Air injection system for engine exhaust gases

Abstract

Apparatus for supplying supplemental air to exhaust gases exiting exhaust ports in a wall of a cylinder head of a multi-cylinder internal combustion engine and entering runners of an exhaust manifold through runner inlet ports aligned with the respective exhaust ports. An air injection plate is interposed between the cylinder head and the manifold. The air injection plate has openings aligned and registering with the respective exhaust ports and runner inlet ports. A fitting directs the supplemental air to the air injection plate openings to combine with the exhaust gases passing from the exhaust ports to the runner inlet ports.

Description

FIELD OF THE INVENTION

[0001] This invention relates to apparatus for supplying supplemental air to exhaust gases exiting from the cylinder head of an internal combustion engine.

BACKGROUND OF THE INVENTION

[0002] To reduce tailpipe non-methane hydrocarbon (NMHC) emissions during engine warm-up, supplemental air is often added to the exhaust gases. The supplemental air induces combustion in the exhaust manifold. The induced combustion burns excess fuel, reducing NMHC emissions and creating heat which transfers to the catalyst substrate. The catalyst is brought up to a functional temperature faster by this heat transfer, thus further decreasing cumulative NMHC tailpipe emissions. Cumulative NOx and CO are also reduced due to faster catalyst warm-up.

[0003] To supply the supplemental air, an air pump is employed. The supplemental air is transferred to the stream of exhaust gases as close to the engine exhaust valve as possible to maximize combustion in the manifold. On many engines, passages for supplemental air are designed into the cylinder head. While such air passages are the ideal way to introduce supplemental air, they are generally very expensive to add unless they are included in the initial cylinder head design. When adding a supplemental air system to an existing engine, an alternative method of supplying the supplemental air is needed.

SUMMARY OF THE INVENTION

[0004] In accordance with the present invention, apparatus is provided to supply supplemental into the exhaust stream close to the exhaust valve but without significant modification of the cylinder head. An air injection plate at the interface between the cylinder head and the manifold has openings aligned with exhaust ports of the cylinder head and runner inlet ports of the manifold.

[0005] A gasket forms a seal between the air injection plate and a wall of the cylinder head. The gasket has an aperture which encompasses more than one of the openings in the air injection plate. Supplemental air is introduced to a space or chamber within the aperture defined between the air injection plate and the cylinder head wall. The supplemental air is supplied to a fitting installed in an exhaust manifold inlet flange, and passes from the fitting into the chamber. Preferably the air injection plate has grooves defining paths for the supplemental air which lead to the openings in the air injection plate. The supplemental air at the openings in the air injection plate enters the exhaust stream passing from the exhaust ports of the cylinder head into the inlet ports of the runners of the manifold.

[0006] One object of this invention is to provide apparatus for supplying supplemental air into an exhaust stream having the foregoing features and capabilities.

[0007] Another object is to provide apparatus for supplying supplemental air which is composed of a relatively few simple parts, is rugged and durable in use, and is capable of being inexpensively manufactured and installed.

[0008] Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present invention will become more fully understood from the detailed description and accompanying drawings, wherein:

[0010] FIG. 1 is an exploded view in perspective of apparatus constructed in accordance with this invention.

[0011] FIG. 2 is an elevational view of a gasket forming part of the apparatus shown in FIG. 1.

[0012] FIG. 3 is an elevational view of an air injection plate forming part of the apparatus shown in FIG. 1. The side of the air injection plate shown in FIG. 3 is opposite the side shown in FIG. 1.

[0013] FIG. 4 is an elevational view of another gasket forming part of the apparatus shown in FIG. 1.

[0014] FIG. 5 is a sectional view of a portion of the apparatus, taken on the line 5—5 in FIG. 3.

[0015] FIG. 6 is a sectional view taken on the line 6—6 in FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] Referring now more particularly to the drawings, a cylinder head 10 of an internal combustion engine 11 has a plurality of laterally spaced apart exhaust ports 12, 14, 16 and 18 extending through a flat outer wall 20 of the cylinder head. A manifold 22 has a plurality of runners 24, 26, 28 and 30 leading to a main manifold outlet 32. The manifold runners have runner inlet ports 34, 36, 38 and 40 aligned and registering with the respective exhaust ports 1218. Exhaust gases from the cylinder head flow into the runners and from the runners to the main outlet 32 where such gases may be routed through a catalytic converter.

[0017] An integrated air injection rail (I.A.I.R.) 42 is placed between the wall 20 of the cylinder head and the inlet ports 34-40 of the manifold runners. The I.A.I.R. 42 consists of an air injection plate 44 and gaskets 46 and 48 on opposite sides of the air injection plate.

[0018] The air injection plate 44 has openings 50, 52, 54 and 56 aligned and registering with the respective exhaust ports 12-18 in the cylinder head wall 20 and inlet ports 34-40 of the runners.

[0019] The gasket 46 forms a seal between the cylinder head wall 20 and one face of the air injection plate 44. An aperture 58 in the gasket 46 has a peripheral edge 60 encompassing the exhaust ports 12 and 14 and the registering openings 50 and 52 in the air injection plate 44. A space or chamber 62 (FIG. 5) in defined between the face of the air injection plate 44 and the cylinder head wall 20, within the peripheral edge 60 of the aperture 58. The gasket 46 is very thin, preferably on the order of about 0.25 mm so that the chamber 62 is correspondingly thin. The thickness of the gasket 48 is also preferably about 0.25 mm.

[0020] An air fitting 64 mounted in a flange 66 of the manifold 22 communicates with the chamber 62 through a hole 68 in the gasket 48 and a hole 70 in the air injection plate 44 to introduce supplemental air from an air pump (not shown) into the chamber. Grooves 74 (FIGS. 3 and 5) in the face of the air injection plate 44 extend from the hole 70 to the two openings 50 and 52 in the air injection plate. The grooves 74 have branches 76 which open into the openings 50 and 52 at several spaced points to facilitate the flow of supplemental air to the openings.

[0021] A second aperture 80 in the gasket 46 has a peripheral edge 82 encompassing the exhaust ports 16 and 18 and registering openings 54 and 56 in the air injection plate 44. A space or chamber 84 is defined between the face of the air injection plate 44 and the cylinder head 20, within the peripheral edge 82 of the aperture 80. An air fitting 86 is mounted in a flange 88 of the manifold 22 and communicates with the chamber 84 through a hole 90 in the gasket 48 and a hole 92 in the air injection plate 44 to introduce supplemental air from an air pump (not shown) into the chamber 84. Grooves 94 in the face of the air injection plate 44 extend from the hole 92 to the two openings 54 and 56 in the air injection plate. The grooves 94 have branches 96 which open into the openings 54 and 56 at several spaced points to facilitate the flow of supplemental air to the openings.

[0022] The air injection plate 44 is preferably about 3 mm in thickness. The depth of the grooves is preferably about 2 mm. The grooved air injection plate 44 may be formed by any suitable means, such, for example as coining, forging, or by using sintered metal.

[0023] The grooves 74 and 94 enable a free flow of supplemental air to the openings 50-56 and are very desirable because of the extreme thinness of the chambers 62 and 84.

[0024] The gasket 48 has openings 100, 102, 104 and 106 aligned and registering with the respective openings 50-56 in the air injection plate 44 and the runner inlet ports 34-40. The gasket forms a seal between the manifold 22 and the air injection plate 44 around the runner inlet ports 34-40 and the openings 50-56 in the air injection plate.

[0025] Fasteners 110 secure together the cylinder head 10, manifold 22, air injection plate 44 and gaskets 46 and 48.

[0026] The supplemental air delivered to the openings 50-56 of the air injection plate 44 combines with the exhaust stream passing from the exhaust ports 12-18 of the cylinder head 20 into the inlet ports 34-40 of the runners 24-30 of the manifold 22.

[0027] The description of the invention is merely exemplary in nature and, thus, variations that do not depart form the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Claims

1. Apparatus for supplying supplemental air to exhaust gases exiting exhaust ports in a wall of a cylinder head of a multi-cylinder internal combustion engine and entering runners of an exhaust manifold through runner inlet ports aligned with the respective exhaust ports, comprising:

an air injection plate interposed between the cylinder head and the manifold,

said air injection plate having openings aligned and registering with the respective exhaust ports and runner inlet ports, and

means for directing the supplemental air to the air injection plate openings to combine with the exhaust gases exiting the exhaust ports and entering the exhaust manifold through the runner inlet ports.

2. The apparatus of claim 1, wherein said means for directing the supplemental air includes a fitting for directing air into a hole in said air injection plate, and grooves in one surface said plate extending from said hole to a plurality of the openings in said plate, said grooves defining air paths from said hole to said plurality of the openings.

3. The apparatus of claim 1, wherein said means for directing the supplemental air to the injection plate openings includes a gasket sealing between one surface of said air injection plate and the wall of the cylinder head, said gasket provided with an aperture having a marginal edge encompassing a plurality of said openings in said plate, a chamber defined by said one surface of said plate and said wall of the cylinder head within the marginal edge of the aperture, and means for introducing supplemental air into said chamber.

4. The apparatus of claim 3, wherein said means for introducing supplemental air into said chamber includes an air fitting carried by said exhaust manifold, said fitting opening into said chamber through a hole in said air injection plate.

5. The apparatus of claim 4, wherein said one surface of said plate has grooves defining air paths leading from the hole in said air injection plate to said respective plurality of openings.

6. The apparatus of claim 5, wherein said grooves have branches which open into each of said plurality of openings at a plurality of spaced points.

7. The apparatus of claim 6, further including a second gasket sealing between a second surface of said plate and said manifold having openings aligned and registering with the openings in said plate and the runner inlet ports.