JPS5833259Y2 - automatic fuel cock - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fuel cock that automatically opens and closes when the engine is started or stopped.

Conventionally, this type of automatic fuel cock has a small diaphragm that receives fuel pressure and a double diaphragm that receives negative pressure, as shown in Figure 1, to ensure that the fuel valve is open during operation and closed when the engine is stopped. It is composed of

This is because the intake negative pressure becomes weaker when the throttle valve is fully open and the engine is running at low speeds, and on the other hand, sufficient fuel must be supplied.
In order to reliably keep the fuel valve open with this weak intake negative pressure, the diaphragm that receives the negative pressure is made thicker, while the fuel diaphragm is made smaller to reduce the influence of the force due to fuel pressure.

A check valve is installed in the passage that introduces negative intake pressure to prevent engine pulsation and to utilize strong intake negative pressure.
A leak is provided to release negative pressure and close the fuel valve when the engine stops.

Therefore, since there is this leak in the conventional one,
There was a limit to the use of strong intake negative pressure, which caused problems such as the fuel valve not opening sufficiently in areas where intake negative pressure was weak, and fuel leaking when the engine stopped. .

In view of these problems, the present invention eliminates the leak and installs a new negative pressure pulp to maintain strong intake negative pressure.This allows the use of a strong spring and reduces the closing force of the fuel valve. As a result, the outer diameter of the diaphragm can be reduced, contributing to miniaturization.

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 is a sectional view of a conventional automatic fuel cock, where 1 is the cock body, 2 is the fuel inlet joint, 3 is the fuel reservoir, 4 is the filter, 5 is the filter holder, and 6 is the cover fixed to the cock body with screws. be done.

7 is a fuel passage, 8 is a fuel outlet joint, 9 is a fuel valve,
10 is a fuel diaphragm, 11 is a tightening screw for attaching the diaphragm to the cock body, 12 is an atmospheric chamber, 13 is an atmospheric opening hole, 14 is a negative pressure diaphragm, 15 is a pressure chamber, 16
17 is a spring, 17 is a check valve, 18 is a negative pressure introduction joint, and 19 is a leak.

To explain the operation of this conventional example, fuel from the fuel tank passes through the inlet joint 2, enters the fuel reservoir 3, and enters the filter 4.
It is sent to the carburetor from the outlet joint 8 as shown by the arrow.

The figure shows the state during operation, but the intake negative pressure is the check valve 17.
The fuel enters the pressure chamber 15 through the diaphragm 14 and opens the fuel valve 9.

In this case, it is desirable to have a strong spring force when considering closing the fuel valve, but there is a certain limit to maintaining the open state with negative intake pressure, and when full-open low-speed operation continues for a long time, such a spring force is necessary. Even with weak intake negative pressure, the fuel valve must be opened sufficiently to enable fuel supply.

As described above, it is impossible to fully satisfy the conditions for opening and closing the fuel valve with one spring, and as a result, various problems occur as described above.

Figure 2 shows an embodiment of the present invention. The same parts as in Figure 1 are designated by the same reference numerals. 1 is the cock body, 3 is the fuel reservoir, 7 is the fuel passage, 8 is the fuel outlet joint, and 9 is the fuel valve. It is supported by a diaphragm 14 and always urged in the closing direction by a spring 16.

Reference numeral 15 denotes a pressure chamber into which intake negative pressure is introduced via a check valve 17 and a negative pressure introduction joint 18 .

Reference numeral 20 denotes a newly installed switching valve device, which has a switching valve chamber 22 partitioned by a diaphragm 21 inside, and a spring 23 installed in the chamber.
is accommodated, and the switching valve 24 fixed to the diaphragm is normally biased in the open direction.

25 is a passage that communicates the pressure chamber 15 and the chamber 22, and is opened and closed by the valve 24.

A passage 26 communicates with the switching valve chamber 22 and a negative pressure introduction passage upstream of the check valve 17.

The operation will be explained based on the above configuration.

Although the figure shows the engine stopped, the fuel valve 9 is connected to the spring 1.
6 closes the passage 7, while the valve 24 of the switching valve device 20 opens the passage 25 by the spring 23, and the pressure chamber 15 is opened to the atmosphere via passages 26 and 18.

When the engine is started in this state, the intake negative pressure is reduced by the check valve 17.
It opens and exerts an effect on the pressure chamber 15, but at the same time it also reaches the switching valve chamber 22 via the passage 26, and the diaphragm is pulled against the spring 23, causing the switching valve 24 to block the passage 25.

Therefore, strong negative pressure remains in the pressure chamber 15 via the check valve, and since there is no leakage, this negative pressure is maintained during engine operation, so even if the spring 16 is strengthened, the fuel valve 9 It opens sufficiently and does not cause any inconvenience to fuel supply.

Furthermore, the sizes of the spring 23 and diaphragm 21 of the switching valve device 20 are set so as to close the passage 25 even when the intake negative pressure is very weak, such as when the engine is fully open and at low speed. 25 is never opened, maintaining negative pressure in the pressure chamber.

When the engine is stopped, the switching valve 24 immediately opens the passage 25 and releases the negative pressure in the pressure chamber 15, so that the strong spring 1
6 quickly closes the passage 7 against the fuel pressure exerted on the diaphragm 14.

In this way, a strong residual negative pressure can be maintained in the pressure chamber while the engine is operating, so a strong spring can be used for the diaphragm 14, so the diaphragm area does not become large, and it can be closed against the fuel pressure sufficiently. In particular, the performance is stable and the structure is simple even without the use of a fuel diaphragm with a small area.

Note that the present invention uses a plurality of diaphragms as shown in the conventional example.

Of course, it can also be applied to a cock, and in this case, the opening and closing of the fuel valve becomes even more reliable.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a conventional automatic fuel cock, and FIG. 2 is a cross-sectional view of essential parts of an automatic fuel cock showing an embodiment of the present invention. 1... Cock body, 4... Filter, 9... Fuel valve, 10, 14... Diaphragm, 15... Pressure chamber, 18...
Negative pressure introduction joint, 20...Switching valve device.

Claims (1)

[Scope of utility model registration request] A spring 16 is housed in a pressure chamber 15 having a diaphragm 14 as one wall, a fuel valve 9 for opening and closing the fuel passage T is fixed to the diaphragm, and the fuel valve 9 is normally biased in the closing direction by the spring 16. At the same time, intake negative pressure is introduced into the pressure chamber 15 via the check valve 17, and the switching valve chamber 2 is introduced from the middle of the negative pressure introduction path upstream of the check valve.
One wall of the switching valve chamber 22 is constituted by a diaphragm, and a switching valve 24 fixed to the diaphragm opens and closes a passage 25 communicating between the switching valve chamber 22 and the pressure chamber 15. The automatic fuel cock further includes a spring 23 that biases the switching valve 25 in the opening direction.