JP7753043B2 - Hybrid vehicle control device - Google Patents

Description

The present invention relates to a control device for a hybrid vehicle.

A hybrid vehicle equipped with a series hybrid system includes, for example, an engine, a generator motor that generates electricity using engine power, a drive motor that generates driving force for traveling, and a battery that stores the electricity supplied to the drive motor. In addition, multiple gears are provided between the drive motor and the wheels.

Such hybrid vehicles operate in powered mode when accelerating and in regenerative mode when decelerating, converting the energy generated by deceleration into electricity and storing it in the battery, allowing them to run efficiently.

International Publication No. 2015/080021

However, in the hybrid vehicles mentioned above, shocks and noise can occur due to gear backlash (gap) when switching between powered and regenerative driving. In particular, in series hybrid systems directly connected to the motor, the good responsiveness (acceleration and deceleration performance) of the drive motor can result in louder shocks and noise.

One way to address this issue is to reduce the time rate of change of the drive motor's torque, but this has the problem of reducing responsiveness. Another physical solution is to eliminate gear backlash, but this has the problem of being very costly.

The object of the present invention is to provide a hybrid vehicle control device that is low-cost, reduces the impact and noise caused by gear backlash, and suppresses a decrease in responsiveness.

To achieve the above object, the present invention provides a control device for a hybrid vehicle, which is used in a hybrid vehicle equipped with an engine, a generator motor that generates electricity using power from the engine, a drive motor that generates power for driving, and a battery that stores the electricity, with multiple gears provided between the drive motor and the wheels. The control device includes: a required torque calculation means that calculates a required torque indicating a torque required of the drive motor in accordance with the vehicle speed and accelerator pedal depression of the hybrid vehicle; a target torque calculation means that calculates a target torque that is a control target value for changing the torque of the drive motor from a current torque to the required torque; and a drive motor control means that controls the drive motor using the target torque. The target torque calculation means makes the time rate of change of the target torque smaller when the target torque is within a predetermined range that straddles zero torque than when the target torque is not within the predetermined range , and changes the predetermined range in accordance with the vehicle speed of the hybrid vehicle, narrowing the predetermined range as the vehicle speed increases .

With this configuration, the time rate of change of the target torque is reduced within a specified range that crosses over zero torque, thereby reducing the impact and noise caused by gear backlash. Furthermore, because the time rate of change of the target torque is not reduced outside the specified range, the reduction in responsiveness can be minimized. Furthermore, since no physical measures are required, costs can be kept low.

Furthermore, in the above-mentioned control device, the target torque calculation means may change the time rate of change of the target torque when it is within the predetermined range in accordance with the vehicle speed of the hybrid vehicle and/or the required torque.

With this configuration, the time rate of change of the target torque when within a specified range can be flexibly changed according to the vehicle speed and required torque of the hybrid vehicle.

Furthermore, in the above-mentioned control device, the target torque calculation means may change the predetermined range depending on the vehicle speed of the hybrid vehicle.

This configuration allows the above-mentioned predetermined range to be flexibly changed depending on the vehicle speed of the hybrid vehicle.

This invention makes it possible to reduce the impact and noise caused by gear backlash in hybrid vehicles at low cost, while also preventing a decrease in responsiveness.

FIG. 1 is a block diagram showing the configuration of a hybrid vehicle to which a control device according to an embodiment of the present invention is applied. FIG. 2 is an explanatory diagram of the mechanism by which shock and noise are generated due to gear backlash. FIG. 3 is a graph showing how the target torque changes when the required torque increases in the embodiment. FIG. 4 is a graph showing how the target torque changes when the required torque decreases in this embodiment. FIG. 5 is a flowchart showing the processing by the control device in the embodiment.

The following describes in detail an embodiment of the present invention with reference to the accompanying drawings.

<Hybrid vehicle>
FIG. 1 is a block diagram showing the configuration of a hybrid vehicle 1 to which a control device according to an embodiment of the present invention is applied.

The hybrid vehicle 1 is equipped with a series hybrid system 2. The hybrid system 2 includes an engine 11, a generator motor (MG1) 12, a drive motor (MG2) 13, a battery 14, and a PCU (Power Control Unit) 15.

The engine 11 is, for example, a gasoline engine.

The generator motor 12 is, for example, a permanent magnet synchronous motor. The rotating shaft of the generator motor 12 is mechanically connected to the crankshaft of the engine 11 via a gear (not shown). For example, an engine output gear is supported on the crankshaft of the engine 11 so as not to rotate relative to it, and a motor gear is supported on the rotating shaft of the generator motor 12 so as not to rotate relative to it, and the engine output gear and motor gear are meshed.

The drive motor 13 is, for example, a permanent magnet synchronous motor that is larger than the generator motor 12. The rotating shaft of the drive motor 13 is connected to the drive system 16 of the hybrid vehicle 1. The drive system 16 includes gears 41a and 41b (an example of multiple gears, such as a differential gear). The power of the drive motor 13 is transmitted to the drive wheels 17 via gears 41a and 41b. This causes the drive wheels 17 to rotate, causing the hybrid vehicle 1 to move forward or backward.

Battery 14 is a battery pack made up of multiple secondary batteries. The secondary batteries are, for example, lithium-ion batteries. Battery 14 outputs DC power of, for example, approximately 200 to 350 V (volts).

The PCU 15 is a unit for controlling the operation of the generator motor 12 and the drive motor 13, and is equipped with a first inverter 21, a second inverter 22, and a converter 23.

When starting the engine 11, the DC power output from the battery 14 is boosted by the converter 23, the boosted DC power is converted to AC power by the first inverter 21, and the AC power is supplied to the generator motor 12. This causes the generator motor 12 to operate in powered mode, and the engine 11 is motored (cranked) by the generator motor 12. When the rotation speed of the crankshaft of the engine 11 has increased to the rotation speed required for starting due to motoring, the engine 11 starts when the spark plug of the engine 11 is fired.

When the hybrid vehicle 1 is running, the drive motor 13 is powered and generates power.

When the output required of the drive motor 13 is less than the output of the battery 14, the hybrid vehicle 1 runs in EV mode. That is, the engine 11 is stopped, no power is generated by the generator motor 12, and power is supplied from the battery 14 to the drive motor 13, which then drives the drive motor 13.

On the other hand, when the output required of the drive motor 13 exceeds the output of the battery 14, the hybrid vehicle 1 operates in HV mode. That is, the engine 11 is operated and the generator motor 12 is operated to generate electricity, so that the power of the engine 11 is converted into AC power by the generator motor 12. The AC power from the generator motor 12 is then converted into DC power by the first inverter 21, and the DC power output from the first inverter 21 is converted into AC power by the second inverter 22. This AC power is then supplied to the drive motor 13, driving it.

Furthermore, when the remaining capacity of the battery 14 falls below a predetermined capacity, the generator motor 12 operates to generate electricity while the engine 11 is running, regardless of whether the drive motor 13 is running or stopped. At this time, the AC power from the generator motor 12 is converted to DC power by the first inverter 21, and the DC power output from the first inverter 21 is stepped down by the converter 23. The stepped-down DC power is then supplied to the battery 14, thereby charging the battery 14.

When the hybrid vehicle 1 decelerates, the drive motor 13 operates in regenerative mode, and the power transmitted from the drive wheels 17 to the drive motor 13 is converted into AC power. At this time, the drive motor 13 acts as a resistor in the driving system, and this resistance acts as a braking force (regenerative braking force) that brakes the hybrid vehicle 1. At this time, in the PCU 15, the AC power supplied from the drive motor 13 to the second inverter 22 is converted into DC power by the second inverter 22, and the DC power output from the second inverter 22 is stepped down by the converter 23. The stepped-down DC power is then supplied to the battery 14, charging it.

The hybrid vehicle 1 is equipped with multiple ECUs (Electronic Control Units). Each ECU has a microcontroller unit (microcomputer). The microcomputer has, for example, a central processing unit (CPU), non-volatile memory such as flash memory, and volatile memory such as dynamic random access memory (DRAM). The multiple ECUs are connected to enable bidirectional communication using the CAN (Controller Area Network) communication protocol. Various sensors required for control are connected to each ECU, and detection signals from the connected sensors are input. In addition to the detection signals input from the various sensors, each ECU also receives information required for control from other ECUs.

Of the multiple ECUs, Figure 1 shows ECU 31 (an example of a control device, required torque calculation means, target torque calculation means, and drive motor control means) that controls hybrid system 2. An accelerator sensor 32 and a vehicle speed sensor 33 are connected to ECU 31. Accelerator sensor 32 outputs a detection signal corresponding to the amount of operation of the accelerator pedal operated by the driver. Vehicle speed sensor 33 outputs a detection signal, a pulse signal synchronized with the rotation of a rotor that rotates as hybrid vehicle 1 travels.

The ECU 31 calculates the accelerator opening, which is the ratio of the current accelerator pedal operation amount to the maximum accelerator pedal operation amount, based on the detection signal from the accelerator sensor 32. The ECU 31 also calculates the frequency of the detection signal (pulse signal) from the vehicle speed sensor 33, and converts this frequency into vehicle speed to calculate the vehicle speed.

In such a hybrid vehicle 1, when switching between power running and regenerative running, shocks and noise may occur due to backlash (gap) between gears 41a and 41b (see Figure 2). In particular, in a series hybrid system directly connected to the drive motor 13, the good responsiveness of the drive motor 13 can result in louder shocks and noise.

One way to address this issue is to reduce the time rate of change of the drive motor's torque, but this has the problem of reducing responsiveness (acceleration and deceleration performance). Another physical solution is to eliminate gear backlash, but this has the problem of being very costly.

The following describes a technology that can reduce the impact and noise caused by gear backlash (hereinafter simply referred to as "impact and noise") at low cost and prevent a decrease in responsiveness.

In the following, reference will be made to Figures 3 and 4 as appropriate. Figure 3 is a graph showing how the target torque changes when the required torque increases in this embodiment. Figure 4 is a graph showing how the target torque changes when the required torque decreases in this embodiment.

The ECU 31 stores a predetermined range that crosses over zero torque for the target torque for the drive motor 13. In Figures 3 and 4, the predetermined range extends from an upper limit value U to a lower limit value D. The specific values of the upper limit value U and the lower limit value D can be determined in advance, for example, through an experiment using the hybrid vehicle 1. In this experiment, the upper limit value U and the lower limit value D are determined based on, for example, the degree of discomfort felt by the driver in response to impacts and sounds.

The ECU 31 calculates the required torque RT (Figures 3 and 4), which indicates the torque required of the drive motor 13, based on the vehicle speed and accelerator opening AO (Figures 3 and 4) of the hybrid vehicle 1.

The ECU 31 calculates the target torque (command torque), which is a control target value for changing the torque of the drive motor 13 from the current torque to the required torque RT. The ECU 31 controls the drive motor 13 using the target torque.

In Figures 3 and 4, target torque C is the target torque for the conventional technology, and target torque T is the target torque for this embodiment.

For example, in Figure 3, in the prior art, after time t1, the target torque C is increased at the same time rate until it reaches the required torque RT.

On the other hand, in this embodiment, after time t1, the ECU 31 increases the target torque T until it reaches the required torque RT, but sets the time rate of change of the target torque T when it is within the specified range to be smaller than the time rate of change of the target torque T when it is not within the specified range. In other words, the time rate of change of the target torque T from time t2 to time t3 is smaller than the time rate of change of the target torque T in the time periods before and after that.

Also, for example, in Figure 4, in the prior art, after time t11, the target torque C is decreased at the same time change rate until it reaches the required torque RT.

On the other hand, in this embodiment, after time t11, the ECU 31 decreases the target torque T until it reaches the required torque RT, but sets the time rate of change of the target torque T when it is within the specified range to be smaller than the time rate of change of the target torque T when it is not within the specified range. In other words, the time rate of change of the target torque T from time t12 to time t13 is smaller than the time rate of change of the target torque T in the time periods before and after that.

In this way, by reducing the time rate of change of the target torque T within a specified range that crosses over zero torque, it is possible to reduce the impact and noise caused by backlash.

The ECU 31 may also change the time rate of change of the target torque T when it is within a predetermined range in accordance with the vehicle speed of the hybrid vehicle 1 and/or the required torque RT. For example, when the vehicle speed is high, shocks and sounds are easily lost in the vehicle's behavior. Therefore, by increasing the time rate of change of the target torque T, responsiveness can be improved and the driver's discomfort caused by shocks and sounds can be minimized. Specifically, the ECU 31 can achieve such control using, for example, a map, function, information table, etc. that indicates the relationship between the vehicle speed and the time rate of change of the target torque T.

Furthermore, for example, if the required torque RT is large, it is considered that the driver desires large torque (acceleration, deceleration), and therefore the driver's desire can be reflected in torque control by increasing the time rate of change of the target torque. Specifically, the ECU 31 can achieve such control using, for example, a map, function, information table, etc. that indicates the relationship between the magnitude of the required torque RT and the time rate of change of the target torque T.

Furthermore, for example, the ECU 31 may change the predetermined range depending on the vehicle speed of the hybrid vehicle 1. As a result, for example, when the vehicle speed is high, shocks and sounds are easily lost in the vehicle's behavior, so by narrowing the predetermined range, responsiveness can be improved and the discomfort felt by the driver due to shocks and sounds can be reduced. Specifically, the ECU 31 can achieve such control using, for example, a map, function, information table, etc. that indicates the relationship between the vehicle speed and the upper limit value U and lower limit value D of the predetermined range.

Next, the processing performed by the control device in this embodiment will be described with reference to Figure 5. Figure 5 is a flowchart showing the processing performed by the control device in this embodiment. Note that the ECU 31 is assumed to constantly calculate the vehicle speed of the hybrid vehicle 1.

In step S1, the ECU 31 detects accelerator operation. That is, the ECU 31 receives a detection signal from the accelerator sensor 32 corresponding to the amount of accelerator pedal operation, and calculates the accelerator opening degree based on that detection signal.

Next, in step S2, the ECU 31 calculates the required torque RT (Figures 3 and 4) of the drive motor 13 based on the vehicle speed and accelerator opening AO (Figures 3 and 4) of the hybrid vehicle 1.

Next, in step S3, the ECU 31 performs rate processing, which is processing related to the time rate of change of the target torque T.

Next, in step S4, the ECU 31 calculates the target torque T. In this case, the ECU 31 sets the time rate of change of the target torque T when it is within the predetermined range to be smaller than the time rate of change of the target torque T when it is not within the predetermined range (Figures 3 and 4).

Next, in step S5, the ECU 31 issues an instruction to the drive motor 13 based on the target torque T calculated in step S4. In response, the drive motor 13 generates torque based on the target torque T.

<Action and effect>
As described above, the control device for the hybrid vehicle 1 of this embodiment reduces the time rate of change of the target torque within a predetermined range that crosses over zero torque, thereby reducing the impact and noise caused by gear backlash. Furthermore, since the time rate of change of the target torque is not reduced outside the predetermined range, the reduction in responsiveness can be minimized. Furthermore, since no physical measures are required, costs can be kept low.

Furthermore, for example, the time rate of change of the target torque when within a specified range may be changed according to the vehicle speed and/or required torque of the hybrid vehicle. As a result, for example, when the vehicle speed is high, shocks and sounds are easily lost in the vehicle's behavior, so by increasing the time rate of change of the target torque, responsiveness can be improved and the discomfort felt by the driver due to shocks and sounds can be minimized. Furthermore, for example, when the required torque is high, it is likely that the driver desires a high torque, so by increasing the time rate of change of the target torque, the driver's wishes can be reflected in the torque control.

The specified range may also be changed depending on the vehicle speed of the hybrid vehicle. For example, when the vehicle speed is high, shocks and sounds can easily be lost in the vehicle's behavior. Therefore, by narrowing the specified range, responsiveness can be improved and the driver's discomfort caused by shocks and sounds can be minimized.

The program executed by the control device of this embodiment can be provided by recording it in an installable or executable file format on a recording medium readable by a computer device, such as a CD (Compact Disc)-ROM (Read Only Memory), a flexible disk (FD), a CD-R (Recordable), or a DVD (Digital Versatile Disk). The program may also be provided or distributed via a network such as the Internet.

Although an embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be embodied in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as set forth in the claims.

For example, in the above embodiment, we have described the reduction of impacts and noise caused by backlash (gap) between gears 41a and 41b, but similarly, impacts and noise caused by gaps (play) between the rotating shaft and bearings in the drive motor 13 can also be reduced.

Furthermore, the specified range when torque increases (Figure 3) and the specified range when torque decreases (Figure 4) may be the same or different.

1... Hybrid vehicle 11... Engine 12... Generator motor 13... Drive motor 14... Battery (cell) 15... PCU 31... ECU (control device, required torque calculation means, target torque calculation means, drive motor control means)

Claims (3)

A control device used in a hybrid vehicle equipped with an engine, a generator motor that generates electricity using power from the engine, a drive motor that generates power for traveling, and a battery that stores electricity, and in which a plurality of gears are provided between the drive motor and wheels,
a required torque calculation means for calculating a required torque indicating a torque required for the drive motor in accordance with a vehicle speed and an accelerator opening of the hybrid vehicle;
a target torque calculation means for calculating a target torque, which is a control target value for changing the torque of the drive motor from a current torque to the required torque;
a drive motor control means for controlling the drive motor using the target torque,
The target torque calculation means, when the target torque is within a predetermined range straddling zero torque, makes the time rate of change of the target torque smaller than the time rate of change of the target torque when the target torque is not within the predetermined range , and changes the predetermined range in accordance with the vehicle speed of the hybrid vehicle, narrowing the predetermined range as the vehicle speed increases . A control device for a hybrid vehicle as described in claim 1, wherein the target torque calculation means changes the time rate of change of the target torque when it is within the predetermined range in accordance with the vehicle speed of the hybrid vehicle and/or the required torque. 2. The control device for a hybrid vehicle according to claim 1, wherein the target torque calculation means changes a time rate of change of the target torque when the target torque is within the predetermined range in accordance with a vehicle speed of the hybrid vehicle, and increases the time rate of change of the target torque when the target torque is within the predetermined range as the vehicle speed increases.