JP2005180309A - Intake device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize compatibility between securement of high output at the time of full-open performance of an engine and reduction in NOx emission amount by EGR gas injection and improvement of fuel economy at the time other than full-open performance. <P>SOLUTION: This intake device for the internal combustion engine is equipped with an intake passage 2 vertically partitioned by a partition wall 7, EGR piping 11 communicating an exhaust passage of the engine with the intake passage and having an opening part 4 in the upstream side from the partition wall 7 of the intake passage 2, and an on-off valve 3 provided in the vicinity of an upstream side end part of the partition wall 7 and blocking the opening 4 of the EGR piping 11 at the time of full-open performance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a structure of an intake device for an internal combustion engine, and more particularly to an intake device for an internal combustion engine including an exhaust gas recirculation device (EGR device).

  In an internal combustion engine, a method is known in which an EGR device that recirculates exhaust gas to an intake pipe is provided to reduce the combustion temperature in the combustion chamber in order to suppress the amount of NOx generated and improve fuel efficiency.

In order to enhance the above-described effect by the EGR device, it is desirable to distribute exhaust circulation gas (EGR gas) evenly to each cylinder. For example, as disclosed in Patent Document 1, a pipe for EGR gas is branched to A method of injecting EGR gas for each cylinder by connecting to each branch part is known.
JP 2002-89376 A

  However, if the EGR gas pipes are connected to the branch portions of the intake manifold, the EGR gas pipes communicate with each other. In addition, one EGR valve that controls supply / stop of EGR gas is usually provided upstream of the portion where the EGR gas pipe branches.

  Therefore, the volume of each branch portion increases by the amount of the EGR gas pipe downstream from the EGR valve.

  As a result, for example, even if EGR gas injection is stopped during full-open performance, the intake negative pressure in the intake stroke is unlikely to increase as the volume increases, so a large amount of air is filled into the combustion chamber using the inertia of the intake air. There is a problem that the effect of so-called inertia supercharging is reduced and the output is reduced.

  Therefore, an object of the present invention is to obtain a high output during the fully open performance while reducing the NOx emission amount and improving the fuel consumption by EGR gas injection.

  An intake system for an internal combustion engine according to the present invention includes an EGR pipe having an intake passage partitioned vertically by a partition, an exhaust passage and an intake passage of the engine, and an opening upstream of the partition of the intake passage. And an opening / closing valve provided near the upstream end of the partition wall and closing the opening of the EGR pipe when fully opened.

  According to the present invention, when the engine is fully opened, the opening portion of the EGR pipe is closed by the on-off valve, so that the branch portions of the intake manifold are prevented from communicating with each other by the EGR pipe, so that the inertia supercharging effect is reduced. Can be prevented. That is, it is possible to obtain a high output by using the inertia supercharging effect at the time of the full opening performance while injecting EGR gas at times other than the time of the full opening performance to reduce the NOx emission amount and improve the fuel consumption.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 (a) and 1 (b) are cross-sectional views of the intake device of the present embodiment, and FIG. 1 (a) is a medium / high load operation during acceleration (hereinafter referred to as fully open performance), FIG. ) Represents a state during low-load operation (hereinafter referred to as partial operation) such as traveling at a constant speed or low-speed traveling.

  FIG. 2 shows a top view of FIGS. FIG. 2 shows a four-cylinder engine as an example of a multi-cylinder engine.

  1 is a collector tank that temporarily stores air drawn from an intake port (not shown), 2 is a branch part that connects the collector tank 1 and the intake port 5 of each cylinder, and 3 is a control of the air flow in the branch part 2 A tumble control valve (hereinafter referred to as TCV) 4 is an EGR injection hole for injecting EGR gas in the downstream direction of the branch portion 2. As shown in FIG. 2, all the EGR nozzle holes 4 communicate with the EGR pipe 11. The EGR pipe 11 is a pipe for supplying a part of exhaust gas flowing through an exhaust pipe (not shown) into the engine, and an EGR valve 10 for connecting and blocking the EGR pipe 11 is provided in the middle.

  A partition plate 7 (7a) extending along the axial center is provided downstream of the TCV 3 in the branch portion 2, and is divided into an upper passage 8 and a lower passage 9. The intake port 5 is also divided into upper and lower portions by providing a similar partition plate 7 (7b). In addition, the partition plate 7 (7a) of the intake port 5 projects the partition plate 7 (7b) of the branch portion 2 from the connection surface with the intake port 5 of the branch portion 2, and connects the branch portion 2 to the intake port 5. In this state, it may be inserted into the intake port 5 to divide the intake port 5 into upper and lower parts.

  The TCV 3 is a so-called rotary valve that has a substantially circular cross section and rotates around an axis that is substantially parallel to the arrangement direction of the branch portions 2 and passes through the center of the cross section. The rotation of the TCV 3 is controlled by a control unit (not shown) according to the driving state of the vehicle.

  On the inner surface of the TCV 3, a flow path (port) 3 c having substantially the same cross section as the effective section of the branch portion 2 is provided, and on both sides thereof, there are a small protrusion 3 a and a large protrusion 3 b that protrude in the inner direction of the TCV 3. Is provided. The two protrusions 3a and 3b are positioned so that the small protrusion 3a closes the EGR injection hole 4 and the large protrusion 3b is located near the bottom of the branch part 2 and the lower passage 9 is opened when fully opened. In addition, in the partial state, the small protrusion 3 a is located at a position where the EGR injection hole 4 is opened, and the large protrusion 3 b is provided at a position where the lower passage 9 is closed.

  The shape of the small protrusion 3a will be described with reference to FIG. FIG. 3 is an enlarged view of the vicinity of the EGR nozzle hole 4 when fully opened.

  The small protrusion 3a only needs to be able to completely close the EGR injection hole 4 when fully opened, but it is desirable that the outer peripheral surface has an arc shape in order to suppress the intake resistance. In the present embodiment, as shown in FIG. 3, the amount of protrusion on the downstream side in the intake flow direction (arrow A in FIG. 3) is increased and is reduced to the vicinity of the imaginary line C connecting the upper ends of the branch portions 2. The tip of the protrusion 3a is projected. As a result, the intake flow separated at the downstream end of the small protrusion 3a flows into the upper passage 8 as it is, and the intake resistance can be further reduced.

  Next, the shape of the large protrusion 3b will be described with reference to FIG. FIG. 4 is an enlarged view of the vicinity of the partition plate 7 at the time of partial.

  As shown in FIG. 4, the large protrusion 3 b has an R shape, and the downstream end of the large protrusion 3 b substantially abuts with the upstream end of the partition plate 7 in the partial state to close the lower passage 9. In this case, the downstream end has a shape such that the tangent S substantially coincides with the partition plate 7. As a result, the abutting portion has a smooth circular arc shape in the partial state, so that air rising from the lower side of the branch portion 2 toward the upper passage 8 along the large protruding portion 3b does not peel off at the abutting portion. Thus, a reduction in intake efficiency can be prevented.

  Further, as shown in FIG. 1 (a), when the fully opened performance is reached, the large protrusion 3b is located near the bottom surface of the branch part 2 and protrudes to the inside of the branch part 2. After satisfying the condition that the tangent line S and the partition plate 7 substantially coincide with each other, the arc shape is such that the separation of the air flowing in the vicinity of the bottom surface of the branch portion 2 at the large protrusion portion 3b becomes as small as possible.

  In the intake device of the present embodiment configured as described above, the small protrusion 3a closes the EGR injection hole 4 and the large protrusion 3b is near the bottom of the branch part 2 when the fully open performance is achieved. The rotation angle of the TCV 3 is controlled so that the road cross-sectional area is maximized. As a result, air is supplied from the upper passage 8 and the lower passage 9 to the combustion chamber.

  Further, at the time of partial, the rotation angle of the TCV 3 is controlled so that the EGR nozzle hole 4 is opened and the large protrusion 3 b closes the lower passage 9. Thus, all the air passes through the upper passage 8 and is supplied into the combustion chamber from the upper half of the cross section of the intake port 5 when the intake valve 6 is opened, thereby forming a tumble flow in the combustion chamber. . By forming the tumble flow, it is possible to surely burn even with a small fuel injection amount. Therefore, for example, lean stratified combustion can be performed to improve fuel efficiency.

  The effect of this embodiment will be described in comparison with a conventional configuration. An example of a conventional configuration is shown in FIGS.

  FIG. 5A shows the state around the TCV 3 at the fully open performance as in FIG. 1A, and FIG. 5B similarly shows the state at the partial time in FIG. 1B. When viewed from the upper side, it is the same as FIG. 2, and each EGR nozzle hole 4 communicates with the EGR pipe 11.

  In FIG. 5, TCV3 is a so-called flap type valve. For this reason, the valve remains as an obstacle in the intake air flow path at the fully open performance, and the pressure loss increases due to the air colliding with the valve. Further, flow separation occurred downstream of the valve, and the actual flow path area was reduced.

  Further, in FIG. 5, the EGR nozzle hole 4 opens toward the upstream side of the air flow. The reason for this is as follows. The opening of the EGR nozzle hole 4 is not provided with an opening / closing means, and the EGR gas injection amount is controlled only by the EGR valve 10 interposed in the middle of the EGR pipe 11, and each EGR nozzle hole 4 communicates with the EGR nozzle hole 4. ing. Accordingly, when the EGR valve 10 is closed to stop the injection of the EGR gas, the supply of the EGR gas is stopped, but the space from the EGR valve 10 to the EGR injection hole 4 remains in communication with the branch part 2, that is, each part The lunch portions 2 are in communication with each other.

  As a result, even if negative pressure is generated due to the descending of the piston sequentially in the intake stroke of each cylinder, the negative pressure in the branch portion 2 develops because each branch portion 2 communicates and the substantial volume increases. It is difficult to inhale a sufficient amount of air. Therefore, in order to reduce the influence on the negative pressure development that each branch part 2 is open and each part launch part 2 communicates with each other, the EGR nozzle hole 4 is directed to the upstream side of the air flow, In addition, the opening area is reduced. For this reason, it has been difficult to inject a large amount of EGR gas and to inject EGR gas in a wide operation region from the partial time to the fully open performance.

  However, in the present embodiment, as described above, the EGR injection hole 4 is closed by the small protrusion 3a and the branch parts 2 do not communicate with each other at the time of the fully open performance, so that the EGR injection hole 4 is located downstream of the air flow. The opening area can be increased and a large amount of EGR gas can be injected at the time of partial.

  Further, the TVC 3 is a rotary valve type, and the large protrusion 3b that closes the lower passage 9 at the time of partial movement moves in the vicinity of the bottom surface of the branch portion 2 when fully opened, and has an arc shape so that no flow separation occurs. Therefore, it is possible to suppress an increase in pressure loss at the time of fully open performance and a decrease in actual flow path area.

  As described above, in the present embodiment, the rotation angle of the rotary type TCV 3 provided with the arc-shaped small protrusion 3a and the large protrusion 3b is set so that the small protrusion 3a closes the EGR nozzle 4 at the time of the fully open performance. 3b is the largest flow passage cross-sectional area of the branch portion 2, and in the partial state, the small projection portion 3a opens the EGR injection hole 4, and the large projection portion 3b is separated by the partition plate 7 provided in the branch portion 2. Control is performed so as to block the divided lower passage 9. Further, the EGR nozzle hole 4 can be opened in a large area in the downstream direction of the air flow.

  As a result, the negative pressure of the branch portion 2 is sufficiently developed at the fully open performance and the intake resistance is small, so that the amount of air flowing into the combustion chamber of the internal combustion engine can be increased and the output can be improved. Since EGR gas can be injected, NOx emission can be reduced and fuel consumption can be improved.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

  The present invention is applicable to an intake device for an internal combustion engine.

It is a cross-sectional view of the intake device of the present embodiment. It is a top view of the intake device of this embodiment. It is an enlarged view near EGR nozzle hole. It is an enlarged view near TCV and a partition plate contact part. It is a figure showing an example of the conventional intake device.

Explanation of symbols

1 Collector tank 2 Branch 3 Tumble control valve (TCV)
4 EGR hole 5 Intake port 7 Partition plate 8 Upper passage 9 Lower passage

Claims (6)

Inside, a branch part having a passage partitioned vertically by a partition,
An EGR pipe that communicates with an exhaust passage of the engine and injects EGR gas into the passage from an opening provided in a branch portion on the upstream side of the partition;
An intake device for an internal combustion engine, comprising: an on-off valve provided near an upstream end portion of the partition wall and closing an opening of the EGR pipe when the engine is fully opened.   The intake device for an internal combustion engine according to claim 1, wherein the on-off valve is a rotary valve whose port opening degree changes according to rotation.   3. The intake device for an internal combustion engine according to claim 2, wherein the portion that closes the opening is a first convex portion having an arcuate outer surface provided on one surface of the port of the rotary valve.   4. The intake device for an internal combustion engine according to claim 2, wherein the rotary valve is provided with a second convex portion on the opposite surface of the port to block the lower passage partitioned by the partition wall.   The port is fully opened when the first convex portion blocks the opening, and the opening is fully open when the second convex portion blocks the lower passage. Item 5. An intake device for an internal combustion engine according to Item 4.   The intake device for an internal combustion engine according to claim 1, wherein the EGR pipe injects EGR gas toward a downstream direction of the branch portion.

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