JP2018118683A - Cooling device for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device for a hybrid vehicle that allows a second cooling circuit to continuously operate to cool; a motor generator if a temperature of refrigerant does not surpass an upper limit temperature of the refrigerant even after continuously operating the second cooling circuit, in the hybrid vehicle which is provided with two-system cooling circuits for the motor generator and is configured so that a second cooling circuit of one system shares the refrigerant with the other cooling system.SOLUTION: A motor generator (MG 1) has cooling circuits of two systems: a cooling system comprising an air-cooling oil cooler 3 for cooling ATF to be supplied from a mechanical oil pump 2 to the MG 1 and a cooling system comprising a water-cooling oil cooler 7 for cooling ATF to be supplied from an electric oil pump 6 to the MG 1. The water-cooling oil cooler 7 shares refrigerant (LLC) with a cooling system of an engine. An ECU 9, when a temperature of the refrigerant does not surpass an upper limit temperature thereof even after continuously operating the air-cooling oil cooler 3, changes timing for stopping the air-cooling oil cooler 3 to vehicle speed in which default values are large.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cooling device for a hybrid vehicle, and more particularly to a device that provides two cooling circuits for a motor generator that is an object to be cooled.

  2. Description of the Related Art Conventionally, a hybrid vehicle including a motor generator having a power generation function and an electric function and a power split device that distributes power output from an internal combustion engine (engine) to a drive train and a generator is known. When the motor generator functions as a generator or as an electric motor, it generates heat due to electric resistance or the like, and the output torque of the motor generator may be reduced by the heat. For this reason, conventionally, the motor generator is configured to be cooled by supplying oil.

  The power split device also includes a differential gear mechanism having a three-element gear having a function of combining or splitting power. Torque for driving the vehicle acts on each gear in the power split device. Therefore, in order to reduce the friction loss of each gear or prevent seizure due to heat generation of each gear, oil is supplied to each gear and cooled.

  As a means for supplying oil to the motor generator and the power split device, an oil pump (MOP) connected to the output shaft of the engine and driven by the power output from the engine, and a vehicle that is electrically controllable It is equipped with an electric oil pump (EOP) that can be driven independently of the travel. Since the mechanical oil pump operates in conjunction with the engine, the mechanical oil pump operates during traveling in a traveling mode (HV traveling mode) in which the power from the engine is the driving force of the vehicle, but only when the engine is stopped, that is, only the power of the motor. When the vehicle is traveling in a traveling mode (EV traveling mode) in which the driving force of the vehicle is used, it does not operate. Therefore, at this time, the electric oil pump supplies oil to the motor generator and the power split device.

  Conventionally, there has been proposed a hydraulic control device that controls to switch the oil supply destination of an electric oil pump to either a motor generator or a power split device based on the temperature and torque of a motor generator (for example, Patent Document 1).

JP 2013-199216 A

  By the way, two systems (a first cooling circuit and a second cooling circuit) are provided as a cooling circuit for the motor generator, and one of them (a second cooling circuit) is configured to share a refrigerant with another cooling system. Vehicles are known. As described above, in the configuration in which the motor generator includes the two cooling circuits, for example, the temperature of the refrigerant in the second cooling circuit is low, but the cooling object in the other cooling system can be sufficiently cooled. If the operation of the second cooling circuit is stopped and the motor generator is cooled, that is, if the operation of the second cooling circuit is controlled without considering the temperature of the refrigerant in the second cooling circuit, the motor generator May not be efficiently cooled.

  The present invention provides a hybrid vehicle having a first and second two-system motor generator cooling circuit, and one second cooling circuit configured to share a refrigerant with another cooling system. If the temperature of the refrigerant does not exceed the upper limit temperature of the refrigerant even if the cooling circuit is continuously operated, the second cooling circuit is continuously operated to cool the motor generator.

  A cooling device for a hybrid vehicle according to the present invention is a cooling device mounted on a vehicle including an internal combustion engine and a motor generator. First and second cooling circuits for supplying oil to the motor generator, and the motor generator A control device for controlling the supply of oil, wherein the first cooling circuit is driven by the power of the internal combustion engine and supplies oil to the motor generator; and from the first oil pump A first oil cooler that cools the oil supplied to the motor generator, and the second cooling circuit is driven by the power of an electric motor, and the vehicle speed is set in advance under the control of the control device A second oil pump that operates until it reaches the stop vehicle speed and supplies oil to the motor generator, and other cooling And a second oil cooler that shares the refrigerant and cools the oil supplied from the second oil pump to the motor generator, and the control device continues to operate the second oil pump. When the temperature of the refrigerant does not exceed the upper limit temperature of the refrigerant, the timing for stopping the second oil pump is changed from the drive stop vehicle speed to a vehicle speed greater than the drive stop vehicle speed.

  According to the present invention, if the temperature of the refrigerant does not exceed the upper limit temperature of the refrigerant even if the second cooling circuit that shares the refrigerant with the other cooling system is continuously operated, the cooling target in the other cooling system The motor generator can be cooled using the second cooling circuit continuously while cooling the object. As a result, the motor generator can be efficiently cooled.

It is a block diagram which shows one Embodiment of the cooling device for hybrid vehicles which concerns on this invention. It is a figure which shows the relationship between the vehicle speed and the thermal radiation amount from the motor generator corresponding to each oil pump in Embodiment 1. FIG. FIG. 3 is a diagram showing a relationship between a required driving force and a loss for a motor generator in the first embodiment. 3 is a flowchart showing an operation control process of the electric oil pump in the first embodiment. FIG. 6 is a configuration diagram showing a hybrid vehicle cooling device in a second embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram showing an embodiment of a cooling device for a hybrid vehicle according to the present invention. A hybrid vehicle cooling device (hereinafter simply referred to as “cooling device”) in the present embodiment is used to cool motor generator (MG) 1.

  The motor generator 1 is constituted by a synchronous motor including a permanent magnet in a rotor, for example, and functions as a generator and an electric motor. The motor generator 1 has a rotor and a stator, and the stator is fixed to a casing or the like (not shown). Since the motor generator 1 outputs a reaction force or an assist torque, oil is supplied to cool heat generated by copper loss or iron loss. In the present embodiment, ATF (Automatic Transmission Fluid) is supplied as oil.

  In the present embodiment, two cooling circuits are provided to cool motor generator 1. The first cooling circuit includes a mechanical oil pump (MOP) 2 and an air-cooled oil cooler (O / C) 3. From the oil pan 4 that stores oil (ATF) through the mechanical oil pump 2 and the air-cooled oil cooler 3. An ATF flow path (oil path) 5 communicating with the motor generator 1 is formed. The second cooling circuit includes an electric oil pump (EOP) 6 and a water-cooled oil cooler (O / C) 7, and extends from the oil pan 4 to the motor generator 1 via the electric oil pump 6 and the water-cooled oil cooler 7. It is formed by an ATF flow path (oil path) 8 that communicates. In FIG. 1, the ATF channels 5 and 8 are indicated by solid arrows.

  The mechanical oil pump 2 included in the first cooling circuit is a first oil pump that is connected to an output shaft of an engine (not shown) and is driven by power output from the engine. Since the mechanical oil pump 2 operates in conjunction with the engine, the mechanical oil pump 2 is always operated when the output shaft of the engine is rotating. On the other hand, when the output shaft of the engine does not rotate, the engine is stopped.

  The air-cooled oil cooler 3 is an air-cooled heat exchanger for cooling the ATF, and is a first oil cooler that cools oil supplied from the mechanical oil pump 2 to the motor generator 1.

  The mechanical oil pump 2 pumps up the ATF stored in the oil pan 4 and supplies it to the air-cooled oil cooler 3. The motor generator 1 is cooled by supplying the ATF cooled by the air cooling oil cooler 3. As described above, since the mechanical oil pump 2 operates by the power of the engine, the first cooling circuit operates in the HV traveling mode in which the power is output by the engine (internal combustion engine) and the power of the motor generator 1. Only works.

  The electric oil pump 6 included in the second cooling circuit is a second oil pump that is driven by an electric motor. Since the electric oil pump 6 can be electrically controlled, unlike the mechanical oil pump 2, the electric oil pump 6 can be driven independently of the traveling of the vehicle. Electric oil pump 6 in the present embodiment operates under the control of ECU 9 until the vehicle speed reaches a preset drive stop vehicle speed, and is controlled to supply oil to motor generator 1.

  The water-cooled oil cooler 7 is a water-cooled heat exchanger for cooling the ATF, and is a second oil cooler that cools the ATF supplied from the electric oil pump 6 to the motor generator 1. The water-cooled oil cooler 7 in the present embodiment uses LLC (Long Life Coolant) that cools the engine as a refrigerant. That is, the refrigerant (LLC) is shared with other cooling systems.

  The electric oil pump 6 pumps the ATF stored in the oil pan 4 and supplies it to the water-cooled oil cooler 7. The motor generator 1 is cooled by supplying the ATF cooled by the water-cooled oil cooler 7. As described above, since the electric oil pump 6 can be electrically controlled, the electric oil pump 6 functions not only in the HV traveling mode but also in various operation modes such as the EV traveling mode in which the engine is stopped.

  The ECU 9 is a control device configured as a logic circuit centered on a microcomputer. Specifically, a CPU (not shown) that executes a predetermined calculation according to a preset control program, and a ROM (not shown) that stores in advance a control program and control data necessary for executing various calculation processes by the CPU Similarly, a RAM (not shown) that temporarily reads and writes various data necessary for performing various arithmetic processes by the CPU, an input / output port (not shown) that inputs and outputs various signals, and the like. In the case of the present embodiment, as one of the operation controls to be performed, oil supply control to the motor generator 1, particularly on / off control of the electric oil pump 6 is performed.

  FIG. 1 further shows a PCU (Power Control Unit) 10, a radiator 11, a water pump (W / P) 12, and an LLC flow path 13 as other cooling systems. The LLC flow path 13 is formed to communicate with the water-cooled oil cooler 7, the PCU 10, the radiator 11, and the water pump (W / P) 12 as indicated by the dashed arrows. The PCU 10 controls output of a voltage for driving the motor generator 1. The radiator 11 is a device that radiates heat of LLC (cools LLC). The water pump 12 is a pump for circulating LLC.

  FIG. 1 shows only one motor generator 1, but when a plurality of motor generators 1 are mounted, for example, an ATF flow path supplied from each oil cooler 3, 7 to the motor generator 1. What is necessary is just to comprise so that 5 and 8 may be branched and provided to each motor generator 1. FIG.

  Further, a check valve for preventing ATF backflow and a strainer for removing foreign substances such as metal powder mixed in ATF may be provided in ATF flow paths 5 and 8, but they are not used in the description in the present embodiment. Components are omitted from the figure.

  Here, the relationship between the vehicle speed and the amount of heat released from the motor generator 1 corresponding to each oil pump 2, 6 will be described with reference to FIG.

  FIG. 2 shows a graph in which the horizontal axis represents the vehicle speed and the vertical axis represents the amount of heat released from the motor generator 1. In FIG. 2, a line 21 indicates the amount of heat released from the motor generator 1 corresponding to the mechanical oil pump 2. The mechanical oil pump 2 does not operate while the engine speed is low (at low speed). When the engine rotational speed (vehicle speed) exceeds a certain level, the mechanical oil pump 2 increases the amount of ATF supplied in proportion to the vehicle speed, so that the amount of heat released from the motor generator 1 increases. A line 22 indicates the amount of heat released from the motor generator 1 corresponding to the electric oil pump 6. The electric oil pump 6 is controlled to be turned on in accordance with the start of traveling of the vehicle, but starts operating although there is a slight delay. As a result, a predetermined amount of ATF cooled by the water-cooled oil cooler 7 is supplied to the motor generator 1, so that the motor generator 1 radiates heat at a constant amount. The electric oil pump 6 is controlled to be turned off at the time when the vehicle speed Vd reaches the default value, and stops operating. That is, the vehicle speed Vd is a vehicle speed (drive stop vehicle speed) indicating the timing at which the operation of the electric oil pump 6 is stopped. In the present embodiment, the vehicle speed Vd is set so that the LLC temperature does not exceed the criteria, that is, the LLC temperature does not exceed the LLC upper limit temperature even if the electric oil pump 6 is continuously operated. ing. The vehicle speeds Vl and Vh are vehicle speeds indicating the timing at which the drive of the electric oil pump 6 is stopped under certain conditions. The vehicle speeds Vl and Vh will be described later.

  The ATF flow rate supplied to the motor generator 1 by the operation of the oil pumps 2 and 6 is proportional to the amount of heat released from the motor generator 1 corresponding to the oil pumps 2 and 6. Therefore, the motor generator 1 is supplied with an amount of ATF obtained by adding the ATF flow rates from the oil pumps 2 and 6 at the current vehicle speed.

  Next, the relationship between the required driving force for motor generator 1 and loss (dragging loss) will be described with reference to FIG.

  FIG. 3 shows a graph in which the horizontal axis represents the required driving force for the motor generator 1 and the vertical axis represents the drag loss. The necessary driving force is a driving force necessary to drive the vehicle at the required vehicle speed. The necessary driving force may be read as vehicle speed. The motor generator 1 generates drag loss (MG loss) due to rotational resistance, electrical resistance, and the like. Similarly, the PCU 10 that drives the motor generator 1 also generates drag loss (PCU loss) due to electrical resistance or the like. Each drag loss is proportional to the required driving force, but the sum of the MG loss and the PCU loss becomes the drag loss. Heat exchange by the water-cooled oil cooler 7 using LLC as a refrigerant raises the temperature of the LLC, and when the heat dissipation capacity of the radiator 11 (= the temperature criteria of the LLC) is exceeded, the loss exceeds the upper limit (Lmax) (broken line) Area 23). FIG. 3 shows that the operation of the electric oil pump 6 needs to be stopped before the loss exceeds the upper limit value.

  Next, the operation control process of the electric oil pump 6 in the present embodiment will be described using the flowchart shown in FIG. This process is repeatedly executed at regular intervals.

  The temperature of the motor generator 1 and the temperature of LLC described later are constantly measured by a temperature sensor (not shown). When the measured temperature of motor generator 1 is equal to or lower than a predetermined threshold A ° C. (Y in step 101), it is determined that motor generator 1 is sufficiently cooled, and the timing for stopping electric oil pump 6 is determined as vehicle speed Vd. To a vehicle speed Vl smaller than the vehicle speed. The vehicle speed Vl may be set to an appropriate value based on empirical rules and the like. The threshold A is set with a certain margin with respect to the heat resistant temperature of the motor generator 1. When the motor generator 1 is sufficiently cooled, it is not necessary to cool the ATF any more. Therefore, the cooling circuit on the side including the electric oil pump 6 among the two cooling circuits is stopped relatively quickly. It seems that there is no problem. The mechanical oil pump 2 cannot be stopped as long as the engine is driven. Further, by changing the vehicle speed Vd to the vehicle speed Vl, the electric oil pump 6 stops earlier than the default time, so that the drag loss that can occur can be reduced.

  On the other hand, when the temperature of the motor generator 1 exceeds the threshold A ° C. (N in Step 101), the motor generator 1 needs to be cooled. Here, when the temperature of the LLC is equal to or lower than the predetermined threshold B ° C. (Step 103), it is determined that the LLC temperature does not exceed the upper limit temperature of the LLC even if the electric oil pump 6 is continuously operated, and the timing at which the electric oil pump 6 is stopped is greater than the vehicle speed from the vehicle speed Vd. Change to Vh. The vehicle speed Vh may be set to an appropriate value based on empirical rules and the like. Thereby, it becomes possible to maintain and improve the cooling performance (heat radiation amount) at high speed.

  The temperature of the LLC is increased by the electric oil pump 6 and the PCU 10, but if the LLC is still cooled by the radiator 11 so that the temperature of the LLC does not exceed the upper limit temperature, the electric oil pump 6 is turned on as described above. Control to continue operation. Thus, the threshold B is set to a temperature that does not exceed the upper limit temperature of LLC. By operating the electric oil pump 6 continuously, the motor generator 1 can be cooled while cooling the engine by another cooling system, which is efficient.

  On the other hand, when the temperature of the LLC exceeds a predetermined threshold B ° C. (N in Step 103), the timing for stopping the electric oil pump 6 is set to the vehicle speed Vd (Step 105).

  In the present embodiment, since the processing described above is repeated, the vehicle speed that is the timing for stopping the electric oil pump 6 is not necessarily changed from the vehicle speed Vd after the vehicle speed Vd is changed (steps 102 and 104). However, in order to clarify the feature of changing the default vehicle speed Vd, such expressions are used in steps 102 and 104.

  Thus, according to the present embodiment, the timing for stopping the electric oil pump 6 is changed according to the temperature of the LLC.

Embodiment 2. FIG.
FIG. 5 is a configuration diagram showing the hybrid vehicle cooling device in the present embodiment. The same components as those in Embodiment 1 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. In the first embodiment, the cooling circuit including the electric oil pump 6 is formed separately from the cooling circuit including the mechanical oil pump 2. However, in the present embodiment, the flow oil valve (FSV) 14 is used to The ATF pumped up from the oil pan 4 by the pump 2 is supplied not only to the air-cooled oil cooler 3 via the flow path 15 but also to the water-cooled oil cooler 7 sharing the refrigerant with other cooling systems via the flow path 16. The supply amount was configured to be controlled. The flow shut valve 14 is a valve that outputs the supply amount of ATF in a controllable manner. In the present embodiment, the electric oil pump 6 is not necessary with this configuration, but the same operational effects as those of the first embodiment can be achieved.

  In the above embodiment, the timing at which the electric oil pump 6 is stopped is controlled by the vehicle speed, but values indicating the load state of the motor generator 1 such as the current of the motor generator 1, the command torque, and the rotation speed are used. However, the same control as described above can be performed.

1 Motor generator (MG), 2 Mechanical oil pump (MOP), 3 Air-cooled oil cooler (O / C), 4 Oil pan, 5, 8 ATF flow path, 6 Electric oil pump (EOP), 7 Water-cooled oil cooler (O / C), 11 radiator, 12 water pump (W / P), 13 LLC flow path, 14 flow shut valve (FSV), 15, 16 flow path.

Claims (1)

In a cooling device mounted on a vehicle including an internal combustion engine and a motor generator,
First and second cooling circuits for supplying oil to the motor generator;
A control device for controlling the supply of oil to the motor generator;
With
The first cooling circuit includes:
A first oil pump that is driven by the power of the internal combustion engine and supplies oil to the motor generator;
A first oil cooler that cools oil supplied from the first oil pump to the motor generator;
With
The second cooling circuit includes:
A second oil pump that is driven by the power of the electric motor, operates until the vehicle speed reaches a preset driving stop vehicle speed under the control of the control device, and supplies oil to the motor generator;
A second oil cooler that shares refrigerant with another cooling system and cools oil supplied from the second oil pump to the motor generator;
With
If the temperature of the refrigerant does not exceed the upper limit temperature of the refrigerant even if the second oil pump is continuously operated, the control device determines the timing for stopping the second oil pump from the drive stop vehicle speed. A cooling device for a hybrid vehicle, wherein the vehicle speed is changed to a vehicle speed greater than the stop vehicle speed.

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