JP2007312463A - Vehicle and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure a braking force from a motor, and to prevent a battery from being fully charged. <P>SOLUTION: A CVT and the motor are controlled (S240, S250) in such a manner that, when it is determined that the remaining capacity (SOC) of the battery is smaller than a threshold Sref1 but larger than a threshold Sref2, and that the battery is not in a state of being fully charged (S150, S160), a lower efficiency gear change rate γlw at which the regeneration efficiency of the motor is lowered is set to a target gear change rate γ<SP>*</SP>of the CVT 50, and a torque command Tm<SP>*</SP>is set (S180, S190) so that required braking torque Tr<SP>*</SP>which is required for a vehicle from a vehicle speed V is output to the vehicle from the motor. By this, the braking force from the motor can be secured even if the battery is not in a state of being fully charged, and the battery can be prevented from being fully charged. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle and a control method thereof.

Conventionally, as this type of vehicle, there has been proposed a vehicle that outputs a regenerative braking force from a motor generator to an axle side via a transmission means (see, for example, Patent Document 1). In this vehicle, the charging power to the battery is increased by decelerating with a gear ratio at which the power generated by the motor generator is as large as possible.
JP 2003-74685 A

  However, in the above-described vehicle, it is good when the battery has a sufficient margin, but when the battery does not have a sufficient margin, regenerative control by the motor generator cannot be performed. Especially when traveling on a long downhill, the braking force by the motor generator cannot be expected after the battery is fully charged. In this case, the braking force can be applied using the hydraulic brake, but the heavy use of the hydraulic brake may cause a so-called vapor lock phenomenon, and the braking force may not be applied.

  One object of the vehicle and the control method thereof according to the present invention is to secure a braking force by an electric motor. Another object of the vehicle and the control method thereof according to the present invention is to prevent a power storage device such as a secondary battery from being fully charged.

  The vehicle and the control method thereof according to the present invention employ the following means in order to achieve at least a part of the above-described object.

The vehicle of the present invention
A motor capable of generating electricity that outputs power for traveling;
Power storage means capable of exchanging electric power with the electric motor;
A transmission means having an input shaft connected to the rotating shaft side of the electric motor and an output shaft connected to the axle side, and transmitting power between the input shaft and the output shaft with a change in gear ratio When,
Vehicle speed detection means for detecting the vehicle speed;
When an output of braking force is requested from the electric motor by performing regenerative control of the electric motor while a predetermined condition is established, a gear ratio that can output the requested braking force at the detected vehicle speed is set. A braking time control means for controlling the speed change means and the electric motor so that the electric motor is regeneratively controlled with a speed ratio with a low efficiency of the electric motor,
It is a summary to provide.

  In the vehicle of the present invention, when the output of the braking force is requested from the motor by performing regenerative control of the motor that outputs the driving power while the predetermined condition is satisfied, the control requested from the vehicle speed is performed. The speed change means and the electric motor are controlled so that the electric motor is regeneratively controlled with a speed ratio in which the efficiency of the motor is low among the speed ratios at which power can be output. Thereby, the braking force by the electric motor can be ensured and the power storage means can be prevented from being fully charged.

  In the vehicle according to the present invention, the predetermined condition may be a condition in which an amount of electric power that can charge the power storage unit is less than a predetermined electric energy. In this way, it is possible to prevent the power storage means from being fully charged after the amount of power that can charge the power storage means is less than the predetermined power amount. Note that the predetermined condition includes not only the condition that the amount of electric power that can charge the power storage means is less than the predetermined amount of electric power but also the condition that a long descent travel is predicted in a vehicle equipped with a navigation system. Also good.

  In the vehicle of the present invention, the braking time control means may be means for controlling the electric motor to be driven at a rotational speed lower than a rotational speed region where the electric motor is most efficiently regeneratively controlled. .

  Further, in the vehicle of the present invention, the braking time control means is allowed to change only the speed ratio from the speed ratio of the speed change means to the downshift side when the output of braking force is requested from the electric motor. It can also be a means for controlling. In this way, acceleration after deceleration can be made smooth.

  Alternatively, the vehicle of the present invention includes a second electric motor capable of inputting / outputting driving power to / from an axle different from the axle and capable of exchanging electric power with the power storage means, and the braking time control means includes the second control means. It may be a means for controlling the second electric motor so that a braking force is output from the electric motor.

The vehicle control method of the present invention includes:
A motor capable of generating electricity for outputting driving power, power storage means capable of exchanging electric power with the motor, an input shaft connected to the rotating shaft side of the motor, and an output shaft connected to the axle side. And a transmission means for transmitting power between the input shaft and the output shaft with a change in gear ratio, and a vehicle control method comprising:
When output of braking force is requested from the motor by regenerative control of the motor while a predetermined condition is satisfied, the motor of the motor among the gear ratios that can output the braking force requested from the vehicle speed. Controlling the speed change means and the electric motor so that the electric motor is regeneratively controlled with a low efficiency gear ratio;
It is characterized by

  In the vehicle control method of the present invention, when the output of braking force is requested from the motor by performing regenerative control of the motor that outputs the driving power while the predetermined condition is established, the request from the vehicle speed is made. The transmission means and the motor are controlled so that the motor is regeneratively controlled with a gear ratio at which the efficiency of the motor is low among the gear ratios at which the braking force can be output. Thereby, the braking force by the electric motor can be ensured and the power storage means can be prevented from being fully charged.

  Next, the best mode for carrying out the present invention will be described using examples.

  FIG. 1 is a configuration diagram showing an outline of a configuration of an electric vehicle 20 as an embodiment of the present invention. As shown in the figure, the electric vehicle 20 of the embodiment is a motor capable of inputting / outputting power to / from a rotary shaft 24 connected to drive wheels 63a, 63b via an axle 64, a gear mechanism 65, and a CVT 50 as a continuously variable transmission. 22, a battery 42 that exchanges power with the motor 22 via the inverter 41, a brake actuator 92 for controlling the hydraulic pressure to the brake wheel cylinders 98 a and 98 b of the drive wheels 63 a and 63 b, and the entire vehicle. A main electronic control unit 70.

  The CVT 50 includes a primary pulley 53 that can be changed in groove width and connected to the rotary shaft 24 as an input shaft, a secondary pulley 54 that is also changeable in groove width and connected to the output shaft 52, a primary pulley 53, and a secondary pulley. 54, and a first actuator 56 and a second actuator 57 that change the groove widths of the primary pulley 53 and the secondary pulley 54, and the primary actuator 56 and the second actuator 57 are used as a primary. By changing the groove widths of the pulley 53 and the secondary pulley 54, the power from the rotating shaft 24 is steplessly changed and output to the output shaft 52. The CVT 50 is shift-controlled by a CVT electronic control unit (hereinafter referred to as CVTECU) 59. The CVTECU 59 receives the rotational speed Nin of the rotational shaft 24 from the rotational speed sensor 61 attached to the rotational shaft 24, the rotational speed Nout of the output shaft 52 from the rotational speed sensor 62 attached to the output shaft 52, and the like. The CVTECU 59 outputs drive signals to the first actuator 56 and the second actuator 57. The CVTECU 59 communicates with the main electronic control unit 70, controls the transmission ratio of the CVT 50 by a control signal from the main electronic control unit 70, and adjusts the rotational speed Nin of the rotary shaft 24 and the output shaft 52 as necessary. Data relating to the operating state of the CVT 50 such as the rotation speed Nout and the gear ratio γ (= Nin / Nout) is output to the main electronic control unit 70.

  The brake actuator 92 has a braking torque according to the share of the brake in the braking force applied to the vehicle by the pressure (brake pressure) of the brake master cylinder 90 and the vehicle speed V generated in response to the depression of the brake pedal 85. The brake wheel cylinders 96a and 96d are adjusted so as to act on the driven wheel 63b and a driven wheel (not shown), and the braking torque is applied to the drive wheels 63a and 63b and the driven wheel regardless of the depression of the brake pedal 85. The hydraulic pressures of 98a to 98d can be adjusted. The brake actuator 92 is controlled by a brake electronic control unit (hereinafter referred to as a brake ECU) 94. The brake ECU 94 communicates with the main electronic control unit 70, and controls the drive of the brake actuator 92 by a control signal from the main electronic control unit 70, and the data related to the state of the brake actuator 92 as necessary. Output to 70.

  The main electronic control unit 70 is configured as a microprocessor centered on the CPU 72. In addition to the CPU 72, a ROM 74 for storing processing programs, a RAM 76 for temporarily storing data, an input / output port and a communication port (not shown). With. The main electronic control unit 70 includes a signal from the rotational position detection sensor 23 that detects the rotational position of the rotor of the motor 22 as a signal necessary for driving and controlling the motor 22, and a battery 42 configured as a secondary battery. Position sensor for detecting the terminal voltage of the battery 42, the charge / discharge current, the battery temperature, the ignition signal from the ignition switch 80, and the operation position of the shift lever 81, which are detected by a sensor (not shown) as signals necessary for managing The shift position SP from 82, the accelerator opening Acc from the accelerator pedal position sensor 84 that detects the depression amount of the accelerator pedal 83, the brake pedal position BP from the brake pedal position sensor 86 that detects the depression amount of the brake pedal 85, and the vehicle speed Sensor 87 Et of the vehicle speed V, the a brake pressure from the pressure sensor 91 attached to the brake master cylinder 90 is input via the input port. From the main electronic control unit 70, a switching control signal to the switching element of the inverter 41 is output through an output port. The main electronic control unit 70 also exchanges various control signals and data with the CVTECU 59 and the brake ECU 94. In the embodiment, as the shift position SP, a parking position or a travel position (D position) as a normal position traveling in the forward direction, a brake position (B position) with a braking force greater than the D position when the accelerator is off, and a neutral position ( N position), reverse position (R position) for traveling in the reverse direction, and the like are prepared. The main electronic control unit 70 also calculates the remaining capacity (SOC) based on the integrated value of the charge / discharge current in order to manage the battery 42.

  Next, the operation of the electric vehicle 20 of the embodiment configured as described above, particularly the operation when the driver releases the depression of the accelerator pedal 83 during traveling will be described. FIG. 2 is a flowchart showing an example of an accelerator-off time control routine executed by the main electronic control unit 70 when the accelerator is turned off. This routine is repeatedly executed every predetermined time (for example, every several milliseconds) when the accelerator is off.

  When the accelerator-off time control routine is executed, the CPU 72 of the main electronic control unit 70 first starts the shift position SP from the shift position sensor 82, the vehicle speed V from the vehicle speed sensor 87, the gear ratio γ of the CVT 50, the remaining battery 42. Processing for inputting data necessary for control such as capacity (SOC) is executed (step S100). When the necessary data is input, the required braking torque Tr * required for the vehicle is set based on the input shift position SP and the vehicle speed V (step S110). Here, in the embodiment, the required braking torque Tr * is stored in the ROM 74 as a required braking torque setting map by predetermining the relationship among the shift position SP, the vehicle speed V, and the required braking torque Tr *. When the vehicle speed V is given, the corresponding required braking torque Tr * is derived and set from the stored map. FIG. 3 shows an example of the required braking torque setting map.

  Subsequently, when the set required braking torque Tr * is output from the motor 22 to the vehicle, the regeneration efficiency E1 of the motor 22 when the transmission gear ratio of the CVT 50 is set to the current transmission gear ratio γ is derived (step S120). In this embodiment, in this embodiment, the relationship between the rotational speed Nm, torque Tm, and regeneration efficiency of the motor 22 is determined in advance and stored in the ROM 74 as a regeneration efficiency derivation map, and the rotational speed Nm, torque Tm of the motor 22 is stored. And the corresponding regeneration efficiency was derived from the stored map. Here, the rotational speed Nm of the motor 22 can be obtained based on the rotational position of the rotor of the motor 22 from the rotational position detection sensor 23, and the torque Tm of the motor 22 is obtained by changing the required braking torque Tr * to the gear ratio Gr. And divided by the product of the transmission ratio γ (Tm = Tr * / (Gr · γ)). FIG. 4 shows an example of the regeneration efficiency deriving map.

  Next, when the set required braking torque Tr * is output from the motor 22 to the vehicle, the rotational speed Nm and the torque Tm of the motor 22 when the speed ratio of the CVT 50 is increased from the current speed ratio γ by the change amount Δγ. At the same time, the regeneration efficiency E2 of the motor 22 at this time is derived from the regeneration efficiency deriving map illustrated in FIG. 4 (step S130). Comparing the derived regenerative efficiencies E1 and E2, the speed ratio at which the regenerative efficiency of the motor 22 becomes lower is set as the low efficiency speed ratio γlw, and the speed ratio at which the regenerative efficiency becomes higher is set as the high efficiency speed ratio γhi. Set (step S140). Here, the amount of change Δγ is set as a range in which the speed ratio of the CVT 50 can be changed at the execution interval of this routine. The reason why the current speed ratio γ is decreased by the change amount Δγ is not considered because only the shift to the downshift side is executed in order to make the next acceleration smooth.

  When the low efficiency gear ratio γlw and the high efficiency gear ratio γhi are set, it is determined whether or not the input remaining capacity (SOC) of the battery 42 is smaller than the threshold value Sref1 (step S150). Here, the threshold value Sref1 is used to determine whether or not the battery 42 is nearly fully charged, and a value such as 95% or 98% can be used, for example. When the remaining capacity (SOC) of the battery 42 is greater than or equal to the threshold value Sref1, it is determined that the battery 42 is almost fully charged, and the current gear ratio γ is set to the target gear ratio γ * of the CVT 50 (step S210). The value 0 is set in the torque command Tm * of the motor 22 (step S220), and the required braking torque Tr * required for the vehicle is set in the brake torque command Tb * (step S230). Then, the set target gear ratio γ * is transmitted to the CVTECU 59 and the brake torque command Tb * is transmitted to the brake ECU 94 (step S240), and the torque corresponding to the torque command Tm * from the motor 22 (in this case, a torque of value 0). Is controlled to switch the switching element of the inverter 41 (step S250), and the accelerator off time control routine is terminated. Here, the CVT ECU 59 having received the target speed ratio γ * at which the current speed ratio γ is set drives and controls the first actuator 56 and the second actuator 57 so as to maintain the current speed ratio γ, and the required braking torque Tr *. The brake ECU 94 that has received the brake torque command Tb * set to controls the brake actuator 92 so that the braking force corresponding to the brake torque command Tb * acts on the vehicle.

  When it is determined in step S150 that the remaining capacity (SOC) of the battery 42 is smaller than the threshold value Sref1, it is determined whether or not the remaining capacity (SOC) is larger than the threshold value Sref2 (step S160). Here, the threshold value Sref2 is used to determine whether or not the battery 42 is sufficiently charged, and for example, a value such as 50%, 60%, or 70% can be used. When the remaining capacity (SOC) of the battery 42 is equal to or less than the threshold value Sref2, it is determined that the battery 42 is sufficiently charged, and the high efficiency gear ratio γhi is set to the target gear ratio γ * of the CVT 50 (step S170). Then, the required braking torque Tr * divided by the product of the gear ratio Gr of the gear mechanism 65 and the target gear ratio γ * (Tr * / (Gr · γ *)) is set as the torque command Tm * of the motor 22 ( Step S190), the value 0 is set to the brake torque command Tb * (Step S200), the processing after Step S240 is executed, and this routine is finished. The CVTECU 59 that has received the target speed ratio γ * in which the high-efficiency speed ratio γhi is set so that it becomes the target speed ratio γ *, that is, the target speed ratio γ * is the sum of the current speed ratio γ and the change amount Δγ. In some cases, the first actuator 56 and the second actuator 57 are controlled to be downshifted by the change amount Δγ, and when the target speed ratio γ * is the current speed ratio γ, the first speed ratio γ is maintained. The actuator 56 and the second actuator 57 are driven and controlled. The brake ECU 94 that has received the brake torque command Tb * in which the value 0 is set controls the brake actuator 92 so that the hydraulic pressure does not act on the brake wheel cylinders 96a to 96d. For the motor 22, the switching element of the inverter 41 is subjected to switching control so that a torque corresponding to the torque command Tm * is output. By controlling in this way, the kinetic energy of the vehicle can be efficiently regenerated as electric power and stored in the battery 42.

  When the remaining capacity (SOC) of the battery 42 is larger than the threshold value Sref2 in step S160, it is determined that the battery 42 is not sufficiently charged, and the low efficiency gear ratio γlw is set to the target gear ratio γ * of the CVT 50 ( Step S180), the processing after step S190 is executed, and this routine is terminated. By controlling in this way, the efficiency at the time of regenerating the kinetic energy of the vehicle into electric power can be reduced, and the battery 42 can be prevented from being fully charged.

  According to the electric vehicle 20 of the embodiment described above, when it is determined that the state of the battery 42 is not sufficiently charged when the accelerator is off, the CVT 50 is controlled so that the regenerative efficiency of the motor 22 is low. In addition, since the motor 22 is controlled so that the required braking torque Tr * is output from the motor 22 via the CVT 50, the braking force from the motor 22 is ensured even when the state of the battery 42 is not sufficiently charged. In addition, the battery 42 can be prevented from being fully charged. As a result, the braking force from the motor 22 can be ensured without using a lot of hydraulic brakes even when traveling on a long downhill. In addition, since the shift of the CVT 50 is only changed to the downshift side, the next acceleration can be smoothly accelerated. Further, when the battery 42 is sufficiently charged, the CVT 50 is controlled so that the regenerative efficiency of the motor 22 is high, and the required braking torque Tr * is output from the motor 22 via the CVT 50. Since the motor 22 is controlled, the braking force from the motor 22 can be secured, and the kinetic energy of the vehicle can be efficiently regenerated as electric power and stored in the battery 42.

  In the electric vehicle 20 of the embodiment, the CVT 50 is shifted only to the downshift side. However, if the required braking torque Tr * is within a range in which the required braking torque Tr * is changed to a gear ratio that can be output from the motor 22, Changes to the upshift side may be allowed.

  In the electric vehicle 20 of the embodiment, when it is determined that the state of the battery 42 is not sufficiently charged, the CVT 50 is controlled so that the regenerative efficiency of the motor 22 becomes a low gear ratio, and the motor 22 is connected via the CVT 50. The motor 22 is controlled so that the required braking torque Tr * is output from the motor. However, regardless of the state of the battery 42, for example, when it is predicted to travel on a long downhill, the regeneration efficiency of the motor 22 is low. The CVT 50 may be controlled so as to achieve the gear ratio, and the motor 22 may be controlled so that the required braking torque Tr * is output from the motor 22 via the CVT 50. Prediction of traveling on a long downhill can include, for example, when traveling on a long uphill or when a vehicle equipped with a navigation system has a long downhill on a route that is predicted to travel.

  In the electric vehicle 20 of the embodiment, when the remaining capacity (SOC) of the battery 42 is smaller than the threshold value Sref1 and larger than the threshold value Sref2, the gear ratio of the CVT 50 is set to the low efficiency gear ratio γlw at which the regeneration efficiency of the motor 22 is lowered. However, the transmission ratio of the CVT 50 may be a transmission ratio at which the rotational speed is lower than the rotational speed range in which the motor 22 is most efficiently regeneratively controlled and the regenerative efficiency of the motor 22 is reduced.

  In the electric vehicle 20 according to the embodiment, when it is determined that the state of the battery 42 is not sufficiently charged when the accelerator is off, the CVT 50 is controlled so that the regenerative efficiency of the motor 22 is low, and the CVT 50 is passed through. Although the motor 22 is controlled so that the required braking torque Tr * is output from the motor 22, the braking force applied to the vehicle when the brake pedal 85 is depressed is determined by the regenerative torque from the motor 22 and the brake actuator 92. The present invention may be applied to the control of the motor 22 and the CVT 50 when outputting using a hydraulic brake.

  In the electric vehicle 20 of the embodiment, the CVT 50 of a continuously variable transmission is provided as a transmission, but is not limited to such a CVT 50, and other types of continuously variable transmissions such as a toroidal type are used. Alternatively, a stepped transmission may be provided.

  In the electric vehicle 20 of the embodiment, the drive wheels 63a and 63b are provided with the motor 22 that inputs and outputs power via the transmission, but the drive wheel 63a is exemplified as the electric vehicle 120 of the modified example of FIG. , 63b may be provided with a motor 122 capable of inputting / outputting power to drive wheels 64a, 64b.

  In the examples, the embodiment of the present invention has been described using the electric vehicle 20, but it may be in the form of a vehicle such as a train other than the automobile, or in the form of a vehicle control method.

  The best mode for carrying out the present invention has been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the gist of the present invention. Of course, it can be implemented in the form.

  The present invention can be used in the vehicle manufacturing industry.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 which is one Example of this invention. It is a flowchart which shows an example of the control routine at the time of the accelerator off performed by the main electronic control unit 70 of an Example. It is explanatory drawing which shows an example of the map for request | requirement braking torque setting. It is explanatory drawing which shows an example of the map for derivation | regeneration efficiency. It is a block diagram which shows the outline of a structure of the electric vehicle 120 of a modification.

Explanation of symbols

20 electric vehicle, 22 motor, 23 rotational position detection sensor, 24 rotational shaft, 41 inverter, 42 battery, 50 CVT, 52 output shaft, 53 primary pulley, 54 secondary pulley, 55 belt, 56 first actuator, 57 second actuator , 59 CVT electronic control unit (CVTECU), 61 rpm sensor, 62 rpm sensor, 63a, 63b drive wheel, 64 axle, 64a, 64b drive wheel, 65 gear mechanism, 70 main electronic control unit, 72 CPU, 74 ROM, 76 RAM, 80 Ignition switch, 81 shift lever, 82 shift position sensor, 83 accelerator pedal, 84 accelerator pedal position sensor, 85 brake pedal, 86 brake pedal position sensor, 87 vehicle speed sensor 90 brake master cylinder, 91 pressure sensor, 92 brake actuator, 94 electronic control unit (brake ECU) for braking, 98a, 98b, 98c, 98d brake wheel cylinders, 120 electric vehicle, 122 motor, 150 a stepped transmission.

Claims (6)

A motor capable of generating electricity that outputs power for traveling;
Power storage means capable of exchanging electric power with the electric motor;
A transmission means having an input shaft connected to the rotating shaft side of the electric motor and an output shaft connected to the axle side, and transmitting power between the input shaft and the output shaft with a change in gear ratio When,
Vehicle speed detection means for detecting the vehicle speed;
When an output of braking force is requested from the electric motor by performing regenerative control of the electric motor while a predetermined condition is established, a gear ratio that can output the requested braking force at the detected vehicle speed is set. A braking time control means for controlling the speed change means and the electric motor so that the electric motor is regeneratively controlled with a speed ratio with a low efficiency of the electric motor,
A vehicle comprising:   The vehicle according to claim 1, wherein the predetermined condition is a condition that an amount of electric power that can charge the power storage unit is less than a predetermined electric energy.   The vehicle according to claim 1 or 2, wherein the braking time control means is a means for controlling the motor to be driven at a rotational speed lower than a rotational speed region where the electric motor is most efficiently regeneratively controlled.   2. The braking time control means is a means for controlling so that only a change in the gear ratio from the gear ratio of the gear shift means to the downshift side when a braking force output is requested from the electric motor is allowed. Or vehicle according to any one of 3; The vehicle according to any one of claims 1 to 4,
A second electric motor capable of inputting and outputting driving power to an axle different from the axle and capable of exchanging electric power with the power storage means;
The braking time control means is means for controlling the second electric motor so that a braking force is output from the second electric motor. A motor capable of generating electricity for outputting driving power, power storage means capable of exchanging electric power with the motor, an input shaft connected to the rotating shaft side of the motor, and an output shaft connected to the axle side. And a transmission means for transmitting power between the input shaft and the output shaft with a change in gear ratio, and a vehicle control method comprising:
When output of braking force is requested from the motor by regenerative control of the motor while a predetermined condition is satisfied, the motor of the motor among the gear ratios that can output the braking force requested from the vehicle speed. Controlling the speed change means and the electric motor so that the electric motor is regeneratively controlled with a low efficiency gear ratio;
A method for controlling a vehicle.

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