JPH08118939A - Self-pumping type shock absorber - Google Patents

Abstract

PURPOSE: To control variably a damping force and pump efficiency with a relatively simple constitution. CONSTITUTION: A piston 34 and cylinder 10, a damping force generating mechanisms 40, 42, a low pressure chamber 22, a high pressure chamber 32 communicating to an upper chamber 52 and a pump 136 for supplying oil from the low pressure chamber 22 to the high pressure chamber 32 by the relative movement of the piston 34 and cylinder 10 are provided. The pump 136 has a pump cylinder hole 44 provided in a rod part 36 of the piston 34, a pump piston 48 fixed to the cylinder on one end to define a pump chamber 62 in cooperation with the pump cylinder hole 44, a low pressure path 68 to connect the low pressure chamber 22 to the pump chamber 62 and a high pressure path 70 for connecting the high pressure chamber 32 to the pump chamber 62. The high pressure chamber 70 is extended at least through one end of the pump piston and a supply and reflux controlling valve 106 for controlling the communicating degree of the high pressure path 70 is provided near the high pressure path 70.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber, and more particularly to a self-pumping type shock absorber.

[0002]

2. Description of the Related Art As one of shock absorbers for vehicles such as automobiles, as disclosed in, for example, Japanese Patent Laid-Open No. 59-159441, they are relatively reciprocally fitted to each other and cooperate with each other. A piston and a cylinder that demarcate the chamber and the lower chamber, a damping force generation mechanism provided in the piston,
A low-pressure chamber, a high-pressure chamber that communicates with the upper chamber, a pump that has a pump chamber whose volume is increased or decreased by the relative movement of the piston and cylinder, and a low-pressure chamber that communicates with the upper chamber when the shock absorber extends a predetermined amount or more. The vehicle has a vehicle height adjusting mechanism, and the pump has a pump cylinder member arranged in the rod portion of the piston, and the pump cylinder member is reciprocally fitted to each other and fixed to the cylinder at one end to cooperate with the pump cylinder member. Pump piston that demarcates the pump chamber,
It includes a suction valve that allows the flow of oil from the low pressure chamber to the pump chamber, and a discharge valve that allows the flow of oil from the pump chamber to the upper chamber.The suction stroke corresponds to the extension stroke of the shock absorber, and 2. Description of the Related Art A self-pumping type shock absorber configured to suck oil into a pump chamber and discharge the oil from the pump chamber to an upper chamber by a discharge stroke corresponding to a contraction stroke of the shock absorber has been conventionally known.

According to such a self-pumping type shock absorber, when the shock absorber repeatedly expands and contracts, the suction stroke and the discharge stroke of the pump are also repeated, whereby oil is supplied from the low pressure chamber to the upper chamber and the lower chamber via the pump. The shock absorber gradually expands, and when the expansion amount of the shock absorber reaches a predetermined amount, the vehicle height adjustment mechanism prevents the shock absorber from extending further, so the vehicle height decreases due to an increase in the vehicle load. Even if the wheels repeatedly bounce and rebound as the vehicle travels, the vehicle height can be automatically returned to the standard vehicle height, and therefore the shock absorber vehicle height adjustment function can be performed without using an electric pump or the like. Can have

[0004]

In order to achieve both riding comfort and steering stability of the vehicle, it is preferable to provide a damping force varying mechanism in the self-pumping type shock absorber as described above. Since it is provided in the rod part of the piston, a control valve or actuator for increasing / decreasing the damping force cannot be incorporated in the rod part of the piston, and the damping force in the self-pumping shock absorber is also disclosed in the above-mentioned publication. It does not disclose variable control or a mechanism therefor.

In the conventional self-pumping type shock absorber described above, the discharge stroke of the pump is performed during the contraction stroke of the shock absorber, and the discharge stroke of the pump resists the high pressure in the pump chamber during the discharge stroke of the pump. The piston must be driven, and in addition to the axial force due to the damping force during the compression stroke of the shock absorber, the axial force due to the discharge stroke of the pump acts, so at the stage where the shock absorber shifts from the extension stroke to the compression stroke. The axial force of the shock absorber in the direction of extension increases rapidly in steps, and the input to the wheels from the road surface is strongly transmitted to the vehicle body via the shock absorber, which deteriorates the riding comfort of the vehicle. There is a problem of doing.

In order to solve such a problem, the efficiency of the pump is lowered when the number of times the pump is driven and the stroke is high, for example, when traveling on a rough road, and the axial force due to the pumping is reduced so that the vehicle travels. It is preferable to variably control the pump efficiency according to the situation to achieve both the riding comfort of the vehicle and the vehicle height adjusting function, but the above-mentioned publication does not disclose the pump efficiency varying mechanism.

The present invention has been made in view of the above-mentioned problems in the conventional self-pumping type shock absorber, and the main object of the present invention is to introduce high-pressure oil from the pump chamber to the high-pressure chamber. The passage is configured to extend at least in a portion that is not displaced relative to the cylinder, and the communication degree of the high-pressure passage and the communication degree of the high-pressure passage and the low-pressure passage are variably controlled so that the passage can be self- comparatively simple. The damping force and the pump efficiency of the pumping type shock absorber are variably controlled, whereby the ride comfort of the vehicle and the steering stability are compatible with each other, and the ride comfort of the vehicle and the vehicle height adjusting function are compatible with each other.

[0008]

SUMMARY OF THE INVENTION According to the present invention, the above-mentioned main object is to provide a piston and a cylinder which are engaged with each other so as to be relatively reciprocable and cooperate with each other to define a working fluid chamber. A damping force generation mechanism provided in the piston or the cylinder, a low pressure chamber, a high pressure chamber that communicates with the working fluid chamber, and a relative motion of the piston and the cylinder causes the working fluid from the low pressure chamber to the high pressure chamber. And a pump cylinder hole provided in a rod portion of the piston, and a pump cylinder hole fixed to the cylinder at one end and reciprocally fitted in the pump cylinder hole. A pump piston that cooperates to define a pump chamber, a low pressure passage means that connects and connects the low pressure chamber and the pump chamber, and a high pressure that connects and connects the high pressure chamber and the pump chamber. Passage means, a first check valve for allowing the flow of the working fluid from the low pressure passage means to the pump chamber, and a second check valve for allowing the flow of the working fluid from the pump chamber to the high pressure passage means. In a self-pumping shock absorber having a stop valve, the high-pressure passage means extends at least through the one end of the pump piston, and the high-pressure passage means communicates with the pump piston in the vicinity of the one end. A self-pumping shock absorber characterized in that a supply control valve for controlling the degree is provided (construction according to claim 1), or a working fluid chamber that cooperates with each other so as to be relatively reciprocable And a cylinder for defining the above, a damping force generating mechanism provided in the piston or the cylinder, a low pressure chamber, and a high pressure chamber communicating with the working fluid chamber. A pump supplying a working fluid from the low pressure chamber to the high pressure chamber by relative movement of the piston and the cylinder, the pump having a pump cylinder hole provided in a rod portion of the piston, and the pump cylinder hole at one end thereof. A pump piston fixed to a cylinder and reciprocally fitted in the pump cylinder hole and cooperating with the pump cylinder hole to define a pump chamber, and a low pressure passage means for connecting the low pressure chamber and the pump chamber in communication. When,
High-pressure passage means for connecting the high-pressure chamber and the pump chamber to each other, a first check valve for allowing the flow of the working fluid from the low-pressure passage means toward the pump chamber, and the high-pressure passage means for the pump chamber. In a self-pumping shock absorber having a second check valve for allowing a flow of working fluid toward it, the high pressure passage means extends at least through the one end of the pump piston. A recirculation passage means for connecting the high-pressure passage means and the low-pressure passage means to each other in the vicinity of the one end, and a recirculation control valve for controlling the degree of communication of the recirculation passage means. This is achieved by a self-pumping shock absorber (construction of claim 2).

[0009]

According to the first aspect of the present invention, the high-pressure passage means for connecting the high-pressure chamber and the pump chamber to each other extends at least through one end of the pump piston, and the high-pressure passage near the one end of the pump piston. Since the supply control valve for controlling the degree of communication of the passage means is provided, it is possible to directly or indirectly support the supply control valve by the cylinder,
Further, by increasing or decreasing the degree of communication of the high-pressure passage means by the supply control valve, the load of the pump, that is, the axial force of the shock absorber as a whole, that is, the damping force as a whole is variably controlled.

According to the second aspect of the present invention, the high-pressure passage means for connecting the high-pressure chamber and the pump chamber to each other extends at least through one end of the pump piston, and the high-pressure passage is provided near one end of the pump piston. Since the recirculation passage means for connecting the means and the low-pressure passage means to each other and the recirculation control valve for controlling the degree of communication of the recirculation passage means are provided, the recirculation control valve can be supported by the cylinder, and By increasing / decreasing the degree of communication of the return passage means by the return flow control valve, the amount of working fluid recirculated from the pump chamber to the low pressure passage means via the high pressure passage means and the return passage means is increased / decreased, thereby increasing the pump efficiency. Is controlled to increase or decrease.

[0011]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing one embodiment of a self-pumping shock absorber according to the present invention, which is configured to perform a pumping discharge stroke in both extension stroke and contraction stroke, and FIG. FIG. 3 is an enlarged partial vertical sectional view showing the pump of the embodiment shown in FIG. 1 and its vicinity, and FIG. 3 is an enlarged partial vertical sectional view showing the supply and return control valve of the embodiment shown in FIG. 1 and its vicinity.

In these drawings, reference numeral 10 denotes a cylinder, which includes an inner cylinder 14 and an outer cylinder 16 extending concentrically with each other along an axis 12. The upper end of the outer cylinder 16 is closed by an end cap 16A which is integral with the outer cylinder 16, and the end cap 18 is fixed to the lower end of the outer cylinder 16. The inner cylinder 14 is fixed to the outer cylinder 16 by a support member 20 at the upper end, and is fixed to the outer cylinder by an end cap 18 at the lower end.

The support member 20 cooperates with the outer cylinder 16 to define an annular low pressure chamber 22, and a low pressure gas 24 and an oil 26 as a working fluid are enclosed in the low pressure chamber 22. Below the lower end of the support member 20, a substantially cylindrical diaphragm 28 is arranged in the annular space between the inner cylinder 14 and the outer cylinder 16. The diaphragm 28 is fixed to the support member 20 at the upper end, and is fixed to the end cap 18 at the lower end, thereby defining a gas chamber 30 in which high-pressure gas is filled in the radially outer side, and radially inwardly. A high pressure chamber 32 in which the high pressure oil 26 is enclosed is defined.

A piston 34 is disposed in the inner cylinder 14 so as to be capable of reciprocating along the axis 12. The piston 34 is a piston rod 36 extending along the axis 12.
And a piston body 3 fixed to the upper end of the piston rod
It consists of eight. The piston body 38 is provided with a damping force generation mechanism 40 for extension stroke and a damping force generation mechanism 42 for compression stroke which are known per se. The piston rod 36 has a cylinder hole 44 extending along the axis 12, and a pump rod 48 extending along the axis 12 is fitted into the cylinder hole 44 from above.

The piston 34 cooperates with the inner cylinder 14, the support member 20, and the pump rod 48 to form the piston body 3.
8 defines an upper chamber 52 as a working fluid chamber, and cooperates with the inner cylinder 14 and the end cap 18 to define a lower chamber 54 as a working fluid chamber below the piston body 38. . The upper end of the upper chamber 52 is connected to the upper end of the high pressure chamber 32 by a high pressure passage 56 defined between the inner cylinder 14 and the support member 20.

The pump rod 48 has a support member 20 at the upper end.
Further, the pump piston 60 is fixed to the outer cylinder 16 by a fixing member 58, and a pump piston 60 is integrally provided near the lower end of the pump rod 48. The pump piston 60 is fitted in the cylinder hole 44 so as to be capable of reciprocating along the axis 12, and cooperates with the cylinder hole to form a first pump chamber 62 and a second pump chamber 6 below and above the pump piston, respectively.
4 is demarcated. The pump piston 60 is provided with a communication hole 66 that connects the first pump chamber 62 and the second pump chamber 64 to each other. The upper end of the piston rod 36 of the second pump chamber 64 is substantially the pump rod 48. It is shut off from the upper chamber 52 by tightly fitting.

The pump rod 48 is provided with a low-pressure passage 68 and a high-pressure passage 70 extending parallel to each other along the axis 12, and the central portion of the pump rod 48 in the longitudinal direction has a low-pressure passage 68 at its inner end. A communication hole 72 that is open at the outer end of the pump rod and that extends in the radial direction is provided at the outer end. The upper end of the low pressure passage 68 is below the low pressure chamber 22 by an intermediate chamber 74 defined around the fixing member 58 between the upper end of the support member 20 and the end cap 16A and a conduit 76 fixed to the support member 20. The lower end of the high-pressure passage 70 is connected to the second pump chamber 64 through a communication hole 78.

As shown in detail in FIG. 2, a first check valve 80 is provided at the lower end of the pump rod 48 in the first pump chamber 60. The check valve 80 includes a plate-shaped valve element 82, a cup-shaped support member 84 fixed to the lower end of the pump rod 48, and the valve element 82 supported by the support member 84 so as to abut the lower end of the pump rod 48. The support member 84 is provided with a communication hole 88 such as a slit or a hole that connects the inside of the support member 84 to the first pump chamber 60 for communication. Thus, the check valve 80 is connected to the first pump chamber 6 from the low pressure passage 68.
By allowing the oil flow toward 0 but blocking the oil flow in the opposite direction, it functions as an intake valve to the first pump chamber.

A second check valve 90 is provided above the pump piston 60. The check valve 90 is the pump rod 4
8 and a spring seat 94 fixed to the pump rod 48, and a substantially annular plate-shaped valve element 92 that reciprocally fits and opens and closes the upper end of the communication hole 66. And a compression coil spring 96 that urges the valve element 92 to the valve closing position shown in the drawing in which the valve element 92 is in contact with the upper surface of the pump piston 60, and from the first pump chamber 60 to the second pump chamber 64 via the communication hole 66. By allowing the flow of oil toward but blocking the flow of oil in the opposite direction, it functions as a discharge valve to the second pump chamber.

A vehicle height adjusting valve 98 is provided in the second pump chamber 64.
The vehicle height adjusting valve 98 has a substantially cylindrical shape and is reciprocally fitted to the pump rod 48. A compression coil spring 100 is elastically mounted between the lower end of the vehicle height adjusting valve 98 and the spring seat 94. The upper end and the lower end of the compression coil spring 100 are the flange portion of the vehicle height adjusting valve 98 and the spring seat 94, respectively. It is fixed to the flange by fitting. The vehicle height adjusting valve 98 maintains the valve closed state by closing the opening end of the communication hole 72 in the illustrated normal state where the compression coil spring 100 is not compressed, and maintains the low pressure passage 68 and the second pump chamber. The state in which the communication between 64 and the upper chamber 52 is blocked is maintained.

When the shock absorber expands by a predetermined amount or more, the vehicle height adjusting valve 98 has its upper end engaged with the lower surface of the upper end of the piston rod 36, and resists the spring force of the compression coil spring 100, and is opposed to the piston rod 36. The valve is opened by moving downward, but the open end of the communication hole 72 is closed by the upper end of the piston rod 36, so that the low pressure passage 68 communicates with the second pump chamber 64 and the upper chamber 52. When the shock absorber further extends, the communication hole 72 moves upward from the upper surface of the upper end of the piston rod 36, and the communication hole 72 causes the low pressure passage 6 to move.
8 and the upper chamber 52 are connected for communication.

As shown in detail in FIG. 3, the upper end of the high-pressure passage 70 is closed by a spherical stopper 102, and a communication hole 104 provided in the pump rod 48, a supply and return control valve 106, and a support. A communication hole 108 provided in the member 20 is communicatively connected to the upper end of the upper chamber 52. A reed valve type check valve 110 is provided at the upper end of the upper chamber 52, and the check valve 110 is fixed to the support member 20 by a lock nut 114 via a spacer 112.
The flow of oil from 06 through the communication hole 108 to the upper chamber 52 is allowed, but the flow of oil in the opposite direction is blocked.

The control valve 106 has a valve element 120 arranged in a valve hole 116 provided in the support member 20 so as to be rotatable about an axis 118 in a substantially dense manner, the valve element 120 having a connecting shaft 122. It is connected to an output shaft 126 of a rotary actuator 124, such as a step motor, via the actuator 124, and is rotationally driven and positioned around the axis 118 by the actuator 124. The support member 20 is provided with a communication hole 128 that communicates with the intermediate chamber 74 at one end and opens into the valve hole 116 at the other end. The valve element 120 defines a valve chamber 130 that is in constant communication with the communication hole 104, and controls the communication between the valve chamber 130 and the communication hole 108 and the communication between the valve chamber 130 and the communication hole 128. The hole 134 is formed.

The control valve 106 has a hole 1 as shown in FIG. 3 with the valve element 120 being rotationally driven and positioned about axis 118 by an actuator 124.
A supply mode in which the communication between the hole 32 and the communication hole 108 is allowed and the communication between the hole 134 and the communication hole 128 is blocked, and the communication between the hole 132 and the communication hole 108 and the hole 1 as shown in FIG.
A supply and return mode that allows communication between the communication hole 34 and the communication hole 128, and a return mode that allows communication between the hole 132 and the communication hole 108 and allows communication between the hole 134 and the communication hole 128 as shown in FIG. It is switched to and, and the supply mode is normally set.

In particular, as shown in FIG. 6, when the communication degree between the hole 132 and the communication hole 108 is Ah and the communication degree between the hole 134 and the communication hole 128 is Ar, the holes 132 and 1 are formed.
The size and shape of 34 are such that when the rotation angle θ of the actuator 124 is −θ _{r1 to} θ _h1 , the communication degree Ah is the maximum value A.
hmax, the degree of communication Ar is 0, and the rotation angle θ is θ
_In the section from _{h1 to} θ _h2, the communication degree Ah gradually decreases as the rotation angle θ increases while the communication degree Ar is maintained at 0, and when the rotation angle θ is θ _h2 , the communication degree Ah.
Is the minimum value Ahmin, and in the section where the rotation angle θ is −θ _r2 to −θ _r1 , the communication degree Ah gradually decreases and the communication degree Ar gradually increases as the rotation angle θ increases in the negative direction. The degree of communication Ah is set to 0 and the degree of communication Ar is set to the maximum value Armax in the section where the rotation angle θ is −θ _r3 to −θ _r2 .

As will be understood from the above description, the members such as the piston rod 36, the pump rod 48, the pump piston 60, the first check valve 80 and the second check valve 90 are the piston 3
The volume of the first pump chamber 62 and the second pump chamber 64 is increased or decreased by the expansion and contraction of the shock absorber due to the relative movement of the cylinder 4 and the cylinder 10, so that oil is supplied from the low pressure chamber 22 to the upper chamber 52 as described later. The pump 136 is bounded. Further, the conduit 76, the intermediate chamber 74, the low pressure passage 6
Reference numeral 8 defines a low pressure passage means which cooperates with each other to connect the low pressure chamber 22 and the first pump chamber 62 to each other. The high pressure passage 56, the upper chamber 52, the communication holes 108 and 104, and the high pressure passage 7 are defined.
0, the communication hole 78, the second pump chamber 68, and the communication hole 66 cooperate with each other to define high-pressure passage means for connecting the high-pressure chamber 32 and the first pump chamber 62 to each other.

Further, the communication hole 128 defines a return passage means for connecting and connecting the high pressure passage means and the low pressure passage means.
The supply and return control valve 106 controls the amount of oil supplied from the first pump chamber 62 to the high pressure chamber 32 via the high pressure passage means by controlling the degree of communication of the high pressure passage means when it is in the supply mode. It functions as a supply control valve, and controls the degree of communication of the return passage means when in the supply and return mode so that the oil returned from the first pump chamber 62 to the low pressure passage means via the high pressure passage means and the return passage means. It functions as a reflux control valve that controls the amount.

Further, as shown in FIG. 1, a connecting member 138 for sealing the lower end of the pump cylinder hole 44 is fixed to the lower end of the piston rod 36 by screwing, and the connecting member 138 and the end cap 18 are connected to each other. A dust boot 140 is provided between them. A connecting member 142 is provided at the upper end of the outer cylinder 16 integrally with the end cap 16A, and the shock absorber is connected to the vehicle body by a connecting member 142 via a rubber cushion not shown in the drawing. Is connected to a suspension member such as a suspension arm via a rubber bush (not shown).

In the embodiment constructed as described above, the piston 34 is caused by the rebound of the wheel not shown in the drawing.
When the cylinder 10 makes a relative movement in the extension stroke, the volume of the upper chamber 52 increases and the volume of the lower chamber 54 decreases, so that the oil in the lower chamber moves to the upper chamber via the piston body 38, and a damping force is generated. Damping force Fse of extension stroke by mechanism 40
Is generated. Similarly, when the wheel bounces, the piston 3
4 and the cylinder 10 move relative to each other in the contracting stroke, the volume of the upper chamber 52 decreases and the volume of the lower chamber 54 increases, so that the oil in the upper chamber moves to the lower chamber via the piston body 38, and the damping force is increased. Damping force F of the contraction process by the generation mechanism 42
sc is generated.

In the extension stroke of the shock absorber, the volume of the first pump chamber 62 increases and the pressure in the pump chamber decreases, and the volume of the second pump chamber 64 decreases and the pump chamber decreases. The increase in the pressure of the first check valve 8 keeps the second check valve 90 in the closed position.
0 is opened, the conduit 76, the intermediate chamber 74, the
Oil is sucked into the first pump chamber 62 through the low-pressure passage 68 and the first check valve 80, and the communication hole 78, the high-pressure passage 70, the communication hole 104, the supply and recirculation control valve 106 from the second pump chamber 64. Through the communication hole 108 and the check valve 110, the upper chamber 5
The oil is discharged and supplied to the second pump 2, whereby the suction stroke to the first pump chamber 62 and the discharge stroke to the upper chamber 52 are performed.

Similarly, in the compression stroke of the shock absorber, the volume of the first pump chamber 62 decreases, the pressure in the pump chamber rises, and the volume of the second pump chamber 64 increases. The second check valve 90 is opened with the first check valve 80 maintained in the closed position, and the oil is discharged and supplied from the first pump chamber 62 to the second pump chamber 64. The pump rod 4 located in the piston rod 36
By increasing the volume of No. 8, the amount of increase in the volume of the second pump chamber 64 is smaller than the amount of decrease in the volume of the first pump chamber 62, and the volume of oil corresponding to the difference between these volumes is the second amount. Is supplied from the pump chamber 64 to the upper chamber 52, whereby the discharge process to the second pump chamber 64 and the discharge process to the upper chamber 52 are performed.

When the suction stroke and the discharge stroke of the pump 136 are repeated in this manner, the amount and pressure of oil in the upper chamber 52, the lower chamber 54 and the high pressure chamber 32 increase, which causes the piston 34 and the cylinder 10 to extend. When the relative displacement becomes a predetermined amount or more, the upper chamber 52 and the low pressure passage 68 are communicatively connected by the communication hole 72, and the upper chamber 52 is
A part of the oil therein is discharged to the low pressure chamber 22, whereby the piston 34 and the cylinder 10 are positioned with respect to each other so that the communication hole 72 is located at the position of the upper end of the piston rod 36. Therefore, even if the load of the vehicle fluctuates and the vehicle height fluctuates, the pumping action of the pump 136 and the communication hole 72 performed by the expansion and contraction of the shock absorber.
The vehicle height is automatically returned to the standard vehicle height determined by the position of the communication hole 72.

As described above, the damping force Fse generated by the damping force generating mechanism 40 is generated according to the speed of relative movement of the piston 34 and the cylinder 10 in the extension stroke, that is, the stroke speed of the wheel in the rebound direction, and the damping force is generated. Mechanism 42
The damping force Fsc generated by is generated according to the speed of relative movement in the contraction stroke, that is, the stroke speed of the wheel in the bouncing direction. Further, when the stroke S is at the maximum position, an axial force is generated by reversing the differential pressure between the upper chamber 52 and the lower chamber 54. Therefore, when a sinusoidal vibration input acts on the shock absorber, The axial force Fs due to expansion and contraction changes as shown in FIG.

Further, in the extension stroke of the shock absorber, the pump 136 resists the differential pressure between the pressure in the low pressure chamber 22 and the pressure in the first pump chamber 62 and the high pressure in the second pump chamber 64. Since the oil suction work and the oil discharge work are performed, the axial force Fpe in the direction opposite to the extension direction of the shock absorber acts on the piston 34 and the cylinder 10. Similarly, in the compression stroke of the shock absorber, the pump 1
Since 36 performs the work of discharging oil against the high pressure in the first pump chamber 62 and the second pump chamber 64, the piston 34 and the cylinder 10 have an axial force in the direction opposite to the direction in which the shock absorber contracts. Fpc acts, and the magnitude of this axial force is larger than the axial force Fpe.

Therefore, assuming that the axial forces Fpe and Fpc are substantially constant regardless of the stroke speed, the pump 136
The axial force Fp due to the suction work and the discharge work changes to a rectangular shape as shown by the solid line in FIG. 7 (B), and the axial force F of the shock absorber as a whole is shown in FIG. 7 (C). It changes as shown by the solid line. Thus, according to the illustrated embodiment, compared with the structure in which the pumping discharge stroke is performed only in the contraction stroke or the extension stroke, the oil supply amount per one expansion / contraction stroke of the shock absorber is high, and the pump Since the efficiency can be increased, the vehicle height can be quickly returned to the standard vehicle height even if the vehicle height fluctuates due to the variation of the vehicle load.

Further, in both the extension stroke and the contraction stroke of the shock absorber, the supply and recirculation control valve 106 is set to the supply mode, and the rotation angle of the actuator 124 is controlled in the section where θ is between θ _{h1 and} θ _h2. Then, the oil is squeezed when flowing from the hole 132 to the communication hole 108.
The axial force Fp due to the pumping of the pump 136 and the axial force F of the shock absorber as a whole become large as shown by the broken lines in FIGS. 7B and 7C, respectively. Therefore, by increasing the rotation angle θ within the range of θ _h1 to θ _h2 , the damping force of the shock absorber can be increased and the steering stability of the vehicle can be improved.
It is possible to reduce the damping force of the shock absorber and improve the riding comfort of the vehicle.

In both the extension stroke and the contraction stroke of the shock absorber, the rotation angle θ of the actuator 124 is controlled in the range of −θ _r2 to −θ _r1 and the supply and return control valve 106 is set to the supply and return mode. By setting
As shown in FIG. 4, the high pressure passage 70 and the communication hole 10
The oil supplied to the valve chamber 130 via 4 flows not only to the upper chamber 52 via the hole 132 and the communication hole 108 but also to the hole 1
34, through the communication hole 128 to the intermediate chamber 74, and thereby the load of the pump 136 is reduced. Therefore, the axial force Fp due to pumping and the axial force F of the shock absorber as a whole are shown in FIGS. It becomes smaller as indicated by the one-dot chain line in C).

Therefore, for example, when traveling on a rough road, the rotation angle θ
The pump 136 by increasing
It is possible to reduce the pump efficiency of the vehicle and improve the riding comfort of the vehicle. Conversely, by reducing the size of the rotation angle θ within a negative range, the pump efficiency is improved and the vehicle height of the shock absorber is increased. By improving the adjusting function, the vehicle height can be efficiently returned to the standard vehicle height even if the vehicle height decreases. Since the number of times of pumping and the stroke are high when traveling on a bad road, the vehicle height adjusting function of the shock absorber is not significantly impaired even if the pump efficiency is reduced as described above.

Further, the rotation angle θ of the actuator 124 is set to −
Set in the interval from θ _r3 to −θ _r2 , supply and recirculation control valve 10
By setting 6 to the reflux mode, all the oil discharged by the pump 136 can be returned to the low-pressure passage 68, in which case the pump 136 does not substantially perform pump work, so that the pumping shaft The force Fp is substantially 0, and the axial force F of the shock absorber as a whole becomes very small as shown by the fine dotted line in FIG. 7C, and the shock absorber does not have the self-pumping function. It can function like a conventional general shock absorber, and can further improve the riding comfort of the vehicle.

Further, according to the illustrated embodiment, the pump rod 48 fixed to the cylinder 10 at the upper end is fitted into the piston rod 36 so that the first pump chamber 62 and the second pump chamber 64 are separated from each other. 36, the high-pressure passage 70 and the low-pressure passage 68 together with the pump rod 4
Since it is provided in the pump rod so as to extend to the upper end of 8, the pump cylinder hole is formed in the same member as the pump rod 48, and extends upward from the upper end of the piston rod 36 to the pump cylinder hole. To simplify the structure of the shock absorber, as compared with the case where a fitting pump rod is provided and the first and second pump chambers are defined by the pump piston provided at the upper end of the pump rod. In addition, the length of the shock absorber can be reduced and the shock absorber can be made compact.

Further, according to the illustrated embodiment, the supply and recirculation control valve 106 functions as a supply control valve for controlling the communication degree of the high-pressure passage means and as a recirculation control valve for controlling the communication degree of the recirculation passage means. Because it fulfills both functions of
Compared with the case where these control valves are individually provided, the structure of the shock absorber can be simplified and the cost can be reduced.

Further, in the illustrated embodiment, the communication hole 108
Check valve 1 that allows only the flow of oil toward the upper chamber 52
10, the supply and recirculation control valve 106 is provided.
Is set to the supply and recirculation mode, the oil in the upper chamber 52 flows back to the valve chamber 130 through the communication hole 108 and the hole 132, and further through the hole 134 and the communication hole 128 to the intermediate chamber 7.
It is possible to surely prevent the flow to 8.

Although the present invention has been described above in detail with reference to specific embodiments, the present invention is not limited to these embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art that

For example, in the above embodiment, the supply control valve for controlling the communication degree of the high pressure passage means and the recirculation control valve for controlling the communication degree of the recirculation passage means are one common control valve. Although configured as the control valve 106, the supply control valve and the recirculation control valve may be provided separately, in which case the communication degree Ah of the high-pressure passage means and the communication degree Ar of the recirculation passage means are independent of each other. It can be controlled to increase or decrease.

Further, in the above-mentioned embodiment, the pumping discharge stroke is carried out in both the extension stroke and the contraction stroke. Sho 59-1594
No. 41, a shock absorber configured to perform a pumping discharge stroke only in a contraction stroke, and an extension stroke as described in JP-A-6-24547 by the applicant of the present application. May be configured as a shock absorber configured to perform the pumping discharge stroke only. However, in these cases, since the damping force and the pump efficiency can be variably controlled, it is limited to the expansion stroke or the compression stroke in which the pumping discharge stroke is performed.
The self-pumping shock absorber according to the present invention is preferably configured to perform the pumping discharge stroke in both the extension stroke and the contraction stroke as in the above-described embodiment.

[0047]

As is apparent from the above description, according to the structure of the above-mentioned claim 1, the high pressure passage means for connecting the high pressure chamber and the pump chamber for communication extends at least through one end of the pump piston, The supply control valve for controlling the degree of communication of the high-pressure passage means is provided in the vicinity of one end of the pump piston, and according to the configuration of claim 2, the high-pressure passage means for connecting the high-pressure chamber and the pump chamber in communication is at least the pump piston. The recirculation passage means extends through one end and connects the high pressure passage means and the low pressure passage means in communication with each other in the vicinity of one end of the pump piston. Since it is provided in the vicinity, the supply control valve and the reflux control valve can be directly or indirectly supported by the cylinder, and these valves are incorporated in the rod portion of the piston. As compared with the case of the formation, it is possible to simplify the structure of the shock absorber.

In particular, according to the structure of claim 1, the load control valve controls the increase / decrease of the communication degree of the high-pressure passage means, whereby the load of the pump, and hence the axial force of the shock absorber as a whole, that is, the damping force as a whole. Can be variably controlled, whereby the riding comfort and the steering stability can be improved according to the running condition of the vehicle.

According to the second aspect of the present invention, the circulation control valve controls the increase / decrease of the degree of communication of the return passage means, so that the return from the pump chamber to the low pressure passage means is performed via the high pressure passage means and the return passage means. It is possible to increase / decrease the amount of fluid to increase / decrease the efficiency of the pump, thereby improving the riding comfort and the vehicle height adjusting function according to the traveling condition of the vehicle.

[Brief description of drawings]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of a self-pumping shock absorber according to the present invention configured to perform a pumping discharge stroke in both extension stroke and contraction stroke.

FIG. 2 is an enlarged partial vertical sectional view showing the pump of the embodiment shown in FIG. 1 and its vicinity.

FIG. 3 is an enlarged partial vertical cross-sectional view showing the supply and recirculation control valve of the embodiment shown in FIG. 1 and its vicinity.

FIG. 4 is an enlarged partial vertical cross-sectional view showing the supply and recirculation control valve shown in FIG. 3 in a supply and recirculation mode.

5 is an enlarged partial vertical cross-sectional view showing the supply and recirculation control valve shown in FIG. 3 in a recirculation mode.

FIG. 6 is a graph showing the relationship between the rotation angle θ of the supply and return control valve and the degree of communication Ah in the supply mode and the degree of communication Ar in the return mode.

FIG. 7A shows the relationship between the axial force Fs due to expansion and contraction of the shock absorber and the stroke S, FIG. 7B shows the relationship between the axial force Fp due to pump work and the stroke S, and FIG. ) Is a graph showing the relationship between the axial force F and the stroke S of the shock absorber as a whole.

[Explanation of symbols]

 10 ... Cylinder 22 ... Low pressure chamber 32 ... High pressure chamber 34 ... Piston 40, 42 ... Damping force generating mechanism 44 ... Cylinder hole 48 ... Pump rod 52 ... Upper chamber 54 ... Lower chamber 60 ... Pump piston 62 ... First pump chamber 64 ... second pump chamber 72 ... communication hole 80 ... first check valve 90 ... second check valve 106 ... supply and recirculation control valve 110 ... check valve 124 ... rotary actuator 136 ... pump

Claims (2)

[Claims] 1. A piston and a cylinder that relatively reciprocally engage with each other and cooperate with each other to define a working fluid chamber, a damping force generating mechanism provided in the piston or the cylinder, and a low pressure chamber. A high pressure chamber that communicates with the working fluid chamber, and a pump that supplies the working fluid from the low pressure chamber to the high pressure chamber by relative movement of the piston and the cylinder, the pump being provided on a rod portion of the piston. A pump cylinder hole provided, a pump piston fixed to the cylinder at one end, fitted reciprocally in the pump cylinder hole, and cooperating with the pump cylinder hole to define a pump chamber, and the low pressure chamber. And a low pressure passage means for connecting the pump chamber to the pump chamber, a high pressure passage means for connecting the high pressure chamber and the pump chamber to each other, and a low pressure passage means to the pump chamber. In a self-pumping shock absorber having a first check valve that allows a flow of a dynamic fluid, and a second check valve that allows a flow of a working fluid from the pump chamber toward the high-pressure passage means, The high-pressure passage means extends at least through the one end of the pump piston, and a supply control valve for controlling the degree of communication of the high-pressure passage means is provided near the one end of the pump piston. A characteristic self-pumping shock absorber. 2. A piston and a cylinder which are fitted to each other so as to be capable of relatively reciprocating movement and cooperate with each other to define a working fluid chamber, a damping force generating mechanism provided in the piston or the cylinder, and a low pressure chamber. A high pressure chamber that communicates with the working fluid chamber, and a pump that supplies the working fluid from the low pressure chamber to the high pressure chamber by relative movement of the piston and the cylinder, the pump being provided on a rod portion of the piston. A pump cylinder hole provided, a pump piston fixed to the cylinder at one end, fitted reciprocally in the pump cylinder hole, and cooperating with the pump cylinder hole to define a pump chamber, and the low pressure chamber. And a low pressure passage means for connecting the pump chamber to the pump chamber, a high pressure passage means for connecting the high pressure chamber and the pump chamber to each other, and a low pressure passage means to the pump chamber. In a self-pumping shock absorber having a first check valve that allows a flow of a dynamic fluid, and a second check valve that allows a flow of a working fluid from the pump chamber toward the high-pressure passage means, The high-pressure passage means extends at least through the one end of the pump piston, and a return passage means for connecting the high-pressure passage means and the low-pressure passage means in communication with each other in the vicinity of the one end of the pump piston. A self-pumping shock absorber, which is provided with a recirculation control valve for controlling the degree of communication of the recirculation passage means.