JPS631005Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a vacuum type ignition timing adjustment device.

Conventionally, there have been devices of this type as shown in FIGS. 1 to 5. In each figure, reference numeral 1 denotes a movable plate on which an engine ignition timing determining member (not shown) is mounted, and is rotatably provided. 2 is a rod connected to this movable plate and has a concave portion 2 which is an engaging portion.
It has a. 3 is a first diaphragm fitted to the tip of this rod; 4a and 4b are mounting fittings for fitting this first diaphragm to the rod 2; A contact portion 41b is formed. 5 and 6 are a pair of cases, which are formed by sheet metal processing. 7 is a first negative pressure chamber formed by this one case 5 and the first diaphragm 3; 8 is a nipple for introducing negative pressure formed in the case 5; 9 is the case 5; 6, 10 is a housing fixed to the case 6, 11 is a second diaphragm, and one end is connected to the housing 10.
The other end is fitted between the case 6 and the spacer 9, respectively. 12a and 12b are the second
One end of the diaphragm 11 is attached to the housing 10.
One of the mounting fittings 12b has an abutting portion 121b at the tip thereof. 1
Reference numeral 3 denotes an atmospheric chamber formed by the first diaphragm 3 and the second diaphragm 11, which communicates with the atmosphere. 14 is a second negative pressure chamber formed by the second diaphragm 11, the case 6, and the housing 10; 15 is provided in the case 6 and applies negative pressure to the second negative pressure chamber 14; The nipples 16a and 16b for introduction are holders that hold the second diaphragm 11, and the tip of one of the holders 16b has an abutting part 161b forming a second stopper, and the other holder 16a is provided with a first stopper 17 that engages with the recess 2a of the rod 2. 18
19 is a first compression coil spring installed between the first diaphragm 3 and the case 5 via the mounting bracket 4a, and 19 is the holder 16b.
A second compression coil spring is installed between the second diaphragm 11 and the case 6 via the spring force of the first compression coil spring 18.

Next, the operation will be explained. First, when negative pressure is introduced into the first negative pressure chamber 7 and atmospheric air is introduced into the second negative pressure chamber 14, the first diaphragm 3
Attempts to move to the left in the figure. Then, when the negative pressure in the first negative pressure chamber 7 increases and overcomes the spring force of the spring 18, the first diaphragm 3 is displaced in accordance with the increase in negative pressure. Therefore, the rod 2 connected to the first diaphragm 3 also moves in the direction of arrow E in FIG. 1, and rotates the movable plate 1 in the direction of arrow G to advance the ignition timing. Thereafter, when the negative pressure further increases and the rod 2 moves and the end face of the recessed portion 2a of the rod 2 comes into contact with the first stopper 17, the displacement of the first diaphragm 3 and the rod 2 is prevented, and the ignition progresses. The angle is also held constant. This state is shown in FIG. 2, and the ignition timing characteristics are shown in A of FIG.

Next, negative pressure is introduced into the second negative pressure chamber 14, and the first
When atmospheric air is introduced into the negative pressure chamber 7, the second diaphragm 11 is displaced to the right in FIG. Therefore, the contact part 41b of the mounting bracket 4b and the holder 16a
Since the first diaphragm 3 is moved in a state where it is in contact with the movable plate 1, the first diaphragm 3 also moves to the right, and the rod 2 connected to the first diaphragm 3 moves in the direction of arrow F in FIG. Turn it in the direction of arrow H to retard the ignition timing. After this, the second negative pressure chamber 1
When the negative pressure of 4 further increases, the second diaphragm 1
1. The first diaphragm 3 and rod 2 are also further displaced to the right. When the second stopper 161b comes into contact with the end surface of the case 6, each diaphragm 11,
3. Displacement of the rod 2 is prevented and the ignition retard angle is also kept constant. This state is shown in FIG. 3, and the ignition timing characteristics in that case are shown in B of FIG. Next, when negative pressure of the same magnitude is introduced into the first and second negative pressure chambers 7, 14, first the first diaphragm 3 resists the spring force of the first spring 18, as shown in FIG. The rod 2 is displaced to the left of the arrow E.
direction and rotates the movable plate 1 in the direction of arrow G to advance the ignition timing of the engine in accordance with the magnitude of the negative pressure. When the negative pressure introduced into the first and second negative pressure chambers 7 and 14 further increases, the second diaphragm 11 is displaced to the right in FIG. 1 against the spring force of the second spring 19. . This displacement of the second diaphragm 11 is caused by the second stopper 161b.
continues until it comes into contact with the case 6, and the amount of displacement is the dimension (m). Therefore, the first stopper 17 also moves to the right in FIG. That is,
Thereafter, even if the negative pressure increases, displacement of the rod 2 is prevented and the ignition advance angle is kept constant. This state is shown in Figure 4,
The ignition timing characteristics in that case are shown in FIG. 5C.

Since the conventional vacuum type ignition timing adjustment device is configured as described above, there are restrictions on the ignition timing characteristics that can be obtained. In other words, the total advance angle θ ₁ obtained by introducing negative pressure only into the first negative pressure chamber, the total retard angle θ 2 obtained by introducing negative pressure only into the second negative pressure chamber, and the total retard angle θ ₂ obtained by introducing negative pressure only into the second negative pressure chamber. The condition θ ₁ = θ ₂ + θ ₃ must be satisfied between the total advance angle θ ₃ obtained by introducing the same negative pressure into the negative pressure chamber, and the desired total retard angle θ ₂ and total advance angle θ ₃ could not be set freely, which had a negative effect on engine performance, especially output and feeling.

This idea was made to eliminate the drawbacks of the conventional ones as described above, and by eliminating the above constraint θ ₁ = θ ₂ + θ ₃ , it is possible to avoid adverse effects on the performance of the engine. The purpose of this invention is to provide a vacuum type ignition timing adjustment device.

An example of this invention is shown in Figs. 6 to 10 below.
The diagram will be explained.

In each figure, 9a is a third stopper provided protruding from the inner periphery of the spacer 9, which engages with the abutting portion 41b to restrict the amount of rightward displacement of the first diaphragm 3. There is.

Next, the operation will be explained. First, when negative pressure is introduced into the first negative pressure chamber 7 and atmospheric air is introduced into the second negative pressure chamber 14, the first diaphragm 3 tends to be displaced to the left in FIG. Then, when the negative pressure in the first negative pressure chamber 7 increases and overcomes the spring force of the spring 18, the first diaphragm 3 is displaced in accordance with the increase in negative pressure. Therefore, the rod 2 connected to the first diaphragm 3 also moves in the direction of arrow E in FIG. 6, and rotates the movable plate 1 in the direction of arrow G to advance the ignition timing. After this, when the negative pressure further increases and the rod 2 moves and the end surface of the recess 2a of the rod 2 comes into contact with the first stopper 17,
Displacement of the first diaphragm 3 and rod 2 is prevented, and the ignition advance angle is also kept constant. This state is shown in FIG. 7, and the ignition timing characteristics are shown in A of FIG. Next, when negative pressure is introduced into the second negative pressure chamber 14 and atmospheric air is introduced into the first negative pressure chamber 7, the second diaphragm 11 overcomes the spring force of the spring 19, as shown in FIG. Displace to the right. Therefore, since the contact part 41b of the mounting bracket 4b and the holder 16a are moved in contact with each other, the first diaphragm 3 is also moved to the right, and the rod 2 connected to the first diaphragm 3 is moved to the sixth position. Moving in the direction of arrow F in the figure, the movable plate 1 is rotated in the direction of arrow H to retard the ignition timing. After this, when the negative pressure in the second negative pressure chamber 14 further increases, the second diaphragm 11
The first diaphragm 3 and rod 2 are also further displaced to the right. Then, the mounting bracket 4 is attached to the third stopper 9a.
When the abutting portion 41b comes into contact with the first diaphragm 3 and the rod 2, displacement of the first diaphragm 3 and the rod 2 is prevented, and the ignition retard angle is also kept constant. Thereafter, when the negative pressure in the second negative pressure chamber 14 further increases, the second diaphragm 11 is further displaced to the right, and the contact portion 41b of the mounting bracket 4b separates from the holder 16a. After this, the second negative pressure chamber 1
When the negative pressure of 4 further increases, the second diaphragm 1
1 is further displaced to the right, and the second stopper 161b
comes into contact with the end face of the case 6. This state is shown in Figure 8, and the ignition timing characteristics in that case are shown in Figure 10.
_B1 , and the movement of the second diaphragm 11 converted into ignition timing characteristics is shown in D of FIG. Next, when negative pressure of the same magnitude is introduced into the first and second negative pressure chambers 7 and 14, first the first diaphragm 3 resists the spring force of the first spring 18 as shown in FIG. As a result, the rod 2 is displaced in the direction of arrow E, and the movable plate 1 is rotated in the direction of arrow G, thereby advancing the ignition timing of the engine in accordance with the magnitude of the negative pressure. Furthermore, when the negative pressure introduced into the first and second negative pressure chambers increases, the second diaphragm 11 is displaced to the right in FIG. 6 against the spring force of the second spring 19. This displacement of the second diaphragm 11 is caused by the second stopper 161.
This continues until b comes into contact with the case 6, and the amount of displacement is the dimension (m). Therefore, the first stopper 17
also shifts to the right in Figure 1 by the dimension (m), so
The amount of displacement of the rod 2 is only the dimension () - (m) until the end surface of the recessed portion 2a of the rod 2 comes into contact with the first stopper 17, and after that, even if the negative pressure increases, the displacement of the rod 2 will not change. This is prevented and the ignition advance angle is held constant. This state is shown in Figure 4,
The ignition timing characteristics in that case are shown in C of FIG.

That is, in this embodiment, since the total retard amount θ ₄ can be determined by the third stopper 9a provided on the spacer 9, the ignition timing characteristic can be kept constant as θ ₁ =θ ₂ +θ ₃ like in the conventional device. Since it is not regulated and it is possible to obtain a wide range of characteristics, it is possible to provide the engine with the optimum ignition timing.

Note that in the above, the displacement of the rod 2 in the E direction provides an advance angle characteristic, and the displacement in the F direction obtains a retardation characteristic. You can also do this.

Furthermore, in the above embodiment, the spacer 9 was provided on the side wall of the atmospheric chamber 13, but as shown in FIG.
may also be provided, and the same effect as in the above embodiment can be achieved.

As described above, according to this invention, by providing the third stopper, the ignition characteristics, θ ₁
= θ ₂ + θ ₃ is eliminated, the optimum ignition timing can be given to the engine, and since it can be done with a simple configuration, the cost does not increase.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional side view showing a conventional vacuum-type ignition timing adjustment device, Figs. 2 to 4 are sectional side views showing the operating state of a conventional vacuum-type ignition timing device, and Fig. 5 is a conventional vacuum-type ignition timing adjustment device. An ignition timing characteristic diagram obtained by an ignition timing adjustment device, FIG. 6 is a cross-sectional side view showing a vacuum type ignition timing adjustment device according to an embodiment of this invention, and FIGS. 7 to 9 are according to an embodiment of this invention. FIG. 10 is a cross-sectional side view showing the operating state of the vacuum type ignition timing adjustment device; FIG.
The figure is a cross-sectional side view showing a vacuum type ignition timing adjustment device showing another embodiment of this invention. In the figure, 1 is a movable plate, 2 is a rod, 2a is a recess, 3 is a first diaphragm, 4a and 4b are mounting brackets, 41b is a contact part, 5 and 6 are a case, and 7 is a first negative pressure chamber , 8 is nipple, 9 is spacer, 9
a is the third stopper, 10 is the housing, 11 is the second diaphragm, 12a, 12b are the mounting brackets, 121b is the contact part, 13 is the atmospheric chamber, 14 is the second negative pressure chamber, 15 is the nipple, 16a , 16b is a holder, 161b is a contact portion which is a second stopper, 17 is a first stopper, 18 is a first compression coil spring, 19 is a second compression coil spring, and 20 is an intermediate case. In the drawings, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of utility model registration request] An atmospheric chamber, first and second diaphragms that form this atmospheric chamber, and negative pressures that are formed on both sides of the atmospheric chamber between the first and second diaphragms and the case, depending on the operating state of the engine. first and second negative pressure chambers introduced into the respective chambers; a second spring, an ignition timing determining rod connected to the first diaphragm and having an engaging portion, connected to the second diaphragm in the atmospheric chamber, one end of which abuts the first diaphragm; a first stopper whose other end is engaged with the engaging portion of the rod to regulate the amount of displacement of the first diaphragm;
and a second stopper for regulating the amount of displacement of the second diaphragm; a second stopper extending inward from the case in the atmospheric chamber and regulating the amount of displacement of the first diaphragm in a direction opposite to the displacement direction; Vacuum type ignition timing adjustment device with 3 stoppers.