JPS6248055B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply system for a spark ignition engine for an automobile, and more particularly to a fuel supply system that is activated when a failure occurs in an electronically controlled fuel supply system.

In order to improve the output, drivability, fuel consumption characteristics, exhaust composition purification characteristics, etc. of a spark ignition engine, it is necessary to appropriately control the air-fuel ratio of the mixture, ignition timing, exhaust recirculation rate, etc. according to the engine operating condition. It is essential to do so. Among these, controlling the air-fuel ratio is particularly important, and many improvements have been made to carburetors and mechanical fuel injection devices. However, these mechanical fuel supply devices have insufficient responsiveness and flexibility in air-fuel ratio control, making it difficult to obtain an appropriate air-fuel ratio over a wide operating range.

In order to improve this, a fuel supply system was developed, as described in Japanese Patent Application Laid-Open No. 54-134223, which added an electronic control device to the conventional carburetor and mechanical fuel injection device that detects the operating state of the engine and operates it. Although it has been commercialized, sufficient measurement accuracy cannot be maintained due to the processing accuracy of the mechanical parts. Therefore, an electronically controlled single-point fuel injection device that converts a signal related to the amount of intake air into an electric signal to electrically control the fuel flow rate has been developed and commercialized. This is to precisely adjust the amount of fuel supplied by adjusting the opening time of a solenoid valve installed in the pressurized fuel flow path. This has greatly improved fuel supply accuracy and responsiveness. However, the electronically controlled single point fuel injection system has the disadvantage that once the fuel injection valve or its drive circuit fails, the engine will stop and it will be completely impossible to start it. Since this would leave the vehicle without any treatment at all, there is a need for countermeasures that would allow the vehicle to at least drive to the nearest repair shop on its own.

An object of the present invention is to provide an electronically controlled fuel supply device that can run on its own even when a fuel injection valve or its drive circuit breaks down. A sensor or a pressure sensor is provided to detect an abnormality in the fuel flow, and when an abnormality occurs, fuel is supplied from another fuel supply means.

FIG. 1 is a system diagram of an electronically controlled fuel supply system. Air is drawn into the feed cylinder 1 from an air cleaner 2, passes around a primary throttle valve 3 and a secondary throttle valve 4, and is supplied to the open cylinder via a suction pipe. An intake air temperature sensor 6 is installed in the air cleaner 2, and an air flow meter 7 is installed in the bypass air passage provided in the feed cylinder 1, and by measuring the amount of intake air and its temperature, the weight of air supplied to the engine is determined. I'm trying to be able to do that. In addition, the engine has a cooling water temperature sensor 8,
A rotation speed sensor 9 is installed to detect the operating state of the engine. Further, a fuel injection valve 5 is installed downstream of the primary throttle valve 3, and a fuel pressure regulator 11
3. It communicates with a fuel tank 15 via a fuel pump 14 and an on-off valve 16. That is, pressurized fuel is supplied to the fuel injection valve 5.

The electronic control device 20 includes a microprocessor 21,
REIT only memory 22, digital input circuit 2
3. Digital output circuit 24, angular velocity signal conversion circuit 25, A/D conversion circuit 26, air flow meter signal processing circuit 27, injection time control circuit 28, bypass air control signal circuit 29, idle rotation speed control circuit 30
A current from the battery 10 is introduced into the digital input circuit 23 via the key switch 11, and a digital signal indicating the opening degree of the primary throttle valve 3 is input to the digital input circuit 23. Further, the signal from the rotational speed sensor 9 is input to the angular velocity signal conversion circuit 25, and the current of the battery 10 and the cooling water temperature sensor 8 are input to the A/D conversion circuit 26.
, the signal of the intake air temperature sensor 6, and the signal of the air flow meter 7, and input the output of the air flow meter signal processing circuit 27.

The processing data of these circuits is temporarily stored in the read-only memory 22, but is read out at any time according to instructions from the microprocessor 21. The output of the digital output circuit 24 opens the on-off valve 16 and sends pressurized fuel to the fuel injection valve 5. In addition, the output of the bypass air control signal circuit 29 operates the diaphragm valve 12 via the idle speed control circuit 30, and opens the air passage bypassing the secondary throttle valve 4 to increase the idle speed. Replenish the amount. The injection time control circuit 28 outputs a signal that determines the opening time of the fuel injection valve 5, and operates the fuel injection valve drive circuit 31 to inject a suitable amount of fuel.

FIG. 2 is an enlarged cross-sectional view of the main part of FIG.
is opened, and the injected fuel particles 18 are supplied to the suction pipe to form a mixture. Note that a sensor of a hot wire air flow meter 7 is installed in an air passageway that opens upstream of the bench lily portion 19 of the feed cylinder 1 and communicates with the bench lily portion 19.

The electronically controlled fuel supply system equipped with the single-point fuel injection valve 5 configured as described above injects and supplies the amount of fuel in the form of fine particles that matches the absolute amount of intake air and the operating condition of the machine, so that the air-fuel mixture is It becomes possible to control the air-fuel ratio in an extremely suitable manner. Therefore,
It improves engine drivability, purifies exhaust composition, and reduces fuel consumption. However, if a failure occurs in the fuel injection valve 5 or its drive system, the amount of fuel supplied will be zero, and the engine will immediately stop, resulting in a situation that is extremely difficult to handle. To prevent this, the following automatic emergency backup means is provided. This backup means first detects an abnormality in the fuel injection valve 5.

FIG. 3 is a sectional view showing the installation location of a fuel injection valve abnormality detection device according to an embodiment of the present invention. The fuel injection valve 5 has a fuel flow path 41 as shown in FIG.
is connected and fuel is supplied at a constant pressure. When the current from the fuel injection valve drive circuit 31 is output to the coil of the fuel injection valve 5, the valve is pulled open and pressurized fuel flows through the fuel flow path 41. If a fuel flow sensor 40 is installed in this fuel flow path 41, abnormalities in fuel supply can be reliably detected.

FIG. 4 is an enlarged view of part B in FIG. 3, showing the hot wire flow rate sensor 42 installed in the fuel flow path 41. That is, the heating element 42a is installed on the upstream side of the fuel flow indicated by the arrow, and the heat-sensitive element 42b is installed on the downstream side, both of which are connected to the drive circuit 43. When the fuel is flowing normally, the fuel heated by the heating element 42a contacts the heat-sensitive element 42b and heats the heat-sensitive element 42b, generating a high-level signal, and the fuel injection valve 5 does not open. generates a low level signal, which is passed through the measuring circuit 43 to the electronic control unit 20.
It is output to.

FIG. 5 is also an enlarged view of part B in FIG. 3, and in this case shows a state in which a pressure sensor 44 is installed in the fuel flow path 41. When the fuel injection valve 5 is operating normally, the fuel pressure decreases when the valve is opened and increases when the valve is closed.
However, when the fuel injection valve 5 or its drive circuit 31 fails, the fuel injection valve 5 is closed by the spring, maintains a high output level, and a signal is output from the measurement circuit 45 to the electronic control device 20. maintain a high level. This detects that fuel is not flowing.

FIG. 6 is a diagram illustrating the abnormality detection method using the fuel flow sensor in FIG. , and d is the shaped waveform of c. When the fuel injection valve 5 is operating normally, it produces a d signal synchronized with b, but when the fuel injection valve 5 breaks down, it does not produce signals like c and d, but becomes a low level signal. It clearly makes a difference. If this is compared using the electronic control device 20, a failure can be easily determined.

The above is a means for determining the stoppage of fuel supply due to failure of the fuel injection valve 5 and various sensors, etc.
Other fuel supply means that automatically operate based on this determination result will be explained.

FIG. 7 is a system diagram of a fuel supply system according to an embodiment of the present invention, in which the same parts as in FIG. 1 are given the same reference numerals. The difference from FIG. 1 is that a fuel flow path 50 opened in the bench lily portion 19 of the fuel supply cylinder 1 is provided, a solenoid valve 47 with a needle facing the orifice 48 of this fuel flow path 50 is arranged, and an electronic The electromagnetic valve 47 is configured to be operated by the output signal of the control device 20. When the fuel injection valve 5 is operating normally, the solenoid valve 47 contacts the orifice 48 and closes the fuel flow path 50, but as described above, the electronic control device 20 prevents normal fuel supply from occurring. If it is determined that there is no malfunction,
Immediately generates an output signal to open the solenoid valve 47. Therefore, the fuel in the fuel passage 50 is sucked in by the negative pressure generated by the intake air flow passing through the bench lily portion 19, and the fuel is ejected into the intake passage. That is, when the fuel injection valve 5, the air flow meter 7, the fuel injection valve drive circuit 31 of the electronic control device 20, etc. fail, the configuration is such that the conventional carburetor is switched to supply emergency fuel. This allows the vehicle to travel on its own to at least the nearest repair shop. Note that the orifice 4 installed in the fuel flow path 50
Reference numeral 9 is installed to facilitate the supply of fuel and to adjust the air-fuel ratio.

The electronically controlled fuel supply system of this embodiment is provided with a fuel flow path that communicates between the vent lily of the feed cylinder and the fuel tank, and a solenoid valve that opens and closes this fuel flow path when the fuel injection valve and its drive circuit are malfunctioning. By configuring the valve to open in response to a signal from an electronic control device, it is possible to temporarily supply fuel and run the vehicle on its own.

FIG. 8 is a system diagram of a fuel supply system that is a modification of FIG. 7. What differs from FIG. The aim is to improve responsiveness by quickly supplying pressurized fuel in the event of a failure. That is, a solenoid valve 47 having a needle 52 inserted into the fuel flow path 41 is installed, and when a failure occurs, the solenoid valve 47 is operated to supply fuel to the bench lily portion 19. The other end of the needle 52 passes through the electromagnetic valve 47 and is fitted with a valve 53, which is pressed by a spring 56. Also, this valve 5
3 is a pressurized fuel flow path 41 and a fuel return path 51
The fuel passage in which the orifice 55 is installed is opened and closed.

When the fuel injection valve 5, air flow rate 7, etc. malfunction and become inoperable and fuel is not supplied, the solenoid valve 4 is activated by the output of the electronic control device 20.
7 to open the needle 52 and valve 53. The pressurized fuel flows from the fuel flow path 41 to the fuel flow path 50 and injects the fuel into the bench lily portion 19.
The orifice 54 is installed to reduce the amount of pressurized fuel. Further, since the valve 53 is also opened together with the needle 52, the fuel whose pressure has been reduced due to being restricted by the orifice 55 is returned to the fuel tank 15 through the fuel return passage 51. The opening areas of the orifices 54 and 55 are set so that the amount of fuel supplied into the bench lily portion 19, that is, the air-fuel ratio of the air-fuel mixture supplied to the engine is appropriate.

The fuel supply device of this embodiment is provided with a fuel flow path that communicates the pressurized fuel flow path to the fuel injection valve with the bench lily, and pressurizes by opening the solenoid valve installed in this fuel flow path in the event of a failure. By spouting fuel into the bench lily, it has the effect of quickly supplying fuel and allowing the vehicle to run on its own.

The electronically controlled fuel supply device of the present invention is provided with means for detecting a failure in which fuel is not injected from the fuel injection valve even if a control signal is output from the electronic control device, and the fuel supply device is provided with a means for detecting a failure in which fuel is not injected from the fuel injection valve even if a control signal is output from the electronic control device. Emergency fuel is supplied by opening the road using the output from the electronic control device that detected the failure,
The effect is that the vehicle can run on its own.

[Brief explanation of the drawing]

Figure 1 is a system diagram of the electronically controlled fuel supply system, Figure 2
The figure is an enlarged sectional view of the main part of Figure 1, Figure 3 is a diagram showing the installation location of the fuel injection valve failure detection device according to the embodiment of the present invention, and Figure 4 is an enlarged view of part B of Figure 3. 5 is an enlarged view of part B in FIG. 3 when another abnormality detection device is installed, FIG.
The figure is a system diagram of a fuel supply system that is an embodiment of the present invention, and FIG. 8 is a system diagram of a fuel supply system that is a modification of FIG. 7. 1... Supply cylinder, 3... Primary side throttle valve, 5... Fuel injection valve, 6... Intake air temperature sensor, 7... Air flow meter, 8... Cooling water temperature sensor, 9... Rotational speed sensor, 10... Battery, 11... Key switch, 12... Diaphragm valve, 13... Fuel pressure regulator, 14... Fuel pump, 15... Fuel tank, 16... Open/close valve, 17... Nozzle, 18
... Fuel particles, 19 ... Bench lily part, 20 ...
electronic control device, 21... microprocessor,
22...Read-only memory, 23...Digital input circuit, 24...Digital output circuit, 25...
Angle signal conversion circuit, 26...A/D conversion circuit, 2
7...Air flow meter signal processing circuit, 28...Fuel injection time control circuit, 29...Bypass air control signal circuit, 30...Idle rotation speed control circuit, 31
... Fuel injection valve drive circuit, 40 ... Fuel flow rate detector, 41, 50 ... Fuel flow path, 42 ... Hot wire flow meter, 43, 45 ... Measurement circuit, 44 ... Pressure sensor, 46 ... Strainer, 47...Solenoid valve, 4
8, 49, 54, 55... orifice, 51...
fuel return passage, 52... needle, 53... valve,
56...Spring.

Claims (1)

[Claims] 1. An electronic control device that inputs and processes signals that detect the amount of air taken in from the feed cylinder and the operating state of the spark ignition engine, and operates based on the output of this electronic control device to inject liquid fuel into the feed cylinder. In an electronically controlled fuel supply system having a fuel injection valve that supplies fuel, a thermal flow sensor or a pressure sensor is provided in the fuel passage leading to the fuel injection valve, and when these sensors no longer detect the flow of fuel. An electronically controlled fuel supply device configured to supply fuel from an auxiliary fuel supply device.