JPH0567804U - Dustproof device - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent dust from entering the drive source side without reducing the efficiency of the drive source. [Structure] Between the inner surface of a through hole 22B communicating with the inside of the direct acting stepping motor 20 and the inside of the flow rate control valve 10 and the outer peripheral surface of the direct acting shaft 3 that directly moves within the through hole 22B,
The dustproof space 43, which is made of a material that allows the hydraulic oil in the through hole 22B to pass but does not allow dust to pass, is arranged in a state of being appropriately bent so as to absorb the relative displacement between the passage 22B and the linear motion shaft 3. .. [Effect] Since the hydraulic oil moves through the dustproof film 43, the differential pressure on both sides of the dustproof film 43 does not increase and the axial thrust is not generated, and the dust to the direct acting stepping motor 20 side is not generated. Intrusion is prevented.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention is a dustproof device that prevents dust from entering from a fluid pressure device side such as a flow control valve that constitutes a hydraulic circuit to a drive source side such as a direct-acting stepping motor integrally provided in the fluid pressure device. With regard to the device, in particular, it is possible to prevent dust from entering the drive source side without lowering the efficiency of the drive source.

[0002]

[Prior Art]

 As a conventional dustproof device used for hydraulic equipment or the like, there is, for example, a device shown in FIG. 7 or 8. FIG. 7 shows an example in which the dust seal 1 is used as a dustproof device, in which the ring-shaped dust seal 1 made of an elastic body is fixed to the inner surface of the passage 2 and is formed on the inner peripheral surface of the dust seal 1. The lip 1a is brought into contact with the outer peripheral surface of the linear motion shaft 3 which linearly moves in the passage 2.

As a result, even if the direct drive shaft 3 moves directly, the lip 1a comes into close contact with the outer peripheral surface of the direct drive shaft 3, so that a drive source (not shown) is provided through the gap between the passage 2 and the direct drive shaft 3. Dust is prevented from entering the side. On the other hand, FIG. 8 shows an example in which the dust boot 4 is used as a dustproof device, in which one opening of the dust boot 4 formed by molding an elastic body into a bellows-shaped cylinder is used as a linear shaft 3. The dust boot 4 is fixed to the outer peripheral surface thereof, and the other opening of the dust boot 4 is fixed to the housing 5 side forming the passage 2.

As a result, the gap between the passage 2 and the linear motion shaft 3 is isolated from the outside, so that dust can be prevented from entering the drive source side (not shown).

[0005]

[Problems to be solved by the device]

 Certainly, even a dustproof device including the dust seal 1 and the dust boot 4 can prevent dust from entering, but when these conventional dustproof devices are used in a fluid, the lip 1a and the dust boot are prevented. Axial thrust is generated due to imbalance of fluid pressures on both sides of the shaft 4, and this acts as an operating resistance of the linear motion shaft 3, resulting in a decrease in efficiency of the drive source and the like. In addition, in the dust seal 1, the lip 1a is attached to the linear drive shaft 3 with a relatively strong force so that the dust can be prevented from entering even if the fluid pressure difference on both sides of the lip 1a is large. Since it is necessary to bring them into contact with each other, a large contact resistance is generated between the lip 1a and the linear motion shaft 3, and this also becomes an operating resistance of the linear motion shaft 3.

The present invention has been made by paying attention to the unsolved problem of such a conventional technique, and prevents dust from entering the drive source side without causing a reduction in efficiency of the drive source. An object of the present invention is to provide a dustproof device that can be used.

[0007]

[Means for Solving the Problems]

 To achieve the above object, a dustproof device according to the present invention is provided with an inner surface of a passage that communicates with the inside of a drive source and the inside of a fluid pressure device and in which a fluid is sealed, and the drive source disposed inside the passage. From the above to the outer peripheral surface of the linear motion shaft that transmits the linear motion displacement to the movable part of the fluid pressure device, a dust-proof film made of a material that allows fluid to pass but does not allow dust to pass through the passage and the linear motion shaft. It is arranged so as to be able to absorb the relative displacement between the two.

[0008]

[Action]

 According to the present invention, since the dust-proof film disposed between the inner surface of the passage and the outer peripheral surface of the linear motion shaft allows the fluid to pass therethrough, the flow of fluid through the dust-proof film causes the dust-proof film. The imbalance of fluid pressure on both sides of the pin is eliminated and the generation of axial thrust is prevented. Further, since the dustproof film does not allow dust to pass therethrough, dust is prevented from entering from the fluid pressure device side to the drive source side.

Further, since the dustproof film is arranged between the inner surface of the passage and the outer peripheral surface of the linear motion shaft so as to be able to absorb the relative displacement between the passage and the linear motion shaft, the dustproof film and the linear motion shaft are There is no sliding resistance between them. As a structure that can absorb the relative displacement between the passage and the linear motion shaft, for example, the dustproof film itself may be formed of an elastically deformable material, or the dustproof film may have a bellows shape or a diaphragm shape. Be done. Even if the dustproof membrane itself is a material or shape that does not deform, if a diaphragm or the like is provided between the dustproof membrane and the linear motion shaft or between the dustproof membrane and the inner surface of the passage, the relative displacement is absorbed as a whole. can do.

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 to 3 are views showing a first embodiment of the present invention, in which a dust control device according to the present invention is used as a flow control valve 10 as a fluid pressure device and a direct-acting stepping motor as a drive source. The present invention is applied to a flow control valve 50 with a direct drive motor, which is integrated with 20 and is incorporated in, for example, a hydraulic power steering device for a vehicle.

First, the configuration will be described. The flow control valve 10 is composed of a valve cylinder 11 whose one opening side is sealed with a cap 12 and a spool 13 which slides in the valve cylinder 11 in the axial direction (left and right direction in FIG. 1). Ports 11A and 11B are opened at 180 degrees in the circumferential direction in the valve cylinder 11, and a circumferential groove 13A continuous in the circumferential direction is formed on the outer peripheral surface of the spool 13.

Therefore, the facing area of the ports 11A, 11B and the circumferential groove 13A changes depending on the axial position of the spool 13, so that the flow rate of the fluid flowing between the ports 11A and 11B becomes variable. On the other hand, the direct acting stepping motor 20 is a known permanent magnet type (PM type: Permanent Magnet Type) stepping motor, in which a top housing 22 and an end housing 23 are fitted into both openings of a cylindrical housing 21, A motor housing 26 is constructed by fastening the top housing 22 and the end housing 23 with bolts 24 and nuts 25. It should be noted that O-rings 27a and 27b are provided between the cylindrical housing 21 and the top housing 22 and the end housing 23 to enhance the sealing performance between them.

On the surface of the top housing 22 facing the inside of the motor housing 26, a cylindrical portion 22 A is integrally formed coaxially with the cylindrical housing 21, and the central portion of the top housing 22 communicates the inside and outside of the motor housing 26. A through hole 22B that is long in the axial direction as a passage is formed. The through hole 22B is formed to have a relatively small diameter inside the columnar portion 22A and a relatively large diameter outside thereof.

Further, the columnar portion 22A of the top housing 22 is press-fitted into the opening side of a cylindrical stainless steel hermetic container 28 whose end housing 23 side is sealed. An O-ring 27c is provided between the columnar portion 22A and the hermetic container 28 to enhance the hermeticity between them. Inside the hermetic container 28, cylindrical end retainers 30a and 30b are supported by bearings 29a and 29b and are rotatably arranged coaxially with the cylindrical housing 21, and the outer peripheral sides of these end retainers 30a and 30b are arranged. A permanent magnet 31 is connected to the inner side of the center retainer 32, and a thin-walled cylindrical center retainer 32 is connected to the inner side by a plurality of spring pins 33 in the rotating direction. In addition, the spring pin 33 is formed by notching the peripheral surface of the cylindrical pin in parallel with the axis so that the elastic force in the expanding direction generated when the diameter of the spring pin is reduced does not rattle the two members. A pin that can be connected.

On the other hand, a coil 34 capable of supplying a control current from the outside of the motor housing 26 is wound around the outer peripheral surface of the hermetically sealed container 28 so as to surround the permanent magnet 31. The motor is configured. Further, the opening side of the valve cylinder 11 of the flow rate control valve 10 is fixed to the surface of the top housing 22 facing the outside so that the spool 13 is positioned coaxially with the through hole 22B, whereby the through hole 22B is formed. Forms a space from the inside of the flow control valve 10 to the inside of the direct-acting stepping motor 20, and the direct-acting shaft 3 is arranged inside this space.

The linear motion shaft 3 has one end coupled to the spool 13 by a spring pin 35 and the other end inserted inside the center retainer 32, and the portion surrounded by the center retainer 32 is more than the other portion. The large-diameter portion 3a has a large diameter, and a spiral groove 3b that is spirally continuous is formed on the outer peripheral surface of the large-diameter portion 3a. The center retainer 32 holds a ball 36 that can roll in the spiral groove 3b so as to be rotatable. A cylindrical member 37 that prevents the balls 36 from falling off is externally fitted to the outer peripheral surface of the center retainer 32.

Therefore, when a control current is supplied to the coil 34 and a rotational force is applied to the permanent magnet 31, the center retainer 32, which is integral with the permanent magnet 31 in the rotation direction, rotates and is retained by the center retainer 32. Although the ball 36 rolls in the spiral groove 3b while rotating on its own axis, the ball 36 is held by the center retainer 32 and cannot be displaced in the axial direction, so an axial forward / backward force is generated in the linear motion shaft 3. As a result, the spool 13 of the flow control valve 10 slides in the valve cylinder 11, and the flow rate of the working oil passing through the flow control valve 10 changes.

Here, the inside of the through hole 22 B and the inside of the hermetically sealed container 28 do not have an adverse effect on the hydraulic circuit side even if hydraulic oil flows in from the gap between the valve cylinder 11 of the flow control valve 10 and the spool 13. In advance, fill with hydraulic oil. The hydraulic oil sealed inside the sealed container 28 also acts as lubricating oil for the rolling elements such as the bearings 28a and 28b and the balls 26.

There is a high possibility that dust is mixed in the hydraulic oil flowing into the through hole 22B from the flow control valve 10 side, and when the dust enters the direct acting stepping motor 20 side, the bearing Since there is a risk of hindering the rolling of the balls 28a, 28b, the balls 26, etc., a dustproof device 40 is provided inside the through hole 22B in order to prevent such dust from entering.

FIG. 2 is an enlarged view of the dustproof device 40. The dustproof device 40 includes an elastic member fitted in a circumferentially continuous circumferential groove 3 A formed on the outer circumferential surface of the linear shaft 3. The elastic ring 41 is formed on the inner peripheral surface of the through hole 22B, and the elastic ring 41, the retaining ring 41a that applies a force in the direction of reducing the diameter of the elastic ring 41 to prevent the elastic ring 41 from falling off the peripheral groove 3A. The elastic ring 42 made of an elastic member fitted in the circumferential groove 22C continuous in the circumferential direction, and a force in the direction of expanding the diameter of the elastic ring 42 are applied to prevent the elastic ring 42 from coming off the circumferential groove 22C. And a dustproof film 43 interposed between the elastic rings 41 and 42.

As shown in FIG. 3 which is a perspective view of the dustproof film 43, the dustproof film 43 has a cylindrical shape in which the opening on the elastic ring 41 side is narrowed. The dustproof film 43 and the elastic rings 41, 42 are integrally molded by inserting both openings of the dustproof film 43 into a mold for molding the elastic rings 41, 42. The dust-proof film 43 is a net-like film that has elasticity and allows the hydraulic oil to pass through, but does not allow dust mixed in the hydraulic oil to pass through.

The axial dimension of the dustproof film 43 is such that even if the linear motion shaft 3 moves most in the direction of insertion into the valve cylinder 11, the dustproof film 43 does not have an elastic restoring force. And Next, the operation of this embodiment will be described. When a pulse current is supplied to the coil 34 of the direct acting stepping motor 20, the permanent magnet 31 rotates by an angle corresponding to the direction of the pulse current and the number of pulses, and the center retainer 32, which is integrated with the permanent magnet 31 in the rotation direction, rotates. To do.

Then, the ball 36 held by the center retainer 32 rolls in the spiral groove 3b, whereby the rotational force of the center retainer 32 is converted into a linear motion, and the linear shaft 3 moves linearly. .. As a result, the axial position of the spool 13 coupled to the direct acting shaft 3 changes, so the communication area between the ports 11A and 11B and the circumferential groove 13A changes, and the hydraulic oil passing through the flow control valve 10 is changed. The flow rate is controlled.

When the linear movement shaft 3 moves linearly, the axial position of the dustproof film 43 changes, and the volumes of the spaces on both sides of the dustproof film 43 fluctuate. Because of the movement, there is no imbalance in the internal pressures of the spaces on both sides, and even when the linear motion shaft 3 moves most in the direction of insertion into the valve cylinder 11, no elastic restoring force is generated in the dustproof film 43. Axial thrust that reduces the drive efficiency of the direct drive stepping motor 20 does not occur.

When the linear drive shaft 3 is displaced in the direction of coming out of the valve cylinder 11, the dustproof net 43 is bent, but the bending is accommodated in the through hole 22B having a relatively large diameter. Since it is absorbed and absorbed, it does not interfere with the forward / backward movement of the linear motion shaft 3. Further, even if dust enters the through hole 22B through the gap between the valve cylinder 11 and the spool 13, the dust-proof film 43 is a net-like film that allows the hydraulic oil to pass but does not allow the dust to pass. It is possible to prevent dust from entering the inside of the bearing, and the rolling performance of the bearings 29a and 29b and the balls 36 is not deteriorated. The operability, reliability and durability of the direct drive stepping motor 20 are secured. To be done.

FIG. 4 is a view showing a second embodiment of the present invention, and is an enlarged view of the dustproof device 40 as in FIG. 3 of the first embodiment. That is, in this embodiment, the elastic ring 41 is provided with a sufficient elastic force in the diameter reducing direction and the elastic ring 42 is provided with an elastic force in the diameter expanding direction, which is used in the first embodiment. The retaining rings 41a and 42a are omitted. This has the advantage of reducing the number of parts. Other functions and effects are similar to those of the first embodiment.

FIG. 5 is a view showing a third embodiment of the present invention, which is also an enlarged sectional view of the dustproof device 40. That is, in this embodiment, by forming the dustproof film 43 into a bellows shape, the dustproof film 43 can be relatively expanded and contracted, and the relative displacement between the linear drive shaft 3 and the through hole 22B can be absorbed. It is a thing.

With such a configuration, there is an advantage that a large relative displacement between the linear drive shaft 3 and the through hole 22B can be absorbed. Other functions and effects are similar to those of the first embodiment. FIG. 6 is a view showing a fourth embodiment of the present invention, which is also an enlarged sectional view of the dustproof device 40.

That is, in the present embodiment, the dustproof film 43 is formed in a diaphragm shape so that the dustproof film 43 can be relatively expanded and contracted. With such a configuration, it is possible to absorb a large relative displacement between the linear motion shaft 3 and the through hole 22B, and there is an advantage that it can be incorporated into a mechanism having no space. Other functions and effects are similar to those of the first embodiment.

In each of the above embodiments, the dustproof device according to the present invention is applied to the flow control valve 50 with a direct drive motor, but the present invention is applied to the device of this type. It is not limited to. In addition, in each of the above-described embodiments, by using an elastic material for the dustproof film 43 or by making it expandable and contractible, a structure capable of absorbing the relative displacement between the linear motion shaft 3 and the through hole 22B is realized. However, for example, even if the dustproof film 43 itself does not elastically deform, a diaphragm or the like is provided between the dustproof film 43 and the outer peripheral surface of the linear motion shaft 3 or between the dustproof film 43 and the inner peripheral surface of the through hole 22. By interposing, the relative displacement between the linear motion shaft 3 and the through hole 22B may be absorbed.

[0031]

[Effect of the device]

 As described above, according to the present invention, a dust-proof film that allows fluid to pass but does not allow dust to pass between the inner surface of the passage and the outer peripheral surface of the linear drive shaft is subjected to relative displacement between the passage and the linear drive shaft. Since it is arranged so as to be able to absorb, the axial thrust that reduces the efficiency of the drive source is not generated, and dust is prevented from entering the drive source side.

[Brief description of drawings]

FIG. 1 is a sectional view showing the overall configuration of a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the first embodiment.

FIG. 3 is a perspective view of a dustproof film.

FIG. 4 is a cross-sectional view showing the main parts of the second embodiment.

FIG. 5 is a cross-sectional view showing the main parts of the third embodiment.

FIG. 6 is a sectional view showing an essential part of a fourth embodiment.

FIG. 7 is a cross-sectional view showing a conventional configuration.

FIG. 8 is a cross-sectional view showing a conventional configuration.

[Explanation of symbols]

3 direct acting shaft 10 flow control valve (fluid pressure equipment) 20 direct acting type stepping motor (driving source) 22B through hole (passage) 40 dustproof device 41, 42 elastic ring 41a, 42a retaining ring 43 dustproof film 50 direct drive motor Flow control valve 50 with

Claims (1)

[Scope of utility model registration request] 1. An inner surface of a passage that communicates with the inside of a drive source and the inside of a fluid pressure device and is filled with a fluid, and a direct movement from the drive source to a movable part of the fluid pressure device. A dustproof film made of a material that allows fluid to pass but does not allow dust to pass is disposed between the outer peripheral surface of the linear motion shaft that transmits displacement and absorbs relative displacement between the passage and the linear motion shaft. A dustproof device.