JPS5828418B2 - Jidouchiyokuchiyokuchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic choke device having a choke valve attached to the air inlet of a carburetor and a bimetallic spring that deforms depending on the temperature of the internal combustion engine to operate the choke valve.

In internal combustion engines, the vaporization of fuel is poor in cold weather, so
By increasing the proportion of fuel in the air-fuel mixture, it is necessary to increase the rotational speed of the internal combustion engine and promote warm-up.

For this reason, there is a conventional automatic choke device that adjusts a choke valve and a throttle valve using atmospheric temperature, exhaust gas temperature, cooling water temperature, etc. as control factors.

Among conventional automatic choke devices, for example, an automatic choke device having a bimetal spring and a choke valve attached to an eccentric shaft is explained. One end of the bimetal spring is fixed at a predetermined position of the carburetor, and the other end is , fixed to the choke lever attached to the eccentric shaft of the choke valve.

Therefore, when the internal combustion engine is cold, the bimetallic spring contracts and the choke valve closes, but as the engine warms up, the bimetallic spring stretches and opens the choke valve.

Further, since the choke valve is attached to an eccentric shaft, as the rotational speed of the internal combustion engine increases, increased air pressure is applied to the upstream surface of the choke valve, so that the choke valve opens further.

In response to this movement of the choke valve, the opening degree of the throttle valve is changed to be slightly larger than the opening degree during idling.

In general, the main purpose of a choke valve is to reduce the amount of air taken in and temporarily create a rich mixture when the internal combustion engine starts in low humidity. If this occurs, this valve must be fully opened immediately.

For this reason, as the temperature of the internal combustion engine increases, it is desirable for the choke valve to open slowly at first and then gradually open faster.

An object of the present invention is to automatically supply an appropriate air-fuel mixture from the low-humidity start of the internal combustion engine until it warms up, thereby reducing the content of HC and CO in the exhaust gas.

According to the present invention, in an automatic choke device having a choke valve attached to an air inlet of a carburetor and a bimetal spring that deforms depending on the temperature of an internal combustion engine to operate the choke valve, the automatic choke device is fixed to an automatic choke valve shaft. A long groove is formed in the choke lever, and a bimetallic spring whose one end is fixed to the carburetor has a pin at the other end, and this pin is slidably fitted into the long groove of the choke lever.

The invention will be described with reference to an embodiment shown in the drawings. FIG. 1 shows an automatic choke device according to the invention, and FIG.
The figure is a sectional view of the main parts of this device.

A choke valve 2 is attached to the air inlet of the carburetor 1, and a throttle valve 10 is attached at a predetermined position downstream of the choke valve 2.

A choke valve shaft 3 is eccentrically attached to the choke valve 2, and a choke lever 4 is attached to the choke valve shaft 3.

The choke lever 4 is provided with a linear long groove 5 from the choke valve shaft 3 side to near one tip of the choke lever 4.

On the other hand, a case 1 including a spiral bimetallic spring 7 wound clockwise from the inside to the outside at a predetermined position of the carburetor 1
2 is provided, and the bimetal spring 7 has one end, which is the center thereof, fixed to the case 12.

The other end of the bimetal spring 7 is connected to a pin 6 slidably fitted into a long groove 5 provided in the choke lever 4.

Inside the bimetal case 12, a heating wire 13 is provided on the side of the bimetal spring I, and one end of the heating wire 13 is connected to a battery 16 via a power supply control device 15 composed of a key switch, a relay, etc.

The other end of the heating wire 13 is connected to the bimetallic case 12 itself at ground potential or to another grounding plate via a PTC element (a semiconductor element such as barium titanate whose resistance value increases more rapidly above a certain temperature) 14. connected above.

Rods 8a, 8b, and 8c are connected and attached to the other end of the choke lever 4, and the other end of the rod 8c is connected to the fast idle cam 9.

The fast idle cam 9 is in contact with the tip of the throttle valve lever 11.

Next, the operation of this device will be explained.

When the internal combustion engine is started at a low temperature, the heating wire 13 is not energized yet, so the bimetal spring 7 is contracted.
The pin 6 is located closest to the choke valve shaft 3 in the long groove 5 of the choke valve lever 4, and the choke valve 2 is closed.

Therefore, the choke lever 4 is in position a in FIG. 1. After the internal combustion engine is started, the heating wire 13 is energized by the power supply control device 15, and the temperature inside the bimetal case 12 rises.
The bimetal spring 7 is stretched, and the pin 6 is placed on the circumference of a radius A, with one end of the bimetal spring 7 attached to the case 12 as the center, and the distance from this center to the other end of the bimetal spring 7 being A. Move clockwise to close choke valve 2.
The pin 6 slides in the long groove 5 from the choke valve shaft 3 side to the tip side of the lever 4, and a force is applied to rotate the choke lever 4 clockwise.
If the distance between the choke lever 4 and the center of rotation is B, then B gradually becomes smaller and A/B becomes larger.

Therefore, the choke valve 2 is activated slowly at first and then
The choke valve 2 opens slowly at first and then gradually opens faster.

In addition, since the choke valve 2 is attached to the eccentric choke valve shaft 3, as the internal combustion engine warms up and the rotational speed of the internal combustion engine increases, the pressure of the intake air also increases, and the choke valve 2 opens further and reaches full open. .

In other words, the choke lever is in position b in Figure 1.

If the temperature inside the bimetal case 12 becomes too high, P
Since the resistance value of the TC element 14 suddenly increases and acts as a kind of switch, the temperature inside the bimetal case is kept constant.

The relationship between the deflection angle X of the bimetal spring and the choke valve opening Y according to this device is shown by the solid line in FIG.

The dotted line indicates the conventional one.

Thus, according to the invention, at the cold start of the internal combustion engine, the choke valve is in the closed state, and as the temperature rises, it is opened slowly at first and then faster to automatically adjust the proper It is possible to supply an amount of air, improve the performance of the internal combustion engine at low temperatures, and further reduce the HC and CO contents in the exhaust gas.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an automatic choke device according to the present invention, FIG.
The figure is a sectional view of the bimetal spring and the choke lever connection part, and FIG. 3 shows the relationship between the bimetal spring deflection angle and the choke valve opening degree. 1...Carburizer, 2...Choke valve, 4
...Choke lever, 5...Long groove, 6
...Pin, 7...Bimetal spring, 1
0... Throttle valve, 12... Bimetal case 13... Heating wire, 14... PT
C element, 16...Battery.

Claims (1)

[Claims] 1. In an automatic choke device having a choke valve attached to the air inlet of a carburetor and a bimetal spring that deforms depending on the temperature of the internal combustion engine to operate the choke valve, a choke lever fixed to the automatic choke valve shaft. An automatic choke device characterized in that a long groove is formed in the choke lever, a bimetal spring having one end fixed to the carburetor has a pin at the other end, and this pin is slidably fitted into the long groove of the choke lever.