JPH01151730A - Auxiliary fuel feed device for engine - Google Patents

Abstract

PURPOSE:To perform proper control of a fuel flow rate through simple and low-cost constitution, by a method wherein a control valve being electromagnetically driven according to the running state of an engine and a regulating valve driven by means of a fuel pressure are situated in juxtaposition, and a regulating valve is driven by means of the outlet pressure of the control valve. CONSTITUTION:In a vaporizer 1, an auxiliary fuel passage 5 is connected to an intake air passage 4 having a venturi 2 and a throttle valve 3, and a fuel pump 6, a pressure regulator 7, and a control valve 8 are situated, in order named, in the auxiliary passage 5. An increase fuel passage 10 is branched from the auxiliary fuel passage 5 and connected to an intake air passage 4, and a regulating valve 11 is mounted in the increase fuel passage 10. In this case, The control valve 8 is controlled by an electronic type control circuit 13. Meanwhile, the regulating valve 11 is driven by means of the outlet pressure of the control valve 8. When the control valve 8 is opened and closed in a duty ratio higher than a given value and the outlet pressure thereof is increased to a value higher than a given value, the regulating valve 11 is opened.

Description

Detailed Description of the Invention (Industrial Field of Application) This invention relates to an auxiliary fuel supply device for increasing the amount of fuel supplied to the 8 AFi engine of the present invention, and is mainly used for low-temperature starting of automobile engines. be done.

(Conventional technology) In the air supply device that supplies fuel to the engine.

It has been considered to provide an auxiliary fuel passage with an electromagnetically driven on-off valve in place of a choke mechanism, idle-up mechanism, acceleration mechanism, etc.
(See Publication No. 0 and Publication No. 62-2284).

Also, in the fuel injection system that supplies fuel to the engine, 9. It is also widely known to provide a separate fuel injection valve to supply fuel during cold start.

(Problems to be Solved by the Invention) The on-off valve installed in the auxiliary fuel passage of the carburetor disclosed in each of the above-mentioned publications is set to the open position by a command from an electronic control circuit into which the engine operating state is input. Alternatively, since the valve is only fixed at one of the valve open positions, it is not possible to increase the amount of fuel appropriately depending on the state of the engine.

Also, what is the appropriate increase in fuel when starting a normal automobile engine at 120C?

It takes about 10 Jh from cranking to complete detonation, and about 0.8 VL after complete detonation. Therefore, in fuel injection systems, electromagnetically driven fuel control valves, which can control a maximum flow rate up to 6 times the minimum flow rate currently provided, cannot handle this. Equipped with an injection valve. especially.

Installing such a separate fuel injector in a single-point injection system can accommodate the wide range of fuel flow rate changes required by a supercharged engine, but it requires the installation of two expensive fuel injectors. Therefore, it is economically disadvantageous. Furthermore, in both single-point and multi-point injection systems, when fuel is increased, the regular fuel injection valve must also be driven for fuel control, making the control system unavoidably complicated. .

In view of these circumstances, the present invention combines - electromagnetically driven control valves with a regulating valve driven by fuel pressure to appropriately control a wide range of fuel flow rates with an inexpensive and simple control system. This invention was developed with the object of providing an auxiliary fuel supply system for an engine that can be used as an engine fuel supply system.

(Means for Solving the Problems) The present invention provides an auxiliary fuel passage having a fuel pump and an electromagnetically driven control valve and opening into an intake passage.

The increase fuel passage includes an increase fuel passage having a regulating valve driven by fuel pressure and opening into the intake passage, and an electronic control circuit that sends a drive signal of a duty ratio according to the engine operating state to the control valve. is branched from the auxiliary fuel passage between the fuel pump and the control valve.

The regulating valve is driven by the outlet pressure of the control valve, and is opened and closed when the control valve is opened and closed at a duty ratio greater than a set value, and the outlet pressure becomes greater than a predetermined value. The above-mentioned problem was solved as the ninth means of T6.

(Function) When the control valve is fixed at the closed position, the regulating valve is also closed. When the control valve starts opening/closing, the
An amount of fuel is injected into the intake passage through the auxiliary fuel passage in accordance with the tee ratio. As the duty ratio increases, the outlet pressure of the control valve gradually increases, and when it exceeds a predetermined value, the regulating valve suddenly opens wide.

The control valve is held at the fully open position in a region where the duty ratio is large.

(Embodiment) An example in which the present invention is implemented in a 1ζ device will be explained with reference to the drawings.

Venturi of carburetor 2. Intake path 4 with throttle valve 3t-i
The king nozzle, idle boat, and slow boat (not shown) are opened, and the main fuel and low-speed fuel are supplied from the constant oil level chamber through the fuel passage leading to these, just as in the conventional case.

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 supply passage downstream of the fuel pump, is connected to the intake passage 4 between the pentier 2 and the throttle valve 3. This passage forms an auxiliary fuel passage 5. The auxiliary fuel passage 5 includes a dedicated fuel pump 6 in the case of the above-mentioned independent passage, and a fuel pump 6 which also serves as the fuel pump of the fuel supply passage in the case of the above-mentioned branched passage, and has a fuel pump 6 on its discharge side. Pressure regulator 7 to keep constant
, an electromagnetically driven control valve 8 are provided in this order.

t+, an increase fuel passage 10 is provided between the pressure regulator 7 and the control valve 8, which branches off from the auxiliary fuel passage 5, and which opens and connects to the intake passage 4 between the pentier 2 and the throttle valve 3. The passage 10 is a regulating valve 1 that changes the degree of opening steplessly.
1. Furthermore, these auxiliary fuel passages 5.10
The opening to the intake passage 4 is a jet 9 that regulates the amount of fuel jetted.
．． It has 12.

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

Parameters of engine operating conditions such as engine rotational speed and negative pressure in the a-inlet pipe are input, and a drive signal consisting of a pulse wave with a predetermined duty ratio is sent to the control valve 8.

Regulating valve 11 is driven by fuel pressure.

That is, in the embodiment shown in FIG. 1, among the two chambers partitioned by the diaphragm 14 to which the regulating valve 11 is fixed, the working chamber 15 that applies a force in the valve opening direction is connected to the auxiliary fuel passage 5 on the downstream side of the control valve 8. The other chamber is an atmospheric chamber 18 containing a valve closing spring 16.

Further, the other chamber partitioned off from the atmospheric chamber 18 by the wall 19 is installed in the middle of the increase fuel passage 10 and is connected to the regulating valve 11.
0 inlet chamber 17 is formed.

The fuel pressurized by the fuel pump 6 and adjusted to a constant pressure by the pressure regulator 7 is supplied to the control valve 8. The flow rate is controlled by the J regulating valve 11, and the air is ejected from the jet 9.12 into the intake passage 4.

When the control valve 8 is fixed in the closed position.

Since fuel is not introduced into the downstream working chamber 15, the regulating valve 11 is also fixed at the closed position by the spring force of the valve closing spring 16. When the control valve 8 starts its opening/closing operation in response to a drive signal sent from the electronic control circuit 13, fuel at a flow rate corresponding to the duty ratio is ejected into the intake passage 4 through the auxiliary fuel passage 5, and the fuel in the working chamber 15 is injected. The pressure and the fuel flow rate from the jet 9 change according to the duty ratio, as shown by curves P1 and 8 in FIG. Further, when the fuel pressure in the nine working chambers 15 overcomes the spring force of the valve closing spring 16, the regulating valve 11 opens, and a flow rate of fuel corresponding to the degree of opening is injected into the intake passage 4 through the increase fuel passage 10. do.

At this time, when the duty ratio increases, the fuel pressure in the working chamber 15 increases and the opening degree of the regulating valve 11 is increased.Therefore, the fuel pressure in the inlet chamber 17 decreases, and the regulating valve 11 becomes easier to open.

The fuel pressure on the downstream side of the regulating valve 11 and the fuel flow rate from the jet 12 change as shown in the P8 curve and C curve in Figure 3, and the regulating valve ■ suddenly opens wide and becomes fully open in a region with a large duty ratio. Retained.

The fuel flow rate injected into the intake passage 4 becomes the human curve in Figure 3, which is the sum of B and C mentioned above, and reaches the maximum flow rate when the control valve 8 is fixed at the open position and the regulating valve 11 is at its maximum opening. .

By changing the spring characteristics of the valve-closing spring 16, it is possible to change the opening degree of the regulating valve 11 for the same duty ratio of the control valve 8 or change the timing at which the regulating valve 11 starts opening.

According to such a configuration, when the engine is started at a low temperature, the control valve 8 is fixed at the open position or opened and closed at a large duty ratio to perform crank younging, and when a complete explosion occurs, the de- and -ti ratios of the control valve 8 are changed. By making it suddenly smaller.

By appropriately increasing the amount of fuel, reliable starting and stable warm-up can be achieved. Also.

It is possible to appropriately increase the amount of fuel by opening and closing the control valve 8 at an appropriate duty ratio during idle up, acceleration, high load operation, and the like.

In the embodiment shown in FIG. 2, the regulating valve 11 is fixed to two diaphragms 20, 21 having different effective areas and arranged in parallel, diaphragm m.

21 forms an atmospheric chamber 22, the first working chamber 15 applies fuel pressure to the first diaphragm J having a large effective area, and the inlet chamber 17 containing a valve closing spring 16 forms a second diaphragm J having a small effective area. The structure is such that fuel pressure is applied to the diaphragm 21 of the engine.

According to this embodiment, the regulating valve 1 responds to the pressure increase in the working chamber 15
1 responds sharply and opens with a small duty ratio of the control valve 6.

Note that the present invention can be applied to single-point type or even multi-point type fuel injection systems, and in these cases, the control valve 8, which functions as a regular fuel injection valve, is equipped with the regulating valve 1.
It is constructed by installing 1.

(Effects of the Invention) According to the present invention, a control valve that opens and closes based on a drive signal with a duty ratio corresponding to the engine operating state and a regulating valve that opens and closes based on fuel pressure are provided in parallel, and the regulating valve is controlled by the outlet pressure of the control valve. Since the valve is configured to open when the value of It is possible to make a very large change in the fuel flow rate for a small change. Therefore, an inexpensive and simple control system using - electromagnetically driven control valves can appropriately control the fuel flow rate over a wide range, and ensure that the engine can be started at low temperatures and warmed up in a reliable and stable manner. .

[Brief explanation of the drawing]

1 and 2 are configuration diagrams showing different embodiments of the present invention, and FIG. 3 is a diagram showing changes in fuel pressure and fuel flow rate with respect to the duty ratio of the control valve. 4...Intake passage, 5...Auxiliary fuel passage. 6...Fuel pump, 8...Control valve, lO...Increase fuel passage, 11...Adjustment valve, 13...Electronic type control circuit, 15.
...Working chamber, 16...Valve closed
Hey, 17...Entrance room.

Claims (1)

[Claims] An auxiliary fuel passage (5) that has a fuel pump (6) and an electromagnetically driven control valve (8) and is open to the intake passage (4), and an intake passage (5) that has a regulating valve (11) driven by fuel pressure. 4), and an electronic control circuit (13) that sends a drive signal with a duty ratio according to the engine operating state to the control valve (8).
10) is branched from the auxiliary fuel passage (5) between the fuel pump (6) and the control valve (8), and the regulating valve (11) is controlled by the outlet pressure of the control valve (8). An auxiliary fuel supply device for an engine, characterized in that the control valve (8) is opened and closed at a duty ratio equal to or higher than a set value, and the valve is opened when the outlet pressure becomes equal to or higher than a predetermined value.