Lost foam engine block pattern

A lost foam pattern for an engine block includes a cylinder and an axially extending transfer passage defined by spaced side walls and an inner wall which is outwardly convex. The pattern further includes a first pattern piece including a wall defining a portion of a cylindrical bore having an axis, and a passage recess extending in the direction of the axis of the cylindrical bore and communicating with the cylindrical bore, which passage recess is defined by opposed walls extending axially with respect to the cylindrical bore and forming the spaced side walls of the transfer passage, a second pattern piece located in the passage recess, having a first arcuate wall forming a continuation of the cylindrical bore portion in the first pattern piece, having a second arcuate wall forming the inner wall of the transfer passage and being outwardly convex, and additional recesses and portions on the first and second pattern pieces for locating the pattern pieces relative to each other and for preventing relative movement therebetween except in the direction opposite the direction of assembly of the pattern pieces.

RELATED APPLICATIONS 
This application is related to my following co-pending applications: 
U.S. Ser. No. 202,970 Filed: June 3, 1988 Entitled "Lost, Foam Pattern 
Assembly For V-Block Engine" now allowed; 
U.S. Ser. No. 202,693 Filed: June 3, 1988 Entitled "Lost Foam Casting 
Assembly" now abandoned; 
U.S. Ser. No. 202,876 Filed: June 3, 1988 Entitled "Die Member For Forming 
A Lost Foam Pattern" now U.S. Pat. No. 4,872,637; 
U.S. Ser. No. 202,489 Filed: June 3, 1988 Entitled "Lost Foam Transfer 
Passage Cavity Construction" now U.S. Pat. No. 4,880,047. 
BACKGROUND OF THE INVENTION 
The invention generally relates to lost foam patterns for two-stroke engine 
blocks including a cylinder having an axis. More particularly, the 
invention relates to arrangements for providing such a lost foam engine 
block pattern with a transfer passage having an arcuate outer wall which 
is concave in a plane parallel to a plane extending from and containing 
the cylinder axis, having an arcuate inner wall which is convex in cross 
section in a plane parallel to a plane extending radially from and 
containing the cylinder axis, and having two generally axially extending 
walls joining the inner and outer arcuate walls. 
Attention is directed to the following United States Patents: 
______________________________________ 
4,243,093 Neiman, J. R. January 6, 1981 
4,632,169 Osborn, H. L. December 30, 1986 
4,640,333 Martin, et al. February 3, 1987 
4,657,063 Morris, R. L. April 14, 1987 
4,691,754 Trumbauer, et al. 
September 8, 1987 
4,721,149 Hesterberg, et al. 
January 26, 1988 
Re.31,488 Trumbauer January 10, 1984 
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In the past, such transfer passages as described above were provided by 
forming the lost foam engine block pattern from three slices or pieces as 
shown generally in the Osborn U.S. Pat. No. 4,632,169, issued Dec. 30, 
1986. In FIGS. 1 and 2 herein, the three pieces are identified by the 
numerals 11, 13, and 15 and the transfer passage is identified by the 
numeral 17. The inner and outer arcuate walls of the transfer passages are 
identified by the reference numerals 19 and 21. As shown, the transfer 
passage includes portions 31, 33, and 35, respectively located in each of 
the pattern portions or pieces 11, 13, and 15. The portion of the transfer 
passage in the piece or pattern portion 11 was provided by a die member 
which opened in the axial direction A. The transfer passage portion 35 
provided in the pattern piece 15 was obtained by a die member which opened 
in the opposite axial direction B. The middle portion 33 of the transfer 
passage 17 was provided by a partially illustrated first die member 41 
which was separated from the pattern portion 13 in the axial direction A 
and by a partially illustrated second die member 43 which was separated 
from the lost foam pattern piece or portion 13 in the axial direction B. 
Thus, in the past, formation of a lost foam engine block pattern with an 
arcuately extending transfer passage involved formation of the pattern 
from three pieces and also involved formation of the transfer passage in 
the middle piece by two die members which cooperated with each other and 
which were separated in opposite directions from the lost foam middle 
piece 13. 
The invention disclosed herein is directed to simplifying this procedure. 
SUMMARY OF THE INVENTION 
The invention provides a lost foam pattern for an engine block including a 
cylinder and an axially extending transfer passage defined by spaced side 
walls and an inner wall which is outwardly convex, the pattern comprising 
a first pattern piece including a wall defining a portion of a cylindrical 
bore having an axis, and a passage recess extending in the direction of 
the axis of the cylindrical bore and communicating with the cylindrical 
bore, which passage recess is defined by opposed walls extending axially 
with respect to the cylindrical bore and forming the side walls of the 
transfer passage, a second pattern piece located in the passage recess, 
having a first arcuate wall forming a continuation of the cylindrical bore 
portion in the first pattern piece, having a second arcuate wall providing 
the inner wall of the transfer passage and being outwardly convex, and 
means on the first and second pattern pieces for locating the pattern 
pieces relative to each. 
The invention also provides a lost foam pattern for an engine block 
including a cylinder having an axis, and an axially extending transfer 
passage having first and second portions, which first portion includes 
spaced axially extending side walls and spaced inner and outer walls 
connecting the side walls, which inner wall is outwardly convex and which 
outer wall is inwardly concave. The lost foam pattern comprises a first 
pattern piece including a wall defining a first portion of a cylindrical 
bore having an axis, a passage recess extending in the direction of the 
axis of the cylindrical bore and communicating with the cylindrical bore, 
which passage recess is defined by opposed axially extending walls at 
least partially forming the side walls of the transfer passage, and by a 
wall joining the opposed axially extending walls, being inwardly concave 
in a plane extending parallel to a plane extending radially from and 
containing the axis of the cylindrical bore, and forming the outer wall of 
the transfer passage, and respective pilot recesses located in each of the 
opposed axially extending walls, which pilot recesses open into the 
cylindrical bore and into the passage recess, a second pattern piece 
located in the passage recess and forming, with the first pattern piece, 
the first portion of the transfer passage, which second pattern piece has 
a first arcuate wall forming a continuation of the cylindrical bore 
portion in the first pattern piece, has a second arcuate wall forming the 
inner wall of the transfer passage and being outwardly convex in a plane 
extending parallel to a plane extending radially from and containing the 
axis of the cylindrical bore, has spaced walls located in the pilot 
recesses to locate the second pattern piece in proper position relative to 
the first pattern piece and to prevent movement of the second pattern 
piece relative to the first pattern piece except in a direction opposite 
to the direction of assembly of the first and second pattern pieces, and a 
third pattern piece including a wall defining a second portion of the 
cylindrical bore and a second recess communicating with the second portion 
of the cylindrical bore and forming the second portion of the transfer 
passage. 
The invention also provides a lost foam pattern for an article including a 
main cavity and a secondary cavity defined by spaced said walls and an 
additional wall which is convex, said pattern comprising a first pattern 
piece including a wall defining a primary recess forming the main cavity 
and extending in a given direction, and a secondary recess extending in 
the given direction and communicating through the wall with the primary 
recess, which secondary recess is defined by opposed walls extending in 
the given direction and forming the spaced side walls of the secondary 
cavity, a second pattern piece located in the secondary recess, having a 
first arcuate wall forming a continuation of the wall defining the primary 
recess in the first pattern piece, and having a second convexly arcuate 
wall forming the additional wall of the secondary cavity, and means on the 
first and second pattern pieces for locating the first and second pattern 
pieces relative to each other. 
Other features and advantages of the invention will become apparent to 
those skilled in the art upon review of the following detailed 
description, claims, and drawings.

GENERAL DESCRIPTION 
The lost foam engine block pattern 101 shown in FIG. 3 includes a 
cylindrical wall or bore 105 having an axis 106 and two arcuately spaced 
and arcuately extending, generally identical, transfer passages 107 and 
109, as well as a boost transfer passage 111. Each of the transfer 
passages 107 and 109 extends arcuately, i.e., includes an outer axially 
extending arcuate wall or surface 113 which is inwardly concave in cross 
section. Specifically, the arcuate wall or surface 113 forming the 
transfer passage 107 is inwardly concave in cross section in a plane 115 
extending parallel to a plane 117 extending radially through and 
containing the axis 106 of the cylindrical bore. In addition, each of the 
transfer passages 107 and 109 includes an inner axially extending arcuate 
wall or surface 119 which is outwardly convex. Specifically, the arcuate 
wall or surface 119 of the transfer passage 107 is outwardly convex in 
cross section in the plane 115 which extends parallel to the plane 117 
extending radially from and containing the axis 106 of the cylinder bore 
105. In addition, each of the transfer passages 107 and 109 includes 
spaced axially extending side walls 125 and 127 which connect the outer 
and inner arcuate walls 113 and 119 to complete the transfer passages. As 
the transfer passages 107 and 109 are formed in substantially identical 
fashion, only the construction of the transfer passage 107 will be 
referred hereinafter. 
More particularly, as shown in FIG. 4, the lost foam engine block pattern 
101 includes three portions or pieces, including two axially adjacent 
pieces 141 and 143 which are die cast of foam material, which are 
respectively referred to hereinafter as the first and third pieces, which 
are glued or otherwise fixed to each other, and which respectively include 
cylindrical walls 145 and 147 forming portions of the cylindrical bore 
105. In addition, the first or end piece or portion 145 contains a 
transfer passage recess or cavity 151 which opens into the cylindrical 
wall 145 and into a surface 153 which mates with the third piece 143. 
As shown best in FIG. 5, the transfer passage recess or cavity 151 includes 
spaced and opposed axially extending walls 161 and 163 which, in part, 
form the side walls 125 and 127 of the transfer passage 107. In addition, 
the transfer passage recess or cavity 151 includes an arcuate outer wall 
165 which forms the outer wall 113, and which is radially inwardly concave 
in cross section in the plane 115 which extends parallel to the plane 117 
extending radially from and containing the axis 106 of the cylindrical 
bore 105. The transfer passage recess or cavity 151 can be formed by a die 
member (not shown) which is separated from the cast lost foam pattern 
piece 141 in the axial direction X. 
Located in the transfer passage recess or cavity 151 is another or second 
pattern piece or portion 171 which is also die cast of foam material. The 
second pattern piece or portion 171 includes an arcuate wall 173 which 
forms a continuation of the cylindrical wall 145 partially defining the 
cylindrical bore 105, a spaced arcuate wall 179 which forms the inner wall 
119 of the transfer passage 107 and which, in the assembled pattern 101, 
is outwardly convex in the plane 115 which extends parallel to the plane 
117 extending radially from and containing the axis 106 of the cylindrical 
bore 105. In addition, the second pattern piece 171 includes two side 
walls 175 and 177 which respectively engage the walls 161 and 163 of the 
transfer passage recesses or cavity 151. 
Means are provided for locating the second pattern piece or portion 171 in 
the transfer passage recess or cavity 151 in proper position and for 
preventing movement of the second pattern piece or portion 171 relative to 
the first pattern piece or portion 141, except in the direction opposite 
to the direction of assembly of the second pattern piece or portion 171 to 
the first pattern piece or portion 141. While other arrangements can be 
employed, in the disclosed construction, the pattern pieces 141 and 171 
are assembled by relative movement therebetween in a single assembly 
direction in the plane 115 which is parallel to the plane 117 extending 
radially from and containing the axis 106 of the cylindrical bore 105, and 
preferably in a direction perpendicular to the axis 106 of the cylindrical 
bore 105. 
While other constructions can be employed, in the disclosed construction, 
such locating means and movement preventing means comprises, in each of 
the wall portions 161 and 163 of the transfer passage recess or cavity 151 
in the pattern piece 141, respective pilot recesses 181 and 183 which open 
into the cylindrical bore 105 and into the transfer passage recess or 
cavity 151 and which respectively receive the side walls 175 and 177 of 
the third pattern piece or portion 171 in inter-fitting engagement to 
prevent movement between the pattern pieces 141 and 171 in all directions 
except the direction opposite to the assembly direction. In this regard, 
it is noted that each of the pilot recesses 181 and 183 includes axially 
spaced surfaces 191 and 193 which serve to axially properly locate the 
pattern pieces 141 and 171 and to prevent relative axial movement 
therebetween. In addition, the pilot recesses 181 and 183 also includes 
axially extending surfaces 195 which serve to properly radially locate the 
pattern pieces 141 and 171 relative to each other and to prevent radially 
relative movement of the pattern pieces 141 and 171. Still further, the 
side walls 175 and 177 of the pattern piece 171 mate with the recessed 
surfaces 201 and 203 of the pilot recesses 181 and 183 in the walls 161 
and 163 to prevent relative angular movement between the pattern pieces 
141 and 171 about the axis 106 of the cylindrical bore 105. 
Any suitable adhesive glue or other suitable means can be employed to 
fixedly attach the pattern piece 171 within the transfer passage recess or 
cavity 151 of the pattern piece 141 and to prevent relative movement of 
the pattern pieces 141 and 171 in the direction opposite to the direction 
of assembly. 
The third pattern piece or portion 143 includes, in addition to the 
cylindrical wall 147, a cavity or recess 197 which forms another portion 
of the transfer passage and which accommodates separation from a die 
member (not shown) movable relatively thereto in the axial direction Y. 
With the disclosed construction, the portion of the transfer passage 
previously provided in the upper and middle portions of the assembled 
pattern as disclosed in the U.S. Pat. No. 4,632,169 can be more easily 
manufactured and assembled. In addition, the construction disclosed herein 
avoids intersection or passage of a glue line through a port to the 
combustion chamber, and thus avoids the possibility of adverse effect on 
the flow through the port and into the combustion chamber due to 
unevenness in the casting resulting from the presence of the glue line. 
Various of the features of the invention are set forth in the following 
claims: