JPS6147971B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition timing control device for an internal combustion engine.

[Conventional technology]

An exhaust gas recirculation device is installed that recirculates a portion of the exhaust gas to the intake system depending on the operating state of the engine, thereby suppressing the maximum combustion temperature and reducing the generation of nitrogen oxides (NOx). However, when exhaust gas recirculation (hereinafter referred to as EGR) is performed, the combustion speed decreases, resulting in a loss of output and drivability, and moreover, there are disadvantages such as deterioration of fuel efficiency.

By the way, Japanese Utility Model Application Publication No. 52-164637, which is an example of prior art that attempts to solve this inconvenience,
The negative pressure in the intake passage that activates the EGR device is
At the minimum opening of the throttle valve, the opening is located upstream of the throttle valve, and when the opening is above a predetermined opening, the opening located downstream of the throttle valve leads to the negative pressure chamber of the EGR valve. An ignition timing control device is described in which the amount of advance is increased as the engine load increases by introducing the negative pressure into the negative pressure chamber on the advance side of the vacuum advance device through a control valve that allows air to escape. has been done.

However, according to this, since both the EGR operation and the advance angle operation of the vacuum advance angle device are controlled by negative pressure from the same negative pressure source, it is difficult to operate both of them by a predetermined amount. In particular, in a transient state such as during acceleration, the change in negative pressure is delayed, so there is a problem that a large negative pressure may lead to poor responsiveness when the vacuum advance device is advanced.

[Problem that the invention seeks to solve]

The present invention has been made based on the above-mentioned circumstances, and is intended to provide an ignition timing control device for an internal combustion engine that eliminates the above-mentioned problems.

[Means for solving problems]

In order to achieve the above object, the present invention provides an EGR valve operated by negative pressure in the intake passage in the EGR passage to recirculate part of the exhaust gas into the intake passage.
It has an EGR device and a vacuum advance device connected to the breaker plate of the distributor, and the vacuum advance device is activated by negative pressure in the intake passage downstream of the throttle valve to advance the angle. A first control valve having a negative pressure chamber and controlling the supply of negative pressure to the negative pressure chamber is provided, and the negative pressure for operating the EGR device is supplied upstream of the throttle valve of the carburetor at its minimum opening. The first and second control valves are connected to a second control valve, which controls the negative pressure to be released to the atmosphere and leads the negative pressure from an opening located downstream at a predetermined opening degree or more. The vacuum advance device is characterized in that it is operated in accordance with pressure fluctuations within the exhaust pipe, and the amount of advance by the vacuum advance device increases as the load on the engine increases.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 is a carburetor, 2 is an intake passage, 3 is a cylinder, 4 is an exhaust passage, and 4 is an exhaust passage.
An EGR passage 5 is provided which communicates the intake passage 2 with the intake passage 2, and the passage 5 has a control orifice 6 and
EGR valve 7 is provided. The negative pressure chamber 10 of the pressure response device 8 that operates the EGR valve 7 is
Throttle valve 12 via pipe 11 and passage 11a
An opening 13 provided so as to be located upstream of the opening when the opening is at a minimum, and located downstream of the opening when the opening is a predetermined opening or more.
is connected to.

Breaker plate 1 of distributor 14
The vacuum advance angle device 16 that controls the vacuum advance angle device 5 has two first and second negative pressure chambers 17 and 18 that are isolated from each other.
Both negative pressure chambers 17, 18 are partitioned by diaphragms 20, 21. Also, breaker plate 1
The rod 22 connecting the vacuum advance angle device 16 with the
The rod 2 is fixed to the diaphragm 21 and is slidable and airtightly penetrates the diaphragm 20.
The locking portion 49 of the second step portion and the locking portion 50 of the diaphragm 20 are configured to lock when the diaphragm 20 moves in the advancing direction A, and the tip engages with the breaker plate 15. are doing.

The diaphragm 21 of the second negative pressure chamber 18 is biased by the spring 25, and the rod 22 pushes the breaker plate 15 in the retard direction R. On the other hand, the diaphragm 20 of the first negative pressure chamber 17 is also deflected in the retard direction R by the spring 24 provided between the partition wall 23 interposed between the diaphragm 21 and the diaphragm 21 . The stop portion 49 and the diaphragm 20 are positioned close to each other without being pressed against each other.

The first negative pressure chamber 17 communicates with an opening 27 provided through a negative pressure passage 26 so as to be located upstream of the throttle valve 12 when the opening is at its minimum, and located downstream of the throttle valve 12 when the opening is a predetermined opening or more. . Second negative pressure chamber 1
8 communicates with the intake passage 2 via a first control valve 29 through a negative pressure passage 28 at a downstream position remote from the throttle valve 12 . The control valve 2
9, a rod 31 connected to the valve body 30 passes through the partition wall 32 in an airtight manner and is connected to a diaphragm 33, and the diaphragm 33 is connected to the valve body 3 by a spring 34.
0 is provided so as to be in pressure contact with the valve port 30'.

On the other hand, a passage 35 connected to the EGR negative pressure passage 11a is inserted into a chamber 37 of a negative pressure control valve 36, which is a second control valve, and its open end faces a valve plate 39 fixed to a diaphragm 38. are doing. The diaphragm 38 is held against the valve plate 3 by a spring 40.
9 is held at a position away from the open end of the passage 35, and the chamber 37 is
The first control valve 29 and the negative pressure control valve 36, which are the second control valves, communicate with the atmosphere through the
a chamber 33' adjacent to the diaphragm 33, 38;
38' communicates with the EGR passage 5 via the passages 6'', 6' and the control orifice 6. Reference numeral A in the figure indicates the direction of advance angle.

Next, the operation of this device will be explained. When the throttle valve 12 is fully closed or slightly opened, the opening 1
3 and 27 are located upstream of the throttle valve 12, and there is almost no negative pressure at the opening thereof, and the exhaust pressure in the exhaust passage 4 is also low. Therefore, EGR
Valve 7, vacuum advance device 16, first control valve 2
9. None of the negative pressure control valves 36, which are the second control valves, operate, EGR is not performed, and ignition timing is not advanced.

When the throttle valve 12 opens beyond a predetermined opening degree due to an increase in load, the openings 13 and 27 become downstream of the throttle valve 12, and negative pressure is generated at the opening, which causes the EGR pressure response device 8 to Negative pressure chamber 1
0, is transmitted to the first negative pressure chamber 17 of the vacuum advance angle device 16. On the other hand, the exhaust pressure is not so high, so the first control valve 29 and the negative pressure control valve 36, which is the second control valve, do not operate. Therefore, the open end of the passage 35 inserted into the control valve 36 remains apart from the valve plate 39, and the negative pressure acting on the negative pressure chamber 10 leaks to the atmosphere through the chamber 37 and the filter 41. This means that the EGR valve 7 will be smaller.
The opening degree is small, and the amount of EGR is controlled to a small amount.
On the other hand, the reason why negative pressure is supplied to the first negative pressure chamber 17 of the vacuum advance device 16 from the opening 27 is to advance the angle by deflecting both diaphragms 20 and 21 against the springs 24 and 25. The amount of advance angle is small. However, since the amount of EGR is small, the advance angle is just right to accommodate that.

Next, when accelerating or under high load, the exhaust pressure increases and this flows through the passages 6, 6', 6'' to the
It acts on the second control valve 29 and the negative pressure control valve 36, which is the second control valve, and operates them together. That is, in the negative pressure control valve 36, the diaphragm 38 is deflected against the spring 40 due to exhaust pressure, and the valve plate 39
closes the open end of the passageway 35 and stops leakage of negative pressure from the opening 13 to the atmosphere. As a result, negative pressure chamber 1
The negative pressure acting on the throttle valve 7 increases, the negative pressure corresponding to the opening degree of the throttle valve 12 is supplied, the opening of the EGR valve 7 increases, and a large amount of EGR is performed, and the first control valve 29 , diaphragm 3
3 is deflected against the spring 34 by the exhaust pressure, and the valve body 30 separates from the valve port 30' and opens it, thereby opening the passage 2 to the second negative pressure chamber 18 of the vacuum advance device 16.
Throttle valve 12 of intake passage 2 through 8
Negative pressure on the downstream side further away is supplied, and the first
An opening 27 opens directly below the throttle valve 12 in the intake passage 2 through the negative pressure passage 26 in the negative pressure chamber 17.
However, due to the negative pressure supplied to the second negative pressure chamber 18, the diaphragm 21 that partitions this chamber is largely deviated to the left against only the spring 25, so that the amount of ignition advance is becomes larger.

Thus, by using a large amount of EGR, it is possible to control the generation of NOx during acceleration or high load, and on the other hand, by increasing the ignition angle, it is possible to prevent deterioration of drivability, decrease in output, and deterioration of fuel efficiency due to an increase in the amount of EGR.

FIG. 2 shows another example of the vacuum advance angle device. This device includes a first negative pressure chamber 43, a second negative pressure chamber 44, diaphragms 45 and 46 that partition both negative pressure chambers, and a spring 4.
7 and 48, the diaphragm 46 of the second negative pressure chamber 44 is connected to the breaker plate 52 by a first connecting rod 51, and the diaphragm 45 of the first negative pressure chamber 43 has a tip of the second connecting rod 53. First connecting rod 51
It is slidably engaged and connected to a long hole 55 provided in the.

Therefore, when negative pressure is supplied to the first negative pressure chamber 43,
The diaphragm 45 is deflected and pulls the second connecting rod 53, and the tip of the second connecting rod 53 hits the end of the elongated hole 55 of the first connecting rod 51, attracting the first connecting rod 51 as well, and advancing the angle. It will be done. When negative pressure is supplied to the second negative pressure chamber 44, the diaphragm 46 is deflected to pull only the first connecting rod 51, further increasing the amount of advance.

In the illustrated example, the control valves 29 and 36 are configured as separate units, but by providing a common diaphragm operated by exhaust pressure,
Both control valves can be constructed integrally.

〔Effect of the invention〕

As is clear from the above, according to the present invention,
Since it is configured to increase the amount of advance of the ignition timing in accordance with the increase in the amount of EGR, it is possible to prevent a decrease in fuel speed due to EGR and achieve improvements in output, drivability, and fuel efficiency.

In addition, since the negative pressure that operates the exhaust gas recirculation device and the negative pressure that advances the vacuum advance device are different, these operations are performed by a predetermined amount by each different negative pressure, and the above-mentioned advance Since negative pressure downstream of the throttle valve in the intake passage acts on the negative pressure chamber of the vacuum advance device that operates the angle, negative pressure is always applied to the first control valve even in transient conditions such as during acceleration. Since the timing is extended without delay, the responsiveness when advancing the vacuum advance angle device becomes better.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention, and FIG. 2 is a diagram showing another embodiment of the vacuum advance angle device. 1... Carburetor, 2... Intake passage, 4... Exhaust passage, 5
...EGR passage, 7...EGR valve, 8...pressure response device, 10...negative pressure chamber, 12...throttle valve, 1
6... Vacuum advance device, 17... First negative pressure chamber, 18... Second negative pressure chamber, 20, 21... Diaphragm, 23... Partition wall, 29... First control valve, 30... Valve body, 36... Negative pressure Control valve (second control valve), 41...filter.

Claims (1)

[Claims] 1. An exhaust gas recirculation device that includes an exhaust gas recirculation valve operated by negative pressure in the intake passage in the exhaust gas recirculation passage to recirculate part of the exhaust gas into the intake passage, and an exhaust gas recirculation device that is connected to the breaker plate of the distributor. The vacuum advance device has a negative pressure chamber that is activated by negative pressure in the intake passage downstream of the throttle valve to advance the angle, and A first control valve for controlling the supply of pressure is provided, and a negative pressure for operating the exhaust gas recirculation device is provided upstream of the throttle valve of the carburetor at its minimum opening, and downstream thereof at a predetermined opening or more. and communicates with a second control valve that controls the negative pressure to escape to the atmosphere, and operates the first and second control valves according to pressure fluctuations in the exhaust pipe of the engine, An ignition timing control device for an internal combustion engine, characterized in that the amount of advance by the vacuum advance device increases as the load on the engine increases.