JP2005207245A - Motor-driven pump unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor-driven pump unit capable of effectively functioning as a pump by increasing the efficiency of an internal gear pump and rotating at a practicable speed and torque. <P>SOLUTION: In this motor-driven pump unit, permanent magnets 32 are fixed to the outer periphery of the outer gear 31 of an internal gear pump having the outer gear (body) 31 and an inner gear 4 meshing with each other, a stator 2 having a plurality of electromagnetic coils 22 is disposed on the outside of the permanent magnets 32, and the outer gear 32 is rotated as the rotor of the motor by the energization of the stator 2. The axial dimension of the permanent magnets 32 is formed larger than the axial dimension of the outer gear 31, and the axial both ends of the permanent magnets 32 are projected from the axial both ends of the outer gear 31. Thus, the axial dimension of the internal gear pump is optimized and a motor capacity enough for rotating the internal gear pump at practicable speed/torque can be provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electric pump unit in which an internal gear pump and a motor are substantially integrated, and more particularly to a small and highly efficient electric pump unit suitable for being mounted on an automobile.

  An inner gear pump having a structure in which an inner gear having a tooth shape formed on the inner periphery is meshed with an inner gear having the same tooth shape formed on the outer periphery and having an eccentric shaft with respect to the outer gear, and these are accommodated in a housing. Trochoid pumps that use trochoidal tooth profile are suitable for mounting in automobiles because they have relatively low discharge pressure but lower noise and less pulsation than other gear pumps, especially drive train clutches and couplings. It is suitable for a hydraulic pump for a hydraulic actuator such as a transmission.

  However, a normal internal gear pump has a structure in which a motor, which is a power source, is connected to the pump body in the axial direction by coupling or the like, which requires a large space and is not limited in size reduction. The number of parts is large, and there is a limit to cost reduction.

  Therefore, in order to achieve a reduction in size and cost of this type of electric pump, there has conventionally been an electric pump unit having a structure in which a permanent magnet is fixed to the outer periphery of the outer gear and the outer gear is directly rotated as a motor rotor. It has been proposed (see, for example, Patent Document 1).

  A configuration example of this type of electric pump unit is shown in an axial parallel cross-sectional view in FIG. 3 and in an axial orthogonal cross-sectional view in FIG. In this example, a motor stator 32, an outer gear 33, an inner gear 34, and a nonmagnetic case 35 are accommodated in a cup-shaped housing 31, and an opening portion of the housing 31 is closed by a nonmagnetic plate 36.

  The motor stator 32 includes a stator core 321 in which six teeth 321b protrude from the annular base portion 321a and electromagnetic coils 322 wound around the teeth 321b.

  The outer gear 33 has a structure in which a plurality of permanent magnets 332 are fixed to the outer periphery of an outer gear main body 331 formed with a trochoid tooth shape meshing with the inner gear 34 on the inner periphery, and the outside of each permanent magnet 332 is covered with a nonmagnetic ring 333. Have. The inner gear 34 is rotatably supported by the housing 31 and the nonmagnetic plate 36 via a shaft 341 at a position eccentric with respect to the outer gear 33. The nonmagnetic plate 36 is formed with an import 361 and an outport 362 for the working fluid.

In the above configuration, when current flows through each electromagnetic coil 322 of the motor stator 32 at a predetermined timing, torque is generated by interacting with the magnetic flux of each permanent magnet 332, and the outer gear 33 rotates as a rotor of the motor. The inner gear 34 that is inscribed and meshed with the outer gear 33 rotates to generate a pump action, and the working fluid is sucked from the import 361 and discharged from the outport 362.
JP 2003-129966 A

  By the way, in general, the ratio of the outer diameter dimension and the axial dimension of the outer gear of the inscribed gear pump is as flat as about 10: 1 to 5: 1. If the axial dimension is made larger than this range, the efficiency can be improved. It will decline. On the other hand, the rotor of a brassless motor using a permanent magnet is usually 2: 1 or more, and its output decreases when it is flattened by reducing the axial dimension.

  In the above-described conventional electric pump unit, as shown in FIGS. 3 and 4, the axial dimension of the outer gear and the axial dimension of the permanent magnet are substantially equal. Therefore, the outer gear of the internal gear pump and the rotor of the motor are The ratio of the outer diameter dimension to the axial dimension is substantially equal.

  In such a structure, in order to improve the efficiency of the internal gear pump, if the ratio of the outer diameter dimension to the axial dimension is flattened within the normal range described above, the axial dimension of the motor rotor is accordingly reduced. As a result, the capacity is insufficient for the pump to function effectively as a pump by rotating at a practical rotational speed.

  On the other hand, in order to obtain a practical pump, if the axial dimension of the rotor of the motor is increased, the axial dimension of the inscribed gear pump increases accordingly, and the ratio to the outer diameter dimension is a ratio for increasing the above-described high efficiency. Will result in a decrease in pump efficiency.

  The present invention has been made in view of such circumstances, and an electric pump unit that can increase the efficiency of the internal gear pump and can effectively function as a pump by rotating it with a practical rotational speed and torque. The challenge is getting.

  In order to solve the above problems, the electric pump unit of the present invention has a permanent magnet fixed to the outer periphery of an outer gear of an internal gear pump having an outer gear and an inner gear that mesh with each other, and outside the permanent magnet. In an electric pump unit in which a stator having a plurality of electromagnetic coils is arranged, and the outer gear rotates as a rotor by energizing the stator, the axial dimension of the permanent magnet is the axial direction of the outer gear. It is larger than a dimension, and it is characterized by the axial direction both sides of the said permanent magnet projecting from the axial direction both ends of the outer gear (Claim 1).

  Here, in this invention, the structure (Claim 2) to which the ring which consists of a magnetic body was respectively fixed inside the protrusion part from the axial direction both ends of the outer gear of the said permanent magnet can be employ | adopted suitably.

  The present invention increases the axial dimension of the permanent magnet fixed to the outer periphery of the outer gear and projects it from both ends of the outer gear in the axial direction compared to the outer dimension of the outer gear. The optimization of the ratio of the directional dimensions and the optimization of the axial dimension of the motor rotor are simultaneously achieved.

  That is, in the electric pump unit in which the outer gear of the internal gear pump and the rotor of the brushless motor are common, the substantial axial dimension as the rotor of the motor, that is, the axial dimension that contributes to the determination of the capacity of the motor is It is not the dimension of the outer gear body in the axial direction, but the dimension of the permanent magnet fixed to the outer periphery thereof. Therefore, in the present invention, the axial dimension of the permanent magnet fixed to the outer periphery is made larger than the axial dimension of the outer gear, and the permanent magnet is protruded from both axial ends of the outer gear. As a result, the axial dimension of the outer gear, and thus the axial dimension of the inscribed gear pump, is a dimension that provides high efficiency in relation to the outer diameter dimension, and at the same time, the inscribed gear pump is rotated at a practical rotational speed. It is possible to obtain a motor capacity that makes the pump function effective. Therefore, the unit can be miniaturized and is particularly suitable for being mounted on an automobile and operating a drive system hydraulic actuator.

  In this type of electric pump unit, as illustrated in FIG. 3, the axial end of the outer gear including the permanent magnet is covered with the nonmagnetic case and the nonmagnetic plate, so that the axial dimension of the permanent magnet is set. If it is larger than that of the outer gear and protrudes from both ends in the axial direction, the inside of the protruding part of the permanent magnet is filled with nonmagnetic material, and the magnetic resistance in the magnetic path inside this protruding part is high. Thus, the output and efficiency of the motor may be reduced. Therefore, as in the invention according to claim 2, by fixing the ring made of a magnetic material to the inner peripheral side of the portion protruding from both ends of the outer gear of the permanent magnet, the inside of the portion protruding from both ends of the outer gear of the permanent magnet The magnetic path is replaced with a material having a low magnetic resistance, so that the motor efficiency can be increased and the amount of magnets used can be reduced. Therefore, the degree of freedom and fuel efficiency of mounting in a car due to miniaturization are further improved.

  According to the present invention, the axial dimension of the inscribed gear pump is set to an optimum dimension that can obtain high pump efficiency, and the axial dimension of the rotor of the motor is set to a practical rotational speed and motor as a pump. It is possible to achieve both dimensions capable of obtaining a capacity. As a result, it is possible to obtain a small and lightweight electric pump unit which has high pump efficiency and which functions practically and effectively.

  Further, according to the invention of claim 2, since a magnetic path with a small magnetic resistance is formed inside the permanent magnet, in addition to the above effects, it is possible to improve the output and efficiency as a motor, and the same As a result of reducing the amount of permanent magnets used to obtain output or capacity, cost reduction can also be achieved.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an axially parallel sectional view of an embodiment of the present invention, and FIG. 2 is an AA sectional view thereof.
A motor stator 2, an outer gear 3, an inner gear 4, and a nonmagnetic case 5 are accommodated inside a cup-shaped housing 1, and the opening of the housing 1 is closed by a nonmagnetic plate 6.

  The motor stator 2 includes a stator core 21 in which six teeth 21b project inward from an annular base portion 21a, and electromagnetic coils 22 wound around the teeth 21b. A direct current is supplied to each of the electromagnetic coils 22 in order from the driver.

  The outer gear 3 includes an outer gear main body 31 having a trochoidal tooth shape formed on the inner periphery, a plurality of permanent magnets 32 fixed to the outer periphery of the outer gear main body 31, and a nonmagnetic ring 33 that covers the outer sides of the permanent magnets 32. It is configured. Each permanent magnet 32 has a shape in which a cylindrical body is divided into four in the circumferential direction, and magnetic poles are formed on the inner peripheral side and the outer peripheral side, respectively, and the directions of the magnetic poles adjacent to each other are opposite to each other. It is arranged to be.

  The outer gear 3 is accommodated in a cup-shaped nonmagnetic case 6, and the outer peripheral surface of the nonmagnetic ring 33, which is the outermost peripheral surface of the outer gear 3, is freely slidable with respect to the inner peripheral surface of the nonmagnetic case 5. It is supported by.

  The inner gear 4 has a trochoidal tooth profile that meshes with the outer gear 3 on the outer periphery, and a shaft 42 is fixed to the center thereof. One end of the shaft 41 is rotatably supported by the base portion of the nonmagnetic case 5 and the other end of the shaft 41 is rotatably supported by the nonmagnetic plate 6. The shaft 41 is arranged at a position eccentric with respect to the center of the outer gear 3. . The nonmagnetic plate 6 is formed with a working fluid import 61 and an outport 62.

  The nonmagnetic case 5, the nonmagnetic plate 6, and the nonmagnetic ring 33 can be made of nonmagnetic stainless steel or resin.

  The feature of this embodiment is that the axial dimension of each permanent magnet 32 is larger than the axial dimension of the outer gear main body 31, and projects from both axial ends of the outer gear 31. Magnetic rings 7a and 7b are fixed to the inner peripheral side of the protruding portion from the outer gear main body 31 to both sides in the axial direction. The axial dimension of the inner gear 4 is equivalent to the axial dimension of the outer gear main body 31.

  The nonmagnetic case 5 described above enters the inside of the magnetic ring 7a from one end face of each permanent magnet 32 and one end face of the one magnetic ring 7a so as to extend along the one end face of the outer gear 31 in the axial direction. Protruding. The nonmagnetic plate 6 also has a shaft extending from the portion along the other end surface of each permanent magnet 32 and one end surface of the other magnetic ring 7b into the inside of the magnetic ring 7b and along the other end surface of the outer gear 31. Protrudes in the direction.

  In the above embodiment, like the conventional electric pump unit, a direct current is supplied to each electromagnetic coil 22 of the motor stator 2 in order to interact with the magnetic flux as the field of each permanent magnet 32 to generate torque. The outer gear 3 to which the permanent magnet 32 is fixed rotates as a rotor of the brushless motor, and the meshing with the inner gear 4 causes a pump action.

  According to the above-described embodiment of the present invention, the axial dimension as the rotor of the brushless motor is larger than the axial dimension as the trochoid gear pump. Increases by the total amount. Accordingly, by appropriately setting the protrusion amount, the ratio of the axial dimension to the outer diameter dimension of the trochoid gear pump is optimized to increase the pump efficiency, and the rotation speed and the speed sufficient to put the trochoid pump into practical use. A motor capacity that can be rotated under torque can be provided.

  Then, due to the presence of the magnetic rings 7a and 7b provided inside the permanent magnets 32 protruding from both axial ends of the outer rotor main body 31, a magnetic path with less magnetic resistance is formed on the inner peripheral side of each permanent magnet 32. As a result, the output / efficiency of the motor is also increased, and the amount of permanent magnets required to obtain the same output can be reduced, thereby contributing to cost reduction.

  In the above embodiment, the trochoid pump is employed as the internal gear pump. However, it is needless to say that the present invention can be equally applied to internal gear pumps having other tooth shapes. In the above embodiment, an example in which a plurality of segment-shaped permanent magnets are fixed to the outer periphery of the outer gear main body has been described. Instead of this, a cylindrical integral permanent magnet is used, and the circumferential direction is constant. Needless to say, the magnetic poles may be magnetized so that the magnetic poles are reversed inward and outward at a pitch.

It is an axial parallel sectional view of an embodiment of the invention. It is an axis orthogonal sectional view of an embodiment of the invention. It is an axial parallel sectional view showing a configuration example of a conventional electric pump unit. It is an axis orthogonal sectional view showing the example of composition of the conventional electric pump unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 2 Motor stator 21 Stator core 22 Electromagnetic coil 3 Outer gear 31 Outer gear main body 32 Permanent magnet 33 Nonmagnetic ring 4 Inner gear 41 Shaft 5 Nonmagnetic case 6 Nonmagnetic plate 7a, 7b Magnetic ring

Claims (2)

A permanent magnet is fixed to the outer periphery of an outer gear of an internal gear pump having an outer gear and an inner gear that mesh with each other, and a stator having a plurality of electromagnetic coils is disposed outside the permanent magnet. In the electric pump unit configured such that the outer gear rotates as a rotor by energizing the motor,
The electric pump unit characterized in that an axial dimension of the permanent magnet is larger than an axial dimension of the outer gear, and both axial sides of the permanent magnet protrude from both axial ends of the outer gear.   2. The electric pump unit according to claim 1, wherein a ring made of a magnetic material is fixed to each inner peripheral side of a protruding portion from both axial ends of the outer magnet of the permanent magnet.

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