Abstract:
The present invention relates to an electric control fuel injection system for motorcycle, especially for middle and small volume motorcycle. The invention includes CMOS chips, sensors, etc. The different air/fuel ratio corresponding to operating conditions can be obtained with the help of programs and parameters stored in the system and instantaneous parameters measured by sensors. The simple structure, less pollution and economy system can accurately control air/fuel ratio and ignition advance angle.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a fuel control system for engines, especially to an electronic fuel injection system suitable for motorcycle with small or medium displacement.  
         BACKGROUND OF THE INVENTION  
         [0002]    In prior art, the fuel supply apparatus used in the engines of motors with small or medium displacement are generally carburetors. The function of the carburetors is to atomize the fuel into fine particles, to mix air with the atomized fuel at a suitable ratio (air/fuel ratio) and to supply the engine with a gas mixture with optimum air/fuel ratio.  
           [0003]    The change rule of the air/fuel ratio provided by the carburetor in the engine depends on the flow rules of the fuel and air. Because the carburetor provides fuel by vacuum sucking, it is difficult to provide gas mixture in optimum air/fuel ratio and made the gas mixture fully burnt. The engine can not maintain at the best efficiency. In addition, the levels of exhaust emissions from motors and the fuel economy are not satisfactory.  
           [0004]    In addition, the throttle of the traditional carburetors controls the amount of fuel by adjusting the jet. Therefore, it can not automatically control the concentration of gas mixture instantaneously according to the changes of the operating conditions and situations of the engine. It also can not control the air/fuel ratio around the theoretical value. By using carburetor to supply fuel, the air/fuel ratio of the gas mixture is either too big or too small.  
           [0005]    In order to provide the engine with a gas mixture at an optimum ratio under any operating conditions, and to control the concentration of the gas mixture instantaneously according to the changes of the operating conditions and situations of the engine, a lot of studies have been made. However, there hardly have been successful reports until now. Although some progresses have been achieved in electronic fuel injection technology of engines with big displacement or twin-cylinder and four-stroke, because of its complicated structure and high cost, it is difficult to manufacture industrially. Besides, it is hard to be applied directly to four-stroke and single cylinder motor engines with small or medium displacements.  
           [0006]    CN2399520 discloses an electronic fuel injection apparatus for engines. It mainly relates to the circuits and the process of signals. However, it does not disclose the connection modes between the apparatus with the engine and the working procedure.  
           [0007]    CN2351577 discloses an electronic fuel injection apparatus for motors. It also does not disclose the connection modes between the apparatus with the engine and the working procedure.  
           [0008]    EP0212988 discloses a control apparatus for worm gear pressure-increasing internal combustion engine. It discloses part technologies of electronic fuel injection for engines. However, since the number of the controlling points is relatively less and the locations of the controlling points are not reasonable, it can not realize the “precise control” as mentioned in the present invention.  
           [0009]    EP0397521 discloses a circular control system for engines. The electric controlled portion also has defects of less data collecting units and unreasonable location of said units. It also can not realize the “precise control” as mentioned in the present invention.  
         OBJECTS OF THE INVENTION  
         [0010]    One object of the present invention is to provide an electronic fuel injection system especially suitable for internal combustion engines with small or medium displacement, including four-stroke motors with single cylinder.  
           [0011]    The second object of the present invention is to provide an engine using the above-mentioned electronic fuel injection system suitable for motors with small or medium displacement.  
           [0012]    The third object of the present inversion is to provide a motor with the above-mentioned engine.  
         SUMMARY OF THE INVENTION  
         [0013]    The present invention provides a system including an engine, chips, circuits, and sensors. By using the various programs and parameters stored in the chips in combination of the instantaneously parameters of the main parts in the vehicle obtained from the sensors, a precise instantaneously calculation can be realized. The engine of the present invention can control the air/fuel ratio precisely. In addition, the engine mentioned above has the advantages of better ignition advance angle, simple structure, higher automation degree, less amount of exhausting gas and less fuel consumption.  
           [0014]    In combination with the accompanying drawings and the preferred examples, the above-mentioned objects, characteristics and advantages will become more apparent in the following description. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 shows the connection relationship between the electronic fuel injection system for motors of the present invention with the electric-circuit controlling unit  18 , wherein  39  represents an external connection circuit.  
         [0016]    [0016]FIG. 2 is the front view and partial sectional view of the throttle  6  of FIG. 1.  
         [0017]    [0017]FIG. 3 is the right view and partial sectional view of FIG. 2.  
         [0018]    FIGS.  4 ( a ) and ( b ) are the circuit block diagram of the  18  in FIG. 1.  
         [0019]    [0019]FIG. 5 is the controlling flow diagram of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]    The engine of the present invention includes fuel passages, fuel pipes, a fuel pump, a fuel filter, a fuel pressure adjuster, a fuel rail, a throttle body, a sensor for sensing the opening degree of the throttle, an inlet passage, a sensor for sensing the temperature of the cylinder head, an engine, a fly wheel, a sensor for sensing the rotating speed and the ignition signal, and an electronic-driven fuel injector etc.  
         [0021]    The throttle body provided in the inlet passage consists of a shell, a throttle, an adjusting wheel for controlling the opening degree of the throttle, a rotating shaft, a back spring, an initial adjusting screw, a fixing spring, a fuel rail, and a connecting mouth of fuel pipe. Wherein, the throttle is mounted in the shell and is fixed on the rotating shaft by screws. The rotating shaft passes through the shaft radically, one end of the shaft is provided with the adjusting wheel, and the other end of the shaft is connected with the sensor for sensing the opening degree of the throttle. The back spring is sleeved on the rotating shaft and is located between the shell and the adjusting wheel. The initial screw is provided on the shell, and the extending end of the screw contacts the rotating wheel. The fuel rail is provided above the shell, and it connects with the shell via an electronic-driven fuel injector. The fuel connection mouth connects with the fuel pipe. A sensor for sensing the temperature of the inlet air is provided at a position ahead of the throttle body.  
         [0022]    The electric-circuit controlling unit (it will be referred as ECU hereinafter) consists of a microprocessor and converting circuit  32 , a signal processing circuit  33 , an ignition circuit  34 , a fuel injection circuit  35 , a fuel pump control circuit  36 , a signal collection circuit  37 , a reposition circuit  38 , an external connection circuit  39  and a power supply circuit  40 . Wherein, the input of the circuit  32  connects with the signal collection circuit  37 , the signal processing circuit  33 , the reposition circuit  38 , and the power supply circuit  40  respectively, and the output of it connects with the circuits the ignition circuit  34 , the fuel injection circuit  35 , the fuel pump control circuit  36 , the reposition circuit  38  and the external connection circuit  39  respectively.  
         [0023]    In addition to connect with the circuit  32 , the input of the circuit  39  also connects with the circuits  34 ,  35 ,  36 , and  40  respectively. In addition to connect with the circuits  33 ,  37  and  40  respectively, the output of the circuit  39  also connects with the fuel pump, the electronic-driven fuel injector, the sensor for sensing the temperature of the inlet air, the sensor for sensing the opening degree of the throttle, the sensor for sensing the temperature of the cylinder head, the sensor for sensing the rotating speed and the ignition signal, and the igniter respectively.  
         [0024]    The circuit  32  in the ECU  18  is a storage device containing computer programs. It not only stores the programs for calculating the opening degree of the throttle, the temperature of the cylinder head, the temperature of the inlet air, the rotating speed and the ignition signal, the programs for obtaining time and air/fuel ratio data, and the overall running program, but also stores the following programs:  
         [0025]    a. A program for calculating the time of injecting fuel for fuel injector, a program for calculating the opening degree of the throttle, the temperature of the cylinder head, the temperature of inlet air, the rotating speed and the ignition signal, and a program for data analysis and comparison device for comparing the calculated results with the time under various operating modes;  
         [0026]    b. A program for the fuel injection apparatus controlled by the signals from the various sensors and the signals from the data analysis and comparison device;  
         [0027]    c. A program for a failure storing and displaying device;  
         [0028]    d. A program for a fuel-saving and protection device;  
         [0029]    e. A program for the ignition device controlled by the output signals from the various sensors and the output signals from the comparison device.  
         [0030]    The present invention adopts the ECU and the programs stored in the chips  41 , and various running status of the engine are monitored by the various sensors. Based on the signals of the flowing amount of the air detected directly or indirectly, the amount of fuel needed for the combustion in the engine can be calculated precisely by a computer. Then, a starting signal is provided to the fuel injector, and the delaying time is controlled correspondingly. After that, the fuel with a suitable pressure is provided with the engine via the fuel injector. Therefore, the engine can have an optimum air/fuel mixture with suitable air/fuel ratio under various operating modes.  
         [0031]    According to the theoretical calculation and experiment results, 14.7 kg air is needed for thoroughly combusting 1 kg gasoline under standard state. However, the air/fuel ratio will be changed according to the different operating modes of the engine in practice.  
         [0032]    In order to realize the functions of the system of the present invention as mentioned above, it is necessary to further explain the structure of the engine, the electronic-controlling apparatus, their connection modes and running modes.  
         [0033]    As shown in FIG. 1, the engine includes a fuel pump  1 , a fuel filter  2 , a fuel pressure adjuster  3 , a fuel rail  4 , a temperature sensor  5  for inlet air, a throttle body  6 , a sensor  7  for controlling the opening degree of the throttle, an inlet air passage  8 , a temperature sensor  9  for sensing the temperature of the cylinder head, an engine  10 , a fly wheel  11 , a sensor  12  for detecting the rotating speed and ignition signal, a spark plug  13 , an ignition coil  14 , an igniter  15 , an electronic-driven fuel injector  16 , a wire  17 , an ECU  18 , an accumulator  19 , a fuel pipe  20  and a fuel tank  21 .  
         [0034]    The connection and location relationship of the various parts as shown in FIG. 1 are as follows:  
         [0035]    The fuel pump  1  is disposed in the fuel tank  21 . The fuel pipe  20  is provided under the fuel pump  1  and the fuel tank  21 . The fuel filter  2  is provided at the outlet of the fuel tank  21 . The fuel pressure adjuster  3  is provided at the inlet of the fuel pipe  20 . The fuel rail  4  is provided at the middle of the fuel pipe  20 . The fuel rail  4  connects with the inlet air passage  8  via the electronic-driven fuel injector  16 . The temperature sensor  9  for sensing the cylinder head and the spark plug  13  are provided at the cylinder head of the engine. The spark plug  13  connects with the igniter  15  via the ignition coil  14 . The sensor for sensing the rotating speed and ignition signals  12  is provided around the flywheel  11  that locates at the lower portion of the engine  10 . The throttle body  6  locates on the inlet air passage  8  of the engine. The temperature sensor  5  for inlet air is provided at the head of the throttle body  6 , and the electronic-driven fuel injector  16  is provided behind the throttle body  6 . The fuel pump  1 , the fuel rail  4 , the temperature sensor  5  for inlet air, the sensor  7  for controlling the opening degree of the throttle, the sensor  12  for rotating speed and ignition signal, the igniter  15  and the electronic-driven fuel injector  16  are connected with the ECU  18  via the wire  17  respectively. The ECU  18  is connected with the accumulator  19 .  
         [0036]    It can be seen further from FIGS. 2 and 3 that, the throttle body  6  mounted on the inlet air passage  8  consists of a shell  23 , a throttle  24 , an adjusting wheel  27  for adjusting the opening degree of the throttle  24 , a rotating shaft  28 , a back spring  29 , an initial adjusting screw  30 , a fixing spring  31 , a fuel rail  4 , and a connection mouth  26  for the fuel pipe.  
         [0037]    Wherein, the throttle  24  is provided in the shell  23  and is fixed on the rotating shaft  28  via screws. The rotating shaft  28  passes through the shell  23  radically. One end of it is provided with the adjusting wheel  27 , and the other end of it connects with the sensor  27 . The back spring  29  is sleeved on the rotating shaft  28 , and is located between the shell  23  and the sensor  27 . The initial adjusting screw  30  is provided on the shell  23 , and the extending end of the screw  30  contacts the rotating shaft  28 . The fuel rail  4  is provided above the shell  23 , and is connected with the shell  23  via the electronic-driven fuel injector  16 . The connection mouth  26  on the fuel rail  4  connects with the fuel pipe  20 .  
         [0038]    From FIGS. 1 and 3, it can be seen clearly that the throttle shell body  23  is also the inlet air passage  8 . One end of the shell body  23  is connected with the cylinder head  22  of the engine of the vehicle, and the other end is connected with the air cleaner  25  of the engine. The temperature sensor locates both above the shell body  23  and at the middle of the fuel pipe  20 . The sensor  7  and the electronic-driven fuel injector  16  connect with the ECU  18  via wires.  
         [0039]    As shown by FIGS.  4 ( a ) and  4 ( b ), the ECU  18  of the present invention is a controlling unit, which includes a microprocessor and converting circuit  32 , a signal processing circuit  33 , an ignition circuit  34 , a fuel injection circuit  35 , a fuel pump control circuit  36 , a signal collection circuit  37 , a reposition circuit  38 , an external connection circuit  39  and a power supply circuit  40 .  
         [0040]    Wherein, the input of the circuit  32  connects with the circuits  37 ,  33 ,  38 , and  40  respectively, and the output of it connects with the circuits  34 ,  35 ,  36 ,  38 , and  39  respectively.  
         [0041]    In addition to connect with the circuit  32 , the input of the circuit  39  also connects with the circuits  34 ,  35 ,  36 , and  40  respectively.  
         [0042]    In addition to connect with the circuits  33 ,  37  and  40  respectively, the output of the circuit  39  also connects with the fuel pump  1 , the electronic-driven fuel injector  16 , the sensor  5  for sensing the temperature of the inlet air, the sensor  7  for sensing the opening degree of the throttle, the sensor  9  for sensing the temperature of the cylinder head, the sensor  12  for sensing the rotating speed and the ignition signal, and the igniter  15  respectively.  
         [0043]    The circuit  32  in the ECU  18  is a storage device containing computer programs. It not only stores the programs for calculating the opening degree of the throttle, the temperature of the cylinder head, the temperature of the inlet air, the rotating speed and the ignition signal, the programs for obtaining time and air/fuel ratio data, and the overall running program, but also stores: I. a program for calculating the time of injecting fuel; II. programs for calculating the opening degree of the throttle, the temperature of the cylinder head, the temperature of inlet air, the rotating speed and the ignition signal, and a program for data analysis and comparison device for comparing the calculated results; III. a program for the fuel injection apparatus controlled by the signals from the various sensors and the signals from the data analysis and comparison device; IV. a program for a failure storing and displaying device; V. a program for a fuel-saving and protection device; VI. a program for the ignition device controlled by the output signals from the various sensors and the output signals from the comparison device.  
         [0044]    The fuel injection device is operated by the program stored in the circuit  32  shown in FIG. 4( a ) according to the following steps:  
         [0045]    allocating the results stored in the program for calculating the time of injecting fuel;  
         [0046]    terminating the run corresponding to the shutting off signal stored in the overall running program.  
         [0047]    The fuel-saving and protection device is operated by the program stored in the circuit  32  shown in FIG. 4( a ) according to the following steps:  
         [0048]    when the motor is under the state of gear shifting and increasing fuel or running at an accelerating speed, this device does not work;  
         [0049]    when the motor is under the state of gear shifting and decreasing fuel or coasting, this device control the fuel injection device to stop the fuel injection.  
         [0050]    The failure storage and display device operated by the program stored in the circuit  32  is such a device that when the electronic-controlled fuel injection system of the present invention is failed, a failure code is displayed on the display device according to the type of the failure.  
         [0051]    In addition to connect with the circuit  32 , the output of signal process circuit  32  of the ECU  18  as shown in FIG. 4( a ) and FIG. 4( b ) also connects with the circuit  34  and the circuit  38  respectively.  
         [0052]    Wherein, in addition to connect with the circuit  32 , the input of the electronic-driven fuel injection circuit  35  also connects with the circuit  38 . In addition to connect with the circuit  39 , the output of it also connects with the circuit  32 .  
         [0053]    Furthermore, in addition to connect with the circuit  32 , the inlet of the fuel pump control circuit  36  also connects with the circuit  33 .  
         [0054]    The composition and the functions of the various circuit units in the ECU  18  of the present invention are as follows:  
         [0055]    1. The Microprocessor and Converting Circuit  32   
         [0056]    The microprocessor uses 97C52 (or 87C51/87C52 series) chips, the A/D converter uses ADC0808/0809 chips or other chips having equivalent functions.  
         [0057]    The signals collected from the throttle sensor, the cylinder temperature sensor, the inlet air sensor and the rotating speed sensor will be converted by A/D converter firstly. Then these signals will be processed by the microprocessor of this circuit to issue corresponding orders according to the needs under different operating modes to control the working states of the fuel pump, the fuel injector and the igniter. Therefore, the ignition angle and the air/fuel ratio of the gas mixture entering the engine can be at optimum values.  
         [0058]    The IC4B, IC4C, IC4D and IC6 are used to exchange the information between the microprocessor and the A/D converter.  
         [0059]    2. The Signal Processing Circuit  33   
         [0060]    This circuit consists of IC3A, IC3B, IC3C, IC3D, IC3E, IC3F, IC7C, IC7D, IC13F, N2, N9, N11, N12, D5, D6, Z1, D16, D18, Z2, D8, C24, C20, C12, C13, C5, R16, R31, R14, R17, R35, R34, R36, R42, R40, R41, R43, R22 and R45.  
         [0061]    The input of this circuit connects with the circuit  39 , and the output of the circuit connects with the circuits  32 ,  34  and  38  respectively. The signals of rotating speed SIGN undergo decoupling, rectifying, amplitude discrimination and power level conversion before they are sent to the microprocessor as the phase reference for the fuel injecting and igniting, and provide interrupt signals to the igniting circuit  34  for the control of ignition as well as to the resetting circuit as controlling signals of the reposition circuit  38 .  
         [0062]    3. The Ignition Circuit  34   
         [0063]    This circuit mainly consists of R54, R19, C21, D15, IC1B, R38, R26, R37, N8, D11, R59, R55, R12, D12, C8, IC1A, R18, R33, R32, N10, R60 and D13.  
         [0064]    The input of this circuit connects with the circuits  32  and  33  respectively, and the output of the circuit connects with the circuit  39 . The igniting circuit generates and sends igniting pulses to the electronic igniter according to the revolution speed signals and the instruction signal ESA from the microprocessor, so that the electronic igniter generates high voltage pulses to ignite the spark plug.  
         [0065]    4. The Electronic-Driven Fuel Injection Circuit  35   
         [0066]    This circuit consists of IC5D, IC5C, IC7A, IC5B, IC7B, IC8B, IC8C, R4, R48, R25, N4, R5, N5, Z3, R52, R29, R47, R30, N3, R44, R28, N7 and Z4.  
         [0067]    The input of this circuit connects with the circuits  32  and  38  respectively, and the output of it connects with the circuits  32  and  39  respectively.  
         [0068]    This circuit includes a logic control circuit and an amplification circuit. The RS trigger consisted of IC5D and IC5D is controlled by the reposition signal and produces a direct positioning signal to control the fuel injection device. IC7A and IC7B will issue a signal for fuel injection pulse to drive the fuel injector according to the position state, the order for fuel injection (FPC) issued by the microprocessor in combination with the state of the microprocessor (issued by IC5B), and this signal is amplified by N4 to drive N5 to obtain a fuel injection pulse, and this pulse will drive the fuel injector to work.  
         [0069]    In the drawing, R52 is a sampling resistance used for detection.  
         [0070]    When the microprocessor circuit is in failure and can not work normally, IC5B receives a fixed signal issued by UA556 to drive the fuel injector at a fixed frequency and flow amount. In this way, the motor can run temporarily. Thus, this circuit is called as “go home” circuit.  
         [0071]    5. The Fuel Pump Control Circuit  36   
         [0072]    This circuit consists of R57, C9, D173, R2, R58, C10, D2, R7, IC1C, IC2A, IC2B, R8, R9, R49, N1, R46, D3, R24 and C121.  
         [0073]    The input of this circuit connects with the circuits  32  and  33  respectively, and the output of it connects with the circuits  32  and  39  respectively. According to the signals of start or stop issued by the microprocessor and the working signals issued by the circuit  33 , which have been processed logically by the IC1C, IC2A and IC2B, this circuit will drive the fuel relay to work.  
         [0074]    Wherein, D3 and C121 are protection circuits; R46 is a sampling resistance for failure detection.  
         [0075]    The DRPMP signal of IC1C is effective when “going home”.  
         [0076]    6. The Signal Collection Circuit  37   
         [0077]    This circuit consists of R192, R50, VRJ, R1, R20, Z7, R53, R21, Z8, R23, Z9 and C25.  
         [0078]    This circuit delivers the collected signals to the circuit  32 . Wherein, the throttle signal THRTT are sampled by R23, Z9 and C25, and are sent to the A/D converter. The cylinder temperature signal THW are sampled by R20, Z7 and are sent to the A/D converter. The air temperature signals THA are sampled by R21, Z8 and are sent to the A/D converter. R50 and VRJ are used to adjust the amount of the injected fuel slightly.  
         [0079]    7. The Reposition Circuit  38   
         [0080]    This circuit mainly consists of UA556A, UA556B, IC4E, IC5A, IC8D, IC8A, IC9A and related external circuits.  
         [0081]    The input of this circuit connects with the circuits  32  and  33  respectively, and the output of the circuit connects with the circuit  35 . The program monitoring signal WDT in the microprocessor triggers UA556A and UA556B circuits to issue a reposition signal RST. When the power is connected or the program is in failure, it can make reposition for the microprocessor to make it back to the initial state. Thus, the program can work under normal state.  
         [0082]    Another function of the UA556A and UA556B is to issue “go home” signal when the microprocessor stop working because of failure to make the “go home” circuit work.  
         [0083]    8. The External Connection Circuit  39   
         [0084]    This circuit mainly consists of T1A, T1B, R116, R115, Z6 and Z5.  
         [0085]    In addition to connect with the circuit  32 , the input of this circuit also connects with the circuits  34 ,  35 ,  36  and  40  respectively, and the output of it connects with the circuits  33 ,  37  and  40  respectively.  
         [0086]    The T1A and T1B are core sockets, and they are used to connect with the external power supply, the sensors, the fuel pump relay, the fuel injector, the failure display device and the igniter.  
         [0087]    Wherein, INJ connects with the fuel injector. PUMP connects with the fuel pump relay. CDIU connects with the igniter. VCC is the output power of 5 V. SIGN connects with the rotating-speed signal sensor. GND connects with ground. THRTT connects with the throttle sensor. THW connects with the cylinder temperature sensor. THA connects with the inlet air temperature sensor. VBAT connects to a 12V power supply. RXD and TXD connect with the failure display device.  
         [0088]    9. The Power Supply Circuit  40   
         [0089]    This circuit consists of D17, E1, E2, Z10, R10, R3, C1, C3, C411, C6, C14 and GND.  
         [0090]    The input of this circuit connects with the accumulator of motor, and the output of it connects with the power ends of the various circuit units respectively to provide with power to the various circuits.  
         [0091]    In this circuit, Z10, R10 and R3 are used to be the detecting power supply, and the detecting results are sent to the microprocessor via the A/D converter.  
         [0092]    The working procedures of the electronic-controlled fuel injection system of the present invention are as follows:  
         [0093]    When the power is connected, the ECU  18  receives a reposition signal, and a start signal will be sent to the relay of the fuel pump  1  within 6 seconds. The fuel in the fuel tank  21 , after pressure adjusting by the fuel pressure adjuster  3 , will be delivered into the electronic-driven fuel injector  16 .  
         [0094]    When the starter button of the engine is pressed, the sensor  7  will have a movement. The movement will produce a weak signal, and this signal will be delivered to the ECU  18 . After receiving this signal, the ECU  18  will send a starting signal to the relay of the fuel pump  1  to make it connected to power, and the fuel pump  1  will start to work.  
         [0095]    At the time of pressing the starter button, the start motor will drive the crankshaft of the engine to rotate. For each revolution, the sensor  12  will issue an ignition pulse signal to the ECU  18 .  
         [0096]    At the same time, the sensor  12 , the sensor  5  ahead of the throttle body  6  and the sensor  9  will produce electronic signals corresponding to the situations, such as the rotating speed, the inlet air temperature, the cylinder head temperature etc., of the engine at the time of starting, and these signals will be delivered to the ECU  18 . These signals are processed by the program stored in 97C52 to obtain an optimum amount of fuel to be injected, and a signal derived from the results are delivered to the output of the electronic-driven fuel injector  16 .  
         [0097]    The fuel is supplied to the electrical-driven fuel injector  16  via the fuel pipe  20 , the fuel pipe connection mouth  26 , and the fuel rail  4 . According to the fuel injection signal provided by the ECU  18 , the fuel is injected by the electronic-driven fuel injector  16 .  
         [0098]    The fuel is supplied to the electronic-controlled fuel injector  16  via the fuel pipe  20 , the connection mouth  26  of the fuel pipe and the fuel tail  4 , and then the electronic-controlled fuel injector  16  jets fuel according to the jet signal from the ECU  18   
         [0099]    At the time of starting the electronic-driven fuel injector  16 , the igniter  15  receives an ignition signal (including that of ignition advance angle) from the ECU  18 . An electric spark will be produced by the spark plug  13  via a high-voltage coil and the ignition coil  14 , and this spark will ignite the fuel/air gas mixture in the combustion chamber of the engine. Therefore, the engine is started and will begin to work normally.  
         [0100]    When the engine runs under the states of accelerating, decelerating or running with load, the various sensors will issue various corresponding signals to the ECU  18 . The ECU  18  will calculate the starting time and ignition signal for the electronic-driven fuel injector  16 . Therefore, the optimum running data can be obtained for the engine under different operating modes.  
         [0101]    The above-mentioned various operating modes, and the adjustment of the starting time, the air/fuel ratio and corresponding ignition angle in accordance with instant operating modes for the electronic-driven fuel injector  16  are well-known by the person skilled in the art.  
         [0102]    The control flowchart for the electronic-controlled fuel injection system of the present invention are as follows:  
         [0103]    1. Reposition  
         [0104]    2. Allocation of the sub-program for measuring the rotation speed  
         [0105]    3. Criterion: Whether the rotation speed&lt;the reference value. If the answer is N, continue. If the answer is Y, back to 1.  
         [0106]    4. Criterion: rotating speed&gt;=the reference value. If the answer is N, continue. If the answer is Y, back to 1 after the “fuel injection time is cleaned to zero”.  
         [0107]    5. Allocation of the sub-program for the opening degree of the throttle  
         [0108]    6. Criterion: Whether the throttle is at the idling position. If the answer is Y, continue. If the answer is N, then criterion: “whether the opening degree of the throttle-last opening degree of the throttle&gt;the reference value”.  
         [0109]    7. Criterion: Whether the rotating speed&gt;the reference value. If the answer is N, continue. If the answer is Y, back to 1 after the “fuel injection time is cleaned to zero”.  
         [0110]    8. Allocation of the sub-program for the stored charts.  
         [0111]    9. Allocation of the sub-program for measuring temperatures.  
         [0112]    10. Allocation of the sub-program for adjusting the temperatures by the stored charts.  
         [0113]    11. Correction of the results from the charts.  
         [0114]    12. Check and store the corrected data, back to 1.  
         [0115]    Following the above step  6 , if the answer is N, then make a criterion: “whether the opening degree of the throttle−the last opening degree of the restrictor&gt;the reference value”. If the answer is N, back to 8; If the answer is Y, allocate the sub-program for the stored charts, adjust the results from the charts and back to 9, which shown in FIG. 5.  
         [0116]    Comparing with the prior art, the electronic-controlled fuel injection system of the present invention has the following advantages:  
         [0117]    The electronic-controlled fuel injection system of the present invention can automatically control the concentration of the fuel-air gas mixture instantaneously according to the opening degree of the throttle, the operating modes of the engine and the change of the environment to realize the precise control.  
         [0118]    Another advantage of the system of the present invention is that the engine can have a suitable air/fuel ratio under various operating modes.  
         [0119]    The system of the present invention also has the advantages of simple structure, higher automation degree, small pollution level and saving fuel. The system of the present invention is suitable for the internal combustion engine with small or medium displacement, especially for the four-stroke engine with small displacement.  
         [0120]    Although a certain preferred embodiment has been shown and described, it should be understood that many changes and modifications may be made therein without departing from the scope of the appended claims.