JP2019035373A - Method for controlling fuel supply - Google Patents

Abstract

To allow, in a gas engine having single-point injection, fuel injection to start in accordance with the intake timing of each cylinder in a short time when the engine is started at a low temperature, so that fuel reaches every cylinder and stable engine starting is obtained.SOLUTION: After an ECU 15 recognizes a signal from a crank angle sensor 13 when cranking is made at the time of starting, by the command from the ECU 15, injection is sequentially made from respective injectors 11 to respective cylinders in synchronization with the crank angles set in advance according to the number of the cylinders to start the engine 1, and after the ECU 15 determines the cylinder based on a signal from a cam angle sensor 14, fuel is injected from each injector 11 to each cylinder in accordance wit ignition timing of each cylinder.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel supply control method for a fuel supply device of a single point injection type gas engine that supplies air-fuel mixture from a plurality of injectors provided in one path to a plurality of cylinders.

  Conventionally, when gas fuel such as LPG or CNG is supplied to an engine, the high pressure liquid gas fuel filled in the pressure vessel is adjusted to a low pressure of about atmospheric pressure with a regulator, and this is sent to a mixer or an injector, The gas engine is supplied from the pipeline.

  In the gas engine, a fuel injection port is provided at one location upstream of the throttle valve with respect to the multipoint injection type fuel device provided with injectors for the cylinders of the plurality of cylinders, and one path is provided for the cylinders of the cylinders. There is known a single-point injection type fuel supply device that supplies an air-fuel mixture from a plurality of injectors.

  This single point injection type fuel supply system can be installed in carburetor type engines with minimal design changes, and it is possible to reduce intake resistance and electronically control older engine designs at a relatively low cost. There are benefits.

  Further, in the single point injection, a so-called multi-injection system in which a plurality of injectors are provided and fuel is injected from each injector into each cylinder in accordance with the intake timing of each cylinder in an ECU (Engine Control Unit) using a signal from a cam angle sensor. A fuel supply control method for performing point injection control is known.

  By the way, in a gas engine employing a single point injection provided with a fuel injection port at one location upstream of the throttle valve, fuel injection by the multipoint injection control for supplying fuel from the injector in accordance with the intake timing of each cylinder (hereinafter referred to as “ "Independent injection"), but cranking is started when the engine is started at a low temperature, cylinder discrimination by a signal from the crank angle is over, and independent injection by the multipoint injection control is performed. Until the cylinder discrimination is completed, fuel injection is performed simultaneously from the injection toward each cylinder regardless of the intake timing of each cylinder (hereinafter referred to as “simultaneous injection”).

  For this reason, the fuel that is injected at the time of start-up passes through the fuel pipe, passes through the intake manifold, and is sucked into the cylinder of the engine. However, a large amount of the simultaneously injected fuel is sucked into a specific cylinder, and a specific cylinder undergoes an initial explosion. The other cylinders will not explode due to fuel shortage, and cranking will continue, the cam angle sensor signal will be read by the ECU, cylinder discrimination will be completed, and fuel injection will begin according to the intake timing of each cylinder. There is a problem that it takes time until a stable engine start is obtained after the fuel reaches the cylinders. There is also a problem that unburned exhaust gas increases when the starting time is prolonged.

  The present invention relates to a gas engine having a fuel supply device that performs independent injection by multipoint injection control in which fuel is injected from each injector into each cylinder in accordance with the intake timing of each cylinder in the conventional single point injection. It is an object of the present invention to provide a fuel supply control method in which fuel injection starts in accordance with the intake timing of each cylinder in a short time when the engine is started and fuel is distributed to each cylinder so that stable engine start can be obtained.

  In order to solve the above-described problems, the present invention provides a single-point injection type gas engine fuel supply device that supplies air-fuel mixture from a plurality of injectors provided in one path to a cylinder of a plurality of cylinders. A fuel control method in which fuel is injected into each cylinder from a predetermined injector in accordance with timing, and after the ECU recognizes a signal from a crank angle sensor during cranking at start-up, it responds to the number of cylinders according to a command from the ECU. The engine is started by sequentially injecting each cylinder from a predetermined injector in synchronism with a predetermined crank angle, and the ECU determines the cylinder by the signal from the cam angle sensor, and then matches the intake timing of each cylinder. Change to a fuel control method that injects fuel from each injector into each cylinder And characterized in that.

Schematic which shows preferable embodiment about the fuel supply apparatus used in order to implement this invention. Explanatory drawing of the injection method in embodiment shown in FIG.

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

  FIG. 1 shows an outline of a fuel supply device in a gas engine 1 for carrying out a preferred embodiment of the present invention. The gas engine 1 includes, for example, compressed natural gas CNG, liquefied natural gas, and liquefied petroleum. Gas fuel such as gas may be used as long as it has a multi-cylinder engine. In this embodiment, the cylinder block 2 includes a first cylinder (# 1), a second cylinder (# 2), Four cylinders, the third cylinder (# 3) and the fourth cylinder (# 4), are arranged in series.

  The cylinder block 2 includes an intake manifold 3 to which a mixed gas of fuel and air is supplied from upstream through branch pipes corresponding to the first cylinder (# 1) to the fourth cylinder (# 4), and a branch pipe. An exhaust manifold 4 for discharging exhaust gas downstream is connected via the.

  The intake passage 5 connected to the upstream side of the intake manifold 3 is provided with a throttle valve 9 and an air cleaner 6 on the upstream side, and the fuel stored in the gas tank 10 is supplied with various decompression devices (not shown). ) Is provided with an outlet 8 of the fuel pipe 7 from the injector 11 to be supplied in accordance with the individual intake timing corresponding to the first cylinder (# 1) to the fourth cylinder (# 4) as a predetermined pressure. This is a so-called single point injection method. In the present embodiment, the injector 11 has a plurality of first cylinder injectors # for each cylinder so that fuel can be injected corresponding to the first cylinder (# 1) to the fourth cylinder (# 4). 1 to 4 cylinder injectors # 4 are provided.

  Further, the gas engine 1 according to the present embodiment is provided with a crank angle sensor 13 for detecting a crank angle which is a rotation angle of the crankshaft 12 and a cam angle sensor 14 for detecting a cam angle when the engine is started. An ECU 15 is provided that reads signals detected from the crank angle sensor 13 and the cam angle sensor 14 and transmits an injection signal to the injector 11.

  In the present embodiment, when the engine 1 is started at a low temperature, the crankshaft 12 rotates to start cranking, and the ECU 15 reads a detection signal from a crank angle sensor 13 attached to the crankshaft 12, The fuel injected from the injector 11 is supplied from the fuel pipe 7 to the intake manifold 3 through the throttle valve 9.

  At this time, as shown in FIG. 2, in the conventional example, as shown by a square dotted line at the time of startup, the injector 11 simultaneously injects the first cylinder injector # 1 to the fourth cylinder injector # 4 to generate fuel. As a result, the fuel that was injected at the same time is sucked into a specific cylinder at the intake timing, and a specific cylinder causes an initial explosion, but the other cylinders do not explode due to a shortage of fuel, and the cranking is further reduced. The ECU 15 continuously reads the signal from the cam angle sensor 14 and completes cylinder discrimination. Fuel injection starts in accordance with the intake timing of each cylinder, and fuel is distributed to each cylinder until stable engine start is obtained. There is a problem that the starting time is slightly longer.

  In contrast, in the present embodiment, independent injection is performed in accordance with the intake timings of the first cylinder injector # 1 to the fourth cylinder injector # 4 of the injector 11 at every crank angle of 180 degrees when the engine is started at a low temperature.

  Therefore, the fuel injected from the injector 11 at the time of start passes through the fuel pipe 7 and the intake manifold 3 in accordance with the intake timing of each cylinder of the first cylinder (# 1) to the fourth cylinder (# 4) in the gas engine 1. Will be inhaled.

  Therefore, in the present embodiment, a stable start can be obtained immediately after the start of cranking at the time of start, and a stable startability can be secured continuously even after the cylinder discrimination by reading the signal from the cam angle sensor 14 in the ECU 15 is completed. Is.

  Since the present embodiment is a four-cylinder gas engine, the intake timings of the first cylinder (# 1) to the fourth cylinder (# 4) transmitted to the injector 11 at the time of start are set as crank angles every 180 degrees. Although the injection is performed, for example, the crank angle in the case of 6 cylinders is appropriately selected according to the number of cylinders of the gas engine to be used, such as every 120 degrees, and the injection is performed.

  1 Gas engine, 2 cylinder block, 3 intake manifold, 4 exhaust manifold, 5 intake passage, 6 air cleaner, 7 fuel piping, 8 outlet, 9 throttle valve, 10 gas tank, 11 injector, 12 crankshaft, 13 crank angle sensor, 14 cam angle sensor, 15 ECU

Claims (3)

  In a fuel supply device of a single point injection type gas engine that supplies a mixture from a plurality of injectors provided in one path to a cylinder of a plurality of cylinders, fuel is supplied from a predetermined injector to each cylinder in accordance with the intake timing of each cylinder. A fuel control method for injecting fuel, wherein after ECU recognizes a signal from a crank angle sensor at the time of cranking at start-up, a predetermined injector is synchronized with a crank angle predetermined according to the number of cylinders according to a command from ECU Fuel that injects fuel from a predetermined injector to each cylinder in accordance with the intake timing of each cylinder after the ECU determines the cylinder based on a signal from the cam angle sensor after sequentially injecting into each cylinder A fuel supply control method, characterized in that the control method is changed.   2. The fuel supply control method according to claim 1, wherein when the number of cylinders is 4, fuel is injected from each injector every 180 degrees in synchronization with a crank angle at the time of starting.   2. The fuel supply control method according to claim 1, wherein when the number of cylinders is 6, fuel injection is performed from each injector every 120 degrees in synchronization with a crank angle at the time of starting.

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