JPS6054497B2 - Carburetor acceleration fuel supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carburetor for an internal combustion engine such as an automobile, and more particularly to an acceleration fuel supply device that compensates for an air-fuel ratio during acceleration.

In an internal combustion engine equipped with a carburetor, when the throttle valve is opened rapidly to rapidly accelerate the engine, the amount of air flowing through the carburetor bore increases immediately in accordance with the opening degree of the throttle valve at that time. However, because the inertia of fuel (gasoline) is greater than that of air, there is a delay in response to an increase in air flow rate, and there is a slight time delay before fuel is sucked out from the main nozzle in response to the increase in air flow rate. be.

For this reason, there is a problem in that the air-fuel mixture supplied to the engine becomes lean in the early stages of acceleration, making it impossible to obtain good acceleration performance. Also, if the mixture becomes thinner temporarily during acceleration,
This prevents exhaust gas purification devices such as the Ξ catalytic converter from working properly, and can also cause deterioration in exhaust gas performance. As mentioned above, there is a tendency for the air-fuel mixture to become lean for a certain period at the beginning of acceleration, rather than when the vehicle is accelerating while the vehicle is running, but after the throttle valve is kept at the idling opening for a certain period of time, such as when the vehicle is stopped or decelerating. This is noticeable during acceleration, and during such acceleration, the drivability of the vehicle is particularly deteriorated and harmful emissions are increased.

To address the above-mentioned problem, additional fuel is supplied into the carburetor bore from a fuel system separate from the main fuel system only during the period when the mixture becomes lean when accelerating from a stopped or decelerating state. Various acceleration fuel supply devices have been proposed so far that prevent the air-fuel mixture from becoming lean.

One of its basic components is a negative pressure operated pump that pumps up liquid fuel when negative pressure is applied to the diaphragm chamber and discharges the pumped liquid fuel when the negative pressure is released;
an accelerating nozzle that directs fuel from the discharge port of the negative pressure operated pump into the carburetor bore; and an acceleration nozzle that connects the diaphragm chamber to a negative pressure source when the throttle valve is at an idling opening and otherwise connects the diaphragm chamber to a negative pressure source. It has a valve device connected to an atmosphere release port, and a restriction element that restricts the flow of fluid between the diaphragm chamber and the negative pressure source, and the throttle valve is connected to the idle link when the vehicle is stopped or decelerated. While the opening position is continuously held for a certain period of time, negative pressure from a negative pressure source is applied to the diaphragm chamber to pump up liquid fuel, and then during acceleration when the throttle valve is opened. A negative pressure-operated acceleration fuel supply device is known that temporarily supplies the pumped liquid fuel as acceleration fuel into the carburetor bore through the acceleration nozzle. A negative pressure operated accelerating fuel supply device having such a basic configuration is usually provided with a suitable restricting element in the middle of a fluid passage connecting the diaphragm chamber to the atmosphere opening boat via the valve device, and the restriction of this restricting element is By adjusting the rate, the discharge duration of a constant amount of fuel discharged by the negative pressure pump in one discharge can be adjusted, thereby providing additional fuel for acceleration over time. The aim is to optimize the aspect.

However, in this case, if the continuation of the supply of additional fuel for acceleration is made relatively long and the degree of restriction of the throttle element is increased, the time delay until the additional fuel for acceleration starts to come out becomes large, and conversely, this time delay increases. If the degree of restriction of the throttle element is relaxed in order to shorten the period, the duration of supply of additional fuel for acceleration becomes shorter, and it may not be possible to optimally adjust both this time delay and the duration of supply.

The present invention makes it possible to independently optimally adjust both the time delay and duration of acceleration fuel supply as described above in a negative pressure operated acceleration fuel supply device having the basic configuration as described above. It is an object of the present invention to realize an accelerating fuel supply system that does this by adding an extremely simple configuration to the basic configuration of the above-mentioned negative pressure-operated accelerating fuel supply system.

According to the present invention, such a purpose is achieved by the above-mentioned negative effects. In the pressure-actuated accelerating fuel supply device, a second throttle element is provided between the valve device and the atmosphere opening boat, and an air storage chamber is further provided between the second throttle element and the valve device. This is achieved by providing

According to this configuration, when the throttle valve is opened from the idling opening degree and the valve device is switched to a position where the diaphragm chamber is connected to the atmosphere open boat, the air stored in the air storage chamber is first discharged. Because it is immediately supplied to the diaphragm chamber, the vacuum-operated pump can immediately supply a designed amount of fuel into the carburetor bore without any substantial delay, followed by the Air enters the diaphragm chamber of the vacuum-operated pump via the second restricting element at a designed flow rate, thereby providing an accelerated fuel supply with a designed duration. . Therefore, in this case, by independently setting the volume of the air storage chamber and the degree of throttling of the second throttling element, it is possible to determine the amount of fuel to be supplied immediately without delay when supplying acceleration fuel, and the amount of fuel to be supplied immediately without any delay time. The supply duration of the fuel to be subsequently supplied gradually can be adjusted separately. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings.

The attached drawing schematically shows the structure of a carburetor equipped with an accelerating fuel supply system according to the present invention.

The carburetor body 1 has an intake bore 2 . A bench lily 3 is provided within the intake bore 2, and a main nozzle 4 is provided at the throat of this bench lily 3. The main nozzle 4 communicates with a float chamber 5 formed in the body 1 through a fuel passage (not shown), and is supplied with gasoline fuel stored in the float chamber 5. There is. Further, a throttle valve 6 is provided on the downstream side of the intake bore 2 with respect to the vent lily so as to be rotatable about a throttle valve shaft 7 as a rotational fulcrum. A negative pressure operated pump 8 is configured in a part of the body 1 .

The negative pressure operated pump 8 has a pump chamber 9, a diaphragm chamber 11 separated from the pump chamber 9 by a diaphragm 10, and is located within the diaphragm chamber 11 with the diaphragm 10 located on the left side in the figure, that is, as shown in FIG. The pump chamber 9 is provided with a compression coil 12 that biases the inner volume of the pump chamber 9 toward a side that decreases the internal volume. On one side, the pump chamber 9 communicates from its fuel inlet 13 to the float chamber 5 via a fuel passage 14, and in the middle of the fuel passage 14, there is only a flow of fuel from the float chamber 5 to the pump chamber 9. A check valve 15 is provided to allow this. On the other hand, the diaphragm chamber 9 is connected to the bench lily 3 via a fuel passage 17 from its fuel discharge port 16.
It communicates with an acceleration nozzle 18 which is open inward. A check valve 19 is provided in the middle of the fuel passage 17 to allow only fuel to flow from the pump chamber 9 toward the acceleration nozzle 18 . The diaphragm chamber 11 of the negative pressure operated pump 8 has either an intake pipe negative pressure take-out boat 21 or an atmosphere release boat 22 opened into the intake bore 2 on the downstream side of the throttle valve 6 by a valve device 20 to be described later. are becoming selectively connected to

The valve device 20 is a three-way electromagnetic switching valve having three boats 20a to 20c. The boat 20a is connected to the intake pipe negative pressure take-out boat 21 through a conduit 23, and the boat 20b is connected to the atmosphere release boat 22 through a conduit 24. , boats 20c are each connected to the diaphragm chamber 11 via conduits 25. A first constriction element 26 is provided in the middle of the conduit 23 to throttle the flow of fluid flowing through the conduit. Further, a second throttle element 27 is provided in the middle of the conduit 24, and the second throttle element 27 allows the valve device 2 to
An air storage chamber 28 that can accommodate a predetermined volume of air is provided on the 0 side. In this case, the second throttle element 27 and the air storage chamber 28 are integrally constructed.
A current supplied from the battery power supply 29 to the electromagnetic coil (not shown in the diagram) of the valve device 20 is connected to the throttle switch 30.
The valve device 20 is selectively supplied through the boat 20 when the electromagnetic coil is energized.
When the electromagnetic coil is not energized, the valve device 20 connects the boats 20b and 20c and closes the boat 20a. There is. The throttle switch 30 is configured to close the circuit when the throttle valve 6 is at the idling opening position, and open the circuit at other times. The carburetor acceleration fuel supply system constructed as described above operates as follows.

When the throttle valve 6 is in the idling opening position, the valve device 20 connects the boats 20a and 20c, and therefore, at this time, the intake pipe negative pressure appearing in the intake pipe negative pressure take-out boat 21 is transferred to the conduit. 23, the first throttle element 26, the valve device 20, and the conduit 25 are transmitted to the diaphragm chamber 11 of the vacuum-operated pump 8, and the negative pressure causes the diaphragm 10 to move against the action of the helical compression spring 12. It is biased to the right at .

As the diaphragm 10 shifts to the right in the drawing, the internal volume of the pump chamber 9 increases, and the fuel stored in the float chamber 5 passes through the fuel passage 14 and the check valve 15 to the fuel intake port 13. The pump chamber 9 is filled by suction. When the throttle valve 6 is opened from the idling position in order to accelerate the engine in such a state, the valve device 20 connects the boat 20c to the boat 20b instead of the boat 20a, so that the diaphragm chamber 11 opens. Atmospheric release boat 2 replaces the intake pipe negative pressure takeout boat 21
2 will be connected.

Then, the second throttle element 27, the conduit 2 male valve device 20, and the conduit 25 are transferred from the atmosphere opening boat 22 into the diaphragm chamber 11.
Atmospheric air is introduced through the diaphragm chamber 11, and the negative pressure in the diaphragm chamber 11 gradually decreases due to the throttling action of the second throttling element 27.
In this case, when the boat 20c of the valve device 20 is connected to the boat 20b, the air previously stored in the air storage chamber 28 is immediately introduced into the diaphragm chamber 11, so that the negative pressure in the diaphragm chamber 11 is reduced. , and then gradually decreases due to the throttling action of the second throttling element 27 . Therefore, at the same time as the diaphragm 10 accelerates, the gasoline fuel in the pump chamber 9 is rapidly shifted to the left side in the figure by a predetermined amount, and as a result, at the same time as the diaphragm 10 accelerates, the gasoline fuel in the pump chamber 9 is first shifted by a predetermined amount to the fuel discharge port 16, the check valve 19, and the fuel passage. 17
The fuel is then discharged from the acceleration nozzle 18 into the intake bore 2, and then the diaphragm 10 gradually deviates to the left in the figure, thereby gradually discharging the fuel.This prevents a delay in the start of fuel discharge from the pump. and additional fuel discharge during acceleration is maintained for a certain period of time.Negative pressure operated pump 8
When the diaphragm chamber 11 of the diaphragm chamber 11 is opened to the atmosphere and all the gasoline fuel in the pump chamber 9 is discharged, the throttle valve 6 of the negative pressure operated pump 8 returns to the idling opening position.
Gasoline fuel is not drawn into the pump chamber 9 from the float chamber 5 until a substantial intake pipe negative pressure is introduced into the diaphragm chamber 11.

In this case, since the first throttle element 26 is provided in the middle of the conduit 23j, even if the throttle valve 6 is returned to the idling opening for a very short period of time, such as during a gear change or frequent acceleration/deceleration, No negative pressure is introduced into the diaphragm chamber 11 that overcomes the action of the compression coil spring 12 and causes the diaphragm 10 to be biased to the right in the drawing. Therefore, at this time, the negative pressure operated pump 8 does not suck gasoline fuel into its pump chamber 9, and does not send gasoline fuel toward the acceleration nozzle 18 even if the throttle valve is opened. Although the present invention has been described in detail with respect to specific embodiments above, it will be understood by those skilled in the art that the present invention is not limited thereto, and that various embodiments are possible within the scope of the present invention. It should be obvious.

[Brief explanation of the drawing]

The attached figure is a sectional view schematically showing the structure of a carburetor equipped with an accelerating fuel supply system according to the present invention. 1 - carburetor body, 2 - intake bore, 3 - bench lily,
4-main nozzle, 5-float chamber, 6-throttle valve, 7-throttle valve shaft, 8-negative pressure operated pump, 9-pump chamber, 10-diaphragm, 11-diaphragm chamber, 12-compression coil spring, 13 ~Fuel inlet, 1
4-Fuel passage, 15-Check valve, 16-Fuel discharge port, 17
~Fuel passage, 18~Acceleration nozzle, 19~Check valve, 20~
Valve device, 21 - intake pipe negative pressure extraction boat, 22 - atmospheric release boat, 23, 24, 25 - conduit, 26 - first throttle element, 27 - second throttle element, 28 - air storage chamber, 29
~ Battery power, 30 ~ Throttle switch.

Claims (1)

[Claims] 1. A negative pressure operated pump that pumps up liquid fuel when negative pressure is applied to the diaphragm chamber and discharges the pumped liquid fuel when the negative pressure is released; an accelerating nozzle that directs fuel into the carburetor bore; a valve device that connects the diaphragm chamber to a negative pressure source when the throttle valve is at an idling opening and otherwise connects the diaphragm chamber to an atmosphere release port; a first throttle element that throttles the flow of fluid flowing between the diaphragm chamber and the negative pressure source; a second throttle element provided between the atmosphere release port and the valve device; An accelerating fuel supply device for a carburetor, comprising an air storage chamber provided between a throttle element and the valve device.