JPH0616994Y2 - Ignition timing control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an ignition timing control device for an internal combustion engine, and more particularly to an ignition timing control device for improving the spark advance characteristic of a spark ignition type internal combustion engine for an automobile.

[Prior Art] As a conventional ignition timing control device, generally, a centrifugal advance (governor advance) device for advancing the engine speed and a vacuum advance device for advancing the engine load (suction negative pressure). Is a combination of.

The centrifugal advance characteristic is determined in consideration of the torque at full load, and the vacuum advance characteristic is determined in combination with the centrifugal advance characteristic in consideration of the fuel consumption rate at partial load and the exhaust emission.

In this case, the ignition timing is usually matched with the ignition timing of the minimum advance angle (MBT) at the maximum torque in order to obtain the maximum torque, the best fuel economy, etc. In order to promote warm-up and clean exhaust emissions, the operation of the vacuum advance device is suppressed, and the ignition timing is retarded after that after warm-up (Actual opening 54-
157238, Japanese Utility Model Publication No. 54-167238, and Japanese Utility Model Publication No. 57-153771).

That is, in these conventional devices, two negative pressure chambers are formed by two diaphragms in the vacuum advance device, and when the warm-up is performed by the switching device in the middle of the negative pressure pipe, the negative pressure is switched to the atmosphere. The operation of the vacuum advance device is suppressed, and a predetermined amount of retard is performed to promote warm-up.

However, these conventional devices have a configuration in which two diaphragms are linked to each other so that the relative displacement between the two diaphragms is regulated. Therefore, for example, when applying to a high compression ratio engine using a lean mixture, There is such a problem.

Since the two diaphragms cannot operate independently, there is little design freedom. Therefore, it is difficult to obtain a sufficient amount of advancement (retardation) that matches the engine specifications, and it is difficult to obtain sufficient warm-up characteristics. If the angular amount is small, the catalyst inlet temperature will be too low and the exhaust emission will be deteriorated. On the other hand, if the retardation amount is too large, the output is rather reduced under high load and the drivability during warm-up is deteriorated.

The two diaphragms require the elements to be linked to each other, which increases the configuration and complicates it.

In addition, because the amount of advance (retard) that meets the engine specifications cannot be obtained, operation due to excessive retardation during low load operation such as idle operation where the control negative pressure introduced into the negative pressure chamber becomes low However, there is a problem in that, when the load is high, the control negative pressure is low, and when the load is high, the retard amount is insufficient and knocking occurs.

[Object of the Invention] The present invention is to provide two diaphragms independently in a vacuum advance device to form two negative pressure chambers, and a negative pressure chamber for controlling the advance angle in the upper negative pressure chamber. This was done with an eye on the fact that the upper end position of the indoor spring can be regulated as appropriate. This gives a degree of freedom in design, has a simple structure, improves drivability at low load operation such as idle operation, and at the time of high load. It is an object of the present invention to provide an ignition timing control device for an internal combustion engine that improves warm-up characteristics, such as prevention of knocking in the engine.

[Structure of the Invention] In order to achieve the above object, the present invention independently provides a first diaphragm and a second diaphragm on both sides of a partition in a case of a vacuum advance device, and the second diaphragm is provided with an ignition timing. The other end of the rod, one end of which is connected to the breaker plate that moves to change, is connected to form a first negative pressure chamber between the case and the first diaphragm, and between the first diaphragm and the second diaphragm. A second communication that forms a second negative pressure chamber, and the second negative pressure chamber is located so as to be located in the intake pipe upstream of the throttle valve when the throttle valve is fully closed and to be located in the intake pipe downstream of the throttle valve when the throttle valve is opened. To the mouth through the second passage, the first
The negative pressure chamber communicates with the first communication port that is located at the intake pipe downstream of the throttle valve, or is connected to the first passage that joins in the middle of the second passage, and the engine cools in the middle of the first passage. A thermo valve for reducing the negative chamber of the first negative pressure chamber is sometimes interposed, and the negative pressure of the second negative chamber is a vacuum advance angle in a predetermined low negative pressure region between the first diaphragm and the second diaphragm. A second spring for moving the breaker plate via the rod is arranged to control the angle to the most retarded side, and the negative pressure in the first negative pressure chamber is reduced between the case and the first diaphragm. At this time, the gist is that the first diaphragm is arranged to bring the first diaphragm into contact with the partition wall in the case to increase the set load of the second spring.

[Operation] During warm-up, when the engine is cold, the thermo valve
The negative pressure introduced into the upper (first) negative pressure chamber is reduced as compared with after warming up, the first diaphragm descends and abuts against the partition wall,
The set load of the second spring of the second negative pressure chamber is increased.

By the way, in the low negative pressure region where the control negative pressure introduced into the second negative pressure chamber is predetermined, the second spring drives the breaker plate via the rod so as to control the vacuum advance angle to the most retard side. During warming up, the second diaphragm does not rise regardless of warming up. Therefore, during low load operation warming up near the throttle valve fully closed, such as in idle operation, where a predetermined low negative pressure region is reached, the delay after warming up is delayed. Since it is set to be the same as the angle amount (the most retarded vacuum advance angle), the driveability failure due to the excessive retardation is prevented. In addition, the same as in the above idle operation such as low load operation
Even under high load operation near the throttle valve full opening where the control negative pressure introduced into the negative pressure chamber becomes a predetermined low negative pressure region, the vacuum advance angle has the most retarded characteristic regardless of the engine temperature. Is prevented from occurring.

Further, during warm-up in an operating region in which the control negative pressure introduced into the second negative pressure chamber from the second communication port is larger than a predetermined low negative pressure region, after warming up (the negative pressure in the first negative pressure chamber is reduced). Is released and the first diaphragm is raised), the second spring pushes the second diaphragm and the rod to maintain the breaker plate in a more retarded position, and the second negative pressure chamber advances the angle. Is delayed and the warm-up is promoted.

[Embodiment] The present invention will be described below based on an embodiment. FIG. 1 is a diagram showing a first embodiment of the present invention. First, the configuration will be described. The distributor 1 includes a vacuum advance device 4 that holds the breaker plate 2 rotatably and that is connected to the breaker plate 2 by a pin 3.

The vacuum advance device 4 has a control negative pressure chamber (second negative pressure chamber) 5, a second spring 6 and a second diaphragm 7. The second diaphragm 7 is connected to the breaker plate 2 with a pin 3 by a rod 8. To be done.

The vacuum advance device 4 also includes a suction negative pressure chamber (first negative pressure chamber) 9
The first spring 10, the first diaphragm 11, and the stopper 12 are provided, and the negative pressure chambers 5 and 9 are separated by the partition wall 13.

The communication port 16 of the first negative pressure chamber 9 is located in the intake pipe 20 downstream of the throttle valve 19 via the check valve 18 and opens.
The communication port 21 is continuous with the first passage 22, and the communication port 17 of the second negative pressure chamber 5 is the second communication port 2 of the control negative pressure near the throttle valve 19.
3 via a second passage 24. This second communication port 23
Is located in the intake pipe 20 upstream of the throttle valve 19 when the throttle valve 19 is fully closed, and is opened in the intake pipe 20 downstream of the throttle valve 19 when the throttle valve 19 is opened.

The thermo valve 30 provided in the middle of the first passage 22 is
By having the bimetal 31 and the leaf spring 32 and being installed in the cooling water passage, the valve is opened when the engine is cold, and the air is introduced from the air filter 33 into the first negative pressure chamber 9 through the passage 34. 1 The negative pressure in the negative pressure chamber 9 is reduced.

The first spring 10 is mounted between the case 14 and the first diaphragm 11 of the vacuum advance device 4, and the first negative pressure chamber 9
If the negative pressure of the
The inner partition wall 13 is closely contacted, and at this time, the second spring 6 mounted between the second diaphragm 7 and the first diaphragm 11 is compressed to increase its repulsive force and increase the set load. There is. The stopper 12 is the first
The upper limit position of the diaphragm 11 is restricted.

The second spring 6 is provided in the second negative pressure chamber 5 as shown in FIG.
In the low load operation area near the throttle valve 19 fully closed and the high load operation area near the throttle valve 19 fully open, such as during idle operation when the control negative pressure becomes a predetermined low negative pressure area m, before or after warming up. First, the breaker plate 2 is driven via the rod 8 in order to control the vacuum advance angle to the most retard side. Further, the second spring 6 reduces the negative pressure of the first negative pressure chamber 9 during warm-up in an operating region where the control negative pressure introduced into the second negative pressure chamber 5 is larger than a predetermined low negative pressure region m. Is released and the first diaphragm 11 is lifted, the second spring 6 pushes the second diaphragm 7 and the rod 8 to maintain the breaker plate 2 in a more retarded position. The advance angle by the second negative pressure chamber 5 is defined as the retard angle.

The case 4 is the housing 1 of the distributor 1.
5 is integrally provided.

Next, the operation of the above embodiment will be described.

(A) Before warming up (FIG. 1) Before warming up the engine, that is, during warming up until the cooling water temperature reaches the set temperature, as shown in FIG. Opening the bimetal 31 of the passage 34
Since the atmosphere is introduced through the first negative pressure chamber 9, the negative pressure in the first negative pressure chamber 9 is reduced, the first diaphragm 11 descends and contacts the partition wall 13, compresses the second spring 6, and strengthens its repulsion force. Increase the set load.

When the throttle valve 19 is opened in this state to increase the control negative pressure of the second communication port 23, this negative pressure is transferred to the second via the second passage 24.
Although it extends to the negative pressure chamber 5, the second diaphragm 7 is operated by the second spring 6 so as to have a certain pressure, that is, a predetermined low negative pressure in low load operation such as idle operation or high load operation, as shown in FIG. The region m, that is, the point Q does not move upward, and the vacuum advance angle by the second negative pressure chamber 5 is controlled to the most retard side. In this embodiment, the vacuum advance angle is set to the most retard side up to the point P where the control negative pressure is set higher than the point Q.

When the control negative pressure further increases from the point P, the second diaphragm 7 contracts the second spring 6 and moves upward, and eventually the angle advances and becomes constant as shown by the dotted line A in FIG. In this case, since the negative pressure is applied to both sides of the first diaphragm 11, the first diaphragm 11 stands still and maintains the position shown in FIG.

(B) After warming up (FIG. 3) After warming up the engine, the cooling water temperature exceeds the set temperature, so that the bimetal 31 of the thermovalve 30 reverses against the leaf spring 32 and shuts off the atmosphere. The suction negative pressure from the communication port 21 reaches the first negative pressure chamber 9 via the check valve 18, and the first diaphragm 11 is raised until the first spring 10 is contracted and abuts on the stopper 12 (state shown in FIG. 3). ).

As a result, the second spring 6 of the second negative pressure chamber 5 expands, and the apparent spring constant becomes weaker, but the control negative pressure is weaker. Similarly, the second diaphragm 7 does not move upward and does not advance to the point Q in FIG.

However, when the control negative pressure gradually increases, the second diaphragm 7 moves upward and advances as shown by the solid line B in FIG. In this case, the advance amount H with respect to before warm-up corresponds to the distance until the first diaphragm 11 hits the stopper 13.

That is, on the contrary, before the warm-up shown by the dotted line in FIG. 2, at the point P where the control negative pressure exceeds the predetermined low negative pressure region m, the engine is retarded by H, and warm-up promotion and exhaust emission are good. In addition, the retard angle can be set in any manner by changing the height of the stopper 13, and the engine specifications can be changed at any time.

Further, since the control negative pressure is not retarded before warming up after warming up in a predetermined low negative pressure region m, after warming up during low load operation such as idling operation, which is the low negative pressure region m. It is possible to prevent poor drivability due to being retarded more than the advance characteristic of. Further, at the time of high load at the time of throttle valve fully open output in the above-mentioned low negative pressure region m, the most retarded angle advance characteristic is obtained, so that knocking is surely avoided.

Since the suction negative pressure is introduced into the first negative pressure chamber 9 via the check valve 18, even when the suction negative pressure becomes weak and the load is high, the strong suction negative pressure in the previous operating state remains. Therefore, the first diaphragm 11 is brought into close contact with the stopper 12 to prevent the first diaphragm 11 from descending, whereby the advance angle can be made as predetermined.

FIG. 4 shows the second embodiment.

In this embodiment, the thermo valve 30 is of a wax type, and when it is extremely cold, the air filter 33 is shut off to introduce a negative pressure as shown in FIG. 4, thereby advancing the angle to facilitate starting. The point is different from the above embodiment.

When the first set temperature is exceeded from the extremely cold state, the first diaphragm 11 is brought into contact with the partition wall 13 by communicating with the air filter 33 to guide the atmosphere, as in the above-described embodiment. Furthermore,
When the second set temperature is exceeded, the full stroke of the thermo valve 30 again shuts off the inlet of the air filter 33 to guide the suction negative pressure to the first negative pressure chamber 9 and the first diaphragm 11
Move up.

Therefore, also in this embodiment, in the operating region where the control negative pressure exceeds the predetermined low negative pressure region, the warm-up is promoted by being retarded before the warm-up compared with after the warm-up, while the predetermined low negative pressure is increased. In the area, the vacuum advance angle is controlled to the most retard side,
It is possible to prevent defective driving during idle operation and avoid knocking during high load when the throttle valve is fully opened.

FIG. 5 shows a third embodiment.

This embodiment has the same characteristics as the first embodiment without a check valve, and the first spring 10 of the first negative pressure chamber 9 sets the spring constant to be very weak and The effective area of the first diaphragm 11 is set to be slightly larger than that of the second diaphragm 7.

Further, the communication port 16 of the first negative pressure chamber 9 has a thermo valve 40.
Is connected to the communication port 41 of No. 2 through the passage 22, and the communication port 42 opposite to the thermovalve 40 is connected through the passage 43 to the first communication port 2 for suction negative pressure.
Connect to 1. In this case, the passage 43 also constitutes the first passage together with the passage 22.

When the thermo valve 40 is cold, the valve body 44 has the communication port 4
When the second side is shut off and the set temperature is exceeded, the valve body 45 shuts off the air filter 33 side.

Therefore, before warming up, the atmosphere is introduced into the first negative pressure chamber 9 through the air filter 33, the first diaphragm 11 is brought into contact with the partition wall 13 as shown in FIG. 5, and as shown by the dotted line A in FIG. In addition, the angle is delayed compared to the solid line B after warming up.

Next, after warming up, since the thermo valve 40 communicates with the suction negative pressure side of the first communication port 21, the first diaphragm 11 rises and advances the angle before warming up. In this case, since a check valve is not provided in the suction negative pressure passage 43, the weak suction negative pressure under high load reaches the first negative pressure chamber 9 without interruption.
Since the first spring 10 is weak and the first diaphragm 11 is slightly large, the first diaphragm 1
No. 1 remains in close contact with the stopper 12, and a more uniform advance is performed than before warming up. This advance angle characteristic is shown by the straight line B in FIG.

Since the engine load is plotted on the horizontal axis in this advance angle characteristic diagram, the control negative pressure is reduced due to the decrease in the absolute value of the negative pressure in the low load operating range m ₁ and the high load operating range m ₂ such as during idle operation. It indicates that the specified low negative pressure region has been reached and the advance angle value is decreasing both before and after warm-up, which results in operation due to excessive retardation during low load operation such as idle operation. Poor performance and knocking under high load are reliably avoided.

When the spring constant of the first spring 10 of the first negative pressure chamber 9 is set to be slightly strong, the effective suction negative pressure is slightly decreased from V to Ve in FIG. 7 by the amount of contraction of the first spring 10 after the engine is warmed up. Therefore, when the engine is in a medium and high load, the characteristic becomes retarded, as indicated by the chain line C in FIG. 6, and this can be a countermeasure when knocking occurs.

In FIG. 7, Vc is the control negative pressure, and M is the maximum advance angle control negative pressure.

FIG. 8 shows a fourth embodiment.

In this embodiment, the first negative pressure chamber 9 is provided in the middle of the second passage 24 connecting the communication port 17 and the second communication port 23 of the second negative pressure chamber 5.
The first passage 22 connected to the communication port 16 is joined at the joining point G, and a thermo valve 30 for reducing the negative pressure of the first negative pressure chamber 9 when the engine is cold is provided in the middle of the first passage 22. The same control negative pressure is introduced into the first and second negative pressure chambers 9 and 5.

In this case, since the bimetal 31 is closed when the engine is cold, the control negative pressure is cut off from the first negative pressure chamber 9 and the first negative pressure chamber 9 is closed.
Atmosphere remains trapped in the first diaphragm 11
Contacts the partition wall 13 to increase the set load of the second spring 6.

Therefore, also in this embodiment, when the control negative pressure exceeds the predetermined low negative pressure region during cold, the advance characteristic after warming up shown by the solid line H is obtained as shown by the dotted line C in FIG. Delays,
Accelerate warm-up. On the other hand, in the low negative pressure region m where the negative pressure is predetermined,
Since the advance angle is the same as that after warming up indicated by the solid line H, it is possible to reliably improve the drivability at the time of low load operation such as idle operation and avoid the knocking at the time of high load.

After the bimetal 31 is opened and the control negative pressure is introduced into the first and second negative pressure chambers 9 and 5, after warming up, the throttle valve 19 in the low control negative pressure region is fully closed, At the time of high load when fully opened, the state of the vacuum advance device 4 is as shown in FIG. 8, and the first diaphragm 11 descends until it contacts the partition wall 13 as before warming up. Therefore, in this case, the vacuum advance angle is small, as indicated by m in FIG. 9, and it is possible to improve the drivability during idle operation and prevent knocking.

When the throttle valve 19 is closed as shown by the arrow from the state of FIG. 8, the first diaphragm 11 and the second diaphragm 7 rise with the same distance maintained until the first diaphragm 11 hits the stopper 12. And advance. This is the first
Since the same negative pressure is applied to the upper and lower surfaces of the diaphragm 11,
This is because the pressure rises so as to cancel this regardless of the increase in the negative pressure. This state is shown by the solid line h ₁ in FIG. 9, and the point K is the contact point with the stopper 12.

Further, when the throttle valve 19 is closed, the negative pressure increases, but since the first diaphragm 11 is stopped, the force of the second spring 6 apparently becomes stronger, and the second spring 6 does not displace relative to the negative pressure.
As indicated by h _{2 in} the figure, the inclination is gentle, the advance angle ratio is reduced, and emission is prevented to meet engine specifications.

Conventionally, since the spring in the vacuum advance device has a linear spring constant, only a straight advance characteristic was obtained, but in this embodiment, the advance characteristic can be made non-linear with a two-step broken line, A simple device can meet the demand for complicated specifications such as avoiding knocking at high load time.

FIG. 10 shows a fifth embodiment. This embodiment is the first
The negative pressure chamber 9 is connected to the first communication port 21 of the suction negative pressure in the first passage 22 via the thermo valve 30, and the effective area of the first diaphragm 11 is larger than that of the second diaphragm 7. Is.

That is, in FIG. 10, the thermo valve 30 shuts off the first passage 22 by closing the bimetal 31 when the engine is cold.
Since the first negative pressure chamber 9 is always kept at the atmospheric pressure, the first diaphragm 11 descends until it comes into contact with the partition wall 13. As a result, the second diaphragm 7 undergoes the maximum lift change from 6h to 3h and is delayed. You will be cornered. That is, as shown in FIG. 11, the advance characteristic in the cold state before warming up is retarded as shown by C in contrast to the advance characteristic H in the warm state after warming up to accelerate warming up.

This advance angle characteristic diagram shows that the control negative pressure is a predetermined low negative pressure region in the low load operating region m ₁ such as at the time of idle operation where the engine intake negative pressure is large, and the high load operating region m ₂ where the engine intake negative pressure is small. Indicates that the advance angle value decreases both before and after warm-up, which results in poor driveability due to excessive retardation at low load such as at idle, and at high load. Knocking is reliably avoided.

After the warm-up in which the bimetal 31 is opened and the suction negative pressure of the first communication port 21 is introduced into the first negative pressure chamber 9, the operation will be described with reference to FIG. The negative pressure becomes a straight line VI (dashed line) on the right side of the throttle opening, and the control negative pressure generated at the second communication port 23 becomes a mountain curve (solid line) VC. The VI is large up to the middle of the throttle opening degrees θ ₁ and θ ₂ , and becomes the same thereafter.

Therefore, since there is no suction negative pressure before the engine is started, the vacuum advance device 4 is as shown in FIG. 13. However, when the vacuum advance device 4 is started and the throttle valve openings are opened to θ ₁ and θ ₂ , the 14th As shown in the figure, the first diaphragm 11 rises and the second diaphragm 7 advances the angle.

Next, when the throttle opening becomes θ ₃ , VC and VI are the same, and the absolute value of the negative pressure also decreases. Therefore, as shown in FIG. 15, the force of the first spring 10 causes the first diaphragm to move. 11
Descends until it abuts the partition wall 13. And the opening θ ₄
After that, the advance is performed by the second diaphragm 7 in the state of FIG.

X in FIG. 12 indicates the position change of the first diaphragm 11,
Indicates the position change of the second diaphragm 7, and Z indicates the position of the partition wall 13.

In this way, the second diaphragm 7 rapidly descends with a slight opening in the high load range m ₂ , so that the ignition timing is delayed as shown by the solid line H as shown in FIG. Next to
Knocking is constantly prevented in the high load range.

[Effect of the Invention] As described above, according to the present invention, when the control negative pressure introduced into the second negative pressure chamber is within the predetermined low negative pressure region,
Since the spring drives the breaker plate via the rod to control the vacuum advance angle to the most retarded side, the second diaphragm does not rise during warm-up, regardless of whether it has warmed up. At low load operation near the throttle valve fully closed, such as in idle operation, when warming up, the delay angle after warming up (the most retarded vacuum advance angle) is set to the same value. It is possible to prevent poor drivability. Further, as in the low load operation such as the idle operation described above, even during the high load operation in the vicinity of the fully opened throttle valve where the control negative pressure introduced into the second negative pressure chamber becomes a predetermined low negative pressure region, the vacuum is generated regardless of the engine temperature. Since the advance angle has the most retarded characteristic, it is possible to reliably avoid knocking.

Further, during warm-up in an operating region in which the control negative pressure introduced into the second negative pressure chamber from the second communication port is larger than a predetermined low negative pressure region, after warming up (the negative pressure in the first negative pressure chamber is reduced). Is released and the first diaphragm is raised), the second spring pushes the second diaphragm and the rod to maintain the breaker plate in a more retarded position, and the second negative pressure chamber advances the angle. Is delayed and the warm-up is promoted.

In this case, since the diaphragms are provided independently of each other, the movements of these diaphragms can be freely performed and may match those of the engine specifications. There is an effect that the characteristics such as obtaining the output at, and tilting at a low load to improve the emission can be obtained with a simple structure.

[Brief description of drawings]

FIG. 1 is an overall view of an embodiment of the present invention, FIG. 2 is an advance angle characteristic diagram of the example of FIG. 1, FIG. 3 is a partial view for explaining the operation of the example of FIG. 1, and FIG. Overall view of the second embodiment, FIG.
6 is an overall view of the embodiment, FIG. 6 is an advance characteristic diagram with respect to engine load, FIG. 7 is a negative pressure characteristic diagram of the same, FIG. 8 is an overall view of the fourth embodiment, and FIG. 9 is an advance angle with respect to suction negative pressure. Characteristic diagram, No. 10
FIG. 11 is an overall view of the fifth embodiment, FIG. 11 is an advance characteristic diagram with respect to suction negative pressure, FIG. 12 is a variation characteristic diagram of negative pressure and diaphragm movement distance with respect to throttle opening, and FIGS. 15 and 15 are operation state diagrams of the example of FIG. Description of reference numerals shown in the drawings 1 ... Distributor 2 ... Breaker plate, 4 ... Vacuum advance device 5 ... Second negative pressure chamber, 6 ... Second spring 7 ... Second diaphragm, 8 ... Rod 9 ... First negative pressure Chamber, 10 ... 1st spring 11 ... 1st diaphragm 12 ... Stopper, 13 ... Partition wall 14 ... Case, 19 ... Throttling valve 20 ... Intake pipe, 21 ... 1st communication port (suction negative pressure) 22 ... 1st passage 23 ... Second communication port (control negative pressure) 24 ... Second passage 30, 40 ... Thermo valve

Claims (1)

[Scope of utility model registration request] 1. A vacuum advancing device is provided with a first member on each side of a partition wall inside a case.
A diaphragm and a second diaphragm are provided independently, and the second diaphragm is connected to the other end of a rod, one end of which is connected to a breaker plate that moves to change the ignition timing, and between the case and the first diaphragm. A first negative pressure chamber and a second negative pressure chamber between the first diaphragm and the second diaphragm, and the second negative pressure chamber is located in the intake pipe upstream of the throttle valve when the throttle valve is fully closed. In addition, when the throttle valve is opened, the second communication port is opened so as to be located in the intake pipe downstream of the throttle valve.
The first negative pressure chamber is connected to the first communication port that is located in the intake pipe downstream of the throttle valve and is open, or is connected to the first passage that joins in the middle of the second passage, A thermo valve for reducing the negative pressure of the first negative pressure chamber during the engine cold state is provided in the middle of the first passage, and the negative pressure of the second negative pressure chamber is provided between the first diaphragm and the second diaphragm. A second spring for moving the breaker plate through the rod is arranged to control the vacuum advance angle to the most retard side in a predetermined low negative pressure region, and the first negative pressure is provided between the case and the first diaphragm. An ignition timing control device for an internal combustion engine in which a first diaphragm is arranged to bring a first diaphragm into contact with a partition wall in a case to increase a set load of a second spring when the negative pressure in the pressure chamber is reduced.