Vehicle control system

Abstract

To provide a control device of a vehicle which can balance cooling of an electric motor and power generation by the electric motor.SOLUTION: A control device of a vehicle comprises: an internal combustion engine; an electric motor; and a cooling device. The electric motor is connected with the internal combustion engine. The cooling device is driven by rotation of the electric motor to cool the electric motor. The control device includes: a temperature acquisition part which acquires temperature of the electric motor; and a rotation number control part which controls rotation number of the internal combustion engine. The rotation number control part increases, when the temperature of the electric motor is higher than a first temperature, the rotation number of the internal combustion engine during idling in comparison with a case that the temperature is the first temperature or less.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Vehicles equipped with an internal combustion engine and an electric motor are known (such as Patent Document 1). The battery is charged by the electric power generated by the electric motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The electric motor during power generation also generates heat. For example, by stopping the power generation by the electric motor, heat generation can be suppressed. However, by stopping the power generation, the battery is no longer charged. If the power of the battery becomes insufficient, there is a risk that the vehicle will have difficulty in running. Therefore, the electric motor is cooled. The water-cooled cooling device can control the cooling performance by, for example, the flow rate of a refrigerant such as water. On the other hand, the air-cooled cooling device is driven as the electric motor rotates. Therefore, the cooling performance of the air-cooled electric motor depends on the rotational speed of the electric motor. When the rotational speed is high, the cooling performance becomes high. When the rotational speed is low, the cooling performance decreases. There has been a shortage of cooling performance. Therefore, an object is to provide a control device for a vehicle that can achieve both cooling of the electric motor and power generation by the electric motor.

Means for Solving the Problems

[0005] The above objective can be achieved by a vehicle control device having an internal combustion engine, an electric motor, and a cooling device, wherein the electric motor is connected to the internal combustion engine, the cooling device is driven by the rotation of the electric motor and cools the electric motor, and the control device comprises a temperature acquisition unit for acquiring the temperature of the electric motor and a rotation speed control unit for controlling the rotation speed of the internal combustion engine, wherein when the temperature of the electric motor is higher than a first temperature, the rotation speed control unit increases the rotation speed of the internal combustion engine during idling compared to when the temperature is below the first temperature.

[0006] If the temperature of the electric motor remains higher than the first temperature for a period of time longer than predetermined, the rotational speed control unit may increase the rotational speed of the internal combustion engine during idling.

[0007] If the temperature of the electric motor is lower than or equal to the second temperature, which is lower than the first temperature, the rotational speed of the internal combustion engine during idling may be reduced compared to when the temperature is higher than the first temperature.

[0008] If the temperature of the electric motor is below the first temperature and higher than the second temperature, the rotational speed control unit may maintain the rotational speed of the internal combustion engine during idling.

[0009] The internal combustion engine has a first pulley, the electric motor has a second pulley, and the internal combustion engine and the electric motor are connected by a belt stretched between the first pulley and the second pulley, and the cooling device may have a fan connected to the electric motor. [Effects of the Invention]

[0010] This enables the provision of a vehicle control system that can simultaneously cool the electric motor and generate electricity using the electric motor. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a diagram illustrating a vehicle according to the first embodiment. [Figure 2] Figure 2 is a flowchart illustrating the process in the first embodiment. [Figure 3] Figure 3 illustrates a threshold value. [Figure 4] Figure 4 is a flowchart illustrating the process in the second embodiment. [Modes for carrying out the invention]

[0012] The vehicle control device of this embodiment will be described below with reference to the drawings. However, the dimensions and proportions of each part in the drawings may not perfectly match those of the actual parts. Also, some details may be omitted in the drawings.

[0013] Figure 1 is a schematic diagram illustrating a vehicle 1 according to an embodiment. It includes an internal combustion engine 10, a transmission 12, an MG (motor generator) 14 (electric motor), batteries 16 and 18, a DC (Direct Current) DC converter 20, auxiliary equipment 22, a cooling system 24, and an ECU (Electronic Control Unit) 30.

[0014] The internal combustion engine 10 may be a gasoline engine or a diesel engine. The internal combustion engine 10 generates power by burning fuel such as gasoline. The power is transmitted to the drive wheels (not shown) through the transmission 12. The vehicle 1 is driven by the power generated by the internal combustion engine 10.

[0015] The MG14 functions as both an electric motor and a generator. The MG14 outputs torque when power is supplied, and generates regenerative power when torque is applied. The MG14 is, for example, an AC rotating electric machine. An AC rotating electric machine is, for example, a permanent magnet synchronous motor with a rotor in which permanent magnets are embedded. The MG14 includes a microcomputer (not shown).

[0016] MG14 is an air-cooled electric motor. A cooling device 24 is provided for MG14. The cooling device 24 has, for example, a fan 25. The fan 25 is connected to the shaft of MG14, and when MG14 rotates, the fan 25 also rotates. When the fan 25 rotates, wind is generated and MG14 is cooled. The temperature sensor 19 is provided near MG14 to detect the temperature of MG14.

[0017] A pulley 11 (first pulley) is attached to the crankshaft of the internal combustion engine 10. A pulley 15 (second pulley) is attached to the rotor of MG14. A belt 13 is wound around the pulley 11 and the pulley 15. When the internal combustion engine 10 rotates, power is transmitted to MG14 through the pulley 11, the belt 13, and the pulley 15. MG14 rotates and the cooling device 24 is driven.

[0018] The batteries 16 and 18 are secondary batteries and can be discharged and charged. The battery 18 is, for example, a 12V battery. The battery 16 is, for example, a nickel-metal hydride battery or a lithium-ion battery, etc., and is a battery with a higher voltage than the battery 18, for example, a 48V battery.

[0019] MG14 is electrically connected to the battery 16 and the DCDC converter 20 through the PCU (Power Control Unit) 17.

[0020] The PCU 17 includes an inverter. The PCU 17 converts the AC power generated by MG14 into DC power. The battery 16 is charged by the power generated by MG14.

[0021] The DCDC converter 20 steps down the power generated by MG14 and supplies it to the battery 18 and the auxiliary machine 22. The battery 18 is charged by the power supplied from MG14. The auxiliary machine 22 includes a light, an air conditioner, etc. The auxiliary machine 22 is driven by the power supplied from MG14.

[0022] The ECU 30 is a control device for the vehicle 1 and includes an arithmetic unit such as a CPU (Central Processing Unit), and storage devices such as a RAM (Random Access Memory) and a ROM (Read Only Memory). The ECU 30 performs various controls by executing programs stored in the ROM and the storage device.

[0023] The ECU 30 controls the MG 14, the batteries 16 and 18, the DCDC converter 20, and the auxiliary machine 22. The ECU 30 functions as a temperature acquisition unit that acquires the temperature of the MG 14 detected by the temperature sensor 19. The ECU 30 can measure time. The ECU 30 functions as a rotational speed control unit that controls the rotational speed of the internal combustion engine 10 and sets the rotational speed of the internal combustion engine 10 (idle rotational speed) during idling. During the idling of the internal combustion engine 10, as the internal combustion engine 10 rotates, the MG 14 also rotates. When the MG 14 rotates, the fan 25 of the cooling device 24 also rotates. By controlling the idle rotational speed, the cooling performance for the MG 14 during idling can be controlled.

[0024] Figures 2 and 3 are flowcharts exemplifying the processes executed by the ECU 30. As shown in Figure 2, the ECU 30 acquires the temperature of the MG 14 from the temperature sensor 19 (step S10). The ECU 30 determines whether the temperature T is higher than a predetermined temperature T1 (first temperature) (step S12). In the case of an affirmative determination (Yes), the ECU 30 measures the counter. The counter starts to count up, and the ECU 30 measures the time C during which the temperature T remains higher than T1 by measuring the counter (step S14).

[0025] The ECU 30 determines whether the time C is longer than a predetermined time C1 (step S16). In the case of a negative determination (No), step S14 is repeated. In the case of an affirmative determination, the ECU 30 sets the idle rotational speed of the internal combustion engine 10 to R1 (step S18) and controls the rotational speed of the internal combustion engine 10 so that the rotational speed R1 is achieved (step S20).

[0026] If the determination in step S12 is negative, it is determined whether the temperature T is less than or equal to T2 (second temperature) (step S22 in Figure 3). If the determination is positive, the ECU 30 measures the counter (step S24) and measures the time during which the temperature T remained below T2. It is determined whether the time C is longer than a predetermined time C2 (step S26). If the determination is negative, step S24 is repeated. If the determination is positive, the ECU 30 sets the idle speed to R2 (step S28) and controls the rotational speed of the internal combustion engine 10 so that the rotational speed R2 is achieved (step S20).

[0027] If the result in step S22 is negative, the ECU 30 clears the counter (step S30). The ECU 30 maintains the idle speed at the previous value (step S32). The ECU 30 controls the rotational speed of the internal combustion engine 10 with the previous value as the target (step S20). After step S20, the process ends.

[0028] Figure 4 is an example of a time chart. The top row shows the rotation speed increase flag. The middle row shows the idle speed. The bottom row shows the temperature of MG14. The horizontal axis represents time. At the start of the time chart, the rotation speed increase flag is off. The idle speed is R2. The temperature T is lower than T2 and T1.

[0029] At time t1, the temperature T exceeds T1 and remains higher than T1. The time from time t1 to t2 corresponds to C1. The ECU 30 measures the time C during which the temperature T remains higher than T1 and detects that time C has become longer than C1 (positive determination in step S16 in Figure 2). The ECU 30 turns on the rotation speed increase flag. The idle rotation speed increases to R1, which is higher than R2 (step S18).

[0030] At time t3, temperature T is less than or equal to T1. Between time t3 and time t4, temperature T is less than or equal to T1 and higher than T2. ​​The rotation speed increase flag is kept on. The idle speed maintains the previous value R1 (step S32).

[0031] At time t4, the temperature T decreases to T2 or below. The time from time t4 to t5 corresponds to C2. The ECU 30 measures the time C during which the temperature T remains below T2 and detects that time C has become longer than C2 (positive determination in step S26 in Figure 3). The ECU 30 turns off the rotation speed increase flag. The idle speed decreases to R2, which is lower than R1 (step S28).

[0032] According to this embodiment, the MG14 is a cooled type and has a cooling device 24. The MG14 is connected to the internal combustion engine 10. When the internal combustion engine 10 rotates, the MG14 also rotates and the cooling device 24 is driven. When the temperature T of the MG14 is higher than T1, the ECU 30 sets the idle speed to R1 (step S18 in Figure 2). The rotation speed R1 is higher than the rotation speed R2 when the temperature T is T1 or less. As the idle speed increases, the rotation speed of the MG14 and the rotation speed of the fan 25 of the cooling device 24 increase. As the rotation speed of the fan 25 increases, the cooling performance improves. By cooling the MG14, the rise in temperature can be suppressed. Since cooling by the cooling device 24 is possible, it is not necessary to reduce the amount of power generated by the MG14. It is possible to achieve both cooling of the MG14 and power generation by the MG14.

[0033] If the temperature T of MG14 remains higher than T1 for a longer period than C1, the ECU 30 sets the idle speed to R1 (step S18). If the MG14 remains at a high temperature, the cooling performance of the cooling device 24 increases. This allows the MG14 to be cooled and the temperature rise to be suppressed.

[0034] When the temperature T of MG14 falls below T2, the ECU30 sets the idle speed to R2, which is lower than R1 (step S28). This reduction in idle speed improves the fuel efficiency of the internal combustion engine 10.

[0035] When the temperature T of MG14 is less than or equal to T1 and higher than T2, the ECU 30 maintains the idle speed at the previous value. Between times t3 and t4 in Figure 4, the idle speed is maintained at R1. As the cooling performance of the cooling device 24 improves, MG14 is cooled and the rise in temperature is suppressed.

[0036] The internal combustion engine 10 has a pulley 11. The MG 14 has a pulley 15. A belt 13 is stretched between pulleys 11 and 15. The driving force of the internal combustion engine 10 is transmitted to the MG 14 through pulleys 11, 13, and 15. Therefore, when the internal combustion engine 10 rotates, the MG 14 also rotates. As the MG 14 rotates, the fan 25 of the cooling device 24 rotates. By increasing the idle speed, the rotation speed of the MG 14 and the fan 25 during idling can be increased. This improves the cooling performance during idling and allows the MG 14 to be cooled effectively.

[0037] Although preferred embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the invention as described in the claims. [Explanation of Symbols]

[0038] 1 Vehicle, 10 Internal combustion engine, 11, 15 Pulley, 12 Transmission, 13 Belt, 14 MG, 16, 18 Battery, 17 PCU, 19 Temperature sensor, 20 DC-DC converter, 22 Auxiliary equipment, 24 Cooling system, 25 Fan, 30 ECU

Claims

1. A control device for a vehicle having an internal combustion engine, an electric motor, and a cooling system, The electric motor is connected to the internal combustion engine. The cooling device is driven by the rotation of the electric motor and cools the electric motor. The control device is A temperature acquisition unit that acquires the temperature of the electric motor, The system comprises a rotational speed control unit for controlling the rotational speed of the internal combustion engine, When the temperature of the electric motor is higher than the first temperature, the rotational speed control unit increases the rotational speed of the internal combustion engine during idling compared to when the temperature is below the first temperature. The internal combustion engine has a first pulley, The aforementioned electric motor has a second pulley, The internal combustion engine and the electric motor are connected by a belt being stretched between the first pulley and the second pulley. The cooling device is a control device for a vehicle having a fan connected to the electric motor.

2. The vehicle control device according to claim 1, wherein if the temperature of the electric motor remains higher than the first temperature for a predetermined period of time, the rotational speed control unit increases the rotational speed of the internal combustion engine during idling.

3. A vehicle control device according to claim 1 or 2, wherein when the temperature of the electric motor is lower than or equal to a second temperature, which is lower than the first temperature, the rotational speed of the internal combustion engine during idling is reduced compared to when the temperature is higher than the first temperature.

4. The vehicle control device according to claim 3, wherein the rotational speed control unit maintains the rotational speed of the internal combustion engine during idling when the temperature of the electric motor is less than or equal to the first temperature and higher than the second temperature.

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