JPS6023495Y2 - Air fuel ratio control device - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an air-fuel ratio control device for a carburetor.

Conventional variable venturi carburetors employ automatic choke devices to facilitate starting in cold weather, and control the air-fuel ratio (A/F) according to warm conditions.

Japanese Unexamined Patent Publication No. 50-26915 discloses a method for this purpose, such as an automatic choke device that operates a spirally wound bimetal with electrical energy to obtain the amount of bypass air according to the warm temperature, and a method that uses wax to generate a bypass air amount according to the warm temperature. An automatic choke device is used that moves the fuel nozzle up and down to adjust the amount of fuel.

The former has a complicated structure and cannot be made smaller, while the latter has structural problems because the fuel pipe moves with the nozzle.

In view of the above, the purpose of this invention is to provide a cold air-fuel ratio control device for a carburetor that eliminates the drawbacks of automatic choke devices, increases the degree of freedom in adaptation, is highly reliable, and is easy to adjust. .

That is, the sliding rod 15 has a tapered portion and is disposed in the air passage of the air bleed and acts as a control valve.
is inserted into the body 1, a temperature sensing element 2, a heating element 5 and an electrode 7 are placed at the rear of the rod and received by a holder 8, and a compression spring 6 is provided between the temperature sensing element 2 and the body 1. The holder 8 is movable back and forth by the adjuster 3 screwed onto the body 1, and the central part of the lever 16, whose one end is rotatably attached to the body 1, is pressed against the spherical end of the sliding rod 15 protruding from the body 1. , is a carburetor air-fuel ratio control device for cold start, characterized in that the other end of the lever 16 is connected to a fast idle cam 13 via a link 14.

Next, the embodiment shown in FIG. 1 will be described.

In the figure, the variable venturi section is omitted.

A sliding rod 15 is inserted into the body 1 so as to be freely movable in the axial direction, a temperature sensing element 2 is placed at the rear of the rod, a heat mass 4, a heating element 5, and an electrode 7 are placed in this order and are received by a holder 8. .

Further, a spring 6 is attached in a compressed state to ensure tight contact with the temperature sensing element 2, heat mass 4, heating element 5, and electrode 7.

When the temperature of the heating element 5 increases, the wax inside the temperature sensing element 2 expands and the piston is pushed out to the right.

Here, the end of the piston rests against the end of the sliding rod, so that the two move as one.

The adjuster 3 is used to adjust the timing at which air escapes from the air inlet to the air outlet. It is screwed into the body 1, and when rotated, it moves back and forth, moving the temperature sensing element 2 and sliding rod 15 back and forth. (horizontal direction in the figure).

One end of a lever 16 is rotatably attached to a stay attached to the body 1, and the center portion of the lever 16 is brought into contact with the spherical end portion of the sliding rod 15.

In addition, the shape of the tapered part 15' of the sliding rod corresponds to the required bleed air amount (A/F) of the engine! , : has an arbitrary tapered shape, although it is different from the above, and the narrow diameter portion 15'' has a passage diameter that does not create resistance when air flows from the air inlet to the air outlet port.

The fast idle cam 13 is rotatably attached to the screw 9.

The link 14 is connected at one end to the fast idle cam 13 and at the other end to the lever 16, and this link mechanism is connected to the lever 16.
is biased by an appropriate spring so as to come into contact with the right end of the sliding rod 15.

The fast idle lever 10 is fastened to a slotted shaft 18 with a nut 17.

Further, the slot valve 12 is fastened and fixed to the throttle shaft by a screw (not shown).

Further, the bent end portion of the fast idle lever 10 is positioned so as to come into contact with the cam surface of the fast idle cam 13.

Note that a so-called choke valve mechanism is not provided because it is unnecessary.

An electric wire is attached to the end of the electrode 7, making it a positive electrode.

Further, the negative electrode is grounded via a spring 6.

By energizing it, the heating element 5 generates heat, and the heat is transferred to the heat mass 4 and the temperature sensing element 2 in order by heat conduction, and the piston 2' inserted at the end of the temperature sensing element 2 moves forward (to the right in the figure). As a result, the sliding rod 1
5 also moves forward.

As a result, the air entering from the air inlet is metered by the air outlet hole and the tapered portion 15' of the sliding rod 15, and is sucked into the bleed input portion (not shown) through the air outlet port.

It also has a mechanism that operates the fast idle cam in conjunction with the movement of the sliding rod.

As a result of this movement, the lever 16 is pushed in the direction of arrow A by the spherical surface at the tip of the sliding rod, and the fast idle cam 13 is accordingly rotated in the direction of arrow B.

Therefore, the fast idle lever 10 rotates in the direction of arrow C, and the throttle valve 12 finally reaches the idling state.

In the embodiment shown in FIG. 1 described above, the bleed is measured by a control valve composed of an air outlet hole and a tapered part 15' of the sliding rod 15, but when sealing performance and flexibility of adaptation are especially required, a control valve is used. A structure as shown in FIG. 2 can be adopted.

In the embodiment shown in FIG. 2, a sliding rod 15 having almost the same shape as the sliding rod used in FIG.
A valve mechanism consisting of a needle valve 20, a bushing pin 22, a back spring 19, and a relief spring 21 is placed above A.

In cold weather, needle pulp 2 is used as shown in the drawing.
0 and the seat portion 23 are in close contact with each other, and air does not flow therethrough.

Moreover, the sliding rod moves forward (
When the tapered portion 15' moves forward (to the right in the drawing), the needle pulp 20 also moves downward due to the force of the back spring 19. As a result, the sheet portion 23 and the needle pulp 20 move downward. Weigh the air by the annular area of .

The purpose of use of the relief spring 21 is to enable movement of the bushing bin 22 after the needle pulp 20 reaches the seat portion 23.

The shape of the fast idle cam is not a stepless cam as in the embodiment, but a stepped cam may be adopted.

According to this idea, it is possible to control the amount of air in the air bleed as the engine warms up, making it possible to downsize the carburetor that supplies a mixture with an optimal air-fuel ratio, and thus reducing its cost. .

In addition, the automatic choke mechanism using a spiral bimetal has a simple structure and improved reliability.

Furthermore, since the operating timing of the sliding recess can be finely adjusted and the fast idle cam is interlocked with the movement using fewer parts, there is an advantage that the degree of freedom of adaptation is improved and it can be used in all carburetors.

[Brief explanation of the drawing]

1 and 2 are sectional views of main parts of different embodiments of this invention. A...Inlet of air passage, mouth...Air outlet, 1...Body, 2...Temperature sensing element, 3
...Adjuster, 5...Heating element, 6.
...Compression spring, 7...Electrode, 8.
...Holder, 13...Fast idle cam, 14...Link, 15.15A...
...Sliding rod that constitutes the control valve, 16...
...Lever, 20 ...Needle valve, 2
1... Relief spring, 22...
Bushpin, 23... Seat part.

Claims (1)

[Scope of utility model registration request] A sliding rod 15, which has a tapered part and is placed in the air passage of the air bleed and acts as a control valve, is attached to the tenon 1.
The temperature sensing element 2, the heating element 5, and the electrode 7 are placed at the rear of the rod and are supported by a holder 8, and a compression spring 6 is inserted into the rod.
is provided between the temperature sensing element 2 and the body 1, and the holder 8 can be moved back and forth with an adjuster 3 screwed onto the body 1, and the central part of the lever 16 is rotatably attached to the body 1 with one end An air-fuel ratio control device characterized in that the lever 16 is pressed against a spherical end portion of the sliding rod 15 protruding from the body 1, and the other end of the lever 16 is connected to a fast idle cam 13 via a link 14.