JPH0143147B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a power device for a carburetor that is capable of automatically adjusting the amount of power fuel supplied when the engine is at high load or full load depending on the temperature. It is something.

(Prior art and its problems) Many of the power devices that supply additional power fuel to obtain the output mixture ratio when the engine is at high load or full load open the power valve using the engine's intake negative pressure. It is configured.

In such power equipment, the amount of power fuel supplied is adjusted in accordance with temperature changes from the perspective of exhaust gas countermeasures and fuel economy, and the output mixture ratio is controlled by reducing the amount at high temperatures and increasing it at low temperatures to maintain an output mixture ratio that does not vary due to temperature. It is clear that it is desirable to have stable output performance. For this purpose, a bimetal is interposed between the valve that controls the power fuel and its operating rod (see Japanese Patent Application Laid-Open No. 106035/1983), and atmospheric air is introduced into the negative pressure chamber of the power device at low temperatures to increase the valve opening. It has been proposed to make adjustments by increasing the size of Not only that, but it is inevitable that the structure will become more complex.

The present invention provides a control spring made of a shape memory alloy in addition to a closing spring that closes the power valve and an actuating spring that opens the power valve, thereby installing a special device and The opening of the power valve is adjusted according to temperature changes with an extremely simple structure without any special processing, and the amount of power fuel supplied is automatically adjusted.

(Means for Solving the Problems) The present invention provides a power valve for controlling power fuel, a piston having an operating rod that is operated by engine intake negative pressure to open and close the power valve, and a valve body of the power valve. In a carburetor power device comprising a valve closing spring acting on the actuating rod and an actuating spring acting in the valve opening direction acting on the actuating rod, a coil-shaped control spring made of a shape memory alloy is attached to the piston. and the control spring has a structure in which the coil length expands and contracts so that the opening degree of the power valve increases when the temperature is low and decreases when the temperature is high by controlling the operation of the operation rod by the operation spring. This is a means to solve the above problems.

A material with a shape memory effect, that is, a shape memory alloy, is known as a material that reversibly changes shape with changes in temperature due to thermoelastic martensitic transformation.
By heat-treating at a temperature higher than A _f to memorize the original shape, and processing and deforming it into the desired shape at a temperature lower than the martensitic transformation end temperature M _f , the original shape and the deformed shape can be changed within the transition temperature range. It is also known that the shape reversibly changes between When a coiled spring is made of a shape memory alloy, if the memorized original shape is compressed at a temperature lower than the above M _f and deformed so that the coil length becomes shorter, the spring will elongate as the temperature rises. Shrinks as temperature decreases. Conversely, when the spring is stretched and deformed so that the coil length becomes longer, the spring contracts as the temperature rises and expands as the temperature falls.

Figure 1 shows the relationship between the minimum T _L and maximum transition temperature T _H of a coiled spring made of shape memory alloy, and the amount of deformation and load at temperatures T ₁ , T ₂ , and T ₃ between them. This is a characteristic curve diagram showing that the amount of deformation is very small in the high temperature region (Figure a).
It can be seen that the spring deforms to a practically effective amount only in a limited low temperature range. When the load of a bias spring made of a metal material without shape memory effect is applied to this spring, the spring deforms along the line S and the amount of deformation is b from the lowest transition temperature T _L. A practically effective deformation is performed in the entire range up to the maximum T _H. Changing the initial load or spring characteristics of the bias spring results in a deformation along a line parallel to line S.

In addition, when the temperature changes, the temperature at which the same amount of deformation is reached differs when the temperature rises and when the temperature falls, but bias springs not only help reduce or eliminate this difference due to hysteresis, but also By constantly applying a load to the accompanying expansion and contraction of the spring, controlled displacement can also be achieved.

As mentioned at the beginning, the purpose of the present invention is to adjust the amount of power fuel supplied at high loads or at full temperature depending on the temperature, that is, the temperature of the atmosphere or the engine, and for this purpose, a material having a shape memory effect is used. The opening degree of the power valve is adjusted depending on the temperature by using the phase dislocation phenomenon caused by thermoelastic martensitic transformation, and the spring made of shape memory alloy can be used at temperatures below the above-mentioned M _f and above A _f . In addition to being used at a temperature between M f and A f , it may also be used at an appropriate temperature range between M _f and A _f .

(Example) Embodiments of the present invention will be described with reference to the drawings.

2 and 3, a power valve 4 having a valve seat 1, a conical or needle-shaped valve body 2, and a coil-shaped valve closing spring 3 is provided inside a float chamber 5, and above the power valve 4 there is a suction negative pressure. Negative pressure chamber 6 and piston 7 into which
is arranged, a downward operating rod 8 protruding from the piston 7 is inserted into the float chamber 5, and a coil-shaped operating spring 9 acting on the operating rod 8 acts in the direction of opening the power valve 4. There is. These valve closing spring 3 and actuating spring 9 are made of ordinary metal materials that do not have a shape memory effect.

When the suction negative pressure becomes low, the piston 7 is activated by the actuating spring 9.
The operating rod 8 pushes the valve body 2 away from the valve seat 1. The fuel in the float chamber 5 flows through the gap between the valve seat 1 and the valve body 2 into the main system through the power jet.

In the embodiment shown in FIG. 2, a coil-shaped control spring 10 acts on the piston 7 in the upward direction and limits the opening of the power valve 4 in opposition to the operating spring 9 _. It is made by heat-treating at a temperature higher than M _f to memorize its original shape, and then compressing and deforming it at a temperature lower than M f .

The control spring 10 contracts when the temperature is low and does not interfere with the opening of the power valve 4, but when the temperature is high it expands and prevents or restricts the operation of the operating rod 8 by the operating spring 9, preventing the power valve 4 from opening. Stop at a small opening. Further, in this embodiment, the actuating spring 9 acts as a bias spring for the control spring 10, and controls the displacement of the actuating rod 8 at low to normal temperatures.

In the embodiment shown in FIG. 3, a control spring 11 acting in a downward direction acts on the piston 7, and a control built in this negative pressure chamber 6 acts in the direction of opening the power valve 4 in opposition to the valve closing spring 3. The spring 11 is heat treated at a temperature higher than A _f to memorize its original shape _.
It is made of a material that has been stretched and deformed at a lower temperature than the above.

When the temperature is low, the control spring 11 expands and pushes down the piston 7, so that even in the operating region where the suction negative pressure is high, the power valve 4
is opening the door. As the temperature rises, the control spring 11
is contracted, the force acting on the piston 7 is reduced, and the power valve 4 is opened as in the conventional case.

In addition, in these embodiments, the control springs 10, 1
The spring force of 1 is always applied to the piston 7,
When the valve closing spring 3 and the operating spring 9 are balanced, the power valve 4
There is no inconvenience of delaying the start of opening of the valve.

(Effects of the Invention) According to the present invention, in addition to the valve closing spring and operating spring that control the opening and closing of the power valve, a coiled control spring made of a shape memory alloy is applied to the piston. The power fuel can be automatically adjusted according to the temperature by simply charging it into the negative pressure chamber of the piston, etc., without installing a device, performing special processing, or adding complicated parts. , it is possible to obtain stable output performance. In addition, the control spring not only adjusts the opening of the power valve, but also opens the power valve at room temperature to replenish fuel in the normal operating range when the temperature is extremely low, or conversely, forces the power valve to open at extremely high temperatures. It is also possible to provide functions beyond the functions of conventional power valves, such as closing the valve to prevent additional fuel from being supplied.

Furthermore, coiled springs made from shape memory alloys have the advantage of being able to change length due to temperature changes larger than bimetals whose shape changes due to heat, as well as being highly reliable in operation. Power fuel can be controlled appropriately by simply charging it into a negative pressure chamber, etc.
Furthermore, the actuating spring, which interacts with the actuating rod and piston, also acts as a bias spring for the control spring, reducing or eliminating hysteresis, ensuring accurate and constant shape change at a constant temperature, and providing stable performance. be able to.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram of a shape memory alloy, and FIGS. 2 and 3 are longitudinal sectional views showing different embodiments of the present invention. 2... Valve body, 3... Valve closing spring, 4... Power valve, 7...
Piston, 8... Operating rod, 9... Operating spring, 10, 1
1...Control spring.

Claims (1)

[Claims] 1. A power valve for controlling power fuel, a piston having an operating rod that is operated by engine intake negative pressure to open and close the power valve, a valve closing spring acting on the valve body of the power valve, and the operating rod. In a carburetor power device comprising an actuation spring acting in the valve opening direction, a coiled control spring made of a shape memory alloy acts on the piston, and the control spring acts in the direction of the actuation. A power device characterized in that the length of the coil expands and contracts so that the opening degree of the power valve increases at low temperatures and decreases at high temperatures by controlling the operation of the operating rod by a spring.