JP2000045879A - Egr device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the transient responsiveness of EGR control. SOLUTION: An EGR gas introduction part 21 is formed in each of branch pipes 15a of an intake manifold 15. These parts 21 are connected to an exhaust passage 12 of an engine by means of an EGR manifold 22 in which the EGR rate is controlled by EGR valves 24 respectively arranged in the introduction parts. Each of the EGR valves 24 is composed a valve plate 24a, and a rotary shaft 24b supporting the valve plate at one side of the latter which is therefore rotatable in opening and closing directions. With this arrangement, it is set so that the passage area of the introduction part 21 and that of the branch pipe 15a are changed in an inverse proportional manner on the branch pipe 15a side of the valve plate 24a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an EGR for an engine.
Related to the device.

[0002]

2. Description of the Related Art As a countermeasure against NOx of an engine, an EGR device for recirculating a part of exhaust gas to an intake side is well known (Japanese Patent Application Laid-Open No. Hei 7-16673). Such EGR
The apparatus includes an EGR passage that connects an exhaust passage and an intake passage of the engine, and an EGR valve that controls an EGR rate of the EGR passage. Then, the flow rate of the EGR gas is controlled in accordance with the opening degree of the EGR valve, and the EGR gas flows into the intake passage and is supplied to each cylinder together with fresh air through the intake manifold.

[0003]

In such a conventional structure, a considerable time delay (time lag) occurs between the time when the EGR valve is opened and the time when the EGR gas reaches the cylinder. There was a problem that the response of the control was not good. Further, since the EGR gas is distributed to each cylinder through the intake manifold together with fresh air, the EGR rate between cylinders tends to vary.

An object of the present invention is to provide an effective countermeasure for remedying such a problem.

[0005]

According to a first aspect of the present invention, in an EGR apparatus for recirculating a part of exhaust gas to an intake side of an engine, an exhaust gas recirculation gas introduction portion is formed in each branch pipe of an intake manifold. And an EGR manifold for connecting an introduction portion of the EGR to an exhaust passage of the engine, and an EGR valve for controlling an exhaust gas recirculation rate.

In the second invention, the EG according to the first invention is used.
One R valve is provided for each introduction part.

In the third invention, each E in the second invention is used.
The GR valve is composed of a valve plate and a rotating shaft that rotatably supports the valve plate on one side thereof in an opening and closing direction. Is set to open and close the passage area in inverse proportion.

In a fourth aspect, the EG according to the third aspect is provided.
The R valve is set so that the valve plate is rotatable toward the EGR manifold side, and only the passage area of the introduction portion is opened and closed according to the rotation angle on the EGR manifold side.

According to a fifth aspect of the present invention, the rotation axes of the respective EGR valves in the third aspect are coaxially connected, and an actuator for opening and closing the valves is connected to these rotation axes.

In the sixth invention, each E in the third invention is used.
The rotation axis of the GR valve is arranged so as to support one side of the valve plate on the upstream side of the intake so as to be freely rotatable in the opening and closing direction.

According to a seventh aspect of the present invention, there is provided an EGR device including an EGR passage for returning a part of exhaust gas to an intake passage of an engine, and an EGR valve for controlling an exhaust gas recirculation rate.
An EGR valve is provided with a valve plate and a rotating shaft that supports the valve plate on one side thereof so as to be freely rotatable in the opening and closing direction. When the valve plate is rotated toward the intake passage, the EGR passage is opened and closed according to the rotation angle. The intake passage is set to open and close in inverse proportion.

[0012]

According to the first aspect of the present invention, when the EGR valve is opened, the EGR gas flows into the branch pipe from each introduction portion and is supplied to the cylinder together with fresh air. Therefore, the EG from the EGR valve is reduced by the amount not passing through the collecting portion of the intake manifold.
Time lag (time delay) until R gas reaches cylinder
, The response of the EGR control at the time of transition can be improved. In addition, by introducing the EGR gas to each branch pipe, the variation in the EGR rate between the cylinders can be suppressed to be small.

In the second aspect, the length of the passage from the EGR valve to the cylinder is also shortened, and the responsiveness of the EGR control during a transient can be greatly improved.

In the third aspect, the passage area of the introduction portion and the passage area of the branch pipe are controlled in inverse proportion to the opening and closing of the EGR valve. Since the EGR valve also functions as an intake throttle valve, valve matching and control thereof are easier than when an intake throttle valve is provided separately from the EGR valve.

In the fourth aspect, the EGR valve opens and closes the introduction portion on the EGR manifold side, so that it is possible to cope with an engine operating state in which only the amount of introduced EGR gas (EGR rate) is controlled without restricting fresh air. Will be possible.

In the fifth invention, each EGR valve can be opened and closed synchronously by one actuator.

In the sixth aspect of the invention, when the EGR valve is opened, the valve plate blocks the flow of intake air (fresh air) around the rotation shaft and rotates the EGR gas to guide the EGR gas to the downstream branch pipe. Therefore, the introduction of the EGR gas can be easily and stably controlled in accordance with the opening degree of the valve plate.

In the seventh aspect, the opening of the EGR passage and the opening of the intake passage are inversely controlled by opening and closing the EGR valve in accordance with the rotation angle of the valve body. Since the EGR valve also functions as an intake throttle valve, valve matching and control thereof are easier than when an intake throttle valve is provided separately from the EGR valve.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 10 denotes a diesel engine, a supercharger 13 (in this example, a turbocharger) for generating a supercharging pressure in an intake passage 11, and cooling of the supercharged air. An intercooler 14 is provided. 1
5 is an intake manifold, 16 is an exhaust manifold, and these are branch pipes (branches) corresponding to each cylinder.
15a, 16a and these collecting parts 15b, 16b are formed, and are connected to the ports 17, 18 on the wall surface of the cylinder head 10a through the mounting parts of the branch pipes 15a, 16a. Reference numeral 19 denotes an intake valve that opens and closes a valve seat of an intake port 17, and reference numeral 20 denotes an exhaust valve that opens and closes a valve seat of an exhaust port 18.

In this case, each branch pipe 15a of the intake manifold 15 is formed in a rectangular hollow cross section, and an EGR gas introduction portion 21 is opened in a rectangular shape on each of the upper surfaces thereof. EG connecting each introduction portion 21 with the exhaust passage 12 of the engine
An R manifold 22 is provided, and a downstream side thereof is formed in a collecting portion 23a that straddles the branch pipe 15a of the intake manifold 15. The collecting part 23 is opened to each of the introduction parts 21, and an EGR cooler 26 for cooling the EGR gas is interposed at a merging part 23 b on the upstream side thereof.

E is inserted one by one into the inlet 21 of each branch pipe 15a.
A GR valve 24 is provided. The EGR valve 24 is a valve plate 24 that opens and closes a rectangular opening (valve opening area) of the introduction section 21.
a and a rotating shaft 24b connected to one side thereof. As shown in FIG. 2, the valve seat 25 of the valve plate 24a is formed on the inner surface of the branch pipe 15a. When the rotation shaft 24b rotates in the direction of the arrow from the closed position where the valve plate 24a is seated on the valve seat 25, the branch pipe 15a is closed. While reducing the passage area,
It is assembled so that the introduction section 21 is opened (the passage area of the introduction section 21 is increased).

The rotating shaft 24b of the EGR valve 24 is disposed so as to freely support one side of the valve plate 24a in the opening and closing direction on the upstream side of the intake air. As a result, the valve plate 24a blocks the flow of fresh air around the rotation shaft 24b on the upstream side,
Since the valve is opened so as to guide the EGR gas to the branch pipe 15a on the downstream side, the introduction of the EGR gas can be easily and stably controlled in accordance with the opening degree of the valve plate 24a. Note that the valve seat 25 has a receiving recess of the valve plate 24a so that a step that causes intake resistance does not occur on the inner surface of the branch pipe 15a when the valve plate 24a is in the closed position.

The rotary shaft 24b of each valve plate 24a is coaxially connected, and one end thereof is connected to a step motor 27 as an actuator for opening and closing the EGR valve 24. 28
Denotes an EGR control, which controls the step motor 27 so as to obtain an EGR rate according to detection signals (engine speed, accelerator opening, cooling water temperature, etc.) of various sensors 29 for detecting an engine operating state.

With such a configuration, the EGR valve 24
Is closed, the EGR gas is retained in the EGR manifold 23 on the upstream side. When the EGR valve 24 is opened, the EGR gas flows from the introduction section 21 into the branch pipe 15a, and is supplied to the cylinder together with the supercharged air (fresh air). That is, since the gas does not pass through the collecting portion of the intake manifold 15, a time lag (time delay) from when the EGR gas reaches the cylinder through the EGR valve 24 is reduced. Also, E
By arranging one EGR valve 24 at each introduction section instead of the merging section 23b of the GR manifold 23,
Since the length of the passage from the GR valve 24 to the cylinder is also reduced, the transient response of the EGR control can be greatly improved.

The EGR valve 24 is a driving mechanism in which these rotary shafts 24b are coaxially connected and a step motor 27 is connected to one end of the EGR valve 24. By controlling one step motor, the EGR valves 24 are synchronized. Can be opened and closed. Introducing section 2 with opening and closing of EGR valve 24
Since the passage area of No. 1 and the passage area of the branch pipe 15a are inversely controlled, and the EGR valve 24 also functions as an intake throttle valve, introduction of EGR gas downstream of the turbocharger 13 becomes easy. Further, compared with a case where an intake throttle valve is provided separately from the EGR valve 24, valve matching and control thereof can be achieved easily and easily.

The EGR gas is distributed to each branch pipe 15a through the EGR manifold 22, and is not distributed to each cylinder together with fresh air through the intake manifold.
Variations in the EGR rate between cylinders can also be suppressed.
The valve opening area of each inlet 21 is determined for each branch pipe (EGR
By setting differently (in accordance with the opening position of the introduction portion 21 in the manifold 23), it is possible to further reduce the variation in the EGR rate between the cylinders.

With respect to the EGR manifold 23, when a cooling jacket is formed in the collecting portion 23a, heat damage of the EGR gas is prevented, and the effect of improving the reliability and durability of the EGR valve 24 is obtained. When the valve plate 24a is set to be rotatable also toward the EGR manifold 22 as shown in FIG. 3, only the passage area of the introduction portion 21 is opened and closed according to the rotation angle on the EGR manifold 22 side. Therefore, it is possible to cope with an engine operating state in which EGR gas is to be introduced without restricting fresh air. This device can be applied to a non-supercharged engine in the same manner as in the above embodiment in order to enhance the transient response of the EGR control.

Regarding the EGR valve 24, the conventional EG
R device (E which recirculates part of exhaust gas to the intake passage of the engine
In the case where a GR passage and an EGR valve for controlling the exhaust gas recirculation rate are provided), it may be provided at a junction of the EGR passage and the intake passage. In that case, the EGR valve 24
Although not shown in the drawings, the valve plate includes a valve plate and a rotation shaft that rotatably supports the valve plate on one side thereof in the opening and closing direction. When the valve plate rotates toward the intake passage, the EGR passage is formed in accordance with the rotation angle. And the intake passage is opened and closed in inverse proportion.

As a result, the EGR valve 24 also functions as an intake throttle valve in the same manner as described above.
Therefore, there is no need to provide an intake throttle valve separately from the intake throttle valve 4, and the effect that the matching of the valve and the control thereof are easy is obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of the present invention.

FIG. 2 is an explanatory view of an EGR valve.

FIG. 3 is an explanatory view of an EGR valve.

[Explanation of symbols]

 Reference Signs List 10 diesel engine 15 intake manifold 15a branch pipe 15b collecting part 21 introduction part 22 EGR manifold 24 EGR valve 24a valve plate 24b rotation axis 26 EGR cooler

Claims (7)

[Claims] In an EGR system for recirculating a part of exhaust gas to an intake side of an engine, an exhaust gas recirculation gas introduction portion is formed in each branch pipe of an intake manifold, and these introduction portions are connected to an exhaust passage of the engine. An EGR device, comprising: an EGR manifold that performs an exhaust gas recirculation and an EGR valve that controls an exhaust gas recirculation rate. 2. The EGR device according to claim 1, wherein one EGR valve is provided for each introduction portion. 3. Each of the EGR valves comprises a valve plate and a rotating shaft for supporting the valve plate on one side thereof so as to be freely rotatable in an opening and closing direction. The EGR device according to claim 2, wherein the passage area of the branch pipe and the passage area of the branch pipe are set so as to open and close in inverse proportion. 4. Each EGR valve is characterized in that the valve plate is rotatable toward the EGR manifold side, and only the passage area of the introduction portion is opened and closed according to the rotation angle on the EGR manifold side. The EGR device according to claim 3, wherein 5. The EGR device according to claim 3, wherein the rotation shafts of the respective EGR valves are connected coaxially, and an actuator for opening and closing the valves is connected to these rotation shafts. 6. The EGR according to claim 3, wherein the rotation shaft of each EGR valve is disposed so as to support one side of the valve plate on the upstream side of the intake so as to freely rotate in the opening and closing direction. apparatus. 7. An EGR device comprising an EGR passage for recirculating a part of exhaust gas to an intake passage of an engine, and an EGR valve for controlling an exhaust gas recirculation rate. Is provided so that the valve plate is rotated to the intake passage side, so that the EGR passage and the intake passage are opened and closed in inverse proportion according to the rotation angle. The EGR device according to claim 2, wherein: