JP2806236B2 - Variable damping force type shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable damping force type shock absorber, and more particularly, to a damping force variable by moving a spool valve guided by a guide member provided in a housing in an axial direction. The present invention relates to a variable force shock absorber.

[0002]

2. Description of the Related Art As one of variable damping type shock absorbers used for automobiles and the like, for example, Japanese Patent Laid-Open No. 5-601 is disclosed.
There is a configuration as disclosed in Japanese Patent Publication No. 65-65. In the damping force variable shock absorber disclosed in this publication, the damping force is varied by moving a spool valve inserted in a piston sliding in a cylinder in the axial direction. As shown in FIG. 10, the conventional variable damping force type shock absorber has a female screw 3 b of an outer race member 3 a in which a male screw 2 a of a shaft 2 integrally connected to a spool valve 1 is fitted to an inner periphery of a rotor 3. , And a permanent magnet 3 c is fixed to the outer periphery of the rotor 3. Therefore,
When the rotor 3 is driven to rotate by the electromagnetic force from the coil 4a of the stepping motor 4, the female screw 3b rotates by a predetermined angle and the spool valve 1 integrated with the shaft 2 having the screw 2a moves in the axial direction.

The rotor 3 is rotatably supported by bearings 5a and 5b in a cylindrical housing 5. A guide member 6 for guiding the axial movement of the shaft 2 is fitted into an upper portion of the housing 5, and a bearing support member 7 is provided in a lower portion.
Are fitted. At the center of the guide member 6 is provided a guide hole 6a into which a rod 2b extending on the axis of the shaft 2 is fitted. Guide hole 6a and rod 2b
Since each has a rectangular cross section, it also functions as a rotation restricting member that restricts the rotation of the shaft 2.

[0004]

However, in the above-described variable damping force type shock absorber, the precision of each component or the guide member 6 and the bearing support member 7
After welding, the axis of the shaft 2 does not match the axis of the guide member 6 due to distortion or the like at the time of welding, and for example, the rod 2b may be inclined with respect to the guide hole 6a as shown in FIG. . Thus, the shaft 2 is connected to the guide member 6.
, The rod 2b comes into oblique contact with the inner wall of the guide hole 6a, and the lateral force A acts on the rod 2b. Therefore, the external thread 2a of the shaft 2 is inclined with respect to the internal thread 3a of the rotor 3 by the lateral force A, so that the contact pressure with the internal thread 3a increases and the rotational resistance increases.

As a result, in the conventional damping force variable shock absorber, the rotational resistance between the external thread 2a and the internal thread 3a increases and an extra load is applied to the stepping motor 4, so that as shown in FIG. 4 greatly fluctuates, and there is a problem that energy loss when driving the stepping motor 4 is large.

In view of the above problem, an object of the present invention is to prevent the rotational resistance from increasing even when the axis of the shaft does not coincide with the axis of the guide member.

[0007]

According to the present invention, there is provided a cylinder in which hydraulic oil is sealed, the cylinder being slidably fitted in the cylinder, and the hydraulic oil being reciprocated in the cylinder. A piston that receives resistance due to the movement, a spool valve that is inserted into the flow path in the piston, changes the flow path area according to the insertion position and varies the damping force, and is coupled to an end of the spool valve, A shaft having a male screw, an actuator for rotating a rotor having a female screw with which the male screw of the shaft is screwed to move the spool valve in the axial direction, and the rotor being rotatable about the axis of the female screw And a rod extending in the axial direction from the end of the shaft, and a rod provided in the housing to allow the rod to move in the axial direction and restrict rotation about the axis. A guide member having a guide hole in which the rod swingably engages, biasing means for biasing the guide member in a swingable manner, and rotation regulating means for regulating rotation of the guide member. It is characterized by becoming.

[0008]

The guide member provided in the housing is swingably provided to prevent the resistance of the threaded portion from increasing when the axis of the shaft and the axis of the guide member are displaced from each other. By providing rotation restricting means for movably urging and restricting the rotation of the guide member, the rotation of the guide member is prevented, and the rotation of the rotor moves the spool valve in the axial direction.

[0009]

1 to 3 show an embodiment of a variable damping force type shock absorber according to the present invention.

The variable damping force type shock absorber shown in FIG. 1 is a twin tube type shock absorber, and has an internal structure as shown in FIGS. In each of the drawings, reference numeral 10 denotes an inner cylinder, and 12 denotes an outer cylinder, which extend concentrically along an axis 14. Both ends of these cylinders are closed by end caps not shown.

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 able to reciprocate along the axis 14.

The piston 18 has a piston main body 24 for separating the inside of the inner cylinder 10 into an upper cylinder chamber 20 and a lower cylinder chamber 22, and is connected to the main body integrally with the main body. And a piston rod 26 extending along it. Piston body 24
Is fixed to the distal end of the piston rod 26 by a nut 28, and the piston body 24 is provided with a damping force generator 30 for a contraction stroke and a damping force generator 32 for an extension stroke having a known structure. .

Although not shown in FIG. 1, a base valve assembly having a structure known per se is provided below the inner cylinder 10, and the base valve assembly has a contraction stroke and a A damping force generator for the extension stroke is provided.

The cylinder upper chamber 20 and the cylinder lower chamber 2
2. A part of the annular chamber 16 has an oil 34 as a working oil.
Is filled, and a high-pressure gas is sealed in an upper portion of the annular chamber 16. Although not shown in FIG. 1,
The upper end of the piston rod 26 is connected to the vehicle body as a sprung part, and the outer cylinder 12 or the end cap at the lower end is connected to a suspension member (not shown) as a unsprung part.

As shown in FIGS. 2 and 3, the damping force generator 30 is provided in the piston body 24 and connects the upper cylinder chamber 20 and the lower cylinder chamber 22 with each other.
a, a damping force generating valve 30b that abuts on the end surface of the piston body 24 on the cylinder upper chamber 20 side, and a spring 30c that urges the damping force generating valve 30b to a valve closing position shown in the figure. or,
The damping force generating valve 30b is an annular plate-shaped member made of an elastic material, and has a plurality of holes.

The spring 30c is also made of an elastic material.
It has a plurality of arms extending radially from the ring,
The tip of the arm portion comes into contact with the damping force generating valve 30b.

The damping force generator 32 includes a piston body 24
And a connection passage 32a for communicating and connecting the cylinder upper chamber 20 and the cylinder lower chamber 22, and a damping force generating valve 32b abutting on the end face of the piston body 24 on the cylinder lower chamber 22 side.
A spring seat 32c fitted to the upper end of the nut 28 so as to be able to reciprocate along the axis 14, and a spring seat elastically mounted between the spring seat 32c and a spring seat portion provided at the lower end of the nut 28. Compression coil spring 32d for urging valve 32c against damping force generating valve 32b
And

As shown in FIG. 2, the piston rod 26 includes a rod member 42 having a hollow hole 40 extending along the axis 14. A valve housing 44 is fixed to the lower end of the rod member 42 by screwing, and a stepping motor 48 as a rotary actuator and a motion conversion device 50 for converting the rotational motion into a reciprocating motion are provided in the hollow hole 40. Is housed.

The stepping motor 48 includes a coil 54 held by a bobbin 52 and a ball bearing 5 respectively.
And a hollow rotor 66 having a permanent magnet 64 fixed on the outer peripheral surface facing the coil 54, and the rotor 66 rotates around the axis 14 when the coil 54 is energized. It is designed to rotate. The upper ball bearing 56 is fitted on the inner periphery of the rotor 66, and the lower ball bearing 58 is fitted on the outer periphery of the housing 62.

The motion converting device 50 is a screw mechanism, and includes a screw shaft 70 extending along the axis 14 and having a screw 70a on the outer peripheral surface, and a screw shaft 70 fixed to the inner peripheral surface of the rotor 66 on the outer peripheral surface. Female screw 72 into which male screw 70a is screwed
a) and an outer race member 72 having a. Further, the shaft 70 integrally has a shaft 71 extending downward from the lower end thereof along the axis 14 and functioning as a drive shaft.

The motion conversion device 50 and the rotor 66 are
It is housed in a cylindrical housing 73. A spring support 74 is fitted to the upper end of the housing 73, and a bearing support member 62 to which the ball bearing 58 is fitted is fitted to the lower end, and each is fixed by welding. As shown in an enlarged manner in FIG. 4, the spring receiver 74 has a concave portion 74a on the lower surface side with which the coil spring 75 contacts, and a rod 76 extending in the axial direction from the upper portion of the screw shaft 70 contacts the concave portion 74a. Without any gaps.

Reference numeral 77 denotes a guide member which is oscillatably urged by the spring force of a coil spring 75, and as shown in FIG.
a, and has a projection 77b fitted on the inner periphery of the upper ball bearing 56 on the lower surface side, and a rectangular guide hole 77c extending in the radial direction is formed on the bottom surface of the projection 77b. Have been. A rod 76 having a rectangular cross section is inserted into the guide hole 77c to restrict rotation and guide movement in the axial direction and the radial direction.

Therefore, the rod 76 is connected to the guide member 77
And are separated from the spring receiver 74 in a swingable manner. The guide member 77 is pressed against the rotor 66 by the spring force of the coil spring 75 interposed between the guide member 77 and the spring receiver 74. Therefore, the guide member 77 is locked so as not to rotate by the frictional force with the coil spring 75, and the guide hole 77c of the guide member 77 is provided.
The rotation of the rod 76 inserted through the guide member 77 is also restricted via the guide member 77.

As described above, since the rod 76 is swingably supported without any restriction by the spring receiver 74, for example, the accuracy of each component or the spring receiver 74 and the bearing support member 62 are welded to the housing 73. As shown in FIG. 6, the screw shaft 70 after the assembly is completed
When the axis 71 is not aligned with the axis 14 and is in an inclined state, the rod 76 is
The rod 76 can be moved in the axial direction because the rod 76 can be inclined along 7c and does not abut the spring receiver 74 at that time.

Therefore, as shown in FIG. 6, even when the screw shaft 70 is tilted, the guide member 77 is tilted in the same direction as the rod 76, so that the contact pressure at the screw portion does not increase and the rotational resistance does not increase. . That is, the rotation of the rotor 66 by the stepping motor 48 does not hinder the axial movement of the screw shaft 70, and the position of the spool valve 86 can be adjusted smoothly.

FIG. 7 shows a stepping motor 48 according to this embodiment.
FIG. 12 shows the results of an experiment in which the torque fluctuation was measured.
Torque fluctuation is smaller than that of the screw shaft 70).
Can be driven with a relatively small torque. Therefore, the load on the stepping motor 48 can be reduced, power consumption can be saved, and the life of the stepping motor 48 can be extended.

The valve housings 44 are provided with O-rings 78 and 80 for sealing between the valve housing 44 and the wall of the hollow hole 40, respectively. A stopper ring 82 for positioning the bobbin 52 and preventing the bobbin 52 from dropping is fixed to the wall surface of the hollow hole 40.

The valve housing 44 has a rod portion 44a, which projects below the lower end of the rod member 42 along the axis 14. The nut 28 is fixed to the lower end of the rod portion 44a by screwing.

The rod portion 44a has a hollow hole 84 extending along the axis 14, and an upper portion of the hollow hole 84 defines a valve hole 88 for receiving a spool valve 86 reciprocally along the axis 14. I have decided. A stopper 90, a spacer 92, and a bypass device 94 are fixed between the piston main body 24 and the valve housing 44 so as to be fitted to the rod portion 44a.

The bypass device 94 includes an inner cylindrical body 96,
It includes an outer cylinder 98 and end caps 100, 102 disposed at opposite ends thereof, and these members cooperate with each other to form an inner space 104 extending annularly around the axis 14.
Has been demarcated. In the end caps 100 and 102,
A plurality of passages 106 and 108 extending in the vertical direction are provided, respectively, and damping force generating valves 110 and 112 that contact the upper surfaces of the end caps 100 and 102 are provided.

The damping force generating valve 110 is sandwiched between the spacer 92 and the end cap 100 at its radially inner peripheral portion so as to allow only the oil flow from the internal space 104 toward the cylinder upper chamber 20. It has become. On the other hand, the damping force generating valve 112 has a spring 114 at its radially inner peripheral portion.
Further, it is sandwiched between the inner cylindrical body 96 and the piston main body 24 via the spacer 116, and allows only the flow of oil from the cylinder upper chamber 20 to the internal space 104.

The inner cylindrical body 96 has a plurality of radial passages 118 communicating with the internal space 104 and the radial passages 118.
And an annular port 120 communicating therewith. An annular port 120 is provided on the rod portion 44a of the valve housing 44.
A plurality of radial passages 122 communicating with the
An annular port 124 communicating with the valve 22 and opening to the valve hole 88 is provided.

The spool valve 86 has a hollow hole 126 extending in the longitudinal direction thereof, and the diameter of the hollow hole 126 is slightly larger than the diameter of the shaft 71, so that the spool valve 86 has a play in the shaft 71. Fitted in the fitted state.
An annular groove 86 a is provided on the outer periphery of the spool valve 86. An annular groove 128 is provided near the lower end of the shaft 71.
The annular groove 128 is provided with a stopper ring 130. The shaft 71 is provided with an annular groove 134 at a position above the upper end of the spool valve 86, and the annular groove 134 has a stopper ring 136.
Is installed.

Between the spring seat 138 arranged in contact with the stopper ring 136 and the end face of the counter bore 140 provided at the upper end of the spool valve 86, the compression coil spring 142 is fitted to the shaft 71. Is armed. The spring force of the compression coil spring 142 is set to a minimum value sufficient to hold the spool valve 86 at a position in contact with the stopper ring 136 against the fluid force and frictional force acting on the spool valve 86. This allows the spool valve 86 to reciprocate along the shaft 71 as it is reciprocated along the axis 14 by the shaft 71, but relatively freely in the direction transverse to the axis 14.
1 can be relatively displaced.

The spool valve 86 defines an upper chamber 144 and a lower chamber 146 above and below the valve hole 88 so as to cooperate therewith. The chambers 144 and 146 are formed with the counterbore 140, the hollow hole 126 and the shaft 71. , The spool valve 86,
Washer 132, shaft 71, stopper ring 130
Are connected to each other by a clearance passage therebetween. When the lower end of the spool valve 86 is in the fully closed position shown in FIG. 2, the communication between the annular port 124 and the lower chamber 146 is cut off, but as shown in FIG. When driven upward, the annular groove 86a moves to a position facing the annular port 124, and the annular port 12
Variable orifice 148 that connects the lower chamber 4 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 on the cylinder. The chamber 20 and the cylinder lower chamber 22 are communicated and connected, and a bypass passage 158 having a valve hole 88 on the way is defined.
The communication of 58 and the degree of communication are variably controlled by controlling the effective passage sectional area of the orifice 148 by the spool valve 86.

The coil spring 75 of this embodiment serves both as a biasing means and a rotation restricting means.

FIG. 8 shows a modification of the present invention.

In the figure, a coil spring 75 is provided at its upper and lower ends so that locking pins 75a and 75b protrude in the axial direction. The spring receiver 74 is a top plate 74b of the concave portion 74a.
Is provided with a locking hole 74c into which the locking pin 75a of the coil spring 75 is fitted. The guide member 77 has a locking hole 77d in which a locking pin 75b of the coil spring 75 is fitted in a spring receiving portion 77a with which the coil spring 75 contacts.

The urging means of this modification is a coil spring 75, and the rotation restricting means are locking pins 75a, 75b, locking holes 74c,
It consists of a locking hole 77d.

For this reason, in the configuration shown in FIG. 8, the locking pins 75a and 75b are fitted into the locking holes 74c of the spring receiver 74 and the locking holes 77d of the guide member 77, so that the coil spring 75 connects the axis line 14. The rotation about the center is regulated, and the rotation of the guide member 77 is also regulated via the coil spring 75. Therefore, the spring receiver 74, the coil spring 75,
When the guide member 77 is combined, the coil spring 75 is reliably prevented from slipping with respect to the spring receiver 74 and the guide member 77, and the rotational force of the stepping motor 48 is transmitted to the screw shaft 70 without transmission loss. be able to.

FIG. 9 shows another modification of the present invention.

In the drawing, the spring receiver 74 has a locking pin 74d for regulating rotation, which protrudes downward from the peripheral edge of the recess 74a. The locking pin 74 d extends to a position where it engages with the guide member 77, and extends outside the coil spring 75 so as not to contact the coil spring 75.

The guide member 77 has a notch 77e for fitting the locking pin 74d outside a spring receiver 75a with which the coil spring 75 contacts. Therefore, when the spring receiver 74, the coil spring 75, and the guide member 77 are combined, the lower end of the locking pin 74d is fitted into the notch 77e, and the guide member 77 is reliably prevented from slipping with respect to the spring receiver 74. , The stepping motor 48
Screw shaft 70 with no transmission loss
Can be transmitted to

The urging means of this modification comprises a coil spring 75, and the rotation restricting means comprises a locking pin 74d and a notch 77e.

In the above embodiment, a variable damping force type shock absorber used in an automobile has been described as an example. However, the present invention is not limited to this, and the present invention may be applied to a shock absorber other than an automobile. Of course you can.

In the above embodiment, the spool valve is moved by using the stepping motor. However, a motor other than the stepping motor or another actuator may be used.

[0048]

As described above, in the variable damping force type shock absorber according to the present invention, the guide member for guiding the rod provided integrally with the shaft is provided so as to be swingable.
Rotation restricting means for preventing the resistance of the threaded portion from increasing when the axis of the shaft and the axis of the guide member are displaced, further urging the guide member to swing, and restricting the rotation of the guide member. With this arrangement, the rotation of the guide member is prevented, and the rotational driving force of the actuator is transmitted without loss, so that the shaft integrated with the spool valve can be moved in the axial direction to vary the damping force. Thus, the spool valve can be smoothly moved in the axial direction, the rotational load of the rotor can be reduced, the torque fluctuation of the actuator can be reduced, and the life of the actuator can be prolonged.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of a variable damping force type shock absorber according to the present invention.

FIG. 2 is a longitudinal sectional view for explaining an internal configuration of a piston rod.

FIG. 3 is a longitudinal sectional view for explaining the operation of the spool valve.

FIG. 4 is a longitudinal sectional view for explaining a main part of the present invention in an enlarged manner.

FIG. 5 is a diagram for explaining a guide member.

FIG. 6 is a longitudinal sectional view showing a state where a screw shaft and a guide member are inclined.

FIG. 7 is a graph showing torque characteristics of a stepping motor.

FIG. 8 is a view showing a modification of the guide member.

FIG. 9 is a view of another modified example of the guide member.

FIG. 10 is a longitudinal sectional view for explaining a conventional configuration.

FIG. 11 is a longitudinal sectional view showing a state in which a screw shaft and a guide member are inclined in a conventional configuration.

FIG. 12 is a graph showing torque characteristics of a conventional stepping motor.

[Explanation of symbols]

 Reference Signs List 10 inner cylinder 12 outer cylinder 14 axis 18 piston 20 upper cylinder chamber 22 lower cylinder chamber 24 piston body 26 piston rod 30, 32 damping force generator 48 stepping motor 50 motion converter 54 coil 66 rotor 70 screw shaft 74 spring receiver 75 coil Spring 76 Rod 77 Guide member 86 Spool valve 94 Bypass device 110, 112 Damping force generating valve 148 Variable orifice 158 Bypass passage

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16F 9/00-9/58 B60G 13/08 F16H 25/12 F16K 31/04

Claims (1)

(57) [Claims] 1. A cylinder in which hydraulic oil is sealed, a piston slidably fitted in the cylinder, and a piston which receives resistance due to the movement of the hydraulic oil as it reciprocates in the cylinder. A spool valve that is inserted into the flow passage in the piston and changes the flow passage area according to the insertion position to vary the damping force; a shaft coupled to an end of the spool valve and having a thread on the outer periphery; An actuator for rotationally driving a rotor having a female screw with which a male screw of a shaft is screwed to move the spool valve in the axial direction; a housing for rotatably supporting the rotor about the axis of the female screw; and the shaft. A rod extending in the axial direction from the end of the rod; and a rod provided in the housing to allow the rod to move in the axial direction and to restrict rotation about the axis. A guide member having a guide hole that movably engages; an urging means for urging the guide member to swing; and a rotation restricting means for restricting rotation of the guide member. Variable damping force type shock absorber.