JP2009207267A - Device and method for shutting down and holding vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce thermal load applied to a motor during shut down control of a vehicle. <P>SOLUTION: A plurality of motors 3 and 7 that transmit a drive torque to wheels are provided. When predetermined shut down holding conditions are satisfied, a shut down holding torque Tstop for holding the shut down state of the vehicle is generated from the motor 3 or 7. The motor 3 or 7 for generating the shut down holding torque Tstop is switched as the time elapses. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle stop holding device and a stop holding method for holding a stop state of a vehicle by a driving torque of a motor when a hill hold function is exhibited.

There is a hill hold function as a function of stopping and holding the vehicle. For example, in the technique described in Patent Document 1, even if the driver releases the braking force by the brake after stopping the vehicle on a slope, the vehicle does not move back and forth by the driving torque of the motor, and the vehicle is moved to that place. Keep stationary. Further, while the vehicle is stopped, the vehicle automatically travels a distance designated by a simple command from the driver and stops at that position.
JP-A-5-268704

In the above prior art, when the vehicle stops on a slope (gradient route), the hill hold (sliding down) of the vehicle is held by the driving torque of one motor. During the holding with this driving torque, since the rotating shaft of the motor does not rotate, a current flows intensively in only one phase of the three-phase AC motor. The longer the holding time, the higher the temperature of the motor, causing a reduction in motor life.
The present invention has been made paying attention to the above points, and it is an object of the present invention to reduce the thermal load applied to the motor during vehicle stop control.

  In order to solve the above-described problem, the present invention generates a stop holding torque for holding a stop state of a vehicle with a motor when a predetermined stop holding condition is satisfied, and sets the motor for generating the stop holding torque to a time. It is characterized by changing over time.

  According to the present invention, it is possible to reduce the thermal load on each motor by changing the motor that generates the stop holding torque with the passage of time.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating an example of an outline of a system configuration of a vehicle to which the vehicle stop holding according to the present embodiment is applied. The vehicle of the present embodiment is an example of a hybrid vehicle that is driven by the engine 1 and the motor 7.
(Constitution)
First, the system configuration of the drive control portion will be described with reference to FIG.
The rotary shaft of the first motor 3 is connected to the output shaft of the engine 1 via the clutch 2. The rotating shaft of the first motor 3 is connected to the input shaft of the speed reducer 5 via the clutch 4. The output shaft of the speed reducer 5 is connected to the front wheel 6. As a result, the driving torque of the engine 1 can be transmitted to the front wheels 6 and the driving torque of the first motor 3 can be transmitted to the front wheels 6. The first motor 3 serves as an engine starting motor.

The rotation shaft of the second motor 7 is connected to the rear wheel 10 via the clutch 8 and the speed reducer 9. As a result, the driving torque of the second motor 7 can be transmitted to the rear wheel 10. The second motor 7 is a drive motor during traveling.
Reference numeral 11 denotes a battery that supplies power to the first and second motors 3 and 7.
The first motor 3 and the second motor 4 control the drive torque in accordance with a command from the drive control unit 12.
A temperature sensor 13 for detecting the temperature of the first motor 3 is provided. The temperature sensor 13 outputs the detected temperature signal to the drive control unit 12. Similarly, a temperature sensor 14 that detects the temperature of the second motor 7 is provided. The temperature sensor 14 outputs the detected temperature signal to the drive control unit 12.

Moreover, the inclination sensor 15 which detects the inclination of a driving | running | working road surface is provided. The tilt sensor 15 outputs the detected tilt signal to the drive control unit 12.
Further, an accelerator opening sensor 16 that detects the opening of the accelerator pedal operated by the driver is provided. The accelerator opening sensor 16 outputs the detected accelerator opening signal to the drive control unit 12.
Moreover, the brake opening degree sensor 17 which detects the opening degree of the brake pedal which a driver | operator operates is provided. The brake opening sensor 17 outputs the detected brake opening signal to the drive control unit 12.

Each wheel 6, 10 is provided with a wheel speed sensor 18. The wheel speed sensor 18 outputs the detected wheel speed signal to the drive control unit 12.
The drive control unit 12 includes a start processing unit 12A, a travel drive control unit 12B, and a stop holding processing unit 12C.
When the start processing unit 12A determines that the start instruction state is based on the accelerator opening detected by the accelerator opening sensor 16, the start processing unit 12A outputs an output command of the engine start required torque Tst to the first motor 3 that is an engine start motor. Further, a drive command is output to the engine 1 to start the vehicle.
The travel drive control unit 12B outputs a drive command to at least one of the engine 1 and the second motor 7 on the basis of the accelerator opening detected by the accelerator opening sensor 16 and the detection signal from the wheel speed sensor 18, etc. Control to a predetermined driving state.

Next, the process of the stop holding processing unit 12C of this embodiment will be described. The stop holding processing unit 12C starts processing when a predetermined stop holding condition is satisfied.
The predetermined stop holding condition is, for example, when it is detected that the brake is returned when the vehicle stops, the accelerator opening is zero, and the slope of the stop road surface is greater than or equal to a predetermined slope.
The process of the stop holding processing unit 12C performs the process shown in FIG. 3 when the operation is started.
First, in step S10, information for stop holding processing is acquired and parameters are initialized.

That is, the number of usable motors n, the stop holding torque Tstop, the time t0 during which a current can be continuously supplied to one phase of each motor, the threshold temperature k0 of the motor temperature sensor, the maximum drive torque reduction width ΔTm0, the shear The falling vehicle speed Vdwn is acquired. Further, the engine start request flag EnSTA is initialized.
The number of usable motors n, the time t0 during which a current can be continuously supplied to one phase of the motor, the motor temperature sensor threshold temperature k0, the maximum driving torque reduction width ΔTm0, and the falling vehicle speed Vdwn are constant. A value may be set in advance.

However, when the heat resistance performance and the like of each motor is different, the time t0 during which a current can be continuously supplied to one phase of the motor and the motor temperature sensor threshold temperature k0 are set for each motor. The time t0 may be a constant value or a value calculated according to the stop holding torque Tstop or the like.
Moreover, in the said system structure, the case where there were two motors was illustrated. However, in order to have a general purpose, the number of motors that can drive wheels is defined as n.
The stop holding torque Tstop is a driving torque that needs to be generated by the motor in order to stop and hold the vehicle. The stop holding torque Tstop is calculated according to the slope of the stop road surface and the like.

Here, the relationship between the motor torque Tm and the holding torque Tr including the running resistance (including the resistance due to the gradient) is as shown in FIG.
In FIG. 4, Tst represents the ENG required start torque.
And, if ΔTm is defined as the following equation (1),
Within the range where “ΔTm> 0”, stop and hold processing, motor-driven traveling, and vehicle acceleration are possible. However, Tr = 0 in the case of a motor that is not an engine starting motor.
ΔTm = Tm− (Tst + Tr) (1)

Next, in step S20, the motor used to stop and hold the vehicle is set as the motor (n), and the process proceeds to step S30.
In step S30, a torque command value for generating the stop holding torque Tstop is output to the motor (n), and the process proceeds to step S40.
In step S40, the engine start monitoring processor 12D is operated to obtain information on whether or not an engine start request (start instruction state) has been detected. When the engine start request is determined, EnSTA is “TRUE”. Otherwise, EnSTA is “FALSE”.

In step S50, it is determined whether EnSTA is "TRUE". If EnSTA determines “TRUE”, that is, an engine start request, the process proceeds to step S140. On the other hand, when EnSTA is “FALSE”, that is, when the vehicle does not start, the process proceeds to step S60.
In step S60, it is determined whether or not the elapsed time t from the generation of the stop holding torque Tstop with the current motor (n) is less than t0 seconds. If the elapsed time t is less than t0 seconds, the process proceeds to step S70. On the other hand, when the elapsed time t is t0 seconds or more, the process proceeds to step S100.

In step S70, based on the temperature signal from the temperature sensor, it is determined whether or not the current temperature K of the motor (n) is lower than K0. If the temperature K is lower than K0, the process proceeds to step S80. On the other hand, when the temperature K is equal to or higher than K0, the process proceeds to step S100.
In step S80, it is determined whether or not the above ΔTm in the current motor (n) is equal to or greater than ΔTm0. If ΔTm is equal to or greater than ΔTm0, the process proceeds to step S90. On the other hand, if ΔTm is less than ΔTm0, the process proceeds to step S100. Note that ΔTm0 is set to a positive value, for example, zero or a slight margin.

In step S90, it is determined whether or not the wheel speed Vw in the reverse direction is less than Vdwm. If the wheel speed Vw in the reverse direction is less than Vdwm, the process returns to step S30 and the generation of the stop holding torque Tstop at the current motor (n) is continued.
On the other hand, when the wheel speed Vw in the reverse direction is equal to or higher than Vdwm, the process proceeds to step S100.
In step S100, the drive change processing unit 12E is operated to switch the motor that generates the stop holding torque Tstop. Thereafter, the process proceeds to step S110.

In step S110, the setting of the identification number of the motor that generates the stop holding torque Tstop is changed, and the process proceeds to step S120.
In step S120, it is determined whether or not the process of generating the stop holding torque Tstop has been performed once for all the motors by sequentially switching the motors. If there is a motor that has not yet been processed, the process proceeds to step S20. In this case, the motor identification number n (≧ 1) is decreased by one. On the other hand, when the process of generating the stop holding torque Tstop is performed for all the motors, the process proceeds to step S130.
In step S130, the motor identification number n is returned to the initial value (the largest value), and the process proceeds to step S20.

On the other hand, if it determines with it being an engine start request | requirement, it will transfer to step S140.
Here, the selection priority of the engine starting motor (first motor 3) is the lowest, and the motor identification number of the engine starting motor is “1”.
In step S140, it is determined whether or not the motor identification number is “1”. That is, it is determined whether or not the motor that is currently generating the stop holding torque Tstop is an engine starting motor. If the motor that is currently generating the stop holding torque Tstop is not for starting the engine, the process proceeds to step S160. On the other hand, if the motor that is currently generating the stop holding torque Tstop is an engine starting motor, the process proceeds to step S150.

In step S150, the engine start drive change processing unit 12F is operated. When the holding process is completed, the process proceeds to step S160.
In step S160, the engine starting process is performed by the engine starting motor, and the process proceeds to the start processing unit 12A. This step S160 is processing of the start processing unit 12A.
Here, by shifting to the start processing unit 12A, the motor control shifts to start processing and further to travel drive control.

Next, processing of the engine start monitoring processing unit 12D will be described.
The engine start monitoring processor 12D determines whether or not the vehicle is in the start instruction state based on the accelerator opening based on the accelerator opening signal. If it is determined that the vehicle is in the start instruction state, the engine start request flag EnSTA is set to “TRUE” and the process returns. If it is determined that the vehicle is not in the start instruction state, “FALSE” is set in the engine start request flag EnSTA and the process returns.

Next, the drive change processing unit will be described.
The drive change processing unit 12E performs motor torque reduction control for the motor (n) that is currently generating the stop holding torque Tstop, and synchronizes motor torque increase control for the next motor (n-1). Do it. However, when n = 1, the motor (n−1) is the motor (n).
At this time, control is performed so that the sum of the motor torque T (n) at the motor (n) and the motor torque T (n−1) at the motor (n−1) satisfies the following expression.
Tstop = T (n) + T (n-1)

For example, as shown in FIG. 5, the amount of increase / decrease per unit time tmot is set to ΔδTm, and the motor torque T (n) is decreased by ΔδTm every unit time tmot and the motor torque is synchronized. Increase T (n-1) by ΔδTm.
The time tmot is set in consideration of the resistance of each motor in consideration of the heat generation of each motor and the output-time characteristics.
This torque reduction and increase processing is performed until Tstop = T (n−1). When Tstop = T (n−1), the process returns.

Next, the engine start drive change processing unit will be described.
The engine start drive change processing unit 12F changes the motor that generates the stop holding torque Tstop by changing the stop holding torque Tstop from the motor (1) that is the engine starting motor to the other motor (n). The change-over process is basically the same as the process of the drive change-over process unit.
That is, the amount of increase / decrease per unit time tmot2 is set to ΔδTm, and the motor torque T (n) is decreased by ΔδTm every unit time tmot until Tstop = T (n), and synchronization is taken. The motor torque T (n−1) is increased by ΔδTm.
The unit time tmot2 is set smaller than the unit time tmot2. In addition, the unit time tmot2 is decreased as the urgency of the start is higher.
When Tstop = T (n), the process is terminated and the process returns.

(Operation)
Next, an operation example of the vehicle stop holding process will be described.
Here, it is assumed that there are two motors capable of generating the stop holding torque Tstop. That is, it is assumed that the motor (1) that is the first motor 3 and the motor (2) that is the second motor 7 are used. That is, the motor (1) is an engine starting motor.
Here, the specifications of the motor (1) and the motor (2) are set as shown in Table 1.

As shown in Table 1, the motor (1) has higher heat resistance than the motor (2).
In this case, when the stop holding process (hill hold process) is entered, the motor (2) first generates a stop holding torque Tstop. The motor (2) is a motor having a larger identification number.
When the elapsed time t of generation of the stop holding torque Tstop by the motor (2) reaches (Δt ₂ -tx), the motor that generates the stop holding torque Tstop is switched from the motor (2) to the motor (1). Then, the motor that generates the stop holding torque Tstop is switched to the motor (1).

Here, the time tx is the time required for the changeover process from the motor (2) to the motor (1). The time tx is determined based on the time tmot, ΔδT, and the stop holding torque Tstop as in the following equation. This time tx may be set to a certain time.
tx = (Tstop / ΔδT) × tmot
When the motor that generates the stop holding torque Tstop is switched to the motor (1), the motor (1) stops and holds until the elapsed time t of generation of the stop holding torque Tstop by the motor (1) reaches (Δt ₁ -2tx). Torque Tstop is generated.

Further, when the elapsed time t of the generation of the stop holding torque Tstop by the motor (1) reaches (Δt ₁ -2tx), a process of switching the motor that generates the stop holding torque Tstop from the motor (1) to the motor (2). Do. Then, the motor that generates the stop holding torque Tstop is switched to the motor (2).
Subsequently, the stop holding torque Tstop is generated by the motor (2) until the elapsed time t of the generation of the stop holding torque Tstop by the motor (1) reaches (Δt ₂ -2tx).
The above operation is repeated until the vehicle stop holding request is canceled.
However, even if the switching time is not reached, the switching process is performed when the current motor temperature reaches the limit temperature.

Further, when the engine start request is detected during the generation of the stop holding torque Tstop by the motor (1), as shown in FIG. Process to change. Then, the motor that generates the stop holding torque Tstop is switched to the motor (2).
That is, when an engine start request is detected, the motor (1) having the engine start function transfers the stop holding torque Tstop to the motor (2) to reduce the load on the motor (1). Thereafter, the engine is started.

(Effect of this embodiment)
(1) The stop holding torque Tstop for stopping and holding the vehicle on a slope (gradient road) is borne by the driving torque of a plurality of motors, and the ratio of the load is changed continuously or intermittently with time.
As a result, it is possible to reduce the thermal load on each motor. That is, it is possible to reduce the life reduction of each motor.

(2) The longer the continuous driving time for generating the stop holding torque Tstop, the longer the motor having a higher heat resistance. Thereby, the drive holding time of each motor for holding and stopping the vehicle can be appropriately set according to the characteristics of the motor.
That is, in the case of a plurality of motor drive torque generating vehicles, each motor heat resistance characteristic and output drive characteristic are considered. As a result, it is possible to appropriately distribute the output drive time of the motor, and it is possible to control the motor having a high output and high heat resistance for a long time and to reduce the load of the motor having the lower tolerance.
(3) By switching the motor that generates the stop holding torque Tstop, the motor that bears the stop holding torque Tstop is changed. As a result, the motor that has generated the stop holding torque Tstop can be given a cooling time for reducing heat generation.

(4) Increasing the second driving torque while reducing the driving torque of the first motor in the transition period (during the holding process) when switching from the first motor generating the stop holding torque Tstop to the second motor . At that time, the torque change of the first and second driving torques is controlled so that the stop holding torque Tstop is generated by the sum of the driving torques of the first motor and the second driving torque.
In this way, by controlling the load of the stop holding torque Tstop due to the driving torques of a plurality of motors in time, the step of torque fluctuation in the transition period is eliminated or reduced. Thus, the torque fluctuation shock is not transmitted to the vehicle occupant or can be reduced.

(5) When it is determined that the engine start motor has generated the stop holding torque Tstop when the vehicle start command is detected, the motor that generates the stop holding torque Tstop is changed from the engine start motor to another engine start motor. Switch to motor.
As a result, the engine 1 can be started while the vehicle is stopped and held.
(6) At this time, as for the processing time for changing the stop holding torque Tstop, the time for changing the engine from the motor for starting the engine to another motor at the time of starting is made shorter than before the starting command. As a result, it is possible to suppress delays in engine start during start processing.
(7) Further, since the stop holding torque Tstop is secured by the driving torque of the motor, no exhaust gas is generated during the holding stop process.

(Modifications and application examples)
(1) In the above embodiment, the case where the stop holding torque Tstop is generated by a single motor is exemplified, except for the transition period in which the changeover process is performed. Instead of this, the stop holding torque Tstop may be generated by the driving torque of a plurality of motors. In this case, for example, when the expected drive allowable time of each motor is approached, a changeover process from that motor to another motor is performed.

(2) In the above embodiment, the case where the front wheel 6 can be driven by the engine starting motor and the rear wheel 10 can be driven by the second motor is illustrated. That is, the case where the stop holding torque Tstop is secured by the front two wheels or the rear two wheels is illustrated.
When the vehicle is a four-wheel in-wheel motor vehicle, the stop holding torque Tstop may be controlled by another combination such as a right front wheel and a left rear wheel, or a left front wheel and a right rear wheel.

(3) In the case of an electric vehicle driven only by motor drive, Δtm may be secured and control may be performed with Tst = 0 for engine start.
(4) In the above embodiment, as an example of the predetermined stop holding condition, when the vehicle is stopped, the accelerator opening is zero, and the slope of the stop road surface is a predetermined slope or more and the brake is returned It is said. The predetermined stop holding condition is not limited to this. For example, detecting that the driver has depressed the brake when the vehicle is stopped may be set as a predetermined stop holding condition.

It is a figure which shows the outline | summary of the system configuration | structure which concerns on embodiment based on this invention. It is a figure which shows the structure of the drive control part which concerns on embodiment based on this invention. It is a figure explaining the process of the stop holding | maintenance process part which concerns on embodiment based on this invention. It is a figure which shows the relationship between the motor torque which concerns on embodiment based on this invention, and another torque. It is a figure explaining explanation at the time of transfer according to an embodiment based on the present invention. It is a figure explaining an operation example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 3 1st motor 6 Front wheel 7 Second motor 10 Rear wheel 12 Drive control part 12A Starting process part 12B Travel drive control part 12C Stop holding | maintenance process part 12D Engine start monitoring process part 12E Drive change process part 12F Drive change for engine start Processing units 13 and 14 Temperature sensor 15 Inclination sensor 16 Accelerator opening sensor EnSTA Engine start request flag K Temperature k0 Motor temperature sensor threshold temperature T Motor torque Tstop Stop holding torque

Claims (6)

When a predetermined stop holding condition is satisfied, a stop holding torque to be applied to the wheels to hold the stop state of the vehicle is generated in the vehicle stop holding device that generates the driving torque of the motor.
It has multiple motors that can transmit drive torque to the wheels,
A stop holding device for a vehicle, wherein the stop holding torque is borne by driving torques of the plurality of motors, and a ratio of the load is changed with time.   The vehicle stop-holding device according to claim 1, wherein a motor having a higher heat resistance characteristic has a longer continuous drive time for generating the stop-holding torque.   The vehicle stop holding device according to claim 1 or 2, wherein a ratio of the load is changed by switching a motor that generates a stop holding torque.   In the transition period for switching from the first motor generating the stop holding torque to the second motor, the second driving torque is increased while decreasing the driving torque of the first motor. The torque change of the first and second drive torques is controlled so that the stop holding torque is generated by the sum of the drive torques of the drive torque and the second drive torque. A vehicle stop holding device. A vehicle stop holding device including an engine for driving a drive wheel,
One of the plurality of motors comprises an engine starting motor that starts the engine,
When it is determined that the engine start motor generates stop holding torque when an engine start request is detected, the motor that generates the stop holding torque is switched from the engine start motor to another motor. The vehicle stop-holding device according to any one of claims 1 to 4, wherein the vehicle stop-holding device is provided.   A vehicle characterized in that when a predetermined stop and hold condition is satisfied, a stop and hold torque for holding the stop state of the vehicle is generated by a plurality of motors, and the motor that generates the stop and hold torque is changed over time. Stop holding method.

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