JPH0275746A - Starting evaporator - Google Patents

Abstract

PURPOSE:To improve startability at the time of re-start up in a device wherein a venturi part of a starting air-fuel mixture passage is opened and closed by expansion of thermowax by surrounding the thermowax with an insulation jacket, and introducing engine cooling water thereinto. CONSTITUTION:A starting evaporator 6 is formed by arranging a starting plunger 8 movably in a vertical direction on a venturi part of a starting air-fuel mixture passage 7 bypassing between upstream and downstream sides of a venturi part of a main air-fuel mixture passage 5a of a main evaporator 5. A driving part 11, formed by inserting a piston holding part 15a of a wax case 15 housing thermowax therein into an upper part of a retainer 13 whose lower end 13a is inserted in the plunger 8, is arranged upside the plunger 8. A PTC heater 16 is arranged on an upper face of the wax case 15. An insulation jacket 17 is installed on the outside of the driving part 11 so as to circulate engine cooling water between the insulation jacket 17 and a head cover 1a.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a starting carburetor for improving the cold startability of an engine, which is employed in, for example, a motorcycle, and in particular, to a starting vaporizer that is used in motorcycles, for example, to improve the cold startability of an engine. The present invention relates to a starting carburetor that can improve startability when restarting the engine after warming up when the starting plunger is moved to open and close the starting mixture passage.

[Conventional technology]

BACKGROUND ART Conventionally, a carburetor for a motorcycle or the like has generally been a combination of a main carburetor for normal driving and a starting carburetor for improving cold starting performance. This starting carburetor is provided with, for example, a starting mixture passage that bypasses the main mixture passage of the main carburetor, a starting plunger is arranged in a venturi portion of the passage so as to be movable up and down, and a PTC heater and a thermowax are installed. The configuration includes a drive section consisting of. And when starting cold,
The starting plunger is in the raised position, the air-fuel mixture becomes richer, and starting becomes easier. Also, when the engine starts, the heater generates heat, the wax expands and pushes down the plunger, and when warm-up is complete, the above-mentioned starting starts. The air-fuel mixture passage is closed.

[Problem that the invention seeks to solve]

However, with the above-mentioned conventional starting carburetor, when the engine is stopped after warm-up and restarted, there is no problem with startability immediately after the stop or after a considerable period of time has passed.
There is a tendency for startability to be insufficient within a certain period of time in between. This is considered to be due to the following reasons. In other words, after the engine stops, the temperature of the engine itself drops somewhat slowly due to its large heat capacity;
The temperature in the starting carburetor section drops faster than this.

Therefore, during the above-mentioned certain period of time, the engine temperature is still high, so the required mixture concentration is about the same as normal driving, but in the starting carburetor, the wax shrinks due to the temperature drop, resulting in a high concentration mixture. supply. As a result, engine fogging occurs, resulting in poor engine startability.

Therefore, the present invention has been made to solve the above-mentioned eight problems in the conventional art, and by bringing the temperature drop of the starting carburetor closer to the temperature drop of the engine after the engine is stopped, the startability upon restarting is improved. The aim is to provide an improved starting carburetor.

[Means for solving problems]

The present invention provides a starting mixture passage that bypasses the main mixture passage of the main carburetor, and a starting plunger that opens and closes a venturi part of the starting mixture passage, which generates heat when energized when the engine starts. In the starting vaporizer, in which thermowax is expanded by a heater, and the starting plunger is moved by the expansion to change the mixture concentration, at least the thermowax portion is surrounded by a heat insulation jacket, and the engine is placed inside the jacket. It is characterized by the introduction of cooling water or engine lubricating oil.

[Effect]

In the starting carburetor according to the present invention, engine cooling water is placed in the heat insulation jacket that covers the thermowax portion.

Alternatively, since lubricating oil is introduced, the tendency of temperature drop after the engine stops is almost the same in both the engine and carburetor parts, and therefore the required mixture concentration of the engine and the mixture concentration produced by the starting carburetor are the same. - As a result, fogging does not occur when restarting, and starting performance can be improved.

〔Example〕

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

1 to 3 are diagrams for explaining a starting carburetor according to an embodiment of the present invention.

In the figure, 1 is a two-stroke water-cooled engine equipped with the starting carburetor of this embodiment, and the cylinder head la of the engine 1 is connected to a radiator 3 placed in front of the engine 1 via a cooling water hose 2. It is connected. Further, the radiator 3 is connected to a cooling water pump (not shown) disposed in the crankcase 1b, and the pump is connected to a water cooling jacket of the cylinder IC via a cooling water passage formed in the crankcase. This allows cooling water to circulate between the engine 1 and the radiator 3.

Above the crankcase lb of the engine 1, there is a pair of carburetors 4. consisting of a main carburetor 5 and a starting carburetor 6.
4 is placed. This starting carburetor 6 is provided with a starting mixture passage 7 that bypasses between the venturi part and the downstream part of the main mixture passage 5a of the main carburetor 5, and a starting plunger 8 is provided in the venturi part of the passage 7. A starter well 10 communicating with a float chamber 9 is connected below the plunger 8 .

A driving section 11 is disposed above the plunger 8 . Inside the inner case 12b disposed within the outer case 12a of the drive unit 1■, a retainer 13 is vertically movable.
It is arranged so as to be biased upward by a cover spring 13b. The lower end taa of the retainer 13 is inserted into the plunger 8, and a buffer spring 14 is disposed between this and the jet needle 8a. Further, a piston support portion 15a of a wax case 15 that accommodates thermowax inside is inserted into the upper part of the retainer 13, and the support portion 15a is inserted into the upper portion of the retainer 13.
The piston 15b protruding downward from the retainer 13
is in contact with the bottom of the In addition, the wax case 15
A PTC heater 16 is arranged on the upper surface of the . Electrode plates 16a are arranged on the upper and lower surfaces of this heater 16! and a power supply lead wire 1 connected to each electrode plate 16a.
6b is led out to the outside through between the outer and inner cases 12a and 12b, and generates an electric current as the engine rotates.
C generator (not shown).

A heat insulation jacket 17 is provided on the outside of the drive unit 11.
The jacket 17 is sized to cover the outer case 12a. In addition, an inlet 17a formed at the upper edge and lower edge of the jacket 17,
An introduction hose 18. The branch side ends 18a and 19a of the discharge hose 19 are connected, and the confluence side ends 18b and 19b of the hose 18 and 19 are connected in communication with the cooling water jacket of the head cover 1a. Thereby, engine cooling water is circulated between the heat insulation jacket 17 of the starting carburetor 6 and the head cover 1a.

Next, the effects of this embodiment will be explained.

In the carburetor 4 of this embodiment, during cold starting, the thermowax contracts and its piston 15b is pushed up to the upper end position by the spring 13b together with the retainer 13, so the starting plunger 8 is positioned at the rising end. and
The starting mixture passage 7 is fully open. Therefore, engine negative pressure due to cranking during engine startup mainly acts on this starting air-fuel mixture passage 7, and as a result, a highly concentrated air-fuel mixture is supplied to the engine 1, making cold starting easier.

Then, when the engine 1 starts, current from the A/C generator is supplied to the heater 16, and due to the heat generated, the thermowax expands and gradually moves into the starting plunger 8.
is lowered to gradually close the starting mixture passage 7, and at the end of the warm-up operation, the starting mixture passage 7 is fully closed, and the mixture concentration drops to the concentration during normal running.

In the device of this embodiment, the air-fuel mixture concentration is automatically adjusted as described above, and engine cooling water is circulated between the head cover 1a and the heat insulation jacket 17.

Therefore, the temperature near the drive part of the starting carburetor 6 increases or decreases under substantially the same conditions as the engine part.

When equipped with a conventional starting carburetor, when the engine is stopped after warming up, the temperature around the carburetor decreases compared to the temperature drop rate of the engine itself (characteristic line A), as shown in Figure 3 (al). Due to the high speed (characteristic kIAB), there was a problem that restartability after a certain period of time had passed.In contrast, in this embodiment, the engine cooling water was
7 and the head cover la, the temperature near the drive unit 11 decreases at the same rate as the cooling water temperature, as shown in Figure 3), and eventually the temperature of the engine itself decreases. This indicates approximately the same -+lrJ as the descent. As a result, the required mixture concentration on the engine side and the mixture concentration from the starting carburetor match, which solves the problem of the mixture concentration being too high at the time of restart, and improves restartability.

In the above embodiment, engine cooling water was introduced into the starting carburetor section, but in the present invention, engine lubricating oil may be introduced into this section.

Further, in the present invention, by introducing engine cooling water etc. into the starting carburetor part, the temperature drop in the carburetor part is brought closer to the temperature drop in the engine itself. Forming a heat insulating layer on the outer case portion is also effective in bringing the temperature drop tendency of this portion closer to the engine itself. This heat insulating layer consists of, for example, a double outer case and a material with low thermal conductivity (for example, air) inside.

This can be achieved by filling it with water (water) or by pasting insulation material inside the outer case.

〔Effect of the invention〕

As described above, according to the starting carburetor according to the present invention, a heat insulating jacket is formed to cover the driving part of the starting carburetor, and cooling water etc. are introduced into the jacket, so that heating is possible. When the engine is stopped after a flight, the temperature drop trend in the starting carburetor section can be brought close to the temperature drop trend in the engine itself, which has the effect of improving restartability by making the air-fuel mixture concentration appropriate when restarting. There is.

[Brief explanation of the drawing]

1 to 3 are diagrams for explaining a starting carburetor according to an embodiment of the present invention, FIG. 1 is a cross-sectional side view thereof, and FIG. 2 is a diagram of an engine equipped with the carburetor. Perspective view,
Figure 3 (al is a diagram showing a temperature drop trend for explaining the conventional problem, Figure 3 (bl is a diagram showing a temperature drop trend of the present invention). In the figure, 5 main carburetors, 5a are Main mixture passage, 6 is a starting carburetor, 7 is a starting mixture passage, 8 is a starting plunger, 16 is a PTC heater, 17 is a heat insulation jacket, 1
8.19 is a cooling water hose. Patent Applicant Yamaha Motor Co., Ltd. Agent Patent Attorney Tsutomu Shimofu Figure 1 Figure 2 Figure 3 (a) (b)

Claims (1)

[Claims] (1) A starting mixture passage that bypasses the main mixture passage of the main carburetor is provided, a starting plunger is provided to open and close the venturi part of the starting mixture passage, and a heater that generates heat when the engine starts generates heat. In a starting vaporizer that expands wax and moves the starting plunger due to the expansion to change the mixture concentration, at least the thermowax portion is surrounded by a heat insulation jacket, and engine cooling water or A starting carburetor characterized by introducing engine lubricating oil.