JP2015227640A - Control unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control unit capable of ensuring the safe operation of an internal combustion engine even if fuels different in cetane number or a fuel with a low cetane number as the fuel or the internal combustion engine are used.SOLUTION: A control unit controls an injector on the basis of a cetane number of a fuel injected by the injector injecting the fuel for an internal combustion engine type engine. While changing injection timing of the injector step by step (step S4), the control unit controls the injector to inject the fuel of a predetermined quantity (step S5). On the basis of a relation between the injection timing of the fuel burned at reference combustion timing out of these injection timing (step S6) and the reference injection timing, the control unit detects the cetane number (step S9).

Description

  The present invention relates to a control device, and more particularly to a control device that controls a fuel injection valve that injects fuel of an internal combustion engine.

  2. Description of the Related Art Conventionally, an internal combustion engine that is driven by burning diesel fuel such as light oil like a diesel engine is known. Diesel fuel has an ignitability in an internal combustion engine with a cetane number based on cetane.

  Conventional internal combustion engines have been controlled as being driven by cetane number fuels that comply with national standards. For this reason, when a fuel having a cetane number relatively lower than the cetane number conforming to the standard is used as the fuel for the internal combustion engine, the combustion state of the internal combustion engine may deteriorate and misfire may occur. .

  On the other hand, for example, in Patent Document 1, it is determined whether misfire has occurred based on the amount of change in the angular velocity of the crankshaft as the output shaft of the internal combustion engine, and it is determined that misfire has occurred. In some cases, an engine that controls an internal combustion engine with a control amount corrected according to the cetane number of the fuel has been proposed.

JP 2013-015042 A

  However, in the case proposed in Patent Document 1, when a misfire occurs, the internal combustion engine can be controlled with a corrected control amount, but the fuel combustion timing is deviated to such an extent that no misfire occurs. Therefore, the internal combustion engine cannot be controlled with the corrected control amount.

  For this reason, the one proposed in Patent Document 1 may not be able to stably operate the internal combustion engine when a fuel having a different cetane number or a fuel having a low cetane number is used as the fuel for the internal combustion engine. There was a problem.

  Therefore, the present invention has been made to solve such problems, and even when a fuel having a different cetane number or a fuel having a low cetane number is used as the fuel for the internal combustion engine, the internal combustion engine can be stabilized. An object is to provide a control device that can be operated.

  A control device according to the present invention is a control device that controls a fuel injection valve based on a cetane number of fuel injected by a fuel injection valve that injects fuel of an internal combustion engine, and has an injection timing stepped on the fuel injection valve. A cetane number detector that detects a cetane number based on the relationship between the reference injection timing and the injection timing of the fuel burned at the reference combustion timing among the injection timings. It has a configuration.

  The present invention can provide a control device capable of stably operating an internal combustion engine even when a fuel having a different cetane number or a fuel having a low cetane number is used as the fuel for the internal combustion engine.

FIG. 1 is a configuration diagram showing a main part of a vehicle equipped with a control device according to a first embodiment of the present invention. FIG. 2 is a conceptual diagram showing a cetane number map referred to by the control device according to the first embodiment of the present invention. FIG. 3 is a flowchart showing the fuel injection control operation of the control device according to the first embodiment of the present invention. FIG. 4 is a flowchart showing the fuel injection control operation of the control apparatus according to the second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
As shown in FIG. 1, a vehicle 1 equipped with a control device according to an embodiment of the present invention includes an internal combustion engine type engine 2 and an engine control unit (hereinafter simply referred to as “EG-ECU”) 3. It consists of

  The engine 2 includes a four-cycle diesel engine that performs a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, and ignites combustion during the compression stroke and the expansion stroke.

  The engine 2 includes a combustion chamber 4 that combusts fuel, and a fuel injection valve or injector 5 that injects fuel into the combustion chamber 4. The injector 5 is configured to inject fuel into the combustion chamber 4 under the control of the EG-ECU 3. The crankshaft 6 serving as the output shaft of the engine 2 is provided with a crank angle sensor 7 for detecting the rotation angle of the crankshaft 6.

  The intake port of the engine 2 is provided with an intake manifold 13 that forms an intake passage 12 for introducing outside air into the engine 2. The exhaust port of the engine 2 is provided with an exhaust manifold 15 that forms an exhaust passage 14 for exhausting the exhaust of the engine 2. The exhaust passage 14 is provided with an exhaust temperature sensor 16 that detects the temperature of exhaust in the exhaust passage 14.

  The EG-ECU 3 is configured by a computer unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an input port, and an output port. .

  The ROM of the EG-ECU 3 stores a program for causing the computer unit to function as the EG-ECU 3 along with various control constants and various maps. That is, in the EG-ECU 3, the computer unit functions as the EG-ECU 3 when the CPU executes a program stored in the ROM.

  In addition to the crank angle sensor 7 and the exhaust temperature sensor 16, various sensors including a vehicle speed sensor 17 for detecting the vehicle speed and various switches are connected to the input port of the EG-ECU 3. Further, various control objects for controlling the engine 2 such as the injector 5 are connected to the output port of the EG-ECU 3. The EG-ECU 3 controls various control objects based on information obtained from various sensors and various switches.

  In the present embodiment, the EG-ECU 3 controls the injector 5 based on the cetane number of the fuel injected by the injector 5 that injects the fuel of the engine 2.

  Specifically, the EG-ECU 3 controls the injector 5 to inject fuel into the combustion chamber 4 that has become high temperature and high pressure in the compression stroke when the stroke of the engine 2 moves from the compression stroke to the expansion stroke. It has become. Thereby, the fuel injected by the injector 5 ignites and burns, causing the engine 2 to generate power.

  The EG-ECU 3 controls the injector 5 to perform the types of injection such as pilot injection, pre-injection, main injection, after-injection, and post-injection while the engine 2 performs a series of four strokes.

  The EG-ECU 3 performs duty control on the injector 5, thereby injecting a predetermined amount of fuel into the injector 5 for the number of injections corresponding to the operating state of the vehicle 1 and the type of injection, thereby injecting the operating state of the vehicle 1 and the injection. An amount of fuel corresponding to the type of fuel is injected into the injector 5.

  As fuel injected by the injector 5, diesel fuel such as light oil is used. Diesel fuel has an ignitability in the combustion chamber 4 of the engine 2 with a cetane number based on cetane.

  The ROM of the EG-ECU 3 stores both a reference value of the cetane number of the fuel of the engine 2 (hereinafter also referred to as “reference cetane number”) and an optimal combustion timing (hereinafter referred to as “reference combustion timing”) of the fuel having the reference cetane number. And the reference injection timing for burning the reference fuel at the reference combustion timing are stored in advance. Here, the reference combustion timing and the reference injection timing are expressed relative to the rotation angle of the crankshaft 6 that makes two turns while the engine 2 performs a series of four strokes, for example.

  That is, when fuel having a reference cetane number is injected at the reference injection timing, the fuel injected at the reference injection timing burns at the reference combustion timing. When fuel having a cetane number lower than the reference cetane number is injected at the reference injection time, the fuel injected at the reference injection time burns at a time later than the reference combustion time. On the other hand, when fuel having a cetane number higher than the reference cetane number is injected at the reference injection timing, the fuel injected at the reference injection timing burns at an earlier time than the reference combustion timing.

  In the present embodiment, the EG-ECU 3 injects a predetermined amount of fuel while changing the injection timing of the injector 5 in stages, and among these injection timings, the fuel injection timing burned at the reference combustion timing and the reference injection timing The cetane number detection unit 20 that detects the cetane number of the fuel injected into the injector 5 is configured.

  Specifically, the EG-ECU 3 performs the latest timing among the plurality of injection timings in the main injection every time the engine 2 performs a series of four strokes during the fuel cut that causes the injector 5 to stop fuel injection. The injector 5 performs one injection while changing the injection timing step by step between the first and the earliest time.

  The EG-ECU 3 detects the time when the rotational angle speed detected by the crank angle sensor 7 fluctuates from a predetermined fluctuation amount as the combustion time. Here, the predetermined fluctuation amount is an adaptive value determined experimentally in advance.

  The EG-ECU 3 selects a combustion timing that coincides with the reference combustion timing from among the detected combustion timings (hereinafter also referred to as “detected combustion timing”). Here, the EG-ECU 3 may select a combustion timing that coincides with the reference combustion timing with a predetermined tolerance among the detected combustion timings. Here, the predetermined allowable error is a conforming value.

  Further, the EG-ECU 3 specifies the injection timing of the fuel burned at the selected combustion timing, and based on the relationship between the specified injection timing (hereinafter also referred to as “specific injection timing”) and the reference injection timing, The value is to be detected.

  Specifically, the EG-ECU 3 calculates a combustion delay time obtained by subtracting the specific injection timing from the reference injection timing. The ROM of the EG-ECU 3 stores a cetane number map in which a cetane number is associated with the combustion delay time as shown in FIG. The EG-ECU 3 detects a cetane number (hereinafter also referred to as “detected cetane number”) corresponding to the combustion delay time in the cetane number map.

  The EG-ECU 3 executes correction control for controlling the injector 5 based on the detected cetane number. Specifically, in the correction control, the EG-ECU 3 determines the fuel injection amount and the injection timing of the injector 5 according to the difference between the detected cetane number and the reference cetane number (hereinafter also referred to as “cetane number difference”). At least one of them is corrected.

  For example, when the EG-ECU 3 corrects the fuel injection amount of the injector 5, if the detected cetane number is lower than the reference cetane number, the EG-ECU 3 performs fuel injection in various types of injection including the main injection. The injector 5 is controlled so as to increase the amount in accordance with the cetane number difference.

  When the EG-ECU 3 corrects the fuel injection amount of the injector 5, the EG-ECU 3 performs fuel injection in various types of injection including the main injection if the detected cetane number is higher than the reference cetane number. The injector 5 is controlled so as to reduce the amount in accordance with the cetane number difference.

  In addition, when the EG-ECU 3 corrects the fuel injection timing of the injector 5, the EG-ECU 3 performs fuel injection in various types of injection including the main injection if the detected cetane number is lower than the reference cetane number. The injector 5 is controlled so as to advance the timing according to the cetane number difference.

  When the EG-ECU 3 corrects the fuel injection timing of the injector 5, the EG-ECU 3 performs fuel injection in various types of injection including the main injection if the detected cetane number is higher than the reference cetane number. The injector 5 is controlled so as to delay the timing according to the cetane number difference.

  The fuel injection control operation by the control apparatus according to the first embodiment of the present invention configured as described above will be described with reference to FIG. The fuel injection control operation described below is repeatedly executed every time the engine 2 performs a series of four strokes.

  First, the EG-ECU 3 determines whether or not the vehicle 1 is traveling based on the vehicle speed detected by the vehicle speed sensor 17 (step S1). Here, if it is determined that the vehicle 1 is not traveling, the EG-ECU 3 ends the fuel injection control operation.

  On the other hand, when it is determined that the vehicle 1 is traveling, the EG-ECU 3 determines whether or not the fuel is being cut (step S2). If it is determined that the fuel is not being cut, the EG-ECU 3 ends the fuel injection control operation.

  On the other hand, when it is determined that the fuel is being cut, the EG-ECU 3 determines whether or not the engine 2 is malfunctioning (step S3). Here, the EG-ECU 3 confirms that the fuel cut is not being executed by detecting a failure of the engine 2 based on detection results of various sensors provided in the engine 2.

  If it is determined in step S3 that the engine 2 is malfunctioning, the EG-ECU 3 ends the fuel injection control operation. On the other hand, when it is determined that the engine 2 is not in failure, the EG-ECU 3 sets information representing the fuel injection timing in the fuel injection control operation in the RAM (step S4).

  In the present embodiment, the EG-ECU 3 changes the injection timing step by step from the latest timing to the earliest timing among the multiple injection timings in the main injection. May be arbitrarily changed depending on the design.

  Next, the EG-ECU 3 causes the injector 5 to inject a predetermined amount of fuel (step S5). Next, the EG-ECU 3 detects the combustion timing based on the fluctuation amount of the rotational angle speed detected by the crank angle sensor 7 (step S6).

  Next, the EG-ECU 3 determines whether or not the combustion timing detected in step S6 matches the reference combustion timing with a predetermined allowable error (step S7). Here, when it is determined that the detected combustion timing does not coincide with the reference combustion timing with a predetermined allowable error, the EG-ECU 3 returns the fuel injection control operation to step S4.

  On the other hand, when it is determined that the detected combustion timing coincides with the reference combustion timing with a predetermined tolerance, the EG-ECU 3 calculates the combustion delay time (step S8). Here, the EG-ECU 3 calculates the combustion delay time by subtracting the specific injection timing from the reference injection timing. The specific injection timing is represented by information set in the RAM in step S4.

  Next, the EG-ECU 3 detects a cetane number corresponding to the combustion delay time (step S9). Here, the EG-ECU 3 refers to the cetane number map stored in the ROM, and detects the cetane number corresponding to the combustion delay time in the cetane number map.

  Next, the EG-ECU 3 executes correction control for correcting at least one of the fuel injection timing and the injection amount by the injector 5 based on the cetane number detected in step S9 (step S10), and ends the fuel injection control operation. .

  In step S7, the EG-ECU 3 does not match the detected combustion timing with the reference combustion timing with a predetermined tolerance, and the injection timing represented by the information set in the RAM in step S4 is a plurality of times in the main injection. The fuel injection control operation may be terminated when the earliest time is reached.

  Further, the EG-ECU 3 performs the fuel injection control operation when the detected combustion timing does not coincide with the reference combustion timing with a predetermined allowable error in step S7 and the process of step S7 is executed a predetermined number of times or more. May be terminated.

  As described above, in the present embodiment, a predetermined amount of fuel is injected while the injection timing of the injector 5 is changed stepwise, and the injection timing of the fuel burned at the reference combustion timing among these injection timings, the reference injection Since the cetane number of the fuel of the engine 2 is detected based on the relationship with the time, even when a fuel having a different cetane number or a fuel having a low cetane number is used as the fuel of the engine 2, the engine 2 can be stabilized. Can be driven.

  In the present embodiment, the cetane number can be detected based on the combustion delay time corresponding to the relationship between the specific injection timing and the reference injection timing.

  Note that, in the present embodiment, the EG-ECU 3 causes the injection timing of the main injection to be performed every time the engine 2 performs a series of four strokes during the fuel cut that causes the injector 5 to stop fuel injection. It has been described that the injector 5 performs one injection while changing the injection timing stepwise between the latest time and the earliest time.

  However, each time the engine 2 performs a series of four strokes during the fuel cut, the EG-ECU 3 steps the injection timing between the latest timing and the earliest timing among the multiple injection timings in the main injection. It is also possible to cause the injector 5 to perform a plurality of injections while changing the speed.

  Further, the EG-ECU 3 steps the injection timing between the latest timing and the earliest timing among the plurality of injection timings in the main injection every time the engine 2 performs a series of four strokes during the fuel cut. It is also possible to cause the injector 5 to perform an injection corresponding to a predetermined set amount while changing the speed.

(Second Embodiment)
In the present embodiment, differences from the first embodiment of the present invention will be described. The hardware configuration of the present embodiment is the same as that of the first embodiment of the present invention shown in FIG.

  The EG-ECU 3 in the present embodiment is different from the EG-ECU 3 in the first embodiment of the present invention in the program stored in the ROM.

  Specifically, in the first embodiment of the present invention, the EG-ECU 3 injects a predetermined amount of fuel while changing the injection timing of the injector 5 stepwise, and at the reference combustion timing among these injection timings. The cetane number of the fuel injected into the injector 5 is detected based on the relationship between the injection timing of the burned fuel and the reference injection timing.

  On the other hand, in the ROM of the EG-ECU 3 in the present embodiment, the exhaust temperature of the engine 2 when a predetermined amount of fuel having the reference cetane number burns at the reference combustion timing (instead of information indicating the reference combustion timing) Hereinafter, information indicating “reference exhaust temperature”) is stored in advance.

  That is, when a predetermined amount of the reference cetane number fuel burns at the reference combustion timing, the exhaust temperature of the engine 2 becomes the reference exhaust temperature, and the predetermined amount of reference cetane number fuel deviates from the reference combustion timing. In the case of combustion, the exhaust temperature of the engine 2 becomes lower than the reference exhaust temperature.

  In the present embodiment, the EG-ECU 3 injects a predetermined amount of fuel while changing the injection timing of the injector 5 in stages, and the exhaust temperature and reference exhaust when the injected fuel in these injection timings burns. Based on the relationship with the temperature, the cetane number of the fuel injected into the injector 5 is detected.

  Specifically, the EG-ECU 3 performs injection between the latest timing and the earliest timing among the plurality of injection timings in the main injection every time the engine 2 performs a series of four strokes during the fuel cut. The injector 5 is made to perform one injection while changing the timing stepwise.

  When the fuel is injected into the injector 5, the EG-ECU 3 detects the highest exhaust temperature detected by the exhaust temperature sensor 16 as the exhaust temperature when the fuel injected into the injector 5 burns. Yes.

  The EG-ECU 3 selects an exhaust gas temperature that matches the reference exhaust gas temperature from the detected exhaust gas temperature (hereinafter also referred to as “detected exhaust gas temperature”). Here, the EG-ECU 3 may select an exhaust gas temperature that coincides with the reference exhaust gas temperature with a predetermined tolerance among the detected exhaust gas temperatures. Here, the predetermined allowable error is a conforming value.

  Further, the EG-ECU 3 specifies the injection timing of the fuel burned at the selected exhaust temperature, and detects the cetane number based on the relationship between the specified injection timing, that is, the specific injection timing, and the reference injection timing. ing.

  Specifically, like the EG-ECU 3 according to the first embodiment of the present invention, the EG-ECU 3 calculates a combustion delay time obtained by subtracting the specific injection timing from the reference injection timing, and sets the calculated combustion delay time. The corresponding cetane number, that is, the detected cetane number is detected in the cetane number map (see FIG. 2). Further, the EG-ECU 3 executes correction control.

  A fuel injection control operation performed by the control device according to the second embodiment of the present invention configured as described above will be described with reference to FIG. The fuel injection control operation described below is repeatedly executed every time the engine 2 performs a series of four strokes.

  First, the EG-ECU 3 determines whether or not the vehicle 1 is traveling based on the vehicle speed detected by the vehicle speed sensor 17 (step S21). Here, if it is determined that the vehicle 1 is not traveling, the EG-ECU 3 ends the fuel injection control operation.

  On the other hand, when it is determined that the vehicle 1 is traveling, the EG-ECU 3 determines whether or not the fuel is being cut (step S22). If it is determined that the fuel is not being cut, the EG-ECU 3 ends the fuel injection control operation.

  On the other hand, when it is determined that the fuel is being cut, the EG-ECU 3 determines whether or not the engine 2 is malfunctioning (step S23). Here, the EG-ECU 3 confirms that the fuel cut is not being executed by detecting a failure of the engine 2 based on detection results of various sensors provided in the engine 2.

  If it is determined in step S23 that the engine 2 is malfunctioning, the EG-ECU 3 ends the fuel injection control operation. On the other hand, when determining that the engine 2 is not in failure, the EG-ECU 3 sets information representing the fuel injection timing in the fuel injection control operation in the RAM (step S24).

  In the present embodiment, the EG-ECU 3 changes the injection timing step by step from the latest timing to the earliest timing among the multiple injection timings in the main injection. May be arbitrarily changed depending on the design.

  Next, the EG-ECU 3 causes the injector 5 to inject a predetermined amount of fuel (step S25). Next, the EG-ECU 3 detects the highest exhaust temperature detected by the exhaust temperature sensor 16 (step S26).

  Next, the EG-ECU 3 determines whether or not the exhaust temperature detected in step S26 matches the reference exhaust temperature with a predetermined tolerance (step S27). Here, if it is determined that the detected exhaust gas temperature does not coincide with the reference exhaust gas temperature with a predetermined allowable error, the EG-ECU 3 returns the fuel injection control operation to step S24.

  On the other hand, when it is determined that the detected exhaust temperature matches the reference exhaust temperature with a predetermined allowable error, the EG-ECU 3 calculates a combustion delay time (step S28). Here, the EG-ECU 3 calculates the combustion delay time by subtracting the specific injection timing from the reference injection timing. The specific injection timing is represented by information set in the RAM in step S24.

  Next, the EG-ECU 3 detects a cetane number corresponding to the combustion delay time (step S29). Here, the EG-ECU 3 refers to the cetane number map stored in the ROM, and detects the cetane number corresponding to the combustion delay time in the cetane number map.

  Next, the EG-ECU 3 executes correction control for correcting at least one of the fuel injection timing and the injection amount by the injector 5 based on the cetane number detected in step S29 (step S30), and ends the fuel injection control operation. .

  In step S27, the EG-ECU 3 determines that the detected exhaust temperature does not coincide with the reference exhaust temperature even with a predetermined tolerance, and the injection timing represented by the information set in the RAM in step S24 is a plurality of times in the main injection. The fuel injection control operation may be terminated when the earliest time is reached.

  In step S27, the EG-ECU 3 performs the fuel injection control operation when the detected exhaust gas temperature does not coincide with the reference exhaust gas temperature with a predetermined allowable error and the process of step S27 is executed a predetermined number of times or more. May be terminated.

  As described above, in the present embodiment, a predetermined amount of fuel is injected while the injection timing of the injector 5 is changed stepwise, and the exhaust temperature when the fuel injected into the injector 5 in the injection timing burns. Since the cetane number of the fuel of the engine 2 is detected based on the relationship with the reference exhaust gas temperature, even if a fuel having a different cetane number or a fuel having a low cetane number is used as the fuel of the engine 2, 2 can be operated stably.

  In the present embodiment, the cetane number can be detected based on the combustion delay time corresponding to the relationship between the specific injection timing and the reference injection timing.

  In the first embodiment of the present invention, a combustion timing that coincides with the reference combustion timing is selected from the detected combustion timings, and an injection timing of fuel burned at the selected combustion timing (hereinafter referred to as “first specific injection”). An example of specifying the "time") has been described.

  In the second embodiment of the present invention, an exhaust gas temperature that matches the reference exhaust gas temperature is selected from the detected exhaust gas temperatures, and an injection timing of fuel burned at the selected exhaust gas temperature (hereinafter referred to as “second specific injection”). An example of specifying the "time") has been described.

  In the present invention, the first specific injection timing may be verified based on the second specific injection timing, or the second specific injection timing may be verified based on the first specific injection timing. With this configuration, the control device according to the present invention can detect the cetane number of the fuel injected by the injector 5 more accurately.

  In the invention, the cetane number may be detected based on the firing delay time corresponding to at least one of the first specific injection timing and the second specific injection timing. With this configuration, the control device according to the present invention can detect the cetane number of the fuel injected by the injector 5 even if detection signals cannot be obtained from the crank angle sensor 7 and the exhaust temperature sensor 16. it can.

  Although the embodiments of the present invention have been disclosed above, it is obvious that those skilled in the art can make modifications without departing from the scope of the present invention. All such modifications and equivalents are intended to be included in the claims recited in the claims.

1 vehicle 2 engine (internal combustion engine)
3 EG-ECU
5 Injector (fuel injection valve)
20 Cetane number detector

Claims (5)

A control device for controlling the fuel injection valve based on a cetane number of fuel injected by a fuel injection valve for injecting fuel of an internal combustion engine,
A predetermined amount of fuel is injected while gradually changing the injection timing of the fuel injection valve. A control device including a cetane number detection unit for detecting a cetane number.   The cetane number detection unit identifies an injection timing at which an exhaust temperature when the injected fuel combusts becomes a reference exhaust temperature among the injection timings, and verifies the injection timing of the fuel burned at the reference combustion timing The control device according to claim 1.   The control device according to claim 1, wherein the cetane number detection unit detects the cetane number based on a combustion delay time corresponding to a relationship between the injection timing and the reference injection timing.   The cetane number detection unit includes a relationship between the first specific injection timing of the fuel burned at the reference combustion timing among the injection timing and the reference injection timing, and exhaust when the injected fuel of the injection timing burns. 2. The control device according to claim 1, wherein the cetane number is detected based on at least one of a relationship between a second specific injection timing of the fuel whose temperature becomes a reference exhaust temperature and the reference injection timing. The cetane number detection unit has a combustion delay time according to at least one of a relationship between the first specific injection timing and the reference injection timing and a relationship between the second specific injection timing and the reference injection timing. The control device according to claim 4, wherein the cetane number is detected based on the cetane number.

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