Cooling device

Abstract

To provide a cooling device capable of improving an electric mileage in the travel of a vehicle which has transmissions arranged on wheels to be driven independently.SOLUTION: The cooling device includes a radiator for cooling water to be cooled, an electric water pump for circulating the cooling water, a heat exchanger for making a heat exchange between the cooling water and oil in the transmissions provided on the respective wheels to be driven independently, an electric oil pump for circulating the oil in the transmissions, and a processor for controlling the electric water pump and the electric oil pump to be driven so as to raise the temperature of the oil for the wheels having low loads up to the vicinity of an upper limit while keeping the temperature of the oil for the wheels having high loads to be lower than the upper limit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a cooling device.

Background Art

[0002] Patent Document 1 discloses a technique of circulating oil in a transmission assembly by an electric oil pump and exchanging heat with a refrigerant in a water jacket.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a demand to improve the electricity cost during vehicle driving.

[0005] The present disclosure has been made in view of the above, and an object thereof is to provide a cooling device capable of improving the electricity cost during driving of a vehicle in which a transmission is disposed on each independently driven wheel.

Means for Solving the Problems

[0006] The cooling device according to the present disclosure includes a radiator that cools cooling water, an electric water pump that circulates the cooling water, a heat exchanger that exchanges heat between the cooling water and oil in a transmission provided on each independently driven wheel, an electric oil pump that circulates the oil in the transmission, and a processor configured to control driving of the electric water pump and the electric oil pump so as to maintain the temperature of the oil of the wheel with a high load below an upper limit and raise the temperature of the oil of the wheel with a low load up to near the upper limit.

Effects of the Invention

[0007] According to the present disclosure, it is possible to realize a cooling device that can improve the electricity cost during the running of a vehicle in which a transmission is disposed on each independently driven wheel.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0009] The cooling device according to the embodiment of the present disclosure will be described with reference to the drawings. Note that the constituent elements in the following embodiments include those that can be replaced by those skilled in the art and are easy to replace, or those that are substantially the same.

[0010] (Embodiment) 〔Configuration of Cooling Device〕 FIG. 1 is a schematic configuration diagram of a vehicle including a cooling device according to an embodiment. The vehicle 1 is a vehicle capable of four-wheel independent drive, and as shown in FIG. 1, a transmission TM is disposed on each wheel T. The cooling device of the vehicle 1 includes a radiator 2, cooling water 3, an electric water pump 4, and an ECU (Electronic Control Unit) 5. The cooling device of the vehicle 1 includes a cooling mechanism including a radiator 2 that cools the cooling water 3 and an electric water pump 4 that circulates the cooling water 3. Under the control of the ECU 5, the cooling water 3 cools the oil in each transmission TM.

[0011] Figure 2 is a cross-sectional view of the transmission shown in Figure 1. In Figure 2, the vertical direction corresponds to the vertical direction of the vehicle 1, and the horizontal direction corresponds to the front-rear direction of the vehicle 1. As shown in Figure 2, the transmission TM includes a driven gear 6 that transmits power to the wheel T, a drive gear 7 that transmits power to the driven gear 6, a gear motor 8 that transmits power from the motor to the drive gear 7, and a gear case 9 that houses each gear.

[0012] Figure 3 is a cross-sectional view corresponding to the A-A line of the transmission shown in Figure 2. As shown in Figure 3, the driven gear 6 is connected to the shaft S, and the power from the driven gear 6 is transmitted from the shaft S to the wheel T. At the end of the shaft S, a bearing 10 that rotatably supports the shaft S and an oil seal 11 that prevents the oil 12 from leaking are disposed.

[0013] The cooling device of the vehicle 1 is stored inside the transmission TM, and includes an oil 12 that lubricates each gear and the bearing 10, an electric oil pump 13 that circulates the oil 12 inside the transmission TM, a heat exchanger 14 that exchanges heat between the cooling water 3 and the oil 12, a temperature sensor 15 that detects the temperature of the oil 12 on the inlet side of the electric oil pump 13, and a temperature sensor 16 that detects the temperature of the cooling water 3 on the outlet side of the heat exchanger 14.

[0014] The ECU 5 controls the vehicle 1. The ECU 5 is configured using a memory and a processor having hardware such as a CPU (Central Processing Unit). Further, the ECU 5 controls the electric water pump 4 and the electric oil pump 13 of each transmission TM. Specifically, the ECU 5 controls the electric water pump 4 and the electric oil pump 13 so as to maintain the temperature of the oil 12 of the wheel T with a high load below the upper limit and raise the temperature of the oil 12 of the wheel T with a low load up to near the upper limit.

[0015] According to the cooling device of the vehicle 1 described above, the ECU 5 can control the temperature of the oil 12 in the transmission TM of each wheel T according to the load of each wheel T by cooperatively controlling the electric water pump 4 and the electric oil pump 13. In particular, by raising the temperature of the oil 12 in the wheel T with a low load to near the upper limit, the viscosity of the oil 12 can be reduced to reduce the driving loss, and the power consumption due to the driving of the electric water pump 4 and the electric oil pump 13 can be suppressed, and the electricity cost during the running of the vehicle 1 can be improved.

[0016] Also, according to the cooling device of the vehicle 1, the ECU 5 can cooperatively control the electric water pump 4 and the electric oil pump 13 so that a situation where only one wheel T can be cooled and the other wheels T cannot be cooled does not occur.

[0017] Also, according to the cooling device of the vehicle 1, since it is a single cooling system including one radiator 2 in the path of the cooling water 3, the number of parts can be reduced compared to a vehicle having an independent cooling system. As a result, a highly reliable, cost-reduced, and lightweight vehicle can be realized.

[0018] Note that this cooling device of the vehicle 1 can be adopted for both vehicles driven by a driver and vehicles with autonomous driving.

[0019] 〔Control in the cooling device〕 (Control 1) The case where the driver drives the vehicle 1 will be described. First, the ECU 5 acquires the accelerator operation amount by the driver and calculates the required torque based on the driving scene. Here, the driving scene represents the overall situation regarding the driving of the vehicle 1. For example, it represents the target vehicle speed according to the accelerator operation amount and the inclination angles in the longitudinal and lateral directions of the road surface on which the vehicle 1 travels. For example, when the driving scene is an uphill slope, since the required torque of the rear wheels is larger than that of the front wheels, the ECU 5 cooperatively controls the electric water pump 4 and the electric oil pump 13 so as to maintain the temperature of the oil 12 in the left and right rear wheels, where the required torque is large and the load is high, below the upper limit. On the other hand, the ECU 5 cooperatively controls the electric water pump 4 and the electric oil pump 13 so as to raise the temperature of the oil 12 in the left and right front wheels, where the required torque is small and the load is low, up to near the upper limit.

[0020] Similarly, when the driving scene is an uphill slope and the road surface slopes downward on the right shoulder, since the required torque of the right rear wheel becomes large, the ECU 5 cooperatively controls the electric water pump 4 and the electric oil pump 13 so as to maintain the temperature of the oil 12 in the right rear wheel, where the required torque is large and the load is high, below the upper limit. On the other hand, the ECU 5 cooperatively controls the electric water pump 4 and the electric oil pump 13 so as to raise the temperature of the oil 12 in the left and right front wheels and the left rear wheel, where the required torque is small and the load is low, up to near the upper limit.

[0021] (Control 2) The case where the vehicle 1 is driven by autonomous driving will be described. First, the ECU 5 determines the driving route (trajectory). Further, the ECU 5 reads the vehicle speed and the inclination angle when traveling on the determined driving route. Then, the ECU 5 calculates the required torque based on the driving scene according to the vehicle speed and the inclination angle. The subsequent processing is the same as that of Control 1.

[0022] (Control 3) The case where the electric water pump 4 is controlled so as to minimize the amount of the cooling water 3 while ensuring that the temperature of the cooling water 3 does not exceed the upper limit will be described.

[0023] First, the ECU 5 calculates the temperature of the cooling water 3 on the outlet side of the radiator 2 optimized according to information on the external environment including the external temperature. Note that the ECU 5 stores in advance conversion formulas, tables, graphs, etc. for optimizing the temperature of the cooling water 3 on the outlet side of the radiator 2 according to the external air temperature. Specifically, the higher the external temperature, the higher the temperature of the cooling water 3 on the outlet side of the radiator 2.

[0024] Subsequently, the ECU 5 calculates the required torque based on the driving scene in the same manner as in Control 1. Note that the ECU 5 stores in advance conversion formulas, tables, graphs, etc. for calculating the required torque according to the target vehicle speed for each inclination angle. Specifically, the higher the target vehicle speed, the greater the required torque, and the greater the inclination angle, the greater the required torque.

[0025] Furthermore, the ECU 5 calculates the amount of the cooling water 3 from the required torque. Note that the ECU 5 stores in advance conversion formulas, tables, graphs, etc. for calculating the amount of the cooling water 3 according to the required torque for each temperature of the cooling water 3 on the outlet side of the radiator 2. Specifically, the greater the required torque, the greater the amount of the cooling water 3, and the higher the temperature of the cooling water 3 on the outlet side of the radiator 2, the greater the amount of the cooling water 3.

[0026] Thereafter, the ECU 5 calculates the temperature rise range of the cooling water 3 from the required torque of each wheel T. Note that the ECU 5 stores in advance conversion formulas, tables, graphs, etc. for calculating the temperature rise range of the cooling water 3 according to the required torque of each wheel T. Specifically, the greater the required torque of each wheel T, the greater the temperature rise range of the cooling water 3.

[0027] Here, the ECU 5 controls the electric water pump 4 so as to maintain the temperature of the oil 12 of the wheel T with a high load below the upper limit. Specifically, when the temperature of the cooling water 3 on the outlet side of the heat exchanger 14 of the wheel T with a high load exceeds the upper limit of the cooling water 3 based on the calculated temperature rise range of the cooling water 3, the ECU 5 increases the amount of the cooling water 3 by a predetermined amount.

[0028] Furthermore, when the temperature of the cooling water 3 at the outlet side of the heat exchanger 14 of the wheel T located immediately before the inlet of the radiator 2 exceeds the upper limit of the cooling water 3, the ECU 5 increases the amount of the cooling water 3 by a predetermined amount.

[0029] Note that the ECU 5 stores in advance a conversion formula, a table, a graph, etc. for calculating the amount of the cooling water 3 according to the rotational speed of the electric water pump 4 for each temperature of the cooling water 3. Specifically, the larger the rotational speed of the electric water pump 4, the larger the amount of the cooling water 3, but the higher the temperature of the cooling water 3, the more necessary it is to increase the rotational speed of the electric water pump 4.

[0030] (Control 4) A case will be described in which the electric oil pump 13 is controlled so as to raise the temperature of the oil 12 of the wheel T with a low load to near the upper limit.

[0031] When the temperature of the oil 12 at the inlet side of the electric oil pump 13 of each wheel T has not reached the upper limit, the ECU 5 reduces the rotational speed of the electric oil pump 13 by a predetermined amount. On the other hand, when the temperature of the oil 12 at the inlet side of the electric oil pump 13 of each wheel T has reached the upper limit, the ECU 5 maintains the rotational speed of the electric oil pump 13.

[0032] (Control 5) Control for preventing the temperature of the oil 12 from exceeding the upper limit will be described.

[0033] When the temperature of the oil 12 at the inlet side of the electric oil pump 13 of each wheel T has not reached a threshold value that is a predetermined number of degrees higher than the upper limit, the ECU 5 maintains the rotational speed of the electric oil pump 13. On the other hand, when the temperature of the oil 12 at the inlet side of the electric oil pump 13 of each wheel T has reached the threshold value, the ECU 5 increases the rotational speed of the electric oil pump 13 by a predetermined amount.

[0034] (Control 6) Control for lubricating the transmission TM of each wheel T will be described.

[0035] When the state where the electric oil pump 13 of each wheel T is not rotating continues for a predetermined time, the ECU 5 rotates the electric oil pump 13 at a predetermined rotational speed for a predetermined time.

[0036] (Modification 1) The electric water pump 4 may be capable of rotating forward and backward. In this case, the ECU 5 controls the flow direction of the cooling water 3 according to the load of each wheel T.

[0037] When the driving scene is an uphill road with a right shoulder - descending road surface, since the load on the right rear wheel is high, the ECU 5 controls the electric water pump 4 so that the cooling water 3 flows from the radiator 2 to the right front wheel, right rear wheel, left rear wheel, and left front wheel in this order. As a result, the oil 12 of the right rear wheel with a high load can be cooled by the low - temperature cooling water 3 close to the radiator 2.

[0038] (Modification 2) FIG. 4 is a cross - sectional view corresponding to the A - A line of the transmission according to Modification 2. As shown in FIG. 4, in the flow path of the cooling water 3, there are arranged a flow path switching valve 21 for switching between a flow path for introducing the cooling water 3 into the heat exchanger 14 and a bypass flow path for bypassing the outside of the heat exchanger 14, and a check valve 22 for preventing the reverse flow of the cooling water 3. Then, the ECU 5 controls the flow path switching valve 21 to make the cooling water 3 flow through the bypass flow path for the wheel T with a low load and make the cooling water 3 flow into the heat exchanger 14 for the wheel T with a high load. As a result, the temperature of the oil 12 of the wheel T with a low load can be more efficiently raised to near the upper limit, and the temperature of the oil 12 of the wheel T with a high load can be more efficiently cooled.

[0039] (Control 2 - 1) The case of controlling the electric oil pump 13 so as to raise the temperature of the oil 12 of the wheel T with a low load to near the upper limit as in Control 4 will be described.

[0040] When the temperature of the oil 12 at the inlet side of the electric oil pump 13 for each wheel T has not reached the upper limit, the ECU 5 causes the cooling water 3 to flow through the bypass passage. On the other hand, when the temperature of the oil 12 at the inlet side of the electric oil pump 13 for each wheel T has reached the upper limit, the ECU 5 causes the cooling water 3 to flow into the heat exchanger 14. In this control, the electric oil pump 13 may be operated at a constant speed at the number of revolutions necessary for lubricating the transmission TM.

[0041] (Control 2-2) The control for preventing the temperature of the oil 12 from exceeding the upper limit, as in Control 5, will be described.

[0042] When the temperature of the oil 12 at the inlet side of the electric oil pump 13 for each wheel T has not reached a threshold value that is a predetermined number of degrees higher than the upper limit, the ECU 5 causes the cooling water 3 to flow through the bypass passage. On the other hand, when the temperature of the oil 12 at the inlet side of the electric oil pump 13 for each wheel T has reached the threshold value, the ECU 5 causes the cooling water 3 to flow into the heat exchanger 14. In this control, the electric oil pump 13 may be operated at a constant speed at the number of revolutions necessary for lubricating the transmission TM.

[0043] Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various changes can be made without departing from the spirit or scope of the general inventive concept defined by the appended claims and their equivalents.

Description of Reference Numerals

[0044] 1 Vehicle 2 Radiator 3 Cooling Water 4 Electric Water Pump 5 ECU 6 Driven Gear 7 Drive Gear 8 Gear Motor 9 Gear Case 10 Bearing 11 Oil seal 12 Oil 13 Electric oil pump 14 Heat exchanger 15, 16 Temperature sensor 21 Flow path switching valve 22 Check valve T Wheel TM Transmission S Shaft

Claims

【Claim 1】 a radiator for cooling cooling water; an electric water pump for circulating the cooling water; a heat exchanger for exchanging heat between the cooling water and the oil of a transmission provided on each wheel independently driven; an electric oil pump for circulating the oil into the transmission; a processor configured to control the driving of the electric water pump and the electric oil pump so as to maintain the temperature of the oil of the wheel with a high load below the upper limit and increase the temperature of the oil of the wheel with a low load up to near the upper limit; a cooling device comprising the same.

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