JPS6131165Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an acceleration pump, in which the vapor generated in the pump chamber especially at high temperatures is returned to the float chamber, and the acceleration fuel can be discharged as usual even during acceleration at high temperatures. It concerns an accelerator pump.

Conventionally, in an acceleration pump device for a carburetor, vapor is generated in the pump chamber at high temperatures, the pressure in the pump chamber increases, and the vapor is discharged from the pump nozzle into the intake passage. For this reason,
During detsoak (engine off),
During the period from high temperature to low temperature, vapor was released from the pump nozzle into the intake passage.
As a result, when the engine is restarted at a high temperature, the air-fuel mixture supplied to the engine becomes too rich due to the vapor released into the intake passage, resulting in a problem that the engine starts slowly.

In order to overcome this drawback, an acceleration pump has been proposed in which a passage for vapor release is provided between the pump chamber and the float chamber, and the passage is equipped with a heat-sensitive valve means that opens the passage only when the temperature is high. but,
With this configuration, during acceleration at high temperatures, the pressure within the pump chamber escapes to the passage, making it impossible to discharge sufficient acceleration fuel.

The present invention was developed in view of the above points, and includes a bimetal valve that forms a passage communicating between the pump chamber and the upper part of the float chamber, closes the passage at low temperatures, and opens it at high temperatures. By closing the return passage with the internal pressure in the pump chamber when the accelerator pump is activated, the vapor generated at high temperatures can always escape from the float chamber, thereby improving startability at high temperature restarts. In addition, the acceleration fuel can be sufficiently discharged even during acceleration at high temperatures. Hereinafter, the present invention will be explained based on the drawings.

The attached drawing is a sectional view showing an embodiment of the accelerator pump according to the present invention. Pump chamber 1 of acceleration pump 10
2 communicates with the float chamber 14 through a passage 16, and an inlet check valve 18 is provided in the middle of the passage 16 to allow flow to pass in only one direction from the float chamber 14 to the pump chamber 12. The pump chamber 12 also has a pump nozzle 21 that opens into the carburetor intake passage 20 through a passage 19.
An outlet check valve 22 is provided in the middle of the passage 19 to allow flow in only one direction from the pump chamber 12 to the pump nozzle 21 to pass through. One side of the pump chamber 12 is formed by a diaphragm 24, which is constantly pressed outward by a spring 26 disposed inside the pump chamber 12. The diaphragm 24 has an actuating pin 28 that projects outwardly.
is fixed, and the actuating pin 28 is pressed by an actuating lever 30 that interlocks with a throttle valve shaft (not shown). That is, the actuating lever 30 moves the diaphragm 24 in the direction that compresses the pump chamber 12 during acceleration.
is pressed, the outlet check valve 22 opens, and acceleration fuel is discharged from the pump nozzle 21. Thereafter, as the operating lever 30 returns, the diaphragm 24 also returns, and at this time, the inlet check valve 18 opens and fuel is supplied from the float chamber 14 to the pump chamber 12.

Although the configuration described above is the configuration of a conventionally known acceleration pump, in the present invention, the pump chamber 12
A return passage 32 is provided between and above the float chamber 14 (a position above the oil level), and a throttle 33 and a valve chamber 34 are formed in the middle of the return passage 32. A bimetal valve 36 and its valve seat 38 for closing and opening the return passage 32 are provided in the valve chamber 34. This bimetallic valve 36 is approximately 40°C to 50°C, which is the initial boiling point of the fuel.
The setting is such that the return passage 32 is closed at temperatures below that and opened at temperatures above that temperature. Further, this bimetal valve 36 is made of a flexible material or has a very thin thickness, and is set to immediately close the return passage 32 by the internal pressure in the valve chamber 12 during acceleration. . Further, it is preferable that this bimetal valve 36 be supported on a cantilever as shown in the figure.

With the above structure, at temperatures below the initial boiling point, that is, at low temperatures, the bimetal valve 36
always closes the return passage 32, and in the acceleration pump according to the present invention, fuel in the pump chamber 12 is discharged from the pump nozzle 21 into the intake passage 20 during acceleration, similar to conventionally known ones. On the other hand, at temperatures above the initial boiling point, that is, at high temperatures, the bimetal valve 3
6 opens the return passage 32. As a result,
The vapor generated in the pump chamber 12 during the desoak is returned to the float chamber 14 through the return passage 32, and the vapor is transferred to the pump nozzle 21.
There will be no more emissions from the air. Therefore,
When the engine is restarted at a high temperature, the air-fuel mixture supplied to the engine does not become too rich, and good drivability can be obtained.

Also, when accelerating at high temperatures, the pump chamber 12
The internal pressure inside increases, and the bimetal valve 36 is immediately pressed toward the valve seat 38 side by the pressure, and the return passage 32 is closed. At the same time, the inlet valve 18 is opened, and acceleration fuel is discharged from the pump nozzle 21 into the intake passage 20, making it possible to obtain fuel discharge characteristics similar to those of a conventional acceleration pump.

As described above, according to the present invention, a return passage is provided that communicates the upper part of the pump chamber and the float chamber, and the return passage is closed off when the temperature is low and is opened when the temperature is high, and the indoor pressure inside the pump chamber is By installing a bimetallic valve that shuts off the return passage when the pump temperature rises, vapor generated in the pump chamber at high temperatures is released, improving operability during high-temperature restarts, and when accelerating at high temperatures. The fuel tank can also discharge fuel in the same way as before.

[Brief explanation of the drawing]

The attached drawing is a sectional view showing an embodiment of the accelerator pump according to the present invention. 12...Pump chamber, 14...Float chamber, 16
... Inlet check valve, 21 ... Pump nozzle, 22 ... Outlet check valve, 24 ... Diaphragm, 30 ... Operating lever, 32 ... Return passage, 36 ... Bimetal valve.

Claims (1)

[Scope of utility model registration request] It has a passage for supplying fuel from the float chamber to the pump chamber via the inlet check valve, and a passage for supplying fuel from the pump chamber to the pump nozzle via the outlet check valve, and operates the pump driving means. In an accelerator pump that discharges fuel in a pump chamber from a pump nozzle, a return passage is formed that communicates the pump chamber with the upper part of the float chamber, and in the middle of the return passage, the return passage is closed when the temperature is low, and when the temperature is high, the return passage is closed. An acceleration pump characterized in that a bimetallic valve is disposed to open a return passage, and the bimetallic valve is operated to close a return passage by indoor pressure in a pump chamber when a pump driving means is operated at a high temperature.