KR101966467B1 - System of recycling exhaust heat from internal combustion engine - Google Patents

Abstract

The present invention relates to an exhaust heat recycling system for an internal combustion engine including a recycling system for circulating a working fluid by using exhaust heat of an internal combustion engine. The exhaust heat recycling system of an internal combustion engine according to the preferred embodiment of the present invention is characterized in that: A working fluid circulating line through which the working fluid circulates; An exhaust-side heat exchange unit installed in an exhaust line for exhausting exhaust gas to transfer heat from the exhaust gas to the working fluid; A turbine generating unit having a turbine that rotates by receiving energy from the working fluid circulating line, a motor generator that converts the rotational force of the turbine into electrical energy to charge the battery, or rotates by receiving power from the battery; And an auxiliary motor connected to the gear train of the internal combustion engine and driving the gear train by receiving power from the battery.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a system for recycling exhaust heat of an internal combustion engine,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust heat recycling system for an internal combustion engine, and more particularly, to an exhaust heat recycling system for an internal combustion engine including a recycling system for circulating a working fluid using exhaust heat of an internal combustion engine.

Internal combustion engines are widely used in vehicles, ships, small generators, etc., and attempts have been made to increase the efficiency of internal combustion engines. In internal combustion engines, a large amount of heat is generally discharged as exhaust heat, and various systems have been developed to recover the exhaust heat to increase the efficiency of the internal combustion engine as a whole.

Considering the equipment, parts, and load required to construct the exhaust heat recovery system, it is preferable to install exhaust heat recycling system in a large vehicle capable of transporting a large number of persons or cargoes with a large exhaust amount, It is more efficient to mount.

In the case of a vehicle, a system for recycling exhaust heat is typically a system using a turbo compound and a system using a thermoelectric element.

In the system using the turbo compound, the exhaust turbine is attached to the exhaust line, and the exhaust turbine is rotated at the exhaust pressure to obtain the output. This method can increase the thermal efficiency of the entire system in which the internal combustion engine is installed, It has a disadvantage that the output of the engine itself is lowered because it acts as an exhaust resistance.

In a system using a thermoelectric element, a method of charging the electricity using a thermoelectric element that generates electricity by temperature difference, or assisting the engine by driving the electric assist motor is used. However, the cost of the thermoelectric device itself can not be ignored, the space for mounting the thermoelectric device is narrow, and it is not easy to increase the thermal efficiency of the engine significantly even if the thermoelectric device is mounted in the actual mass production vehicle.

In order to solve such a problem, the inventor of the present invention has developed an exhaust heat recycling system for circulating a working fluid by using heat received from an exhaust side of an internal combustion engine and rotating the turbine with the working fluid. However, it is clear that this exhaust heat recycling system is not an invention disclosed to a person who is not obliged to maintain confidentiality based on the time of filing of the present invention.

In order to increase the efficiency of the exhaust heat recycling system, it is necessary to reduce the load of the engine by making maximum use of the rotational force of the turbine rotating by the working fluid.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an exhaust heat recycling system for an internal combustion engine capable of increasing fuel economy by reducing the load of the engine.

In order to achieve the above object, an exhaust heat recycling system for an internal combustion engine according to a preferred embodiment of the present invention includes: a working fluid circulating line in which a working fluid satisfying a Rankine cycle circulates; An exhaust-side heat exchange unit installed in an exhaust line for exhausting exhaust gas to transfer heat from the exhaust gas to the working fluid; A turbine generating unit having a turbine that rotates by receiving energy from the working fluid circulating line, a motor generator that converts the rotational force of the turbine into electrical energy to charge the battery, or rotates by receiving power from the battery; And an auxiliary motor connected to the gear train of the internal combustion engine and driving the gear train by receiving power from the battery.

The auxiliary motor may drive the gear train until the voltage of the battery falls from a start-up initial state of the battery to a predetermined charging start reference voltage.

The exhaust heat recycling system of the internal combustion engine further includes an EGR line for circulating a part of the exhaust gas generated in the internal combustion engine to the intake side, (T1), the rotational energy of the turbine can be converted into electric energy.

The exhaust heat recycling system of the internal combustion engine may further include an EGR side heat exchange unit for exchanging heat between the EGR gas flowing through the EGR line and the working fluid flowing through the working fluid circulating line.

When the temperature of the EGR gas is higher than the reference temperature T1, the EGR gas is circulated to the intake side via the EGR heat exchanger unit. When the temperature of the EGR gas is lower than the reference temperature T1, Can be circulated to the intake side without passing through the EGR side heat exchange unit.

The T1 may be 500 ° C.

The turbine generating unit further includes a pulley and a clutch, and the turbine and the rotor of the motor generator are coaxially connected, and the clutch can interlock the turbine and the pulley.

Further, the turbine generating unit may further include a second clutch capable of mechanically interrupting the turbine and the motor generator, and when the battery can be overcharged by the motor generator, And the motor generator can be mechanically disconnected.

Further, when the voltage of the battery drops to a predetermined charging start reference voltage, the second clutch can mechanically connect the turbine and the motor generator.

Further, the exhaust-side heat exchange unit may be disposed on the upstream side of the working fluid circulation line with respect to the EGR-side heat exchange unit.

Further, the working fluid can always pass through the exhaust-side heat exchange unit.

According to the present invention, it is possible to provide an exhaust heat recycling system of an internal combustion engine capable of increasing the fuel consumption by reducing the load of the engine.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given above, serve to further the understanding of the technical idea of the invention, And should not be construed as interpretation.
1 is a conceptual diagram of an exhaust heat recycling system of an internal combustion engine according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited or limited by the following examples.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

In the drawings, the size of each element or a specific part constituting the element is exaggerated, omitted or schematically shown for convenience and clarity of description. Therefore, the size of each component does not entirely reflect the actual size. In the following description, it is to be understood that the detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

1 is a conceptual diagram of an exhaust heat recycling system of an internal combustion engine according to the present invention.

1, an exhaust heat recycling system (hereinafter referred to as a "recycling system") of an internal combustion engine according to the present invention includes a working fluid circulating line 100 in which a working fluid satisfying a Rankine cycle circulates, An exhaust side heat exchange unit 400 installed in an exhaust line for discharging heat from the exhaust gas to the working fluid, a turbine 510, a motor generator 530, a clutch 520 and a pulley 540, And an auxiliary motor 40 connected to the gear train 7 of the internal combustion engine and supplied with power from the battery 20 to drive the gear train 7. A Rankine cycle is a cycle consisting of two adiabatic changes and two equilibrium changes, in which the working fluid involves a phase change of vapor and liquid. Since the Rankine cycle is one of the well-known cycles, a further detailed description thereof will be omitted.

The recycling system may further include an EGR line 200 for circulating a part of the exhaust gas generated in the internal combustion engine to the intake side. The EGR gas may be supplied to the EGR line 200 through the EGR gas flowing through the working fluid circulation line 100 And an EGR side heat exchange unit (300) for mutually exchanging heat of the working fluid.

The working fluid always passes through the exhaust-side heat exchange unit 400, but only when the temperature of the EGR gas flowing through the EGR line 200 is equal to or higher than the reference temperature T1, the working fluid passes through the EGR-side heat exchange unit 300.

The temperature of the EGR gas is considered to reflect the temperature of the engine 1 because the temperature of the EGR gas is low when the temperature of the engine 1 is low and the temperature of the EGR gas is high when the temperature of the engine 1 is high. Therefore, it is possible to measure the temperature of the EGR gas without having to measure the temperature of the cylinder block or the head cover of the engine 1 in order to judge whether the engine 1 has been sufficiently preheated, Can be determined.

When the engine 1 is sufficiently preheated to circulate the working fluid and thereby the turbine rotates, the point of time when the fuel economy of the vehicle equipped with the engine 1 is improved is that the temperature of the EGR gas reaches 500 캜 One point. Hereinafter, the circulation path through the EGR line 200 of the EGR gas will be described as an example when the reference temperature T1 is set to 500 ° C.

If the temperature of the EGR gas is 500 ° C or more, the EGR gas is circulated to the intake side via the EGR heat exchanger unit 300. If the temperature of the EGR gas is less than 500 ° C, the EGR gas does not pass through the EGR heat exchanger unit 300 And is circulated to the intake side.

This will be described in more detail.

The EGR line 200 is provided with an EGR side bypass valve 220 for converting the path of the EGR gas and is connected to the EGR bypass valve 220 through the EGR valve 210 from the exhaust manifold 3, The EGR bypass valve 220 is opened and the EGR gas moves to the right side of the EGR bypass valve 220 on the basis of FIG. 1, passes through the EGR-side heat exchange unit 300, (2). On the other hand, when the EGR gas is less than 500 ° C, the EGR bypass valve 220 is closed so that the EGR gas moves upward of the EGR bypass valve 220 and does not pass through the EGR heat exchanger unit 300 And is supplied to the intake manifold 2 side.

As described above, when the temperature of the exhaust gas is low as in the case of starting the engine at the initial stage, the EGR gas is introduced into the intake manifold 2 without passing through the EGR heat exchanger unit 300, And it is possible to prevent occurrence of a phenomenon in which the operating fluid is circulated unduly for reducing the fuel consumption of the engine 1 when the engine 1 is not preheated.

On the other hand, the EGR-side heat exchange unit 300 thermally connects the EGR line 200 and the working fluid circulation line 100, cools the EGR gas by heat exchange between the EGR gas and the working fluid, To the fluid. The EGR side heat exchange unit 300 also has an EGR cooler 320 for cooling the EGR gas and a superheater 310 for transferring heat from the EGR gas to the working fluid that has passed through the exhaust side heat exchange unit 400 .

Hereinafter, a path through which the working fluid circulates on the working fluid circulating line 100 will be described.

The working fluid is introduced into the working fluid pump 70 through the outlet 64 of the reservoir tank 60 which stores the working fluid in the liquid state and has the inlet 62 and the outlet 64, And supplies the working fluid to the working fluid circulating line (100). As described above, since the EGR gas passes through the EGR heat exchanger unit 300 only when the temperature of the EGR gas is equal to or higher than the reference temperature T1, the working fluid pump 70 is operated until the temperature of the EGR gas is equal to or higher than the reference temperature T1 It is desirable to operate only when.

The working fluid pumped by the working fluid pump (70) is heated while passing through the recuperator (50). The working fluid that has passed through the recuperator 50 is supplied to the exhaust-side heat exchange unit 400 to receive heat again and receives heat through the superheater 310 provided in the EGR-side heat exchange unit 300. Here, the exhaust-side heat exchange unit 400 may be formed in a structure that allows the working fluid to receive heat from the exhaust gas while being in contact with the surface of the exhaust pipe 404. In this case, unlike the system using the turbo compound There is an advantage that the output of the engine 1 itself does not deteriorate because there is no exhaust resistance.

The working fluid in the liquid state that has not yet been vaporized even before passing through the superheater 310 is separated by the gas-liquid separator 330. The working fluid in the gaseous state, which has passed through the superheater 310, Only.

Since the working fluid receives heat from the recuperator 50 and the exhaust-side heat exchange unit 400 is disposed on the upstream side of the working fluid circulation line 100 than the EGR-side heat exchange unit 300, Side heat exchanging unit 400 and the EGR-side heat exchanging unit 300, and further receives heat.

The gaseous working fluid is supplied to the turbine 510 through the turbine inlet pipe 304 to rotate the turbine 510 and the working fluid that has lost energy by rotating the turbine 510 is returned to the recuperator 50. [ And returns to the inlet 62 of the reservoir tank 60.

The turbine 510 is a component of the turbine generator unit 500 that receives and receives energy from the working fluid circulation line 100. The construction and operation of the turbine generator unit 500 will be described in detail later .

The recuperator 50 is arranged between the working fluid flowing into the reservoir tank 60 and the working fluid flowing out of the reservoir tank 60 in fluid communication with both the inlet 62 and the outlet 64 of the reservoir tank 60 Heat exchange is performed.

From the viewpoint of the working fluid flowing out of the outlet 64 of the reservoir tank 60 is heated by receiving heat from the working fluid flowing into the recuperator 50 after passing through the turbine 510 and conversely, Is cooled by the working fluid flowing out of the outlet 64 of the reservoir tank 60 from the viewpoint of the working fluid flowing into the recuperator 50 after passing through the reservoir tank 510. The recuperator 50 is disposed on the upstream side of the reservoir tank 60 with respect to the inlet 62 of the reservoir tank 60 and is disposed upstream of the reservoir tank 60 with respect to the outlet 64 of the reservoir tank 60 60 so that the working fluid supplied to the reservoir tank 60 can be stably supplied in a liquid state and at the same time the working fluid is preheated before being supplied to the exhaust heat exchange unit 400, And the efficiency of exhaust heat recovery can be increased.

The working fluid circulation line 100 may include a TEG condenser 370 and a cooling fan 360.

The TEG condenser 370 is disposed between the inlet 62 of the reservoir tank 60 and the recuperator 50 to take the amount of heat from the working fluid and to make the working fluid flowing into the reservoir tank 60 liquid And performs a predetermined role. Further, the piping between the recuperator 50 and the TEG condenser 370 is formed of a working fluid radiator curved a plurality of times, and the working fluid is further cooled by blowing the cooling fan 360 thereto .

The working fluid pump 70 is disposed between the reservoir tank 60 and the recuperator 50 so that the working fluid flowing through the piping connecting the reservoir tank 60 and the working fluid pump 70 When absorbed and vaporized, the pumping efficiency may be lowered. In order to prevent such a decrease in pumping efficiency, a pipe connecting the reservoir tank 60 and the working fluid pump 70 may be heat-treated.

In the working fluid circulation line 100, a point on the turbine inlet pipe 304, which is a conduit connecting the turbine 510 from the EGR side heat exchange unit 300, and a point between the turbine 510 and the recuperator 50 These two points are connected by a working fluid bypass 350 which includes a working fluid bypass valve 352 for selectively bypassing the working fluid to the recuperator 50, Respectively.

If the working fluid exceeds a certain temperature and pressure, the molecular structure may be destroyed and the inherent properties of the working fluid may be lost. When the working fluid can lose its inherent property, the working fluid is supplied to the recuperator 50 (50) by using the working fluid bypass valve 352 to make the working fluid return to the normal state before passing through the turbine 510 ). The working fluid bypassed by the recuperator 50 can pass through the recuperator 50 and return to the normal state.

Ideally, only the working fluid circulates in the working fluid circulation line 100, but the high-temperature working fluid must rotate the turbine 510, and the turbine 510 ) Is lubricated by turbine lubricating oil. Therefore, the working fluid that has passed through the turbine 510 can be mixed with the turbine lube oil, and the oil separator for separating the turbine lube oil discharged from the turbine 510 and other fluid other than the working fluid from the working fluid circulation line 100 (302) may be formed in the piping between the turbine (510) and the recuperator (50).

1, the exhaust gas discharged through the exhaust manifold 3 is supplied to the impeller 6B formed at the exhaust manifold 3 side end portion of the exhaust pipe 404 at a high speed Side impeller 6A formed coaxially with the impeller 6B while rotating the impeller 6B so that the supercharged air flows into the intake manifold 2 through the intercooler 5 and the engine radiator 4 . The exhaust gas that has passed through the impeller 6B passes through the exhaust pipe 404 and the post-treatment unit 402 and the exhaust-side heat exchange unit 400 in order and can be discharged to the outside of the internal combustion engine. Here, the post-treatment unit 402 is installed in the exhaust line to reduce pollutants in the exhaust gas, and may be equipped with a catalytic converter, activated carbon, or the like.

The post-treatment unit 402 is required to have a high exhaust gas temperature in order to purify the exhaust gas. Therefore, the exhaust-side heat exchange unit 400 is disposed on the downstream side of the post-treatment unit 402 provided in the exhaust line .

In the case of a natural intake type internal combustion engine in which the impellers 6A and 6B are not formed, the exhaust gas is discharged from the exhaust manifold 3 The discharged exhaust gas can be discharged to the outside of the internal combustion engine through the exhaust pipe 404, the post-treatment unit 402 and the exhaust-side heat exchange unit 400 in order.

Hereinafter, a method of utilizing the rotational force of the turbine 510 rotated by the working fluid with the turbine generating unit 500 and the auxiliary motor 40 as a main body will be described.

The recycling system according to the present invention has a turbine generating unit 500 that includes a turbine 510, a clutch 520, a motor generator 530, a pulley 540, Respectively.

The turbine 510 is rotatable by receiving energy from the working fluid circulation line 100 and the turbine 510 and the rotors of the motor generator 530 are coaxially connected and the motor generator 530 is connected to the turbine 510 Can be converted into electric energy to charge the battery 20 or to receive power from the battery 20 and rotate. The clutch 520 plays a role of mechanically interrupting the turbine 510 and the pulley 540

The auxiliary motor 40 may be installed so as to engage with the gear train 7 of the engine 1. The auxiliary motor 40 receives power from the battery 20 through the inverter 30, It is possible to drive the gear train 7 installed in the internal combustion engine until the voltage of the battery 20 falls from the starting initial state and becomes the predetermined charging start reference voltage. The auxiliary motor 40 may also be used to start the engine 1. [

The rotation force of the turbine 510 is converted into electric energy by the motor generator 530 and the electric energy is charged in the battery 20 and supplied to the auxiliary motor 40 from the battery 20, It is possible to generate the output for driving the auxiliary motor 40 without lowering the output of the engine 1 itself, unlike the system using the turbo compound or the like, as a system for rotating the gear train 7. Therefore, The load of the engine 1 can be reduced by using the auxiliary motor 40, and the fuel consumption of the internal combustion engine can be increased thereby. It is also possible to assist the driving force of the engine 1 to raise the output of the engine 1. [

When the temperature of the EGR gas flowing through the EGR line 200 is equal to or higher than the reference temperature T1, the turbine generating unit 500 directly drives the rotary shaft 6 installed in the internal combustion engine using the rotational energy of the turbine 510 can do. Here, the rotating shaft 6 provided in the internal combustion engine may be the main driving shaft of the engine 1 that transmits power to the wheels, but the present invention is not limited thereto. For example, And may be an axis that drives the devices operating using the rotational force. The rotational energy from the turbine 510 may be transmitted to the rotary shaft 6 through the belt 8, where a chain or gear may be used instead of the belt 8.

On the other hand, when the temperature of the EGR gas is equal to or higher than the reference temperature T1, the motor generator 530 of the turbine generating unit 500 may convert the rotational energy of the turbine 510 into electric energy, And stored in the battery 20. The rotation of the turbine 510 is used only for power production and the clutch 520 drives the turbine 510 and the pulley 540 to rotate relative to each other The rotating force of the turbine 510 may be used not only for power generation but also for applying power to the rotary shaft 6 installed in the internal combustion engine.

When the temperature of the EGR gas is lower than the reference temperature T1, the motor generator 530 can receive the electric power from the battery 20 and drive the rotary shaft 6 installed in the internal combustion engine. When the temperature of the EGR gas is lower than the reference temperature T1, the circulation of the working fluid in the working fluid circulation line 100 is stopped and the working fluid does not rotate the turbine 510, It is possible to generate a rotational force by receiving power from the battery 20 without any interference from the line 100 and the rotational force causes the rotational shaft 6 to rotate through the belt 8. [

Meanwhile, the turbine generating unit 500 may further include a second clutch (not shown) capable of mechanically interrupting the turbine 510 and the motor generator 530. When the temperature of the EGR gas reaches the reference temperature T1 ). Therefore, when the working fluid rotates the turbine 510, if the period during which the rotational force of the turbine 510 is converted into electrical energy becomes excessively long, the battery 20 may be overcharged. In this case, the second clutch may mechanically disconnect the turbine 510 and the motor generator 530, and the turbine 510 may continue to rotate with the motor generator 530 mechanically disconnected.

The second clutch may mechanically connect the turbine 510 and the motor generator 530 when the voltage of the battery 20 falls to a predetermined charging start reference voltage and in this case the motor generator 530 is connected to the turbine The voltage of the battery 20 can be increased again by charging the battery 20 while rotating together with the battery 510. [

For example, when the voltage of the battery 20 in the initial startup state is 24 V and the charging start reference voltage is 22 V, the auxiliary motor 40 rotates the gear train 7 or various machines provided in the vehicle equipped with the internal combustion engine The motor generator 530 connected to the turbine 510 by the second clutch rotates together with the turbine 510 so that the voltage of the battery (20) The motor generator 530 is disconnected by the second clutch and the battery 20 is prevented from being overcharged when the battery 20 reaches 24V, .

In the foregoing detailed description of the present invention, specific examples have been described. However, various modifications are possible within the scope of the present invention. The technical idea of the present invention should not be limited to the embodiments of the present invention but should be determined by the equivalents of the claims and the claims.

1: Engine 2: Intake manifold
3: exhaust manifold 4: engine radiator
5: intercooler 6: rotating shaft
7: gear train 8: belt
20: Battery 30: Inverter
40: auxiliary motor 50: recuperator
60: reservoir tank 62: inlet
64: outlet 70: working fluid pump
100: working fluid circulation line 200: EGR line
210: EGR valve 220: EGR bypass valve
300: EGR side heat exchange unit 302: Oil separator
304: turbine inlet pipe 310: superheater
320: EGR cooler 330: gas-liquid separator
350: working fluid bypass 352: working fluid bypass valve
360: Cooling fan 370: TEG capacitor
400: exhaust-side heat exchange unit 402: post-processing unit
404: Exhaust pipe 500: Turbine generator unit
510: turbine 520: clutch
530: Motor generator 540: Pulley

Claims (11)

A working fluid circulation line through which the working fluid satisfying the Rankine cycle circulates;
An exhaust-side heat exchange unit installed in an exhaust line for exhausting exhaust gas to transfer heat from the exhaust gas to the working fluid;
A turbine generating unit having a turbine that rotates by receiving energy from the working fluid circulating line, a motor generator that converts the rotational force of the turbine into electrical energy to charge the battery, or rotates by receiving power from the battery; And
An auxiliary motor connected to the gear train of the internal combustion engine and driving the gear train by receiving power from the battery;
A second clutch that mechanically disconnects the turbine and the motor generator when the battery can be overcharged by the motor generator;
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The turbine generating unit transmits the rotational power of the turbine to a rotating shaft installed in the internal combustion engine,
The second clutch mechanically couples the turbine and the motor generator when the voltage of the battery drops to a predetermined charging start reference voltage,
Wherein the internal combustion engine is configured to reduce the load by receiving the rotational power of the turbine and the driving force of the gear train. The method according to claim 1,
The auxiliary motor includes:
Wherein the drive circuit drives the gear train until the voltage of the battery drops from a start-up initial state of the battery to a predetermined charging start reference voltage. The method according to claim 1,
Further comprising an EGR line for circulating a part of the exhaust gas generated in the internal combustion engine to the intake side,
Wherein the motor generator converts the rotational energy of the turbine into electric energy when the temperature of the EGR gas flowing through the EGR line is equal to or higher than the reference temperature (T1). The method of claim 3,
Further comprising an EGR-side heat exchange unit for exchanging heat between EGR gas flowing through the EGR line and a working fluid flowing through the working fluid circulating line. 5. The method of claim 4,
Wherein the EGR gas is circulated to the intake side via the EGR heat exchange unit when the temperature of the EGR gas is equal to or higher than the reference temperature T1, Side heat exchange unit is circulated to the intake side without passing through the heat exchange unit. 6. The method of claim 5,
Wherein T1 is 500 DEG C. 5. The exhaust heat recycling system of an internal combustion engine according to claim 1, The method of claim 3,
Wherein the turbine generating unit further comprises a pulley and a clutch,
Wherein the turbine and the rotor of the motor generator are coaxially connected,
And the clutch interrupts the turbine and the pulley. delete delete 5. The method of claim 4,
Wherein the exhaust-side heat exchange unit is disposed upstream of the EGR-side heat exchange unit on the upstream side of the working fluid circulation line. 11. The method of claim 10,
Wherein the working fluid passes through the exhaust-side heat exchange unit at all times.

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