JP5093022B2 - In-wheel motor control device - Google Patents

Description

  The present invention relates to a control device for an in-wheel motor that is provided for each drive wheel of a vehicle and that can directly transmit power to the drive wheel to apply drive torque or braking torque.

  Since the in-wheel motor is provided in or near the wheel of the drive wheel of the vehicle and directly transmits power to the drive wheel, a power transmission mechanism such as a transmission or a differential provided in a conventional vehicle is used. There is no need to provide it, and the configuration of the vehicle can be simplified. An example of a control device for controlling such an in-wheel motor is described in Patent Document 1. The in-wheel motor control device described in Patent Document 1 includes an in-wheel motor that is assembled to a wheel of a wheel to rotate the wheel, and a brake unit that is provided on the wheel and includes a braking unit that brakes rotation of the wheel. A temperature detecting means for estimating the temperature of the in-wheel motor based on the operating mode of the in-wheel motor and the operating mode of the brake means, and the temperature detecting means estimates in consideration of the influence of heat generated in the braking portion of the brake means The in-wheel motor is appropriately controlled based on the temperature of the in-wheel motor.

  Patent Document 2 or Patent Document 3 discloses a technique for estimating the temperature of a motor using a thermal model or a motor thermal model (heat transfer model).

  Further, Patent Document 4 or Patent Document 5 discloses a technique for detecting a performance deterioration of a brake device, that is, a brake fade, and warning the driver of that fact to call attention.

JP 2005-341701 A JP-A-4-71379 Japanese Patent Laid-Open No. 6-153381 JP 2001-206218 A JP 2001-122107 A

  The in-wheel motor as described above is installed in or near the wheel of the wheel as a driving force source of the vehicle, so that a braking unit (for example, a brake disk or the like) of the brake device that brakes the wheel and generates a braking force on the vehicle. The brake drum) is also installed in the vicinity thereof. Accordingly, the in-wheel motor is inevitably affected by frictional heat generated in the brake disc and the brake drum when the brake device is operated. When controlling the in-wheel motor, the control is performed in consideration of the motor temperature of the in-wheel motor itself or the change state of the motor temperature. Therefore, when controlling an in-wheel motor, it is necessary to reflect the influence of the heat from the outside with respect to motor temperature, such as the frictional heat which generate | occur | produces in a brake device, to control.

  With regard to such a point, in the in-wheel motor control device described in Patent Document 1, the hydraulic pressure value and the time during which the hydraulic pressure is applied are read from the pressure sensor provided in the master cylinder or the braking unit of the brake device. The motor temperature of the in-wheel motor is estimated from these values in consideration of the heat generated by the brake device. And it is comprised so that the operation | movement aspect of an in-wheel motor may be controlled based on the estimated value of the motor temperature. For example, when the estimated value of the motor temperature is higher than a predetermined value, control is performed to reduce the current value supplied to the in-wheel motor so that the load on the in-wheel motor is reduced and the motor temperature is lowered. It has become.

  However, when the motor temperature of the in-wheel motor is estimated based on the measured hydraulic pressure of each part of the brake device as described above, for example, if some abnormality occurs in the brake device and the heat generation amount of the brake device increases, the motor temperature is accurately set. It becomes difficult to estimate. That is, the actual heat generation amount of the brake device is not accurately reflected in the estimated value of the motor temperature. As a result, there is a possibility that the in-wheel motor cannot be properly controlled based on the motor temperature.

  The present invention has been made paying attention to the above technical problem, and accurately estimates the change in the motor temperature due to the influence of heat from the outside, and reflects it in the control to appropriately control the in-wheel motor. An object of the present invention is to provide a control device for an in-wheel motor that can be used.

  In order to achieve the above object, the invention of claim 1 is provided in or near a wheel of the wheel together with a brake device for braking the wheel by friction force, and directly transmits power to the wheel to drive torque or In an in-wheel motor control device for applying a braking torque, a theoretical temperature of the in-wheel motor using a motor temperature detecting means for detecting an actual temperature of the in-wheel motor and a heat transfer model of the in-wheel motor. The difference between the motor temperature estimating means for estimating the actual motor temperature detected by the motor temperature detecting means and the estimated motor temperature estimated by the motor temperature estimating means is determined in advance to determine the overheat state of the brake device. Brake overheat detected when the brake device is estimated to be in an overheated state when the threshold is greater than 1. And a motor torque limiting unit that limits the output torque of the in-wheel motor when the brake device is determined to be in an overheated state by the brake overheat detecting unit. Device.

  According to a second aspect of the present invention, in the first aspect of the invention, the brake overheat detection means determines that the brake device is in an overheated state and the output torque of the in-wheel motor is limited. When the deviation between the actual motor temperature and the estimated motor temperature is larger than a predetermined second threshold value for determining the rising tendency of the actual motor temperature, it is necessary to stop the operation of the in-wheel motor. Warning means for calculating and notifying the driver of the in-wheel motor operable time when it is determined by the brake overheat detecting means that the operation of the in-wheel motor needs to be stopped. Is further provided.

  According to the first aspect of the present invention, the actual motor temperature of the in-wheel motor is actually measured, and the heat transfer between the in-wheel motor and the outside air is modeled on the basis of the theoretical formula. The estimated motor temperature of the motor is estimated, and based on the deviation between the actual motor temperature and the estimated motor temperature, the heat generation state of the brake device provided close to the in-wheel motor is estimated and determined. And when it determines with a brake device being an overheated state, the output torque of an in-wheel motor is restrict | limited. That is, by limiting the output torque of the in-wheel motor, it is avoided that the motor temperature of the in-wheel motor is excessively increased due to the abnormal heat generation of the brake device. Therefore, it is possible to properly estimate and detect a situation where some abnormality has occurred in the brake device and the brake device is abnormally generating heat, and the in-wheel motor can be appropriately adjusted by reflecting the detection result in the control. Can be controlled.

  According to the invention of claim 2, the actual motor temperature of the in-wheel motor is determined although the brake device is determined to be in an overheated state and the output torque of the in-wheel motor is correspondingly limited. When it is determined that the in-wheel motor has risen, the remaining drivable time of the in-wheel motor is calculated and a warning is given to the driver. Therefore, it is possible to cause the driver to recognize that an abnormality occurs in the brake device and the motor temperature of the in-wheel motor may rise excessively due to the influence of abnormal heat generation in the brake device. The in-wheel motor can be protected from abnormal heat generation by urging the driver to perform an appropriate operation such as stopping the operation of the in-wheel motor.

  Next, an embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 shows the configuration of an in-wheel motor to be controlled in the present invention. In FIG. 1, reference numeral 1 denotes a wheel of a wheel W in a vehicle on which an in-wheel motor is mounted. The wheel 1 is composed of a wheel disc 2 and a rim 3 provided on the outer periphery thereof, and a tire 4 is attached to the rim 3. It is configured as follows. An in-wheel motor 5 is disposed on the inner periphery of the wheel 1 and coaxially with the wheel 1. In other words, the in-wheel motor 5 is built in the wheel 1 of the wheel W.

  The in-wheel motor 5 is mainly for outputting a driving torque for running the vehicle. A motor 6 such as an induction motor is housed in a housing 7, and the housing 7 is attached to the arm member 8. The arm member 8 is connected to and supported by a vehicle body (not shown). An output shaft 9 for outputting the torque of the motor 6 is provided. The output shaft 9 and the motor 6 may be directly connected. In this example, the output shaft 9 and the motor 6 are connected via a speed reducer 10 constituted by, for example, a planetary gear mechanism. The output shaft 9 is connected to a wheel hub 11 that is a wheel mounting portion, and the wheel 1 is mounted on the wheel hub 11.

  A brake disc 12 integral with the wheel hub 11 is also provided. The brake disk 12 may be attached to the output shaft 9 because the brake disk 12 only needs to rotate integrally with the wheel 1. The brake disc 12 may be either a so-called solid type or a ventilated type. For example, the brake disc 12 is braked by a brake unit 13 attached to a fixed portion supported on the vehicle body side such as the housing 7.

  That is, the caliper 14 is attached to a fixed portion such as the outer surface of the housing 7, and the brake pad 15 for sandwiching the brake disk 12 from the inside (the vehicle body side, the left side in FIG. 1) and the outside (the right side in FIG. 1), 16 is provided on the caliper 14. The caliper 14 and the brake pads 15 and 16 have the same configuration as that of a conventional vehicle disc brake, and a piston (not shown) is provided for each brake pad 15 and 16, respectively. The brake pads 15 and 16 are pressed against the brake disc 12 to generate a frictional force, that is, a braking force. The pistons and the brake pads 15 and 16 are moved backward by the elastic return force of the piston seal.

  In order to operate each brake pad 15, 16, the brake unit 13 is connected to a hydraulic circuit 17 having hydraulic equipment such as a switching valve, a pressure regulating valve, and a hydraulic power source (not shown) such as a hydraulic pump. ing. Therefore, the brake disc 18 and the brake unit 13, the hydraulic circuit 17, a brake pedal (not shown), and the like constitute a brake device 18 that uses the brake disc 12 and the brake unit 13 as the braking portions 12 and 13.

  The in-wheel motor 5 described above operates with electric power supplied from a power source 19 such as a battery or a generator to output driving torque, and is forcibly rotated with torque received from the wheel 1 to generate electric power. The reaction force at that time becomes the braking torque. An electronic control unit (ECU) 20 for controlling the in-wheel motor 5, that is, for controlling the rotation of the motor 6 is provided, and the motor 6 transmits a control signal to the electronic control unit 20. Are connected as possible.

  Various sensors for controlling the in-wheel motor 5 are connected to the electronic control device 20, specifically, a temperature sensor 21 that detects the temperature of the in-wheel motor 5, and oil oil in the housing 7. Detection signals from an oil temperature sensor 22 that detects the temperature, a wheel speed sensor 23 that detects the rotational speed of the wheel W, and the like are input. Thereby, the electronic control unit 20 can detect the temperature state of each part of the in-wheel motor 5. On the other hand, the electronic control unit 20 is configured to output signals for controlling the rotation of the motor 6 via, for example, an inverter (not shown).

  As described above, the in-wheel motor 5 is installed inside the wheel 1 of the wheel W together with the brake units 12 and 13 of the brake device 18, that is, the brake disk 12 and the brake unit 13. As described above, since the braking units 12 and 13 of the brake device 18 are configured to generate a braking force by the frictional force between the brake disk 12 and the brake pads 15 and 16, heat due to friction is generated during braking. Therefore, the in-wheel motor 5 is inevitably affected by the heat generated by the braking portions 12 and 13 of the brake device 18 that is in close proximity. That is, the heat generated by the braking units 12 and 13 is easily transmitted to the in-wheel motor 5 that is close thereto.

  When the in-wheel motor 5 is operated, the temperature of the in-wheel motor 5 itself increases as the load and the number of rotations increase. However, there is an upper limit of the allowable temperature in the configuration of the in-wheel motor 5, and therefore the in-wheel motor 5 is controlled in consideration of the temperature of the in-wheel motor 5, that is, the temperature of the in-wheel motor 5 is detected and the value is reflected in the control of the in-wheel motor 5. Therefore, as described above, the heat generated in the braking units 12 and 13 of the brake device 18 that affects the temperature of the in-wheel motor 5 needs to be reflected in the control of the in-wheel motor 5.

  Therefore, in the control device for the in-wheel motor 5 according to the present invention, using a so-called heat transfer model (heat model) in which heat transfer between the in-wheel motor 5 and its surroundings is modeled based on a theoretical formula, For example, the in-wheel motor 5 can be appropriately controlled even when some trouble occurs in the brake device 18 and the braking units 12 and 13 generate heat abnormally.

  FIG. 2 is a flowchart for explaining an example of the control. The routine shown in this flowchart is repeatedly executed every predetermined short time. In FIG. 2, first, the motor temperature of the in-wheel motor 5 is estimated using a heat transfer model (thermal model) of the in-wheel motor 5. Further, the actual motor temperature of the in-wheel motor 5 is also detected by the temperature sensor 21 or the like (step S1).

  As shown in FIG. 3, the heat transfer model M is obtained by modeling heat transfer between the in-wheel motor 5 and each member around the in-wheel motor 5 based on a theoretical calculation formula. Heat transfer between the motor 6 of the in-wheel motor 5 and the housing 7, heat transfer between the motor 6 and the oil in the housing 7, and the motor 6 via the oil in the housing 7 and the gear of the speed reducer 10 This is a model for estimating the motor temperature of the in-wheel motor 5 based on theoretical equations such as heat transfer between the housing 7 and heat transfer between the housing 7 and the outside air.

  More specifically, as shown in FIG. 3, heat transfer between the motor 6 and the housing 7 of the in-wheel motor 5, that is, contact between the motor 6 and the housing 7 such as a fixed portion of the motor 6 with respect to the housing 7. The direct heat transfer in the section is modeled on the basis of a theoretical formula under a constant condition of a thermal resistance value determined according to, for example, the case of the motor 6 and the material of the housing 7. Further, indirect heat transfer between the motor 6 and the housing 7 through the oil in the housing 7 and the gear of the speed reducer 10 is modeled. That is, direct heat transfer between the motor 6 and the oil in the housing 7 is modeled based on a theoretical formula under a thermal resistance value that is a function of the oil temperature of the oil, and the housing 7 The direct heat transfer between the oil in the housing and the housing 7 is modeled on the basis of a theoretical formula under the condition that the thermal resistance value is constant, and the gear of the oil in the housing 7 and the speed reducer 10 Direct heat transfer between the gear of the reduction gear 10 and the housing 7 is modeled on the basis of a theoretical equation under a thermal resistance value that is a function of the oil temperature of the oil. The direct heat transfer is modeled on the basis of a theoretical formula under the condition that the thermal resistance value is constant. The heat resistance between the housing 7 and the outside air, that is, the indirect heat transfer between the housing 7 and the braking units 12 and 13 of the brake device 18 via the outside air is a thermal resistance that is a function of the vehicle speed. It is modeled based on the theoretical formula under the value.

As described above, when the motor temperature of the in-wheel motor 5 is estimated based on the heat transfer model M, the estimated value T ′ of the motor temperature and the motor of the in-wheel motor 5 detected by the temperature sensor 21 and the like. A deviation of the temperature from the actual measurement value T is obtained, and it is determined whether or not the deviation is larger than the threshold value α (step S2). That is,
(Actual value T−estimated value T ′)> threshold α
Whether or not is established is determined. Here, the threshold value α is a predetermined value set in advance in order to determine whether or not the error of the measured value T with respect to the estimated value T ′, that is, the theoretical value of the motor temperature of the in-wheel motor 5 is within an allowable range. This corresponds to the first threshold value in the present invention.

  If the deviation between the measured value T and the estimated value T ′ of the motor temperature of the in-wheel motor 5 is equal to or less than the threshold value α, and if a negative determination is made in this step S2, the process returns to the above step S1, The same control as is continued.

  On the other hand, as shown in FIG. 4, when the deviation between the measured value T and the estimated value T ′ of the motor temperature of the in-wheel motor 5 is larger than the threshold value α, if the determination in step S2 is affirmative, Proceeding to step S3, motor torque limit control is performed in which the increase in output torque of the in-wheel motor 5 is limited to suppress an increase in motor temperature.

  Specifically, when the deviation amount of the actual measured value T of the motor temperature from the estimated value (that is, the theoretical value) T ′ increases beyond the threshold value α, the motor temperature does not exceed the allowable temperature Ta. The allowable increase torque of the in-wheel motor 5 is obtained using the heat transfer model M. The increase in the output torque of the in-wheel motor 5 is limited based on the allowable increase torque, that is, so as not to exceed the allowable increase torque.

Subsequently, it is determined whether or not the deviation between the estimated value T ′ of the motor temperature and the measured value T is larger than the threshold value β (step S4). That is,
(Actual value T−estimated value T ′)> threshold β
Whether or not is established is determined. Here, the threshold value β is determined that the deviation of the estimated value T ′, that is, the measured value T from the theoretical value of the motor temperature of the in-wheel motor 5 tends to increase even though the motor torque limit control is executed. This is a predetermined value set in advance, and corresponds to the second threshold value in the present invention.

  If the deviation between the measured value T and the estimated value T ′ of the motor temperature of the in-wheel motor 5 is equal to or less than the threshold value β, and if a negative determination is made in this step S4, the process returns to the above step S3. The same control as is continued.

  On the other hand, as shown in FIG. 4, when the deviation between the measured value T and the estimated value T ′ of the motor temperature of the in-wheel motor 5 is larger than the threshold value β, a positive determination is made in step S4. Proceeding to step S5, based on the estimated value T ′ of the motor temperature and the actually measured value T, the time until the motor temperature reaches the allowable temperature Ta is estimated and determined. In other words, when the motor temperature continues to increase due to the temperature increase estimated from the estimated value T ′ of the motor temperature and the actual measurement value T, the remaining time during which the operation of the in-wheel motor 5 can be continued is calculated. The

  In addition, a warning is issued to notify the driver of the remaining time during which the operation of the in-wheel motor 5 calculated as described above can be continued (step S6). For example, the driver can be visually warned by a display monitor, a warning lamp, or the like, or can be audibly warned by voice guidance or a warning sound.

  When the deviation between the measured value T and the estimated value T ′ of the motor temperature of the in-wheel motor 5 becomes larger than the threshold value β even though the motor torque limit control is executed as described above, It is conceivable that the motor temperature continues to rise due to the influence outside the control range of the motor 5 itself. Specifically, it is assumed that the braking units 12 and 13 of the brake device 18 provided close to the in-wheel motor 5 are abnormally heated. Therefore, in step S6, the driver is warned of the remaining time during which the operation of the in-wheel motor 5 can be continued, thereby causing the driver to recognize that the occurrence of some abnormality in the brake device 18 is estimated. Then, control for urging to stop the operation of the in-wheel motor 5, that is, to stop the vehicle is executed.

  Therefore, if the driver is warned of the remaining time during which the in-wheel motor 5 can be operated, it is determined whether or not the vehicle has stopped (step S7). If the vehicle is not yet stopped, that is, the operation of the in-wheel motor 5 has not been stopped, and if a negative determination is made in step S7, the process returns to step S6 and the same control as before is performed. It is executed continuously. In other words, the control in steps S6 and S7 is repeatedly executed until the vehicle is stopped and the operation of the in-wheel motor 5 is stopped.

  On the other hand, when the vehicle has stopped, that is, when the operation of the in-wheel motor 5 has been stopped, if the determination in step S7 is affirmative, the process proceeds to step S8, and the remaining travel according to the stop time. The available time is announced to the driver. That is, since the measured value T of the motor temperature deviates from the estimated value (theoretical value) T ′ and continues to rise, the operation of the in-wheel motor 5 is stopped, so that the motor temperature that has continued to rise is increased. The actual measurement value T will decrease, and there is a margin for the allowable temperature Ta by the amount that the motor temperature has decreased, so the remaining time that the in-wheel motor 5 can be operated increases by that margin. . Therefore, in this step S8, the driver is informed of the remaining travelable time according to the stop time, for example, the vehicle is evacuated to a safe place, or the vehicle is allowed to self-run to an appropriate repair factory. The control for assisting the vehicle to travel appropriately is executed. Thereafter, this routine is once ended.

  As described above, according to the control apparatus for an in-wheel motor according to the present invention, the actual motor temperature (actual value of the motor temperature) T of the in-wheel motor 5 is measured, and between the in-wheel motor 5 and the outside air. Estimated motor temperature (estimated motor temperature) T ′ of the in-wheel motor 5 is estimated using a heat transfer model M in which the heat transfer of the motor is modeled based on a theoretical formula, and the actual motor temperature T and the estimated motor temperature are estimated. Based on the deviation from T ′, the heat generation state of the braking units 12 and 13 of the brake device 18 provided close to the in-wheel motor 5 is estimated and determined. And when it determines with the braking parts 12 and 13 of the brake device 18 being an overheated state, motor torque restriction | limiting control is performed and the output torque of the in-wheel motor 5 is restrict | limited. That is, by limiting the output torque of the in-wheel motor 5, it is avoided that the motor temperature of the in-wheel motor 5 rises excessively due to the influence of abnormal heat generation in the brake device 18. Therefore, it is possible to appropriately estimate and detect a situation in which some abnormality occurs in the brake device 18 and the braking units 12 and 13 of the brake device 18 are abnormally heated, and the detection result is reflected in the control. Thus, the in-wheel motor 5 can be appropriately controlled.

  Further, the actual motor temperature of the in-wheel motor 5 is determined even though the braking units 12 and 13 of the brake device 18 are determined to be in an overheated state and the output torque of the in-wheel motor 5 is limited correspondingly. When it is determined that T is increasing, the remaining drivable time of the in-wheel motor 5 is calculated and notified to the driver as a warning. Therefore, there is a possibility that some abnormality occurs in the brake device 18 and the motor temperature of the in-wheel motor 5 is excessively increased due to the influence of abnormal heat generation in the braking units 12 and 13 of the brake device 18. The driver can recognize this, and the driver can perform an appropriate operation such as stopping the operation of the in-wheel motor 5 to protect the in-wheel motor 5 from abnormal heat generation from the outside.

  Here, the relationship between the above-described specific example and the present invention will be briefly described. The functional means for executing step S1 described above corresponds to the “motor temperature detecting means” and the “motor temperature estimating means” in the present invention. The functional means for executing steps S2, S4 and S5 correspond to the “brake overheat detecting means” in the present invention. The functional means for executing step S3 described above corresponds to the “motor torque limiting means” in the present invention, and the functional means for executing steps S6, S7, S8 corresponds to the “warning means” in the present invention. To do.

It is a conceptual diagram which shows typically the structural example of the in-wheel motor made into the object of control by this invention. It is a flowchart for demonstrating an example of control by the control apparatus of this invention. It is a conceptual diagram for demonstrating the heat transfer model of the in-wheel motor used when performing the control shown in FIG. 3 is a time chart showing a relationship between an actual motor temperature and an estimated motor temperature when the control shown in FIG. 2 is executed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Wheel, 5 ... In-wheel motor, 12 ... Brake disk, 13 ... Brake unit, 18 ... Brake device, 20 ... Electronic control unit (ECU), 21 ... Temperature sensor, 22 ... Oil temperature sensor, 23 ... Wheel speed sensor W ... Wheels.

Claims (2)

In an in-wheel motor control device that is provided in or near the wheel of the wheel together with a brake device that brakes the wheel by frictional force, and that directly transmits power to the wheel to apply driving torque or braking torque.
Motor temperature detecting means for detecting the actual temperature of the in-wheel motor;
Motor temperature estimating means for estimating a theoretical temperature of the in-wheel motor using a heat transfer model of the in-wheel motor;
When the deviation between the actual motor temperature detected by the motor temperature detecting means and the estimated motor temperature estimated by the motor temperature estimating means is larger than a first threshold value that is predetermined for determining the overheat state of the brake device, Brake overheat detection means for estimating and detecting that the brake device is in an overheat state,
In-wheel motor control comprising: motor torque limiting means for limiting the output torque of the in-wheel motor when the brake overheat detection means determines that the brake device is in an overheated state. apparatus. The brake overheat detecting means determines that the brake device is in an overheated state and the output torque of the in-wheel motor is limited, and the deviation between the actual motor temperature and the estimated motor temperature is the actual motor temperature. Means for determining that it is necessary to stop the operation of the in-wheel motor when it is greater than a second predetermined threshold value for determining the upward tendency of
When it is determined by the brake overheat detection means that it is necessary to stop the operation of the in-wheel motor, it further comprises warning means for calculating the in-wheel motor operable time and notifying the driver. The in-wheel motor control device according to claim 1.

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