JPH0561445U - Exhaust gas recirculation system for internal combustion engine with supercharger - Google Patents

Abstract

(57) [Summary] [Purpose] To allow an exhaust gas recirculation to be performed well without deteriorating fuel efficiency in a vehicle equipped with a supercharger. [Structure] A throttle portion 33, a cylindrical portion 34, and a widening portion 35 are provided in an intake passage 23 downstream of a compressor turbine, and an opening 38 is directed downstream by a downstream outer peripheral wall of the widening portion 35 and a narrowing portion 37. Form. Further, the downstream end of the exhaust gas recirculation passage 30 is connected to the hollow portion 36 outside the cylindrical portion 34.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an exhaust gas recirculation device for an internal combustion engine with a supercharger.

[0002]

[Prior Art]

 As a conventional example of an exhaust gas recirculation system for an internal combustion engine with a supercharger, there are the following ones (JP-A-54-19015, JP-A-56-105646, JP-A-2-43448, etc.). reference). In this system, an intake throttle control valve is provided in the intake passage downstream of the compressor of the exhaust turbocharger, and the intake passage downstream of the intake throttle control valve and the exhaust passage are connected by an exhaust gas recirculation passage. A pressure-controlled exhaust gas recirculation control valve is provided in the exhaust gas recirculation passage, and the intake pressure downstream of the intake throttle control valve is introduced into the working chamber of the exhaust gas recirculation control valve.

Then, in a predetermined operation region, the intake throttle control valve throttles intake air to operate the exhaust gas recirculation control valve to control the exhaust gas recirculation amount. Another example of the conventional exhaust gas recirculation device is shown in FIG. 5 (see Japanese Utility Model Publication No. 56-11646). This is an engine that does not include a supercharger that uses LPG as fuel. An LPG venturi 4 is provided in the intake passage 3 upstream of the primary side and secondary side throttle valves 1 and 2, and the venturi 4 is provided. Has a large number of communication holes 5. Then, the LPG combustion is introduced into the intake passage 3 via the rear communication hole 5 introduced into the hollow portion of the venturi 4 via the LPG passage 6 and the metering orifice 7.

An EGR venturi 8 is provided in the intake passage 3 upstream of the LPG venturi 4, and the venturi 8 has upstream and downstream communication holes 9 and 10. Then, the exhaust gas is introduced into the hollow portion of the venturi 8 via the EGR passage 11, and then is mainly introduced into the intake passage 3 from the downstream side communication hole 10.

[0005]

[Problems to be solved by the device]

 However, in the former type in which the intake throttle control valve is provided downstream of the compressor of the exhaust turbocharger and the exhaust gas is recirculated to the intake passage downstream of the control valve, the pressure loss due to the intake throttle control valve becomes large, so pumping There is a problem that the loss increases and the fuel efficiency deteriorates. Further, when the exhaust gas is recirculated to the downstream side of the compressor, in the diesel engine, the intake pressure becomes higher than the exhaust pressure particularly during low-speed and high-load operation, so that the exhaust gas cannot be recirculated.

In addition, in the case of introducing the exhaust gas into the intake passage from the communication holes 9 and 10 of the EGR venturi 8, in addition to the same problem as described above, soot in the exhaust gas is particularly blocked in the communication hole 10. There is. On the contrary, if the exhaust gas is recirculated to the upstream side of the compressor, the soot in the exhaust gas may adhere to the blades of the compressor and cause malfunction.

The present invention has been made in view of such a situation, and an object thereof is to allow exhaust gas recirculation to be performed favorably without deteriorating fuel efficiency.

[0008]

[Means for Solving the Problems]

 Therefore, the present invention provides a tubular throttle portion that throttles the pressurized intake air and a tubular portion connected to the downstream end of the throttle portion in the intake passage downstream of the compressor turbine of the supercharger. A hollow portion formed by an inner wall of the intake passage is provided on the outer peripheral side of the throttle portion and the cylindrical portion, and an opening portion having a predetermined gap is provided between the outer peripheral wall of the cylindrical portion and the outermost peripheral end of the cylindrical portion substantially downstream of the intake passage. A projecting portion facing the outermost peripheral wall of the most downstream end of the tubular portion is formed in the intake passage so as to be opened toward the outside, and the downstream end portion of the exhaust gas recirculation passage is communicated with the hollow portion.

[0009]

[Action]

 Then, the flow velocity of the pressurized intake air is accelerated by the throttle and the cylinder to reduce the static pressure of the intake air passing through the inside of the opening, and the static pressure causes the exhaust gas to be sucked into the intake passage from the opening. did.

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 show an embodiment of the present invention. First, the overall structure of the diesel engine with an exhaust turbocharger will be described with reference to FIG. 1. The intake manifold 22 of the engine body 21 is connected to an intake pipe 23 that constitutes an intake passage, and the exhaust manifold 24 is connected to the exhaust manifold 24. The pipe 25 is connected. A compressor turbine 27 of an exhaust turbocharger 26 is installed in the middle of the intake pipe 23, and an exhaust turbine 28 that rotates the compressor turbine 27 is installed in the middle of the exhaust pipe 25.

An exhaust gas introducing portion 29, which will be described later, is formed in the intake pipe 23 downstream of the compressor turbine 27, and the exhaust gas introducing portion 29 and the exhaust pipe 25 upstream of the exhaust turbine 28 are connected to each other by an exhaust gas recirculation passage 30. ing. Reference numeral 31 is an air cleaner, and 32 is a muffler. As shown in FIG. 2, a cylindrical throttle portion 33 is coaxially connected to the downstream end portion of the upstream intake pipe 3 in the exhaust introduction portion 29, and the throttle portion 33 has a flow passage cross-sectional area downstream. It is formed so as to become gradually smaller. A cylindrical small-diameter portion 34 is coaxially connected to the downstream end of the narrowed portion 33, and the flow passage cross-sectional area of the small-diameter portion 34 is formed in substantially the same manner over the entire area. A cylindrical expansion portion 35 is coaxially connected to the downstream end of the cylindrical portion 34, and the expansion portion 35 is formed so that the cross-sectional area of the flow passage gradually increases toward the downstream side.

A cylindrical hollow portion 36 is provided so as to cover the outer circumferences of the throttle portion 33 and the small diameter portion 34, and the exhaust gas recirculation passage 30 is connected to the hollow portion 36. Exhaust gas is introduced from the exhaust gas recirculation passage 30. A cylindrical throttling portion 37 serving as a protruding portion is connected to the downstream end of the hollow portion 36 so as to cover the outside of the expanding portion 35, and the throttling portion 37 gradually becomes smaller as the flow passage cross-sectional area becomes downstream. It is formed to be small. Here, an opening 38 is formed between the inner peripheral wall of the narrowed portion 37 and the outer peripheral wall of the expanded portion 35 so as to open downstream.

Further, a cylindrical small-diameter portion 39 is coaxially connected to the downstream end of the throttle portion 37, and the flow passage cross-sectional area of the small-diameter portion 39 is formed to be substantially the same over the entire area. A widened portion 40 is coaxially connected to the downstream end of the small diameter portion 39, and the flow passage cross-sectional area of the widened portion 40 is formed so as to gradually increase as it flows downward. The upstream end of the downstream intake pipe 23 is coaxially connected to the downstream end of the expanding portion 40.

Reference numeral 41 is an exhaust gas recirculation control valve for controlling the amount of exhaust gas recirculation. According to this structure, the intake air pressurized by the compressor turbine 27 flows through the suction pipe 23 and is introduced into the throttle portion 33 and the small diameter portion 34, and is then introduced into the small diameter portion 39 from the expanded portion 35. .. Then, the flow velocity of the intake air is increased in the throttle portion 33 and the small diameter portion 34, and the intake air whose static pressure has decreased passes through the inside of the opening portion 38, so that the exhaust effect causes the exhaust gas to flow from the opening portion 38 into the passage. It is sucked in, introduced, and mixed with intake air.

At this time, since the intake air smoothly flows through the throttle portion 33 and the small diameter portion 34, the pressure loss can be made smaller than that of the conventional example (the one having the intake throttle control valve), so that the pumping loss can be reduced and the fuel economy Can be improved. In particular, since the opening 38 opens to the downstream side of the passage, the exhaust gas suction effect can be improved. Further, since the static pressure can be made sufficiently low, the exhaust gas can be introduced into the intake pipe 23 and the exhaust gas recirculation rate can be improved even if the supercharging pressure is higher than the exhaust gas pressure. Further, since the flow passage cross-sectional area of the opening 38 is relatively large, it is possible to prevent the soot in the exhaust from clogging the opening 38.

FIG. 3 shows a modification of the mounting position of the exhaust introduction part 29. When the intake pipe 23 downstream of the compressor turbine 27 is provided with an intercooler 42, the exhaust introduction is carried out to the intake pipe 23 downstream of the intercooler 42. It is desirable to provide the portion 29. FIG. 4 shows a modification of the exhaust gas introducing portion. In this embodiment, the throttle portion 52 and the cylindrical portion 53 are coaxially provided in the intake pipe 51, and the exhaust gas recirculation passage 54 is provided in the hollow portion 54 formed on the outer periphery of the throttle portion 52 and the cylindrical portion 53. Connect the downstream ends in communication.

Further, in order to form an opening 55 that opens downstream between the outermost wall of the most downstream end of the cylindrical portion 53, a circumferential protrusion is formed with a predetermined gap with the outer wall of the most downstream end of the cylindrical portion 53. The part 56 is formed in the intake pipe 51. Such a structure is effective when the intake flow velocity is low.

[0018]

[Effect of the device]

 As described above, the present invention accelerates the flow velocity of the intake air pressurized by the supercharger to the throttle portion and the cylinder portion to reduce the static pressure, and the static pressure sucks the exhaust gas efficiently from the opening. As a result, pressure loss can be reduced, fuel consumption can be improved, exhaust gas recirculation rate can be improved, and soot in exhaust gas can be prevented from clogging the opening.

[Brief description of drawings]

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

FIG. 2 is an enlarged view of a main part of the above.

FIG. 3 is a diagram showing a modified example of the above.

FIG. 4 is a diagram showing another modification of the above.

FIG. 5 is a sectional view of an essential part showing an embodiment of an exhaust gas recirculation device.

[Explanation of symbols]

 23 Intake Pipe 26 Exhaust Turbocharger 27 Compressor Turbine 29 Exhaust Introducing Section 30 Exhaust Gas Recirculation Channel 33 Throttle Valve 34 Cylindrical Section 35 Expanding Section 36 Hollow Section 37 Throttling Section 38 Opening

Claims (1)

[Scope of utility model registration request] 1. An internal combustion engine with a supercharger comprising a supercharger for pressurizing intake air with a compressor turbine, and a tubular throttle portion for restricting the pressurized intake air in an intake passage downstream of the compressor turbine. A tubular portion connected to the downstream portion of the throttle portion, and a hollow portion formed by the intake passage inner wall on the outer peripheral side of the throttle portion and the tubular portion, and the outermost wall of the most downstream end of the tubular portion. A protrusion facing the outermost wall of the most downstream end of the tubular portion is formed in the intake passage to form an opening of a predetermined gap between the intake passage and the exhaust gas recirculation passage in the hollow portion. An exhaust gas recirculation system for an internal combustion engine with a supercharger, the downstream end of which is connected to communicate.