JP5803165B2 - Electric pump unit - Google Patents

Description

This invention relates to, for example, the electric pump unit using a pump which is used as a hydraulic pump for supplying hydraulic pressure to the automobile transmission (transmission).

  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).

JP 2008-215088 A

  In the above conventional electric pump unit, an internal gear pump is used as a pump, and a DC brushless motor is used as an electric motor. The motor shaft of the electric motor is directly connected to the inner gear that is the pump rotor, and the motor shaft and the inner gear rotate at the same rotational speed.

  For this reason, there are the following problems in terms of the efficiency of the entire electric pump unit.

  FIG. 4 is a graph showing the relationship between the rotational speed and efficiency in the internal gear pump and the DC brushless motor. FIG. 4A shows the efficiency of the pump alone (pump efficiency), FIG. 4B shows the efficiency of the motor alone (motor efficiency), the horizontal axis shows the rotation speed, and the vertical axis shows the efficiency.

  Generally, in an internal gear pump, the efficiency decreases as the rotational speed increases. On the other hand, the motor is more efficient when it is a high-rotation and low-torque type, and the efficiency increases as the rotational speed increases. For this reason, there is a relatively large difference between the rotational speed Sp at which the pump efficiency is maximum and the rotational speed Sm at which the motor efficiency is maximum, and the rotational speeds of the pump and motor are set to either Sp or Sm. As a whole, the electric pump unit cannot achieve high efficiency. Therefore, conventionally, the rotational speed (for example, S) is set such that the product of the pump efficiency and the motor efficiency is the highest, but the efficiency of the electric pump unit as a whole is still low.

The purpose of this invention is to solve the above problems, while achieving weight reduction and compactness, there is provided a photoelectric dynamic pump unit can be made higher overall efficiency.

An electric pump unit according to the present invention includes a pump having a pump rotor connected to a pump drive shaft in a pump body, and an electric motor provided in a motor housing connected to the pump body and driving the pump drive shaft. In the electric pump unit, a transmission is incorporated between the inner periphery of the pump rotor and the pump drive shaft to change the rotation of the pump drive shaft and transmit it to the pump rotor. The reduction ratio of the transmission is set so that the pump efficiency is the highest when the value is set to be the highest .

  The pump is driven by, for example, an electric motor. In this case, the pump drive shaft can be the motor shaft of the electric motor. The rotation of the pump drive shaft is shifted by the transmission and transmitted to the pump rotor. For this reason, even when the rotational speed at which the efficiency is highest differs between the pump and the electric motor, each rotational speed can be set in a region where the respective efficiency becomes high, thereby increasing the efficiency of the entire electric pump unit. be able to.

  Since the transmission is incorporated in the inner periphery of the pump rotor, the axial dimension of the pump does not increase. In order to incorporate the transmission on the inner periphery of the pump rotor, it is necessary to increase the inner diameter of the pump rotor, but in some cases, the outer diameter of the pump rotor may be reduced by reducing the radial thickness of the pump rotor. Can be made the same as before. Even if this is not the case, the increase in the radial dimension of the pump rotor can be minimized.

  For example, the transmission is a planetary gear reducer.

  The planetary gear type reduction gear includes a sun gear, a ring gear, and a plurality of planetary gears. The sun gear is fixedly provided on the outer periphery of the pump drive shaft. The ring gear is fixedly provided on the inner periphery of the pump rotor. The planetary gear is disposed between the sun gear and the ring gear and meshes with both gears.

  In this case, the rotation of the pump drive shaft is decelerated by the planetary gear reducer and transmitted to the pump rotor. For this reason, even when the pump is driven by an electric motor and the rotational speed at which the efficiency is highest is higher in the electric motor, the respective rotational speeds can be set in regions where the respective efficiency is increased. This can increase the efficiency of the entire electric pump unit. When the pump efficiency and the motor efficiency are as shown in FIG. 4, the rotation speed of the pump can be set in a region close to Sp, and the rotation speed of the electric motor can be set in a region close to Sm.

  In addition, since the planetary gear type speed reducer has the above-described configuration, it can be easily incorporated into the inner periphery of the pump rotor.

  For example, the pump is an internal gear pump in which an inner gear that rotates in mesh with the outer gear is disposed inside the outer gear, and a pump rotor in which a transmission is incorporated on the inner periphery is the inner gear.

  The electric pump unit according to the present invention includes the pump according to the present invention, and a motor driving electric motor for driving a pump driving shaft is provided in a motor housing connected to the pump body.

  In this case, the motor shaft of the electric motor can be used as the pump drive shaft. And the efficiency of the whole electric pump unit can be raised like the case of said pump, and a dimension increase can be made small as much as possible.

According to electrostatic dynamic pump unit of the invention, as described above, together with reducing the weight and compact, it is possible to increase the efficiency of the entire electric pump unit.

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. FIG. 3 is an enlarged cross-sectional view taken along line III-III in FIG. FIG. 4 is a graph showing the relationship between the rotational speed and efficiency in the pump and the electric motor.

  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). Although not shown, an oil suction port and an oil discharge port are formed in the pump housing (7) and the pump plate (8), and an oil suction hole and an oil communicating with the oil suction port are formed in the pump plate (8). An oil discharge hole communicating with the discharge port is formed. 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 portion (7b) having a smaller diameter than the motor case (13) is integrally formed at the center of the rear end surface of the pump housing (7), and the bearing device (17) provided at the rear portion in the cylindrical portion (7b) A motor shaft (18), which is a pump drive shaft extending in the front-rear direction, is cantilevered. In this example, the bearing device (17) is composed of two single row deep groove ball bearings (19) adjacent to the front and rear, and the inner ring (19a) of each bearing (19) is a motor shaft (18). The outer ring (19b) is fixed to the cylindrical portion (7b). In this example, the bearing (19) is a grease lubricated hermetically sealed bearing. The front part of the motor shaft (18) penetrates the hole (21) formed in the rear wall of the pump housing (7) and enters the pump chamber (9). An inner gear (12) is connected to the front end of the motor shaft (18) in the pump chamber (9), as will be described in detail later. An oil seal (22) is provided between a portion of the cylindrical portion (7b) in front of the bearing device (17) and the motor shaft (18).

  A motor rotor (23) constituting the motor (3) is fixed to a rear 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 (19) 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).

  Details of the part of the pump (2) are shown in FIG.

The inner gear (12) of the pump (2) is connected to the motor shaft (18) via the transmission (40). The transmission (40) is disposed between the inner periphery of the inner gear ( 12 ) and the motor shaft (18). In this example, the transmission (40) is a planetary gear reducer.

  The transmission (40) is composed of an external sun gear (41), an internal ring gear (42), and a plurality (three in this example) of planetary gears (43) meshing therewith. The sun gear (41) is fixedly provided at the front end of the motor shaft (18). The ring gear (42) is fixedly provided on the inner periphery of the inner gear (12). The planetary gear (43) is rotatably supported at both front and rear ends by a support shaft (44) fixed to the pump plate (8) and the pump housing (7).

  In the above example, the ring gear (42) is fixed to the inner periphery of the inner gear (12), but teeth may be formed directly on the inner periphery of the inner gear (13) to provide the ring gear in a fixed form. Good. The sun gear (41) is also fixed to the outer periphery of the front end portion of the motor shaft (18) in the above example, but the sun gear is fixed by forming teeth directly on the outer periphery of the motor shaft (18). You may make it provide.

  The reduction ratio of the transmission (40) is determined by the number of teeth of the sun gear (41) and the number of teeth of the ring gear (42) regardless of the number of teeth of the planetary gear (43). When the pump efficiency and the motor efficiency are as shown in FIG. 4, the rotational speed of the inner shaft (12) is set to a region close to Sp and the rotational speed of the motor shaft (18) is set to Sm by appropriately setting the reduction ratio. It is possible to set each in a region close to. Thereby, the efficiency of the entire electric pump unit is increased.

  The transmission (40) is not limited to a planetary gear reducer.

  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
(11) Outer gear
(12) Inner gear (pump rotor)
(18) Motor shaft (pump drive shaft)
(40) Transmission

Claims (3)

A pump for have a pump rotor connected to the pump drive shaft within the pump body,
In an electric pump unit that is provided in a motor housing connected to the pump body and includes an electric motor that drives a pump drive shaft,
A transmission that shifts the rotation of the pump drive shaft and transmits it to the pump rotor is incorporated between the inner periphery of the pump rotor and the pump drive shaft so that the motor efficiency is maximized. An electric pump unit characterized in that a reduction gear ratio of the transmission is set so that the pump efficiency becomes highest when set. 2. The electric pump unit according to claim 1, wherein the transmission is a planetary gear reducer . 2. The pump according to claim 1, wherein the pump is an internal gear pump in which an inner gear rotating in mesh with the outer gear is disposed inside the outer gear, and the pump rotor in which a transmission is incorporated on the inner periphery is the inner gear. 2 electric pump units.

Images