JPH0727165A - Damping force variable type shock absorber - Google Patents

Abstract

PURPOSE:To reduce the occurrence of slide resistance of a spool valve for controlling a damping force and to perform smooth reciprocation. CONSTITUTION:A damping force variable type shock absorber comprises a cylinder; a piston to partition upper and lower chambers from each other in coordination with the cylinder; and a damping force generating device. The piston comprises a bypass passage 158 through which the upper and lower chambers are interconnected; a valve hole 88 formed in the middle of the bypass passage; a spool valve 86 fitted in the valve hole reciprocatively along the axis line 14 of the valve hole and controlling communication of the bypass passage; and an actuator 46 to drive and position the spool valve. The spool valve is relatively displaceably coupled to the shaft 71 of the actuator in a direction extending across the axis line and energized to the tip of the shaft 71 of the actuator along the axial line through the force of a spring 142.

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 shock absorber having a variable damping force.

[0002]

2. Description of the Related Art As one of shock absorbers of variable damping force type for vehicles such as automobiles, for example, JP-A-59-117 is known.
As described in Japanese Laid-Open Patent Publication No. 933, a cylinder, a piston that reciprocally fits in the cylinder and cooperates with the cylinder to define a cylinder upper chamber and a cylinder lower chamber, and a relative movement of the piston with respect to the cylinder. A damping force generation device that generates a damping force by giving a flow resistance to the working fluid that flows,
A bypass passage provided in the piston for connecting the cylinder upper chamber and the cylinder lower chamber to each other, a valve hole provided in the middle of the bypass passage, and a bypass passage that is rotatably or reciprocally fitted in the valve hole. BACKGROUND ART A shock absorber having a valve body that selectively controls and an actuator that drives and positions the valve body is conventionally known.

In such a shock absorber, the position of the valve element is controlled by the actuator and the communication or the degree of communication of the bypass passage is controlled, so that the shock absorber flows through the bypass passage between the cylinder upper chamber and the cylinder lower chamber. Since the flow rate of the working liquid to be controlled is controlled, the flow rate of the working liquid passing through the damping force generating device is changed, whereby the damping force generated by the damping force generating device is variably controlled.

[0004]

In the conventional shock absorber as described above, the valve element is rigidly connected and fixed to the tip of the drive shaft of the actuator and is driven by being rotated or reciprocated by the drive shaft. Since the drive shaft or the valve body and the valve hole are displaced from each other in the lateral direction or in the intersecting direction with each other, the shock absorber component is assembled when the shock absorber is assembled. When the actuator is driven, the sliding resistance between the valve hole and the wall surface becomes high, the response of switching control of the damping force of the shock absorber deteriorates, and the actuator with the increase in the driving force required for the actuator Problems such as an increase in size and an increase in energy consumption occur.

Further, in order to prevent the above-mentioned various problems caused by the increased sliding resistance of the valve body from occurring, the processing accuracy and assembly accuracy of the constituent members of the shock absorber are extremely high. Must be tightly controlled,
Therefore, the cost increase of the shock absorber is inevitable.

In view of the above-mentioned problems in the conventional damping force type shock absorber, the present invention drives the valve element even if the processing accuracy and assembly accuracy of the constituent members of the shock absorber are not strictly controlled. It is an object of the present invention to provide a shock absorber with a variable damping force improved so that the sliding resistance at the time of movement does not increase and the valve body is always driven and positioned smoothly.

[0007]

SUMMARY OF THE INVENTION According to the present invention, the above object is to provide a cylinder and a cylinder upper chamber and a cylinder lower chamber which are reciprocally fitted in the cylinder and cooperate with the cylinder. Which establishes a damping force by giving a flow resistance to the working liquid flowing with the relative movement of the piston with respect to the cylinder, and the cylinder upper chamber and the cylinder lower chamber, which are provided in the piston, communicate with each other. A bypass passage to be connected, a valve hole provided in the middle of the bypass passage, and a valve for reciprocatingly fitting into the valve hole along its axis to selectively control the communication or the degree of communication of the bypass passage. A body and an actuator including a drive shaft connected to the valve body for reciprocating and positioning the valve body, the drive shaft being provided on the valve body and extending substantially along the axis. A shock absorber having a variable damping force, which is fitted in a hole in a loosely fitted state, and in which the valve element is biased by a biasing means substantially along the axis of the drive shaft. Achieved by

[0008]

According to the above construction, the drive shaft of the actuator is loosely fitted in the hole provided in the valve body and extending substantially along the axis of the valve hole, and the valve body is Since the biasing means biases the tip of the drive shaft substantially along the axis, the valve body can be displaced relative to the drive shaft in a direction transverse to the axis, and the valve body is biased by the biasing means. It is not strongly pressed against the wall of the valve hole.

Therefore, even if the shock absorber components are assembled with the axis of the drive shaft or valve element and the axis of the valve hole offset from each other, the valve element can smoothly reciprocate along the valve hole. Therefore, it is surely avoided that the sliding resistance becomes high when the valve body is driven.

[0010]

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 a main part of a first embodiment of a shock absorber according to the present invention configured as a twin-tube type shock absorber, and FIG. 2 spools a main part of a piston of the first embodiment. FIG. 3 is an enlarged partial vertical cross-sectional view showing the valve in the fully closed position. FIG. 3 shows the connection structure between the drive shaft of the actuator and the spool valve in the first embodiment with the spool valve in the fully open position. FIG. 4 is an enlarged partial vertical cross-sectional view shown by.

In FIG. 1, 10 and 12 indicate an inner cylinder and an outer cylinder extending concentrically along an axis 14, both ends of which are closed by end caps not shown in the drawing. Has been. The cylinders 10, 12 and the end cap cooperate with each other to define an annular chamber 16. A piston 18 is arranged in the inner cylinder 10 so as to be capable of reciprocating along an axis 14. The piston 18 extends along the axis 14 through a piston body 24 that divides the inside of the inner cylinder 10 into a cylinder upper chamber 20 and a cylinder lower chamber 22, and a piston body 24 integrally connected to the body and penetrating an upper end cap. And a piston rod 26. The piston body 24 is the nut 2
8 is fixed to the tip end portion of the piston rod 26, and the piston body 24 has a well-known structure for a damping force generator for the extension stroke (the check valve 30 and the damping force generating valve 3).
2) is provided.

Although not shown in FIG. 1, a base valve assembly having a structure known per se is provided in a lower portion of the inner cylinder 10, and the base valve assembly is used for an extension stroke. A damping force generator for contraction stroke similar to the damping force generator of FIG. Further, the cylinder upper chamber 20, the cylinder lower chamber 22, and a part of the annular chamber 16 are filled with oil 34 as a working liquid, and the upper portion of the annular chamber 16 is filled with high-pressure gas. Although not shown in FIG. 1, the upper end of the piston rod 26 is connected to the vehicle body as a sprung body, and the outer cylinder 12 or the end cap at the lower end is connected to a suspension member as a unsprung body not shown. It is supposed to be done.

As shown in FIG. 2, the piston rod 26 includes a rod member 42 having a hollow bore 40 extending along the axis 14. A valve housing 44 is fixed to the lower end of the rod member 42 by screwing, and an actuator 46 is accommodated in the hollow hole 40.
The actuator 46 includes a step motor 48 and a ball screw device 50 as a motion conversion device that converts the rotational motion of the step motor 48 into a reciprocating motion. The step motor 48 is rotatably supported by a coil 54 and a plurality of magnetic pole members 55 held by a bobbin 52, and bearing support members 60 and 62 via ball bearings 56 and 58, respectively, and is provided on an outer peripheral surface facing the coil 54. The permanent magnet 64 has a hollow rotating shaft 66 fixed thereto, and when the coil is energized, the rotating shaft rotates about the axis 14.

The ball screw device 50 has a ball screw shaft 70 extending along the axis 14 and having a spiral groove on the outer peripheral surface for receiving a plurality of balls 68, and a rotary shaft 66 on the outer peripheral surface.
And an outer race member 72 having a spiral groove which is fixed to the inner peripheral surface and receives the plurality of balls 68 on the inner peripheral surface. The shaft 70 integrally has a projection 74 having a rectangular cross section at its upper end, and the projection is reciprocally fitted along a shaft line 14 into a hole 76 having a rectangular cross section provided in the bearing support member 60. When the rotating shaft 66 rotates, the shaft 70 moves linearly along the axis 14 upward or downward in the figure without rotating in accordance with the rotating direction. Further, the shaft 70 integrally has a shaft 71 extending downward from the lower end along the axis 14 and functioning as a drive shaft.

The valve housing 44 is provided with O-rings 78 and 80 for sealing the bearing housing 62 and the wall surface of the hollow hole 40, respectively. Also hollow hole 4
A stopper ring 82 for fixing the bobbin 52 and preventing the bobbin 52 from falling off is fixed to the wall surface of 0.

The valve housing 44 has a rod portion 44a, which projects downward from the lower end of the rod member 42 along the axis 14. The nut 28 is the rod portion 44
It is fixed to the lower end of a by screwing. Rod part 4
4a has a hollow hole 84 extending along the axis 14, and the upper portion of the hollow hole defines a valve hole 88 for reciprocally receiving the spool valve 86 along the axis 14. A stopper 9 is provided between the piston body 24 and the valve housing 44.
0, the spacer 92, and the bypass device 94 are the rod portion 44a.
It is fixed in a state of being fitted to.

The bypass device 94 includes an inner cylinder 96 and an outer cylinder 98 that extend coaxially to each other and end caps 100 and 102 located at opposite ends thereof, the members cooperating with each other to provide the axis 14; An inner space 104 that extends in a ring shape is defined. The end caps 100 and 102 are provided with a plurality of passages 106 and 108 extending in the vertical direction in the figure, respectively, and are in contact with the upper surfaces of the end caps 100 and 102, and check valves 110 and 112, respectively. It is provided. The check valve 110 is sandwiched between the spacer 92 and the end cap 100 at the radially inner portion thereof, and
Further, only the flow of oil toward the cylinder upper chamber 20 is allowed. On the other hand, the check valve 112 is sandwiched between the inner cylindrical body 96 and the piston body 24 via the spring 114 and the spacer 116 at the radially inner peripheral portion thereof, and the oil flowing from the cylinder upper chamber 20 to the internal space 104. Only the flow of is allowed.

The inner cylindrical body 96 is provided with a plurality of radial passages 118 communicating with the internal space 104 and an annular port 120 communicating with the passages. The rod portion 44a of the valve housing is provided with a plurality of radial passages 122 communicating with the annular port 120 and an annular port 124 communicating with the passages and opening to the valve hole 88.

The spool valve 86 has a hollow hole 126 extending in the longitudinal direction thereof, and the diameter of the hollow hole is set to be slightly larger than the diameter of the shaft 71, whereby the spool valve 86 is attached to the shaft 71. It is fitted in a loose fit state. An annular groove 128 is provided near the lower end of the shaft 71, and a stopper ring 130 is attached to the annular groove. A washer 132 is interposed between the stopper ring 130 and the lower end of the spool valve 86. An annular groove 134 is provided on the shaft 71 at a position above the upper end of the spool valve 86, and a stopper ring 136 is attached to the annular groove.

A compression coil spring 142 is fitted between the spring seat 138 disposed in contact with the stopper ring 136 and the end surface of the counter bore 140 provided at the upper end of the spool valve 86 in a state of being fitted to the shaft 71. It is equipped with ammunition. The spring force of the compression coil spring 142 is set to a minimum value sufficient to hold the spool valve in contact with the washer 132 as shown, against the fluid force and frictional force acting on the spool valve 86. , Thereby causing spool valve 86 to reciprocate according to the shaft as it is reciprocated by shaft 71 along axis 14.
4 is relatively free to be displaced relative to the shaft in the direction crossing 4.

The spool valve 86 cooperates with a valve hole 88 to define an upper chamber 144 and a lower chamber 146 above and below the valve hole 88, which are located between the counter bore 140, the hollow hole 126 and the shaft 71. The space, the spool valve, the washer 132, the shaft 71, and the clearance passage between the stopper ring 130 communicate with each other. Also spool valve 8
The lower end of 6 is tapered so that when the spool valve is in the fully closed position shown in FIG. 2, the communication between the annular port 124 and the lower chamber 146 is blocked.
When the spool valve is driven upward from the fully closed position in the figure as shown in FIG. 5, the variable orifice 148 that connects the annular port 124 and the lower chamber 146 in communication is defined.

Thus, the passages 106 and 108, the internal space 104, the radial passage 118, the annular port 120, the radial passage 122, the annular port 124, and the hollow hole 84 bypass the damping force generators 30 and 32 and are located in the cylinder upper chamber. 20 and the cylinder lower chamber 22 are communicatively connected to each other, and a bypass passage 158 having a valve hole 88 is defined in the middle of the passage. It is variably controlled by being controlled.

In the operation of the illustrated embodiment, the pressure in the cylinder lower chamber 22 becomes lower than the pressure in the cylinder upper chamber 20 and the annular chamber 16 in the extension stroke of the piston, so that the cylinder upper chamber And a part of the oil in the annular chamber circulates to the cylinder lower chamber, and at that time, a damping force generator for extension stroke and 30 and 32 provided in the piston give a flow resistance to the oil, which causes the damping force. Is generated.

Similarly, in the compression stroke of the piston, the pressure in the cylinder lower chamber 22 is changed to the cylinder upper chamber 20 and the annular chamber 16.
When the internal pressure becomes higher than the internal pressure, a part of the oil in the cylinder lower chamber flows into the cylinder upper chamber and the annular chamber, and at that time, it is converted into oil by the damping force generator for the compression stroke provided in the base valve assembly. A flow resistance is given to the flow resistance, which generates a damping force.

In both the extension stroke and the contraction stroke of the piston, when the spool valve 86 is in the fully closed position shown in FIG. 2, the bypass passage 158 is in the closed state, so that the oil is bypassed. Through the cylinder upper chamber 2
0 and the cylinder lower chamber 22 do not flow, and always pass through the damping force generator provided in the piston and the damping force generator provided in the base valve assembly, and by these damping force generators A high damping force is generated, which causes the shock absorber to operate in the so-called hard mode.

On the other hand, the coil 5 of the step motor 48
4 and the spool valve 86 is switched to the fully open position shown in FIG. 3 or an intermediate position between the fully closed position and the fully open position, the annular port 124 and the lower chamber 146 are connected to the orifice 1
The communication is connected by 48, which allows the bypass passage 15
Since 8 is in the communication state, a part of the oil in the cylinder upper chamber 20 and the cylinder lower chamber 22 flows through each other through the bypass passage, and the damping force generated by the damping force generating device is reduced, whereby the shock is generated. The absorber operates in a so-called soft mode or an intermediate mode between the soft mode and the hard mode depending on the opening position of the spool valve.

In this case, in the extension stroke of the piston, the oil in the cylinder upper chamber 20 passes through the check valve 112 when flowing into the cylinder lower chamber 22 through the bypass passage 158, while the oil is in the compression stroke of the piston. Cylinder lower chamber 2
The oil in 2 passes through the check valve 110, but the check valve 11
Since 0 is not biased by a spring such as spring 114, the damping force generated during the piston's compression stroke is lower than during its extension stroke.

Further, according to the illustrated embodiment, as described above, the spool valve 86 is loosely fitted to the shaft 71, and is held by the compression coil spring 142 at the position where it is in contact with the washer 132. It is urged against the stopper ring 130 along the shaft 71 with a minimum spring force that is sufficient. Therefore, the spool valve 86 can be relatively freely displaced relative to the shaft in the direction across the axis 14, and the compression coil spring 142 substantially causes the valve hole 8 to move.
Since it is not pressed against the wall surface of 8, the spool valve is reciprocated even if these members are assembled with the shaft 71 or the spool valve 86 axis line and the valve hole 88 axis line displaced from each other. The sliding resistance does not increase when the spool valve moves, and the spool valve can smoothly reciprocate along the valve hole.

FIG. 4 is an enlarged partial vertical cross-sectional view showing the connecting structure between the drive shaft of the actuator and the spool valve in the second embodiment of the shock absorber according to the present invention in a state where the spool valve is in the fully open position. Is. 4, the same members as those shown in FIG. 3 are designated by the same reference numerals as those shown in FIG.

In this embodiment, the upper end of the valve hole 88 is enlarged. The compression coil spring 142 that biases the spool valve 86 against the stopper ring 130 along the shaft 71 is a conical coil spring, and
6 is elastically mounted between the upper end of 6 and the lower surface of the bearing support member 62, so that the spool valve 86 can be moved along the shaft 71 with a minimum spring force sufficient to hold the spool valve 86 in the position in contact with the washer 132. The stopper ring 130 is biased.

Therefore, also in this embodiment, the spool valve 86
Is relatively freely displaceable relative to the shaft 71 in a direction transverse to the axis 14, and is substantially not pressed against the wall surface of the valve hole 88 by the compression coil spring 142, so that the shaft or spool valve Even if these members are assembled with the axis and the axis of the valve hole 88 displaced from each other, the sliding resistance when the spool valve reciprocates does not increase, and the spool valve is It can reciprocate smoothly along the hole.

In the extension stroke and the contraction stroke of the piston with the spool valve 86 open, the spool valve 8 is moved by the dynamic pressure of the oil passing through the bypass passage 158.
A fluid force acts on 6 along the axis 14. In the above-described first embodiment, the fluid force is generated as indicated by the broken line A in FIG. 5 with the downward direction in the figure being positive. As can be seen from FIG. 5, there is a region where the fluid force acting on the spool valve has a negative value in the extension stroke of the piston. The positive fluid force acts in a direction to reduce the effective passage cross-sectional area of the orifice 148 by urging the spool valve 86 downward in the figure, whereas the negative fluid force moves the spool valve upward in the figure. When the ball screw device 50, the bearing 58, or the like has play in the axial direction, the fluid force is increased in the extension stroke of the piston. The spool valve vibrates due to the positive and negative fluctuations, which makes it easy for abnormal noise to occur and for the damping force to fluctuate unstablely.

On the other hand, according to the second embodiment, the compression coil spring 142 is elastically mounted between the upper end of the spool valve 86 and the lower surface of the bearing support member 62, and the compression coil spring 142 moves upward in the drawing of the spool valve. The positive spring force B as shown by the phantom line in FIG.
5, the combined force of the fluid force A and the spring force B always has a positive value regardless of the displacement amount of the spool valve as shown by the solid line in FIG.
Even if there is rattling in the bearing 58 or the like, it is possible to reliably prevent the generation of abnormal noise and the unstable fluctuation of the damping force due to the vibration of the spool valve, and to assemble the actuator 46 with high accuracy. It is not necessary, and the durability of the actuator can be improved.

Further, according to the two embodiments shown in the drawings, the end caps 100 and 102 defining the internal space 104, which is a part of the bypass passage 158, are constructed as members separate from the cylindrical body 98. , Check valves 110
The seating surfaces of the end caps 100 and 102 with respect to the end caps 112 and 112 can be easily processed. Can be processed,
This allows the check valve 112 to operate favorably.

In this case, the end cap 100 is the cylindrical body 9
8 and in that case, the number of parts can be reduced to improve the assembly efficiency of the shock absorber, and the outer diameter of the annular port of the passage 106 on the side of the check valve 110 is shown. It is possible to further increase the size as compared with the case of the embodiment described above, whereby the pressure receiving area of the check valve 110 can be increased and the check valve can be opened and closed even better.

According to the two embodiments shown in the drawings, the actuator 46 includes a step motor 48 capable of accurate driving and positioning, and a ball screw device 50 as a motion converting device for converting rotational motion of the step motor into reciprocating motion. Therefore, the spool valve 86 can be accurately driven and positioned as compared with the case where a reciprocating actuator is used.

Although the two embodiments described above are constructed as twin-tube type shock absorbers, the shock absorber according to the present invention may be constructed as a so-called mono-tube type shock absorber.

The actuator in the shock absorber of the present invention is not limited to the actuator having the structure shown in the illustrated embodiment, but may have any structure as long as the valve element can be reciprocated and positioned. You may

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

[0041]

As is apparent from the above description, according to the present invention, the valve body can be displaced relative to the drive shaft in the direction transverse to the axis, and the valve body is urged to the wall surface of the valve hole. Since it is not strongly pressed against the valve shaft, even if the shock absorber components are assembled with the drive shaft or valve body axis line and valve hole axis line displaced from each other, the valve body will not be attached to the valve hole axis line. Therefore, it is possible to smoothly reciprocate along the shaft, and it is possible to reliably avoid an increase in sliding resistance when the valve element is driven, which deteriorates the responsiveness of switching control of the damping force of the shock absorber. The valve body can always be smoothly driven and positioned without causing problems such as an increase in the size of the actuator and an increase in energy consumption due to an increase in the driving force required for the actuator.

Further, since the valve body can always be smoothly driven and positioned without strictly controlling the processing accuracy and the assembly accuracy of the constituent members of the shock absorber, the manufacturing cost of the shock absorber can be reduced. .

Further, as compared with the case where the drive shaft and the valve body are connected to each other by, for example, a ball joint, or the structure in which the valve body is biased against the drive shaft in the direction transverse to the axis by the biasing means, It is possible to reduce the risk of the valve body being pressed against the wall surface of the valve hole when the valve body reciprocates, and to reduce the size of the valve body.

Further, the drive shaft is loosely fitted in a hole provided in the valve body, and the two valve chambers defined on both sides of the valve body have a space between the drive shaft and the valve body. Are connected to each other by means of the conventional shock absorber in order to prevent a pressure difference from occurring between the two valve chambers when the valve body reciprocates in the valve hole. It is possible to omit the passage that connects the two valve chambers, which is provided, so that it is possible to reduce the processing cost and the size of the valve body.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a first embodiment of a shock absorber according to the present invention configured as a twin-tube type shock absorber.

FIG. 2 is an enlarged partial vertical cross-sectional view showing a main part of the piston of the first embodiment with the spool valve in a fully closed position.

FIG. 3 is an enlarged partial vertical cross-sectional view showing a connecting structure between a drive shaft of an actuator and a spool valve in the first embodiment in a state where the spool valve is at a fully open position.

FIG. 4 is an enlarged partial vertical cross-sectional view showing a connecting structure between a drive shaft of an actuator and a spool valve in a second embodiment of the shock absorber according to the present invention in a state where the spool valve is at a fully open position. .

FIG. 5 is a graph showing the relationship between the amount of displacement of the spool valve and the axial force acting on the spool valve.

[Explanation of symbols]

 10 ... Inner cylinder 12 ... Outer cylinder 18 ... Piston 20 ... Cylinder upper chamber 22 ... Cylinder lower chamber 24 ... Piston body 30, 32 ... Damping force generator 34 ... Oil 46 ... Actuator 48 ... Step motor 50 ... Ball screw device 71 ... Shaft 86 ... Spool valve 88 ... Valve hole 94 ... Bypass device 142 ... Compression coil spring 158 ... Bypass passage

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayuki Tsuchiya 1 Toyota-cho, Toyota-cho, Aichi Prefecture Toyota Motor Corporation (72) Ichiro Okada 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Corporation

Claims (1)

[Claims] 1. A cylinder, a piston that reciprocally fits into the cylinder, and cooperates with the cylinder to define an upper chamber and a lower chamber of the cylinder, and a fluid that flows with relative movement of the piston with respect to the cylinder. Means for applying a flow resistance to the working liquid to generate a damping force, a bypass passage provided in the piston for connecting the cylinder upper chamber and the cylinder lower chamber to each other, and a valve provided in the middle of the bypass passage. A hole, a valve body that reciprocally fits in the valve hole along its axis and selectively controls communication or the degree of communication of the bypass passage, and reciprocates the valve body connected to the valve body. An actuator including a drive shaft for positioning, the drive shaft being fitted loosely into a hole provided in the valve body and extending substantially along the axis, and the valve body being biased. By means Damping force control shock absorber, characterized by being urged substantially along the axis relative to the tip of the serial drive shaft.