GB1588052A - Engine housing component and method of manufacture thereof - Google Patents

Description

(54) AN ENGINE HOUSING COMPONENT AND METHOD OF MANUFACTURE THEREOF (71) We, FORD MOTOR COMPANY LIM ITED, of Eagle Way, Brentwood, Essex CM 13 3BW, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to an engine housing component and to a method of making the component.

With the advent of stricter governmental controls for engine emissions and with increased concern being given to weight reduction of passenger vehicles to economize fuel, there is a need for conserving the residual heat of exhaust gases of internal combustion engines so that a vehicle exhaust system may operate with simplicity and effectiveness to reduce the emission levels of the engine. This need has become quite apparent to the automotive industry and is currently under intense development effort. Any solution to this problem must be durable and yet not introduce any additional problems. Heat loss experi enced by exhaust gases as they travel from the combustion zone through the withdrawal exhaust passage of the engine head to the exterior exhaust tubing, can be considerable Such heat loss is accomplished by conduction, convection and radiation.The ability to maintain a sufficiently high temperature in the exhaust gases of an internal combustion engine has not been fully attainable at reasonable costs by the prior art. Insulating implants have been placed in engine housing components to retard the loss of heat through the withdrawal passage of the engine. Fabrication and installation of such insulating implants has been a most difficult problem.

For example, if a single-walled metal liner of exotic material containing a high content of nickel (the outside of which is covered with casting sand to form an air gap in the final casting) were to be placed into a casting mold and molten cast iron thereabout, serious damage of the liner may occur. It has been found that exotic materials, although having great strength at high temperatures, do have a lower melting temperature. Thus, during casting, such exotic materials are sensitive to the heat conducted to them and are distorted or completely destroyed by the casting of molten iron about them. Refractory coatings and implants of conventional fibrous insulation have not proven of considerable value, except as an economical expedience.

According to the invention a method of making an insulated passage within an engine housing component, comprises: (a) selecting at least three but no more than four continuous ferrous-based sheet metal pieces, (b) with at least one piece forming a hollow cylindrical tube having the margins along opposite edges thereof defined as first flanges extending laterally outwardly therefrom, with two other pieces forming each as a hemicylindrical wall with the margins along opposed side edges thereof forming second flanges extending laterally outwardly therefrom, (c) placing said hemi-cylindrical shapes in contiguous relation with the flanges mating and forming an enclosed cylindrical space, (d) nesting said tube within said mated hemicylinders to form an assembly in which said first and second flanges are in contiguous sandwiched relation, (e) deforming said assembly at each end to close the space between said tube and hemicylinders, (f) bonding said sandwiched flanges together and bonding said deformed ends to said tube to form a double-ply implant assembly with a totally closed air space therebetween, and (g) casting molten aluminium about said assembly to form an engine housing component with a passage defined by said assembly.

According to another aspect of the inven tion an engine housing component having an insulated passage comprises: (a) a body of aluminium having first walls defining at least part of a chamber in which combustion of said engine is carried out, said body also having second walls defining a passage communicating said chamber with an outwardly facing side of said housing, (b) a cylindrically configured liner assembly extending substantially throughout said passage, said assembly having cylindrically shaped radially spaced ferrous-based sheet metal walls enclosing a trapped air space therebetween, the outer cylindrical wall being mechanically trapped within said aluminium body.

The invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a sectional view of an internal combustion engine showing an engine head having the implant fabricated in accordance with this invention: Figure 2 is an enlarged sectional view of the implant assembly; and Figure 3 is a fragmentary sectional view taken substantially along line 3-3 of Figure 2.

The goal of this invention is to provide an apparatus that will assist an internal combustion engine to produce lower emissions in the raw exhaust. It is also helpful if the invention programs the raw exhaust gas for better efficiency in applications where a thermal reactor is utilized to modify the raw exhaust gas. This is accomplished by two features (a) reduction of the heat transfer coefficient through walls defining a reaction passage immediately downstream of the exhaust valve, and (b) rearranging the combustion process to assure excess oxygen in said passage. One engine mode, according to this invention, which meets these goals, is shown in Figure 1. The engine 10 has a cast aluminium head 30 and cast block 31 which may be aluminium or iron.The block has one or more cylinders 11 within which is disposed a piston 12 reciprocally operating therein; a connecting rod 13, forming part of a driven means includes a crankshaft, not shown. The head has a chamber 32 which completes definition of the combustion chamber along with the cylinder 11 and piston 12.

The engine utilizes a stratified charge combustion process for creating programmed exhaust constituents having excess oxygen.

A line implant assembly, according to this invention, is used in the exhaust passage of the engine head and a thermal reactor is also used. The induction system 9 for the engine has a primary intake passage 15 effective to convey a lean phase of a combustible mixture from carburetor 14 to the chamber 32. A separate carburetor 34 is used to introduce a rich mixture into a small prechamber 54 defined by cylindrical wall 55; the prechamber has an induction port 53 controlled by an induction valve 52. The induction valve 52 and primary intake valve 19 are coordinated by a suitable actuating assembly 50. The spark plug 51 is located so as to ignite the mixture solely within the prechamber 54 (as opposed to locating the spark plug in the main cylinder as in the embodiment of Figure 1).The mixture in the prechamber will burn fast, thoroughly and operate to ignite the mixture in the upper region 32 of the main chamber 11 by the way of a torch effect which exits from the prechamber through a nozzle 56 or suitable port opening. The gas in the prechamber will burn extremely fast and thoroughly. The temperature drops as the flame spreads to the main chamber where the lean mixture will burn more slowly. This minimizes hydrocarbon emissions without creating undue nitrogen oxide compounds.

The CO is kept low by operating the engine with the largest percentage of the mixture being very lean. Since the engine is a fourcycle engine, the induction phase, where the combustible mixture is sucked into both the main chamber and prechamber, will draw a portion of the rich phase into a small upper region 32 of the main chamber 11 through the nozzle 56; however, upon the compression stroke, the rich phase will, of course, return to the prechamber, after having been somewhat diluted by the lean mixturee entering past the primary intake valve 19, where it will be ignited by the spark plug 51 located solely therein. To this end, the upper region 32 of the main chamber 11 should be made non-symmetrical so that it facilitates the return of the rich phase during the compression cycle.Furthermore, the spark plug 51 should be recessed in such a manner that the induction of the rich phase will pass into the prechamber in a manner so as not to foul the spark plug.

To insure that excess oxygen and programmed exhaust emissions result, the volume of the prechamber should be smaller in comparison to the main chamber 11 and probably should not be greater than 10%. Nozzle 56 or other equivalent communicating port should be sized in relationship to the venturi controlling the induction of the air/fuel mixture into the prechamber. It is appropriate that the air/fuel mixture inducted into the prechamber should be preheated as the fuel/mixture is preheated for induction into the main chamber; this can be accomplished by heat exchange with the exhaust gases.

The exhaust system for the engine comprises a relatively short passage 16 extending from the upper region 32 to the exterior surface 24 of the engine head (traversing a distance 23). Valves 19 and 20 are utilized respectively to control the intake port 17 and exhaust port 18.

To further reduce and modify the harmful emissions eminating from the engine, a thermal reactor 25 is typically employed, although a catalytic converter may serve a comparable function. The thermal reactor receives the exhaust gases through passage 27 which conducts such gases to an inner chamber 28 where the gases are turbulated and permitted a predetermined dwell time for oxidizing said harmful emissions. After suffi- cient turbulization and mixing within the thermal reactor, the exhaust gases are bled to an outer chamber 36 at one end of the reactor and ultimately passed along an outlet passage 37. Suitable thermal walls are employed to retain the heat of the thermal reactor for improving efficiency since appropriate temperature of the exhaust gases is çritical for chemical reactivity.

Turning now more specifically to the head 30, it is comprised of cast aluminium defining a body having first walls which form at least part of a chamber 32 in which internal combustion is carried out. The body of aluminium further defines second walls 16 forming a passage communicating said chamber with an outwardly facing side 24 of the housing. Such passage here constitutes the exhaust passage which in past prior art constructions has usually conformed to a somewhat L-shaped configuration with the cylindrical interior shape modified to accommodate cooling passages 38 and 39 surrounding the passage.

The exhaust passage contains a cylindrical liner assembly 40 extending substantially throughout the entire length 23 of said passage. The liner assembly is comprised of cylindrically shaped, radially spaced, ferrousbased sheet metal walls.

As shown in Figures 2 and 3, the inner wall 41 is preferably comprised of a stainless steel to withstand the corrosive effects of high temperature exhaust gases and the outer cylindrical wall 42 is preferably constituted of carbon steel. The walls are maintained in radially spaced relation by deforming the leading edges 43 and trailing edges 44 of the outer wall to form a closure thereby trapping air within the space 45 extending along said length and between said walls. The closed dead space may be formed by drawing the outer cylindrical wall tightly against the inner wall and sealing by way of an annular enveloping weld 46. The space may also be controlled by drawing other locations of the cylindrical walls together at predetermined locations, such as at 47 as demanded by unusual contours to accommodate exhaust valve penetration 20.Suitable weld 48 may be used to mate the walls at 47. However, it is preferable that such cylindrical walls be more streamlined and be devoid of any unusual contours.

The radial spacing between said inner and outer walls is preferably maintained at a distance of about 2 5 mm and the length of the air gap is as long as possible within the confines of the cylinder head design. The thickness of the metal pieces constituting said liner assembly is in the range of 10-20 mm and preferably about 1-5 mm.

The outer cylindrical wall is mechanically trapped within said aluminium body, such as may occur as a result of casting molten aluminium about said liner assembly.

A modification of the single air space employed in the preferred embodiment would be to bond temporarily a layer of sand, e.g. a sand core, to the exterior of the assembly during casting; such sand may be removed conveniently through access openings after having cast molten aluminium about the assembly. This produces a double air gap about the cylindrical tube, the inner air gap being trapped between the pieces of sheet metal in the liner assembly and the other air gap being established, as result of the casting sequence, between the implant assembly and the body of solidified aluminium and closed by supplemental elements during assembly of the engine.

To stabilize the joint between the latter assembly and the cast aluminium body thereabout, and also to facilitate fabrication of the liner assembly, flanges 49a, 49b, 49c and 49d may be provided which extend radially outwardly from opposite sides of the latter assembly. Said flanges not only extend outwardly, but also extend substantially along the length of the assembly. The flanges are enveloped by the cast aluminium body thereabout and serve to stabilize the structure within the housing.

A preferred method for carrying out the method aspects of this invention, comprises (a) selecting at least three but no greater than four pieces of ferrous-based sheet metal, (b) with at least one piece, forming a hollow cylindrical first tube 60 having opposite edges 60a and 60b of said piece meeting to define first flanges 49b and 49c extending laterally outwardly from at least one side (if two pieces are used, the pieces are formed as hemi-cylinders and each have flanges 49b mated at opposite sides to the flanges 49c of the other pieces), (c) with at least two of the other pieces, forming from each a hemicylinder 61 and 62 with the margins of opposed side edges 61a and 62a forming second flanges 49a and 49d extending laterally outwardly therefrom, (d) placing the hemi-cylinders with the flanges in contiguous contact as in Figure 3; sealingly mating said flanges (such as by welding) so as to form a cylindrical space 64 interrupted by flanges 49b abd 49c, (e) deforming the leading edges 43 and trailing edges 44 of said assembly together to close said space 64, and bonding said deforming portions at 46 and (g) casting molten aluminium about said liner or implant assembly to form an engine component having a passage defined by said liner. It is important that the molten aluminium cast thereabout be able to contact and entrap the leading edges 43, the trailing edges 44 and the area of valve penetration 47 of said liner assembly.

WHAT WE CLAIM IS: 1. A method of making an insulated passage within an engine housing component, comprising: (a) selecting at least three but no more than four continuous ferrous-based sheet metal pieces, (b) with at least one piece, forming a hollow cylindrical tube having the margins along opposite edges thereof defined as first flanges extending laterally outwardly therefrom, with two other pieces forming each as a hemicylindrical wall with the margins along opposed edges thereof forming second flanges extending laterally outwardly therefrom, (c) placing said hemi-cylindrical shapes in contiguous relation with the flanges mating and forming an enclosed cylindrical space, (d) nesting said tube within said mated hemi-cylinders to form an assembly in which said first and second flanges are in contiguous sandwiched relation, (e) deforming said assembly at each end to close the space between said tube and hemicylinders, (f) bonding said sandwiched flanges together and bonding said deformed ends to said tube to form a double-ply implant assembly with a totally closed air space therebetween, and (g) casting molten aluminium about said assembly to form an engine housing component with a passage defined by said assembly.

2. The method as in Claim 1, in which the thickness of said pieces is in the range of 1 0 to 20 mm.

3. The method as in Claim 1, in which said one piece is constituted of stainless steel, and said two other pieces are constituted of carbon steel.

4. The method as in Claim 1, in which prior to completion of step (g), a layer of sand is temporarily bonded to the exterior of said implant assembly, and said sand and implant assembly being placed in a mold such that after having cast molten aluminium thereabout according to step (f), said sand may be removed from said casting, whereby a double air gap is established about said hollow cylindrical tube, one air gap being established between said pieces of sheet metal, the other air gap being established between the implant assembly and the body of solidified aluminum.

5. An engine housing component having an insulated passage, comprising: (a) a body of aluminium having first walls defining at least part of a chamber in which combustion of said engine is carried out, said body also having second walls defining a passage communicating said chamber with an outwardly facing side of said housing, (b) a cylindrically configured liner assembly extending substantially throughout said passage, said assembly having cylindrically shaped radially spaced ferrous-based sheet metal walls enclosing a trapped air space therebetween, the outer cylindrical wall being mechanically trapped within said aluminum body.

6. The housing component as in Claim 5, in which the interior walls of said assembly are comprised of a stainless steel metal and the exterior walls are comprised of plain carbon steel.

7. The housing component as in Claim 5, in which said outer wall of said liner assembly is continuously mechanically trapped along substantially its entire surface to said aluminium body by casting of that aluminium body about the liner assembly.

8. The housing component as in Claim 5, in which the outer sheet metal wall of said liner assembly is mechanically trapped within said aluminum body at the leading edges, trailing edges, and valve penetration area of said outer sheet metal wall.

9. The housing component as in Claim 5, in which each of said cylindrical walls have flanges extending radially outwardly from opposite sides thereof and extending substantially along the length of said liner assembly, said flanges being enveloped by said surrounding cast body for stabilizing and adding additional surface for mechanical entrapment of said liner assembly within the aluminum body.

10. A method of making an engine hous

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   43 and trailing edges 44 of said assembly together to close said space 64, and bonding said deforming portions at 46 and (g) casting molten aluminium about said liner or implant assembly to form an engine component having a passage defined by said liner. It is important that the molten aluminium cast thereabout be able to contact and entrap the leading edges 43, the trailing edges 44 and the area of valve penetration 47 of said liner assembly.

   WHAT WE CLAIM IS: 1. A method of making an insulated passage within an engine housing component, comprising: (a) selecting at least three but no more than four continuous ferrous-based sheet metal pieces, (b) with at least one piece, forming a hollow cylindrical tube having the margins along opposite edges thereof defined as first flanges extending laterally outwardly therefrom, with two other pieces forming each as a hemicylindrical wall with the margins along opposed edges thereof forming second flanges extending laterally outwardly therefrom, (c) placing said hemi-cylindrical shapes in contiguous relation with the flanges mating and forming an enclosed cylindrical space, (d) nesting said tube within said mated hemi-cylinders to form an assembly in which said first and second flanges are in contiguous sandwiched relation, (e) deforming said assembly at each end to close the space between said tube and hemicylinders, (f) bonding said sandwiched flanges together and bonding said deformed ends to said tube to form a double-ply implant assembly with a totally closed air space therebetween, and (g) casting molten aluminium about said assembly to form an engine housing component with a passage defined by said assembly.
2. 2. The method as in Claim 1, in which the thickness of said pieces is in the range of 1 0 to 20 mm.
3. 3. The method as in Claim 1, in which said one piece is constituted of stainless steel, and said two other pieces are constituted of carbon steel.
4. 4. The method as in Claim 1, in which prior to completion of step (g), a layer of sand is temporarily bonded to the exterior of said implant assembly, and said sand and implant assembly being placed in a mold such that after having cast molten aluminium thereabout according to step (f), said sand may be removed from said casting, whereby a double air gap is established about said hollow cylindrical tube, one air gap being established between said pieces of sheet metal, the other air gap being established between the implant assembly and the body of solidified aluminum.
5. 5. An engine housing component having an insulated passage, comprising: (a) a body of aluminium having first walls defining at least part of a chamber in which combustion of said engine is carried out, said body also having second walls defining a passage communicating said chamber with an outwardly facing side of said housing, (b) a cylindrically configured liner assembly extending substantially throughout said passage, said assembly having cylindrically shaped radially spaced ferrous-based sheet metal walls enclosing a trapped air space therebetween, the outer cylindrical wall being mechanically trapped within said aluminum body.
6. 6. The housing component as in Claim 5, in which the interior walls of said assembly are comprised of a stainless steel metal and the exterior walls are comprised of plain carbon steel.
7. 7. The housing component as in Claim 5, in which said outer wall of said liner assembly is continuously mechanically trapped along substantially its entire surface to said aluminium body by casting of that aluminium body about the liner assembly.
8. 8. The housing component as in Claim 5, in which the outer sheet metal wall of said liner assembly is mechanically trapped within said aluminum body at the leading edges, trailing edges, and valve penetration area of said outer sheet metal wall.
9. 9. The housing component as in Claim 5, in which each of said cylindrical walls have flanges extending radially outwardly from opposite sides thereof and extending substantially along the length of said liner assembly, said flanges being enveloped by said surrounding cast body for stabilizing and adding additional surface for mechanical entrapment of said liner assembly within the aluminum body.
10. 10. A method of making an engine hous

    ing component substantially as hereinbefore described with reference to the accompanying drawings.
11. 11. An engine housing component substantially as hereinbefore described with reference to and as shown in the accompanying drawings.