JPH0953514A - Starter for vaporizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the miniaturized starter of a carburetor excellent in its starting property with a small number of parts. SOLUTION: A starting air passage 35, a starting mixture gas passage 34 and a starting fuel passage are opened to the starting valve chamber 31 of a starter B and opening of these passage is open/close controlled by a starting valve 39. A low speed air passage 21 and a low speed fuel jet 17 are opened by continuing to the low speed well 22 in a low speed fuel system S. The upper stream side of a starting fuel passage is opened by continuing to the low speed well 22 and its lower stream side is opened by continuing to the starting valve chamber 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carburetor for adjusting and controlling the amount and concentration of air-fuel mixture supplied to an engine. The present invention relates to a carburetor starting device for supplying to the.

[0002]

2. Description of the Related Art A conventional carburetor starting device is shown in FIG.
This will be described below. Reference numeral 1 denotes a carburetor main body in which an intake passage 2 penetrates laterally inside and a throttle valve guide cylinder 3 is formed upward from an intermediate portion of the intake passage 2. A float chamber body 4 is arranged below the vaporizer body 1, and a float chamber 5 is formed by the vaporizer body 1 and the float chamber body 4. XX is
The fuel liquid level is formed in the float chamber 5, and is formed by the cooperative action of the valve seat 6, the float valve 7, and the float 8. Reference numeral 9 denotes a throttle valve movably arranged in the throttle valve guide cylinder 3, and the intake passage 2 is opened / closed by the throttle valve 9 operated by the driver.

M is the main fuel system and consists of:
Reference numeral 10 is a main fuel jet for measuring the amount of main fuel, which is arranged below the fuel level XX, and this main fuel jet 10 is introduced into the intake passage 2 via a main bleed pipe 11 and a needle jet 12. A main air jet 13, which is open and measures the main air amount, is connected via a main air passage 14 into an annular main well 15 formed on the outer circumference of the main bleed tube 11. The jet needle 16 that is integrally attached to the throttle valve 9 is inserted into the needle jet 12.

S is a low-speed fuel system, which consists of:
Reference numeral 17 is a low-speed fuel jet for measuring the amount of low-speed fuel, and its lower opening is arranged below the fuel level XX, and the low-speed fuel jet 17 has a low-speed bleed pipe 1.
8. A low-speed air jet 20, which opens into the intake passage 2 through the bypass hole 19 and measures the low-speed air amount, is an annular low-speed well formed on the outer periphery of the low-speed bleed pipe 18 through the low-speed air passage 21. 22 is contacted. The low-speed air jet 20 in this conventional example is the adjustment screw 2
Although the jet opening is variably adjustable by screwing 0A, a fixed low-speed air jet may be used. Further, a pilot outlet hole 23 branching from the low speed fuel system S opens in the intake passage 2A on the engine side of the throttle valve 9.

The starting device B is formed by: 30
Is a starter body formed integrally with or separately from the carburetor body 1, and the starter body has a bottomed cylindrical starter valve chamber 31. Reference numeral 32 denotes a starting fuel tank main body which is disposed below the starting device main body 30 and is formed integrally with or separately from the float chamber main body 4, and the starting fuel tank 33 is formed by the starting device main body 30 and the starting fuel tank main body 32. It is formed. In this conventional example, since the starting device body 30 is formed integrally with the carburetor body 1 and the starting fuel tank body 32 is formed integrally with the float chamber body 4, the fuel liquid level is provided on the side of the starting fuel tank 33. The above-mentioned float chamber 5 in which XX is formed is formed. A start mixture channel 34 and a start air passage 35 are opened in the side wall of the start valve chamber 31, and an emulsion tube as a start fuel passage 36 is opened in the bottom. An air bleed hole is formed in this emulsion tube. The intake passage 2 on the engine side of the throttle valve 9 is provided downstream of the starting mixture passage 36.
Open to A The upstream side of the starting air passage 35 is connected to the intake passage 2B on the air cleaner side of the throttle valve 9 or the atmosphere.
The upstream side (corresponding to the lower end) of the emulsion tube serving as the starting fuel passage 36 opens below the fuel level in the starting fuel tank 33. Reference numeral 37 is a starting fuel jet that connects the starting fuel tank 33 with the fuel liquid level XX below the float chamber 5,
38 is on the fuel level XX in the float chamber 5 and the starting fuel passage 3
6 is a starting air jet that connects with the outer peripheral gap of the emulsion tube 6. A starting valve 39 is movably arranged in the starting valve chamber 31, and the starting valve 39 closes the starting fuel passage 36, the starting air passage 35, and the starting mixture passage 34 at the lowest position. By holding the start valve 39 and moving the start valve 39 upward, the start fuel passage 36 opens in the start valve chamber 31, and the start air passage 35 and the start mixture mixture passage 36 increase in the start valve chamber 31. To do. According to this conventional example, the start valve 39
Is a thermal expansion and contraction material (for example, olefin) depending on temperature change
Is operated to be moved by the wax member 40 that expands and contracts the volume of and moves the output rod 40A forward and backward. That is, in a state where the ambient temperature of the wax member 40 is high, the thermal expansion / contraction material expands and moves the output rod 40A downward to move the start valve 3
9 closes the starting fuel passage 36, the starting air passage 35, and the starting mixture passage 34, while the thermal expansion and contraction material contracts in a state where the ambient temperature of the wax member 40 is low and the output rod 40.
A moves upward, and the starting valve 39 is pressed upward by the spring 42 corresponding to the upward movement of the output rod 40A, and the starting fuel passage 36, the starting air passage 35, and the starting mixture passage 36.
To open.

[0006]

According to such a conventional carburetor starting device, there are the following problems. Start valve 39
Slightly upward (for example, 1.0 to 1.5 mm) to slightly open the starting air passage 35 and the starting mixture passage 34 and open the starting fuel passage 36.
At the time of starting the engine in the minute open range of 9, the air-fuel mixture supplied to the engine tends to be diluted, which is not preferable in the starting performance of the engine. This is the starting valve 39
In the minute open area of the starting fuel mixture passage 34, the opening to the inside of the starting valve chamber 31 is so small that the negative pressure in the starting valve chamber 31 cannot be sufficiently increased. This is because it is difficult to suck the fuel into the start valve chamber 31 against the head difference H through the opening of the start fuel passage 36 on the fuel level XX into the start valve chamber 31.
Therefore, only the starting air flowing from the starting air passage 35 into the starting valve chamber 31 is sucked into the intake passage 2A on the engine side from the throttle valve 9 through the starting mixture passage 34, and the low speed fuel system S Therefore, the low-speed air-fuel mixture supplied into the intake passage 2 through the bypass hole 19 and the pilot outlet hole 23 is thinned, so that the entire air-fuel mixture supplied to the engine is thinned.

As the starting device B, an emulsion tube as the starting fuel passage 36, a starting fuel tank 33 as a starting fuel source for the starting fuel passage 36, and a starting air jet 38 for atomizing the starting fuel are required. Become. According to the above, the number of parts and the number of assembling steps are increased, which is not preferable because the manufacturing cost of the carburetor is increased. Further, the need for the starting fuel tank 33 means that the starting device B is large. Therefore, the degree of freedom of arrangement in a motorcycle or the like is limited, which is not preferable. In particular, when the entire vehicle is relatively small, such as a small motorcycle having an engine displacement of 125 cc or less, the degree of freedom in mounting is hindered.

The carburetor starter according to the present invention has been made in view of the above problems, and its main purpose is to provide a starter which is excellent in startability, has a small number of parts, and is small in size. To do.

[0009]

In order to achieve the above object, a carburetor starter according to the present invention is provided with a throttle valve for opening and closing an intake passage passing through a carburetor main body, a main fuel jet, and a main air jet. The main fuel system that mixes the fuel and air measured by and supplies it toward the intake passage, and mixes the fuel and air measured by the low-speed fuel jet and the low-speed air jet toward the intake passage. Low-speed fuel system to supply,
The starting air passage, the starting air-fuel mixture passage, and the starting fuel passage that open into the starting valve chamber are controlled to be opened and closed by the starting valve, and the starting air-fuel mixture is introduced into the intake passage on the engine side from the throttle valve via the starting air-fuel mixture passage. In a vaporizer provided with a starting device for supplying,
The upstream side of the starting fuel passage of the starter is connected to and opened to the low speed well in the low speed fuel system S for mixing the low speed fuel and the low speed air, while the downstream side is opened to be connected to the start valve chamber of the starter B. It is characterized by

[0010]

According to the present invention, even if air is sucked out from the starting mixture passage in the minute opening region of the starting valve, the air sucks the air supplied into the low speed well. According to this, since the amount of low speed air supplied to the low speed fuel system S is reduced, the air-fuel mixture sucked into the intake passage from the bypass hole and the pilot outlet hole becomes rich,
Good starting characteristics of the engine can be obtained without diluting the total air-fuel mixture supplied to the engine.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vaporizer starting device according to the present invention will be described below with reference to FIG. Note that the same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted. Reference numeral 50 denotes a starting fuel passage, the upstream side of which is opened and connected to the low speed well 22 and the downstream side of which is opened to a lower lower portion of the starting valve chamber 31.
It should be noted that upstream and downstream are in the flow direction,
Further, a flow rate control jet 51 is arranged in the starting fuel passage 50. The flow rate control jet 51 is provided as needed.

Next, the operation will be described. When the ambient temperature of the engine is equal to or higher than a certain temperature (for example, 58 ° C. or higher), the thermal expansion and contraction material of the wax member 40 expands and the output rod 40A moves downward in the starting valve 39 of the starting device B. It is arranged so as to be pressed downward in the chamber 31. Therefore, the starting fuel passage 50, the starting air passage 35, and the starting mixture passage 34 are closed and held by the starting valve 39. When the engine is operating, the adjusting screw 20
Low-speed air jet 20 whose opening is adjusted by A
The low-speed air metered by is supplied to the low-speed well 22 via the low-speed air passage 21, while the low-speed fuel metered by the low-speed fuel jet 17 is supplied to the low-speed bleed pipe 18. Then, the metered low speed fuel and low speed air are mixed in the low speed well 22 by the low speed bleed pipe 18 to form a low speed mixture, and this low speed mixture is passed through the bypass hole 19 and the pilot outlet hole 23. It is sucked into the intake passage 2. That is, the low speed air-fuel mixture is supplied from the low speed fuel system S to the intake passage 2.

On the other hand, the main air measured by the main air jet 13 is supplied into the main well 15 through the main air passage 14, and the main fuel measured by the main fuel jet 10 is supplied into the main bleed pipe 11. It The supplied main air and main fuel are mixed in the main bleed pipe 11 to form a main air-fuel mixture, which is sucked into the intake passage 2 via the needle jet 12. That is, the main air-fuel mixture is supplied from the main fuel system M. Therefore, the engine is operated by the mixture supplied from the low speed fuel system S and the main fuel system M according to the opening degree of the throttle valve 9.

Next, a description will be given of the time of starting the engine when the engine ambient temperature drops below a certain temperature (eg, 57 ° C.). First, when the engine ambient temperature is low (for example, 3
The starting time of the engine at 5 ° C to 50 ° C will be described. In such a state, the thermal expansion / contraction material in the wax member 40 slightly contracts depending on its temperature, and the output rod 40A moves slightly upward in accordance with the contraction. According to this, the start valve 39 is
The spring force of 2 causes the output rod 40A to move in the upward direction, for example, moves in the upward direction by about 1.0 to 1.5 mm. According to the above, the starting valve 39 opens the starting fuel passage 50 and starts the starting mixture passage 3.
4. Open the starting air passage 35 slightly.

When the engine is started in this state, the intake passage 2A on the engine side of the throttle valve 9 is operated.
Negative pressure is generated in the inside, and this negative pressure is generated in the starting mixture passage 34.
The negative pressure in the intake passage 2A acts on the low-speed fuel system S through the pilot outlet hole 23 and the bypass hole 19 via the valve.

That is, in the starting device B, since the starting mixture passage 34 opens slightly to the inside of the starting valve chamber 31, the negative pressure in the intake passage 2A on the engine side is set in the starting valve chamber 31. Is introduced, and the negative pressure in the starting valve chamber 31 acts in the low speed well 22 via the starting fuel passage 50. Therefore, a part of the low-speed air supplied into the low-speed well 22 through the low-speed air passage 21 is located on the engine side of the throttle valve 9 through the starting fuel passage 50, the starting valve chamber 31, and the starting mixture passage 34. It is sucked out into the intake passage 2A.

On the other hand, in the low speed fuel system S, the low speed air-fuel mixture is sucked into the intake passage 2 through the pilot outlet hole 23 and the bypass hole 19. Since part of the low-speed air supplied into the well 22 is sucked into the starting fuel passage 50, the amount of low-speed air in the low-speed well 22 is reduced correspondingly. Therefore, the concentration of the low-speed air-fuel mixture formed by the low-speed fuel system S can be increased, and the enriched low-speed air-fuel mixture is sucked into the intake passage 2 through the pilot outlet hole 23 and the bypass hole 19.

According to the above, in the minute open region of the starting valve 39, the intake passage 2 is moved from the starting mixture passage 34 of the starting device B.
Although the air is sucked into A, the low-speed air-fuel mixture enriched from the pilot outlet hole 23 and the bypass hole 19 of the low-speed fuel system S is sucked into the intake passage 2 and thus sucked into the intake passage 2A. It does not dilute the total concentration of the mixture. Therefore, the startability of the engine in the minute opening range of the start valve 39 can be remarkably improved.

Further, when the ambient temperature of the engine further decreases from the low temperature state, the thermal expansion and contraction material of the wax member 40 further contracts, whereby the output rod 40A moves further upward, and the start valve 39 becomes The starting fuel passage 50 is opened, and the starting mixture passage 34 and the starting air passage 35 are opened further. Therefore, at the time of starting in such a strong low temperature state, the starting air-fuel mixture passage 34 opens largely in the starting valve chamber 31 and a negative pressure larger than that in the starting fuel passage 50 acts on the low-speed well 22. The amount of air flowing toward the bypass hole 19 and the pilot outlet hole 23 is further reduced to increase the concentration of the air-fuel mixture in the low speed fuel system S, and the fuel in the low speed well 22 directly acts in the low speed well 22. Is sucked by the negative pressure, and this fuel is sucked into the intake passage 2A on the engine side from the throttle valve 9 through the starting fuel passage 50, the starting valve chamber 31, and the starting mixture gas passage 34. According to the above, it is possible to supply the engine with a sufficiently increased and rich starting mixture.
Therefore, the engine can be started satisfactorily at a strong low temperature.

The embodiment shown in FIG. 1 is for a carburetor equipped with an air screw type low speed fuel system, but the embodiment shown in FIG. 2 is for a carburetor equipped with a pilot screw type low speed fuel system. explain. The difference from FIG. 1 will be described. The low speed fuel system S consists of: 52 is a low speed well, a low speed fuel jet 53 is arranged at the lower end thereof, and a bypass hole 19 is opened at the upper end thereof toward the intake passage 2. Further, the low speed well 52 has a low speed air passage 21 in which the fixed low speed air jet 20 is arranged.
A pilot outlet hole 23, which opens to the intake passage 2A on the engine side of the throttle valve 9, opens in the vicinity of the upper portion of 2.
Reference numeral 54 is a pilot screw for adjusting the effective opening area of the pilot outlet hole 23. And
The upstream side of the starting fuel passage 50 that opens at the bottom of the starting valve chamber 31 of the starting device B opens in series with the low speed well 52.

The pilot screw type carburetor described above also operates in the same manner as the embodiment shown in FIG. That is, in the minute open region of the start valve 39 when the engine ambient temperature is low, a part of the low speed air supplied into the low speed well 52 flows through the start fuel passage 50, the start valve chamber 31, and the start mixture gas passage 34. Through the throttle valve 9 toward the inside of the intake passage 2A on the engine side, while the amount of low-speed air in the low-speed well 52 is reduced by the amount sucked into the starting fuel passage 50 to enrich the concentration of the low-speed mixture. Therefore, the concentration of the entire air-fuel mixture sucked into the intake passage 2 is not diluted, and the startability of the starting valve 39 in the minute open range at low temperatures can be improved. Further, when the engine atmosphere temperature is very low, a sufficiently increased and enriched starting air-fuel mixture can be supplied to the engine, so that the engine can be started well at high temperatures. .

The starting device in the present embodiment is shown to automatically open and close the starting valve 39 by using the wax member 40, but a so-called manual type in which the driver mechanically controls the opening and closing of the opening and closing valve 39 is shown. It may be one. Further, although a sliding throttle valve type is shown as the throttle valve 9, a butterfly type throttle valve may be used. Further, the starting device main body 30 may be formed integrally with the carburetor main body 1 and the float chamber main body 4, or may be formed separately from them. Furthermore, the pilot outlet hole 23 of the low speed fuel system S may be eliminated.

[0023]

As described above, the carburetor starter according to the present invention has the following effects. The mixture supplied into the intake passage when the engine is started in the small opening range of the start valve where the start valve moves slightly upward to slightly open the start fuel passage, start mixture passage, and start air passage. Since the rich mixture can be supplied to the engine without being diluted, the startability of the engine can be greatly improved. When the engine is started in the wide open range of the start valve where the start valve has moved greatly upward and the start fuel passage, start mixture passage, and start air passage have been greatly opened Since the low-speed fuel is directly sucked, it is possible to increase the amount of the sufficiently rich starting air-fuel mixture to be supplied to the engine, so that the engine startability can be improved in addition to the above. As a starting device, a starting fuel tank,
Emulsion tubes and starting air jets are no longer needed, so the number of parts and assembly work can be reduced, and the manufacturing cost of the carburetor can be reduced. In particular, the fact that the starting fuel tank is not necessary means that the entire starting device can be greatly reduced in size, and the starting device can be easily mounted on a relatively small vehicle such as a small motorcycle. Furthermore, the starting device can be easily arranged separately from the carburetor, which makes it possible to accurately convey the temperature condition of the engine to the wax member which is the temperature-sensitive part of the starting device. It has become possible to supply the starting air-fuel mixture that meets the requirements of the engine.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a carburetor starter according to the present invention.

FIG. 2 is a longitudinal sectional view showing a second embodiment of the carburetor starting device according to the present invention.

FIG. 3 is a vertical cross-sectional view showing a conventional carburetor starting device.

[Explanation of symbols]

 20 Low-speed air jet 21 Low-speed air passage 22, 52 Low-speed well 50 Starting fuel passage M Main fuel system S Low-speed fuel system B Starting device

Claims (1)

[Claims] 1. A throttle valve that opens and closes an intake passage that penetrates a carburetor main body, and a main fuel system that mixes fuel and air measured by a main fuel jet and a main air jet and supplies the mixture into the intake passage. And a low-speed fuel system that mixes the fuel and air measured by the low-speed fuel jet and the low-speed air jet and supplies the mixed fuel and air toward the intake passage, and a starting air passage and a starting air-fuel mixture passage that open into the starting valve chamber. A carburetor comprising: a starting fuel passage and a starting valve, the opening / closing control of which is performed by a starting valve, and the starting fuel mixture is supplied into the intake passage on the engine side from a throttle valve via the starting mixture passage. Of the starting fuel passage 50 is connected to the low speed well 22 or 25 in the low speed fuel system S for mixing low speed fuel and low speed air to be opened, while the downstream side is connected to the starting valve chamber 31 of the starting device B. Opened And a carburetor starting device.