JPH0660792U - Vane pump - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent a decrease in self-sufficiency and discharge force due to contact between the inner wall surfaces of both ends of the pump chamber 11 and the rotor 12. An output shaft 1 of a motor 18 is inserted into a shaft hole 2 of a rotor 12 in a loosely fitted state in which axial relative movement is possible and engaged with each other in a rotational direction.
Are restrained from each other in the axial direction to prevent axial movement of the rotor 12 due to a change in the relative positional relationship between the output shaft 1 and the pump chamber 11 with respect to the axial direction.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a small vane pump built in, for example, an electric device as a water supply means.

[0002]

[Prior art]

 The vane pump is generally used when a large discharge pressure or self-sufficiency (a force that allows a pump to be installed at a position higher than the liquid surface and suck up the liquid from a dry state inside the pump chamber) is used. Has a structure as shown in FIG. That is, the rotor 12 is rotatably arranged at an eccentric position in the pump chamber 11 formed in the casing 10, and the vanes 14 are formed in each of the plurality of vane grooves 13 radially formed in the rotor 12. Are arranged so as to project and retract in the radial direction. An output shaft 19 of a motor 18 (see FIG. 6) protruding into the pump chamber 11 is press-fitted into the shaft hole 12a of the rotor 12.

In this type of vane pump, when the rotor 12 is rotationally driven in the X direction by the output shaft 19, the vanes 14 are brought into sliding contact with the peripheral wall of the pump chamber 11 by a centrifugal force, and the peripheral wall and the peripheral wall are eccentric to each other. By moving the vanes 14 in the crescent-shaped space 15 between the rotors 12, the fluid is sucked from the suction port 16 while the fluid is discharged from the discharge port 17, but the discharge pressure and the self-sufficiency are improved. In order to do so, it is necessary to process the surfaces of the pump chamber 11 and the rotor 12 with a tolerance of μm with high accuracy, and to make the gap between the facing end faces of the rotor 12 and the pump chamber 11 as small as possible.

However, for example, in the case of a small general-purpose vane pump to be incorporated in an electric device such as a water supply means to a steam generating part of an electric iron, it is difficult to perform highly accurate machining by cutting a metal material from the viewpoint of cost. As shown in FIG. 6, the present inventors formed an expansion chamber 20 in the casing 10 which is expanded stepwise from the open end of the pump chamber 11, and the open end is formed in the expansion chamber 20. Bending plate 21 made of metal arranged so as to close the second bending plate 22 disposed inside the expansion chamber 20 outside the bending plate 21 and having an opening 22a in the center, and an outer end surface of the casing 10. A cover 23 having a convex portion 23a fixed to the expansion chamber 20 by a screw member 25, and between the flexible plates 21 and 22 and between the outer flexible plate 22 and the convex portion 23a. Through We have developed a small vane pump equipped with a pair of O-rings 24 that are present and seal the gap between the expansion chamber 20 and the wall surface.

That is, in this vane pump, the O-ring 24 is compressed when the cover 23 is completely fastened to the casing 10 by the screw member 25, so that the O-ring 24, the flexible plate 21, and the convex portion 24 a of the cover 23. By pressurizing the closed space S surrounded by, the flexible plate 21 forming one end wall surface of the pump chamber 11 flexes toward the inside of the pump chamber 11, and thereby the rotor 12 has axially opposite sides. The existing gaps are made smaller and self-sufficiency is improved. Therefore, according to this configuration, the dimensional accuracy of the casing 10, the rotor 12, and the like can be roughened, so that the casing 10 can be manufactured by molding a synthetic resin material, and the cost can be reduced.

[0006]

[Problems to be solved by the device]

 However, in this case, when the temperature change factor due to the fluid passing through the pump chamber 11 or the heat generation of the motor 18 acts, the thermal expansion coefficient of the synthetic resin casing 10 and the metal motor output shaft 19 that constitute the pump chamber 11 is increased. The relative positional relationship between the casing 11 and the rotor 12 changes by about several tens of μm due to the difference. Therefore, if the gaps on both sides of the rotor 12 in the axial direction are made extremely small in order to improve the self-sufficiency and the discharge force, the end face 12b of the rotor 12 on the motor 18 side and the bottom face of the pump chamber 11 are improved when the ambient temperature is high. When the ambient temperature is low, the end face 12c of the rotor 12 on the side opposite to the motor and the flexible plate 21 easily come into contact with each other, and the power loss of the motor increases and the rotation speed decreases. However, there was a problem that high self-sufficiency and discharge power could not be realized. The present invention is intended to prevent the reduction of the self-sufficiency and the discharge force due to the contact between both end surfaces of the pump chamber and the rotor.

[0007]

[Means for Solving the Problems]

 The above technical problems can be effectively solved by the present invention. That is, the vane pump according to the present invention has a rotor rotatably arranged in an eccentric position in the pump chamber and a plurality of vane grooves radially formed in the rotor, the vanes being arranged so as to be projected and retracted in the radial direction. The output shaft of the motor is inserted into the shaft hole of the rotor in a loosely fit state in which the output shaft of the motor is relatively movable in the axial direction, and is engaged with each other in the rotational direction. In this case, more preferably, a large number of dynamic pressure generating means are formed on both end surfaces of the rotor.

[0008]

[Action]

 Since the output shaft of the motor is inserted into the shaft hole of the rotor in a loosely fit state so that the output shaft and the rotor can move relative to each other in the axial direction, the behavior of the output shaft and the rotor in the axial direction are substantially separated from each other. The position of is not affected by a change in the relative positional relationship between the output shaft and the pump chamber with respect to the axial direction or an error. Further, the dynamic pressure generating means formed on both end faces of the rotor generate a dynamic pressure in the fluid existing in the gap between the pump chamber and the both end faces as the rotor rotates, and this dynamic pressure is applied to the rotor. Acts as a bearing pressure that supports the bearings from both sides in the axial direction at a fixed position.

[0009]

【Example】

 1 and 2 show a first embodiment in which the present invention is applied to a vane pump incorporated as a water supply means to a steam generating portion in an electric iron, for example, a convex portion 23a of a cover 23 and a flexible plate. 21, a coil spring 30 is appropriately compressed so that the central portion of the flexible plate 21 is pressed toward the inside of the pump chamber 11, and the flexible plate 21 is substantially aligned with the axial center of the rotor 12. It has a structure in which small holes 31 are opened at corresponding positions.

This structure is intended to prevent a decrease in self-sufficiency due to a decrease in the bending amount of the bending plate 21 with time. That is, in the vane pump of FIG. 6 described above, the bending of the bending plate 21 toward the pump chamber 11 side depends on the pressure of the air compressed in the closed space S at the time of assembly. The air pressure in the closed space S is changed by the occurrence of time-dependent creep (permanent strain) of the casing 10 and the cover 23 made of material, the leakage of the air existing in the closed space S, or the change of the deformed state of the O-ring 24. However, the vane pump of the present embodiment does not depend on the air pressure for the deflection of the deflection plate 21, but only the biasing force of the coil spring 30. In addition, since the initial stress caused by tightening the cover 23 and the casing 10 is made as small as possible, the deflection is hardly reduced, and the gaps at both ends of the rotor 12 in the axial direction are kept minute. With self-sufficiency force and ejection force can be improved Therefore, it is possible to prevent the decreasing over time.

The output shaft 1 of the motor 18 penetrates the through hole 10 a of the casing 10, reaches the inside of the pump chamber 11, and is inserted into the shaft hole 2 of the rotor 12. The insertion portion 1a of the output shaft 1 into the shaft hole 2 and the shaft hole 2 are formed in a substantially semi-cylindrical shape in which a cross section taken along a plane orthogonal to the shaft center is a part of a circle. The shaft hole 2 is formed slightly larger than the insertion portion 1a. That is, since the output shaft 1 of the motor 18 and the shaft hole 2 of the rotor 12 are fitted with a clearance without a tightening margin, the output shaft 1 and the rotor 12 are not mutually opposed in the axial direction. It is a constraint, and is bound to each other in the circumferential direction by the fitting of the semi-cylindrical shapes. In the output shaft 1, the base portion 1b on the motor 18 side excluding the insertion portion 1a has a simple cylindrical surface, and the shaft periphery is sealed by a packing 3 attached to the inner peripheral surface of the through hole 10a of the casing 10, The airtightness between the chamber 11 and the motor 18 side is maintained. Since the rotor 12 is a synthetic resin molded product, such a shaft hole 2 having a non-circular cross section can be easily formed at the time of molding.

When the rotor 12 is rotated only in one direction, the spiral groove 4 is provided as a dynamic pressure generating means on both axial end faces of the rotor 12, as shown as a second embodiment in FIG. Is formed. The spiral groove 4 extends in the direction of taking in fluid from the outer peripheral side by rotation. When the rotor 12 is rotated in both forward and reverse directions, a plurality of Rayleigh steps 5 are provided as dynamic pressure generating means on both axial end faces of the rotor, as shown as a third embodiment in FIG. It is formed.

According to this vane pump, even if a difference in thermal expansion between the synthetic resin casing 10 and the metal output shaft 1 occurs due to a change in the ambient temperature, the output shaft 1 and the rotor 12 are not mutually opposed in the axial direction. Because of the restraint, the axial relative position of the rotor 12 in the pump chamber 11 is not forcibly changed by the output shaft 1, and the spiral groove 4 or the Rayleigh step 5 is formed on both end faces of the rotor 12. As a result, during rotation, a significant dynamic pressure is generated in the fluid existing at both axial ends of the rotor 12, and this dynamic pressure floats and supports the rotor 12 from both axial ends of the pump chamber 11 at a fixed position, so It is possible to prevent the end surface of the slider 12 and the casing 11 or the flexible plate 21 from sliding. In addition, when the pump is assembled, it is not necessary to precisely control the press-fitting length of the output shaft 1 in order to form the gaps on both sides of the rotor 12 in the axial direction with high accuracy, and the press-fitting process itself is not required.

In the present invention, the insertion portion 1a and the shaft hole 2 of the output shaft 1 are not limited to the illustrated semi-cylindrical shape, but may be prismatic or spline-shaped with projections and depressions extending in the axial direction. It suffices if it engages so as to be movable in any direction, and the dynamic pressure generating means formed on both end faces of the rotor 12 is not limited to the spiral groove 4 or the Rayleigh step 5 having the illustrated shape, In short, it is sufficient if it can generate a significant dynamic pressure in the fluid by rotation.

[0015]

[Effect of device]

 According to the present invention, the output shaft of the motor is inserted into the shaft hole of the rotor in a loosely fit state so that the output shaft and the casing have different thermal expansion coefficients. The sliding of the casing is prevented, and the self-sufficiency and discharge force can be improved. Further, since the work of controlling the assembling of the rotor in the pump chamber with high accuracy is not required, the manufacturing is easy.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of a vane pump according to the present invention, taken along a plane passing through its axis.

FIG. 2 is a cross-sectional view of the first embodiment cut perpendicularly to its axis.

FIG. 3 is a plan view of a rotor showing a second embodiment of the vane pump according to the present invention.

4A and 4B show a third embodiment of a vane pump according to the present invention, FIG. 4A is a plan view of a rotor, and FIG. 4B is a partial sectional view taken along line BB in FIG. 4A.

FIG. 5 is a cross-sectional view showing the basic structure of a vane pump, taken along a line perpendicular to the axis.

FIG. 6 is a cross-sectional view showing a conventional vane pump taken along a plane passing through an axis.

[Explanation of symbols]

 1 Output Shaft 2 Shaft Hole 4 Spiral Groove (Dynamic Pressure Generation Means) 5 Rayleigh Step (Dynamic Pressure Generation Means) 10 Casing 11 Pump Chamber 12 Rotor 14 Vanes 18 Motor

Claims (2)

[Scope of utility model registration request] 1. A rotor provided rotatably at an eccentric position in a pump chamber, and a vane radially projectingly retractable in each of a plurality of vane grooves radially formed in the rotor, A vane pump, characterized in that an output shaft of a motor is inserted into a shaft hole of the rotor in a loosely fitted state so as to be relatively movable in the axial direction and engaged with each other in a rotational direction. 2. The vane pump according to claim 1, wherein a large number of dynamic pressure generating means are formed on both end surfaces of the rotor.