JP7035559B2 - Electric vehicle - Google Patents

Description

The present invention relates to a cooling mechanism for a drive motor or the like in an electric vehicle.

The following Patent Document 1 describes a hybrid type electric vehicle equipped with a vehicle drive motor and an engine. In this electric vehicle, the oil used for cooling and lubricating the drive motor and the power split mechanism is circulated in cooperation with a mechanical pump operated by the torque of the engine and an electric pump operated by a dedicated electric motor. Then, the electric pump is controlled so as to flow the required flow rate according to the state of the electric vehicle such as the READY state after the vehicle is started, the temperature state of the vehicle drive motor while the vehicle is being driven by the vehicle drive motor, and the running state by the engine. Is being done.

Japanese Unexamined Patent Publication No. 2016-052844

Some electric vehicles include a switch for switching the traveling characteristics of the vehicle based on the user's selection. When the traveling characteristics are switched, it is considered that the cooling amount of the vehicle drive motor may be different. However, Patent Document 1 does not describe or suggest such a situation.

An object of the present invention is to improve the appropriateness of cooling of an electric vehicle according to a traveling characteristic selected by a user.

The electric vehicle of the present invention includes a motor for driving a vehicle, an electric pump that circulates and cools a coolant flowing in a cooling system of the motor, a reception means that accepts a user to select a mode for driving characteristics, and the above. The control means for controlling the output of the motor according to the mode, and the circulation amount of the coolant by the electric pump are changed according to the mode, and the coolant by the electric pump is changed according to the increase in vehicle speed. It is provided with a changing means for increasing the circulation amount and increasing the circulation amount of the coolant by the electric pump in response to an increase in the temperature of the motor or the temperature of the coolant .

An electric vehicle is a vehicle equipped with a drive motor as a drive source. In addition to a vehicle that uses only a drive motor as a drive source, a vehicle that also uses another drive source such as an internal combustion engine is also included in the electric vehicle. In this vehicle, the user can select a mode for driving characteristics. The selection is made, for example, by operating an operation button on the instrument panel of the vehicle, or by voice input by the user. The running characteristics refer to characteristics characteristic of running, such as acceleration characteristics during running and power consumption characteristics during running. Further, the mode for driving characteristics means that such driving characteristics are set so as to be changeable with some tendency. Specifically, a mode in which acceleration characteristics are enhanced in some or all speed bands, a mode in which acceleration characteristics are enhanced when climbing a slope, a mode in which power consumption is suppressed in some or all speed bands, and the like are exemplified. be able to.

In an electric vehicle, the output of the motor is controlled based on the mode selected by the user. When the torque from the motor is transmitted to the axle through the gear, it may be possible to directly or indirectly control the output of the motor by controlling the switching of the gear. The changing means changes the circulation of the coolant flowing in the cooling system of the motor corresponding to this mode. The cooling system of a motor means a cooling path related to cooling of the motor. When the motor is cooled by a one-stage cooling path, that cooling path is the cooling system of the motor. When the motor is cooled by the two-stage cooling path, for example, the coolant cooled in the first-stage cooling path cools the coolant in the second-stage cooling path, and the second-stage cooling path cools the motor. When it is cooled, it can be said that both the first-stage cooling path and the second-stage cooling path are the cooling systems of the motor. The cooling system of the motor is provided with one or more electric pumps to circulate the coolant. In the changing means, the circulation amount of the coolant by one or two or more electric pumps is changed according to the mode of the traveling characteristic selected by the user. Of course, the circulation amount may be changed depending on other factors such as the motor temperature, the coolant temperature, the vehicle speed, and the like. In this case, the changing means may change the circulation amount according to the mode, for example, in a situation where other elements are included in a specific range.

According to the present invention, it is possible to improve the appropriateness of cooling the motor as compared with the case where the motor for driving the vehicle is uniformly cooled regardless of the mode of the traveling characteristic. This can be expected to have the effect of achieving both the appropriateness of cooling the motor and the power saving of the electric pump for cooling.

It is a figure which shows the schematic structure of the electric vehicle which concerns on this embodiment. It is a figure which shows three control areas of an oil pump in a normal mode. It is a figure which shows the movement condition between regions. It is a figure which shows the control mode of the oil pump in each region. It is a figure explaining the control mode when the LLC temperature is low in the region A. It is a figure which shows the change state of the control area of an oil pump in a power mode. It is a figure which shows the cooling system which concerns on the modification.

Hereinafter, embodiments will be described with reference to the drawings. In the description, specific embodiments are shown for ease of understanding, but these are examples of embodiments, and various other embodiments can be taken.

FIG. 1 is a diagram showing a part of the structure of the electric vehicle 10 according to the present embodiment. FIG. 1 shows a body 12 and front wheels 13 in front of an electric vehicle, and also shows a schematic configuration of various devices housed inside the body 12.

The electric vehicle 10 is equipped with a battery (not shown), and DC power is supplied from the battery to the power control unit (PCU) 14. The PCU 14 is equipped with a charger, a booster and an inverter. A charger is a device that supplies electric power supplied from outside the vehicle to a battery through a power plug or the like. A booster is a device that boosts or boosts the voltage of DC power. In addition, the inverter is a device that converts DC power into AC power, and also has a converter function that converts AC power into DC power. The DC power supplied from the battery is boosted or boosted by a booster as needed, and then converted into three-phase AC power by an inverter. Then, the three-phase AC power is supplied to the motor generator (called MG) 16.

The MG 16 is a vehicle drive motor that converts three-phase AC power into rotary motion. The MG 16 includes a stator with a coil and a rotor installed inside the stator. A plurality of permanent magnets are embedded in the rotor, and a plurality of magnetic poles are formed. The rotor receives a force from a rotating magnetic field generated by the coil of the stator by three-phase AC electric power and rotates around the rotor shaft to generate torque for driving the vehicle. This torque is transmitted to the front wheels 13 through the drive shaft to drive the electric vehicle 10. The MG 16 also functions as a generator that generates electricity by using the torque transmitted from the drive shaft. The generated power is stored in the battery through the PCU 14.

A condenser 18 which is a heat exchanger for an air conditioner is provided at the frontmost portion of the electric vehicle 10. The condenser 18 is a device that cools and condenses a refrigerant that has been heated to a high temperature and high pressure by a compressor. The condensed refrigerant is vaporized to a low temperature and then used for cooling the air in the room. The vicinity of the upper part of the capacitor 18 becomes a high temperature state exceeding 100 degrees depending on the usage conditions, but the vicinity of the lower part of the capacitor 18 is maintained at a relatively low temperature.

A radiator 20 is provided on the lower rear surface of the condenser 18. The radiator 20 is a heat exchanger that cools LLC (Long Life Coolant), which is a kind of cooling water. A flow path 22a extends from the radiator 20 to the PCU 14. Further, the flow path 22b extends from the PCU 14 to the oil cooler 26. A flow path 22c extends from the oil cooler 26 to the radiator 20. The LLC works as a refrigerant while circulating in a series of cooling paths including these flow paths 22a. This circulation is driven by a water pump 28, which is an electric pump provided on the flow path 22a.

The oil cooler 26 is a heat exchanger that exchanges heat between LLC and cooling oil. A flow path 30a extends from the oil cooler 26 to the MG 16, and a flow path 30b extends from the MG 16 to the oil cooler 26. The cooling oil works as a refrigerant while circulating in a series of cooling paths including these flow paths 30a and 30b. This circulation is driven by an oil pump 32, which is an electric pump provided in the flow path 30a. The output of the oil pump 32 is controlled by PWM control by on / off switching of electric power. Specifically, when the duty ratio, which is the ratio of the time when the switch is turned on, is increased, the output is increased, and when the duty ratio is decreased, the output is decreased. The output of the oil pump 32 is substantially proportional to the circulation amount of the cooling oil circulated by the oil pump 32. Therefore, the oil pump 32 can control not only the on / off control of the circulation amount but also the circulation amount in the on state.

The electric vehicle 10 is provided with an ECU (Electric Control Unit) 34 that controls the vehicle. The ECU 34 is composed of hardware having a computer function and software such as programs and data used for its operation.

Data from various sensors are input to the ECU 34. In the example shown in FIG. 1, a temperature sensor 36 provided near the inlet of the PCU 14 in the flow path 22a measures the temperature of the LLC flowing through the flow path 22a, and the measured LLC temperature data is input to the ECU 34. Has been done. The temperature sensor 38 is installed in the PCU 14 at a portion where it can be directly monitored whether the PCU 14 has reached the heat resistant temperature or a portion where it can be indirectly estimated. Data on the PCU temperature is input to the ECU 34 from the temperature sensor 38. Further, a temperature sensor 40 for measuring the temperature of the cooling oil flowing through the flow path 30a is provided near the inlet of the MG 16 in the flow path 30a. Data of the cooling oil temperature measured by the temperature sensor 40 is also input to the ECU 34. Further, the MG 16 is provided with a temperature sensor 42 for measuring the coil temperature of the stator, and the motor temperature data measured by the temperature sensor 42 is also input to the ECU 34. From the coil temperature of the stator, the temperature of the permanent magnet stored in the rotor core can be estimated. Data regarding the speed of the electric vehicle 10 is also input to the ECU 34. Specifically, the rotation speed data per unit time of the rotor is input from the MG 16, and the speed data of the electric vehicle 10 is input from the speedometer 44 that measures the rotation speed of the axle of the front wheel 13.

The ECU 34 is provided with a mode reception unit 34a, a motor control unit 34b, and a cooling change unit 34c as functional configurations. Further, the motor control unit 34b stores the motor control table 34d as data for use in control, and the cooling change unit 34c includes a cooling control table 34e as data for use in control. The mode reception unit 34a performs a process of receiving the setting information of the traveling mode from the user. In the electric vehicle 10, two modes, "normal mode" and "power mode", are prepared as the traveling characteristic modes. Of these, the normal mode is the mode set by default. The user can switch between the normal mode and the power mode, and the mode receiving unit 34a receives the switching information and reflects it in the control of the ECU 34.

The motor control unit 34b acquires control information according to the traveling characteristic mode from the motor control table 34d and controls the MG 16. The motor control table 34d stores control modes such as step-up and step-down of the voltage sent from the PCU 14 to the MG 16 for each mode of the normal mode and the power mode. For example, in the motor control table 34d, it is assumed that the power mode is set to boost the voltage of the alternating current sent from the PCU 14 to the MG 16 by 10%, 20%, 30%, or 50% as compared with the normal mode. In this case, the motor control unit 34b controls to boost the voltage of the alternating current sent from the PCU 14 to the MG 16 in the power mode as compared with the normal mode. As a result, in the power mode, even if the motor rotation speed is the same as in the normal mode, the power consumption increases and a large acceleration force is generated.

The cooling change unit 34c refers to the cooling control table 34e and acquires control information according to the running characteristic mode, thereby changing to the cooling control according to the running characteristic mode and executing the changed cooling control. .. The cooling control table 34e is data in which the mode of cooling control of the PCU 14 and the MG 16 is set for each traveling characteristic mode. The cooling change unit 34c controls cooling according to the input data from the various sensors described above according to the software. Specifically, the cooling change unit 34c controls the start, increase, decrease, and stop of the LLC circulation in the water pump 28. It also controls the start, increase, decrease, and stop of the circulation of the cooling oil in the oil pump 32. The control mode of the water pump 28 or the oil pump 32 is defined in the cooling control table 34e for each running characteristic data, and the cooling change unit 34c controls by referring to the cooling control table 34e.

The mode button 46 is provided on the instrument panel around the driver's seat and is used by the user, the driver 48, to select a driving characteristic mode. The mode button 46 has two buttons, a NORMAL button 46a for selecting a normal mode and a POWER button 46b for selecting a power mode. The normal mode is set by default in the electric vehicle 10, and is a mode that is automatically selected when the user does not operate a button. Further, by pressing the NORMAL button 46a with the power mode selected, it is possible to switch to the normal mode. The POWER button 46b is a button for selecting a power mode.

Here, the operation of the electric vehicle 10 will be described. In the electric vehicle 10, the vehicle is driven according to the operation of the driver 48. The driver 48 can operate the mode button 46 in the process of driving. When the driver 48 does not operate the mode button 46, the normal mode set by default is selected, and when the driver 48 selects the mode button 46, the normal mode or the power mode is adopted according to the operation result. The ECU 34 receives the travel characteristic mode based on the user operation, and then refers to the motor control table 34d to perform drive control of the electric vehicle 10 according to the travel characteristic mode.

At this time, in the PCU 14, the temperature rises due to the consumption of a small amount of electric power by the semiconductor device or the like. Further, the MG 16 generates heat larger than that of the PCU 14 due to copper loss in the coil, iron loss in the permanent magnet and the core, and the temperature rises.

The heat resistant temperature of the PCU 14 is determined by the heat resistant temperature of the semiconductor device included in the PCU 14. The value is relatively low, for example, about 60 degrees Celsius to 80 degrees Celsius. Therefore, the PCU 14 is cooled by LLC. The LLC is circulated and driven in the cooling path by the water pump 28. Specifically, after being cooled by the outside air by the radiator 20, it is sent to the PCU 14 through the flow path 22a to cool the PCU 14. Subsequently, it is sent to the oil cooler 26 through the flow path 22b to cool the cooling oil. The temperature of LLC is higher than the initial temperature as a result of cooling the PCU 14, but since the PCU 14 has a relatively small calorific value and a low temperature, the cooling oil can be cooled. After that, the LLC is refluxed to the radiator 20 and cooled again.

The heat resistant temperature of MG 16 is determined by, for example, the degaussing temperature of a permanent magnet. The temperature at which degaussing of a permanent magnet occurs varies depending on the type of magnet material, and is, for example, about 100 degrees Celsius to about 300 degrees Celsius. Depending on the conditions, the heat-resistant temperature of the MG 16 may be lower than the heat-resistant temperature of the PCU 14, but in the present embodiment, it is assumed that the heat-resistant temperature of the MG 16 is higher than the heat-resistant temperature of the PCU 14.

The MG 16 is cooled by cooling oil and maintained below the heat resistant temperature. The cooling oil is circulated by the oil pump 32. Specifically, the cooling oil is cooled by the oil cooler 26 and then sent to the MG 16 through the flow path 30a. Then, after cooling the MG 16, it is returned to the oil cooler 26 through the flow path 30b.

The heat taken by the cooling oil from the MG 16 is given to the LLC through the oil cooler 26. Therefore, the waste heat of the PCU 14 is directly given to the LLC, and the waste heat of the MG 16 is indirectly given to the LLC. Then, these heats are released from the radiator 20 to the outside air. That is, in the electric vehicle 10, it can be said that the PCU 14 and the MG 16 are cooled by one cooling system. A single cooling system may reduce the weight of the device as compared to a two cooling system that cools the PCU 14 and MG 16 independently. In addition, there is a possibility that the manufacturing cost can be suppressed.

When constructing a single cooling system, parts having sufficient performance to cool the PCU 14 and MG 16 are selected. For example, as the radiator 20, a radiator 20 having a performance capable of releasing the maximum amount of heat emitted by the PCU 14 and the MG 16 under severe running conditions is adopted. Further, as the water pump 28 and the oil pump 32, those that can secure the required circulation amount at the maximum output are selected. However, if the water pump 28 and the oil pump 32 are always operated at the maximum output, the energy efficiency is deteriorated. In addition, since the pump makes a relatively loud noise, if it is operated wastefully, it will bring unnecessary noise to the electric vehicle 10. Therefore, it is desirable to cool at an appropriate level.

Further, in one cooling system, it is necessary to consider the cooling balance between the PCU 14 and the MG 16. For example, if the cooling of the MG 16 is sufficiently advanced, the temperature of the LLC rises through the oil cooler 26, and a situation may occur in which the PCU 14 cannot be sufficiently cooled. Therefore, it is desirable to proceed with cooling the MG 16 while monitoring the temperature of the LLC or the temperature of the PCU 14.

The cooling change unit 34c of the ECU 34 is programmed to control cooling in consideration of these various conditions. In particular, since the level of power consumption and the level of heat generation in the PCU 14 and MG 16 change depending on the selected driving characteristic mode, the cooling control is performed for each driving characteristic mode with reference to the cooling control table 34e. Will be done.

From the viewpoint of cooling the MG16, it can be said that a two-stage cooling system is constructed, that is, cooling by LLC and cooling by cooling oil. The cooling of the MG 16 is controlled by both the water pump 28, which is responsible for the cooling of the first stage, and the oil pump 32, which is responsible for the cooling of the second stage. The change in the cooling of the MG 16 is directly performed by changing the circulation amount of the oil pump 32, but it can also be performed by changing the circulation amount of the water pump 28, and both the water pump 28 and the oil pump 32 can be changed. It is thought that efficiency can be improved by doing this.

Hereinafter, the control of the oil pump 32 by the cooling change unit 34c of the ECU 34 will be described in detail with reference to FIGS. 2 to 6. In this description, it is assumed that the water pump 28 is operated with a constant delivery amount and then the oil pump 32 is controlled according to the situation. In the description, first, the control mode in the normal mode will be described with reference to FIGS. 2 to 5, and then the control mode in the power mode will be described with reference to FIG.

FIG. 2 is a diagram showing a control mode region of the oil pump 32 implemented in the normal mode. The horizontal axis is the vehicle speed of the electric vehicle 10 measured by the speedometer 44, and the left vertical axis is the motor temperature measured by the temperature sensor 42 of the MG 16. The right vertical axis shows the cooling oil temperature measured by the temperature sensor 40. There is no one-to-one relationship between the motor temperature and the cooling oil temperature, and the correspondence relationship changes depending on the conditions. However, in general, when the motor temperature rises, the cooling oil also rises in temperature, so that there is a high correlation.

In FIG. 2, it is divided into three regions, A region, B region, and C region, according to the vehicle speed and the motor temperature or the cooling oil temperature. The region A covers a state in which the motor temperature rises during low-speed running such as when climbing a long uphill, and a state in which the motor temperature rises to some extent during medium- and high-speed running. Specifically, in the A region, the vehicle speed is less than V2 and the motor temperature is T4 or more or the cooling oil temperature is U4 or more, the vehicle speed is V2 or more, and the motor temperature is T2 or more or cooling oil. The temperature is in the range of U2 or higher. However, among these conditions, the range in which the vehicle speed is V4 or higher and the motor temperature is T4 or higher or the cooling oil temperature is U4 or higher is classified in the B region. The other range is the C region. That is, in the C region, when the vehicle speed is from zero (stopped state) to less than V2, the motor temperature is less than T4 and the cooling oil temperature is less than U4, and when the vehicle speed is V2 or more, the motor temperature is less than T2 and cooling. The oil temperature is in the range of less than U2.

The boundaries of these areas can vary depending on the various conditions of the motor vehicle 10. However, exemplifying specific values, V2 can be about 10 km / h to 50 km / h, and V4 can be about 80 km / h to 120 km / h. The T2 value is about 60 degrees Celsius to 100 degrees Celsius, the U2 value is about 50 degrees Celsius to 90 degrees Celsius, the T4 value is about 90 degrees Celsius to 200 degrees Celsius, and the U4 value is about 80 degrees Celsius. About 150 degrees Celsius can be exemplified. However, in particular, since the conditions regarding the temperature differ greatly depending on the target location where the temperature is measured, it is fully assumed that the values outside the illustrated range are taken.

The electric vehicle 10 is classified into any of the A region to the C region according to the traveling state of the vehicle while traveling in the normal mode. Then, it moves in the A region to the C region according to the change in the vehicle speed and the change in the motor temperature or the cooling oil temperature. As a general rule, movement is done when the area of the new area is entered. However, if this condition is applied as it is, when the electric vehicle 10 shows a state near the boundary of each region, it is conceivable that the control operation becomes unstable due to frequent reciprocating of the boundary. Therefore, the conditions are slightly different between the case of moving from one area to another and the case of returning to the original area. Specifically, regarding the speed, V1 which is slightly slower than V2 (for example, about 5 km / h slower) and V3 which is slightly slower than V4 (for example, about 10 km / h slower) are set. The motor temperature is set to T1 which is slightly lower than T2 (for example, about 10 degrees Celsius lower) and T3 which is slightly lower than T4, and the cooling oil temperature is U1 which is slightly lower than U2 and U4 which is slightly lower than U4. A slightly lower U3 is set. Then, the area is changed according to the conditions shown in FIG.

FIG. 3 is a diagram showing conditions when moving between adjacent regions in the normal mode. The left line shows which area to move to which area, and the right line shows the conditions corresponding to the movement of the left line. For example, "C → A" means a movement from the C region to the A region. The condition is that if it belongs to the C region at a certain time, at the next time, "[Vehicle speed <V2 and [Motor temperature ≥ T4 or cooling oil temperature ≥ U4]]" or [Vehicle speed ≥ V2 and [Motor temperature ≥ T2] or Cooling oil temperature ≧ U2]] ”. That is, when the vehicle speed is less than V2 and the motor temperature is T4 or more or the cooling oil temperature is U4 or more, or the vehicle speed is V2 or more and the motor temperature is T2 or more or the cooling oil temperature is U2 or more. In the case, it moves to the A area. The cooling change unit 34c of the ECU 34 periodically checks the conditions shown in FIG. 3 (for example, every 1 second, every 5 seconds, etc.). Then, the oil pump 32 is controlled according to the region.

FIG. 4 is a diagram showing a mode in which the oil pump 32 is controlled for each of the regions A to C. In the region A, control is performed according to the LLC temperature, and when the LLC temperature is Tc or higher, control is performed to fix the transmission amount to a constant value (P% of the maximum output). When the LLC temperature is Tc or higher, the LLC temperature is relatively high, so that the PCU 14 cannot be sufficiently cooled. Therefore, the output of the oil pump 32 is limited to P% of the maximum output to suppress the cooling of the MG 16. The temperature of Tc depends on the heat resistant temperature of PCU14, but may be, for example, about 50 degrees Celsius to 80 degrees Celsius. Further, the value of P% is selected within a range in which an increase in LLC temperature can be suppressed. The specific value may vary depending on the conditions, but for example, an embodiment of about 30% to 70% can be considered.

In the region A, when the LLC temperature is less than Tc, control is performed to change the delivery amount in multiple stages according to the motor temperature. When the LLC temperature is less than Tc, the LLC is in a state where it can sufficiently cool the PCU 14. Therefore, it is possible to increase the cooling of the MG 16. Therefore, control is performed to sufficiently cool the MG 16 according to the motor temperature.

FIG. 5 is a diagram illustrating a control mode of the oil pump 32 when the LLC temperature is less than Tc in the A region. Here, the pump output on the vertical axis is set according to the value of the motor temperature on the horizontal axis. That is, the pump output is increased as the motor temperature rises, and the pump output is decreased as the motor temperature decreases. However, if the pump output is increased and decreased at the same motor temperature, the operation near this motor temperature may become unstable. Therefore, the motor temperature at which the pump output is decreased is set slightly lower than the motor temperature at which the pump output is increased.

Specifically, six threshold values of Tm0 to Tm5 are set for the motor temperature. Each temperature has a relationship of Tm0 <Tm1 <Tm2 <Tm3 <Tm4 <Tm5. Further, it is assumed that T2 <Tm1. The relationship between Tm1 to Tm5 and T3 or T4 can be arbitrarily set. In the process of increasing the motor temperature, the pump is stopped when the motor temperature is less than Tm1, and when the motor temperature becomes Tm1 or more, the pump is started and set to a value of 50% of the maximum value. Further, when the motor temperature rises to Tm3 or higher, the pump output is increased to 75% of the maximum value. When the motor temperature is Tm5 or higher, the pump output is maximized (100%). On the other hand, in the process of lowering the motor temperature, the pump output is lowered to 75% when the motor temperature is less than Tm4, the pump output is lowered to 50% when the motor temperature is less than Tm2, and the motor output is Tm0. If it becomes less than, the pump is stopped. The values of Tm0 to Tm5 are appropriately set in consideration of the cooling state of the motor. The output of the motor may be changed in more stages according to the motor temperature, or may be changed in the non-current stage according to the calculation formula.

In the above description, in the A region, the output of the oil pump 32 is fixed to a constant value when the LLC temperature is Tc or higher, and the oil pump 32 is set to 0% to 100% only when the LLC temperature is lower than Tc. Control was performed to change the temperature within the range of. However, it is also possible to control the oil pump 32 to fluctuate when the LLC temperature is Tc or higher. Specifically, it is possible to exemplify an embodiment in which the upper limit of the output is set to P% and the output is varied in the range of 0% to P% depending on the motor temperature. Further, in the above description, in the A region, the LLC temperature is controlled by dividing it into two cases of Tc or more and less than Tc, but the control is performed by dividing it into three or more cases according to the LLC temperature. You may do it.

Returning to FIG. 4, the description of the control of the oil pump 32 for each region will be continued. In region B, the oil pump 32 is set to maximum output. In the B region, the MG 16 is driven at a high rotation speed, so that the motor temperature becomes high and the situation is severe. Therefore, the oil pump 32 cools the MG 16 by maximizing the circulation amount of the cooling oil. As a result, a large amount of waste heat of MG 16 is transferred to LLC, but a large amount of heat is taken from the radiator 20 by the outside air flowing at high speed, so that the LLC temperature does not rise so much. Therefore, the PCU 14 can be sufficiently cooled.

In the C region, the oil pump 32 is stopped. Since the C region is a region where the motor temperature is lower than T2 and the need for cooling the MG 16 is low, such control is performed. Further, when the vehicle speed is less than V2, the oil pump 32 is stopped even in the range where the motor temperature is T2 or more and less than T4 so that the quietness of the electric vehicle 10 is not destroyed by the driving sound of the oil pump 32.

Next, the control of the oil pump 32 in the power mode will be described with reference to FIG. FIG. 6 is a diagram corresponding to FIG. 2, and shows a control mode region of the oil pump 32 implemented in the power mode. The difference between FIGS. 6 and 2 is that in FIG. 6, the A region in FIG. 2 is completely replaced by the B region. In the power mode, the MG 16 is driven by a high voltage AC voltage sent from the PCU 14. Therefore, it is expected that the temperature of MG 16 will be higher than that of the normal mode. Therefore, in the normal mode, the range that was the A region is changed to the B region, and the control is performed to maximize the circulation amount by the oil pump 32. This makes it possible to suppress the heating of MG 16. When the driver 48 switches to the power mode while belonging to the A region in the normal mode, the output of the oil pump 32 changes along with the change in the traveling characteristics.

The portion that was the A region in the normal mode includes a region where the vehicle speed is relatively slow. It is also considered that at low speeds, the amount of heat that can be released from the radiator 20 is reduced as compared with the case of high speeds, so that the temperature of LLC and cooling oil as a whole becomes high, and one or both of PCU14 and MG16 cannot be sufficiently cooled. .. In that case, the capacity of the radiator 20 may be increased to such an extent that cooling in the power mode is possible. Alternatively, of the parts that were in the A region in the normal mode, the parts that are close to the initial B region (for example, the vehicle speed is faster than an appropriate speed in the range of V2 to V3, and the motor temperature is T2 to T4). Only the portion that is higher than the appropriate temperature in the range of) may be changed to the B region in the power mode. In this way, stable running in the power mode can be realized by setting the boost of the power mode and strengthening the cooling within the range where cooling is possible.

In the above, in the normal mode, the oil pump 32 is controlled by dividing the A region shown in FIG. 2 into the C region, and in the power mode, a part or all of the A region is set as the B region. .. However, this area setting is only one aspect of the control method. For example, in the normal mode, the A region may be further divided and detailed control may be performed, or the control may be continuously changed without clarifying the boundary between the A region and the B region. Further, in the power mode, it is conceivable to set a part of the C area to be changed to the A area. In any case, in the power mode, the control mode is determined so that the cooling amount of the MG 16 is increased as compared with the normal mode after the cooling of the PCU 14 and the MG 16 is compatible.

Further, in the description here, it is assumed that the water pump 28 is always driven with a constant output. However, the water pump 28 constitutes a cooling system of the MG 16 via the oil cooler 26, and if the LLC is cooled by the water pump 28, the cooling of the MG 16 also proceeds. Therefore, even in the water pump 28, it is effective to perform control to increase the circulation amount in the power mode as compared with the normal mode. The control can be performed in the same manner as the change control of the oil pump 32 shown in FIGS. 2 to 6, for example. The cooling of the water pump 28 may be changed at the same timing as the cooling of the oil pump 32, or may be changed at different timings. Further, in the case of performing at the same timing, the change ratio of the circulation amount of the water pump 28 may be the same as or different from the change ratio of the circulation amount of the oil pump 32.

In the above description, a cooling mode of one system for cooling the PCU 14 and the MG 16 using one radiator 20 has been described. However, it is also possible to have two cooling mechanisms for independently cooling the PCU 14 and the MG 16 using separate radiators. In this case, it is possible to control so that each cooling is appropriately performed without considering the cooling balance between the PCU 14 and the MG 16.

FIG. 7 is a diagram showing a modified example of the cooling system. In FIG. 7, only the portion of the range shown in FIG. 1 that is directly related to the cooling of the PCU 14 and MG 16 is shown. Further, the same configurations as those in FIG. 1 are designated by the same reference numerals.

In the modified example shown in FIG. 7, a radiator 50 for cooling the PCU 14 is newly provided. From the radiator 50, the flow path 52a extends to the PCU 14, and from the PCU 14, the flow path 52b extends to the radiator 50. Then, LLC is circulated by the water pump 54, which is an electric pump provided in the middle of the flow path 52a. The cooling of the PCU 14 is enhanced by increasing the output of the water pump 54.

The radiator 20 is not involved in the cooling of the PCU 14, but is involved only in the cooling of the MG 16. From the radiator 20, the flow path 56a extends to the oil cooler 26, and from the oil cooler 26, the flow path 56b extends to the radiator 20. Then, LLC is circulated by a water pump 58 which is an electric pump provided in the flow path 56a. In the oil cooler 26, the cooling oil is cooled by LLC, and the cooling oil cools the MG 16 by the oil pump 32, which is the same as the embodiment shown in FIG. That is, the cooling of the MG 16 is composed of a two-stage cooling system.

In the power mode, the temperature of the MG 16 becomes particularly high, so that it is required to strengthen the cooling of the MG 16. The cooling of the MG 16 can be enhanced by increasing the circulation amount of the oil pump 32. Further, increasing the circulation amount of the water pump 58 also contributes to the cooling of the MG 16. Then, by increasing the circulation amount of both the water pump 58 and the oil pump 32, the cooling of the MG 16 proceeds most. In the power mode, the circulation amount by the water pump 54 for cooling the PCU 14 may be increased.

In the above description, the normal mode and the power mode are taken as examples as the driving characteristic modes. Various other driving characteristic modes can be considered. Specifically, "eco mode" that suppresses power consumption by relatively lowering the voltage applied to MG16, "climbing mode" that increases the voltage applied to MG16 at low speeds to facilitate climbing slopes, etc. Can be given as an example of. In any case, since the need for cooling the MG 16 is related by changing the traveling characteristic mode, it is effective to change the cooling amount of the MG 16 according to the difference in the traveling characteristic mode. However, when three or more driving characteristic modes are provided, it is not always necessary to switch the cooling control for each traveling characteristic mode. For example, when a plurality of running characteristic modes are similar, the mode of cooling control may be made common for these running characteristic modes.

10 electric vehicle, 12 body, 13 front wheel, 14 PCU, 16 MG, 18 condenser, 20, 50 radiator, 22a, 22b, 22c, 30a, 30b, 52a52b, 56a, 56b flow path, 26 oil cooler, 28, 54, 58 water pump, 32 oil pump, 34 ECU, 34a mode reception unit, 34b motor control unit, 34c cooling change unit, 34d motor control table, 34e cooling control table, 36, 38, 40, 42 temperature sensor, 44 speedometer, 46 mode button, 46a NORMAL button, 46b POWER button, 48 driver.

Claims (1)

A motor for driving a vehicle and
An electric pump that circulates the coolant flowing in the cooling system of the motor to cool it.
A reception means that accepts the user to select a mode for driving characteristics,
A control means for controlling the output of the motor according to the mode, and
The circulation amount of the coolant by the electric pump is changed according to the mode, the circulation amount of the coolant by the electric pump is increased according to the increase in vehicle speed, and the temperature of the motor or the temperature of the coolant is increased. A changing means for increasing the circulation amount of the coolant by the electric pump in response to an increase in
An electric vehicle characterized by being equipped with.

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