JPH021489Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improvement of a mixture supply device using a variable ventilator carburetor.

In conventional variable ventilator carburetors, fuel is metered by a metering needle attached to the ventilee piston and a jet attached to the fuel outlet. Since the metering needle is attached to the ventilate piston, the annular area of the metering section changes depending on the amount of movement of the piston. However, it is difficult to accurately control the air-fuel ratio, and it is also difficult to incorporate a mechanism for detecting excess oxygen in the exhaust gas and feedback controlling the mixture ratio.

In view of the above, the present invention is a variable ventilator system that not only accurately controls the air-fuel ratio and secures the fuel supply amount according to the amount of movement of the ventilator piston, but also allows the fuel supply amount to be easily controlled by the output signal of another compensation mechanism. This is an improved type of air-fuel mixture supply device using a type carburetor, and is a variable ventilized type carburetor in which a ventilized piston 3 moves forward and backward toward a ventilated part 2 provided with a fuel discharge port 13, and the stroke of the ventilized piston is controlled. The electrical signal is converted into a pulse signal, and the supplied fuel is controlled by operating a control member provided in the fuel passage.The control member includes the fuel discharge port 13 and the fuel inlet 11. A metering section 17 consisting of a metering needle 9 and a seat 10, which move forward and backward by the rotation of a step motor 8,
In addition to providing a supply fuel metering device 7 having a
The fuel inlet 11 is provided at the lower part of the carburetor main body 1, and the fuel passage 15 from the fuel inlet 11 is upwardly connected via the fuel metering device to a diaphragm fuel pressure regulator 12 attached to the upper part of the carburetor main body. It extends to form a return passage and communicates with the fuel tank via the regulator, and also communicates one side of the diaphragm of the fuel pressure regulator 12 with a negative pressure port 14 opened near the fuel discharge port 13 of the ventilary part 2. , furthermore, immediately before the metering section 17, there is a large cavity 1 which communicates with the fuel passage 15 with the metering needle 9 as the center.
5a is provided.

Next, embodiments of the drawings will be described.

In FIG. 1, a detection device 6 for detecting linear displacement and converting it into an electric signal is installed at the rear (left side of the figure) of a guide 4 fixed to a ventilator piston 3 located in a ventilator part 2 of a carburetor body 1. A displacement-to-voltage converter using a displacement detection potentiometer is arranged to detect the amount of movement of the guide 4. The ventilator piston 3 is always urged forward by a spring 5. As shown in FIG. 2, the drive control device 100 connected from the detection device 6 to the input terminal of the drive control device 100 includes a comparator 101, an oscillator 102, an up/down counter 103, a latch 104, a timing generator 105, and a digital /Analog converter 1
06 and a drive circuit 107. The output terminal of the drive control device 100 is connected to the step motor 8 of the fuel metering device 7. Referring again to FIG. 1, the fuel metering device 7 is composed of a step motor 8, a metering needle 9 that moves forward and backward as the step motor rotates, and a seat 10 that measures fuel by an annular area between the metering needle and the metering needle. ing. Here, the metering needle 9 and the sheet 10 constitute a measuring section 17. A fuel inlet 11 is attached to the lower part of the carburetor body 1, and a fuel pressure regulator 12 is attached to the upper part of the carburetor body 1. The fuel pressure regulator 12 is a known diaphragm type regulator that includes a diaphragm biased by a spring, a valve operated by the diaphragm, and a seat. One side of the diaphragm of the fuel pressure regulator 12 communicates with a negative pressure port 14 opened near the fuel discharge port 13 of the ventilate section 2, and the negative pressure of the ventilate section is guided from the negative pressure port 14. The valve seat of the fuel pressure regulator 12 also communicates with the fuel tank via an outlet 16. The fuel inlet 11 and the other side of the diaphragm of the fuel pressure regulator 12, ie, the valve seat side, are connected by a passage 15 to form a return passage, and the fuel metering device 7 is located in the middle of this passage. The measuring section 1
7, there is a large empty space 1 which communicates with the fuel passage 15 with the metering needle 9 as the center.
5a is provided. The end of the fuel passage of the fuel metering device 7 opens into the ventilate portion 2 at a fuel discharge port 13. In the embodiment shown in FIG. 1, a displacement-to-voltage converter using a linear displacement detection potentiometer is used to detect the amount of movement of the ventilate piston 3, but a differential transformer or the like may also be used. You can also do that.

Next, its effect will be explained.

The ventilator piston 3 of the ventilator part 2 of the carburetor main body 1 is supported by a spring 5 so that the flow rate of intake air passing through the ventilator part 2 is always constant.
It is controlled by and moves back and forth according to the amount of intake air. This amount of movement is detected by a detection device 6 provided after the piston guide 4, and converted into an electrical signal corresponding to the amount of movement of the ventilated piston 3. That is, a DC voltage proportional to the amount of movement of the piston is obtained as the output of the detection device 6 and the drive control device 10
It is input to 0.

In the drive control device 100, a timing generator 105 controls the digital signal (signal corresponding to the position of the metering needle) of an up-down counter 103, which functions as a circuit for storing the position of the metering needle 9 of the fuel metering device 7. Digital/analog via latch 104
The converter 106 converts it into an analog signal voltage corresponding to the position of the metering needle, and the comparator 101 compares it with the output signal voltage from the detection device 6. /When the output voltage is higher than the output voltage of the analog converter, the stepper motor 8 is driven to generate an output signal that rotates the step motor 8 in a direction in which the annular area between the metering needle 9 and the seat 10 of the fuel metering device 7 increases. circuit 10
7 is an oscillator 10 according to the comparison output of the comparator 101.
2 is pulse-modulated and applied to the step motor 8. The step motor 8 rotates in a rotational direction according to the output signal of the drive circuit 107, moves the metering needle 9 backward to the right, and increases the annular area between the metering needle 9 and the seat 10.

Conversely, if the output voltage of the digital/analog converter corresponding to the signal of the storage circuit 103 is higher than the output signal voltage of the detection device 6, the annular area between the metering needle 9 and the seat 10 is reduced. The step motor of the fuel metering device 7 is driven in the opposite direction of rotation. Fuel passes through a fuel filter from a fuel tank (not shown), is pressurized by a fuel pump, and is forced into the fuel inlet 11 of the carburetor main body 1. Further, the pressure is controlled by the fuel pressure regulator 12 to a constant pressure determined by the negative pressure of the ventilary section 2 and the spring against the diaphragm of the fuel pressure regulator 12. The fuel controlled to a constant pressure is metered by a metering section 17 of the fuel metering device 7 located between the fuel inlet 11 and the fuel pressure regulator 12. That is, the fuel is metered by the annular area of the metering section 17 composed of the metering needle 9 and the seat 10, is discharged from the fuel outlet 13 to the ventilary section 2, is mixed with intake air, and is sent to the engine through the intake pipe. supplied to the cylinder. Further, the amount of fuel pumped by the fuel pump is always greater than the maximum fuel consumption of the engine, and the amount other than the amount discharged to the ventilate is sent from the fuel pressure regulator 12 to the fuel tank via the outlet 16. However, the fuel pumped under pressure from the fuel pump has a slow flow rate at a large cavity 15a located immediately in front of the metering section 17 in the middle of the passage 15, making it easy to separate the fuel from the fuel vapor. Therefore, vapor does not flow into the measuring section 17, and accurate metering is performed.

The up/down counter 103 is the comparator 101
The pulses from the oscillator 102 are added or subtracted depending on the comparison output of the oscillator 102. That is, when the output signal voltage of the detection device 6 corresponding to the amount of movement of the ventilary piston 3 is large compared to the output voltage of the digital/analog converter 106 applied to the input of the comparator 101, addition is performed. Increasing its memory value, digital/analog converter 1
When the output signal voltage of the detection device is smaller than the output voltage of 06, subtraction is performed to decrease the stored value. When the up-down counter is added, the drive circuit 107 rotates the step motor 8 by the same number of steps as the number of addition pulses, thereby retracting the metering needle 9 and increasing the amount of fuel to be supplied. Further, when the up-down counter is subtracted, the drive circuit 107 rotates the step motor 8 in the opposite direction by the same number of steps as the number of subtraction pulses to reduce the supplied fuel. In this way, the up-down counter stores the position of the metering needle as a number of pulses. Therefore, the comparator 101 compares the amount of movement (position) of the ventilate piston 3 corresponding to the air flow rate passing through the ventilate section with the position of the metering needle 9 that determines the amount of fuel to be supplied, and the correspondence between the two matches. output to control the system. However, the characteristics of each device, such as the ventilary piston detection device 6 and the fuel metering device 7, are determined in advance so that the optimal air-fuel ratio is achieved when these two correspondences match.

The present invention converts the stroke of the ventilate piston into an electrical signal, and drives the step motor of the fuel metering device in accordance with the electrical signal to move the metering needle forward and backward, thereby achieving a highly accurate air-fuel ratio. In addition, it is easy to use electrical signals to perform compensation such as during startup, low temperature, and feedback control using an exhaust 02 sensor.

Further, since the fuel metering device is composed of a step motor, a metering needle, and a seat, and the fuel is continuously discharged and atomized into the ventilate, stable engine rotation and good distribution performance between cylinders can be obtained.

In addition, since the fuel is constantly recirculated by the fuel pressure regulator, the fuel temperature is kept at a relatively low temperature and there is little vaporization of the fuel.Furthermore, the position above the metering part 17 is such that excess recirculated fuel always flows upward. A fuel pressure regulator is arranged in the metering part 17, and the empty chamber 15a for separating the vapor is arranged in the metering part 17.
Since the metering needle 9 is provided directly in front of the metering needle 9, even if the fuel is vaporized, the vapor is separated and refluxed and does not adversely affect the fuel metering.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the present invention, and FIG. 2 is a circuit diagram of the drive control device. 1... Carburetor body, 2... Ventilation part, 3
...Benture piston, 4...Guide, 5...
... Spring, 5a... Chamber, 6... Detection device, 7
...Fuel metering device, 8...Step motor, 9...
...Metering needle, 10...Sheet, 11
... Fuel inlet, 12 ... Fuel pressure regulator, 13
... Fuel discharge port, 14 ... Negative pressure port, 15 ... Passage, 17 ... Measuring section, 100 ... Drive control device,
101... Comparison circuit, 102... Oscillator, 103
...Up-down counter, 104...Latch, 105...Timing generator, 106
...Digital/analog converter, 107
...Drive circuit.

Claims (1)

[Scope of utility model registration request] This is a variable ventilator type carburetor in which a ventilator piston 3 moves forward and backward toward a ventilator section 2 provided with a fuel discharge port 13, and converts an electric signal caused by the stroke of the ventilator piston into a pulse signal, thereby causing air to flow into the fuel passage. In the device in which the supplied fuel is controlled by operating a control member provided, the control member includes the fuel discharge port 1.
A supply fuel metering device 7 having a metering section 17 consisting of a metering needle 9 and a seat 10 that move forward and backward with the rotation of a step motor 8 is provided in a passage connecting the fuel inlet 11 and the fuel inlet 11. A return passage is provided at the lower part of the carburetor body 1, and a fuel passage 15 from the fuel inlet 11 is extended upward through the fuel metering device to a diaphragm fuel pressure regulator 12 attached to the upper part of the carburetor body. The metering section 17 An air-fuel mixture supply device characterized in that a large cavity 15a is provided immediately before the metering needle 9 and communicates with the fuel passage 15.