JPH0528372Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention improves the air-fuel ratio by controlling the fuel flow rate to maintain a constant liquid level in the negative pressure passage for detecting the intake flow rate, which communicates with the fuel passage. This invention relates to a fuel supply device that properly maintains the fuel.

[Conventional technology]

Conventionally, there is a device of this type as shown in FIG. 5, for example, in which 1 indicates an intake passage, 2
3 is a fixed bench lily; 3 is an air valve capable of opening and closing the intake passage 1; 4 is a negative pressure actuator having a diaphragm 4a and controlling the operation of the air valve 3; 5;
6 is a negative pressure intake port communicating with the negative pressure chamber 4b of the negative pressure actuator 4 and opening on the downstream side of the air valve 3;
7 is a control valve that can be turned on and off by the negative pressure introduced into the negative pressure chamber 6a through the negative pressure intake port 5, and can introduce atmospheric air into the negative pressure chamber 4b of the negative pressure actuator 4 through the valve 6b. A throttle valve 9 is provided on the downstream side of the air valve 3 via a throttle shaft 8; 9 is a slow-flow vent lily; 10 is a throttle valve for supplying fuel to the fuel chamber 11 in order to maintain the liquid level in the fuel chamber 11 at a reference level; A solenoid valve 12 is a level sensor for detecting the liquid level in the fuel chamber 11, 13 is a main jet, and 14 is a slow system vent 9 in the middle after the slow system passage 14a and the main system passage 14b join together.
and ports 14c and 14d that open to the intake passage 1
A fuel passageway 16 communicating with the slow port 15 controls the flow rate of fuel from the main jet 13 based on the output signal from the level sensor 18 so that the height of the fuel column 17a in the negative pressure passageway 17 is constant. 19 is a solenoid valve that controls the flow rate of fuel from the pilot jet 22 based on the output signal of the level sensor 21 so that the height of the fuel column 20a in the negative pressure passage 20 is constant. .

In this device, the air valve 3 closes the intake passage 1 in the slow range of the engine, but
When the negative pressure on the downstream side of the air valve 3 reaches a predetermined value, the negative pressure introduced into the negative pressure chamber 6a of the control valve 6 through the negative pressure intake port 5 causes the valve 6 to
b isolates the negative pressure chamber 4b of the negative pressure actuator 4 from the atmosphere and introduces negative pressure into the negative pressure chamber 4b. As a result, the air valve 3 is connected to the intake passage 1.
begins to open, resulting in a transition from the slow area to the main area.

[Problem that the invention attempts to solve]

The relationship between the intake air flow rate and the negative pressure on the downstream side of the air valve 3 in such a conventional device is expressed as shown in FIG. In this case, the negative pressure controlled by the air valve 3 needs to be set small in order to prevent the output from decreasing near the maximum engine output when the throttle valve is fully opened. However, as shown in FIG. 6, when such a controlled negative pressure is made small, it is not possible to set a large amount of intake air on the downstream side of the air valve 3. Therefore, there is a problem in that the range in which the liquid level can be controlled based on the detection signals of the level sensors 18 and 21 with respect to the amount of intake air is limited.

In addition, since liquid level control cannot be performed in such a region where the amount of intake air is large, the level sensor 18
When the negative pressure inside the fixed bench lily 2 exceeds a certain value in the main system liquid level control using the detection signal,
This negative pressure causes fuel to be discharged from the tip of the negative pressure passage 17, that is, in a region where the negative pressure passage 17 functions as a normal naturalizing device, there is a problem in that the metering accuracy of the discharged fuel cannot be ensured.

In view of this situation, the present invention has been developed to ensure a wide range in which the liquid level can be controlled for the negative pressure on the downstream side of the air valve, thereby making it possible to control even in areas where the amount of intake air is large, thereby reducing the negative pressure in the fixed bench lily. It is an object of the present invention to provide a fuel supply device that can prevent fuel from being discharged from the tip of a negative pressure passage until a value necessary to ensure accuracy is reached.

[Means and actions for solving problems]

In the fuel supply device according to the present invention, the negative pressure chamber of the negative pressure actuator or the negative pressure chamber of its control valve is communicated with a passage leading to the atmosphere,
The passage is adapted to be opened and closed in response to rotation of the throttle shaft. Therefore, after the throttle valve begins to open, the negative pressure chamber of the negative pressure actuator is communicated with the atmosphere until it reaches a predetermined opening degree, and the air valve closes the intake passage, during which time the negative pressure downstream of the air valve is maintained. Since the fuel is not discharged from the end of the negative pressure passage into the stationary bench lily, proper liquid level control is achieved, and when the throttle valve opens, the negative pressure chamber of the negative pressure actuator is removed from the atmosphere. Since the air valve is shut off, the air valve opens, and the negative pressure on the downstream side of the air valve decreases temporarily, but at this time, the throttle valve is relatively open to nearly full opening, so the air valve is able to secure the intake air necessary for maximum output. It is possible to control the negative pressure on the downstream side.

〔Example〕

Hereinafter, an embodiment of the fuel supply device according to the present invention will be described based on FIGS. 1 to 4, using the same reference numerals for the same members as in the conventional example.
23 is a passage that can be opened and closed at one end to communicate with the atmosphere by the rotation of the throttle shaft 8, and the other end communicates with the negative pressure chamber 4b of the negative pressure actuator 4; 24 is formed in the throttle shaft 8; This notch is arranged so that when the opening degree of the throttle valve 7 is relatively small, the above-mentioned one end of the passage 23 is opened (see Fig. 2), and when the opening degree exceeds a predetermined value, it is closed (see Fig. 3). .

Since the fuel supply system according to the present invention is constructed as described above, first, the air valve 3 that closes the intake passage 1 in the slow region of the engine is configured.
The negative pressure on the downstream side of the throttle shaft 8 increases as the intake air flow rate increases by gradually opening the throttle valve 7 from the idling state (region A in Fig. 4). Since the notch 24 opens the passage 23, the negative pressure actuator 4 does not operate, and the air valve 3 maintains the closed state of the intake passage 1. In this case, the negative pressure in the fixed bench lily 2 is relatively low because the absolute amount of intake air is small because it is in the slow region, and the negative pressure downstream of the air valve 3 does not directly affect the fixed bench lily 2. Since it is small, fuel is not discharged from the tip of the negative pressure passage 17, and appropriate liquid level control can be performed. Further, when the throttle valve 7 opens and reaches a predetermined opening degree, the throttle shaft 8 itself opens the passage 23.
is closed (FIG. 3), and as a result, the negative pressure chamber 4b of the negative pressure actuator 4 is cut off from the atmosphere, so that the air valve 3 begins to open the intake passage 1. The opening timing can be set as desired by adjusting the shape of the notch 24, etc., and is given as a displacement point B in FIG. 4 in relation to the intake air flow rate. That is, at this point, the throttle valve 7 has reached a predetermined opening degree and the air flow rate itself has increased relatively, so if the throttle valve 7 is fully opened, the amount of intake air required for maximum output will be sufficient. can be secured. Further, after the displacement point B, the negative pressure on the downstream side of the air valve 3 becomes smaller due to the opening of the intake passage 1, and from this point onwards, the air valve 3 is closed until the throttle valve 7 is fully opened.
When the opening degree of the valve 3 reaches near full open, the negative pressure on the downstream side of the valve 3 is not increased more than necessary, and the pressure on the downstream side is controlled so that the maximum air flow rate is always obtained. In this way, the range in which the liquid level can be properly controlled can be expanded, and the intake air flow rate can be controlled so that the maximum output is always obtained.

Here, the passage 23 may be communicated with the negative pressure chamber 6b of the control valve 6, as shown by the two-dot chain line in FIG. 1, and in this case, when the throttle valve 7 reaches a predetermined opening The negative pressure chamber 6b is shut off from the atmosphere and is actuated by the negative pressure on the downstream side of the air valve 3. As a result, the air valve 3 begins to open the intake passage 1 via the negative pressure actuator 4 based on the negative pressure. , as in the above embodiment, when the throttle valve 7 is fully open at maximum output, the liquid level controllable range can be maintained without increasing the negative pressure on the downstream side of the air valve 3 more than necessary and without reducing the maximum output. Can be expanded. In any of the above cases, the shape, size, etc. of the notch portion 24 may be appropriately selected, and similar effects can be obtained.

[Effect of idea]

As mentioned above, the fuel supply device according to the present invention has the following features:
This type of liquid level control can be performed effectively even when the throttle valve is fully open, and has the advantage that a sufficient intake flow rate required for maximum output can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an embodiment of the fuel supply device of the present invention, and FIGS. 2 and 3 are partial sectional views showing an atmosphere introduction passage and an opening/closing notch of the passage according to the present invention. Fig. 4 is a graph showing the relationship between the intake air flow rate and the negative pressure downstream of the air valve according to the present invention, Fig. 5 is a sectional view showing the structure of a conventional fuel supply device, and Fig. 6 is a graph showing the structure of the conventional fuel supply device. It is a graph showing the relationship between the intake air flow rate and the negative pressure on the downstream side of the air valve. 1...Intake passage, 2...Fixed bench lily, 3...
...Air valve, 4...Negative pressure actuator, 6...
... Control valve, 7 ... Throttle valve, 8 ... Throttle shaft, 9 ... Slow system bench lily, 10, 16, 19 ... Solenoid valve, 14 ... Fuel passage, 17, 20 ... Negative pressure passage, 23... Passage, 24... Notch.

Claims (1)

[Claims for Utility Model Registration] A main system negative pressure passage that communicates with the fuel passage and opens into the fixed bench lily, and a slow system negative pressure passage that communicates with the fuel passage via the pilot jet and opens into the slow system bench lily. and a solenoid valve is disposed in each of the main system and slow system fuel passages communicating with the main system and slow system negative pressure passage, respectively, and the main system and slow system fuel passages are merged on the downstream side thereof. An air valve that is opened at the discharge port and that can properly control the air-fuel ratio by controlling the fuel flow rate so as to keep the liquid level in each negative pressure passage constant using the solenoid valve, and can also open and close the intake passage. In a fuel supply device configured to control a negative pressure actuator for an air valve by a control valve that operates based on negative pressure downstream of the air valve, one end communicates with the atmosphere and the other end connects to the negative pressure chamber of the negative pressure actuator or The opening and closing of the communication passage communicating with the negative pressure chamber of the control valve is controlled by the rotation of the throttle shaft so that the opening is opened when the opening of the throttle valve is small and closed when the opening is larger than a predetermined opening. A fuel supply device characterized in that the operating negative pressure on the downstream side of an air valve is controlled.