Battery warm-up system

Abstract

To provide a battery warm-up system capable of warming up a battery without adding a component only for warming up the battery.SOLUTION: A battery warm-up system 2 includes a transaxle 10 including two motor generators 1112, and a transmission mechanism 13, a cooling circuit performing heat exchange between the transaxle 10 and a battery 23, and a separation mechanism 15 capable of separating and connecting an output shaft 16 connected to a drive wheel of a vehicle from the transaxle 10, and warms up the battery 23 by operating at least one of the two motor generators 1112,.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a battery warm-up system that warms up a battery mounted in a vehicle. [Background technology]

[0002] Patent Document 1 below proposes a technology for accelerating the warm-up of a battery. The battery pack described in Patent Document 1 below has an electric motor for rotating an impeller inside a housing. The battery pack described in Patent Document 1 below controls the output of the electric motor to be equal to or higher than the continuous rated output but lower than the rated output for a short period of time when the temperature of the battery cell falls below a threshold temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-128821 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, an impeller and an electric motor are provided inside the housing to warm up the battery, which increases costs due to the additional components and control required for battery warm-up. In addition, additional space is required inside the housing to accommodate the impeller and electric motor.

[0005] An object of the present disclosure is to provide a battery warm-up system that is capable of warming up a battery without adding any components solely for warming up the battery. [Means for solving the problem]

[0006] The present disclosure relates to a battery warm-up system that includes a transaxle including two motor generators and a transmission mechanism provided on the output side of either of the two motor generators, a cooling circuit that performs heat exchange between the transaxle and the battery, and a disconnection mechanism that can disconnect and connect the output shaft that connects from the transaxle to the drive wheels of the vehicle, and that warms up the battery by operating at least one of the two motor generators. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a battery warm-up system that is capable of warming up a battery without adding any components solely for warming up the battery. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram for explaining the configuration of a battery warm-up system according to this embodiment. [Figure 2] FIG. 2 is a diagram for explaining the configuration of the transaxle shown in FIG. [Figure 3] FIG. 3 is a diagram for explaining the operation of the transaxle. [Figure 4] FIG. 4 is a diagram for explaining the operation of the transaxle. [Figure 5] FIG. 5 is a diagram for explaining the operation of the transaxle. [Figure 6] FIG. 6 is a diagram for explaining the operation of the transaxle. [Figure 7] FIG. 7 is a diagram for explaining the operation of the transaxle. [Figure 8] FIG. 8 is a diagram for explaining a modified example of the battery warm-up system. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0010] The battery warm-up system 2 shown in Fig. 1 is a system mounted on a vehicle. The vehicle is an electric vehicle without an internal combustion engine, such as a BEV (Battery Electric Vehicle) or FCEV (Fuel Cell Electric Vehicle). The battery warm-up system 2 includes a transaxle 10, a disconnection mechanism 15, an output shaft 16, an oil cooler 21, an inverter 22, a battery pack 23, and a control device 31. The transaxle 10 includes a first MG 11, a second MG 12, a transmission mechanism 13, and a power combining mechanism 14.

[0011] The battery pack 23 is a battery for supplying power to the first MG 11 and the second MG 12. The inverter 22 converts the direct current supplied from the battery pack 23 into alternating current and drives the first MG 11 and the second MG 12.

[0012] Cooling water flows so as to circulate through the oil cooler 21, inverter 22, and battery pack 23. The cooling water is heated by cooling the oil cooler 21 and inverter 22, and warms up the battery pack 23. The oil cooler 21 is a heat exchanger that exchanges heat between the cooling oil circulating through the transaxle 10 and the cooling water.

[0013] The first MG 11 and the second MG 12 are arranged in parallel. The first MG 11 and the second MG 12 are motor generators, and function as both electric motors and generators. A power combining mechanism 14 is provided to combine the output of the first MG 11 and the output of the second MG 12. A transmission mechanism 13 is arranged between the first MG 11 and the power combining mechanism 14. The transmission mechanism 13 has at least a high gear and a low gear. The high gear has a gear ratio of, for example, less than 5.8. The low gear has a gear ratio of, for example, 6.8 or more. Note that these gear ratios are merely examples, and other gear ratios may be used.

[0014] The output combined by the power combining mechanism 14 is transmitted to the output shaft 16 via a disconnecting mechanism 15. The disconnecting mechanism 15 is a mechanism that can disconnect and connect the output connected from the transaxle 10 to the output shaft 16.

[0015] Required heat information indicating the amount of heat required to warm up the battery pack 23 is input to the control device 31. Required driving force information indicating the driving force to be output from the output shaft 16 is input to the control device 31. The control device 31 controls the transaxle 10 and the disconnection mechanism 15 based on the required heat information and the required driving force information. The control manner by the control device 31 will be described later.

[0016] The first MG 11, the second MG 12, the speed change mechanism 13, the power combining mechanism 14, the separation mechanism 15, and the output shaft 16 will be described with reference to Figure 2. Figure 2(A) is a diagram for explaining the arrangement of each mechanism. Figure 2(B) is a diagram showing the connection state of each mechanism as seen in the axial direction.

[0017] The power combining mechanism 14 is configured as a counter gear. A speed change mechanism 17 is disposed between the power combining mechanism 14 and the separation mechanism 15. The speed change mechanism 13 and the speed change mechanism 17 are each configured as a planetary gear. A differential ring gear 18 is disposed between the separation mechanism 15 and the output shaft 16.

[0018] When the vehicle equipped with the battery warm-up system 2 is stopped, the control device 31 opens the disconnection mechanism 15. The control device 31 causes the second MG 12 to rotate the first MG 11 and generate heat.

[0019] Figure 3 shows an example of operating points when the second MG 12 is the driving side and the first MG 11 is the driven side. The example shown in Figure 3 is an example when the vehicle equipped with the battery warm-up system 2 is stopped. Figure 3(A) shows the relationship between the rotation speed and torque of the second MG 12, which is the driving side, and Figure 3(B) shows the relationship between the rotation speed and torque of the first MG 11, which is the driven side. In both cases of Figure 3(A) and Figure 3(B), as torque increases, copper loss increases and the amount of heat generated increases, and as rotation speed increases, iron loss increases and the amount of heat generated increases.

[0020] For example, if a large amount of heat generation is required, the control device 31 sets the transmission mechanism 13 to Lo gear. Next, the control device 31 increases the rotation speed while suppressing the torque of the second MG 12 ("1" in FIG. 3A). The first MG 11 becomes the driven side via Lo gear, so the rotation speed decreases and the torque increases ("1" in FIG. 3B).

[0021] For example, when efficient heat generation is required, the control device 31 sets the transmission mechanism 13 to high gear. Next, the control device 31 sets the rotation speed to a medium level while suppressing the torque of the second MG 12 ("2" in FIG. 3A). The first MG 11 becomes the driven side via the high gear, so the rotation speed is reduced and the torque is relatively suppressed ("2" in FIG. 3B).

[0022] When the vehicle equipped with the battery warm-up system 2 is running, the control device 31 closes the disconnection mechanism 15. The control device 31 rotates the first MG 11 or the second MG 12 for driving and transmits power to the differential ring gear 18 and the output shaft 16, while rotating the other MG that is not used for driving and generating heat.

[0023] Figure 4 shows an example of an operating point when the second MG 12 is the driving side and the first MG 11 is the driven side during driving, and shows an example of when heat generation is desired. Figure 4(A) shows the relationship between the rotation speed and torque of the second MG 12, which is the driving side, and Figure 4(B) shows the relationship between the rotation speed and torque of the first MG 11, which is the driven side. In both Figures 4(A) and 4(B), as torque increases, copper loss increases and the amount of heat generation increases, and as rotation speed increases, iron loss increases and the amount of heat generation increases.

[0024] The operating point of the second MG 12, which is the drive side, is determined so as to conform to the requirements of the traveling side. The control device 31 sets the gear ratio of the transmission mechanism 13 so that a load is applied to the first MG 11 with respect to the operating point of the second MG 12. For example, if the operating point of the second MG 12 is on the low torque side, the transmission mechanism 13 is set to Lo gear. On the other hand, if the operating point of the second MG 12 is on the high torque side, the transmission mechanism 13 is set to Hi gear.

[0025] Next, Figure 5 shows an example of operating points when the second MG 12 is the driving side and the first MG 11 is the driven side during driving, and shows an example of when some heat generation or no heat generation is required. Figure 5(A) shows the relationship between the rotation speed and torque of the second MG 12, which is the driving side, and Figure 5(B) shows the relationship between the rotation speed and torque of the first MG 11, which is the driven side. In both Figures 5(A) and 5(B), as torque increases, copper loss increases and the amount of heat generation increases, and as rotation speed increases, iron loss increases and the amount of heat generation increases.

[0026] The operating point of the second MG 12, which is the driving side, is determined so as to meet the requirements of the traveling side. The control device 31 sets the gear ratio of the transmission mechanism 13 so as to improve the efficiency of the first MG 11 with respect to the operating point of the second MG 12. For example, regardless of the operating point of the second MG 12, the transmission mechanism 13 is set to High gear.

[0027] Fig. 6 shows a detailed example of control when a vehicle equipped with the battery warm-up system 2 is stopped. Fig. 6(A) is a table showing combinations of operating points and conditions. Fig. 6(B) is a graph showing the operating points of Fig. 6(A) as a torque-rotation speed graph.

[0028] Operating point 1 is an operating point where the required heat quantity is "large" and the required driving force is "0." The second MG 12 on the driving side is driven at high rotation speed and low torque. The transmission mechanism 13 is set to low gear. The first MG 11 on the driven side is subjected to high load and low rotation speed. As a result, iron loss in both the first MG 11 and the second MG 12 is large, and the amount of heat generated is large.

[0029] Operating point 2 is an operating point where the required heat amount is "medium" and the required driving force is "0." The second MG 12 on the driving side is driven at high rotation speed and low torque. The transmission mechanism 13 is set to high gear. The first MG 11 on the driven side is at medium load and medium rotation speed. As a result, the second MG 12 has large iron loss and generates a large amount of heat, but the first MG 11 has medium iron loss and copper loss, and generates a medium amount of heat.

[0030] Operating point 3 is an operating point where the required heat quantity is "small" and the required driving force is "0." The second MG 12 on the driving side is driven at medium speed and medium torque. The transmission mechanism 13 is set to high gear. The first MG 11 on the driven side is at medium load and medium speed. As a result, the second MG 12 has medium iron loss and medium copper loss, and the first MG 11 has low iron loss and medium copper loss, resulting in a small amount of heat generation.

[0031] Fig. 7 shows a detailed control example when a vehicle equipped with the battery warm-up system 2 is running. Fig. 7(A) is a table showing combinations of operating conditions when the vehicle is running with the second MG 12 as the drive side. Fig. 7(B) is a table showing combinations of operating conditions when the vehicle is running with both the first MG 11 and the second MG 12 as the drive side.

[0032] The operating conditions at the top of Figure 7(A) are operating conditions when the required heat quantity is "large" and the required driving force is "large." The second MG 12 on the driving side is driven at low rotation speed and high torque. The transmission mechanism 13 is set to low gear. A low-load driving force is transmitted from the second MG 12 on the driving side to the transmission mechanism 13, and by passing through the transmission mechanism 13, the first MG 11 on the driven side is subjected to a high load and low rotation speed. As a result, the copper loss in the first MG 11 becomes large and the iron loss in the second MG 12 becomes large, resulting in a large amount of heat generation.

[0033] 8 shows the configuration of a modified battery warm-up system 2A. In the battery warm-up system 2A, a first MG 11 and a second MG 12 are arranged in series. A transmission mechanism 13 and a power combining mechanism 14 are arranged between the first MG 11 and the second MG 12.

[0034] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise.

[0035] [Appendix 1] a transaxle 10 including two motor generators and a transmission mechanism 13 provided on the output side of either of the two motor generators; a cooling circuit for exchanging heat between the transaxle 10 and the battery; a disconnection mechanism 15 that can disconnect and connect an output shaft 16 that is connected to the drive wheels of the vehicle from the transaxle 10; A battery warm-up system 2, 2A operates at least one of the two motor generators to warm up the battery.

[0036] In the present disclosure, the two motor generators are exemplified as a first MG 11 and a second MG 12. In the present disclosure, the battery is exemplified as a battery pack 23.

[0037] According to Supplementary Note 1, at least one of the two motor generators is operated to warm up the battery, so there is no need to add components just for warming up the battery, and the battery can be warmed up with a simple structure and control. [Explanation of symbols]

[0038] 2: Battery warm-up system 10: Transaxle 11: 1st MG 12: 2nd MG 13: Transmission mechanism 14: Power merging mechanism 15: Detachment mechanism 16: Output shaft 17: Transmission section 18: Differential ring gear 21: Oil cooler 22: Inverter 23: Battery pack 31: Control device

Claims

[Claim 1] a transaxle including two motor generators and a transmission mechanism provided on the output side of either of the two motor generators; a cooling circuit for exchanging heat between the transaxle and the battery; a disconnection mechanism that can disconnect and connect an output shaft that is connected to a drive wheel of a vehicle from the transaxle, a battery warm-up system that warms up the battery by operating at least one of the two motor generators;

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