JPH01130045A - Auxiliary fuel supply system for carburetor - Google Patents

Abstract

PURPOSE:To make a proper fuel increment easily performable at an extensive flow range by operating a fuel control valve for its opening or closing according to a duty ratio, and opening a fuel flow control valve at the time of cranking but closing it at a driving range other than that. CONSTITUTION:In an auxiliary fuel passage 5, there are provided with a fuel pump 6, a pressure regulator 7, a fuel control valve 8 and a jet 9 in order. An increment fuel passage 12 with a fuel flow control valve 10 and a jet 11 is parallelly branched and formed at the more downstream side than the fuel pump 6 of the auxiliary fuel passage 5. The fuel control valve 8 is subjected to electromagnetic drive and opened or closed by a driving signal consisting of a pulse wave in a specified duty ratio fed out of an electronic control circuit 13. The fuel flow control valve 10 is also subjected to the electromagnetic drive, and it is fixed to a valve opening position at the time of cranking but it is fixed to a valve closing position at a driving range other than that.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an auxiliary fuel supply device for increasing the amount of fuel supplied to an engine, and is mainly used for increasing the amount of fuel at a cold start. Ru.

(Prior Art) For example, a carburetor that supplies air-fuel mixture to an automobile engine includes a choke mechanism for properly performing low-temperature start and subsequent warm-up operation, an idle-up mechanism for stabilizing idling operation, and an idle-up mechanism for stabilizing idling operation. The vehicle is equipped with an acceleration mechanism to speed up the acceleration operation.

Since these are provided as separate devices, not only does the structure of the carburetor become extremely complicated, but there are also problems such as poor reliability in properly increasing the amount of fuel. Therefore.

An auxiliary fuel passage is provided that opens from the constant oil level chamber to the downstream side of the throttle valve in the intake passage, and air is introduced into the fuel flowing through this passage, and by opening this passage when increasing the amount of fuel, the required air-fuel mixture is replenished. The one that was made was
No. 0307, Utility Model No. 87320, Utility Model Publication No. 1982-
This method has been proposed in various publications such as No. 2284.

(Problems to be Solved by the Invention) However, in the above-mentioned Japanese Patent Publication No. 5, the fuel and air supplied through the auxiliary fuel passage are controlled according to the engine temperature.
The means described in Publication No. 1-10307 has low control accuracy (it is not possible to properly increase the amount of fuel in response to the operating conditions).In addition, input is input to the electronic control circuit while the engine is operating, and from there the auxiliary fuel passage is The means described in the above-mentioned Japanese Utility Model Publications No. 54-87320 and Japanese Utility Model Publication No. 62-2284, which control the provided on-off valve by sending a drive signal, also control the on-off valve simply by electromagnetic force. Therefore, it is impossible to increase the amount of fuel appropriately in response to the operating conditions.

Here, if the carburetor is provided with an auxiliary fuel passage as described above in addition to the normal low-speed fuel system.

For example, when starting the engine at -20°C, increase the amount of fuel from cranking to complete explosion.

That is, the fuel flow rate to be replenished through the auxiliary fuel passage is at most 10 q in a typical automobile engine, and is about 0-8 q after complete explosion.

Therefore, in order to control fuel in this flow rate range, it is necessary to use an on-off valve with an arbitrarily variable duty ratio, but currently available electromagnetic-driven on-off valves have a maximum flow rate of up to 6 times the minimum flow rate. is within the controllable range, and may cause starting problems due to insufficient fuel during cranking or engine instability due to excess fuel after complete combustion.

Furthermore, the fuel is sucked out by the suction pipe negative and positive on the downstream side of the throttle valve, and since the fuel flow rate depends on the suction pipe negative pressure, the control of the on-off valve becomes more complicated to correct it.

The present invention was invented in order to solve these problems and provide a carburetor auxiliary/fuel supply device that can easily increase the amount of fuel appropriately over an extremely wide flow range.

(Means for Solving the Problems) The present invention provides a fuel pump and an 'I! an auxiliary fuel passage having an L magnetically driven fuel control valve in series and having an opening connected to the intake passage;
comprising an increase fuel passage having an electromagnetically driven fuel adjustment valve and branched in parallel to the auxiliary fuel passage on the downstream side of the fuel pump, and an electronic control circuit that outputs a drive signal according to the engine operating state, The fuel control valve is opened and closed according to a duty ratio of a drive signal output by the electronic control circuit.

The above problem is solved by configuring the fuel adjustment valve to be fixed at the open position during engine cranking and fixed at the closed position during other operating ranges.

(Function) When starting the engine, the fuel control valve opens and closes at a large duty ratio or is fixed at the open position during cranking, and the fuel adjustment valve is fixed at the open position. Therefore, almost all of the fuel pressurized by the fuel pump is directly injected into the °C intake passage through the fuel control valve and the fuel adjustment valve. When the engine starts to rotate by itself after cranking, the fuel control valve is fixed at the closed position, and fuel is injected into the intake passage in accordance with the duty ratio of the fuel control valve.

(Example) Embodiments of the present invention will be explained based on the drawings.

Vaporizer L Be/Chicory 2. Conventionally, a main nozzle, an idle boat, and a slow boat (not shown) are opened in the intake passage 4 having the throttle valve 3, and the main silent fuel and low-speed fuel are supplied through the fuel passage leading from the constant oil level chamber to these. It's exactly the same.

A passage provided separately from the fuel supply passage leading from the fuel tank to the constant oil level chamber, or a passage branched from the fuel pump downstream side of the fuel supply passage, is opened and connected to the intake passage 4 on the downstream side of the throttle valve 3. This passage forms an auxiliary fuel passage 5. The auxiliary fuel passage 5 serves a dedicated fuel pump 6 in the case of the above-mentioned independent passage, or serves as a fuel pump for the fuel supply passage in the case of the above-mentioned branched passage, and applies fuel pressure to its discharge side. A pressure regulator 7 is provided to keep the pressure constant, and a fuel control valve 8° jet 9 is further provided downstream of the pressure regulator 7.
are provided in order. Further, the pressure downstream of the fuel pump 6 in the auxiliary fuel passage 5 is branched into an increase fuel passage 12 having a fuel regulating valve 10 and a jet 11 in parallel.

Reference numeral 13 is an electronic control circuit such as a computer installed in the automobile that issues control commands such as air-fuel ratio and other control commands, such as throttle valve opening and engine temperature.

Appropriate drive signals are output by manually inputting engine operating state parameters such as engine speed and suction pipe negative pressure.

The fuel control valve 8 is electromagnetically driven, and the electronic control circuit 13
It is opened and closed by a drive signal consisting of a pulse wave with a predetermined duty ratio sent from the gate. The fuel adjustment valve 10 is also electromagnetically driven, and is fixed in the open position by a drive signal output when the electronic control circuit 13 determines that cranking is in progress based on the engine speed and suction pipe negative pressure. Alternatively, the valve is connected to the terminal of the starting motor and is fixed at the valve open position in synchronization with the rotation of the starting motor, and otherwise fixed at the valve closed position.

According to this embodiment with such a configuration, the engine temperature is low during cold start, and both the engine rotation speed and the suction pipe negative pressure are low during cranking, so the fuel control valve 8 is opened and closed at a large duty ratio, or is opened and closed at a large duty ratio. This valve is fixed at the valve position, and together with the fuel adjustment valve lO being fixed at the open position during cranking, a large amount of fuel pressurized by the fuel pump 6 is spouted into the intake passage 4. .

When the engine completely explodes and starts to rotate on its own, the fuel - valve regulator 1
0 is fixed at the valve closed position, and the intake passage 4 is supplied with fuel controlled by a fuel control valve 8 that opens and closes at a duty ratio according to warm-up.

It goes without saying that the duty ratio of the fuel control valve 8 is changed to an appropriate value depending on the engine temperature during cranking and the warm-up state. Furthermore, appropriate fuel replenishment is possible by opening and closing the fuel control valve 8 at an appropriate duty ratio even when it is necessary to increase the rotational speed during idling operation, or during acceleration or deceleration operation.

In the embodiment shown in FIG. 1, the control valve 8 is located downstream of the pressure regulator 7. Increase fuel passage 12 by bypassing jet 9
It has been established.

The amount of replenishment to the intake passage 4 is controlled within the range of fuel flow rate defined by the pressure V@regulator 7.

The embodiment of FIG. 2 is a pressure regulator 7. Fuel control valve8. The jet 9 is bypassed and an increase fuel passage 12 is provided, and the embodiment shown in FIG. 3 is an example in which the pressure regulator 7 is bypassed and an increase fuel passage 12 is provided. and R5 to the pressure regulator 7 (it is possible to increase the amount of fuel supplied to the intake passage 4 according to the discharge pressure of the fuel pump 6, and according to the configuration shown in FIG. 3, the fuel control valve 80
Since the inlet pressure increases, the fuel flow rate can be increased by keeping the duty ratio constant.

(Effects of the Invention) According to the present invention, since fuel pressurized by a fuel pump is supplied to the intake passage, a large amount of P and F can be stably supplied in comparison with conventional products that suck out fuel using negative pressure in the intake pipe. For this reason, flow rate control using the fuel control valve can be performed with a simple system. In addition, during cranking, a large amount of fuel is supplied to the engine through the increased fuel passage installed in parallel, ensuring a reliable start at low temperatures. By supplying fuel, warm-up is performed properly.

This allows for accurate replenishment of fuel over an extremely wide flow range.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the invention, and FIGS. 2 and 3 are schematic diagrams showing different embodiments of the invention. l... Carburetor, 4... Intake path, 5...
... Auxiliary fuel passage, 6 ... Fuel pump, 8
... Fuel control valve, 10 ... Fuel adjustment valve, 12 ... Increased fuel passage, 13 ... Electronic control circuit.

Claims (3)

[Claims] (1) An auxiliary fuel passage having a fuel pump and an electromagnetically driven fuel control valve in series and connected to the intake passage, and an electromagnetically driven fuel regulating valve that is parallel to the auxiliary fuel passage on the downstream side of the fuel pump. The fuel control valve is provided with an increase fuel passage branched into the fuel passageway and an electronic control circuit that outputs a drive signal according to the engine operating state, and the fuel control valve opens and closes according to the duty ratio of the drive signal output from the electronic control circuit. 1. An auxiliary fuel supply device for a carburetor, wherein the fuel regulating valve is configured to be fixed at an open position during cranking of the engine and fixed at a closed position during other operating ranges. (2) The device according to claim (1), wherein the increase fuel passage is provided to bypass the fuel control valve. (3) The device according to claim (1), wherein the increase fuel passage is branched in parallel to the auxiliary fuel passage on the upstream side of the fuel control valve.