JP4704953B2 - Gas engine fuel supply method and gasoline alternative gas fuel injection control device - Google Patents

Description

  The present invention relates to a fuel supply method for a gas engine and a gasoline alternative gas fuel injection control device when an existing gasoline injection system is used in a gasoline alternative gas fuel injection system using gas fuel.

  It is widely known that gas fuel such as LPG, which has characteristics such as composition and vaporization characteristics different from gasoline, is used as a fuel for a spark ignition engine. For example, as a method using LPG, as described in JP-A-6-17709, etc., there is a system in which LPG is in a gas state, adjusted to a predetermined pressure, injected into an intake pipe, and supplied to an engine. As described in Japanese Laid-Open Patent Publication No. 61-138860, etc., there is known a system in which LPG is injected into an intake pipe as a liquid and supplied to an engine. On the other hand, since CNG maintains a gas state more stably than LPG, it has been put into practical use that it is adjusted to a predetermined positive pressure gas, injected into the intake pipe, and supplied to the engine.

  When the engine is equipped with an injection system that injects gas fuel, which has different characteristics from gasoline, from the injector to the intake pipe, an injection amount that gives the optimum fuel supply amount to the new gas engine according to the engine operating condition The system may be designed and constructed from the beginning so as to control the injector using the electronic control device for setting the.

  However, for an existing engine equipped with a gasoline injection system, it is set in the electronic control unit that constitutes the gasoline injection system as an injection amount that gives the optimum fuel supply amount according to the operating state of the engine. For example, as described in Japanese Patent Application Laid-Open No. 2004-108148, a fuel injection amount that gives an air-fuel mixture equivalent to the gasoline injection amount is calculated by a predetermined calculation formula using various data. Existing gasoline injection system by adding an electronic control unit for gasoline alternative gas fuel with extremely simple functions and using injectors with valve diameter and dynamic range suitable for injection for each type of fuel As it is, the gasoline alternative gas fuel injection system is constructed and the engine is adapted to the gas fuel to be used. Rukoto can.

  FIG. 4 is a layout diagram common to a fuel injection system equipped with a conventional fuel supply apparatus including the present invention, and FIG. 5 is a functional block diagram of a control device provided in the fuel injection system shown in FIG. In such a system, the operation state of the engine 1 is detected by the respective sensors 5 to 9, and the electronic control unit 10 as a gasoline injection control device that outputs the gasoline injection signals 11 to ln, and the gasoline injection signal for the gas fuel. And an electronic control unit 11 as a gasoline alternative gas fuel injection control device that outputs the gas fuel injection signals O1 to On to the injectors 2 provided in each cylinder.

  As shown in the waveform diagram of FIG. 2A, the electronic control unit 11 is supplied with a gasoline injection signal ln from the electronic control unit 10, and the start of gasoline injection is switched from OFF to ON in the signal. When the waveform is detected, a predetermined delay time is counted, and then the gas fuel injection signal On is turned from OFF to ON, and the gas fuel injection calculated based on the gasoline injection time X and the engine operating state input from various sensors is performed. At time Y, control for injecting gaseous fuel from the injector 2 is executed.

However, as shown in the waveform diagram of FIG. 2B, the gasoline injection signal ln is turned ON and the next injection cycle starts before the calculated gas injection time Y ′ of the gas fuel injection signal On ends. In the case, the gas fuel injection signal On may end at the gas injection time Y ″ and turn OFF, and the injection time is shortened from the calculated gas injection time Y ′, so that an accurate air-fuel ratio can be obtained. There is a problem that the operating state of the engine is deteriorated without being obtained.
JP-A-6-17709 Japanese Utility Model Publication No. 61-138860 JP 2004-108148 A

The present invention is intended to solve the above-described problems, and a gasoline injection signal output from the gasoline injection control device is received by an existing gasoline injection system having an engine having a gasoline injection control device. Supply for a gas engine implemented in a gasoline alternative gas fuel injection system that includes a gasoline alternative gas fuel injection control device that calculates the amount of fuel injection and a gas fuel injector connected to the gasoline alternative gas fuel injection control device in the method, even when the next injection cycle gasoline injection signal before during injection end of the gas fuel that has been calculated in the gas fuel injection signal is started, to be able to ensure accurate injection time of fuel gas Is an issue.

Accordingly, the present invention provides a gasoline alternative gas fuel injection control device that receives a gasoline injection signal output from the gasoline injection control device and calculates an injection amount of gas fuel in an existing gasoline injection system having a gasoline injection control device. And a fuel supply method for a gas engine implemented in a gasoline alternative gas fuel injection system that includes an additional fuel injector connected to the gasoline alternative gas fuel injection control device,
The gasoline alternative gas fuel injection control apparatus, a shall perform the injection control of fuel gas by using a flag indicating that the solution of the gas fuel injection or non-injection, the flag at the injection start time point of the gasoline injection signal There is initiating an injection of fuel gas is set to the flag indicating that the injection to indicate in a non-injection, the flag indicating that the non-injection when the flag injection termination time of the gas fuel indicating that the injection set, said flag injection start time point of the gasoline injection signal is set to the flag indicating that the non-ejection to indicate during an injection, when the flag in the injection termination time of the gas fuel indicating that the non-injection Even if the next injection cycle of the gasoline injection signal starts before the end of the injection of the gas fuel injection signal, the gas fuel injection is started by setting the flag indicating that the fuel is being injected. It was assumed to ensure the time.

  By adopting such control, the next injection cycle of the gasoline injection signal is started before the gas fuel injection time calculated based on the input gasoline injection signal and the detected engine operating state is over. In this case, the calculated injection time of the gas fuel can be secured, and an appropriate air-fuel ratio can be realized.

  Further, in this fuel supply method of the gas engine, when the gasoline alternative gas fuel injection control device starts the next injection cycle of the gasoline injection signal after the completion of the injection of the gas fuel, the gas fuel from the start of the injection of the gasoline injection signal. The gas fuel injection is started with a predetermined delay time until the start of injection of the injection signal, and this delay is started when the next injection cycle of the gasoline injection signal is started before the end of the injection of the gas fuel. If the gas fuel injection is started as a correction delay time corrected by a predetermined calculation method, fuel injection control with more appropriate injection timing can be realized.

  Further, the corrected delay time is calculated by subtracting the time required from the start of the next injection cycle of the gasoline injection signal to the end of injection of the gas fuel injection signal from the delay time. It will be easy to secure.

  Still further, a program for executing each procedure of the above-described fuel supply method is stored in the storage means, which is arranged in the gasoline alternative gas fuel injection system, and for executing the above-described gas engine fuel supply method. If the gasoline alternative gas fuel injection control device is used, the above-described fuel supply method of the gas engine can be realized reliably and easily.

  According to the present invention, even when the injection cycle of the next gasoline injection signal is started before the end of the injection of the gas fuel calculated in the gas fuel injection signal, an accurate gas fuel injection time can be ensured. It can be done.

  The best mode of the present invention will be described below with reference to the drawings. FIG. 4 is a layout diagram showing a gasoline alternative gas fuel injection system in which an electronic control unit 11 serving as a gasoline alternative gas fuel injection control device and an injector 2 for gas fuel are added to an existing gasoline injection system of an engine. In this embodiment, the gas fuel to be used is a case where LPG or the like that is relatively easy to vaporize is used, and a delivery pipe (not shown) extending from a liquid phase portion of a cylinder filled with gas fuel (not shown) It is connected to a plurality of injectors 2 via a predetermined vaporization means, and the electronic control unit 11 drives and controls each injector 2.

  The present invention is applied when an existing gasoline engine equipped with a gasoline injection system including an electronic control unit 10 as a gasoline injection control device and a gasoline injector (not shown) is modified to a gas engine. is there. The electronic control unit 10 outputs a gasoline injection signal calculated based on the engine operating state detected by the throttle opening sensor 8, the MAP sensor 9, the O2 sensor 6, the water temperature sensor 7, and the crank angle sensor 5, and is not shown. The gasoline injector is opened and closed with a duty cycle corresponding to this drive signal, gasoline of the required flow rate is injected and supplied to the engine, and the spark plug 4 is ignited at a predetermined timing. This is a well-known technique.

  In the present embodiment, an electronic control unit 11 as a gasoline alternative gas fuel injection control device and an injector 2 for gas fuel are added to leave the gasoline injection system, thereby constituting a gasoline alternative gas fuel injection system. In this case, the gasoline injector (not shown) may be removed and replaced with the gas fuel injector 2. The signal line for each cylinder from the electronic control unit 10 to the gasoline injector is replaced with the electronic control unit 11 as it is. The input signal line may be used.

  Here, it is conceivable to use an injector for gasoline for injection of gas fuel. However, since the volumetric flow rate corresponding to the engine required fuel flow rate is larger in each stage than gasoline, in the present invention the gas fuel is used. Therefore, a dedicated gas fuel injector 2 having a valve diameter and a dynamic range capable of proper injection is used.

  The electronic control unit 11 is a general-purpose electronic control unit provided with a CPU, ROM, RAM, input / output interface, etc. (not shown). The hardware is the same as that of a conventional gasoline alternative gas fuel control device. The present invention is characterized in that a program for executing the fuel supply method for a gas engine of the present invention described below is provided.

  As shown in the functional block diagram of FIG. 5, the electronic control unit 11 outputs the gasoline injection signals 11 to 11 which are output according to the engine operating state by the electronic control unit 10 as a gasoline injection control device and input via the gasoline injection signal line. Based on ln, an appropriate injection amount of the gas fuel is calculated by multiplying a predetermined correction coefficient, and the gas fuel injection signals O1 to O2 that give the calculated gas fuel injection amount are obtained via the drive signal line. This is output to the injector 2 for each cylinder, and this function is common to the conventional gasoline alternative gas fuel injection control device.

  In addition to this function, the electronic control unit 11 performs gas fuel injection control using a flag indicating that gas fuel is being injected (1) or non-injecting (2). Even when the injection cycle of the next gasoline injection signal is started before the end of the calculated gas injection, an accurate gas fuel injection time can be secured. That is, the ROM which is the storage means of the electronic control unit 11 stores a program for executing the procedure of the fuel supply method of the gas engine described in detail in the following embodiment. The operation of the electronic control unit 11 that implements the fuel supply method for the gas engine in the present embodiment will be described in detail below using the flowchart of FIG.

  With reference to the flowchart of FIG. 3 and the waveform diagram of FIG. 1 (A), a normal control method will be described first. A gasoline injection signal from the electronic control unit 10 is input to the electronic control unit 11, and detection signals are input from sensors that detect the operating state of the engine. It is determined whether or not an injection start waveform is detected in the input gasoline injection signal ln (A1). If not detected, the process returns to the beginning (return), and if detected, the flag indicating the injection state of the gas fuel is not set. It is determined whether or not the injection is being performed (A2). When the flag indicates non-injection, the flag is set to indicate injection (B1), and the gas injection is started by starting a delay time for starting gas injection calculated in advance (B2).

  Then, it is determined whether or not the end of gas fuel injection has been detected from the waveform in the gas fuel injection signal (A3). If not detected, the process returns to the beginning. If it is detected, it is determined whether or not the flag indicates that the fuel is being injected. Determine (A4). In this case, since the flag indicates that the fuel is being injected, the flag is set to indicate that the fuel is not being injected (B3), and the process returns to the beginning.

  On the other hand, if the next injection cycle of the gasoline injection signal is started before the end of the calculated injection of the gas fuel injection signal, the injection start flag is detected after detecting the start of injection of the gasoline injection signal (A1). It shows the inside (A2). Therefore, a flag indicating that the non-injection is being performed is set (C1).

  When the end of injection of the gas fuel injection signal is detected (A3), the flag indicates non-injection (A4), this is set as a flag indicating injection (C2), and the delay time described above is set. The corrected correction delay time is started and gas fuel injection is started. The delay time is corrected by subtracting the time required from the start of the next injection cycle of the gasoline injection signal to the end of the gas fuel injection calculated from the initial delay time. Thus, it is easy to realize an appropriate gas fuel injection time and injection timing.

  Since the electronic control unit 11 executes each procedure of the fuel supply method of such a gas engine, from the normal control shown in the waveform diagram of FIG. 1A, the waveform diagram of FIG. In the control when the next injection cycle of the gasoline injection signal is started before the end of the calculated injection of the gas fuel injection signal shown in FIG. Y ′ can be secured, and an accurate air-fuel ratio of gas fuel can be realized.

(A), (B) is a wave form diagram which shows the state of control in the gasoline alternative gas fuel injection control apparatus of embodiment of this invention. (A), (B) is a wave form diagram which shows the state of control of the conventional gasoline alternative gas fuel injection control apparatus. The flowchart which shows operation | movement of the fuel-injection control apparatus in the wave form diagram of FIG. 1 (A), (B). The layout of the fuel supply system common to embodiment and the prior art example in this invention. The functional block diagram which shows the flow of the signal in the gasoline injection control apparatus of FIG. 4, and a gasoline alternative gas fuel injection control apparatus.

Explanation of symbols

1 engine, 2 injectors, 10, 11 electronic control unit

Claims (4)

Gasoline alternative gas fuel injection control device for calculating an injection amount of gas fuel by receiving a gasoline injection signal output from the gasoline injection control device in an existing gasoline injection system having a gasoline injection control device, and the gasoline alternative gas In a fuel supply method for a gas engine that is implemented in a gasoline alternative gas fuel injection system with an additional gas fuel injector connected to a fuel injection control device,
The gasoline alternative gas fuel injection control apparatus, a shall perform the injection control of fuel gas by using a flag indicating that the solution of the gas fuel injection or non-injection, the flag at the injection start time point of the gasoline injection signal There is initiating an injection of fuel gas is set to the flag indicating that the injection to indicate in a non-injection, the flag indicating that the non-injection when the flag injection termination time of the gas fuel indicating that the injection set, said flag injection start time point of the gasoline injection signal is set to the flag indicating that the non-ejection to indicate during an injection, when the flag in the injection termination time of the gas fuel indicating that the non-injection Even if the next injection cycle of the gasoline injection signal starts before the end of the injection of the gas fuel injection signal, the gas fuel injection is started by setting the flag indicating that the fuel is being injected. The fuel supply method for a gas engine, characterized in that to secure the time.   The gasoline alternative gas fuel injection control device, from the start of injection of the gasoline injection signal to the start of injection of the gas fuel injection signal, when the next injection cycle of the gasoline injection signal starts after the end of the injection of gas fuel When the injection of gas fuel is started with a predetermined delay time and the next injection cycle of the gasoline injection signal starts before the end of the gas fuel injection, the delay time is corrected by a predetermined calculation method. The fuel supply method for a gas engine according to claim 1, wherein the injection of gas fuel is started as the corrected delay time.   3. The correction delay time is calculated by subtracting, from the delay time, a time required from the start of the next injection cycle of the gasoline injection signal to the end of injection of the gas fuel injection signal. The gas engine fuel supply method described.   The fuel supply for a gas engine according to claim 1, 2 or 3, wherein a program for executing each procedure of the fuel supply method is stored in a storage means while being arranged in the gasoline alternative gas fuel injection system. Gasoline alternative gas fuel injection control device for carrying out the method.

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