JPH07260084A - Pulsation absorbing device - Google Patents

Abstract

PURPOSE:To absorb and damp pulsation in pressure fluid such as pressure operating oil and compressed air, etc., in a wide range from a low frequency range to a high frequency range effectively by a simple composition. CONSTITUTION:A pulsation absorbing device consists of an expansion and contraction tube 2, a holding member 3 which has a fusiform inner wall surface 31 for forming fusiform space 30 toward the outer circumferential surface 24 of the expansion and contraction tube 2 and which is integrated with the expansion and contraction tube 2 while covering the expansion and contraction tube 2, and a compressed elastic body 4 which is arranged in the space 30 between the outer circumferential surface 24 of the expansion and contraction tube 2 and the fusiform inner wall surface 31 of the holding member 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulsation absorbing device.

[0002]

2. Description of the Related Art Conventionally, a fluid passage for supplying a pressure fluid such as pressure oil or compressed air to various actuators has a vibration,
A pulsation absorbing means is used for absorbing and attenuating the pulsation of pressure fluid that causes noise. As the pulsation absorbing means, for example, an accumulator, a silencer, a softened hose, etc. which are used by connecting to the fluid passage are known.

[0003]

[Problems to be Solved by the Invention]

(1) The accumulator is, for example, a high-pressure vessel in which high-pressure nitrogen is enclosed by a partition made of an elastic film. When this accumulator is used by connecting it to a passage for pressure hydraulic oil delivered from a hydraulic pump, for example, as a pressure fluid, the pulsation with a long cycle of impact pressure and pressure fluctuations that occur during low rotation of the hydraulic pump (hereinafter referred to as low frequency (Referred to as pulsation of a region) acts on the partition wall, the partition wall follows and displaces to compress the high-pressure nitrogen, thereby absorbing and damping the impact pressure and pulsation.

On the other hand, however, according to the accumulator, the partition wall cannot follow or displace the pulsation having a short cycle of pressure fluctuation (hereinafter referred to as pulsation in the high frequency range) which occurs when the hydraulic pump rotates at a high speed. The damping effect of is limited. Further, when the accumulator is used for a long period of time, there is a problem that nitrogen gas permeates through the partition wall and the pulsation damping effect is reduced. Therefore, in order to prevent the leakage of the nitrogen gas, a composite material of a resin material and a rubber material is used as the partition wall, but there is a problem that the manufacturing cost increases. (2) When the silencer is used by connecting it to the passage of the pressure hydraulic oil, pressure wave interference with a wavelength shift occurs due to the silencer, so that the effect of absorbing and damping pulsation and noise in a high frequency region is large. . However, on the other hand, since the length of the silencer cannot be made very long, the effect of absorbing and damping pulsation and noise in the low frequency region is small.

Further, when a silencer is used, it is necessary to dispose a plurality of hoses or pipes when installing the silencer, which complicates the hydraulic oil path, increases pressure loss, and increases cost. (3) The softened hose can be considered as a kind of accumulator, and since the contact area between the fluid and the partition wall is large, the pulsation in the low frequency range to the pulsation in the high frequency range is wide due to the change in the partition wall. Absorption and damping effects can be obtained within the range.

However, since the softened hose utilizes its own elastic deformation, it is necessary to lengthen the hose in order to exert its effect, and the pressure loss decreases the pressure responsiveness. There is. The present invention provides a pulsation absorbing device capable of effectively absorbing and attenuating pulsation in a pressure fluid such as pressure hydraulic oil or compressed air in a wide range from a low frequency region to a high frequency region with a simple configuration. To aim.

[0007]

The pulsation absorbing device of the present invention has a telescopic tube and a spindle-shaped inner wall surface forming a spindle-shaped space between the outer peripheral surface of the telescopic tube, and the telescopic tube covering the telescopic tube. A holding member integrated with the tube,
And a compressed elastic body disposed in the space between the outer peripheral surface of the expandable tube and the spindle-shaped inner wall surface of the holding member.

According to a preferred aspect of the present invention, the holding member has a cylindrical inner wall surface that abuts the outer peripheral surface of the telescopic tube at both ends of the spindle inner wall surface, and is divided into a plurality of axially divided surfaces. It can be configured as described above. The holding member may be made of any material having rigidity, such as a metal such as iron and aluminum, a synthetic resin such as a glass fiber reinforced nylon resin, or the like.

In another preferred aspect of the present invention, the elastic body to be compressed is made of foamed rubber, a three-dimensional mesh body made of an elastic material, and is integrally formed on a spindle-shaped inner wall surface of a holding member. Alternatively, it may be integrally formed on the outer peripheral surface of the expandable tube. As the foamed rubber, for example, molded nitrile rubber, urethane rubber or the like can be used. Further, the hardness and the expansion ratio of the foamed rubber can be set to various values suitable for absorbing and attenuating the pulsation between the low frequency region and the high frequency region and the pulsation in the target frequency region range. For example, a rubber material having a rubber hardness before foaming of 30 to 70 (JIS A) and foamed at a foaming ratio of 2 to 20 times can be used.

As the elastic material forming the three-dimensional mesh body, for example, nitrile rubber or the like can be used. The material and hardness of the expansion tube can be variously selected according to the type of fluid flowing in the expansion tube and the temperature of the fluid. For example, when mineral oil is used as the hydraulic oil,
Nitrile rubber, urethane rubber, fluororubber, hydrin rubber, etc. are used and have a hardness of 30 to 70 (JIS
A) can be used. When the operating temperature of the hydraulic oil is in the range of 30 ° C to 100 ° C, nitrile rubber or the like is used as the material of the expandable tube, and the hardness thereof is set to 40 to 60 (JIS A). What was done can be used.

[0011]

The pulsation absorbing device of the present invention is used by connecting the expansion tube to the fluid passage in order to damp the pulsation of the pressure fluid flowing in the fluid passage and the noise accompanying the pulsation. The expandable tube is elastically deformed and expanded and contracted in accordance with the pulsating waveform generated in the pressure fluid. When the expandable tube expands in a spindle shape due to the action of the peak portion (peak pressure) of the pulsating waveform, the elastic tube is pressed and elastically deformed. Therefore, the elastic body to be compressed is pressed between the expandable tube that is pressed against the spindle-shaped inner wall surface of the holding member and is in an expanded state, and the spindle-shaped inner wall surface. The ridges of the pulsating waveform are absorbed by the elastic deformation of the expandable tube and the elastic body to be compressed.

At the same time, an elastic repulsive force proportional to the amount of deformation at the time of compression is accumulated in the elastic body to be compressed.
Since the expandable tube and the elastic body to be compressed elastically deform into a shape along the spindle-shaped inner wall surface of the holding member, the amount of deformation is limited by the spindle-shaped inner wall surface and is appropriate without becoming excessive. Then, when moving to the valley portion of the pulsating waveform, when the peak portion of the pulsating waveform is generated, due to the action of the elastic repulsive force accumulated in the compressed elastic body, the telescopic tube, together with the compressed elastic body, quickly returns to its original state. Return to shape.

[0013]

【Example】

(Embodiment 1) Embodiment 1 applied when the pulsation absorbing device of the present invention is used by being connected to a hydraulic oil passage of an automobile power steering system will be described with reference to FIGS.
A pulsation absorbing device 1 according to a first embodiment shown in cross section in FIG. 1 includes a telescopic tube 2, a holding member 3, and a compressed elastic body 4.

The telescopic tube 2 has a length of about 70 mm, an inner diameter of about 9 mm, a wall thickness of 2 ± 1 mm, and a hardness of 50 to 60 (JIS.
It is composed of a tubular tube made of nitrile rubber of A) (see FIG. 3). As shown in FIG. 4, the telescopic tube 2 has one end 22 side and the other end 23 side of the hole passage 20 inserted and connected to the outer peripheral portions of the passages 50 and 51 made of a metal pipe forming a part of the hydraulic circuit. .

The holding member 3 is formed of symmetrical holding pieces 3a, 3b which are divided into two along the dividing surfaces S, S (see FIG. 2) along the axial direction P (see FIG. 1). Holding piece 3a,
3b is made of a metal made of iron having rigidity.
As shown in FIG. 3, a spindle-shaped inner wall surface 31 that forms a spindle-shaped space 30 is formed between the telescopic tube 2 and the outer peripheral surface 24.
The spindle-shaped inner wall surface 31 covers the outer peripheral surface 24 of the expandable tube 2 and the elastic body 4 to be compressed, and integrates them. The holding pieces 3a, 3b also have cylindrical inner wall surfaces 32, 33 on both ends of the spindle-shaped inner wall surface 31, which are in contact with the outer peripheral surface 24 of the telescopic tube 2. The cylindrical inner wall surfaces 32 and 33 are formed with ring-shaped protrusions 34 and 35 protruding toward the center. The protrusions 34 and 35 are the outer peripheral surface 24 of the telescopic tube 2.
Is pressed against the passages 50, 51 to enhance the sealing property of the telescopic tube 2. Further, the holding pieces 3a, 3b have bolt holes 37 through which the tightening bolts 36 are inserted.

The compressed elastic body 4 is of a spindle type (see FIG. 6) made of foamed rubber, and is divided into two by dividing planes S and S (see FIG. 2) along the axial direction P (see FIG. 1). It is formed by the symmetrical elastic pieces 4a, 4b. The compressed elastic pieces 4a, 4b are attached to the spindle-shaped inner wall surfaces 31 of the holding pieces 3a, 3b, respectively (see FIG. 7). Thereafter, the holding pieces 3a, 3b are tightened by the bolt 36 (see FIG. 1) and a nut (not shown) via the expansion tube 2 and the elastic pieces 4a, 4b, and the divided surfaces S, S are brought into close contact with each other. Are integrally fixed and held (see FIG. 2).

As a result, the elastic pieces 4a, 4b form the compressed elastic body 4, and the space 30 between the outer peripheral surface 24 of the telescopic tube 2 and the spindle-shaped inner wall surface 31 of the holding member 3.
Is located in. As the foamed rubber, nitrile rubber having a rubber hardness of 50 (JIS A) before foaming was foamed at a foaming ratio of 5 times. According to the pulsation absorbing device 1 of the first embodiment configured as described above, when the power steering system is operated, the pulsation of the pressure hydraulic oil sent from the hydraulic pump interlocked with the rotation of the engine (not shown) causes the passage 5 to pass.
Acts on the telescopic tube 2 between 0 and 51.

The elastic tube 2 elastically deforms and expands and contracts in accordance with the pulsating waveform generated in the pressure hydraulic oil. That is, the expandable tube 2 elastically deforms in the direction of expanding the inner diameter of the hole passage 20 when the peak portion (peak pressure) of the pulsating waveform acts on the inner peripheral surface 21 of the hole passage 20, and expands in a spindle shape. Then, the telescopic tube 2 has the outer peripheral surface 24 and the inner peripheral surface 4 of the elastic body 4 to be compressed.
Press on 1. As a result, the compressed elastic body 4 is elastically deformed and is compressed by the outer peripheral surface 24 of the expandable tube 2 and the spindle-shaped inner wall surface 32 of the holding member 3. Due to the elastic deformation of the expandable tube 2 and the compressed elastic body 4, the peak portion of the pulsating waveform is absorbed.

At the same time, the compressed elastic body 4 is
Elastic repulsive force proportional to the amount of deformation at the time of compression is accumulated. Since the expandable tube 2 and the elastic body 4 to be compressed elastically deform into a shape along the spindle-shaped inner wall surface 31 of the holding member 3, the deformation amount is limited by the spindle-shaped inner wall surface 31 and is not excessive. It will be Next, when moving to the valley portion of the pulsating waveform, the elastic repulsive force that is compressed in the peak portion of the pulsating waveform and accumulated in the compressed elastic body 4 causes the expansion tube 2 to quickly move to the original shape together with the compression elastic body 4. Return to.

According to the pulsation absorbing device 1 of the first embodiment, the following effects can be obtained. That is, (1) a simple configuration including the above-described expandable tube 2, the holding member 3 formed by the holding pieces 3a and 3b, and the compressed elastic body 4 formed by the elastic pieces 4a and 4b, Product cost can be reduced. (2) Since the telescopic tube 2 is flexible and has a large contact area with the flow path, it is elastically deformed according to the pulsation of each frequency region of the pressure hydraulic oil, and the passage hole 20 is expanded and displaced in a spindle shape. As a result, the pulsation can be absorbed and attenuated. (3) Since the compressed elastic body 4 is pressed and elastically deformed by the telescopic tube 2 that expands in a spindle shape, and is compressed between the elastic body 4 and the spindle-shaped inner wall surface 31 of the holding member 3, an elastic reaction force can be accumulated. .

The elastic reaction force of the elastic body 4 to be compressed causes the expansion tube to expand when the expansion tube 2 in the expanded state contracts and returns to its original shape (when the pulsating waveform changes from the peak portion to the valley portion). It is given to 2. Therefore, even if the expandable tube 2 is made of a flexible material, the contracted displacement from the expanded state to the original shape is quickly performed, so that it is possible to sufficiently cope with the pulsation in the high frequency region.

That is, the expandable tube 2 has a good responsiveness, and is useful for absorbing and attenuating the pulsation between the low frequency region and the high frequency region and the pulsation in the intended frequency region range. (4) Further, the range in which the telescopic tube 2 expands in the spindle shape is limited by the spindle-shaped inner wall surface 31 of the holding member 3 via the elastic body 4 to be compressed, so that it can be set within a preset maximum expansion. Useless pressure loss can be prevented.

(Second Embodiment) A second embodiment of the pulsation absorbing device of the present invention will be described with reference to FIG. The pulsation absorbing device 1A according to the second embodiment is provided on the outer peripheral side of the expandable tube 2A during its manufacture.
Spindle-shaped compressed elastic part 4 made of the same material as the telescopic tube 2A
3 is integrally provided, and has the same spindle-shaped inner wall surface 31 that forms a spindle-shaped space 30 between the outer peripheral surface 44 and the outer peripheral surface 44, and has the same configuration as the pulsation absorbing device 1 of the first embodiment.

According to the pulsation absorbing device 1A of the second embodiment, in addition to the effect of the pulsation absorbing device 1 of the first embodiment, the effect of reducing the number of parts can be obtained. (Modification) A pulsation absorbing device according to a modification of the second embodiment will be described with reference to FIG. In the pulsation absorbing device 1a of the modified example, a compressed elastic portion 43 is integrally provided on the outer peripheral side of the expandable tube 2a, and the compressed elastic portion 43 has an uneven outer peripheral surface 44a.
The same as the configuration of the pulsation absorbing device 1A of the second embodiment except that the above is formed.

According to the pulsation absorbing device 1a of the modified example, it is possible to obtain substantially the same effect as that of the pulsation absorbing device 1A of the second embodiment. (Embodiment 3) FIG. 10 shows Embodiment 3 of the pulsation absorbing device of the present invention.
It will be described based on. The pulsation absorbing device 1B of the third embodiment is
Other than forming the holding member 3B integrally with the spindle-shaped inner wall surface 31 by the adhesive portion 6 (see the thick black curve portion in FIG. 10) to which the spindle-shaped compressed elastic portion 43b made of nitrile rubber is adhered The configuration is the same as that of the pulsation absorbing device 1 of Example 1.

According to the pulsation absorbing device 1B of the third embodiment, in addition to the effect of the pulsation absorbing device 1 of the first embodiment, the labor for assembling the compressed elastic pieces 4a, 4b of the pulsation absorbing device 1 can be omitted. it can.

[0027]

According to the pulsation absorbing device of the present invention having the above structure, the following effects can be obtained. That is, (1) it has a simple structure including the above-described expandable tube, the holding member, and the elastic body to be compressed, and the product cost can be reduced. (2) Since the telescopic tube has flexibility and has a large contact area with the flow path, it elastically deforms according to the pulsation of each frequency region of the pressure hydraulic oil, and expands and displaces in a spindle shape to cause the pulsation. Can be absorbed and attenuated. (3) Since the compressed elastic body is pressed and elastically deformed by the telescopic tube that expands in a spindle shape, and is compressed between itself and the spindle-shaped inner wall surface of the holding member, an elastic reaction force can be accumulated.

Therefore, even if the expandable tube is made of a flexible material, a repulsive force is applied by the elastic reaction force due to the compression accumulated in the elastic body to be compressed, and the expanded tube returns to its original shape. Since the contraction displacement is rapidly performed, it is possible to sufficiently cope with the pulsation in the high frequency region. That is, the expandable tube has good responsiveness, and is useful for absorbing and attenuating the pulsation between the low frequency region and the high frequency region and the pulsation in the target frequency region range. (4) The range of expansion of the telescopic tube into the spindle shape is
Since it is limited by the spindle-shaped inner wall surface of the holding member via the elastic body to be compressed, the maximum expansion can be set within a preset range, and wasteful pressure loss can be prevented.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional front view showing a state in which a pulsation absorbing device according to a first embodiment is cross-sectioned along a split surface along an axial direction of a holding member and is viewed from the split surface side.

FIG. 2 is a cross-sectional view showing the pulsation absorbing device of the first embodiment in a state in which it is not divided by a dividing surface along the axial direction of the holding member, taken along line AA in FIG.

FIG. 3 is a cross-sectional view showing a telescopic tube in FIG.

FIG. 4 is a cross-sectional view showing a state where the telescopic tube in FIG. 3 is attached to a pressure hydraulic oil passage formed of a pipe.

5 is a front view of the holding piece of the holding member in FIG. 1 seen from the dividing surface.

FIG. 6 is a front view of the compressed elastic piece of the compressed elastic body in FIG. 2 seen from the dividing surface.

7 is a front view showing a state in which the compressed elastic piece of the compressed elastic body in FIG. 6 is attached to the holding piece of the holding member in FIG.

FIG. 8 is a partial cross-sectional front view showing a state in which the pulsation absorbing device according to the second embodiment is sectioned along a split surface along the axial direction of the holding member and is viewed from the split surface side.

FIG. 9 is a partial cross-sectional front view showing a state in which a pulsation absorbing device according to a modified example of the second embodiment is sectioned along a split surface along the axial direction of the holding member and is viewed from the split surface side.

FIG. 10 is a partial cross-sectional front view showing a state in which the pulsation absorbing device of Example 3 is cut along a split surface along the axial direction of the holding member and seen from the split surface side.

[Explanation of symbols]

 1.1A. 1a. 1B ... Pulsation absorber 2 ... Telescopic tube 3 ... Holding member 3a. 3b ... Holding piece 4 ... Compressed elastic body 4a. 4b ... Compressed elastic piece

Claims (7)

[Claims] 1. A telescopic tube, a holding member having a spindle-shaped inner wall surface forming a spindle-shaped space between the telescopic tube and an outer peripheral surface of the telescopic tube, and a holding member which covers the telescopic tube and is integrated with the telescopic tube, and the telescopic tube. And a compressed elastic body disposed in the space between the outer peripheral surface and the spindle-shaped inner wall surface of the holding member. 2. The holding member has a cylindrical inner wall surface abutting the outer peripheral surface of the telescopic tube on both ends of the spindle-shaped inner wall surface.
Pulsation absorber. 3. The pulsation absorbing device according to claim 1 or 2, wherein the holding member is divided into a plurality of pieces by dividing surfaces along the axial direction. 4. The compressed elastic body is foamed rubber.
Alternatively, the pulsation absorbing device described in 2. 5. The pulsation absorbing device according to claim 1, wherein the elastic body to be compressed has a three-dimensional mesh shape formed of an elastic material. 6. The pulsation absorbing device according to claim 1, wherein the compressed elastic body is integrally formed on the spindle-shaped inner wall surface of the holding member. 7. The pulsation absorbing device according to claim 1, wherein the compressed elastic body is integrally formed on the outer peripheral surface of the expandable tube.