Control system for hybrid vehicles

Abstract

To provide a control device for hybrid vehicles that can prevent the engine from starting unnecessarily. [Solution] The hybrid vehicle 1 includes an engine 2, an MG1 that generates electricity using the driving force of the engine 2, a battery 3 that is charged with the electricity generated by the MG1, 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 controls the engine start determination conditions to change whether or not to start the engine 2 depending on whether the hybrid vehicle 1 is moving forward or backward.

Description

Technical Field

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

Background Art

[0002] [[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Therefore, conventional hybrid vehicles, when using the same engine starting conditions for both reverse and forward movement, sometimes unnecessarily start the engine when reversing, indicating that there was still room for improvement.

[0007] This invention has been made in view of the above circumstances, and aims to provide a control device for a hybrid vehicle that can suppress the unnecessary starting of the engine. [Means for solving the problem]

[0008] 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 the control device comprises a control unit that controls the engine start determination conditions to determine whether or not to start the engine depending on whether the hybrid vehicle is moving forward or backward. [Effects of the Invention]

[0009] The present invention can provide a control device for a hybrid vehicle that can suppress the engine from starting unnecessarily. [Brief explanation of the drawing]

[0010] [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 flowchart showing the engine start control operation of a control device for a hybrid vehicle according to an embodiment of the present invention. [Modes for carrying out the invention]

[0011] 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 controls the engine start determination conditions to change depending on whether the hybrid vehicle is moving forward or backward, in order to determine whether or not to start the engine. As a result, the control device for a hybrid vehicle according to one embodiment of the present invention can suppress the engine from starting unnecessarily. [Examples]

[0012] 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.

[0013] 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.

[0014] Engine 2 has multiple cylinders. In this embodiment, engine 2 generates power by performing a series of four strokes for each cylinder, consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke.

[0015] Battery 3 is composed of a rechargeable secondary battery, such as a lithium-ion battery. Battery 3 stores the power generated by MG1 and MG2 and supplies power to drive MG1 and MG2.

[0016] MG1 is provided to be interlocked with the crankshaft of the engine 2. MG1 is connected to the battery 3 via the first inverter 5 and the boost converter 8. MG1 has the function of an electric motor that rotates by being supplied with power from the battery 3 to start the engine 2, and the function of a generator that converts the power generated by the engine 2 into electric power. MG1 constitutes the generator in the present invention.

[0017] MG2 is provided to be interlocked with the drive wheels 9 via a power transmission member such as a gear mechanism. MG2 is connected to the battery 3 via the second inverter 7 and the boost converter 8.

[0018] MG2 has the function of an electric motor that rotates by being supplied with power from the battery 3 and MG1 to rotate the drive wheels 9, and the function of a generator that converts the rotational force of the drive wheels 9 into electric power. MG2 constitutes the electric motor in the present invention.

[0019] 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.

[0020] A / C 10 operates with the electric power supplied from the battery 3 and adjusts the temperature inside the vehicle cabin. The DCDC converter 11降压 the electric power stored in the battery 3 and supplies it to the low-voltage battery 12.

[0021] The low-voltage battery 12 stores the electric power supplied to electrical loads such as headlights, lamps, meters provided on the instrument panel, and a car navigation system.

[0022] The DCAC converter 13 converts the electric power stored in the battery 3 from DC to AC electric power and supplies the AC electric power to an electrical load that operates on AC connected to a power outlet provided in the hybrid vehicle 1, for example.

[0023] The HCU 14 is composed of a computer unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data and the like, an input port, and an output port.

[0024] In the ROM of this computer unit, together with various constants and various maps, etc., a program for making the computer unit function as the HCU 14 is stored. That is, by the CPU executing the program stored in the ROM using the RAM as a working area, this computer unit functions as the HCU 14 in this embodiment.

[0025] Connected to the input port of the HCU 14 are various sensors including a shift position sensor 21 for detecting a shift position, a vehicle speed sensor 22 for detecting a vehicle speed, a rotational speed sensor 23 for detecting the rotational speed of MG2 (hereinafter, also simply referred to as "MG2 rotational speed"), a battery sensor 25 for detecting the state of the battery 3 such as the charge and discharge current of the battery 3 and the voltage between the terminals of the battery 3, a temperature sensor 26 for detecting the temperature of the battery 3, and a water temperature sensor 27 for detecting the temperature of the cooling water of the engine 2.

[0026] Connected to the output port of the HCU 14 are various control targets including a first inverter 5, a second inverter 7, a boost converter 8, an A / C 10, an injector 31 for supplying fuel to the engine 2, and a spark plug 32 for igniting in the combustion chamber of the engine 2.

[0027] Note that when the engine 2 is constituted by an engine that does not require a spark plug, such as a diesel engine, etc., the spark plug 32 is removed from the configuration of the hybrid vehicle 1.

[0028] The HCU14 controls various control targets connected to the output port based on information obtained from various sensors connected to the input port. In this embodiment, the HCU14 functions as a control unit 40 that controls the engine start determination conditions to change whether or not to start the engine 2 depending on whether the hybrid vehicle 1 is moving forward or backward.

[0029] The HCU14 determines that the engine start condition has been met if the power required for the MG2 (hereinafter simply referred to as "required power") continues to meet the predetermined conditions for a predetermined time TH or longer.

[0030] The HCU14 determines that the required power meets the predetermined conditions if it is unable to supply power equivalent to the required power from battery 3 to MG2. In other words, the HCU14 determines that the required power meets the predetermined conditions if the required power is greater than the power that can be supplied from battery 3 to MG2.

[0031] In this embodiment, the HCU14 determines whether the required power satisfies the predetermined conditions according to the following equation (1). That is, if equation (1) is true, the HCU14 determines that the required power satisfies the predetermined conditions, and if equation (1) is not true, it determines that the required power does not satisfy the predetermined conditions.

[0032] In equation (1), Mr represents the required power, Mc represents the power output by MG2, Em represents the power that battery 3 can discharge, Ee represents the power required to start engine 2, Mm represents the margin load, and Ec represents the power that battery 3 is discharging.

[0033] Mr-Mc>(Em-Ee-Mm)-Ec (1)

[0034] The HCU14 calculates the required torque, which is the output torque of the MG2 (hereinafter also simply referred to as "MG2 torque"). The HCU14 determines the power Mc output by the MG2 from the MG2 rotational speed detected by the rotational speed sensor 23 and the calculated MG2 torque.

[0035] In this embodiment, the ROM of the HCU14 stores a battery dischargeable power map in which the power Em that the battery 3 can discharge is associated with the temperature of the battery 3. The HCU14 refers to the battery dischargeable power map and determines the power Em that the battery 3 can discharge from the temperature of the battery 3 detected by the temperature sensor 26.

[0036] Furthermore, the ROM of the HCU14 stores an engine startup power map, which associates the power Ee required to start the engine 2 with the temperature of the engine 2's coolant. The HCU14 refers to the engine startup power map and determines the power Ee required to start the engine 2 from the temperature of the coolant detected by the water temperature sensor 27.

[0037] The margin load Mm is set to prevent excessive discharge of the battery 3. In this embodiment, the margin load Mm is a constant value. For example, the margin load Mm includes the load of the MG1 driven when starting the engine 2. The HCU 14 determines the power Ec being discharged by the battery 3 from the charge / discharge current and terminal voltage of the battery 3 detected by the battery sensor 25.

[0038] The ROM of the HCU14 stores multiple hold time maps, each associating a predetermined time TH with the vehicle speed, the requested power Mr, and the State of Charge (SOC) of the battery 3. In this embodiment, the ROM of the HCU14 stores a hold time map for forward movement and a hold time map for reverse movement.

[0039] In each hold time map, the predetermined time TH is associated with decreasing vehicle speed, and also with decreasing required power Mr, and also with decreasing State of Charge (SOC) of battery 3.

[0040] The hold time map for reverse gear has each predetermined time TH set to be longer than the hold time map for forward gear. In other words, even if the vehicle speed, required power Mr, and the state of charge of battery 3 are the same, the predetermined time TH associated with the hold time map for reverse gear is set to be longer than the predetermined time TH associated with the hold time map for forward gear.

[0041] The HCU14 selects a hold time map for forward gears if the shift position detected by the shift position sensor 21 corresponds to a forward gear, and selects a hold time map for reverse gears if the shift position detected by the shift position sensor 21 corresponds to a reverse gear.

[0042] In this way, the HCU14 controls the engine start determination conditions, which determine whether or not to start the engine 2, by selecting a hold time map depending on whether the hybrid vehicle 1 is moving forward or backward.

[0043] The engine start control operation of the HCU14 configured as described above will be explained with reference to Figure 2. Note that the engine start control operation described below is repeatedly executed throughout the period when engine 2 is stopped.

[0044] First, in S1, the HCU14 determines whether the required power meets the predetermined conditions. That is, in S1, the HCU14 determines whether the above-mentioned equation (1) is true.

[0045] In S1, if it is determined that the required power meets the predetermined conditions, that is, if equation (1) is true, the HCU14 executes the process in S2. In S1, if it is determined that the required power does not meet the predetermined conditions, that is, if equation (1) is not true, the HCU14 terminates the engine start control operation.

[0046] In S2, the HCU 14 sets a predetermined time TH according to the direction of travel of the hybrid vehicle 1. Specifically, in S2, the HCU 14 selects a hold time map based on the shift position detected by the shift position sensor 21, and sets a predetermined time TH from the selected hold time map. After executing the process in S2, the HCU 14 executes the process in S3.

[0047] In S3, the HCU14 determines whether the duration for which the required power meets the predetermined conditions has exceeded a predetermined time TH. In other words, the HCU14 determines whether the duration is longer than the predetermined time TH.

[0048] In S3, if it is determined that the duration has exceeded the predetermined time TH, the HCU14 determines that the engine start condition has been met and executes the process in S4. In S3, if it is determined that the duration has not exceeded the predetermined time TH, the HCU14 executes the process in S1.

[0049] In S4, the HCU14 starts the engine 2. Specifically, in S4, the HCU14 controls the first inverter 5 to drive the MG1, thereby rotating the crankshaft of the engine 2 and starting the fuel supply by the injector 31 and ignition by the spark plug 32, thus starting the engine 2. After executing the process in S4, the HCU14 terminates the engine start control operation.

[0050] As described above, the control device for the hybrid vehicle according to this embodiment controls the engine start determination conditions to change depending on whether the hybrid vehicle 1 is moving forward or backward, thereby preventing the engine 2 from starting unnecessarily.

[0051] Furthermore, the control device for the hybrid vehicle according to this embodiment sets a predetermined time TH to a different time depending on whether the hybrid vehicle 1 is moving forward or backward, thereby preventing the engine 2 from starting unnecessarily.

[0052] Furthermore, the control device for the hybrid vehicle according to this embodiment sets the predetermined time TH to be longer when the hybrid vehicle 1 is moving in reverse than when the hybrid vehicle 1 is moving forward. This makes it possible to suppress the starting of the engine 2 when the hybrid vehicle 1 is parked and there is a high probability that the engine 2 will be stopped in a short time.

[0053] Furthermore, the control device for the hybrid vehicle according to this embodiment sets the predetermined time TH to be longer as the vehicle speed decreases, so it can suppress the starting of the engine 2 when the hybrid vehicle 1 is parked and there is a high probability that the engine 2 will be stopped in a short time.

[0054] In this embodiment, an example was described in which the HCU 14 selects a hold time map depending on whether the hybrid vehicle 1 is moving forward or backward. However, the HCU 14 may be configured to switch between a first mode in which it selects a hold time map depending on whether the hybrid vehicle 1 is moving forward or backward, and a second mode in which it selects a hold time map for forward movement regardless of the direction of travel of the hybrid vehicle 1. For example, the HCU 14 may be configured to switch between the first mode and the second mode using a switch provided on the instrument panel of the hybrid vehicle 1.

[0055] 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]

[0056] 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 comprising a control unit that controls the engine start determination conditions to change depending on whether the hybrid vehicle is moving forward or backward, in order to determine whether or not to start the engine.

2. The control unit, If the power required for the electric motor remains at a predetermined level for a predetermined period of time, it is determined that the engine start condition has been met. The control device for a hybrid vehicle according to claim 1, characterized in that the predetermined time is set to different times depending on whether the hybrid vehicle is moving forward or backward.

3. The control device for a hybrid vehicle according to claim 2, characterized in that the control unit sets the predetermined time to be longer when the hybrid vehicle is moving in reverse than when the hybrid vehicle is moving forward.

4. The control device for a hybrid vehicle according to claim 3, characterized in that the control unit sets the predetermined time to be longer as the vehicle speed decreases.

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