JP2012031832A - Electric pump unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric pump unit that controls an oil pressure without adding a hydraulic pump.SOLUTION: The electric pump unit 1 includes: a pump 3 which inhales and discharges oil; an electric motor 4 for pump driving; and a motor control device 5 which has a drive circuit for PWM-driving the electric motor 4 on the basis of the oil pressure. The motor control device 5 calculates the oil pressure on the basis of an input current and a voltage PWM duty of the drive circuit and an oil temperature.

Description

  The present invention relates to an electric pump unit used in, for example, a hydraulic pressure supply device in an automobile.

  Conventionally, as a hydraulic pressure supply apparatus in an automobile, an apparatus having only a main pump driven by an engine as a main power source has been used.

  However, when an idle stop function is provided that stops the engine when the vehicle is stopped, the conventional main pump and battery are connected to ensure the supply of hydraulic pressure to the drive system such as the transmission even when the engine is stopped due to the idle stop. Two hydraulic sources are required, with an auxiliary pump driven by an electric motor as a power source.

  As a hydraulic pressure supply device for an automobile provided with such two hydraulic pressure sources, the one shown in Patent Document 1 is known.

  This hydraulic pressure supply device supplies hydraulic pressure to the transmission, and the auxiliary pump constitutes an electric pump unit together with an electric motor and a motor control device for driving the auxiliary pump.

  When the engine is driven and the oil pressure in the main discharge oil passage from the main pump to the transmission is greater than or equal to a predetermined value, the drive of the auxiliary pump is stopped, and when the oil pressure in the main discharge oil passage is less than the predetermined value, the auxiliary pump is stopped. The pump is driven.

  The detection of the hydraulic pressure in the main discharge oil passage is performed using a hydraulic pressure sensor provided in the main discharge oil passage.

Japanese Patent Laid-Open No. 2002-206634

  In the hydraulic pressure supply apparatus as described above, when the auxiliary pump is driven, it is necessary to control the hydraulic pressure within a predetermined range. For this purpose, it is conceivable to use a hydraulic pressure sensor provided in the main discharge oil passage.

  However, the hydraulic pressure supplied by the main pump is several tens of times larger than the hydraulic pressure supplied by the auxiliary pump. And since the measurement range of the hydraulic sensor is set according to the hydraulic pressure supplied by the main pump, if it is used for hydraulic control of the auxiliary pump, the measurement accuracy is not sufficient and the hydraulic control is not There are things you can't do well. In that case, it is necessary to add a hydraulic sensor with a low measurement range for the electric pump unit.

  An object of the present invention is to solve the above problems and provide an electric pump unit capable of hydraulic control without adding a hydraulic pump.

  An electric pump unit according to the present invention includes a pump that sucks and discharges oil, an electric motor for driving a pump, and a motor control device that has a drive circuit that PWM-drives the electric motor based on hydraulic pressure. The apparatus is characterized in that the hydraulic pressure is obtained based on the input current of the drive circuit, the voltage PWM duty, and the oil temperature.

  For example, the motor control device obtains the load torque of the electric motor from the input current of the drive circuit and the voltage PWM duty, and obtains the hydraulic pressure from the load torque and the oil temperature.

  The load torque of the electric motor has a certain relationship with the hydraulic pressure and the oil temperature. Based on this relationship, the hydraulic pressure can be obtained from the load torque and the oil temperature. The load torque is balanced with the motor torque, and the motor torque corresponds to the motor current. The motor current has a fixed relationship with the input current of the drive circuit and the voltage PWM duty. Based on these relationships, the load torque can be obtained from the input current of the drive circuit and the voltage PWM duty. Therefore, the hydraulic pressure can be obtained based on the input current and voltage PWM duty of the drive circuit and the oil temperature. For this reason, it is possible to control the hydraulic pressure of the electric pump unit without adding a hydraulic pressure sensor.

  The oil temperature is detected by, for example, an oil temperature sensor. Further, without using the oil temperature sensor, the oil temperature can be obtained from other information, for example, the resistance value of the stator coil of the electric motor immersed in oil.

  According to the hydraulic pressure supply apparatus of the present invention, as described above, hydraulic pressure control can be performed without adding a hydraulic pressure sensor.

FIG. 1 is a schematic configuration diagram showing an embodiment in which the present invention is applied to a hydraulic pressure supply device for an automobile. FIG. 2 is a schematic configuration diagram showing an example of a motor control device of the electric pump unit of FIG.

  Embodiments in which the present invention is applied to a hydraulic pressure supply device for an automobile will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram illustrating an example of a hydraulic pressure supply device that supplies hydraulic pressure to a transmission of an automobile.

  In FIG. 1, the hydraulic pressure supply device is provided with an electric pump unit (1) for transmission. This electric pump unit (1) is used for auxiliary supply of hydraulic pressure that decreases during idle stop in the transmission (2) of an automobile, and includes a pump (3) that is an auxiliary pump for hydraulic supply, and a pump An electric drive motor (4) and a motor control device (controller) (5) for controlling the motor (4) are provided.

  Although detailed description is omitted, in this example, the motor (4) is a sensorless control brushless DC motor, and the auxiliary pump (3) is an internal gear pump.

  Preferably, the pump (3) and the motor (4) are integrally provided in a common housing. The motor control device may also be provided in a common housing with the pump (3) and the motor (4).

  In addition to the electric pump unit (1) having the auxiliary pump (3), the hydraulic pressure supply device is provided with a main pump (7) driven by the engine (6).

  The oil suction port (8) of the main pump (7) is connected to the oil pan (9), and the oil discharge port (10) is connected to the transmission (2) via the main discharge oil passage (11). The oil suction port (12) of the auxiliary pump (3) is connected to the oil pan (9), and the oil discharge port (13) is connected to the main discharge oil passage (11) via the auxiliary discharge oil passage (14). Yes. The auxiliary discharge oil passage (14) is provided with a check valve (15) that prevents backflow of oil from the main discharge oil passage (11) side to the auxiliary pump (3). The main discharge oil passage (11) is provided with a hydraulic pressure sensor (16) and an oil temperature sensor (17).

  Connected to the motor control device (5) are a battery (18) as a DC power source and an ECU (19) as a computer for controlling the engine (6) and the transmission (2). The ECU (19) monitors the oil pressure in the main discharge oil passage (11) from the output of the oil pressure sensor (16). When the oil pressure is higher than the preset value, the auxiliary pump stop signal is given. The pump drive signal is output to the motor control device (5).

  When the auxiliary pump stop signal is output from the ECU (19), the motor control device (5) stops driving the motor (4), stops driving the auxiliary pump (3), and drives the auxiliary pump. When the signal is output, the motor (4) is driven to drive the auxiliary pump (3).

  When the engine (6) is driven, the main pump (7) is driven by this, and normally the hydraulic pressure in the main discharge oil passage (11) is higher than the set value, and the auxiliary pump (3) stops driving. is doing. At this time, oil is supplied from the main pump (7) to the transmission (2) via the main discharge oil passage (11). The check valve (15) prevents the backflow of oil from the main discharge oil passage (11) to the auxiliary pump (3).

  When the engine (6) is stopped, the oil pressure in the main discharge oil passage (11) is generally zero and less than the set value, and the auxiliary pump (3) is driven. Thus, oil is supplied from the auxiliary pump (3) to the transmission (2) through the auxiliary discharge oil passage (14) and the main discharge oil passage (11).

  Even if the engine (6) is driven, if the oil pressure in the main discharge oil passage (11) is less than the set value, the auxiliary pump (3) is driven, and the auxiliary pump (3) to the auxiliary discharge oil passage (14) Oil is supplied to the main discharge oil passage (11) through the.

  When the auxiliary pump (3) is driven, hydraulic control as described later is performed.

  FIG. 2 is a schematic configuration diagram showing one specific example of the motor control device (5).

  The motor control device (5) uses a battery (18) to drive the motor (4) by the one-side PWM method, and drives the motor (4) by a drive circuit (inverter) (20), a drive circuit ( An energization control unit (21) for controlling 20) and a current detection circuit (22) for detecting an input voltage of the drive circuit (20) are provided.

  The drive circuit (20) is a switching circuit including a plurality of switching elements (not shown) for controlling energization from the battery (18) to the motor (4). The energization control unit (21) includes a CPU (not shown), estimates the rotational position of the rotor (not shown) of the motor (4) from the phase voltage of each phase of the motor (4), and based on the estimated position, the PWM method Each switching element of the drive circuit (20) is controlled, and thereby energization to the motor (4) is controlled. The current detection circuit (22) detects the input voltage I1 of the drive circuit (20), and its output is input to the energization control unit (21). The DC voltage V1 of the battery (18) is applied to the drive circuit (20) and the energization control unit (21), and this becomes the input voltage of the drive circuit (20). Further, the output of the oil temperature sensor (17) is input to the energization control unit (21). Let T be the oil temperature detected by the oil temperature sensor (17). Since the drive circuit (20), the energization control unit (21), and the current detection circuit (22) can take a known appropriate configuration, detailed description thereof is omitted.

  The energization control unit (21) is based on the input current I1 and voltage PWM duty V2 of the drive circuit (20) detected by the current detection circuit (22) and the oil temperature T detected by the oil temperature sensor (17). The hydraulic pressure is obtained, and the motor (4) is controlled so that the hydraulic pressure falls within a predetermined setting range. For example, the load torque of the motor (4) is obtained from the input current I1 of the drive circuit (20) and the voltage PWM duty V2, and the oil pressure is obtained from the load torque and the oil temperature T.

  The load torque of the motor (4) has a certain relationship with the hydraulic pressure and the oil temperature T. Based on this relationship, the hydraulic pressure can be obtained from the load torque and the oil temperature T. The load torque is balanced with the motor torque, and the motor torque corresponds to the motor current I2. The motor current I2 has a fixed relationship with the input current I1 and the voltage PWM duty V2 of the drive circuit (20). Based on these relationships, the load torque can be obtained from the input current I1 and the voltage PWM duty V2 of the drive circuit (20). Accordingly, the hydraulic pressure can be obtained based on the input current I1, voltage PWM duty V2 and oil temperature T of the drive circuit (20). For this reason, hydraulic control of the electric pump unit (1) can be performed without adding a hydraulic pressure sensor to the electric pump unit (1).

  The following relationship exists between the input voltage V1 and the input current I1, and the motor current I2 and the voltage PWM duty V2 of the drive circuit (20).

V1 x I1 = (V2 x I2) x φ (100)
Here, φ is the conversion efficiency.

  From equation (100), I2 is as follows.

I2 = (V1 × I1) / (V2 × φ) (101)
The input voltage V1 is a DC voltage of the battery (18) and is constant. The voltage PWM duty V2 is a value generated in the energization control unit (21). Therefore, the motor current I2 is obtained from the input current I1 and the conversion efficiency φ. The conversion efficiency φ is a constant determined by the motor (4) and varies depending on the rotational speed of the motor (4). However, since the change is small, the motor current I2 can be obtained from the input current I1 with the conversion efficiency φ being constant. It is also possible to store the relationship between the conversion efficiency φ and the rotation speed in a table, obtain the conversion efficiency φ from the rotation speed at that time, and obtain the motor current I2 from the conversion efficiency φ and the input current I1. . The load torque is proportional to the motor torque, and the motor torque is proportional to the motor current I2. Therefore, the load torque is obtained from the motor current I2. Then, the oil pressure can be obtained from the load torque and the oil temperature T by a calculation formula or from a table storing the relationship between the load torque and the oil temperature T and the oil pressure. Furthermore, the hydraulic pressure can be obtained from the detected input current I1, the input voltage V1, the voltage PWM duty V2, and the conversion efficiency φ.

  In the above embodiment, the oil temperature is detected by the oil temperature sensor (17), but the oil temperature may be obtained from other information without using the oil temperature sensor. For example, the oil temperature can be obtained from the resistance value of the stator coil of the motor (4) immersed in oil. The resistance value of the stator coil can be obtained from the change in the input voltage I1 when the motor (4) is started. Since the resistance value of the stator coil varies depending on the temperature (oil temperature), the oil temperature can be obtained from the resistance value. In this case, for example, an electric pump assembly in which the auxiliary pump (3) and the motor (4) are integrated is housed in a recess formed in the transmission housing, and oil is introduced into the recess to pump (3) and The motor (4) is immersed in oil, and this oil is sucked from the oil suction port (12) of the pump (3).

  In the above embodiment, the auxiliary pump (3) is switched between driving and stopping based on the hydraulic pressure of the main discharge oil passage (11), but when the engine (6) is driven, the auxiliary pump (3) can be stopped, and the auxiliary pump (3) can be driven when the engine (6) is stopped.

  The configuration of the electric pump unit (1) is not limited to that of the above embodiment, and can be changed as appropriate.

  The present invention can also be applied to devices other than automobile hydraulic pressure supply devices.

(3) Auxiliary pump
(4) Electric motor
(5) Motor controller
(20) Drive circuit

Claims (2)

A pump for sucking and discharging oil, an electric motor for driving the pump, and a motor control device having a drive circuit for PWM driving the electric motor based on hydraulic pressure,
An electric pump unit characterized in that the motor control device obtains a hydraulic pressure based on an input current of a drive circuit, a voltage PWM duty, and an oil temperature.   2. The electric pump unit according to claim 1, wherein the motor control unit obtains the load torque of the electric motor from the input current of the drive circuit and the voltage PWM duty, and obtains the hydraulic pressure from the load torque and the oil temperature.

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