Engine assembly with valve seat vent passages and method of forming

The present disclosure relates to engine cylinder head intake ports.

This section provides background information related to the present disclosure which is not necessarily prior art.

Engine assemblies may include a cylinder head defining an intake port having a valve seat insert disposed therein. The interface between the valve seat insert and the cylinder head may include a small gap allowing for the introduction of fuel during injection events. This small gap may trap the fuel between the valve seat insert and cylinder head. In engines burning fuel containing higher percentages of ethanol, this trapped fuel may result in corrosion of the cylinder head. One solution to this problem has been to form passages in the valve seat insert. However, the use of these modified valve seat inserts requires extensive modification to dies used in the manufacture of the traditional inserts or additional expensive machining of existing inserts.

This section provides a general summary of the disclosure, and is not comprehensive of its full scope or all of its features.

An engine assembly may include an engine block defining a cylinder bore, a cylinder head fixed to the engine block, and a valve seat insert. The cylinder head may include an intake port, defining an inlet in fluid communication with an air source and an outlet in fluid communication with the cylinder bore. The valve seat may be defined at the outlet of the intake port and may include a stepped region. The stepped region may define a seating surface extending radially outward from the intake port. The seating surface may include a series of protrusions circumferentially spaced from one another around the outlet and forming a series of recesses therebetween. The valve seat insert may be located within the stepped region and may include a first axial end surface abutting the protrusions on the seating surface.

A method of forming a cylinder head may include casting a cylinder head defining an intake port including a valve seat at an outlet of the intake port. The valve seat may define a stepped region having a seating surface extending radially outward from the intake port. The method may further include forming a series of circumferentially spaced recesses in the seating surface separated by a series of protrusions. A valve seat insert may be secured within the stepped region. The valve seat insert may include an axial end surface abutting the protrusions after the securing.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1 is a schematic illustration of a portion of an engine assembly according to the present disclosure;

FIG. 2 is a fragmentary section view of a cylinder head of the engine assembly of FIG. 1 ;

FIG. 3 is a plan view of the cylinder head of FIG. 2 ;

FIG. 4 is a perspective view of a valve seat insert of the engine assembly of FIG. 1 ;

FIG. 5 is a fragmentary section view of the cylinder head of FIG. 2 in an initial state; and

FIG. 6 is a perspective view of a tool according to the present disclosure.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

Examples of the present disclosure will now be described more fully with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

Referring to FIGS. 1-4 , an engine assembly 10 may include an engine block 12 , a cylinder head 14 , a valve seat insert 16 , and a valve 18 . The engine block 12 may define a cylinder bore 20 . The cylinder head 14 may be fixed to the engine block 12 and may define an intake port 22 and a valve seat 24 .

The valve seat 24 may be defined as an outlet of the intake port 22 and may include a stepped region 26 . The stepped region 26 may include an axial end surface 28 , an inner radial surface 30 , protrusions 32 , and recesses 34 . The cylinder head features discussed above may be formed integrally as a single casting. Alternatively, the protrusions 32 and recesses 34 may be formed in the cylinder head 14 after casting.

The valve seat insert 16 may include an annular body 36 having an outer radial surface 38 , an inner radial surface 40 , a first axial end surface 42 , a second axial end surface 44 , and a valve seating surface 46 . The first axial end surface 42 may define a generally continuous planar surface. The valve seat insert 16 may be located within the valve seat 24 of the cylinder head 14 . More specifically, the first axial end surface 42 may abut the protrusions 32 on the stepped region 26 . The outer radial surface 38 of the valve seat insert 16 may abut and be frictionally engaged with the inner radial surface 30 of the stepped region 26 , securing the valve seat insert 16 within the valve seat 24 .

During engine operation, an air and fuel mixture may be provided to the intake port 22 . The valve 18 may be selectively displaced from the valve seat insert 16 to provide communication between the intake port 22 and the cylinder bore 20 , allowing the air and fuel mixture to travel to the cylinder bore 20 . The valve seat insert 16 and the stepped region 26 may cooperate to define an annular recess 48 therebetween. The protrusions 32 , the recesses 34 , and the first axial end surface 42 may define a series of radial passages 49 providing fluid communication axially between the valve seat insert 16 and the valve seat 24 of the cylinder head 14 . The radial passages 49 may generally allow fuel present in the intake port 22 to travel freely between the first axial end surface 42 of the valve seat insert 16 and the valve seat 24 of the cylinder head 14 . Allowing this free flow of fuel may limit formation of corrosive byproducts, or acids, between valve seat insert 16 and the valve seat 24 .

The valve seat 24 of the cylinder head 14 may be formed in a variety of ways. With reference to FIGS. 5 and 6 , in a first non-limiting example, the cylinder head 14 may be formed as a casting and the recesses 34 may be formed by a deforming process. After casting, the valve seat 24 may define a generally planar surface 50 . In a non-limiting example, the valve seat 24 may be machined after casting to define the planar surface 50 . A tool 52 may be forced against the planar surface 50 to create the recesses 34 .

The tool 52 may include a series of protrusions 54 circumferentially spaced by recesses 56 . The tool 52 may be formed from a material having a greater hardness than the planar surface 50 of the cylinder head 14 . By way of non-limiting example, the cylinder head 14 may be cast from aluminum and the tool 52 may be formed from hardened steel. The protrusions 54 may include a variety of shapes for forming the recesses 34 in the planar surface 50 . In the present non-limiting example, the protrusions 54 are shown having a generally arcuate shape. However, it is understood that the protrusions 54 may take on any shape suitable to form the recesses 34 in the planar surface 50 .

As discussed above, the tool 52 may be forced against the planar surface 50 to create the recesses 34 . The tool 52 may be forced in a direction generally perpendicular to the planar surface 50 and the protrusions 54 may engage and deform the planar surface 50 , forming the recesses 34 . More specifically, the protrusions 54 may indent the planar surface 50 , forming the recesses 34 on the stepped region 26 of the cylinder head 14 . The planar surface 50 may be free from engagement with the tool 52 at the recesses 56 on the tool 52 . Alternatively, the recesses 56 may abut the planar surface 50 to form a stop for the tool 52 .

It is understood that the recesses 34 may be formed in a variety of alternate ways. In a first alternate method, the recesses 34 may be machined into the axial end surface 28 after the cylinder head 14 has been cast. In yet another method, the protrusions 32 and recesses 34 may be cast into the cylinder head 14 during formation thereof.