JP2012217281A - Travel road determining device for vehicle, and drive force control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a travel road determining device for a vehicle allowing a travel road to be determined in an early stage even when a drive wheel is in a stop state, and to provide a drive force control device allowing an escape from the stop state of the drive wheel.SOLUTION: In a hybrid vehicle, on condition that a vehicle speed is substantially "0" when a drive wheel is in a lock state, an accelerator opening is relatively large, a rotation speed of the drive wheel is relatively small, torque for going up a hill is obtained when a road surface is the hill, and output suppression control is not started, a drive wheel lock state in a sandy ground is determined when at least one of a temperature rise gradient of a motor generator and a temperature rise gradient of an inverter is larger than a predetermined threshold. In the case of the drive wheel lock state in the sandy ground, an escape from the sandy ground is made by increasing a gain of request drive force relative to the accelerator opening.

Description

  The present invention relates to a traveling path determination device and a driving force control device for a vehicle provided with an electric motor as a driving source for traveling. In particular, the present invention provides a measure for enabling determination of the travel path even when the drive wheel is stopped, and a state where the drive wheel is stopped due to the travel path (for example, sand) ( It relates to measures for enabling escape from the stop state when it is in the locked state.

  Conventionally, as disclosed in, for example, Patent Literature 1 and Patent Literature 2, it has been proposed to determine the state of a vehicle's travel path and execute control according to the state. For example, it is possible to determine that the travel path is sandy, and when it is determined that the travel path is sandy, it is possible to travel by controlling the braking force or the like suitable for it.

  Specifically, in Patent Document 1, when both the vehicle body acceleration and the actual wheel acceleration are less than the driving force estimated acceleration that is estimated to be generated under the driving force generated by the internal combustion engine, the travel path Is determined to be sandy. When it is determined that the travel path is sandy, the brake hydraulic pressure is controlled according to the slip rate of each wheel, and ABS control suitable for traveling on sandy is performed.

  Further, in Patent Document 2, it is considered that the integral value of the differential rotational speed difference between each front wheel and each rear wheel in a four-wheel drive vehicle tends to increase because it is always differential when traveling on sand. When the integrated value of the differential rotational speed difference tends to increase, it is determined that the travel path is sandy. When it is determined that the travel path is sandy, the torque distribution suitable for traveling on sandy by increasing the engagement force between the clutch plates of the coupling device interposed between the front wheel and the rear wheel. Like to do.

JP 2006-335114 A JP 2008-265641 A

  As described above, in the conventional traveling path determination method, it is determined whether or not the traveling path is sandy ground on the assumption that the driving wheel is rotating. For this reason, for example, in a hybrid vehicle using an internal combustion engine and an electric motor as a driving source for driving, driving force for driving is generated from the electric motor, or in an electric vehicle using only the electric motor as a driving source for driving. When the driving force for driving is generated from the motor, in the situation where all the driving wheels are in the locked state (non-rotating state, also called the stack) Determination of whether or not there is).

  Further, as disclosed in Patent Document 2, in the case of determining a travel path based on an integral value of a differential rotational speed difference between each front wheel and each rear wheel, the integral value is predetermined. Therefore, a standby time (integration time) until it is determined whether or not the threshold value is reached is required, and a long time is required until the traveling path is determined. Not only that, but if the road is sandy and the drive wheels are locked, the temperature of the electric motor rises rapidly until it is determined that the road is sandy, The performance may be degraded. In other words, even after the road is determined to be sandy, even if control is performed to escape from that sandy, the performance of the electric motor is reduced, and the vehicle cannot escape well. There is a possibility that.

  The present invention has been made in view of such a point, and the object of the present invention is a vehicle travel path determination device that enables early determination of the travel path even when the drive wheels are in a stopped state, and An object of the present invention is to provide a driving force control device that enables escape of a driving wheel from a stopped state.

-Principle of solving the problem-
The solution principle of the present invention taken to achieve the above object is based on the temperature rise gradient (rise temperature per unit time) of the electric motor or inverter in a situation where the electric motor is used as a driving source for traveling. To determine the driving path. In other words, for example, when the driving path is sandy and the driving wheels are locked despite the driving force being generated from the electric motor, the temperature of the electric motor or inverter rises rapidly. become. By utilizing this fact, it is possible to determine the traveling path at an early stage even when the driving wheels are not rotating.

-Solution-
Specifically, the present invention is premised on a vehicle travel path determination device including an electric motor that is inverter-controlled as a travel drive source. The vehicle travel path determination device includes temperature gradient recognition means and drive wheel lock state determination means. The temperature gradient recognizing means recognizes the rising gradient of the temperature of at least one of the electric motor and the inverter. The driving wheel lock state determination unit compares the temperature increase gradient of at least one of the electric motor and the inverter recognized by the temperature gradient recognition unit with a preset driving wheel lock state determination threshold value. When the determination operation is performed and the temperature increase gradient of at least one of the electric motor and the inverter is equal to or higher than the driving wheel lock state determination threshold, the driving wheel is in the locked state due to the road surface state of the traveling road. Is determined.

  In this case, as the driving wheel lock state determination threshold value, the same value may be set for both the electric motor and the inverter, or different values may be set for each.

  For example, when the road is sandy and the driving wheels are locked (the driver adjusts the accelerator opening relatively small to escape the sanding while avoiding slipping of the driving wheels, In a situation where the wheel is not rotated), even if the driver requests acceleration, the locked state of the drive wheels may not be easily released. In such a situation, since the electric motor does not rotate despite the voltage being applied to the electric motor, the temperature of the electric motor or the inverter rises rapidly. That is, the temperature rises with a steeper slope than the temperature gradient of the electric motor or inverter during normal travel. When such a rapid increase in temperature occurs (when the temperature increase gradient of at least one of the electric motor and the inverter is greater than the drive wheel lock state determination threshold), the drive wheel lock state determination means It is determined that the driving wheel is in the locked state due to the road surface condition. For example, it is determined that the driving wheel is in a locked state due to the fact that the travel path is sandy. As described above, in the present solution, since the traveling road can be determined even when the driving wheel is in the non-rotating state, and the determination is based on the temperature gradient, the integrated value of the determination value (for example, Patent Document 2 above) The determination can be completed earlier than the determination of the travel path by the integrated value of the differential rotational speed difference between each front wheel and each rear wheel. As a result, it is possible to avoid a situation in which the temperature of the electric motor or the inverter rapidly rises and the performance deteriorates until the determination of the travel path is completed.

  More specifically, as a determination method of the travel path, when the temperature increase gradient of at least one of the electric motor and the inverter is larger than the drive wheel lock state determination threshold, the drive wheel lock state determination means The driving wheel is determined to be in a locked state due to the traveling road being sandy.

  For example, if the driver is excellent in driving technology for driving on sandy ground, when the drive wheel is locked on sandy ground, the driver tries to escape from the sandy ground while avoiding slippage of the driving wheel. In many cases, the adjustment is relatively small. In such a situation, there is a case where the temperature increase gradient of at least one of the electric motor and the inverter becomes larger than the drive wheel lock state determination threshold while the drive wheel is in the locked state. In other words, it leads to the situation because it is excellent in driving technology. In other words, although the accelerator opening is relatively large, it is in a locked state because the accelerator opening is small, even though the sand is likely to escape. Assuming such a situation, in the present solution, when the temperature increase gradient of at least one of the electric motor and the inverter becomes larger than the drive wheel lock state determination threshold, it is caused by the road surface condition of the traveling road. Thus, it is determined that the driving wheel is in the locked state.

  The driving wheel lock state determination operation is preferably canceled as necessary. Specifically, when the traveling speed of the vehicle is relatively high, when the accelerator pedal opening is relatively small, when the rotational speed of the drive wheels is relatively high, it is necessary to protect the electric motor and the inverter from damage due to overheating. When it becomes a certain situation, the case where the vehicle stops on the uphill road, etc. are mentioned. When any one of these situations occurs, it is preferable to cancel the driving wheel lock state determination operation. Each will be specifically described below.

  First, vehicle speed detecting means for detecting the traveling speed of the vehicle is provided, and when the traveling speed of the vehicle detected by the vehicle speed detecting means exceeds a preset lock state determination release speed, the drive wheel The drive wheel lock state determination operation by the lock state determination unit is canceled.

  That is, when the traveling speed of the vehicle is relatively high, the driving wheel is not in the locked state, and the driving wheel locking state determination operation is canceled assuming that the driving wheel locking state due to the road surface state of the traveling path has not occurred.

  Further, an accelerator opening degree detecting means for detecting the opening degree of the accelerator pedal by the driver of the vehicle is provided, and the opening degree of the accelerator pedal detected by the accelerator opening degree detecting means is set to a preset lock state determination release opening. If it is smaller than the degree, the drive wheel lock state determination operation by the drive wheel lock state determination means is released.

  That is, when the accelerator pedal opening is relatively small, the driver does not request acceleration and it is not necessary to determine the road surface condition of the traveling road, and the driving wheel lock state determination operation is cancelled.

  In addition, a drive wheel rotation speed detection means for detecting the rotation speed of the drive wheel of the vehicle is provided, and the rotation speed of the drive wheel detected by the drive wheel rotation speed detection means is a preset lock state determination release speed. When it exceeds, the drive wheel lock state determination operation by the drive wheel lock state determination means is canceled.

  In other words, when the rotational speed of the driving wheel is relatively high, the driving wheel is not in a locked state (assuming that it is traveling or slipping), and the driving wheel is locked due to the road surface state of the traveling path. The driving wheel lock state determination operation is canceled assuming that no state has occurred.

  Further, when the temperature of at least one of the electric motor and the inverter reaches a predetermined allowable upper limit value, output suppression control for limiting the voltage applied to the electric motor is executed, and the electric motor and the inverter When at least one of the temperatures reaches the allowable upper limit value, the driving wheel lock state determination operation by the driving wheel lock state determination unit is canceled.

  In other words, in a situation where it is necessary to protect against damage due to overheating of the electric motor or inverter, when the driving wheel lock state determination operation for comparing the temperature rising gradient and the driving wheel lock state determination threshold is executed, the electric motor or In such a situation, the driving wheel lock state determination operation is canceled in order to protect the electric motor and the inverter.

  Further, the road surface inclination angle is detected, the road surface inclination angle that can be climbed is recognized based on the current driving force for driving, and the road surface inclination angle that can be climbed is detected based on the current driving force for driving. If it is smaller than the inclined angle of the road surface, the drive wheel lock state determination operation by the drive wheel lock state determination means is canceled.

  In other words, when the driving force that enables traveling on the uphill road is not obtained because the vehicle is currently stopped, it is not the driving wheel locked state due to the road surface state of the traveling road, so the driving wheel locked state Release the judgment operation.

An example of the case where the drive wheel lock state determination operation is performed by the drive wheel lock state determination means is a case where the following conditions are both satisfied.
(1) The vehicle traveling speed is equal to or lower than a preset lock state determination release speed;
(2) The opening degree of the accelerator pedal by the operation of the driver of the vehicle is equal to or larger than a preset locking state determination opening degree;
(3) The rotational speed of the drive wheel of the vehicle is equal to or lower than a preset lock state determination release speed,
(4) The temperature of at least one of the electric motor and the inverter does not reach a predetermined allowable upper limit value,
(5) The road surface inclination angle that can be climbed based on the current driving force for traveling is equal to or greater than the detected road surface inclination angle.

  As described above, when it is determined that the driving wheel is in the locked state due to the traveling road, the driving control unit corrects the driving force of the vehicle. .

  In this case, the travel driving force correction means is configured to perform an increase correction of the travel driving force by increasing the gain of the travel driving force of the vehicle with respect to the opening degree of the accelerator pedal by the driver.

  As a result, in a situation where the driving wheel is locked because the accelerator opening is small, the traveling driving force is increased even if the accelerator opening is the same, so that the escape performance from sand or the like is improved. In other words, the rough road performance of the vehicle is improved.

  In the present invention, the travel path is determined based on the temperature rise gradient of the electric motor or the inverter. For this reason, even when the driving wheel is in a non-rotating state, it is possible to determine the travel path, and since the determination is based on the temperature gradient, the determination can be completed early. As a result, it is possible to avoid a situation in which the temperature of the electric motor or the inverter rapidly rises and the performance deteriorates until the determination of the travel path is completed.

It is a figure which shows schematic structure of the drive system of the hybrid vehicle which concerns on embodiment. It is a block diagram which shows the structure of control systems, such as drive-train ECU. It is a figure which shows the normal request | requirement drive force map used for the normal driving | operation and for calculating | requiring request | requirement drive force by the accelerator opening. It is a flowchart figure which shows the first half of the procedure of driving | running | working path determination operation | movement. It is a flowchart figure which shows the second half of the procedure of driving | running | working path determination operation | movement. It is a figure which shows the climbable gradient equivalent acceleration map for calculating | requiring the climbable gradient equivalent acceleration from a request | requirement driving force. It is a figure which shows the motor generator temperature map for calculating | requiring motor generator temperature by making into the parameter the voltage applied to a motor generator, and voltage application continuation time. It is a figure which shows the inverter temperature map for calculating | requiring inverter temperature by using the voltage applied to a motor generator, and voltage application continuation time as a parameter. It is a figure which shows the temperature change of the motor generator at the time of a normal driving | running | working start, and the temperature change of the motor generator at the time of a driving wheel lock. It is a figure which shows the required driving force map for sandy escaping which is used at the time of escaping from sandy ground and calculates | requires required driving force by the accelerator opening.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. This embodiment demonstrates the case where this invention is applied to the hybrid vehicle which can drive | work by 4 wheel drive.

  FIG. 1 is a diagram illustrating a schematic configuration of a drive system of a hybrid vehicle 1 according to the present embodiment. The hybrid vehicle 1 includes, as a drive system for front wheels 6a and 6b, an engine 2, a triaxial power distribution and integration mechanism 3 connected to a crankshaft 2a as an output shaft of the engine 2 via a damper 2b, A first motor generator MG1 capable of generating electricity connected to the power distribution and integration mechanism 3 and a second motor generator connected to a ring gear shaft 3e as a drive shaft connected to the power distribution and integration mechanism 3 via a reduction gear 7. MG2. The ring gear shaft 3e is connected to the front wheels 6a and 6b via the gear mechanism 4 and the differential gear 5 for the front wheels.

  On the other hand, the drive system for the rear wheels 9a, 9b includes a third motor generator MG3 connected to the rear wheels 9a, 9b via a differential gear 8 for rear wheels.

  The hybrid vehicle 1 also includes a hybrid electronic control unit (hereinafter referred to as a hybrid CPU) 10 that controls the entire drive system of the vehicle.

  The engine 2 is an internal combustion engine that outputs power using a hydrocarbon-based fuel such as gasoline or light oil, and an engine electronic control unit (hereinafter referred to as an engine CPU) that receives signals from various sensors that detect the operating state of the engine 2. 11) performs operation control such as fuel injection control, ignition control, intake air amount adjustment control, and the like. The engine CPU 11 communicates with the hybrid CPU 10, controls the operation of the engine 2 by a control signal from the hybrid CPU 10, and outputs data related to the operating state of the engine 2 to the hybrid CPU 10 as necessary. The hybrid CPU 10 and the engine CPU 11 constitute a drive system ECU 18.

  The power distribution and integration mechanism 3 includes an external gear sun gear 3a, an internal gear ring gear 3b arranged concentrically with the sun gear 3a, a plurality of pinion gears 3c that mesh with the sun gear 3a and mesh with the ring gear 3b. The planetary gear mechanism includes a carrier 3d that holds a plurality of pinion gears 3c so as to rotate and revolve, and performs a differential action using the sun gear 3a, the ring gear 3b, and the carrier 3d as rotating elements. In the power distribution and integration mechanism 3, the crankshaft 2a of the engine 2 is connected to the carrier 3d, the first motor generator MG1 is connected to the sun gear 3a, and the reduction gear 7 is connected to the ring gear 3b via the ring gear shaft 3e.

  When the first motor generator MG1 functions as a generator, the driving force of the engine 2 input from the carrier 3d is distributed to the sun gear 3a side and the ring gear 3b side according to the gear ratio. When the first motor generator MG1 functions as an electric motor, the driving force of the engine 2 input from the carrier 3d and the driving force of the first motor generator MG1 input from the sun gear 3a are integrated and output to the ring gear 3b side. The driving force output to the ring gear 3b is finally output to the front wheels 6a and 6b from the ring gear shaft 3e via the gear mechanism 4 and the differential gear 5.

  The reduction gear 7 includes an external gear sun gear 7a, an internal gear ring gear 7b arranged concentrically with the sun gear 7a, a plurality of pinion gears 7c that mesh with the sun gear 7a and mesh with the ring gear 7b. And a carrier 7d for holding a plurality of pinion gears 7c so as to rotate freely. In the reduction gear 7, the carrier 7d is fixed to the transmission case, the sun gear 7a is connected to the second motor generator MG2, and the ring gear 7b is connected to the ring gear shaft 3e.

  Motor generators (electric motors; driving sources for traveling) MG1, MG2, and MG3 are each configured as a well-known synchronous generator motor that can be driven as a generator and driven as an electric motor. Inverters 12, 13, and 14 and a boost converter Power is exchanged with the battery 16 via 15. A power line 17 connecting each inverter 12, 13, 14, boost converter 15 and battery 16 is configured as a positive bus and a negative bus shared by each inverter 12, 13, 14, and motor generators MG1, MG2, MG3. The electric power generated by any of the above can be consumed by another motor. Therefore, battery 16 is charged / discharged by electric power generated from any of motor generators MG1, MG2 and MG3 or insufficient electric power. If the balance of electric power is balanced by motor generators MG1, MG2, and MG3, battery 16 is not charged / discharged.

  Motor generators MG1, MG2, and MG3 are all driven and controlled by a motor electronic control unit (hereinafter referred to as motor ECU) 20. The motor ECU 20 receives signals necessary for driving and controlling the motor generators MG1, MG2, MG3, for example, from rotational position detection sensors 21, 22, 23 that detect the rotational positions of the rotors of the motor generators MG1, MG2, MG3. A signal and a phase current applied to motor generators MG1, MG2, and MG3 detected by a current sensor (not shown) are input, and a switching control signal to inverters 12, 13, and 14 is output from motor ECU 20. Yes. The motor ECU 20 communicates with the hybrid CPU 10, and controls the motor generators MG1, MG2, MG3 by the control signal from the hybrid CPU 10 and hybridizes data related to the operating state of the motor generators MG1, MG2, MG3 as necessary. It outputs to CPU10.

  The motor generators MG1, MG2, and MG3 and the inverters 12, 13, and 14 are cooled by air cooling. For example, a cooling fan (not shown) is disposed in the vicinity, and cooling is performed using outside air by driving the cooling fan.

  The battery 16 is managed by a battery electronic control unit (hereinafter referred to as a battery ECU) 25. The battery ECU 25 receives signals necessary for managing the battery 16, for example, an inter-terminal voltage from a voltage sensor (not shown) installed between the terminals of the battery 16, and a power line 17 connected to the output terminal of the battery 16. The charging / discharging current from the attached current sensor (not shown), the battery temperature from the temperature sensor (not shown) attached to the battery 16 and the like are input, and data on the state of the battery 16 is communicated to the hybrid CPU 10 by communication as necessary. Output. The battery ECU 25 also calculates the remaining capacity (SOC) based on the integrated value of the charge / discharge current detected by the current sensor in order to manage the battery 16. Furthermore, the battery 16 is provided with a battery cooling fan 16a, which is configured to prevent the temperature of the battery 16 from excessively rising due to the control of the battery cooling fan 16a by the battery ECU 25.

  A hydraulic brake that is actuated by hydraulic pressure from the brake actuator 31 is attached to each of the front wheels 6a and 6b and the rear wheels 9a and 9b. Adjustment of the hydraulic pressure from the brake actuator 31 is performed by drive control by the brake ECU 30. The brake ECU 30 is connected to a longitudinal acceleration sensor (G sensor) 32 and a wheel speed sensor (drive wheel rotational speed detecting means) 33. The longitudinal acceleration sensor 32 detects acceleration in the longitudinal direction of the vehicle body, and can detect the acceleration / deceleration of the vehicle, the road surface gradient, and the like. Moreover, the wheel speed sensor 33 is provided in each wheel (drive wheel) 6a, 6b, 9a, 9b, and can detect the rotational speed of each wheel 6a, 6b, 9a, 9b. Further, a drive signal or the like is output from the brake ECU 30 to the brake actuator 31 via an output port. Note that the brake ECU 30 communicates with the hybrid CPU 10 and controls the drive of the brake actuator 31 by a control signal from the hybrid CPU 10 and, as necessary, the state of the brake actuator 31 and the front wheels 6a and 6b and the rear wheels 9a and 9b. Data on the state is output to the hybrid CPU 10.

  As shown in FIG. 2, the drive system ECU 18 includes a hybrid CPU 10, an engine CPU 11, a ROM 41, a RAM 42, a backup RAM 43, and the like. The ROM 41 stores various control programs, maps that are referred to when the various control programs are executed, and the like. The hybrid CPU 10 and the engine CPU 11 execute various arithmetic processes based on various control programs and maps stored in the ROM 41. The RAM 42 is a memory that temporarily stores calculation results in the hybrid CPU 10 and the engine CPU 11, data input from each sensor, and the like. The backup RAM 43 is a non-volatile memory that stores, for example, data to be saved when the ignition is turned off.

  The hybrid CPU 10, the engine CPU 11, the ROM 41, the RAM 42, and the backup RAM 43 are connected to each other via the bus 46 and to the input interface 44 and the output interface 45.

  The input interface 44 includes an ignition switch 50 that transmits an ignition signal when the driver is turned on, a shift position sensor 51 that detects the operation position of the shift lever, and an accelerator opening sensor (accelerator opening that detects the amount of depression of the accelerator pedal). Detection means) 52, a brake pedal sensor 53 for detecting the depression amount of the brake pedal, a vehicle speed sensor (vehicle speed detection means) 54 for detecting the vehicle body speed (relative speed with respect to the road surface), and the like are connected. As a result, the drive system ECU 18 receives an ignition signal from the ignition switch 50, a shift position signal from the shift position sensor 51, an accelerator opening signal from the accelerator opening sensor 52, a brake pedal position signal from the brake pedal sensor 53, A vehicle speed signal or the like from the vehicle speed sensor 54 is input.

  The input interface 44 and the output interface 45 are connected to the motor ECU 20, the battery ECU 25, and the brake ECU 30, and the hybrid CPU 10 and the engine CPU 11 perform various control signals between the motor ECU 20, the battery ECU 25, and the brake ECU 30. And exchanging data.

  The hybrid vehicle 1 configured as described above should be output to each wheel (drive wheel) 6a, 6b, 9a, 9b based on the accelerator opening Acc and the vehicle speed V corresponding to the amount of depression of the accelerator pedal by the driver. Torque (required torque) is calculated, and the engine 2 and motor generators MG1, MG2, MG3 are controlled to run with the required power corresponding to the required torque. FIG. 3 is a normal required driving force map used during normal operation, and the required driving force based on the accelerator opening is obtained from the normal required driving force map. Then, the engine 2 and the motor generators MG1, MG2, and MG3 are controlled to obtain the required driving force obtained from the normal required driving force map. Specifically, in order to reduce fuel consumption, in the operation region where the required driving force is relatively low, the required driving force is obtained by using any one or a plurality of motor generators MG1, MG2, and MG3. To be obtained. On the other hand, in the operation region where the required driving force is relatively high, one or more of the motor generators MG1, MG2, and MG3 are used, the engine 2 is driven, and the above request is made by the driving force from these driving sources. The driving force should be obtained. In order to realize such an operation switching operation, in the normal required driving force map, the rate of increase in the required driving force with respect to the amount of increase in the accelerator opening is set to be relatively small, so that the fuel consumption rate can be improved. It has become. Even if the required driving force is in an operation region where the required driving force is relatively low, if the amount of power stored in the battery 16 is less than a predetermined amount, the engine 2 is driven to obtain the required driving force and the first motor The power storage amount of the battery 16 is increased by causing the generator MG1 to function as a generator.

-Travel path judgment operation-
Next, a travel route determination operation, which is an operation characteristic of the present embodiment, will be described.

  First, an outline of the travel route determination operation will be described. This travel path determination is to determine the state of the road surface on which the vehicle is currently traveling (or the drive wheel is locked). Specifically, the drive wheels 6a, 6b, 9a, 9b When the vehicle is stopped, it is determined whether or not the cause is traveling on a road surface such as sand or rock. As a specific method for the determination, the traveling path is determined based on the temperature rise gradient (rise temperature per unit time) of the motor generator MG3 (MG1, MG2) and the inverter 14 (12, 13). ing. That is, for example, when the travel path is sandy and the driving wheel is locked despite the generation of driving force from the motor generator MG3 (MG1, MG2), the motor generator MG3 (MG1, MG2). ) And the temperature of the inverter 14 (12, 13) rises rapidly (the temperature rises with a larger gradient than the temperature rise gradient of the motor generator MG3 (MG1, MG2) and the inverter 14 (12, 13) in a normal running state) Therefore, it is possible to determine that the travel path is sandy by using this fact.

  In the following description, a case will be described in which the motor generator and the inverter that detect the temperature rise gradient for the traveling path determination are the third motor generator MG3 and the inverter 14 for the rear wheels. This is because the rear wheel third motor generator MG3 and the inverter 14 are smaller in capacity than the other motor generators MG1 and MG2 and the inverters 12 and 13, and the temperature tends to rise relatively. This is because it is possible to complete the determination of being sandy at an earlier stage.

  4 and 5 are flowcharts showing the procedure of the traveling path determination operation. This flowchart is executed every several milliseconds after the ignition switch 50 is turned on.

  First, in step ST1, the vehicle body speed Vn is detected based on the vehicle speed signal from the vehicle speed sensor 54. Thereafter, the process proceeds to step ST2, and it is determined whether or not the detected vehicle body speed Vn is equal to or lower than a preset vehicle speed threshold value Vs (lock state determination release speed) (Vn ≦ Vs). The vehicle speed threshold value Vs is set to 2 km / h, for example. That is, in this step ST2, it is determined whether or not the vehicle body is substantially stopped (the vehicle speed is substantially “0”). This value is not limited to this.

  If the vehicle body speed Vn exceeds the vehicle speed threshold value Vs and a NO determination is made in step ST2, the process proceeds to step ST3, where the travel path determination operation is canceled and the process returns. That is, the vehicle is in a traveling state, and the traveling road determination operation is canceled and returned, assuming that the driving wheel lock state in the sand has not occurred.

  On the other hand, if the vehicle body speed Vn is equal to or lower than the vehicle speed threshold value Vs and YES is determined in step ST2, the process proceeds to step ST4, where the accelerator opening degree θn is detected based on the accelerator opening signal from the accelerator opening sensor 52. To do. Thereafter, the process proceeds to step ST5, where it is determined whether or not the detected accelerator opening θn is equal to or greater than a preset accelerator opening threshold θs (lock state determination release opening) (θn ≧ θs). The accelerator opening threshold value θs is set to, for example, 30% accelerator opening. This value is not limited to this. That is, in this step ST5, when the accelerator opening is relatively large and the drive wheels 6a, 6b, 9a, 9b are in the locked state, the driver releases the locked state (for example, escapes from the sand). It is determined whether or not the vehicle is going to be driven (the vehicle speed is substantially “0” but the driver has an intention to accelerate).

  If the accelerator opening θn is less than the accelerator opening threshold θs and a NO determination is made in step ST5, the routine proceeds to step ST3, where the travel path determination operation is canceled and the process returns. In other words, the accelerator opening is relatively small, and the drive wheel lock state in the sand has not occurred (the drive wheel is not rotating despite the driver's intention to accelerate). As a result, the traveling path determination operation is canceled and the process returns.

  On the other hand, if the accelerator opening θn is equal to or greater than the accelerator opening threshold θs and the determination in step ST5 is YES, the process proceeds to step ST6, where each drive wheel (four wheels) is based on the output signal from the wheel speed sensor 33. ) The rotational speed (wheel speed) of 6a, 6b, 9a, 9b is detected. Thereafter, the process proceeds to step ST7, where the lowest rotation speed (hereinafter referred to as the drive wheel minimum speed) MIN (lock state determination release speed) among the detected rotation speeds of the drive wheels 6a, 6b, 9a, 9b is set in advance. It is determined whether or not the driving wheel speed threshold value Ws is equal to or less. The driving wheel speed threshold value Ws is set to, for example, 1 rotation / sec (1 rotation per second). This value is not limited to this. That is, in this step ST7, the rotational speeds of all the driving wheels 6a, 6b, 9a, 9b are low or stopped, and all the driving wheels 6a, 6b, 9a, 9b are in the locked state. Is determined. Here, even if the drive wheels 6a, 6b, 9a, 9b are slightly rotated (rotation of 1 rotation / sec or less), it is determined that they are in the locked state.

  When the drive wheel minimum speed MIN exceeds the drive wheel speed threshold value Ws and the NO determination is made in step ST7, the process proceeds to step ST3 to cancel the travel path determination operation and return. That is, when the drive wheel minimum speed MIN is relatively high, the drive road determination operation is canceled and the process returns, assuming that the drive wheel lock state in the sand has not occurred.

  On the other hand, if the drive wheel minimum speed MIN is equal to or less than the drive wheel speed threshold Ws and the determination in step ST7 is YES, the process proceeds to step ST8, and the required drive force is obtained from the current accelerator opening. Specifically, the accelerator opening degree θn is detected based on the accelerator opening degree signal from the accelerator opening degree sensor 52, and the accelerator opening degree θn is applied to the normal required driving force map shown in FIG. The required driving force corresponding to the accelerator opening θn is obtained. For example, when the accelerator opening is θA in FIG. 3, the required driving force is obtained as TA in the figure. In addition, you may make it calculate a request | requirement drive force from accelerator opening degree (theta) n by the arithmetic expression memorize | stored in the said ROM41 irrespective of the said normal request | requirement drive force map.

  After the required driving force is obtained, the process proceeds to step ST9, and the climbable gradient equivalent acceleration Gc is obtained from the required driving force. The climbable gradient-equivalent acceleration Gc is a value corresponding to an acceleration (acceleration in the reverse direction along the road surface) due to the gradient of the road surface that can be climbed by the driving force when the required driving force is obtained. It is. That is, when it is assumed that the road surface is inclined, this is a value corresponding to the acceleration in the backward direction caused by the inclination gradient capable of ascending by the required driving force. Specifically, the requested driving force obtained in step ST8 is applied to the climbable gradient equivalent acceleration map shown in FIG. 6 to obtain an uphillable gradient equivalent acceleration Gc corresponding to the requested driving force.

  Further, the climbable gradient equivalent acceleration Gc can also be calculated by the following equation (1).

Gc = tan [sin ⁻¹ {Fa / (W · R) −Mr}] (1)
Here, Fa is the required driving force, W is the vehicle weight, R is the tire dynamic load radius, and Mr is the rolling resistance coefficient.

  Thereafter, the process proceeds to step ST10 (FIG. 5), and based on the output signal from the longitudinal acceleration sensor 32, the vehicle body longitudinal acceleration Gn due to the road surface gradient is detected. That is, the acceleration Gn generated due to the actual road gradient is detected. Thereafter, the process proceeds to step ST11, and it is determined whether or not the detected acceleration Gn in the longitudinal direction of the vehicle body is equal to or less than the above-described acceleration corresponding to the climbable gradient Gc (Gn ≦ Gc). This determination is due to the fact that the vehicle is currently stopped, but the cause is an uphill road (climbable gradient-equivalent acceleration Gc exceeding the acceleration Gn in the vehicle longitudinal direction by the uphill road (acceleration according to the required driving force)). ) Is not obtained or whether the driving wheel is locked in sand or the like. That is, when the uphill-capable gradient-equivalent acceleration Gc is less than the acceleration Gn in the longitudinal direction of the vehicle body (Gn> Gc), a driving force sufficient to climb the uphill road is not obtained, that is, the vehicle is currently stopped. It can be determined that the reason is that the road is uphill. On the other hand, when the acceleration corresponding to the climbable gradient Gc is equal to or greater than the acceleration Gn in the longitudinal direction of the vehicle body (Gn ≦ Gc), the current vehicle is in spite of having a driving force sufficient to climb the uphill road. Since the vehicle is in a stopped state, it can be determined that there is a possibility that this stopped state is a drive wheel locked state. That is, it can be determined that the traveling road may be a bad road such as sand. In other words, this determination operation detects the slope angle of the road surface, recognizes the road slope angle that can be climbed based on the current driving force for driving, and can climb the road surface based on the current driving force for driving. If the inclination angle is smaller than the detected road inclination angle, a NO determination is made in step ST11.

  In step ST11, if the acceleration Gn in the longitudinal direction of the vehicle body exceeds the climbable gradient equivalent acceleration Gc and a NO determination is made, the process moves to step ST3 to cancel the travel path determination operation and return. In other words, it is judged that the vehicle is on an uphill road such as a paved road and the vehicle cannot travel because the accelerator opening is small (cannot climb the uphill road), that is, the vehicle can travel if the accelerator opening is large. It is determined that the situation is present, the traveling path determination operation is canceled, and the process returns.

  On the other hand, when the acceleration Gn in the longitudinal direction of the vehicle body is equal to or less than the gradient-equivalent acceleration Gc and the determination in step ST11 is YES, the process proceeds to step ST12 and the temperature Tm of the third motor generator MG3 is estimated. This temperature estimation operation is performed according to a motor generator temperature map for obtaining the motor generator temperature using the voltage applied to the third motor generator MG3 and the voltage application duration as parameters. FIG. 7 shows this motor generator temperature map. The higher the voltage applied to the third motor generator MG3 and the longer the voltage application duration, the higher the motor generator temperature Tm is estimated. .

  Thereafter, the process proceeds to step ST13, where it is determined whether or not the estimated motor generator temperature Tm is lower than a preset output suppression control start temperature Tm1 (allowable upper limit value) (Tm <Tm1). The output suppression control start temperature Tm1 is set to 120 ° C., for example. This value is not limited to this. That is, when the temperature of the third motor generator MG3 reaches the output suppression control start temperature Tm1, voltage application to the third motor generator MG3 is performed to protect the third motor generator MG3 (protection from overheating). Since it is suppressed, it is determined whether or not the output suppression control is started by comparing the motor generator temperature Tm with the output suppression control start temperature Tm1.

  When the motor generator temperature Tm is equal to or higher than the output suppression control start temperature Tm1 and NO is determined in step ST13, the process proceeds to step ST3 to cancel the traveling path determination operation and return. That is, even if the driving wheel is locked on sand, the temperature of the third motor generator MG3 is maintained within the allowable range by giving priority to the output suppression control.

  On the other hand, if the motor generator temperature Tm is less than the output suppression control start temperature Tm1 and YES is determined in step ST13, the process proceeds to step ST14, and the temperature Ti of the inverter 14 is estimated. This temperature estimation operation is performed according to an inverter temperature map for determining the inverter temperature using the voltage applied to third motor generator MG3 and the voltage application duration as parameters. FIG. 8 shows this inverter temperature map. The higher the voltage applied to the third motor generator MG3 and the longer the voltage application duration, the higher the inverter temperature Ti is estimated.

  Thereafter, the process proceeds to step ST15, and it is determined whether or not the estimated inverter temperature Ti is lower than a preset output suppression control start temperature Ti1 (allowable upper limit value) (Ti <Ti1). This output suppression control start temperature Ti1 is also set to 120 ° C., for example. This value is not limited to this. That is, when the temperature of the inverter 14 reaches the output suppression control start temperature Ti, voltage application to the third motor generator MG3 is suppressed to protect the inverter 14, so that the inverter temperature It is determined whether or not the output suppression control is started by comparing Ti with the output suppression control start temperature Ti1.

  If the inverter temperature Ti is equal to or higher than the output suppression control start temperature Ti1 and a NO determination is made in step ST15, the process proceeds to step ST3 to cancel the travel path determination operation and return. That is, even if the driving wheel is locked in sand, the temperature of the inverter 14 is maintained within the allowable range by giving priority to the output suppression control.

  On the other hand, if the inverter temperature Ti is lower than the output suppression control start temperature Ti1, and YES is determined in step ST15, the process proceeds to step ST16.

  In step ST16, the temperature increase gradient (temperature increase per unit time) ΔTm of the third motor generator MG3 is calculated, and then the process proceeds to step ST17 to calculate the temperature increase gradient ΔTi of the inverter 14. The temperature increase gradients ΔTm and ΔTi are calculated based on the motor generator temperature and the inverter temperature acquired from the maps (motor generator temperature map and inverter temperature map), and the temperature increase gradient ΔTm of the third motor generator MG3. And it is performed by calculating the temperature rise gradient ΔTi of the inverter 14 (the temperature rise gradient recognition operation of the electric motor and the inverter by the temperature gradient recognition means).

  Then, the process proceeds to step ST18, where the calculated temperature increase gradient ΔTm of the third motor generator MG3 is equal to or greater than a predetermined temperature increase gradient threshold dTM (driving wheel lock state determination threshold), and the calculated inverter 14 It is determined whether at least one of the temperature increase gradient ΔTi is equal to or higher than a predetermined temperature increase gradient threshold dTI (drive wheel lock state determination threshold) (driving by the drive wheel lock state determination means). Wheel lock state determination operation). Here, the temperature increase gradient thresholds dTM and dTI are set to 2 ° C./sec, for example. This value is not limited to this.

  When the temperature increase gradient ΔTm of the third motor generator MG3 is less than the temperature increase gradient threshold value dTM and the temperature increase gradient ΔTi of the inverter 14 is less than the temperature increase gradient threshold value dTI, and NO is determined in step ST18. Then, the process goes to step ST3 to cancel the traveling path determination operation and return. That is, assuming that both the temperature rise gradient ΔTm of the third motor generator MG3 and the temperature rise gradient ΔTi of the inverter 14 are small and the driving wheel is not locked in the sand, the traveling path determination operation is canceled and the process returns.

  On the other hand, at least one of the temperature increase gradient ΔTm of the third motor generator MG3 is equal to or higher than the temperature increase gradient threshold dTM and the temperature increase gradient ΔTi of the inverter 14 is equal to or higher than the temperature increase gradient threshold dTI is established. If YES in step ST19, the flow shifts to step ST19, where the sand determination is turned ON, and the control operation is switched to the control operation for escape from the sand in step ST20.

  FIG. 9 is a diagram showing a change in temperature of motor generator MG3 at the start of normal travel and a change in temperature of motor generator MG3 when the drive wheels are locked. As apparent from FIG. 9, when the drive wheel is locked, the temperature of motor generator MG3 rises rapidly, and the rising gradient is higher than the temperature rising gradient of motor generator MG3 at the start of normal traveling. It is big. For this reason, the above-described traveling path determination operation is performed using the difference in temperature gradient. As in the case of the temperature change of motor generator MG3, the temperature of inverter 14 rises rapidly when the drive wheel is locked, and the rising gradient is the normal start of running. It becomes larger than the temperature rise gradient of the inverter 14 at the time.

  As the control operation for escape from the sand, the required drive force is extracted according to the accelerator opening by the normal required drive force map (FIG. 3) used until it is determined that the travel path is sand. The operation is switched to the required driving force extraction operation corresponding to the accelerator opening based on the required sanding escape driving force map shown in FIG.

  This sandy ground escape required driving force map is for increasing the driving force by increasing the gain of the required driving force with respect to the accelerator opening. In other words, when the required driving force is set according to the sandy ground escape required driving force map, the required driving force is set even when the accelerator opening is the same as when the required driving force is set according to the normal required driving force map. The driving force is set high. In other words, the escape performance from the sand is improved while sacrificing the fuel consumption rate to some extent, thereby improving the rough road running performance of the vehicle (increase correction of the driving force by the driving force correction means). For example, when the accelerator opening is θA in FIG. 10, the required driving force is obtained as TB (TB> TA) in the figure.

  For example, a driver who is excellent in driving technology of this type of four-wheel drive vehicle will escape from the sand while avoiding slippage of the drive wheels 6a, 6b, 9a, 9b when the drive wheel is locked in the sand. Therefore, the accelerator opening is adjusted to be relatively small (for example, about 50%). In such a case, if the torque of the drive wheels 6a, 6b, 9a, 9b is increased a little, it may be possible to escape from the sand. For this reason, when the sand judgment is turned on, the driving force of the drive wheels 6a, 6b, 9a, 9b is increased to escape from the sand even when the accelerator opening is small. As an operation for increasing the driving force of the driving wheels 6a, 6b, 9a, 9b, when using one or a plurality of motor generators MG1, MG2, MG3, or any one or a plurality of motor generators MG1, MG2, MG3. The engine 2 may be driven while using These are determined by the magnitude of the required driving force obtained by the required driving force map for escape from sand.

  Note that after the escape from the sand or the like is performed by the required driving force obtained by the required driving force map for the escape from the sand, the temperature rise gradient of the motor generator MG3 and the inverter 14 gradually decreases. If the temperature increase gradient falls below a predetermined value, a NO determination is made in step ST18, and the travel path determination operation is canceled.

  As described above, in the present embodiment, based on the temperature rise gradient of the motor generator MG3 and the inverter 14, is the traveling path sandy or the like, and the drive wheels 6a, 6b, 9a, 9b are in a locked state? It is determined whether or not. For this reason, even when the drive wheels 6a, 6b, 9a, 9b are not rotating, the travel path can be determined, and since the determination is based on the temperature gradient, the integrated value of the determination value (for example, the above-mentioned patent) The determination can be completed earlier than in the case where the road is determined based on the differential rotational speed difference between each front wheel and each rear wheel in Document 2. As a result, it is possible to avoid a situation in which the temperature of motor generators MG1, MG2, MG3 and inverters 12, 13, and 14 rapidly rises and the performance deteriorates until the travel path determination is completed. Therefore, before the above-described output suppression control is started, it is possible to escape from the sand and the like, and it is possible to improve the rough road running performance of the vehicle.

  Further, since the travel path determination operation in the present embodiment is performed based on the temperature rise gradient of the motor generator MG3 and the inverter 14, depending on the ambient temperature of the motor generator MG3 and the inverter 14 (temperature due to the influence of the outside air temperature, etc.). Judgment is not affected. For this reason, the accuracy of the traveling path determination can be increased.

-Other embodiments-
In the embodiment described above, the case where the present invention is applied to the hybrid vehicle 1 capable of traveling by four-wheel drive has been described. The present invention is not limited to this, and can also be applied to a hybrid vehicle that travels by two-wheel drive. The present invention can also be applied to an electric vehicle using only an electric motor (motor generator) as a driving source for traveling. In this case, an electric vehicle capable of traveling by four-wheel driving and an electric vehicle performing traveling by two-wheel driving. The present invention is applicable to both.

  In the above embodiment, both the temperature of the motor generator MG3 and the temperature of the inverter 14 are estimated using the applied voltage and the voltage application duration as parameters. The present invention is not limited to this, and a temperature sensor may be provided in the vicinity of motor generator MG3 and in the vicinity of inverter 14 to detect (sense) the temperature of motor generator MG3 and the temperature of inverter 14.

  In the above embodiment, the third motor generator MG3 and the inverter 14 for the rear wheels are targeted as the motor generator and the inverter that detect the temperature rise gradient for the travel path determination. The present invention is not limited to this, and one of the other motor generators MG1 and MG2 and inverters 12 and 13 may be set to detect a temperature increase gradient for traveling path determination, or a plurality of motors Generators MG1, MG2, and MG3 and inverters 12, 13, and 14 may be set to detect a temperature increase gradient in order to determine the travel path.

  Further, in the above embodiment, when the road surface is a slope, when the torque sufficient to climb the slope is not obtained, the travel road determination operation is canceled. It is not necessary to set the condition for canceling the operation, and a traveling path determination operation that does not use the condition as a cancel condition is also within the scope of the technical idea of the present invention.

  In the above-described embodiment, only the traveling path determination operation when the drive wheels 6a, 6b, 9a, and 9b are not rotating has been described. However, when the drive wheels 6a, 6b, 9a, and 9b are rotating ( For example, when NO is determined in step ST7 in the flowchart, the traveling path is determined by a conventionally known determination operation. In this case, if it is determined that the road surface is a bad road, an escape operation is performed accordingly. For example, a control operation (generally referred to as CRAWL control) is performed in which the driving force is increased in a state where the braking force is applied to all the driving wheels 6a, 6b, 9a, 9b.

  INDUSTRIAL APPLICABILITY The present invention can be applied to travel path determination that enables determination of a travel path such as sandy land even when all drive wheels are in a stopped state in a vehicle including a motor generator that is controlled by an inverter as a travel drive source. It is.

1 Hybrid vehicles 6a, 6b Front wheels (drive wheels)
9a, 9b Rear wheel (drive wheel)
12, 13, 14 Inverter 32 Longitudinal acceleration sensor 33 Wheel speed sensor (drive wheel rotational speed detection means)
52 accelerator opening sensor (accelerator opening detecting means)
54 Vehicle speed sensor (vehicle speed detection means)
MG1, MG2, MG3 Motor generator (electric motor)

Claims (10)

In a travel path determination device for a vehicle including an electric motor controlled by an inverter as a travel drive source,
Temperature gradient recognition means for recognizing a rising gradient of at least one of the electric motor and the inverter;
A drive wheel lock state determination operation is performed to compare a temperature increase gradient of at least one of the electric motor and the inverter recognized by the temperature gradient recognition unit with a preset drive wheel lock state determination threshold, and the electric motor Drive wheel lock state determination that determines that the drive wheel is in the locked state due to the road surface condition of the traveling road when the temperature gradient of at least one of the motor and the inverter is equal to or higher than the drive wheel lock state determination threshold value. And a vehicle travel path determination device. The vehicle travel path determination device according to claim 1,
The drive wheel lock state determination means drives when the temperature increase gradient of at least one of the electric motor and the inverter is larger than the drive wheel lock state determination threshold because the travel path is sandy. A traveling path determination device for a vehicle, characterized in that it is configured to determine that a wheel is in a locked state. In the vehicle travel path determination device according to claim 1 or 2,
Vehicle speed detecting means for detecting the traveling speed of the vehicle,
The driving wheel lock state determination operation by the driving wheel lock state determination unit is canceled when the traveling speed of the vehicle detected by the vehicle speed detection unit exceeds a preset lock state determination release speed. An apparatus for determining a traveling path of a vehicle. In the vehicle travel path determination device according to claim 1, 2, or 3,
Accelerator opening detection means for detecting the opening of the accelerator pedal by the driver of the vehicle,
When the accelerator pedal opening detected by the accelerator opening detection means is smaller than a preset lock state determination release opening, the drive wheel lock state determination operation by the drive wheel lock state determination means is canceled. A vehicle travel path determination device characterized in that the vehicle travel path is determined. In the traveling path determination device for a vehicle according to any one of claims 1 to 4,
Drive wheel rotation speed detection means for detecting the rotation speed of the drive wheel of the vehicle,
When the rotational speed of the drive wheel detected by the drive wheel rotational speed detection means exceeds a preset lock state determination release speed, the drive wheel lock state determination operation by the drive wheel lock state determination means is performed. A traveling path determination device for a vehicle, characterized by being configured to cancel. In the traveling path determination device for a vehicle according to any one of claims 1 to 5,
When the temperature of at least one of the electric motor and the inverter has reached a predetermined allowable upper limit value, output suppression control for limiting the voltage applied to the electric motor is executed,
When the temperature of at least one of the electric motor and the inverter has reached the allowable upper limit value, the drive wheel lock state determination operation by the drive wheel lock state determination unit is configured to be released. A vehicle travel path determination device. In the traveling path determination device for a vehicle according to any one of claims 1 to 6,
The road surface inclination angle that can be climbed is recognized based on the current driving force for driving, and the road surface inclination angle that can be climbed based on the current driving force for driving is detected. When the vehicle is smaller than the inclination angle of the vehicle, the driving wheel locking state determination operation by the driving wheel locking state determination means is configured to be released. In the vehicle travel path determination device according to claim 1 or 2,
The driving wheel lock state determination means includes the following conditions:
(1) The vehicle traveling speed is equal to or lower than a preset lock state determination release speed;
(2) The opening degree of the accelerator pedal by the operation of the driver of the vehicle is equal to or larger than a preset locking state determination opening degree;
(3) The rotational speed of the drive wheel of the vehicle is equal to or lower than a preset lock state determination release speed,
(4) The temperature of at least one of the electric motor and the inverter does not reach a predetermined allowable upper limit value,
(5) The road surface inclination angle that can be climbed based on the current driving force for traveling is equal to or greater than the detected road surface inclination angle,
A driving road determining device for a vehicle, characterized in that the driving wheel lock state determining operation is executed on the condition that both are established.   If the vehicle travel path determination device according to any one of claims 1 to 8 determines that the drive wheels are in a locked state due to the travel path, the travel drive force of the vehicle is increased. A driving force control device for a vehicle, comprising travel driving force correction means for performing correction. In the vehicle driving force control device according to claim 9,
The travel drive force correction means is configured to perform an increase correction of the travel drive force by increasing a gain of the travel drive force of the vehicle with respect to an accelerator pedal opening by a driver. Force control device.

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