JP6896747B2 - Bellows pump - Google Patents

Description

The present invention relates to a bellows pump used for sending and circulating a liquid such as a chemical solution or a slurry solution in a manufacturing process of a semiconductor, a liquid crystal, an organic EL or the like.

As a conventional bellows pump, as disclosed in Patent Document 1 or Patent Document 2, each linear wall and one of the linear walls adjacent thereto are connected by a chevron wall and with the other of the adjacent linear walls. It is configured to exert a liquid feeding function by using a bellows that has a bellows-shaped peripheral wall with a cross-section that is connected by a valley wall and can expand and contract in the axial direction (hereinafter referred to as "conventional bellows pump"). Is well known. In the conventional bellows pump, as disclosed in FIG. 2 of Patent Document 1 and FIG. 2 of Patent Document 2, the wall thickness of the straight wall, the chevron wall and the valley wall constituting the peripheral wall of the bellows is uniform and the same. Alternatively, they are substantially the same, and the liquid feeding function is performed by alternately performing a suction step of sucking the liquid into the bellows by extending the bellows and a discharge step of discharging the liquid in the bellows by contracting the bellows. Is demonstrated.

JP-A-2002-174180 Japanese Unexamined Patent Publication No. 2012-21512

However, in the conventional bellows pump, if the period of use is long, a part of the peripheral wall of the bellows may be cracked and damaged, which causes a problem in the durability of the bellows.

The present invention has been made in view of the above points, and an object of the present invention is to provide a bellows pump capable of improving the durability of bellows.

In the present invention, a plurality of linear walls parallel to each other in the axial direction, a chevron wall connecting each linear wall and one of the adjacent linear walls to the outer peripheral end thereof, each linear wall and the linear wall thereof. It is configured to suck and discharge liquid by a bellows that has a bellows-shaped peripheral wall with a cross section consisting of a valley-shaped wall that connects the inner peripheral ends with the other of the adjacent straight walls and that can expand and contract in the axial direction. In order to achieve the above object, the first chevron wall portion, which is a portion of the chevron wall on the extension direction side of the bellows, is a portion of the chevron wall on the contraction direction side of the bellows. We propose a bellows pump characterized by having a reinforcing portion having a wall thickness larger than that of the second chevron wall portion.

In a preferred embodiment of the bellows pump of the present invention, the reinforcing portion is all portions of the first chevron wall portion except the boundary portion with the straight wall portion and the boundary portion with the second chevron wall portion. Alternatively, it is a part, and in the reinforcing portion, an arbitrary angle α (0 ° <α <90 °) with respect to a straight line extending in the extending direction of the bellows from the center of curvature of the inner peripheral surface of the chevron wall in the cross section of the chevron wall. The wall thickness at the position forming) is larger than the wall thickness at the position forming an angle β (= 180 ° −α) with respect to the straight line in the second chevron wall portion. Further, the wall thickness of the linear wall connected to the first chevron wall portion is made larger than the wall thickness of the linear wall connected to the second chevron wall portion, or is connected to the second chevron wall portion. It can be the same as or substantially the same as the wall thickness of the linear wall.

In the bellows pump of the present invention, the first chevron wall portion that is easily damaged by stress concentration is assumed to have a reinforcing portion having a wall thickness larger than the wall thickness of the second chevron wall portion, and the first chevron wall portion is reinforced. Therefore, damage to the first chevron wall portion can be prevented as much as possible, and the durability of the bellows can be significantly improved.

FIG. 1 is a cross-sectional view showing an example of a bellows pump according to the present invention. FIG. 2 is a cross-sectional view corresponding to FIG. 1 showing a state different from that of FIG. FIG. 3 is an enlarged cross-sectional view showing a main part of FIG. FIG. 4 is an enlarged cross-sectional view showing a main part of FIG. FIG. 5 is an enlarged cross-sectional view showing a main part of FIG. FIG. 6 is an enlarged cross-sectional view showing a main part of FIG. 3, showing a form different from that of FIG. FIG. 7 is a cross-sectional view of a main part corresponding to FIG. 3 showing a modified example of the bellows pump according to the present invention. FIG. 8 is a cross-sectional view of a main part corresponding to FIG. 5 showing another modified example of the bellows pump according to the present invention. FIG. 9 is a cross-sectional view corresponding to FIG. 8 showing still another modification of the bellows pump according to the present invention. FIG. 10 is a cross-sectional view corresponding to FIG. 8 showing still another modification of the bellows pump according to the present invention. FIG. 11 is a cross-sectional view of a main part corresponding to FIG. 3 showing still another modification of the bellows pump according to the present invention. FIG. 12 is an enlarged cross-sectional view showing a main part of FIG. FIG. 13 is a cross-sectional view of a main part corresponding to FIG. 12 showing still another modification of the bellows pump according to the present invention. FIG. 14 is a cross-sectional view corresponding to FIG. 13 showing still another modification of the bellows pump according to the present invention. FIG. 15 is a schematic cross-sectional view of a main part showing still another modification of the bellows pump according to the present invention.

A mode for carrying out the present invention will be specifically described with reference to the drawings.

FIG. 1 is a cross-sectional view showing an example of a bellows pump according to the present invention, FIG. 2 is a cross-sectional view corresponding to FIG. 1 showing a state different from that of FIG. The cross-sectional view shows the most contracted state of the bellows, FIG. 4 is an enlarged cross-sectional view showing the main part of FIG. 2, and shows the most extended state of the bellows, and FIGS. 5 and 6 are FIGS. It is a cross-sectional view which shows the main part of 3 in an enlarged view, and shows a different bellows shape. In the following description, the left and right means the left and right in FIGS. 1 to 3. The axis means the center line of the bellows, which will be described later, and the axis direction means a direction parallel to the axis.

The bellows pumps shown in FIGS. 1 and 2 are double-acting horizontal bellows pumps that send liquids F such as chemicals and slurry liquids, and are a pump head 3 forming a discharge passage 1 and a suction passage 2 and a pump. A pair of left and right cylinder cases 4 and 4 provided on both sides of the head 3, and a pair of left and right bottomed bottoms that are arranged in each cylinder case 4 and attached to the pump head 3 and can be expanded and contracted in the axial direction (left and right direction). Cylindrical bellows 5 and 5, a pair of left and right pump chambers 6 and 6 surrounded by each bellows 5, and a pair of left and right discharge side reverse stops attached to the pump head 3 so as to project into each pump chamber 6. The valves 7 and 7 and a pair of left and right suction-side check valves 8 and 8 attached to the pump head 3 so as to project into each pump chamber 6 are provided, and both bellows 5 and 5 are alternately expanded and contracted. As a result, the liquid F is sent from one pump chamber 6 to the discharge passage 1 via the discharge side check valve 7 and the other pump chamber 6 from the suction passage 2 via the suction side check valve 8. It is configured to simultaneously perform the suction step of supplying the liquid to the pump. The cylinder cases 4 and 4, both bellows 5 and 5, both pump chambers 6 and 6, both discharge side check valves 7 and 7, and both suction side check valves 8 and 8 constituting the bellows pump are respectively. It has the same structure except that it has a symmetrical structure.

The pump head 3 has a disk shape in which a discharge passage 1 connected to the liquid supply line and a suction passage 2 connected to the liquid supply line are formed, and as shown in FIGS. 1 and 2, the pump head 3 is formed on both the left and right sides thereof. The upstream end of the discharge passage 1 and the downstream end of the suction passage 2 are branched and opened in each pump chamber 6.

As shown in FIGS. 1 and 2, each cylinder case 4 has a bottomed cylindrical shape attached to the pump head 3, and constitutes a pump housing in which the opening is closed by the pump head 3.

As shown in FIGS. 1 to 4, each bellows 5 has a cylindrical peripheral wall 5a that can be expanded and contracted in the axial direction (left-right direction), a bottom wall 5b that closes one end of the peripheral wall 5a, and the other end of the peripheral wall 5a. It is a bottomed cylinder composed of a flange wall 5c connected to the opening. Each bellows 5 is attached to the pump head 3 so as to be expandable and contractible in the axial direction by fixing the flange wall 5c to the pump head 3, and by expanding and contracting, the pump head 3 and the peripheral wall 5a and the bottom wall 5b of the bellows 5 are expanded and contracted. The volume of the pump chamber 6 surrounded by and is changed (expanded and contracted).

As shown in FIGS. 3 and 4, the peripheral wall 5a of each bellows 5 is a cylindrical body that can be expanded and contracted in the axial direction, and is an annular linear wall that is a plurality of annular flat plates parallel to each other in the axial direction. An annular body connecting the outer peripheral ends of the 51 and one of the linear walls 51 and 51 adjacent to the linear wall 51, and having a V-shape or a U-shape in the outer peripheral direction of the peripheral wall 5a. An annular body that connects the inner peripheral ends of each linear wall 51 and one of the linear walls 51 and 51 adjacent thereto, and is inside the peripheral wall 5a. It has a bellows-shaped cross-sectional shape composed of an annular valley-shaped wall 53 that bends in a V-shape or a U-shape in the circumferential direction. In the cross section of each chevron wall 52, the inner peripheral surface 52a of the chevron wall 52 has a semicircular shape, and in the cross section of each valley wall 53, the outer peripheral surface 53a of the valley wall 53 has a semicircular shape. ing.

Both bellows 5 and 5 are synchronously expanded and contracted in opposite directions by connecting the disk-shaped movable plates 9 and 9 fixed to the bottom walls 5b and 5b with the connecting rod 10. That is, as shown in FIGS. 1 and 2, the connecting rod 10 interlocks and connects both bellows 5 and 5 so that when one bellows 5 is in the most contracted state, the other bellows 5 is in the most extended state. When one bellows 5 contracts, the other bellows 5 expands in conjunction with this.

The operating means for expanding and contracting the bellows 5 is generally composed of a piston / cylinder mechanism, a crank mechanism, an air cylinder mechanism, and the like, but in this example, the operating means is composed of an air cylinder mechanism. That is, in the bellows pumps shown in FIGS. 1 and 2, the operating means is between the bellows 5 and the movable plate 9 and the cylinder case 4 from the air supply / exhaust port 4a formed on the end wall of each cylinder case 4. By supplying and exhausting the pressurized air 4b to the formed space, each bellows 5 is configured to expand and contract in the axial direction. The air supply and exhaust from both air supply and exhaust ports 4a and 4a are alternately performed in synchronization, and air is supplied from one air supply and exhaust port 4a and at the same time exhausted from the other air supply and exhaust port 4a. The expansion / contraction operation, that is, the expansion / contraction operation of both pump chambers 6 and 6 is performed synchronously in the opposite directions. That is, the suction step (or discharge step) in one pump chamber 6 and the discharge step (or suction step) in the other pump chamber 6 are performed in synchronization, and the discharge steps (liquid F) in both pump chambers 6 and 6 are performed. The liquid is sent from the pump chamber 6 to the discharge passage 1 via the discharge side check valve 7) and the suction step (the liquid F is supplied from the suction passage 2 to the pump chamber 6 via the suction side check valve 8). The switching with the process) is performed at the same time. FIG. 1 shows the completed state of the suction process in the pump chamber 6 on the left side and the discharge process in the pump chamber 6 on the right side, and FIG. 2 shows the discharge process in the pump chamber 6 on the left side and the suction process in the pump chamber 6 on the right side. Indicates the start state of. Further, FIG. 3 shows the bellows 5 on the right side in FIG. 1, and FIG. 4 shows the bellows 5 on the left side in FIG.

As shown in FIGS. 1 and 2, each discharge side check valve 7 is formed in a valve case 71 attached to the pump head 3 with the inside communicating with the discharge passage 1 and a pump chamber formed in the valve case 71. A valve inlet passage 72 that opens in 6, a valve seat opening 73 formed at the opening end of the valve inlet passage 72, a valve body 74 that is built in the valve case 71 and opens and closes the valve seat opening 73, and a valve body 74. This is provided with a spring 75 that is attached to a valve closing position that closes the valve seat opening 73, and in the suction step in which the bellows 5 extends (the volume of the pump chamber 6 expands and changes), the valve body 74 Is held in the valve closing position by the urging force of the spring 75, the space between the discharge passage 1 and the pump chamber 6 is cut off, and the bellows 5 contracts (the volume of the pump chamber 6 contracts and changes) in the discharge process. The valve body 74 is configured to be displaced to the valve opening position where the valve seat opening 73 is opened against the urging force of the spring 74 due to the pressure increase of the pump chamber 6, and the discharge passage 1 and the pump chamber 6 are communicated with each other. ing.

As shown in FIGS. 1 and 2, each suction-side check valve 8 is formed in a valve case 81 attached to the pump head 3 with the inside communicating with the suction passage 2 and a pump chamber formed in the valve case 81. A valve outlet passage 82 that opens in 6, a valve seat opening 83 formed at the opening end of the valve outlet passage 82 on the suction passage 2 side, and a valve body 84 that is built in the valve case 81 to open and close the valve seat opening 83. The valve body 84 is provided with a spring 85 for urging the valve body 84 to a valve closing position where the valve seat opening 83 is closed, and in the discharge process, the valve body 84 has a back pressure (pressure of the pump chamber 6) and a spring 85. The valve body 84 is held in the valve closed position by the urging force of the pump chamber 6 to shut off between the suction passage 2 and the pump chamber 6, and in the suction process, the valve body 84 opposes the urging force of the spring 85 by the pressure drop of the pump chamber 6. It is configured so that the suction passage 2 and the pump chamber 6 are communicated with each other by being displaced to the valve opening position where the seat opening 83 is opened.

Of the pump components, appropriate materials are selected for the wetted members such as the bellows 5 that come into contact with the liquid F according to the pump conditions such as the properties of the liquid F. In this example, all the members including the bellows 5 are selected. The wetted member is made of a fluororesin such as polytetrafluoroethylene, which has excellent corrosion resistance and chemical resistance. Depending on the pump conditions, these wetted members may be made of a plastic material or a metal material other than fluororesin.

Thus, in the peripheral wall 5a of each bellows 5, as shown in FIGS. 3 to 5 or 3, 4, and 6, the extension direction of the bellows 5 on the chevron wall 52 (right direction in FIG. 3, left in FIG. 4). The first chevron wall portion 52A, which is a portion on the (direction) side, is a second chevron wall portion 52A on which the wall thickness T1 is on the contraction direction (left direction in FIG. 3, right direction in FIG. 4) of the bellows 5 on the chevron wall 52. It has a reinforcing portion 52C that is larger than the wall thickness T2 of the wall portion 52B.

Here, as shown in FIG. 5 or 6, the first chevron wall portion 52A extends in the extension direction of the bellows 5 from the center of curvature C of the inner peripheral surface 52a of the chevron wall 52 in the cross section of the chevron wall 52 (FIGS. 5 and 6). A straight line extending in the right direction in 6) (a straight line extending from the center of curvature C in the extending direction of the bellows 5 in parallel with the axis of the bellows 5 and hereinafter referred to as a "reference line") at 0 ° to 90 ° with respect to L1. It is a portion of the chevron wall 52 located in an angled region, and the second chevron wall portion 52B is a portion of the chevron wall 52 located in a region forming an angle of 90 ° to 180 ° with respect to the reference line L1. That is, the first chevron wall portion 52A is a chevron wall 52 located in a region on the extension direction side of the bellows 5 from a straight line (hereinafter referred to as “boundary line”) L2 that passes through the center of curvature C and is orthogonal to the axis of the bellows 5. The second chevron wall portion 52B is a portion of the chevron wall 52 located in the region on the contraction direction side of the bellows 5 with respect to the boundary line L2. The wall thicknesses T1 and T2 of the chevron wall portions 52A and 52B refer to the wall thicknesses of the chevron wall portions 52A and 52B on a straight line passing through the center of curvature C in the cross section of the chevron wall 52.

As shown in FIG. 5 or 6, the reinforcing portion 52C is a boundary portion between the first chevron wall portion 52A and the linear wall 51 connected to the first chevron wall portion 52A (hereinafter referred to as “first straight wall 51A”) and the first chevron wall portion. All parts or parts of the first chevron wall portion 52 excluding the boundary between the 52A and the second chevron wall portion 52B (hereinafter, the region of the first chevron wall portion 52A excluding the boundary portion is referred to as "the first chevron". The area where the reinforcing portion can be formed of the wall portion 52A ").

FIG. 5 shows a bellows 5 in which all the portions in the reinforcing portion formable region of the first chevron wall portion 52A are the reinforcing portion 52C, and FIG. 6 shows a part of the reinforcing portion forming region of the first chevron wall portion 52A. The bellows 5 with the reinforced portion 52C is shown. In the reinforcing portion 52C, as shown in FIG. 5 or 6, the wall thickness T1 at a position forming an arbitrary angle α (0 ° <α <90 °) with respect to the reference line L1 is the second chevron wall portion 52B. The wall thickness is set to be larger than the wall thickness T2 at a position forming an angle of β (= 180 ° −α) with respect to the reference line L1. That is, the wall thickness T1 of the reinforcing portion 52C is made larger than the wall thickness T2 of the second chevron wall portion 52B at all positions symmetrical with respect to the boundary line L2. For example, as shown by a chain line in FIGS. 5 and 6, when the symmetrical shape of the second chevron wall portion 52B with respect to the boundary line L2 is superimposed on the first chevron wall portion 52A, the outer peripheral surface in the cross section of the first chevron wall portion 52A. The 52b protrudes outward from the symmetrical outer peripheral surface 52c of the second chevron wall portion 52B in all portions of the reinforcing portion 52C. In the bellows 5 shown in FIGS. 5 and 6, the shape of the outer peripheral surface 52b in the cross section of the first chevron wall portion 52A is smoothly aligned with the outer peripheral surface of the second chevron wall portion 52B and the outer peripheral surface of the first linear wall portion 51A. It has a continuous arc shape. Further, as shown in FIG. 3, the shape of the inner peripheral surface 53b in the cross section of the valley wall 53 is a linear shape parallel to the axis.

Further, the wall thicknesses T3 and T4 of the first and second linear walls 51A and 51B are made uniform, respectively. In this example, the wall thickness T3 of the first linear wall 51A is shown in FIGS. 3 to 5 or As shown in FIGS. 3, 4 and 6, the wall thickness T1 of the second straight wall 51B is set to be larger than the wall thickness T4 of the second straight wall 51B, and the wall thickness T1 is the wall thickness of the second straight wall 51B in all the reinforcing portions 52C. It is larger than T4. The wall thickness of the linear wall in a general bellows pump such as a conventional bellows pump is the minimum necessary dimension as long as it has a strength that does not deform (swell outward) due to the liquid pressure inside the bellows (hereinafter, "general"). Although it is set to "thickness t"), the wall thickness T4 of the second linear wall 51B is set to be the same as or substantially the same as such a general wall thickness t.

By the way, the present inventor has conducted various experiments and studies to investigate the cause of cracks and breakage in the peripheral wall 5a of the bellows 5.
(1) Cavitation occurs in the peripheral wall 5a during the discharge process, that is, during the contraction operation of the bellows 5.
(2) In the region surrounded by the chevron wall 52 and the linear walls 51A and 51B connected to both ends thereof, the first chevron wall portion 52A which is the peripheral wall portion on the extension direction side of the bellows 5 and the first straight line connected thereto. Pushing pressure and impact force act on the shaped wall 51A due to the above cavitation, and stress is locally concentrated on the first chevron wall portion 52A.
(3) Stress concentration in the first chevron wall portion 52A does not occur at the boundary portion with the first linear wall portion 51A and the boundary portion with the second chevron wall portion 52B.
(4) If the wall thickness of the chevron wall is uniform and is the same as or substantially the same as the wall thickness of both linear walls connected to the chevron wall like the conventional bellows pump, the chevron wall portion on the extension direction side of the bellows (first chevron). The wall portion 52A) is insufficient in strength against the stress concentration, and a crack is generated at the stress concentration portion of the first chevron wall portion 52A, and the bellows is damaged from the crack portion.
(5) The stress concentration points, that is, the cracks and breakage occurrence points in the first chevron wall portion 52A are the material of the bellows 5, the properties of the liquid F to be pumped (presence or absence of foaming, temperature, pressure, etc.) and the expansion and contraction operation of the bellows 5. Although it depends on the pump operating conditions such as speed (particularly contraction operation speed), by conducting experiments under the conditions according to the pump operating conditions, the stress concentration points (cracks and breakage occurrence points) in the first chevron wall portion 52A are obtained in advance. ) Can be grasped with some accuracy,
There was found.

In the bellows 5 shown in FIG. 5 and the bellows 5 shown in FIG. 6, the stress concentration points are assumed in advance by the experiment of (5) above, and the assumed stress concentration points (hereinafter referred to as “assumed stress concentration points”) 52d. The wall thickness T0 is set to be the maximum of the wall thickness T1 of the reinforcing portion 52C.

In the bellows pump configured as described above, the wall thickness T1 of the reinforcing portion 52C of the first chevron wall portion 52A and the wall thickness T2 of the second chevron wall portion 52A (and the wall thickness of the second straight wall 52B) are used. Since the thickness T4) is made larger than the thickness T4) to increase the strength of the reinforcing portion 52C and the wall thickness T1 of the reinforcing portion 52C is set to the maximum wall thickness T0 at the assumed stress concentration portion 52d, the bellows 5 shrinks. It is possible to prevent cracks and breakages due to stress concentration due to cavitation during operation as much as possible, and the durability of each bellows 5 is greatly improved.

Further, since the shape of the outer peripheral surface 52b in the cross section of the first chevron wall portion 52A is a smooth arc shape as shown in FIG. 5 or FIG. 6, the reinforcing portion 52C is a portion other than the assumed stress concentration portion 52d. However, the wall thickness T1 does not change (decrease) more than the wall thickness (maximum wall thickness) T0 of the portion 52d, and the strength is not extremely inferior to that of the assumed stress concentration portion 52d. Therefore, even when the actual stress concentration point is slightly deviated from the assumed stress concentration point 52d, the occurrence of cracks and breakage at the stress concentration point is effectively prevented. In particular, as shown in FIG. 5, if all the parts of the first chevron wall portion 52A where the reinforcing portion can be formed are set as the reinforcing portion 52C and the entire first chevron wall portion 52A is reinforced, the actual stress is obtained. Even when the concentrated portion deviates significantly from the assumed stress concentrated portion 52d, the occurrence of cracks and breakage at the stress concentrated portion is effectively prevented.

By the way, unlike the first chevron wall portion 52A, stress is not locally concentrated on the first straight wall 51A, but it acts on the second straight wall 51B due to cavitation during the contraction operation of the bellows 5. Since a pressing force or an impact force larger than the pressing force (liquid pressure) acts, the first linear wall 51A may be deformed more than necessary, and may be fatigued or damaged during long-term use. Even when there is such a possibility, the wall thickness T3 of the first linear wall 51A is made larger than the wall thickness T4 of the second linear wall 51B as shown in FIG. 5 or 6, and the strength thereof is increased. By raising the height, deformation, fatigue, and breakage of the first straight line wall 51A can be reliably prevented, and the durability of the bellows 5 can be further improved.

The configuration of the bellows pump according to the present invention is not limited to the above-described embodiment, and can be appropriately improved or changed without departing from the basic principle of the present invention.

For example, the present invention can be similarly applied to a single-acting bellows pump that exerts a pump function by one bellows, in addition to the above-mentioned double-acting bellows pump.

Further, the shape of the bellows 5 is not limited to the above-described embodiment, and can be configured as shown in FIGS. 7 to 15, for example.

That is, in the bellows 5 shown in FIG. 7, the chevron wall 52 and the linear walls 51A and 51B have the same shape as the bellows 5 shown in FIGS. 1 to 4, but the shape of the inner peripheral surface 53b in the cross section of the valley wall 53. Is formed into an arc shape smoothly connected to the linear walls 51A and 51B.

Further, the bellows 5 shown in FIG. 8 has a substantially square cross-sectional shape of the first chevron wall portion 52A, and similarly to the bellows 5 shown in FIG. 5, all the portions of the reinforcing portion formable region of the first chevron wall portion 52A are covered. It is formed in the reinforcing portion 52C, and the portion on the straight line passing from the center of curvature C to the corner portion of the first chevron wall 52A is set as the assumed stress concentration portion 52d and has the maximum wall thickness T0. Further, the bellows 5 shown in FIG. 9 has an arcuate shape at a corner of the first chevron wall 52A in the bellows 5 shown in FIG. The bellows 5 shown in FIG. 10 is the bellows 5 shown in FIG. 8 with the corners of the first chevron wall 52A chamfered. In each bellows 5 shown in FIGS. 8 to 10, similarly to the bellows 5 shown in FIG. 5 or 6, the wall thickness T4 of the second linear wall 51B is the same as or substantially the same as the general wall thickness t. The wall thickness T3 of the first linear wall 51A is made larger than the wall thickness T4 of the second straight wall 51B, and the wall thickness T1 of all the parts in the reinforcing portion 52C is set to all the wall thickness T1 in the second chevron wall part 52B. The wall thickness T2 of the portion and the wall thickness T4 of the second linear wall portion 51B are made larger.

Further, in the bellows 5 shown in FIGS. 11 to 15, the wall thickness T3 of the first linear wall 51A is the same as or substantially the same as the wall thickness T4 of the second linear wall 51B.

In the bellows 5 shown in FIGS. 11 and 12, the cross-sectional shape of the first chevron wall portion 52A is substantially the same as that of the bellows 5 shown in FIG. 9, and all the portions of the reinforcing portion formable region of the first chevron wall portion 52A. Is used as the reinforcing portion 52C. In this bellows 5, the wall thickness T1 of all the portions of the reinforcing portion 52c is made larger than the wall thickness T2 of all the portions of the second chevron wall portion 52A and the wall thicknesses T3 and T4 of the linear walls 51A and 51B. is there. Further, the bellows 5 shown in FIG. 13 has a square cross-sectional shape of the first chevron wall portion 52A similar to that of the bellows 5 shown in FIG. It is as part 52C. Further, in the bellows 5 shown in FIG. 14, the outer peripheral surface 52b in the cross section of the first chevron wall portion 52A has an arc shape, and a part of the reinforcing portion formable region of the first chevron wall portion 52A is used as the reinforcing portion 52C. is there. In addition, in FIGS. 8 to 10 and 12 to 14, similarly to FIGS. 5 and 6, the symmetrical shape of the second chevron wall portion 52B with respect to the boundary line L2 is superimposed on the first chevron wall portion 52A. The outer peripheral surface 52c having a symmetrical shape is shown by a chain line.

Further, in each of the bellows 5 described above, the wall thickness T4 of the second linear wall 51B is the same as or substantially the same as the general wall thickness t, but the chevron wall 52 and both linear shapes at the time of maximum contraction of the bellows 5 are formed. When it is necessary to reduce the total thickness T3 + T4 (see FIG. 3) of the adjacent peripheral wall portion composed of the walls 51A and 51B or the valley wall 53 and the linear walls 51A and 512B, the load due to cavitation is applied. The wall thickness T4 of the second linear wall 51B, which has never been seen, can be made smaller than the general wall thickness t.

Further, the number of the first linear wall 51A and the second linear wall 51B in the bellows 5 and the connection form between the linear walls 51A and 51B and the bottom wall 5b and the flange wall 5c are also arbitrary, for example, FIG. 16 (A). )-(C) can be configured. That is, in the bellows 5 shown in FIG. 16A, a plurality of first linear walls 51A and a second linear wall 51B, which is one less than the peripheral wall 5a, are alternately arranged in the axial direction, and these straight lines are formed. The bottom wall 5b is connected to the inner peripheral end of the first straight wall 51A located at one end of the straight walls 51A and 51B groups, and the first straight wall 51A located at the other end of the straight walls 51A and 51B groups. A flange wall 5c is connected to the outer peripheral end portion of the above. Further, in the bellows 5 shown in FIG. 16B, a plurality of first linear walls 51A and a second linear wall 51B having one more peripheral wall 5a are arranged alternately in the axial direction, and these straight lines are formed. The bottom wall 5b is connected to the outer peripheral end of the second straight wall 51B located at one end of the straight walls 51A and 51B groups, and the second straight wall 51B located at the other end of the straight walls 51A and 51B groups. A flange wall 5c is connected to the inner peripheral end. Further, in the bellows 5 shown in FIG. 16C, the peripheral walls 5a are formed by alternately arranging a plurality of first linear walls 51A and the same number of second linear walls 51B in the axial direction, and these linear walls 51A. , The bottom wall 5b is connected to the outer peripheral end of the second linear wall 51B located at one end of the 51B group, and the outer peripheral end of the first straight wall 51A located at the other end of the straight walls 51A and 51B. The flange wall 5c is connected to the.

5 Bellows 5a Circumferential wall 51A 1st linear wall (straight line wall)
51B 2nd linear wall (straight line wall)
52 chevron wall 52a inner peripheral surface of chevron wall 52A 1st chevron wall part 52B 2nd chevron wall part 52C reinforcement part 53 valley wall C curvature center F liquid L1 reference line T0 wall thickness of reinforcement part (maximum wall thickness)
T1 Wall thickness of reinforcement part T2 Wall thickness of 2nd chevron wall part T3 Wall thickness of 1st linear wall T4 Wall thickness of 2nd straight wall

Claims (6)

A plurality of linear walls parallel to each other in the axial direction, a chevron wall connecting each linear wall and one of the adjacent linear walls at the outer peripheral end, and each linear wall and a linear shape adjacent thereto. A bellows pump configured to suck and discharge liquid with a bellows that has a bellows-shaped peripheral wall with a cross-section that consists of a valley-shaped wall that connects the inner peripheral ends to the other side of the wall and that can expand and contract in the axial direction. There,
The first chevron wall portion, which is a portion of the chevron wall on the extension direction side of the bellows, has a reinforcing portion having a wall thickness larger than the wall thickness of the second chevron wall portion, which is a portion of the chevron wall on the contraction direction side of the bellows. A bellows pump that features that. The reinforcing portion is all or a part of the first chevron wall portion except the boundary portion with the straight wall portion and the boundary portion with the second chevron wall portion, and in the reinforcing portion, the chevron wall The wall thickness at a position forming an arbitrary angle α (0 ° <α <90 °) with respect to a straight line extending in the extending direction of the bellows from the center of curvature of the inner peripheral surface of the chevron wall in the cross section of the second chevron wall. The bellows pump according to claim 1, wherein the bellows pump is larger than the wall thickness at a position forming an angle β (= 180 ° −α) with respect to the straight line in the portion. The bellows pump according to claim 1, wherein the wall thickness of the linear wall connected to the first chevron wall portion is larger than the wall thickness of the linear wall connected to the second chevron wall portion. The bellows pump according to claim 2, wherein the wall thickness of the linear wall connected to the first chevron wall portion is larger than the wall thickness of the linear wall connected to the second chevron wall portion. The bellows according to claim 1, wherein the wall thickness of the linear wall connected to the first chevron wall portion is the same as or substantially the same as the wall thickness of the linear wall connected to the second chevron wall portion. pump. The bellows according to claim 2, wherein the wall thickness of the linear wall connected to the first chevron wall portion is the same as or substantially the same as the wall thickness of the linear wall connected to the second chevron wall portion. pump.

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