JPS59105946A - Choke mechanism for carburetor - Google Patents

Abstract

PURPOSE:To operate a choke valve smoothly, by employing such an arrangement that the line of action of choke actuating force transmitted from a temperature-sensitive member to a choke lever supported in a freely rotatable manner on a choke shaft and that line of choke-motion actuating force exerted by the negative pressure in an intake pipe via a diaphragm are located on the same side of the choke shaft. CONSTITUTION:A complete-explosion lever 5' is formed with a driven arm 5b' to which a connecting rod 12 is connected, in the manner that the driven arm 5b' is integral with the lever 5'. A driven arm 4c is projected from a choke lever 4' and opposed to a driven and driving arm 5b'. The arrangement is such that the line of action of the force transmitted from a temperature-sensitive member to the choke lever 4', shown by an arrow PT in the drawing, and that of the force exerted by the negative pressure in an intake pipe via a diaphragm, shown by an arrow PS, are located on the same side of a choke shaft 3. As to the balance of force in the direction of parallel shifting, the choke shaft 3 supports a force corresponding to the difference of the two forces PS and PT. By employing such an arrangement, it is enabled to reduce the pressure acted on the contact surface of the choke shaft 3 and the lever 5' and the frictional force preventing smooth rotation extremely. Therefore, movement of the choke shaft 3 supporting a choke valve 2 and its relevant members can be made smooth.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a choke mechanism for a carburetor for an internal combustion engine, and particularly to a choke mechanism that is improved so as to operate smoothly at low temperatures.

[Prior art]

Fig. 1 is a vertical sectional view of a carburetor having a choke mechanism equipped with a two-stage complete explosion piston means, in which 1 is a carburetor supply air cylinder, 2 is a choke valve, and 3 is a structure in which the above-mentioned choke pulp is fixed and rotated. It is a freely supported choke shaft. A choke lever 4 is mounted on the choke shaft 3, and the choke valve 2 is opened and closed via the choke lever 4.

This type of choke mechanism has a temperature-sensitive operating mechanism that closes the choke valve when the temperature is low and opens the choke valve when the temperature is high.
In addition, it is equipped with a pressure-sensitive operating mechanism that automatically opens and closes in response to the negative pressure in the intake pipe, and has the function of automatically controlling the opening and closing of the choke pulp when the temperature is low to easily achieve complete explosion.

Section A shown in the figure is the above-mentioned temperature-sensitive operating mechanism, and section B is the pressure-sensitive 11-tri-motor 4M9 located on the upper 11 sides.

1) In the choke bar 4 described in II, an arm 4b for receiving force from the pressure-sensitive actuation mechanism A and an arm 4a for receiving force from the pressure-sensitive actuation mechanism B are formed in an 11.1ζ shape. has been done.

The above-mentioned arm 4b is attached to a temperature-sensitive member 13 such as a bimetal, and receives a force in the choke pulp valve closing direction as shown by arrow C when the temperature is low.

The complete explosion lever 5 is connected to the connecting rod 12. Connect L! ! III 1
o, second piston spring 11. It is connected to the diaphragm 8 via a spring cylindrical second piston 9, receives a force in the direction of the arrow by the negative pressure 14 in the intake pipe, and pushes the arm 4a via the transmission arm 5a, A force is applied to the choke pulp 2 in the direction of valve opening as shown by arrow E. 6 is a redundant piston, and 7 is a spring for balancing the intake negative pressure 14.

The complete explosion lever 5 is rotatably supported on the choke shaft 3, and is connected to a transmission arm 5a and a driven arm 5.
b are integrally formed. The driven arm 5b is pivoted to the connecting rod 12, and the transmission arm 5a faces the arm 4a of the choke lever 4.

The operation of the choke mechanism provided with the complete explosion piston means as described above will now be described with reference to FIG.

The vertical axis indicates the degree of opening of the chalk pulp. θ1 is a choke pulp opening degree suitable for starting the engine at low temperatures and starting warm-up operation. θ3 is the opening degree when the choke pulp is fully opened after the warm-up operation is completed.

Now, in a state where pressure-sensitive actuation mechanism B does not act, at the time of starting, the choke valve opening degree is θI due to the action of temperature-sensitive actuation mechanism A.
Since the engine is at K, it can be started easily and the engine can be warmed up. As the warm-up progresses, the choke pulp gradually opens to 03, allowing load operation.

However, there are cases where the intake pipe negative pressure becomes large and the pressure-sensitive actuation mechanism A is activated while the warm-up is not completed.

For example, this may occur if the accelerator pedal is depressed to promote warm-up and the negative pressure in the intake pipe increases.

In FIG. 2, the solid curve a-t)-C shows an example of normal startup and warm-up operation.

T1 is the richness of the sensitive material at the time of starting. From this T1 temperature to T3 temperature, the choke pulp circuit layer is θ
It is kept at 1.

θ2 is the pulp opening 1w when the spiral spring-shaped sensitive material member 13 is pushed open by the operating force of the one-magnet operating mechanism B and the chalk pulp 2 is opened.

Starts at point a (+a degree T I ) and starts at point b (temperature T3)
If you warm up without depressing the accelerator until the temperature reaches T
Between 1 and 4, the temperature sensing member 13 changes from a cold state to a hot state, the operating force of the temperature sensing actuation mechanism A decreases, and the choke pulp opens by θ2 to reach the 0 point. Thereafter, at the normal operating temperature T5, the choke pulp becomes fully open θ3 and becomes the rated operating state d.

However, after starting at point a, if you step on the accelerator at point e at temperature T2 without waiting for the slow warm-up to the severity level T3, the pressure-sensitive actuation mechanism B acts and chokes as shown by the broken line. As in the above case, the pulp opening degree θ2 immediately passes through point f and reaches point C.
leading to.

However, if the accelerator is released, for example near point g, before the above point C (temperature T4) is reached, the choke pulp opening degree θ1 will be returned to the closing direction as shown by the virtual line arrow, and the above-mentioned Matching the solid line curve, the change at that time is 1.
The operating condition must be suitable for rt.

However, when the choke pulp is supposed to close the valve as shown by the imaginary arrow above, if any of the components of the choke mechanism is pulled and prevents the valve from closing, the choke continues even after the accelerator pedal is released. Since the pulp is left open at θ2 and warm-up is not completed, the intake atomization of gasoline becomes unsatisfactory, leading to engine stall. Such a problem may occur in the shaded area shown in FIG.

In conventional choke mechanisms, when the accelerator is depressed and released during warm-up, the engine often stalls due to the above-mentioned tension of the choke pulp.

The cause of the above-mentioned sluggish valve closing operation of the choke pulp will be described below with reference to FIGS. 3 and 4.

FIG. 3 is a cross-sectional view of the vicinity of the choke shaft 3 shown in FIG. 1 taken along a plane including the τ extraction. FIG. 4 is a partial sectional view of the complete explosion lever 5 shown in FIG. 1 and its related members.

As shown in FIG. 3, the choke lever 4 is connected to the choke shaft 3.
is fixed to. This choke lever 4 has two arms 4a and 4b integrally molded therein. Arm 4 above
The temperature sensing member 13 is attached to the arm 4a, and the arm 4a faces the transmission arm 5a of the complete explosion lever 5.

The above-mentioned complete explosion lever 5 is connected to the choke shaft 3 via the bearing portion 5c.
This complete explosion lever 5, which is rotatably supported by , rotates in a plane perpendicular to the choke shaft 3, but if the above-mentioned force outside the rotation plane acts on the complete explosion lever 5, , as shown in the figure, the bearing part 5C of the complete explosion lever 5 is connected to the choke shaft 3.
The tilting force moves against the object, and strongly hits locally at the two points (r and s) shown in the figure, preventing free rotation.

As mentioned above, the reason why the force that makes the bearing part 5c move against the choke shaft 3 is generated is because the transmission arm 5a is bent with respect to the main body of the complete explosion lever 5. This is because the contact point F with the arm 4a is located outside the rotation plane of the complete explosion lever 5.

Moreover, as shown in FIG. 4, a force is applied to the complete explosion lever 5 in the form of a balance, so that a large contact force is exerted between the complete explosion lever 5 and the choke shaft 3. That is, the arrow PR in this figure indicates the force that the driven arm 5b of the complete explosion lever 5 receives from the connecting rod 12;
Arrow Pt is a reaction force that the transmission arm 5a of the complete explosion lever 5 receives from the arm 4a of the choke lever 4 (only the arm portion is shown). Regarding the balance of forces in the rotation direction, arrow Ps
The clockwise moment caused by the O force and the counterclockwise moment caused by the arrow PT are in a balanced relationship with the choke shaft 3 as the fulcrum. Looking at the balance of forces in the parallel movement direction, the force supported by the choke shaft 3 as a fulcrum is P s 1 P
Ding and Nasi are extremely powerful. For this reason, the frictional force near the fulcrum increases and free rotation is hindered.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems 7 and 11, and an object of the present invention is to provide a choke mechanism that significantly reduces the force that hinders the rotation of the choke pulp and that operates smoothly without causing any tension on the choke pulp. With the goal.

[Summary of the Invention] In order to achieve the above object, the present invention provides a choke mechanism for a carburetor of an internal combustion engine, in which an opening/closing operation is transmitted from a temperature-sensitive member to a choke lever rotatably supported by a choke shaft. It is characterized in that the line of action of the power and the line of action of the opening/closing force applied by the negative pressure in the intake pipe via the diaphragm are arranged on the same side with respect to the choke shaft.

[Embodiments of the invention]

Next, an embodiment of the present invention will be described with reference to FIGS. 5 and 6. FIG. 5 is a diagram corresponding to FIG. 4 of the conventional device, and the choke shaft 3. Connecting rod 12. The temperature sensing member 13 is the same component as in the conventional device.

4' is a choke lever in this embodiment, and <-15/ is a complete explosion lever in this embodiment. Figure 6 shows the choke lever 4' and the choke lever (-5')
FIG. 3 is a cross-sectional view taken along a plane including the axis of l13.

The '7' explosive lever 5' of this embodiment has a driven arm 5b' that connects the connecting rod 12 integrally formed with the following features:1. This driven arm 5b' is also used as a transmission arm.

That is, the driven arm 4C is made to protrude from the choke lever 4' and is opposed to the above-mentioned driven/transmission arm s b /.

As a result, as shown in FIG. 5, the line of action of the force Pg that the complete explosion arm 5' receives from the connecting rod 12 and the line of action of the reaction force PT that the explosion arm 5' receives from the choke lever 4' are different with respect to the choke shaft 3, which is the fulcrum. located on the same side. In this embodiment, as described above, the line of action of the force transmitted from the temperature sensing member to the choke lever 4' (arrow 1"T) and the line of action of the force applied by the negative pressure in the intake pipe via the diaphragm (arrow) P
8 and are arranged on the same side with respect to the choke 1lQtl3.

As described above, the choke shaft 3 supports a force corresponding to the difference between the two operating forces Ps and PT in terms of force balance in the parallel force direction in this example.
The pressure acting on the contact surface between the choke shaft 3 and the complete explosion lever 5' is much smaller than that in the conventional device (FIG. 4). Therefore, the force that prevents free rotation is extremely small, and the choke shaft 3 that supports the choke valve 2 and its related members operate extremely smoothly.

Moreover, in this embodiment, as shown in FIG. 6, the contact point F' between the choke lever 4' and the complete explosion lever 5' is located at the rotational surface of the complete explosion lever 5'. No force acts on the complete explosion lever 5' to bias its attitude.

Therefore, the bearing part 5C of the complete explosion lever 5' is connected to the choke shaft 3.
There is no risk of anger arising from anger. As in this example, the contact point F' between the choke lever 4' and the lever member (complete exposure lever 5' in this example) that transmits the rotational operating force to the intake pipe negative pressure with respect to the choke lever 4' is ,
When the rotation of the complete explosion lever 5' is set to be improved, the rotation of the complete explosion lever 5' becomes smoother.

Furthermore, as in this example, if the lines of action of both operating forces Ps and PT are arranged in a plane perpendicular to the choke shaft 3, the choke lever 4' and the complete explosion lever 5' can be moved relative to the choke shaft 3. No force in the tilting direction is applied (For details, refer to choke shaft 3.
The choke mechanism operates smoothly without any force acting to bias its vertical position. Furthermore, the line of action Ps of both operating forces.

The closer the Pts are to each other, the smaller the force applied to the choke shaft 3 and the smoother the operation.

〔Effect of the invention〕

As described above in detail, the present invention provides a choke mechanism for a carburetor of an internal combustion engine, in which the line of action of an opening/closing operating force transmitted from a temperature-sensitive member to a choke lever rotatably supported on a choke shaft is provided. By arranging the line of action of the opening/closing force applied by the negative pressure in the intake pipe via the diaphragm on the same side with respect to the choke shaft, the force that obstructs the choke can be significantly reduced. Accordingly, it is possible to construct a choke mechanism for a carburetor that operates smoothly without causing the choke valve to be pulled.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of a conventional carburetor having a choke mechanism equipped with a complete detonation piston means, Fig. 2 is a diagram showing the operation of the above choke mechanism, and Fig. 3 is a cross section of the above choke operating mechanism. FIG. 4 is a partial cross-sectional view of the choke mechanism and snow-related components of the choke mechanism. 5 and 6 show an embodiment of the choke mechanism of the carburetor of the present invention, and FIG.
FIG. 6 is a sectional view corresponding to FIG. 3 of the conventional device. 3...Choke shaft, 4.4'...Choke renoku-
, 4a, 411... Arm, 4C... Driven arm, 5゜5'... Complete explosion lever, 5a... Transmission arm, 5b... Driven arm, s b /... Transmission and driven Arno 1.5C...Bearing part, 8...Diaphragm, 9...Second piston 12...Connecting rod, 13...Temperature sensing member, A...Temperature sensing operation Groove, B...pressure-sensitive actuation mechanism. Agent Patent Attorney Masami Akimoto Figure 3 Illness Figure 5 Figure 4' Figure tJ-Figure 6

Claims (1)

[Claims] 1. In the choke mechanism of the carburetor of an internal combustion engine, what is the sensitivity to the square yoke lever rotatably supported by the choke shaft? A carburetor characterized in that the line of action of the opening/closing force transmitted from the crystal member and the line of action of the opening/closing force applied by negative pressure in the intake pipe via the diaphragm are arranged on the same side with respect to the choke shaft. choke mechanism. 2. The lines of action of both of the opening/closing forces are arranged in a plane perpendicular to the choke axis, and the lines of action of both forces are arranged close to each other. The carburetor choke mechanism according to item 1. 3. Place the point of contact between the choke lever and the V-bar member that transmits the operating force due to the negative pressure in the intake pipe to the choke lever on the rotating surface of a portion of the lever for transmitting the operating force. A choke mechanism for a carburetor according to claim 1 or 2, characterized in that: