JPH0315787Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a first idle device for a carburetor.

Generally, such a fast idle device improves engine startability by increasing the amount of air supplied to the engine when starting the engine compared to the amount of air when the throttle valve is idling open. They may be interlocked by an interlocking device such as a link, or the throttle valve lever may be driven by a heat-sensing response member such as wax. However, all of these devices have the disadvantage that they not only have a large number of component parts and are expensive, but also have various parts added around the carburetor and cannot be assembled compactly.

In addition, in the case of a device that is mechanically connected to the chiyoke lever, it acts as a resistance to the rotational force of the chiyoke lever, and has the disadvantage that the operation load of the chiyoke lever becomes heavy.

The first idle device for a carburetor according to the present invention has been developed in view of the above points, and it is an object of the present invention to provide a first idle device having a very simple and inexpensive structure with a small number of parts. To provide a compact first idle device having no protrusion to the outside of the main body.
In order to achieve the above object, a first idle hole corresponding to the first idle air amount is bored in the throttle valve itself, and the first idle hole is opened and closed by a control plate made of a shape memory alloy.

Shape memory alloys utilize the phenomenon that occurs when the low-temperature phase generated by thermoelastic martensitic transformation is deformed and then reversely transformed into the high-temperature phase by heating. It changes to an austenite structure at higher temperatures, and changes to a martensitic structure at lower temperatures. When this shape memory alloy is cooled from the high temperature side, it undergoes a transformation from an austenitic structure to a martensitic structure, and has superelasticity; conversely, when it is heated from a low temperature side, the martensitic structure transforms to an austenitic structure, which can be used in the forming process. It returns to the memorized shape. Known alloys that exhibit such a shape memory effect include nickel-titanium, copper-aluminum-nickel, and copper-aluminum.

An embodiment of a first idle device for a carburetor according to the present invention will be described below. 1 is a throttle valve 4 which has an intake passage 2 passing through it, has a ventilary part 2A in the middle thereof, and is rotatably supported on a throttle valve shaft 3 in the intake passage 2 on the downstream side of the ventilium part 2A; and a carburetor main body in which low-velocity nozzle holes (not shown) are opened in the intake passage 2, corresponding to the main nozzle 5 and the throttle valve 4 in the ventilate portion 2A. Further, a chiyoke valve 7 rotatably supported by a chiyoke valve shaft 6 is disposed in the intake passage 2 on the upstream side of the ventilator portion 2A (upper side in the figure).

On the other hand, the throttle valve 4 has a fast idle hole 4A corresponding to the amount of air in the fast idle state.
A control plate 8 made of a shape memory alloy is arranged above the first idle hole 4A to control the opening and closing of the first idle hole 4A. energized.

This control plate controls the drive body 1 when the temperature decreases at the martensitic transformation start point (Ms point).
The bending deformation of No. 1 starts, and this deformation stops when the martensitic transformation end point (Mf point) is reached.

On the other hand, as the temperature increases, the reverse transformation start point (As point)
At , the shape starts to be restored and becomes flat, and the flat deformation ends at the reverse transformation end point (Af point). In this embodiment, the shape of the control plate 8 is memorized so that the control plate 8 bends and deforms when the temperature of the control plate 8 becomes 10° C. or less.

Next, its effect will be explained.

First, when the engine ambient temperature is 10° C. or higher, the control plate 8 deforms to become flat and is pressed by the elastic member 9, so that the control plate 8 keeps the first idle hole 4A closed.

Therefore, in such a temperature state, no air flows into the engine from the first idle hole 4A, so the idling opening of the throttle valve 4 is limited to the throttle valve 4.
This can be accurately controlled by adjusting the gap between the outer periphery of the air intake passage 2 and the intake passage 2. According to this, it is possible to accurately control the amount of idling air in a normal temperature state and obtain good idling operation.

Next, when the engine ambient temperature falls below 10° C., the control plate 8 bends as shown in the figure against the spring force of the elastic member 9, opening the first idle hole 4A. When the first idle hole 4A is opened in this way, the amount of air passing through the first idle hole 4A is increased to the amount of air controlled by the idling opening, and the first idle air amount is obtained, especially at low temperatures. This makes it possible to improve the starting characteristics of the engine. After the engine is started, when the engine warms up and the temperature of the surrounding atmosphere rises, and the temperature of the control plate 8 rises to 10°C or more, the control plate 8 deforms flat and is controlled by the elastic member 9. It closes the hole 4A and functions as a normal throttle valve. According to the first idle device of the present invention, a control hole is formed in the throttle valve, and the opening and closing of the control hole is controlled by a control plate made of a shape memory alloy. Since the first idle air amount could be obtained completely independently, there is no effect on the operability of the choke valve or the operating force of the throttle valve connected thereto.

In addition, as a first idle device, the control hole,
Since only a control plate and an elastic plate are required, an inexpensive first idle device can be obtained with a small number of parts. Furthermore, all the parts can be accommodated within the intake tract and there are no parts that protrude outside the carburetor body, so the degree of freedom in design is increased.

[Brief explanation of the drawing]

The figure is a longitudinal sectional view showing an embodiment of a first idle device for a carburetor according to the present invention. 4... Throttle valve, 4A... Control hole, 8... Control plate made of shape memory alloy, 9... Elastic plate.

Claims (1)

[Scope of utility model registration request] A throttle valve that controls the amount of air flowing through an intake passage that penetrates the carburetor body, a first idle hole formed in the throttle valve, and a control plate made of a shape memory alloy that controls opening and closing of the first idle hole. A first idle device for a carburetor, wherein the control plate comprises an elastic plate urging the first idle hole to close, and the control plate opens the first idle hole at a temperature below a certain temperature.