JPH0240062A - Carburetor - Google Patents

Abstract

PURPOSE:To improve startability right after the starting of an engine and to improve fuel consumption by a method wherein a starter system is communicated to a main system through an air passage, and an amount of air fed through an air passage is controlled according to actuation of a starter plunger. CONSTITUTION:A starter system C is communicated to the open air. The starter system C is communicated to a main system A through an air passage 25. According to actuation of a starter plunger 8, an amount of air fed through the air passage 25 is controlled. While fuel-air mixture is produced through actuation of the starter system C during cold down right after a starting, an amount of air fed to the main system A is limited, and concentration of fuel-air mixture is increased. This constitution improves startability right after the starting of an engine and improves fuel consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a carburetor, and more particularly, to a carburetor that improves starting performance after starting an engine.

[Prior Art] When an engine installed in a vehicle is opened by opening the throttle immediately after starting the engine, it is difficult to vaporize the air-fuel mixture when the engine is cold, so it may be difficult to maintain smooth rotation of the engine. be. For this reason, the vehicle is warmed up before starting, but this is not preferable in the case of a motorcycle because it impairs its maneuverability.

By the way, as shown in Figure 3, the engine required mixture ratio in response to changes in outside temperature is different between the engine rotation sustainability line and the startability line, and in order to achieve both, (starter system flow rate) It is necessary to ensure starting performance by + (main system flow rate).

Therefore, in order to prevent the air-fuel mixture from becoming lean when starting, it is necessary to set the main system low-speed flow rate to the rich side, but if the air-fuel mixture concentration is set to the rich side even during low-speed warm-up. , which is disadvantageous in terms of improving fuel efficiency.

For this reason, for example, as described in Japanese Utility Model Publication No. 58-8929, a negative pressure operating device is provided in the carburetor, and by the operation of this negative pressure operating device, when the starter plunger rises immediately after starting, the main air passage There is a method that controls the amount of air supplied to the fuel mixture so that the concentration of the air-fuel mixture increases.

[Problem to be solved by the invention] However, this carburetor must be specially equipped with a negative pressure operating device, and a negative pressure operating device generally requires a valve, a diaphragm,
The air passage is configured to be switched using a spring or the like, and the structure is complicated and expensive, and moreover, it is undesirable because it is prone to failure.

This invention was made in view of these circumstances, and aims to provide a carburetor that uses a simple mechanism to improve starting performance immediately after starting the engine, and improves fuel efficiency even during low-speed warm-up. .

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a carburetor having a main system for obtaining an air-fuel mixture and a starter system for obtaining an air-fuel mixture by actuation of a starter plunger at the time of startup, in which the starter The system is characterized in that the system is communicated with the main system via an air passage, and the amount of air supplied from the air passage is controlled in accordance with the operation of the starter plunger.

[Function] In the present invention, the amount of air supplied to the main system is controlled in accordance with the operation of the starter plunger of the starter system. In this way, without any special mechanism, by utilizing the operation of the starter plunger in the starter system, the amount of air from the air passage is restricted when the engine is cold immediately after starting, and the concentration of the mixture obtained in the main system is reduced. Make it darker to improve starting performance.

[Example] Next, an example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a carburetor and connections of passages within the carburetor, and FIG. 2 is a cross-sectional view of the vicinity of a starter plunger in a starter system of the carburetor.

Reference numeral 1 in the figure is a carburetor main body, and a piston valve 4 having a jet needle 3 in its mixing chamber 2.
is provided, and is always biased in the direction of closing the intake passage by a spring 4a.

A float chamber 5 is provided at the bottom of the carburetor body 1, and a needle shed 6 that is opened and closed by a jet needle 3 is provided in the float chamber 5, and a main system A is constituted by these.

Finally, pilot jet 7 is installed in float chamber 5.
are provided, and these constitute the slow system B. This slow system B is provided to mainly operate during idling, but it also operates together with the starter system C during startup.
also works.

The carburetor body 1 is further provided with a starter plunger 8 of a starter system C, the plunger chamber 9 of which is connected to a passage 10.
11 to the outside air and the mixing chamber 2, respectively. This passage 10.11 is opened and closed by a piston 13 sliding in the cylinder part 12. This piston 13
A starter needle 14 is supported, and a jet port 15 opened and closed by the starter needle 14 is communicated with the float chamber 5 via a starter pipe 16 and a starter jet 17 .

A support body 18 is arranged above the cylinder part 12, and a wax element 19 is mounted on this support body 18.
The piston 13 is connected to the lower part 19b via a mounting member 20.

Two lead wires 22a and 22b provided in the housing 21 that covers the support 18 are connected to the power generation system, and contact pieces 23a and 23b of the lead wires 22a and 22b are connected to the heating element 24. .

The heating element 24 generates heat when a current flows through the power generation system, and a PTC thermistor, for example, is used as the heating element 24. When the engine is operated, a thermal expansion body built into the wax element 19 expands, and the piston 13 moves up and down via the attachment member 20 of the lower part 19b.

A lower air port 25a of the air passage 25 is provided on the side wall of the cylinder portion 12, an upper air port 25b is provided in the space 26 formed between the cylinder portion 12 and the support body 18 of the wax element 19, and an upper air port 25b is provided below these. airport 2
5a and the air from the upper air port 25b is passed through the air passage 25.
The water is introduced into the needle jet 6 of the main system A via.

An air port 27a is also formed in this space 26, and communicates with the air introduction portion 28 via the air passage 27. The air introduction portion 28 can be configured such that an air hose is inserted into the vehicle body frame and introduced from the vehicle body frame, or the air hose may be connected to the upstream side of the carburetor.

Further, the air introduction section 28 is connected to the pilot jet 7 of the slow system B via an air passage 29, so that the slow system B is communicated with the atmosphere.

Therefore, when the engine starts, the power generation system is not operating.
The temperature of the heating element 24 of the starter system C is low and the piston 13 is in the upper position as shown in FIG. Therefore, the starter needle 14 opens the injection port 15, fuel is supplied to the mixing chamber 2, a rich air-fuel mixture is obtained, and the engine can be started easily.

At this time, since the piston 13 closes the lower air port 25a and the upper air port 25b is open, air is supplied to the main system A from the upper air port 25b via the air passage 25. Therefore, even if a throttle valve (not shown) is opened, the amount of air supplied is suppressed to obtain a relatively highly concentrated air-fuel mixture, which improves the starting performance immediately after starting the engine.

Further, during warm-up, the wax element 19 is operated by the heat generated by the heating element 24, and the piston 13 is lowered to close the plunger chamber 9 and cut off the supply of fuel via the passage 11. Lower air port 25 of section 12
Since a is also opened by the piston 13, the air port 27a
Air is supplied to the main air passage 25 through both air ports 25a and 25b, increasing the amount of air supplied, returning the air-fuel mixture concentration in the main system A to the normal state, and reducing fuel consumption during warm-up. Improvements will be made.

In this way, only while the starter plunger 8 is raised to operate the starter system C and supply the air-fuel mixture, the lower air port 25a is closed and the amount of air supplied from the air passage 25 is restricted, and the main system A The concentration of the air-fuel mixture obtained by the operation of is increased.

As described above, the carburetor of the present invention is a simple mechanism that utilizes the starter system C, and can improve starting performance immediately after starting the engine, and improve fuel efficiency even during low-speed warm-up.

In this embodiment, the two air ports 25a and 25b opened in the cylinder portion 12 are formed apart from each other in the direction of movement of the piston 13, but they may be elongated holes in the direction of movement of the piston 13.

[Effects of the Invention] As explained above, in the present invention, the starter system is communicated with the atmosphere, the starter system is communicated with the main system via the air passage, and the air is discharged from the air passage in response to the operation of the starter plunger. Since the amount of air supplied to the main system is controlled, the amount of air supplied to the main system is limited while the mixture is being obtained by the operation of the starter system when the engine is cold immediately after starting, increasing the concentration of the mixture in the main system.

In this way, with a simple mechanism that uses the starter system to limit the amount of air supplied to the main system without using any special equipment, it improves the starting performance immediately after starting the engine, and also because it does not operate when the engine is warmed up. Efforts will be made to improve fuel efficiency.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the carburetor and the connection of passages within the carburetor, Figure 2 is a cross-sectional view of the area around the starter plunger in the starter system of the carburetor, and Figure 3 is a diagram showing the engine required mixture ratio. . In the figure, 1 is the carburetor main body, 6 is a needle jet, 8 is a starter plunger, 12 is a cylinder part, 13 is a piston, 25a, 25b are air ports, 25 is an air passage, 2
7a is an air port, and 27 is an air passage.

Claims (1)

[Claims] In a carburetor having a main system for obtaining an air-fuel mixture and a starter system for obtaining an air-fuel mixture by actuation of a starter plunger at startup, the starter system is communicated with the main system via an air passage, and the starter system is connected to the actuation of the starter plunger. A vaporizer characterized in that the amount of air supplied from an air passage is controlled accordingly.