JP2022145095A - cooling system - Google Patents

Abstract

[Problem] To provide a cooling system capable of reducing uneven cooling of an electric device that supplies power to a rotating electric machine. [Solution] The cooling system includes a first cooling circuit that cools the electric device that supplies power to the rotating electric machine with a first coolant, a second cooling circuit that cools the rotating electric machine and the electric device with a second coolant, a heat exchanger that exchanges heat between the first coolant and the second coolant, a flow rate adjustment mechanism provided in the first cooling circuit that adjusts the flow rate of the first coolant flowing into the heat exchanger, and a control device that controls the flow rate adjustment mechanism, wherein the control device controls the flow rate adjustment mechanism so that the flow rate of the first coolant flowing into the heat exchanger when the rotation speed of the rotating electric machine is equal to or higher than a predetermined rotation speed is greater than the flow rate of the first coolant flowing into the heat exchanger when the rotation speed of the rotating electric machine is less than the predetermined rotation speed. [Selected Figure] Figure 6

Description

The present invention relates to cooling systems.

Patent Document 1 discloses a water cooling system that cools a PCU, which is an electrical device that supplies power to and controls a motor that is a rotating electric machine, with cooling water, an oil cooling system that cools the motor and the PCU with oil, and a water cooling system. A cooling system is disclosed that includes a heat exchanger that exchanges heat between the cooling water of the system and the oil of the oil cooling system.

JP 2019-080432 A

Here, when the number of revolutions of the motor is high, the motor current value is small, so the heat generation of the PCU is small and the temperature of the cooling water in the water cooling system does not rise easily. temperature of the oil tends to rise. Therefore, unless the temperature of the oil is reduced to the maximum by exchanging heat between the cooling water and the oil in the heat exchanger, the temperature difference between the cooling water and the oil when cooling the PCU will become too large, and the PCU will have a large temperature difference. Uneven cooling may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide a cooling system capable of reducing uneven cooling of an electric device that supplies electric power to a rotating electric machine.

In order to solve the above-described problems and achieve an object, a cooling system according to the present invention includes a first cooling circuit for cooling an electrical device that supplies electric power to a rotating electrical machine with a first cooling liquid; and a second cooling circuit for cooling the electrical device with a second cooling liquid, a heat exchanger for exchanging heat between the first cooling liquid and the second cooling liquid, and the first A cooling system comprising: a flow rate adjusting mechanism provided in a cooling circuit for adjusting the flow rate of the first cooling liquid flowing into the heat exchanger; and a control device controlling the flow rate adjusting mechanism, The control device reduces the flow rate of the first coolant flowing into the heat exchanger when the number of rotations of the rotating electric machine is equal to or higher than a predetermined number of rotations when the number of rotations of the electric rotating machine is less than the predetermined number of rotations. The flow rate adjusting mechanism is controlled so that the flow rate of the first cooling liquid flowing into the heat exchanger is larger than that of the first cooling liquid in the heat exchanger.

Thereby, the temperature of the second cooling liquid is reduced to the maximum by heat exchange between the first cooling liquid and the second cooling liquid in the heat exchanger, and the first cooling liquid when cooling the electric device is obtained. It is possible to reduce the temperature difference between the liquid and the second cooling liquid, and to reduce uneven cooling of the electrical equipment.

Further, in the above, the flow rate adjustment mechanism may include the flow rate of the first cooling liquid flowing through a first path for supplying the first cooling liquid to the electrical device via the heat exchanger, and the Even if it is a flow rate adjustment valve that can adjust the flow rate of the first cooling liquid flowing through the second path for supplying the first cooling liquid to the electrical device without passing through a heat exchanger good.

As a result, the flow rate adjustment valve increases the flow rate of the first cooling liquid flowing through the first path for supplying the first cooling liquid to the electrical equipment via the heat exchanger, for example, to increase the flow rate of the heat exchanger. The heat exchange between the first cooling liquid and the second cooling liquid at allows the temperature of the second cooling liquid to be reduced as much as possible.

Further, in the above, the direction in which the first cooling liquid flows when cooling the electrical device is opposite to the direction in which the second cooling liquid flows when cooling the electrical device. may

As a result, it is possible to reduce uneven cooling of the electrical equipment due to the temperature deviation in the respective flow directions of the first cooling liquid and the second cooling liquid with respect to the electrical equipment.

The cooling system according to the present invention can reduce the temperature difference between the first cooling liquid and the second cooling liquid when cooling the electrical equipment that supplies electric power to the rotating electric machine, thereby reducing uneven cooling of the electrical equipment. There is an effect that it can be reduced.

FIG. 1 is a schematic diagram showing the configuration of a vehicle cooling system according to an embodiment. FIG. 2 is a diagram showing a cooling structure of a power card provided in the PCU. FIG. 3 is a diagram showing a state in which the switching pattern of the first switching valve and the second switching valve is pattern 2 in the first cooling circuit. FIG. 4 is a diagram showing a state in which the switching pattern of the first switching valve and the second switching valve is Pattern 3 in the first cooling circuit. FIG. 5 is a diagram showing a map of switching patterns of the first switching valve and the second switching valve with respect to the MG rotation speed and the MG torque. FIG. 6 is a flowchart showing an example of selection control of the switching pattern of the first switching valve and the second switching valve, which is performed by the ECU.

An embodiment of a vehicle cooling system according to the present invention will be described below. It should be noted that the present invention is not limited by this embodiment. The vehicle cooling system according to the embodiment can be applied to, for example, a hybrid vehicle including an internal combustion engine and a motor as power sources for driving drive wheels, and an electric vehicle such as an electric vehicle including a motor as the power source. .

FIG. 1 is a schematic diagram showing the configuration of a vehicle cooling system 100 according to an embodiment. As shown in FIG. 1 , a vehicle cooling system 100 according to the embodiment includes a first cooling circuit 1 in which a first coolant (LLC) that cools a PCU (Power Control Unit) 4 is circulated. and a second cooling circuit 2 in which lubricating oil, which is a second cooling liquid for cooling the rotary electric machine 22 and the PCU 4, circulates. The lubricating oil, which is the second cooling liquid, has higher insulating properties than the LLC, which is the first cooling liquid, and is also used for lubricating the rotating electric machine 22 and the like.

The first cooling circuit 1 includes a first electric pump 11, a reserve tank 12, an oil cooler 3 which is a heat exchanger, a PCU 4, a radiator 13, a first switching valve 14, and a second switching valve 15. arranged and connected by pipes. The oil cooler 3 is shared with the second cooling circuit 2, and heat exchange is possible between the LLC flowing through the first cooling circuit and the lubricating oil flowing through the second cooling circuit in the oil cooler 3. It's becoming In the first cooling circuit 1 , the LLC circulates within the first cooling circuit 1 by operating the first electric pump 11 .

The solid arrows in FIG. 1 indicate the paths through which the LLC flows in the first cooling circuit 1, and the broken lines in FIG. shows no flow path. In the first cooling circuit 1, a flow path R11 from the first electric pump 11 to the reserve tank 12, a flow path R12 from the reserve tank 12 to the first switching valve 14, and a flow path R12 from the first switching valve 14 to the oil cooler 3 , a flow path R14 from the first switching valve 14 to the second switching valve 15, a flow path R15 from the oil cooler 3 to the second switching valve 15, and a flow path R15 from the second switching valve 15 to the PCU 4. , a flow path R17 from the PCU 4 to the radiator 13, and a flow path R18 from the radiator 13 to the first electric pump 11 are formed. In FIG. 1, in the first cooling circuit 1, by operating the first electric pump 11, when the first electric pump 11 is used as a starting point, the first electric pump 11, the reserve tank 12, the first The LLC circulates through the switching valve 14, the oil cooler 3, the second switching valve 15, the PCU 4, and the radiator 13 in this order.

The first switching valve 14 is a three-way valve having a first port 14a, a second port 14b, and a third port 14c, which are inlets and outlets for fluid in three directions. The first switching valve 14 communicates between the first port 14a and the second port 14b, communicates between the first port 14a and the third port 14c, and communicates with the first port 14a. It is configured to selectively switch the state of communicating with both the second port 14b and the third port 14c. The first port 14a is connected to the reserve tank 12 by a pipe forming a flow path R12. The second port 14b is connected to the oil cooler 3 by a pipe forming a flow path R13. The third port 14c is connected to the first port 15a of the second switching valve 15 by a pipe forming the flow path R14.

Therefore, the first switching valve 14 is operated in a state in which the LLC that has flowed from the reserve tank 12 through the flow path R12 into the first switching valve 14 flows into the oil cooler 3 through the flow path R13. and a state in which part of the oil flows into the oil cooler 3 through the flow path R13 and the rest flows into the second switching valve 15 through the flow path R14. is selectively switched. The switching operation of the first switching valve 14 is performed using a driving mechanism such as an actuator controlled by the ECU 5, for example.

The second switching valve 15 is a three-way valve having a first port 15a, a second port 15b, and a third port 15c, which are inlets and outlets for fluid in three directions. The second switching valve 15 has a state in which the first port 15a and the third port 15c are communicated, a state in which the second port 15b and the third port 15c are communicated, and a state in which the first port 15a and the third port 15c are communicated. It is configured to selectively switch a state in which both the second port 15b and the third port 15c are communicated. The first port 15a is connected to the third port 14c of the first switching valve 14 by a pipe forming the flow path R14 as described above. The second port 15b is connected to the oil cooler 3 by a pipe forming a flow path R15. The third port 15c is connected to the PCU 4 by a pipe forming a flow path R16 so as to communicate with a first cooling path 41, which will be described later.

Therefore, the second switching valve 15 is configured such that the LLC that has flowed from the first switching valve 14 through the flow path R14 into the second switching valve 15 flows through the flow path R16 into the first cooling path 41 of the PCU 4. a state in which the LLC that has flowed from the oil cooler 3 to the second switching valve 15 through the flow path R15 flows into the first cooling path 41 of the PCU 4 through the flow path R16; and a state in which the first switching valve 14 through the flow path R14 into the second switching valve 15 and the LLC flowing into the second switching valve 15 through the flow path R15 from the oil cooler 3 merge, and the merged LLC flows into the second switching valve 15. and flow into the first cooling path 41 of the PCU 4 through the path R16. The switching operation of the second switching valve 15 is performed using a driving mechanism such as an actuator controlled by the ECU 5, for example.

In the cooling system 100 according to the embodiment, the first switching valve 14 and the second switching valve 15 are for supplying LLC from the reserve tank 12 to the first cooling path 41 of the PCU 4 via the oil cooler 3. Flow rate of LLC flowing through the first route (passages R13, R15, R16) and a second route for supplying LLC from the reserve tank 12 to the first cooling passage 41 of the PCU 4 without passing through the oil cooler 3 It functions as a flow rate adjusting valve capable of adjusting the flow rate of the LLC flowing through (the flow paths R14 and R16), and constitutes a flow rate adjusting mechanism. As a result, the first switching valve 14 and the second switching valve 15 increase the flow rate of LLC flowing through the first path (flow paths R13, R15, R16), for example, and the LLC in the oil cooler 3 It is possible to reduce the temperature of the lubricating oil as much as possible by exchanging heat between it and the lubricating oil.

A second electric pump 21, an oil cooler 3, a PCU 4, a rotating electrical machine 22, and an oil pan 23 are arranged in the second cooling circuit 2, and are connected to each other by pipes. The lubricating oil circulates in the second cooling circuit 2 by operating the second electric pump 21 . In addition, the arrow shown by the dashed-dotted line in FIG. In the second cooling circuit 2, a flow path R21 from the second electric pump 21 to the oil cooler 3, a flow path R22 from the oil cooler 3 to the PCU 4, a flow path R23 from the PCU 4 to the rotating electrical machine 22, and from the rotating electrical machine 22 A flow path R24 to the oil pan 23 and a flow path R25 from the oil pan 23 to the second electric pump 21 are formed. In FIG. 1, in the second cooling circuit 2, by operating the second electric pump 21, when the second electric pump 21 is used as a starting point, the second electric pump 21, the oil cooler 3, the PCU 4, the rotation The lubricating oil circulates through the electric machine 22 and the oil pan 23 in this order.

FIG. 2 is a diagram showing the cooling structure of the power card 40 provided in the PCU 4. As shown in FIG. In addition, in FIG. 2, the figure which looked at PCU4 from the upper surface side, the side surface side, and the lower surface side, respectively is shown.

The PCU 4 is an electric device that supplies electric power to the rotating electric machine 22, and is configured by placing a power card 40 and the like in a case that forms the outer shell of the PCU 4. The PCU 4 is driven by power from a battery mounted on the vehicle, It controls the operation of the rotating electric machine 22 . The rotary electric machine 22 uses the electric power of the battery to generate power for driving the driving wheels of the vehicle according to the control signal from the PCU 4 . In addition, PCU4 is arrange|positioned above the rotary electric machine 22, and has the electromechanical integrated structure in which PCU4 and the rotary electric machine 22 were integrally comprised. In the case where the PCU 4 and the rotating electric machine 22 are integrated with each other in this way, the heat of the rotating electric machine 22 can be transferred to the case of the PCU 4 and the temperature of the lower surface of the power card 40 can rise. The cooling system 100 according to the embodiment has a cooling structure that cools the upper surface side and the lower surface side of the power card 40 with cooling liquid (LLC and lubricating oil) within the case of the PCU 4 .

In the PCU 4, the power card 40 is constructed by arranging a plurality of semiconductor elements 400a, 400b, and 400c in a line in a plane at intervals. On the upper side of the power card 40, a first heat dissipation member is thermally connected to the upper surfaces of the plurality of semiconductor elements 400a, 400b, 400c and dissipates heat transferred from the plurality of semiconductor elements 400a, 400b, 400c. 401 is provided. In addition, on the lower side of the power card 40, there is a second heat sink which is thermally connected to the respective lower surfaces of the plurality of semiconductor elements 400a, 400b, 400c and which dissipates heat transferred from the plurality of semiconductor elements 400a, 400b, 400c. of the heat radiation member 402 is provided. Inside the case of the PCU 4, there is a first cooling path 41 through which LLC cools the first heat radiation member 401 on the upper surface side of the power card 40, and a second heat radiation member 402 on the lower surface side of the power card 40. A second cooling passage 42 through which lubricating oil flows is separated by a seal member 403 .

LLC flows into the first cooling path 41 from the third port 15c of the second switching valve 15 through the flow path R16. Since it is sent from the cooling path 41 to the radiator 13 through the flow path 17, it can be said that the first cooling path 41 constitutes a part of the first cooling circuit. Lubricating oil flows into the second cooling path 42 from the oil cooler 3 through the flow path R22, and the lubricating oil after cooling the second heat radiating member 402 flows from the second cooling path 42 to the flow path R23. It can be said that the second cooling path 42 constitutes a part of the second cooling circuit because the cooling air is sent to the rotating electric machine 22 through.

In the cooling system 100 according to the embodiment, the flow direction of the LLC flowing through the first cooling path 41 and the direction of the flow of the second cooling path with respect to the arrangement direction of the plurality of semiconductor devices 400a, 400b, and 400c in the power card 40 It is opposite to the direction of flow of lubricating oil through 42 . That is, in the first cooling path 41, LLC flows so that the semiconductor element 400a, the semiconductor element 400b, and the semiconductor element 400c are cooled in this order. On the other hand, in the second cooling path 42, the lubricating oil flows so as to cool the semiconductor element 400c, the semiconductor element 400b, and the semiconductor element 400a in this order. Therefore, the temperature of the LLC flowing through the first cooling path 41 increases from the semiconductor element 400a toward the semiconductor element 400c, and the temperature of the lubricating oil flowing through the second cooling path 42 increases from the semiconductor element 400c to the semiconductor element 400a. It gets taller as you go. Thereby, the cooling of the power card 40 (the plurality of semiconductor elements 400a, 400b, 400c) due to the temperature deviation in the respective flow directions of the LLC and the lubricating oil with respect to the power card 40 (the plurality of semiconductor elements 400a, 400b, 400c) Unevenness can be reduced.

Various sensor data are input to the ECU 5 . For example, data such as the MG rotation speed, which is the rotation speed of the rotating electrical machine 22, and the MG torque, which is the torque of the rotating electrical machine 22, are input. Note that the MG torque has a correlation with the MG current value, which is the value of the current that rotationally drives the rotary electric machine 22, and the larger the MG torque, the larger the MG current value. Therefore, in the present embodiment, data on the MG current value is input to the ECU 5 as data on the MG torque.

In the cooling system 100 according to the embodiment, the ECU 5 switches the first switching valve 14 and the second switching valve 15 based on the MG rotation speed and the MG torque (MG current value) of the rotary electric machine 22. perform an operation. In the cooling system 100 according to the embodiment, three patterns, pattern 1, pattern 2, and pattern 3, are set as switching patterns of the first switching valve 14 and the second switching valve 15 .

Pattern 1 is, as shown in FIG. and the second switching valve 15 is switched from the oil cooler 3 to the first cooling of the PCU 4 through the flow path R16. Switch to the state of flowing into the channel 41 .

Pattern 2 is, as shown in FIG. The LLC that has switched to the state of flowing into the switching valve 15 and has flowed into the second switching valve 15 from the first switching valve 14 through the flow path R14 flows through the flow path R16. The state is switched to flow into the first cooling path 41 of the PCU 4 .

Pattern 3 is, as shown in FIG. The remaining LLC from the reserve tank 12 flows into the oil cooler 3 and flows into the second switching valve 15 through the flow path R14, and the second switching valve 15 is switched to the first switching valve. 14 through the flow path R14 into the second switching valve 15 and the LLC flowing into the second switching valve 15 through the flow path R15 from the oil cooler 3 are merged, and the merged LLC The state is switched to flow into the first cooling path 41 of the PCU 4 through the flow path R16.

FIG. 5 is a diagram showing a map of switching patterns of the first switching valve 14 and the second switching valve 15 with respect to the MG rotation speed and the MG torque.

As shown in FIG. 5, the operating state of the rotary electric machine 22 in which the MG rotation speed is equal to or greater than the predetermined rotation speed N1 and the MG torque is less than the predetermined torque T1, in other words, the high MG rotation speed and the low MG torque In the operation state of the rotary electric machine 22 in , pattern 1 is selected as the switching pattern of the first switching valve 14 and the second switching valve 15 . When the rotary electric machine 22 operates at a high MG rotation speed and a low MG torque, the MG current value is small, so the heat generation of the power card 40 (semiconductor elements 400a, 400b, 400c) of the PCU 4 is small, and the temperature of the LLC hardly rises. Also, iron loss occurs in the rotary electric machine 22, and the temperature of the lubricating oil tends to rise. Therefore, it is necessary to reduce the temperature of the lubricating oil as much as possible by exchanging heat with the LLC in the oil cooler 3 . Therefore, in the operating state of the rotary electric machine 22 at high MG rotation speed and low MG torque, pattern 1 is selected so that all LLC from the reserve tank 12 can flow into the oil cooler 3 . As a result, it is possible to reduce the temperature difference between the LLC and the lubricating oil when the PCU 4 cools the first heat radiating member 401 and the second heat radiating member 402. 400c) can be reduced.

Further, as shown in FIG. 5, the operating state of the rotary electric machine 22 in which the MG rotation speed is less than the predetermined rotation speed N1 and the MG torque is less than the predetermined torque T1, in other words, the low MG rotation speed and the low In the operating state of the rotary electric machine 22 at MG torque, Pattern 2 is selected as the switching pattern of the first switching valve 14 and the second switching valve 15 . In the operating state of the rotary electric machine 22 at low MG rotation speed and low MG torque, the temperatures of both the LLC and the lubricating oil are less likely to rise. Therefore, pattern 2 is selected so that all LLC from the reserve tank 12 can flow directly into the first cooling passage 41 of the PCU 4 without heat exchange with the lubricating oil in the oil cooler 3 . As a result, it is possible to reduce the temperature difference between the LLC and the lubricating oil when the PCU 4 cools the first heat radiating member 401 and the second heat radiating member 402. 400c) can be reduced.

Further, as shown in FIG. 5, the operating state of the rotary electric machine 22 in which the MG rotation speed is less than the predetermined rotation speed N1 and the MG torque is equal to or greater than the predetermined torque T1, in other words, the low MG rotation speed and the high rotation speed In the operating state of the rotary electric machine 22 at MG torque, pattern 3 is selected as the switching pattern of the first switching valve 14 and the second switching valve 15 . When the rotary electric machine 22 operates at a low MG rotation speed and a high MG torque, the power card 40 (the plurality of semiconductor elements 400a, 400b, and 400c) of the PCU 4 generates a large amount of heat due to the large MG current value, and the temperature of the LLC rises. In addition, iron loss occurs in the rotary electric machine 22, and the temperature of the lubricating oil tends to rise. Therefore, part of the LLC from the reserve tank 12 and the oil cooler 3 exchange heat to lower the temperature of the lubricating oil, and the remaining LLC from the reserve tank 12 is directly transferred to the PCU 4 without going through the oil cooler 3. Pattern 3 is selected, which allows flow into one cooling passage 41 . As a result, it is possible to reduce the temperature difference between the LLC and the lubricating oil when the PCU 4 cools the first heat radiating member 401 and the second heat radiating member 402. 400c) can be reduced.

In the map of the switching patterns of the first switching valve 14 and the second switching valve 15 shown in FIG. 5, the MG torque may be replaced with the MG current value.

FIG. 6 is a flowchart showing an example of selection control of switching patterns of the first switching valve 14 and the second switching valve 15 performed by the ECU 5 . Note that in the switching control shown in FIG. 6, the MG current value is used instead of the MG torque.

First, in step S1, the ECU 5 determines whether or not the current MG current value is greater than or equal to a predetermined current value. When the ECU 5 determines that the current MG current value is equal to or greater than the predetermined current value (Yes in step S1), in step S2, the switching pattern of the first switching valve 14 and the second switching valve 15 is set to Select 3 to end the series of controls. On the other hand, when the ECU 5 determines that the current MG current value is not equal to or greater than the predetermined current value (No in step S1), in step S3, it determines whether the current MG rotation speed is equal to or greater than the predetermined rotation speed. to judge. When the ECU 5 determines that the current MG rotation speed is equal to or higher than the predetermined rotation speed, in step S4, the ECU 5 selects pattern 1 as the switching pattern of the first switching valve 14 and the second switching valve 15, and performs a series of operations. End control. On the other hand, when the ECU 5 determines that the current MG rotation speed is not equal to or greater than the predetermined rotation speed (No in step S3), the switching pattern of the first switching valve 14 and the second switching valve 15 is determined in step S5. , the pattern 2 is selected, and the series of controls ends.

In the cooling system 100 according to the embodiment, the first switching valve 14 and the second switching valve 15 are switched according to the operating state of the rotating electric machine 22, in other words, the MG rotation speed and the MG torque (MG current value). The pattern can be selected to reduce the temperature difference between the LLC and the lubricating oil when the PCU 4 cools the first heat radiating member 401 and the second heat radiating member 402. , 400b, 400c) can be reduced.

1 first cooling circuit 2 second cooling circuit 3 oil cooler 4 PCU
5 ECUs
11 First electric pump 12 Reserve tank 13 Radiator 14 First switching valve 14a First port 14b Second port 14c Third port 15 Second switching valve 15a First port 15b Second port 15c 3 port 21 second electric pump 22 rotary electric machine 23 oil pan 40 power card 400a semiconductor element 400b semiconductor element 400c semiconductor element 401 first heat radiation member 402 second heat radiation member 403 sealing member

Claims (3)

a first cooling circuit that cools an electrical device that supplies electric power to the rotating electric machine with a first cooling liquid;
a second cooling circuit that cools the rotating electrical machine and the electrical equipment with a second coolant;
a heat exchanger that exchanges heat between the first cooling liquid and the second cooling liquid;
a flow rate adjustment mechanism provided in the first cooling circuit for adjusting the flow rate of the first coolant flowing into the heat exchanger;
a control device that controls the flow rate adjustment mechanism;
A cooling system comprising
The control device controls the flow rate of the first coolant flowing into the heat exchanger when the number of rotations of the rotating electric machine is equal to or higher than a predetermined number of rotations of the rotating electric machine. A cooling system, wherein the flow rate adjusting mechanism is controlled so that the flow rate of the first cooling liquid flowing into the heat exchanger is larger in the case of (1). The flow rate adjustment mechanism controls the flow rate of the first cooling liquid flowing through a first path for supplying the first cooling liquid to the electrical equipment via the heat exchanger, and a flow rate control valve capable of adjusting a flow rate of the first cooling liquid flowing through a second path for supplying the first cooling liquid to the electric device without being connected to the electrical equipment. 2. The cooling system according to claim 1. The direction in which the first cooling liquid flows when cooling the electrical device and the direction in which the second cooling liquid flows when cooling the electrical device are opposite to each other. 3. The cooling system according to 1 or 2.

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