Motor cooling device of hybrid vehicle

Abstract

To provide a motor cooling device of a hybrid vehicle that can adequately control flow volumes of oil for cooling a motor for driving.SOLUTION: When a hybrid vehicle is running at speed determined to be low Vth or lower (S3:YES), a motor cooling device of the hybrid vehicle makes a first oil pump and a second oil pump supply oil to an MG2 (S5), and when the hybrid vehicle is running at over the speed determined to be low Vth (S3: NO), makes only the second oil pimp supply oil to the MG2 (S6).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a motor cooling device for a hybrid vehicle. [Background technology]

[0002] Conventionally, Patent Document 1 proposes a technology that includes a first oil pump connected to the wheels and driven when the vehicle is running, a second oil pump connected to the engine and driven when the engine is operating, a first lubrication / cooling oil passage that guides oil discharged by the first oil pump to an electric motor, and a second lubrication / cooling oil passage that guides oil discharged by the second oil pump to an electric motor and a generator, and that starts the engine and cools the electric motor with oil discharged from the second oil pump when lubrication and cooling by the first oil pump is impossible. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-106599 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, while the conventional technology described above can cool the electric motor (hereinafter also referred to as the "drive motor") with the oil discharged from the second oil pump, it has the problem that the flow rate of the oil cooling the drive motor cannot be properly controlled.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a motor cooling device for a hybrid vehicle that can appropriately control the flow rate of oil that cools the drive motor. [Means for solving the problem]

[0006] The motor cooling device for a hybrid vehicle of the present invention is a motor cooling device for a hybrid vehicle including an engine, a generator motor linked to the engine and generating electricity using the driving force of the engine, a drive motor linked to drive wheels and capable of generating driving force for driving the drive wheels, a first oil pump linked to a rotating shaft of the generator motor and supplying oil to the generator motor and the drive motor, and a second oil pump linked to a rotating shaft of the drive motor and supplying oil to the drive motor, and is configured to include a control unit that controls the second oil pump to supply oil to the drive motor and the generator motor to drive the generator motor to supply oil to the drive motor when the hybrid vehicle is running at or below a predetermined low speed judgment speed, and stops the generator motor and supplies oil to the drive motor only by the second oil pump when the hybrid vehicle is running above the low speed judgment speed. Effect of the Invention

[0007] The present invention can provide a motor cooling device for a hybrid vehicle that can appropriately control the flow rate of oil that cools the drive motor. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a vehicle equipped with a motor cooling device for a hybrid vehicle according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of an oil circulation circuit of a vehicle equipped with a motor cooling device for a hybrid vehicle according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a flowchart showing the motor cooling operation of the motor cooling device for a hybrid vehicle according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A motor cooling device for a hybrid vehicle according to one embodiment of the present invention includes an engine, a generator motor that is connected to the engine and generates electricity using the driving force of the engine, a drive motor that is connected to drive wheels and can generate driving force for driving the drive wheels, a first oil pump that is connected to a rotating shaft of the generator motor and supplies oil to the generator motor and the drive motor, and a second oil pump that is connected to a rotating shaft of the drive motor and supplies oil to the drive motor, and is characterized in that the motor cooling device further includes a control unit that controls the second oil pump to supply oil to the drive motor and the generator motor to drive the generator motor to supply oil to the drive motor when the hybrid vehicle is running at or below a predetermined low speed determination speed, and stops the generator motor and supplies oil to the drive motor only by the second oil pump when the hybrid vehicle is running above the low speed determination speed. As a result, the motor cooling device for a hybrid vehicle according to one embodiment of the present invention can appropriately control the flow rate of oil that cools the drive motor. EXAMPLES

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle equipped with a motor cooling device for a hybrid vehicle according to an embodiment of the present invention will now be described with reference to the drawings.

[0011] As shown in FIG. 1, the vehicle 1 includes an engine 2, a battery 3, a generator motor 4 (hereinafter also referred to as "MG1"), a first inverter 5, a drive motor 6 (hereinafter also referred to as "MG2"), a second inverter 7, a boost converter 8, drive wheels 9, a first oil pump 10, a second oil pump 11, and a hybrid controller (hereinafter simply referred to as "HCU") 12.

[0012] A plurality of cylinders are formed in the engine 2. In this embodiment, the engine 2 generates power to rotate the MG1 by performing a series of four strokes, which are an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, for each cylinder.

[0013] The battery 3 is configured by a rechargeable secondary battery, for example a lithium ion battery, and stores the power generated by the MG1 and MG2, and supplies the power to drive the MG1 and MG2.

[0014] The MG1 is provided to be interlocked with the crankshaft of the engine 2. The MG1 is connected to the battery 3 via a first inverter 5 and a boost converter 8. The MG1 has a function of an electric motor that starts the engine 2 by rotating when power is supplied from the battery 3, and a function of a generator that converts the power generated by the engine 2 into electric power.

[0015] The MG2 is provided so as to move in conjunction with drive wheels 9 via a power transmission member such as a gear mechanism. The MG2 is connected to the battery 3 via a second inverter 7 and a boost converter 8.

[0016] The MG2 has a function of an electric motor that rotates the drive wheels 9 by being rotated when supplied with electric power from the battery 3 and the MG1, and a function of a generator that converts the rotational force of the drive wheels 9 into electric power.

[0017] The boost converter 8 is provided between the battery 3 and the first inverter 5 and second inverter 7, and boosts the voltage of the power supplied from the battery 3 to the first inverter 5 and second inverter 7, and lowers the voltage of the power supplied from the first inverter 5 and second inverter 7 to the battery 3.

[0018] The first oil pump 10 is linked to the rotating shaft of MG1 and supplies cooling oil to MG1 and MG2. The second oil pump 11 is linked to the rotating shaft of MG2 and supplies cooling oil to MG2.

[0019] As shown in FIG. 2, the vehicle 1 has an oil pan 21, a strainer 22, an MG1 tank 23, and an MG2 tank 24.

[0020] Oil for cooling MG1 and MG2 is stored in the oil pan 21. The first oil pump 10 and the second oil pump 11 pump up the oil stored in the oil pan 21 through a strainer 22.

[0021] The oil pumped up by the first oil pump 10 is supplied to the MG1 tank 23 and the MG2 tank 24. The oil pumped up by the second oil pump 11 is supplied to the MG2 tank 24.

[0022] The MG1 tank 23 drips the oil supplied by the first oil pump 10 onto the MG1, particularly onto the coil portion of the MG1. The flow rate of the oil dripping from the MG1 tank 23 increases as the flow rate of the oil supplied by the first oil pump 10 increases.

[0023] The MG2 tank 24 drips the oil supplied by the first oil pump 10 and the second oil pump 11 onto the MG2, particularly onto the coil portion of the MG2. The flow rate of the oil dripping from the MG2 tank 24 increases as the flow rate of the oil supplied by the first oil pump 10 and the second oil pump 11 increases.

[0024] The oil dripping from the MG1 tank 23 and the oil dripping from the MG2 tank 24 are collected in the oil pan 21.

[0025] In FIG. 1, the HCU12 is composed of a computer unit having a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, etc., an input port, and an output port.

[0026] The ROM of this computer unit stores various constants, various maps, and the like, as well as a program for causing the computer unit to function as the HCU 12. That is, the CPU executes the program stored in the ROM using the RAM as a working area, causing the computer unit to function as the HCU 12 in this embodiment.

[0027] An input port of the HCU 12 is connected to various sensors including a temperature sensor 31 for detecting the temperature of the MG 2 and a vehicle speed sensor 32 for detecting the vehicle speed.

[0028] Various control objects are connected to an output port of the HCU 12, including the first inverter 5, the second inverter 7, the boost converter 8, an injector 41 that supplies fuel to the engine 2, and an ignition plug 42 that ignites in the combustion chamber of the engine 2. When the engine 2 is configured as an engine that does not require an ignition plug, such as a diesel engine, the ignition plug 42 is excluded from the configuration of the vehicle 1.

[0029] The HCU 12 controls various control objects connected to the output port based on information obtained from various sensors connected to the input port. In this embodiment, the HCU 12 functions as a control unit 50 that, when the vehicle 1 is traveling at a speed equal to or lower than the low-speed determination speed Vth, supplies oil to the MG2 by the second oil pump 11 and drives the MG1 to supply oil to the MG2 by the first oil pump 10, and, when the vehicle 1 is traveling at a speed higher than the low-speed determination speed Vth, stops the MG1 and supplies oil to the MG2 only by the second oil pump 11.

[0030] The low-speed determination speed Vth is set to a value that allows the MG2 to be sufficiently cooled by the oil supplied only by the second oil pump 11. The HCU 12 determines, based on the vehicle speed detected by the vehicle speed sensor 32, whether the vehicle 1 is traveling at or below the low-speed determination speed Vth and whether the vehicle 1 is traveling above the low-speed determination speed Vth.

[0031] When the vehicle 1 is traveling at a speed equal to or lower than the low-speed determination speed Vth, if the temperature detected by the temperature sensor 31 (hereinafter simply referred to as the "MG2 temperature") is equal to or higher than a threshold value TH, the HCU 12 drives the MG1 to supply oil to the MG2 by the first oil pump 10. The threshold value TH is set to a temperature at which the MG2 does not overheat.

[0032] That is, even if the vehicle 1 is traveling at or below the low speed determination speed Vth, if the MG2 temperature is below the threshold value TH, the HCU 12 does not drive the MG1 to cool the MG2.

[0033] When the vehicle 1 is traveling at a speed equal to or lower than the low-speed determination speed Vth and the MG2 temperature reaches or exceeds the threshold value TH, the HCU 12 starts the engine 2 and drives the MG1 linked to the engine 2.

[0034] When starting the engine 2, the HCU 12 controls the first inverter 5 to drive the MG 1 to rotate the crankshaft of the engine 2, and starts the supply of fuel by the injector 41 and ignition by the spark plug .

[0035] When the engine 2 drives the MG1 and the first oil pump 10 supplies oil to the MG2, the HCU 12 drives the engine 2 so that the operating point of the engine 2 is along the fuel efficiency optimum operating line, and controls the first inverter 5 to cause the MG1 to generate electricity.

[0036] The motor cooling operation of the HCU 12 configured as above will be described with reference to Fig. 3. The motor cooling operation described below is repeatedly performed while the HCU 12 is in operation.

[0037] First, in S1, the HCU 12 determines whether the vehicle 1 is traveling. If it is determined that the vehicle 1 is traveling, the HCU 12 executes the process of S2. If it is determined that the vehicle 1 is not traveling, the HCU 12 ends the motor cooling operation.

[0038] In S2, the HCU 12 judges whether the vehicle 1 is moving forward. If it is judged that the vehicle 1 is moving forward, the HCU 12 executes the process of S3. If it is judged that the vehicle 1 is not moving forward, that is, that the vehicle 1 is moving backward, the HCU 12 executes the process of S4.

[0039] In S3, the HCU 12 judges whether the vehicle 1 is traveling at a speed equal to or lower than the low-speed judgment speed Vth, i.e., whether the vehicle 1 is traveling at a low speed. If it is judged that the vehicle 1 is traveling at a low speed, the HCU 12 executes the process of S4. If it is judged that the vehicle 1 is not traveling at a low speed, the HCU 12 executes the process of S6.

[0040] In S4, the HCU 12 judges whether the MG2 temperature is equal to or higher than the threshold TH. If it is judged that the MG2 temperature is equal to or higher than the threshold TH, the HCU 12 executes the process of S5. If it is judged that the MG2 temperature is not equal to or higher than the threshold TH, the HCU 12 executes the process of S6.

[0041] In S5, if the MG1 is not being driven, the HCU 12 drives the MG1 by starting the engine 2. After executing the process of S5, the HCU 12 ends the motor cooling operation.

[0042] In S6, if the MG1 is being driven, the HCU 12 stops the MG1 by stopping the engine 2. After executing the process of S6, the HCU 12 ends the motor cooling operation.

[0043] As described above, the motor cooling device for a hybrid vehicle in this embodiment, when the vehicle 1 is traveling at or below the low-speed judgment speed Vth, supplies oil to MG2 via the second oil pump 11 and drives MG1 to supply oil to MG2 via the first oil pump 10, and when the vehicle 1 is traveling at a speed above the low-speed judgment speed Vth, controls so that MG1 is stopped and oil is supplied to MG2 only by the second oil pump 11, thereby making it possible to appropriately control the flow rate of oil cooling MG2.

[0044] For example, the motor cooling device of the hybrid vehicle in this embodiment controls the supply of oil to MG2 only by the second oil pump 11 when the vehicle 1 is traveling at high speeds, exceeding the low-speed judgment speed Vth, thereby preventing the oil flow rate from becoming excessive, thereby preventing a deterioration in fuel efficiency.

[0045] In addition, the motor cooling device of the hybrid vehicle in this embodiment controls the first oil pump 10 and the second oil pump 11 to supply oil to MG2 when the vehicle 1 is traveling at a low speed below the low-speed judgment speed Vth, thereby preventing a shortage of the flow rate of oil cooling MG2, and thereby enabling MG2 to be sufficiently cooled.

[0046] In this way, the motor cooling device of the hybrid vehicle of this embodiment can sufficiently cool MG2 while preventing a deterioration in fuel efficiency by controlling the flow rate of oil supplied by the first oil pump 10 in accordance with the traveling speed of the vehicle 1.

[0047] In addition, the motor cooling device of the hybrid vehicle of this embodiment does not drive MG1 to cool MG2 when the MG2 temperature is below the threshold value TH, even if the vehicle 1 is traveling at or below the low-speed judgment speed Vth, thereby preventing a deterioration in fuel efficiency.

[0048] In addition, when the motor cooling device for a hybrid vehicle in this embodiment drives MG1 using the engine 2 and supplies oil to MG2 using the first oil pump 10, it drives the engine 2 so that the operating point of the engine 2 is along the fuel efficiency optimum operating line and controls the first inverter 5 to cause MG1 to generate electricity, thereby preventing a deterioration in fuel efficiency.

[0049] In the embodiment described above, an example has been described in which, when the vehicle 1 is traveling at or below the low speed judgment speed Vth and the MG2 temperature becomes equal to or higher than the threshold value TH, the HCU 12 starts the engine 2 and drives the MG1 that is linked to the engine 2.

[0050] On the other hand, when the MG2 temperature becomes equal to or higher than the threshold value TH while the vehicle 1 is traveling at or below the low speed determination speed Vth, the HCU 12 may control the first inverter 5 to drive the MG1.

[0051] In addition, when the vehicle 1 is traveling at or below the low-speed judgment speed Vth and the MG2 temperature becomes equal to or higher than the threshold value TH, the HCU 12 may selectively execute a first process of starting the engine 2 and driving the MG1 linked to the engine 2, and a second process of controlling the first inverter 5 to drive the MG1.

[0052] For example, when the MG2 temperature becomes equal to or higher than the threshold TH while the vehicle 1 is traveling at a speed equal to or lower than the low speed determination speed Vth, the HCU 12 may execute the first process if the remaining capacity of the battery 3 is less than the low charge determination threshold, and execute the second process if the remaining capacity of the battery 3 is equal to or higher than the low charge determination threshold. The low charge determination threshold is set to a value at which the battery 3 is determined to be in a low charge state.

[0053] In addition, in the embodiment described above, an example has been described in which, when MG1 is driven by the engine 2 to supply oil to MG2 via the first oil pump 10, the HCU 12 controls the first inverter 5 to cause MG1 to generate electricity.

[0054] On the other hand, in a state in which the MG1 is driven by the engine 2 so that the first oil pump 10 supplies oil to the MG2, the HCU 12 may control the first inverter 5 so as not to cause the MG1 to generate electricity.

[0055] For example, in a state where MG1 is driven by the engine 2 to supply oil to MG2 by the first oil pump 10, if the remaining capacity of the battery 3 is less than the high charge determination threshold, the HCU 12 may control the first inverter 5 to cause the MG1 to generate power, and if the remaining capacity of the battery 3 is equal to or greater than the high charge determination threshold, the HCU 12 may control the first inverter 5 to prevent the MG1 from generating power. The high charge determination threshold is set to a value at which the battery 3 is determined to be in a highly charged state.

[0056] Furthermore, in a state in which MG1 is driven to supply oil to MG2 by the first oil pump 10, the HCU 12 may control the rotation speed of MG1 to be faster as the vehicle speed detected by the vehicle speed sensor 32 becomes lower. By configuring in this manner, the motor cooling device for the hybrid vehicle according to this embodiment can more appropriately control the flow rate of oil that cools MG2.

[0057] In addition, the above-mentioned low speed determination speed Vth, threshold value TH, low charging determination threshold value and high charging determination threshold value may each be determined with hysteresis so as to suppress frequent switching of the driving states of the engine 2 and MG1 in a short period of time.

[0058] While the present invention has been disclosed by way of example, it will be apparent that modifications may be made to the present invention without departing from the spirit and scope of the present invention, and the present invention is disclosed with the understanding that equivalents of such modifications are intended to be included within the scope of the appended claims. [Explanation of symbols]

[0059] 1 vehicle (hybrid vehicle) 2. Engine (internal combustion engine) 4. Generator motor 6 Driving motor 9 Drive wheels 10 No. 1 oil pump 11 No. 2 oil pump 50 Control section

Claims

1. The engine, a power generating motor that is linked to the engine and generates power using the driving force of the engine; A drive motor that is linked to a drive wheel and is capable of generating a drive force for running on the drive wheel; a first oil pump that is linked to a rotating shaft of the power generation motor and supplies oil to the power generation motor and the drive motor; a second oil pump that is linked to a rotary shaft of the drive motor and supplies oil to the drive motor, When the hybrid vehicle is traveling at or below a predetermined low speed determination speed, the second oil pump supplies oil to the drive motor, and the generator motor is driven to supply oil to the drive motor by the first oil pump; A motor cooling device for a hybrid vehicle, characterized in that it includes a control unit that controls the generator motor to stop and supply oil to the drive motor only by the second oil pump when the hybrid vehicle is traveling above the low speed judgment speed.

2. The control unit is The motor cooling device for a hybrid vehicle as described in claim 1, characterized in that when the hybrid vehicle is traveling at or below the low-speed judgment speed, if the temperature of the drive motor is above a threshold value, the generator motor is driven and oil is supplied to the drive motor by the first oil pump.

3. The control unit is 2. The motor cooling device for a hybrid vehicle as described in claim 1, wherein, when the generator motor is driven to supply oil to the drive motor by the first oil pump, the engine is driven so that the operating point of the engine is along a fuel efficiency optimum operating line to cause the generator motor to generate electricity.

Images