JP2008292040A - Heat exchanger system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger system capable of improving the efficiency of the heat exchange of a heat exchanger while suppressing the deterioration of fuel economy of a vehicle. <P>SOLUTION: This heat exchanger system 100 used in an internal combustion engine 10 mounted to the vehicle is provided with the heat exchanger 20 connected with the internal combustion engine, a vibration exciting means 30 connected with the heat exchanger and exciting the vibration of the heat exchanger to improve heat a transfer coefficient of the heat exchanger, a heat-radiation quantity determining means 52 for determining whether a quantity of the heat generation of the internal combustion engine is larger than a quantity of heat radiation of the heat exchanger or not, and a vibration excitation control means 56 for controlling the vibration exciting means to excite the vibration of the heat exchanger based on results of the determination of the heat-radiation quantity determining means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat exchanger system, and more particularly to a heat exchanger system mounted on a vehicle.

  A heat exchanger mounted on a vehicle includes, for example, a plurality of heat transfer tubes arranged in parallel and wavy heat radiation fins arranged so as to sandwich these heat transfer tubes as main components. The heat transfer pipe communicates with a cooling pipe provided around the engine. A coolant for absorbing the heat of the engine flows in the cooling pipe and the heat transfer pipe. The coolant absorbs engine heat on the engine side, releases heat absorbed on the heat exchanger side to the outside, and absorbs engine heat on the engine side again. As the coolant repeats this, the engine is cooled.

  In such a heat exchanger, heat is transferred between the coolant in the heat transfer tube and the air flowing around the fins. At this time, a temperature boundary layer may be formed near the surface of the fin. Since the heat transfer coefficient of the temperature boundary layer is low, the heat transfer efficiency of the heat exchanger is improved as the temperature boundary layer is thinner. Therefore, in order to improve the heat transfer efficiency of the heat exchanger, for example, a technique for vibrating the heat exchanger is disclosed.

  Patent Document 1 discloses a technique in which permanent magnets are arranged to face each other with a heat transfer tube interposed therebetween, and a heat exchanger is vibrated by applying a magnetic field to the permanent magnets so that the temperature boundary layer disappears. Patent Document 2 discloses a technology that includes a vibration device that vibrates a fin and controls a vibration amount by determining a temperature boundary layer by measuring a temperature distribution of the fin. Patent Document 3 discloses a technique for destroying a temperature boundary layer by applying ultrasonic vibration to a heat exchanger. Patent Document 4 discloses a technique for stirring and extinguishing a temperature boundary layer by applying ultrasonic vibration to a heat exchanger.

JP-A-62-33298. JP-A-8-170895. Japanese Patent Application Laid-Open No. 58-110995. Japanese Utility Model Publication No. 58-27688.

  In recent years, as vehicles have been downsized, there has been a strong demand for downsizing heat exchangers mounted on vehicles. However, if the heat exchanger is vibrated to meet this requirement, the electric power is required for the vibration, and the fuel consumption of the vehicle may be deteriorated.

  An object of this invention is to provide the heat exchanger system which can improve the heat exchange efficiency of a heat exchanger, suppressing the fuel consumption fall of a vehicle.

  A heat exchanger system according to the present invention is a heat exchanger system used for an internal combustion engine mounted on a vehicle, the heat exchanger connected to the internal combustion engine, and the heat exchanger connected to the heat exchanger. Excitation means for oscillating the heat exchanger to improve the heat transfer rate, heat release amount determination means for determining whether the heat generation amount of the internal combustion engine is larger than the heat release amount of the heat exchanger, and heat release amount determination Vibration control means for controlling the vibration means to vibrate the heat exchanger based on the determination result of the means. According to the heat exchanger system of the present invention, since the vibration means is provided, the formation of the temperature boundary layer around the fins of the heat exchanger is suppressed. Thereby, the heat exchange efficiency of the heat exchanger is improved. Further, since the heat radiation amount determining means and the vibration control means are provided, the vibration means is vibrated when the heat generation amount of the internal combustion engine is larger than the heat radiation amount of the heat exchanger. In this case, compared with the case where the vibration means is always operated, the load of the power source for operating the vibration means is small, so that the fuel efficiency of the vehicle is improved.

  The above configuration further includes load factor detection means for detecting the load factor of the internal combustion engine and vehicle speed detection means for detecting the speed of the vehicle, and the heat radiation amount determination means has a detection result of the load factor detection means equal to or greater than a predetermined value. When the detection result of the vehicle speed detection means is not more than a predetermined value, it may be determined that the heat generation amount of the internal combustion engine is larger than the heat dissipation amount of the heat exchanger.

  In the above configuration, the load factor detecting means for detecting the load factor of the internal combustion engine, the vehicle speed detecting means for detecting the speed of the vehicle, and the time for acquiring the elapsed time after the detection result of the vehicle speed detecting means becomes a predetermined value or less. An acquisition means; and a time determination means for determining whether or not the acquisition result of the time acquisition means is equal to or greater than a predetermined time, and the heat dissipation amount determination means includes a detection result of the load factor detection means equal to or greater than a predetermined value. And when the detection result of the vehicle speed detection means is less than or equal to a predetermined value, it is determined that the heat generation amount of the internal combustion engine is larger than the heat dissipation amount of the heat exchanger, and the vibration control means is The heat exchanger is vibrated when it is determined that the amount of heat generated is greater than the amount of heat released from the heat exchanger, and the time determination means determines that the acquisition result of the time acquisition means is greater than or equal to a predetermined time. To control the vibration means Good. According to this configuration, the time acquisition unit and the time determination unit are further provided. Thereby, the excitation means is vibrated after a predetermined time has elapsed since the amount of heat generated by the internal combustion engine is greater than the amount of heat released by the heat exchanger. In this case, the fuel consumption of the vehicle can be further improved as compared with the case where the time acquisition unit and the time determination unit are not provided.

  In the above configuration, the apparatus further comprises load factor detecting means for detecting the load factor of the internal combustion engine, and climbing state determining means for determining whether or not the vehicle is in an uphill state, and the heat release amount determining means is the load factor detecting means. May be determined that the amount of heat generated by the internal combustion engine is greater than the amount of heat released by the heat exchanger when it is determined by the uphill state determination means that the vehicle detection result is equal to or greater than a predetermined value and the vehicle is in the uphill state. .

  ADVANTAGE OF THE INVENTION According to this invention, the heat exchanger system which can improve the heat exchange efficiency of a heat exchanger can be provided, suppressing the fuel consumption fall of a vehicle.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1 is a block diagram showing an overall configuration of a heat exchanger system 100 according to a first embodiment of the present invention. As shown in FIG. 1, a heat exchanger system 100 is used for an internal combustion engine 10, and includes a heat exchanger 20, an excitation means 30, a load factor detection means 42, a vehicle speed detection means 44, an ECU 50, a power source. 60. FIG. 1 also shows a transmission 70 connected to the internal combustion engine 10. The internal combustion engine 10 is not particularly limited as long as it is mounted on a vehicle. For example, a gasoline engine or the like can be used.

  The heat exchanger 20 is connected to the internal combustion engine 10 and has a function of cooling the heat generated in the internal combustion engine 10. As the heat exchanger 20, for example, a radiator or the like can be used. The heat exchanger 20 includes, as main components, for example, a plurality of heat transfer tubes (not shown) arranged in parallel and a wave-like heat radiation fin (not shown) arranged so as to sandwich the heat transfer tubes. ing. The heat transfer pipe communicates with a cooling pipe (not shown) provided around the internal combustion engine 10. A coolant (not shown) for absorbing the heat of the internal combustion engine 10 flows in the cooling pipe and the heat transfer pipe. The fin is in contact with the outside air. The coolant absorbs the heat of the internal combustion engine 10 on the internal combustion engine 10 side. Then, returning to the heat exchanger 20 side, the absorbed heat is released to the outside air through the fins, and the heat of the internal combustion engine 10 is absorbed again on the internal combustion engine 10 side. As the coolant repeats this, the internal combustion engine 10 is cooled.

  The vibration means 30 is connected to the heat exchanger 20. The vibration means 30 vibrates the heat exchanger 20 in order to improve the heat transfer coefficient of the heat exchanger 20 in accordance with an instruction from the ECU 50. The vibration means 30 is not particularly limited as long as the heat exchanger 20 can be vibrated. For example, as the vibration means 30, what is provided with the magnetic material apply | coated to each fin of the heat exchanger 20, and the magnetic field generator connected to each fin can be used. In this case, the vibration means 30 causes the magnetic material to generate a magnetic field in accordance with an instruction from the ECU 50. Thereby, each fin is vibrated. In this case, the generation of a temperature boundary layer around each fin is suppressed. As a result, the heat exchange efficiency of the heat exchanger 20 is improved.

  The load factor detection means 42 detects the load factor of the internal combustion engine 10. As the load factor detecting means 42, for example, a throttle opening sensor can be used. The throttle opening sensor is connected to the throttle of the internal combustion engine 10, detects the throttle opening, and transmits the detection result to the ECU 50. The vehicle speed detection means 44 detects the vehicle speed of the vehicle. As the vehicle speed detection means 44, for example, a vehicle speed sensor or the like can be used. For example, the vehicle speed sensor detects the vehicle speed based on the rotation of the output shaft of the transmission 70 mounted on the vehicle, and transmits the detection result to the ECU 50.

  The ECU 50 is an electronic control unit (Electronic Control Unit) composed of a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory) and the like. The ECU 50 controls the operation of the vibration means 30. The ECU 50 includes a heat release amount determination unit 52, a time acquisition unit 54, a time determination unit 55, and an excitation control unit 56.

  The heat release amount determination means 52 determines whether or not the heat generation amount of the internal combustion engine 10 is larger than the heat release amount of the heat exchanger 20. The time acquisition unit 54 acquires an elapsed time after the detection result of the vehicle speed detection unit 44 becomes a predetermined value or less. The time acquisition unit 54 includes, for example, a timer, and starts measurement when the detection result of the vehicle speed detection unit 44 becomes a predetermined value or less, and measures the holding time held below the predetermined value. Thereby, the time acquisition means 54 can acquire the elapsed time after the detection result of the vehicle speed detection means 44 becomes a predetermined value or less. The time determination unit 55 determines whether the acquisition result of the time acquisition unit 54 is equal to or longer than a predetermined time. The vibration control means 56 controls the vibration means 30 so that the heat exchanger 20 is vibrated based on the determination result of the heat release amount determination means 52 and the determination result of the time determination means 55.

  The power source 60 supplies power to the vibration means 30 and the ECU 50. As the power supply 60, for example, a battery or the like can be used. The battery is connected to a generator (not shown) connected to the internal combustion engine 10. The generator generates electric power when a rotational force is applied from the internal combustion engine 10 and supplies the generated electric power to the battery. The battery is charged with the electric power supplied from the generator.

  The transmission 70 is connected between a crankshaft (not shown) of the internal combustion engine 10 and a vehicle axle (not shown). The transmission 70 receives power from the crankshaft and outputs it to the axle. At this time, the rotational speed of the crankshaft is changed to a rotational speed corresponding to the reduction ratio of the transmission 70 and output to the axle. Although it does not specifically limit as the transmission 70, For example, the transmission which changes a reduction ratio in steps according to a driver's operation, The automatic transmission which changes a reduction ratio in steps automatically regardless of a driver's operation (AT) or the like can be used.

  Next, the determination method of the heat release amount determination means 52 will be described in detail. First, as the load factor of the internal combustion engine 10 increases, the heat generation amount of the internal combustion engine 10 increases. In this case, the heat radiation amount that the heat exchanger 20 must radiate also increases. On the other hand, when the vehicle speed increases, the amount of outside air per unit time corresponding to the fins of the heat exchanger 20 also increases. In this case, the heat dissipation amount of the heat exchanger 20 increases. That is, whether or not the heat generation amount of the internal combustion engine 10 is larger than the heat dissipation amount of the heat exchanger 20 is affected by the vehicle speed and the load factor of the internal combustion engine 10. FIG. 2 is a schematic diagram showing the relationship between the vehicle speed and the load factor of the internal combustion engine 10. In FIG. 2, the vertical axis represents the vehicle speed, and the horizontal axis represents the load factor of the internal combustion engine 10. In FIG. 2, the determination line 75 represents the vehicle speed at which the heat generation amount of the internal combustion engine 10 and the heat dissipation amount of the heat exchanger 20 are equal. That is, a region where the vehicle speed is slower than the determination line 75 is a region where the heat generation amount of the internal combustion engine 10 is larger than the heat dissipation amount of the heat exchanger 20.

  A region where the heat generation amount of the internal combustion engine 10 is larger than the heat dissipation amount of the heat exchanger 20 may be calculated or measured in advance and stored in the ROM of the ECU 50 as a map. The heat release amount determination means 52 refers to the map stored in the ROM based on the detection results of the load factor detection means 42 and the vehicle speed detection means 44, so that the heat generation amount of the internal combustion engine 10 is reduced by the heat exchanger 20. It can be determined whether or not it is larger than the heat dissipation amount.

  Subsequently, the operation of the heat exchanger system 100 will be described. FIG. 3 is a flowchart showing an example of the operation of the ECU 50 until the vibration means 30 operates. For example, when the operation of the vehicle on which the heat exchanger system 100 is mounted is started, the load factor detection means 42 and the vehicle speed detection means 44 detect the load factor of the internal combustion engine 10 and the vehicle speed of the vehicle, respectively, and send it to the ECU 50. Tell.

  Next, the heat release amount determination means 52 determines whether or not the load factor is a predetermined value or more (for example, 90% or more) (step S1). When it is determined in step S1 that the load factor is equal to or greater than the predetermined value, the heat release amount determination means 52 reads a vehicle speed determination value corresponding to the load factor from the map (step S2). For example, as shown in FIG. 2, when the load factor of the internal combustion engine 10 is 75a, the heat release amount determination means 52 reads the vehicle speed 75b corresponding to the load factor 75a as a determination value.

  Next, the heat release amount determination means 52 determines whether or not the vehicle speed is equal to or less than a determination value (step S3). When it is determined in step S3 that the vehicle speed is equal to or less than the determination value, the heat release amount determination unit 52 determines that the heat generation amount of the internal combustion engine 10 is larger than the heat release amount of the heat exchanger 20. Next, the time acquisition unit 54 acquires an elapsed time after the detection result of the vehicle speed detection unit 44 becomes equal to or less than the determination value (step S4). Next, the time determination unit 55 determines whether or not the acquisition result of the time acquisition unit 54 is a predetermined time or more (for example, 10 seconds or more) (step S5). In step S5, when it is determined that the acquisition result of the time acquisition unit 54 is equal to or longer than the predetermined time, the vibration control unit 56 controls the vibration unit 30 to vibrate the heat exchanger 20 ( Step S6). Thereafter, the ECU 50 ends the execution of the flowchart.

  On the other hand, if it is not determined in step S1 that the load factor is equal to or greater than the predetermined value, the time acquisition unit 54 deletes the acquisition time acquired at the time of execution of the previous flowchart, if any. (Step S7). Next, the ECU 50 ends the execution of the flowchart. If it is not determined in step S3 that the vehicle speed is equal to or lower than the determination value, the time acquisition unit 54 deletes the acquisition time acquired when the previous flowchart is executed (if it is acquired) ( Step S7). Next, the ECU 50 ends the execution of the flowchart. If it is not determined in step S5 that the acquisition result of the time acquisition unit 54 is equal to or longer than the predetermined time, the ECU 50 ends the execution of the flowchart.

  According to the heat exchanger system 100 according to the present embodiment, since the vibration means 30 is provided, the formation of a temperature boundary layer around the fins of the heat exchanger 20 is suppressed. Thereby, the heat exchange efficiency of the heat exchanger 20 improves. In addition, since the heat radiation amount determination means 52 and the vibration control means 56 are provided, the vibration means 30 is vibrated when the heat generation amount of the internal combustion engine 10 is larger than the heat radiation amount of the heat exchanger 20. In this case, since the load of the power source 60 for operating the vibration means 30 is less than when the vibration means 30 is always operated, the fuel efficiency of the vehicle is improved. In addition, since the time acquisition means 54 and the time determination means 55 are further provided, the vibration excitation means 30 is added after a predetermined time has elapsed since the heat generation amount of the internal combustion engine 10 is larger than the heat dissipation amount of the heat exchanger 20. Shake. In this case, the fuel consumption of the vehicle can be further improved as compared with the case where the time acquisition unit 54 and the time determination unit 55 are not provided.

  Then, the heat exchanger system 100a which concerns on 2nd Example of this invention is demonstrated. FIG. 4 is a block diagram showing the overall configuration of the heat exchanger system 100a according to the second embodiment. As shown in FIG. 4, the heat exchanger system 100 a is different from the heat exchanger system 100 shown in FIG. 1 in that an ECU 50 a is provided instead of the ECU 50 and a transmission 70 a is provided instead of the transmission 70. Other configurations are the same as those of the heat exchanger system 100 shown in FIG.

  The ECU 50a includes a heat release amount determination unit 52a, an excitation control unit 56a, and an uphill determination unit 58. The heat release amount determination unit 52a determines whether or not the heat generation amount of the internal combustion engine 10 is larger than the heat release amount of the heat exchanger 20. The vibration control unit 56a controls the vibration unit 30 so that the heat exchanger 20 is vibrated based on the determination result of the heat release amount determination unit 52a.

  The uphill determination means 58 determines whether or not the vehicle is in an uphill state. The climbing determination means 58 is not particularly limited as long as it can determine whether or not the vehicle is in an uphill state. As the uphill determination means 58, for example, an uphill determination means used for a general AT can be used. For example, the uphill determination means 58 stores in advance a map indicating the relationship between the vehicle speed and the load factor of the internal combustion engine 10 when traveling on flat ground in the ROM. When the vehicle is in an uphill state, the load factor of the internal combustion engine 10 is increased compared to the load factor of the internal combustion engine 10 when the vehicle speed is traveling on a flat ground. That is, the uphill determination means 58 determines that the vehicle is in the uphill state by referring to the detection result of the vehicle speed detection means 44, the detection result of the load factor detection means 42, and the map stored in the ROM in advance. Can do.

  An AT is preferably used as the transmission 70a. In this case, the uphill determination means possessed by the AT can be used as the uphill determination means 58.

  Next, the determination method of the heat release amount determination unit 52a will be described in detail. As already described with reference to FIG. 2, whether or not the heat generation amount of the internal combustion engine 10 is greater than the heat release amount of the heat exchanger 20 is affected by the vehicle speed and the load factor of the internal combustion engine 10. Here, in general, when the vehicle is in an uphill state, the load factor of the internal combustion engine 10 is increased and the vehicle speed is reduced as compared to when the vehicle is traveling on flat ground. It often becomes larger than the amount of heat dissipation. That is, by determining whether or not the vehicle is in an uphill state, it is possible to determine whether or not the heat generation amount of the internal combustion engine 10 is greater than the heat dissipation amount of the heat exchanger 20. Therefore, in the heat exchanger system 100a according to the present embodiment, when the detection result of the load factor detection unit 42 is equal to or greater than a predetermined value and the uphill determination unit 58 determines that the vehicle is in the uphill state, the release is performed. The heat amount determination means 52a determines that the heat generation amount of the internal combustion engine 10 is larger than the heat release amount of the heat exchanger 20.

  Next, the operation of the heat exchanger system 100a will be described. FIG. 5 is a flowchart showing an example of the operation of the ECU 50a until the vibration means 30 operates. For example, when the operation of the vehicle on which the heat exchanger system 100a is mounted is started, the load factor detecting means 42 and the vehicle speed detecting means 44 detect the load factor of the internal combustion engine 10 and the vehicle speed of the vehicle, respectively, and send it to the ECU 50a. Tell.

  Next, the heat release amount determination means 52a determines whether or not the load factor is a predetermined value or more (for example, 90% or more) (step S8). When it is determined in step S8 that the load factor is equal to or greater than the predetermined value, the climbing determination unit 58 determines whether or not the vehicle is in the climbing state (step S9). When it is determined in step S9 that the vehicle is in the uphill state, the heat release amount determination unit 52a can determine that the heat generation amount of the internal combustion engine 10 is larger than the heat release amount of the heat exchanger 20. Next, the vibration control unit 56a controls the vibration unit 30 to vibrate the heat exchanger 20 (step S10). Thereafter, the ECU 50a ends the execution of the flowchart.

  On the other hand, when it is not determined in step S8 that the load factor is equal to or greater than the predetermined value, the ECU 50a ends the execution of the flowchart. If it is not determined in step S9 that the vehicle is in an uphill state, the ECU 50a ends the execution of the flowchart.

  According to the heat exchanger system 100a according to the present embodiment, since the vibration means 30 is provided, the formation of the temperature boundary layer around the heat dissipating fins of the heat exchanger 20 is suppressed. Thereby, the heat exchange efficiency of the heat exchanger 20 improves. Further, since the heat radiation amount determination means 52a, the vibration control means 56a, and the climbing slope determination means 58 are provided, when the heat generation amount of the internal combustion engine 10 is larger than the heat radiation amount of the heat exchanger 20, the vibration means 30 is Excited. In this case, since the load of the power source 60 for operating the vibration means 30 is less than when the vibration means 30 is always operated, the fuel efficiency of the vehicle is improved.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

It is a block diagram which shows the whole structure of the heat exchanger system which concerns on 1st Example of this invention. It is a schematic diagram which shows the relationship between the vehicle speed which concerns on Example 1, and the load factor of an internal combustion engine. 3 is a flowchart illustrating an example of an operation of the ECU according to the first embodiment. It is a block diagram which shows the whole structure of the heat exchanger system which concerns on 2nd Example. It is a flowchart which shows an example of operation | movement of ECU which concerns on 2nd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 20 Heat exchanger 30 Excitation means 42 Load factor detection means 44 Vehicle speed detection means 50 ECU
52 Heat release amount determination means 54 Time acquisition means 55 Time determination means 56 Excitation control means 58 Climbing determination means 60 Power supply 70 Transmission 100 Heat exchanger system

Claims (4)

A heat exchanger system used in an internal combustion engine mounted on a vehicle,
A heat exchanger connected to the internal combustion engine;
An excitation means connected to the heat exchanger for exciting the heat exchanger to improve the heat transfer coefficient of the heat exchanger;
A heat release amount determination means for determining whether or not a heat generation amount of the internal combustion engine is larger than a heat release amount of the heat exchanger;
And a vibration control means for controlling the vibration means to vibrate the heat exchanger based on the determination result of the heat radiation amount determination means. Load factor detecting means for detecting a load factor of the internal combustion engine;
Vehicle speed detection means for detecting the speed of the vehicle,
When the detection result of the load factor detection means is equal to or greater than a predetermined value and the detection result of the vehicle speed detection means is equal to or less than a predetermined value, the heat release amount determination means determines the amount of heat generated by the internal combustion engine as the heat exchanger. The heat exchanger system according to claim 1, wherein the heat exchanger system is determined to be larger than the heat release amount. Load factor detecting means for detecting a load factor of the internal combustion engine;
Vehicle speed detection means for detecting the speed of the vehicle;
Time acquisition means for acquiring an elapsed time after the detection result of the vehicle speed detection means becomes a predetermined value or less;
A time determination means for determining whether or not the acquisition result of the time acquisition means is a predetermined time or more,
When the detection result of the load factor detection means is equal to or greater than a predetermined value and the detection result of the vehicle speed detection means is equal to or less than a predetermined value, the heat release amount determination means determines the amount of heat generated by the internal combustion engine as the heat exchanger. Is determined to be greater than
The vibration control means determines that the heat generation amount of the internal combustion engine is larger than the heat dissipation amount of the heat exchanger by the heat dissipation amount determination means, and the acquisition result of the time acquisition means is a predetermined time or more. 2. The heat exchanger system according to claim 1, wherein the vibration exciter is controlled so that the heat exchanger is vibrated when it is determined by the time determination unit. Load factor detecting means for detecting a load factor of the internal combustion engine;
An uphill state determination means for determining whether or not the vehicle is in an uphill state,
The heat dissipation amount determination means determines the amount of heat generated by the internal combustion engine when the detection result of the load factor detection means is equal to or greater than a predetermined value and the climbing state determination means determines that the vehicle is in an uphill state. The heat exchanger system according to claim 1, wherein the heat exchanger system is determined to be larger than a heat release amount of the heat exchanger.

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