JP2008274854A - Electric pump unit and electric oil pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric pump unit reduced in size in an axial direction, improved in assemblability by having fewer components, and surely and stably applying a preload on a rolling bearing. <P>SOLUTION: A small groove 13f is formed on a surface of a pump plate 13 to communicate with a small space 2a formed between a pump plate 13 and a tip part 37t of a motor rotor. Oil is introduced to a space 2a through the small groove 13f under a pressurized condition with accompanying operation of an internal gear pump 2, and preload is applied on a rolling bearing rotatably supporting the motor rotor via the motor rotor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric pump unit in which a pump unit that sucks and discharges oil (fluid) and an electric motor that drives the pump unit, and an electric oil pump in which the electric pump unit is preferably used.

  In recent years, in response to global environmental problems, electric oil pumps for assisting hydraulic pressure that decreases during idle stop have been widely used in automobile transmissions (transmissions).

  The electric oil pump uses an electric pump unit in which an internal gear pump that sucks and discharges oil (fluid) as a drive source and an electric motor that drives the internal gear pump are unitized (integrated). (See Patent Document 1).

  In such an electric oil pump, the internal gear pump and the motor rotor (rotary main shaft) of the electric motor are combined to reduce the number of parts, reduce the size, and reduce the manufacturing cost.

  Referring to FIG. 4, the overall structure of this type of electric oil pump will be described. The electric oil pump includes an inner rotor 21 having a Paracoid (registered trademark) tooth shape and an outer mesh that is in mesh with the inner rotor 21. An internal gear pump 2 (pump portion) having a rotor 22 and configured to suck and discharge oil by rotation of both rotors 21 and 22, and provided adjacent to the internal gear pump 2; A suction port (not shown) for sucking oil into a pump chamber formed between the outer periphery of the inner rotor 21 and the inner periphery of the outer rotor 22 and for discharging the oil to the exterior transmission of the automobile. And a pump plate 13 having a discharge port (not shown).

  The electric oil pump further includes a motor rotor 37 that pivotally supports the inner rotor 21 at a tip end portion 37t from a side different from the pump plate 13 by using a stator 34 to rotate the motor rotor 37 by electromagnetic force. The gear pump 2 includes an electric motor 3 that sucks and discharges oil, and a housing body 1 that houses the inscribed gear pump 2 and the electric motor 3.

  Specifically, the housing body 1 includes a bottomed cylindrical pump housing 11 that houses the inscribed gear pump 2, and a bottomed cylindrical motor housing 12 that houses the electric motor 3. The housing body 1 is partitioned by a bottom 11a of a pump housing 11, and the inscribed gear pump 2 and the electric motor 3 are accommodated in the partitioned spaces. The inscribed gear pump 2 is housed in a cylindrical pump housing space 23 formed by closing the pump housing 11 with a pump plate 13.

  In the electric oil pump shown in FIG. 4, a small cylindrical space (gap) 2 a is formed between the tip 37 t of the motor rotor 37 and the pump plate 13. The pump plate 13 is joined (adjacent) to the inscribed gear pump 2 and closes the pump accommodating space 23 by a joining surface 13s on the electric motor 3 side.

  The stator 34 includes a stator core 32 made of a laminated core and a coil 33 wound around the stator core 32 via an insulator. Further, the motor rotor 37 is made of mild steel, and includes a rotor core 35 whose central portion bulges in a columnar shape, and a cylindrical permanent magnet 36 that is externally fitted to the bulged portion of the rotor core 35.

The motor rotor 37 is rotatably supported by a housing body 1 that houses the electric motor 3 via a pair of axially front and rear rolling bearings 5a and 5b.
Specifically, the inner rings of the rolling bearings 5a and 5b are fixed to the front end portion 37t and the rear end portion 37e of the motor rotor 37 so as not to move relative to each other. The pump housing 11 is provided with a through hole 11b having a stepped portion so as to penetrate the tip portion 37t of the motor rotor 37, and the outer ring of the rolling bearing 5a is fitted and fixed in the through hole 11b. Yes. The through hole 11b is fitted with a seal material 5 for preventing oil from entering from the inscribed gear pump 2 through the through hole 11b. On the other hand, the outer ring of the rolling bearing 5b is fitted and fixed in a cylindrical projecting portion 14b provided on the bottom plate (bottom portion) 14 of the motor housing 12 (housing main body 1).

  Further, as shown in an enlarged view in FIG. 5A, the bottom of the cylindrical protrusion 14b of the motor housing 12 is provided as an urging member shown in FIGS. 5B and 5C. An annular wave washer 12a (plate material thickness Ta [mm], full width Tb [mm] of the corrugated portion; Ta <Tb) is disposed on the inner periphery of the projecting portion 14b along the outer periphery thereof. The wave washer 12a is interposed in a gap having a thickness Ts [mm] (Ta <Ts <Tb) formed between the bottom plate 14 of the motor housing 12 and the rolling bearing 5b (outer ring thereof). The center of the motor rotor 37 is positioned on the center axis, and the bottom plate 14 of the motor housing 12 and the rolling bearing 5b (the outer ring thereof) are pressed simultaneously.

  The electric oil pump shown in FIG. 4 includes a controller board 6 on which an electronic circuit for controlling the electric motor 3 is formed. The controller board 6 is connected to the controller board 6 via a plurality of bolts 14a,. It is fixed to the bottom plate 14 of the motor housing 12.

In the electric oil pump shown in FIG. 4, the rolling bearing 5b is directly pressed by the wave washer 12a to give a so-called “preload”, and the white arrow in FIG. 4 is shown via the rolling bearing 5b. The bulging portion of the motor rotor 37 is pressed in the direction a. Further, this pressing force is transmitted to the rolling bearing 5a through the bulging portion, and presses the inner ring of the rolling bearing 5a, so that “preload” is applied to the rolling bearing 5a. In this way, the “gap” due to the internal gaps of the rolling bearings 5a and 5b is eliminated, and the motor rotor 37 rotates stably without shaking.
JP 2006-188968 A

  However, such a wave washer 12a leads to an increase in the number of parts in the electric oil pump and an accompanying deterioration in assemblability. This is also contrary to the demand for cost saving that has been particularly strongly demanded for parts for automobiles in recent years. Further, since the wave washer 12a is disposed on the central axis of the motor rotor 37, the presence of the wave washer 12a may hinder the axial reduction of the electric oil pump (electric pump unit). Furthermore, since the wave washer 12a is a member made of a metal material deformed, the so-called “sagging” occurs with time, the elastic force is deteriorated, and the pressing force to the rolling bearings 5a and 5b is reduced. There are also concerns.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an axial compact in an electric pump unit in which a pump unit for sucking and discharging fluid and an electric motor are unitized. An electric pump unit is provided that can reduce the number of components and improve the assembly performance, and can reliably and stably apply a preload to a rolling bearing.

  In order to solve the above problems, the invention according to claim 1 is directed to a pump unit having an inner rotor, an outer rotor that is in mesh with the inner rotor, an outer periphery of the inner rotor, and an inner periphery of the outer rotor. A pump port for sucking fluid into a pump chamber formed between and a discharge port for discharging the fluid to the outside, and a pump plate provided adjacent to the pump unit, An electric motor in which the pump unit sucks and discharges fluid by rotating a motor rotor that pivotally supports the inner rotor from a side different from the pump plate by electromagnetic force using a stator, and the pump unit and the electric motor An electric pump unit comprising a housing for accommodating a motor, wherein the motor rotor is disposed in front and rear in the axial direction on the housing. A small space is formed between the front end of the motor rotor and the pump plate, and the pump plate includes a suction port and a discharge port in the space. A passage for introducing fluid from any one of them is formed, and fluid is introduced into the space in a pressurized state through the passage as the pump unit is operated, and preload is applied to the rolling bearing through the motor rotor. The gist is to do.

  According to this configuration, with the operation of the pump unit, a part of the fluid sucked and discharged by the pump unit into the space passes through the passage formed in the space formed between the tip of the motor rotor and the pump plate. It is introduced in a pressurized state by the discharge pressure of the pump unit. Then, the motor rotor is pressed in the axial direction by the fluid pressure, whereby preload is applied to the pair of axially front and rear rolling bearings that rotatably support the motor rotor on the housing via the motor rotor. As a result, a biasing member such as a wave washer disposed on the central axis of the motor rotor in order to apply a preload to the rolling bearing in the prior art can be eliminated without making a major design change from the conventional structure. As a result, in the electric pump unit, the overall length of the motor rotor is shortened, the axial compactness is promoted, the number of parts is reduced, and the assemblability is improved. Further, the pressing force applied to the rolling bearing does not decrease due to the sag of the wave washer over time, and a preload can be reliably and stably applied to the rolling bearing.

  According to a second aspect of the present invention, in the electric pump unit according to the first aspect, the passage communicates with the high-pressure portion side of the discharge port and a space formed between the tip portion of the motor rotor and the pump plate. The gist is that it is provided.

  According to this configuration, the passage formed in the pump plate includes the high-pressure part side (the side where the volume of the pump chamber is reduced with the rotation of the inner rotor with respect to the outer rotor), the tip of the motor rotor, and the pump Since it is provided so as to communicate with the space formed between the plates, high pressure oil supplied from the high pressure part on the discharge side of the pump chamber is used, and the motor rotor is axially high in hydraulic pressure through the passage. Thus, the preload can be more reliably applied to the rolling bearing.

  The gist of the invention of claim 3 is that, in the electric pump unit of claim 2, the passage is formed in a groove shape on the surface of the pump plate on the motor rotor side.

  According to this configuration, the passage formed in the pump plate so as to communicate with the space formed between the front end portion of the motor rotor and the pump plate is formed in a groove shape on the surface of the pump plate adjacent to the pump portion, that is, Since it is formed in a concave shape with respect to the surface, it is possible to apply a preload to the rolling bearing without requiring a space that the passage occupies in the axial direction. As a result, axial reduction in the electric pump unit is promoted.

  Invention of Claim 4 is an electric pump unit in any one of Claims 1-3. WHEREIN: The pressure of the fluid of the pressurized state introduce | transduced into the said space is 0.15 Mpa or more and 0.2 Mpa or less It is within the scope.

  According to this configuration, since the pressure of the fluid under pressure introduced into the space formed between the tip of the motor rotor and the pump plate is within the range of 0.15 MPa to 0.2 MPa, the motor rotor is Thus, the necessary preload can be reliably applied to the rolling bearing. Moreover, even if the pressure loss due to the passage formed in the pump plate is taken into consideration so as to communicate with the space formed at the tip of the motor rotor, the entire length and width of the passage are set to an appropriate length. In the pump section having a rated discharge pressure of about 0.2 MPa, the fluid pressure in the pressurized state can be easily set in the range of 0.15 MPa or more and 0.2 MPa or less without significantly increasing the pump loss. .

  The invention according to claim 5 is an electric oil pump for assisting a hydraulic pressure that is lowered during idle stop in a transmission of a vehicle such as an automobile, and the electric pump according to any one of claims 1 to 4. The gist is that the unit is used.

  According to this configuration, since the electric pump unit according to any one of claims 1 to 4 is used as an electric oil pump for assisting a hydraulic pressure that is reduced during idle stop in an automobile transmission, The use of a biasing member such as a wave washer for applying preload to the rolling bearing is promoted, and the number of parts is reduced and the assemblability is improved. Preload can be applied stably. As a result, cost saving and improved reliability as an electric pump unit for automobiles can be achieved.

  According to the electric pump unit of the present invention, downsizing in the axial direction is promoted, and the number of parts is reduced to improve the assemblability, and a preload can be reliably and stably applied to the rolling bearing. .

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings.
The electric pump unit of the present embodiment is used as an electric oil pump for assisting the hydraulic pressure that is reduced during idle stop in an automobile transmission (transmission). The electric pump unit of the conventional structure shown in FIG. 4 has the same structure except for the features of the invention, and the same or corresponding reference numerals are given to the common parts, except as specifically described below. Therefore, the description is omitted.

  As shown in FIG. 1, the electric oil pump according to the present embodiment includes an inner rotor 21 having a Paracoid (registered trademark) tooth shape and an outer rotor 22 in meshing with the inner rotor 21. , 22 is provided with an inscribed gear pump 2 (pump portion) adapted to suck and discharge oil (fluid) by rotation of the inner and outer gears 22, 22 and adjacent to the inscribed gear pump 2. A pump having a suction oil passage 13a for sucking oil into a pump chamber 25 formed between the inner peripheries of the rotor 22 and a discharge oil passage 13b for discharging the oil to the transmission of an automobile outside. Plate 13.

  Specifically, the inner rotor 21 and the outer rotor 22 are driven by the electric motor 3 described above and are rotated in the directions of arrows A1 and A2, respectively. Further, an arc-shaped pump chamber 25 is formed between the tooth grooves 21a,..., And the tooth grooves 22a, which form the Paracoid (registered trademark) tooth profile of the rotors 21 and 22. As the rotors 21 and 22 rotate, a low pressure portion 25a is formed on the suction side and a high pressure portion 25b is formed on the discharge side.

  The pump plate 13 communicates with the low-pressure part 25a and the high-pressure part 25b of the pump chamber 25 and has a crescent-shaped suction port 13ri and a crescent moon along the outer circumference arcs of the rotors 21 and 22, respectively. A discharge port 13ro is formed through the pump plate 13 in the thickness direction. In the crescent-shaped discharge port 13ro, on the side where the volume of the pump chamber 25 is reduced as the inner rotor 21 rotates with respect to the outer rotor 22, that is, on the upper side of the crescent-shaped discharge port 13ro in FIG. A high pressure portion is formed in the crescent-shaped discharge port 13ro.

  Further, the pump plate 13 has a suction oil passage 13a and a discharge oil passage 13b connected to an external pipe communicating with the crescent-shaped suction port 13ri and the crescent-shaped discharge port 13ro through communication ports 13co and 13ci, respectively. It is formed to do.

  Furthermore, a cylindrical reflux oil passage 13d is formed in the pump plate 13 so as to communicate with the lower end portion of the crescent-shaped discharge port 13ro and extend rightward along an axis axr (left-right direction in FIG. 1). In addition, a valve mounting hole 13e having a larger diameter is formed in the reflux oil passage 13d so as to communicate along the axis axr and to a lower portion of the crescent-shaped intake port 13ri. .

  Then, when the oil pressure (fluid pressure) on the crescent-shaped discharge port 13ro (discharge oil passage 13b) exceeds a predetermined pressure, oil is supplied to the valve mounting hole 13e from the crescent-shaped discharge port 13ro to the crescent-shaped intake port 13ri. A relief valve 4 is fitted as oil recirculation means (fluid recirculation means) for recirculation. The relief valve 4 is interposed between a bottomed cylindrical adjustment screw 41 and a spool 42, and between the adjustment screw 41 and the spool 42. The oil pressure on the crescent-shaped discharge port 13ro side is set to a predetermined pressure (in this embodiment). If the pressure is less than 0.45 MPa), the spool 42 is urged toward the crescent-shaped discharge port 13ro to block the return of oil from the crescent-shaped discharge port 13ro to the crescent-shaped intake port 13ri, and the hydraulic pressure is A spring 4 s that displaces the spool 42 toward the crescent-shaped suction port 13 ri against the biasing force when the pressure exceeds a predetermined pressure, and returns oil from the crescent-shaped discharge port 13 ro side to the crescent-shaped suction port 13 ri side. ing.

  In the electric pump unit of the present embodiment, referring to FIG. 1, in the pump plate 13, the crescent moon is formed in the space 2 a (see FIG. 4) formed between the tip portion 37 t of the motor rotor 37 and the pump plate 13. It is characterized in that a semi-cylindrical small groove (passage) 13f for introducing oil from the cylindrical discharge port 13ro is formed.

  Specifically, referring to FIGS. 2A and 2B, the small groove 13f is formed on the joint surface 13s of the pump plate 13 from the high-pressure portion side of the crescent-shaped discharge port 13ro. In order to communicate with the small space 2a near the tip portion 37t, the tip portion 37t is formed to extend toward the tip portion 37t.

  The operation of the preload applying mechanism for the rolling bearings 5a and 5b according to the present embodiment will be described with reference to FIG. 3. When the automobile is running, an oil pump 50a provided as an auxiliary machine for the engine 50 is used. The oil is sucked from the oil pan 52 provided in the automobile, and the hydraulic pressure necessary for the transmission is continuously given through the check valve 7a. On the other hand, when the engine of the automobile is stopped (idle stop), the electric motor 3 is operated to assist the hydraulic pressure that is lowered during the idle stop, and the inscribed gear pump 2 is rotationally driven to provide an oil pan provided in the automobile. Oil is sucked from 52 and supplied to the transmission 51 of the vehicle at a substantially constant pressure through the check valve 7b. At this time, oil is introduced into the space 2a in a pressurized state from the crescent-shaped discharge port 13ro through the small groove 13f by the rotation of the inscribed gear pump 2, whereby the motor rotor 37 is indicated by the black arrow b in FIG. The preload is applied to the pair of front and rear rolling bearings 5a and 5b. In this case, the direction of the preload (the direction of the pressing force for pressing the motor rotor 37) is opposite to that of the conventional example (see the directions of the white arrow a and the black arrow b in FIG. 4). .

  In FIG. 3, when the pressure on the discharge side (crescent-shaped discharge port 13ro side) of the inscribed gear pump 2 becomes equal to or higher than a predetermined pressure (0.45 MPa), the relief valve 4 operates as described above. The oil is recirculated from the discharge side of the inscribed gear pump 2 to the suction side (the crescent-shaped suction port 13ri side). When the pressure of the oil introduced into the space 2a exceeds 0.2 MPa, the oil escapes to the crescent-shaped discharge port 13ro through a groove (not shown) provided in the bottom 11a of the pump housing 11. It is.

  In the inscribed gear pump 2 of the present embodiment, the rated discharge pressure is about 0.2 MPa. Therefore, in the small groove 13f, with reference to FIG. When the width (d) is d [mm], the total length L is preferably set to 15 [mm] to 25 [mm] and the width d is set to 1 [mm] to 2 [mm]. As a result, in the internal gear pump 2 having a rated discharge pressure of about 0.2 MPa, the pressurized oil pressure introduced from the crescent-shaped discharge port 13ro into the space 2a without significantly increasing the pump loss. Can be easily set in a range of 0.15 MPa or more and 0.2 MPa or less. As a result, the necessary preload can be reliably applied to the rolling bearings 5a and 5b via the motor rotor 37.

In this embodiment, the pressing force applied to the motor rotor 37 is not limited to the total length L and width d of the small groove 13f, and the shape and surface state (surface roughness Ra, etc.) of the small groove 13f, but also the motor rotor 37. Therefore, the cross-sectional area is determined to be 0.15 MPa or more, which requires a pressurized hydraulic pressure introduced into the space 2a in contact with the tip portion 37t of the motor rotor 37. to the following ranges .2MPa, for example, it is preferable that the 1 [mm ^2] or more 4 [mm ^2] or less.

As described above, according to the electric pump unit of the present embodiment, the following operations and effects can be obtained.
(1) Accompanying the operation of the internal gear pump 2, the internal gear pump 2 sucks the space 2a through the small groove 13f communicating with the small space 2a formed between the tip 37t of the motor rotor 37 and the pump plate 13. A part of the discharged oil is introduced in a pressurized state by the discharge pressure of the internal gear pump 2. Then, the motor rotor 37 is pressed in the axial direction by the hydraulic pressure, so that a preload is applied to the pair of rolling bearings 5a and 5b in the axial direction, which supports the motor rotor 37 rotatably on the housing body 1 via the motor rotor 37. Is granted. As a result, for example, only by forming the small groove 13f when the pump plate 13 is molded, the motor rotor 37 is configured to apply a preload to the rolling bearings 5a and 5b in the prior art without making a large design change from the conventional structure. The urging member such as the wave washer 12a disposed on the central axis of the can be eliminated. As a result, in the electric pump unit, the entire length of the motor rotor 37 is shortened by the thickness Ts [mm] (see FIG. 5A), and the axial compactness is promoted, and the number of parts is reduced and assembled. Improves. In addition, the pressing force applied to the rolling bearings 5a and 5b is not reduced by the sag of the wave washer 12a over time, and the preload can be reliably and stably applied to the rolling bearings 5a and 5b.

  (2) The small groove 13f formed in the joint surface 13s of the pump plate 13 reduces the volume of the pump chamber 25 as the crescent-shaped discharge port 13ro rotates on the high pressure portion side, that is, the inner rotor 21 with respect to the outer rotor 22. 1, the upper side of the crescent-shaped discharge port 13ro in FIG. 1 and the space 2a formed between the tip 37t of the motor rotor 37 and the pump plate 13 are provided to communicate with each other. For this reason, it is possible to press the motor rotor 37 with high hydraulic pressure in the axial direction through the small groove 13f by using high pressure oil supplied from the high pressure portion on the discharge side of the pump chamber 25, and to the rolling bearings 5a and 5b. Preloading can be performed more reliably.

  (3) The pump plate 13 adjacent to the inscribed gear pump 2 has a small groove 13f formed in the pump plate 13 so as to communicate with the small space 2a formed between the tip 37t of the motor rotor 37 and the pump plate 13. The bonding surface 13s (surface) is formed in a groove shape, that is, in a concave shape with respect to the bonding surface 13s. For this reason, preload can be applied to the rolling bearings 5a and 5b via the motor rotor 37 without requiring a space occupied by the small groove 13f in the axial direction. As a result, axial reduction in the electric pump unit is promoted.

  (4) Since the pressure of the pressurized oil introduced into the small space 2a formed between the tip 37t of the motor rotor 37 and the pump plate 13 is in the range of 0.15 MPa to 0.2 MPa, The necessary preload can be reliably applied to the rolling bearings 5a and 5b via the motor rotor 37. In addition, even when the pressure loss ΔP due to the small groove 13f formed in the pump plate 13 so as to communicate with the space 2a in contact with the tip 37t of the motor rotor 37 is taken into consideration, the total length L [mm] and the width d of the small groove 13f are considered. [Mm] is preferably set to an appropriate length, that is, as described above, 15 [mm] ≦ L ≦ 25 [mm] and 1 [mm] ≦ d ≦ 2 [mm], respectively. As a result, in the inscribed gear pump 2 having a rated discharge pressure of about 0.2 MPa, the hydraulic pressure in the pressurized state can be easily set to the required 0.15 MPa or more and 0.2 MPa or less without significantly increasing the pump loss. Pressure range.

  (5) Since the electric pump unit of the present embodiment is used as an electric oil pump for assisting the hydraulic pressure that is reduced during idle stop in an automobile transmission, downsizing in the axial direction is promoted, and the rolling bearing 5a, By not using an urging member such as a wave washer 12a to apply preload to 5b, the number of parts is reduced and assembly is improved, and preload is reliably and stably applied to the rolling bearings 5a and 5b. it can. As a result, cost saving and improved reliability as an electric pump unit for automobiles can be achieved.

The above embodiment may be modified as follows.
In the above embodiment, the small groove 13f for introducing the oil into the space 2a in contact with the tip 37t of the motor rotor 37 is formed on the joint surface 13s of the pump plate 13 on the high pressure portion side (outer side of the inner rotor 21) of the crescent-shaped discharge port 13ro It is formed starting from the side where the volume of the pump chamber 25 is reduced as the rotor 22 rotates, ie, the upper side of the crescent-shaped discharge port 13ro in FIG. However, the present invention is not limited to this, and as long as a necessary pressing force can be applied via the motor rotor 37 in order to apply an appropriate preload to the rolling bearings 5a and 5b, the small groove 13f is on the low pressure portion side of the crescent-shaped discharge port 13ro. (The lower side of the crescent-shaped discharge port 13ro in FIG. 1) can be used as a starting point, or can be formed at the crescent-shaped intake port 13ri.

  In the above embodiment, the electric pump unit is used as an electric oil pump for assisting the hydraulic pressure that is reduced during idle stop in an automobile transmission, but the electric pump unit of the present invention is used for other automobile applications, for example, It can also be used as a steering pump for assisting the steering operation of an automobile, and can be widely used for applications other than such automobile applications.

  In the above-described embodiment, the inscribed gear pump includes a paracoid (registered trademark) including an inner rotor 21 having a paracoid (registered trademark) tooth profile and an outer rotor 22 that is in mesh with the inner rotor 21 in an eccentric state. ) An example of the inscribed gear pump 2 using a tooth profile has been described. However, the internal gear pump 2 is not limited to this, and the internal gear pump 2 includes other internal gear pumps composed of an inner rotor 21 as an external gear and an outer rotor 22 as an internal gear, for example, a trochoidal tooth profile. It may be an internal gear pump.

  In the above-described embodiment, the small groove 13f as a passage leading to the small space 2a formed so as to be adjacent to the tip portion 37t of the motor rotor 37 is formed to extend linearly on the surface (joining surface 13s) of the pump plate 13. . However, the small groove 13f may not be so linear as long as a necessary pressing force can be applied via the motor rotor 37 in order to apply an appropriate preload to the rolling bearings 5a and 5b. It may be bent at an angle, or may be an arc shape or a wave shape.

  In the above embodiment, to the rolling bearings 5 a and 5 b instead of the wave washer 12 a disposed on the bottom plate 14 of the housing body 1 as an urging member for applying a preload to the rolling bearings 5 a and 5 b via the motor rotor 37. Although the above-described configuration of the present embodiment is employed as the preload applying mechanism, a conventional preload applying mechanism replaced by the configuration of the present embodiment is an urging member other than the wave washer 12a. Needless to say, the urging member disposed on the bottom plate 14 may be applicable to, for example, a leaf spring, a coil spring, and the like.

Sectional drawing which shows the principal part of the electric pump unit concerning embodiment of this invention. (A) is the perspective view which looked at the pump plate of the electric pump unit shown in FIG. 1 from the joint surface side which joins an internal gear pump ((alpha) is the enlarged view which expanded the small groove part), (b) is (a) ) Is a front view of the small groove in FIG. The figure which shows an example of the hydraulic circuit for supplying hydraulic pressure to the transmission of the motor vehicle concerning embodiment of this invention. The axial sectional view of the electric pump unit concerning a prior art example. (A) is sectional drawing which expanded the rear end part vicinity of the motor rotor in the electric pump unit concerning a prior art example, (b) is used in the electric pump unit concerning a prior art example in order to give a preload to a rolling bearing. (C) is a BB direction arrow view of (b).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Housing main body, 2 ... Internal gear pump, 2a ... Space, 3 ... Electric motor, 4 ... Relief valve, 5a, 5b ... Rolling bearing, 11 ... Pump housing, 12 ... Motor housing, 13 ... Pump plate, 13a ... Intake oil passage, 13b ... Discharge oil passage, 13f ... Small groove, 13ri ... Crescent suction port, 13ro ... Crescent discharge port, 21 ... Inner rotor, 22 ... Outer rotor, 25 ... Pump chamber, 25a ... Low pressure part, 25b ... High pressure part, 37... Motor rotor, 37 t... Tip end of motor rotor, 51.

Claims (5)

A pump unit having an inner rotor and an outer rotor inscribed and meshed with the inner rotor;
The pump unit includes a suction port for sucking fluid into a pump chamber formed between the outer periphery of the inner rotor and the inner periphery of the outer rotor, and a discharge port for discharging the fluid to the outside. An adjacent pump plate;
An electric motor configured to suck and discharge fluid by rotating a motor rotor that pivotally supports the inner rotor from a side different from the pump plate by electromagnetic force using a stator, and the pump unit and In an electric pump unit comprising a housing that houses an electric motor,
The motor rotor is rotatably supported by the housing via a pair of axially front and rear rolling bearings,
A small space is formed between the tip of the motor rotor and the pump plate, and
The pump plate is formed with a passage for introducing fluid into the space from either the suction port or the discharge port.
An electric pump unit, wherein a fluid is introduced into the space through the passage in a pressurized state in accordance with the operation of the pump unit, and a preload is applied to the rolling bearing through the motor rotor. In the electric pump unit according to claim 1,
An electric pump unit in which the passage is provided so as to communicate a high-pressure portion side of the discharge port with a space formed between a tip portion of a motor rotor and a pump plate. In the electric pump unit according to claim 2,
The electric pump unit in which the passage is formed in a groove shape on the surface of the pump plate on the motor rotor side. In the electric pump unit according to any one of claims 1 to 3,
An electric pump unit in which a pressure of a fluid in a pressurized state introduced into the space is in a range of 0.15 MPa to 0.2 MPa.   An electric oil pump for assisting a hydraulic pressure that decreases during idle stop in a transmission of a vehicle such as an automobile, wherein the electric pump unit according to any one of claims 1 to 4 is used. Electric oil pump.

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