JPS59103948A - High-temperature startability improving device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent difficulty of the engine start at a high temperature by releasing fuel vapor into the atmosphere when percolation occurs. CONSTITUTION:A temperature sensing chamber 50 with its lower limit set by an inner case 40 is formed in an outer case 41 of a temperature sensing valve 39, and a snap-like bimetal plate 51 is arranged in the temperature senging chamber 50. While an engine is stopped, the second diaphragm chamber 30 of a vapor control valve 20 is kept at the atmospheric pressure, a diaphragm 28 is pushed to the right by the pressing force of a compression coil spring 36, and a valve body 38 opens a valve port 26. When the temperature of an engine room chamber is a predetermined value or higher, the bimetal plate 51 is turned round in an upward convex shape, thereby a valve body 48 opens a valve port 47, and fuel vapor is released into the atmosphere through vapor bleed pipes 25, 56, 57.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a device for improving high temperature startability of an internal combustion engine.

In an internal combustion engine with a carburetor, when the temperature in the engine room is high, fuel vapor is generated in the fuel passage and main well of the carburetor, and the pressure of the fuel vapor pushes liquid fuel out of the main nozzle. The air-fuel ratio may become too rich, making it difficult to start the engine. This phenomenon is called ``nomer coalescence'', and conventional countermeasures have been to provide a vapor bleed passage that communicates the main well with the atmosphere, and to remove the fuel vapor generated in the main well and the fuel passage. It was proposed to be released during popular demand. However, with this method, when the vehicle is normally running, that is, in the operating range of the main nozzle, air is sucked from the vapor bleed passage due to the ventri negative pressure acting on the main nozzle, reducing the amount of fuel discharged from the main nozzle. However, a problem arises in that the engine malfunctions. Additionally, when the temperature in the engine room is low and the Chirok valve is closed, air is sucked in from the vapor bleed passage due to the venturi negative pressure acting on the main nozzle, and fuel is no longer discharged from the main nozzle, causing the engine to A problem arises in that the required rich mixture cannot be obtained.

The purpose of the present invention is to ensure fuel discharge from the main nozzle even when the vehicle is normally running and when the engine valve is closed, and at the same time to release fuel vapor to the atmosphere when percolation occurs. An object of the present invention is to provide a device for improving high temperature startability of an internal combustion engine, which prevents difficulty in starting the engine at high temperatures.

According to the present invention, the invention comprises a diaphragm device having a vapor bleed passage connected to the main well of the vaporizer at one end and open to the atmosphere at the other end, and a working chamber, the pressure of which is approximately a vapor control valve that opens only at atmospheric pressure;
and a temperature sensing valve that opens only when the temperature in the engine room is above a predetermined value, and the vapor control valve and the temperature sensing valve are interposed in series in the middle of the vapor bleed passage, and An orifice is interposed in the middle of the vapor bleed passage, the working chamber of the diaphragm device is communicated with the intake manifold through a negative pressure passage, and a check valve and an orifice are interposed in the middle of the negative pressure passage. The stop valve is achieved by a device for improving high temperature startability of an internal combustion engine, which is characterized in that it only allows air to flow from the working chamber toward the intake manifold.

Next, embodiments of the present invention will be described in detail based on the drawings. The figure shows an embodiment of a device for improving high-temperature startability of an internal combustion engine according to the present invention. In the same figure, an intake manifold 33 is attached to the engine body 58, and the intake manifold 33 has carburetors 1 and 1 in sequence in the upstream direction.
and an air cleaner 54 are attached. The intake passage 2 of the carburetor main body 1 is provided with a Chirok valve 3, a small venturi 4, a large venturi 5, and a throttle valve 6 in this order from upstream. There is. The main nozzle 7 is connected to a main well 8, and the main well 8 is communicated with a float chamber 10 via a fuel passage 9. A fuel gauge 11 for measuring the amount of fuel is arranged between the fuel passage 9 and the float chamber 10. An air bleeder 12 is loosely inserted into the main well 8, and an orifice 13 is provided at the upper end of the air bleeder 12. Furthermore, the air bleeder 12 is provided with a large number of small holes 14, and the air that enters from the orifice 13 and enters the main well 8 through the small hole I4 mixes with the fuel in the main well 8 to form an emulsion town. be done. A slow boat 15 and an idle boat 1 are located near the throttle valve 6.
6 are provided, and these boats communicate with the fuel passage 9 via a slow fuel passage 17. A vapor bleed hole 18 is formed in the side wall of the main well 8 to release fuel vapor into the atmosphere, and an orifice 19 is provided in the vapor bleed hole 18 . The vapor control valve 2° consists of a valve housing 21 and a diaphragm device 22. Inside the valve housing 21, a first chamber 23 and a second chamber 24 are defined by a partition wall 59, and the second chamber 24 communicates with the vapor bleed hole 18 through a vapor bleed pipe 25. The partition wall 59 has the first chamber 2
A valve boat 26 is bored through which the valve port 3 and the second chamber 24 communicate with each other. The diaphragm device 22 includes a diaphragm case 2
It has a first diaphragm chamber 29 and a second diaphragm chamber 30, each of which is partitioned by a diaphragm 28.

The first diaphragm chamber 29 is constantly communicated with the atmosphere through the atmosphere communication hole 31. The second diaphragm chamber 30 is communicated with an intake manifold 33 via a negative pressure passage 32, and an orifice 34 and a check valve 35 are interposed in the middle of the negative pressure passage 32. The check valve 35 only allows air to flow from the second diaphragm chamber 30 toward the intake manifold 33. Inside the second diaphragm chamber 30 is a compression coil spring 3 that presses the diaphragm 28.
6 is placed. A rod 37 that slidably penetrates the walls of the diaphragm case 27 and the valve housing 21 and extends into the first chamber 23 is connected to the diaphragm 28, and the tip of the rod 37 opens and closes the valve boat 26. A valve body 38 is attached for this purpose. Temperature sensing valve 39
consists of an inner case 40 and an outer case 41,
The inner case 40 is screwed into the outer case 41 with screws 42 and fixed by bending a collar 43 provided at the lower end of the outer case 41 inward. Inner case 4
0, an artificial passageway 44 and an exit passageway 45 are bored,
These communicate with each other in an inner chamber 46 provided within the inner case 40. An outlet passage 45 projects from the inner chamber 46 to form a valve boat 47, which is opened and closed by a valve body 48. A compression coil spring 49 is disposed within the inner chamber 46 to press the valve body 48 in a direction in which the valve body 48 opens the valve boat 47 . Inside the outer case 41 is a sensitive chamber 50 whose lower limit is limited by the inner case 40.
is formed, and a snap-shaped bimetal plate 51 is arranged inside the sensitive chamber 50. The bimetal plate 51 is
"C" is reversed depending on the temperature.A rod 52 is attached to the valve body 48.
The rod 52 is loosely inserted into a communication hole 53 that communicates the inner chamber 46 and the sensitive room 50, and
The rod 52 extends inward, and the tip of the rod 52 is in contact with the center of the bimetal plate 51 . The entire temperature sensing valve 39 is attached to the air cleaner 54 so that the outer case 41 faces the clean side 55 of the air cleaner 54. Entrance passage 4
4 communicates with the first chamber 23 of the vapor control valve 20 via a vapor bleed pipe 56, and the outlet passage 45 communicates with the clean side 55 of the air cleaner 54 via a vapor bleed pipe 57.

The operation of the above embodiment will be explained. When the engine is stopped, the inside of the intake manifold 33 is at atmospheric pressure, so the second diaphragm chamber 30 of the vapor control valve 20 is also at atmospheric pressure. Therefore, the diaphragm 28 is pushed rightward by the pressing force of the compression coil spring 36, so that the valve body 38 opens the valve boat 26. At this time, if the temperature in the engine room is above a predetermined value (percolation generation temperature of the carburetor), the snap-shaped bimetallic plate 51 of the temperature sensing valve 39 is inverted into an upwardly convex shape, so that the valve The body 48 opens the valve boat 47 by the pressing force of the compression coil spring 49. When the temperature in the engine room is high, the temperature of the carburetor main body 1 is also high, so fuel vapor is generated in the main well 8 and the fuel passage 9, and as described above, this fuel vapor flows through the vapor control valve 20. And since the temperature sensing valve 39 is open, it is released into the atmosphere via the vapor bleed pipe 25, 56, 57. In this way, the internal pressure in the main well 8 is reduced, liquid fuel is no longer forced out of the main nozzle 7 due to the pressure of fuel vapor, the air-fuel ratio is maintained at an appropriate level, and the engine can be started easily. Also, during engine cranking, venturi negative pressure acts on the main nozzle 7, but since the vapor control valve 20 and temperature sensing valve 39 are open, the atmosphere flows through the vapor bleed pipe 25, 56, 57 to the main nozzle. 7 into the small venturi 4. Therefore, fuel vapor and liquid fuel are prevented from being discharged from the main nozzle 7, the air-fuel ratio is maintained appropriately, and the engine starts easily. When the engine starts, intake pipe negative pressure is generated in the intake manifold 33, and the second vapor control valve 20
Since the air in the second diaphragm chamber 30 flows into the intake manifold 33 immediately after opening the check valve 35, the inside of the second diaphragm chamber 30 becomes negative pressure. Therefore, the diaphragm 28 is attracted to the left against the pressing force of the compression coil spring 36, so that the valve body 38 closes the valve boat 26. Thus, when the vehicle is running, the venturi negative pressure acting on the main nozzle 7 causes the vapor bleed pipe 25,56,57
Since air is sucked in from the main well 7, the amount of fuel discharged from the main well 7 does not decrease, and engine malfunction does not occur. Here, the check valve 35 is configured so that when the inside of the intake manifold 33 becomes atmospheric pressure due to acceleration of the vehicle, the second diaphragm chamber 30 of the vapor control valve 20 becomes atmospheric pressure and the valve boat 26 is opened. In connection with the provision of the check valve 35, the orifice 34 is provided to prevent when the vehicle is stopped.
It is provided to bring the second diaphragm chamber 30 of the vapor control valve 20 to atmospheric pressure and open the valve boat 26 in preparation for restarting the engine. Note that the vapor bleed hole 18 is provided with an orifice 19 for the following reason. That is, when the vehicle is running, the venturi negative pressure acting on the main nozzle 7 pulsates due to turbulence in the air flowing through the small venturi 4. It is conceivable that fuel flows backward through the vapor bleed hole 18 and adheres to the vapor bleed pipe 25 due to the pulsation of the internal pressure of the main well 8 based on the pulsation of the venturi negative pressure. Normally, the vapor bleed pipe 25 is made of an elastic material such as rubber, but since rubber has the property of swelling and deteriorating when fuel (gasoline) adheres to it, the backflow of this fuel is prevented as much as possible. This is because it is necessary to do so. Note that if the diameter of the orifice 19 is made too small,
In order to inhibit the discharge of fuel vapor when percolation occurs, its diameter is determined to a value that satisfies both the above-mentioned fuel backflow prevention and fuel vapor discharge to a practical extent.

When the temperature in the engine room is lower than a predetermined value (the temperature at which the carburetor burns out), the snap-shaped bimetallic plate 51 of the temperature sensing valve 39 is inverted in a downwardly convex shape. The valve body 4 due to the reversing force of 51
8 is a valve boat 47 resisting the pressing force of a compression coil spring 49.
is closed. Therefore, even when the engine is warming up and the temperature sensing valve 3 is closed, it is natural that the temperature sensing valve 3
9 is closed. Thus, even when the engine is started with the check valve 3 closed, air is sucked in from the vapor bleed pipe 25, 56, 57 due to the venturi negative pressure generated by cranking the engine. This is not the case, and as fuel is discharged from the main nozzle 7 as before, the rich air-fuel mixture required by the engine is ensured.

As described above, according to the device for improving high temperature startability of an internal combustion engine according to the present invention, the main well of the carburetor is opened to the atmosphere via the vapor bleed passage, and when the engine is operating and inside the engine room. Since the vapor bleed passage is closed when the temperature of the engine is below the temperature at which percolation occurs, the engine will not malfunction even when the vehicle is running normally or the engine is warming up, and the engine will stop. When the temperature is such that percolation occurs, the fuel vapor is released to the atmosphere, which has the effect of preventing engine starting problems due to over-enriched air-fuel mixture.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram of an embodiment of an apparatus for improving high-temperature startability of an internal combustion engine according to the present invention. 1-"--Vaporizer 8-----Main well 1B--Vapor bleed hole (vapor bleed passage) +9--Orifice 20-----Vapor control valve 22-1 - Diaphragm device 25.56.57 ---- Babe bleed pipe (vapor bleed passage) 30 - - Second diaphragm chamber (operating chamber) 32
---Negative pressure passage 34 --- Orifice 35 --- Check valve 39 --- Temperature sensing valve

Claims (1)

[Claims] One ring is connected to the main well of the vaporizer, and the other end is equipped with a vapor bleed passage opened to the atmosphere and a diaphragm device having an operating chamber, and a vapor control valve that opens only when the pressure in the operating chamber is approximately atmospheric pressure. and a temperature sensing valve that opens only when the temperature in the engine room is above a predetermined value, the vapor control valve and the temperature sensing valve are interposed in series in the middle of the vapor bleed passage, and the vapor control valve and the temperature sensing valve are disposed in series in the vapor bleed passage, and the vapor control valve and the temperature sensing valve are disposed in series in the vapor bleed passage, and An orifice is interposed in the middle of the vapor bleed passage, the working chamber of the diaphragm device is communicated with the intake manifold through a negative pressure passage, and a check valve and an orifice are interposed in the middle of the negative pressure passage. A device for improving high temperature startability of an internal combustion engine, wherein the check valve only allows air to flow from the working chamber toward the intake manifold.