JPH04353213A - Liquid-cooled type exhaust manifold - Google Patents

Abstract

PURPOSE:To improve the heat exchange efficiency between the exhaust heat and the cooling liquid. CONSTITUTION:A discharge part 8 for exhaust gas which extends from the collection part 4b of an inner cylinder 4 is installed at the front edge part of an outer cylinder 5, and arranged in the vicinity of the feeding part 11 for cooling liquid 10. Accordingly, the exhaust gas which flows in the inner cylinder 4 and the cooling liquid 10 which flows in an advance passage 13 form the opposed flow, and the temperature difference between the exhaust heat and the cooling liquid becomes large, and the heat exchange efficiency is improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid-cooled exhaust manifold for an engine for a cogeneration system.

0002

[Prior Art] A cogeneration system uses a gas engine, diesel (gasoline) engine, etc. to generate electricity, and uses the exhaust heat from these engines to supply thermal energy for hot water supply, air conditioning, heating, etc., and has a high thermal efficiency. It has the advantage of extremely high energy consumption and the fact that unlike large-scale power generation systems, the location is not limited.
There is a tendency for their introduction to increase, mainly in offices and commercial areas.

Some engines used in such cogeneration systems are equipped with a liquid-cooled exhaust manifold that recovers exhaust heat from the exhaust manifold and converts it into useful thermal energy. In other words, each branch part of the exhaust manifold that communicates with the exhaust port of the cylinder head and the gathering part thereof have a double structure consisting of an inner cylinder through which exhaust gas flows and an outer cylinder that covers this, and the inner cylinder and outer cylinder have a double structure. A passage is formed between the cylinder and the cylinder, through which the cooling liquid circulates, so that heat exchange is performed between the exhaust gas flowing in the inner cylinder and the cooling liquid.

[0004] In conventional liquid-cooled exhaust manifolds, the position of the exhaust outlet extending from the gathering part is often provided regardless of the position of the coolant inlet/outlet provided in the outer cylinder.
Generally, in consideration of ease of connection with the exhaust pipe and installation of other auxiliary equipment, the exhaust outlet is located on the same side as the coolant outlet, that is, on the downstream side of the exhaust, near the rear of the manifold. There are many things to do.

[0005]

[Problems to be Solved by the Invention] As mentioned above, if the exhaust outlet is located on the coolant outflow side, the flow direction of the coolant and the flow direction of the exhaust gas will be the same, so the coolant will flow downstream. There is a problem that the temperature difference with the exhaust gas gradually decreases toward the side, the heat exchange efficiency between the exhaust heat and the coolant decreases, and the rate of temperature rise of the coolant decreases.

The present invention has been made to solve the above problems, and its purpose is to reduce the difference between exhaust heat and coolant by always maintaining a large temperature difference between the exhaust gas and the coolant. An object of the present invention is to provide a liquid-cooled exhaust manifold that can improve heat exchange efficiency.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a plurality of branch portions communicating with an exhaust port of a cylinder block, a gathering portion for gathering the branch portions, and a portion extending from the gathering portion. An outer cylinder surrounds an inner cylinder consisting of an exhaust part for discharging exhaust gas, and the exhaust heat is collected into a cooling liquid that circulates through a passage formed between the inner cylinder and the outer cylinder. In the cold exhaust manifold, a cooling liquid supply section is provided at one of the front and rear ends of the outer cylinder, and an outlet section is provided at the other end, and the exhaust gas discharge section is arranged near the supply section. It is characterized by

[0008]

[Operation] Since the exhaust gas discharge part is located near the coolant supply part, the exhaust gas flowing in the inner cylinder and the coolant flowing in the passages flow in opposite directions, so that the exhaust gas is heated by the exhaust heat. The temperature difference between the tube and the coolant increases, increasing the mutual heat exchange efficiency.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows an engine for a cogeneration system, for example a diesel engine.
A liquid-cooled exhaust manifold (2), which will be described in detail below, is attached to one side of the cylinder head (1).

As shown in FIGS. 2 and 3, on the side surface of the cylinder head (1), there are branch portions (4a) that communicate with each exhaust port (3), and a generally horizontally elongated cylindrical group that collects the branch portions (4a). An inner cylinder (4) consisting of a collector (4b), and an outer cylinder (5) that covers the periphery of the inner cylinder (4) and is integrally connected to its outer wall at a required distance. , a plurality of flanges (6) protruding from the upper and lower ends of the outer cylinder (5) are attached to the side wall of the cylinder head (1) by bolts (7).
), it is installed with a slight downward tilt.

At the front end (left end in FIG. 3) of the collecting part (4b) in the inner cylinder (4), there is an exhaust part (8) for discharging the exhaust gas that has flowed into the collecting part (4b) to the outside. is arranged facing the exhaust gas flow path of the frontmost branch part (4a) so as to face substantially the same direction, and an exhaust pipe (9) is bolted to the flange part thereof.

[0012] From each branch part (4a) to the discharge part (8
The exhaust gas passageway (4c) leading to ) is gently bent so as to communicate in almost the same plane, and is connected to the core (not shown), the main mold, and the inner cylinder (4) during casting. The structure of the covering outer cylinder (5) is simplified to facilitate molding thereof and to facilitate die cutting.

[0013] A cooling liquid (10
) The supply part (11) and the outflow part (12) are arranged facing in the front-rear direction, and the supply part (11) is connected to the inner and outer cylinders (4) (
The cooling liquid (10) that has flowed into the passage (13) between
After being warmed by the exhaust heat, it flows out from the outflow section (12), supplies heat to, for example, a heating device (not shown), and then returns to the supply section (11) for recirculation.

Liquid-cooled exhaust manifold (2) of the above embodiment
), the exhaust gas discharge part (8) is connected to the collecting part (4b).
If it is installed near the front end of the cooling liquid (10), i.e. near the supply part (11) on the upstream side of the cooling liquid (10), as shown by the arrow in FIG. Therefore, the temperature difference between the coolant (10) flowing in the passage (13) toward the outflow part (12) and the inner cylinder (4) heated by exhaust heat is always maintained large. be able to. As a result, the heat exchange efficiency between the exhaust heat and the coolant (10) increases, and the temperature of the coolant (10) effectively increases as it flows downstream.

Furthermore, since the supply part (11) and the outflow part (12) of the cooling liquid (10) are provided almost symmetrically at the front and rear ends of the outer cylinder (5), the passage (13) can be easily formed. It is easy to mold the core for use, and the supply part (11) and outflow part (1
2) can also serve as a baseboard for supporting the core, so the core can be stably supported without providing a separate baseboard.

[0016]

According to the present invention, the exhaust gas and the cooling liquid flow in opposite directions, and the temperature difference between them can be maintained largely, so that the efficiency of heat exchange between the exhaust heat and the cooling liquid is greatly increased.

[Brief explanation of drawings]

FIG. 1 is a side view of an engine for a cogeneration system including an embodiment of the present invention.

FIG. 2 is an enlarged longitudinal sectional front view of a main part taken along line A-A in FIG. 1.

FIG. 3 is a cross-sectional plan view of essential parts taken along line BB in FIG. 2;

[Explanation of symbols]

(1) Cylinder head (2) Liquid-cooled exhaust manifold

Claims (1)

[Claims] Claim 1: A periphery of an inner cylinder comprising a plurality of branch portions that communicate with an exhaust port of a cylinder block, a gathering portion that gathers the branch portions, and an exhaust portion extending from the gathering portion for discharging exhaust gas. In a liquid-cooled exhaust manifold, the exhaust manifold is covered with an outer cylinder, and the exhaust heat is collected into a cooling liquid circulating through a passage formed between the inner cylinder and the outer cylinder,
A liquid cooling device characterized in that a cooling liquid supply section is provided at one of the front and rear ends of the outer cylinder, and an outlet section is provided at the other end, and the exhaust gas discharge section is arranged near the supply section. type exhaust manifold.