JPS6016763Y2 - Exhaust recirculation amount control device - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an exhaust gas recirculation amount control device for an internal combustion engine.

Various types of exhaust gas recirculation amount control devices are known that control the amount of exhaust gas recirculation (EGR) in an internal combustion engine using engine parameters, and in this case, intake negative pressure is usually used as the engine parameter.

FIG. 1 shows a part of an internal combustion engine equipped with such a conventional exhaust gas recirculation amount control device.

In this figure, an intake manifold 2 is attached to an engine body 1, and an intake pipe 4 having a venturi 3 constituting a part of a carburetor communicates with the intake manifold 2.

The intake pipe 4 communicates with the atmosphere via an air cleaner 5.

A throttle valve 6 is provided downstream of the venturi 3.

A recirculation passage 8 that communicates with the exhaust system via a control valve 7 communicates with the intake manifold 2 .

The control valve 7 includes a valve body 9, a rod 11 that compresses the valve body 9 and a diaphragm 10, and a back spring 12 that biases the diaphragm 10, and is controlled by suction negative pressure supplied through a passage 13. Ru.

The passage 13 opens slightly upstream of the throttle valve 6, and is configured so that negative pressure is not supplied to the control valve 7 during idling.

The exhaust gas recirculation amount control device having the above-mentioned configuration has the disadvantage that the amount of exhaust recirculation that is required depending on the load condition of the internal combustion engine cannot necessarily be obtained because the amount of exhaust gas recirculation is controlled only by the suction negative pressure. are doing.

Further, since the ignition angle is similarly advanced by the suction negative pressure, under certain conditions, the ignition angle may not be advanced enough even though the amount of exhaust gas recirculation is large due to the suction negative pressure characteristics, which may impair drivability.

Furthermore, if the traveling distance becomes long, carbon may adhere to the control valve 7, and as a result, there is a possibility that the desired recirculation amount may not be obtained.

Therefore, an object of the present invention is to provide an exhaust gas recirculation amount control device that eliminates the above-mentioned drawbacks.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a cross-sectional view of an embodiment of the exhaust gas recirculation amount control device according to the present invention, and parts equivalent to those in FIG. 1 are designated by the same reference numerals.

In the figure, a control valve 7 is provided in a recirculation passage 8 that communicates the intake manifold with the exhaust system.

The control valve 7 includes a valve body 9, a rod 11 that connects a diaphragm 10 provided in a housing 14 and the valve body 9, and a back spring 12 that biases the diaphragm 10 in the direction of the valve body 9.
It is composed of.

The housing 14 includes an atmospheric chamber 16 that communicates with the atmosphere through a hole 15 through the diaphragm 10, an atmospheric pressure introduction passage 17 that opens to the atmosphere, and at least two negative pressure introduction passages 18 that open to the intake manifold of the internal combustion engine. control room 20 having 19;
The control valve 7 that controls the amount of exhaust gas recirculated and the negative pressure control section that drives the control valve are integrated.

One of the two negative pressure introduction paths, for example, the negative pressure introduction path 19, is connected to a solenoid 21, a leaf spring 22 that is activated by energizing or de-energizing the solenoid 21, and a rubber member 23 fixed to the tip of the leaf spring 22. It is opened and closed by a solenoid valve.

The solenoid 21 is controlled to be turned on and off according to the pulse width from the control unit 24.

This control unit 24 controls the solenoid 21 according to the EGR rate from the EGR rate indicating means 25 that corresponds to the negative state of the engine.
Determine the pulse width, or duty factor, of the pulse to be supplied to the

In addition, orifices 26, 27, 28 are provided in the atmosphere introduction path 17 and the negative pressure introduction paths 18, 19, respectively.
If the diameter of the orifice is appropriately selected, the internal pressure of the control chamber 20 can be kept almost constant even if the suction negative pressure fluctuates as long as the duty factor is constant, as shown in FIG. 3a.

However, if the orifice is improperly selected, even if the duty factor is the same, the internal pressure in the control chamber 20 will also change greatly due to a change in the suction negative pressure, resulting in changes in response, etc., as shown in Figure 3. adversely affect characteristics.

In addition, since exhaust gas recirculation is required in a high load region, the suction negative pressure must be used at a low value, for example, suction negative pressure 1
A maximum flow rate of about 100 rranH is required.

Therefore, the lift characteristic of the control valve 7 is, for example, 50 mmH.
Since it is used in a very narrow range of rising at 100 rrvn Hg and full lift at 100 rrvn Hg, the range of the duty factor used for control is narrow and the resolution ability is reduced in the characteristics shown in FIG.

Therefore, when the duty factor is 100%, the internal pressure of the control chamber 20 is always kept at -5o by the balance between the orifices 26 and 27.
By controlling the flow rate passing through the orifice 28 and setting it to -100=Hg when the duty factor is 0%, the duty factor used for control is set to rMtHg as shown in Figure 3a.
The range of factors can be widened.

In addition, since the control range of negative pressure is between -5-Hg and 1100 mm, two negative pressure introduction paths are provided, and negative pressure (for example, -20rrrmHg) is supplied to the control room 2 from one of the introduction paths 18.
0 and the opening/closing of the other introduction passage 19 is controlled on/off by the solenoid 21, the negative pressure introduction passage becomes 1.
In the case of a book, it is controlled between 0 and -10077aHg, whereas in the case of two books according to the present invention, it is controlled between -20 and -100mmH.
Since the distance between g is controlled, more accurate control can be achieved.

Furthermore, as shown in FIG. 4a, the flow rate of the air passing through the orifice remains constant even if the pressure difference increases since the flow velocity becomes sonic when the pressure difference across the orifice reaches around 350 mmHg or higher.

On the other hand, in the case of a sonic orifice, as shown in FIG. 4, when the differential pressure reaches 10077EllIH, the flow rate passing through becomes constant as described above.

Therefore, by providing sonic orifices in the negative pressure introduction paths 18 and 19, the internal pressure of the control chamber 20 is controlled only by the duty factor without being affected by fluctuations in the suction negative pressure, as shown in FIG. 3a. .

In this way, by controlling the solenoid 21 on and off in accordance with the duty factor determined by the control unit 24 to open and close the negative pressure introduction path 19, the internal pressure of the control room can be controlled within the range of, for example, -50 to -100m+nHg. Change.

Therefore, the opening degree of the control valve 7 is determined by the balance between the internal pressure of the control chamber 20, that is, the control pressure, and the spring pressure of the back spring 12, and the EGR amount is determined according to the EGR rate from the EGR rate indicating means 25.

The control unit 24 controls the EG according to the load condition of the internal combustion engine.
The duty factor to the solenoid 21 continues to be controlled until the R amount is obtained.

As described in detail above, according to the exhaust gas recirculation amount control device according to the present invention, the exhaust recirculation control valve and the load control section are integrally configured. It saves the trouble of piping between the pressure control section and can be configured compactly, reducing costs.
Furthermore, the required EGR amount according to the engine load condition can be obtained reliably, and if the desired recirculation amount, that is, the duty factor, is controlled by exhaust pressure, it will not be affected even if carbon adheres to the control valve 7. The desired reflux amount can be obtained without any

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of an internal combustion engine equipped with a conventional exhaust gas recirculation amount control device, FIG. 2 is a cross-sectional view of an embodiment of the exhaust gas recirculation amount control device according to the present invention, and FIG. The control pressure diagram of the control chamber in the figure, and FIG. 4 are flow rate characteristic diagrams passing through the orifice and sonic orifice in FIG. 2. Explanation of symbols of main parts, 7...Control valve, 10.
...Diaphragm, 17...Atmospheric pressure introduction path, 18°19...Negative pressure introduction path, 20...
...Control room, 21... Solenoid, 26...
... Orifice, 27, 28 ... Sonic orifice.

Claims (2)

[Scope of utility model registration request] (1) A control valve provided in an exhaust gas recirculation passage of an internal combustion engine,
An exhaust gas recirculation amount control device comprising a control chamber formed by a casing including a diaphragm connected to the control valve, and a control means for controlling the internal pressure of the control chamber, the control means controlling the internal pressure of the control chamber. an atmospheric pressure introduction passage that communicates with the atmosphere, at least two negative pressure introduction passages that communicate the control chamber with the intake manifold of the internal combustion engine, a solenoid valve that opens and closes one of the negative pressure introduction passages; The exhaust return comprises a control unit that controls on/off of a valve depending on the load state of the internal combustion engine, and an orifice is provided in the atmospheric pressure introduction path, and a sonic orifice is provided in the negative pressure introduction path. Flow control device. (2) The exhaust gas recirculation amount control device according to claim 1, wherein the solenoid valve is integrally attached to the housing.