JP2004332744A - Cooling system of hybrid electric car - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable efficient cooling to meet an operational condition of an engine and an electric motor. <P>SOLUTION: An engine cooling system 4 and a motor cooling system 5 are communicated with each other via circulation pipes 18 and 21, and a displacement type assist electric pump 19 with water shut-off function when stopping the pump is provided on the circulation pipes 18 and 21. Sensors 22 and 23 to sense the water temperature in the engine cooling system 4 and the water temperature in the motor cooling system 5 are provided, and an electric pump 15 and an assist electric pump 19 of the motor cooling system are driven according to signals of the sensors 22 and 23. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is a vehicle capable of traveling by an electric motor, comprising a generator driven by an engine, and a battery for storing generated electricity, a motor cooling system for cooling the electric motor, and an engine. In a cooling system for a hybrid electric vehicle that includes a cooling system for an engine that cools the vehicle, the power consumption of a cooling system such as a cooling fan is reduced, and the size of the heat exchanger is reduced to reduce the weight, thereby improving fuel efficiency. Regarding technology to improve.

  2. Description of the Related Art Conventionally, a hybrid electric vehicle that combines an engine and an electric motor to improve exhaust emission has been known.

  Such a hybrid electric vehicle includes a generator driven by an engine, and a battery for storing the generated electricity, and can be driven by an electric motor. A cooling system for the engine and a cooling system for the electric motor are provided. The control temperature is greatly different from that of the electric motor, and the cooling system of the motor is usually set lower due to the rating of the electric motor. Therefore, it is not possible to simply share the two cooling systems, and each requires a separate radiator and a separate blower. Therefore, it is important to share water by properly switching the flow of water to the plurality of heat exchangers.

FIG. 15 shows an example of a cooling system, which is a combination of a water cooling system of the engine 50 and a water cooling system of an intercooler 51 for cooling the intake air of the engine. In this example, in addition to a radiator 52 for engine cooling and a radiator 53 for intercooler, a third radiator 55 selectively connected to each water cooling system by a switching valve 54 is provided. When necessary, the third radiator 55 is communicated with the engine cooling system, and when the cooling capacity of the intercooler 51 is required, the third radiator 55 is communicated with the intercooler cooling system. The surplus cooling capacity is used for heat radiation of another water cooling system to reduce the size of the cooling water heat radiation system (for example, Patent Document 1).
JP-A-6-81648

  However, in such a cooling system, since the third radiator is switched according to the water temperature of one of the cooling systems, there is a concern that water temperature hunting may occur when the water temperature difference between the two cooling systems is large. In addition, when the present invention is applied to a cooling system for an engine and an electric motor of the hybrid electric vehicle, efficient cooling suitable for operating conditions cannot be performed. Further, there is no layout freedom of each heat exchanger, and the cooling system is affected by hot air from the engine room.

  An object of the present invention is to provide a cooling system optimal for a cooling system of an engine and an electric motor of a hybrid electric vehicle.

  A first invention is a vehicle capable of traveling by an electric motor, comprising a generator driven by an engine, and a battery for storing generated electricity, and a motor cooling system for cooling the electric motor. And a cooling system for a hybrid electric vehicle including an engine cooling system for cooling the engine, wherein the engine cooling system is formed so that cooling water can be circulated by an engine-driven mechanical pump, and A thermostat for controlling water flow is provided, and the cooling system for the motor is formed so that cooling water can be circulated by a positive displacement type electric pump having a function of shutting off water when stopped. Communicates with the cooling system via a circulation pipe and has a water cutoff function when the circulation pipe is stopped. A displacement assist electric pump is provided, and sensors for detecting a water temperature in the engine cooling system and a water temperature in the motor cooling system are provided. The electric pump and the assist electric pump are provided in accordance with signals from these sensors. Drive it.

  According to a second aspect, in the first aspect, when the water temperature in the engine cooling system is lower than a predetermined value, the thermostat is closed, and the water temperature in the motor cooling system is higher than the predetermined value, the electric pump and The assist electric pump is operated to exchange cooling water between the engine cooling system and the motor cooling system.

  According to a third aspect, in the first aspect, the assist electric pump is provided under the condition that the water temperature in the engine cooling system is higher than a predetermined value, the thermostat is open, and the water temperature in the motor cooling system is lower than the predetermined value. And the electric pump is stopped to exchange cooling water between the engine cooling system and the motor cooling system.

  In a fourth aspect based on the first aspect, the battery is disposed at a location away from the engine room, the sides of the battery are surrounded by a pair of casings, and a radiator of an engine cooling system is provided on a front side of the casing with respect to the vehicle. It is installed so that the battery is cooled by cooling air passing through the radiator.

  According to the first aspect, the cooling water is exchanged between the two cooling systems in accordance with the water temperature in the engine cooling system and the water temperature in the motor cooling system, thereby achieving high cooling performance of the engine and the electric motor. , And water temperature control in each cooling system can be finely performed, and efficient cooling suitable for the operation state can be performed. Therefore, the heat transfer area of the heat exchanger of each cooling system can be effectively used, the power consumption of the cooling fan can be reduced, and the area and weight of the heat exchanger can be reduced.

  According to the second aspect, the electric motor can be efficiently and accurately cooled by using the engine cooling system in a region where cooling performance of the electric motor is required.

  According to the third aspect, the engine can be efficiently and accurately cooled by utilizing the motor cooling system for engine cooling in an area where engine cooling performance is required.

  According to the fourth aspect, the cooling of the battery can be performed by the same cooling fan together with the cooling of the radiator of the engine cooling system. In addition, the radiator of the engine cooling system, which may be activated for charging when the vehicle is stopped, is arranged at a location away from the engine room, so that the low-temperature airflow behind the vehicle can be sucked as much as possible, and the radiator of the engine cooling system Good heat radiation performance can be secured.

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

  In FIG. 1, 1 is an engine, 2 is a generator driven by the engine 1, 3 is an electric motor used for traveling driven by electricity generated by the generator 2 and electric power of a battery, and 4 is engine cooling. The system 5 is a motor cooling system.

  In the engine cooling system 4, the cooling water receives heat by cooling the engine 1, passes through the engine outlet pipe 6, the thermostat 7, and the radiator inlet pipe 8, flows into the engine radiator 9, and radiates heat. Thereafter, the water is sucked by a water pump 12 as a mechanical pump driven by the engine 1 via a radiator outlet pipe 10 and an engine inlet pipe 11, and is returned to the engine 1. In this case, when the temperature of the engine cooling water is equal to or lower than a predetermined value, the thermostat 7 shuts off the flow of water to the radiator 9 for the engine, and the cooling water of the engine outlet pipe 6 immediately passes through the bypass passage 13 to the water pump 12. Reflux.

  In the motor cooling system 5, the cooling water in the cooling system path 14 is sent to the electric motor 3 and the generator 2 by an electric pump (electric water pump) 15, cools them, passes through a radiator 16 for the motor, and releases heat. I do.

  The radiator outlet pipe 10 of the radiator 9 for the engine and the cooling water inlet 17 of the radiator 16 for the motor are connected by a communication pipe 18 serving as a circulation pipe, and an assist electric pump ( An assist electric water pump 19 is installed. The cooling water outlet 20 of the radiator 16 for the motor and the radiator inlet pipe 8 of the radiator 9 for the engine are connected by a return pipe 21 as a circulation pipe.

  As the electric pump 15 and the assist electric pump 19, for example, a positive displacement pump that shuts off water when stopped, such as a gear pump, is used.

  On the other hand, a sensor 22 for detecting the temperature of the cooling water in the radiator 9 for the engine and a sensor 23 for detecting the temperature of the cooling water in the radiator 16 for the motor are provided. These detection signals are detected by a sensor 37 described later. The signal is input to the control unit 26 together with the signal.

  The drive of the electric pump 15 and the assist electric pump 19 is controlled by the control unit 26 based on the detection signals of the sensors 22 and 23. The control unit 26 also controls the driving of cooling fans (electric fans) 24 and 25 for forcing cooling air to flow through the radiator 9 for the engine and the radiator 16 for the motor, respectively.

  FIG. 2 shows the arrangement of the present system, and is a view of the vehicle as viewed from under the floor. The engine 1, the generator 2, and the electric motor 3 are arranged in an engine room 31 on the front side of the vehicle 30. The motor radiator 16 is arranged at the front end of the engine room 31 alongside the air conditioner condenser 32.

  The battery 33 is arranged at a central portion under the floor of the vehicle 30 distant from the engine room 31, and is surrounded by a housing 34 on the side (lateral direction of the vehicle 30). The radiator 9 for the engine is installed on the front side of the casing 30 of the vehicle 30, and the ventilation port 35 is formed on the rear side of the casing 30 of the vehicle 30.

  The cooling fan 24 not only cools the radiator 9 for the engine, but also cools the battery 33. A sensor 37 for detecting the ambient temperature of the battery 33 in the housing 34 is provided, and the control unit 26 controls the driving of the cooling fan 24 also by the detection signal of the sensor 37.

  The cooling fan 24 is of a double type, and reference numeral 38 in the figure denotes a cooling fan for the air conditioner condenser 32. Reference numeral 39 denotes an exhaust pipe of the engine 1, and reference numeral 40 denotes wheels.

  Next, the control contents of the control unit 26 will be described based on the control map of FIG. 3 and the flowcharts of FIGS.

  As described above, the target control water temperature differs between the engine cooling system and the motor cooling system. The target control water temperature differs depending on the type of the engine and the motor, but for the sake of explanation, the following description will be made on the assumption that the maximum target water temperature of the engine is 110 ° C and the maximum target water temperature of the motor is 60 ° C. FIG. 3 shows a control map of the motor water temperature and the engine water temperature. In each of the regions (a) to (g) shown here, the operation is performed by switching the water flow system shown in FIG.

  In step 1 of FIG. 4, it is determined whether or not the ambient temperature of the battery 33 is 50 ° C. or higher. If it is 50 ° C. or higher, the cooling fan 24 of the engine radiator 9 is turned on in step 2 regardless of a routine described later.

  In step 3, it is determined whether the motor water temperature (water temperature detected by the sensor 22) is 50 ° C. or higher. If it is lower than 50 ° C., in step 4, it is determined whether the engine water temperature (water temperature detected by the sensor 23) is 80 ° C. or higher. , 80 ° C., the flow proceeds to A (FIG. 5), and if it is 80 ° C. or more, the flow proceeds to D (FIG. 8).

  If the motor water temperature is equal to or higher than 50 ° C. in step 3, it is determined in step 5 whether the engine water temperature is equal to or higher than 80 ° C. If the motor water temperature is equal to or higher than 80 ° C., the flow proceeds to E (FIG. 9). If so, it is determined in step 6 whether the engine water temperature is 55 ° C. or lower and the motor water temperature is 55 ° C. or higher. If No, the flow proceeds to B (FIG. 6); if Yes, C (FIG. 7) Proceed to flow.

  In step 11 of FIG. 5 (control in the area of FIG. 3A), the electric pump 15 and the assist electric pump 19 are turned off, and both the cooling fans 24 and 25 of the engine radiator 9 and the motor radiator 16 are turned off. .

  In step 21 of FIG. 6 (control in the region of FIG. 3B), the electric pump 15 is turned on and the assist electric pump 19 is turned off. In step 22, it is determined whether or not the motor water temperature is 58 ° C. or higher. If it is lower than 58 ° C., in step 23, both the cooling fans 24 and 25 of the engine radiator 9 and the motor radiator 16 are turned off. For example, in step 24, the cooling fan 24 of the engine radiator 9 is turned off, and the cooling fan 25 of the motor radiator 16 is turned on.

  In step 31 of FIG. 7 (control in the region of FIG. 3C), the electric pump 15 and the assist electric pump 19 are turned on. In step 32, it is determined whether or not the motor water temperature is 58 ° C. or higher. If it is lower than 58 ° C., in step 33, the cooling fans 24 and 25 of the engine radiator 9 and the motor radiator 16 are turned off. For example, in step 34, the cooling fan 24 of the engine radiator 9 is turned off, and the cooling fan 25 of the motor radiator 16 is turned on.

  In step 41 of FIG. 8 (control in the region of FIG. 3D), the electric pump 15 is turned on and the assist electric pump 19 is turned off. In step 42, it is determined whether or not the engine water temperature is 95 ° C. or higher. If the temperature is lower than 95 ° C., in step 43, both the cooling fans 24 and 25 of the engine radiator 9 and the motor radiator 16 are turned off. For example, in step 44, the cooling fan 24 of the engine radiator 9 is turned on, and the cooling fan 25 of the motor radiator 16 is turned off.

  In step 51 of FIG. 9 (control in the region of FIG. 3E), the electric pump 15 is turned on and the assist electric pump 19 is turned off.

  In step 52, it is determined whether the engine water temperature is 95 ° C. or higher. If the temperature is lower than 95 ° C., it is determined in step 53 whether the motor water temperature is 58 ° C. or higher. 9. The cooling fans 24 and 25 of the motor radiator 16 are both turned off. If the temperature is 58 ° C. or more, the cooling fan 24 of the engine radiator 9 is turned off and the cooling fan 25 of the motor radiator 16 is turned on in step 55. .

  If the engine water temperature is equal to or higher than 95 ° C. in step 52, it is determined in step 56 whether the motor water temperature is equal to or higher than 58 ° C. If it is lower than 58 ° C., the cooling fan 24 of the engine radiator 9 is turned on in step 57, The cooling fan 25 of the motor radiator 16 is turned off. If the temperature is equal to or higher than 58 ° C., both the engine radiator 9 and the cooling fan 24 of the motor radiator 16 are turned on in step 58.

Next, the operation state of each area, that is, the areas of FIGS. 3A to 3G will be described.
Area (a): [Motor water temperature and engine water temperature are sufficiently low]
FIG. 10 shows the state of water flow in this case. The thermostat 7 is open to the bypass path 13 side, and does not flow water to the engine radiator 9. In addition, the electric pump 15 and the assist electric pump 19 do not operate, and do not flow water to the motor radiator 16.
Region (b): [When the engine water temperature is low but the motor water temperature rises]
FIG. 11 shows the state of water flow in this case. The vehicle runs with the motor 3 and the engine 1 is hardly operated. The thermostat 7 is open to the bypass path 13 side, and does not flow water to the engine radiator 9. The electric pump 15 operates, cools the motor 3 and the generator 2, and radiates heat with the motor radiator 16. The assist electric pump 19 is not operated, and exchange of cooling water between the engine cooling system and the motor cooling system is not performed.
Area (c): [Motor water temperature rises and engine water temperature is lower than motor water temperature]
FIG. 12 shows the state of water flow in this case. Since the engine water temperature is low, the thermostat 7 is open to the bypass path 13 side, and the cooling water of the engine cooling system does not flow to the engine radiator 9. The electric pump 15 operates, cools the motor 3 and the generator 2, and radiates heat with the motor radiator 16. Here, the assist electric pump 19 is operated, and the low-temperature cooling water radiated by the engine radiator 9 flows into the cooling water inlet 17 of the motor radiator 16. Here, by mixing with high-temperature cooling water in the motor cooling system, the motor water temperature is lowered. After flowing in the cooling water, the heat is radiated by the motor radiator 16, then flows into the radiator inlet pipe 8 of the engine radiator 9 by the return pipe 21, is further radiated by the engine radiator 9, and cools down. Then, it flows again into the motor cooling system. That is, the engine radiator 9 also contributes to the heat radiation of the motor 3.
Area (d): [Motor water temperature is low, but engine water temperature rises]
FIG. 13 shows the water passing state in this case. Since the engine water temperature is high, the thermostat 7 opens to the engine radiator 9 side. On the other hand, the electric pump 15 does not operate, and does not flow water to the high-temperature cooling water motor 3 and the generator 2 in the motor cooling system. At this time, the assist electric pump 19 is operated to cause high-temperature cooling water in the engine cooling system to flow into the motor cooling system, radiate heat by the motor radiator 16, and return to the radiator of the engine radiator 9 by the return pipe 21. The heat is exchanged by flowing back to the inlet pipe 8 and mixing with the cooling water in the engine cooling system. That is, the motor radiator 16 is used for cooling the engine.
Area (e): [When both the motor water temperature and the engine water temperature rise]
FIG. 14 shows the water passing state in this case. Since the engine water temperature is high, the thermostat 7 opens to the engine radiator 9 side. The electric pump 15 operates, cools the motor 3 and the generator 2, and radiates heat with the motor radiator 16. Here, the assist electric pump 19 does not operate, and the cooling system for the engine and the cooling system for the motor perform cooling independently of each other.

  On the other hand, the cooling fans 24 and 25 are operated when the heat radiation is inevitably insufficient (when the water temperature approaches the limit water temperature) to perform forced air cooling to secure the heat radiation amount. The purpose is to reduce the power consumed by the cooling system, and the cooling fans 24 and 25 are not operated as much as possible. Therefore, the electric pump 15 and the assist electric pump 19 are controlled so that the area of the heat exchanger is effectively used. Priority is given to heat dissipation through natural convection. That is, the cooling fan 24 of the engine radiator 9 operates when the engine water temperature exceeds 95 ° C., and the cooling fan 25 of the motor radiator 16 operates when the motor water temperature exceeds 58 ° C.

  Thus, the exchange of the cooling water between the engine cooling system and the motor cooling system is enabled, and the exchange of the cooling water is controlled while monitoring the engine water temperature and the motor water temperature. In a region where cooling performance is required, the engine radiator 9 is used for motor cooling, and in a region where cooling performance of the engine 1 is required, the motor radiator 16 is used for engine cooling to ensure high cooling performance. For example, the water temperature of the motor does not exceed the specified value due to the priority of the engine cooling, the water temperature in each cooling system can be finely controlled, and efficient cooling suitable for the operation state can be performed.

  Further, since the exchange of the cooling water between the engine cooling system and the motor cooling system having different water temperatures can be controlled according to the respective water temperature differences, the water temperature hunting when the exchange is switched can be reduced.

  In addition, since the battery 33 is disposed in the center of the vehicle 30 under the floor away from the engine room 31 and the radiator 9 for the engine is installed on the front side of the vehicle 30 in the housing 34 surrounding the battery 33, the radiator 9 for the engine The following advantages are provided in addition to the fact that the cooling of the battery 33 can be performed by the same fan 24 together with the cooling.

  That is, since traveling wind can be expected during traveling, it is most effective to place a heat exchanger at the front end of the vehicle. Therefore, the radiator 16 for the motor 3 mainly used during traveling is arranged at the front end of the engine room 31. On the other hand, when the vehicle stops, there is a so-called blow-back phenomenon in which hot air in the engine room 31 flows around and is sucked into the heat exchanger. Therefore, it is better to keep the heat exchanger as far away from the engine room 31 as possible. Therefore, by disposing the radiator 9 for the engine 1 which may be operated for charging when the vehicle is stopped in the central portion under the floor of the vehicle 30 away from the engine room 31, the low-temperature airflow as far as possible behind the vehicle is sucked. The performance of the engine radiator 9 is ensured. As a result, good heat radiation performance of the engine radiator 9 and the motor radiator 16 can be ensured, and the above-described control allows the radiator to operate under the conditions of the front of the vehicle and the center under the floor under the condition where the cooling performance is required. Therefore, high heat radiation performance of the engine radiator 9 and the motor radiator 16 can be ensured under all conditions.

  As described above, the heat transfer areas of the radiators 9 and 16 can be effectively used, the power consumption of the cooling fans 24 and 25 can be reduced, and thus the reliability of the engine 1 and the motor 3 can be improved, and the area and weight of the heat exchanger As a result, the fuel consumption can be improved.

1 is a configuration diagram of a system according to an embodiment. It is an arrangement | positioning block diagram. It is a characteristic view showing a control map. It is a flowchart which shows the control content. It is a flowchart which shows the control content. It is a flowchart which shows the control content. It is a flowchart which shows the control content. It is a flowchart which shows the control content. It is a flowchart which shows the control content. It is explanatory drawing of a water flow situation. It is explanatory drawing of a water flow situation. It is explanatory drawing of a water flow situation. It is explanatory drawing of a water flow situation. It is explanatory drawing of a water flow situation. FIG. 9 is a configuration diagram of a conventional example.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Engine 2 Generator 3 Electric motor 4 Engine cooling system 5 Motor cooling system 6 Engine outlet piping 6
Reference Signs List 7 Thermostat 8 Radiator inlet pipe 9 Radiator 10 Radiator outlet pipe 11 Engine inlet pipe 12 Water pump 13 Bypass path 14 Cooling system path 15 Electric pump 16 Radiator 17 Cooling water inlet 18 Communication pipe 19 Assist electric pump 20 Cooling water outlet 21 Return Piping 22, 23 Sensor 24, 25 Cooling fan 26 Control unit 30 Vehicle 31 Engine room 33 Battery 34 Housing 35 Ventilation hole 37 Sensor

Claims (4)

A vehicle capable of traveling by an electric motor, comprising: a generator driven by an engine; and a battery for storing generated electricity, a motor cooling system for cooling the electric motor, and cooling the engine. A cooling system for a hybrid electric vehicle, comprising:
The engine cooling system is formed so as to circulate cooling water by an engine-driven mechanical pump, and includes a thermostat that controls water flow to a radiator.
The cooling system for the motor is formed so that cooling water can be circulated by a positive displacement electric pump having a water cutoff function when stopped.
The engine cooling system and the motor cooling system are communicated with each other through a circulation pipe, and a positive displacement electric pump having a water cutoff function when the circulation pipe is stopped is provided in the circulation pipe,
A sensor is provided for detecting a water temperature in the engine cooling system and a water temperature in the motor cooling system, respectively.
A cooling system for a hybrid electric vehicle, wherein the electric pump and the assist electric pump are driven according to signals from these sensors.   Under the condition that the water temperature in the engine cooling system is lower than the predetermined value, the thermostat is closed, and the water temperature in the motor cooling system is higher than the predetermined value, the electric pump and the assist electric pump are operated and the engine cooling system is operated. 2. The cooling system for a hybrid electric vehicle according to claim 1, wherein cooling water is exchanged between the cooling water and the motor cooling system. 3.   Under the condition that the water temperature in the engine cooling system is higher than a predetermined value, the thermostat is open, and the water temperature in the motor cooling system is lower than the predetermined value, the assist electric pump is operated, the electric pump is stopped, and the engine is stopped. The cooling system for a hybrid electric vehicle according to claim 1, wherein cooling water is exchanged between a cooling system for the motor and a cooling system for the motor.   The battery is disposed at a position away from the engine room, the sides of the battery are surrounded by a pair of casings, and a radiator of an engine cooling system is installed on the vehicle front side of the casing, and cooling air passing through the radiator is used. The cooling system for a hybrid electric vehicle according to claim 1, wherein the battery is cooled.

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