JP2020037911A - Supercharge system and control device of supercharge system - Google Patents

Abstract

To provide a supercharge system which can stabilize the combustion of fuel in an engine at an engine cold time, and a control device of the supercharge system.SOLUTION: A supercharge system 1 comprises: an electric supercharger 40 having a compressor 41 arranged in an intake passage 3 of an engine 2, and an electric motor 42 for driving the compressor; a bypass passage 51 for making a portion at an upstream side of the intake passage rather than the compressor and a portion at a downstream side communicate with each other; a bypass valve 52 for opening and closing the bypass passage; and a control device 80 for performing control processing for valve-opening the bypass valve, and operating the electric motor at an engine cold time at which a temperature of intake air sucked into the engine, or a temperature of an engine refrigerant for cooling the engine is lower than a preset temperature.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a supercharging system and a control device for the supercharging system.

  BACKGROUND ART Conventionally, a supercharging system including an electric supercharger arranged in an intake passage of an engine and a control device for controlling the electric supercharger has been known (for example, see Patent Document 1).

JP 2017-57752 A

  By the way, in general, when the temperature of the intake air drawn into the engine or the temperature of the engine coolant that cools the engine is lower than a preset temperature, when the engine is cold, the ignitability of fuel in the engine deteriorates. Therefore, the combustion of the fuel may be unstable. In this regard, in the conventional supercharging system, it has been difficult to stabilize fuel combustion in the engine when the engine is cold.

  The present disclosure has been made in view of the above, and an object of the present disclosure is to provide a supercharging system and a control device for a supercharging system that can stabilize fuel combustion in an engine when the engine is cold. It is.

  In order to achieve the above object, a supercharging system according to the present disclosure includes an electric supercharger having a compressor disposed in an intake passage of an engine and an electric motor that drives the compressor, and a turbocharger that is higher than the compressor in the intake passage. A bypass passage communicating the upstream portion and the downstream portion, a bypass valve for opening and closing the bypass passage, and a temperature of intake air taken into the engine or a temperature of an engine coolant for cooling the engine are preset. And a control device that executes control processing for opening the bypass valve and operating the electric motor when the engine is colder than the set temperature.

  In order to achieve the above object, a control device for a supercharging system according to the present disclosure includes: an electric supercharger having a compressor disposed in an intake passage of an engine; and an electric motor driving the compressor. A control device applied to a supercharging system including: a bypass passage that communicates a portion upstream and a portion downstream of the compressor, and a bypass valve that opens and closes the bypass passage. When the temperature of the intake air to be taken in or the temperature of the engine coolant for cooling the engine is lower than a preset temperature, the engine is in a cold state, and a control process for opening the bypass valve and operating the electric motor is executed. .

  According to the supercharging system and the control device for the supercharging system according to the present disclosure, it is possible to stabilize fuel combustion in the engine when the engine is cold.

FIG. 1 is a schematic configuration diagram illustrating a configuration of a supercharging system according to an embodiment. It is an example of a flowchart of control of the supercharging system by the control device according to the embodiment. FIGS. 3A and 3B are explanatory diagrams for explaining the operation and effect when the intake air temperature increase control process according to step S20 is executed. It is an example of the flowchart which the control apparatus which concerns on the modification of embodiment performs while performing the intake air temperature rise control processing which concerns on step S20.

  Hereinafter, a supercharging system 1 and a control device 80 of the supercharging system 1 according to the embodiment will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram for explaining a configuration of a supercharging system 1 according to the present embodiment. The supercharging system 1 includes an engine 2, an intake passage 3, an exhaust passage 4, an exhaust gas recirculation (EGR) device 10, a turbocharger 20, an intercooler 30, and an electric supercharger. 40, a bypass device 50, a flow control valve 60, a group of sensors (temperature sensors 70a and 70b, pressure sensors 71a and 71b, etc.), and a control device 80.

  In the present embodiment, a diesel engine is used as a specific example of the engine 2. The engine 2 includes a cylinder block in which a plurality of cylinders are formed, a cylinder head disposed in an upper part of the cylinder block, a piston disposed in each cylinder, a crankshaft connected to the piston via a connecting rod, And a fuel injection valve for injecting fuel into the corresponding cylinder. The operation of the engine 2 is controlled by a control device 80 described later.

  At least a cylinder block of the engine 2 is provided with a water jacket (that is, an internal refrigerant passage). The refrigerant that cools the engine 2 (referred to as an engine refrigerant) absorbs heat of the engine 2 when passing through the water jacket, thereby cooling the engine 2.

  The intake passage 3 is a passage through which intake air taken into the engine 2 passes. The downstream end of the intake passage 3 in the intake air flow direction is connected to an intake port of the engine 2. The exhaust passage 4 is a passage through which the exhaust gas discharged from the engine 2 passes. The upstream end of the exhaust passage 4 in the exhaust flow direction is connected to an exhaust port of the engine 2.

  The EGR device 10 includes an EGR passage 11, an EGR valve 12, and an EGR cooler 13. The EGR passage 11 communicates between the middle of the exhaust passage 4 and the middle of the intake passage 3. Specifically, the EGR passage 11 according to the present embodiment includes a portion of the exhaust passage 4 on the upstream side of a turbine 21 described later and a portion of the intake passage 3 where a later-described bypass passage 51 is connected to the intake passage 3. And a portion on the downstream side with respect to. EGR valve 12 is arranged in EGR passage 11. The EGR valve 12 opens and closes under the control of the control device 80 to control the flow rate of exhaust gas (referred to as EGR gas) passing through the EGR passage 11. The EGR cooler 13 is a heat exchanger that cools the EGR gas passing through the EGR passage 11 by heat exchange with a refrigerant.

  The EGR cooler 13 according to the present embodiment is arranged in a portion of the EGR passage 11 upstream of the EGR valve 12. However, the location of the EGR cooler 13 is not limited to this. For example, the EGR cooler 13 may be located at a location downstream of the EGR valve 12 in the EGR passage 11.

The turbocharger 20 is a device that supercharges intake air drawn into the engine 2 using energy of exhaust gas. Specifically, the turbocharger 20 according to the present embodiment includes a turbine 21, a compressor 22, and a connection shaft 23 connecting the turbine 21 and the compressor 22. The turbine 21 is arranged in the exhaust passage 4. An exhaust purification device (not shown) such as a filter is disposed in a portion of the exhaust passage 4 downstream of the turbine 21. The compressor 22 is arranged in the intake passage 3. The turbine 21 rotates by receiving the energy of the exhaust gas passing through the exhaust passage 4. When the turbine 21 rotates, the compressor 22 connected to the turbine 21 via the connection shaft 23 also rotates, and compresses the intake air passing through the intake passage 3 (ie, supercharges).

  In the present embodiment, the turbocharger 20 is not an essential component, and the supercharger system 1 may have a configuration without the turbocharger 20. However, when the supercharging system 1 includes the turbocharger 20, the intake air drawn into the engine 2 can be supercharged more effectively than when the turbocharger 20 does not include the turbocharger.

  The intercooler 30 is a heat exchanger that cools the intake air in the intake passage 3 by exchanging heat with refrigerant. The intercooler 30 according to the present embodiment is disposed in a portion of the intake passage 3 upstream of the compressor 41 of the electric supercharger 40 and downstream of the compressor 22 of the turbocharger 20. Cooling the intake air passing through the part.

  The intercooler 30 is not an essential component in the present embodiment, and the supercharging system 1 may have a configuration without the intercooler 30. However, when the supercharging system 1 includes the intercooler 30, it is possible to effectively suppress the intake air drawn into the engine 2 from becoming too hot as compared with the case where the supercooling system 1 does not include the intercooler 30.

  Here, the refrigerant of the intercooler 30 according to the present embodiment (referred to as an intercooler refrigerant) is configured by a refrigerant of a different system from the engine refrigerant that cools the engine 2. Specifically, the intercooler refrigerant according to the present embodiment is a refrigerant circulation path for the intercooler (this is a path for the intercooler refrigerant to circulate between the intercooler 30 and the refrigerant pump for the intercooler 30). ), The intercooler refrigerant circulation path includes an engine refrigerant circulation path (this is a path through which the engine refrigerant circulates between the engine 2 and the engine 2 refrigerant pump). Not joined. However, the present invention is not limited to this configuration. For example, a configuration in which the intercooler refrigerant mixes with the engine refrigerant in the course of its distribution may be adopted.

  The location of the intercooler 30 in the intake passage 3 is not limited to the location illustrated in FIG. To give another example, the intercooler 30 is provided in a portion of the intake passage 3 downstream of the compressor 41 of the electric supercharger 40, more specifically, in a portion of the intake passage 3 downstream of the compressor 41. Of these, the bypass passage 51 may be further disposed at a portion downstream of the portion connected to the intake passage 3 and at a portion upstream of the portion where the flow control valve 60 is disposed.

  The electric supercharger 40 is a supercharger driven by electricity. Specifically, the electric supercharger 40 according to the present embodiment includes a compressor 41, an electric motor 42 that drives the compressor 41, and a connection shaft 43 that connects the compressor 41 and the electric motor 42. The compressor 41 is disposed in a portion of the intake passage 3 downstream of the compressor 22 of the turbocharger 20 (in the present embodiment, further downstream of the intercooler 30). The electric motor 42 is electrically connected to a power supply (battery). The operation of the electric motor 42 is controlled by the control device 80. When the electric motor 42 operates (specifically, rotates), the compressor 41 connected to the electric motor 42 via the connection shaft 43 rotates, and the rotated compressor 41 compresses intake air.

The bypass device 50 is a device that allows the intake air in the intake passage 3 to pass by bypassing the compressor 41 of the electric supercharger 40. Specifically, the bypass device 50 according to the present embodiment includes a bypass passage 51 and a bypass valve 52 that opens and closes the bypass passage 51.

  The bypass passage 51 has a portion on the upstream side of the compressor 41 of the electric supercharger 40 in the intake passage 3 (in the present embodiment, a portion on the downstream side of the compressor 22 and the intercooler 30 of the turbocharger 20). And a portion of the intake passage 3 downstream of the compressor 41.

  The bypass valve 52 according to the present embodiment is configured by an on-off valve that is opened and closed under the control of the control device 80. When the bypass valve 52 is closed to close the bypass passage 51, the intake air that has passed through the intercooler 30 is introduced into the compressor 41. When the bypass passage 52 is opened by opening the bypass valve 52, the intake air that has passed through the intercooler 30 preferentially passes through the bypass passage 51. That is, in this case, the intake air that has passed through the intercooler 30 flows by bypassing the compressor 41.

The flow rate adjustment valve 60 is located downstream of the “portion where the bypass passage 51 is connected to the intake passage 3” in the intake passage 3 and the “portion where the EGR passage 11 is connected to the intake passage 3” in the intake passage 3. ”Is located on the upstream side. The flow control valve 60 is controlled by the control device 80 to adjust the intake flow rate (m ³ / sec) of the intake air passing through the flow control valve 60. Thus, the intake flow rate in the intake passage 3 on the downstream side of the flow control valve 60 can be adjusted. Specifically, when the flow control valve 60 that has received the instruction from the control device 80 reduces the intake flow rate, the intake flow rate downstream of the flow control valve 60 decreases.

  Temperature sensor 70 a detects the temperature of the intake air taken into engine 2 and transmits the detection result to control device 80. Specifically, the temperature sensor 70a according to the present embodiment detects, for example, the temperature of the intake air at the downstream end (the intake port portion of the engine 2) in the intake passage 3. Temperature sensor 70b detects the temperature of the engine refrigerant and transmits the detection result to control device 80. Specifically, the temperature sensor 70b according to the present embodiment is arranged, for example, in a portion of a water jacket in the engine 2 and detects the temperature of the engine refrigerant in this portion.

  The pressure sensor 71a detects the inlet pressure of the EGR passage 11 (pressure at the upstream end) and transmits the detected value to the control device 80. The pressure sensor 71b detects the outlet pressure of the EGR passage 11 (pressure at the downstream end) and transmits the detected value to the control device 80.

  The supercharging system 1 includes, for example, a crank angle sensor that detects a crank angle of the engine 2 and an accelerator pedal of a vehicle equipped with the supercharging system 1 in addition to the above-described sensors illustrated in FIG. Accelerator opening sensor that detects the accelerator opening of the vehicle, a brake opening sensor that detects the brake opening of the brake pedal of the vehicle, a rotation speed sensor that detects the engine speed of the engine 2, a vehicle speed sensor that detects the vehicle speed of the vehicle, and the like. And various sensors.

  The control device 80 is electrically connected to control objects (in the present embodiment, the engine 2, the EGR valve 12, the electric motor 42, the bypass valve 52, and the flow control valve 60), and controls these control objects. I do. Such a control device 80 includes a CPU (Central Processing Unit) 81 as an example of a processor that executes various control processes, and a storage unit 82 that stores various data and programs used for the operation of the CPU 81. It has a microcomputer. The storage unit 82 is specifically configured by a storage medium such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The supercharging system 1 according to the present embodiment has a configuration in which a control target is controlled by one control device 80, but is not limited to this configuration. For example, the control target is controlled by a plurality of control devices. May be adopted.

  Subsequently, details of control of the supercharging system 1 by the control device 80 according to the present embodiment will be described. FIG. 2 is an example of a flowchart of control of the supercharging system 1 by the control device 80 according to the present embodiment. Each step in FIG. 2 is specifically executed by the CPU 81 of the control device 80 based on a program stored in the storage unit 82. The control device 80 starts the flowchart of FIG. 2 at the same time as the start of the engine 2 (start of cranking), and thereafter repeatedly executes the process at a predetermined cycle. Further, at the time of the first start in FIG. 2, it is assumed that the bypass valve 52 is closed and the electric motor 42 of the electric supercharger 40 is stopped.

  In step S10, the control device 80 determines whether or not the temperature of the intake air sucked into the engine 2 or the temperature of the engine refrigerant is lower than a preset temperature in the "engine cold state". Specifically, in step S10, control device 80 determines whether the intake air temperature detected by temperature sensor 70a is lower than a first temperature set in advance, or whether the engine coolant temperature detected by temperature sensor 70b is It is determined whether the temperature is lower than a preset second temperature. When the intake air temperature detected by the temperature sensor 70a is determined to be lower than the first temperature, or when the engine refrigerant temperature detected by the temperature sensor 70b is determined to be lower than the second temperature, the control device It is determined that the engine 80 is cold (that is, the engine 2 is cold).

  Although the specific value of the first temperature is not particularly limited, in the present embodiment, the first temperature is such that the ignitability of the fuel in the engine 2 deteriorates and the combustion of the fuel becomes unstable. Intake temperature is used. As a specific example of such a first temperature, for example, a temperature in the range of 0 ° C to 20 ° C can be used. In the present embodiment, 10 ° C. is used as a specific example of the first temperature.

  Further, although the specific value of the second temperature is not particularly limited, in the present embodiment, the second temperature is used as the second temperature, so that the ignitability of the fuel in the engine 2 deteriorates and the combustion of the fuel becomes unstable. Such an engine coolant temperature is used. As a specific example of such a second temperature, for example, a temperature in the range of 30 ° C to 50 ° C can be used. In the present embodiment, 40 ° C. is used as a specific example of the second temperature. The first temperature and the second temperature are stored in the storage unit 82 of the control device 80 in advance (that is, set in advance).

  Step S10 is repeatedly executed until it is determined as YES. When it is determined as YES in step S10 (that is, when the engine is cold), the control device 80 performs the control process of opening the bypass valve 52 and operating the electric motor 42 (the “intake air temperature rise control process”). (Step S20). The operation and effect of the case where the intake air temperature rise control process according to step S20 is executed will be described as follows.

  FIG. 3A is an explanatory diagram for explaining a state immediately after execution of the intake air temperature rise control processing, and FIG. 3B is a state after a short time has passed since the execution of the intake air temperature increase control processing. FIG. 3 is an explanatory diagram for explaining the method.

First, referring to FIG. 3A, when the intake air temperature increase control process in step S <b> 20 is executed, the intake valve preferentially passes through the bypass passage 51 as a result of the opening of the bypass valve 52. However, even in this state, since air exists around the compressor 41 of the electric supercharger 40, when the compressor 41 rotates in this state, the outlet pressure of the compressor 41 becomes the inlet pressure of the compressor 41. Higher than. As a result, as shown in FIG. 3B, the intake air on the outlet side of the compressor 41 flows backward through the bypass passage 51 and flows into the inlet side of the compressor 41. That is, an “intake air circulation flow” in which the intake air circulates between the compressor 41 and the bypass passage 51 is formed. The temperature of the circulating flow of the intake air gradually increases due to friction between the circulating flow of the intake air and the rotating compressor 41.

  Even when the intake air is circulating in this way, a part of the circulating flow of the intake air is sucked into the engine 2 when the piston of the engine 2 moves down in the cylinder during the intake stroke. That is, a part of the circulating flow whose temperature has risen is drawn into the engine 2.

  By the above mechanism, the temperature of the intake air taken into the engine 2 can be increased by performing the intake temperature increase control process in step S20.

  Note that the termination condition for terminating the execution of the intake air temperature rise control process in step S20, that is, the termination condition for closing the bypass valve 52 and stopping the operation of the electric motor 42, is particularly limited. However, for example, a condition that the elapsed time from the start of the execution of step S20 has reached a predetermined time, a condition that the engine is no longer cold, or the like can be used. In determining whether or not the engine is no longer cold, the control device 80 determines that the intake air temperature detected by the temperature sensor 70a is equal to or higher than the first temperature, and that the engine refrigerant temperature detected by the temperature sensor 70b is equal to the second temperature. In this case, it may be determined that the engine is no longer cold.

  Further, during execution of the intake air temperature rise control process at step S20, the control device 80 according to the present embodiment makes the outlet pressure of the EGR passage 11 equal to or higher than the inlet pressure of the EGR passage 11 with the EGR valve 12 opened. In this case, the outlet pressure of the EGR passage 11 is reduced by controlling the flow adjustment valve 60 so that the intake air flow downstream of the flow adjustment valve 60 is reduced. The pressure is set lower than the inlet pressure of the EGR passage 11.

  Specifically, the control device 80 monitors the detection results of the pressure sensor 71b and the pressure sensor 71a while the EGR valve 12 is opened during the execution of the intake air temperature increase control process according to step S20. It is determined whether or not the outlet pressure of the EGR passage 11 has become equal to or higher than the inlet pressure while the EGR valve 12 is open. If the control device 80 determines that the outlet pressure of the EGR passage 11 has become equal to or higher than the inlet pressure, the control device 80 throttles the flow control valve 60 to reduce the intake flow rate downstream of the flow control valve 60. As a result, the outlet pressure of the EGR passage 11 decreases, so that the outlet pressure of the EGR passage 11 becomes lower than the inlet pressure of the EGR passage 11. As a result, the EGR gas can flow back to the intake passage 3 through the EGR passage 11.

  The operational effects of the present embodiment as described above are summarized as follows. According to the present embodiment, when the engine is cold (YES in step S10), the intake air temperature increase control process (step S20) of opening the bypass valve 52 and operating the electric motor 42 is executed. As described above, when the engine is cold, the temperature of the intake air drawn into the engine 2 can be increased. This makes it possible to stabilize fuel combustion in the engine 2 when the engine is cold.

Further, according to the present embodiment, during the execution of the intake air temperature rise control process in step S20, when the outlet pressure of the EGR passage 11 becomes equal to or higher than the inlet pressure of the EGR passage 11 with the EGR valve 12 opened. In order to reduce the outlet pressure of the EGR passage 11 by controlling the flow adjustment valve 60 so that the intake air flow downstream of the flow adjustment valve 60 decreases, the outlet pressure of the EGR passage 11 is reduced. Lower than the inlet pressure. Thus, even when the electric supercharger 40 operates during cold engine, the EGR gas can be returned to the intake passage 3 through the EGR passage 11.

(Modification of the above embodiment)
In the above embodiment, the control device 80 may further execute the following flowchart shown in FIG. 4 during the execution of the intake air temperature increase control process in step S20.

  FIG. 4 is an example of a flowchart executed by the control device 80 according to the present modification during the execution of the intake air temperature increase control process at step S20. 4 are executed by the CPU 81 of the control device 80 based on a program stored in the storage unit 82.

  First, the control device 80 starts the flowchart of FIG. 4 first when the execution of the intake air temperature increase control process in step S20 of FIG. 2 is started. In step S30 of FIG. 4, control device 80 determines whether or not there is an “acceleration request” that is a request to accelerate the rotation of engine 2. Although the specific execution content of step S30 is not particularly limited, the control device 80 according to the present modification determines, as an example, the presence or absence of an acceleration request based on the detection result of the accelerator opening.

  Specifically, control device 80 acquires the accelerator opening based on the detection result of the accelerator opening sensor, and the acquired increasing speed (increase amount per unit time) of accelerator opening is greater than zero. When it has become, it is determined that there is an acceleration request (YES), and when the increasing speed of the accelerator opening is zero, it is determined that there is no acceleration request (NO). Step S30 is repeatedly executed until it is determined to be YES.

  If NO is determined in step S30, control device 80 continues to execute the intake air temperature increase control process in step S20.

  On the other hand, if YES is determined in step S30 (if there is an acceleration request), in step S40, control device 80 stops executing the intake air temperature increase control process. At the same time, the control device 80 executes a control process for closing the bypass valve 52 and operating the electric motor 42 (referred to as a supercharging control process). If the electric motor 42 is already operating, the control device 80 continues operating the electric motor 42 as it is.

  In the supercharging control process according to step S40, the intake air that has passed through the intercooler 30 is introduced into the compressor 41 by closing the bypass valve 52. Then, by rotating the compressor 41 in this state, the intake air can be supercharged by the compressor 41. Then, by introducing the supercharged intake air into the engine 2, the rotation of the engine 2 can be rapidly accelerated.

  As described above, according to the present modification, when there is a request to accelerate the engine 2 when the engine is cold, the rotation of the engine 2 can be rapidly accelerated in response to the request for acceleration. . Also in this modified example, when there is no request for acceleration of the engine 2 when the engine is cold, the execution of the intake air temperature increase control process in step S20 described above is continued. And the combustion of the fuel in the engine 2 can be stabilized.

  The above-described embodiments and modified examples have been presented as examples, and do not limit the scope of the invention. The above-described embodiments and modifications can be further modified and changed within the scope of the invention described in the claims.

DESCRIPTION OF SYMBOLS 1 Supercharging system 2 Engine 3 Intake passage 10 EGR device 11 EGR passage 12 EGR valve 20 Turbocharger 30 Intercooler 40 Electric supercharger 41 Compressor 42 Electric motor 50 Bypass device 51 Bypass passage 52 Bypass valve 60 Flow control valve 80 Control device

Claims (4)

An electric supercharger having a compressor disposed in an intake passage of the engine and an electric motor driving the compressor,
A bypass passage communicating an upstream portion and a downstream portion of the intake passage with respect to the compressor,
A bypass valve for opening and closing the bypass passage;
A control process for opening the bypass valve and operating the electric motor when the temperature of the intake air drawn into the engine or the temperature of the engine coolant that cools the engine is lower than a preset temperature when the engine is cold. A supercharging system, comprising: An exhaust recirculation passage that communicates between a passageway in the exhaust passage of the engine and a portion of the intake passage on the downstream side of a portion where the bypass passage is connected to the intake passage;
An exhaust gas recirculation valve disposed in the exhaust gas recirculation passage;
In a portion of the intake passage downstream of a portion where the bypass passage is connected to the intake passage, and in a portion of the intake passage upstream of a portion where the exhaust recirculation passage is connected to the intake passage. Further comprising an arranged flow control valve,
The control device, during the execution of the control process, when the outlet pressure of the exhaust gas recirculation passage becomes equal to or higher than the inlet pressure of the exhaust gas recirculation passage with the exhaust gas recirculation valve opened, The flow rate control valve is controlled such that the intake flow rate downstream of the flow rate control valve is reduced, so that the outlet pressure is reduced and the outlet pressure is lower than the inlet pressure. Supercharging system.   The control device, during the execution of the control process, if there is an acceleration request to accelerate the rotation of the engine, stops the execution of the control process, closes the bypass valve, and the electric motor The supercharging system according to claim 1, wherein the supercharging system executes a control process for operating the supercharger. An electric supercharger having a compressor disposed in an intake passage of the engine and an electric motor driving the compressor, and a bypass passage communicating an upstream portion and a downstream portion of the intake passage with respect to the compressor. A control device applied to a supercharging system, comprising: a bypass valve that opens and closes the bypass passage.
A control process for opening the bypass valve and operating the electric motor when the temperature of the intake air drawn into the engine or the temperature of the engine coolant that cools the engine is lower than a preset temperature when the engine is cold. To perform the control of the supercharging system.

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