JP2012189015A - Electric pump unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric pump unit which is reduced in weight and size, increased in bearing support rigidity of a bearing device, and reduced in tilting of a motor shaft and a motor rotor.SOLUTION: A motor housing 6 incorporating a pump-driving electric motor 3 is fixed to the pump body 5 of a pump 2 that sucks and discharges oil. The bearing device 17 is provided to the inside of a cylindrical part 7b formed in the pump body 5 and extended into the motor housing. The electric motor includes a pump-driving electric motor shaft 18 supported by the bearing device, a cylindrical motor rotor 23 extended outward in a radial direction from one free end of the motor shaft and surrounding the outer periphery of the bearing device, and a motor stator 27. A pump rotor 12 is fixed to the other free end of the motor shaft 18. The bearing device 17 consists of two ball bearings 21, 22 axially adjacent across a sealing member 20, and the ball bearing 21 of the pump 2 side is an open type.

Description

  The present invention relates to an electric pump unit used as a hydraulic pump for supplying hydraulic pressure to a transmission (transmission) of an automobile, for example.

  Hydraulic pressure is supplied to the vehicle's transmission by a hydraulic pump. However, in order to save energy, the vehicle is stopped when the vehicle is stopped, so-called idle stop (idling stop) is secured. In order to do so, an electric hydraulic pump is used.

  Since an electric hydraulic pump for an automobile transmission is mounted in a limited space of a vehicle body, it is required to be compact, and to be light and reduce costs. In order to meet such a demand, an electric pump unit in which a pump, an electric motor for driving a pump, and a controller for the electric motor are incorporated in a common unit housing has been proposed (for example, see Patent Document 1).

  In such a conventional electric pump unit, a motor housing is connected to a pump body constituting the pump, and an electric motor and a controller are built in a sealed motor chamber formed in the motor housing. The electric motor is disposed on the pump body side in the motor chamber, and a controller board is fixed to the end surface of the electric motor on the side opposite to the pump body. A plurality of electrical components (electrical components and electronic components) such as capacitors and FETs constituting the controller are attached to the substrate.

  The electric motor includes a cylindrical motor rotor extending radially outward from one free end of the pump drive motor shaft supported by the bearing device and surrounding the outer periphery of the bearing device, and a motor fixed to the motor housing. And a stator. A pump chamber is formed inside the pump body. The pump body is formed with a cylindrical portion extending inside the motor housing, and a motor shaft bearing device is provided inside the cylindrical portion. The other free end of the motor shaft enters the motor chamber, and the pump rotor of the pump is fixed to the tip of the motor shaft. When the pump is an internal gear pump, an inner gear that is an inner pump rotor is fixed to the tip of the motor shaft.

  The bearing device includes two single-row deep groove ball bearings arranged side by side in the axial direction. An oil seal for sealing between the pump chamber and the bearing device is provided in the cylindrical portion of the pump body.

JP 2010-116914 A

  In the above-described conventional electric pump unit, two rolling bearings of the bearing device are adjacent to each other in order to reduce the size. In order to reduce the cost, the two rolling bearings are single row deep groove ball bearings, and the ball bearings are clearance fit to reduce assembly costs. Since the two ball bearings need to be lubricated, they are sealed with grease lubrication. And in order to improve the sealing performance of the oil seal, the interference is increased.

  When the pump is an internal gear pump, the oil suction port and the oil discharge port are formed at symmetrical positions of the pump housing corresponding to the meshing portion of the inner gear and the outer gear which is the outer pump rotor.

  When the pump is operating, the oil suction port in the pump chamber is at a low pressure, but the oil discharge port is at a high pressure. For this reason, a radial force acts on the tip of the cantilevered motor shaft to which the inner gear is fixed. As described above, the single row deep groove ball bearing in which the two rolling bearings of the bearing device are arranged side by side is a clearance fit, so that the bearing support rigidity is low and the motor shaft is inclined. Due to the tilt of the motor shaft, the inner gear tilts and rotates in contact with the motor housing. For this reason, noise is generated and wear occurs in the motor rotor and the motor housing. In addition, since the interference of the oil seal is large, there is a problem that the rotational torque is large.

  An object of the present invention is to provide an electric pump unit that can solve the above-described problems, reduce the weight and size, increase the bearing support rigidity of the bearing device, and reduce the inclination of the motor shaft and the motor rotor.

  In the electric pump unit according to the present invention, a motor housing incorporating a pump driving electric motor is fixed to a pump main body of a pump for sucking and discharging oil, and a pump chamber accommodating a pump rotor is formed in the pump main body. A bearing device is provided inside a cylindrical portion that is formed in the pump body and extends into the motor housing, and the electric motor is supported by a pump drive motor shaft supported by the bearing device and one free end of the motor shaft. A cylindrical motor rotor extending radially outward and surrounding the outer periphery of the bearing device, and a motor stator fixed to the motor housing, and a pump rotor at the other free end of the motor shaft entering the pump chamber In the electric pump unit in which the bearing is fixed, the bearing device is composed of two rolling bearings adjacent in the axial direction across the sealing member. Ri, in which the pump side of the rolling bearing is characterized in that an open type.

  A motor housing incorporating a pump driving electric motor is fixed to the pump body, and the electric motor has the above-described configuration. Therefore, the electric pump unit can be reduced in weight and size.

  Oil leaking from the pump chamber is accumulated in a portion closer to the pump than the sealing member of the cylindrical portion in the motor housing. Normally, this oil is allowed to escape to a low-pressure oil suction port, but a sealing member is necessary to prevent entry to the electric motor side.

  Since the two rolling bearings constituting the bearing device are arranged with the sealing member interposed therebetween, the interval between the two bearings is widened, and the bearing support rigidity is increased accordingly. Thereby, the inclination of the motor shaft and the pump rotor can be reduced. Since the position of the sealing member that seals between the bearing device and the pump chamber is between the two bearings, the axial dimension does not increase.

  Since the rolling bearing on the pump side is lubricated by the oil leaked from the pump chamber, it can be an open type. In addition, since there is a bearing on the pump side, the hydraulic pressure at which the oil leaked from the pump chamber acts on the sealing member is lowered, so that the interference of the sealing member can be reduced and the rotational torque can be reduced.

  For example, the two rolling bearings of the bearing device are single row deep groove ball bearings. Even if it does so, a bearing support rigidity can be improved for said reason, and cost can be reduced by setting it as a single row deep groove ball bearing.

  For example, if the inner ring of the pump-side rolling bearing is fitted into the motor shaft, the outer ring is fitted into the cylindrical part, and the inner ring and outer ring of the opposite rolling bearing are fitted into the motor shaft and cylindrical part, respectively. It has been

  In this case, since the outer ring of the rolling bearing on the pump side and the inner and outer rings of the rolling bearing on the opposite side are fitted together, the bearing support rigidity can be further increased. Further, since the inner ring of the rolling bearing on the pump side is fitted with clearance, it is possible to absorb the deviation between the center of the inner ring and the center of the outer ring due to press-fitting, and to reduce the clearance.

  According to the electric pump unit of the present invention, as described above, it is possible to reduce the inclination of the motor shaft and the pump rotor while reducing the weight and the size and increasing the bearing support rigidity of the bearing device.

FIG. 1 is a longitudinal sectional view of a main part of an electric pump unit showing an embodiment of the present invention. FIG. 2 is a cross-sectional view of the main part of the electric pump unit of FIG.

  Hereinafter, an embodiment in which the present invention is applied to an electric pump unit for an automobile transmission will be described with reference to the drawings.

  FIG. 1 is a longitudinal sectional view of a main part of an electric pump unit showing an embodiment of the present invention. In the following description, the left side of FIG.

  In the electric pump unit, a pump (2) for sucking and discharging oil, an electric motor (3) for driving the pump, and a controller (4) for the electric motor (3) are integrally incorporated in the unit housing (1). Is. In this example, the pump (2) is an internal gear pump, and the motor (3) is a sensorless control DC brushless motor having a three-phase winding.

  The unit housing (1) includes a pump body (5) of the pump (2), and a motor housing (6) incorporating an electric motor (3) and a controller (4).

  The pump body (5) includes a rear pump housing (7) and a front pump plate (8). The pump housing (7) has a thick plate shape that extends in a direction orthogonal to the front-rear direction, and a pump chamber (9) having an open front is formed at the center thereof. A pump plate (8) is fixed to the front surface of the pump housing (7) via an O-ring (10), and the front surface of the pump chamber (9) is closed. An outer gear (11) that is an outer pump rotor is rotatably accommodated in the pump chamber (9), and an inner gear (12) that is an inner pump rotor that meshes with the outer gear (11) is disposed inside the outer gear (11). The pump housing (7) and the pump plate (8) are made of, for example, an aluminum alloy.

  The motor housing (6) includes a cylindrical synthetic resin motor case (13) and a disc-shaped lid (14) fixed to the rear end of the motor case (13). The front end of the motor case (13) is fixed to the rear surface of the pump housing (7) via an O-ring (15). The pump plate (8), the pump housing (7), and the motor case (13) include a plurality of connecting portions (8a), (7a), and (13a) that are integrally formed so as to protrude radially outward from the outer periphery thereof. The parts are secured to each other by bolts (16). The rear end opening of the motor case (13) is closed by the lid (14).

  A cylindrical part (7b) smaller in diameter than the motor case (13) is integrally formed at the center of the rear end surface of the pump housing (7) and extends into the motor case (13), and is provided in the cylindrical part (7b). The bearing device (17) supports a motor shaft (18) which is a pump drive shaft extending in the front-rear direction. The front part of the motor shaft (18) passes through the hole (19) formed in the rear wall of the pump housing (7) and enters the pump chamber (9), and its front end (free end) The inner gear (12) is fitted and fixed to the inner side. The bearing device (17) includes two ball bearings (21) and (22) that are adjacent to the front and rear of the oil seal (20) that is a sealing member. The oil seal (20) seals between the cylindrical portion (7b) and the motor shaft (18). Inner rings (21a) and (22a) of both bearings (21) and (22) are fixed to the motor shaft (18), and outer rings (21b) and (22b) are fixed to the cylindrical part (7b). The front bearing (21) on the pump (2) side is an open single row deep groove ball bearing, and the rear bearing (22) on the opposite side is a grease lubricated sealed single row deep groove ball bearing. The inner ring (21a) of the front open type ball bearing (21) is fitted into the motor shaft (18), and the outer ring (21a) is fitted into the cylindrical part (7b). The inner ring (22a) and the outer ring (22b) of the rear sealed ball bearing (22) are fitted into the motor shaft (18) and the cylindrical portion (7b), respectively. Further, the interference of the oil seal (20) is slightly smaller than before.

  A motor rotor (23) constituting the motor (3) is fixed to a rear end portion (free end portion) of the motor shaft (18) protruding rearward from the cylindrical portion (7b). The rotor (23) extends from the rear end of the motor shaft (18) in the radial direction, and on the outer periphery of a cylindrical rotor body (24) surrounding the outer periphery of the bearing device (17), a permanent magnet holding member made of synthetic resin ( 25) is provided in a fixed shape, and segment-shaped permanent magnets (26) are held at a plurality of locations equally dividing the holding member (25) in the circumferential direction. The axial position of the center of gravity of the rotating part including the motor shaft (18), the rotor (23) and the inner gear (12) of the pump (2) is within the axial range of the bearing device (17). In this example, the axial position of the center of gravity is between the two ball bearings (21) and (22) constituting the bearing device (17).

  A motor stator (27) constituting the motor (3) is fixedly provided on the inner periphery of the motor case (13) facing the rotor (23). The stator (27) is an insulator (synthetic resin insulator) (29) incorporated in a stator core (28) made of laminated steel sheets, and a stator coil (30) is wound around the insulator (29). . In this example, the stator (27) is molded integrally with the inner periphery of the motor case (13).

  The board (31) of the controller (4) is fixed to the rear end of the insulator (29), and the component (32) constituting the controller (4) is attached to the board (31). Although only one component (32) attached to the front surface of the substrate (31) is shown in FIG. 1, the component is disposed at a predetermined position on at least one of the front surface and the rear surface of the substrate (31). The component (32) shown in FIG. 1 is, for example, an electrolytic capacitor.

  FIG. 2 is a cross-sectional view (a cross-sectional view seen from the back) showing a molded body of the motor case (13) and the stator (27).

  As shown in FIG. 2, the core (28) has pole portions (tooth portions) protruding radially inward at a plurality of locations (six locations in this example) that equally divide the inner periphery of the annular portion (28a) in the circumferential direction. (28b) is integrally formed. The tip of each pole portion (28b) extends on both sides in the circumferential direction, and its inner peripheral surface forms one cylindrical surface.

  The insulator (29) is composed of a pair of front and rear halves (33) (34). Each half body (33) (34) is formed of a synthetic resin such as PPS (polyphenylene sulfide resin), for example, and a core (28) excluding the outer peripheral surface of the annular portion (28a) and the inner peripheral surface of the pole portion (28b). It is incorporated into the core (28) from both the front and rear sides so as to cover the surface of the core. Each half body (33) (34) is formed with a coil mounting portion (33a) (34a) covering a portion excluding the inner peripheral surface of the pole portion (28b) of the core (28). In each pole part (28b) of the core (28), the coil (30) is wound around the part covered with the coil mounting parts (33a) (34a) of both halves (33) (34). Substrate protrusions (34b) extending backward are integrated into a plurality of locations (six locations in this example) that equally divide the radially outer portion of the coil mounting portion (34a) of the rear half (34) in the circumferential direction. Is formed. A metal female screw member (35) having a female screw formed on the inner periphery is embedded inside the rear end of each protrusion (34b).

  The motor case (13) is integrated with the stator (27) by molding a synthetic resin such as PA66 (polyamide 66) on the outer peripheral side of the stator (27) using a mold. The stator (27) except for the inner peripheral surface of the pole portion (28b) of the core (28), the inner peripheral surface of the coil mounting portion (33a) (34a) of the insulator (29), and the rear end surface of the protrusion (34b). Is covered with a motor case (13). A connector (37) having a plurality of pins (36) is integrally formed on the outer periphery of the motor case (13).

  The lid (14) is made of synthetic resin and is fixed to the rear end of the motor case (13) by an appropriate means such as heat welding.

  The substrate (31) of the controller (4) is fixed to the insulator (29) by a screw (39) screwed to the female screw member (35) of the protrusion (34b) of the insulator (29). Although not shown, a plurality of bus bars are incorporated in the molded body of the insulator (29) and the motor case (13), and the coils (30) of the stator (27) are electrically connected to each other using these bus bars. And electrically connected to the substrate (31). The pin (36) of the connector (37) is also electrically connected to the substrate (31).

  The oil suction port ( 40) (41) is formed. The oil discharge port (42) ) (43) is formed. The pump plate (8) has an oil suction hole (44) communicating with the oil suction port (41) and an oil discharge hole (44) communicating with the oil discharge port (43). An oil relief groove (46) communicating the hole (19) and the oil suction port (40) is formed in the wall of the pump housing (7) facing the pump chamber (9).

  When the pump (2) is driven by the electric motor (3) and the inner gear (12) and the outer gear (11) rotate, the oil suction ports (40) (41) are at low pressure and the oil discharge ports (42) (43 ) Becomes high pressure. For this reason, the inner gear (12) receives a force in the radial direction (downward in this example). Since the two ball bearings (21) and (22) constituting the bearing device (17) are arranged with the oil seal (20) sandwiched between them, the distance between the bearings (21) and (22) is widened. The bearing support rigidity is increased. Therefore, even when the cantilevered motor shaft (18) receives a radial force, the inclination is small. Since the outer ring (21b) of the front bearing (21) and the inner and outer rings (22a) (22b) of the rear bearing (22) are interference fit, the bearing support rigidity is further increased. When all the inner rings (21a) (22a) and outer rings (21b) (22b) of both bearings (21) (22) are fit together, the center of the inner ring (21a) (22a) and the outer ring (21b) Deviation occurs at the center of (22b). By making the inner ring (21a) of the bearing (21) on the pump (2) side a clearance fit, the above-mentioned deviation can be absorbed and the clearance can be reduced. Since the oil seal (20) between the two bearings (21) and (22) is the position of the conventional oil seal on the pump (2) side, the axial dimension increases. There is no.

  During operation of the pump (2), some of the oil in the oil discharge port (42) enters the hole (19) from between the pump housing (7) and the inner gear (12), but inside the hole (19). However, since the oil relief groove (46) communicates with the low pressure oil suction port (40), the oil in the hole (19) does not become high pressure. Since this oil lubricates the bearing (21) on the pump (2) side, the bearing (21) can be made open. This pump (2) side bearing (21) reduces the hydraulic pressure at which the oil in the hole (19) acts on the oil seal (20), so the tightening margin of the oil seal (20) is reduced and rotational torque is reduced. Can be reduced.

  In the above embodiment, the motor shaft (18) is supported at one location in the axial direction by the bearing device (17), and the motor rotor (23) is provided so as to surround the outer periphery of the bearing device (17). Therefore, the length of the motor shaft (18) can be shortened, and further downsizing can be achieved. Further, since the axial position of the center of gravity of the rotating part including the motor shaft (18), the motor rotor (23) and the inner gear (12) of the pump (2) is within the axial range of the bearing device (17), the rotating part Can be stably rotated. Further, since the position of the center of gravity is between the two ball bearings (21) and (22) constituting the bearing device (17), the rotating part can be supported and rotated more stably. Also, the bearing device (17) can be supported only by the cylindrical portion (7b) formed integrally with the pump housing (7), and no other configuration for supporting the bearing device is required. For this reason, the number of parts can be further reduced, and further weight reduction and downsizing can be achieved. Furthermore, since the motor stator (27) is integrally formed with the synthetic resin motor case (13) constituting the motor housing (6), the dimensional control of the motor case (13) is easy and the number of assembly steps is reduced. .

  In the above embodiment, the motor rotor (23) has a plurality of permanent magnets (26) on the permanent magnet holding member (25) made of synthetic resin fixedly provided on the outer periphery of the cylindrical rotor body (24). Therefore, there is no need to fix the permanent magnet (26) to the rotor body (24) with an adhesive, and there is no possibility of the permanent magnet (26) peeling off.

  The overall configuration of the electric pump unit and the configuration of each unit are not limited to those of the above-described embodiment, and can be changed as appropriate.

  Moreover, this invention is applicable also to electric pump units other than the electric pump unit for transmissions.

(2) Pump
(3) Electric motor
(5) Pump body
(6) Motor housing
(7b) Cylindrical part
(9) Pump room
(12) Inner gear (pump rotor)
(17) Bearing device
(18) Motor shaft
(20) Oil seal (sealing member)
(21) (22) Ball bearing
(23) Motor rotor
(27) Motor stator

Claims (2)

A motor housing incorporating a pump drive electric motor is fixed to a pump body of a pump that sucks and discharges oil, and a pump chamber containing a pump rotor is formed in the pump body, and the motor is formed in the pump body. A bearing device is provided inside a cylindrical portion extending in the housing, and the electric motor includes a pump drive motor shaft supported by the bearing device, and a bearing extending radially outward from one free end of the motor shaft. An electric pump unit including a cylindrical motor rotor surrounding the outer periphery of the apparatus and a motor stator fixed to the motor housing, and the pump rotor being fixed to the other free end of the motor shaft that has entered the pump chamber In
An electric pump unit, wherein the bearing device is two rolling bearings adjacent in the axial direction with a sealing member interposed therebetween, and the rolling bearing on the pump side is an open type.   The inner ring of the rolling bearing on the pump side is fitted into the motor shaft, the outer ring is fitted into the cylindrical part, and the inner ring and outer ring of the opposite rolling bearing are fitted into the motor shaft and cylindrical part, respectively. The electric pump unit according to claim 1, wherein

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