JPS5867952A - Carburetor - Google Patents

Abstract

PURPOSE:To prevent fuel from becoming an overrich state at tilting and the like of a vehicle, in a carburetor having a rising passage, lowering passage and communication passage, by communicating the rising passage to the communication passage through a hole, forming the hole in a plug and specifically sloping the communication passage. CONSTITUTION:A rising passage 10 is communicated to a float chamber 1 through a main passage 7, emulsion passage 21, etc., and a peripherally directional groove 26, vertical hole 28 and horizontal hole 29 are formed to a step jet plug 23, closing an upper end of the rising passage 10, then the rising passage 10 is communicated to the groove 26 through the holes 28, 29. While a communication passsage 30, communicated to the groove 26, is communicated to a lowering passage 14, opened to an intake passage 2, and a fuel passage 31 is constituted by the passage 7, rising passage 10, holes 28, 29, communication passage 30 and the lowering passage 14. In thiw way, a vehicle is tilted, even if a level of fuel is sloped, the communication passage 30 is opened to an upper end position of the rising passage 10, and an overflow, due to increase of a fuel oil level, is never caused.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carburetor, and more particularly, to a carburetor that prevents fuel and air-fuel mixture supplied to an engine from becoming excessively rich when a vehicle tilts or turns.

- As a conventional carburetor, the one shown in FIG. 1, for example, is known. (Refer to Service Bulletin No. 440, June 1980, published by Nissan Motor Co., Ltd.) In Figure 1, (]) indicates the float chamber where fuel is stored (2) indicates the fuel passage (3) in this float chamber ([). This is an intake passage that is communicated through the air.

A float (4) is provided in the float chamber (1) to maintain a constant amount of fuel supplied from the fuel pump.
A secondary throttle valve (5) is provided within the intake passage (2). The fuel passage (3) is a main passage communicating with the float chamber (1) via a main jet (6), and a step jet (8) is installed inside and the upper end is closed by a step jet plug (9). The ascending passage QO), the descending passage (141) with a step port (+21 (+31) formed therein, and the ascending passage 00) whose upper end is closed by the plug old) and whose lower end opens near the secondary throttle valve (5). Descending path (1
It has a horizontal communication passage (151) that communicates the upper ends of the 4J and 4J. Also, (161 is an air passage that communicates with the 1 ascending passage (10), and this Air flowing in from the air passage (16) is supplied from the emulsion hole (181) into the step jet (8) and mixed with fuel to form an emulsion.

Therefore, in such a carburetor, when the secondary throttle valve starts to open, the fuel in the float chamber (1) is diverted to the main passage (from the upward path 00) by the suction negative pressure of the bonder.
The emulsion is mixed with air in the ascending passage f+01 of this 5 to form an emulsion, which is guided to the descending passage (14+) through the communication passage (151) and sucked out from the step port Q21 (13 to the intake passage (2)).

However, in such a conventional carburetor, the opening of the communication passage to the rising passage was restricted by the step jet plug (9) and was provided below the step jet plug (9), so that the float chamber (11
The height (h) from the fuel level to the opening was insufficient. Therefore, when the vehicle is tilted or when the vehicle turns, the liquid (oil) level is inclined as shown by the two-dot chain line in FIG. 1, and fuel tends to overflow from the communication path. As a result, the mixture ratio of fuel and air becomes too rich,
There are problems such as engine stalling and an increase in the concentration of HC and NOx in the exhaust gas due to incomplete combustion, and once the fuel overflows, it continues to flow out due to the siphon effect.

This invention was made by focusing on such conventional problems, and a hole is formed in the step jet plug of the carburetor to communicate the ascending path and the communicating path, and the communicating path is directed downward from the descending path. The purpose of this invention is to increase the height from the fuel liquid (oil) level to the opening of the communication passage to the ascending passage without increasing the size of the carburetor, thereby solving the above-mentioned problems.

The present invention will be explained below based on the drawings.

FIG. 2 is a diagram showing an embodiment of the present invention. In addition,
Components that are the same as those of the conventional example shown in FIG. 1 are designated by the same reference numerals.

First, to explain the configuration, (1) is a float chamber that stores fuel supplied from a fuel pump (not shown), and a float (1) is housed in the float chamber (1) so as to float on fuel oil. There is. Flow 4 (41) supplies and disconnects fuel from the fuel bonder by rising and falling according to the amount of fuel stored, and by utilizing the rise and fall of this float (4), the fuel in the float chamber (+) is liquid (
The height of the oil level is kept constant. Float chamber (11
The air passage (force) is connected to the rising passage (10). The air passage +1!11 is opened in the rising passage 1tj, and the air passage (16) has an air bleed for measuring the amount of air taken in. (171 is installed. Also, the ascending road 0
Inside the step jet (8), a step jet (8) is screwed so that its lower end is in close contact with the side wall of the main passage (force). An emulsion passage Qυ is formed. This emulsion passage circle and the main passage (7) communicate with each other via a measuring part (2) formed at the lower end of the step jet (8). Qυ and the air passage (16) are communicated by an emulsion hole (I81) formed at the lower end of the step jet (8).Furthermore, the upper end of the emulsion passage (211) opens into the ascending passage (10). The upper end of the ascending path (10) is closed by a step jet plug (231).This step jet plug (2'5 has a threaded shaft portion C?4) and a head. A groove c!6) is formed in the upper end of the shaft part C4 in the circumferential direction of the shaft part C40.In addition, a hole (27
) is formed.

This hole (27) is a vertical hole (2) communicating with the ascending path (10).
and a horizontal hole (2!1) communicating with this vertical hole Q81 and opening into the groove (4).
is connected to a downwardly sloping communication path (G),
Connecting path (phantom is a descending path (connected to I4I). Descending path (
The upper end of 141 is closed by a plug (mark), and the lower end of each descending passage (141) is formed with a Metilaf" boat f121 (131) that opens into the intake passage (2). is provided with nine secondary throttle valves (5), and this intake passage (2) communicates with a combustion chamber of the engine (not shown).From the oil level of the fuel in the float chamber (1) to the communication passage ( If the height up to 3o) is set to 0, then the flow [41] will maintain this height constant.Also, these main passages (7), ascending passages aO
) The S hole (2η, the communication passage (3ω and the descending passage 14) constitute a fuel passage (31) as a whole.

Next, the action will be explained.

When the secondary throttle valve 15) starts to open, the fuel in the float chamber
) and the measuring section (23) and the emulsion passage (21
I am guided by 1. The fuel led to the emulsion passage (2H) is mixed with the air taken in from the air bleed OD, the air passage (16) and the emulsion hole Q& to form an emulsion, and the emulsion-toned fuel ascends the emulsion passage +211 and passes through the upward passage. (It passes through the step jet plug (2-moat vertical hole). This fuel passes from the vertical hole, through the horizontal hole, the groove (A), and the communication passage 4, and then -1 descending passage (1. D. The fuel guided to the lower end of the descending path a is fed step by step (121) +121 (1
3) Intake passage + 2) K is sucked out from the intake passage (2)
9. The fuel sucked out is in the form of an emulsion and is sufficiently mixed with the air flowing through the intake passage (2), resulting in an optimal mixing ratio.9. It is burned in the combustion chamber of the engine.

In the carburetor configured as described above, when the vehicle is tilted or the vehicle width is turned, the oil level of the fuel is tilted as shown by the two-dot chain line in FIG. In this case, within the range of the normal vehicle's permissible inclination angle and permissible centrifugal force due to turning, the communication passage (3o) opens at the top end of the ascending passage II O), so overflow due to the rising oil level may occur. does not occur. Therefore, it is possible to prevent the air-fuel mixture from becoming too rich when the vehicle is tilted or turning, and to reduce NOx in the exhaust gas due to engine stalling or incomplete combustion.
) (It is possible to prevent an increase in the concentration of C.'Furthermore, in this invention, the hole (27) is provided in the step jet plug (23), and the communication path (to) is completely sloped. Therefore, the height (2) from the oil level to the opening to the communication path (301 groove) can be increased without increasing the size of the carburetor.

FIG. 3 is a diagram showing another embodiment of the invention.

In the description of this embodiment, only the same reference numerals are given to the same components as those of the embodiment shown in FIG. 2, and the explanation thereof will be omitted. In this embodiment, the diameter of the vertical hole of the step jet plug of the previously described embodiment is increased. (4υ is a step jet plug, and this step jet plug (4υ has a vertical hole (47J) with a larger diameter than the emulsion passage CD and communication passage ■). (441 is formed in the same manner as in the previous embodiment, and these vertical holes (421 and horizontal holes (4, il) constitute the hole (49) as a whole.Furthermore, the main passage (7), The ascending passage 00), the hole (451, the communicating passage -, and the descending passage (+4)) constitute a fuel passage (4bl) as a whole.

In this embodiment, by making the diameter of the vertical hole (421) larger than the diameter of the emulsion passage (21) and the communication passage (30), fuel flows into the communication passage C by capillary action when the vehicle is tilted or turning. , 30+.Furthermore, even if the oil level is greatly tilted due to the tilt or turning of the vehicle and there is an overflow, the fuel in the vertical hole f42) can be easily drained when the vehicle returns to its natural state. , the mixture ratio of fuel and air can be quickly restored to its optimum value.

As described above, according to the present invention, the structure includes a float chamber in which fuel is stored, an intake passage that supplies a mixture of fuel and air to the combustion chamber, and these float chambers and the intake passage. The fuel passage has a lower end that opens below the liquid level in the float chamber, an upper end that is closed by a plug, and a rising path that has a step jet that mixes fuel and air below the oil surface. In the carburetor, the carburetor has a descending passage whose lower end opens to the intake passage, and a communicating passage communicating the ascending passage and the descending passage, and a hole is formed in the plug to communicate the ascending passage and the communicating passage. In addition, since the communication passage is sloped downwards from the descending passage, the carburetor does not need to be enlarged, and fuel overflows when the vehicle is tilted or turns, preventing the mixture from becoming too rich when being supplied to the combustion chamber. As a result, it is possible to prevent an increase in the HC and NOx concentrations in the exhaust gas due to engine stalling and incomplete combustion.

Further, other embodiments have the following effects in addition to the above-mentioned common effects. That is, it is possible to prevent overflow due to capillary action when the vehicle is tilting or turning, and to quickly return the mixture ratio to the optimum value when the vehicle returns to its natural state. Although the present invention has been exemplified on the secondary side, it is of course applicable to the primary side.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing a conventional carburetor, FIG. 2 is a schematic sectional view showing one embodiment of the carburetor of the present invention, and FIG. 3 is a schematic sectional view showing another embodiment of the carburetor of the present invention. be. +1)...Float chamber (2)...Intake passage (8
)...Step jet (19...Ascent path Q41.
... Descending path C? 31 (4υ...Step jet plug (2η(, 19...hole (7)...Communication passage 3υ(4Gl...Fuel passage Patent applicant Nissan Motor Co., Ltd. agent Patent attorney Yuga Army - Department Figure 1 Figure 2

Claims (1)

[Claims] A float chamber in which fuel is stored and an intake passage that supplies a mixture of fuel and air to a combustion chamber. A fuel passage that communicates these float chambers with the intake passage is provided, and the lower end of this fuel passage opens below the liquid level in the float chamber, and the upper end is closed by a 7° lug, so that fuel and air are kept below the liquid level. an ascending path with a step jet mixing at
In a carburetor having a descending passage whose lower end opens into an intake passage, and a communication passage communicating the ascending passage and the descending passage, the plug is provided with a hole communicating the ascending passage and the communication passage, A carburetor characterized in that a communication passage is inclined downwardly from the descending passage.