JP2016053309A - Electric oil pump combined with automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric oil pump combined with a new automatic transmission for improving an efficiency of the electric oil pump by increasing a rate of heat flowing from a stator toward a pump housing.SOLUTION: An outer peripheral surface of a stator is shrink fitted to an inner peripheral surface of a pump housing and fixed there to cause the inner peripheral surface of the pump housing to be pressed against the outer peripheral surface of the stator and metal contacted to each other, heat generated at a winding is directly transmitted from the stator to the pump housing and released to working oil flowing at a pump storing part arranged at a main body of an automatic transmission. With this arrangement as above, heat generated at the winding flows directly from the stator part to the pump housing, so that it is possible to release heat of the winding efficiently to working oil and improve an efficiency of the electric oil pump.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electric oil pump, and more particularly to an electric oil pump combined with an automatic transmission of an automobile.

  In recent years, as the demand for reducing fuel consumption of automobiles has increased, commercialization of automobiles with an idling stop function and hybrid cars has progressed. Since these vehicles also stop various pumps driven by the internal combustion engine when the internal combustion engine is stopped, a pump drive source other than the internal combustion engine is required. In particular, in an automobile with an idle stop function, a hybrid vehicle, or the like, an oil pump is required to ensure the hydraulic pressure of a hydraulic mechanism that controls the automatic transmission. From such a background, the use of electric oil pumps that perform a pump action by applying a rotational force to a pump rotor using an electric motor tends to increase.

  Conventionally, trochoidal internal gear pumps are often used as electric oil pumps mounted on automobile automatic transmissions and the like. In the internal gear pump, the pump rotor is rotated by a drive rotating shaft driven by an electric motor, and the outer rotor having the inner teeth that mesh with the outer teeth of the pump rotor is rotated, so that the inner teeth of the outer rotor and the outer teeth of the pump rotor are The volume of the plurality of volume chambers formed between the two is continuously changed to suck and discharge the working oil. Such an electric oil pump is described in, for example, Japanese Patent Application Laid-Open No. 2012-207638 (Patent Document 1).

  In such an electric oil pump, a drive control unit that controls energization to the electric motor, a winding unit that generates a magnetomotive force by energization from the drive control unit, a stator unit having an iron core, and an inner circumferential space of the stator unit The rotor portion having a permanent magnet and rotating by magnetomotive force, the drive rotation shaft fixed to the rotor portion by means such as press-fitting and rotating integrally, and the drive rotation shaft fixed by means such as press-fitting to the drive rotation shaft And a pump rotor portion that rotates integrally with the shaft.

  In recent electric oil pumps, a drive control unit for allowing a controlled drive current to flow in the winding portion is integrally fixed to a pump housing of the electric oil pump. As described above, the reason why the drive control unit is integrated with the electric oil pump is that the wiring between the winding and the drive control unit is shortened to reduce the adverse effect of external noise as much as possible, and the wiring cost is reduced. This is done for the purpose of facilitating calibration between the pump and the pump unit and improving handling.

JP 2012-207638 A

  By the way, as disclosed in Patent Document 1, this type of electric oil pump is used by being embedded in a pump housing portion provided in an automatic transmission main body. And this electric oil pump is used in the range of about -40 to +120 degreeC from a viewpoint of the use environment of a motor vehicle. In this case, the operating oil of the automatic transmission fluctuates within a range of about -40 to + 140 ° C. However, in a cold environment or in a winter environment where the temperature is extremely low, the operating oil viscosity increases and the pump In many cases, the rotational resistance of the rotor increases and it becomes difficult to smoothly perform the pumping action by the pump rotor.

  For this reason, in order to supply the amount of hydraulic oil required for the automatic transmission, it is necessary to increase the power supplied to the motor. However, when the electric power supplied to the electric motor is increased, the amount of heat generated by the winding wound around the iron core of the stator portion of the electric motor increases, and the electric motor efficiency decreases. The temperature of the stator portion at this time is about 200 ° C.

  And if supply electric power is increased in order to compensate the fall of the motor efficiency by the heat_generation | fever of a coil | winding, the situation where the temperature of an electric motor will raise further will be caused. Therefore, if the heat generated in the winding wound around the iron core of the stator portion is released as much as possible, it is possible to suppress a decrease in the motor efficiency due to the heat of the motor, thereby suppressing a further increase in power supply. Is possible.

  In the conventional electric oil pump as disclosed in Patent Document 1, the pump housing of the electric oil pump is housed in a pump housing portion provided in the automatic transmission main body and is in contact with the working oil. For this reason, the heat transfer from the pump housing to the working oil is easy at this contact portion. However, the stator portion around which the winding is wound is housed in the inner peripheral surface of the pump housing that houses the stator portion via a gap, and the stator portion is fixed to the pump housing by a fixing screw. For this reason, it becomes the structure where an air layer with high heat insulation exists in a stator part and an inner peripheral surface of a pump housing. In Patent Document 1, the stator portion and the pump housing are depicted as being in close contact with each other, but an air layer actually exists.

  Accordingly, since the heat generated in the winding is transferred to the pump housing via the stator core and the air layer, the ratio of the heat flowing from the stator core to the pump housing is reduced, and the stator portion consisting of the winding and the iron core. The temperature will increase. For this reason, the subject that the efficiency of an electric oil pump falls by the efficiency of an electric motor falling and the subject that the thermal lifetime of the drive control part integrated with a pump housing is reduced arise.

  An object of the present invention is to provide an electric oil pump combined with a novel automatic transmission that increases the efficiency of the electric oil pump by increasing the rate of heat flowing from the stator portion to the pump housing.

  The feature of the present invention is to fix the outer peripheral surface of the stator portion to the inner peripheral surface of the pump housing by shrink fitting, so that the inner peripheral surface of the pump housing and the outer peripheral surface of the stator portion are brought into metal contact so as to press each other, The heat generated in the winding is directly transmitted from the stator portion to the pump housing, and is released to the working oil flowing through the pump housing portion provided in the automatic transmission main body.

  According to the present invention, since the heat generated in the winding flows directly from the stator portion to the pump housing, the heat of the winding can be efficiently released to the working oil, and the efficiency of the electric oil pump can be improved. .

1 is an overall perspective view of an electric oil pump to which the present invention is applied. It is a disassembled perspective view of the electric oil pump shown in FIG. It is a longitudinal cross-sectional view of the electric oil pump which becomes one Example of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and various modifications and application examples are included in the technical concept of the present invention. Is also included in the range.

  Hereinafter, an embodiment of an electric oil pump combined with an automatic transmission according to the present invention will be described with reference to the drawings. The electric oil / oil pump is, for example, an oil pump mounted for an automatic transmission of a vehicle having an idle stop function. This automatic transmission is a belt-type continuously variable transmission, and includes a mechanical pump that is driven by an engine. Here, as described above, the electric oil pump can be fixed to various pump fixing devices. However, in this embodiment, the electric oil pump is used as a hydraulic pressure supply source of the automatic transmission. It is fixed to the housing.

  When the engine is stopped by the idle stop control, the hydraulic pressure by the mechanical pump cannot be secured, and if the hydraulic pressure decreases due to a frictional engagement element or a leak from the pulley in the belt type continuously variable transmission, it is necessary for restarting. Since it takes time to secure the hydraulic pressure, the operability is reduced. Therefore, in addition to the mechanical pump, an electric oil pump that can discharge hydraulic pressure regardless of the operating state of the engine is provided, and the engine is restarted and restarted by securing the hydraulic pressure corresponding to the leakage from the frictional engagement elements and pulleys. The driving performance at the time is improved. The automatic transmission may be a stepped transmission other than the belt type continuously variable transmission.

  FIG. 1 is a perspective view showing the overall configuration of the electric oil pump, and FIG. 2 is an exploded perspective view of the electric oil pump. The electric oil pump 10 includes an electric motor unit 10A, a drive control unit 10B fixed adjacent to the electric motor unit 10A, and a pump unit 10C driven by the electric motor unit 10A.

  As shown in FIG. 2, the electric motor unit 10 </ b> A includes at least a rotor unit 16 and a stator unit 18. The electric motor unit 10A is accommodated in an electric motor unit accommodating unit 24 provided on one side of a metallic pump housing 20 made of, for example, an aluminum alloy.

  The pump housing 20 is formed with a pump housing part 22 for housing the pump 10C. The pump unit 10C includes at least a pump rotor 12 having an external gear and an outer rotor 14 having an internal gear. The pump rotor 12 and the outer rotor 14 are housed in a pump housing portion 22 provided on the other side of the pump housing 20. The drive control unit 10B includes at least a housing 46, a control board housed in the housing 46, and a housing cover 48 fixed to the housing 46 so as to house the control board.

  Next, the detailed structure of the electric oil pump 10 in a state where the electric oil pump 10 is fixed to the casing of the automatic transmission will be described with reference to FIG.

  The casing 26 of the automatic transmission CVT is formed with a pump housing portion 26A, and the pump housing portion 26A is provided with an inflow passage 26B and an outflow passage 26C for operating oil. The electric oil pump 10 is housed in the pump housing portion 26A, and is fixed to the housing 26 by fixing bolts or the like. Then, the operation oil is sucked from the inflow passage 26B by the operation of the electric oil pump 10, and discharged from the outflow passage 26C.

  Here, the space formed by the inner peripheral surface of the pump housing portion 26 </ b> A and the outer peripheral surface of the pump housing 20 of the electric oil pump 10 is filled with the working oil, and this working oil is sucked by the electric oil pump 10. And discharged to the outflow passage 26C. Therefore, the hydraulic oil is in thermal contact with the outer peripheral surface of the pump housing 20 of the electric oil pump 10, and heat can be taken from the outer peripheral surface of the pump housing 20 to cool the electric oil pump 10.

  The electric oil pump 10 includes a pump portion 10C including a pump rotor 12 having an external gear and an outer rotor 14 having an internal gear, a rotor portion 16 coupled to the pump rotor 12, and a stator portion 18. And an electric motor unit 10A. The stator portion 18 includes a winding 18A wound around a bobbin and an iron core 18B that forms a magnetic circuit by the winding 18A. The winding 18A is drawn into the drive control unit 10B from the electric motor unit 10A.

  The pump part 10C and the motor part 10A are housed in a pump part storage part 22 provided on one end face of the pump housing 20 and a motor part storage part 24 provided on the other end face. That is, the pump housing 20 has a pump portion accommodating portion 22 that rotatably accommodates the outer rotor 14 inside the one end surface side, fixedly supports the stator portion 18 on the inner peripheral side of the opening on the other end surface side, and has a rotor inside. An electric motor unit storage unit 24 for storing the unit 16 and the like is formed, and a bracket for attaching to the housing 26 of the automatic transmission is further formed outside the motor unit storage unit 24 in the axial direction. Here, the pump housing 20 is made of a metal made of an aluminum alloy.

  The bracket formed on the pump housing 20 is fixed to the housing 26 of the automatic transmission by a fixing bolt (not shown). Although not shown, only two other brackets having the same configuration are formed, and the electric oil pump 10 is fixed to the housing 26 with the same configuration.

  Inside the pump housing 20, there is provided a bearing portion 30 that rotatably supports a drive rotary shaft 28 that connects the pump rotor 12 and the rotor portion 16. The bearing portion 30 is configured to pivotally support the outer peripheral surface of the intermediate portion of the drive rotary shaft 28 on its own inner peripheral surface.

  And the bearing part 30 is formed in the partition 32 which isolates between the pump part accommodating part 22 and the electric motor part accommodating part 24. As shown in FIG. This bearing portion 30 is a slide bearing, and a gap of a predetermined length is formed between the inner peripheral surface of the bearing portion 30 and the outer peripheral surface of the drive rotary shaft 28, and this gap is interposed via an oil introduction passage 34. The oil on the discharge side with high pressure is introduced. Further, a seal member 36 for sealing the drive rotary shaft 28 is provided above the drive rotary shaft 28 and the bearing portion 30.

  The pump cover 38 has a discharge port 40 that extends in a cylindrical shape that communicates with the discharge port of the pump unit 10C, and a suction port 42 that communicates with the suction port of the pump unit 10C. A seal ring 44 is attached to the outer periphery of the distal end of the discharge port 40.

  A housing 46 constituting the drive control unit 10B is fixed to the motor housing portion 24 side of the pump housing 20, and a housing cover 48 is fixed so as to seal a control board provided in the housing 46. Yes.

  The drive control unit 10B is made of a synthetic resin that covers a casing 46 made of synthetic resin fixed to the pump housing 20 and a terminal forming body (not shown) that is molded and accommodated integrally in the casing 46. The housing cover 48 and the housing cover 48 are used.

  In the space formed by the housing 46 and the housing cover 48, the input terminal forming body and the neutral terminal forming body and the end portion of the winding 18A wound around the stator portion 18 of the electric motor portion 10A are fusing processed. Connected by. A connector portion 50 is formed integrally with the housing 46, and a part of the terminal forming body is exposed to the connector portion 50 and connected to an external power source (not shown).

  In the electric oil pump 10, the winding start end portion and the winding end end portion of the winding 18 </ b> A wound around the stator portion 18 constituting the electric motor portion 10 </ b> A are fixed adjacent to the electric motor portion storage portion 24. The input terminal forming body and the neutral terminal forming body embedded in the housing 46 are connected through an insertion hole provided in the housing 46. Therefore, a drive control signal from the control board is supplied to the winding 18A through the input terminal forming body to rotate the rotor portion 16 of the electric motor portion 10A, and finally rotate the pump rotor 12 to perform the pump action. It is what.

  The electric oil pump 10 combined with such an automatic transmission is used in the range of about −40 to + 140 ° C. from the viewpoint of the use environment of the automobile as described above. For this reason, in a use environment where the temperature is extremely low, such as in a cold region or in winter, the viscosity of the working oil increases and the rotational resistance of the pump rotor 12 increases, making it difficult for the pump rotor 12 to perform the pumping action. In order to rotate the pump rotor 12 against the rotational resistance, it is necessary to increase the power supplied to the motor unit 10A.

  When the electric power supplied to the electric motor unit 10A is increased, the amount of heat generated by the winding 18A wound around the iron core 18B of the stator unit 18 of the electric motor unit 10A increases, and the electric motor efficiency decreases. Therefore, if the heat generated in the winding wound around the iron core 18B of the stator portion 18 is released as much as possible, it is possible to suppress a reduction in the motor efficiency due to the heat of the motor.

  However, in the conventional electric oil pump as disclosed in Patent Document 1, the iron core 18B around which the winding 18A is wound has an air gap on the inner peripheral surface of the motor housing portion 24 of the pump housing 20 that houses the stator portion 18. The stator portion 18 is fixed to the pump housing 20 by a fixing screw. For this reason, it becomes the structure where an air layer with high heat insulation exists in a stator part and an inner peripheral surface of a pump housing. For this reason, since the heat generated in the winding 18A is transmitted to the pump housing 20 via the iron core 18B of the stator portion 18 and the air layer, the ratio of heat flowing from the iron core 18B of the stator portion 18 to the pump housing 20 is reduced. The temperature of the stator portion 18 composed of the winding 18A and the iron core 18B rises.

  And in order to reduce the temperature rise of such an electric motor part 10A, this embodiment is characterized by adopting the following configuration.

  In the present embodiment, the outer diameter of the iron core 18B of the stator portion 18 is formed slightly larger than the inner diameter of the motor housing portion 24 of the pump housing, and the stator portion 18 is housed and fixed in the motor housing portion 24 by shrink fitting. Is. Therefore, as shown in FIG. 3, the outer peripheral wall of the iron core 18 </ b> B of the stator portion 18 is fixed to the inner peripheral wall of the motor housing portion 24 of the pump housing 20 in a press-fitted form.

  That is, since the pump housing 20 is made of an aluminum alloy, it has a high rate of expansion due to heat. In this embodiment, the heat treatment of the pump housing 20 expands the inner circumference of the electric motor housing portion 24 to the outside and increases the inner circumference diameter. In this state, the normal temperature stator portion 18 is housed in the motor housing portion 24, and when the temperature of the pump housing 20 is lowered, the pump housing 20 contracts and returns to its original shape. 24 is firmly fixed.

  Therefore, the inner peripheral surface of the motor housing portion 24 of the pump housing 20 and the outer peripheral surface of the iron core 18B of the stator portion 18 are brought into metal contact so as to press each other. For this reason, the heat generated in the winding 18 </ b> A is transmitted to the iron core 18 </ b> B of the stator portion 18, and the heat from the iron core 18 </ b> B is directly and efficiently transmitted to the motor housing portion 24 of the pump housing 20.

  The space formed by the inner peripheral surface of the pump housing portion 26 </ b> A and the outer peripheral surface of the pump housing 20 of the electric oil pump 10 is filled with working oil. Accordingly, although the heat of the winding 18A transmitted to the pump housing 20 increases the temperature of the housing 20, the working oil is in thermal contact with the outer peripheral surface of the pump housing 20 and takes heat away from the outer peripheral surface of the pump housing 20. Thus, the motor unit 10A can be efficiently cooled. As a result, since the heat generated in the winding of the electric motor unit 10A flows directly from the stator unit 18 to the pump housing 20, the heat of the winding can be efficiently released to the working oil, and the efficiency of the electric oil pump is improved. It is something that can be done.

  Here, the shrink-fit fixing strength of the iron core 18B of the stator portion 18 and the motor housing portion 24 of the pump housing 20 is set to a value larger than the maximum generated torque generated in the motor portion 10A. This is because if the shrink-fit fixing strength is smaller than the maximum generated torque of the motor unit 10A, the stator unit 18 may rotate. For this reason, in this embodiment, the shrink-fit fixing strength is determined to be larger than the maximum generated torque generated in the electric motor unit 10A, and specifically, set to about 6 to 10 times.

  When the shrinkage fixing strength is not large, an anti-rotation mechanism in the axial direction, for example, a concave and convex anti-rotation mechanism extending in the axial direction, is provided between the inner peripheral wall of the motor housing 24 and the outer peripheral wall of the iron core 18B. Can do. According to this, since it is not necessary to increase the shrink-fitting fixing strength, the thickness of the pump housing 20 can be reduced, and the outer shape of the electric oil pump 10 can be reduced.

  Further, in the conventional electric oil pump as disclosed in Patent Document 1, the stator portion 18 is assembled with the electric motor housing portion 24 in such a configuration that there is a predetermined gap. There is a problem that the outer diameter of the electric motor storage section 24 is increased. On the other hand, in the present embodiment, the outer peripheral wall of the iron core 18B of the stator portion 18 and the inner peripheral wall of the motor housing portion 24 are fixed in close contact with each other, so that the outer diameter of the motor housing portion 24 of the pump housing 20 can be reduced. Miniaturization of the electric oil pump 10 can be promoted.

  Furthermore, in the conventional electric oil pump as disclosed in Patent Document 1, since the stator portion 18 is assembled to the pump housing 20 by a fixing means such as a fixing bolt, the number of parts is increased by this amount and the product cost is increased. Alternatively, there is a problem that the weight increases as the number of parts increases. On the other hand, in this embodiment, the outer peripheral wall of the iron core 18B of the stator portion 18 and the inner peripheral wall of the motor housing portion 24 are fixed by shrinkage fitting, so that fixing means such as fixing bolts can be omitted, thereby reducing the product cost. Or the weight can be reduced.

  As described above, according to the present invention, the outer peripheral surface of the stator portion is fixed to the inner peripheral surface of the pump housing of the electric oil pump by shrink fitting so that the inner peripheral surface of the pump housing and the outer peripheral surface of the stator portion are pressed against each other. In this way, the metal is brought into contact, and the heat generated in the winding is directly transmitted from the stator portion to the pump housing so as to be released to the working oil flowing through the pump housing portion provided in the automatic transmission main body. According to this, since the heat generated in the winding flows directly from the stator portion to the pump housing, the heat of the winding can be efficiently released to the working oil, and the efficiency of the electric oil pump can be improved.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  DESCRIPTION OF SYMBOLS 10 ... Electric oil pump, 12 ... Pump rotor, 14 ... Outer rotor, 16 ... Rotor part, 18 ... Stator part, 20 ... Pump housing, 22 ... Pump accommodating part, 24 ... Electric motor part accommodating part, 28 ... Drive rotating shaft, 30 DESCRIPTION OF SYMBOLS ... Bearing part, 33 ... Partition, 34 ... Oil introduction passage, 38 ... Pump cover, 40 ... Discharge port, 42 ... Suction port, 44 ... Housing, 48 ... Housing cover.

Claims (6)

A rotor part comprising a pump part composed of a pump rotor and an outer rotor housed in a pump part housing part formed in a metal pump housing, and a permanent magnet housed in an electric motor housing part formed in the pump housing And an electric motor part composed of a stator part including an iron core and a winding, a driving rotary shaft that couples the pump rotor and the rotor part, a discharge port and a suction port communicated with the pump part, and the pump part In the electric oil pump that is composed of a pump cover fixed to the pump housing so as to cover, and is combined with an automatic transmission that rotates the rotor portion and drives the pump portion,
By fixing the inner peripheral wall of the motor housing part of the pump housing and the outer peripheral wall of the iron core of the stator part by shrinkage fitting, the inner peripheral wall of the pump housing and the outer peripheral wall of the stator part core are pressed against each other. The metal is made to contact each other and heat from the iron core is directly transmitted to the pump housing,
Further, the pump housing is housed in a pump housing portion formed in the casing of the automatic transmission, and working oil flows into the space between the outer peripheral surface of the pump housing and the inner peripheral surface of the pump housing portion, and An electric oil pump combined with an automatic transmission characterized in that heat from an iron core is taken through the pump housing. In the electric oil pump combined with the automatic transmission according to claim 1,
The pump housing is made of an aluminum alloy, the outer diameter of the stator core of the stator portion is formed larger than the inner diameter of the motor housing portion of the pump housing, and the pump housing is heated to heat the motor. The stator portion at room temperature is accommodated in the electric motor accommodating portion with the inner peripheral diameter of the accommodating portion being expanded outwardly and the inner peripheral diameter being increased, and the inside of the electric motor accommodating portion of the pump housing is reduced by a decrease in temperature of the pump housing. An electric oil pump combined with an automatic transmission, wherein a peripheral wall and an outer peripheral wall of the iron core of the stator portion are fixed. In the electric oil pump combined with the automatic transmission according to claim 1 or 2,
Combined with the automatic transmission, the shrinkage fit strength between the inner peripheral wall of the motor housing portion of the pump housing and the outer peripheral wall of the iron core of the stator portion is larger than the maximum generated torque of the electric motor. Electric oil pump. In the electric oil pump combined with the automatic transmission according to claim 3,
The shrinkage fixing strength between the inner peripheral wall of the motor housing portion of the pump housing and the outer peripheral wall of the iron core of the stator portion is about 6 to 10 times the maximum generated torque of the motor. Electric oil pump combined with the automatic transmission featured. In the electric oil pump combined with the automatic transmission according to claim 1 or 2,
An electric oil pump combined with an automatic transmission, wherein an anti-rotation mechanism is formed between an inner peripheral wall of the motor housing portion of the pump housing and an outer peripheral wall of the iron core of the stator portion. In the electric oil pump combined with the automatic transmission according to claim 5,
The anti-rotation mechanism is a concave-convex anti-rotation mechanism formed in the axial direction of the inner peripheral wall of the motor housing portion of the pump housing and the outer peripheral wall of the iron core of the stator portion. Electric oil pump.

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