JP2004015989A - Brush motor for vehicle drive unit and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that it is difficult to protect the temperature of a motor in all conditions only by measuring the temperature of a brush, since a condition may arise that a high output is required in a short time in a vehicle drive unit, while the brush often becomes highest in temperature when the operation of the brush is continued or repeated. <P>SOLUTION: A brush motor for the vehicle drive unit is configured such that either of a front wheel or a rear wheel of a vehicle is driven by an engine, and the other is driven by a motor. The brush motor comprises the brush that feeds power to a rotor of the brush motor for the vehicle drive unit, and a brush holder that connects power from the outside to the brush via a power line. A temperature sensor for measuring the temperature of the motor is installed to the brush holder. The brush motor also comprises a first overtemperature protecting logic that restricts a motor input by combining an energizing current value and an energizing time, and a second overtemperature protecting logic that restricts the motor input by detecting an output signal from the temperature sensor. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vehicle drive device in which one of front and rear wheels is driven by an engine and the other is driven by a brush motor, and more particularly to a brush motor for a vehicle drive device having functions and a control method thereof.
[0002]
[Prior art]
2. Description of the Related Art Various types of electric motors with a reduction gear, such as a drive device of a four-wheel drive vehicle and a starter that drives an engine at the time of starting, are incorporated in an automobile. For example, in a four-wheel drive vehicle in which the front wheels of a vehicle are driven by an engine and the rear wheels are driven by a dedicated generator or a DC motor directly driven by energy from a battery, the driving force of the rear wheels is increased at the time of starting. It has a function of assisting the starting force, and is particularly suitable for starting assist on a low μ road such as a snowy road or a frozen road, starting assist on a stepped or rutted road, or continuous climbing operation on a low μ road. A motor drive device used in a vehicle drive device in which one of the front and rear wheels is driven by an engine and the other is driven by a motor is described in, for example, JP-A-2000-318473.
[0003]
On the other hand, high output is often used in a short period of time in a vehicle drive system in which one of the front and rear wheels is driven by an engine and the other is driven by a motor. become. Therefore, in order to protect the motor from over-temperature, it is necessary to install a motor protection temperature sensor near the heat source.
[0004]
If the motor is overloaded for some reason, such as the condition of the road surface, the coil and the like of the motor will generate heat above the set temperature. As a motor protection device, for example, the following motor protection devices (1), (2) and (3) are employed.
{Circle around (1)} A protection device for a motor, in which a thermosensitive element is provided in a field coil to turn off the power of the motor when a predetermined temperature is reached,
(2) A brush connected to a power supply is brought into contact with a commutator attached to a rotating shaft, a bimetal switch is provided in proximity to the brush, and when the temperature of the brush reaches a predetermined value or more is detected by the bimetal switch. In the electric motor configured to cut off the power, the plurality of brush holding frames of the substrate of the brush holder are fixed by caulking, and the brush is held by each brush holding frame. A motor protection device having a bimetal switch or a heat-sensitive element fixed to the outside (for example, Japanese Utility Model Application Laid-Open No. 60-11654,
No. 26253),
{Circle around (3)} As a mounting structure of a temperature sensor (thermistor) for protecting the motor, there is a method of inserting a thermistor into a through hole of a brush holter and fixing the same (for example, Japanese Patent Application Laid-Open No. H11-299177). There is also a method of measuring the brush heat with a copper brush lead wire having high thermal conductivity as a measurement point of the brush temperature (for example, Japanese Patent Application Laid-Open No. H10-86831).
[0005]
[Problems to be solved by the invention]
In the case of embedding the heat-sensitive element inside the field coil as described in (1) above, the assembling of the heat-sensitive element is troublesome, so that the workability at the time of assembling the motor is poor and the size of the heat-sensitive element is limited. For this reason, it is conceivable to mount the heat-sensitive element on the surface of the field coil.However, since the field coil is wound, the dimensions of the field coil vary depending on the product, and the field coil is mounted at a predetermined position on all line products without variation. Is difficult. Further, when the heat-sensitive element is attached to the yoke supporting the field coil, the yoke is in contact with the outside air, and the heat radiation is good, so that accurate heat information cannot be obtained and the protection function may be impaired.
[0006]
Further, when used as a drive device for a vehicle, the motor protection device of (2) shuts off the connection between the motor and the input power source, and the motor does not generate a driving force, but the rotor of the motor is rotated by an external force including the wheels. At this time, since the brush and the commutator are in contact with each other, the brush temperature further rises due to friction between the brush and the commutator, or the speed of the temperature decrease becomes slow, resulting in an over-protection mechanism. In addition, since the condition of being turned by an external force extends for a long time, it leads to abrasion of the brush. In addition, when the input power is cut off as a switch, the output of the motor is suddenly lost, thereby causing a drastic change in vehicle drivability.
[0007]
In addition, the motor for the vehicle driving device is used for starting assistance, so that it has a high output and a short driving time. Therefore, since the temperature of the motor rises transiently, if the mounting position of the temperature sensor is away from the portion that is the heat source, the sensitivity to the actual heat temperature becomes dull.
[0008]
Therefore, in the method of (3), in which the brush holder is provided with a through hole and a thermistor is inserted into the through hole of the brush holder and fixed, the brush is separated from the brush which is a heat source when the brush is used as a heat source. Sensitivity of temperature becomes dull. Similarly, in the method of attaching a temperature sensor to the end of the brush lead wire, the sensitivity to the brush temperature is reduced by separating from the brush.
[0009]
Furthermore, in order to measure the temperature of the brush, which is the heat generating part of the motor, a method of embedding the temperature sensor in the brush or fixing it to the brush lead wire with an adhesive or the like, the workability of mounting the temperature sensor is poor. The accuracy of the measured temperature was poor due to variations in the location.
[0010]
Further, as described above, since this motor is used for starting assistance, a high output is required in a short time. At the time of continuous operation, it is possible to regulate the temperature at which the motor is protected by measuring the temperature of the brush.However, when a large current is supplied in a short time, it is difficult to instantaneously detect the motor temperature without a response delay. The parts which need to be protected are not only the vicinity of the brush but also the windings and varnish of the rotor. Therefore, if the motor operation time is defined only by the current value and the current supply time, it is difficult to grasp the current temperature of the motor in a repetitive state, and furthermore, it is necessary to consider many operation patterns. .
[0011]
Further, if the input to the motor is momentarily interrupted only by the time regulation, a sudden change in the motor driving force is added during the running of the vehicle, which leads to a sudden change in the vehicle driveability.
[0012]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a brush motor for a vehicle drive device and a control method thereof that can protect against transient heat generation or heat generation during continuous operation.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a brush motor for a vehicle drive device in which one of a front wheel and a rear wheel of a vehicle is driven by an engine, and the other is driven by a motor. And a brush holder for connecting external power to the brush via a power line, and a temperature sensor for measuring motor temperature is attached to the brush holder. By limiting the motor input based on the value detected by the temperature sensor, the brush motor for a vehicle drive device can be protected from transient heat generation or heat generation during continuous operation.
[0014]
Also provided is a first over-temperature protection logic that limits the motor input by a combination of the energizing current value and the energizing time, and a second over-temperature protection logic that detects the output signal from the temperature sensor and limits the motor input. Things. The motor heat generation is limited to the instantaneous power supply by the first over-temperature protection logic, and the heat generation due to continuous energization or repeated energization is limited by the second over-temperature protection logic, so that transient heat generation or continuous heat generation is achieved. The brush motor for a vehicle drive device can be protected from heat generated during operation.
[0015]
Further, the input power to the motor is gently limited before the temperature of the motor becomes excessive, the motor output is gently reduced, and control is performed so as not to cause a drastic change in the driveability of the vehicle.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention applied to a drive device of a four-wheel drive vehicle will be described with reference to the drawings.
[0017]
FIG. 1 is a diagram illustrating the overall structure of the vehicle drive device. The front wheel 3 of the four-wheel drive vehicle 1 is driven by the engine 2, and the rear wheel 4 is driven by a brushed DC motor 5 arranged near the front wheel 3. In the engine room, a first generator 7 for performing a normal charging and power generation system is belt-driven by the engine 2, and its output is stored in a battery 8. A second generator 9 which is similarly belt-driven by the engine 2 is disposed in the vicinity of the second generator 9. The second generator 9 is electrically connected to the electric motor 5 by a one-line electric power supply line 10 for driving the electric motor by body earth. Connected. Here, the generator 9 can be replaced with a battery for the purpose of driving the motor 5, and the battery 8 can be used as the battery. The electric motor 5 may be a two-wire type, instead of a one-wire type with a body ground. The brushed DC motor 5 is connected to the axle of the rear wheel 4 via a drive shaft 13 and a differential gear 12 integrally provided with a speed reducer and a clutch 11. When the clutch 11 is connected, the output shaft of the DC motor with brush 5 is connected to the differential gear 12 via the clutch 11. When the clutch 11 is disengaged, the brushed DC motor 5 is disconnected from the rear wheel 4 side. The brushed DC motor 5 can be easily switched between forward and reverse rotations. By using a DC shunt motor or a separately-excited DC motor capable of increasing and decreasing magnetism, switching between forward and backward traveling of the vehicle is easy, and the output of the motor can be improved. The possible range also expands. Reference numeral 14 denotes a motor drive controller including a microcomputer, which controls a signal for optimally controlling the output voltage of the second generator 9 based on a vehicle speed signal S and the like and an optimal armature current flowing into the brushed DC motor 5. To control the output of the second generator 9. A field current controlled by the motor drive controller 14 is supplied from the battery 8 to the field winding 29 of the brushed DC motor 5 through the field power supply line 20. A vehicle speed sensor 15 is provided near the front wheel 3 and the rear wheel 4 of the four-wheel drive vehicle 1. An ABS control unit 16 equipped with a microcomputer has a friction coefficient μ on the road surface based on the output of each vehicle speed sensor 15 and the like. Is calculated, and the ABS actuator 18 is operated such that a braking force corresponding to the value of μ is applied to the brake 17 (braking device) corresponding to each wheel. On the other hand, reference numeral 19 denotes an engine control unit which includes a microcomputer and controls the engine 2. Further, the clutch 11 receives the signal S from the vehicle speed sensor 15, generates an on / off signal calculated by a microprocessor or the like as necessary, and controls the connection / disconnection state. A temperature sensor line 21 extends from the brushed DC motor 5, and a signal t from a temperature sensor attached to the brushed DC motor 5 is transmitted to the motor drive controller 14.
[0018]
The current input to the motor is detected by the current sensor 6 and transmitted to the motor drive controller 14.
[0019]
FIG. 2 is a sectional view of the brushed DC motor 5 used in the drive device of the four-wheel drive vehicle shown in FIG. The casing of the electric motor 5 includes a yoke 22 and brackets 23 and 24 arranged on both sides of the yoke 22.
23 and 24 are integrated by tightening with a through bolt 25. The electric motor 5 is configured to insert a tightening bolt (not shown) into a bolt mounting hole 26 of the bracket 23 and fix the electric motor 5 at a desired position. An armature core 28 is provided on the rotating shaft 27, and a pole core 30 on which a field winding 29 is wound is fixed inside the yoke 22 by a bolt 31 which is passed through a bolt hole formed in the yoke 22 from outside. Have been. A commutator 34 is provided on the rotating shaft 27 on the bearing 33 side of the armature 32, and a brush 38 in a brush holder 39 is urged by a brush pressing spring 46 to contact the commutator 34.
[0020]
FIG. 3 is a detailed view of a screw-integrated thermistor 45 in which the thermistor 37 is enclosed in a threaded metal case 35. The screw integrated thermistor 45 is applied to a brush motor for a vehicle drive device as a temperature sensor. FIG. 4 is a structural view in which the screw integrated thermistor 4 shown in FIG. The brush holder 39 has a pillow base portion formed by pressing a single metal plate. Since the threaded hole is formed on the stand, and the screw is formed on the outside of the metal case 35 in which the thermistor 37 is sealed, the thermistor 37 can easily and unevenly disperse the part of the stand. Less installation is possible. A terminal connected to the brush lead wire 40, a brush lead wire 40, a wadding wire 43, a spring washer, and a screw-integrated thermistor 45 are mounted in this order in this order, and sealed in a metal case 35. In order to detect heat with high sensitivity using the thermistor 37, a structure is used in which the portion of the metal case 35 in which the thermistor 37 is sealed is covered by the height of a screw applied to the tanshi stand, a washer, a tanshi, or the like. ing. Further, the workability is further improved by integrating the brush lead wire 40 and the wadding wire 43. The heat generated at the brush tip by the fireworks rectification of the brush 38 passes through the brush 38 and the brush lead wire 40 and is detected by the screw integrated thermistor 45. Further, since the brush holder 39 and the tansi table attached to the brush holder plate 41 are a metal plate integrated by press molding, the brush 38, the brush holder 39 and the tan table, which are heat sources, come into metal contact, Further improvement in thermal conductivity can be achieved. Further, in the mounting structure using the screw-integrated thermistor 45, the inside of the metal case 35 is sealed with a resin 36 or the like in order to enhance heat conduction inside the metal case 35 which has been subjected to screw processing, and the thermistor 37 is fixed with an adhesive or the like. Things. In order to provide higher thermal conductivity, it is desirable to use copper or aluminum for the metal case and the brush holder 39.
[0021]
The position where the screw-integrated thermistor 45 is mounted is the case of the brush 38 which is electrically positive. In this case, an insulating plate 42 is interposed below the brush holder 39 on the positive side to electrically insulate the base from the brush holder 39. By sandwiching the insulating plate 42 having lower heat conductivity than metal, the heat of the positive brush holder 39 is less likely to escape than the negative brush holder in contact with metal. Therefore, by arranging the temperature sensor on the positive side, it is possible to more accurately detect the accurate heat storage around the brush.
[0022]
When the brush 38 is worn and shortened, the thermal resistance and capacity of the brush 38 decrease, and the temperature rise is detected faster than in the initial stage.
[0023]
FIG. 5 is a flowchart in the motor temperature protection logic. The motor drive controller 14 determines whether or not 4WD drive is necessary, and checks whether the temperature signal from the thermistor 37 is equal to or less than a specified value. Here, the temperature of the motor is high immediately after the motor is repeatedly operated or continuously operated for a long time. Therefore, even if the motor enters the 4WD mode, the motor immediately enters a temperature failure. This is for restarting the 4WD mode after lowering. The motor is operated for 4WD drive, and the current supplied to the motor is detected by the current sensor 6 if the current is equal to or greater than the specified current. If the specified current is exceeded, the input to the motor is limited when the specified time is exceeded. FIG. 6 shows a characteristic diagram at the time of the temperature protection operation, and shows the relationship between the energizing current and the energizing time. This characteristic diagram is determined, for example, from the heat-resistant temperatures of the armature winding and the varnish portion, and limits the input of the motor when the current value input to the motor is equal to or longer than the time specified in FIG. If the current value detected by the current sensor is equal to or less than the specified current value, the temperature of the thermistor 37 is detected, and if the thermistor temperature exceeds the primary specified value, the motor input is limited. If the temperature of the thermistor continues to rise further with the limited input and becomes equal to or higher than the secondary specified value, the input to the motor is turned off so that the system is not operated. Here, the primary specified value is set to a value with a margin with respect to the heat resistant temperature of each part of the motor, and the secondary specified value is set to the heat resistant temperature of each part of the motor. FIG. 7 shows the temporal characteristics of the brush temperature, the commutator temperature, and the brush lead wire temperature. For example, during continuous operation of the motor, it can be seen that the portion of the motor where the temperature rises sharply is the brush 38 made of brush rectified sparks and the commutator 34 in contact with the brush 38. Further, assuming that the commutator 34 is a resin-molded part, it is assumed that the resin having low heat resistance is the resin in the commutator. Here, assuming that the heat-resistant temperature of the resin in the commutator is 180 ° C., the above-mentioned primary specified value is set to 150 ° C., and the secondary specified value is set to 170 ° C., which is a lower value than the heat-resistant temperature. Protect the heat resistance of Here, since the above specified value does not directly measure the commutator temperature, it is desirable to take a correlation between the commutator 34 and the thermistor installation portion in the experimental stage in order to improve the accuracy of logic.
[0024]
In addition, when the operation state of the motor enters the protection logic of the relation between the energizing current and time and the primary specified value in the thermistor 37, the motor input is not cut off immediately, but is gradually reduced or gradually. By dropping, the output change of the motor can be gradually changed, and the temperature of the motor can be protected without abrupt change in the vehicle drivability.
[0025]
In this system, the internal temperature of the motor is detected by a temperature sensor and a protection system in a dual system of estimating a temperature by a combination of a conduction current and a conduction time.
[0026]
As described above, in one embodiment of the present invention, a screw-integrated temperature sensor is used for a brush motor for a vehicle drive device that drives wheels in a direction different from the direction of wheels driven by an engine. The temperature sensor can be easily arranged with little variation in the vicinity of the brush which is the heat source of the temperature. Further, by attaching the attachment portion of the temperature sensor to the brush holder in metal contact with the brush, it is possible to more accurately estimate the brush temperature. Furthermore, by setting the temperature sensor mounting position on the positive side where the insulating material is sandwiched between the brush holder and the brush holder plate, the escape of the brush temperature is reduced compared to the negative side, and a more accurate estimation of the brush temperature is possible. It becomes possible. In addition to the motor temperature detection by the temperature sensor, the motor input is restricted by the combination of the energizing current and the energizing time, so that a two-system motor over-temperature protection system can be provided with only one sensor. Motor heat generated by instantaneous power supply is limited by the over-temperature protection logic that limits the motor input according to the combination of the energizing current value and energizing time.Heat generated by continuous energization and repeated energization generates an output signal from the thermistor sensor. By detecting and limiting the motor input, the motor can be used up to a more accurate motor heat resistant temperature. Also, by gradually or stepwise reducing the input of the motor, the temperature of the motor can be protected without abrupt change in the driveability of the vehicle.
[0027]
【The invention's effect】
A brush motor for a vehicle drive device capable of protecting against transient heat generation and heat generation during continuous operation, and a control method thereof.
[Brief description of the drawings]
FIG. 1 is a diagram showing the overall structure of a vehicle drive device.
FIG. 2 is a sectional view of a brushed DC motor used in the drive device of the four-wheel drive vehicle shown in FIG.
FIG. 3 is a detailed view of a screw integrated thermistor.
FIG. 4 is a structural view of a screw-integrated thermistor.
FIG. 5 is a flowchart in a motor temperature protection logic.
FIG. 6 is a characteristic diagram during a temperature protection operation.
FIG. 7 is a characteristic diagram of a brush temperature, a commutator temperature, and a time characteristic of a brush lead wire.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... vehicle, 2 ... engine, 3 ... front wheel, 4 ... rear wheel, 5 ... brushed DC motor, 6 ... current sensor, 7 ... 1st generator, 8 ... battery, 9 ... 2nd generator, 10 ... Power supply line for motor drive, 11 ... Clutch, 12 ... Differential gear, 13 ... Drive shaft, 14 ... Controller for motor drive, 15 ... Vehicle speed sensor, 16 ... ABS control unit, 17 ... Brake, 18 ... ABS actuator, 19 ... Engine control unit, 20: Field power line, 21: Temperature sensor line, 22: Yoke, 23: Front bracket, 24: Rear bracket, 25: Through bolt, 26: Bolt mounting hole, 27: Rotating shaft, 28 ... Armature core, 29 ... Field winding, 30 ... Pole core, 31 ... Bolt, 32 ... Armature, 33 ... Bearing 34 ... commutator 35 ... metal case, 36 ... resin,
37 ... Thermistor, 38 ... Brush, 39 ... Brush holder, 40 ... Brush lead wire, 41 ... Brush holder plate, 42 ... Insulating plate, 43 ... Water wire, 44 ... Thermistor lead wire, 45 ... Screw integrated thermistor, 46 ... Brush press spring.

Claims (9)

A brush for a vehicle drive device that drives one of a front wheel and a rear wheel of a vehicle with an engine and the other is driven by a motor, and a brush that supplies power to a rotor of the vehicle drive device brush motor, A brush motor for a vehicle drive device, comprising: a brush holder for connecting external power to the brush via a power supply line; and a temperature sensor for measuring a motor temperature attached to the brush holder. The brush motor for a vehicle drive device according to claim 1, wherein the power supply line is fixed to the brush holder. The brush motor for a vehicle drive device according to claim 1, wherein the temperature sensor is enclosed in a case. The brush motor for a vehicle drive device according to claim 3, wherein the case is a metal case. 2. The brush motor for a vehicle drive device according to claim 1, wherein the temperature sensor is capable of estimating a temperature of the brush at which the brush motor reaches a maximum temperature when the brush motor is continuously operated. 3. . 2. The brush motor for a vehicle drive device according to claim 1, wherein the brush holder is an electrically insulated positive side. A brush motor for a vehicle drive device in which one of a front wheel and a rear wheel of a vehicle is driven by an engine, and the other is driven by a motor. The brush motor has a temperature sensor for measuring a temperature of the motor. A vehicle comprising: a first over-temperature protection logic that limits a motor input according to a combination of time; and a second over-temperature protection logic that detects an output signal from a temperature sensor and limits the motor input. Brush motor for drive unit. 8. The brush motor for a vehicle drive device according to claim 7, wherein heat generated by the motor is limited by the first over-temperature protection logic for instantaneous power supply, and heat generated by continuous energization or repeated energization is provided by the second over-temperature protection. A brush motor for a vehicle drive device, wherein the brush motor is limited by logic. A method for controlling a brush motor for a vehicle drive device in which one of a front wheel and a rear wheel of a vehicle is driven by an engine and the other is driven by a motor, wherein input power to the motor is reduced before the temperature of the motor becomes excessive. A brush motor control method for a vehicle drive device, wherein the brush motor is controlled so as to limit the output gently, to reduce the motor output gently, and not to cause a drastic change in the driveability of the vehicle.

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