JP2003161209A - Egr cooler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact EGR cooler capable of efficiently cooling EGR gas without increasing a load of an engine cooling system. <P>SOLUTION: In an engine equipped with a water-cooled type cooler 2 in which engine cooling water is circulated and supplied to an EGR pipe 1 leading to an intake air system branched from an exhaust gas system, a pipe 3 with a fin provided with a fin 3a and 3b at least one side of a periphery or an inner circumference constitutes at least some part of the EGR pipe 1 leading to the water-cooled type cooler 2 from the exhaust gas system. Then, the EGR gas supplied into the water-cooled type cooler 2 is pre-cooled by the pipe 3 with a fin to enlarge a cooling (heat exchange) capacity as a whole cooler. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EGR cooler of an EGR system provided as an engine exhaust purification means. [0002] In an EGR system, a high-temperature EG
When the R gas is returned to the intake system, the heat load of the engine increases. Therefore, conventionally, an EGR pipe branched from the exhaust system to the intake system is provided with a water-cooled cooler for circulating and supplying engine cooling water to cool the EGR gas. Accordingly, as the flow rate of the EGR gas increases, or as the efficiency of the EGR cooler increases, the load on the engine cooling system increases and the temperature difference between the steam and water decreases. The radiator provided in the system needs to be larger or more efficient, and an improvement is being demanded as an in-vehicle engine required to be reduced in weight. [0004] The present invention has been made in view of the above circumstances, and an EGR cooler capable of efficiently cooling EGR gas without increasing the load on an engine cooling system. The challenge is to provide [0005] In order to solve the above-mentioned problems, the present invention provides a water-cooled cooler for circulating and supplying engine cooling water to an EGR pipe branched from an exhaust system to an intake system. The engine is characterized in that at least a part of the EGR pipe from the exhaust system to the water-cooled cooler is constituted by a finned pipe provided with fins on at least one of the outer periphery and the inner periphery. An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of an EGR cooler according to the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG. [0007] In these figures, a conventionally known water-cooled cooler 2 for circulating and supplying engine cooling water is provided in the middle of an EGR pipe 1 branching from an exhaust manifold (not shown) to an intake manifold. 2a is a cooling water inlet, and 2b is a cooling water outlet. A part of the EGR pipe 1 on the exhaust manifold side of the water-cooled cooler 2 is constituted by a finned pipe 3. By providing a heat radiation fin 3a on the outer peripheral surface of the finned pipe 3 and providing a heat exchange fin 3b inside the finned pipe 3, the EGR gas passing through the inside of the finned pipe 3 and the outside of the finned pipe 3 are removed. The heat exchange capacity with the flowing outside air is increased. Specifically, a large number of flange-shaped fins are fixed to the outer peripheral surface of the finned pipe 3 to increase the heat transfer area between the outside air and the finned pipe 3 and to form a star having a hollow cross section. Heat exchange fins 3b into finned pipes 3.
Finned pipe 3
The heat exchange capacity is increased by increasing the contact area between the EGR gas flowing inside the pipe 3 and the finned pipe 3 while suppressing an increase in the passage resistance inside the pipe. Therefore, the EGR gas flowing from the exhaust manifold to the intake manifold is heat-exchanged (pre-cooled) with the outside air while flowing through the finned pipe 3, and its temperature is lowered. As a result, the cooling (heat exchange) capacity of the entire cooler increases. For this reason, for example, when the heat exchange capacity of the water-cooled cooler 1 is set to the same level as the conventional one, the temperature of the EGR gas decreases by the amount of cooling by the finned pipe 3 and the load on the engine cooling system increases. An EGR gas having a lower temperature can be obtained without causing this. In the case where the temperature of the EGR gas should be approximately the same as the conventional one, the water-cooled cooler 2 can reduce the heat exchange capacity by an amount corresponding to the heat exchange capacity of the finned pipe 3. Load can be reduced. In the embodiment, the finned pipe 3
A radiating fin 3a having a flange shape is fixed to the outer periphery of the finned pipe 3, and a heat exchange fin 3b is provided inside the finned pipe 3 to increase the heat exchange capacity between the EGR gas and the outside air flowing outside the finned pipe 3. However, for example, when the radiation fins 3a are omitted, the installation space of the finned pipe 3 can be reduced, and when the heat exchange fins 3b are omitted, the passage resistance of the EGR gas can be reduced. it can. Accordingly, for example, the size and shape of the radiation fins 3a and the heat exchange fins 3b according to the restrictions on the installation space in the engine room, the length and cross-sectional area of the finned pipe 3, or the flow rate of the EGR gas. May be appropriately set, and if the finned pipe 3 can be made sufficiently long, one of the fins may be omitted. As is apparent from the above description, according to the present invention, at least a part of the EGR pipe which has only the function of guiding the EGR gas to the water-cooled cooler is constituted by a finned pipe. Since the cooling function similar to that of the air-cooled cooler is maintained, the capacity of the water-cooled cooler can be reduced and the load on the engine cooling system can be reduced without sacrificing the cooling function of the EGR gas.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing one embodiment of an EGR cooler according to the present invention. FIG. 2 is a sectional view taken along line AA of FIG. [Description of Signs] 1 EGR pipe 2 Water-cooled cooler 3 Pipe with fins 3a Radiation fin 3b Heat exchange fin

Claims (1)

Claims 1. An EGR that branches from an exhaust system to an intake system.
A finned pipe in which at least a part of an EGR pipe from an exhaust system to a water-cooled cooler is provided with a fin on at least one of an outer circumference and an inner circumference in an engine provided with a water-cooled cooler in which engine cooling water is circulated and supplied to the pipe. An EGR cooler characterized by comprising: