JP2516764B2 - Sliding throttle valve carburetor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding throttle valve type carburetor adapted to correct a fuel flow rate under a constant condition.

(Prior Art) In an internal combustion engine, a rich air-fuel mixture is required at high load and high rotation, but as a means for correcting the fuel flow rate at this high load and high rotation, a power jet system or an improved version thereof (see, for example No. 45-805) is known.

(Problems to be Solved by the Invention) In the conventional power jet method, the correction flow rate of the fuel is uniquely determined by the opening of the sliding throttle valve, that is, the value of the negative pressure in the mixing chamber. It will be decided.

However, the fuel correction amount may be different from that in a normal use environment depending on the use environment of the internal combustion engine (for example, an extremely cold region), and in such a case, there is a disadvantage that the conventional power jet method cannot deal with. is there.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a sliding throttle valve type carburetor capable of appropriately correcting the fuel flow rate according to the usage environment of the internal combustion engine. .

(Means for Solving the Problems) In order to achieve the above object, the present invention has a sliding throttle valve that slides at a right angle to the air flow in the main bore of the mixing chamber. In the sliding throttle valve type carburetor configured to move the jet needle bound to it in the main nozzle communicating with the float chamber, thereby changing the opening area of the main nozzle,
A first fuel passage and a second fuel passage are formed at a position upstream of the sliding throttle valve in the mixing chamber, and one end of each of the first and second fuel passages is formed as a sliding throttle valve sliding surface of the mixing chamber. And opening the other end of the first fuel passage to communicate with the float chamber via a fuel pipe.
The other end of the fuel passage is opened at a position near the air intake port of the main bore, and the sliding throttle valve has a U-shaped fuel passage communicating with the first and second fuel passages in a high opening range. The flow rate of the fuel injected into the main bore is adjusted, and an opening / closing means constituted by a valve is provided in the middle of the fuel pipe.

(Operation) According to the present invention, the U-shaped fuel passage formed in the sliding throttle valve serves as the mixing chamber when the sliding throttle valve is in the high opening range and the load is high at a high speed in the internal combustion engine. Since it communicates with the formed first and second fuel passages, the negative pressure generated in the main bore pulls the fuel in the float chamber from the upstream side of the sliding throttle valve of the main bore through the fuel passage to inject fuel. However, if the flow of the fuel in the fuel pipe is controlled by the opening / closing means according to the usage environment of the internal combustion engine, the proper fuel can always be supplied.

(Example) Below, the Example of this invention is described based on an accompanying drawing.

First, a schematic structure of a motorcycle equipped with a sliding throttle valve carburetor according to the present invention will be described with reference to the side view of FIG. 2. In FIG. A front wheel 2 is rotatably supported on the lower end.

An engine 3, which is a drive source, is mounted in the substantial center of the vehicle body, and a fuel tank 4 is provided above the engine 3.
However, seats 5 are arranged behind the fuel tank 4, respectively. A sliding throttle valve type carburetor 6 according to the present invention is connected to an intake system of the engine 3, and an air cleaner (not shown) is connected to the sliding throttle valve type carburetor 6. An exhaust pipe 7 is led out from the exhaust system of the engine 3.

Here, details of the sliding throttle valve type carburetor 6 will be described with reference to the longitudinal sectional view of FIG.

In FIG. 1, reference numeral 8 denotes a Venturi tube-shaped mixing chamber in which a main bore 9 whose cross-sectional area is rapidly reduced in the air flow direction (the direction of arrow a in the figure).
Are formed. A sliding throttle valve 10 is vertically slidably fitted to a boss portion 8a formed in the upper portion of the mixing chamber 8, and the lower end of the sliding throttle valve 10 is tapered downward. The jet needle 11 is bound. The sliding throttle valve 10 is always urged downward (throttle side) by a spring (not shown), and the sliding throttle valve 10 is connected to an accelerator portion via a throttle wire (not shown).

On the other hand, a float chamber 12 is provided below the mixing chamber 8, and the float chamber 12
A fuel is contained in the inside, and the liquid level of this fuel is always kept constant by a float (not shown). Further, a main nozzle 13 communicating with the inside of the float chamber 12 faces the same axis as the jet needle 11 of the main bore 9 of the mixing chamber 8, and the jet needle 11 can move back and forth in the main nozzle 13. Facing.

By the way, a first fuel passage 14a and a second fuel passage 14c are formed on the upstream side (right side in FIG. 1) of the sliding throttle valve 10 of the mixing chamber 8, and the first and second fuel passages are formed. 1
One end of each of 4a and 14c is opened to the sliding surface 8a-1 of the boss portion 8a of the mixing chamber 8 (the inner peripheral surface of the boss portion 18a on which the sliding throttle valve 10 slides). The other end of the first fuel passage 14a communicates with the inside of the float chamber 12 via the fuel pipe 15, and the other end of the second fuel passage 14c has a fuel discharge hole 16
The main bore 9 is open at a position near the air intake port. A fixed jet 17 for regulating the flow rate is provided in the middle of the first passage 14a.

Further, the sliding throttle valve 10 communicates with the first fuel passage 14a and the second fuel passage 14c as shown in the drawing when the sliding throttle valve 10 is in a high opening state including a fully opened state. A U-shaped fuel passage 14b is formed.

A valve 19 forming an opening / closing means is provided in the middle of the fuel pipe 15.

 Next, the operation of the sliding throttle valve type carburetor 6 will be described.

If the sliding throttle valve 10 is moved up, for example, in FIG. 1 by operating the accelerator part, the jet needle attached to this
11 moves upward in the main nozzle 13, and as a result, the opening area of the main nozzle 13 increases and the flow rate of the fuel flowing from the float chamber 12 through the main nozzle 13 into the main bore 9 increases. In the engine 3 shown in FIG. 2, during low / medium load operation in which the opening of the sliding throttle valve 10 is small, the first and second fuel passages 14a, 14c are closed by the sliding throttle valve 10 and both are closed. Is cut off, and therefore, the fuel correction described later is not performed when the engine 3 is operating at low and medium loads.

When the sliding throttle valve 10 is further moved up and this is in a high opening range including full opening, the sliding throttle valve 10
Since the U-shaped fuel passage 14b formed in 10 communicates with the first and second fuel passages 14a and 14c as shown in FIG. 1, the negative pressure generated in the main bore 9 causes the inside of the float chamber 12 to be drawn. Fuel of the fuel pipe 15 and the fuel passage 14a, 14b, 14c
Through the fuel discharge hole 16 toward the main bore 9 and the fuel flow rate is corrected. This corrected fuel flow rate is larger as the negative pressure in the main bore 9 is higher, that is, as the opening degree of the sliding throttle valve 10 is larger, but its absolute value is U-shaped in the first and second fuel passages 14a, 14c. It can be arbitrarily adjusted by changing the area of communication with the fuel passage 14b. Since the fuel flowing through the fuel pipe 15 is controlled by opening and closing the valve 19, if the valve 19 is opened and closed according to the usage environment of the engine 3 to control the fuel flowing through the fuel pipe 15, a proper fuel is always supplied. can do.

Therefore, at the time of high load operation, the rider should properly correct the fuel flow rate according to environmental conditions such as temperature and atmospheric pressure, and
It can be done easily.

In the present embodiment, the fuel pipe 15 is opened to the atmosphere,
Air may be bleeded into the main bore 9 from the fuel discharge hole 16.

(Effects of the Invention) As apparent from the above description, according to the present invention, the second
Since the fuel passage opens in the vicinity of the air intake port of the main bore, atomization of the correction fuel flowing out into the main bore is promoted, and since variable jets are provided at two locations, the appropriate fuel flow rate is provided. Can be corrected.

Further, although the opening / closing means constituted by the valve is provided in the middle of the fuel pipe, the valve can be kept open at this opening / closing means, so that the first fuel passage and the second fuel passage are communicated with each other. When this is done, fuel is immediately ejected, the response is improved, and the valve structure is simplified.

Further, when the amount of fuel increased at the time of high load and high speed of the internal combustion engine becomes excessive and the mixture concentration becomes too rich, the opening / closing means can be closed, so that the output reduction of the internal combustion engine can be prevented.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a sliding throttle valve type carburetor according to the present invention, and FIG. 2 is an overall side view of a motorcycle. 6 ... Sliding throttle valve carburetor, 8 ... Mixing chamber, 9 ... Main bore, 10 ... Sliding throttle valve, 11 ... Jet needle, 12 ... Front chamber, 13 ... Main nozzle, 14a, 14b, 14c …… fuel passage, 16 …… fuel discharge hole, 19 …… valve (opening / closing means).

Claims (1)

(57) [Claims] 1. A main nozzle having a sliding throttle valve that slides at a right angle to an air flow in a main bore of a mixing chamber, and a jet needle attached to the sliding throttle valve to communicate with the float chamber. A sliding throttle valve type carburetor configured to move inside of the main nozzle so as to change the opening area of the main nozzle, wherein a first fuel passage and a second fuel passage are provided at a position upstream of the sliding throttle valve in the mixing chamber. And forming one end of each of the first and second fuel passages in the sliding throttle valve sliding surface of the mixing chamber and connecting the other end of the first fuel passage to the float chamber via a fuel pipe. , The other end of the second fuel passage is opened in the vicinity of the air intake port of the main bore, and the sliding throttle valve has a U-shape communicating with the first and second fuel passages in a high opening range. Of the sliding throttle valve type carburetor, characterized in that the fuel passage is formed to adjust the flow rate of the fuel injected into the main bore, and an opening / closing means constituted by a valve is provided in the middle of the fuel pipe.