Self-priming pump

Abstract

The present invention relates to a self-priming pump capable of preventing a swirl flow from developing during the self-priming operation and assuring the smooth flow of a stream of water during the pumping operation.

Description

TECHNICAL FIELD

[0001] The present invention relates to a self-priming pump used for pumping.

BACKGROUND ART

[0002] Conventionally, there are known self-priming pumps described in Japanese Patent Publication No. S50-21682 and Japanese Utility Model Registration No. S51-47602.

[0003] The former self-priming pump comprises a large scroll casing and a small scroll casing formed around an impeller, a main line extending from the large scroll casing, an auxiliary line extending from the small scroll casing, and a casing in which an upper end of the auxiliary line is spirally brought into communication with the main line along a wall surface of the main line from a tangent direction thereof. The main line is formed with a swirl flow forming space in which self-primed water accumulated in the casing is discharged into the main line from the small scroll casing through the auxiliary line together with air during self-priming operation, thereby generating a swirl flow in the main line to carry out air-water separation. A mushroom-like lump is provided in the main line below the swirl flow forming space as means for eliminating the swirl flow.

[0004] In the latter self-priming pump, a bag-like liquid stagnation casing is provided in an intermediate portion of a trap which is in communication with a suction opening of the casing.

[0005] In the self-priming pump, swirl flow is generated in the swirl flow forming space during the self-priming operation to generate centrifugal separation, and the air-water separation is carried out using the centrifugal separation. At that time, there is generated a circulation flow in which self-primed liquid interflows into the main line from the small scroll casing through the auxiliary line, and returns into the large scroll casing from the main line and again flows into the auxiliary line from the small scroll casing. With the circulation flow, the swirl flow develops like tornado. If the swirl flow develops such as to extend downward, bubble again returns into the large scroll casing, which hinders the self-priming operation and thus, it is necessary to prevent this.

[0006] However, if the mushroom-like lump is provided below the swirl flow forming space as in the conventional pump (former pump), there is a problem that although the swirl flow is prevented from developing by the mushroom-like lump during the self-priming operation, this mushroom-like lump hinders the water flow during the pumping operation, and since a cross-sectional area of the portion where the mushroom-like lump is provided and a cross-sectional area of a portion where the mushroom-like lump is terminated (swirl flow forming space) are largely different, the water flow is disturbed and the pumping performance becomes unstable.

[0007] Further, since air is discharged from a suction pipe while circulating the self-primed liquid in the casing, it is necessary to accumulate the self-primed liquid in the casing without fail.

[0008] However, if the bag-like liquid stagnation casing is provided in the intermediate portion of the trap which is in communication with the suction opening of the casing as in the conventional pump (latter pump), although the bag-like liquid stagnation casing is provided, since the entire bag-like liquid stagnation casing is the straight pipe-like trap, its entire length becomes long, and the suction-side structure can not be made compact.

[0009] Further, since the trap has the straight pipe-like shape, siphonage is prone to be generated, water (liquid) flows backward from the casing into the suction pipe by the siphonage, and the self-primed liquid can not be accumulated. To prevent this, it is necessary to largely set a vertical level difference such that a trap inlet port is set higher than a trap outlet port. As a result, a pumping load is increased, the self-priming time is increased, and the pumping ability must be enhanced.

[0010] The present invention has been accomplished to solve the above conventional problems, and it is a first object to provide a self-priming pump capable of preventing a swirl flow from developing during the self-priming operation and assuring the smooth flow of a stream of water during the pumping operation.

[0011] It is a second object of the invention to provide a self-priming pump capable of making the suction side structure compact, reducing a pumping load and reducing the self-priming time without increasing the pumping ability, and capable of reliably accumulating self-primed liquid in a casing when the pump is stopped.

DISCLOSURE OF THE INVENTION

[0012] To solve the first object, the present invention (claim 1) provides a self-priming pump comprising a casing in which a large scroll casing and a small scroll casing are formed around an impeller, a main line extends from the large scroll casing, and a spout is formed on an upper end of the main line, an auxiliary line extends from the small scroll casing, and an upper end of the auxiliary line is spirally brought into communication with the main line along a wall surface of the main line from a tangent direction thereof, a swirl flow forming space being formed in the main line, and in the swirl flow forming space, self-primed water accumulated in the casing being discharged into the main line together with air from the small scroll casing through the auxiliary line during self-priming operation, thereby generating swirl flow in the main line, and air-water separation being carried out, wherein

[0013] a plate member for eliminating the swirl flow extends in an extension direction of the main line in the main line below the swirl flow forming space.

[0014] This self-priming pump is characterized in that the swirl flow forming space is provided below the plate member as means for eliminating the swirl flow during the self-priming operation.

[0015] If the plate member is provided below the swirl flow forming space, when the swirl flow generated in the swirl flow forming space tries to extend downward, the swirl flow can be obstructed by a surface of the plate member, and it is possible to eliminate the swirl flow which tries to extend downward.

[0016] Further, since the plate member extends in the extension direction of the main line, the plate member does not hinder the water flow during the pumping operation. Only a cross-sectional area corresponding to a plate thickness of the plate member is varied between a portion where the plate member is provided and a portion where the plate member is terminated (swirl flow forming space) and therefore, water flow is not disturbed, and pumping performance does not become unstable.

[0017] To solve the second object, the present invention (claim 2) provide a self-priming pump wherein a water tank for self-primed water is provided between the suction opening and a suction pipe, the water tank comprises a reserving portion swelling in the lateral direction and having a cross-sectional area greater than an opening area of the suction opening, a water outlet which laterally opens into a bottom end of the reserving portion and which is in communication with the suction opening substantially horizontally, and a water inlet which laterally opens into an upper end of the reserving portion and which is in communication with the suction pipe, and a lower end level of the water inlet is formed higher than an upper end level of the water outlet.

[0018] In this self-priming pump, since the reserving portion of the water tank is allowed to swell in the lateral direction, necessary self-primed liquid can be accumulated only by this reserving portion and thus, it is possible to reliably accumulate the self-primed liquid in the casing 1 when the pump is stopped.

[0019] Since it is possible to reliably accumulate the necessary self-primed liquid only by the reserving portion, the entire length of the pump need not be increased unlike the conventional straight pipe like pump, and it is unnecessary to largely set a vertical level difference between the inflow port and the outflow port. Therefore, the suction side structure can be made compact, and a pumping load can be reduced. Thus, it is possible to reduce the self-priming time without increasing the pump ability.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is an axial sectional view showing an essential portion of a self-priming pump according to a first embodiment of the present invention.

[0021] FIG. 2 is a sectional side view showing a casing of the self-priming pump.

[0022] FIG. 3 is a sectional view taken along a line A-A in FIG. 2.

[0023] FIG. 4 is a sectional view taken along a line B-B in FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

[0024] An embodiment of the present invention will be explained in detail with reference to the drawings. A concrete structure of the invention is not limited to this embodiment.

[0025] FIG. 1 is an axial sectional view showing an essential portion of a self-priming pump according to a first embodiment of the present invention, FIG. 2 is a sectional side view showing a casing of the self-priming pump, FIG. 3 is a sectional view taken along a line A-A in FIG. 2, and FIG. 4 is a sectional view taken along a line B-B in FIG. 1.

[0026] In the drawings, a reference number 1 represents a casing, and an impeller 2 is accommodated in the casing 1. A large scroll casing 10 and a small scroll casing 11 are formed around the impeller 2. A main line 12 extends from the large scroll casing 10, and a spout 13 is formed on an upper end of the main line 12. An auxiliary line 14 extends from the small scroll casing 11, and an upper end of the auxiliary line 14 is spirally brought into communication with the main line 12 along a wall surface of the main line 12 from a tangent direction thereof.

[0027] A swirl flow forming space 15 is formed in the main line 12. In the swirl flow forming space 15, self-primed water accumulated in the casing 1 is discharged into the main line 12 together with air from the small scroll casing 11 through the auxiliary line 14 during self-priming operation, thereby generating swirl flow in the main line 12, and air-water separation is carried out. As shown in FIG. 3, a plate member 16 extends in an extension direction of the main line 12 below the swirl flow forming space 15.

[0028] A suction opening 17 is formed on a central portion of one side of the casing 1. A water tank 4 for self-primed water is provided between the suction opening 17 and a suction pipe 3.

[0029] As shown in FIG. 4, the water tank 4 comprises a reserving portion 40 swelling in the lateral direction and having a cross-sectional area greater than an opening area of the suction opening 17, a water outlet 41 which laterally opens into a bottom end of the reserving portion 40 and which is in communication with the suction opening 17 substantially horizontally, and a water inlet 42 which laterally opens into an upper end of the reserving portion 40 and which is in communication with the suction pipe 3. In this case, a lower end level L1 of the water inlet 42 is formed higher than an upper end level L2 of the water outlet 41 so that water is accumulated up to the lower end level L1 of the water inlet 42 so that the casing 1 is filled with self-primed water.

[0030] An impeller shaft 20 is supported at a central portion of the other side of the casing 1, and the impeller shaft 20 is connected to a driving motor (not shown).

[0031] In the self-priming pump, circulation flow is generated in such a manner that self-primed liquid interflows into the main line 12 from the small scroll casing 11 through the auxiliary line 14 during the self-priming operation, the self-primed liquid returns into the large scroll casing 10 from the main line 12 and again flows into the auxiliary line 14 from the small scroll casing 11. During that time, swirl flow is generated in the swirl flow forming space 15, and air-water separation is carried out by centrifugal separation caused by this swirl flow.

[0032] The swirl flow tries to develop into tornado with the circulation flow, but since the self-priming pump is provided with the plate member 16 below the swirl flow forming space 15, the swirl flow can be obstructed by a surface of the plate member 16, and it is possible to eliminate the swirl flow which tries to extend downward.

[0033] Further, since the plate member 16 extends in the extension direction of the main line 12, the plate member 16 does not hinder the water flow during the pumping operation. Only a cross-sectional area corresponding to a plate thickness of the plate member 16 is varied between a portion where the plate member 16 is provided and a portion where the plate member 16 is terminated (swirl flow forming space 15) and therefore, water flow is not disturbed, and pumping performance does not become unstable.

[0034] In the self-priming pump, since air is discharged from a suction pipe 3 while circulating the self-primed liquid in the casing 1, it is necessary to accumulate the self-primed liquid in the casing 1 without fail.

[0035] Thereupon, in this self-priming pump, the reserving portion 40 of the water tank 4 is allowed to swell in the lateral direction. Necessary self-primed liquid can be accumulated only by this reserving portion 40 and thus, it is possible to reliably accumulate the self-primed liquid in the casing 1 when the pump is stopped.

[0036] Since it is possible to reliably accumulate the necessary self-primed liquid only by the reserving portion 40 , the entire length of the pump need not be increased, and it is unnecessary to largely set a vertical level difference between the inflow port (water outlet 41) and the outflow port (water inlet 42). Therefore, the suction side structure can be made compact, and a pumping load can be reduced.

[0037] The water tank 4 and the casing 1 may be integrally molded with each other.

[0038] INDUSTRIAL AVAILABILITY

[0039] As explained above, the self-priming pump of the present invention (claim 1) has an effect that it is possible to prevent a swirl flow from developing during the self-priming operation and to assure the smooth flow of a stream of water during the pumping operation.

[0040] The self-priming pump of the invention (claim 2) has an effect that it is possible to make the suction side structure compact, to reduce a pumping load and reducing the self-priming time without increasing the pumping ability, and to reliably accumulate self-primed liquid in a casing when the pump is stopped.

Claims

1. A self-priming pump comprising a casing in which a large scroll casing and a small scroll casing are formed around an impeller, a main line extends from said large scroll casing, and a spout is formed on an upper end of said main line, an auxiliary line extends from said small scroll casing, and an upper end of said auxiliary line is spirally brought into communication with said main line along a wall surface of said main line from a tangent direction thereof, a swirl flow forming space being formed in said main line, and in said swirl flow forming space, self-primed water accumulated in said casing being discharged into said main line together with air from said small scroll casing through said auxiliary line during self-priming operation, thereby generating swirl flow in said main line, and air-water separation being carried out, wherein a plate member for eliminating the swirl flow extends in an extension direction of said main line in said main line below said swirl flow forming space.

2. A self-priming pump wherein a water tank for self-primed water is provided between said suction opening and a suction pipe, said water tank comprises a reserving portion swelling in the lateral direction and having a cross-sectional area greater than an opening area of said suction opening, a water outlet which laterally opens into a bottom end of said reserving portion and which is in communication with said suction opening substantially horizontally, and a water inlet which laterally opens into an upper end of said reserving portion and which is in communication with said suction pipe, and a lower end level of said water inlet is formed higher than an upper end level of said water outlet.