JP2007205256A - Fuel supply method and fuel supply device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize fuel supply quantity and injection timing in a gasoline-replacing fuel injection system using a gasoline injection system. <P>SOLUTION: In a gasoline-replacing fuel injection system adding an injector 2 for non-gasoline fuel and an electronic control unit 11 for non-gasoline fuel injection control receiving gasoline injection signal output according to engine operation condition and calculating injection quantity of non-gasoline fuel on a gasoline injection system existing on an engine provided with an electronic control unit 10 for gasoline injection control and various sensors 5-9 detecting engine operation conditions, the electronic control unit 11 directly calculates injection quantity of non-gasoline fuel based on data of an engine operation condition without using gasoline injection signal, outputs fuel injection signal to the injector 2 and executes independent control when the engine gets in the predetermined operation condition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an engine fuel supply method and a fuel supply apparatus in which an existing gasoline injection system is used in a gasoline alternative fuel injection system using non-gasoline fuel.

  It is widely known that a non-gasoline fuel such as LPG having characteristics such as composition and vaporization characteristics different from gasoline is used as a fuel for a spark ignition engine. For example, instead of the conventionally known method in which vaporized gas adjusted to a pressure of about atmospheric pressure using a regulator (vaporizer) and a mixer is sucked into the intake pipe and supplied to the engine, As described in Japanese Laid-Open Patent Application No. 6-17709 and the like, a system in which LPG that is in a gas state and adjusted to a predetermined pressure is injected into the intake pipe and supplied to the engine, Japanese Utility Model Publication No. 61-138860, and the like As described in the above, there is provided a system in which LPG is injected into an intake pipe in a liquid state 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 installing an injection system that injects non-gasoline fuel such as liquefied gas fuel, which has different characteristics from gasoline, into the intake pipe from the injector, the optimal fuel supply for new engines depends on the engine operating conditions The system may be designed and constructed from the beginning to control the injector using an electronic control device that sets the amount of injection that gives the quantity.

  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. An existing gasoline injection system can be installed by adding an electronic control unit for non-gasoline fuel with extremely simple functions and using an injector with a valve diameter and dynamic range suitable for injection for each type of fuel. Build a gasoline alternative fuel injection system that uses non-gasoline fuel as it is, and engine that corresponds to the fuel used It can be modified to. For details of the method, supply positive pressure to the existing gasoline injection system.

  Referring to FIG. 1, which is a layout diagram common to a conventional gasoline alternative fuel injection system and a gasoline alternative fuel injection system of the present invention to be described later, such a gasoline alternative fuel injection system has an operation state of an engine 1 as a sensor. Electronic control unit 10 as a gasoline injection control device that detects gasoline injection signals 11 to ln and outputs gasoline injection signals 11 to ln, and corrects and applies the gasoline injection signal for non-gasoline fuel to produce fuel injection signals O1 to On. And an electronic control unit 11 that is a non-gasoline fuel injection control device that outputs to the injector 2.

However, in certain engine operating situations that are different from normal operation, such as during cold start, when the gasoline injection amount is detected from the gasoline injection signal and the injection amount of gasoline alternative fuel is determined by the procedure described above, the characteristics of both fuels Due to the difference, there are cases where it is difficult to obtain an optimal injection amount of alternative fuel for gasoline, and there is a problem that engine operability is deteriorated. Further, it is preferable that the fuel injection is finished before the start of the intake stroke. However, as described above, the injection timing is detected by correcting the fuel injection amount to the gasoline alternative fuel output after detecting the gasoline injection signal. If there is a delay, there is a concern that a problem such as a decrease in the engine output may be caused depending on the operating state of the engine.
JP-A-6-17709 Japanese Utility Model Publication No. 61-138860 JP 2004-108148 A

  The present invention is intended to solve the above-mentioned problems, and in a gasoline alternative fuel injection system using a gasoline injection system, the non-gasoline fuel electronic control device detects the injection amount of non-gasoline fuel from the gasoline injection signal. It is an object of the present invention to achieve optimization of the fuel supply amount and the injection timing in a specific operation situation where it is difficult to obtain an optimal fuel injection amount even when calculating the above or a slight deviation in injection timing leads to engine trouble.

  Therefore, the present invention outputs the gasoline injection control device to the existing gasoline injection control system in which the gasoline injection control device and the engine operation state detection means are arranged in response to the output signal of the engine operation state detection means. A non-gasoline fuel injection control device that calculates the injection amount of non-gasoline fuel by receiving a gasoline injection signal via a gasoline injection signal line arranged for each cylinder, and a non-gasoline fuel injector connected thereto are added. An engine fuel supply method implemented in a gasoline alternative fuel injection system, wherein a non-gasoline fuel injection control device generates a gasoline injection signal when a predetermined predetermined engine operating state is reached. Non-gasoline fuel injection amount is calculated directly based on the data detected by the engine operating state detection means without using it. And it outputs a fuel injection signal to the emission fuel injector and shall perform a single control.

  This makes it difficult to achieve the target fuel injection amount for non-gasoline fuel, which has a temperature characteristic that differs greatly from gasoline when correcting from a gasoline injection signal to a non-gasoline fuel injection signal, for example, at low temperature start. In certain operating situations, such as when a slight delay in injection timing is likely to lead to engine trouble, for example, a basic injection quantity pattern specific to non-gasoline fuel corresponding to the operating situation is stored in advance, and this is stored in the engine. By correcting according to the operating state, it becomes possible to determine and inject an appropriate fuel injection amount regardless of the gasoline injection signal, and in addition, the injection timing does not delay the engine cycle and causes engine troubles such as output reduction. There will be less worry.

  Moreover, if this single control is executed when the non-gasoline fuel injection control device determines that it is at the time of low-temperature start, good low-temperature startability can be obtained even for non-gasoline fuel having a temperature characteristic greatly different from that of gasoline. It will be easy to demonstrate.

  Further, an electronic control device for non-gasoline fuel and a non-gasoline fuel injector provided with storage means storing a program for executing the above-described engine fuel supply method are arranged in an existing gasoline injection system of the engine. If the fuel supply device for an engine that implements the fuel supply method of the engine is configured as a gasoline alternative fuel supply system, the above-described non-gasoline fuel supply method can be reliably realized at a low cost. .

  Even if the non-gasoline fuel electronic control unit calculates the non-gasoline fuel injection amount from the gasoline injection signal, it is difficult to achieve the optimum fuel injection amount or a slight deviation in the injection timing is likely to lead to engine trouble. According to the present invention, the non-gasoline fuel injection amount is directly determined in accordance with the engine operating state detected by the non-gasoline fuel injection control device regardless of the gasoline injection signal. The fuel supply amount and the injection timing can be optimized.

  The best mode of the present invention will be described below with reference to the drawings. FIG. 1 shows a gasoline alternative fuel injection system according to the present invention, in which an electronic control unit 11 as an injection control device for non-gasoline fuel and an injector 2 for non-gasoline fuel are added to an existing gasoline injection system of an engine. FIG. This embodiment is a case where the non-gasoline fuel to be used is a liquefied gas fuel such as LPG, which is relatively easy to vaporize, and a delivery pipe (not shown) extending from a liquid phase portion of a cylinder filled with the non-gasoline fuel (not shown). These are connected to a plurality of injectors 2 via predetermined vaporization means, and the electronic control unit 11 drives and controls each of the injectors 2.

  In the present invention, when an existing gasoline engine equipped with a gasoline injection system equipped with an electronic control unit 10 that is an injection control device for gasoline and a gasoline injector (not shown) is modified to a non-gasoline fuel use engine. Applicable. The electronic control unit 10 serving as a gasoline injection control device calculates the gasoline injection 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. A signal is output, an unillustrated gasoline injector is opened / closed at 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 an injection control device for non-gasoline fuel and an injector 2 for non-gasoline fuel are added to leave the gasoline injection system, thereby constituting a gasoline alternative fuel injection system. . In this case, a gasoline injector (not shown) may be removed and replaced with a non-gasoline fuel injector 2, and 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. Thus, an input signal line may be used.

  Here, it is conceivable to use an injector for gasoline for injection of non-gasoline fuel. However, in the present invention, the volume flow rate corresponding to the engine required fuel flow rate is larger for each stage of non-gasoline fuel than gasoline. It was decided to use a dedicated non-gasoline fuel injector 2 having a valve diameter and a dynamic range that enable proper injection of non-gasoline fuel.

  The electronic control unit 11 is a general-purpose electronic control unit having a CPU, ROM, RAM, input / output interface, etc. (not shown), and a program for executing a non-gasoline fuel supply method for gasoline replacement described below in the ROM. It is characterized by having.

  As shown in the functional block diagram of FIG. 4, the electronic control unit 11 outputs a gasoline injection signal 11 that is output according to the engine operating state by the electronic control unit 10 that is a gasoline injection control device and is input via a gasoline injection signal line. Based on ˜ln, an appropriate injection amount of the non-gasoline fuel is calculated by multiplying a predetermined correction coefficient, and the non-gasoline fuel injection signals O1 to O2 that give the calculated non-gasoline fuel injection amount are used as drive signals. This is output to the injector 2 for each cylinder via a line, and this function is common to the non-gasoline fuel injection control device in the conventional gasoline alternative fuel injection system.

  In addition to this function, as shown in the functional block diagram of FIG. 2, the electronic control unit 11 independently determines the injection amount of non-gasoline fuel independently of the gasoline injection signal in a predetermined operating state of the engine. It is characterized in that a single control is executed in which a fuel injection signal is output to each injector 2.

  That is, in the ROM as the storage means of the electronic control unit 11, for example, when the gasoline injection signal is corrected and the non-gasoline fuel injection signal is generated at the time of low temperature start or high output operation, appropriate fuel injection control is achieved. If the basic injection pattern is stored in advance for each specific operating situation, it is determined based on the operating state of the engine at that time. A program for executing an independent control that does not depend on a gasoline injection signal, characterized in that an optimal fuel injection amount is determined by the calculation method of (2) is stored.

  The operation of the electronic control unit 11 disposed in the fuel supply apparatus for the engine that implements the non-gasoline fuel supply method for the engine in the present embodiment will be described in detail below using the flowchart of FIG.

  The electronic control unit 11 detects a detection signal from each sensor that detects the operating state of the engine (A1), and determines whether or not the operating state of the engine is a state suitable for predetermined single control (A2). If the situation is not suitable, the process shifts to non-gasoline fuel injection control by a gasoline injection signal. That is, after detecting the gasoline injection signal (B1), each sensor signal is detected (B2), the non-gasoline fuel injection amount is calculated by a predetermined calculation method (B3), and the non-gasoline injection signal is calculated. It is assumed that the data is output to each injector 2 (B4), and thereafter, the process returns to the beginning and (A1) and subsequent steps are repeated.

  On the other hand, when it is determined that the situation is suitable for independent control, the engine operating state is detected from each sensor signal (A3). For example, if it is a cold start, a predetermined cold start fuel injection pattern The non-gasoline fuel injection amount is calculated by a predetermined calculation method based on the detected engine operating state (A4). In addition, what is necessary is just to determine whether the data detected with the water temperature sensor 7 and the crank angle sensor 5 are settled in the data range as the time of predetermined cold start etc. as a judgment material at the time of cold start.

  Then, an injection signal is output at an appropriate timing for each cylinder in accordance with the detected rotation period of the engine (A5), and thereafter, the process returns to the beginning and (A1) and subsequent steps are repeated. That is, in such a special operating situation, there are many cases where the necessary fuel injection amount and the period thereof are empirically known depending on the type of fuel, so the fuel injection pattern in that situation is determined in advance. For this reason, the fuel injection amount can be determined with only a slight correction in accordance with the operating condition of the engine, and it becomes easy to obtain an appropriate fuel supply amount.

  Further, by adopting such a procedure, the output of the non-gasoline fuel injection signal is not delayed from the intake timing of each cylinder. In the fuel supply method for the engine described in this flowchart, the determination as to whether or not the situation is suitable for single control is repeated continuously. However, the output of the non-gasoline fuel injection signal is output a predetermined number of times or for a predetermined time. If the operation status of the single control does not occur again between the start and stop of the engine as in the cold start, a predetermined time after the single control is started. Alternatively, after a predetermined number of engine rotation cycles have elapsed, the control may be shifted to non-gasoline injection control using a gasoline injection signal.

  As described above, the engine fuel supply method and apparatus according to the present embodiment accurately determines whether or not the non-gasoline fuel control device is in an operating state of the engine suitable for single control. In the case of control, a fuel injection signal is generated based on the operating state of the engine, so that fuel can be injected without delaying the cycle of each cylinder, and fuel that matches the fuel supply amount required by the engine The injection amount can be calculated. Therefore, optimization of the supply amount of non-gasoline fuel and the injection timing can be realized.

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 non-gasoline fuel supply apparatus of embodiment in this invention. The flowchart which shows operation | movement of the non-gasoline fuel injection control apparatus in the non-gasoline fuel supply apparatus of FIG. The functional block diagram which shows the flow of the signal in the non-gasoline fuel supply apparatus of a prior art example.

Explanation of symbols

1 engine, 2 injectors, 5 crank angle sensor, 6 O2 sensor, 7 water temperature sensor, 8 throttle opening sensor, 9 MAP sensor, 10, 11 electronic control unit

Claims (3)

A gasoline injection signal output from the gasoline injection control device in response to an output signal of the engine operating state detection means is added to a cylinder in an existing gasoline injection system provided with an injection control device for gasoline and an engine operating state detection means. Non-gasoline fuel injection control device for calculating the injection amount of non-gasoline fuel received via a gasoline injection signal line arranged every time and a non-gasoline fuel injector connected thereto An engine fuel supply method implemented in an injection system, comprising:
When the non-gasoline fuel injection control device is in a predetermined predetermined engine operating condition, the non-gasoline fuel is directly controlled based on the data detected by the engine operating state detection means without using the gasoline injection signal. A fuel supply method for an engine comprising: calculating an injection amount of the engine and outputting a fuel injection signal to each of the non-gasoline fuel injectors to execute independent control.   The engine fuel supply method according to claim 1, wherein the single control is executed when the non-gasoline fuel injection control device determines that the start is at a low temperature. A non-gasoline fuel electronic control device comprising storage means storing a program for carrying out the engine fuel supply method according to claim 1 or 2 and the non-gasoline fuel injector include the gasoline already installed in the engine. A fuel supply apparatus for an engine, which is disposed in an injection system and constitutes the gasoline alternative fuel injection system to implement the fuel supply method for the engine.

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