WO2001053666A1

WO2001053666A1 - Controlling exhaust manifold temperatures

Info

Publication number: WO2001053666A1
Application number: PCT/US2001/002114
Authority: WO
Inventors: John H. Westerbeke
Original assignee: Westerbeke Corporation
Priority date: 2000-01-21
Filing date: 2001-01-22
Publication date: 2001-07-26
Also published as: WO2001053666A8; AU2001231062A1

Abstract

An exhaust manifold cooling jacket (20) has internal passages (30) for the circulation of liquid coolant and encloses an exhaust manifold such that a gap (31) is created between the exhaust manifold and cooling jacket (20). Flowing coolant through the jacket (20) regulates outer jacket temperature while enabling high intra-manifold exhaust gas temperature for thorough intra-manifold combustion and improved emissions. In some marine applications, for example, seawater coolant is discharged into the exhaust gas stream at an attached exhaust elbow.

Description

CONTROLLING EXHAUST MANIFOLD TEMPERATURES

TECHNICAL FIELD

This invention relates to cooling engine exhaust manifolds, and more particularly to controlling the temperature of engine exhaust manifolds and the exhaust gasses flowing through them.

BACKGROUND

The exhaust gasses flowing through an exhaust gas manifold of an internal combustion engine are typically very hot, and the exhaust manifold itself may reach very high surface temperatures. To keep the outer surface temperature of the exhaust manifold down for safety reasons, some exhaust manifolds are water cooled, meaning that they contain inner passages through which cooling water flows during engine operation or that they are placed within jackets with cooling water flowing directly across the outer surface of the manifold. Indeed, there are some regulations requiring that exhaust manifolds be provided with cooling jackets for particular applications, such as for marine vessel inspections.

SUMMARY

The invention features a cooling jacket having internal passages for flowing water or other coolant through the jacket to moderate jacket temperature. The jacket attaches to the engine cylinder head to enclose and cool the exhaust manifold of the engine, thereby moderating the temperature of the exhaust gas flowing through the manifold and blocking the outer surface of the manifold from unwanted contact with nearby objects or personnel. As the coolant flows through internal passages in the manifold rather than through or across the exhaust manifold, the coolant never comes into contact with the manifold itself. Manifold cooling is achieved via radiant and convective heat transfer to the jacket when an air gap is provided between the outer surfaces of the manifold and the inner surfaces of the cooling jacket, or by conduction through an insulating material placed between the manifold and jacket. Among the various aspects of the invention are the cooling jacket so described, engines equipped with such cooling jackets, and methods of cooling engine exhaust manifolds by incorporating such jackets.

In some embodiments the cooling jacket defines a coolant inlet and a coolant outlet that are both separate from the exhaust stream. In some other cases, particularly applicable to l marine engines, for example, coolant enters the jacket through a separate inlet but then joins the exhaust flow as the exhaust leaves the manifold, thereby further reducing exhaust gas temperature.

According to one aspect of the invention, an exhaust manifold cooling jacket has a housing to be attached to a cylinder head of a combustion engine. The housing defines a cavity sized to enclose an exhaust manifold of the engine and form an insulating space between the exhaust manifold and housing, as attached to the cylinder head, a coolant passage for receiving liquid coolant from an inlet of the jacket and for flowing the coolant through the cooling jacket, and an exhaust passage extending between an inner manifold interface surface of the housing and an exhaust elbow interface surface of the housing, for forming a sealed exhaust conduit for conducting a flow of exhaust from the exhaust manifold through the housing.

In the illustrated embodiment, the cooling jacket housing is in the form of a shell having an open side sufficiently large to permit the housing to be placed about the exhaust manifold of the engine with the exhaust manifold mounted upon the cylinder head.

Preferably, the open side of the housing comprises a rim extending about the open side and lying in a single plane to form a planar block interface surface. The rim of the housing may be arranged to be coplanar with a block interface surface of the exhaust manifold as attached to the cylinder head, for example, for engaging a backing plate mounted between the cylinder head and exhaust manifold and extending laterally beyond the exhaust manifold.

Preferably, the cooling jacket housing is sized and constructed to directly contact the exhaust manifold only at the inner manifold interface surface.

In some embodiments, the coolant passage comprises a single enclosed, cup-shaped cavity extending across one broad face of the housing and into multiple sides of the housing. For preferred marine applications, the housing also defines a coolant outlet extending from the coolant passage through the exhaust elbow interface surface adjacent the exhaust conduit.

The housing is preferably in the form of a unitary casting, such as of salt resistant aluminum or cast iron, for example. The housing further defines, in some embodiments, at least one mounting hole extending through the housing adjacent the exhaust passage and arranged to align with a mounting hole on the exhaust manifold, for receiving a threaded fastener to attach the housing to the cylinder head via the exhaust manifold. The mounting hole of the housing

9 may be further arranged to align with a corresponding mounting hole on an exhaust elbow placed against the exhaust elbow interface surface to receive exhaust flow from the exhaust conduit, for simultaneously attaching both the housing and the exhaust elbow to the exhaust manifold. Ideally, the cooling jacket is constructed to isolate the liquid coolant from any direct contact with the exhaust manifold.

The insulating space between the cooling jacket and the housing may be filled with air and isolated from the flow of exhaust, or filled with a conductively insulating material, for example. According to another aspect of the invention, a method is provided for altering a combustion engine to enhance exhaust gas cooling for use in a marine environment. The method features placing the above-described cooling jacket directly between an upstream exhaust manifold secured to a cylinder head of the engine, and a downstream exhaust elbow of the engine. In some applications, a backing plate is placed between the exhaust manifold and the cylinder head. The backing plate defines sealed passages for conducting exhaust gasses from the cylinder head to the exhaust manifold, and extends laterally beyond the exhaust manifold to engage the cooling jacket housing to inhibit air flow through the insulating space between the cooling jacket housing and the exhaust manifold. For some applications, such as preferred marine applications, the exhaust elbow is provided with a coolant passage having an inlet for receiving the coolant from the cooling jacket housing and for injecting the coolant into a flow of exhaust received from the exhaust manifold through the cooling jacket housing.

Advantageously, some embodiments of the exhaust elbow and cooling jacket housing can be simultaneously mounted to the exhaust manifold by inserting at least one fastener through aligned mounting holes in the exhaust elbow and cooling jacket housing and securing the fastener to the exhaust manifold.

The invention can provide for the ready modification of engines to comply with exhaust manifold cooling requirements, without having to modify the exhaust manifold to either provide for internal cooling or withstand prolonged surface contact with a desired coolant. Furthermore, the temperature of the exhaust gas within the manifold can be maintained at a higher temperature than with normally cooled manifolds, given a maximum allowable exposed surface temperature, enabling more complete intra-manifold combustion and improving overall emissions.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

Figs. 1A and IB are front and back perspective views, respectively, of an exhaust manifold cooling jacket.

Fig. 2 is a side view of the cooling jacket, viewed from the side adjacent the engine. Fig. 3 is an end view of the cooling jacket.

Figs. 4 and 5 are cross-sectional views, taken along lines 4-4 and 5-5, respectively, in Fig. 2.

Fig. 6 is a cross-sectional view, taken along line 6-6 in Fig. 3.

Fig. 7 is a perspective view of a mounting plate for the cooling jacket. Figs. 8A and 8B are front and back perspective views, respectively, of an exhaust elbow.

Fig. 9 is an end view of the exhaust elbow, as looking toward the cooling jacket.

Fig. 10 is a side view of the exhaust elbow.

Figs. 1 1 and 12 are cross-sectional views, taken along lines 11 -1 1 and 12-12, respectively, in Fig. 9.

Fig. 13 is a cross-sectional view, taken along line 13-13 in Fig. 10.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Referring first to Figs. 1A and IB, cooling jacket 20 is sand or investment cast in a shape designed to form an interior cavity 22 sized to fit about an engine exhaust manifold (not shown) when the cooling jacket is mounted against the engine head. In this embodiment, the jacket includes a mounting boss 24 and associated exhaust port 26 through which exhaust gas flows from the manifold to a downstream exhaust elbow (shown in Figs. 8A through 13). Accordingly, boss 24 features mounting holes 28 through which fasteners from the exhaust elbow extend into threaded bosses on the exhaust manifold, sandwiching the cooling jacket 20 between the manifold and elbow and sealing the exhaust passage. If desired, the cooling jacket may also be mounted securely to the engine cylinder head by appropriate lugs and fasteners (not shown).

Referring also to Figs. 2-6, cooling jacket 20 is cast to define an internal cooling passage or cavity 30 in hydraulic communication with a coolant inlet 32, which is attached to a pressurized coolant source (not shown) for circulating coolant through the cooling jacket. From passage 30, the coolant exits the cooling jacket through ports 34 in boss 24 and flows into the exhaust elbow, where it is blended with the exhaust gas. Alternatively, a separate coolant exit port (not shown) may be provided for returning the coolant to its source.

As shown in Fig. 3, in this embodiment an air gap 31 is formed between the inner surface of the cooling jacket and the outer surface 33 of the exhaust manifold (shown in dashed outline). Alternatively, an appropriate insulating material, such as glass fiber (not shown), may be packed into this gap and provide insulation against heat conduction between the exhaust manifold and cooling jacket.

Cooling jacket 20 may be cast of any material suitable to the intended environment. For marine applications employing salt water as coolant, a salt resistant aluminum alloy is appropriate. If the cooling jacket is to be mounted directly against a cast iron engine head, or if very high temperatures are anticipated, cast iron may be more appropriate. If aluminum is used and exiting exhaust gas temperatures are high or the exhaust gas is particularly corrosive to aluminum, an iron sleeve may be provided through exhaust port 26. To completely enclose the exhaust manifold, a backing plate 36 may be employed as shown in Fig. 3, and illustrated in Fig. 7. The backing plate is made of flat metal stock, with appropriate exhaust ports placed to align with the exhaust ports of the engine cylinder head. Backing plate 36 is positioned as if it were an exhaust manifold gasket, between the cylinder head (shown as a dashed line to the right of the backing plate) and manifold, with the manifold fasteners securing the backing plate in place. The outer edges of the backing plate engage the rim of the cooling jacket, such that there is no appreciable convective air flow through the cooling jacket.

Referring now to Figs. 8A and 8B, exhaust elbow 38 is adapted to mount on boss 24 of cooling jacket 20 (see Fig. 1A) via an appropriate mounting flange 40. Exhaust inlet 42 aligns with exhaust port 26 of the cooling jacket (Fig. 1 A), and appropriately positioned coolant inlets 44 align with the coolant outlet ports 34 of the cooling jacket (Fig. 1 A), such that both the exhaust gasses and coolant enters exhaust elbow 38 separately. At its downstream end 46, the exhaust elbow is coupled to the remainder of the exhaust system (not shown) in typical fashion.

Referring to Figs. 9-13, from mounting flange 40 and inlet 42 the exhaust gas flows straight through the exhaust elbow along a central exhaust passage 49 to an exhaust outlet 48. The coolant flows through coolant passage 50 to the downstream end 46 of the exhaust elbow, where it exits the exhaust elbow at outlets 52 and joins the flow of exhaust gas. Coolant passage 50 is not completely annular at either end of the exhaust tube, due to the structural ribs required between the inner and outer portions of the exhaust elbow.

A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, a single manifold/jacket assembly may replace the standard exhaust manifold and contain both internal exhaust passages and internal coolant passages, with an internal air space between the coolant passages and exhaust passages such that many of the benefits of the invention are achieved. Because of direct exposure to high temperature exhaust gasses, however, such a combination version would be limited to particular materials, such as cast iron or steel. Accordingly, other embodiments are within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. An exhaust manifold cooling jacket comprising a housing to be attached to a cylinder head of a combustion engine, the housing defining a cavity sized to enclose an exhaust manifold of the engine and form an insulating space between the exhaust manifold and housing, as attached to the cylinder head, a coolant passage therein for receiving liquid coolant from an inlet of the jacket and for flowing the coolant through the cooling jacket, and an exhaust passage extending between an inner manifold interface surface of the housing and an exhaust elbow interface surface of the housing, for forming a sealed exhaust conduit for conducting a flow of exhaust from the exhaust manifold through the housing.

2. The exhaust manifold cooling jacket of claim 1, wherein the cooling jacket housing is in the form of a shell having an open side sufficiently large to permit the housing to be placed about the exhaust manifold of the engine with the exhaust manifold mounted upon the cylinder head.

3. The exhaust manifold cooling jacket of claim 2. wherein the open side of the housing comprises a rim extending about the open side and lying in a single plane to form a planar block interface surface.

4. The exhaust manifold cooling jacket of claim 3, wherein the rim of the housing is arranged to be coplanar with a block interface surface of the exhaust manifold, as attached to the cylinder head, for engaging a backing plate mounted between the cylinder head and exhaust manifold and extending laterally beyond the exhaust manifold.

5. The exhaust manifold cooling jacket of claim 1 , wherein the cooling jacket housing is sized and constructed to directly contact the exhaust manifold only at the inner manifold interface surface.

6. The exhaust manifold cooling jacket of claim 1 , wherein the coolant passage comprises a single enclosed, cup-shaped cavity extending across one broad face of the housing and into multiple sides of the housing.

7. The exhaust manifold cooling jacket of claim 1 , wherein the housing further defines a coolant outlet extending from the coolant passage through the exhaust elbow interface surface adjacent the exhaust conduit.

8. The exhaust manifold cooling jacket of claim 1, wherein the housing is in the form of a unitary casting.

9. The exhaust manifold cooling jacket of claim 1 , wherein the housing further defines at least one mounting hole extending through the housing adjacent the exhaust passage and arranged to align with a mounting hole on the exhaust manifold, for receiving a threaded fastener to attach the housing to the cylinder head via the exhaust manifold.

10. The exhaust manifold cooling jacket of claim 9, wherein the mounting hole of the housing is further arranged to align with a corresponding mounting hole on an exhaust elbow placed against the exhaust elbow interface surface to receive exhaust flow from the exhaust conduit, for simultaneously attaching both the housing and the exhaust elbow to the exhaust manifold.

1 1. The exhaust manifold cooling jacket of claim 1, wherein the cooling jacket is constructed to isolate the liquid coolant from any direct contact with the exhaust manifold.

12. The exhaust manifold cooling jacket of claim 1 , wherein said insulating space is filled with air and isolated from the flow of exhaust.

13. The exhaust manifold cooling jacket of claim 1 , wherein said insulating space is filled with a conductively insulating material.

14. A method of altering a combustion engine to enhance exhaust gas cooling for use in a marine environment, the method comprising the step of placing a cooling jacket directly between an upstream exhaust manifold secured to a cylinder head of the engine, and a downstream exhaust elbow of the engine, the cooling jacket comprising a housing defining a cavity sized to enclose an exhaust manifold of the engine and form an insulating space between the exhaust manifold and housing, as attached to the cylinder head, a coolant passage therein for receiving liquid coolant from an inlet of the jacket and for flowing the coolant through the cooling jacket, and an exhaust passage extending between an inner manifold interface surface of the housing and an exhaust elbow interface surface of the housing, for forming a sealed exhaust conduit from the exhaust manifold through the housing.

15. The method of claim 14 further comprising the step of placing a backing plate between the exhaust manifold and the cylinder head, the backing plate defining sealed passages therethrough for conducting exhaust gasses from the cylinder head to the exhaust manifold, the backing plate extending laterally beyond the exhaust manifold to engage the cooling jacket housing to inhibit air flow through the insulating space between the cooling jacket housing and the exhaust manifold.

16. The method of claim 14 further comprising the step of providing the exhaust elbow with a coolant passage with an inlet for receiving the coolant from the cooling jacket housing and for injecting the coolant into a flow of exhaust received from the exhaust manifold through the cooling jacket housing.

17. The method of claim 14 comprising simultaneously mounting the exhaust elbow and cooling jacket housing to the exhaust manifold by inserting at least one fastener through aligned mounting holes in the exhaust elbow and cooling jacket housing and securing the fastener to the exhaust manifold.