Valve guide relining sleeve

A sleeve for lining a valve guide of an internal combustion engine and being able to receive a valve stem therethrough, has a seam that extends the length thereof. The inner surface of the sleeve has a plurality of spaced apart indentations. The indentations are formed in rows down the sleeve and each row has at least two identations.

FIELD OF INVENTION 
The present invention relates to a sleeve for lining a valve guide of an 
internal combustion engine so as to ensure that the valve stem receives 
adequate lubrication during its oscillatory movement within the guide 
whilst substantially eliminating the migration of oil to the combustion 
chamber. 
BACKGROUND ART 
Australian Patent Specification No. 586,341 discloses a slitted tubular 
valve guide insert having a substantially spiral groove along the entire 
length of its inner surface. At each point of intersection between the 
spiral groove and the slit or seam, the adjacent open ends of the 
substantially spiral groove are offset to create a linear discontinuity in 
the spiral groove. The spiral groove is, therefore, divided into a 
plurality of inclined groove segments. It is suggested in Australian 
Patent Specification No. 586,341 that by dividing the substantially spiral 
groove into a plurality of inclined, discrete groove segments, oil flow 
along the substantially spiral groove to the combustion chamber will be 
greatly reduced or eliminated during operation of the engine. 
It has however, been found by the present inventor that during engine 
operation, the above arrangement suffers from a gradual leakage of oil 
down each of the inclined groove segments to the seam, where the 
accumulated oil passes downwardly to be released into the combustion 
chamber. Furthermore, the provision of a transverse portion to the seam 
does not significantly inhibit such oil flow. Whilst it is suggested that 
the combined effect of the oscillatory and rotational movement of the 
valve stem through the valve guide is to pick up and evenly spread the oil 
that is in the groove segments throughout the surface of the valve stem, 
it has been found by the present inventor that much of the oil that is 
within each of the groove segments is not picked up by the surface of the 
moving valve stem as it abuts against the innermost face of the valve 
guide but rather spills out into the seam. 
The effect of having a succession of groove segments that open out into the 
seam coupled with having a single transverse portion of the seam where 
misalignment of the corresponding opposite edges of the sleeve is likely 
to occur are seen by the present inventor as the primary causes of this 
spillage. As a result, accumulated oil loss to the combustion chamber 
still occurs at unsatisfactorily high levels. 
It is an object of the present invention to substantially ameliorate the 
disadvantages of the prior art. 
DISCLOSURE OF THE INVENTION 
According to the invention there is provided a sleeve for lining a valve 
guide of an internal combustion engine and adapted to receive a valve stem 
therethrough, said sleeve having a seam extending the length thereof, the 
inner surface of the sleeve having a plurality of spaced apart elongated 
indentations, the spacing of the indentations being such that they are 
formed in rows down the sleeve with each row being comprised of at least 
two spaced apart indentations. 
Preferably, the direction of elongation of each indentation in each row is 
perpendicular to the longitudinal axis of the sleeve. 
In another preferred form, the indentations of one row are staggered in 
relation to the indentations of an adjacent row. 
In a further preferred form, each indentation from any one row has at least 
one end portion thereof that overlaps an end portion of an identation of 
an adjacent row according to an axial line of reference. 
The successive rows of identations may be interrupted by a portion or 
portions of the sleeve lacking rows of indentations, and, where there is a 
single such portion, said portion may be located substantially adjacent to 
the midpoint of the length of the sleeve. 
Preferably, the elongated indentations are rectangular in shape and the 
outermost indentations of each row do not intersect across the seam.

DESCRIPTION OF PREFERRED EMBODIMENT 
The valve assembly of FIG. 1 has a valve guide 10 housing a valve stem 11. 
A sleeve 12 is inserted by interference fit against the wall of the valve 
guide 10 and closely abuts against the valve stem 11. The sleeve 12 will 
be described in more detail below. A valve spring 13 encircles the upper 
portion of the valve guide 10. A pair of valve keepers 14 retain the valve 
stem 11 in its operative position. The valve stem 11 extends downwardly 
into an engine combustion chamber 15 and terminates in a valve face 16. In 
its recipratory movement, the valve face 16 is periodically received by a 
seat 17 to the combustion chamber 15 by upward force of the spring 13 and 
is caused to move away rom the seat 17 by operation of the rocker arm 18. 
The sleeve 12 shown in FIG. 2 is a cylindrical shape and has an end to end 
seam 19 that defines a lock tag arrangement 20 at the midpoint thereof. 
The seam 19 is, therefore, divided into three longitudinally oriented seam 
lines that provide for tight alignment between the complementary side 
portions 21 and 22 of the sleeve 12 when it assumes an interference fit 
within the valve guide 10. 
The developed inner surface of the sleeve 12 shown in FIG. 3 has a series 
of rows of evenly spaced apart rectangular indentations 23 pressed 
therein. The longitudinal axis of each rectangular indentation 23 is 
perpendicular to the longitudinal axis 25 of the sleeve 12. The 
rectangular indentations 23 of any one row are staggered in relation to 
the rectangular indentations 23 of the adjacent row. When viewed according 
to an axial line of reference, each rectangular indentation 23 partly 
overlaps an adjacent staggered rectangular indentation 23. 
The portion 24 of the sleeve 12 located adjacent its midpoint lacks rows of 
indentations. This is because most of the wear between stem 11 and sleeve 
12 occurs at opposite ends of the sleeve remote from the midpoint. 
Although not drawn to scale, the most peripheral rectangular indentations 
23 of each row come to within 1 millimeter of either of the side portions 
21 and 22. It is important that care be taken in the manufacture of the 
preferred sleeve 12 to ensure that none of the indentations 23 intersect 
the seam line 19 as even with the improved seam alignment profile of this 
embodiment some spillage of oil from an indentation having an opening to 
the seam may occur, albeit in small amounts and infrequently. 
Preferably the sleeve 12 is constructed of a phosphor bronze material which 
does not absorb lubrication oil as would more porous sleeve materials such 
as cast iron. 
Preferably the rectangular indentations 23 are approximately 3 millimeters 
(mm) in length, 0.25 mm in width and 0.12 mm in depth. 
The fitting of the sleeve 12 into the valve guide 10 is by conventional 
means. 
Various modifications may be made in details of design and construction 
without departing from the scope or ambit of the invention.