JP2005344601A - Motor operated pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor operated pump capable of suppressing pump vibration occurring during operation. <P>SOLUTION: An impeller 12 is provided with six blades 14 causing fluid to generate a pressure. Further, the impeller 12 has a cylindrical part which is situated at the outer periphery of a stator 22 and is polarized, and constitutes a six-pole motor with a stator 22. And, in the impeller 12, a polarizing position to the blade 14 is regulated such that when a pressure fluctuation (impeller pulsation) of fluid generated by a position relation between a discharge port 18 and the blade 14 of the impeller 12 is maximized, cogging torque of a motor is minimized. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electric pump, and more particularly, to an electric pump that drives an impeller having a plurality of blades with a motor.

  In an electric pump that drives an impeller having a plurality of blades with a motor, pressure fluctuation (hereinafter referred to as “impeller pulsation”) due to the positional relationship between the fluid discharge port and the impeller blades or cogging of the motor. Pump vibration is generated due to torque, and pump noise is generated by propagating the pump vibration to the structure. Here, the cogging torque is a torque generated by the magnetic force action between the magnet provided on the rotor and the iron core of the stator. When the motor rotates, a sensation is generated and the pump vibration is generated in the electric pump. Cause.

  In particular, in vehicles that require quietness, in particular, hybrid vehicles that can operate even when the electric pump used as a water pump is stopped, and electric vehicles that do not have an engine (electric vehicles), Since noise from the electric pump becomes relatively significant in a situation where no operating noise is generated, reduction of pump noise is one of important issues.

Patent Document 1 discloses a centrifugal pump that can reduce the generation level of liquid pulsation and reduce the vibration response of a structure caused by the pulsation. According to this Patent Document 1, the pulsation level is reduced by giving the fluid pulsation in the tank an opposite phase by the two centrifugal pumps whose phases are controlled and superimposing them. A pulsation measuring sensor is provided in the pipe, and the rotational phase of the two centrifugal pumps is controlled by the phase controller using the measured value. Thereby, the generation level of the liquid pulsation can be reduced, or the vibration response of the structure caused by the pulsation can be reduced (see Patent Document 1).
JP-A-9-68156 JP 2004-68670 A Japanese Utility Model Publication No. 63-098494 JP 2003-336591 A JP-A-8-270595

  However, according to the technique disclosed in Patent Document 1, since it is essential to have two pumps, there is a demerit in a vehicle that requires cost reduction and size reduction. Moreover, the technique disclosed in Patent Document 1 is to reduce liquid pulsation by synthesizing pulsation generated from each pump, and does not suppress pump vibration itself.

  Accordingly, the present invention has been made to solve such a problem, and an object thereof is to provide an electric pump capable of suppressing pump vibration generated during operation.

  According to the present invention, an electric pump includes an impeller having a plurality of blades, a rotor having a plurality of field poles, and a motor unit including a stator having a plurality of iron cores each wound with a coil. The field pole is such that the first peak of the cogging torque periodically generated by the magnetic action of the plurality of field poles and the plurality of iron cores is shifted from the second peak of pulsation periodically generated by the rotation of the impeller. It is formed in the circumferential direction of the rotor.

  Preferably, the impeller has m blades (m is a natural number of 2 or more) blades, the motor unit has m field poles and m iron cores, and the plurality of field poles are adjacent to each other. It is formed in the circumferential direction of the rotor so that the first peak is generated substantially at the center of the two peaks.

  Preferably, the plurality of field poles are formed in the circumferential direction of the rotor such that the generation period of cogging torque is different from the generation period of pulsation.

  Preferably, the impeller has m (m is a natural number of 2 or more) blades, and the motor unit has n (n is a natural number of 2 or more different from m) field poles.

  Preferably, the impeller constitutes a rotor of the motor unit, and the plurality of field poles are formed by magnetizing the impeller in the circumferential direction.

  Preferably, the impeller is provided so that a part thereof covers the outer periphery of the stator, and a part of the impeller is magnetized in the circumferential direction to constitute a rotor, and the plurality of blades are arranged in the direction of the rotation axis of the impeller Is disposed on one of the end faces.

  In the electric pump according to the present invention, the first peak of the cogging torque periodically generated by the magnetic action of the plurality of field poles and the plurality of iron cores is the second peak of the pulsation periodically generated by the rotation of the impeller. Since the plurality of field poles are formed in the circumferential direction of the rotor so as to be shifted, cogging torque and pulsation due to rotation of the impeller do not occur simultaneously.

  Therefore, according to this invention, pump vibration is suppressed. Further, since vibration of the electric pump itself is suppressed, it is not necessary to provide two electric pumps in order to cancel pulsation, and suppression of pump vibration can be realized at low cost.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment 1]
1 is a front view showing a configuration of an electric pump according to Embodiment 1 of the present invention.

  With reference to FIG. 1, the electric pump 10 according to the first embodiment includes an impeller 12, a blade 14, a rotating shaft 16, a discharge port 18, and an upper case 20. The impeller 12 is fixed to the rotary shaft 16 and rotates in the clockwise direction around the rotary shaft in conjunction with the rotary shaft 16. Six blades 14 are fixed to the impeller 12 and arranged at equal intervals in the rotation direction. When the impeller 12 rotates, the blade 14 generates pressure due to centrifugal action on the fluid sucked from the vicinity of the center of the impeller 12. The discharge port 18 is an output port for discharging the fluid whose pressure has been increased by the rotation of the impeller 12 to the outside. The upper case 20 is a housing that covers the outer periphery of the impeller 20.

  In the electric pump 10, when the impeller 12 rotates clockwise, the six blades 14 provided on the impeller 12 generate water pressure. Then, the fluid whose pressure is increased between the adjacent blades 14 is sequentially output from the discharge port 18.

  Here, impeller pulsation due to the positional relationship between the discharge port 18 and the blades 14 is generated in the fluid output from the discharge port 18. In the electric pump 10, six blades 14 are provided at equal intervals in the rotation direction. When the impeller 12 makes one rotation, six pressure peaks due to the positional relationship between the discharge port 18 and the blades 14 are periodically generated. Occur.

  FIG. 2 is a cross-sectional view taken along section II-II in the electric pump 10 shown in FIG. In FIG. 2, the upper case 20 shown in FIG. 1 is not shown.

  With reference to FIG. 2, the electric pump 10 includes an impeller 12, a blade 14, a rotating shaft 16, a stator 22, a bearing 24, and a substrate 26. The impeller 12 has a hollow structure and is disposed so as to cover the stator 22 from the outer peripheral side. The impeller 12 is magnetized alternately in the N direction / S pole in the circumferential direction, as will be described later, and constitutes an outer rotor of the stator 22.

  Here, the magnetization position in the circumferential direction of the impeller 12 is determined in relation to the six blades 14. In other words, the impeller in which the peak of the cogging torque of the motor constituted by the rotor constituted by magnetizing the impeller 12 and the stator 22 is generated due to the positional relationship between the discharge port 18 and the blade 14 described above. The magnetization position in the circumferential direction of the impeller 12 is adjusted so as not to overlap with the peak of pulsation.

  The stator 22 is configured by laminating and crimping electromagnetic steel plates having excellent electromagnetic characteristics in the direction of the rotation axis, and is fixed to the substrate 26. The stator 22 generates a rotating magnetic field when a predetermined current flows through a coil (not shown), and constitutes a motor together with the magnetized portion of the impeller 12. One end of the rotating shaft 16 is fixed to the impeller 12, and the other end is supported by the bearing 24. The bearing 24 supports the rotary shaft 16 in a freely rotatable manner. The substrate 26 fixes the stator 22 and supplies current to the stator 22.

  In the electric pump 10, the stator 22 generates a rotating magnetic field when a current is passed through the coil. Then, a rotational force is generated in the impeller 12 by the magnetic action between the generated rotating magnetic field and the magnetized portion of the impeller 12, and the impeller 12 rotates around the stator 22. As a result, the six blades provided on the impeller 12 generate water pressure.

  FIG. 3 is a cross-sectional view of section III-III in electric pump 10 shown in FIG.

  Referring to FIG. 3, impeller 12 has six field poles that are alternately magnetized to the N / S poles in the circumferential direction. The stator 22 has six iron cores 28 in the circumferential direction, and a coil 30 for generating a magnetic field is wound around each iron core 28. The stator 22 generates a rotating magnetic field when a current in a predetermined order and a predetermined direction flows through each coil 30, and the impeller 12 causes the stator 12 to move to the stator by a magnetic action between the rotating magnetic field and the field pole formed on the impeller 12. Rotate around 22.

  Here, in the electric pump 10, even if no current flows through the coil 30 wound around the iron core 28, the cogging torque is generated by the magnetic action between the field pole formed on the impeller 12 and the iron core 28 of the stator 22. Occur. In the electric pump 10 composed of six field poles and six iron cores, when the impeller 12 makes one rotation, six times of cogging torque is generated periodically.

  As described above, in the electric pump 10, the impeller pulsation caused by the positional relationship between the discharge port 18 and the blade 14 and the cogging torque of the motor constituted by the impeller 12 and the stator 22 are the main pump vibrations. Causes it to occur. The impeller pulsation or cogging torque itself does not generate a large pump vibration that can cause pump noise. However, if the impeller pulsation pressure peak and the cogging torque peak overlap and overlap, a large pump vibration that can cause pump noise is generated. Occur. Therefore, in the first embodiment, the relationship between the position of the blade 14 and the magnetized position in the impeller 12 is adjusted so that the pressure peak of the impeller pulsation and the peak of the cogging torque do not overlap.

  FIG. 4 is a waveform diagram of impeller pulsation and cogging torque in electric pump 10 according to the first embodiment. The impeller pulsation shown here is a fluid pressure fluctuation generated only by the positional relationship between the discharge port 18 and the blade 14.

  Referring to FIG. 4, the vertical axis represents the impeller pulsation (kPa) and the cogging torque (N · m) of the motor, and the horizontal axis represents a rotational position where the peak of the impeller pulsation occurs at the reference position (phase 0 degree). ) Represents the rotation angle of the impeller 12. As shown in the figure, in the electric pump 10, the impeller pulsation occurs when the rotation angle is approximately 60 degrees, approximately 120 degrees, approximately 180 degrees, approximately 240 degrees, approximately 300 degrees, and approximately 360 degrees (approximately 0 degrees). The peak occurs. On the other hand, the cogging torque has a rotation angle of approximately 0 to approximately 60 degrees, approximately 60 to approximately 120 degrees, approximately 120 to approximately 180 degrees, approximately 180 to approximately 240 degrees, approximately 240 to approximately 300 degrees, and approximately. A peak occurs when the angle is from 300 degrees to approximately 360 degrees, and is a minimum when the rotation angle is such that a peak of impeller pulsation occurs.

  In other words, in the electric pump 10, the magnetized position (magnetic pole position) with respect to the blade 14 is adjusted in the impeller 12 so that the cogging torque is minimized at the peak of the impeller pulsation. Therefore, in the electric pump 10, a large pump vibration is not generated due to the pressure peak of the impeller pulsation and the peak of the cogging torque overlapping each other.

  As described above, according to the first embodiment, the magnetizing position of the impeller 12 is adjusted so that the cogging torque of the motor formed by the field pole formed on the impeller 12 and the stator 22 does not overlap with the impeller pulsation. Therefore, cogging torque and impeller pulsation do not occur simultaneously, and pump vibration is suppressed.

[Embodiment 2]
FIG. 5 is a front view showing the configuration of the electric pump according to the second embodiment of the present invention.

  Referring to FIG. 5, electric pump 10 </ b> A according to the second embodiment includes impeller 12 </ b> A instead of impeller 12 in the configuration of electric pump 10 according to the first embodiment. The impeller 12A has nine blades 14 arranged at equal intervals in the rotation direction. The other configuration of the electric pump 10A is the same as that of the electric pump 10 according to the first embodiment.

  Therefore, in the electric pump 10A, when the impeller 12A makes one rotation, nine pressure peaks due to the positional relationship between the discharge port 18 and the blades 14 are periodically generated. On the other hand, the impeller 12A has six field poles alternately magnetized in the N direction / S pole in the circumferential direction, and the stator 22 (not shown) has six iron cores 28 in the circumferential direction. As in the electric pump 10 according to the first embodiment, when the impeller 12A rotates once, six cogging torques are periodically generated.

  That is, this electric pump 10A is designed so that the generation periods of the impeller pulsation and the cogging torque are different.

  FIG. 6 is a waveform diagram of impeller pulsation and cogging torque in electric pump 10A according to the second embodiment. Similar to FIG. 4, the impeller pulsation shown here is also a fluid pressure fluctuation generated only by the positional relationship between the discharge port 18 and the blade 14.

  Referring to FIG. 6, the vertical axis represents impeller pulsation (kPa) and motor cogging torque (N · m), and the horizontal axis represents a rotational position at which the impeller pulsation peak occurs at a reference position (phase 0 degree). ) Represents the rotation angle of the impeller 12A. As for the impeller pulsation, nine peaks occur at equal intervals between the rotation angles of 0 degrees and 360 degrees. On the other hand, with respect to the cogging torque, six peaks occur at equal intervals when the rotation angle is between 0 degrees and 360 degrees.

  Therefore, as shown in the figure, in this electric pump 10A, the peak of impeller pulsation and the peak of cogging torque do not overlap. In this electric pump 10A, unlike the electric pump 10 in the first embodiment, the cogging torque does not become the minimum at the peak of the impeller pulsation, but at least the peak of the impeller pulsation and the peak of the cogging torque do not overlap. Pump vibration can be suppressed.

  As described above, according to the second embodiment, the magnetizing position of the impeller 12 is adjusted so that the number of field poles formed on the impeller 12A is different from the number of blades in the impeller 12A, and the cogging torque of the motor is reduced. Since the generation cycle is different from the generation cycle of impeller pulsation, the peak of cogging torque and the peak of impeller pulsation do not occur simultaneously, and pump vibration is suppressed.

  In the first embodiment described above, the number of blades 14 and the number of magnetic poles are six, but these numbers are not limited thereto. In the second embodiment, the relationship between the number of blades 14 and the number of magnetic poles is not limited to the above number. If the numbers are different, the pump vibration suppressing effect can be expected.

  Further, in each of the above embodiments, the number of magnetic poles formed on the impellers 12 and 12A and the number of iron cores of the stator 22 are both the same number of 6, but these numbers may be different. When the number of magnetic poles and the number of iron cores of the stator 22 are different, a cogging torque of the least common multiple of these numbers is generated per motor rotation, and the magnitude of the cogging torque is the number of times the cogging torque is generated per motor rotation. Therefore, pump vibration can be suppressed.

  Further, in each of the above embodiments, the impellers 12 and 12A are magnetized to form the rotor. However, the configuration of the electric pump is not limited to such a configuration, and the impeller and the motor are combined. It may be configured separately and the impeller and the rotor may be connected by a rotating shaft. Further, in each of the above embodiments, the abduction type motor configuration in which the rotor (impeller 12, 12A) is provided on the outer periphery of the stator 22 is described. However, the scope of application of the present invention is limited to the abduction type motor. In addition, an internal rotation type motor in which the rotor is provided on the inner peripheral side of the stator is also included.

  Moreover, the electric pumps 10 and 10A in the above-described embodiments are suitable for, for example, a hybrid vehicle and an electric vehicle that have attracted much attention in recent years. That is, in such a vehicle, silence, cost reduction, and downsizing are required. However, according to the electric pumps 10 and 10A, since pump vibration is suppressed, water is used when the engine is stopped in a hybrid vehicle. Silence can be ensured even in situations where noise from the pump can be significant. Further, according to the electric pumps 10 and 10A, since a simple method of adjusting the magnetized position of the impeller is used, pump vibration can be suppressed at a low cost. Further, according to the electric pumps 10 and 10A, since vibration of the electric pump itself is suppressed, it is not necessary to provide two electric pumps in order to cancel each other's vibration (pulsation), thereby reducing the cost of the vehicle. And contribute to miniaturization.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

It is a front view which shows the structure of the electric pump by Embodiment 1 of this invention. It is sectional drawing of the cross section II-II in the electric pump shown in FIG. It is sectional drawing of the cross section III-III in the electric pump shown in FIG. It is a waveform diagram of impeller pulsation and cogging torque in the electric pump according to the first embodiment. It is a front view which shows the structure of the electric pump by Embodiment 2 of this invention. It is a waveform diagram of impeller pulsation and cogging torque in the electric pump according to the second embodiment.

Explanation of symbols

  10, 10A electric pump, 12, 12A impeller, 14 blades, 16 rotary shaft, 18 discharge port, 20 upper case, 22 stator, 24 bearing, 26 substrate, 28 iron core, 30 coil.

Claims (6)

An impeller having a plurality of blades;
A motor unit including a rotor having a plurality of field poles and a stator having a plurality of iron cores each wound with a coil;
The plurality of field poles have a second pulsation in which a first peak of cogging torque that is periodically generated by the magnetic action of the plurality of field poles and the plurality of iron cores is periodically generated by rotation of the impeller. An electric pump formed in the circumferential direction of the rotor so as to deviate from the peak. The impeller has m (m is a natural number of 2 or more) blades,
The motor unit has m field poles and m iron cores,
2. The electric pump according to claim 1, wherein the plurality of field poles are formed in a circumferential direction of the rotor such that the first peak is generated at substantially the center of the adjacent second peak.   2. The electric pump according to claim 1, wherein the plurality of field poles are formed in a circumferential direction of the rotor such that a generation cycle of the cogging torque is different from a generation cycle of the pulsation. The impeller has m (m is a natural number of 2 or more) blades,
The electric pump according to claim 3, wherein the motor unit has n (n is a natural number of 2 or more different from m) field poles. The impeller constitutes a rotor of the motor unit,
The electric pump according to any one of claims 1 to 4, wherein the plurality of field magnetic poles are formed by magnetizing the impeller in a circumferential direction. The impeller is provided so that a part thereof covers the outer periphery of the stator,
A part of the impeller constitutes the rotor by being magnetized in the circumferential direction,
The electric pump according to claim 5, wherein the plurality of blades are disposed on one of end faces in a rotation axis direction of the impeller.

Images