JPS63285251A - Carburetor - Google Patents

Abstract

PURPOSE:To enhance the effect of removal or vapor by communicating the upper section of an auxiliary chamber communicated with a pump chamber in an accelerator pump, with a float chamber through an orifice, and by communicating the lower section of the pump chamber with the float chamber through an orifice. CONSTITUTION:The upper section of an auxiliary chamber 34 communicated with a pump chamber 32 in an accelerator pump 31 is communicated with fuel in a float chamber 6 through a communication passage 36 having an orifice 35. Further the lower section of the pump chamber 32 is communicated with fuel in the float chamber 6 through a lower section communication passage 38 having an orifice 37. With this arrangement vapor in the pump chamber may be removed efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vaporizer equipped with an accelerator pump, and particularly to measures for removing fuel vapor (hereinafter referred to as vapor) generated within the accelerator pump.

(Prior Art) Conventionally, a carburetor of an internal combustion engine (hereinafter also referred to as an engine) installed in an automobile or the like is generally equipped with an acceleration pump that compensates for over-lean air-fuel ratio during acceleration. FIG. 2 shows a longitudinal sectional view of a carburetor equipped with a diaphragm accelerator pump. 1 is the intake passage, 2 is the venturi section, 3 is the main
Nozzle, 4 is a throttle valve, and 5 is a choke valve.

6 is a float chamber, and an acceleration pump 11 is installed at the bottom of the float chamber 6.
is installed. The inside of the acceleration pump 11 is divided into a pump chamber 13 and a pressure chamber 14 by a diaphragm 12. The negative pressure in the throttle valve F region of the intake passage 1 is applied to the pressure chamber 14 by a negative pressure passage 15 .

Further, a back spring 16 is inserted into the pressure chamber 14 and biases the diaphragm 12 toward the pump 13 side.

The pump chamber 13 is provided with a fuel intake port 17 and a fuel discharge port 18 . The fuel intake port 17 communicates with the float chamber 6 via a check valve 19 that opens only when fuel is inhaled. The fuel discharge port 18 is communicated with an acceleration nozzle 21 through a fuel passage 20. A discharge side check valve 22 is provided at the inlet of the acceleration nozzle 21 and opens only when fuel is discharged. A pressure regulator 23 is provided in the upper part of the pump chamber 13 and communicates with the float chamber 6 via a communication passage 24. As shown in FIG. 5, the pressure regulator 2°3 has an outer housing 25, an inner housing 26, and a ball valve type on-off valve 27. The outer and inner housings 25 and 26 are coaxially provided with passages 25a and 26a lfi each having a throttle function. The pressure regulator 23 is set to open the passages 25a, 26a only at a pressure lower than the opening pressure of the discharge side book valve 22 and within a certain pressure range.

In the accelerator pump 11 configured as described above, when paper is generated in the fuel in the section sealed by both check valves 19 and 22, that is, the pump chamber 13 and the fuel passage 20, due to an increase in fuel temperature, paper is generated in the fuel in this section. The pressure increases, and the pressure regulator 23 opens to dispense new paper.

In this way, deterioration in the performance of the accelerator pump due to the paper and irregular enrichment of the air-fuel ratio due to the fuel blowout phenomenon are prevented.

As a prior art, there is JP-A-57-157044.

(Problems to be Solved by the Invention) However, the pressure regulating device 23 as described above has some problems.

(1) Since the valve opens only within a certain pressure range, it is not possible to cope with minute paper generation, and even in case of rapid paper generation, the initial discharge m is not sufficient, so the paper removal effect is small.

(2) Due to the tilt and vibration of the engine, the sealing of the ball valve type on-off valve 27 tends to become incomplete, causing fuel to leak into the float chamber 6.

(3) If excess paper is temporarily generated, the fuel in the pump chamber will decrease, which may result in malfunction during the next acceleration.

(4) The Mi structure is complicated, and the on-off valve requires high precision, which increases the cost.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a carburetor having a paper removing means for an accelerator pump which has a simple structure, has a great paper handling effect, and is not affected by the tilt or vibration of the engine.

(Means for solving the problem) In order to achieve the above object, the structure of the vaporizer of the present invention is as follows:
an auxiliary chamber communicating with the upper part of the pump chamber of the accelerator pump; an upper communicating path through which the upper part of the auxiliary chamber communicates with the fuel in the float chamber via a throttle; and a lower part of the pump chamber communicating with the fuel in the float chamber. It is characterized by providing a lower communication path which communicates with the lower part through the throttle.

(Function) The paper generated in the pump chamber is constantly transported from the preliminary chamber to the float chamber through the restriction of the upper communication path due to its own buoyancy. In particular, paper that has formed multiple layers due to a rapid temperature rise is temporarily stored in a preliminary chamber. Further, fuel in the float chamber is filled into the pump chamber from the lower communication passage by the amount of fuel discharged from the upper communication passage of the pump chamber. Therefore, the generated paper is removed one by one, the pump chamber is always filled with liquid fuel, and the acceleration pump always exhibits stable discharge performance.

(Example) The present invention will be described below based on drawings showing examples. FIG. 1 shows a longitudinal sectional view of a vaporizer according to the invention. Components that are the same as those in the prior art are designated by the same numbers as in FIG. 4, and explanations thereof will be omitted. The acceleration pump 31 of this invention has a pump chamber 3
A communication path 33 is provided on the upper wall of the float chamber 6 side of the float chamber 2, and a preliminary chamber 34 is provided outside of the communication path 33. Preparatory room 3
A communication passage 36 into which a throttle 35 is inserted is provided at the top of the float chamber 4 to communicate the preliminary chamber 36 with the fuel in the float chamber 6 . On the other hand, a lower communication passage 38 in which a throttle 37 is inserted is provided in the lower part of the pump chamber 32, and the lower part of the pump chamber 32 is communicated with the fuel in the float chamber 6.

In the carburetor configured as described above, when the ambient temperature is normal temperature, the pump chamber 32 of the acceleration pump 31 is filled with liquid fuel. When the acceleration pump 31 operates, the throttles 35 and 37 are set so small that their influence on the discharge efficiency can be ignored.

When the temperature around the carburetor rises and the fuel temperature in the pump chamber 32 becomes high, paper begins to form in the fuel. The paper moves to the upper part of the pump chamber 32 due to buoyancy, and the increase in internal pressure of the pump chamber 32 is also transmitted, passes through the preliminary chamber 34, and is sequentially discharged into the float chamber 6 from the upper communication passage 36. The fuel GJ discharged from the upper communication passage 36 of the pump chamber 32 and the fuel in the float chamber 6 are filled into the pump chamber 32 from the lower communication passage 38 . Therefore, the pump chamber 32
is always filled with liquid fuel even when the temperature is high, and the discharge amount of the acceleration pump 31 is stable.

Immediately after the vehicle stops, as shown in FIG. 2, the humidity A around the carburetor rapidly rises, and a large amount of paper is temporarily generated. However, this large amount of paper is temporarily stored in the preliminary chamber 34 and is sequentially discharged to the float chamber 6 through the throttle 35. To explain this with the graph of FIG. 3, graph B shows the discharge mound of the upper communication passage 36 equipped with the aperture 35. On the other hand, graph C shows the actual amount of vapor generated. Immediately after the vehicle stops, the paper in the shaded area above graph B cannot pass through the throttle 35 and is temporarily stored in the preliminary chamber 34. Therefore, even if a large amount of paper is temporarily generated immediately after the vehicle is stopped, the paper is almost completely removed from the pump chamber 32, and the accelerator pump 31 can function perfectly.

In addition, since the internal pressure of the pump chamber 32 is always at the same level as the float chamber 6, it is possible to prevent fuel from being pushed out of the acceleration nozzle 21 due to high temperatures except during acceleration, thereby preventing the air-fuel ratio from becoming irregularly overrich. This can prevent surges caused by over-richness and poor fetal movement.

The acceleration pump of the embodiment described above is a diaphragm pump C, but plunge 1! The same applies to a complete pump.

(Effects of the Invention) As explained above, the present invention provides a carburetor equipped with an accelerator pump, in which the pre-S chamber communicating with the upper part of the pump chamber of the accelerator pump and the upper part of the preliminary chamber are immersed in fuel in the float chamber. By providing an upper communication passage that communicates with the fuel in the float chamber through the throttle, and a lower communication passage that communicates the lower part of the pump chamber with the fuel in the float chamber through the throttle, it is possible to easily transfer small amounts of paper to temporary liquids. Even large amounts of paper can be removed efficiently. Therefore, even at high temperatures, the pump chamber is filled with liquid fuel, and the fuel in the pump chamber does not leak due to engine tilt or vibration, ensuring stable discharge. amount of acceleration fuel can be supplied.

Furthermore, since the internal pressure of the pump chamber is always at the same level as the float chamber, this prevents the air-fuel ratio from irregularly becoming over-rich due to the fuel being forced out of the acceleration nozzle due to high temperatures except during acceleration. This has the effect of eliminating surges and restart failures caused by over-rich conditions.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment according to the present invention, and FIGS. 2 and 3 are diagrams for explaining the operation. FIG. 4 is a longitudinal sectional view of a conventional carburetor equipped with an accelerator pump, and FIG. 5 is a detailed view of the FF force adjustment device shown in FIG. 4. 6...Flow 1-chamber 31...Acceleration pump. 32... Pump chamber 35. 37... Throttle 36... Upper communicating passage 37... Lower communicating passage

Claims (1)

[Claims] a preliminary chamber that communicates with the upper part of the pump chamber of the accelerator pump; an upper communication passage that communicates the upper part of the preliminary chamber with the fuel in the float chamber via a throttle; and the lower part of the pump chamber communicates with the fuel in the float chamber. A carburetor characterized by being provided with a lower communication passage communicating through a throttle.