JPS6131299B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas recirculation device for an internal combustion engine such as an automobile, and more particularly to an improved back pressure controlled exhaust gas recirculation device.

A back pressure controlled exhaust gas recirculation device, which is known as one type of exhaust gas recirculation device for internal combustion engines, is installed in the middle of a recirculation exhaust gas passage and responds to the increase in negative pressure acting on its diaphragm chamber. an exhaust gas recirculation control valve that operates to increase its opening amount;
an intake pipe negative pressure outlet port located upstream of the throttle valve in the fully closed position and located downstream of the throttle valve when the throttle valve is opened to a predetermined opening degree or more;
A so-called EGR port and a negative pressure provided in the middle of a conduit connecting the intake pipe negative pressure take-out port to the diaphragm chamber of the exhaust gas recirculation control valve and adjusting the intake pipe negative pressure in the conduit according to exhaust. The exhaust gas recirculation control valve is operated by the negative pressure adjusted according to the discharge by the negative pressure adjustment valve, thereby adjusting the amount of exhaust gas recirculation relative to the amount of intake air. The exhaust gas is recirculated by keeping the exhaust gas recirculation rate constant.

However, in this type of exhaust gas recirculation device, the exhaust gas recirculation control valve is operated by negative pressure adjusted according to the exhaust pressure, so the exhaust gas recirculation control valve is operated in response to changes in the amount of intake air. Before the flow rate changes, there is a time lag between intake air being sent into the engine's cylinders, becoming exhaust gas, and the pressure of that exhaust gas reaching the negative pressure regulating valve, resulting in acceleration or deceleration. During transient operations such as this, the exhaust gas recirculation amount has a considerable delay in following changes in the intake air amount. In addition, in this type of exhaust gas recirculation device, since a restriction is usually provided in the middle of the conduit, it takes time for changes in the intake pipe negative pressure to be transmitted to the diaphragm of the exhaust gas recirculation control valve. There is a delay, which also causes a delay in the response of the exhaust gas recirculation control during transient operation. This response delay is not a problem when accelerating, but when decelerating,
This becomes a problem especially during sudden deceleration. That is, in this case,
Although momentary, high exhaust pressure still acts on the negative pressure regulating valve even though the amount of intake air has been reduced, and during that time, the amount of exhaust gas corresponding to the amount of intake air before deceleration is recirculated, resulting in unused air. If necessary, excessive exhaust gas recirculation takes place, so that the internal combustion engine misfires, and in the next moment the exhaust pressure acting on the negative pressure regulating valve decreases, and the exhaust gas recirculation amount decreases accordingly or reaches zero. As the internal combustion engine starts to burn normally again, the car vibrates back and forth, impairing drivability. This phenomenon becomes more noticeable as the amount of exhaust gas recirculation increases, and depending on the characteristics of the internal combustion engine itself, it may occur more intensely when the throttle valve is closed to the idling opening (fully closed position). This may occur violently when the throttle valve is closed to a low-load operation opening close to the idling opening.

In view of the above-mentioned drawbacks of conventional back pressure controlled exhaust gas recirculation devices, the present invention quickly stops exhaust gas recirculation during deceleration to prevent deterioration of drive quality due to a delay in exhaust gas recirculation. It is an object of the present invention to provide an improved backpressure controlled exhaust gas recirculation device that avoids.

According to the present invention, this purpose is achieved by providing an exhaust gas recirculation control valve that is provided in the middle of the recirculation exhaust gas passage and operates to increase the opening amount in response to an increase in the negative pressure acting on the first diaphragm chamber. a conduit that guides negative pressure to the first diaphragm chamber of the exhaust gas recirculation control valve when the throttle opening is above a predetermined value except during idle operation; A negative pressure regulating valve that adjusts negative pressure according to exhaust pressure, and a valve port for opening and closing the atmosphere opening provided directly on a wall member defining the first diaphragm chamber of the exhaust gas recirculation control valve. It has a valve element, and when negative pressure in the intake pipe is introduced into the second diaphragm chamber, and when a negative pressure equal to or higher than a predetermined value corresponding to the time of deceleration is introduced into the second diaphragm chamber, the valve opens and the second diaphragm chamber is opened. This is achieved by an exhaust gas recirculation device characterized by having a negative pressure control valve that closes when a negative pressure of a predetermined value or higher is not introduced.

According to this configuration, during deceleration, the first diaphragm chamber of the exhaust gas recirculation control valve is opened to the atmosphere by the negative pressure control valve, and at this time, the first diaphragm chamber is opened to the atmosphere. A valve port for opening to the atmosphere is provided in a wall member defining the first diaphragm chamber, so that the first diaphragm chamber is directly opened to the atmosphere,
As a result, atmospheric air is quickly introduced into the first diaphragm chamber without any substantial response delay, and even if the back pressure control system has a response delay, the exhaust gas recirculation control valve closes immediately. , exhaust gas recirculation is quickly stopped. This reliably prevents exhaust gas recirculation from being performed at an excessive flow rate even temporarily during deceleration due to a response delay of the back pressure control system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings.

The attached FIG. 1 is a schematic diagram showing one embodiment of an exhaust gas recirculation device according to the present invention.

The exhaust gas recirculation control valve 1 has a valve casing 4 with an exhaust gas inlet port 2 and an exhaust gas outlet port 3, which are supplied with a portion of the exhaust gas flowing through the exhaust system, not shown in the figure. The exhaust gas outlet port 3 is connected via a conduit 5 to an intake passage 6 for recirculating exhaust gas from the exhaust system into the intake passage 6. A valve port 8 is defined between the exhaust gas inlet port 2 and the exhaust gas outlet port 3 of the valve casing 4 by a valve seat element 7, and the valve port 8 is co-located with the valve seat 7. It is adapted to be opened and closed by a working valve element 9.
Valve element 9 is carried by a valve rod 10 which is connected to and is driven by a diaphragm 11. Diaphragm 11 is diaphragm cover 1
2 to define a first diaphragm chamber 13 on the upper side in the figure, and a compression coil spring 1 provided in the diaphragm chamber.
4 is flexibly biased toward the valve seat element 7, that is, toward the valve closing direction. The diaphragm chamber 13 is located upstream of the throttle valve 16 provided in the intake passage 6 when the throttle valve 16 is in the fully closed position, and is located downstream of the throttle valve 16 when the throttle valve 16 is opened to a predetermined opening or more. The intake pipe negative pressure outlet port 17 is preferably opened into the intake passage 6 through a conduit 18.

Further, a negative pressure control valve 19 for selectively opening the diaphragm chamber 13 to the atmosphere is integrally provided on the upper part of the diaphragm cover 12. The negative pressure control valve 19 is connected to the diaphragm cover 1.
It has a casing assembly 20 secured to 2 and includes a diaphragm 21 within the casing assembly 20. The diaphragm 21 cooperates with a casing 20a to define a second diaphragm chamber 22 on its upper side, and defines an atmosphere open chamber 2 on its lower side in cooperation with a casing 20b.
3 has been determined. The atmosphere open chamber 23 is opened to the atmosphere through an air filter 24 and an atmosphere port 25 provided in the casing 20b. Said diaphragm 21 carries in its central part a valve element 26 which is mounted on said diaphragm cover 12 and is connected to said diaphragm chamber 13.
A valve port 27 for opening to the atmosphere is selectively opened and closed. The valve element 26 is moved downward in the figure by a compression coil spring 29 provided between the valve element 26 and the spring receiving element 30, that is, in the direction in which it seats on the valve seat 28 defined on the periphery of the valve port 27. The diaphragm chamber 22
The valve is configured to sit on the valve seat portion 28 and close the valve port 27 unless a large negative pressure equal to or higher than a predetermined value corresponding to deceleration is introduced into the valve seat 28 . The spring receiving element 30 is connected to the casing 20a via an adjusting screw element 31, and the initial setting pressure of the compression coil spring 29 is adjusted by the screwing amount of the adjusting screw element 31.
Further, the diaphragm chamber 22 is connected to an intake pipe negative pressure outlet port 33 through a conduit 32, and the negative pressure appearing at this port is introduced. In this case, the intake pipe negative pressure outlet port 3
3 is located on the downstream side of the throttle valve in the fully closed position, and is located on the upstream side of the throttle valve 16 when it is opened beyond a predetermined opening degree. Note that this intake pipe negative pressure extraction port is not limited to this, and may be provided so as to be always located on the downstream side of the throttle valve 16.

A negative pressure regulating valve 34 is incorporated in the middle of the conduit 18 for selectively introducing the conduit into the conduit to appropriately reduce and adjust the intake pipe negative pressure within the conduit. This negative pressure regulating valve 34 works together with a casing 35 to form a diaphragm 39 that defines an atmosphere open chamber 37 communicating with the atmosphere via an air filter 36 on the upper side and a diaphragm chamber 38 on the lower side in the figure. , a valve port 40 that is communicatively connected in the middle of the conduit 18 and opens toward the upper surface of the diaphragm 39 , and a valve port 40 that is attached to the diaphragm 39
0, the valve element 41 opens and closes the valve port 40, and a compression coil spring 42 flexibly urges the diaphragm 39 downward in the figure. The valve element 41 of the pressure regulating valve 34 is in the position shown to open the valve port 40 when the pressure within the diaphragm chamber 38 is approximately atmospheric; When the pressure is higher than atmospheric pressure, it is displaced upward in the figure to close the valve port 40. The diaphragm chamber 38 is connected to the valve seat element 7 of the exhaust gas recirculation control valve 1 and from this to the exhaust gas inlet port 2.
The pressure chamber 15 is connected via a conduit 44 to a pressure chamber 15 defined between the orifice element 43 provided on the side thereof, and the pressure within this pressure chamber 15 is introduced. Further, a throttle element 45 is provided in the middle of the conduit 18 on the side closer to the intake pipe negative pressure outlet port 17 than the valve port 40 .

The exhaust gas recirculation device constructed as described above operates as follows. When the throttle valve 16 is not opened beyond the intake pipe negative pressure takeout port 17, that is, during idling, the intake pipe negative pressure does not act on the intake pipe negative pressure takeout port 17, and the intake pipe negative pressure is substantially increased. Air pressure is present, so the exhaust gas recirculation control valve 1 is in the closed state and the exhaust gas recirculation is stopped. When the throttle valve 16 is opened beyond the intake pipe vacuum outlet port 17 as shown, substantial intake pipe vacuum appears at that port 17, and that intake pipe vacuum passes through the conduit 18 and The exhaust gas is adjusted to be reduced in pressure by the pressure control valve 34 and introduced into the diaphragm chamber 13 of the exhaust gas recirculation control valve 1, thereby opening the exhaust gas recirculation control valve 1 and recirculating the exhaust gas. It becomes like this. In this case, if the pressure of the exhaust gas in the pressure chamber 15 of the exhaust gas recirculation control valve 1 is lower than the valve closing setting pressure of the negative pressure regulating valve 34, the negative pressure regulating valve 3
The pressure in the diaphragm chamber 38 of No. 4 is also low, and the valve element 41 is in the position shown in the figure, opening the valve port 40, so that the intake pipe negative pressure outlet port 1
The negative pressure appearing at 7 is largely released into the atmosphere and is removed from the diaphragm chamber 1 of the exhaust gas recirculation control valve 1.
3 becomes smaller, so that the valve element 9 of the exhaust gas recirculation control valve 1 is displaced toward the valve seat element 7 by the action of the compression coil spring 14, and the passage cross-sectional area of the valve port 8 is reduced. decrease or close it. As a result, when the pressure of the exhaust gas in the pressure chamber 15 increases, the pressure in the diaphragm chamber 38 of the negative pressure regulating valve 34 also increases, so the diaphragm 39 is displaced upward in the figure, and the valve element 41
This causes the valve port 40 to close. As a result, the intake pipe negative pressure appearing at the intake pipe negative pressure outlet port 17 is introduced into the diaphragm chamber 13 of the exhaust gas recirculation control valve 1 without being substantially reduced, and the diaphragm 11 is compressed. It is displaced upward in the figure against the action of the coil spring 14, displacing the valve element 9 in a direction away from the valve seat element 7, and increasing the passage cross-sectional area of the valve port 8. Then, the pressure of the exhaust gas within the pressure chamber 15 begins to decrease again. Thereafter, by repeating the above-described operations, the pressure within the pressure chamber 15 is maintained at the closing set pressure of the negative pressure regulating valve 34, that is, approximately atmospheric pressure.

Since the flow rate of the exhaust gas flowing through the exhaust gas recirculation control valve 1 is the same everywhere, it can be represented by the orifice element 43, and the pressure downstream of the orifice element is approximately constant near atmospheric pressure. Therefore, the recirculation amount of exhaust gas is determined by the exhaust pressure and the passage cross-sectional area of the orifice element 43. The flow rate of exhaust gas flowing through the exhaust pipe is approximately proportional to the amount of intake air, and the exhaust pressure changes in response to the flow rate of exhaust air. Therefore, the amount of recirculation of exhaust gas changes almost in proportion to the amount of intake air, and the orifice element 4
Once the effective cross-sectional area of the passage No. 3 is determined, the proportionality coefficient of the reflux amount, that is, the reflux rate is determined.

Furthermore, during idling operation, during acceleration operation when the throttle valve 16 is opened, or during steady operation, a large intake pipe negative pressure corresponding to that during deceleration does not act on the intake pipe negative pressure outlet port 33. Therefore, the negative pressure control valve 19 maintains the closed state as shown in the figure, and the diaphragm chamber 13 of the exhaust gas recirculation control valve 1 is not opened to the atmosphere.

In order to perform deceleration, when the throttle valve 16 is rapidly closed from the load operating opening as shown in the figure, it passes over the intake pipe negative pressure take-out port 33, and the intake passage 6
The amount of intake air flowing therein suddenly decreases, and a large negative pressure that is not seen during steady operation comes to act on the intake pipe negative pressure outlet port 33. This negative pressure is passed through the conduit 32 to the diaphragm chamber 22 of the negative pressure control valve 19.
immediately inwards, displacing the diaphragm 21 upwardly in the figure, pulling the valve element 26 away from the valve seat 28 and opening the valve port 27. As a result, the diaphragm chamber 13 of the exhaust gas recirculation control valve 1 is directly opened to the atmosphere via the atmosphere opening chamber 23 of the negative pressure control valve 19, the air filter 24, and the atmosphere port 25, and the inside of the diaphragm chamber 13 is immediately opened. Atmosphere is introduced. The valve element 9 of the exhaust gas recirculation control valve 1 therefore immediately seats on the valve seat element 7, closing the valve port 8 and quickly stopping the exhaust gas recirculation. As a result, even if there is a response delay in the back pressure control system, exhaust gas recirculation is immediately stopped during deceleration.
In this case, it is reliably avoided that the exhaust gas recirculation occurs even temporarily at an excessive flow rate. Large negative pressure during deceleration will cause
As the rotational speed of the internal combustion engine decreases, the pressure decreases to a value lower than the opening set pressure of the negative pressure control valve 19, so the negative pressure control valve 19 closes after a predetermined time has elapsed after deceleration. The valve port 27 is closed to isolate the diaphragm chamber 13 of the exhaust gas recirculation control valve 1 from the atmospheric port 25 and to allow exhaust gas recirculation.

In the case of this embodiment, when the throttle valve is opened to a predetermined opening degree or more, the intake pipe negative pressure outlet port 33 is located on the upstream side of the throttle valve and is substantially exposed to atmospheric pressure. The negative pressure control valve 19 closes at the same time, allowing the exhaust gas to be recirculated. In this case, the opening degree at which the throttle valve crosses the intake pipe negative pressure takeout port 33 may be smaller or larger than the opening degree at which the throttle valve crosses the intake pipe negative pressure takeout port (EGR port) 17. It may be equal to the opening degree.

As is clear from the above description, according to the exhaust gas recirculation device according to the present invention, the diaphragm chamber of the exhaust gas recirculation control valve is directly opened to the atmosphere during deceleration, and the atmosphere is quickly introduced into the diaphragm chamber. , it will be appreciated that exhaust gas recirculation is quickly stopped substantially simultaneously with deceleration.

[Brief explanation of the drawing]

The attached figure is a schematic diagram showing one embodiment of an exhaust gas recirculation device according to the present invention. 1 - exhaust gas recirculation control valve, 2 - exhaust gas inlet port, 3 - exhaust gas outlet port, 4 - valve casing, 5 - conduit, 6 - intake passage, 7 - valve seat element,
8-valve port, 9-valve element, 10-valve rod, 1
1 - diaphragm, 12 - diaphragm cover,
13 - diaphragm chamber, 14 - compression coil spring,
15~pressure chamber, 16~throttle valve, 17~
Intake pipe negative pressure extraction port, 18 - conduit, 19 - negative pressure control valve, 20 - casing assembly, 21 - diaphragm, 22 - diaphragm chamber, 23 - atmospheric release chamber, 24 - air filter, 25 - atmospheric port,
26 - valve element, 27 - valve port, 28 - valve seat,
29 ~ Compression coil spring, 30 ~ Spring receiving element, 31 ~
Adjustment screw element, 32 - Conduit, 33 - Intake pipe negative pressure outlet port, 34 - Negative pressure adjustment valve, 35 - Casing, 36 - Air filter, 37 - Atmospheric release chamber, 3
8 ~ diaphragm chamber, 39 ~ diaphragm, 40
~valve port, 41~valve element, 42~compression coil spring, 43~orifice element, 44~conduit, 45~
aperture element.

Claims (1)

[Claims] 1 An exhaust gas recirculation control valve that is installed in the middle of the recirculation exhaust gas passage and operates to increase the amount of valve opening in response to an increase in the negative pressure acting on the first diaphragm chamber, and an exhaust gas recirculation control valve that is installed in the middle of the recirculation exhaust gas passage and operates to increase the opening amount in response to an increase in the negative pressure acting on the first diaphragm chamber. a conduit that conducts negative pressure to the first diaphragm chamber of the exhaust gas recirculation control valve when the temperature is above a predetermined value;
a negative pressure regulating valve provided in the middle of the conduit and adjusting the negative pressure in the conduit according to exhaust pressure; and a negative pressure regulating valve provided directly on a wall member defining the first diaphragm chamber of the exhaust gas recirculation control valve. It has a valve element that opens and closes a valve port for opening to the atmosphere, and a negative pressure in the intake pipe is introduced into the second diaphragm chamber, and a negative pressure equal to or higher than a predetermined value corresponding to the time of deceleration is introduced into the second diaphragm chamber. An exhaust gas recirculation device comprising: a negative pressure control valve that is opened at times and closed when a negative pressure of a predetermined value or higher is not introduced into the second diaphragm chamber.