JPH05302638A - Damping force variable shock absorber - Google Patents

Abstract

PURPOSE:To provide a damping force variable shock absorber where a rotary actuator and a piston rod can be miniaturized and relatively easily manufactured. CONSTITUTION:A rotary actuator 23 is disposed in the vicinity of the tip of a piston rod 4 projected from an inner cylinder 2 and an outer cylinder 3. A ball screw shaft 16 and a ball screw nut 15 are contained inside the piston rod 4 for converting a rotating motion into a linear motion. The ball screw shaft 16 is connected to the rotary actuator 23, while the ball screw nut 15 is connected to a spool valve 5 for opening or closing oil passages 9, 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil damper type shock absorber used in a vehicle suspension or the like, and more particularly to a variable damping force type shock absorber capable of adjusting the damping force by opening and closing an internal valve. Regarding absorbers.

[0002]

2. Description of the Related Art For example, as a shock absorber of a variable damping force used for an automobile suspension, a DC motor is conventionally arranged in a piston rod of the shock absorber, and a rotary for adjusting an oil flow rate in a cylinder. A shock absorber for controlling the oil flow rate between the upper chamber and the lower chamber of a piston by opening and closing the valve by its motor is known from Japanese Patent Laid-Open No. 62-67343.

[0003]

Since this type of shock absorber has a structure in which the motor is built in the piston rod, the built-in portion of the piston rod has a large diameter, and the movement width of the piston is limited. .. In addition, the structure of the piston rod has become very complicated, making its processing and assembly difficult. Furthermore, since this shock absorber uses a rotary valve, in order to change the damping force linearly according to the rotation angle of the valve, a special transfer type opening is provided in the rotary valve 30 as shown in FIG. Since it is necessary to form the portion 31, it is unavoidable to use precision machining such as electric discharge machining, and there is a problem that the manufacturing cost increases.

Further, conventionally, in Japanese Patent Laid-Open No. 3-82355, a rotary drive device composed of two motors or the like is provided at the tip of a piston rod projecting upward from a cylinder of a shock absorber, and 2 is provided in the piston rod. A shock absorber has been proposed in which a rotary shaft of a book is provided, and a compression side disk valve and an expansion side disk valve are connected to the rotary shaft of a piston.

This shock absorber drives an external rotary drive device to move the pressure side disc valve and the extension side disc valve to control the oil flow rate between the upper chamber and the lower chamber in the cylinder to reduce the damping force. Works to adjust. However, since a considerably large torque is required to drive the disk valve, there is no choice but to make the rotary drive large, and there is a problem that it is difficult to install the rotary drive in a limited space in an automobile.

The present invention has been made in view of the above points, and provides a damping force variable shock absorber which allows a rotary actuator and a piston rod to be downsized and which can be manufactured relatively easily. With the goal.

[0007]

In order to achieve the above object, the damping force variable shock absorber of the present invention has a cylinder filled with a working fluid, and one tip of the cylinder protrudes from the cylinder and A piston member that is slidably arranged and divides the inside of the cylinder into an upper chamber and a lower chamber, and a flow path of a working fluid that is disposed inside the piston member and that flows between the upper chamber and the lower chamber is opened and closed. In a variable damping force shock absorber including a valve, a rotary actuator that is disposed between a vehicle body and a tip end portion of the piston member that projects from the cylinder, and that generates a rotational driving force, and is disposed in the piston member. The rotary actuator is connected between the valve and the rotary drive force generated by the rotary actuator is linearly driven by a screw mechanism. That is converted to and a conversion means for transmitting to the valve to its gist.

[0008]

In the variable damping force shock absorber having the above-described structure, when the rotary actuator is driven to rotate, the converting means converts the rotary driving force into the linear driving force by the screw mechanism and transmits the linear driving force to the valve. Due to this linear driving force, the valve opens and closes the flow path of the working fluid that flows between the upper chamber and the lower chamber. When changing the damping force, the damping force is controlled to increase by decreasing the opening of the valve, and the damping force is controlled to decrease by increasing the opening of the valve.

As described above, according to the shock absorber of the present invention, since the screw type conversion mechanism for converting the rotational movement into the linear movement is arranged in the piston rod, the rotational load of the rotary actuator can be reduced. Therefore, the rotary actuator can be downsized. Therefore, it becomes possible to arrange the rotary actuator in a limited space such as an automobile. Also, since only the screw type conversion mechanism is installed in the piston rod, it is not necessary to make the diameter of the piston rod so large, and the volume in the cylinder and the stroke of the piston rod can be sufficiently secured. Easy to process.

Further, since the conversion mechanism for converting into linear motion is used, a valve having a simple structure such as a spool valve that moves linearly can be used as the valve, and the valve can be processed more easily than the conventional rotary valve. It is easy and cheap to manufacture.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sectional view of a shock absorber. This shock absorber is basically
The inner cylinder 2 is inserted into the outer cylinder 1, the piston 3 is slidably inserted into the inner cylinder 2, and the piston rod 4 is inserted into the outer cylinder 1 and the inner cylinder 2 from above, so that the piston rod 4 It is configured by fixing the piston 3 to the lower end.

The piston rod 4 is formed in a pipe shape,
A spool valve 5 and a screw-type conversion mechanism for opening and closing the spool valve 5 are arranged therein. That is, the valve chamber 6 is formed in the lower portion of the piston rod 4, the lower portion of the valve chamber 6 communicates with the lower chamber 7 on the lower side of the piston 3, and the spool valve 5 is fitted in the valve chamber 6 so as to be vertically slidable. Two pairs of oil passages 9 and 10 are formed between the upper chamber 8 and the valve chamber 6 on the upper side of the piston 3.

The spool valve 5 is formed in a tubular shape and has a tapered portion 5a formed at its tip so that the oil flow rate can be changed linearly and in a wide range, and can communicate with the oil passage 10 on both sides of the intermediate side wall. Hole 5b is formed. The lower end of the connecting shaft 11 is fitted into the upper portion of the spool valve 5, and the connecting shaft 1
1 is supported by a bearing portion 13 fixed inside the piston rod 4 so as to be vertically slidable. A seal member 24 is mounted inside the bearing portion 13 to prevent the oil in the cylinder from leaking to the outside through the piston rod due to the pressure during operation.

With the lower end of the connecting shaft 11 fitted in the upper portion of the spool valve 5, the E-clip 12 is fitted in the distal end of the connecting shaft 11, and the compression coil spring 14 is arranged between the spool valve 5 and the bearing portion 13. It Therefore, the advancing of the connecting shaft 11 at the advancing end of the spool valve 5 is allowed to some extent, and the spool valve 5 and the connecting shaft 11 are allowed to rotate about the shaft, whereby the galling and the chewing of the spool valve 5 are allowed. To prevent crowding.

In the piston rod 4 above the bearing 13,
A ball screw nut 15 is arranged so as to be vertically movable and prevented from rotating, and the upper end of the connecting shaft 11 is provided with the ball screw nut 1.
It is fixed to the bottom of 5. At the bottom of the ball screw nut 15, a flat portion 15a having flat side surfaces is formed.
The flat portion 15a enters between the guide portions 13a formed on the upper portion of the bearing portion 13 and is guided (FIG. 3). As a result, the ball screw nut 15 is prevented from rotating within the piston rod 4, and is supported so as to be vertically slidable within a predetermined range.

A ball screw shaft 16 is inserted into the ball screw nut 15 from above and is screwed into the ball screw shaft 16 through a large number of balls. The upper end of the ball screw shaft 16 is connected and fixed to the lower end of the control rod 17 by screwing, press fitting, or the like. The upper portion of the control rod 17 is rotatably supported by a bearing 18 fixed in the piston rod 4.

Further, a male screw portion 17a is formed on an upper portion of the control rod 17 protruding upward from the bearing 18, and a nut 19 is screwed into the male screw portion 17a. The nut 19 is provided to adjust the position of the spool valve 5. By rotating the nut 19 to raise the stationary position of the control rod 17, the position of the spool valve 5 is raised and the stationary position of the control rod 17 is lowered. Thus, the position of the spool valve 5 is lowered. When the position adjustment of the spool valve 5 by the nut 19 is completed, the nut lock agent is applied to the inner peripheral portion of the nut 19, and the nut 19 is fixed to the control rod 17. A sliding member 20 is inserted on the upper surface and the lower surface of the nut 19 in order to smooth the rotational movement thereof.

Therefore, when the control rod 17 supported by the bearing 19 rotates, the ball screw shaft 16 rotates, and the ball screw nut 1 is rotated by the screw mechanism.
5 moves up or down. The vertical movement of the ball screw nut 15 moves the spool valve 5 up and down to open and close the oil passages 9 and 10.

The upper end of the piston rod 4 is covered with a screw cap 21 via a coil spring 22 with the upper end of the control rod 17 protruding upward. The coil spring 22 constantly urges the nut 19 downward through the sliding member 20 to prevent the nut 19 and the control rod 17 from rattling up and down. A flat portion 17b is formed on the upper end of the control rod 17, and the output shaft 23a of the rotary actuator 23 is connected to the flat portion 17b so as to allow only a vertical movement within a certain range and to transmit the rotational movement (Fig. 2). A step motor, a torque motor, or the like is used for the rotary actuator 23.

In the structure for supporting the control rod 17, as shown in FIG. 4, a radial ball bearing 28 is inserted in the piston rod 4, and a fixing ring 29 is press-fitted on the radial ball bearing 28 to press the outer ring of the radial ball bearing 28. Can be fixed to the inner surface of the piston rod, and the control rod 17 can be rotatably supported by the radial ball bearing 28.

The piston 3 of the shock absorber constructed as described above is provided with an orifice, the orifice and a check valve are provided at the bottom of the inner cylinder 2 as in the conventional one, and the outer cylinder 1 and the inner cylinder are further provided. The inside of 2 is filled with oil and gas.

The shock absorber constructed as described above is used, for example, in an automobile suspension. In that case, the rotary actuator 23 located at the upper part is mounted on the upper support fixed to the upper end of the piston rod 4.

Next, the operation of the shock absorber having the above structure will be described.

When changing the damping force of the shock absorber, the rotary actuator 23 is operated, the control rod 17 is rotated, and the ball screw mechanism consisting of the ball screw shaft 16 and the ball screw nut 15 (conversion for converting rotational motion into linear motion) The spool valve 5 is moved up and down via the mechanism) to adjust the opening areas of the oil passages 9 and 10.

That is, when increasing the damping force, the rotary actuator 23 is rotated from the state of FIG. 1 to the side where the ball screw nut 15 is lowered. This rotation is converted into downward movement via the ball screw shaft 16 and the ball screw nut 15, and the spool valve 5 descends via the connecting shaft 11. Due to the lowering of the spool valve 5, the opening areas of the oil passages 9 and 10 are narrowed, and the upper chamber 8 of the piston 3 during operation is reduced.
The oil flow rate between the lower chamber 7 and the lower chamber 7 is reduced, and thereby the damping force is controlled to increase.

On the other hand, when the damping force is reduced, the rotary actuator 23 is rotated from the state shown in FIG. 1 to the side where the ball screw nut 15 is raised. This rotation is converted into upward movement via the ball screw shaft 16 and the ball screw nut 15, and the spool valve 5 rises via the connecting shaft 11. The opening area of the oil passages 9 and 10 is enlarged by the rise of the spool valve 5, and the upper chamber 8 of the piston 3 during operation is
The oil flow rate between the lower chamber 7 and the lower chamber 7 increases, and thereby the damping force is controlled to decrease.

As described above, since the ball screw mechanism for converting the rotary motion into the linear motion is arranged in the piston rod 4, the rotary load of the rotary actuator 23 can be reduced and the rotary actuator 23 can be miniaturized. be able to. Therefore, it becomes possible to arrange the rotary actuator in a limited space such as an automobile. Further, since only the ball screw mechanism is provided in the piston rod 23, it is not necessary to make the diameter of the piston rod so large as in the case of incorporating a conventional actuator, and the volume in the cylinder and the piston Sufficient rod stroke can be secured, and its processing and assembly are easy.

Further, since the valve can be operated by linear movement, the spool valve 5 having a simple structure and easy to process can be used, and the spool valve 5 can be easily provided by providing a taper portion at its tip. The damping force can be linearly controlled.

Further, the movement amount of the spool valve 5 per one rotation of the control rod 17 can be easily adjusted by changing the screw pit of the ball screw mechanism at the time of manufacture, and if the screw lead is made small, it can be made small. Even when the torque rotary actuator is used, the spool valve 5 can be moved within a sufficient range and the damping force can be controlled with a large width.

Since the oil seal in the piston rod 4 can be performed by the seal member 24 of the bearing portion 13 provided on the portion of the connecting shaft 11 which moves linearly, the seal can be surely performed, and the oil seal from below can be achieved. By replenishing oil, the lubricity of the sealing surface is secured, and the durability of the sealing material can be secured well.

Further, since the ball screw mechanism is provided in the piston rod 4, it is not necessary to provide a speed reducing mechanism such as a gear in the rotary actuator 23. Therefore, the speed reducing mechanism conventionally provided in the external rotary actuator is used. Can be eliminated, and the generation of noise due to the reduction mechanism can be prevented.

As shown in FIG. 5, a normal screw mechanism may be used instead of the ball screw mechanism, and a normal control rod male screw portion 17c is attached to a nut portion 25 having a normal female screw hole. It is also possible to screw it into a conversion mechanism that converts rotational movement into linear movement.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a shock absorber showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

3 is an enlarged sectional view taken along the line III-III in FIG.

FIG. 4 is a partially enlarged cross-sectional view of another embodiment.

FIG. 5 is a partially enlarged cross-sectional view of another embodiment.

FIG. 6 is a plan view of a rotary valve used in a conventional shock absorber.

[Explanation of symbols]

1-outer cylinder, 2-inner cylinder, 3-piston, 4-
Piston rod, 5-spool valve (valve), 9, 10
-Oil passage, 15-ball screw nut, 16-ball screw shaft, 23-rotation actuator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masayuki Yano, 1-1, Showa-cho, Kariya city, Aichi prefecture, Nihon Denso Co., Ltd. (72) Inventor, Yasuhiro Harada, 1-1, Showa-cho, Kariya city, Aichi prefecture, Nihon Denso Co., Ltd. Within the corporation

Claims (1)

[Claims] 1. A cylinder filled with a working fluid, and a piston member whose one end projects from the cylinder and is slidably disposed in the cylinder and divides the inside of the cylinder into an upper chamber and a lower chamber. A damping force variable shock absorber provided in the piston member, the valve for opening and closing a flow path of a working fluid flowing between the upper chamber and the lower chamber, wherein a tip of the piston member protruding from the cylinder And a rotary actuator that is arranged between the vehicle body and the vehicle body and that generates a rotary driving force; and a rotary actuator that is arranged inside the piston member, connects the rotary actuator and the valve, and generates a rotary driving force by the rotary actuator. And a conversion means for converting the driving force into a linear driving force by a screw mechanism and transmitting the driving force to the valve. Click absorber.