Hybrid vehicle control device

Abstract

To reduce impact and sound caused by backlash of a gear and suppress deterioration in responsiveness, at low costs, in a hybrid vehicle.SOLUTION: A control device of a hybrid vehicle is used in a hybrid vehicle that is mounted with an engine, a power generating motor that generates electric power by power of the engine, a driving motor that generates power for travelling and a battery that stores electric power, where a plurality of gears are provided between the driving motor and a wheel. The control device calculates required torque indicating torque required by the driving motor, in accordance with a vehicle speed and accelerator aperture of the hybrid vehicle; calculates target torque which is a control target value for varying torque of the driving motor from current torque to the required torque; controls the driving motor using the target torque; and when the target torque is in a predetermined range in which the target torque strides across predetermined zero torque, makes a change rate with time of the target torque smaller than a change rate with time of the target torque set at the time when the target torque is not in the predetermined range.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a control device for a hybrid vehicle. [Background technology]

[0002] 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.

[0003] 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 a battery, allowing them to travel efficiently. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2015 / 080021 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned hybrid vehicles, shocks and noise can occur due to gear backlash (gap) when switching between power running and regenerative running. 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 large shocks and noise.

[0006] One way to address this issue is to reduce the time rate of change of the drive motor torque, but this reduces responsiveness.Another physical solution is to eliminate gear backlash, but this is costly.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a control device for a hybrid vehicle that is low-cost and can reduce the impact and noise caused by gear backlash and suppress a decrease in responsiveness. [Means for solving the problem]

[0008] To achieve the above object, the control device for a hybrid vehicle according to the present invention 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 the torque required of the drive motor in accordance with the vehicle speed and accelerator pedal position 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 the 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 sets the time rate of change of the target torque smaller when the target torque is within a predetermined range that crosses zero torque than when the target torque is not within the predetermined range. The predetermined range is changed in accordance with the vehicle speed of the hybrid vehicle, and the predetermined range is narrowed as the vehicle speed increases. do.

[0009] With this configuration, the time rate of change of the target torque is reduced 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.

[0010] In addition, 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 depending on the vehicle speed of the hybrid vehicle and / or the required torque.

[0011] According to this configuration, the time rate of change of the target torque when it is within the predetermined range can be flexibly changed according to the vehicle speed and required torque of the hybrid vehicle.

[0012] In the above-described control device, the target torque calculation means may change the predetermined range in accordance with the vehicle speed of the hybrid vehicle.

[0013] According to this configuration, the above-mentioned predetermined range can be flexibly changed in accordance with the vehicle speed of the hybrid vehicle. [Effects of the Invention]

[0014] According to the present invention, in a hybrid vehicle, it is possible to reduce shocks and noise caused by gear backlash at low cost and to suppress a decrease in responsiveness. [Brief explanation of the drawings]

[0015] [Figure 1] 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. [Figure 2] Figure 2 is an explanatory diagram of the mechanism by which shock and noise are generated due to gear backlash. [Figure 3] FIG. 3 is a graph showing how the target torque changes when the required torque increases in the embodiment. [Figure 4] FIG. 4 is a graph showing how the target torque changes when the required torque decreases in the embodiment. [Figure 5] FIG. 5 is a flowchart showing the processing by the control device in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0017] <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.

[0018] 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.

[0019] The engine 11 is, for example, a gasoline engine.

[0020] 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 the motor gear are meshed.

[0021] 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 a drive system 16 of the hybrid vehicle 1. The drive system 16 includes gears 41a and 41b (examples of multiple gears, such as a differential gear). The power of the drive motor 13 is transmitted to drive wheels 17 via the gears 41a and 41b. This causes the drive wheels 17 to rotate, causing the hybrid vehicle 1 to move forward or backward.

[0022] The battery 14 is a battery pack made up of a combination of a plurality of secondary batteries. The secondary batteries are, for example, lithium ion batteries. The battery 14 outputs DC power of, for example, about 200 to 350 V (volts).

[0023] The PCU 15 is a unit for controlling the driving of the generator motor 12 and the drive motor 13, and includes a first inverter 21, a second inverter 22, and a converter .

[0024] 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 into 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 perform power running, 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 ignition plug of the engine 11 is sparked, and the engine 11 starts.

[0025] When the hybrid vehicle 1 is traveling, the drive motor 13 is operated in a power running mode, and the drive motor 13 generates power.

[0026] When the output required of the drive motor 13 is smaller than the output of the battery 14, the hybrid vehicle 1 runs in EV mode. That is, the engine 11 is stopped, the generator motor 12 does not generate electricity, and power is supplied from the battery 14 to the drive motor 13, which is then driven by the power.

[0027] On the other hand, when the output required of the drive motor 13 exceeds the output of the battery 14, the hybrid vehicle 1 runs 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. The AC power is supplied to the drive motor 13, thereby driving the drive motor 13.

[0028] 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, 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 supplied to the battery 14, thereby charging the battery 14.

[0029] When the hybrid vehicle 1 decelerates, the drive motor 13 undergoes regenerative operation, and 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 traveling drive 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, thereby charging the battery 14.

[0030] The hybrid vehicle 1 is equipped with a plurality of ECUs (Electronic Control Units). Each ECU has a microcontroller unit (microcomputer). The microcomputer has, for example, a central processing unit (CPU), a nonvolatile memory such as a flash memory, and a volatile memory such as a dynamic random access memory (DRAM). The plurality of ECUs are connected to enable bidirectional communication using the controller area network (CAN) communication protocol. Each ECU is connected to various sensors required for control, and receives detection signals from the connected sensors. In addition to the detection signals received from the various sensors, each ECU also receives information required for control from other ECUs.

[0031] 1 shows an ECU 31 (an example of a control device, a required torque calculation means, a target torque calculation means, and a drive motor control means) that controls the hybrid system 2 out of the multiple ECUs. An accelerator sensor 32 and a vehicle speed sensor 33 are connected to the ECU 31. The accelerator sensor 32 outputs a detection signal corresponding to the amount of operation of the accelerator pedal operated by the driver. The vehicle speed sensor 33 outputs a pulse signal as a detection signal that is synchronized with the rotation of a rotor that rotates as the hybrid vehicle 1 travels.

[0032] The ECU 31 calculates the accelerator opening, which is the ratio of the current operation amount to the maximum operation amount of the accelerator pedal, based on the detection signal of the accelerator sensor 32. Furthermore, the ECU 31 calculates the frequency of the detection signal (pulse signal) of the vehicle speed sensor 33 based on the detection signal, and converts the frequency into vehicle speed, thereby calculating the vehicle speed.

[0033] 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 FIG. 2). In particular, in a series hybrid system directly connected to drive motor 13, the good responsiveness of drive motor 13 may result in large shocks and noise.

[0034] One way to address this issue is to reduce the time rate of change of the drive motor's torque, but this reduces responsiveness (acceleration and deceleration performance).Another physical solution is to eliminate gear backlash, but this is costly.

[0035] Therefore, below we will explain 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 suppress a decrease in responsiveness.

[0036] In the following, Figures 3 and 4 will be referred to as appropriate. Figure 3 is a graph showing how the target torque changes when the required torque increases in the embodiment. Figure 4 is a graph showing how the target torque changes when the required torque decreases in the embodiment.

[0037] 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. Note that 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 an impact or sound.

[0038] The ECU 31 calculates a required torque RT (FIGS. 3 and 4) that indicates the torque required of the drive motor 13, in accordance with the vehicle speed of the hybrid vehicle 1 and the accelerator opening AO (FIGS. 3 and 4).

[0039] The ECU 31 calculates a target torque (command torque) that 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.

[0040] In addition, in FIG. 3 and FIG. 4, the target torque C is the target torque in the case of the conventional technology, and the target torque T is the target torque in the case of this embodiment.

[0041] For example, in FIG. 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.

[0042] 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 predetermined range to be smaller than the time rate of change of the target torque T when it is not within the predetermined 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.

[0043] Also, for example, in FIG. 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.

[0044] 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 predetermined range to be smaller than the time rate of change of the target torque T when it is not within the predetermined 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.

[0045] In this way, by reducing the time change rate of the target torque T within a predetermined range that crosses over 0 torque, it is possible to reduce the impact and noise caused by backlash.

[0046] Furthermore, the ECU 31 may 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 hidden in the vehicle behavior. Therefore, by increasing the time rate of change of the target torque T, responsiveness can be improved and 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, or the like that indicates the relationship between the magnitude of the vehicle speed and the time rate of change of the target torque T.

[0047] Furthermore, for example, when the required torque RT is large, it is considered that the driver desires a large torque (acceleration, deceleration), and therefore the driver's desire can be reflected in the torque control by increasing the time rate of change of the target torque. Specifically, the ECU 31 can realize such control by, for example, a map, function, information table, etc., which indicates the relationship between the magnitude of the required torque RT and the time rate of change of the target torque T.

[0048] Furthermore, for example, the ECU 31 may change the predetermined range in accordance with the vehicle speed of the hybrid vehicle 1. As a result, for example, when the vehicle speed is high, shocks and sounds are easily hidden in the vehicle behavior, so by narrowing the predetermined range, responsiveness can be improved and 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, or the like that indicates the relationship between the vehicle speed and the upper limit value U and lower limit value D of the predetermined range.

[0049] Next, processing by the control device in the embodiment will be described with reference to Fig. 5. Fig. 5 is a flowchart showing processing by the control device in the embodiment. It is assumed that the ECU 31 constantly calculates the vehicle speed of the hybrid vehicle 1.

[0050] In step S1, the ECU 31 detects the accelerator operation, that is, receives a detection signal corresponding to the accelerator pedal operation amount from the accelerator sensor 32, and calculates the accelerator opening degree based on the detection signal.

[0051] Next, in step S2, the ECU 31 calculates the required torque RT (FIGS. 3 and 4) of the drive motor 13 in accordance with the vehicle speed of the hybrid vehicle 1 and the accelerator opening AO (FIGS. 3 and 4).

[0052] 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.

[0053] 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 a predetermined range to be smaller than the time rate of change of the target torque T when it is not within the predetermined range (FIGS. 3 and 4).

[0054] 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 to this, the drive motor 13 generates torque based on the target torque T.

[0055] <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.

[0056] Furthermore, for example, the time rate of change of the target torque when it is within a predetermined range may be changed according to the vehicle speed and / or the required torque of the hybrid vehicle. For example, when the vehicle speed is high, shocks and noises are easily hidden in the vehicle behavior. Therefore, by increasing the time rate of change of the target torque, responsiveness can be improved and the driver's discomfort caused by shocks and noise can be minimized. Furthermore, for example, when the required torque is high, it is considered that the driver desires a high torque. Therefore, by increasing the time rate of change of the target torque, the driver's desires can be reflected in the torque control.

[0057] Furthermore, the predetermined range may be changed according to the vehicle speed of the hybrid vehicle. For example, when the vehicle speed is high, shocks and sounds are easily hidden in the vehicle behavior, so by narrowing the predetermined range, responsiveness can be improved and discomfort to the driver caused by shocks and sounds can be minimized.

[0058] The program executed by the control device of this embodiment can be provided by being recorded in an installable or executable file format on a computer-readable recording medium 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.

[0059] Although the embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. This novel embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims.

[0060] For example, in the above-described embodiment, the reduction of impact and noise caused by backlash (gap) between gears 41a and 41b was described, but similarly, impact and noise caused by gap (play) between the rotating shaft and bearing in drive motor 13 can also be reduced.

[0061] Furthermore, the predetermined range when the torque increases (FIG. 3) and the predetermined range when the torque decreases (FIG. 4) may be the same or different. [Explanation of symbols]

[0062] 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

1. 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.

2. 2. The control device for a hybrid vehicle according to claim 1, wherein the target torque calculation means changes the time rate of change of the target torque when the target torque is within the predetermined range in accordance with the vehicle speed of the hybrid vehicle and / or the required torque.

3. 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.

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