Control system for hybrid vehicles

Abstract

To provide a control device for a hybrid vehicle that can appropriately change the engine speed in response to the driver's acceleration request. [Solution] The hybrid vehicle 1 comprises an engine 2, an MG1 that generates electricity using the driving force of the engine 2, a battery 3 into which the electricity generated by the MG1 is charged, an MG2 that drives the drive wheels 9 using the electricity generated by the MG1 and the electricity charged in the battery 3, and a control unit 40 that sets a target engine rotation speed based on the amount of change in the accelerator opening.

Description

Technical Field

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

Background Art

[0002] Conventionally, there has been proposed in Patent Document 1 a control device for a hybrid vehicle including a drive motor that transmits driving force to drive wheels, a generator, an engine that drives the generator, and a battery that stores electric power, the control device changing the amount of change in the rotational speed of the engine according to the required output of the drive motor. Further, Patent Document 1 proposes that the amount of change in the rotational speed of the engine is increased as the vehicle speed or the accelerator opening degree is higher.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the conventional technology as described above has a problem that it cannot appropriately change the rotational speed of the engine (hereinafter, also referred to as "engine rotational speed") according to the driver's acceleration request.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a control device for a hybrid vehicle that can appropriately change the engine rotational speed according to the driver's acceleration request.

Means for Solving the Problems

[0006] The control device for a hybrid vehicle according to the present invention is a control device for a hybrid vehicle comprising an engine, a generator that generates electricity using the driving force of the engine, a battery that is charged with the electricity generated by the generator, and an electric motor that drives the drive wheels using the electricity generated by the generator and the electricity charged in the battery, and is configured to include a control unit that sets a target engine rotational speed based on the amount of change in the accelerator opening. [Effects of the Invention]

[0007] The present invention can provide a control device for a hybrid vehicle that can appropriately change the engine speed in response to the driver's acceleration request. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram of a hybrid vehicle equipped with a control device for a hybrid vehicle according to an embodiment of the present invention. [Figure 2] Figure 2 is a functional block diagram of the control unit constituting the control device of a hybrid vehicle according to an embodiment of the present invention. [Figure 3] Figure 3 is a functional block diagram of the target power generation calculation unit that constitutes the control device of a hybrid vehicle according to an embodiment of the present invention. [Figure 4] Figure 4 is a conceptual diagram of the first filter time constant map referenced by the control device of a hybrid vehicle according to an embodiment of the present invention. [Figure 5] Figure 5 is a functional block diagram of the target engine speed calculation unit that constitutes the control device of a hybrid vehicle according to an embodiment of the present invention. [Figure 6] Figure 6 is a conceptual diagram of the first time constant map referenced by the control device of a hybrid vehicle according to an embodiment of the present invention. [Figure 7] Figure 7 is a conceptual diagram of a second time constant map referenced by the control device of a hybrid vehicle according to an embodiment of the present invention. [Figure 8]Figure 8 is a conceptual diagram of a weight map referenced by a control device for a hybrid vehicle according to an embodiment of the present invention. [Figure 9] Figure 9 is a flowchart showing the target power generation calculation operation of the control device for a hybrid vehicle according to an embodiment of the present invention. [Figure 10] Figure 10 is a flowchart showing the target engine speed calculation operation of the control device for a hybrid vehicle according to an embodiment of the present invention. [Modes for carrying out the invention]

[0009] A control device for a hybrid vehicle according to one embodiment of the present invention is a control device for a hybrid vehicle comprising an engine, a generator that generates electricity using the driving force of the engine, a battery that is charged with the electricity generated by the generator, and an electric motor that drives the drive wheels using the electricity generated by the generator and the electricity charged in the battery, and is characterized by comprising a control unit that sets a target engine rotational speed based on the amount of change in the accelerator opening. As a result, the control device for a hybrid vehicle according to one embodiment of the present invention can appropriately change the engine rotational speed in response to the driver's acceleration request. [Examples]

[0010] Hereinafter, a hybrid vehicle equipped with a control device for a hybrid vehicle according to an embodiment of the present invention will be described with reference to the drawings.

[0011] As shown in Figure 1, the hybrid vehicle 1 is composed of an engine 2, a battery 3, a first motor 4 (hereinafter also referred to as "MG1"), a first inverter 5, a second motor 6 (hereinafter also referred to as "MG2"), a second inverter 7, a boost converter 8, drive wheels 9, an air conditioner (hereinafter also referred to as "A / C") 10, a DC-DC converter 11, a low-voltage battery 12, a DC-AC converter 13, and a hybrid controller (hereinafter simply referred to as "HCU") 14.

[0012] The engine 2 has a plurality of cylinders formed therein. In the present embodiment, the engine 2 generates power by performing a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke for each cylinder.

[0013] The battery 3 is composed of a rechargeable secondary battery, for example, a lithium-ion battery. The battery 3 stores the electric power generated by the MG1 and the MG2 and supplies the electric power for driving the MG1 and the MG2.

[0014] The MG1 is provided so as to be interlocked with the crankshaft of the engine 2. The MG1 is connected to the battery 3 via the first inverter 5 and the boost converter 8. The MG1 has a function of an electric motor that starts the engine 2 by rotating when electric power is supplied from the battery 3, and a function of a generator that converts the power generated by the engine 2 into electric power. The MG1 constitutes the generator in the present invention.

[0015] The MG2 is provided so as to be interlocked with the drive wheels 9 via a power transmission member such as a gear mechanism. The MG2 is connected to the battery 3 via the second inverter 7 and the boost converter 8.

[0016] The MG2 has a function of an electric motor that rotates the drive wheels 9 by rotating when electric power is supplied from the battery 3 and the MG1, and a function of a generator that converts the rotational force of the drive wheels 9 into electric power. The MG2 constitutes the electric motor in the present invention.

[0017] The boost converter 8 is provided between the battery 3 and the first inverter 5 and the second inverter 7, boosts the voltage of the electric power supplied from the battery 3 to the first inverter 5 and the second inverter 7, and降压 the voltage of the electric power supplied from the first inverter 5 and the second inverter 7 to the battery 3.

[0018] It should be noted that there is an error in the last sentence of the original text. It says "降压" which is not a recognized English word. I translated it as "降压" as it seems to be a wrong or incomplete expression in the original. If it was meant to be "reduce the voltage", the translation would be more accurate.The A / C 10 operates using power supplied from the battery 3 and regulates the temperature inside the vehicle. The DC-DC converter 11 steps down the power stored in the battery 3 and supplies it to the low-voltage battery 12.

[0019] The low-voltage battery 12 stores power supplied to electrical loads such as headlights, lamps and meters on the instrument panel, and the car navigation system.

[0020] The DC-AC converter 13 converts the power stored in the battery 3 from direct current to alternating current, and supplies the alternating current to an AC-operating electrical load connected to an outlet provided in the hybrid vehicle 1, for example.

[0021] The HCU14 consists of a computer unit equipped with a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory for storing backup data, input ports, and output ports.

[0022] The ROM of this computer unit stores various constants and maps, along with a program that allows the computer unit to function as an HCU14. In other words, the CPU executes the program stored in the ROM using RAM as a working area, thereby allowing this computer unit to function as an HCU14 in this embodiment.

[0023] The input ports of the HCU14 are connected to various sensors, including an accelerator pedal position sensor 21 that detects the amount of accelerator pedal operation (hereinafter also simply referred to as "accelerator pedal position"), a vehicle speed sensor 22 that detects vehicle speed, and an MG2 rotational speed sensor 23 that detects the rotational speed of the MG2.

[0024] The output ports of the HCU14 are connected to various control devices, including the first inverter 5, the second inverter 7, the boost converter 8, the A / C 10, the injector 31 that supplies fuel to the engine 2, and the spark plug 32 that ignites in the combustion chamber of the engine 2.

[0025] Furthermore, if engine 2 is composed of an engine that does not require a spark plug, such as a diesel engine, the spark plug 32 is omitted from the configuration of hybrid vehicle 1.

[0026] The HCU14 controls various control targets connected to its output ports based on information obtained from various sensors connected to its input ports. In this embodiment, the HCU14 functions as a control unit 40 that sets a target engine rotational speed based on the amount of change in the accelerator opening. The target engine rotational speed represents the target value of the rotational speed of the engine 2.

[0027] As shown in Figure 2, the control unit 40 includes a driver-required torque calculation unit 41, a driver-required power calculation unit 42, a system-required power calculation unit 43, a target power generation calculation unit 44, and a target engine rotational speed calculation unit 45.

[0028] The driver-requested torque calculation unit 41 calculates the driver-requested torque according to the accelerator opening and vehicle speed. For example, the ROM of the HCU 14 stores a driver-requested torque map in which the driver-requested torque is associated with the accelerator opening and vehicle speed.

[0029] The driver-requested torque calculation unit 41 refers to the driver-requested torque map and calculates the driver-requested torque from the accelerator opening detected by the accelerator opening sensor 21 and the vehicle speed detected by the vehicle speed sensor 22.

[0030] The driver power request calculation unit 42 calculates the driver power request from the product of the driver torque request calculated by the driver torque request calculation unit 41 and the rotational speed of the MG2 detected by the MG2 rotational speed sensor 23.

[0031] The system power requirement calculation unit 43 calculates the system power requirements that are not directly related to the operation of the hybrid vehicle 1. The system power requirements include, for example, the power to charge the battery 3, the power to charge the low-voltage battery 12 connected to the DC-DC converter 11, the power consumed by the electrical load connected to the DC-AC converter 13, and the power consumed by the compressor of the A / C 10.

[0032] The target power generation calculation unit 44 calculates the target power generation from the driver request power calculated by the driver request power calculation unit 42 and the system request power calculated by the system request power calculation unit 43. The target power generation represents the target value of the power generation of MG1.

[0033] As shown in Figure 3, the target power generation calculation unit 44 includes an adder 51, a first filter processing unit 52, and a first filter time constant calculation unit 53. The adder 51 calculates a provisional target power generation by adding the driver's requested power and the system's requested power. The provisional target power generation represents a provisional value of the target power generation.

[0034] The first filter processing unit 52 processes the provisional target power generation calculated by the summing unit 51 using the first filter to calculate the target power generation. The first filter consists of a first-order lag filter.

[0035] The first filter time constant calculation unit 53 calculates the time constant of the first filter. The ROM of the HCU 14 stores a first filter time constant map in which the time constant of the first filter is associated with the accelerator opening angle Acc and the vehicle speed V.

[0036] As shown in Figure 4, in the first filter time constant map, the time constant of the first filter decreases as the accelerator opening Acc increases, at least in some sections. Furthermore, in the first filter time constant map, the time constant of the first filter decreases as the vehicle speed V increases, at least in some sections.

[0037] The first filter time constant calculation unit 53 refers to the first filter time constant map and calculates the time constant of the first filter from the accelerator opening detected by the accelerator opening sensor 21 and the vehicle speed detected by the vehicle speed sensor 22.

[0038] In Figure 2, the target engine rotation speed calculation unit 45 calculates the target engine rotation speed from the target power generation calculated by the target power generation calculation unit 44. As shown in Figure 5, the target engine rotation speed calculation unit 45 includes a provisional target engine rotation speed calculation unit 61, a second filter processing unit 62, and a second filter time constant calculation unit 63.

[0039] The provisional target engine rotation speed calculation unit 61 calculates the provisional target engine rotation speed from the target power generation. The provisional target engine rotation speed represents a provisional value of the target engine rotation speed. The ROM of the HCU 14 stores a provisional target engine rotation speed map in which the provisional target engine rotation speed is associated with the target power generation.

[0040] The provisional target engine rotation speed map defines the engine rotation speed at which the MG1 outputs the target power generation while the engine 2 operates on the optimal operating line. The provisional target engine rotation speed calculation unit 61 refers to the provisional target engine rotation speed map and calculates the provisional target engine rotation speed from the target power generation.

[0041] The second filter processing unit 62 processes the provisional target engine rotation speed calculated by the provisional target engine rotation speed calculation unit 61 using the second filter to calculate the target engine rotation speed. The second filter consists of a first-order lag filter. Furthermore, the second filter constitutes a first-order lag filter in the present invention.

[0042] The second filter time constant calculation unit 63 calculates the time constant of the second filter. The second filter time constant calculation unit 63 includes a first time constant calculation unit 71, a second time constant calculation unit 72, a weight calculation unit 73, and a filter time constant arbitration unit 74.

[0043] The first time constant calculation unit 71 calculates a first time constant to suppress rapid changes in the rotational speed of the engine 2. The ROM of the HCU 14 stores a first time constant map in which the first time constant is associated with the accelerator opening Acc and the vehicle speed V.

[0044] As shown in Figure 6, in the first time constant map, the first time constant decreases as the accelerator opening Acc increases in at least some sections. Furthermore, in the first time constant map, the first time constant decreases as the vehicle speed V increases in at least some sections.

[0045] The first time constant calculation unit 71 refers to the first time constant map and calculates the first time constant from the accelerator opening detected by the accelerator opening sensor 21 and the vehicle speed detected by the vehicle speed sensor 22.

[0046] Thus, the first time constant calculation unit 71 sets the first time constant to a large value when the accelerator opening is small, and to a small value when the accelerator opening is large. Furthermore, the first time constant calculation unit 71 sets the first time constant to a large value when the vehicle speed is low, and to a small value when the vehicle speed is high.

[0047] The second time constant calculation unit 72 calculates the second time constant when rapid acceleration is required. The ROM of the HCU 14 stores a second time constant map in which the second time constant is associated with the change in accelerator opening ΔAcc and the vehicle speed V.

[0048] As shown in Figure 7, in the second time constant map, the second time constant decreases as the change in accelerator opening ΔAcc increases, at least in some sections. Furthermore, in the second time constant map, the second time constant decreases as the vehicle speed V increases, at least in some sections.

[0049] The second time constant calculation unit 72 refers to the second time constant map and calculates the second time constant from the amount of change in accelerator opening detected by the accelerator opening sensor 21 and the vehicle speed detected by the vehicle speed sensor 22.

[0050] Thus, the second time constant calculation unit 72 sets the second time constant to a large value when the change in accelerator opening is small, and to a small value when the change in accelerator opening is large. Furthermore, the second time constant calculation unit 72 sets the second time constant to a large value when the vehicle speed is low, and to a small value when the vehicle speed is high.

[0051] In Figure 5, the weight calculation unit 73 calculates the weight ω of the first time constant calculated by the first time constant calculation unit 71. In this embodiment, the weight ω of the first time constant is represented by a real number between 0 and 1. The weight of the second time constant is represented by (1-ω).

[0052] The ROM of the HCU14 stores a weight map in which weights ω are associated with the accelerator opening Acc. As shown in Figure 8, in the weight map, for at least some sections, the weight ω decreases as the accelerator opening Acc increases. The weight calculation unit 73 refers to the weight map and calculates the weight ω from the accelerator opening detected by the accelerator opening sensor 21.

[0053] In Figure 5, the filter time constant arbitration unit 74 calculates the time constant τ of the second filter according to the following equation (1) from the first time constant τ1 calculated by the first time constant calculation unit 71, the second time constant τ2 calculated by the second time constant calculation unit 72, and the weight ω calculated by the weight calculation unit 73.

[0054] τ = τ1 × ω + τ2 × (1 - ω) (1)

[0055] Thus, the filter time constant arbitration unit 74 calculates the time constant τ of the second filter by taking a weighted average of the first time constant τ1 calculated by the first time constant calculation unit 71 and the second time constant τ2 calculated by the second time constant calculation unit 72.

[0056] The target power generation calculation operation of the HCU14 configured as described above will be explained with reference to Figure 9. The target power generation calculation operation described below will be repeatedly executed throughout the period that the HCU14 is operating.

[0057] First, in S1, HCU14 calculates the provisional target power generation. HCU14 calculates the provisional target power generation by adding the driver's requested power and the system's requested power. After executing the process in S1, HCU14 executes the process in S2.

[0058] In S2, the HCU14 calculates the time constant of the first filter. The HCU14 refers to the first filter time constant map and calculates the time constant of the first filter from the accelerator opening detected by the accelerator opening sensor 21 and the vehicle speed detected by the vehicle speed sensor 22. After executing the process in S2, the HCU14 executes the process in S3.

[0059] In S3, HCU14 calculates the target power generation. HCU14 calculates the target power generation by processing the provisional target power generation using a first filter with the time constant calculated in S2. After executing the process in S3, HCU14 terminates the target power generation calculation operation.

[0060] Next, with reference to Figure 10, the target engine speed calculation operation of HCU14 will be described. The target engine speed calculation operation described below is repeatedly performed throughout the period in which HCU14 is operating, in parallel with the target power generation calculation operation described with reference to Figure 9.

[0061] First, in S11, HCU14 calculates the provisional target engine rotation speed. HCU14 refers to the provisional target engine rotation speed map and calculates the provisional target engine rotation speed from the target power generation calculated in the target power generation calculation operation. After executing the process in S11, HCU14 executes the process in S12.

[0062] In S12, the HCU14 calculates the first time constant. The HCU14 refers to the first time constant map and calculates the first time constant from the accelerator opening detected by the accelerator opening sensor 21 and the vehicle speed detected by the vehicle speed sensor 22. After executing the process in S12, the HCU14 executes the process in S13.

[0063] In S13, the HCU14 calculates the second time constant. The HCU14 refers to the second time constant map and calculates the second time constant from the amount of change in accelerator opening, which is obtained from the accelerator opening detected by the accelerator opening sensor 21, and the vehicle speed detected by the vehicle speed sensor 22.

[0064] In this embodiment, the HCU14 calculates the difference between the accelerator opening when the target engine speed calculation operation was performed in the previous cycle and the accelerator opening when the target engine speed calculation operation was performed in the current cycle as the change in accelerator opening. After executing the process in S13, the HCU14 executes the process in S14.

[0065] In S14, HCU14 calculates the weight of the first time constant. HCU14 refers to the weight map and calculates the weight ω from the accelerator opening detected by the accelerator opening sensor 21. After executing the process in S14, HCU14 executes the process in S15.

[0066] In S15, HCU14 calculates the time constant τ of the second filter. HCU14 calculates the time constant τ of the second filter from the first time constant τ1, the second time constant τ2, and the weight ω according to equation (1) above. After executing the process in S15, HCU14 executes the process in S16.

[0067] In S16, HCU14 calculates the target engine rotational speed. HCU14 calculates the target engine rotational speed by processing the provisional target engine rotational speed with a second filter set to the time constant τ calculated in S15. After executing the process in S16, HCU14 terminates the target engine rotational speed calculation operation.

[0068] In this way, once the target engine rotational speed is calculated by performing the target engine rotational speed calculation operation, the HCU 14 adjusts, for example, the amount of fuel supplied by the injector 31 and the ignition timing of the spark plug 32 so that the rotational speed of the engine 2 becomes the target engine rotational speed.

[0069] As described above, the control device for the hybrid vehicle according to this embodiment sets a target engine speed based on the amount of change in accelerator opening, and therefore can appropriately change the engine speed in response to the driver's acceleration request.

[0070] Furthermore, the control device for the hybrid vehicle according to this embodiment calculates the time constant of the second filter that processes the target engine rotational speed based on the amount of change in the accelerator opening, so that the engine rotational speed can be appropriately changed in response to the driver's acceleration request.

[0071] Furthermore, the control device for the hybrid vehicle according to this embodiment sets the second time constant to a large value when the amount of change in the accelerator opening is small, thereby suppressing abrupt changes in engine speed when the amount of change in the accelerator opening is small.

[0072] Furthermore, the control device for the hybrid vehicle according to this embodiment can suppress rapid changes in engine speed when the amount of change in accelerator opening is small, thereby suppressing the deterioration of NVH (Noise, Vibration, Harshness).

[0073] Furthermore, the control device for the hybrid vehicle according to this embodiment sets the second time constant to a small value when the amount of change in accelerator opening is large, thereby improving the responsiveness of the engine speed to changes in accelerator opening when the amount of change in accelerator opening is large.

[0074] Furthermore, the control device for the hybrid vehicle according to this embodiment calculates the time constant of the second filter by a weighted average of a first time constant corresponding to the accelerator opening and a second time constant corresponding to the change in the accelerator opening. This allows for a smooth transition of the time constant of the second filter between the first and second time constants.

[0075] Furthermore, the control device for the hybrid vehicle according to this embodiment sets the first time constant to a large value when the accelerator opening is small, thereby suppressing abrupt changes in engine speed when the accelerator opening is small.

[0076] Furthermore, the control device for the hybrid vehicle according to this embodiment can suppress rapid changes in engine speed when the accelerator opening is small, thereby suppressing the deterioration of NVH (Noise, Vibration, and Harshness).

[0077] Furthermore, the control device for the hybrid vehicle according to this embodiment can improve the responsiveness of the engine speed to changes in the accelerator opening by setting the first time constant to a small value when the accelerator opening is large.

[0078] In this embodiment, the second filter time constant calculation unit 63 is described as having a first time constant calculation unit 71, a second time constant calculation unit 72, a weight calculation unit 73, and a filter time constant arbitration unit 74.

[0079] Alternatively, a second filter time constant map may be stored in which the time constant of the second filter is associated with the accelerator opening, vehicle speed, and the amount of change in accelerator opening. The second filter time constant calculation unit 63 may then refer to the second filter time constant map and calculate the time constant of the second filter from the accelerator opening, vehicle speed, and the amount of change in accelerator opening.

[0080] Although embodiments of the present invention have been disclosed above, it is clear that modifications can be made to these embodiments without departing from the scope of the present invention. The embodiments of the present invention are disclosed on the premise that equivalents with such modifications are included in the invention described in the claims. [Explanation of symbols]

[0081] 1. Hybrid vehicle 2 engines 3 Batteries 4. First motor (generator) 6. Second motor (electric motor) 9 Drive wheels 40 Control Unit

Claims

1. The engine and A generator that generates electricity using the driving force of the aforementioned engine, A battery that is charged with electricity generated by the aforementioned generator, A control device for a hybrid vehicle, comprising: an electric motor that drives the drive wheels using electricity generated by the generator and electricity charged in the battery, A control device for a hybrid vehicle, characterized by having a control unit that sets a target engine rotational speed based on the amount of change in accelerator pedal opening.

2. The control unit, The aforementioned target engine rotational speed is processed by a first-order lag filter, The control device for a hybrid vehicle according to claim 1, characterized in that the time constant of the first-order lag filter is calculated based on the amount of change in the accelerator opening.

3. The control unit, When the amount of change in the accelerator opening is small, the time constant of the first-order lag filter is set to a large value. The control device for a hybrid vehicle according to claim 2, characterized in that the time constant of the first-order lag filter is set to a small value when the amount of change in the accelerator opening is large.

4. The control unit, The aforementioned target engine rotational speed is processed by a first-order lag filter, Based on the accelerator opening, the first time constant of the first-order lag filter is calculated. The second time constant of the first-order lag filter is calculated based on the amount of change in the accelerator opening. The control device for a hybrid vehicle according to claim 1, characterized in that the time constant of the first-order lag filter is calculated by a weighted average of the first time constant and the second time constant.

5. The control unit, When the accelerator opening is small, the first time constant is set to a large value. The control device for a hybrid vehicle according to claim 4, characterized in that the first time constant is set to a small value when the accelerator opening is large.

Images