JP2006183612A - Start controller of multi-cylinder internal combustion engine using hydrogen fuel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To rapidly start an internal combustion engine while preventing a hydrogen fuel from leaking to the outside through an intake port. <P>SOLUTION: The fuel injection valve 21 of the engine 1 formed, for example, in a rotary piston type is disposed to directly inject the fuel into a combustion chamber, and the fuel injection timing of the fuel injection valve is controlled by a control unit U. When the engine in a stop state is started in response to a start instruction, the engine 1 is driven by a generator 3 used also as a starter motor. When the generator 3 is driven, the fuel is injected into the combustion chamber in a compression stroke when the intake port 27 of the combustion chamber in the compression stroke is closed when the engine is stopped, and the fuel is injected after the intake port 27 is closed when the intake port of the combustion chamber in the compression stroke is opened when the engine is stopped. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a start control device for a multi-cylinder internal combustion engine using hydrogen fuel.

  In order to start an internal combustion engine (engine), when a start command (for example, an ignition switch ON operation) is issued, the motor (starter motor) is driven to crank the internal combustion engine, and the internal combustion engine has a rotational speed. Normally, fuel injection is started in a state where the rotational speed is exceeded.

  On the other hand, in recent internal combustion engines (engines), in particular, internal combustion engines for automobiles, the number of in-cylinder direct injection types in which fuel is directly injected into the cylinder tends to increase. In Patent Document 1, in a direct injection type multi-cylinder internal combustion engine, in order to start the internal combustion engine as quickly as possible, the electric motor is driven in accordance with a start command so as to perform fuel injection from the first cycle at the start. In addition, it is disclosed that fuel injection is performed on a cylinder in the period from the intake stroke to the first half of the compression stroke when the internal combustion engine is stopped. In this way, by performing fuel injection (combustion associated therewith) at an early stage of the drive start time of the electric motor, it is possible to shorten the time required for the internal combustion engine to complete explosion.

JP 2000-120513 A

  By the way, in recent internal combustion engines, various types using hydrogen as a fuel are being proposed due to environmental problems. In an internal combustion engine using hydrogen fuel, since the hydrogen fuel is an extremely light gas and has high flammability, direct in-cylinder injection is used from the viewpoint of preventing leakage of hydrogen fuel to the outside of the combustion chamber through the intake port. It is common to use a method.

  In an internal combustion engine using hydrogen fuel as described above, how to start the engine quickly becomes a problem. In other words, since hydrogen fuel is very light, if the intake port is open when supplied to the combustion chamber, it will leak out through the intake port, and it is necessary to take measures against this point. . Note that when the internal combustion engine is completely exploded and normal operation is being performed, that is, when the internal combustion engine speed is high, even if fuel injection is performed with the intake port slightly open, the intake port However, the fact that hydrogen fuel leaks to the outside through the intake port is not a problem in practice, but the internal combustion engine speed is very low at start-up, so the intake port is open. In this case, if hydrogen fuel is supplied to the combustion chamber, there is a high possibility that the hydrogen fuel leaks to the intake port.

  The present invention has been made in consideration of the above-described circumstances, and its purpose is to prevent the hydrogen fuel from leaking outside through the intake port and to start the internal combustion engine as quickly as possible. An object of the present invention is to provide a start control device for a multi-cylinder internal combustion engine using fuel.

In order to achieve the above object, the following solution is adopted in the present invention. That is, as described in claim 1 in the claims,
Fuel injection means for directly injecting hydrogen fuel into the cylinder, fuel injection control means for controlling the fuel injection timing from the fuel injection means, ignition means for igniting the hydrogen fuel directly injected into the cylinder, and starting A start control device for a multi-cylinder internal combustion engine that uses hydrogen fuel and a starter motor that drives the internal combustion engine in response to a command,
When the motor is driven in response to a start command, the fuel injection control means injects fuel into the combustion chamber in the compression stroke when the intake port for the combustion chamber in the compression stroke is closed when stopped. Sometimes when the intake port for the combustion chamber in the compression stroke is open, fuel injection is performed on the combustion chamber in the compression stroke after the intake port changes from the open state to the closed state.
It is like that.

  According to the above solution, the driving of the internal combustion engine by the electric motor is started in response to the start command. At this time, when the intake port of the combustion chamber in the compression stroke is closed at the time of stoppage, that is, immediately before the start command, fuel injection is performed to the combustion chamber in the compression stroke, and the internal combustion engine is immediately completed. In other words, it will be started. In addition, when the intake port of the combustion chamber in the compression stroke is open at the time of stop, the fuel injection is performed to the combustion chamber in the compression stroke after waiting for the intake port to be closed. Although there is a slight delay in waiting until the intake port is changed from the open state to the closed state, the internal combustion engine is completely explosive. Of course, in any of the above cases, since the intake port is closed when fuel is injected, a situation in which hydrogen fuel leaks outside through the intake port is surely prevented.

A preferred mode based on the above solution is as described in claim 2 and the following claims. That is,
When the combustion chamber is at the end of the compression stroke at the time of stop, the fuel injection control means waits for the combustion chamber of another cylinder in the intake stroke at the time of stop to be in the compression stroke and the intake port to change from the open state to the closed state. Thus, the fuel can be injected into the combustion chamber in the compression stroke (corresponding to claim 2). In this case, even if fuel is injected into the combustion chamber at the end of the compression stroke when stopping, it will be difficult to obtain good combustion because the injected fuel is not sufficiently compressed. The possibility increases. However, in this case, instead of injecting fuel into the combustion chamber at the end of the compression stroke, the combustion chamber of another cylinder that is in the intake stroke at the time of stoppage is eventually in the compression stroke and the intake port is opened by the drive of the motor. Since the fuel injection is performed at the timing when the state is changed to the closed state, the internal combustion engine can be started immediately while reliably obtaining good combustion. Of course, in this case as well, since fuel injection is performed with the intake port closed, it is possible to reliably prevent hydrogen fuel from leaking outside through the intake port.

  The fuel injection control means can perform fuel injection that is performed after the intake port changes from an open state to a closed state when the intake port changes from an open state to a closed state ( Corresponding to claim 3). In this case, by performing fuel injection at an early timing, i.e., when the intake port changes from the open state to the closed state during the closed state, the fuel injection is reliably performed before the optimal ignition timing. This is preferable in order to shorten the time until the complete explosion of the engine while ensuring good combustion.

  According to the present invention, the internal combustion engine can be started quickly while preventing hydrogen fuel from leaking outside through the intake port.

  FIG. 1 shows a drive system of a vehicle to which the present invention is applied. 1 is an engine (internal combustion engine), 2 is a traveling motor, and 3 is a generator that also serves as a starting electric motor (starting motor). The engine 1, the motor 2, and the generator 3 are coupled to a differential gear 6 provided between the left and right drive wheels 5 via a drive mechanism 4 described later. The power generated by the generator 3 is supplied to the battery 8 via the inverter 7. The electric power from the battery 8 is supplied to the running motor 2 through the inverter 7 and also to the generator 3 when used as a starting motor.

  An example of the drive mechanism 4 is shown in FIG. The drive mechanism 4 has a planetary gear mechanism 11. The planetary gear mechanism 11 has a sun gear 12, a ring gear 13, and a plurality of planetary gears 14 meshed with both gears 12 and 13, and each planetary gear 14 is rotatably held by a carrier 15. ing. The engine 1 (output shaft thereof) is connected to the carrier 15 so as to rotate integrally. The generator 3 is connected to the sun gear 12 so as to rotate integrally.

  Two rotation shafts α2 and α3 are arranged in parallel to the rotation shaft of the planetary gear mechanism 11 (the rotation shaft of the sun gear 12) α1. The rotation axis α3 is the rotation axis of the differential gear 6, and its input gear is denoted by reference numeral 16. The large and small gears 17 and 18 are fixed to the rotation shaft α2 so as to rotate integrally. The larger gear 17 is meshed with the ring gear 13 of the planetary gear mechanism 11, and the smaller gear 18 is meshed with the input gear 16. Further, a gear 19 fixed to the rotating shaft 2 a of the motor 2 is meshed with the larger gear 17.

  The driving force of the engine 1 input to the carrier 15 is transmitted to the input gear 16 of the differential gear 6 via the planetary gear 14 (revolving motion thereof), the ring gear 13 and the gears 17 and 18. The driving force of the motor 2 input to the gear 18 is transmitted to the input gear 16 via the gear 17. At the time of braking in which braking force is applied to the drive wheels 5, the driving force (braking force) from the input gear 16 is transmitted to the motor 2 or the engine 1 through a path opposite to the above, and also to the planetary gear. 14 is transmitted to the sun gear 12, that is, the generator 3 (regenerative braking by the power generation of the generator 3). When the engine 1 is stopped, the driving force of the generator 3 input to the sun gear 12 is transmitted from the planetary gear 14 (revolving motion) to the engine 1 via the carrier 15 to drive the engine 1 for starting. Will be given.

  As described above, the drive system shown in FIG. 1 is for a so-called hybrid vehicle. Depending on the traveling state of the vehicle, for example, only the engine 1 is driven, both the engine 1 and the motor 2 are driven, An appropriate drive mode can be used properly among the three drive modes of driving by the motor 2 alone. However, since such a drive mode is not directly related to the present invention, its detailed description is omitted. Of course, the present invention is not limited to a hybrid vehicle, but can be similarly applied to a vehicle driven by only the engine 1. Alternatively, the generator 3 may be dedicated to power generation, while a dedicated starter motor for engine starting may be separately provided.

  The engine 1 is combusted using hydrogen fuel. In the embodiment, the engine 1 is a two-rotor Wankel-type rotary piston engine. That is, two fuel injection valves 21 are provided for each cylinder of the engine 1, and each fuel injection valve 21 is connected to a fuel tank 22 that stores hydrogen fuel. In FIG. 3 showing the details of the engine 1, 23 is a rotor housing, 24 is a rotor, 25 is an output shaft (eccentric shaft), 26 is a spark plug (ignition means), 27 is an intake port, and 28 is an exhaust port. FIG. 3 shows a state in which the fuel injection valve 21 (fuel injection means) faces the combustion chamber in the intake stroke and the intake port 27 is open.

  FIG. 4 shows the relationship between the rotation angle of the output shaft 15 of the engine 1 and the stroke, focusing on the combustion chamber of one cylinder, and the combustion chamber of the other cylinder has only two strokes. The process is shifted. In addition to the eccentric angle, FIG. 4 also shows corresponding angles at ATDC (after top dead center) and BBDC (before bottom dead center), and three combustion chambers are formed per rotor. There are three compression strokes (three expansion strokes, exhaust strokes or intake strokes) per rotation of the rotor 24. In addition, although it becomes 1 cycle at an eccentric angle of 1080 degrees, the compression stroke is in the range of an eccentric angle of 810 degrees to 1080 degrees. In a complete explosion state where the rotational speed of the engine 1 becomes large, a wide range corresponding to 90 degrees after the top dead center during the intake stroke and 180 degrees after the top dead center during the compression stroke ranges from the intake port 27 to the hydrogen. The hydrogen fuel can be injected in a state where the fuel does not leak. On the other hand, at the time of start-up before the complete explosion when the engine speed is small, in order to prevent hydrogen fuel from leaking from the intake port 27, the hydrogen fuel injection possible range is 60 degrees after top dead center. It becomes narrow with the range of 180 degrees after the point.

  The setting of 180 degrees after the top dead center indicating the end of the fuel injectable range is based on the arrangement position of the fuel injection valve 21 shown in FIG. This is because the injection valve 21 is cut off. Therefore, fuel injection can be performed by disposing at least a part of the fuel injection valves 21 on the side more advanced in the rotor rotation direction than in the case of FIG. In the case of a reciprocating engine in which the fuel injection valve always faces the combustion chamber, fuel injection is possible even at the end of the compression stroke.

  In FIG. 1 again, U is a control unit (controller) configured using a microcomputer. This control unit U (fuel injection control means) performs, in particular, drive control of the generator 3 when the engine 1 is started, and fuel injection control from the fuel injection valve 21 (ignition timing control accompanying fuel injection). . The control unit U receives signals from various sensors or switches S1 to S3. The sensor S1 is an ignition switch. The sensors S2 and S3 are rotational position sensors that detect the rotational angle position of the output shaft 25, as will be described later.

  The sensors S2 and S3 for detecting the rotational position are arranged as shown in FIG. 5, for example. That is, in FIG. 5, reference numeral 31 denotes a flywheel that rotates integrally with the output shaft 25, and a total of six recesses (recesses) 32 each having an angle range of 30 degrees are formed on the outer peripheral surface of the flywheel 31 at 30 degrees. It is formed at intervals. The sensors S2 and S3 are disposed with a phase difference of 15 degrees from each other so as to face the outer peripheral surface of the flywheel 31. Each of the sensors S2 and S3 is turned off, for example, at a position that matches the recess 32 (facing position), and is turned on when the sensor is out of the recess 32.

  FIG. 6 shows the output state of the sensors S2 and S3 when the output shaft 25 rotates in a predetermined direction (forward rotation direction). As is apparent from FIG. 6, the rotational angle position of the output shaft 25 can be detected in units of 15 degrees, and the stroke of the combustion chamber can be determined in units of 15 degrees. Become. The rotation angle position of the output shaft 25 is set to a minute angle unit, for example, 1 degree unit by looking at the time between ON and OFF (or OFF to ON) of the sensors S2 and S3 occurring in 15 degree units. Therefore, it becomes possible to detect. In particular, when focusing on the combustion chamber in the compression stroke, it is possible to know whether the intake port 27 is in a closed state or an open state. Further, by looking at the output relationship between the sensors S2 and S3, it is possible to know whether the output shaft 25 is rotating in the forward direction or in the reverse direction. Note that it is possible to know which stroke a certain combustion chamber is in (the absolute angular position of the output shaft 25) only by the outputs of both sensors S2 and S3, but a sensor for detecting the absolute angular position of the output shaft 25 is provided separately. You can also.

  Next, the control contents of the control unit U when the engine is started will be described. First, the rotational angle position of the output shaft 25 when the engine 1 stops is detected (determined) by looking at the outputs of the sensors S2 and S3 from when the engine 1 is in operation until it is stopped. . By knowing the rotational angle position of the output shaft 25, when the engine is stopped (when an engine start command is issued from the engine stop state), the cylinder having the combustion chamber in the compression stroke is determined, and the compression stroke is determined. It is determined whether the intake port 27 of a certain combustion chamber is closed (shown in FIG. 7 when closed) or open (shown in FIG. 8 when open). Further, it is also determined whether or not the combustion chamber in the compression stroke is at the end of the compression stroke. When the combustion chamber of one cylinder is at the end of the compression stroke, the combustion chamber of the other cylinder is at the end of the intake stroke (see FIG. 9). It should be noted that immediately after the start of driving of the engine 1 by the generator 3, the rotational position of the output shaft 25 at the initial stage of rotation (for example, a state rotated by a slight rotational angle of several degrees from the stopped state) is detected by the sensors S2, S3. By doing so, it may be determined whether the cylinder is in the compression stroke or the intake stroke or whether the intake port 27 of the combustion chamber in the compression stroke is in a closed state or an open state.

  When an engine start command is issued, for example, when the ignition switch S4 is turned on, or when switching from a running state using only the motor 2 to a running state in which the engine 1 is also driven (for example, when a high output is requested or a battery is When the power storage capacity of 8 becomes smaller than a predetermined value), a start command is generated. When this start command is generated, the generator 3 is immediately driven to function as a motor for starting the engine. Fuel injection is performed as follows according to the situation of the combustion chamber. First, when the combustion chamber is in a compression stroke in a state that is not at the end of the compression stroke and the intake port 27 is closed (in the range from 60 degrees ATDC to 180 degrees ATDC in FIG. 4), the generator 3 The fuel injection is executed with the start of driving (see FIG. 7).

  Second, when the combustion chamber is in the compression stroke and the intake port 27 is open (in the range of the exhaust angle 810 degrees to ATDC 60 degrees in FIG. 4), the engine 1 is driven by the drive of the generator 3. Thus, fuel injection is performed when the intake port 27 is closed (see FIG. 8). The fuel injection is preferably performed when the intake port 27 changes from the open state to the closed state from the viewpoint of performing the fuel injection as quickly as possible.

  Third, it is when the combustion chamber is at the end of the compression stroke (in FIG. 4, a range from ATDC 180 degrees to eccentric angle 1080 degrees). In this case, even if fuel is injected into the combustion chamber in the compression stroke, a sufficient compression action cannot be obtained, and it becomes difficult to ensure good combustion. At this time, the combustion chamber of one cylinder is at the end of the compression stroke, and the combustion chamber of another cylinder is at the end of the intake stroke (see FIG. 8). Therefore, at this time, when the engine is driven by the generator 3, the combustion chamber of the other cylinder in the intake stroke is in a compression stroke that is not at the end of the compression stroke and the intake port 27 is closed (in FIG. 4, ATDC 60). Fuel injection is performed (see FIG. 8). The fuel injection is preferably performed when the intake port 27 changes from the open state to the closed state from the viewpoint of performing the fuel injection as quickly as possible. Of course, in any of the first to third cases described above, the combustion chamber in which fuel injection has been performed is ignited at a known timing near the end of the compression stroke.

  As described above, when an engine start command is issued, the timing at which the generator 3 starts driving the engine 1 to start the engine 1 (in the case of FIG. 7) or as soon as possible with a slight delay (in FIGS. 8 and 9). In this case, the time required for the engine 1 to be completely exploded can be shortened. In FIG. 10, the case where the start control according to the present invention is performed is indicated by a solid line, and for comparison, the case where the fuel injection is started from the time when the engine 1 is increased to a certain number of revolutions by the generator 3 is indicated by a wavy line. is there. As can be understood from FIG. 10, by executing the start control according to the present invention, the time until the engine 1 is completely exploded is greatly shortened.

  FIG. 11 is a flowchart showing the control contents of the control unit U described above, and this flowchart will be described below. In the following description, P represents a step. First, at P1, it is determined whether or not the engine 1 is currently stopped. For example, when the engine speed detected by the sensors S2 and S3 is 0, the engine 1 is determined to be stopped. If YES in P1, it is determined in P2 whether or not there is an engine start command described above. If NO in the determination of P2 or NO in the determination of P1, it returns to P1 because it is not when the engine 1 is started.

  If the determination in P2 is YES, it is determined in P3 whether or not the intake port 27 of the specific combustion chamber in the compression stroke is closed (at this time, the specific combustion chamber in the compression stroke is Existing cylinders are also determined). When the determination at P3 is YES, it is determined whether or not the specific combustion chamber is at the end of the compression stroke. When the determination at P4 is NO, at P5, driving of the engine 1 by the generator 3 and fuel injection are simultaneously executed (control execution in FIG. 7). When the determination in P4 is YES, the combustion chamber of a cylinder other than the cylinder having the specific combustion chamber at the end of the compression stroke becomes the compression stroke by the engine drive by the generator 3, and the intake port 27 is opened. When the state changes from the closed state to the closed state, fuel injection is executed (control execution in FIG. 9).

  If the determination at P3 is NO, the engine 1 is driven by the generator 3 at P7, and when the intake port 27 of the combustion chamber in the compression stroke is changed from the open state to the closed state by this drive, the fuel is discharged. Injection is executed (execution of control in FIG. 8).

  After P5, P6, and P7, the process proceeds to P8, where it is determined whether or not the engine speed is equal to or higher than a predetermined engine speed (complete explosion engine speed). When the determination at P8 is NO, the process returns to P3, and when the determination at P8 is YES, the mode is shifted to the normal mode (the shift to the fuel injection mode when the complete explosion speed is exceeded).

  Although the embodiment has been described above, the present invention is not limited to the embodiment, and can be appropriately changed within the scope described in the scope of claims. For example, the invention includes the following cases. . The engine 1 may have three or more rotors, and can be similarly applied to a multi-cylinder reciprocating engine. In particular, the multi-cylinder engine is preferably a multi-cylinder engine in which when the combustion chamber of a certain cylinder is at the end of the compression stroke, the combustion chamber of another cylinder is at least in the intake stroke.

  Fuel injection may be performed on the combustion chamber at the end of the compression stroke. In this case, although it becomes difficult in terms of ensuring good combustion, it is advantageous in terms of early startup of the engine speed using combustion. The individual control contents by the control unit U or the processing functions at the steps (step groups) shown in the flowchart can also be expressed with the names of means. The object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

1 is an overall system diagram showing an embodiment of the present invention. The figure which shows the detail of the drive mechanism shown in FIG. The figure which shows the detail of the engine shown in FIG. The figure which shows the change of each stroke when a rotor makes 1 rotation, and a suitable time for fuel injection. The figure which shows the example of arrangement | positioning of the sensor which detects the rotation position of an engine output shaft. The figure which shows the example of an output of the sensor shown in FIG. The figure which shows the time of an engine start command, when a combustion chamber is the compression stroke which is not the end of a compression stroke, and the intake port is a closed state. The figure which shows when a combustion chamber is a compression stroke and the intake port is in an open state at the time of engine start command. The figure which shows the state when the combustion chamber of one cylinder exists in the end of a compression stroke, and the combustion chamber of the other cylinder exists in the end of an intake stroke at the time of engine starting instruction | command. The figure which shows the effect of this invention illustratively. The flowchart which shows the example of control of this invention.

Explanation of symbols

1: Engine 3: Generator (starting motor)
21: Fuel injection valve 22: Fuel tank 25: Output shaft 26: Spark plug 27: Intake port S1: Vehicle speed sensor S2, S3: Rotation position detection sensor of output shaft S4: Ignition switch U: Control unit

Claims (3)

Fuel injection means for directly injecting hydrogen fuel into the cylinder, fuel injection control means for controlling the fuel injection timing from the fuel injection means, ignition means for igniting the hydrogen fuel directly injected into the cylinder, and starting A start control device for a multi-cylinder internal combustion engine that uses hydrogen fuel and a starter motor that drives the internal combustion engine in response to a command,
When the motor is driven in response to a start command, the fuel injection control means injects fuel into the combustion chamber in the compression stroke when the intake port for the combustion chamber in the compression stroke is closed when stopped. Sometimes when the intake port for the combustion chamber in the compression stroke is open, fuel injection is performed on the combustion chamber in the compression stroke after the intake port changes from the open state to the closed state.
A start control device for a multi-cylinder internal combustion engine using hydrogen fuel. In claim 1,
When the combustion chamber is at the end of the compression stroke at the time of stop, the fuel injection control means waits for the combustion chamber of another cylinder in the intake stroke at the time of stop to be in the compression stroke and the intake port to change from the open state to the closed state. Then, fuel is injected into the combustion chamber in the compression stroke.
A start control device for a multi-cylinder internal combustion engine using hydrogen fuel. In claim 1 or claim 2,
The fuel injection control means performs fuel injection after waiting for the intake port to change from an open state to a closed state when the intake port changes from an open state to a closed state. A start control device for a multi-cylinder internal combustion engine.

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