hand, a ceiling-shaped end cap 11 is screwed on the outer periphery of the upper end of the outer shell 10. A bracket 12 on the vehicle body side is provided on the top of the end cap 11, and the outer shell 10 is connected to the vehicle body via the bracket 12.

In this way, the shock absorber body D is interposed between the vehicle body in the vehicle and the axles of the rear wheels. Then, when the rear wheels vibrate up and down with respect to the vehicle body, such as when the vehicle travels on an uneven road surface, the piston rod 3 moves in and out of the outer shell 10 and the shock absorber body D expands and contracts. The expansion and contraction of the shock absorber body D in this way is also referred to as the expansion and contraction of the shock absorber A.

Further, in the present embodiment, the suspension spring S is a coil spring. The upper end of the suspension spring S is supported by the upper spring receiver 13 mounted on the outer circumference of the outer shell 10. On the other hand, the lower end of the suspension spring S is supported by the lower spring receiver 31 attached to the bracket 30 on the axle side. Since the bracket 30 on the axle side is connected to the piston rod 3, it can be said that one end of the suspension spring S is supported by the outer shell 10 and the other end is supported by the piston rod 3.

Then, when the shock absorber A contracts and the piston rod 3 enters the outer shell 10, the suspension spring S is compressed and exerts an elastic force to urge the shock absorber A in the extension direction. In this way, the suspension spring S exerts an elastic force according to the amount of compression so that the vehicle body can be elastically supported.

The direction in which the shock absorber A is attached is not limited to the drawing, and may be, for example, upside down in FIG. Further, the mounting target of the shock absorber A is not limited to the vehicle and can be changed as appropriate. Further, the suspension spring S may be a spring other than the coil spring such as an air spring, and the suspension spring S may be omitted depending on the attachment target of the shock absorber A.

Subsequently, the shock absorber main body D is a double cylinder type, and a cylinder 1 as an inner cylinder is provided inside the outer shell 10. A piston 2 is slidably inserted into the cylinder 1. The piston 2 is connected to the outer periphery of the upper end of the piston rod 3 with a nut 32. Then, when the shock absorber A expands and contracts, the piston rod 3 moves in and out of the cylinder 1, and the piston 2 moves up and down (axially) in the cylinder 1.

Further, as described above, a ceiling-shaped end cap 11 is screwed around the outer periphery of the upper end of the outer shell 10, and the upper end of the outer shell 10 is closed by the end cap 11. On the other hand, an annular rod guide 14 that slidably supports the piston rod 3 is attached to the lower end of the outer shell 10. Seals 15, 16 and 17 are attached to the rod guide 14, and the outer circumference of the piston rod 3 and the inner circumference of the outer shell 10 are sealed, respectively.

In this way, the inside of the outer shell 10 is a closed space, and the liquid contained in the outer shell 10 including the inside of the cylinder 1 is prevented from leaking to the outside. A working chamber L filled with a liquid such as hydraulic oil is formed in the cylinder 1, and the working chamber L is divided into a lower extension side chamber L1 and an upper compression side chamber L2 by a piston 2. ing.

The extension side chamber L1 referred to here is the room that is compressed by the piston 2 when the shock absorber A is extended, out of the two chambers partitioned by the piston. On the other hand, the compression side chamber L2 is the chamber of the two chambers partitioned by the piston 2 that is compressed by the piston 2 when the shock absorber A contracts.

The piston 2 is formed with an extension side passage 2a and a compression side passage 2b that communicate the extension side chamber L1 and the compression side chamber L2, and the extension side chamber L1 and the compression side chamber L2 pass through the extension side passage 2a or the compression side passage 2b. A hard side damping element FH is attached that resists the flow of liquid moving between them. The hard-side damping element FH includes an extension-side hard leaf valve 20 which is a leaf valve that opens and closes the extension-side passage 2a, a compression-side hard leaf valve 21 which is a leaf valve that opens and closes the compression-side passage 2b, and an orifice 22 (FIG. 4) and is configured.

The extension side and compression side hard leaf valves 20 and 21 are thin annular plates made of metal or the like, or a laminated body obtained by stacking the annular plates, and have elasticity. The extension side hard leaf valve 20 is laminated on the upper side of the piston 2 in a state where the outer peripheral side (or inner peripheral side) is allowed to bend, and the extension side hard leaf valve 20 has the pressure of the extension side chamber L1. Acts in the direction of bending the outer peripheral portion upward. The compression side hard leaf valve 21 is laminated on the lower side of the piston 2 in a state where the outer peripheral side (or inner peripheral side) of the hard leaf valve 21 is allowed to bend, and the pressure of the compression side chamber L2 is applied to the compression side hard leaf valve 21. It acts in the direction of bending the outer peripheral part downward.

The orifice 22 has a notch provided on the outer peripheral portion of one or both of the hard leaf valves 20 and 21 on the extension side and the compression side that are detached and seated on the valve seat of the piston 2, or a stamp provided on the valve seat or the like. Is formed by. Therefore, it can be said that the orifice 22 is provided in one or both of the extension side passage 2a and the compression side passage 2b in parallel with the extension side and compression side hard leaf valves 20 and 21.

The extension side chamber L1 is compressed by the piston 2 when the shock absorber A is extended, and its internal pressure rises, which is higher than the pressure of the compression side chamber L2. On the other hand, the compression side chamber L2 is compressed by the piston 2 when the shock absorber A contracts, and its internal pressure rises, which is higher than the pressure of the extension side chamber L1. As described above, when the shock absorber A expands and contracts, a differential pressure is generated between the extension side chamber L1 and the compression side chamber L2. When the piston speed is in the low speed range when the shock absorber A expands and contracts, and the differential pressure is less than the valve opening pressures of the extension side and compression side hard leaf valves 20 and 21, the liquid extends through the orifice 22. Sometimes it goes from the extension chamber L1 to the compression side chamber L2, and when it contracts, it goes from the compression side chamber L2 to the extension chamber L1, and resistance is given by the orifice 22 to the flow of the liquid.

Further, when the piston speed increases when the shock absorber A is extended and the piston speed is in the medium to high speed range, and the differential pressure becomes large and exceeds the valve opening pressure of the extension side hard leaf valve 20, the outer circumference of the extension side hard leaf valve 20 The portion bends upward to form a gap between the outer peripheral portion and the piston 2, and the liquid passes through the gap from the extension side chamber L1 to the compression side chamber L2 and imparts resistance to the flow of the liquid. Will be done. Further, when the piston speed is in the middle and high speed range when the shock absorber A contracts, and the differential pressure between the extension side chamber L1 and the compression side chamber L2 becomes large and exceeds the valve opening pressure of the compression side hard leaf valve 21, the compression side hard leaf valve The outer peripheral portion of 21 bends downward to form a gap between the outer peripheral portion and the piston 2, and the liquid passes through the gap from the compression side chamber L2 to the extension side chamber L1 and with respect to the flow of the liquid. Resistance is given.

As can be seen from the above, the orifice 22 of the hard side damping element FH and the extension side hard leaf valve 20 give resistance to the flow of liquid from the extension side chamber L1 to the compression side chamber L2 when the shock absorber A is extended. Acts as the first damping element of. Further, the orifice 22 of the hard side damping element FH and the compression side hard leaf valve 21 are the first compression side damping elements that give resistance to the flow of liquid from the compression side chamber L2 to the extension side chamber L1 when the shock absorber A contracts. Functions as. The resistance due to these first damping elements is caused by the orifice 22 when the piston speed is in the low speed range, and is caused by the hard leaf valves 20 and 21 on the extension side or the compression side when the piston speed is in the medium and high speed range. ..

Subsequently, a tubular gap C1 is formed between the cylinder 1 and the outer shell 10. The gap C1 is always communicated with the extension side chamber L1 through a hole 1a formed at the lower end of the cylinder 1. Further, the gap C1 is communicated with the damping force adjusting portion E through the hole 10a formed in the upper end portion of the outer shell 10 and the extension side opening 11a formed in the end cap 11. Further, the end cap 11 is formed with a compression side opening 11b, and the compression side chamber L2 is communicated with the damping force adjusting portion E through the compression side opening 11b.

As shown in FIG. 2, the damping force adjusting portion E includes a bottomed cylindrical housing 4, a cap 40 that closes the opening of the housing 4, and one end supported by the cap 40 and housed in the housing 4. A sub-cylinder 41, a valve case 5 fixed in the sub-cylinder 41, and a solenoid valve V provided on the cap 40 side of the valve case 5 in the sub-cylinder 41 are provided.

Further, in the tubular gap formed between the housing 4 and the sub-cylinder 41, the extension side gap C2 that leads the gap to the extension side opening 11a (FIG. 1) and the compression side gap that leads to the compression side opening 11b (FIG. 1) A low-pressure priority valve 6 is provided which is partitioned from the C3 and connects the low-pressure side of the extension-side gap C2 and the compression-side gap C3 to the tank T (FIG. 1). As described above, the extension side opening 11a leading to the extension side gap C2 is communicated with the extension side chamber L1, and the compression side opening 11b communicating with the compression side gap C3 is communicated with the compression side chamber L2. Therefore, it can be said that the low pressure priority valve 6 connects the low pressure side of the extension side chamber L1 and the compression side chamber L2 to the tank T.

Further, in the present embodiment, the central axis Y of the damping force adjusting unit E passing through the center of the housing 4 is a straight line orthogonal to the central axis X of the shock absorber main body D passing through the center of the piston rod 3 shown in FIG. It is arranged along Z. Hereinafter, for convenience of explanation, the left and right sides of FIG. 2 of the damping force adjusting unit E are simply referred to as “left” and “right”, but the direction in which the damping force adjusting unit E is attached can be appropriately changed. For example, the damping force adjusting unit E may be arranged so that the central axis Y extends in the vehicle width (left and right) direction of the vehicle, or may be arranged so as to extend in the front-rear direction.

Further, in the present embodiment, the housing 4 of the damping force adjusting portion E is integrally molded with the end cap 11 that closes the upper end of the outer shell 10 and the bracket 12 on the vehicle body side. The term "integral molding" as used herein means that a plurality of separately molded members are not bonded or joined, but a plurality of members are joined at the same time as molding to be integrated.

Next, as shown in FIG. 2, the inside of the sub-cylinder 41 housed in the housing 4 is the first chamber L3 on the left side (cap 40 side) and the second chamber on the right side (anti-cap side) by the valve case 5. It is partitioned into L4. Then, the valve case 5 is formed with an extension side soft passage 5a and a compression side soft passage 5b that communicate the first chamber L3 and the second chamber L4, and also passes through the extension side soft passage 5a or the compression side soft passage 5b. A soft side damping element FS that provides resistance to the flow of liquid moving between the first chamber L3 and the second chamber L4 is attached.

Further, a lateral hole 41a that opens in the extension side gap C2 is formed on the left side of the valve case 5 of the sub-cylinder 41, and the solenoid valve V is provided in the middle of the passage connecting the lateral hole 41a and the first chamber L3. It is provided. As described above, the extension side gap C2 is communicated with the extension side chamber L1 through the extension side opening 11a of the end cap 11 (FIG. 1). On the other hand, the second chamber L4 is always communicated with the compression side gap C3, and the compression side gap C3 is communicated with the compression side chamber L2 through the compression side opening 11b of the end cap 11 (FIG. 1).

That is, in the present embodiment, the tubular gap C1 formed between the cylinder 1 and the outer shell 10 described above, the extension side gap C2, the lateral hole 41a, the first chamber L3, the second chamber L4, and the compression side gap C3. A bypass path B is formed which bypasses the hard side damping element FH and communicates the extension side chamber L1 and the compression side chamber L2. Then, the solenoid valve V and the soft side damping element FS are provided in series in the middle of the bypass path B. The soft-side damping element FS includes an extension-side soft leaf valve 50 which is a leaf valve that opens and closes the extension-side soft passage 5a, a compression-side soft leaf valve 51 which is a leaf valve that opens and closes the compression-side soft passage 5b, and an orifice 52 ( It is configured to have FIG. 4).

The soft leaf valves 50 and 51 on the extension side and the compression side are thin annular plates made of metal or the like, or a laminated body obtained by stacking the annular plates, and have elasticity. The extension side soft leaf valve 50 is laminated on the right side of the valve case 5 in a state where the outer peripheral side (or inner peripheral side) is allowed to bend, and the extension side soft leaf valve 50 has a first chamber L3. Pressure acts in the direction of bending the outer circumference to the right. The pressure side soft leaf valve 51 is laminated on the left side of the valve case 5 in a state where the outer peripheral side (or inner peripheral side) is allowed to bend, and the pressure side soft leaf valve 51 has the pressure of the second chamber L4. Acts in the direction of bending the outer peripheral portion to the left.

The orifice 52 is formed by a notch provided on the outer peripheral portion of the soft leaf valves 50 and 51 on the extension side and the compression side that are detached and seated on the valve seat of the valve case 5, or a stamp provided on the valve seat. There is. Therefore, it can be said that the orifice 52 is provided in one or both of the extension side soft passage 5a and the compression side soft passage 5b in parallel with the extension side and compression side soft leaf valves 50 and 51.

The pressure in the first chamber L3 rises due to the pressure in the extension side chamber L1 when the solenoid valve V opens the extension side port 7a, which will be described later, when the shock absorber A is extended, and the pressure in the second chamber L4 rises. It becomes higher than the pressure, which causes a differential pressure between the first chamber L3 and the second chamber L4. When the shock absorber A is extended and the solenoid valve V opens the port 7a on the extension side, the piston speed is in the low speed range, and the differential pressure is the valve opening pressure of the soft leaf valve 50 on the extension side. If the amount is less than the above, the liquid flows from the first chamber L3 to the second chamber L4, that is, from the extension side chamber L1 to the compression side chamber L2 through the orifice 52, and resistance is imparted to the flow of the liquid.

Further, when the shock absorber A is extended and the solenoid valve V opens the port 7a on the extension side, the piston speed increases and is in the medium and high speed range, and the differential pressure becomes large and the soft leaf valve on the extension side increases. When the valve opening pressure exceeds 50, the outer peripheral portion of the soft leaf valve 50 on the extension side bends to form a gap between the outer peripheral portion and the valve case 5, and the liquid passes through the gap from the first chamber L3. Along with moving from the second chamber L4, that is, the extension side chamber L1 to the compression side chamber L2, resistance is imparted to the flow of this liquid.

Subsequently, the pressure in the second chamber L4 rises under the pressure of the compression side chamber L2 when the solenoid valve V opens the port 7b on the compression side, which will be described later, when the shock absorber A contracts, and the pressure in the first chamber L4 rises. It becomes higher than the pressure of L3, which causes a differential pressure between the second chamber L4 and the first chamber L3. When the shock absorber A is contracting and the solenoid valve V is opening the port 7b on the compression side, the piston speed is in the low speed range, and the differential pressure satisfies the valve opening pressure of the soft leaf valve 51 on the compression side. If not, the liquid flows through the orifice 52 from the second chamber L4 to the first chamber L3, that is, from the compression side chamber L2 to the extension side chamber L1, and resistance is imparted to the flow of this liquid.

Further, when the shock absorber A is contracted and the solenoid valve V is opening the port 7b on the compression side, the piston speed increases and is in the medium to high speed range, and the differential pressure increases to increase the pressure side soft leaf valve 51. When the valve opening pressure is higher than the valve opening pressure, the outer peripheral portion of the soft leaf valve 51 on the compression side bends to form a gap between the outer peripheral portion and the valve case 5, and the liquid passes through the gap from the second chamber L4 to the first chamber. Along with going from L3, that is, the compression side chamber L2 to the extension side chamber L1, resistance is imparted to the flow of this liquid.

As can be seen from the above, the orifice 52 of the soft side damping element FS and the extension side soft leaf valve 50 resist the flow of liquid from the extension side chamber L1 to the compression side chamber L2 through the bypass path B when the shock absorber A is extended. Acts as a second damping element on the extension side that gives. Further, the orifice 52 of the soft damping element FS and the soft leaf valve 51 on the compression side give resistance to the flow of liquid from the compression side chamber L2 to the extension side chamber L1 on the bypass path B when the shock absorber A contracts. Functions as a secondary damping factor. The resistance due to these first and second damping elements is caused by the orifice 52 when the piston speed is in the low speed range, and the extension side or compression side soft leaf valves 50 and 51 when the piston speed is in the medium and high speed range. caused by.

Further, the soft leaf valve 50 on the extension side of the soft side damping element FS is a valve having a lower valve rigidity (easy to bend) than the hard leaf valve 20 on the extension side of the hard side damping element FH, and the flow rate is the same. , The resistance (pressure loss) given to the flow of liquid is small. Similarly, the soft leaf valve 51 on the compression side of the soft side damping element FS is a valve having a lower valve rigidity (easier to bend) than the hard leaf valve 21 on the compression side of the hard side damping element FH, and when the flow rates are the same, The resistance (pressure loss) given to the flow of liquid is small. In other words, the liquid is more likely to pass through the soft leaf valves 50, 51 than the hard leaf valves 20, 21 under the same conditions. Further, the orifice 52 of the soft side damping element FS is a large diameter orifice having a larger opening area than the orifice 22 of the hard side damping element FH, and when the flow rates are the same, the resistance (pressure loss) given to the liquid flow is increased. small.

Subsequently, the solenoid valve V attaches the tubular holder 7 fixed in the sub-cylinder 41, the spool 8 reciprocally inserted into the holder 7, and the spool 8 in one of the moving directions thereof. It is configured to have a urging spring 80 for urging and a solenoid 9 for applying a thrust in a direction opposite to the urging force of the urging spring 80 to the spool 8. The holder 7 is formed with ports 7a and 7b on the extension side and the compression side, and the opening degree of each port 7a and 7b can be adjusted by changing the position of the spool 8 in the holder 7. There is.

More specifically, the holder 7 has the central axis Y of the housing 4 in a state where one end in the axial direction is directed to the left side (cap 40 side) and the other end is directed to the right side (valve case 5 side) in the sub cylinder 41. It is arranged along. The extension side and compression side ports 7a and 7b each penetrate the wall thickness of the holder 7 in the radial direction and are arranged at predetermined intervals in the axial direction.

An annular extension-side valve seat 70 and a compression-side valve seat 72 are provided between the holder 7 and the housing 4 on both sides of the lateral hole 41a between the extension-side and compression-side ports 7a and 7b. There is. The extension side valve seat 70 is equipped with an extension side check valve 71 that allows only one-way flow of liquid from the extension side gap C2 through the lateral hole 41a toward the extension side port 7a. On the other hand, the compression side valve seat 72 is equipped with a compression side check valve 73 that allows only one-way flow of liquid from the compression side port 7b through the lateral hole 41a toward the extension side gap C2.

The extension side and compression side ports 7a and 7b are individually opened and closed by the spool 8. The spool 8 has a tubular shape and is slidably inserted into the holder 7. A plate 81 is laminated on the left end of the spool 8, and a plunger 9a of a solenoid 9 described later is in contact with the plate 81. On the other hand, the urging spring 80 abuts on the right end of the spool 8, and the urging spring 80 urges the spool 8 to the left side (solenoid 9 side).

Further, the central hole 8a formed in the central portion of the spool 8 communicates with the first chamber L3 via the right end opening of the spool 8. Further, the spool 8 is formed with annular grooves 8b, 8d on the extension side and the compression side along the circumferential direction of the outer circumference thereof at predetermined intervals in the axial direction, and inside and the center hole of each annular groove 8b, 8d. Side holes 8c and 8e that communicate with 8a are formed. As a result, the insides of the annular grooves 8b and 8d are communicated with the first chamber L3 via the side holes 8c and 8e and the central hole 8a.

According to the above configuration, when the spool 8 is located at a position where the extension-side annular groove 8b faces the extension-side port 7a of the holder 7, as shown in FIG. 2, the extension-side port 7a and the first chamber Communication with L3 is allowed, and the flow of liquid from the extension chamber L1 through the extension gap C2, the lateral hole 41a, the extension check valve 71, and the extension port 7a to the first chamber L3 is allowed.

Further, when the spool 8 shown in FIG. 2 moves to the right and the spool 8 is located at a position where the pressure-side annular groove 8d faces the compression-side port 7b of the holder 7, the pressure-side port 7b and the first Communication with the chamber L3 is allowed, and the flow of liquid from the first chamber L3 through the compression side port 7b, the compression side check valve 73, the lateral hole 41a, and the extension side gap C2 to the extension side chamber L1 is allowed.

The state in which the annular groove and the port face each other here means a state in which the annular groove and the port overlap in a radial direction, and the opening degree of each port changes according to the amount of overlap. For example, when the overlapping amount of the annular groove and the corresponding port increases, the opening degree of the port increases, and conversely, when the overlapping amount of the annular groove and the corresponding port decreases, the opening degree of the port decreases. Further, when the spool moves to a position where the annular groove and the corresponding port do not completely overlap, the port is blocked.

Further, in the spool 8 of the present embodiment, as shown in FIG. 2, when the opening degree of the port 7a on the extension side becomes the maximum (fully open), the opening degree of the port 7b on the compression side becomes the minimum (fully closed). As the opening degree of the port 7a on the extension side is decreased, the opening degree of the port 7b on the compression side increases, and when the opening degree of the port 7b on the compression side becomes the maximum (fully open), the port 7a on the extension side The opening is set to the minimum (fully closed).

The solenoid 9 that applies thrust to the spool 8 and drives the spool 8 is held by the cap 40, and although detailed illustration is omitted, a tubular stator including a coil and a movably inserted into the stator. It has a tubular movable iron core to be formed, and a plunger 9a which is attached to the inner circumference of the movable iron core and whose tip abuts on the plate 81. The harness 90 that supplies electric power to the solenoid 9 projects outward from the cap 40 and is connected to a power source.

Then, when the solenoid 9 is energized through the harness 90, the movable iron core is pulled to the right, the plunger 9a moves to the right, and the spool 8 moves to the right against the urging force of the urging spring 80. Then, the compression side annular groove 8d and the compression side port 7b face each other to open the compression side port 7b, and the amount of overlap between the extension side annular groove 8b and the extension side port 7a is reduced to reduce the extension side port. 7a closes.

That is, the urging spring 80 urges the spool 8 in the direction of opening the port 7a on the extension side and closing the port 7b on the compression side. On the other hand, the solenoid 9 applies a thrust in the direction opposite to the urging force of the urging spring 80, that is, a thrust in the direction of closing the port 7a on the extension side and opening the port 7b on the compression side to the spool 8.

Therefore, the relationship between the opening degree of the port 7a on the extension side and the energization amount to the solenoid 9 becomes a negative proportional relationship having a negative proportionality constant, and the opening degree of the port 7a on the extension side increases as the energization amount increases from zero. Becomes smaller. The extension-side port 7a is one-way by the extension-side check valve 71, and the liquid flows from the extension-side gap C2 toward the first chamber L3. Therefore, when the opening degree of the port 7a on the extension side is adjusted, the flow rates of the soft leaf valve 50 and the orifice 52 on the extension side downstream thereof are adjusted in magnitude.

On the other hand, the relationship between the opening degree of the port 7b on the compression side and the amount of energization to the solenoid 9 is a proportional relationship having a positive proportionality constant, and the opening degree of the port 7b on the compression side increases as the amount of energization increases from zero. The pressure side port 7b is one-way by the pressure side check valve 73, and the liquid flows from the first chamber L3 toward the extension side gap C2. Therefore, when the opening degree of the compression side port 7b is adjusted, the flow rates of the compression side soft leaf valve 51 and the orifice 52 located upstream thereof are adjusted in magnitude.

That is, when the opening degree of the port 7a on the extension side of the solenoid valve V is increased or decreased, the opening area of the bypass path B when the liquid passes through the soft side damping element FS and goes through the bypass path B from the extension side chamber L1 to the compression side chamber L2. Is adjusted. Similarly, when the opening degree of the port 7b on the compression side of the solenoid valve V is increased or decreased, the opening area of the bypass path B when the bypass path B is directed from the compression side chamber L2 to the extension side chamber L1 through the soft side damping element FS is adjusted. Will be done.

Next, the low-pressure priority valve 6 provided on the outer circumference of the sub-cylinder 41 is a shuttle valve, and as shown in FIG. 3, take off and seat at both ends of the annular valve seat portion 42 provided on the outer circumference of the sub-cylinder 41. Includes two annular valve bodies 60, 61 and a connecting portion 62 that connects the two valve bodies 60, 61 and is arranged with a gap C4 between the two valve bodies 60, 61 and the housing 4. The low-pressure priority valve 6 is provided on the outer periphery of the sub-cylinder 41 while the two valve bodies 60 and 61 are in sliding contact with the inner circumference of the housing 4 and the connecting portion 62 is in sliding contact with the outer circumference of the valve seat portion 42. It is designed to reciprocate between the two stoppers 43 and 44.

Notches 6a, 6b, 6c, and 6d are formed at the portions of the valve bodies 60 and 61 facing the corresponding stoppers 43 and 44 and at the ends of the connecting portions 62 on both valve bodies 60 and 61, respectively. Has been done. Then, when one valve body 60 (61) is seated on the valve seat portion 42, the other valve body 61 (60) is separated from the valve seat portion 42 to form a gap. Then, through the notch 6c (6a) of the other valve body 61 (60), the above gap, and the notch 6d (6b) of the connecting portion 62, the extension side gap C2 or the compression side gap C3 and the outer circumference of the connecting portion 62 It communicates with the gap C4 that can be formed.

The gap C4 is connected to the tank T. As shown in FIG. 1, the inside of the tank T is divided into a liquid chamber L5 and a gas chamber G by a bladder 18. In the present embodiment, the gas chamber G is filled with high-pressure gas, the liquid chamber L5 is pressurized by the pressure of the gas chamber G, and the pressure acts on the cylinder 1 through the damping force adjusting unit E. It has become.

According to the above configuration, when the extension side chamber L1 is pressurized by the piston 2 when the shock absorber A is extended and the pressure of the extension side chamber L1 is received to increase the pressure of the extension side gap C2, as shown in FIG. Upon receiving the pressure, the low pressure priority valve 6 moves to the right side, and the valve body 60 on the left side is seated on the valve seat portion 42. Then, a gap is formed between the valve body 61 on the right side and the valve seat portion 42, and the tank T and the compression side gap C3 are communicated with each other. Since the compression side gap C3 is communicated with the compression side chamber L2, the pressure in the compression side chamber L2 becomes substantially the same as the pressure in the tank T (tank pressure) when the shock absorber A is extended.

On the contrary, when the pressure side chamber L2 is pressurized by the piston 2 when the shock absorber A contracts, and the pressure of the pressure side chamber L2 increases and the pressure of the pressure side gap C3 increases, the pressure is received and the low pressure priority valve 6 moves to the left side. The valve body 61 on the right side moves and is seated on the valve seat portion 42. Then, a gap is formed between the valve body 60 on the left side and the valve seat portion 42, and the tank T and the extension side gap C2 are communicated with each other. Since the extension side gap C2 is communicated with the extension side chamber L1, the pressure in the extension side chamber L1 becomes substantially the same as the pressure in the tank T (tank pressure) when the shock absorber A contracts.

The configuration of the tank T can be changed as appropriate. For example, the liquid chamber L5 and the gas chamber G may be partitioned by a free piston, and the free piston may be urged toward the liquid chamber side by a spring such as a coil spring or an air spring. Further, the liquid chamber L5 does not necessarily have to be pressurized as long as the pressure inside the cylinder 1 does not become negative.

Summarizing the above, as shown in FIG. 4, the shock absorber A according to the present embodiment is slidably inserted into the cylinder 1 and the cylinder 1, and the inside of the cylinder 1 is the extension side chamber L1 and the compression side chamber L2. It is connected to the low pressure side of the extension side chamber L1 and the compression side chamber L2 by a piston 2 which is divided into two parts, a piston rod 3 whose tip is connected to the piston 2 and whose end protrudes to the outside of the cylinder 1, and a low pressure priority valve 6. It is equipped with a cylinder T. Further, the shock absorber A is provided with an extension side passage 2a, a compression side passage 2b, and a bypass passage B as a passage for communicating the extension side chamber L1 and the compression side chamber L2.

The extension side passage 2a and the compression side passage 2b are provided with an extension side hard leaf valve 20 and a compression side hard leaf valve 21 that open and close each of them, and one or both of the extension side passage 2a and the compression side passage 2b are provided with an extension side. An orifice 22 is provided in parallel with the hard leaf valves 20 and 21 on the compression side. A hard leaf valve 20 on the extension side, a hard leaf valve 21 on the compression side, and an orifice 22 are configured to form a hard side damping element FH that resists the flow of liquid.

On the other hand, the bypass path B branches into an extension side soft passage 5a and a compression side soft passage 5b on the way. The extension side soft passage 5a and the compression side soft passage 5b are provided with an extension side soft leaf valve 50 and a compression side soft leaf valve 51 that open and close each of them, and one or both of the extension side soft passage 5a and the compression side soft passage 5b are provided. An orifice 52 is provided in parallel with the soft leaf valves 50 and 51 on the extension side and the compression side.

The orifice 52 is a large-diameter orifice having a larger opening area than the orifice 22. Further, the soft leaf valves 50 and 51 are leaf valves having lower valve rigidity than the hard leaf valves 20 and 21. A soft leaf valve 50 on the extension side, a soft leaf valve 51 on the compression side, and an orifice 52 are provided to form a soft side damping element FS that reduces resistance to the flow of liquid.

Further, the bypass path B is provided with a solenoid valve V in series with the soft side damping element FS. The solenoid valve V fully opens the port 7a on the extension side that allows one-way flow of the liquid from the extension side chamber L1 to the compression side chamber L2 when the electricity is not supplied, and also allows the liquid from the compression side chamber L2 to the extension side chamber L1. The compression side port 7b that allows unidirectional flow is set to be fully closed. Then, the opening degree of the port 7a on the extension side becomes smaller as the amount of energization increases, so that the opening area of the bypass path B when the liquid goes from the extension side chamber L1 to the compression side chamber L2 becomes smaller. On the other hand, the opening degree of the port 7b on the compression side increases as the amount of energization increases, so that the opening area of the bypass path B when the liquid flows from the compression side chamber L2 to the extension side chamber L1 increases.

The operation of the shock absorber A according to the embodiment of the present invention will be described below.

When the shock absorber A is extended, the piston rod 3 retracts from the cylinder 1 and the piston 2 compresses the extension side chamber L1. Then, the liquid in the extension side chamber L1 moves to the compression side chamber L2 through the hard side damping element FH or the soft side damping element FS of the bypass path B. A resistance is imparted to the flow of the liquid by the hard side damping element FH or the soft side damping element FS, and an extension side damping force due to the resistance is generated. Then, when the shock absorber A is extended, the distribution ratio of the liquid passing through the hard side damping element FH and the soft side damping element FS changes according to the amount of energization to the solenoid valve V.

Specifically, when the shock absorber A is extended, the liquid is the extension-side hard leaf valve 20 or orifice 22 that constitutes the extension-side first damping element of the hard-side damping element FH, or the soft-side damping element. It passes through the extension-side soft leaf valve 50 or orifice 52 that constitutes the second extension-side damping element of the FS. As described above, the first and second damping elements on the extension side are configured to have orifices 22 and 52, respectively, and a hard leaf valve 20 or a soft leaf valve 50 which are leaf valves parallel thereto. .. Therefore, the damping force characteristic on the extension side becomes an orifice characteristic proportional to the square of the piston speed peculiar to the orifice when the piston speed is in the low speed range, and the leaf valve when the piston speed is in the medium and high speed range. The valve characteristics are proportional to the unique piston speed.

Then, when the amount of current supplied to the solenoid valve V is increased to reduce the opening degree of the extension side port 7a, the proportion of the liquid passing through the extension side damping element of the soft side damping element FS decreases and the hardware The proportion of liquid passing through the damping element on the extension side of the side damping element FH increases. Since the orifice 52, which is the damping element on the extension side of the soft side damping element FS, is a large-diameter orifice having a larger opening area than the orifice 22, which is the damping element on the extension side of the hard side damping element FH, the soft side damping element FS. As the proportion of liquid toward the side decreases, the damping coefficient increases in both the low speed range and the medium and high speed range, and the extension side damping force generated with respect to the piston speed increases. Then, when the amount of current supplied to the solenoid valve V is maximized, the port 7a on the extension side is closed and the total flow rate passes through the attenuation element on the extension side of the hard side attenuation element FH. Then, the damping coefficient becomes maximum, and the extension side damping force generated with respect to the piston speed becomes maximum.

On the contrary, when the amount of current supplied to the solenoid valve V is reduced and the opening degree of the extension side port 7a is increased, the liquid passing through the extension side damping element of the soft side damping element FS is increased. As the ratio increases, the ratio of the liquid passing through the extension side damping element of the hard side damping element FH decreases. Then, the damping coefficient becomes small in both the low speed region and the medium / high speed region, and the extension side damping force generated with respect to the piston speed becomes small. Then, when the energization of the solenoid valve V is cut off, the port 7a on the extension side is fully opened. Then, the damping coefficient becomes the minimum, and the extension side damping force generated with respect to the piston speed becomes the minimum.

In this way, when the distribution ratio of the liquid passing through the first and second damping elements on the extension side of the hard side damping element FH and the soft side damping element FS is changed by the solenoid valve V, the damping coefficient becomes large or small, as shown in FIG. As shown, the slope of the characteristic line indicating the damping force characteristic on the extension side changes. Then, the extension side damping force is adjusted between the hard mode in which the inclination of the characteristic line is maximized to increase the damping force generated and the soft mode in which the inclination is minimized to decrease the damping force generated.

In the soft mode, the slope of the characteristic line showing the damping force characteristic becomes small in both the low speed range and the medium / high speed range, and in the hard mode, the slope of the characteristic line showing the damping force characteristic becomes small in the low speed range and the medium / high speed range. Both grow larger. Therefore, the change in the damping force characteristic from the orifice characteristic to the valve characteristic is gradual in any mode.

Further, the damping element on the extension side of the soft damping element FS has a soft leaf valve 50, which is a leaf valve having low valve rigidity, in parallel with the orifice 52. For this reason, a hard leaf valve with high valve rigidity and high valve opening pressure is used as the leaf valve that constitutes the extension side damping element of the hard side damping element FH, and the adjustment range in the direction of increasing the extension side damping force is adjusted. Even if it is increased, the damping force in the soft mode does not become excessive.

Further, when the shock absorber A is extended, the pressure in the extension side chamber L1 becomes higher than the pressure in the compression side chamber L2, and the pressure side chamber L2 on the low pressure side is communicated with the tank T by the low pressure priority valve 6. Therefore, when the shock absorber A is extended, the pressure in the compression side chamber L2 becomes the tank pressure, and the liquid corresponding to 3 volumes of the piston rod discharged from the cylinder 1 is supplied from the tank T to the compression side chamber L2.

On the contrary, when the shock absorber A contracts, the piston rod 3 enters the cylinder 1 and the piston 2 compresses the compression side chamber L2. Then, the liquid in the compression side chamber L2 moves to the extension side chamber L1 through the hard side damping element FH or the soft side damping element FS of the bypass path B. A resistance is imparted to the flow of the liquid by the hard side damping element FH or the soft side damping element FS, and a compression side damping force due to the resistance is generated. Then, even when the shock absorber A contracts, the distribution ratio of the liquid passing through the hard side damping element FH and the soft side damping element FS changes according to the amount of energization to the solenoid valve V.

Specifically, when the shock absorber A contracts, the liquid of the compression side hard leaf valve 21 or orifice 22 or the soft side damping element FS constituting the first damping element on the compression side of the hard side damping element FH. It passes through the compression side soft leaf valve 51 or orifice 52 that constitutes the compression side second damping element. As described above, the first and second damping elements on the compression side include the orifices 22 and 52, and the hard leaf valve 21 or the soft leaf valve 51 which is a leaf valve parallel to the orifices 22 and 52. Therefore, the damping force characteristic on the compression side becomes an orifice characteristic proportional to the square of the piston speed peculiar to the orifice when the piston speed is in the low speed range, and is peculiar to the leaf valve when the piston speed is in the medium and high speed range. The valve characteristics are proportional to the piston speed of.

Then, when the amount of current supplied to the solenoid valve V is increased to increase the opening degree of the compression side port 7b, the proportion of the liquid passing through the compression side damping element of the soft side damping element FS increases and the hard side attenuation increases. The proportion of liquid passing through the damping element on the compression side of the element FH is reduced. Since the orifice 52, which is the damping element on the compression side of the soft side damping element FS, is a large-diameter orifice having a larger opening area than the orifice 22 which is the damping element on the compression side of the hard side damping element FH, it is moved to the soft side damping element FS side. As the proportion of the heading form increases, the damping coefficient becomes smaller in both the low speed range and the medium and high speed range, and the compression side damping force generated with respect to the piston speed becomes small. Then, when the amount of current supplied to the solenoid valve V is maximized, the port 7b on the compression side is fully opened. Then, the damping coefficient becomes the minimum, and the compression side damping force generated with respect to the piston speed becomes the minimum.

On the contrary, when the amount of current supplied to the solenoid valve V is reduced to reduce the opening degree of the compression side port 7b, the proportion of the liquid passing through the compression side damping element of the soft side damping element FS is increased. As it decreases, the proportion of liquid passing through the compression side damping element of the hard side damping element FH increases. Then, the damping coefficient becomes large in both the low speed region and the medium / high speed region, and the compression side damping force generated with respect to the piston speed becomes large. Then, when the energization of the solenoid valve V is cut off, the port 7b on the compression side is closed and the entire flow rate passes through the damping element FH on the hard side. Then, the damping coefficient becomes maximum, and the compression side damping force generated with respect to the piston speed becomes maximum.

In this way, when the distribution ratio of the liquid passing through the first and second damping elements on the compression side of the hard side damping element FH and the soft side damping element FS is changed by the solenoid valve V, the damping coefficient becomes large or small, and the damping on the extension side Similar to the force, the slope of the characteristic line indicating the damping force characteristic on the compression side changes. Then, the compression side damping force is adjusted between the hard mode in which the inclination of the characteristic line is maximized to increase the damping force generated and the soft mode in which the inclination is minimized to decrease the damping force generated.

In addition, as in the case of expansion, the slope of the characteristic line showing damping force characteristics becomes smaller in both the low speed range and the medium and high speed range in the soft mode, and in both the low speed range and the medium and high speed range in the hard mode. Since it becomes large, the change in the damping force characteristic from the orifice characteristic to the valve characteristic is gradual in any mode. Further, since the compression side damping element of the soft side damping element FS also has the soft leaf valve 51 which is a leaf valve having low valve rigidity in parallel with the orifice 52, the compression side damping element of the hard side damping element FH can be used. Even if a hard leaf valve with high valve rigidity and high valve opening pressure is used as the leaf valve to be configured, the damping force in the soft mode does not become excessive.

The action and effect of the shock absorber A according to the embodiment of the present invention will be described below.

The shock absorber A according to the present embodiment includes a cylinder 1, a piston 2 that is movably inserted into the cylinder 1 in the axial direction and divides the inside of the cylinder 1 into an extension side chamber L1 and a compression side chamber L2, and this piston. It includes a piston rod 3 which is connected to 2 and one end of which protrudes to the outside of the cylinder 1, and a tank T which is connected to the low pressure side of the extension side chamber L1 and the compression side chamber L2 by a low pressure priority valve 6.

Further, the shock absorber A communicates with the hard side damping element FH that gives resistance to the flow of the liquid moving between the extension side chamber L1 and the compression side chamber L2, and the extension side chamber L1 and the compression side chamber L2 by bypassing the hard side damping element FH. It is provided with a solenoid valve V capable of changing the opening area of the bypass path B, and a soft side damping element FS provided in series with the solenoid valve V in the bypass path B. The hard-side damping element FH is configured to have an orifice 22 and hard leaf valves 20 and 21 on the extension side and the compression side, which are leaf valves provided in parallel with the orifice 22. On the other hand, the soft side damping element FS is configured to have an orifice (large diameter orifice) 52 having an opening area larger than that of the orifice 22.

According to the above configuration, the damping force generated when the shock absorber A expands and contracts becomes the orifice characteristic peculiar to the orifice when the piston speed is in the low speed range, and when the piston speed is in the medium and high speed range, it becomes the orifice characteristic. The valve characteristics are peculiar to leaf valves. Then, if the opening area of the bypass path B is changed by the solenoid valve V, among the liquids that move between the extension side chamber L1 and the compression side chamber L2 when the shock absorber A expands and contracts, the hard side damping element FH and the soft side damping element FH Since the distribution ratio of the flow rate of the liquid passing through the FS changes, both the damping coefficient when the piston speed is in the low speed range and the damping coefficient when the piston speed is in the medium and high speed range can be freely set, and the piston speed is medium and high speed. The adjustment range of the damping force when it is in the range can be increased.

Further, in the soft mode in which the opening area of the bypass path B is changed to increase the distribution ratio of the liquid toward the soft side damping element FS, the damping coefficient when the piston speed is in the low speed range and the damping coefficient when the piston speed is in the medium high speed range. Both damping coefficients are smaller. On the other hand, in the hard mode in which the distribution ratio of the liquid toward the soft damping element FS is reduced, both the damping coefficient when the piston speed is in the low speed range and the damping coefficient when the piston speed is in the medium and high speed range are large. Therefore, when the damping force characteristic changes from the orifice characteristic in the low speed range to the valve characteristic in the medium and high speed range, the change in the slope of the characteristic line becomes gentle in any mode. As a result, when the shock absorber A according to the present embodiment is mounted on the vehicle, the discomfort caused by the change in inclination can be reduced and the riding comfort of the vehicle can be improved.

Further, in the shock absorber A of the present embodiment, the soft side damping element is the orifice (large diameter orifice) 52 and the extension side and compression side soft leaf valves 50, 51 which are leaf valves provided in parallel with the orifice 52. It is configured to have and. In this way, if a leaf valve is also provided on the soft side damping element FS, the hard leaf valves 20 and 21, which are the leaf valves of the hard side damping element FH, have high valve rigidity and are soft even if the valve opening pressure is high. The damping force in the mode does not become excessive. That is, according to the above configuration, a valve having high valve rigidity can be adopted as the hard leaf valves 20 and 21 which are the leaf valves of the hard side damping element. By doing so, the adjustment range of the damping force increases in the direction of increasing the damping force, so that the adjustment range of the damping force when the piston speed is in the medium-high speed range can be further increased.

Further, in the present embodiment, as the leaf valve of the hard side damping element FH, the extension side hard leaf valve 20 that gives resistance to the flow of the liquid from the extension side chamber L1 to the compression side chamber L2, and the extension side chamber L2 to the extension side chamber L1 A hard leaf valve 21 on the compression side that resists the flow of liquid toward is provided. Further, as the leaf valve of the soft side damping element FS, the bypass path B is extended from the extension side chamber L1 to the extension side soft leaf valve 50 that resists the flow of the liquid toward the compression side chamber L2, and the bypass path B is extended from the compression side chamber L2. A soft leaf valve 51 on the compression side that resists the flow of liquid toward the concubine L1 is provided. As a result, the adjustment range of the damping force increases in the direction of increasing the damping force both during expansion and contraction of the shock absorber A, so that the damping force on both sides of the extension when the piston speed is in the medium-high speed range The adjustment range can be further increased.

Further, in the present embodiment, the solenoid valve V is movably inserted into the tubular holder 7 in which the extension side and compression side ports 7a and 7b connected to the bypass path B are formed, and the holder 7. A spool 8 capable of opening and closing ports 7a and 7b on the extension side and the compression side, an urging spring 80 for urging the spool 8 in one of the moving directions of the spool 8, and a direction opposite to the urging force of the urging spring 80. It has a solenoid 9 that applies the thrust of the above to the spool 8.

Here, for example, like the solenoid valve described in Japanese Patent Application Laid-Open No. 2010-7758, a needle valve that can reciprocate as a valve body is provided, and the gap formed between the tip of the needle valve and the valve seat is large or small. When changing the opening degree, it is necessary to increase the stroke amount of the valve body in order to increase the adjustment range of the opening degree, but such a case may not be possible.

Specifically, when the stroke amount of the needle valve is increased, the movable space of the needle valve becomes large and it becomes difficult to secure the accommodation space. Further, in order to increase the stroke amount of the needle valve, if it is attempted to increase the stroke amount of the plunger of the solenoid, it is necessary to change the design of the solenoid, which is complicated. Furthermore, if an attempt is made to increase the stroke amount of the needle valve without changing the design of the solenoid, parts for increasing the movement amount of the needle valve with respect to the movement amount of the plunger are required, and the number of parts increases and the accommodation space increases. It becomes difficult to secure.

On the other hand, in the solenoid valve V of the present embodiment, the spool 8 reciprocally inserted into the tubular holder 7 opens and closes the extension side and compression side ports 7a and 7b formed in the holder 7. As a result, the solenoid valve V opens and closes. Therefore, if a plurality of the ports 7a and 7b are formed in the circumferential direction of the holder 7 or the shape is long in the circumferential direction, the solenoid valve V does not need to increase the stroke amount of the spool 8 which is the valve body of the solenoid valve V. The opening degree of the valve V can be increased. Therefore, the adjustment range of the opening degree of the solenoid valve V can be increased, and the adjustment range of the damping force can be easily increased.

Further, in the present embodiment, as the ports of the solenoid valve V, the extension side port 7a where the unidirectional flow of the liquid from the extension side chamber L1 to the compression side chamber L2 is allowed, and the liquid from the compression side chamber L2 to the extension side chamber L1. A port 7b on the compression side that allows unidirectional flow is provided. The solenoid valve V of the present embodiment is set so that the opening degree of the port 7b on the compression side increases and the opening degree of the port 7a on the extension side decreases as the amount of energization increases. Therefore, if the extension side damping force is adjusted to be large, the compression side damping force is automatically reduced, and the vehicle height can be guided to be lowered. On the contrary, if the compression side damping force is adjusted to be large, the extension side damping force is automatically reduced, and the vehicle can be guided in the direction of increasing the vehicle height.

However, as the amount of energization to the solenoid valve V is increased from zero, the extension side damping force may be increased and the compression side damping force may be decreased. In this case, all the ports 7a on the extension side are filled when the solenoid valve V is not energized. For closing, the ports 7a and 7b or the annular grooves 8b and 8d for opening the ports 7a and 7b may be arranged so as to fully open the port 7b on the compression side. Further, the damping force on both sides of the expansion may be increased as the amount of electricity supplied to the solenoid valve V is increased.

In such a case, as in the solenoid valve V1 shown in FIG. 6, the port formed in the holder may be a port 7c that allows bidirectional flow of liquid. According to the configuration, the extension side valve seat 70, the compression side valve seat 72, the extension side check valve 71, and the compression side check valve 73 can be omitted, so that the configuration of the solenoid valve V1 can be simplified and miniaturized. The solenoid valve V1 shown in FIG. 6 is set so that the opening degree of the port 7c increases as the amount of energization increases. However, the solenoid valve V1 is set so as to increase the amount of energization. The opening degree of the port 7c may be set to be small.

Further, as described above, when the solenoid valves V and V1 having the holder 7, the spool 8, the urging spring 80, and the solenoid 9 are used, the port and the annular groove for opening and closing the port are used. The relationship between the opening degree of the solenoid valve and the amount of energization can be set according to the positional relationship of. Therefore, according to the above configuration, the degree of freedom in setting the relationship between the opening degree of the solenoid valve and the amount of energization can be extremely increased.

In the shock absorbers A and A1 shown in FIGS. 1 and 6, the damping forces on both sides of the extension are exerted, and the damping forces on both sides of the extension can be adjusted by the solenoid valves V and V1. However, one of the extension side and compression side hard leaf valves 20 and 21 of the hard side damping element FH and one or both of the extension side and compression side soft leaf valves 50 and 51 of the soft side damping element FS may be omitted. , The shock absorbers A and A1 can be used as a one-sided shock absorber that exerts a damping force only at the time of extension or contraction, or the damping force of either the extension side or the compression side can be used by the solenoid valves V and V1. You may adjust it.

Further, in the present embodiment, the spool 8 and the low pressure priority valve 6 move along the central axis Y of the bottomed tubular housing 4. Since the housing 4 is arranged so that its central axis Y is along a straight line Z (FIG. 1) orthogonal to the central axis X passing through the center of the piston rod 3, the spool 8 and the low pressure priority valve 6 are aligned with the straight line Z. It can be said that it moves along.

According to the above configuration, the spool 8 and the low pressure priority valve 6 move in a direction orthogonal to the expansion / contraction direction of the shock absorber A, and the moving direction does not match the vibration direction of the vehicle. Therefore, it is not necessary to vibrate the spool 8 and the low pressure priority valve 6 in the moving direction due to vibration during vehicle travel. However, the moving directions of the spool 8 and the low pressure priority valve 6 are not necessarily limited to this.

Further, the shock absorber A of the present embodiment includes a housing 4 and a sub-cylinder 41 provided in the housing 4 and accommodating the soft side damping element FS inside. A low-pressure priority valve 6 is provided between the housing 4 and the sub-cylinder 41.

According to the above configuration, it is possible to prevent the housing 4 accommodating the soft side damping element FS, the solenoid valve V, and the low pressure priority valve 6 from becoming long in the axial direction. Therefore, even if the housing 4 is arranged so that the moving directions of the spool 8 and the low pressure priority valve 6 do not match the vibration direction of the vehicle, the left and right widths of the shock absorber A in FIG. 1 are not bulky, and the vehicle of the shock absorber A Can be mounted on the vehicle well.

Further, in the present embodiment, the housing 4 is integrated with the cylinder 1. The state in which the cylinder 1 and the housing 4 are integrated here means that the housing 4 is fixed so as not to move freely with respect to the cylinder 1 when the shock absorber A is handled alone, and one of them is used. A state in which it can be handled like an (integral) member.

According to the above configuration, the inside of the housing 4 and the inside of the cylinder 1 can be communicated with each other by utilizing the holes formed in the portion connecting the housing 4 and the cylinder 1 such as the end cap 11. Therefore, it is not necessary to connect the housing 4 and the cylinder 1 with a hose, and it is possible to prevent an unintended damping force from being generated due to the resistance when the liquid passes through the hose. Furthermore, since the hose can be omitted, the cost can be reduced.

However, the mounting method of the damping force adjusting portion including the housing 4 can be changed as appropriate. For example, the housing 4 and the cylinder 1 may be connected by a hose. Further, in the present embodiment, the housing 4 and the tank T are connected by a hose, but the tank T and the housing 4 may be integrated. In such a case, the housing 4, the end cap 11, the bracket 12 on the vehicle body side, and the tank T may be integrally molded.

Although the preferred embodiments of the present invention have been described in detail above, modifications, modifications, and changes can be made as long as they do not deviate from the claims.

A, A1 ... shock absorber, B ... bypass path, L1 ... extension side chamber, L2 ... compression side chamber, FH ... hard side damping element, FS ... soft side damping element, T. ... Tank, V, V1 ... Solenoid valve, X ... Center line, Z ... Straight line, 1 ... Cylinder, 2 ... Piston, 3 ... Piston rod, 4 ... Housing 5, 5a ... extension side soft passage, 5b ... compression side soft passage, 6 ... low pressure priority valve, 7 ... holder, 7a, 7b, 7c ... port, 8 ... spool , 9 ... solenoid, 20 ... extension side hard leaf valve (leaf valve), 21 ... compression side hard leaf valve (leaf valve), 22 ... orifice, 41 ... sub cylinder, 50 ... extension side soft leaf valve (leaf valve), 51 ... compression side soft leaf valve (leaf valve), 52 ... orifice (large diameter orifice), 80 ... urging spring

Claims (9)

Cylinder and
A piston that is movably inserted into the cylinder to partition the inside of the cylinder into an extension side chamber and a compression side chamber.
A piston rod that is connected to the piston and one end of which protrudes out of the cylinder.
A hard side damping element that resists the flow of liquid moving between the extension side chamber and the compression side chamber.
A solenoid valve capable of changing the opening area of a bypass path that bypasses the hard side damping element and communicates the extension side chamber and the compression side chamber.
A soft side damping element provided in series with the solenoid valve in the bypass path,
A tank connected to the extension side chamber and the low pressure side of the compression side chamber by a low pressure priority valve is provided.
The hard side damping element is configured to have an orifice and a leaf valve provided in parallel with the orifice.
The soft side damping element is a shock absorber characterized by having a large-diameter orifice having a larger opening area than the orifice. The shock absorber according to claim 1, wherein the soft-side damping element is configured to have a leaf valve provided in parallel with the large-diameter orifice. The solenoid valve is provided in one of a tubular holder in which a port connected to the bypass path is formed, a spool that is movably inserted into the holder and can open and close the port, and a spool in the moving direction. The shock absorber according to claim 1 or 2, further comprising an urging spring that urges the spool and a solenoid that applies a thrust in a direction opposite to the urging force of the urging spring to the spool. As the leaf valve of the hard side damping element, a hard leaf valve on the extension side that gives resistance to the flow of liquid from the extension side chamber to the compression side chamber and a resistance to the flow of liquid from the compression side chamber to the extension side chamber. A hard leaf valve on the pressing side is provided,
As the leaf valve of the soft side damping element, the extension side soft leaf valve that gives resistance to the flow of liquid from the extension side chamber to the compression side chamber in the bypass path, and the extension side chamber in the bypass path from the compression side chamber to the compression side chamber. The shock absorber according to claim 2 or claim 3, wherein a soft leaf valve on the compression side that resists the flow of liquid toward the liquid is provided. The ports include an extension port that allows one-way flow of liquid from the extension chamber to the compression side chamber and a compression side port that allows one-way flow of liquid from the compression side chamber to the extension chamber. Provided,
As the amount of energization to the solenoid valve is increased, the opening degree of one of the extension side port and the compression side port is increased, and the opening degree of the other port is decreased. The shock absorber according to claim 3 or claim 4, which is subordinate to claim 3. The shock absorber according to claim 3, wherein the port is allowed bidirectional flow of liquid, or is dependent on claim 3. Claim 3, claim 5, or claim 5, which is dependent on claim 3, wherein the spool and the low-pressure priority valve move along a straight line orthogonal to a central axis passing through the center of the piston rod. The shock absorber according to 6. With the housing
A sub-cylinder provided in the housing and accommodating the soft side damping element is provided inside.
The shock absorber according to any one of claims 1 to 7, wherein the low-pressure priority valve is provided between the housing and the sub-cylinder. The shock absorber according to claim 8, wherein the housing is integrated with the cylinder.

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