JP3372664B2 - Idle opening adjustment mechanism for carburetor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle opening adjusting mechanism used in an idle opening control device for a car carburetor or the like.

[0002]

2. Description of the Related Art In a carburetor for an internal combustion engine, an idle opening control device that controls the idle opening of a throttle valve according to the temperature of the engine, and an idle opening adjustment that manually adjusts the fast idle opening with an adjusting screw. Mechanism is used.

FIG. 2 shows a main part of an idle opening control device equipped with such an idle opening adjusting mechanism.
Is a carburetor body, 2 is a throttle valve, 3 is a throttle shaft, 4 is a throttle arm fixed to the throttle shaft 3, 5 is a fast idle lever rotatably attached to the throttle shaft 3, and 6 is an adjusting screw. The lower neck portion of the fast idle lever 5 is screwed into a female screw formed in the bent portion 4a of the throttle arm 4 through a hole formed in the bent portion 5a. Reference numeral 7 denotes a spring as a compression coil spring, which is mounted between the throttle arm 4 and the fast idle lever 5 between the bent portions 4a and 5a.

By rotating the adjusting screw 6, the throttle arm 4 and the fast idle lever 5 are relatively rotated around the throttle shaft 3,
The throttle arm 4 to the spring 7 constitute the idle opening adjustment mechanism 8.

A fast idle cam 9 is rotatably mounted on the set screw 10, and the movable end 5b of the fast idle lever 5 is in contact with the cam surface 9a thereof. The fast idle cam 9 is constantly urged counterclockwise by the spring 11, and engages with a temperature-sensing portion (not shown) to determine the rotational position. This temperature sensing portion rotates the fast idle cam 9 according to the temperature of the cooling water of the engine.

The throttle valve 2 is always biased in a closing direction by a return spring (not shown), and the elastic force of the return spring causes the movable end 5b of the fast idle lever 5 to move to the cam surface 9a of the fast idle cam 9. It is pressed.

12 is a choke connecting lever,
The set screw 10 is rotatably mounted and is linked to the fast idle cam 9. 13 is a choke valve, 14 is a choke shaft, 15 is a choke lever whose one end is fixed to the choke shaft 14, 16
Is a choke link that connects the choke connecting lever 12 and the choke lever 15.

FIG. 3A is an enlarged view of the idle opening adjusting mechanism 8 shown in FIG. 4b is a female screw carved in the bent portion 4a of the throttle arm 4, 5c is the hole formed in the bent portion 5a of the fast idle lever 5, 6a is the head of the adjusting screw 6, and 6b is the adjusting screw 6. It is a male screw provided over the entire area under the neck.

The diameter of the hole 5c is the same as the male screw 6b of the adjusting screw 6.
Is slightly larger than the outer diameter of the male screw 6b, and the male screw 6b is screwed into the female screw 4b through the hole 5c. 3A is an axis of the throttle shaft 3 and a throttle arm 4
The fast idle lever 5 and the fast idle lever 5 rotate around this axis 3A, and by turning the adjusting screw 6, the relative angle between the two changes and the idle opening of the throttle valve 2 is adjusted.

Such an idle opening adjusting mechanism is also known in the automatic choke device of Japanese Utility Model Publication No. 1-30603. FIG. 4 shows another prior art known in Japanese Utility Model Laid-Open No. 4-27143, in which parts having the same functions as those in the prior art shown in FIGS. 2 and 3 are designated by the same reference numerals and unnecessary explanations are omitted.

In FIG. 4, reference numeral 4 is a throttle shaft 3.
With the throttle arm rotatably attached to the fast idle lever 5, a male screw under the neck of the adjusting screw 6 penetrates through a hole opened in the bent portion 4a of the throttle arm and is engraved in the bent portion 5a of the fast idle lever 5. It is screwed onto the screw.

Therefore, in the idle opening adjusting mechanism of the prior art shown in FIG. 4, in the case of the prior art of FIG. 3, the female screw for screwing the male screw into the hole for passing the male screw under the neck of the adjusting screw 6 is used. Although it is provided on a part different from the above, the adjustment of the idle opening by adjusting the relative angle between the throttle arm 4 and the fast idle lever 5 by rotating the adjusting screw 6 is the same.

A roller 5d is provided at the movable end of the fast idle lever 5, and is a cam surface 9 of the fast idle cam 9.
Contact a. Reference numeral 11A is a spring that biases the fast idle cam 9 clockwise around the set screw 10, and 17 is a pinion that meshes with a gear portion 9b of the fast idle cam 9, and a choke valve 13 is provided via a strangler spring (not shown). Are linked to.

Reference numeral 18 is a thermowax type temperature sensing section,
It is mounted in a cylindrical adapter 20 via an O-ring 19, and the rod 18a moves back and forth by sensing the temperature of engine cooling water passing through the adapter 20.

Reference numeral 21 is a round-shaped bimetal, which has a temperature sensing portion 18
It is mounted between the left end of the figure and the bottom surface of the adapter 20, and when the engine cooling water temperature becomes a certain temperature or higher, the state is inverted and deformed from the state shown in the figure, and the central protruding portion (the instep round portion) becomes the right side in the figure. The warm part 18 is moved to the right in the figure.

The tip (right side in the figure) of the rod 18a engages with the fast idle cam 9 via the screw 22, changes the angular position of the fast idle cam 9 according to the cooling water temperature of the engine, and opens the throttle valve 2 idle. Control the degree.

FIG. 5 shows still another conventional technique, which is shown in FIG.
It is known from Japanese Patent No. 147321. Also in this conventional technique, the portions having the same functions as those of the conventional technique shown in FIGS. 2, 3 and 4 are denoted by the same reference numerals, and unnecessary description will be omitted.

In FIG. 5, an idle cam 9A is rotatably attached to the set screw 10, and its cam surface is
A roller provided at the tip of the throttle arm 4 is in contact. A lever 23 is rotatably mounted on the set screw 10 and is rotatable relative to the idle cam 9A. The idle screw 9A is formed by the adjusting screw 6 and the spring 7.
The relative angle with is adjustable. That is, the adjusting screw 6, the spring 7, the idle cam 9A and the lever 23 constitute an idle opening adjusting mechanism 8 for adjusting the idle opening of the throttle valve 2.

A diaphragm device 24 is composed of a front diaphragm device 25 and a rear diaphragm device 26.
The tip of the operating rod 27 is connected to the movable end of the lever 23 of the idle opening degree adjusting mechanism 8 via a link 28.

The negative pressure and atmospheric pressure of the intake manifold 30 are supplied to the diaphragm chambers of the front diaphragm device 25 and the rear diaphragm device 26 via the spool type temperature switching valve 29 according to the engine cooling water temperature.

Reference numeral 31 is a thermowax cap as a temperature sensing portion of the spool type temperature switching valve 29, which is used for engine cooling water
Sensing a temperature of 2. Reference numeral 33 is a negative pressure port, 34 is an atmosphere connection filter, 35 is a negative pressure passage for guiding the negative pressure of the intake manifold 30 from the negative pressure port 33 to the spool type temperature switching valve 29, and 36 and 37 are from the spool type temperature switching valve 29. The pipes supply negative pressures corresponding to the cooling water temperature to the respective diaphragm chambers of the front diaphragm device 25 and the rear diaphragm device 26.

In the prior art of FIG. 5, the temperature switching valve 29
Selectively connects the two diaphragm chambers of the diaphragm device 24 to the negative pressure source and the atmosphere according to the temperature of the engine, thereby depending on the three states of cold start, warm operation, and warm-up. The idle cam 9A is displaced, and the throttle valve opens at an angle according to the three modes.

By the way, in the prior arts of FIGS. 2 and 3 and the prior art of FIG. 4, the idle opening adjusting mechanism 8 is interposed between the throttle shaft 3 and the fast idle cam 9. In the prior art shown in FIG. 5, the idle opening adjustment mechanism 8 is interposed between the link 28 and the lever 4.

However, in any of the conventional techniques, as shown in the typical prior art of FIGS. 2 and 3 (a), the axis 3
Of the first lever 4 and the second lever 5 which are independently rotatable around A, the male screw 6a of the adjusting screw 6 is screwed into the female screw 4b of one lever 4 and the adjusting screw 6 The lower part of the neck is inserted into the other lever 5 through a hole 5c, and a compression spring 7 is mounted between the levers 4 and 5.

In the prior art of FIG. 5, the set screw 10
The axis line of 3 corresponds to the axis line 3A, and the idle cam 9A and the lever 23 correspond to the first lever 4 and the second lever 5, respectively.

[0026]

SUMMARY OF THE INVENTION In the above conventional technique,
The male screw 6b of the adjusting screw 6 is formed over the entire length of the lower neck portion, and the diameter of the hole 5c formed in the bent portion 5a of the second lever 5 is such that the male screw 6b passes through.
It was slightly larger than the outer diameter of.

At the center position of the adjusting range of the adjusting screw 6, the bent portion 4a of the first lever 4 and the bent portion 5a of the second lever 5 are parallel to each other as shown in FIG. 3 (a). In such a state, a slight gap was present over the entire circumference between the outer circumference of the male screw 6b and the wall surface of the hole 5c.

Therefore, when the adjusting screw 6 is turned from the state shown in the drawing to adjust the levers 4 and 5, the levers 4 and 5 relatively rotate about the axis 3A, and the bent portions 4a and 5a are no longer parallel to each other. Incline. This inclination becomes larger as the degree of adjustment of the adjusting screw 6 from the state of FIG.

The adjustment of the idle opening of the throttle valve 2 by the adjusting screw 6 changes the necessary width due to variations in the dimensions of some parts related to the idle opening of the throttle valve, so that in mass production, As the inclination increases, the base portion of the male screw 6b of the adjusting screw 6 hits the wall surface of the hole 5c formed in the bent portion 5a of the second lever 5 and is twisted as shown in FIG. 3 (b). The inclination θ may increase.

In this way, the inclination θ becomes large and the hole 5c
If the base of the male screw 6b and the base of the male screw 6b are not concentric with each other and shift, the outer periphery of the base of the male screw 6b hits the wall surface of the hole 5c and is twisted, making it difficult to adjust and not being able to adjust to an optimum idle opening degree. There was a problem that there were cases.

For example, if the fast idle opening cannot be adjusted in the direction of increasing it, that is, in the direction of advancing the adjusting screw 6, the fast idle opening becomes smaller than the design value, and the fast idle rotation speed does not become high, and the engine is stopped in the worst case. There was a problem of doing.

On the contrary, if the adjusting screw 6 cannot be adjusted in the backward direction, the fast idle speed does not decrease and the fuel consumption deteriorates. In order to prevent interference between the outer periphery of the base portion of the male screw 6b and the hole 5c, the hole 5c is enlarged into an elliptical shape, and its major axis direction is substantially the vertical direction in FIGS. 3 (a) and 3 (b). Some have tried to avoid galling. In such a case, the left end of the spring 7 in the drawing may enter and bite into the major axis portion of the hole 5c, which leaves a problem that the idle opening degree cannot be adjusted smoothly.

Therefore, according to the present invention, the male screw 6b is prevented from interfering with the hole 5c and the spring from biting into the hole 5c even if a certain degree of inclination θ occurs, so that the adjusting screw 6 can be smoothly adjusted. Another object of the present invention is to provide an idle opening adjustment mechanism for a carburetor, which can solve the problems such as the inability to adjust.

[0034]

In order to achieve the above object, an idle opening adjusting mechanism of a carburetor according to claim 1 controls an idle opening of a throttle valve according to an engine temperature. An idle opening adjustment mechanism used in the device, comprising a first lever (4), a second lever (5), and a second lever (5) that are independently rotatable about an axis (3A). 5) An adjusting screw (6) having a male screw (6b) for screwing the lower neck portion through the hole (5c) into the female screw (4b) of the first lever (4), and both levers (6b). 4) With a spring (7) mounted between (5), a portion (6c) having a diameter smaller than the outer diameter of the male screw (6b) is provided at the base of the lower neck portion of the adjusting screw (6). It is characterized by

According to a second aspect of the invention, in the idle opening adjusting mechanism of the carburetor according to the first aspect, the diameter of the small diameter portion (6c) is set to be equal to or smaller than the root diameter of the male screw (6b). A third aspect of the present invention is the carburetor idle opening adjusting mechanism according to the first aspect, wherein the small diameter portion (6c) has a male screw (6b).
It is characterized in that it is almost the same as or slightly smaller than the valley diameter of.

Then, the fourth aspect is the first, second or third aspect.
The idle opening adjusting mechanism of the carburetor described above is characterized in that the axial length of the small-diameter portion (6c) is made larger than the axial length of the hole (5c).

[0037]

[Function] Even if the adjusting screw (6) is largely adjusted from the central position and the lower neck portion of the adjusting screw (6) is moved to a position offset to the hole (5c) of the second lever (5). Since there is a small-diameter portion (6c), there is no risk that the base portion under the neck will hit the wall surface of the hole (5c) and pry.

[0038]

FIG. 3 is a schematic diagram of the embodiment of FIGS. 1 (a) and 1 (b).
The parts corresponding to the parts of the prior art shown in FIGS.

Reference numerals 4 and 5 denote levers that are independently rotatable around the axis 3A, and the bent portion 4a of the first lever 4 is engraved with a female screw 4b so that the second lever 5 has A hole 5c is formed in the bent portion 5a concentrically with the female screw 4b.

The axis 3A is perpendicular to the plane of the drawing, and the bent portion 4
Also, a and 5a are formed at right angles to the paper surface. A small-diameter portion 6c is formed at the base of the under-neck portion of the adjusting screw 6, and a male screw 6b is formed at the remaining portion.

The diameter of the small-diameter portion 6c is smaller than the outer diameter of the male screw 6b and is substantially the same as the root diameter of the male screw 6b, and the small-diameter portion 6c is finished to have a smooth surface without traces of the male screw 6b. ing.

The diameter of the hole 5c formed in the bent portion 5a of the lever 5 is such that the male screw 6b can be easily penetrated.
It is slightly larger than the outer diameter of. When the adjusting screw 6 is at the center position, as shown in FIG.
a and 5a are parallel to each other, and the small-diameter portion 6 of the adjusting screw 6
c is in the center of the hole 5c.

The case where the adjusting screw 6 is largely retracted from this central position and both the bent portions 4a and 5a are inclined by an angle θ is shown in FIG. Since the small-diameter portion 6c is formed, the base portion of the under-neck portion of the adjusting screw 6 does not interfere with the wall surface of the hole 5c of the bent portion 5a of the lever 5, so that twisting between the two can be avoided.

The diameter of the small-diameter portion 6c is preferably less than or equal to the root diameter of the male screw 6b so that twisting does not occur and can be adjusted smoothly. Most preferably, the diameter is slightly smaller than the root diameter of the male screw 6b so that no trace of 6b remains.

The axial length of the small-diameter portion 6c is
The length of the hole 5c in the axial direction, that is, the thickness of the bent portion 5a may be made larger to surely prevent interference between the two.

[0046]

Since the idle opening adjusting mechanism of the carburetor of the present invention is constructed as described above, a small-diameter portion (6c) which is provided at the base of the neck portion of the adjusting screw and is not machined with a male screw.
Prevents interference with the hole (5c) of the second lever (5),
Eliminates twisting between the two. Also springs (7)
Does not cut into. Therefore, the throttle valve opening adjustment range that can be smoothly adjusted can be expanded, and assembly defects can be reduced.

This, combined with the fact that the adjusting screw itself can be adjusted smoothly, not only contributes to cost reduction by shortening the adjustment time of the carburetor, but also prevents engine stall due to improper idle adjustment and prevents Fuel efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a partially longitudinal front view showing a main part of an embodiment of the present invention, (a) shows a state in which an adjusting screw is in a central position, (b) shows
FIG. 6 is a view showing a state in which the adjusting screw is retracted from the state shown in FIG.

FIG. 2 is a front view of a conventional idle opening control device.

FIG. 3 is a partially enlarged vertical front view showing an enlarged main part of the prior art shown in FIG. 2, in which (a) shows a state in which an adjusting screw is at a central position,
(B) is a figure which shows the state which retracted the adjustment screw from the state of the same figure (a).

FIG. 4 is a front view of another conventional idle opening control device.

FIG. 5 is a front view of still another conventional idle control device.

[Explanation of symbols]

3A axis 4 first lever 4b female screw 5 Second lever 5c hole 6 adjustment screws 6b male screw 6c Small diameter part 8 Idle opening adjustment mechanism

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Claims (4)

(57) [Claims] 1. An idle opening adjusting mechanism used in an idle opening control device for controlling an idle opening of a throttle valve according to an engine temperature, wherein the idle opening adjusting mechanism is capable of independently rotating around an axis. A lever, a second lever, an adjusting screw having a male screw for screwing an under-neck portion through a hole made in the second lever into a female screw of the first lever, and the adjusting screw mounted between both levers. A carburetor idle opening adjustment mechanism characterized by comprising a portion having a diameter smaller than the outer diameter of the male screw at the base of the neck portion of the adjusting screw. 2. The idle opening adjusting mechanism for a carburetor according to claim 1, wherein the diameter of the small-diameter portion is equal to or smaller than the root diameter of the male screw. 3. The idle opening adjusting mechanism for a carburetor according to claim 1, wherein the diameter of the small diameter portion is set to be substantially the same as or slightly smaller than the root diameter of the male screw. 4. The idle opening adjusting mechanism for a carburetor according to claim 1, 2 or 3, wherein the axial length of the small-diameter portion is larger than the axial length of the hole.