JPH0564448U - Vaporizer - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the delay of the main fuel from the main nozzle 5 during the transition of vehicle acceleration to eliminate breathing during the transition. A main nozzle pump 12 that discharges fuel when the negative pressure in the intake pipe downstream of the throttle valve 3 becomes small is provided, and its discharge port 21 is connected to a main fuel passage 8 between a main jet 7 and a main well 9.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of a carburetor for an internal combustion engine of an automobile.

[0002]

[Prior Art]

 In this type of carburetor, fuel is supplied to the intake passage from the slow system, the main system and the acceleration system.

The main system fuel has a structure in which it is mixed with bleed air by an air bleed shaft from a float chamber through a main jet and a main well, and is supplied from a main nozzle to a venturi portion of an intake passage.

Further, the acceleration fuel is discharged from the acceleration pump to the intake passage through an acceleration nozzle different from the main nozzle.

[0005]

[Problems to be solved by the device]

 The above-mentioned conventional technique has a problem that the main system fuel supplied from the main nozzle is delayed and breathes during the transient period in which the throttle valve is opened to accelerate the vehicle from the medium to low speed operation. This is because in the main system, air with a small mass precedes in the transition period, and fuel with a large mass lags behind and is discharged from the main nozzle, and it is not possible to catch up only by increasing the amount from the acceleration system.

Therefore, an object of the present invention is to provide a carburetor capable of reducing the delay of the fuel supplied from the main nozzle during such a transition period and eliminating breathing.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the carburetor of the present invention is provided with a main nozzle pump (12) which discharges fuel when the negative pressure in the intake pipe downstream of the throttle valve (3) becomes small, and the discharge port (21) of the main nozzle (21) is provided. It communicated with the main fuel passage (8) between 7) and the main well (9).

[0008]

[Action]

 When the throttle valve (3) is opened to accelerate from the medium to low speed operation, the negative pressure in the intake pipe decreases and the main nozzle pump operates to discharge fuel from its outlet to the main fuel passage (8). Therefore, the fuel pressure in the main fuel passage rises, the fuel level in the main well rises, and the main fuel discharged from the main nozzle is immediately increased.

[0009]

【Example】

 In FIG. 1, 1 is a carburetor body, 2 is an intake passage, 3 is a throttle valve, 4 is a small venturi, 5 is a main nozzle opening to the small venturi 4, 6 is a float chamber, 7 is a main jet, and 8 is a main fuel. A passage, 9 is a main well, 10 is an air bleed tube, and 11 is an air bleed jet. Since these structures are the same as those of a known vaporizer, detailed description thereof will be omitted.

Reference numeral 12 denotes a main nozzle pump, which is a diaphragm 13, a spring 14 for urging the diaphragm 13 downward, a diaphragm chamber 15 formed above the diaphragm 13, and an atmosphere hole 16 formed below the diaphragm 13 to communicate with the atmosphere. An air chamber 17, a piston 19, which is connected to the center of the diaphragm 13 at the upper end of the rod, and which is fitted and slid into a cylinder inner wall 18 formed in the carburetor body, a pump chamber 20 surrounded by the piston 19 and the cylinder inner wall 18, and a pump. The chamber 20 comprises a discharge port 21 which communicates with the main fuel passage 8, and the diaphragm chamber 15 communicates with an intake pipe downstream of the throttle valve 3 by a passage 22.

In the above-described embodiment, since the intake pipe negative pressure applied to the diaphragm chamber 15 is large in the medium to low speed operation, the diaphragm 13 is in a position where it is raised against the spring 14 as shown in FIG.

When the throttle valve 3 is suddenly opened at time t ₀ in FIG. 2 to accelerate the vehicle, the intake pipe negative pressure is rapidly reduced, so that the diaphragm 13 is pushed by the spring 14 and descends together with the piston 19. The fuel in the pump chamber 20 is discharged from the discharge port 21 to the main fuel passage 8, the fuel level in the main well 9 immediately rises, and the fuel increased from the main nozzle 5 is discharged to the small venturi 4.

At this time, the air-fuel ratio of the air-fuel mixture supplied to the engine follows a rapid decrease in the intake pipe negative pressure, as indicated by the dotted line B in FIG. This series of operations is used to improve the transient response as the opening speed of the throttle valve 3 becomes faster.

The solid line C in FIG. 2 shows the change in the air-fuel ratio of the conventional vaporizer without the known mechanical acceleration pump as in the above embodiment, and is compared with the dotted line B in the case of the present invention. It is clear that the change in the air-fuel ratio is delayed.

The change in the air-fuel ratio shown by the one-dot chain line 2 in FIG. 2 is provided with a mechanical acceleration pump, and a conventional carburetor configured to supply acceleration fuel from this acceleration pump to an acceleration nozzle different from the main nozzle. In this case, the followability is better than that of the prior art shown by the solid line C, but it is clear that the characteristics of the dotted line B of the present invention are still inferior.

[0016]

[Effect of the device]

 Since the carburetor of the present invention is configured as described above, when the throttle valve is suddenly opened while the vehicle is running, the main fuel is quickly increased from the main nozzle, and so-called delay of main fuel delay occurs. Since it is eliminated, the transient response from the middle and low speed range is improved, and the breathing of the engine can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an embodiment of the present invention.

FIG. 2 is a diagram showing a temporal change of an air-fuel ratio and an intake pipe negative pressure.

[Explanation of symbols]

 3 Throttle valve 7 Main jet 9 Main well 12 Main nozzle pump 21 Discharge port

Claims (1)

[Scope of utility model registration request] 1. A main nozzle pump (12) which discharges fuel when a negative pressure in an intake pipe downstream of a throttle valve (3) becomes small, and a discharge port (21) of the main jet (7) and a main well (9) is provided. A carburetor communicating with the main fuel passage (8) between.