JP2024007117A - motor unit - Google Patents

Abstract

To provide a technique of estimating a temperature of a rotor with high accuracy.SOLUTION: A motor unit may comprise: a motor having a brush, a rotor having a magnetic wiring to which a power is supplied via the brush, and a coolant path where a coolant for cooling the rotor passes; a first temperature sensor that detects a temperature of the brush; a second temperature sensor that detects a temperature of the coolant after the rotor is cooled; and an estimation part that estimates a temperature of the rotor by using the temperature of the brush detected by the first temperature sensor, a temperature of the coolant detected by the second temperature sensor, and an atmospheric temperature at a circumference of the motor.SELECTED DRAWING: Figure 1

Description

The technology disclosed in this specification relates to a motor unit.

Patent Document 1 discloses a brush motor that includes a brush that supplies power to a rotor, a brush holder that supplies power from the outside to the brush via a power line, and a temperature sensor that is attached to the brush holder. There is.

Japanese Patent Application Publication No. 2004-015989

In order to suppress the temperature rise of the rotor, a configuration in which the rotor is cooled using a refrigerant may be adopted. With this configuration, it is difficult to estimate the temperature of the rotor using the temperature detected by the temperature sensor attached to the brush holder. This specification provides a technique that can accurately estimate the temperature of a rotor.

The technology disclosed herein relates to a motor unit. The motor unit includes a motor including a brush, a rotor having a field winding that is supplied with power through the brush, a refrigerant passage through which a refrigerant for cooling the rotor passes, and a first temperature sensor that detects the temperature of the brush. , a second temperature sensor that detects the temperature of the refrigerant after cooling the rotor, the temperature of the brush detected by the first temperature sensor, the temperature of the refrigerant detected by the second temperature sensor, and the temperature around the motor. The method may include an estimating section that estimates the temperature of the rotor using the ambient temperature.

According to this configuration, by using the temperature of the refrigerant and the ambient temperature around the motor in addition to the temperature of the brushes, the temperature of the rotor can be accurately estimated without directly detecting the temperature of the rotor.

A schematic diagram of a vertical cross section of the motor is shown. A block diagram of the motor unit is shown.

As shown in FIG. 1, the motor 10 is mounted on, for example, a vehicle and used for driving the vehicle. The motor 10 includes a housing 12, a rotor 20, a stator 18, brushes 26, 28, and a refrigerant pipe 14 housed in the housing 12. The rotor 20 includes a shaft 22 rotatably supported by a housing 12 via two bearings 16, 16 around a rotation axis X, and a plurality of fields arranged at intervals in the rotational direction of the shaft 22. A magnetic winding 24 is provided. The number of field windings 24 is not particularly limited.

A stator 18 is disposed on the outside of the rotor 20 and faces the outer periphery of the rotor 20 with a gap therebetween. Note that in FIG. 1, the internal configurations of the rotor 20 and stator 18 are not shown. Stator 18 is fixed to housing 12.

The field winding 24 of the rotor 20 is supplied with DC power from a battery mounted on the vehicle via brushes 26 and 28 and slip rings 27 and 29 attached to the shaft 22. As a result, a magnetic field is generated in the field winding 24, and the rotor 20 rotates. Each of the brushes 26, 28 is biased toward each of the slip rings 27, 29 by a resilient member to maintain contact with each of the slip rings 27, 29.

A refrigerant pipe 14 is arranged within the housing 12 . The refrigerant pipe 14 is formed with a refrigerant passage through which refrigerant supplied from outside the housing 12 flows. A plurality of openings 14a are arranged in the refrigerant pipe 14.

The refrigerant passes through any one of the plurality of openings 14a and flows out as shown by the arrow. As a result, the refrigerant flows downward and accumulates at the lower end of the housing 12 while cooling the rotor 20. The refrigerant 40 accumulated at the lower end of the housing 12 is discharged to the outside of the housing 12. The refrigerant is, for example, ATF (Automatic Transmission Fluid).

As shown in FIG. 2, the motor unit 2 includes a control device 50 and temperature sensors 30 and 32 in addition to the motor 10. Temperature sensor 30 is disposed within housing 12 close to brush 26 and detects the temperature of brush 26 . Note that in a configuration in which a holder holding the brush 26 is disposed, the temperature sensor 30 may be disposed close to the holder. Alternatively, the temperature sensor 30 may be placed proximate the brush 28 or the holder of the brush 28. The temperature sensor 32 is arranged so as to be in contact with the refrigerant 40 collected at the lower end of the housing 12, and detects the temperature of the refrigerant after the rotor 20 has been cooled. The temperature sensors 30 and 32 supply the detected temperatures of the brush 26 and the refrigerant to the control device 50. In a variation, the refrigerant may cool the rotor 20 by passing at or near the shaft 22 of the rotor 20. In this case, the temperature sensor 32 may be placed at a position where it can detect the temperature of the refrigerant 40 after the rotor 20 has been cooled.

The control device 50 includes a CPU, memory, and the like. The control device 50 controls the motor 10 by the CPU executing processing according to a computer program stored in a memory. The control device 50 controls the motor 10 according to commands (eg, required torque, etc.) from the main control unit 4 of the vehicle. The control device 50 is communicably connected to the temperature sensors 30 and 32. The control device 50 is further communicably connected to a temperature sensor 6 that detects the ambient temperature around the motor 10 mounted on the vehicle. The control device 50 acquires the ambient temperature detected by the temperature sensor 6.

The memory of the control device 50 stores in advance a data map for estimating the temperature of the rotor 20 from three temperatures: the temperature of the brush 26, the temperature of the refrigerant, and the ambient temperature. The data map is specified in advance through experiments and simulations and is stored in memory. Note that instead of the data map, the memory stores a function representing the relationship between the temperature of the brush 26, the temperature of the refrigerant, the ambient temperature, and the temperature of the rotor 20, which has been specified in advance through experiments and simulations. You can. The function may be, for example, a coefficient derived from the temperature of the rotor 20 = the temperature of the brush 26 × the temperature of the refrigerant × the coefficient derived from the ambient temperature.

The memory of the control device 50 may further store a temperature threshold value in advance. The temperature threshold is the upper limit temperature of the heat resistance of the rotor 20, and is determined using the heat resistance temperature of the components of the rotor 20 at a temperature that does not make the rotor 20 unusable or below a temperature that does not accelerate deterioration of the rotor 20 due to heat. has been done.

While the motor 10 is driving, the control device 50 repeatedly checks the temperature of the brush 26, the temperature of the refrigerant, and the ambient temperature acquired from the temperature sensors 6, 30, and 32, and the data map stored in the memory. is used to estimate the temperature of the rotor 20. The control device 50 limits the output of the motor 10 when the estimated temperature of the rotor 20 is equal to or higher than a predetermined upper limit temperature. For example, controller 50 limits the output of motor 10 to a torque that is predetermined and stored in memory. In this case, the control device 50 sends a notification to the main control unit 4 that the output of the motor 10 is being restricted. The main control unit 4 may notify the vehicle occupant that the output of the motor 10 is limited (for example, by displaying on an indicator or outputting audio).

In the motor unit 2, the temperature of the rotor 20 is estimated using the temperature of the brush 26, the temperature of the refrigerant, and the ambient temperature. can be improved.

When the accuracy of estimating the temperature of the rotor 20 is improved, it is not necessary to take a large margin for limiting the output of the motor 10 in anticipation of an estimation error. Thereby, the frequency of output restriction of the motor 10 can be reduced. The potential performance of the motor 10 can be appropriately exhibited.

Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The techniques described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims as filed. Furthermore, the techniques illustrated in this specification or the drawings can achieve multiple objectives simultaneously, and achieving one of the objectives has technical utility in itself.

2: Motor unit, 6, 30, 32: Temperature sensor, 10: Motor, 12: Housing, 14: Refrigerant pipe, 18: Stator, 20: Rotor, 22: Shaft, 24: Field winding, 26, 28: Brush, 40: Refrigerant, 50: Control device

Claims (1)

A motor unit,
A motor comprising a brush, a rotor having a field winding supplied with power through the brush, and a refrigerant passage through which a refrigerant for cooling the rotor passes;
a first temperature sensor that detects the temperature of the brush;
a second temperature sensor that detects the temperature of the refrigerant after cooling the rotor;
The temperature of the rotor is determined using the temperature of the brush detected by the first temperature sensor, the temperature of the refrigerant detected by the second temperature sensor, and the ambient temperature around the motor. A motor unit comprising: an estimating section that performs estimating.

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