JP3475487B2 - Engine carburetor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carburetor for an engine, and more particularly to a carburetor for an engine which is prevented from freezing in a cold region. [0002] A vehicle such as a motorcycle equipped with a gasoline engine has a carburetor as an engine intake system.
The carburetor is located in the intake passage of the engine and atomizes gasoline and mixes the gasoline with air to form a gaseous mixture (mixture) and sends it into the cylinder of the engine. When a vehicle is traveling under low-temperature, high-humidity air conditions, such as in a cold region, a needle jet, a fuel outlet near a throttle valve, and air passages of a main system and a slow system are formed. Moisture may freeze. As a result, the flow rates of air and fuel in the carburetor are significantly reduced, and an appropriate air-fuel ratio is not maintained, causing engine stall. Also, it becomes difficult to restart the engine. The cause is that, in the low-temperature, high-humidity atmosphere, first, the outside air and the cold air passing through the carburetor cool the carburetor itself. Further, the inside of the carburetor is further cooled by the latent heat of vaporization of gasoline.
As a result, moisture in the air freezes inside the carburetor. Therefore, in recent years, a carburetor has been devised in which a carburetor is prevented from freezing by attaching an anti-freezing means such as an electric heating element to a throttle body constituting the carburetor. As an example of a method of attaching a heating element to a throttle body, there is an example in which a heating element is attached around a fuel outlet of a slow system of a throttle body (Japanese Patent Laid-Open No. 56-1).
18539). As another example, there is an example in which a boss is provided on a throttle body, and a heating element is attached to the boss (see Japanese Patent Application Laid-Open No. 62-298652). [0007] In the conventional method of mounting the heating element on the throttle body, it is necessary to form a mounting portion of the heating element on the throttle body in advance. Since the throttle body is generally formed by die-casting a light metal material such as aluminum, if a conventional method is adopted, it is necessary to newly manufacture a molding die for the throttle body. However, only the carburetor of the cold district is required to prevent the carburetor from freezing. As a result, two molds are required including those for the area other than the cold district, which leads to an increase in the cost of the throttle body. Would. [0009] Further, even if a heating element is retrofitted to an existing throttle body, it requires labor and cost such as processing of the throttle body. Furthermore, when a plurality of throttle bodies are connected in series, the conventional method requires a plurality of heating elements because each of the heating elements is attached to the throttle body, which complicates the structure and wiring. Increases costs. The present invention has been made in view of the above circumstances, and has as its object to provide an engine carburetor that can prevent freezing of a throttle body without requiring processing of the throttle body. [0012] In order to solve the above-mentioned problems, a carburetor for an engine according to the present invention is provided with a throttle body and a throttle body. The throttle body is provided with a venturi passage and a throttle valve penetrating therethrough, and a cap for a negative pressure chamber of a float chamber and a piston valve is provided as the carburetor constituent member. A carburetor for supplying an air-fuel mixture to the engine, wherein a float chamber is provided inside the float chamber detachably provided on the throttle body, and a boss portion is formed integrally with the float chamber, Provided in the body A plurality of fuel outlet and air passages in the vicinity of the throttle valve which, the transfer heat antifreeze means fuel outlet opening into at least the vicinity of the throttle valve as well as disposed in the boss portion of the float chamber, the throttle body
Formed in the above float chamber, which is detachably mounted on the
Boss part with the outer peripheral flange of the float chamber
In addition, freezing prevention means is buried in the outer peripheral flange . According to the present invention having the above structure, the present invention comprises a throttle body and a carburetor component which is detachable from the throttle body, and supplies an air-fuel mixture to the engine. In the engine carburetor, the carburetor component is a cap for a negative pressure chamber of a float chamber and a piston valve, and the carburetor antifreezing means is disposed on at least one of the carburetor components. The freezing of the throttle body can be prevented without the need for a throttle. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an engine C to which the present invention is applied.
FIG. 2 is a front view showing a first embodiment of a V (constant vacuum) type carburetor 1, and FIG. 2 is a longitudinal sectional view thereof. The left side in the figure is the air cleaner side,
The right side is the engine side. The throttle body 2, which is the main body of the carburetor 1, is formed by die-casting a light metal material such as aluminum. The upper part is made of, for example, aluminum and is removably closed by a negative pressure chamber cap 3 which is a constituent member of the carburetor 1 to form a negative pressure chamber 4 therein. Then, a diaphragm device 5 is provided in the negative pressure chamber 4. On the other hand, a float chamber 6 which is made of, for example, aluminum for storing fuel and is a constituent member of the carburetor 1 is detachably provided on the throttle body 2 at a lower portion of the throttle body 2, and a float chamber 7 is formed therein. . Further, a venturi passage 8 is formed at the center of the throttle body 2 so as to penetrate in the lateral direction in the figure. The venturi passage 8 is provided with a piston valve 9 and a throttle valve 10. The piston valve 9 is inserted from above the throttle body 2 so as to be able to move up and down, is connected to the diaphragm 11 of the diaphragm device 5 and is urged downward by the spring 12, and is controlled to move up and down by the operation of the diaphragm device 5 so that the venturi passage 8 is formed. Adjust the passage area. The diaphragm device 5 senses a pressure change in the venturi passage 8 due to a change in the opening of the throttle valve 10 due to the operation of an accelerator (not shown), and moves the diaphragm 11 up and down to move the piston valve 9 up and down. The pressure change in the venturi passage 8 is, for example,
Is transmitted to the diaphragm device 5 by a negative pressure port 13 provided in the diaphragm device 5. The carburetor 1 is provided with a slow system 14 for supplying necessary fuel during low-speed rotation of the engine.
The slow system 14 includes a slow jet (not shown), a slow air jet 15, a slow outlet 16, a bypass outlet 17, and the like. The slow outlet 16 and the bypass outlet 17 are fuel outlets, and are provided in the throttle valve 10 of the venturi passage 8.
It is opened near. The carburetor 1 is provided with a main system 18 for supplying necessary fuel during normal traveling and high-speed traveling. The main system 18 has a tapered shape fixed to the lower end of the piston valve 9. Jet needle 19,
Cylindrical needle jet 20 and needle jet 2
0, for example, a main jet 21 formed on the side, and a main air jet (not shown). The needle jet 20 connects the float chamber 7 and the venturi passage 8 via the main jet 21, and the jet needle 19 is inserted into the needle jet 20 from the fuel outlet 22 on the side of the venturi passage 8. A boss 23 is formed integrally with the negative pressure chamber cap 3, and the boss 23 is provided with anti-freezing means. The anti-freezing means is, for example, a PTC heater 25 incorporating a PTC (semiconductive barium titanate ceramics) element 24 which is an electric heating element. FIG. 3A is a front view of the PTC heater 25, FIG. 3B is a right side view, and FIG.
FIG. 4 is a cross-sectional view taken along line CC of FIG. As shown in FIGS. 3 (a), 3 (b) and 3 (c), the PTC heater 25 comprises a main body 26 and a terminal 2
And a thread 28 on the outer peripheral surface of the main body 26.
Is formed, and a PTC element 24 is provided in the main body. The temperature-resistance characteristic of the element 24 is such that the resistance is low at a low temperature, but the resistance rapidly increases from a certain temperature. When the element 24 is energized, it works as a normal heating element at low temperatures, but when it enters a region where the resistance increases rapidly, almost no current flows, so the temperature rise stops there. That is, the temperature is automatically controlled (see FIGS. 4A and 4B). Although not shown in detail, the terminal 27 of the PTC heater 25 is connected to a power source such as a battery mounted on the vehicle via a connector. FIG. 5 shows a carburetor 1 to which the present invention is applied.
And FIG. 6 is a longitudinal sectional view of the second embodiment. The same members as those in the first embodiment are denoted by the same reference numerals. The carburetor 1 shown in the second embodiment has substantially the same configuration as the carburetor 1 shown in the first embodiment. The difference from the first embodiment is that the PTC heater 25 provided on the negative pressure chamber cap 3 in the first embodiment is disposed on the boss 23 formed integrally with the float chamber 6. FIG. 7 shows a carburetor 1 to which the present invention is applied.
FIG. 7 is a longitudinal sectional view showing a third embodiment of the present invention. The same members as those in the first embodiment are denoted by the same reference numerals. The third embodiment is different from the third embodiment in that the PTC element 24 is embedded in the outer peripheral flange 29 of the float chamber 6. FIG. 8 shows a carburetor 1 to which the present invention is applied.
FIG. 9 is a front view showing the fourth embodiment, and FIG. 9 is a right side view thereof. FIG. 10 is a longitudinal sectional view taken along line XX of FIG. The same members as those in the first embodiment are denoted by the same reference numerals. The fourth embodiment is a carburetor 1 having a plurality of, for example, four throttle bodies 2 connected in parallel.
And the throttle body 2 is, for example, a carburetor 1
Are connected by two throttle body connection shafts 30 and 31 which are constituent members of. In the fourth embodiment, as shown in FIG. 9, a PTC heater 25 is attached to one end of one throttle body connecting shaft 30, for example. The PTC heater 25 may be provided on the other throttle body connecting shaft 31 or on both throttle body connecting shafts 30, 31. FIG. 11 is a right side view showing a fifth embodiment of the carburetor 1 to which the present invention is applied. The same members as those in the first embodiment are denoted by the same reference numerals. In the fifth embodiment, the throttle valves 10 provided in the venturi passages 8 in the respective throttle bodies 2 are connected by a throttle valve connecting shaft 32 which is a constituent member of the carburetor 1, and the throttle valves 10 are integrally formed. It is linked to.
The PTC heater 25 is attached to, for example, an end of the throttle valve connecting shaft 32. In the fifth embodiment, an example is shown in which the invention is applied to a carburetor 1 having a plurality of throttle bodies 2 connected in parallel.
The present invention is also applicable to a carburetor 1 including a single throttle body 2. Next, the operation of the present embodiment will be described. When the throttle valve 10 is opened with the engine started, a strong negative pressure is generated below the piston valve 9 by the flow of air in the venturi passage 8.
Then, the air in the negative pressure chamber 4 of the diaphragm device 5 is sucked out through the negative pressure port 13, the pressure in the negative pressure chamber 4 decreases, the diaphragm 11 is pushed up to the atmospheric pressure, and the piston valve 9 is lifted and the venturi is lifted. The diameter of the passage 8 increases. As the opening of the throttle valve 10 increases, the negative pressure in the venturi passage 8 increases, and the piston valve 9 rises to increase the area of the venturi passage 8,
Increase the intake air volume. As the air passes through the venturi passage 8, the flow rate of the fuel in the float chamber 7 is measured by the main jet 21 constituting the main system 18, and then the main air jet (not shown) in the needle jet 20. ), And is further sucked into the venturi passage 8 from the fuel outlet 22 at the upper end of the needle jet 20 while being regulated by the taper of the jet needle 19, and is foamed into a gaseous mixture to the engine. Sent. When the opening of the throttle valve 10 is small, such as when the engine is running at a low speed, the amount of intake air is small, so the negative pressure in the venturi passage 8 is also small, and the piston valve 9 is lowered most. At this time, the negative pressure is larger on the right side of the throttle valve 10 in the figure, that is, on the engine side, and the fuel in the float chamber 7 is measured by a slow jet (not shown) constituting the slow system 14, and then the flow rate is measured.
The air is mixed with the air from the slow air jet 15 and foams out from the slow outlet 16 and the bypass outlet 17 to the peripheral portion of the throttle valve 10 to be jetted as an air-fuel mixture and sent to the engine. In a low-temperature, high-humidity atmosphere such as a cold region, the slow air jet 15, the slow outlet 16, the bypass outlet 17, and the like of the slow system 14 provided in the throttle body 2 are provided. Water in the air may freeze on the main air jet (not shown) of the system 18 or the fuel outlet 22 at the upper end of the needle jet 20. In the present invention, each of the carburetor 1 and the negative pressure chamber cap 3 of the piston valve 9 as components of the carburetor 1 and each of the carburetors 1 in which a plurality of throttle bodies 2 are connected in parallel are provided with respective throttles. Since the PTC heater 25 (electric heating element) is provided on the throttle body connecting shafts 30 and 31 connecting the bodies 2 and the throttle valve connecting shaft 32 connecting each throttle valve 10, the heat of the PTC heater 25 causes the structure of the carburetor 1. The heat is transferred from the member to the throttle body 2, and the entire carburetor 1 including the fuel outlets 16, 17, 22 and the air passage 15 is warmed, and the carburetor 1 is prevented from freezing. Further, in the present invention, no processing for mounting the heating element 24 on the throttle body 2 is required, so that it is not necessary to newly manufacture a molding die for the throttle body 2 as in the prior art. Instead, the carburetor components 3, 6, 30, 31, and 32, such as the float chamber, require new processing. However, since these have a simpler structure than the throttle body 2, the cost increase due to the processing is minimal. Only need to be done. Further, a carburetor 1 of a normal area specification
To the cold specification, the carburetor component 3,
Since only the exchange of 6, 30, 31, and 32 is required, the conversion can be easily performed without much cost. In particular, in the case where the heating element 21 is provided in the float chamber 6, the fuel outlets 16, 17, and
In particular, a portion that is particularly easy to freeze, such as the air passage 22 and the air passage 15, is easily heated efficiently, and the fuel in the float chamber 7 is heated by the heating element 24, thereby improving the fuel vaporization. The heating element applied to the present invention is PT
A C (semiconducting barium titanate ceramics) element 24, which has a self-temperature control function, does not require a separate complicated temperature control device, and enables stable temperature control. is there. As described above, according to the carburetor for the engine according to the present invention, the carburetor is composed of the throttle body and the carburetor component detachable from the throttle body, and supplies the air-fuel mixture to the engine. In the engine carburetor described above, the carburetor component is a cap for a negative pressure chamber of a float chamber and a piston valve, and the carburetor antifreezing means is disposed on at least one of the carburetor components. The freezing of the throttle body can be prevented without the need for a throttle. [0053]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view showing a first embodiment of a CV carburetor for an engine to which the present invention is applied. FIG. 2 is a longitudinal sectional view of FIG. 3A is a front view of a PTC heater, FIG. 3B is a right side view, and FIG. 3C is a cross-sectional view taken along line CC of FIG. 3B. FIGS. 4A and 4B are diagrams showing characteristics of a PTC element. FIG. 5 is a front view showing a second embodiment of the carburetor to which the present invention is applied. FIG. 6 is a longitudinal sectional view of FIG. FIG. 7 is a longitudinal sectional view showing a third embodiment of the carburetor to which the present invention is applied. FIG. 8 is a front view showing a fourth embodiment of the carburetor to which the present invention is applied. FIG. 9 is a right side view of FIG. 8; FIG. 10 is a longitudinal sectional view taken along line XX of FIG. 9; FIG. 11 is a right side view showing a fifth embodiment of the carburetor to which the present invention is applied. [Description of Signs] 1 Carburetor 2 Throttle body (carburetor body) 3 Cap for negative pressure chamber (carburetor component) 6 Float chamber (carburetor component) 8 Venturi passage 10 Throttle valve 14 Slow system 15 Slow air jet (air passage) 16 Slow Outlet (Fuel Outlet) 17 Bypass Outlet (Fuel Outlet) 18 Main System 19 Jet Needle 20 Needle Jet 22 Needle Jet Fuel Outlet 23 Boss Portion for Freezing Prevention Means 24 PTC Element (Freezing Prevention Means) 25 PTC Heater ( Anti-freezing means) 29 Outer peripheral flanges 30 and 31 of float chamber Throttle body connection shaft (carburetor component) 32 Throttle valve connection shaft (carburetor component)

Continuation of the front page (56) References JP-A-2-40063 (JP, A) JP-A-6-50220 (JP, A) JP-A-62-26352 (JP, A) JP-A-56-54941 (JP, A) , A) Japanese Utility Model Application Sho 56-145645 (JP, U) Japanese Utility Model Application Hei 5-17146 (JP, U) Japanese Utility Model Application Hei 6-22553 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB Name) F02M 15/04 H05B 3/14

Claims (1)

(57) [Claim 1] A throttle body, and a carburetor component detachable from the throttle body, wherein the throttle body has a venturi passage and a throttle valve penetrating therethrough. In the carburetor for an engine, which includes a float chamber and a cap for a negative pressure chamber of a piston valve as the carburetor constituent member and supplies an air-fuel mixture to the engine, the float chamber is detachably provided in the throttle body. A float chamber is provided, and a boss is formed integrally with the float chamber. On the other hand, a plurality of fuel outlets and air passages are provided near the throttle valve provided in the throttle body, and an opening is provided at least near the throttle valve. Do The transfer heat antifreeze means while disposed in the boss portion of the float chamber to the charge outlet, the said throttle body
Formed in the float chamber that is detachably provided
The boss part as the outer peripheral flange of the float chamber,
A carburetor for an engine , wherein freezing prevention means is embedded in the outer peripheral flange .