JPS6037299B2 - Automatic choke device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic choke device configured to obtain an optimal air-fuel mixture at the time of engine startup and during the flight.

Conventional automatic choke devices in vehicle engines are of a type in which the choke valve's closing force changes proportionally to the rise in engine temperature, so the air-fuel ratio of the intake air-fuel mixture changes with each engine temperature and rotation speed. The air-fuel ratio cannot be maintained within the desired range, especially when the engine is started and warmed up, resulting in problems such as poor starting, unstable rotation, smoldering 9E gas, and the generation of harmful gases. Accompanied by L.

The present invention has been made in order to eliminate the drawbacks of the above-mentioned conventional systems, and it automatically adjusts the spring constant of the strangler spring provided in the choke drive system according to the engine temperature from the cold state of the engine to the period when the engine is running. To provide an automatic choke device which optimizes the effect of the choke and the combustion state of an engine by keeping the closing force of a choke valve within a desired range.

Hereinafter, the present invention will be explained based on embodiments shown in the drawings. As shown in FIGS. 1 and 2, the double-elbow type choke lever 2 in the choke drive system 1 has an actuating rod of a wax element 4 as a temperature sensor at the elbow on the fast idle cam 3 side. A pinion gear 7 of a rotating body 6 is engaged with a fan-shaped rack gear 5 provided on the opposite elbow.

The rotating body 6 is further connected via a strangler spring 8 to a choke shaft 9 for rotation thereof. 10 is a choke valve.

Here, the thermal expansion of the wax element 4 causes the choke lever 2 to rotate clockwise in the drawing, and via the rack gear 5 and pinion gear 7, rotates the rotating body 6 counterclockwise.
The case of heat shrinkage of the wax element 4 is the opposite of the above. Now, as shown in FIGS. 3 and 4, the strangler spring 8 in the first embodiment has a spring constant K.
Coil springs 11 and 12 having ^ and KB respectively and wound in the same direction are connected in series by a stopper 13 with a clip, so that the spring 11
The other end is loosely fitted with iron into an annular groove provided in the rotating body 6, and its tip is fixed to the rotating body 6, and the spring 1
The end of the pond 2 is latched onto the choke arm 14 of the choke shaft 9.

On the spring mounting side of the rotating body 6, there is a central protrusion 15 that passes through the springs 11 and 12 and guides the springs.
and a pinion arm 16 that extends on the outer peripheral side of the spring and can be rotatably engaged with the stopper 13. When the engine is cold, the rotating body 6 is in the position where its pinion arm 16 rotates while pressing the stopper 13 clockwise, and only the urging force applied to the spring 12 applies a closing force to the choke shaft 9. ing. It has already been mentioned that an increase in engine temperature causes the rotating body 6 to rotate counterclockwise, but the bias of the spring is set so that the pinion arm 16 begins to leave the stopper 13 when the temperature reaches the set temperature. The above-mentioned closing force from the cold state to the set temperature is based on the bias of the spring 12 alone.In other words, the spring 12 having the bending constant KB
This is due to single labor. As the temperature increases from the set temperature to room temperature, the pinion arm 16 and the stopper 13 are further separated, and the bias remaining in the series connection between the springs 12 and 11 is responsible for the closing force applied to the choke shaft. In other words, it is due to the cooperation of the springs 11 and 12, and its imitation constant is the same.
Here, KB> is constitutional. FIG. 4A shows an example of a strangler spring having a circle-shaped stopper 3 formed by the spring itself in the center of a series of springs 11 having a spring constant K^. The spring constant during operation is K Seira:
It is also the 'ground constant' during ruts.

In describing the effects of the first embodiment, an engine temperature vs. choke valve shutoff force diagram (hereinafter simply referred to as a shutoff force diagram) will be explained.

Starting from a cold engine before cranking,
When the engine temperature changes from normal temperature (approximately 20 qo) to Fujiki completion temperature (approximately 400 qo C) due to warm-up, the engine requires an intake air-fuel mixture with an air-fuel ratio corresponding to that temperature. Of course, this air-fuel ratio has a range between an upper limit and a lower limit, and the cut-off force that must be applied to one choke valve to obtain this air-fuel ratio differs depending on the engine type. Shown in the figure. In this cutoff force diagram, the curve formed by lines U, U2 represents the upper limit cutoff force line, and line L' represents the lower limit cutoff force line, so the range between these upper and lower limit cutoff force lines is It is only necessary to design the choke valve of the engine so that the shut-off force is set accordingly. However, the strangler spring used in the conventional choke drive system has only one spring and its spring constant is constant, so the shutoff force against engine temperature changes and rotational changes of the separate rotating body 6 is linear. This resulted in a proportional change that did not fall within the range between the upper and lower limit force lines, and undesirable gas combustion occurred. This example has two springs 1 connected in series.
1 and 12 form a strangler spring 8, which is attached with sufficient bias to close the choke 10 when the engine is cold, and when the engine temperature rises and reaches the set temperature,
Up until then, the spring 12 had been working solely due to the contact and pressing of the pinion arm 16 against the stopper 13.
By switching the springs 11 and 12 to work together, the spring constant of the strangler spring 8 is set to a large value K8.
By changing the slope of the cut-off force line to a smaller value, the inclination of the cut-off force line can be greatly changed so that it falls within the range between the upper and lower limit cut-off force lines.

The illustrated broken line represents the cut-off force line of this embodiment.
As mentioned above, the setting temperature for changing the spring from joint action to single action can be freely selected.
The contact point of 6 can be adjusted and set by means of a screw 7 (see FIG. 1). In addition, in this example,
Although one pinion arm 16 can be passed through the stopper 13 of the part where the two springs 11 and 12 are connected in series, two-stage spring constants can be used, but three or more spring constants can be used if necessary. If these springs are connected in series, a stopper is provided at each connected part, and one pinion arm is used to sequentially contact the stoppers, a more gentle spring can be achieved using three or more stages of spring constants. The cut-off force lines can be obtained.

The second embodiment shown in FIG.
The latches, etc. are the same as those in the first embodiment.

However, the relative positions of the stopper 13 and the pinion arm 16 are opposite to each other. Therefore, from the low temperature of the engine to the set temperature, the springs 11 and 12 work together.
From the set temperature to the room temperature, the spring 12 acts alone. Therefore, the change in the cut-off force line at the set temperature forms an inverted F-shape compared to the F-shape in the first embodiment, and an example of the cut-off force line is shown by a dashed-dotted line in FIG. In addition,
As in the first embodiment, three or more springs can be connected in series to obtain a spring constant of three or more stages. The third embodiment shown in FIG. 7 relates to a strangler spring in which two springs are combined in parallel.

A guide cylinder 51 is provided on the opposite side of the pinion 7 in the rotating body 5, and a rod-shaped central protrusion 54 having a zero circle is provided in the center of the guide cylinder 51. The spring 55 is wound around the outer periphery of the guide cylinder 51, one end is fixed to the base of the rotating body (not shown), and the other end extends outward to form a hook portion 56. The spring 57 is wound around the central protrusion 54, and its end is loosely inserted into the groove between the guide cylinder 51 and the central protrusion 54, and its tip is fixed to the groove 52 of the guide cylinder 51. The end of the pond is latched onto an L-shaped choke arm 58 provided on the choke shaft 9. The green portion of the guide cylinder 51 is provided with a protrusion 53 that extends outward in the direction of rotation, and the free end of an L-shaped choke arm 58 provided on the choke shaft 9 extends to the outer periphery of the guide cylinder 51 and is connected to the rotating body 50. There is a circumferential interval so that the choke arm 58 and the convex element 53 do not touch each other even when the choke shaft 9 rotates relative to each other. Moreover, the L-shaped choke arm 58 and the protrusion 53
and are disposed so as to be in contact with the hook portion 56 in relative rotation with the spring 55. In the third embodiment in which the strangler spring and related members are configured as described above, when the rotating body 50 is in the deepest clockwise position when the engine is cold,
The hook portion 56 of the spring 55 is attached to the protrusion 53 as shown in Fig. 7D.
and the L-shaped choke arm 58, and are set in a state where they are pressed in a direction that applies a closing force to the choke shaft 9. Also, the spring 57 is set in such a state that it is in contact with the L-shaped choke arm 58 and presses them in a direction that applies a closing force to the choke shaft 9. Since it is set to apply a closing force to the choke shaft via the arm 58, the closing force is due to the cooperation of both springs 55 and 57, and each of the springs 55 and 57 Let the imitation constant be Kc,K.

Then, the cooperative spring constant acts on the cut-off force as Kc+Ko. Also, when the engine reaches the set temperature, the hook portion 56 is activated by the setting of the spring 57 and the L-shaped choke arm 58
Since the choke shaft is set so that it starts to move away from the choke shaft, the closing force applied to the choke shaft in response to a subsequent temperature rise is due only to the bias remaining in the spring 57, and the spring constant in this case is Ko. FIG. 7E shows a state in which the hook portion 56 is completely separated from the choke arm 58. Here, since Kc+Ko>Ko, the slope of the cut-off force line corresponding to the temperature increase after the set temperature is shallower than that before that. Further, depending on the biasing state of the spring 55 when the protrusion 53 and the hook portion 56 are in contact with each other, the two cut-off force lines drawn with the set temperature as a boundary can have a sharp cross section. FIG. 8 shows an example of the cut-off force line according to the third embodiment using a two-dot chain line. As mentioned earlier, the requirements for the best choke valve shutoff force relative to the engine temperature differ depending on the type of engine, and the shape of the narrow shutoff force region between the upper and lower limits is never linear. It is actually refracted. The first aspect of the present invention,
The cut-off force lines created by the second and third embodiments each have different bending directions and faults, and the position where bending or faulting is required can not only be freely selected as the set temperature, but also by changing the spring constant of the spring. The inclination of the closing force line can be adjusted freely by selecting settings, and the strength of the closing force can be adjusted by changing the strength of the urging force when the spring is installed. By setting appropriately, the choke valve cut-off force requirements for all types of engines can be easily met. Furthermore, as is already clear,
In the configuration of the above embodiment, the means for switching the strangler spring consisting of a plurality of springs between single action and co-action and thereby changing the spring constant are the stopper 13, the pinion arm 16, the L-shaped choke arm 58, and the protrusion 53. , and a hook portion 56. As described above, the present invention provides an automatic choke mechanism for a carburetor that is configured to detect the engine temperature and transmit the displacement of the temperature sensing element that operates as a shutoff force to the choke valve via a spring. Since a spring constant changing means is provided to change the spring constant of the spring according to the displacement of the body, the choke valve's closing force can be kept within the desired range required by the engine, and it can be used during engine startup and warm-up. It automatically maintains the air-fuel ratio of the air-fuel mixture to the best possible value, thereby eliminating problems such as poor starting, unstable rotation, smoldering exhaust gas, and generation of harmful gases, as well as shortening the time required for the pig machine.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic diagram of the choke drive system used to explain the present invention, and FIG.
FIG. 3 is a side view of the first embodiment of the strangler spring; FIG. 4 is an exploded perspective view of FIG. 3; Figure A is a perspective view of the same type of strangler spring shown in Figure 4 F, Figure 5 is a graph of engine temperature versus choke valve shutoff force according to the first embodiment, and Figure 6 is a second embodiment of the strangler spring. 7 is a side view of the third embodiment of the strangler spring; FIG. 7 is a side view; FIG. FIG. 8 is a graph of engine temperature versus choke valve shutoff force according to the second and third embodiments. 4... Wax element (temperature sensing element), 6... Rotating body, 8... Strangler spring, 10... Choke valve, 60... Rotating body. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. In an automatic shut-off mechanism of a carburetor that is configured to transmit the displacement of a temperature sensing element activated by detecting the engine temperature to the shutoff valve via a spring, the spring is activated in response to the displacement of the temperature sensing element. An automatic spring constant yoke device characterized in that it is provided with a spring constant changing means for changing the spring constant of the automatic spring constant.