JP7623255B2 - Hybrid vehicle control device - Google Patents

Description

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

For example, Patent Document 1 discloses a hybrid vehicle equipped with an internal combustion engine and an electric motor as a driving source for traveling. This hybrid vehicle is equipped with a first radiator that cools the cooling water of the internal combustion engine, and a first electric fan that cools the first radiator. This hybrid vehicle is also equipped with a second radiator that cools the cooling water of a power supply device that supplies power to the electric motor, and a second electric fan that cools the second radiator. The second electric fan is driven when the temperature of the cooling water of the power supply device is equal to or higher than a predetermined temperature. Furthermore, even if the temperature of the cooling water of the power supply device is below the predetermined temperature, the second electric fan is driven to cool the engine compartment if a predetermined condition is met.

JP 2019-119242 A

When it is desired to simply control the operation of the second electric fan, it is possible to adopt on/off control using a relay circuit.
In this case, if the second electric fan is driven not only based on the temperature condition of the cooling water of the power supply device but also based on other predetermined conditions, the frequency with which the second electric fan is turned on and off increases, which may cause the contacts of the relay circuit to wear out prematurely.

The hybrid vehicle control device that solves the above problem is a control device applied to a hybrid vehicle equipped with an internal combustion engine and an electric motor as a driving source for traveling. The hybrid vehicle has a first radiator that cools the cooling water of the internal combustion engine, a first electric fan that cools the first radiator and changes the airflow in multiple stages, a second radiator that cools the cooling water of a power supply device that supplies power to the electric motor, and a second electric fan that cools the second radiator and is controlled to be turned on and off through a relay circuit. When a heat generation state value that correlates with the amount of heat generated by the internal combustion engine is equal to or greater than a predetermined judgment value, the control device executes a process of driving both the first electric fan and the second electric fan, and a process of prohibiting the second electric fan from being stopped until a predetermined time has elapsed since the second electric fan started to be driven.

According to this configuration, when the heat generation state value of the internal combustion engine reaches or exceeds the judgment value, both the first electric fan and the second electric fan are driven. Therefore, the air blown from the first electric fan and the second electric fan can lower the temperature of the internal combustion engine and the engine room in which the internal combustion engine is located.

In addition, with this configuration, the second electric fan is prohibited from being stopped until a predetermined time has elapsed since the second electric fan started to be driven. This prevents the second electric fan from being turned on and off too frequently. This prevents wear on the contacts of the relay circuit that controls the on and off of the second electric fan.

1 is a diagram illustrating a schematic configuration of a vehicle to which an embodiment of a control device for a hybrid vehicle is applied; FIG. 4 is a diagram showing the relationship between the duty ratio for driving the first fan and the engine water temperature. A diagram showing the relationship between the on/off state of the second fan and the PCU water temperature. 4 is a flowchart showing a processing procedure executed by the control device. 4 is a flowchart showing a processing procedure executed by the control device. FIG. 11 is a diagram showing the relationship between the duty ratio for driving the first fan and the exhaust temperature.

Hereinafter, an embodiment will be described with reference to the drawings.
<Vehicle configuration>
In this embodiment, the direction that coincides with the traveling direction of the vehicle is referred to as the front, and the opposite direction is referred to as the rear.

As shown in FIG. 1, a vehicle 500 is a hybrid vehicle equipped with an internal combustion engine and an electric motor as drive sources for traveling.
An internal combustion engine 10 is disposed in an engine room 510 of a vehicle 500. A crankshaft of the internal combustion engine 10 is connected to a power split mechanism 53 provided in a transaxle 50. The transaxle 50 is disposed adjacent to the internal combustion engine 10 in the width direction H of the vehicle 500.

The first motor generator 51 and the second motor generator 52 are drivingly connected to the power split mechanism 53. Furthermore, the drive wheels of the vehicle 500 are connected to the power split mechanism 53 via a differential gear (not shown) or the like.

The first motor generator 51 functions as a generator that generates electricity using the engine output, and also functions as a starting starter (electric motor) that cranks the crankshaft when starting the internal combustion engine 10. The second motor generator 52 functions as an electric motor that generates driving force for the drive wheels, and also functions as a generator that generates electricity using regenerative braking when the vehicle 500 is decelerating.

The first motor generator 51 and the second motor generator 52 exchange power with a battery (not shown) via a PCU (Power Control Unit) 60. The PCU 60 is a power supply device that supplies power to the first motor generator 51 and the second motor generator 52. The PCU 60 includes a converter that boosts and outputs a DC voltage input from the battery, and an inverter that converts the DC voltage boosted by the converter into an AC voltage and outputs it to the first motor generator 51 and the second motor generator 52. In this embodiment, the PCU 60 is attached to the transaxle 50.

<Vehicle cooling system>
The vehicle 500 is equipped with a first cooling system 100 whose main purpose is to cool the internal combustion engine 10 , and a second cooling system 200 whose main purpose is to cool the PCU 60 .

The first cooling system 100 has a first radiator 120 that is disposed in front of the transaxle 50 inside the engine compartment 510 .
The first radiator 120 is a heat exchanger for cooling the cooling water that has become hot by flowing through a water jacket or the like provided inside the internal combustion engine 10 .

A first electric fan 110 (hereinafter referred to as the first fan 110) for cooling the first radiator 120 is provided behind the first radiator 120. This first fan 110 is an electric cooling fan driven by a motor. A driver 140 is connected to the motor of the first fan 110, which receives a PWM signal and supplies power to the motor.

The circulation of the cooling water between the first radiator 120 and the internal combustion engine 10 is performed via a first cooling water passage 130 that connects the first radiator 120 and the internal combustion engine 10. In addition, the first cooling system 100 is also equipped with a reserve tank, a thermostat, and a bypass passage that circulates the cooling water by bypassing the first radiator 120, which are not shown.

The second cooling system 200 has a second radiator 220 that is disposed in front of the internal combustion engine 10 in the engine compartment 510 .
The second radiator 220 is a heat exchanger for cooling the cooling water that has become hot by cooling the PCU 60 .

A second electric fan 210 (hereinafter referred to as the second fan 210) for cooling the second radiator 220 is provided behind the second radiator 220. This second fan 210 is also an electric cooling fan driven by a motor. A relay circuit 240 that controls the power supply to the motor is connected to the motor of the second fan 210.

The circulation of the cooling water between the second radiator 220 and the PCU 60 is performed via a second cooling water passage 230 that connects the second radiator 220 and the PCU 60. In addition, the second cooling system 200 is also equipped with a reserve tank, a thermostat, and a bypass passage that circulates the cooling water by bypassing the second radiator 220, which are not shown.

<Control device>
The control device 300 includes a CPU 310 and a memory 320. The control device 300 controls the internal combustion engine 10, the first motor generator 51, the second motor generator 52, the first fan 110, the second fan 210, etc., by the CPU 310 executing a program stored in the memory 320. Although not shown, the control device 300 is made up of a plurality of control units, such as a control unit for the internal combustion engine 10 and a control unit for the PCU 60.

To carry out various controls, the control device 300 acquires, for example, the intake air volume GA detected by the air flow meter 80 and the output signal Scr of the crank angle sensor 81. The control device 300 also acquires the engine water temperature THWe detected by the first water temperature sensor 82. The engine water temperature THWe is the temperature of the coolant that flows from the internal combustion engine 10 into the first coolant passage 130, that is, the temperature of the coolant that has been heated by the internal combustion engine 10. The control device 300 also acquires the PCU water temperature THWp detected by the second water temperature sensor 83. The PCU water temperature THWp is the temperature of the coolant that flows from the PCU 60 into the second coolant passage 230, that is, the temperature of the coolant that has been heated by the PCU 60.

The control device 300 calculates the engine speed NE based on the output signal Scr of the crank angle sensor 81. The control device 300 also calculates the engine load factor KL based on the engine speed NE and the intake air amount GA. Here, the engine load factor KL represents the ratio of the current cylinder inflow air amount to the cylinder inflow air amount when the internal combustion engine 10 is operated steadily with the throttle valve fully open at the current engine speed NE. The cylinder inflow air amount is the amount of intake air flowing into each cylinder during the intake stroke.

<Processing Executed by the Control Device>
The control device 300 controls the air volume of the first fan 110 by changing the duty ratio DR of the voltage applied to the motor of the first fan 110 through pulse width modulation control (PWM control).

As shown in FIG. 2, the control device 300 variably sets the duty ratio DR based on the engine water temperature THWe obtained at a predetermined interval, thereby changing the air volume of the first fan 110 in multiple stages.

That is, in this embodiment, the temperatures to be compared with the acquired engine water temperature THWe are set in ascending order of temperature, such as the first engine water temperature THWe1 < the second engine water temperature THWe2 < the third engine water temperature THWe3 < the fourth engine water temperature THWe4. In addition, the duty ratio DR to be set is set in ascending order of value, such as "0%" < the first duty ratio DR1 < the second duty ratio DR2 < the third duty ratio DR3. Note that, although "100%" is set as the third duty ratio DR3 in this embodiment, a value smaller than 100% may be set.

When the engine water temperature THWe rises with the duty ratio DR at "0%," that is, when the first fan 110 is stopped, and reaches the second engine water temperature THWe2, the duty ratio DR that was set to "0%" is set to the first duty ratio DR1. In the process in which the engine water temperature THWe rises from the second engine water temperature THWe2 to the third engine water temperature THWe3, the duty ratio DR is gradually increased from the first duty ratio DR1 to the second duty ratio DR2. The section between the second engine water temperature THWe2 and the third engine water temperature THWe3 is a gradual change section that suppresses a sudden change in the duty ratio DR. By providing such a gradual change section, the generation of noise due to a sudden change in the rotation speed of the first fan 110 is suppressed. When the engine water temperature THWe is between the third engine water temperature THWe3 and the fourth engine water temperature THWe4, the duty ratio DR is held at the second duty ratio DR2. When the engine water temperature THWe reaches the fourth engine water temperature THWe4, the duty ratio DR is held at the third duty ratio DR3.

On the other hand, when the engine water temperature THWe decreases while the duty ratio DR is held at the third duty ratio DR3, and the engine water temperature THWe decreases to the third engine water temperature THWe3, the duty ratio DR is set to the second duty ratio DR2. In the gradual change section in which the engine water temperature THWe decreases from the third engine water temperature THWe3 to the second engine water temperature THWe2, the duty ratio DR is gradually decreased from the second duty ratio DR2 to the first duty ratio DR1. When the engine water temperature THWe is between the second engine water temperature THWe2 and the first engine water temperature THWe1, the duty ratio DR is held at the first duty ratio DR1. When the engine water temperature THWe decreases to the first engine water temperature THWe1, the duty ratio DR is held at "0%".

In this manner, in this embodiment, the duty ratio DR is changed to three stages, namely, the first duty ratio DR1, the second duty ratio DR2, and the third duty ratio DR3, so that the airflow when the first fan 110 is driven can be changed to three stages.

The control device 300 also controls the driving and stopping of the second fan 210 by supplying and stopping power to the motor of the second fan 210 through on/off control using the relay circuit 240.

As shown in FIG. 3, the control device 300 performs on/off control of the second fan 210 by turning on/off the relay circuit 240 connected to the motor of the second fan 210 based on the PCU water temperature THWp acquired at a predetermined interval.

In other words, in this embodiment, the temperatures to be compared with the acquired PCU water temperature THWp are set in ascending order of temperature, such as first PCU water temperature THWp1 < second PCU water temperature THWp2.

When the PCU water temperature THWp becomes equal to or higher than the second PCU water temperature THWp2 while the second fan 210 is off, the control device 300 turns on a request flag FD that requests the second fan 210 to be driven. When the request flag FD is turned on, the control device 300 starts supplying electricity to the second fan 210 by turning on the contacts of the relay circuit 240. Through this process, the second fan 210 is turned on and driven.

On the other hand, when the second fan 210 is on and the PCU water temperature THWp falls below the first PCU water temperature THWp1, the control device 300 turns off the request flag FD. When the request flag FD turns off, the control device 300 executes a series of processes shown in FIG. 4 described below to stop driving the second fan 210. When stopping the driving of the second fan 210, the CPU 310 turns off the contacts of the relay circuit 240 to stop the flow of electricity to the second fan 210. This stopping of the flow of electricity turns off the second fan 210 and brings it into a stopped state.

The control device 300 also executes the processes shown in FIGS.
The process shown in Fig. 4 is realized by CPU 310 executing a program stored in memory 320. The process shown in Fig. 4 is repeatedly executed at predetermined intervals when second fan 210 is on and driven. In the following, the step number of each process is represented by a number preceded by "S."

In the series of processes shown in FIG. 4, the CPU 310 determines whether or not there is a request to drive the second fan 210 (S100). In this S100, if the request flag FD is on, the CPU 310 determines that there is a request to drive the second fan 210.

If it is determined that there is no request to drive the second fan 210 (S100: NO), that is, if the request flag FD is off, the second fan 210 is not immediately stopped from being driven, but instead the process of S110 is executed.

In the process of S110, the CPU 310 determines whether the drive time TK of the second fan 210 is equal to or greater than a predetermined reference value TKref. The drive time TK is the time elapsed since the second fan 210 starts to drive, and is measured by the CPU 310 in a separate process. In addition, a value appropriate for protecting the contacts of the relay circuit 240 is preset as the reference value TKref.

If it is determined that the drive time TK is equal to or greater than the reference value TKref (S110: YES), the CPU 310 stops the drive of the second fan 210 by turning off the contacts of the relay circuit 240 (S120).

When the CPU 310 has finished processing S120, when a positive determination is made in processing S100, or when a negative determination is made in processing S110, the CPU 310 temporarily ends the series of processes shown in FIG. 4.

The process shown in Fig. 5 is realized by the CPU 310 executing a program stored in the memory 320. The process shown in Fig. 5 is repeatedly executed at predetermined intervals.
5, the CPU 310 acquires the exhaust temperature THex, which is the temperature of the exhaust gas discharged from the combustion chamber of the internal combustion engine 10 (S200). This exhaust temperature THex is a value acquired as a heat generation state value that correlates with the amount of heat generated by the internal combustion engine 10. In this embodiment, the exhaust temperature THex is calculated from the engine speed NE, the engine load factor KL, etc. in a separate process, and the calculated value is acquired in S200. The exhaust temperature THex may be detected by a sensor.

Next, the CPU 310 determines whether the exhaust temperature THex is equal to or greater than a predetermined reference value THexref (S210). The reference value THexref is preset to a value appropriate for determining that it is desirable to lower the temperature in the internal combustion engine 10 or the engine compartment 510.

If it is determined that the exhaust temperature THex is equal to or greater than the reference value THexref (S210: YES), the CPU 310 calculates the duty ratio DR for driving the first fan 110 based on the exhaust temperature THex (S220).

As shown in FIG. 6, in this embodiment, the temperatures to be compared with the acquired exhaust temperature THex are set in ascending order of temperature, such as the first exhaust temperature THex1 < the second exhaust temperature THex2 < the third exhaust temperature THex3 < the fourth exhaust temperature THex4. In addition, the duty ratio DR to be set is set in ascending order of value, such as "0%" < the first duty ratio DR1 < the second duty ratio DR2 < the third duty ratio DR3. Note that, although "100%" is set as the third duty ratio DR3 in this embodiment, a value smaller than 100% may be set.

When the exhaust temperature THex rises and reaches the second exhaust temperature THex2 while the duty ratio DR is "0%", that is, when the first fan 110 is stopped, the duty ratio DR that was set to "0%" is set to the first duty ratio DR1. As the exhaust temperature THex rises from the second exhaust temperature THex2 to the third exhaust temperature THex3, the duty ratio DR is gradually increased from the first duty ratio DR1 to the second duty ratio DR2. The section between the second exhaust temperature THex2 and the third exhaust temperature THex3 is a gradual change section that suppresses a sudden change in the duty ratio DR. By providing such a gradual change section, the generation of noise due to a sudden change in the rotation speed of the first fan 110 is suppressed. When the exhaust temperature THex is between the third exhaust temperature THex3 and the fourth exhaust temperature THex4, the duty ratio DR is maintained at the second duty ratio DR2. When the exhaust temperature THex becomes equal to or higher than the fourth exhaust temperature THex4, the duty ratio DR is set to the third duty ratio DR3.

On the other hand, when the exhaust temperature THex decreases while the duty ratio DR is held at the third duty ratio DR3, and the exhaust temperature THex decreases to the third exhaust temperature THex3, the duty ratio DR is set to the second duty ratio DR2. In the gradual change section in which the exhaust temperature THex decreases from the third exhaust temperature THex3 to the second exhaust temperature THex2, the duty ratio DR is gradually decreased from the second duty ratio DR2 to the first duty ratio DR1. When the exhaust temperature THex is between the second exhaust temperature THex2 and the first exhaust temperature THex1, the duty ratio DR is held at the first duty ratio DR1. When the exhaust temperature THex becomes equal to or lower than the first exhaust temperature THex1, the duty ratio DR is set to "0%".

Next, the CPU 310 drives the first fan 110 at the duty ratio DR set in S220, and also drives the second fan 210 by turning on the request flag FD that requests the second fan 210 to be driven (S230). Then, this process is temporarily terminated.

The first fan 110 and the second fan 210 that were started in the process of S230 are stopped when a default stop condition is met. An example of the default stop condition is that the exhaust temperature THex is equal to or lower than a default stop determination value THexref2 that is a value lower than the above-mentioned determination value THexref. In addition, the above-mentioned first exhaust temperature THex1 may be used as the determination value THexref2.

When the stop condition is met in this way, the request flag FD, which requests the second fan 210 to be driven, is turned off. Then, the drive of the second fan 210 is stopped by executing the series of processes shown in FIG. 4.

On the other hand, when it is determined in the process of S210 that the exhaust temperature THex is less than the reference value THexref (S210: NO), the CPU 310 temporarily ends this process.
<Action and Effects>
The operation and effects of this embodiment will be described.

(1) As shown in FIG. 4, when there is no request to drive the second fan 210, the drive of the second fan 210 is stopped when the drive time TK of the second fan 210 becomes equal to or greater than the judgment value TKref. In other words, the drive of the second fan 210 is prohibited from being stopped until the predetermined judgment time has elapsed since the drive of the second fan 210 started. This prevents the second fan 210 from being frequently turned on and off. This prevents wear on the contacts of the relay circuit 240 that controls the on and off of the second fan 210.

(2) As shown in FIG. 5, when the exhaust temperature THex becomes equal to or greater than the reference value THexref, both the first fan 110 and the second fan 210 are driven. Therefore, the temperature inside the internal combustion engine 10 and the engine room 510 can be reduced by the air blown from the first fan 110 and the second fan 210.

(3) Engine performance such as friction, fuel vaporization, and knocking resistance is affected by the coolant temperature of the internal combustion engine 10. Therefore, in order to improve the controllability of the coolant temperature of the internal combustion engine 10, it is desirable to change the airflow rate of the first fan 110 in multiple stages.

On the other hand, the cooling water temperature of the PCU 60 only needs to be controlled so that the PCU 60 does not exceed an allowable temperature, and therefore simple on/off control is also sufficient.
Therefore, in this embodiment, a control that changes the airflow rate in multiple stages is adopted for the first fan 110, while an on/off control is adopted for the second fan 210. Therefore, as with the first fan 110, the cost of controlling the second fan 210 can be reduced compared to a case in which a control that changes the airflow rate in multiple stages is adopted for the second fan 210.

<Example of change>
The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

The manner in which the duty ratio DR is set as shown in FIG. 2 or FIG. 6 can be changed as appropriate.
In the process of S220 shown in Fig. 5, the duty ratio DR is variably set based on the exhaust temperature THex. Alternatively, the duty ratio DR may be set to a predetermined fixed value.

- Although the exhaust temperature THex is acquired as the heat generation state value that correlates with the amount of heat generated by the internal combustion engine 10, other values may also be acquired. For example, the engine speed NE and the engine load factor KL may also be acquired.

Although the air volume when the first fan 110 is driven is changed to three levels, it may be changed to two levels or four or more levels.
Although the above-mentioned gradual change interval is set when setting the duty ratio DR of the first fan 110, such a gradual change interval may be omitted. An example of this modification is as follows. That is, in setting the duty ratio DR shown in FIG. 2, in the process in which the engine water temperature THWe increases, the first duty ratio DR1 or the second duty ratio DR2 may be maintained between the second engine water temperature THWe2 and the third engine water temperature THWe3. Also, in the process in which the engine water temperature THWe decreases, the second duty ratio DR2 may be maintained between the third engine water temperature THWe3 and the second engine water temperature THWe2.

The positional relationship between the internal combustion engine 10 and the transaxle 50 may be changed as appropriate.
The positions of the first radiator 120 and the second radiator 220 may be changed as appropriate.

The number of motor generators included in the vehicle 500 may be changed as appropriate as long as it is one or more.
The hybrid system of the vehicle is not limited to the system shown in FIG. 1 and may be another system.

The control device 300 is not limited to a device equipped with a CPU 310 and memory 320 and executing software processing. For example, it may be equipped with a dedicated hardware circuit, such as an ASIC, that performs hardware processing of at least a portion of what was processed by software in the above embodiment. That is, the control device may have any of the following configurations (a) to (c). (a) It comprises a processing device that executes all of the above processing according to a program, and a program storage device, such as a ROM, that stores the program. (b) It comprises a processing device and program storage device that executes a portion of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (c) It comprises a dedicated hardware circuit that executes all of the above processing. Here, there may be multiple software execution devices equipped with a processing device and program storage device, and multiple dedicated hardware circuits.

REFERENCE SIGNS LIST 10: internal combustion engine 50: transaxle 51: first motor generator 52: second motor generator 53: power split mechanism 60: PCU
Reference Signs List 80: Air flow meter 81: Crank angle sensor 82: First water temperature sensor 83: Second water temperature sensor 100: First cooling system 110: First electric fan 120: First radiator 130: First cooling water passage 140: Driver 200: Second cooling system 210: Second electric fan 220: Second radiator 230: Second cooling water passage 240: Relay circuit 300: Control device 310: CPU
320...Memory 500...Vehicle 510...Engine room

Claims (1)

A control device applied to a hybrid vehicle having an internal combustion engine and an electric motor as a driving source for traveling,
The hybrid vehicle includes:
a first radiator for cooling a cooling water of the internal combustion engine;
a first electric fan that cools the first radiator and whose airflow rate is changed in multiple stages;
a second radiator for cooling a cooling water of a power supply device for supplying electric power to the electric motor;
a second electric fan that cools the second radiator and is controlled to be turned on and off through a relay circuit,
The control device includes:
a process of driving both the first electric fan and the second electric fan when a heat generation state value correlated with a heat generation amount of the internal combustion engine is equal to or greater than a predetermined determination value;
and prohibiting stopping of the drive of the second electric fan until a predetermined time has elapsed since the drive of the second electric fan was started.

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