JPS6233977Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a temperature opening/closing valve for opening and closing an outer vent passage connecting a float chamber and a canister in an engine carburetor according to temperature.

Generally, the fuel vapor generated in the float chamber of the carburetor when the engine is stopped is
The fuel is guided to the canister through the outer vent passage and adsorbed to facilitate the starting of the next engine. A temperature opening/closing valve is provided that connects the outer vent passage only when the condition is such that the outer vent passage is in a state where Therefore, it has a built-in bimetal reversible valve plate that closes the outer vent passage in a dish-shaped state when the temperature is low, but when the temperature rises, it reverses to the opposite dish-shaped state and opens the outer vent passage. Temperature shut-off valves are used.

However, this temperature on/off valve using a bimetallic reversible valve plate shaped like a plate opens and closes the passage by reversing and returning the reversible valve plate. Although it has the advantage of being able to open and close rapidly depending on the temperature, it has hysteresis in the reversing and returning operations of its reversible valve plate, and the reversible valve plate reverses as the temperature rises. The reversal operating temperature T1 when the reversible valve plate reverses to the dish-shaped state and becomes fully open, and the temperature when the reversible valve plate returns to the original dish-shaped state as the temperature decreases and becomes fully closed. Since the return operating temperature T2 differs depending on the hysteresis of the bimetal as shown in FIG. There are problems as described below.

In other words, if the operating temperature of the temperature on/off valve from the closed state to the open state is set at the reversal operating temperature T1 at which the reversible valve plate reverses to the opposite dish shape as the temperature rises, the temperature on/off valve will be When the temperature decreases, it becomes closed at a temperature T2 lower than the reversal operation temperature T1, and during that time, the float chamber and the canister are in communication, and only low boiling point components in the fuel in the float chamber are evaporated. In addition, the fuel in the float chamber will be oxidized and deteriorated, which may make it difficult to start the engine in this state or cause the engine to stop immediately after starting. In addition, if the temperature at which the temperature on/off valve closes is set at the return operating temperature T2 when the reversible valve plate returns to its original dish shape as the temperature decreases,
When the temperature rises, the temperature opening/closing valve becomes open at a temperature T1 higher than the return operating temperature T2, and during that time, the float chamber and the canister are out of communication, and the fuel vapor generated in the float chamber is released. Since it cannot be adsorbed by the canister, all the fuel vapor generated in the float chamber of the carburetor flows out into the intake manifold and accumulates, which reduces the starting performance the next time you start the engine. I will do it.

If a bimetallic temperature sensing valve like the one described above is installed in the outer vent passage connecting the float chamber of the carburetor and the canister, the float chamber of the carburetor and the canister will always be in communication after the engine has started. As a result, the negative intake pressure in the intake manifold acts on the float chamber,
The amount of fuel supplied to the carburetor will fluctuate, or the amount of evaporated fuel adsorbed to the canister will increase more than necessary.

The object of the present invention is to solve the above-mentioned problems in a temperature control valve using a bimetallic reversible valve plate having hysteresis.

Therefore, in the present invention, when the temperature is low, the outer vent passage from the float chamber to the canister is blocked in a dish-shaped state, but when the temperature rises, the outer vent passage is reversed into a dish-shaped state. A temperature switching valve having a built-in bimetallic reversible valve plate communicating with the outer vent passage is provided, and the temperature switching valve is configured to heat the bimetallic reversible plate valve at the time of starting the engine. An electric heating coil is provided, and a start-up blockage valve, which is closed when the engine is started, is provided in the outer vent passage in series with the temperature sensing valve.

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, reference numeral 1 denotes an intake manifold, 4 a canister connected to the intake manifold 1 and a fuel tank (not shown) through passages 2 and 3, and 5 a canister connected to the intake manifold 1 and a fuel tank (not shown). Each carburetor attached to the intake manifold 1 is shown, and the upper part of the float chamber 6 in the carburetor 5 is connected to the canister 4 via an outer vent passage 7.

In the outer vent passage 7, a temperature opening/closing valve 8, which will be described in detail later, and an electromagnetic start/close valve 21 which is closed during engine operation and opened when the engine operation is stopped are provided in series.

The temperature opening/closing valve 8 is constituted by two valve cases 9 and 10 which are caulked together as shown in FIG. , 12, a disc-shaped valve seat body 13 is attached inside the valve seat body 13, and an annular valve seat 14 made of rubber or the like is provided on the outer periphery of the surface of the valve seat body 13 that faces one of the valve cases 9.
A valve plate seat 15 also made of rubber or the like is provided in the center, and a plurality of through holes 16 are provided in the valve seat body 13 on the inner diameter side of the valve seat 14 to communicate the valve cases 9 and 10 with each other. We are prepared. Further, a reversible valve plate 17 formed of a bimetal plate and shaped like a downward dish is inserted into one of the valve cases 9, and the reversible valve plate 17 is supported by a spring 18 in the valve case 9 The reversible valve plate 17 is pressed against the seat 14 so as to close the through hole 16, and when the temperature rises, the reversible valve plate 17 inverts into an upward dish shape as shown by the two-dot chain line, and closes the through hole 16. is configured to open.

An electric heating coil 1 is provided at an appropriate location on the outside or inside of one or both of the valve cases 9 and 10 in the temperature on/off valve 8.
9, and the electric heating coil 19 is configured to be energized when the engine starting switch 20 is turned on.

The electric heating coil 19 is equipped with a PTC thermistor that shuts off electricity when the electric heating coil 19 reaches a certain temperature.

In this configuration, when the starting switch 20 is turned on when starting the engine, the electric heating coil 19 provided in the temperature shut-off valve 8 is energized at the same time as the engine starts, and the reversible valve plate 17 of the temperature shut-off valve 8 is forcibly turned on. Since it is heated, the reversible valve plate 17 is reversed from the solid line state to the two-dot chain line state to open the through hole 16.
Also, when the engine starts, the starting blockage valve 21
By closing, it is ensured that the intake negative pressure in the intake manifold 1 will not act on the float chamber 6 of the carburetor 5 after the engine has started, and that more evaporated fuel than necessary will be adsorbed in the canister 4. This can be avoided.

When the engine is stopped when the temperature of the engine or its surroundings becomes high enough to evaporate fuel in the float chamber 6 of the carburetor 5 due to engine operation, the start block valve is installed in the engine due to the stoppage. 21 opens, and the outer vent passage 7 communicates with the electric heating coil 1 in the temperature on/off valve 8.
9 is cut off. In this case, since the reversible valve plate 17 keeps the through hole 16 open unless the temperature of itself and the surrounding area decreases, the fuel vapor generated in the float chamber 6 of the carburetor 5 is transferred to the outer vent passage 7. Since fuel vapor is sequentially adsorbed to the canister 4 via the fuel vapor, it is possible to prevent fuel vapor from accumulating in the intake manifold 1.

After the engine has stopped, when the temperature of the engine or its surroundings drops to a temperature at which fuel evaporation in the float chamber 6 is reduced, the reversible valve plate 17 returns from the state shown by the two-dot chain line to the state shown by the solid line. Since the mold is returned and the through hole 16 is closed, communication between the float chamber 6 and the canister 4 is cut off.

In this case, when the temperature on-off valve 8 is not provided with the electric heating coil 19, the temperature on-off valve 8
The bimetallic reversible type opens only when the temperature rises after the engine starts, and the temperature at which it opens as the temperature rises and the temperature at which it closes as the temperature falls are different from that of the bimetallic reversible type. Since the difference occurs due to the hysteresis in the valve plate 17, the above-mentioned problems occur.

On the other hand, if the temperature opening/closing valve 8 is provided with an electric heating coil 19 that is energized when the engine is started, and is opened by heating by this electric heating coil 19, the temperature opening/closing valve 8 Hysteresis in the bimetallic reversible valve plate 17 can be reduced by setting the temperature at which the reversible valve plate 17 closes at the return operating temperature T2 at which the reversible valve plate 17 returns to its original dish shape as the temperature decreases. This allows you to avoid problems caused by

That is, according to the present invention, a temperature opening/closing valve with a built-in bimetallic reversible valve plate is used in the outer vent passage from the float chamber to the canister in the carburetor so that the outer vent passage can be rapidly opened and closed. This makes it possible to reliably avoid deterioration in engine startability due to the hysteresis of the bimetallic reversible valve plate, which was a problem in the previous case, and significantly improve engine startability. be.

Moreover, according to the present invention, there is a problem that occurs due to the provision of a bimetallic temperature sensing valve in the outer vent passage, that is, the amount of fuel supplied to the carburetor fluctuates due to negative intake pressure in the intake manifold acting on the float chamber. The start-up blockage valve provided in the outer vent passage has the effect of reliably preventing the fuel vapor adsorbing into the canister from increasing more than necessary.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a diagram showing the main parts of the engine, FIG. 2 is a longitudinal sectional front view of the temperature control valve, FIG. 3 is a cross-sectional view taken from the side of FIG. 2, and FIG. is a diagram showing hysteresis in a bimetallic reversible valve plate. 1...Intake manifold, 4...Canister,
5... Carburizer, 6... Float chamber, 7... Outer vent passage, 8... Temperature opening/closing valve, 9, 10... Valve case, 13... Valve seat body, 17... Reversible valve plate,
21...Start-up blockage valve.

Claims (1)

[Scope of utility model registration request] In the outer vent passage from the float chamber to the canister in the carburetor, when the temperature is low, the outer vent passage is shaped like a saucer, blocking the outer vent passage, but when the temperature rises, it turns into the opposite dish shape and opens the outer vent passage. A temperature on/off valve having a built-in bimetallic reversible valve plate is provided, and the temperature on/off valve is provided with an electric heating coil that heats the bimetallic reversible plate valve upon starting the engine; 1. A temperature opening/closing valve device for an outer vent passage in a carburetor, characterized in that a start-up shutoff valve, which is closed when the engine is started, is provided in the outer vent passage in series with the temperature sensing valve.