JP2000027922A - Actuator device for shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a machining cost of a damping force variable type actuator device for a shock absorber. SOLUTION: A screw shaft 11 is threadedly engaged with the screw hole 9 of a rotatably nut member 7 incorporated at the internal part of a housing 2 and a magnet 21 is mounted on the outer periphery of a nut member 7. A stator 22 of which a stepping motor 20 consists in cooperation with the magnet 21 is mounted on the outer periphery of the housing 2. The magnet 21 is arranged above the forming portion of the screw hole 9, an oil pressure release hole 24 to release the oil pressure of the closed end part of the screw hole 9 to the interior of the housing 2 is formed between the closed ends of the magnet 21 and the screw hole 9 and machining is facilitated.

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 actuator for a shock absorber used mainly in automobiles.

[0002]

2. Description of the Related Art FIG. 4 shows a known shock absorber actuator device of a variable damping force type. In this shock absorber actuator device, a housing 31 communicating with the inside of the piston at a lower end is mounted inside a piston 30 slidable in a cylinder filled with oil, and two bearings mounted inside the housing 31 are provided. The upper and lower ends of the nut member 33 are rotatably supported by 32a and 32b, a screw shaft 35 is screwed into a screw hole 34 formed in the nut member 33, and the nut member 33 is rotated by a stepping motor 36. Then, the screw shaft 35 is moved in the axial direction, and the damping force is adjusted by controlling the oil flow rate by moving the spool valve 37 attached to the lower end of the screw shaft 35 in the axial direction.

[0003] The stepping motor 36 comprises a magnet 38 and a stator 39.
Is attached to the outer periphery of the nut member 33, and the stator 39 is attached to the outer periphery of the housing 31.
, The stator 39 is excited to rotate the magnet 38.

[0004] In the actuator device for a shock absorber having the above configuration, oil is sealed in the closed end of the screw hole 34 in order to lubricate the screw engaging portion between the nut member 33 and the screw shaft 35.

Here, if the oil is kept sealed, the oil is compressed when the screw shaft 35 moves toward the closed end side of the screw hole 34, and the rotational resistance of the nut member 33 is increased, so that the nut member 33 is rotated. Does not rotate smoothly, the position of the spool valve 37 cannot be adjusted, and the damping force of the shock absorber cannot be adjusted accurately.

Further, the load on the stepping motor 36 also increases, causing seizure and failure.

In order to solve such a problem, in a shock absorber actuator device shown in FIG. 4, a vertical hole 40 is formed in a screw shaft 35 in an axial direction from an upper end thereof.
A radial horizontal hole 41 communicating with the vertical hole 40 is formed to communicate the inside of the housing 31 with the closed end of the screw hole 34, and the oil at the closed end of the screw hole 34 is supplied to the housing 31.
I try to miss it.

[0008]

In the above-described actuator for a shock absorber, a screw shaft 35 having a small shaft diameter is formed with a vertical hole 40 long in the axial direction and a horizontal hole 41 in the radial direction. Since the structure is designed to release the hydraulic pressure at the closed end of the above, there is a problem that the processing is extremely troublesome and the cost is high.

It is an object of the present invention to reduce the processing cost of an actuator device for a variable damping force type shock absorber.

[0010]

In order to solve the above-mentioned problems, according to the present invention, a housing is mounted in a piston having a hollow inside, and a lower end is attached to a nut member rotatably provided in the housing. A screw shaft for damping force adjustment is screw-engaged with a screw shaft mounted on the lower end of the screw hole, and a magnet is attached to the outer periphery of the nut member. In the actuator device for a shock absorber in which a stator that forms a motor with the magnet is excited, the stator is excited to rotate the nut member, and the screw shaft is moved in the axial direction. A configuration in which a hydraulic pressure relief hole communicating the closed end with the inside of the housing is formed.

Here, it is preferable that the hydraulic relief hole is provided with a magnet of a motor mounted above a screw hole formed in a nut member, and the hydraulic relief hole is provided between the magnet and a closed end of the screw hole. In this case, as the hydraulic pressure relief hole, one having a configuration including a radial through hole provided between the magnet and the closed end of the screw hole, and an axial hole communicating from the closed end of the screw hole to the through hole is used. Can be adopted.

As described above, by mounting the magnet of the motor at a position shifted above the screw hole of the nut member, the hydraulic relief hole communicating the closed end of the screw hole and the inside of the housing has a large shaft diameter. It can be formed in the nut member, and the hydraulic relief hole can be easily formed.

Here, in order to rotate the nut member smoothly, it is preferable that the nut member is formed of synthetic resin to reduce the frictional resistance at the screw engagement portion between the nut member and the screw shaft. Examples of the synthetic resin include a polyimide resin.

Further, in order to reduce the frictional resistance of the screw engagement portion between the nut member and the screw shaft, a female screw formed on the inner periphery of the nut member and a male screw provided on the outer periphery of the screw shaft are advanced. It is preferable to make line contact at two points in the direction.

As a method of making line contact, there is a method in which the cross-sectional shape of one of the female screw and the male screw is made semicircular, and the screw groove between the other screw threads is formed by two inclined surfaces inclined in opposite directions. it can.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG.
Is slidably provided in a cylinder (not shown) in which oil is sealed.

The piston 1 is hollow inside, and a housing 2 is mounted in the hollow portion. Housing 2
Is connected to a sleeve 3 made of a synthetic resin whose upper part is closed, a holding ring 4 attached on the outer periphery of the large-diameter cylindrical portion 3a below the sleeve 3, and a connecting pin 5 to the holding ring 4. The holding ring 4 is press-fitted into the inner surface of the piston 1.

A nut member 7 is incorporated in the housing 2. The nut member 7 includes a bearing 8a mounted on the upper inside of the sleeve 3 and a bearing 8b mounted on the lower ring 6.
The upper and lower ends are rotatably supported by these.

The nut member 7 has a screw hole 9 opened at the lower end, and a female screw 10 formed on the inner periphery of the screw hole 9 and a male screw 12 provided on the outer periphery of the rear end of the screw shaft 11.
Are engaged by screws.

As shown in FIG. 2, the female screw 10 has a semicircular cross section, while the screw groove between the male screws 12 is formed by two inclined surfaces 12a which are inclined in opposite directions. Are in line contact at two points in the direction of travel of the screw.

The axial movement of the screw shaft 11 is limited by a stopper ring 13 inserted inside the lower ring 6. The screw shaft 11 is movably supported in the axial direction by a guide ring 14 inserted inside the lower ring 6, and is inserted into an axial guide groove 14 a formed on the inner periphery of the guide ring 14. The screw shaft 11 is prevented from rotating by fitting the guide pin 11a and the guide groove 14a.

The stopper ring 13 and the guide ring 14 are attached to the lower ring 6 by crimping the lower end of the lower ring 6 inward.

A spool valve 15 is attached to the screw shaft 11 at a distal end portion which is located outside through a guide ring 14. The spool valve 15 moves in the axial direction together with the screw shaft 11, and adjusts the damping force by adjusting the oil flow rate in the same manner as the spool valve described in JP-A-7-167192.

The nut member 7 is a stepping motor 2
Rotated by zero. Here, as the motor 20,
To position the spool valve 15 with high accuracy, a stepping motor is employed. The stepping motor 20 includes a magnet 21 mounted on the nut member 7.
And a stator 22 mounted on the outer diameter surface of the sleeve 3.
Consisting of

Here, the magnet 21 is connected to the nut member 7.
Is mounted above the female screw forming portion. At the time of attachment, the nut member 7 is molded with a synthetic resin such as a polyimide resin, and the magnet 21 is integrated with the molding at the same time.

The stator 22 has a plurality of cores 22a mounted on the outer diameter surface of the sleeve 3 and coils 22b wound on the respective cores 22a. And the terminal holding member 23 fitted to the rear end of the sleeve 3 prevents the terminal 3 from moving in the axial direction.

The nut member 7 is provided with a hydraulic pressure relief hole 24 communicating between the closed end of the screw hole 9 and the inside of the large-diameter cylindrical portion 3a of the sleeve 3. The hydraulic relief hole 24 includes a radial through hole 24 a provided between the magnet 21 and the closed end of the screw hole 9, and an axial hole 24 b communicating from the closed end of the screw hole 9 to the through hole 24 a. ing.

The nut member 7 is formed with a square shaft portion 7a at a position facing the small-diameter hole 6a of the lower ring 6, and is provided between the square shaft portion 7a and the inner peripheral surface of the small-diameter hole 6a. Further, an oil passage 25 is provided as shown in FIG. The oil passage 25 communicates with a steal 26 formed at the closed end of the large-diameter hole 6 b of the lower ring 6.

When the coil 22b of the stator 22 is energized, the nut member 7 rotates together with the magnet 21.
The screw shaft 11 that is screw-engaged with the nut member 7 moves in the axial direction. The spool valve 15 moves together with the axial movement of the screw shaft 11 to adjust the damping force.

When the screw shaft 11 moves toward the closed end of the screw hole 9, the oil sealed in the closed end of the screw hole 9 flows from the hydraulic relief hole 24 through the large-diameter cylindrical portion of the sleeve 3. 3a, flows through the oil passage 25, the steal 26, and the bearing 8b from the large-diameter cylindrical portion 3a, and furthermore, the axial groove 13a and the guide groove of the guide ring 14 formed on the inner diameter surface of the stopper ring 13. Piston 1 flowing to 14a
Inflow inside.

As described above, the oil in the closed end of the screw hole 9 flows smoothly into the piston 1, so that the rotational resistance of the nut member 7 does not increase, and the failure of the stepping motor 20 due to seizure or the like is prevented. It can be prevented beforehand.

[0032]

As described above, according to the present invention, since the hydraulic relief hole communicating the closed end of the screw hole and the inside of the housing is formed in the nut member, the hydraulic relief hole is formed in the screw shaft. In comparison with the above, machining is easier, machining cost can be reduced, and a hydraulic relief hole having a large passage diameter can be formed, so that the hydraulic pressure at the closed end of the screw hole can be smoothly released. .

Further, by forming the nut member from a synthetic resin molded product, the magnet can be integrated at the time of molding the nut member, thereby facilitating assembly.

Further, by making the female screw of the nut member and the male screw of the screw shaft come into line contact at two points, the contact resistance at the screw engaging portion is small, the load on the motor for rotating the nut member is reduced, and the burning of the motor is reduced. Sticking and the like can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an actuator device according to the present invention.

FIG. 2 is an enlarged cross-sectional view of the screw engaging portion of the above.

FIG. 3 is a sectional view taken along the line III-III in FIG. 1;

FIG. 4 is a sectional view showing a conventional actuator device for a shock absorber.

[Explanation of symbols]

 Reference Signs List 1 piston 2 housing 9 screw hole 11 internal thread 12 external thread 12a slope 15 spool valve 20 stepping motor 21 magnet 22 stator 24 hydraulic relief hole 24a through hole 24b hole

Claims (6)

[Claims] A housing is mounted in a piston having a hollow inside, and a nut member rotatably provided in the housing is formed with a screw hole opening at a lower end, and the screw hole has a screw hole for adjusting damping force. The spool valve is screw-engaged with a screw shaft mounted at the lower end, a magnet is attached to the outer periphery of the nut member, and a stator that forms a motor with the magnet is attached to the outer periphery of the housing, and the stator is excited. In the actuator device for a shock absorber in which the nut member is rotated to move the screw shaft in the axial direction, the nut member has a hydraulic relief hole communicating the closed end of the screw hole and the inside of the housing. An actuator device for a shock absorber, characterized in that: 2. The motor according to claim 1, wherein the magnet of the motor is mounted above a screw hole formed in a nut member, and the hydraulic relief hole is provided with a radial through hole provided between a closed end of the magnet and the screw hole; An actuator device for a shock absorber, comprising an axial hole communicating with the through hole from a closed end of the hole. 3. The actuator device for a shock absorber according to claim 1, wherein the nut member is a molded product of a synthetic resin, and a magnet is integrated at the time of molding. 4. The actuator device for a shock absorber according to claim 3, wherein the synthetic resin is made of a polyimide synthetic resin. 5. The screw according to claim 1, wherein the female screw formed on the inner periphery of the nut member and the male screw provided on the outer periphery of the screw shaft are in linear contact with each other at two points in the traveling direction of the screw. The actuator device for a shock absorber according to the above. 6. The female thread of the nut member and the male thread of the screw shaft have one semi-circular cross-sectional shape, and a thread groove between the other threads is formed by two inclined surfaces inclined in opposite directions. The actuator device for a shock absorber according to claim 5, wherein the actuator device is in line contact with a point.