JP2694909B2 - Carburetor for starting - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a carburetor for start-up, which is used in, for example, a motorcycle for improving cold startability of the engine, and particularly relates to a temperature condition of the engine. The present invention relates to a starting carburetor capable of accurately responding to an engine temperature condition and responsiveness when a starting plunger and a needle are automatically moved up and down.

[Conventional technology]

Conventionally, as a carburetor in a motorcycle or the like, it is general to employ a carburetor that is a combination of a main carburetor for normal traveling and a starting carburetor for improving cold startability. This starting carburetor is provided with, for example, a starting mixture passage that bypasses the main mixer passage of the main carburetor, a starting plunger is arranged in the venturi portion of the passage so as to be vertically movable, and a PTC heater and a thermo wax. It is configured to include a drive unit consisting of. And at cold start,
The starting plunger is located at the upper portion to open the starting air-fuel mixture passage, so that the air-fuel mixture concentration is high and the starting is facilitated. When the engine is started, the heater heats up, the wax expands, the plunger is pushed down gradually, and the starting air-fuel mixture passage closes when the warm-up ends.

[Problems to be solved by the invention]

However, in the above-described conventional carburetor for start-up, when the engine is stopped and restarted at the end of the warm-up operation, there is no problem in startability immediately after the stop or after a considerable time has passed, but there is a certain intermediate value. Startability in time tends to be insufficient. This is considered to be due to the following reasons. That is, after the engine is stopped, the temperature of the engine itself drops to some extent slowly because the engine itself has a large heat capacity, whereas the temperature of the starting carburetor part drops earlier than this.
Therefore, within the above-mentioned fixed time, the engine temperature is still high, so the required air-fuel mixture concentration is about the same as in normal running, whereas in the start-up carburetor, the wax contracts due to the temperature decrease, and the high-concentration air-fuel mixture is To supply. As a result, the engine fogging phenomenon occurs, and it is considered that the engine startability is not good.

Therefore, the present invention has been made to solve the above-mentioned conventional problems, and provides a starting carburetor capable of accurately responding to the temperature condition of the engine and with good responsiveness and improving the starting property at the time of restarting. The purpose is to do.

[Means for solving the problem]

According to the present invention, a starting mixture passage 7 that bypasses the main mixture passage 5a of the main vaporizer 5 is provided, and a plunger 8 that opens and closes the venturi portion of the starting mixture passage 7 is provided. In the starting carburetor 6 in which the mixture concentration is changed depending on the position, the small diameter cylinder portion 13a of the retainer 13 is coupled to the plunger 8 and the retainer 1
Cylinder part 1 of guide part 12c of case 12
2f is slidably and oil-tightly fitted, the piston 15 is slidably inserted into the cylinder portion 12f, the tip of the piston 15 is brought into contact with the retainer 13, and the large diameter cylinder of the retainer 13 is attached. Department
A large-diameter urging spring 13b for urging the terryner 13 in the opening direction is disposed between the case 13c and the case 12, and the jet needle 8a of the plunger 8 and the small-diameter cylindrical portion 13a are provided with the jet needle. A small-diameter biasing spring 14 that biases 8a in the closing direction,
At least a portion of the pressure spring 12b is arranged so as to overlap the large-diameter biasing spring 13b in the axial direction, and a pressure chamber 12d having a diameter larger than that of the piston 15 is formed in the guide portion 12c.
A pressure-sensitive hose 16 having a diameter smaller than that of the piston 15 is connected and connected to the temperature-sensing case 17 in the engine. The temperature-sensing case 17 is connected to the temperature-sensing chamber 17c and the pressure-generating chamber 17 by a diaphragm 17b.
The temperature sensitive chamber 17c is filled with a thermowax 17a that expands in volume according to the engine temperature, and the other end of the pressure transmitting hose 16 is connected to the pressure generating chamber 17d so as to communicate with the pressure generating chamber 17d. It is characterized in that hydraulic oil is enclosed in the generation chamber 17d, the pressure transmission hose 16, and the pressure chamber 12d.

[Action]

According to the carburetor for start-up according to the present invention, the temperature-sensitive case 17 arranged on the engine side is defined by the diamond plum 17b into the temperature-sensitive chamber 17c and the pressure generating chamber 17d, and the thermowax is provided in the temperature-sensitive chamber 17c. Since 17a is filled and the pressure generating chamber 17d, the pressure transmission hose 16 and the pressure chamber 12d are filled with hydraulic oil,
When the thermowax 17a expands in accordance with the engine temperature, this expansion amount can be surely converted into the moving amount of the hydraulic oil and the piston 15 can be moved reliably, and as a result, the mixture concentration according to the temperature state of the engine can be increased. can get.

Piston 1 through expansion of thermowax 17a via hydraulic oil
In the case of the method of transmitting the hydraulic fluid to the piston 5, there is a concern that the hydraulic oil may leak from the piston 15 side. Since it is fitted to the, it is possible to prevent leakage of hydraulic oil.

Also, a large-diameter biasing spring that biases the retainer 13 in the opening direction.
Since 13b and the small-diameter biasing spring 14 that biases the jet needle 8a in the closing direction are arranged so that at least a part thereof wraps in the axial direction, the retainer biasing spring 13b and the jet needle biasing force are set. While providing the spring 14, it is possible to suppress expansion of the axial length.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 and 2 are views for explaining a starting carburetor according to a first embodiment of the present invention.

In the figure, reference numeral 1 is a two-cycle water-cooled engine equipped with a start-up carburetor of the present embodiment, and a cylinder head 1a of the engine 1 is connected to a radiator 3 arranged in front of the engine 1 by a cooling water hose 2. It is connected. Further, the radiator 3 is connected to a cooling water pump (not shown) arranged in the cunk case 1b, and the pump is connected to a cylinder 1c via a cooling water passage formed in the crank case 1b.
The cooling water is circulated between the engine 1 and the radiator 3 by means of the water cooling jacket.

A pair of carburetors 4, 4 consisting of a main carburetor 5 and a starting carburetor 6 are provided above the crankcase 1b of the engine 1.
Is arranged. The starting vaporizer 6 is the main vaporizer 5
Is provided with a starting mixture passage 7 for bypassing between the upstream part and the downstream part of the venturi part of the main mixture passage 5a, and a starting plunger 8 (opening / closing member) having a needle 8a fixed to the venturi part of the passage 7 is provided. A vertically movable starter well 10 communicating with the float chamber 9 is provided below the plunger 8.

A drive unit 11 is arranged above the plunger 8. The case 12 of the drive unit 11 is composed of an outer case 12a and an inner case 12b that surrounds a guide portion 12c integrally formed with the axis of the outer case 12a. The guide portion 12c includes a hydraulic chamber 12d and a cylinder portion coaxial with the hydraulic chamber 12d.
12f and are formed. A retainer is provided on the cylinder portion 12f.
The large-diameter cylindrical portion 13c of 13 is slidably and oil-tightly fitted, and the retainer 13 is biased upward (in the opening direction) by a biasing spring 13b.

Further, the small-diameter cylinder portion (lower end portion) 13a of the retainer 13 is engaged with the upper end of the plunger 8, and the needle 8a is closed between the small-diameter cylinder portion 13a and the jet needle 8a of the plunger 8. A biasing spring 14 for biasing is provided.
The upper part of the biasing spring 14 is located in the lower part of the biasing spring 13b and wraps in the axial direction.

A piston 15 as a drive member is vertically movably inserted in the guide portion 12c, and an upper end of the piston 15 faces a hydraulic chamber 12d formed in the guide portion 12c. The hydraulic hose 16 is installed in the hydraulic inlet 12e of the hydraulic chamber 12d.
One end 16a of is connected.

The other end 16b of the hydraulic hose 16 is connected to a temperature sensing portion 19 formed in the cylinder head 1a of the engine 1, as shown in a model in FIG. The temperature sensing section 19 has a temperature sensing case 17 arranged in the cooling jacket of the head cover 1a, and the temperature sensing case 17 is divided into a greenhouse 17c by a diaphragm 17b and a pressure generating chamber 17d to which the hydraulic hose 16 is connected. Defined and thermowax 1 as a temperature sensitive member in the greenhouse 17c
It is configured by filling 7a. This Thermo Wax 17a
Expands and contracts as the engine coolant temperature rises and falls. Further, a hydraulic oil 18 (liquid transmission medium) for transmitting the expansion operation of the wax 17a to the piston 15 is enclosed in the pressure generating chamber 17d of the temperature sensitive case 17, the hydraulic hose 16 and the hydraulic chamber 12d. ing.

Next, the operation and effect of this embodiment will be described. In the apparatus of the present embodiment, at the time of cold start, the thermowax 17a is contracted, the retainer 13 is pushed up together with the piston 15 by the spring 13b, and the plunger 8 is located at the rising end thereof. 7 is fully open.
Therefore, the engine negative pressure mainly acts on the starting air-fuel mixture passage 7 due to cranking at the time of engine start, and as a result, a high-concentration air-fuel mixture is supplied to the engine 1 and the engine 1 is easily started.

Then, when the engine 1 is started, the warm-up operation proceeds, and the temperature of the engine cooling water rises, the thermowax 17a
Gradually expands, and this expanding action is transmitted to the hydraulic chamber 12d by the diaphragm 17b pressurizing the hydraulic oil 18, and the hydraulic oil 18 in the hydraulic chamber 12d pushes down the piston 15. This causes the retainer 13 to lower the plunger 8,
The mixture passage 7 for start-up is gradually closed, and is fully closed at the end of the warm-up operation. As a result, the air-fuel mixture concentration decreases to the normal traveling concentration.

When the engine 1 is stopped, the thermowax 17a contracts according to the temperature drop of the engine cooling water, the retainer 13 is pushed up by the spring 13b according to the contraction amount, and the plunger 8 opens the mixture passage 7. The air-fuel mixture concentration increases as the temperature of the engine 1 drops.

When the conventional starting carburetor was provided, when the engine was stopped after warming up, the temperature drop rate around the carburetor was faster than the temperature drop of the engine itself, so there was a problem of poor restartability. . On the other hand, in the present embodiment, the thermowax 17a is directly expanded and contracted at the engine cooling water temperature, and the plunger 8 is lowered by the expansion operation, so that the engine temperature and the temperature around the carburetor are There is no problem caused by the difference, and as a result, the problem that the required mixture concentration on the engine side and the mixture concentration from the start-up carburetor 6 match and the mixture functionality at restart is too high can be solved. The restartability can be improved.

Although the thermowax is expanded and contracted by the engine cooling water in the first embodiment, the thermowax may not necessarily be the cooling water, and the point is that the temperature sensitive member is expanded and contracted at the temperature of the engine. Well, for example, the lubricating oil temperature may be used.

By the way, in the present invention, the thermowax is expanded and contracted depending on the engine temperature. However, as shown in FIG. 3, when the carburetor having the icing prevention PTC heater 20 is provided, this heater 20 It is also possible to configure the temperature sensing unit 19 by utilizing.

〔The invention's effect〕

As described above, according to the carburetor for start-up according to the present invention, the temperature-sensitive case on the engine side is defined by the diaphragm into the temperature-sensitive chamber and the pressure generating chamber, and the temperature-sensitive chamber side is filled with thermowax, and the pressure is increased. Since the generation chamber side is filled with hydraulic oil, the expansion of the thermowax can be reliably transmitted to the piston via the hydraulic oil, and the mixture concentration according to the temperature condition of the engine can be obtained, which has the effect of improving startability. .

Also, the large-diameter cylindrical part of the retainer is slidably and oil-tightly fitted to the cylinder part, and the bias spring for the plunger and the bias spring for the jet needle are arranged so that at least a part of them overlaps in the axial direction. Therefore, there is an effect that the leakage of hydraulic fluid can be prevented while suppressing the expansion of the dimension in the height direction.

[Brief description of the drawings]

1 and 2 are views for explaining a starting carburetor according to a first embodiment of the present invention. FIG. 1 is a sectional side view of the carburetor, and FIG. 2 is an engine equipped with the carburetor. Perspective view of
FIG. 3 is a cross-sectional view showing a temperature sensitive portion outside the scope of the present invention. In the figure, 1 is an engine, 5 is a main vaporizer, 5a is a main mixture passage, 6 is a starting carburetor, 7 is a starting mixture passage,
8a is a starting plunger and a needle (opening / closing member), 16 is a hydraulic hose (transmission passage), 17a is a thermowax (temperature sensitive member), 18 is hydraulic oil (liquid transmission medium), 24 is a transmission cable, 25 is a needle ( Opening / closing member), 29 is a double spiral bimetal (temperature sensitive member).

Claims (1)

(57) [Claims] 1. A mixture mixture for starting, which bypasses the main mixture passage of a main vaporizer, is provided with a plunger for opening and closing a venturi portion of the mixture passage for starting, and the mixture concentration depends on the position of the plunger. In the carburetor for start-up, the small-diameter cylinder part of the retainer is connected to the plunger, and the large-diameter cylinder part of the retainer is slidably and oil-tightly fitted on the cylinder part of the guide part of the case. Then, the piston is slidably inserted into the cylinder portion, the tip of the piston is brought into contact with the retainer, and the retainer is urged in the opening direction between the large-diameter cylindrical portion of the retainer and the case. A urging spring having a diameter, and a urging spring having a small diameter for urging the jet needle in the closing direction between the jet needle of the plunger and the small diameter cylindrical portion of the retainer, at least a part of which has the large diameter. Bias of A pressure chamber having a diameter larger than that of the piston is formed in the guide portion so as to wrap in the axial direction, and one end of a pressure transmission hose having a diameter smaller than that of the piston is connected to the pressure chamber for communication with the engine. A temperature-sensitive case is arranged, the temperature-sensitive case is defined by a diaphragm into a temperature-sensitive chamber and a pressure-generating chamber, and the temperature-sensitive chamber is filled with thermowax that expands in volume according to the engine temperature. A carburetor for start-up, comprising the other end of which is communicatively connected to the pressure generating chamber, and hydraulic oil is enclosed in the pressure generating chamber, the pressure transmitting hose, and the pressure chamber.