JP2002147362A - Bellows and bellows type pump device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent durability from being decided by the deterioration of a crest part and a trough part of bellows due to stress concentration on the crest part and the trough part of the bellows when repeatedly receiving telescopic operation over a long period in the bellows used for a bellows type pump device. SOLUTION: In this bellows 2, one intermediate folding part 2c is formed between the crest part 2a and the trough part 2b of the bellows. This intermediate folding part 2c is wholly bent in the same direction, and a cross section presents an almost V shape. When the bellows 2 extends and contracts, stress is dispersively generated in the intermediate folding part 2c besides the crest part 2a and the trough part 2b of the bellows. Thus, durability of the bellows 2 can be improved more than conventional durability. Since a bending angle θof the intermediate folding part 2c is arranged in a range of 90 deg. to 110 deg., and a radius of curvature r of the intermediate folding part 2c is arranged in a range of 0.5 to 0.7 mm, the stress generated in the bellows 2 can be efficiently dispersed to the crest part 2a, the trough part 2b, and the intermediate folding part 2c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bellows having a bellows-like cylindrical shape which elastically expands and contracts in the axial direction, and a bellows for sucking and pumping a working fluid by utilizing a volume change caused by expansion and contraction of the bellows. The present invention relates to a hydraulic pump device.

[0002]

2. Description of the Related Art As bellows used in bellows type pump devices and the like, U-shaped bellows and nesting bellows having U-shaped cross-sections of bellows are generally used. These bellows are subjected to repeated expansion and contraction operations over a long period of time. When the bellows undergoes expansion and contraction, stress concentrates on the peaks and valleys of the bellows, and thus the durability is determined by the deterioration of the peaks and valleys of the bellows.

[0003]

A technique disclosed in Japanese Patent Application Laid-Open No. H10-148258 is known as a technique for improving the durability by relaxing the stress concentration at the peaks and valleys of the bellows. This technique provides a gap between the bellows and a joining member such as a flange attached to the end of the bellows,
This is to alleviate the stress concentrated on the bellows peak closest to the joining member. However, this technique aims at alleviating the stress concentration at the peak of the bellows closest to the joining member, and has no effect of reducing the stress generated at the peaks and valleys of the bellows. For this reason, in the related art, stress cannot be avoided from being concentrated on the peaks and valleys of the bellows, and the durability is determined by the deterioration of the peaks and valleys of the bellows. An object of the present invention is to disperse the stress generated in the peaks and valleys of the bellows to improve the durability,
Another object of the present invention is to provide a bellows type pump device having excellent durability.

[0004]

According to the first aspect of the present invention, when the bellows expands and contracts, stress is applied not only to the peaks and valleys of the bellows but also to the intermediate folded portions. Occur in a dispersed manner. That is, since the stress is dispersed in the middle folded portion, the stress generated in the peak portion and the valley portion can be reduced. As described above, the stress generated when the bellows expands and contracts is distributed to the peaks, the valleys, and the intermediate folds, so that the durability of the bellows can be improved as compared with the related art.

According to the second aspect of the present invention, when the bellows expands and contracts, a member (for example, a dead volume filling member) disposed inside the bellows and an inner periphery of the bellows are formed. Even if the bellows contacts, the bellows escape to the outside due to the inclination of the inner circumference of the bellows, so that the problem that the bellows is damaged can be avoided.

According to the third aspect of the present invention, since the stress generated in the bellows can be substantially evenly distributed to the peaks, the valleys, and the intermediate folded portions, the durability of the bellows can be improved. Can be improved.

[Means of Claims 4 and 5] By adopting the means of claims 4 or 5, a bellows having excellent durability is mounted. Can be improved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described using a plurality of examples and modifications. FIG. 1 is a schematic sectional view of a bellows unit 1 mounted on a bellows type pump device. The bellows unit 1 shown in this embodiment is used for a hydrogen supply pump, for example, and is made of a metal material (for example, stainless steel) that does not transmit hydrogen and has excellent poisoning resistance and durability. Things.

The bellows unit 1 comprises a bellows 2 having a bellows-like cylindrical shape which elastically expands and contracts in the axial direction, a cap 3 fixed to the drive end side of the bellows 2, and a dead end arranged inside the bellows 2. A volume filling member 4 is provided, and a working fluid is suctioned and pumped by utilizing a change in internal volume caused by expansion and contraction of the bellows 2.

The right end of the bellows 2 in FIG. 1 is a drive end that receives expansion and contraction drive, and the left end in FIG. 1 is a fixed end. The drive end of the bellows 2 is joined to the disk-shaped cap 3 by a joining technique such as brazing or welding, and the drive end of the bellows 2 is reciprocated by the reciprocating motion of the cap 3. The fixed end of the bellows 2 is joined to a flange 4a provided on the left side of the dead volume filling member 4 having a substantially cylindrical shape by a joining technique such as brazing or welding. The working space 5 for sucking and compressing the working fluid is formed by the space surrounded by the dead volume filling member 4 and isolated from the outside.

FIG. 2 is an enlarged view of a portion A in FIG. 1. As shown in FIG. 2, the bellows 2 includes a bellows crest 2a (a folded portion on the outer peripheral side) and a valley 2b (inside). Intermediate folded portion 2c having a substantially rectangular cross section between the circumferential folded portions)
Are formed. The intermediate fold 2c is bent in the same direction, and is located between all the peaks 2a and the valleys 2b.
It is formed one by one.

The valley 2b on the inner peripheral side of the bellows 2 faces the drive end side of the bellows 2 as shown in FIG. Accordingly, even when the dead volume filling member 4 disposed inside the bellows 2 comes into contact with the inner periphery of the bellows 2 when the bellows 2 expands and contracts, the bellows 2 escapes to the outside due to the inclination of the inner peripheral side of the bellows. Therefore, it is possible to avoid a problem that the bellows 2 is damaged.

The bending angle θ of the intermediate folding part 2c is preferably in the range of 90 ° to 110 °, more preferably 100 °.
It is provided before and after. FIG. 3 shows the relationship between the bending angle θ of the intermediate folding part 2c and the amount of stress generated. In addition, FIG.
The degree of occurrence of stress is represented by an amplitude, and the stress amplitude on the vertical axis indicates the largest amplitude value among the peak 2a, the valley 2b, and the middle fold 2c.

As can be seen from FIG. 3, the bending angle θ of the intermediate folding portion 2c is 180 ° (no bending).
When the bending angle θ becomes smaller than 120 °, the amount of stress amplitude starts to decrease suddenly. When the bending angle θ is around 100 °, the amount of stress amplitude becomes minimum. When the bending angle θ of the intermediate folding portion 2c is smaller than 90 °, the degree of decrease in the stress amplitude decreases. in this way,
By setting the bending angle θ of the intermediate folded portion 2c in the range of 90 ° to 110 °, the stress generated by the expansion and contraction of the bellows 2 can be dispersed to the peak portion 2a, the valley portion 2b, and the intermediate folded portion 2c. Thus, the degree of stress concentration can be reduced.
Further, the amount of stress amplitude can be minimized by setting the bending angle θ of the intermediate folding portion 2c to about 100 °.

Here, assuming that the bellows 2 is made of stainless steel having a thickness of 0.2 mm, the radius of curvature r of the intermediate folded portion 2c is preferably in the range of 0.4 to 1.0 mm, and more preferably. It is provided in the range of 0.5 to 0.7 mm. FIG. 4 shows the relationship between the radius of curvature r of the intermediate folded portion 2c and the stress generated in the intermediate folded portion 2c. In FIG. 4, the degree of stress occurrence is represented by an amplitude, and the stress amplitude on the vertical axis indicates the largest amplitude value among the peaks 2a, the valleys 2b, and the middle folds 2c. .

As can be seen from FIG. 4, by setting the radius of curvature r of the intermediate folded portion 2c in the range of 0.4 to 1.0 mm, the amount of stress amplitude can be reduced, and the stress amplitude is generated on the bellows 2. The stress can be distributed to the peaks 2a, the valleys 2b, and the middle folds 2c. And the middle folding part 2
By setting the radius of curvature r of c in the range of 0.5 to 0.7 mm, the amount of stress amplitude can be further reduced.

The dead volume filling member 4 is a member for filling the dead volume generated in the internal space of the bellows 2 and improving the working fluid compression ratio of the working chamber 5 to obtain an appropriate compression ratio. Inside the dead volume filling member 4, a suction passage 6 for guiding the working fluid to the working chamber 5 and a discharge passage 7 for guiding the working fluid pumped from the working chamber 5 to the outside are formed. This simplifies the arrangement of the suction passage 6 and the discharge passage 7 in the bellows unit 1.

At a portion where the suction passage 6 communicates with the working chamber 5, there is provided a suction valve 8 which is a one-way valve for flowing a working fluid only from the suction passage 6 toward the working chamber 5. Also,
A discharge valve 9, which is a one-way valve that allows a working fluid to flow only from the working chamber 5 toward the discharge passage 7, is provided at a portion where the discharge passage 7 communicates with the working chamber 5. The suction valve 8 and the discharge valve 9 use well-known one-way valves such as a reed valve or a check valve.

Next, the drive mechanism of the bellows unit 1 in the bellows type pump device will be described. As shown in FIG. 5, the drive mechanism of this embodiment includes an electric motor 11 that generates rotational power, and a reciprocating mechanism that converts the rotational power generated by the electric motor 11 into reciprocating motion of the cap 3 in the axial direction. And 12. The bellows type pump device has a plurality of (eight in this embodiment) bellows units 1 mounted thereon as shown in FIG.
, Four bellows units 1 are arranged facing each other.

The reciprocating mechanism 12 is of a swash plate type using a swash plate 14 which rotates integrally with a rotary shaft 13, and the swash plate 14 is arranged between the bellows units 1 facing each other in the axial direction. I have. A drive shaft 15 for transmitting the swing of the swash plate 14 to the respective caps 3 is attached to the swash plate 14, and the swing of the swash plate 14 is provided between the swash plate 14 and the drive shaft 15. A shoe 16 for converting to reciprocating movement is provided. The drive shaft 15 is provided in the cylinder 17 so as to be movable only in the axial direction.

Next, a connection structure between the suction passage 6 and the discharge passage 7 is shown in FIG. This figure shows a delivery plate 18 fixed to each dead volume filling member 4, and the delivery plate 18 is provided with a working fluid for each bellows unit 1.
A suction passage 6 is formed so as to distribute the working fluid, and a discharge passage 7 is formed so as to collect the working fluid compressed in each bellows unit 1.

FIG. 5 is a sectional view of the entire bellows type pump device.
Shown in As shown in this figure, eight bellows units 1 are provided with a delivery plate 18 at both ends and a rectangular casing 1.
9 is housed in the space surrounded by. Here, the rectangular casing 19 includes a first frame 19 a that covers the periphery of the four bellows units 1 on the side close to the electric motor 11, and the suction passage 6.
A second frame 19b formed with a suction port 6a communicating with the discharge port 7a and a discharge port 7a communicating with the discharge passage 7;
It comprises a frame 19c and a fourth frame 19d that covers the periphery of the four bellows units 1 on the side remote from the electric motor 11. A cylinder 17 for slidably holding the drive shaft 15 only in the axial direction is disposed inside the second and third frames 19b and 19c.

[Operation of the First Embodiment] When the electric motor 11 operates, the swash plate 14 rotates in an inclined state with the rotation of the rotating shaft 13. Then, the swing of the end of the swash plate 14 is transmitted to the cap 3 via the drive shaft 15, and the cap 3 is reciprocated in the axial direction. As the cap 3 reciprocates, the bellows 2 expands and contracts. When the bellows 2 extends, the working fluid flows from the suction passage 6 into the working chamber 5 due to the increase in the volume of the working chamber 5. Subsequently, when the bellows 2 contracts, the volume of the working chamber 5 is reduced, thereby causing the working chamber 5 to contract.
Is compressed, and the compressed working fluid is pumped to the outside through the discharge passage 7. That is, the bellows units 1 perform the pump operation by the expansion and contraction driving of the cap 3 continuously.

In this embodiment, four bellows units 1 are arranged around the rotating shaft 13 at intervals of 90 degrees.
Since this is driven using the swash plate 14, the operation phase of each bellows unit 1 is shifted by 90 degrees. As a result, the pulsation of suction and discharge of the working fluid is averaged.

[Effects of the First Embodiment] As shown in the above embodiment, the bellows 2 can be expanded and contracted by forming the intermediate bent portion 2c between the peak 2a and the valley 2b of the bellows 2 of the bellows. In this case, the stress is dispersed and generated not only in the bellows peak portion 2a and the valley portion 2b but also in the middle folding portion 2c. As described above, since the stress is distributed to the peaks 2a, the valleys 2b, and the middle folds 2c,
The durability of the bellows 2 can be improved as compared with the related art. In particular, the bending angle θ of the intermediate folding portion 2c is set to 90 ° to 1 °.
By providing the radius of curvature r of the intermediate folded portion 2c within the range of 0.5 to 0.7 mm within the range of 10 °, the stress generated in the bellows 2 is reduced to the peak portion 2a, the valley portion 2b, and the intermediate portion. It is possible to efficiently disperse them in the folded portions 2c. For this reason,
The durability of the bellows 2 can be dramatically increased. Alternatively, since the amount of expansion and contraction can be increased, the dead volume generated in the bellows 2 can be reduced. Since the pump efficiency (volume efficiency) is improved by reducing the dead volume, the size of the bellows unit 1 can be reduced.

The valley portion 2b on the inner peripheral side of the bellows 2 is arranged toward the driving end side of the bellows 2, so that when the bellows 2 expands and contracts, the dead volume filling member 4 arranged inside the bellows 2 is removed. Even if the inner periphery of the bellows 2 comes into contact, the bellows 2 escapes to the outside due to the inclination on the inner peripheral side of the bellows. Therefore, it is possible to avoid a problem that the bellows 2 is damaged. Further, with this technique, the clearance between the bellows 2 and the dead volume filling member 4 can be reduced, so that the dead volume can be reduced and the bellows unit 1 can be downsized. Further, since the bellows type pump device uses the bellows 2 having excellent durability, the durability of the bellows type pump device is improved.

Second Embodiment Bellows Unit 1 of FIG.
The second embodiment will be described with reference to a schematic sectional view of FIG. In the drawings, the same reference numerals as those in the first embodiment denote the same functional objects. The second embodiment relates to a reciprocating mechanism 12 used for a drive mechanism of the bellows unit 1. The reciprocating mechanism 12 according to this embodiment includes a crank 21 that is rotationally driven by an electric motor 11 (reference numeral, see the first embodiment) and a cap 3 that rotates the crank 21.
And a crankshaft 22 that converts the axial movement of the cap 3. When the crank 21 is rotationally driven, the cap 3 reciprocates in the axial direction.

Third Embodiment Bellows unit 1 shown in FIG.
The third embodiment will be described with reference to the schematic sectional view of FIG. In the drawings, the same reference numerals as those in the first embodiment denote the same functional objects. In the third embodiment, the reciprocating mechanism 12
It is about. The reciprocating mechanism 12 of this embodiment includes:
The cam 23 is rotated by the electric motor 11 (reference numeral, see the first embodiment). The cam 23 presses the cap 3 against the restoring force of the bellows 2, and the cam 23 is driven to rotate. And the cap 3 reciprocates in the axial direction.

[Modifications] In the above embodiment, an example in which the present invention is applied to a hydrogen supply pump has been described. For example, a gas pressure pump such as a flammable gas or a toxic gas, a flammable liquid,
The present invention may be applied to a pump for feeding a liquid such as a toxic liquid. In the above-described embodiment, as an example of the bellows 2, the example in which the U-shaped bellows 2 in which the ridges 2 a and the valleys 2 b have a U-shape is used, but ring disks provided in a disk spring shape are alternately provided. The present invention may be applied to a bellows 2 configured by overlapping and joining. In the above-described embodiment, an example in which metal is used as the material of the bellows unit 1 has been described. However, some or all of the constituent members of the bellows unit 1 may be configured using resin or rubber. That is, for example, the bellows 2 and the like may be configured using resin or rubber according to the applied working fluid.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a bellows unit (first embodiment).

FIG. 2 is an enlarged sectional view of a portion surrounded by A in FIG. 1 (first embodiment).

FIG. 3 is a graph showing a relationship between a bending angle of a middle folded portion and a stress amplitude amount (first embodiment).

FIG. 4 is a graph showing the relationship between the radius of curvature of the middle fold and the amount of stress amplitude (first embodiment).

FIG. 5 is a sectional view of a bellows type pump device (first embodiment).

FIG. 6 is a perspective view showing an arrangement of a bellows unit (first embodiment).

FIG. 7 is an explanatory view showing an arrangement of a suction passage and a discharge passage in a delivery plate (first embodiment).

FIG. 8 is a schematic sectional view of a bellows unit (second embodiment).

FIG. 9 is a schematic sectional view of a bellows unit (third embodiment).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bellows unit 2 Bellows 2a Peak part 2b Valley part 2c Intermediate folded part 3 Cap 4 Dead volume filling member 6 Suction passage 7 Discharge passage 8 Suction valve 9 Discharge valve

Continued on the front page (72) Inventor Yukihiro Kimoto 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in Denso Corporation (reference) 3H077 AA01 AA11 BB03 BB05 CC03 DD02 DD12 EE21 EE34 FF02 FF09 FF10 FF22 3J045 AA04 AA20 BA02 BA03 BA04 CB04 CB25 EA10

Claims (5)

[Claims] 1. A bellows having a bellows-like cylindrical shape which elastically expands and contracts in the axial direction, wherein the bellows has a substantially rectangular shape in cross section between a peak and a valley of the bellows. A bellows comprising two intermediate folds. 2. The bellows according to claim 1, wherein a valley on an inner peripheral side of the bellows is provided toward a driving end side of the bellows. 3. The bellows according to claim 1, wherein a bending angle of the intermediate bent portion is in a range of 90 ° to 110 °. 4. The bellows according to claim 1, further comprising: a drive mechanism for reciprocatingly driving one end of the bellows in an axial direction, wherein a change in an internal volume caused by expansion and contraction of the bellows is used. hand,
Bellows type pump device for conveying working fluid. 5. The bellows according to claim 1, a cap fixed to a drive end side of the bellows, and a fixed end side of the bellows are fixed and arranged in the bellows, A suction passage and a suction valve for supplying a working fluid to the inside of the bellows in accordance with an increase and a change in the volume in the bellows, and a discharge passage and a discharge valve for discharging the working fluid to the outside of the bellows due to a decrease in the volume in the bellows. Equipped with a dead volume filling member, and a driving mechanism for reciprocatingly driving the cap, utilizing a change in internal volume due to expansion and contraction of the bellows,
Bellows type pump device for conveying working fluid.