WO2020179682A1

WO2020179682A1 - Shock absorber

Info

Publication number: WO2020179682A1
Application number: PCT/JP2020/008378
Authority: WO
Inventors: 宏一郎粟野; 壮大島内; 隆久望月; 將史植村
Original assignee: Ｋｙｂ株式会社
Priority date: 2019-03-04
Filing date: 2020-02-28
Publication date: 2020-09-10
Also published as: JP2020143682A

Abstract

This shock absorber (A) is provided with a hard-side attenuating element (FH) which imparts a resistance to a flow of a liquid that moves between an expansion side chamber (L1) and a compression side chamber (L2), an electromagnetic valve (V) capable of changing an opening surface area of a bypass path (B) which bypasses the hard-side attenuating element (FH) and provides communication between the expansion side chamber (L1) and the compression side chamber (L2), a soft-side attenuating element (FS) provided in the bypass path (B) in series with the electromagnetic valve (V), and a tank (T) connected to a low-pressure side among the expansion side chamber (L1) and the compression side chamber (L2) by means of a low-pressure priority valve (6), wherein: the hard-side attenuating element (FH) is configured to include orifices (22) and hard leaf valves (20, 21) in parallel therewith; and the soft-side attenuating element (FS) is configured to include orifices (52) having an opening surface area larger than that of the orifices (22).

Description

Buffer

The present invention relates to an improvement of a shock absorber.

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 composed of, for example, an orifice and a leaf valve provided in parallel with this 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 characteristic of the damping force 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).

JP2010-7758A JP2014-156885A

For example, in the shock absorber provided with the needle valve described in JP2010-7758A, when the needle valve is driven to increase the opening area of the bypass passage, the flow rate of the liquid passing through the damping element decreases and the damping force generated decreases. (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 to adjust 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 middle and 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 JP2014-156885A, when the valve opening pressure of the pilot valve is made low and the back pressure of the leaf valve is made small, the valve opening pressure of the leaf valve becomes low and damping occurs. The force becomes smaller (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 controlling the back pressure of the leaf valve and changing its opening pressure, the adjustment range of the damping force can be increased when the piston speed is in the middle and high speed range. 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, the occupant may feel uncomfortable and the ride quality may be deteriorated.

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 capable of changing the opening area of a bypass passage that bypasses the element and connects the expansion side chamber and the compression side chamber, a soft side damping element provided in series with the solenoid valve in the bypass passage, and a low pressure priority valve And a tank connected to the low pressure side of the pressure side chamber. The hard damping element has an orifice and a leaf valve provided in parallel with the orifice, and the soft damping element has a large-diameter orifice having an opening area larger than that of 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 passage is changed by the solenoid valve, the distribution ratio of the flow rate of each of the liquids moving between the expansion side chamber and the compression side chamber that passes through the hard side damping element and the soft side damping element 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 middle and high speed ranges 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 device is mounted on a vehicle, the ride comfort of the vehicle can be improved.

Further, in the above shock absorber, the soft side damping element may be configured to have a leaf valve 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 can be further increased when the piston speed is in the middle-high speed range.

Further, in the above-mentioned shock absorber, a cylindrical holder in which a port where the solenoid valve is connected to the bypass path is formed, a spool which is reciprocally inserted in the holder and which can open and close the port, and a 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. With this configuration, 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 range of the opening area of the bypass passage 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-mentioned shock absorber, as a leaf valve of the damping element on the hard side, a hard leaf valve on the expansion side that gives resistance to the flow of liquid from the expansion side chamber to the compression side chamber and a liquid flow from the compression side chamber to the expansion side chamber are provided. A hard leaf valve on the pressure side that provides resistance is provided, and as a leaf valve for the damping element on the soft side, the soft path valve on the expansion side that provides resistance to the flow of liquid from the expansion side chamber to the pressure side chamber and the bypass path are used as the bypass valve. A soft leaf valve on the pressure side may be provided that provides resistance to the flow of liquid from the pressure side chamber to the expansion side chamber. In this way, it is possible to increase the adjustment range of the damping force on both sides of the extension when the piston speed is in the medium to high speed range.

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 one of the extension side and the compression side is adjusted to have a high damping force, the other damping force is automatically adjusted to be low. The height can be induced to be higher or lower.

Further, in the above 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 above 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. With this configuration, 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 thereof due to the vibration during traveling 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. By doing so, it is possible to prevent the axial length of the housing from increasing.

Also, 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 can be increased when the piston speed is in the middle and high speed range, and the riding comfort when mounted on the vehicle can be improved.

FIG. 1 is a front view in which a shock absorber according to an embodiment of the present invention is partially cut away. FIG. 2 is a partially enlarged vertical sectional view showing an enlarged damping force adjusting portion of the shock absorber according to the embodiment of the present invention. FIG. 3 is a vertical cross-sectional view showing a part of FIG. 2 in an enlarged manner. FIG. 4 is a hydraulic circuit diagram of a shock absorber according to an embodiment of the present invention. FIG. 5 is a damping force characteristic diagram showing the characteristic of the damping force with respect to the piston speed of the shock absorber according to the embodiment of the present invention. FIG. 6 is a hydraulic circuit diagram showing a modified example of the shock absorber according to the embodiment of the present invention. FIG. 7 is a damping force characteristic diagram showing the characteristics of the damping force with respect to the piston speed of the shock absorber provided with the conventional needle valve. FIG. 8 is a damping force characteristic diagram showing the characteristics of the damping force with respect to the piston speed of a shock absorber provided with a conventional pilot valve.

A buffer device according to an embodiment of the present invention will be described below with reference to the drawings. The same reference numerals allotted throughout the several figures refer to 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 upper and lower sides with the shock absorber attached to the vehicle are simply referred to as “upper” and “lower” 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. An axle-side bracket 30 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 wheel is rotatably supported by the swing arm, it can be said that the piston rod 3 is connected to the axle of the rear wheel.

On the other hand, a ridged tubular end cap 11 is screwed around 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 of the vehicle and the rear wheel axle. When the rear wheel vibrates vertically with respect to the vehicle body as 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 main body D 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 an 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 bearing 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 the suspension spring S has one end supported by the outer shell 10 and the other end 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 to elastically support the vehicle body.

The direction in which the shock absorber A is attached is not limited to that shown in the figure, and for example, the top and bottom 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 a coil spring such as an air spring, and the suspension spring S may be omitted depending on the object to which the shock absorber A is attached.

Next, the shock absorber main body D is a double cylinder type, and the cylinder 1 as an inner cylinder is provided inside the outer shell 10. A piston 2 is slidably inserted in the cylinder 1. The piston 2 is connected to the outer periphery of the upper end of the piston rod 3 by a nut 32. 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 (axial direction) in the cylinder 1.

Further, as described above, a capped cylindrical end cap 11 is screwed onto the outer periphery of the upper end of the outer shell 10, and the upper end of the outer shell 10 is closed by this 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.

In this way, the inside of the outer shell 10 is a sealed 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 working oil is formed in the cylinder 1, and the working chamber L is partitioned by the piston 2 into a lower expansion side chamber L1 and an upper compression side chamber L2. ing.

The expansion side chamber L1 here is the one of the two chambers partitioned by the piston that is compressed by the piston 2 when the shock absorber A extends. On the other hand, the pressure side chamber L2 is one 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 and the compression side passage 2b. A hard side damping element FH is attached that resists the flow of liquid moving between them. This hard side damping element FH includes an expansion side hard leaf valve 20 that is a leaf valve that opens and closes the expansion side passage 2a, a compression side hard leaf valve 21 that is a leaf valve that opens and closes the compression side passage 2b, and an orifice 22 (see FIG. 4) and is configured.

The

hard leaf valves

20 and 21 on the expansion side and the compression side are thin annular plates made of metal or the like, or a laminated body in which the annular plates are stacked, 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 is allowed to bend, and the pressure of the extension side chamber L1 is applied to the extension side hard leaf valve 20 so that the outer peripheral portion is upward. Acts in the direction of bending. 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 is allowed to bend, and the pressure of the compression side chamber L2 is applied to the compression side hard leaf valve 21 on the outer peripheral side downward. Acts in the direction of bending.

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 expansion side passage 2a and the compression side passage 2b in parallel with the expansion side and compression side

hard leaf valves

20 and 21.

The expansion side chamber L1 is compressed by the piston 2 when the shock absorber A extends and the internal pressure thereof rises, and becomes higher than the pressure of the compression side chamber L2. On the other hand, the pressure side chamber L2 is compressed by the piston 2 when the shock absorber A contracts and its internal pressure rises, and becomes 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 is expanded and contracted, and the differential pressure is less than the opening pressure of the

hard leaf valves

20 and 21 on the expansion side and the compression side, the liquid expands through the orifice 22. Occasionally, the expansion side chamber L1 moves toward the compression side chamber L2, and when contracting, the compression side chamber L2 moves toward the expansion side chamber L1. The orifice 22 provides resistance to the liquid flow.

Further, when the shock absorber A is extended, the piston speed increases and is in the medium to high speed range, and when 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 medium to 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 hard-leaf valve 20 on the expansion side provide resistance to the flow of liquid from the expansion-side chamber L1 to the compression-side chamber L2 when the shock absorber A extends. 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. Function 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 expansion side or pressure side

hard leaf valves

20, 21 when the piston speed is in the medium and high speed ranges. ..

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 communicates with the damping force adjusting portion E through a hole 10a formed in the upper end portion of the outer shell 10 and an extension side opening 11a formed in the end cap 11. A pressure side opening 11b is formed in the end cap 11, and the pressure side chamber L2 communicates with the damping force adjusting portion E through the pressure side opening 11b.

As shown in FIG. 2, the damping force adjusting portion E is housed in the housing 4 with a bottomed tubular housing 4, a cap 40 that closes an opening of the housing 4, and one end supported by the cap 40. The sub-cylinder 41, the valve case 5 fixed in the sub-cylinder 41, and the electromagnetic 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 for partitioning into C3 and connecting the low-pressure side of the expansion-side clearance C2 and the compression-side clearance 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 expansion 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 portion E passing through the center of the housing 4 is a straight line orthogonal to the central axis X of the shock absorber body D passing through the center of the piston rod 3 shown in FIG. It is arranged along Z. Hereinafter, for convenience of description, the left and right of the damping force adjusting section E in FIG. 2 are simply referred to as “left” and “right”, but the direction in which the damping force adjusting section E is attached can be appropriately changed. For example, the damping force adjusting unit E may be arranged such that the central axis Y extends in the vehicle width (left and right) direction of the vehicle or the longitudinal 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 integral molding mentioned here does not mean that a plurality of members that have been molded separately are bonded or joined, but that a plurality of members are joined together 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. The valve case 5 is formed with an expansion-side soft passage 5a and a compression-side soft passage 5b which communicate the first chamber L3 and the second chamber L4, and through the expansion-side soft passage 5a or the compression-side soft passage 5b. A soft damping element FS is attached that provides resistance to the flow of liquid moving between the first chamber L3 and the second chamber L4.

On the left side of the valve case 5 of the sub-cylinder 41, a lateral hole 41a opening to the expansion side clearance C2 is formed, 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 expansion side gap C2 communicates with the expansion side chamber L1 through the expansion 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 cylindrical gap C1, the expansion side gap C2, the lateral hole 41a, the first chamber L3, the second chamber L4, and the pressure side gap C3 formed between the cylinder 1 and the outer shell 10 are formed. A bypass passage B is formed which bypasses the hard side damping element FH and connects 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 expansion-side soft leaf valve 50 that is a leaf valve that opens and closes the expansion-side soft passage 5a, a compression-side soft leaf valve 51 that 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 in which the annular plates are stacked, 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 is allowed to bend, and the pressure of the first chamber L3 is applied to the outer peripheral portion of the extension side soft leaf valve 50. It acts in the direction of bending 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 is allowed to bend, and the pressure side soft leaf valve 51 has the pressure in the second chamber L4 on the outer peripheral side to the left side. Acts in the direction of bending.

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 expansion side soft passage 5a and the compression side soft passage 5b in parallel with the expansion side and compression side

soft leaf valves

50 and 51.

The pressure in the first chamber L3 rises under the pressure of 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 extension side port 7a, the piston speed is in the low speed range, and the differential pressure is the opening pressure of the extension side soft leaf valve 50. 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 expanded and the solenoid valve V is opening the expansion side port 7a, the piston speed increases and is in the middle-high speed range, and the differential pressure increases and the expansion side soft leaf valve increases. When the valve opening pressure of 50 or more is reached, the outer peripheral portion of the expansion side soft leaf valve 50 bends to form a gap between the outer peripheral portion and the valve case 5, and the liquid passes through the gap and leaves 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 contracted 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. When there is no liquid, the liquid flows from the second chamber L4 to the first chamber L3, that is, from the pressure side chamber L2 to the extension side chamber L1 through the orifice 52, and resistance is imparted to the flow of the liquid.

Further, when the shock absorber A is contracted and the solenoid valve V opens the pressure side port 7b, the piston speed increases and is in the middle and high speed range, and the differential pressure increases and the soft leaf valve 51 on the pressure side increases. When the pressure exceeds the valve opening pressure, the outer peripheral portion of the pressure side soft leaf valve 51 bends to form a gap between the outer peripheral portion and the valve case 5, and the liquid passes through the gap to move 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. It functions as a secondary damping element. The resistance due to the first and second damping elements is caused by the orifice 52 when the piston speed is in the low speed range, and is extended or compressed by the

soft leaf valves

50, 51 when the piston speed is in the medium and high speed ranges. caused by.

Further, the soft leaf valve 50 on the extension side of the soft side damping element FS is a valve having a valve rigidity lower (easy to bend) than the hard leaf valve 20 on the extension side of the hard side damping element FH, and has the same flow rate. , The resistance (pressure loss) applied to the liquid flow 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) applied to the liquid flow is small. In other words, the liquid passes through the

soft leaf valves

50 and 51 more easily than the

hard leaf valves

20 and 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 small.

Subsequently, the solenoid valve V includes a cylindrical holder 7 fixed in the sub-cylinder 41, a spool 8 reciprocally inserted in the holder 7, and a spool 8 attached in one of the moving directions. A biasing spring 80 for biasing and a solenoid 9 for applying a thrust in a direction opposite to the biasing force of the biasing spring 80 to the spool 8 are configured. 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 is arranged such that one end of the holder 7 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, with the central axis Y of the housing 4 being held. It is arranged along. The expansion side and

compression side ports

7a and 7b respectively penetrate through the wall thickness of the holder 7 in the radial direction and are arranged at a predetermined interval 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 expansion side valve seat 70 is equipped with an expansion side check valve 71 that allows only one-way flow of the liquid from the expansion side gap C2 through the lateral hole 41a to the expansion side port 7a. On the other hand, the pressure side valve seat 72 is provided with a pressure side check valve 73 that allows only one-way flow of the liquid from the pressure side port 7b through the lateral hole 41a toward the expansion side gap C2.

The expansion 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, a biasing spring 80 contacts the right end of the spool 8, and the biasing spring 80 biases the spool 8 to the left side (the solenoid 9 side).

Also, the center hole 8a formed in the center of the spool 8 communicates with the first chamber L3 through 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 inside of each

annular groove

8b, 8d communicates with the first chamber L3 via the side holes 8c, 8e and the central hole 8a.

According to the above configuration, as shown in FIG. 2, when the spool 8 is located at a position where the extending side port 7a of the holder 7 faces the extending side annular groove 8b, the extending side port 7a and the first chamber Communication with L3 is permitted, and the flow of liquid from the extension side chamber L1 to the first chamber L3 through the extension side gap C2, the lateral hole 41a, the extension side check valve 71 and the extension side port 7a 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 to the extension side chamber L1 through the compression side port 7b, the compression side check valve 73, the lateral hole 41a and the extension side gap C2 is allowed.

Note that the state where the annular groove and the port face each other here means a state where the annular groove and the port overlap each other when viewed in the radial direction, and the opening degree of each port changes depending on the overlapping amount. 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 becomes larger, 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. The movable core has a cylindrical shape, and the plunger 9a is attached to the inner periphery of the movable core and has a tip abutting against the plate 81. The harness 90 for supplying 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 expansion side port 7a and the energization amount to the solenoid 9 is a negative proportional relationship having a negative proportional constant, and the opening degree of the expansion side port 7a increases as the energization amount increases from zero. Becomes smaller. The expansion side port 7a is one-wayed by the expansion side check valve 71, and the liquid flows from the expansion side gap C2 toward the first chamber L3. Therefore, when the opening degree of the expansion side port 7a is adjusted, the flow rates of the expansion side soft leaf valve 50 and the orifice 52 located downstream of the adjustment are adjusted.

On the other hand, the relationship between the opening degree of the pressure side port 7b and the energization amount to the solenoid 9 is a proportional relationship having a positive proportional constant, and the opening degree of the pressure side port 7b increases as the energization quantity 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 pressure side port 7b is adjusted, the flow rates of the pressure side soft leaf valve 51 and the orifice 52 located upstream thereof are adjusted.

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, it is seated on both ends of an 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 and 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. The gap C4 that can be formed is communicated.

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 expansion side chamber L1 is pressurized by the piston 2 when the shock absorber A extends, and the pressure in the expansion side gap C2 increases due to the pressure in the expansion side chamber L1, 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 right valve element 61 and the valve seat portion 42, and the tank T and the pressure side gap C3 are communicated with each other. Since the pressure side gap C3 communicates with the pressure side chamber L2, when the shock absorber A extends, the pressure of the pressure side chamber L2 becomes substantially the same as the pressure in the tank T (tank pressure).

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 communicates 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 biased toward the liquid chamber 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 passages that connect 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-side damping element FH having a hard leaf valve 20 on the expansion side, a hard leaf valve 21 on the pressure side, and an orifice 22 and configured to provide resistance to the flow of liquid is configured.

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.

This 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 extends, the piston rod 3 retracts from the cylinder 1 and the piston 2 compresses the expansion side chamber L1. Then, the liquid in the expansion 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 passage B. A resistance is applied to the flow of the liquid by the hard damping element FH or the soft damping element FS, and an extension damping force due to the resistance is generated. Then, when the shock absorber A extends, the distribution ratio of the liquid passing through the hard damping element FH and the soft damping element FS changes according to the amount of electricity supplied 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 hard side damping element FS is hardened. 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 expansion side damping element of the soft side damping element FS, is a large diameter orifice having a larger opening area than the orifice 22 which is the expansion side damping element of the hard side damping element FH, the soft side damping element FS. When the ratio of the liquid heading to the side decreases, the damping coefficient increases in both the low speed region and the medium and high speed regions, and the expansion 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 expansion side port 7a is closed and the entire flow rate passes through the expansion side damping element of the hard side damping 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.

As described above, when the distribution ratio of the liquid passing through the first and second damping elements on the expansion 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 and small. As shown, the inclination 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 smaller in both the low speed region and the medium and high speed regions. It gets bigger in both. Therefore, the change in the damping force characteristic from the orifice characteristic to the valve characteristic is gradual in any mode.

Further, the extension side damping element of the soft side 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 soft mode does not become excessive.

Further, when the shock absorber A extends, the pressure in the expansion 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 connected to 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.

Conversely, when the shock absorber A contracts, the piston rod 3 enters the cylinder 1 and the piston 2 compresses the pressure 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 passage B. A resistance is applied to the flow of the liquid by the hard damping element FH or the soft damping element FS, and a compression 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 is contracted, the liquid is the hard side leaf valve 21 or the orifice 22 on the pressure side that constitutes the first damping element on the pressure side of the hard side damping element FH, or the liquid on the soft side damping element FS. 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 are configured to include the

orifices

22 and 52 and the hard leaf valve 21 or the soft leaf valve 51 which are leaf valves parallel thereto. 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.

When the amount of current supplied to the solenoid valve V is increased to increase the opening degree of the pressure side port 7b, the proportion of the liquid passing through the pressure side damping element of the soft side damping element FS increases and the hard side damping element increases. The proportion of liquid passing through the damping element on the pressure side of 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. When the ratio of the heading direction increases, the damping coefficient becomes smaller in both the low speed region and the medium and high speed regions, and the compression side damping force generated with respect to the piston speed becomes smaller. 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 and the opening degree of the pressure side port 7b is reduced, the proportion of the liquid passing through the pressure side damping element of the soft side damping element FS is reduced. 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 increases in both the low speed region and the medium and high speed regions, and the compression side damping force generated with respect to the piston speed increases. When the solenoid valve V is de-energized, the pressure side port 7b is closed and the entire flow rate passes through the hard side damping element FH. Then, the damping coefficient becomes maximum, and the compression side damping force generated with respect to the piston speed becomes maximum.

As described above, when the distribution ratio of the liquid passing through the pressure-side first and second damping elements of the hard-side damping element FH and the soft-side damping element FS is changed by the solenoid valve V, the damping coefficient increases and decreases, and the expansion-side damping increases. 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 indicating the damping force characteristic 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. As the damping force characteristic changes from the orifice characteristic to the valve characteristic, the change is gentle in any mode. Further, 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, so that the compression side damping element of the hard side damping element FH is Even if a hard leaf valve with high valve rigidity and high opening pressure is adopted 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 in 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 between the extension side chamber L1 and the compression side chamber L2 by bypassing 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. The bypass valve B includes a solenoid valve V capable of changing the opening area of the bypass passage B, and a soft side damping element FS provided in the bypass passage B in series with the solenoid valve V. The hard side damping element FH includes 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-mentioned configuration, the characteristic of the damping force generated when the shock absorber A expands and contracts has an 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 to high speed range, The valve characteristics are peculiar to leaf valves. If the opening area of the bypass passage B is changed by the solenoid valve V, the hard-side damping element FH and the soft-side damping element of the liquid that moves between the expansion side chamber L1 and the compression side chamber L2 when the shock absorber A expands and contracts. Since the distribution ratio of the flow rate of the liquid passing through the FS changes, it is possible to freely set 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 middle and high speed ranges, and The adjustment range of the damping force when 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 and high speed range. Both damping factors are small. 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 region to the valve characteristic in the medium and high speed region, 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. And is configured. In this way, if the soft-side damping element FS is also provided with a leaf valve, even if the

hard leaf valves

20 and 21 which are the leaf valves of the hard-side damping element FH have high valve rigidity and high valve opening pressure, they are soft. The damping force in the mode does not become excessive. That is, according to the above configuration, valves having high valve rigidity can be adopted as the

hard leaf valves

20 and 21 which are leaf valves of the hard side damping element. Then, since the adjustment range of the damping force increases in the direction of increasing the damping force, the adjustment range of the damping force can be further increased when the piston speed is in the middle and high speed range.

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 a cylindrical holder 7 in which the expansion-side and pressure-

side ports

7a and 7b connected to the bypass B are formed, and is movably inserted into the holder 7. The spool 8 capable of opening and closing the expansion side and

compression side ports

7a, 7b, a biasing spring 80 for biasing the spool 8 in one of the moving directions of the spool 8, and a direction opposite to the biasing force of the biasing spring 80. And a solenoid 9 that applies the thrust of

Here, for example, like the solenoid valve described in JP2010-7758A, a needle valve that can reciprocate as a valve body is provided, and the opening degree is increased or decreased by increasing or decreasing the gap formed between the tip of the needle valve and the valve seat. When changing, the stroke amount of the valve element must be increased in order to increase the adjustment range of the opening, but this may not be possible.

Specifically, if the stroke amount of the needle valve is increased, the movable space of the needle valve increases and it becomes difficult to secure the accommodation space. Further, if the stroke amount of the solenoid plunger is increased in order to increase the stroke amount of the needle valve, the solenoid design must be changed, which is complicated. Furthermore, if it is attempted to increase the stroke of the needle valve without changing the design of the solenoid, parts are needed to increase the travel of the needle valve relative to the travel of the plunger, increasing the number of parts and accommodating space. 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. However, this allows the solenoid valve V to open and close. For this reason, if a plurality of

ports

7a and 7b are formed in the circumferential direction of the holder 7 or have a shape that is long in the circumferential direction, the electromagnetic force can be increased without increasing the stroke amount of the spool 8 that is the valve body of the electromagnetic 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. The port 7b on the pressure side that allows the unidirectional flow is provided. In the solenoid valve V of the present embodiment, the opening degree of the pressure side port 7b increases and the opening degree of the extension side port 7a decreases as the energization amount increases. For this reason, when the extension side damping force is adjusted to be large, the compression side damping force is automatically reduced, and the vehicle height can be reduced. 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 height can be increased.

However, the expansion side damping force may be increased and the compression side damping force may be decreased as the energization amount to the solenoid valve V is increased from zero. In such a case, all ports 7a on the expansion side are 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 pressure may be increased as the amount of electricity supplied to the solenoid valve V is increased.

In such a case, like the solenoid valve V1 shown in FIG. 6, the port formed in the holder may be the port 7c that allows the bidirectional flow of the liquid. And according to the said structure, since the expansion side valve seat 70, the compression side valve seat 72, the expansion side check valve 71, and the compression side check valve 73 can be omitted, the structure 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 energization amount increases, but the solenoid valve V1 increases as the energization amount increases. The opening of the port 7c may be set to be small.

Further, as described above, when the solenoid valves V, V1 including the holder 7, the spool 8, the biasing spring 80, and the solenoid 9 are used, a port and an annular groove for opening and closing the port are provided. 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 addition, the shock absorbers A and A1 shown in FIGS. 1 and 6 exhibit damping forces on both sides of compression and can be adjusted by 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 cylindrical 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 to move 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 axial length of the housing 4 that houses the soft side damping element FS, the solenoid valve V, and the low pressure priority valve 6 from increasing. 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. Here, the state where the cylinder 1 and the housing 4 are integrated 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 as a single unit. 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 unit 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 vehicle body side bracket 12, and the tank T may be integrally formed.

The preferred embodiments of the present invention have been described above in detail, but modifications, variations, and changes can be made without departing from the scope of the claims. This application claims priority based on Japanese Patent Application No. 2019-038128 filed with the Japan Patent Office on Mar. 4, 2019, the entire contents of which are incorporated herein by reference.

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

It ’s a shock absorber,
Cylinder and
A piston that is movably inserted in the cylinder in the axial direction to partition the inside of the cylinder into an expansion 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 damping element that provides resistance to the flow of liquid moving between the expansion 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 has a large-diameter orifice having an opening area larger than that of the orifice.
The shock absorber according to claim 1.
The soft side damping element is a shock absorber having a leaf valve provided in parallel with the large diameter orifice.
The shock absorber according to claim 1.
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. A shock absorber, comprising: a biasing spring that biases the spool; and a solenoid that applies a thrust in a direction opposite to the biasing force of the biasing spring to the spool.
The shock absorber according to claim 2, wherein
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 pressure side to give is provided,
As the leaf valve of the soft-side damping element, an expansion-side soft leaf valve that gives resistance to the flow of liquid from the expansion-side chamber to the compression-side chamber in the bypass path, and the bypass path from the compression-side chamber to the expansion-side chamber A shock absorber equipped with a soft leaf valve on the compression side that resists the flow of liquid toward.
The shock absorber according to claim 3, wherein
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,
A shock absorber in which 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 as the amount of energization to the solenoid valve increases.
The shock absorber according to claim 3, wherein
The port allows bidirectional flow of liquid.
The shock absorber according to claim 3, wherein
The spool and the low pressure priority valve are shock absorbers that move along a straight line that passes through the center of the piston rod and is orthogonal to the central axis.
The shock absorber according to any one of claims 1 to 7.
Housing,
A sub-cylinder provided in the housing and accommodating the soft side damping element is provided inside.
The low pressure priority valve is a shock absorber provided between the housing and the sub cylinder.
The shock absorber according to claim 8, wherein
A shock absorber in which the housing is integrated with the cylinder.