JP2010014020A - Motor-operated pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor-operated pump in which noise of a gear pump such as an internal gear pump is reduced, and its grow in size is avoided. <P>SOLUTION: In the motor-operated pump having the internal gear pump and a motor part, a one-way clutch 36 is arranged between a shaft 31 in the radial direction of a rotating member 3a of the motor part and a field magnet 32. In the one-way clutch 36, when the rotational speed of the field magnet 32 is low with respect to the rotational speed of the shaft 31, a rolling element 361 of the one-way clutch 36 does not come into sliding contact with the outer peripheral surface 314c in a large diameter part 314 of the shaft 31, consequently rotation of the field magnet 32 is not transmitted to the shaft 31. Thus, transmission of such torque variation to the shaft 31, that is caused by cogging torque between the field magnet 32 and an armature, can be suppressed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electric pump that sucks and discharges oil by rotating a gear pump.

  In recent years, with the demand for energy saving of vehicles, so-called idling stop, in which the engine of the vehicle stops when idling while the vehicle is stopped, has been performed. For this reason, in a vehicle that stops idling, in addition to a mechanism for supplying oil to the vehicle transmission using the power of the conventional engine, an oil is supplied to the vehicle transmission using an electric pump operated by a battery. A mechanism is employed (see, for example, Patent Document 1). With the above mechanism, oil can be supplied to the transmission when the engine is stopped. And since an electric pump operates at the time of an engine stop, a low noise is calculated | required.

  In addition, with the recent electrification of vehicles, the number of electronic components mounted on the vehicle is increasing. Accordingly, since many electronic components are arranged in a limited space of the vehicle, the arrangement space of each electronic component is reduced, so that each electronic component is required to be downsized. Therefore, miniaturization is also required for the electric pump which is one of the electronic components.

The structure of a conventional electric pump will be described with reference to FIG. FIG. 6 is a cross-sectional view showing a conventional electric pump including a central axis and cut along a plane along the axial direction.
As shown in FIG. 6, the electric pump 100 includes an internal gear pump 103 and a motor 104 that drives the internal gear pump 103. The internal gear pump 103 is configured by accommodating the internal rotation member 101 having the external teeth 101a and the external rotation member 102 having the internal teeth 102a in a space surrounded by the pump case 108 and the pump plate 109. The The motor 104 includes a shaft 105, a field magnet 106 fixed to the shaft 105, and an armature 107 that faces the field magnet 106 in the radial direction.

An inversion member 101 is fixed to the shaft 105. And while the shaft 105 rotates, the internal rotation member 101 rotates. Further, since the outer teeth 101a of the inner rotation member 101 and the inner teeth 102a of the outer rotation member 102 mesh with each other, the inner rotation member 101 rotates and the outer rotation member 102 rotates. At this time, the abduction member 102 slides with respect to the pump case 108. The suction port provided in the pump plate 109 is changed by changing the volume of the gap formed between the inner rotation member 101 and the outer rotation member 102 as the inner rotation member 101 and the outer rotation member 102 rotate. Oil is sucked from (not shown), and oil is discharged from a discharge port provided in the pump plate 109.
JP 2008-69838 A

  In response to the demand for noise reduction of the electric pump, in the conventional electric pump 100, the shaft 105 rotates with uneven rotation due to torque fluctuation caused by the cogging torque between the field magnet 106 and the armature 107. The meshing sound between the outer teeth 101a and the inner teeth 102a was increased. In other words, since the shaft 105 rotates with uneven rotation, the external teeth 101a of the internal rotation member 101 fixed to the shaft 105 also mesh with the internal teeth 102a of the external rotation member 102 with uneven rotation. Therefore, the relative rotational speed of the external teeth 101a with respect to the rotational speed of the internal teeth 102a cannot be made zero, and the contact between the internal teeth 102a and the external teeth 101a during the engagement between the internal teeth 102a and the external teeth 101a. The state cannot be maintained. For this reason, there are cases where the internal teeth 102a and the external teeth 101a are repeatedly contacted and non-contacted while the internal teeth 102a and the external teeth 101a are engaged with each other. Therefore, the contact noise between the internal teeth 102a and the external teeth 101a increases, and the noise of the internal gear pump 103 increases. As a result, it has been difficult to achieve noise reduction of the electric pump 100.

  Further, as the noise reduction of the internal gear pump 103, the number of teeth of the internal teeth 102a of the external rotation member 102 and the number of external teeth 101a of the internal rotation member 101 are increased, whereby the internal teeth 102a and the external teeth 101a are engaged. It may be possible to reduce the volume of the sound itself. However, by increasing the number of teeth of the inner teeth 102a and the outer teeth 101a, the outer diameters of the outer rotation member 102 and the inner rotation member 101 are increased, and it is difficult to reduce the size of the electric pump 100. End up. In addition, as the outer diameter of the outer member 102 increases, the sliding resistance of the outer member 102 with respect to the pump case 108 increases. As a result, the drive efficiency of the electric pump 100 may be reduced.

  Accordingly, the present invention has been made in view of the above circumstances, and the object of the present invention is to achieve a reduction in noise of a gear pump such as an inscribed gear pump and to prevent an increase in the size of the gear pump, It is an object of the present invention to provide an electric pump that prevents a decrease in driving efficiency.

  The invention according to claim 1 of the present invention is an electric pump having a gear pump and a motor unit for driving the gear pump, the motor unit being fixed to the gear pump, and a field that rotates together with the shaft as a drive shaft. A rotating member having a magnet for magnets, and a fixing member having an armature disposed to face the field magnet, and in the radial direction of the electric pump, between the shaft and the field magnet, A one-way clutch is provided.

  According to the above configuration, since the one-way clutch is disposed between the shaft and the field magnet in the radial direction of the electric pump, the rotation speed of the field magnet is higher than the rotation speed of the shaft. When is low, the rotation of the field magnet is not transmitted to the shaft. Therefore, it is possible to suppress transmission of cogging torque generated between the field magnet and the armature to the shaft. As a result, the rotation of the gear pump fixed to the shaft becomes uniform, and the noise of the gear pump can be reduced. Therefore, the noise reduction of the gear pump can be achieved without increasing the number of teeth of the gear pump. That is, it is possible to prevent an increase in the size of the gear pump due to an increase in the number of teeth of the gear pump and a decrease in driving efficiency of the electric pump due to an increase in the size of the gear pump. As a result, it is possible to provide an electric pump that achieves a reduction in noise of the electric pump, prevents an increase in the size of the electric pump, and prevents a reduction in driving efficiency of the electric pump.

  The invention according to claim 2 of the present invention is the electric pump according to claim 1, wherein the one-way clutch includes a rolling element and an outer ring that surrounds the rolling element and to which the field magnet is fixed. The rolling element is in sliding contact with the outer peripheral surface of the shaft.

  According to the said structure, when the rolling element of a one-way clutch contacts the outer peripheral surface of a shaft, the outer peripheral surface of a shaft plays the role of the inner ring | wheel of a one-way clutch. Therefore, the inner ring | wheel of a one-way clutch can be made unnecessary and the enlargement of the rotating member in radial direction can be suppressed. As a result, the enlargement of the electric pump in the radial direction can be suppressed.

A third aspect of the present invention is the electric pump according to the second aspect, wherein the rolling element is a cylindrical roller.
According to the said structure, the enlargement of the one-way clutch in radial direction can be prevented by using a cylindrical roller for a rolling element compared with the case where a spherical ball is used for a rolling element. Therefore, an increase in the size of the rotating member in the radial direction can be suppressed, and an increase in the size of the electric pump in the radial direction can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, while achieving low noise of gear pumps, such as an internal gear pump, the enlargement of a gear pump can be prevented and the electric pump which prevented the fall of the drive efficiency of an electric pump can be provided.

  An embodiment of an electric pump according to the present invention will be described with reference to FIG. FIG. 1 is a sectional view showing an electric pump according to the present invention. In the following, along the axial direction, the inscribed gear pump side is defined as the axially upward direction, and the armature side is defined as the axially downward direction, but this does not define the direction in which the electric pump is actually attached.

  As shown in FIG. 1, the electric pump 1 includes an internal gear pump 2 and a motor unit 3. The electric pump 1 of the present embodiment is mounted on a vehicle (not shown) and plays a role of supplying oil to a transmission (not shown) of the vehicle by being driven when the vehicle is idling stopped.

  The inscribed gear pump 2 that is a gear pump includes an inversion member 21 that is fixed to a shaft 31 (to be described later) of the motor unit 3, an outer rotation member 22 that rotates by the rotation of the inner rotation member 21, the inner rotation member 21, and the outer rotation member And a housing member 23 for housing 22. The housing member 23 includes a pump housing 24 provided with a recess 241 that houses the inner rotation member 21 and the outer rotation member 22, and a pump plate 25 that seals the recess 241 of the pump housing 24.

  The motor unit 3 includes a shaft 31 extending along a central axis and a rotating member 3 a having a field magnet 32 that rotates together with the shaft 31 and a radial direction of the electric pump 1 (hereinafter simply referred to as “radial direction”). A fixing member 3b having an armature 33 facing the magnet 32 and a motor case 35 that houses the armature 33, an upper bearing portion 3c and a lower bearing portion 3d that are bearing portions that rotatably support the shaft 31; Is provided.

  The armature 33 is disposed so as to surround the field magnet 32. The armature 33 includes an armature core 331 formed by laminating a plurality of thin electromagnetic steel plates in the axial direction of the electric pump 1 (hereinafter simply referred to as “axial direction”), and the armature core 331. And a coil 332 formed by winding a plurality of conductive wires.

  The upper bearing portion 3c and the lower bearing portion 3d are disposed on both sides of the field magnet 32 in the axial direction. The upper bearing portion 3c and the lower bearing portion 3d of the present embodiment are ball bearings, respectively. The lower bearing portion 3d fixed below the field magnet 32 of the shaft 31 in the axial direction is an upper bearing portion 3c fixed above the field magnet 32 of the shaft 31 in the axial direction. Use larger ball bearings. With this configuration, it is possible to improve the durability against the force generated by the internal gear pump 2 applied to the shaft 31 in the radial direction.

  By energizing the coil 332 of the armature 33 from an external power source (not shown), a magnetic field is formed in the coil 332. Then, due to the interaction between the magnetic field of the coil 332 and the field magnet 32, rotational torque about the central axis is generated, and the shaft 31 rotates about the central axis.

  Next, the structure of the internal gear pump will be described with reference to FIG. FIG. 2 is a plan view showing the internal gear pump of the present embodiment as seen from the axial direction (that is, seen from the AA direction in FIG. 1).

  As shown in FIG. 2, the internal rotation member 21 fixed to the shaft 31 is provided with external teeth 211. The outer rotation member 22 is provided with inner teeth 221 that mesh with the outer teeth 211 of the inner rotation member 21. The rotational torque of the inner rotation member 21 is transmitted to the outer rotation member 22 when the outer teeth 211 and the inner teeth 221 of the outer rotation member 22 mesh with each other. Therefore, the inner rotation member 21 rotates and the outer rotation member 22 rotates.

  Further, the number of teeth of the external teeth 211 and the number of teeth of the internal teeth 221 are different from each other (the number of teeth of the external teeth 211 of this embodiment is 8, and the number of teeth of the internal teeth 221 is 9). The rotation center C1 of the outer rotation member 22 is eccentric with respect to the rotation center C2 of the inner rotation member 21 (that is, the central axis that is the rotation center of the shaft 31). For this reason, the volume of the gap formed between the inversion member 21 and the abduction member 22 changes as the inversion member 21 and the abduction member 22 rotate.

  A suction port (not shown) and a discharge port (not shown) provided in the pump plate 25 (see FIG. 1) are respectively located at a position where a gap between the inner member 21 and the outer member 22 becomes large, and the inner member. 21 and the outer rotation member 22 are provided at a position where the gap becomes small. Accordingly, when the inner rotation member 21 and the outer rotation member 22 in the pump housing 24 rotate, oil is sent from the suction port of the pump plate 25 to the discharge port, and the oil is supplied to the transmission.

  Next, the structure of the rotating member will be described with reference to FIGS. FIG. 3 is an enlarged view of the rotating member and the bearing portion in FIG. 1 showing the rotating member of the present embodiment. FIG. 4 is a cross-sectional view showing the one-way clutch of this embodiment. FIG. 5 is a partially enlarged view of FIG. 4 showing the position of the rolling element of the one-way clutch according to the state of the rotational speed of the shaft and the field magnet. In comparison, a case where the rotation speed of the field magnet is equal or larger is shown, and (b) is a diagram showing a case where the rotation speed of the field magnet is lower than the rotation speed of the shaft. .

  As shown in FIG. 3, the rotating member 3 a includes a shaft 31, a field magnet 32 that rotates together with the shaft 31, and one direction disposed between the shaft 31 and the field magnet 32 in the radial direction. A clutch 36.

  The shaft 31 includes a first fixing portion 311 to which the inner member 21 is fixed, a second fixing portion 312 to which the lower bearing portion 3d is fixed, and a third fixing portion 313 to which the upper bearing portion 3c is fixed. Prepare. A large outer diameter D3 between the second fixing portion 312 and the third fixing portion 313 in the axial direction is larger than the outer diameter D1 of the second fixing portion 312 and the outer diameter D2 of the third fixing portion 313. A diameter portion 314 is provided. In addition, the inner ring 3e of the upper bearing portion 3c contacts the upper surface 314a of the large diameter portion 314, and the inner ring 3f of the lower bearing portion 3d contacts the lower surface 314b of the large diameter portion 314. With this configuration, the large-diameter portion 314 constitutes a part of the preload structure of the upper bearing portion 3c and the lower bearing portion 3d. Therefore, it is not necessary to provide a separate member on the shaft 31 for preloading the upper bearing portion 3c and the lower bearing portion 3d, and the number of parts can be reduced. As a result, the cost of the electric pump 1 can be reduced.

  The field magnet 32 is a substantially cylindrical permanent magnet that surrounds the large diameter portion 314 of the shaft 31. A plurality of magnetic poles are magnetized in the circumferential direction of the field magnet 32. The field magnet 32 of the present embodiment is a neodymium magnet.

  The one-way clutch 36 only allows transmission of the field magnet 32 in the forward rotation (in the direction of arrow X in FIG. 4). The one-way clutch 36 includes a plurality of rolling elements 361, a holder 362 that holds the rolling elements 361, and a substantially cylindrical outer ring 363 that surrounds the rolling elements 361 and the holder 362. The outer ring 363 is fixed to the field magnet 32 with, for example, an adhesive.

  The rolling element 361 is in sliding contact with the outer peripheral surface 314 c of the large diameter portion 314 of the shaft 31. That is, the large diameter portion 314 of the shaft 31 serves as an inner ring of the one-way clutch 36. Since the large-diameter portion 314 of the shaft 31 serves as an inner ring of the one-way clutch 36, the inner ring of the one-way clutch 36 can be eliminated. Therefore, as compared with the structure in which the one-way clutch having the inner ring is fixed to the shaft 31, it is possible to reduce the size of the rotating member 3a in the radial direction. As a result, the electric pump 1 in which the motor unit 3 is downsized in the radial direction can be provided.

  Here, the rolling element 361 of this embodiment uses a cylindrical roller. As shown in FIG. 3, the cylindrical roller has a cylindrical shape (columnar shape) in which the axial length H is longer than the radial length (circle diameter) R <b> 2. Therefore, the one-way clutch 36 can be downsized in the radial direction as compared with the case where the rolling element 361 uses a spherical ball. As a result, the electric pump 1 in which the motor unit 3 is downsized in the radial direction can be provided.

  As shown in FIG. 4, a planar portion 363 a is provided on the inner peripheral surface (that is, the inner surface of the outer ring 363 in the radial direction) of the outer ring 363 of the one-way clutch 36 at the position where the rolling element 361 is disposed. . An elastic member 364 that biases the rolling element 361 is disposed between the cage 362 and the rolling element 361. The elastic member 364 of this embodiment is a coil spring. The rotating member 3a rotates in the X direction in the circumferential direction of the electric pump 1 (hereinafter simply referred to as “circumferential direction”).

  As shown in FIG. 5A, when the rotational speed of the field magnet 32 is equal to or larger than the rotational speed of the shaft 31, the rolling element 361 has a large diameter portion of the shaft 31 in the radial direction. 314 is locked between the outer peripheral surface 314c of the outer ring 314 and the flat portion 363a of the outer ring 363 (that is, the rolling element 361 is sandwiched between the outer peripheral surface 314c and the flat portion 363a of the outer ring 363 and fixed in the radial direction). It becomes. Thereby, the rotational torque of the field magnet 32 is transmitted to the shaft 31 via the one-way clutch 36.

  Further, as shown in FIG. 5B, when the rotation speed of the field magnet 32 is lower than the rotation speed of the shaft 31, the rolling element 361 moves in a direction in which the elastic member 364 is compressed, The outer peripheral surface 314c of the large diameter part 314 of the shaft 31 and the rolling element 361 are not in contact with each other. Therefore, the rotational torque of the field magnet 32 is not transmitted to the shaft 31 by the one-way clutch 36.

  Therefore, as shown in FIGS. 5A and 5B, the one-way clutch 36 has the field magnet 32 only when the rotational speed of the field magnet 32 is equal to or larger than the rotational speed of the shaft 31. Is transmitted to the shaft 31.

  Here, the field magnet 32 causes rotation unevenness due to torque fluctuation due to cogging torque generated between the field magnet 32 and the armature 33. That is, the field magnet 32 does not rotate at a uniform rotational speed. However, since the one-way clutch 36 is disposed between the field magnet 32 and the shaft 31 in the radial direction, the rotational speed of the field magnet 32 is lower than the rotational speed of the shaft 31. In this case, the rotational torque of the field magnet 32 is not transmitted to the shaft 31. Therefore, it is possible to suppress the torque fluctuation due to the cogging torque when the rotational speed of the field magnet 32 is small relative to the rotation of the shaft 31 from being transmitted to the shaft 31. Therefore, the magnitude of the torque fluctuation of the shaft 31 due to the cogging torque generated between the field magnet 32 and the armature 33 can be reduced. As a result, compared with the rotational speed of the shaft 31, the component of rotational unevenness when the rotational speed of the field magnet 32 is small can be suppressed.

  With this configuration, the rotation unevenness of the shaft 31 is reduced as described above in this embodiment as compared with the structure in which the shaft and the field magnet of the conventional structure shown in FIG. 6 are directly fixed. That is, the rotation unevenness of the inner member 21 fixed to the shaft 31 can also be reduced. Accordingly, when the external teeth 211 of the internal rotation member 21 and the internal teeth 221 of the external rotation member 22 mesh with each other, the external teeth 211 and the internal teeth 221 can be kept in contact with each other. The meshing sound with 221 can be reduced. Thereby, since the meshing noise between the external teeth 211 and the internal teeth 221 can be reduced without increasing the number of teeth of the external teeth 211 and the internal teeth 221, the size of the internal gear pump 2 can be increased. Can be prevented. As a result, it is possible to provide the electric pump 1 in which the internal gear pump 2 is prevented from being enlarged while the noise of the internal gear pump 2 is reduced.

  Further, the field magnet 32 is applied with a force to move in the circumferential direction against the outer ring 363 by the interaction with the armature 33. Therefore, when the field magnet 32 and the outer ring 363 are fixed with an adhesive, the inner peripheral surface 32a of the field magnet 32 and the outer peripheral surface of the outer ring 363 (that is, the outer surface of the outer ring 363 in the radial direction). This means that a bonding strength sufficient to counteract the force with which the field magnet 32 tries to move in the circumferential direction with respect to the outer ring 363 is required. Further, since the bonding strength is proportional to the area of the bonding surface, the inner diameter of the inner peripheral surface of the field magnet 32 and the inner diameter of the outer peripheral surface of the outer ring 363 need to have a certain size. In the conventional structure shown in FIG. 6, the area of the joint surface with the inner peripheral surface 106a of the field magnet 106 is reduced by providing a large-diameter portion 105a having a larger outer diameter than other portions of the shaft 105 serving as the joint surface. It was secured.

  In the present embodiment, a structure in which the one-way clutch 36 is disposed at the position of the large-diameter portion 105a of the shaft 105 having the conventional structure shown in FIG. 6 (that is, the outer diameter and the large-diameter portion 104a of the one-way clutch 36). Of the outer diameter D4). That is, the outer diameter D3 of the large-diameter portion 314 of the shaft 31 of the present embodiment is set smaller than the outer diameter D4 of the large-diameter portion 105a of the shaft 105 having the conventional structure. The one-way clutch 36 is disposed within the range of the inner diameter R1 of the inner peripheral surface 32a of the field magnet 32. As a result, the cost of the shaft 31 can be reduced because the base material price and processing time of the shaft 31 can be reduced compared to the shaft 105 having the conventional structure. In addition, since the one-way clutch 36 is disposed within the range of the inner diameter R1 of the inner peripheral surface 32a of the field magnet 32, the motor unit 3 in the radial direction is compared with the conventional structure shown in FIG. Increase in size can be prevented.

According to the electric pump of this embodiment, the following effects can be obtained.
(1) The electric pump of this embodiment is configured such that a one-way clutch 36 is disposed between the shaft 31 and the field magnet 32 in the radial direction. With this configuration, when the rotational speed of the field magnet 32 is smaller than the rotational speed of the shaft 31, the rolling element 361 of the one-way clutch 36 and the outer peripheral surface 314c of the large-diameter portion 314 of the shaft 31 are in a non-contact state. Therefore, the rotational torque of the field magnet 32 is not transmitted to the shaft 31. And the shaft 31 can suppress the influence of the rotation nonuniformity which generate | occur | produces by the torque fluctuation by the cogging torque of the field magnet 32, and can suppress the rotation nonuniformity of the internal rotation member 21 fixed to the shaft 31. Accordingly, since the outer teeth 211 and the inner teeth 221 can be kept in contact with each other while the outer teeth 211 of the inner rotation member 21 and the inner teeth 221 of the outer rotation member 22 are engaged, the outer teeth 211 and the inner teeth 221 are maintained. The meshing noise can be reduced. As a result, the meshing noise between the outer teeth 211 and the inner teeth 221 can be reduced without increasing the number of teeth of the outer teeth 211 of the inner rotation member 21 and the number of teeth of the inner teeth 221 of the outer rotation member 22. . Therefore, it is possible to provide an electric pump that prevents the electric pump from being enlarged while achieving reduction in noise of the electric pump.

  (2) The electric pump of this embodiment is configured such that the rolling element 361 of the one-way clutch 36 is in sliding contact with the outer peripheral surface 314 c of the large-diameter portion 314 of the shaft 31. Therefore, the outer peripheral surface 314c of the large-diameter portion 314 of the shaft 31 serves as an inner ring of the one-way clutch 36, and an inner ring that is in sliding contact with the rolling element 361 is not required for the one-way clutch 36. As a result, compared with a structure in which a one-way clutch having an inner ring is fixed to the large-diameter portion 314 of the shaft 31, the rotating member 3a can be downsized in the radial direction, and the motor portion 3 in the radial direction can be achieved. It is possible to provide the electric pump 1 having a reduced size.

  (3) The electric pump of this embodiment is configured such that the rolling elements 361 of the one-way clutch 36 are cylindrical rollers. Therefore, compared with the case where the rolling element 361 is a spherical ball, the one-way clutch 36 can be reduced in size in the radial direction. Therefore, as compared with a structure in which a one-way clutch provided with a spherical ball is fixed to the large-diameter portion 314 of the shaft 31, it is possible to reduce the size of the rotating member 3a in the radial direction. The electric pump 1 in which the size 3 is reduced can be provided.

The electric pump of this embodiment can be modified as follows.
In the electric pump 1 of the present embodiment, the internal gear pump 2 in which the external teeth 211 of the internal rotation member 21 and the internal teeth 221 of the external rotation member 22 mesh with each other is used as the gear pump, but the present invention is not limited to this. Never happen. For example, an external gear pump may be used as the gear pump.

  -Although the one-way clutch 36 of the electric pump 1 of this embodiment used the coil spring for the elastic member 364, this invention is not limited to this. For example, the elastic member 364 may be changed from a coil spring to a leaf spring.

  In the electric pump 1 of the present embodiment, the field magnet 32 and the armature 33 are opposed to each other in the radial direction, and the armature 33 is disposed so as to surround the field magnet 32. However, the present invention is not limited to this. For example, a structure in which the field magnet 32 is disposed so as to surround the armature 33 may be employed. Further, the field magnet 32 and the armature 33 may face each other in the axial direction.

  -Although the one way clutch 36 of the electric pump 1 of this embodiment was the structure where the rolling element 361 slidably contacts with the outer peripheral surface of the shaft 31, this invention is not limited to this. For example, a substantially cylindrical inner ring with which the rolling element 361 is in sliding contact may be fitted and fixed to the outer peripheral surface 314 c of the large diameter portion 314 of the shaft 31.

It is sectional drawing which showed the electric gear pump of this invention. It is the top view seen from the axial direction which showed the internal gear pump of this invention. It is the enlarged view of FIG. 1 which showed the rotary body of this invention. It is sectional drawing which showed the one-way clutch of this invention. FIG. 5 is a partially enlarged view of FIG. 4 showing the position of the rolling element of the one-way clutch according to the rotational speed state of the shaft and the field magnet, and (a) is compared with the rotational speed of the shaft; The case where the rotational speed of the field magnet is equal or large is shown, and (b) is a diagram showing the case where the rotational speed of the field magnet is lower than the rotational speed of the shaft. It is sectional drawing which showed the conventional electric gear pump.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electric pump, 2 ... Internal gear pump (gear pump), 3 ... Motor part, 3a ... Rotating member, 3b ... Fixed member, 31 ... Shaft, 314c ... Outer peripheral surface, 32 ... Field magnet, 33 ... Armature, 36: one-way clutch, 361: rolling element, 363: outer ring.

Claims (3)

An electric pump having a gear pump and a motor unit for driving the gear pump,
The motor unit includes a rotating member fixed to the gear pump and having a shaft serving as a drive shaft, a field magnet that rotates together with the shaft, and an armature disposed to face the field magnet. A fixing member,
An electric pump, wherein a one-way clutch is disposed between the shaft and the field magnet in a radial direction of the electric pump. The electric pump according to claim 1,
The one-way clutch includes a rolling element and an outer ring that surrounds the rolling element and to which the field magnet is fixed.
The electric pump characterized in that the rolling element is in sliding contact with the outer peripheral surface of the shaft. The electric pump according to claim 2,
The rolling element is a cylindrical roller.

Images