JP2013064379A - Cooling apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove air remaining in a cooling liquid circulation path for cooling a drive motor.SOLUTION: A cooling apparatus includes a pump that circulates a cooling liquid in a circulation path, a heating device that heats the cooling liquid in the circulation path, a temperature detection device that detects the temperature of the cooling liquid, and a control device. If a determination device determines that air bleed is required, and the temperature detection device detects a temperature not higher than a reference temperature, the heating device operates, and the pump is rotated at a high speed rotation for air bleed. If the determination device determines that the air bleed is required, and the temperature detection device detects a temperature not lower than the reference temperature, the pump is rotated at the high speed rotation for air bleed without actuating the heating device. The cooling liquid is heated to reduce viscosity when the temperature is low, so that air can be bled even at a pump rotation speed at which air cannot be bled at a low temperature.

Description

  In this specification, the cooling device provided with the circulation path is disclosed. In particular, a device that is mounted on a vehicle including a motor that applies driving force to driving wheels and cools at least the motor is disclosed. The technique described in this specification can be used for cooling a motor, cooling a motor and a PCU, cooling a PCU, and the like.

  A hybrid vehicle, an electric vehicle, a fuel cell vehicle, and the like include a motor that applies a driving force to driving wheels, and a device that cools the motor. An apparatus for efficiently cooling a motor using a coolant and a circulation path has been developed. In the apparatus, the circulation path extends in a range in contact with the motor, and heat generated by the motor is transferred to the coolant. In order to cool the heated coolant, the circulation path makes a circuit between the radiator (heat radiator) and the motor. The radiator cools the coolant by radiating heat to the atmosphere.

  In order to efficiently transfer the heat generated by the motor to the coolant, the circulation path is bent in a complicated manner in the range in contact with the motor. Further, since it is necessary to make a circuit between the radiator and the motor in the engine compartment housing various devices, the circulation path extending in the engine compartment is bent in a complicated manner. If the circulation path is bent in a complicated manner, particularly if it is bent in the vertical direction, air mixed in the circulation path may remain in the position (trapped), and air may remain in the circulation path. In particular, when an empty circulation path is filled with cooling liquid, air is easily trapped in the circulation path, and even if a pump that circulates the cooling liquid is operated, air may remain in the circulation path. . If air remains in the circulation path, the cooling capacity will decrease. Or the wear of the pump is promoted.

  Therefore, a technique for extracting air trapped in the circulation path has been developed. In the technique of Patent Document 1, when there is a possibility that air is trapped in the circulation path, the pump for circulating the coolant is rotated at a high speed. The rotational speed at that time is set to a rotational speed at which the air trapped in the circulation path can be pushed away into the reservoir tank by vigorously circulating the coolant. Hereinafter, the rotational speed is referred to as a high speed rotational speed for air venting.

JP 2005-57953 A

  As a result of research, the rotational speed at which the air trapped in the circulation path can be swept into the reservoir tank by vigorously circulating the cooling liquid, that is, the high speed rotational speed for venting, varies depending on the temperature of the cooling liquid. There was found. The coolant has a viscosity, and the viscosity changes depending on the temperature of the coolant. It becomes low viscosity at high temperatures and high viscosity at low temperatures. When the coolant is high temperature and low in viscosity, the coolant can be circulated vigorously, so the high-speed rotation speed for air venting may be low. On the other hand, when the coolant is low temperature and highly viscous, it is difficult to circulate the coolant vigorously, so that the high-speed rotation speed for air venting is increased.

  If the high-speed rotation speed for air venting is set to a high-speed rotation speed that allows the cooling liquid to circulate vigorously even if the cooling liquid is cold and highly viscous, the temperature of the cooling liquid can be adjusted. Air can be extracted without depending on it. In that case, however, a high-performance pump capable of high-speed rotation must be installed. Higher performance pumps are more expensive and larger and are not a practical choice.

  In the present specification, a technology is disclosed that enables air to be vented at a low temperature with a pump rotation speed that allows air to be ventilated because the coolant is high temperature and low viscosity. That is, a technique is disclosed in which air can be vented at a pump rotational speed such that air cannot be vented if the coolant is in a low temperature and highly viscous state.

The cooling device disclosed in this specification is mounted on a vehicle including a motor that applies driving force to driving wheels, and cools at least the motor. The cooling device detects a temperature of the coolant in the circulation path, a circulation path through which the coolant circulates, a pump for circulating the coolant in the circulation path, a heating device for heating the coolant in the circulation path, and the like. A temperature detection device, a determination device for determining whether air is likely to be mixed in the circulation path, and a control device are provided. The circulation path extends in a range in contact with the motor.
The control device 1) When it is determined that there is a possibility that air is mixed in the determination device and when the temperature detection device detects a temperature below the reference temperature, the heating device is operated and the pump is vented. 2) If it is determined that there is a possibility that air is mixed in the determination device and if the temperature detection device detects a reference temperature or higher, do not operate the heating device. Rotate the pump at high speed for venting.

In the above, “below the reference temperature and above the reference temperature” is not defined by mathematics, and is a generic term for “below the reference temperature and above the reference temperature” and “below the reference temperature and above the reference temperature”. doing.
The high-speed rotation speed for air release means that air can be extracted when the coolant is above the reference temperature and low viscosity, but air is extracted when the coolant is below the reference temperature and high viscosity. The pump speed is not possible.

  According to the above cooling device, the cooling liquid is heated to lower the viscosity at a low temperature, so that the cooling liquid is below the reference temperature, and therefore the pump rotation speed should not be able to extract air when the viscosity is high. However, the air can be removed. It avoids the need for a high-performance pump to vent the air at low temperatures, and enables the pump to have a performance that allows air to be vented at high temperatures.

  According to the technique described in the present specification, it is possible to employ a pump having such a performance that air can be vented at a high temperature. An inexpensive and small pump can be used.

It is a block diagram which shows the structure of the hybrid vehicle of an Example. It is a figure which shows the cooling device mounted in the hybrid vehicle of an Example. It is a flowchart which shows the processing content 1 which hybrid ECU performs. It is a flowchart which shows the processing content 2 which hybrid ECU performs. It is a timing chart which shows the change of the number of rotations of a pump. It is the figure which showed the process in which the air which remained in the circulation path is removed. It is a figure which shows the modification of the cooling device mounted in the hybrid vehicle.

The main features of the embodiments shown below are listed.
(Feature 1) The circulation path circulates between the motor and the PCU that adjusts the power supplied to the motor.
(Characteristic 2) The cooling liquid heating device is also used as a device necessary for other applications.

  With reference to FIG. 1, the structure of the hybrid vehicle carrying the cooling device of an Example is shown. The hybrid vehicle 1 includes an engine 10, a motor 6, a generator 20, a main battery 36, an auxiliary battery 30, a PCU (Power Control Unit) 14, a hybrid ECU (Electronic Control Unit) 22, and a pump 12. And a sensor 13 for detecting the temperature of the coolant, a power distribution mechanism 8, a speed reducer 4, a drive wheel 2, an ignition switch 34, and the like.

  The driving force generated by the engine 10 is divided into two paths by the power distribution mechanism 8. One rotates the drive wheel 2 via the speed reducer 4. The other generates electricity by rotating the generator 20.

  The electric power generated by the generator 20 is selectively used according to the traveling state of the vehicle and the state of charge (SOC) state of the main battery 36. For example, during rapid acceleration, the electric power generated by the generator 20 is supplied to the motor 6. When the SOC of the main battery 36 is lower than a predetermined value, the electric power generated by the generator 20 is converted from AC to DC by the inverter 16 built in the PCU 14, and the voltage is adjusted by the converter 18. Is stored in the main battery 36.

  The motor 6 is driven by at least one of the electric power stored in the battery 36 and the electric power generated by the generator 20. The driving force of the motor 6 is transmitted to the driving wheel 2 via the speed reducer 4. The motor 6 assists the engine 10 to rotate the driving wheel 2 or rotates the driving wheel 2 by the motor 6 alone.

  When the hybrid vehicle 1 is braked, the motor 6 is driven by the drive wheels 2 via the speed reducer 4, and the motor 6 operates as a generator. The motor 6 operates as a regenerative brake that converts braking energy into electric power. The electric power generated by the motor 6 is stored in the main battery 36 via the inverter 16 and the converter 18.

The hybrid ECU 22 includes a CPU (Central Processing Unit) 24, a memory 26, and a flag 28. The CPU 24 calculates the accelerator opening, the amount of depression of the brake pedal, the shift position, and the SOC of the main battery 36 based on a map and a program stored in the memory 26. Accordingly, the hybrid ECU 22 controls the devices mounted on the vehicle so that the vehicle is in a desired traveling state. The hybrid ECU 22 is electrically connected to the terminal of the auxiliary battery 30 via the connector 32.
When the hybrid vehicle 1 is operated, the engine 10, the generator 20, the motor 6, and the PCU 14 generate heat. The cooling device of this embodiment cools the motor 6 and the PCU 14. The engine 10 and the generator 20 are cooled by separate cooling devices.

  With reference to FIG. 2, the cooling apparatus 54 concerning an Example is demonstrated. The cooling device 54 includes a circulation path 40. The circulation path 40 goes around the reservoir tank 44, the PCU cooling unit 48 that cools the PCU 14, the motor cooling unit 50 that cools the motor 6, and the radiator (heat radiator) 52. The reservoir tank 44 is located at the uppermost part of the circulation path 40. A pressure cap 42 is provided above the reservoir tank 44. When the pressure cap 42 is removed, the coolant inlet 46 is opened, and the coolant can be injected into the reservoir tank 44. A water level sensor (not shown) is arranged in the reservoir tank 44.

  If normal, the circulation path 40 is filled with a coolant. When the pump 12 is operated, the coolant cools the motor 6 by passing through the motor cooling unit 50, and the coolant is cooled by passing through the radiator 52, and is temporarily stored in the reservoir tank 44, and then cooled by the PCU. The PCU 14 is cooled by passing through the section 48 and returned to the pump 12. The order in which the coolant flows is not limited to this.

  As shown in FIG. 2, the circulation path 40 has a complicated shape that descends or rises in the middle. In particular, the PCU cooling unit 48 and the motor cooling unit 50 have a structure that moves in a complicated manner in order to increase the cooling efficiency. Therefore, when filling the empty circulation path 40 with the cooling liquid, even if the cooling liquid is injected into the reservoir tank 44 while the pump 12 is operated, air remains in various places in the circulation path 40. If air remains in the circulation path 40, the cooling capacity of the motor 6 and the PCU 14 is reduced. Further, the pump 12 is worn out in a short period of time.

  If the pump 12 continues to be operated even after a sufficient amount of coolant has been injected into the reservoir tank 44, the air remaining in the circulation path 40 may be returned to the reservoir tank 44 together with the coolant. When the air is returned to the reservoir tank 44, the air is extracted from the circulation path 40.

  In the cooling device of the embodiment, the vertical movement of the circulation path 40 is severe, and air cannot be extracted from the circulation path 40 even if the pump 12 is continuously operated as usual. If air remains in the circulation path 40, the air cannot be removed from the circulation path 40 unless special processing is performed.

A program executed by the hybrid ECU 22 will be described with reference to FIG. The process of FIG. 3 is executed while the ignition switch 34 is turned off.
In step S <b> 2, the hybrid ECU 22 determines whether or not the auxiliary battery 30 has been removed from the hybrid vehicle 1.
At the time of shipment from the factory, the circulation path 40 is filled with the coolant. At the time of shipment from the factory, the air venting process is carefully implemented. When maintaining or exchanging parts related to the circulation path 40, the coolant may be removed from the circulation path 40. When the parts related to the circulation path 40 are maintained and replaced, the auxiliary battery 30 is removed. If the auxiliary battery 30 is removed, step S2 becomes NO and the unconnected flag is turned on in step S4. If the auxiliary battery 30 is not removed, the unconnected flag is not turned on. If the non-connected flag is on, it can be seen that the auxiliary battery 30 has been removed, and that the coolant may have been removed from the circulation path 40.

  Even if the auxiliary battery 30 is not removed, the coolant may be extracted from the circulation path 40. For this purpose, in step S6, it is determined whether or not the water level in the reservoir tank 44 has dropped below the first reference water level, and if so, the drop flag is turned on (step S8). In step S12, it is determined whether or not the water level in the reservoir tank 44 has risen above the second reference water level, and if it rises, the rising flag is turned on (step S14). The first reference water level is lower than the second reference water level, and is set to a water level that drops below the first reference water level when the coolant is removed from the circulation path 40. The second reference water level is equal to or higher than the first reference water level, and is set to a water level that rises above the second reference water level when the coolant is supplemented to the circulation path 40. Steps S12 and S14 are executed only after the lowering flag is turned on (step S10). After the ignition switch 34 is turned off, the coolant is removed from the circulation path 40 (decreases below the first reference water level), and then the coolant is replenished to the circulation path 40 (rises above the second reference water level). If so, the rising flag is turned on.

The process of FIG. 4 is executed while the ignition switch 34 is turned on. Alternatively, the process of FIG. 4 may be executed while the READY switch is on.
In step S20, it is determined whether or not the unconnected flag is on. If it is ON, there is a possibility that the coolant has been once extracted from the circulation path 40 when the auxiliary battery 30 is removed and inspections are carried out.
In step S22, it is determined whether or not the rising flag is on. If it is ON, the coolant may have been replenished after being extracted from the circulation path 40, and therefore the process proceeds to the air venting process after step S28.

  As will be described later with reference to step S26, when air venting is unnecessary, the temperature of the coolant is detected, and the current value stored in the map is read in association with the temperature and read. The pump 12 is driven with the current value. That is, the target rotational speed of the pump is determined by the temperature of the coolant, and the pump 12 is driven with a current value that should rotate at the target rotational speed. If the load of the pump 12 is as expected, the pump 12 rotates at a target rotational speed determined by the temperature of the coolant.

  In step S24, it is determined whether or not the difference between the actual rotational speed of the pump 12 and the target rotational speed exceeds the reference rotational speed. When air is mixed in the coolant, the load on the pump 12 is reduced. For this reason, the actual rotational speed rises above the target rotational speed. If the difference between the actual rotational speed and the target rotational speed is greater than or equal to the reference rotational speed, it is determined that air is mixed and that air removal processing is required. Details of this technique are described in JP-A-2008-95570.

If YES is obtained in any of steps S20, S22, and S24, the air bleeding process after step S24 is performed. Actually, it may not be necessary to carry out the air venting process, but it may be necessary.
In the present embodiment, a discrimination device that discriminates whether or not there is a possibility that air is mixed in the circulation path is realized by the hybrid ECU 22 that performs the processes of FIGS. 3 and 4.
In the present embodiment, the three conditions of steps S20, S22, and S24 are determined by OR logic to determine whether or not air may be mixed in the circulation path. Alternatively, one or two of the conditions may be employed.

  In step S28, the coolant temperature is detected by the temperature sensor 13, and it is determined whether or not the coolant temperature is equal to or lower than a reference temperature (T ° C.). The reference temperature (T ° C.) is determined based on the viscosity of the coolant and the performance of the pump 12. The viscosity of the coolant varies with temperature, and becomes low at high temperatures and high at low temperatures. The performance of the pump 12 is not high, and when the coolant is below the reference temperature (T ° C.) and highly viscous, the air cannot be extracted even if the pump 12 is driven at a high speed for air removal. . However, when the coolant is higher than the reference temperature (T ° C.) and has a low viscosity, the air can be extracted by driving the pump 12 at a high rotational speed for removing air.

  If it is determined in any of steps S20, 22, and 24 that the air venting process is necessary, and it is determined in step S28 that the coolant is below the reference temperature and is highly viscous, the pump 12 is turned on for high speed for air venting. The air is not completely vented only by rotating at the rotational speed. Therefore, step S30 is performed. In step S30, the viscosity is lowered by heating the coolant. Thereafter, step S32 is performed. In step S32, the pump 12 is rotated at a high speed for releasing air. As shown in step S34, the pump 12 is rotated at a high speed for a reference time required for the air venting process. If the coolant is heated to a reference temperature or higher during the air venting operation, step S30 is skipped thereafter. That is, the air venting operation is continued in a state where the coolant is heated to the reference temperature. When the pump 12 is rotated at a high speed for the reference time required for the air venting process, the control is returned to the normal rotation speed control shown in step S26. When step S26 is performed, as described above, the pump 12 is operated so as to achieve the target rotational speed determined by the temperature of the coolant. This is shown in FIG.

If it is determined in any of steps S20, 22, and 24 that the air venting process is necessary, and if it is determined in step S28 that the coolant is above the reference temperature and has low viscosity, the pump 12 is operated in step S32. . In this case, step S30 is not executed. In step S32, the pump 12 is rotated at a high speed for releasing air. When the coolant is above the reference temperature and has a low viscosity, the air venting process is executed when the pump 12 is rotated at a high speed for air venting. When the pump 12 is rotated at a high speed for a reference time required for the air venting process, the control is returned to the normal rotation speed control shown in step S26. When the air venting process is finished, turn off the unconnected flag and turn off the flag a little.
The control unit for controlling the heating device and the pump during the air venting operation is realized by the hybrid ECU 22 that performs the processing after step S26.

  The PCU 14 includes a capacitor and a reactor device. When the capacitor is charged and discharged via the reactor device, the reactor device and the capacitor generate heat. When the PCU 14 generates heat, the coolant is heated while passing through the PCU cooling unit 48. Some vehicles include a heater (PCT heater) for preventing freezing in the circulation path 40. In that case, the coolant can be heated by operating the PCT heater. It is not necessary to add a dedicated machine for heating the cooling liquid, and the cooling liquid can be heated using equipment existing for other uses.

  If the coolant is above the reference temperature and low in viscosity, the pump 12 is rotated at a high speed for air venting, so that the upper part of the PCU cooling unit 48 and the motor cooling unit 50 is shown in FIG. As shown in FIG. 6B, the air remaining in the air is pushed into the reservoir tank 44 together with the coolant. Air is released into the atmosphere in the reservoir tank. As a result, the air remaining in the PCU cooling unit 48 and the motor cooling unit 50 is removed.

  If the coolant is below the reference temperature and highly viscous, the coolant is heated to the reference temperature and the pump 12 is rotated. As a result, air can be vented at a pump speed that cannot be vented if the temperature remains low.

<Modification>
As shown in FIG. 7, the branch pipe 56 may be branched from the circulation path 40 and a pressure cap 58 may be attached to the upper end opening. In this case, if the pressure cap 58 is removed, air can be extracted therefrom.
In the present embodiment, the cooling device mounted on the hybrid vehicle 1 including the engine 10 and the motor 6 is disclosed. However, the present invention is not limited to this and can be applied to a fuel cell vehicle and an electric vehicle. . Moreover, although the cooling device of an Example cools PCU14 and the motor 6, the cooling object is not restricted to these. The vent hole for removing the remaining air may be formed integrally with the reservoir tank 44 or may be provided in the circulation path 40 in the middle. Alternatively, a plurality of vent holes may be provided.

  The above examples are illustrative and not limiting. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

2: Drive wheel 4: Reducer 6: Motor 8: Power distribution mechanism 10: Engine 12: Pump 13: Temperature detection sensor 14: PCU
20: Generator 22: Hybrid ECU 22
30: Auxiliary battery 36: Main battery 40: Circulation path 44: Reservoir tank 48: PCU cooling unit 50: Motor cooling unit 52: Radiator 54: Cooling device

Claims (1)

It is a cooling device mounted on a vehicle equipped with a motor that applies driving force to the driving wheels,
A circulation path extending through the range in contact with the motor and circulating the coolant;
A pump for circulating the coolant in the circulation path;
A heating device for heating the coolant in the circulation path;
A temperature detection device for detecting the temperature of the coolant in the circulation path;
A discriminating device for discriminating whether air may be mixed in the circulation path;
If the discriminator determines that there is a possibility and if the temperature detector detects a temperature below the reference temperature, the heater is operated and the pump is rotated at a high speed for air bleeding. And a control device that rotates the pump at a high speed for air bleeding without operating the heating device when the temperature detection device detects a temperature higher than the reference temperature, and
Equipped with a cooling device.

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