JPS631006Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of an ignition timing control device for an internal combustion engine, and particularly in one in which a diaphragm senses negative pressure fluctuations in the engine and controls the ignition timing accordingly. The present invention relates to an improvement of the diaphragm device for sensing pressure fluctuations.

The structure and function of a conventional diaphragm device will be explained below. In FIG.
It is divided into chambers A and B, and the backing plates 3 and 4 are placed on both sides of the center of the diaphragm 2, fixed at the end 5a of the rod 5, and the other end 5b of the rod 5 is passed through the chamber R. to protrude from the casing 1 to the outside. A spring 6 is set in the chamber 1, and the spring 6 acts to constantly push down the diaphragm 2. Further, an inlet 7 is provided in the chamber A to take in the negative pressure of the engine. Normally, when the engine is not operating, the diaphragm 2 is pressed against the spring 6 and the shoulder 5c of the rod 5 is pushed against the support bottom 1.
It is pressed against a. The configuration has been explained above, but to explain the function, that is, how it operates, the negative pressure inlet 7 connected to the engine.
Introduce negative pressure from the engine into chamber A. Inside the chamber, the position of the diaphragm 2 is balanced by the negative pressure of the engine at that time and the strength of the spring 6.
This is intended to match the ignition timing with the rotation of the engine by changing the position of the other end 5b of the rod 5 attached to the diaphragm 2 and changing the contact position of a switchboard (not shown) connected thereto. . Having explained the functions above, when the engine starts operating and is idling, that is, when the engine speed is 650~
At 850RP.M, the negative pressure in chamber A introduced from the engine is weaker than the pressing force of spring 6, so diaphragm 2 does not operate, the contact position connected to rod 5 does not move, and the ignition timing does not change. However, as the engine speed is gradually increased, the negative pressure inside the chamber gradually becomes stronger, and when the pressing force of the spring 6 is exceeded, the diaphragm 2 operates, moving the rod 5 and changing the ignition timing. It is something. The balance between the time when the diaphragm 2 starts operating and the negative pressure of the engine is very important, and if this balance is not well-balanced, the ignition timing will not be set correctly when the engine speed is increased, and the engine Not only does it reduce efficiency, but it also generates incompletely combusted gas, so it is not very environmentally friendly. Also, the error in the pressing force at the start of operation of this diaphragm 2 is
Due to the slight difference between 200 and 400g, spring 6
Depending on the spring coefficient of the spring, the difference in the length of the spring when set has a large effect on performance. Therefore, in the above structure, the set length of the spring 6 requires very little control. Therefore, looking at the parts that determine the set length of the conventional spring 6, in Fig. 1 the depth of the casing 1, the thickness of the backing plates 3 and 4, and the diaphragm
There are many factors such as the thickness of the shoulder part 5c of the rod 5, and even if each tolerance is kept small, the accumulated tolerance becomes large and it becomes difficult to keep the set length of the spring 6 within the standard. The present invention is an attempt to improve the above-mentioned drawbacks, and aims to reduce the number of parts that determine the set length of the spring 6 as much as possible.The present invention will be explained below using figures. , in Fig. 2,
A casing 1 formed from a thin metal plate is divided into chambers A and B by a diaphragm 2, and backing plates 3 and 4 are applied to the center of the diaphragm 2 on both sides,
It is fixed at the end of the rod 5, and the other end of the rod 5 is made to pass through the chamber and protrude outside from the casing 1. A spring 6 is set in the chamber 1, and the spring 6 acts to constantly push down the diaphragm 2. Further, an inlet 7 for taking in the negative pressure of the engine is attached to the chamber A.

As shown in FIG. 3, the shape of the backing plate 3 is as shown in FIG.
An edge 3b3c is provided which is bent outward from the outer periphery of the plate-shaped plate 3a. In the chamber 1, a stopper 8 as shown in FIG. 4 is provided on the casing 1. The stopper 8 is a ring-shaped plate with an inner notch 8a. The imaginary line indicates the edge 3 of the backing plate 3.
This is the case when b and 3c are engaged. The present invention has the above-mentioned structure, and its functions and effects will be explained below.The figure shown in Fig. 2 is the position when the negative pressure is rising, and the load of the spring 6 at this time is the rising load. Become. In this figure, the dimensions that affect the set length of the spring 6 are determined by dimensions C and D, that is, the drawing depth of the casing 1 and the dimension from the inner bottom surface of the backing plate 3 to the edge 3c. The maximum stroke of the diaphragm 2 is determined by the dimensions, that is, the inner dimensions of the edges 3c and 3b and the thickness of the stopper 8. As described above, according to the present invention, the length and stroke of the spring 6 for negative pressure rise can be made with fewer combinations of dimensions than in the past, so the stacking tolerance is also smaller, allowing for more severe negative pressure rise loads and progress. This provides angular characteristics.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional product. Figure 2 is a cross-sectional view of the product of the present invention. Figure 3A is a plan view of Figure 2. FIG. FIG. 4 is a plan view of FIG. 28.

Claims (1)

[Scope of utility model registration request] Separate the inside of the casing with a diaphragm, apply a backing plate to one or both sides of the diaphragm, fix it at the end of the rod, let the other end of the rod protrude outside from the casing, and protect the periphery of the diaphragm. , in an ignition timing control device for an internal combustion engine that is sandwiched between a casing, the outer periphery of a backing plate fixed to the diaphragm surface and integrally molded in a dish shape is cut out, at least four edges are provided, and 1. An ignition timing control device for an internal combustion engine, characterized in that adjacent edges have the same height, adjacent edges have different heights, and a stopper provided on a casing is engaged between the edges.