Impeller For Pump

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority Japanese patent application 2017-042478 filed Mar. 7, 2017, the disclosure of which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to an impeller for a pump used for cooling water pumps of outboard engines, bilge pumps, and the like and, in particular, to an impeller for a pump that prevents vanes from departing from an inner circumferential face of a pump housing and can thereby enhance discharging performance.

BACKGROUND

Conventionally known is an impeller for a pump used for cooling water pumps of outboard engines, bilge pumps, and the like having a structure illustrated in FIG. 4 (Patent Documents 1 and 2).

In FIG. 4, the reference numeral 100 is an impeller for a pump rotatably held within a pump housing 200. The impeller 100 for a pump is mounted on a rotating shaft 300 arranged at an eccentric position within the pump housing 200. The impeller 100 for a pump includes a plurality of vanes 110 made of a rubber-like elastic material and is in elastic contact with an inner circumferential face 210 of the pump housing 200.

The above-described impeller 100 for a pump divides the inside of the pump housing 200 into a plurality of compartments 120 by the vanes 110. When the impeller 100 for a pump is rotated with the rotating shaft 300, the vanes 110 are bent in a direction opposite to a rotational direction (the arrow R) of the impeller 100 for a pump. When the impeller 100 for a pump is rotated, the compartment 120 between two adjacent vanes 110 and 110 decreases in volume on a side in which the rotating shaft 300 is near the inner circumferential face 210 of the pump housing 200 and increases in volume on a side in which the rotating shaft 300 is far from the inner circumferential face 210 of the pump housing 200.

When the volume of the compartment 120 increases (a direction of the arrow R1), water is sucked from the outside to this compartment 120 through a suction port (not illustrated) provided in the pump housing 200. When the volume of the compartment 120 decreases (a direction of the arrow R2), the water is discharged from this compartment 120 to the outside through a discharge port (not illustrated) provided in the pump housing 200.

In the impeller 100 for a pump described in Patent Document 1, the vanes 110 are formed inclined in a direction opposite to the rotational direction of the impeller 100 relative to a radial direction. Such inclination decreases the displacement amount (the interference) of the vanes 110 from a natural state when the vanes are bent by the rotation of the impeller 100 for a pump, and thus the fatigue of the material by the displacement is reduced.

SUMMARY OF THE INVENTION

In recent years, the enhancement of discharging performance has been demanded for the impeller for a pump described above. To enhance discharging performance, a reaction force that the vanes 110 generate is required to be increased to increase a pressing force against the inner circumferential face 210 of the pump housing 200 and to cause the vanes 110 not to depart from the inner circumferential face 210 by water pressure generated during rotation.

Examples of means for increasing the reaction force that the vanes 110 generate in the conventional impeller 100 for a pump include increasing the rubber hardness of the vanes 110, increasing the thickness of the vanes 110, and increasing the length of the vanes 110.

To maintain elongation characteristics and fatigue characteristics at favorable levels, the rubber hardness of the vanes 110 is a Shore A hardness Hs (JIS K6253) of 70 at the maximum; exceeding this value is not desirable. Consequently, it is impracticable to increase the rubber hardness of the vanes 110 in order to increase the reaction force that the vanes 110 generate.

If the thickness of the vanes 110 is increased, the compartment 120 between two vanes 110 and 110 becomes narrower, and a suction amount and a discharge amount decrease. Consequently, it is impracticable to increase the thickness of the vanes 110 in order to increase the reaction force that the vanes 110 generate.

If the length of the vanes 110 is increased, the diameter of the impeller 100 for a pump increases, and the number of products that can be manufactured from one rubber mold decreases, which causes manufacturing costs to increase. Consequently, it is impracticable to increase the length of the vanes 110 in order to increase the reaction force that the vanes 110 generate.

The present invention has been made in view of the foregoing circumstances, and an object thereof is to provide an impeller for a pump that increases a reaction force that vanes generate by increasing an effective interference when being mounted on a housing without increasing the diameter of the impeller and the manufacturing costs of the impeller, prevents the vanes from departing from an inner circumferential face of the housing, and can thereby enhance discharging performance.

Other objects of the present invention will be made clear by the following description.

To achieve at least one of the abovementioned objects, according to an aspect of the present invention, an Impeller for pump reflecting one aspect of the present invention is as follows.

An impeller for a pump comprises a cylindrical bush for being rotatably held at an eccentric position within a cylindrical pump housing via a rotating shaft and a plurality of vanes that are fixed to an outer circumferential face of the bush and radially extend for dividing the inside of the pump housing into a plurality of compartments. Each of the vanes being made of a rubber-like elastic material and being formed inclined in a rotational direction of the bush relative to a radial direction from the rotating shaft of the bush.

The present invention can provide an impeller for a pump that increases a reaction force that vanes generate by increasing an effective interference when being mounted on a housing without increasing the diameter of the impeller and the manufacturing costs of the impeller, prevents the vanes from departing from an inner circumferential face of the housing, and can thereby enhance discharging performance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view of an embodiment of an impeller for a pump according to the present invention.

FIG. 2 is a schematic diagram illustrating an inclined structure of vanes of the impeller for a pump illustrated in FIG. 1.

FIG. 3 is an enlarged view of the principal part of the impeller for a pump illustrated in FIG. 2.

FIG. 4 is a plan view of a conventional impeller for a pump.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following describes an embodiment of the present invention with reference to the accompanying drawings.

An impeller for a pump of the present invention is used for cooling water pumps of outboard engines, bilge pumps, and the like.

FIG. 1 is a schematic cross-compartmental view of an embodiment of the impeller for a pump of the present invention, FIG. 2 is a schematic diagram illustrating an inclined structure of vanes of the impeller for a pump illustrated in FIG. 1, and FIG. 3 is an enlarged view of the principal part of the impeller for a pump illustrated in FIG. 2.

In FIG. 1, the reference numeral 1 is an impeller for a pump, and the impeller 1 for a pump is rotatably held within a pump housing 2.

The pump housing 2 is made of a metallic material or the like in a cylindrical shape the upper and lower ends of which are blocked and has a suction port (not illustrated) on a lower face side and a discharge port (not illustrated) on an upper face side, for example. A material excellent in corrosion resistance is preferably selected for the material of the pump housing 2 when being in contact with highly corrosive water.

As illustrated in FIG. 1 to FIG. 3, the impeller 1 for a pump has a cylindrical bush 13 and a plurality of vanes 11 radially formed on an outer circumferential face of the bush 13. In this embodiment, the impeller 1 for a pump has six vanes 11.

As illustrated in FIG. 2 and FIG. 3, the vanes 11, in a natural state before being mounted on the housing, are inclined in a rotational direction (a direction indicated by the arrow R) of the impeller 1 for a pump. Means for inclining them is not limited to particular means; in the present embodiment, they are inclined by a method of forming. The details of the inclined structure will be described below.

In the form illustrated in FIG. 1, the impeller 1 is rotated, and the vanes 11 are in sliding contact with an inner circumferential face 21 of the pump housing 2 and are thereby bent in a direction opposite to a rotational direction R of the impeller 1. The impeller 1 is rotated at a rotational speed of about 6,000 RPM, for example.

The bush 13 is made of a resin material such as a thermoplastic resin or a thermosetting resin. The material of the bush 13 is not limited to a particular material; a polyamide resin excellent in strength can be selected to use, for example.

The vanes 11 are made of a rubber-like elastic material such as chloroprene rubber (CR) or nitrile rubber (NBR) and are bonded to the outer circumferential face of the bush 13. A method of bonding is not limited to a particular method; with an adhesive applied to the bush 13, the vanes 11 can be baked thereon to be formed, or the vanes 11 can be bonded to the bush 13 with an adhesive after being formed.

To maintain elongation characteristics and fatigue characteristics at favorable levels, the rubber hardness of the vanes 11 can be a Shore A hardness Hs (JIS K6253) in the range of 45 to 75. As described below, the vanes 11 are inclined to the rotational direction, whereby rubber hardness with favorable fatigue characteristics and low hardness can be selected. However, a rubber hardness of less than 45 gives an excessively low rubber reaction force and is thus not used.

The bush 13 is mounted on a rotating shaft 3 arranged at an eccentric position within the pump housing 2 and is rotatably held by this rotating shaft 3.

The bush 13 has a shaft hole 13a along its central axis, and the rotating shaft 3 is inserted into this shaft hole 13a. A keyway 13b is provided on an inner circumferential face of the shaft hole 13a. A parallel key 3a formed on an outer circumferential face of the rotating shaft 3 fits into this keyway 13b to prevent the rotating shaft 3 from idling.

The bush 13 is rotatingly driven together with the vanes 11 by a power source (not illustrated) via the rotating shaft 3.

The vanes 11 bring distal end parts 12 into elastic contact with the inner circumferential face 21 of the pump housing 2.

The vanes 11 may provide sliding contact members made of a resin material on the distal end parts 12 to bring this sliding contact members into elastic contact with the inner circumferential face 21 of the pump housing 2. The sliding contact members can be formed so as to cover the distal end parts 12 of the vanes 11. The sliding contact members are preferably made of a fluorine resin, a polyamide resin, or the like excellent in sliding resistance and the like. In this case, small sliding resistance can be kept stably for a long term, the wearing out and damage of the impeller 1 for a pump can be prevented, and rotational torque is reduced, whereby power loss can be reduced and fuel economy can be improved.

As illustrated in FIG. 1, the impeller 1 for a pump divides the inside of the pump housing 2 into a plurality of compartments 14 by the vanes 11. When impeller 1 for a pump is rotated via the rotating shaft 3 and the bush 13, the vanes 11 are bent in a direction opposite to the rotational direction (a direction indicated by the arrow R in FIG. 1) of the impeller 1.

In this process, the vanes 11 generate reaction forces (restoring forces) that press the inner circumferential face 21 of the pump housing 2 by a distal end side 11a including the distal end part 12. The reaction forces (restoring forces) bring the distal end side 11a of the vane 11 into pressing contact with the inner circumferential face 21 of the pump housing 2.

In this impeller 1 for a pump, the pressing forces by the vanes 11 against the inner circumferential face 21 of the pump housing 2 are large, and the vanes 11 are prevented from departing from the inner circumferential face 21 by water pressure generated during rotation.

When the impeller 1 for a pump is rotated, each of the compartments 14 between two vanes 11 and 11 decreases in volume on a side (the left side in FIG. 1) in which the rotating shaft 3 is near the inner circumferential face 21 of the pump housing 2 to increase pressure within the compartment 14, and increases in volume on a side (the right side in FIG. 2) in which the rotating shaft 3 is far from the inner circumferential face 21 of the pump housing 2 to reduce the pressure within the compartment 14.

In a section (a section indicated by the arrow R1) in which the volume of the compartment 14 increases, water is sucked from the outside to this compartment 14 through the suction port (not illustrated). In a section (a section indicated by the arrow R2) in which the volume of the compartment 14 decreases, the water is discharged from this compartment 14 to the outside through the discharge port (not illustrated).

The following specifically describes the inclined structure of the vanes based on FIG. 2 and FIG. 3. As illustrated in the drawings, the vanes 11 of the impeller 1 for a pump are formed in a shape inclined by an angle θ in a rotational direction R of the bush 13 relative to a radial direction from a central axis 3c of the rotating shaft 3 holding the bush 13.

The vanes 11 are formed inclined by the angle θ in the rotational direction R side of the bush 13, and when this impeller 1 for a pump is rotated, as illustrated in FIG. 1, the distal end side (a lip part) 11a is bent in a counter-rotational direction with an intermediate part 11c as a starting point, and a pressing force F against the inner circumferential face 21 of the pump housing 2 increases; in other words, an interference increases.

This pressing force F acts so as to return the distal end side 11a of the vane 11 to its original state.

The pressing force F against the inner circumferential face 21 of the pump housing increases, and the action of the pressing force F (the reaction force) to return the distal end side 11a to its original state acts on the intermediate part 11c.

Consequently, a basal end side 11b is prevented from bending in the counter-rotational direction to act so as to maintain the state inclined in the rotational direction R.

In other words, the pressing force F increases, and consequently, the state in which the basal end side 11b of the bane 11 is inclined in the rotational direction R can be maintained.

In this impeller 1, when being rotated in the pump housing 2, the interference of the vanes 11 increase, whereby the reaction force generated in the vanes 11 increases.

The pressing force against the inner circumferential face 21 of the pump housing 2 is large, thereby preventing the vanes 11 from departing from the inner circumferential face 21, and in each of the compartments 14 of the pump housing 2 divided by the vanes 11, water does not leak to another compartment. Further, in each of the compartments 14, water does not leak to another compartment, and consequently, discharging performance is enhanced.

In this impeller 1, the vanes 11 are inclined in the rotational direction R, whereby even when the thickness of the vanes 11 is made slightly smaller than conventional one, the pressing force F against the inner circumferential face 21 can be increased. Consequently, the compartment 14 between two vanes 11 and 11 can also be increased, and a suction amount and a discharge amount can be increased.

Further, this impeller 1 for a pump does not increase its diameter compared with conventional one by inclining the vanes 11 by the inclined structure unique to the present invention. Consequently, the number of products that can be manufactured from one rubber mold does not decrease, and manufacturing costs do not increase.

FIG. 3 is the enlarged view of the principal part of the impeller for a pump illustrated in FIG. 2.

As illustrated in FIG. 3, the vane 11 is inclined by the angle θ, and therefore a length L2 of the vane 11 is longer than a length L1 (a length that allows the vane 11 to be constantly in sliding contact with the inner circumferential face 21 of the pump housing 2 and be bent) required when this vane 11 is not inclined.

If the inclination angle θ of the vane 11 is small, the length L2 of the vane 11 is close to the length L1. As the inclination angle θ increases, the length L2 of the vane 11 increases relative to the length L1.

If the inclination angle θ of the vane 11 is excessively small, the interference does not sufficiently increase when the impeller 1 rotates in the housing 2, and a required reaction force cannot be generated. In contrast, if the inclination angle θ of the vane 11 is excessively large, the vane 11 cannot be bent even when the impeller 1 rotates.

Consequently, the inclination angle θ of the vane 11 is preferably about 0.1 degrees to 10 degrees. This inclination angle θ may be an angle appropriate enough to enable the state in which the basal end side 11b is inclined in the rotational direction R to be maintained in relation to the above-described pressing force F during rotation.

A thickness T of the vane 11 can be determined as appropriate in relation to the inner diameter of the pump housing 2. The inclination angle θ and the thickness T of the vane 11 are preferably designed appropriately enough to enable the state in which the basal end side 11b is inclined in the rotational direction R to be maintained during rotation.

Because these conditions are satisfied, the vanes 11 can favorably bent, sufficiently increase the interference, and generate the required reaction force when the impeller 1 for a pump is rotated, and consequently, discharging performance can be enhanced.

It is understood that the present invention can adopt various embodiments so long as they do not depart from the gist of the present invention, not limited to the above-described embodiment.

EXPLANATIONS OF LETTERS OR NUMERALS

1 Impeller for pump

11 Vane

11
a Distal end side

11
b Basal end side

11
c Intermediate part

12 Distal end part

13 Bush

14 Compartment

2 Pump housing

21 Inner circumferential face

3 Rotating shaft

Impeller For Pump

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Priority Claims (1)