U.S. patent number RE29,806 [Application Number 05/676,712] was granted by the patent office on 1978-10-17 for rotor housing for a rotary piston type engine and method for manufacturing the same.
Invention is credited to Mutsuo Ichihara, Hirotaka Iida, Hiroshi Masaoka, Sadao Taketomo, Koji Tashiro, Yoshitaka Uebayashi, Michinobu Yamada.
United States Patent |
RE29,806 |
Iida , et al. |
October 17, 1978 |
Rotor housing for a rotary piston type engine and method for
manufacturing the same
Abstract
Rotor housing for a rotary piston type engine comprising a liner
made of a metal sheet having one surface formed with teeth-like
projections, said liner being formed into a trochoidal
configuration with said one surface directed outside, and an
aluminum based metal housing substrate cast around the liner
whereby firm bonding is assured between the liner and the housing
substrate due to the existence of the projections. Novel method for
manufacturing such a rotor housing is also disclosed.
Inventors: |
Iida; Hirotaka (Hiroshima-shi,
Hiroshima-ken, JP), Masaoka; Hiroshi (Onaga-machi,
Hiroshima-shi, Hiroshima-ken, JP), Yamada; Michinobu
(Ujinahigashi, Hiroshima-shi, Hiroshima-ken, JP),
Ichihara; Mutsuo (Aki-gun, Hiroshima-ken, JP),
Uebayashi; Yoshitaka (Aki-gun, Hiroshima-ken, JP),
Tashiro; Koji (Aki-gun, Hiroshima-ken, JP), Taketomo;
Sadao (Asa-gun, Hiroshima-ken, JP) |
Family
ID: |
27290530 |
Appl.
No.: |
05/676,712 |
Filed: |
April 14, 1976 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
459329 |
Apr 9, 1974 |
03934321 |
Jan 27, 1976 |
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Foreign Application Priority Data
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Apr 10, 1973 [JP] |
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48-40580 |
Apr 11, 1973 [JP] |
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48-41639 |
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Current U.S.
Class: |
418/178;
29/527.5; 418/179; 29/888.012; 29/888; 164/98; 164/112 |
Current CPC
Class: |
F02B
55/08 (20130101); F01C 21/106 (20130101); Y10T
29/49229 (20150115); Y10T 29/49988 (20150115); Y02T
10/12 (20130101); Y02T 10/17 (20130101); Y10T
29/49234 (20150115) |
Current International
Class: |
F02B
55/00 (20060101); F02B 55/08 (20060101); F01C
21/00 (20060101); F01C 21/10 (20060101); F01C
021/00 (); B23P 015/00 () |
Field of
Search: |
;29/156.4WL,527.1,527.5
;164/98,112,113 ;418/178,179 ;123/193C ;92/169 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Metals Handbook, 8th Edition, Welding and Brazing, vol. 6, American
Society For Metals, 1971, p. 504..
|
Primary Examiner: Lanham; C.W.
Assistant Examiner: Crane; Daniel C.
Attorney, Agent or Firm: Fleit & Jacobson
Claims
We claim:
1. Method for manufacturing a rotor housing for a rotary piston
type engine having a rotor housing liner with a cold zone located
substantially opposite an ignition plug opening, comprising steps
of providing a rolled metal sheet, scratching one side of said
metal sheet to provide a rough surface, welding opposite terminal
edges of said metal sheet together with said rough surface directed
outside, forming said metal sheet into a trochoidal configuration
to provide a liner with the welded edges disposed within a cold
zone of the completed housing, and casting under pressure an
aluminum based material around said liner with terminal edges
welded to form a housing substrate.
2. Method in accordance with claim 1 in which the liner is formed
into a trochoidal configuration having a major axis longer than
that of a nominal trochoidal configuration which is larger than a
desired configuration of the rotor housing by an average shrinkage
during manufacture of the housing, and a minor axis shorter than
that of the nominal trochoidal configuration.
3. Method in accordance with claim 1 in which a plurality of
saw-teeth like projections are formed to provide the rough surface
by the scratching step.
4. Method in accordance with claim 1 in which a plurality of
saw-teeth like projections are formed in staggered relationship
with each other on said one side of the metal sheet to provide said
rough surface by the scratching step.
5. Method in accordance with claim 1 in which said metal sheet is
formed into a circular configuration with said edges flattened to
the welding step.
6. Method in accordance with claim 1 in which said metal sheet is
formed into a trochoidal configuration before the edges are welded
together. .Iadd. 7. A method of manufacturing a rotor housing for a
rotary piston type engine having a rotor housing liner with a cold
zone located substantially opposite an ignition plug opening,
comprising the steps of providing a metal sheet, treating one side
of said metal sheet to provide a rough surface, bonding opposite
terminal edges of said metal sheet together with said rough surface
directed outside, forming said metal sheet into a trochoidal
configuration to provide a liner with the bonded edges disposed
within a cold zone of said housing and casting an aluminum based
material around said liner to form a housing substrate. .Iaddend.
.Iadd. 8. A method in accordance with claim 7 wherein said treating
step comprises scratching said one side of said metal sheet.
.Iaddend..Iadd. 9. A method in accordance with claim 8 wherein said
scratching step includes forming a plurality of sawteeth like
projections on said one side of said metal sheet. .Iaddend..Iadd.
10. A method in accordance with claim 7 wherein said bonding step
comprises welding together said metal sheet terminal edges.
.Iaddend. .Iadd. 11. A rotor housing for a rotary piston type
engine, comprising a liner provided by a rolled metal sheet which
is scratched at one side to form a rough surface and has opposite
terminal edges welded together to form a trochoidal configuration
with said rough surface directed outside, and an aluminum based
metal housing substrate cast around the liner, said welded terminal
edges of the metal sheet being disposed within a cold zone of the
housing located substantially opposite an ignition plug opening.
.Iaddend. .Iadd. 12. A rotor housing in accordance with claim 11 in
which said liner is made of iron. .Iaddend..Iadd. 13. A rotor
housing in accordance with claim 11 in which said rough surface of
the liner is constituted by a plurality of saw-teeth like
projections formed by scratching the surface. .Iaddend. .Iadd. 14.
A rotor housing in accordance with claim 13 in which said
projections are arranged in staggered relationship with each other.
.Iaddend. .Iadd. 15. A rotor housing for a rotary piston type
engine, comprising a liner provided by a metal sheet which is
treated at one side to form a rough surface and has opposite
terminal edges bonded together to form a trochoidal configuration
with said rough surface directed outside, and an aluminum based
metal housing substrate cast around the liner, said bonded terminal
edges of the metal sheet being disposed within a cold zone of the
housing located substantially opposite an ignition plug opening.
.Iaddend. .Iadd. 16. A rotor housing in accordance with claim 15 in
which said liner is made of iron. .Iaddend..Iadd. 17. A rotor
housing in accordance with claim 15 in which said rough surface of
the liner is constituted by a plurality of saw-teeth like
projections formed by treating the surface. .Iaddend..Iadd. 18. A
rotor housing in accordance with claim 17 in which said projections
are arranged in staggered relationship with each other. .Iaddend.
Description
The present invention relates to a rotor housing for a rotary
piston type internal combustion engine and a method for
manufacturing such a rotor housing. More particularly, the present
invention relates to a rotor housing comprising a rolled metal
plate liner and an aluminum based cast metal substrate surrounding
the liner.
It has been recognized that a rotor housing of a rotary piston type
internal combustion engine is subjected at its sliding surface to
high temperature gas so that a substantial thermal load is applied
thereto. Further, since a rotor is moved in a planetary revolving
motion in the rotor housing, the rotor housing is subjected to
cyclic shock load so that the housing material must be of a shock
resistant property. It is further required that the rotor housing
have a wear resistant sliding surface because apex seals on the
rotor slidably move thereon.
Thus, it has been proposed to cast a rotor housing substrate by a
material having a high heat conductive property, such as aluminum
alloy, and then provide a hard plated layer such as by chromium
plating on the inner surface of the housing substrate.
In fact, there has been proposed to form a hard layer by directly
plating chromium on the cast aluminum alloy substrate. However, it
has been experienced that the plated layer thus formed is often
peeled off when it is subjected to cyclic shock load from the
rotor. Internal defects such as blow holes and/or pin holes in the
casted aluminium alloy substrate locally reduce heat conductivity
of the substrate possibly causing peeling-off of the plated layer.
Further, the plated layer may have cracks which may be a cause of
corrosion. The direct plating method is further disadvantageous in
that it requires complicated pre-treatments in order to secure a
satisfactory bonding of the plated layer to the substrate.
It has also been proposed to provide a compound nickel plating
directly on the cast aluminium alloy substrate. However, this
method has disadvantages as in the aforementioned method since the
housing substrate is made of aluminum alloy. Further, carbides such
as SiC are educed during nickel plating and these carbides make
machining of the housing inner surface very difficult. Since the
amount of educed SiC affects the amount of wear of a sliding member
which slidably moves on the plated surface, it is important to
control the amount of SiC, however, such a control has been
considered as being very difficult. Further, as far as the plating
process is concerned, a complicated process is required to supply
nickel ion to the plating bath and to maintain the anode.
Another known method is to provide a plated layer of a hard
material, such as chromium on the inner surface of the cast
aluminum alloy substrate with the intervention of a sprayed metal
layer therebetween. However, an additional step is required in
spraying the metal and further it is difficult to perform quality
control.
There has also been proposed to provide a cast iron liner having
rough surfaces, then cast aluminum alloy around the liner to form a
housing substrate and then provide a chromium plated layer on the
inner surface of the cast iron liner. The liner provides a
sufficient bonding of the plated chromium layer, and in order to
provide satisfactory rough surfaces, a centrifugal casting process
may be employed in providing the cast iron liner. This method is
disadvantageous, however, in that it is limited to a use of a cast
material such as a cast iron in providing the liner. Further, the
method cannot provide a higher production rate. When a centifugal
casting process is employed, the method can only produce a
cylindrical liner so that it cannot be applied to a manufacture of
a rotor housing for a rotary piston type engine.
Therefore, the present invention has an object to eliminate the
aforementioned disadvantages of the known methods.
Another object of the present invention is to provide a novel
construction of a rotor housing which can be readily
manufactured.
A further object of the present invention is to provide a rotor
housing for a rotary piston type engine having an inner plated
layer which is substantially free from any breakage.
Still further object of the present invention is to provide a
method for manufacturing such a rotor housing of novel
construction.
According to the present invention, the above and other objects can
be achieved by a rotor housing for a rotary piston type engine,
comprising a liner provided by a rolled metal sheet which is
scratched at one side to form a rough surface and has opposite
terminal edges welded together to form a trochoidal configuration
with said rough surface directed outside, and an aluminum based
metal housing substrate cast around the liner, said welded terminal
edges of the metal sheet being disposed within cold zone of the
housing. Preferably, the liner is made of a steel plate and a
plated layer of hard metal such as chromium may be provided on the
inner surface of the liner.
According to a further aspect of the present invention, there is
provided a method for manufacturing a rotor housing, comprising
steps of providing a rolled metal sheet, scratching one side of
said metal sheet to provide a rough surface, welding opposite
terminal edges of said metal sheet together with said rough surface
directed outside, forming said welded metal sheet into a trochoidal
configuration to provide a liner with the welded edges disposed
within cold zone of the completed housing, and casting under
pressure an aluminum based material around said liner to form a
housing substrate. According to a preferred mode of the present
invention, the liner is formed into a trochoidal configuration
having a major axis longer than that of a nominal trochoidal
configuration which is larger than a desired trochoidal
configuration of the rotor housing by an average shrink of the
housing during manufacturing, and a minor axis shorter than that of
the nominal trochoidal configuration. After casting the housing
substrate, the liner is brought into the desired trochoidal
configuration during cooling process of the housing.
The above and other objects and features of the present invention
will become apparent from the following descriptions of the
preferred embodiments taking reference to the accompanying
drawings, in which:
FIG. 1 is a perspective view of a rotor housing in accordance with
the present invention;
FIG. 2 diagrammatically shows a portion of the apparatus for
carrying out a process for preparing a sheet metal liner of
trochoidal configuration;
FIG. 3 shows another step in the process of the invention;
FIG. 4 shows a further step in the process of the invention;
FIG. 5 shows a further step in the process of the invention;
FIG. 6 shows a further step in the process of the invention;
FIG. 7 shows a further step in the process of the invention;
FIG. 8 shows a further step in the process of the invention;
FIG. 9 shows a further step in the process of the invention;
FIG. 10 shows a further step in the process of the invention;
FIG. 11 diagrammatically shows one step of another process for
forming a trochoidal sheet metal liner;
FIG. 12 shows a further step in the embodiment of FIG. 11;
FIG. 13 shows a further step in the embodiment of FIG. 11;
FIG. 14 shows a further step in the embodiment of FIG. 11;
FIG. 15 is a view showing a step of forming a trochoidal sheet
metal liner which is deviated from a desired trochoidal
configuration; and
FIG. 16 is a diagram showing the deviation of the trochoidal
configuration of the sheet metal liner from the desired trochoidal
configuration;
FIG. 17 is an enlarged sectional view showing a section of a
scratched rough surface on the metal sheet;
FIG. 18 is a sectional view of a die assembly for moulding a
housing substrate around the sheet metal liner;
Referring now to the drawings, particularly to FIG. 1, there is
shown in perspective view a rotor housing 1 made in accordance with
the present invention. The rotor housing 1 comprises an inner liner
2 which is made of a sheet metal such as a steel plate which has
opposite terminal edges welded together as shown by 2a in FIG. 1.
The liner 2 is formed into a trochoidal configuration and has a
rough outer surface 2b which is prepared by scratching the surface.
Around the liner 2, there is formed a housing substrate 3 which is
provided by aluminum or its alloy through a well known die-cast
process. The housing is formed with ignition plug holes 4 and an
exhaust port 5 as is well known in the art. Further, the housing
substrate has legs 3a and 3b integrally formed therewith. In FIG.
1, the area Z shows a cold zone where the temperature is
substantially lower than in the other zones. It should be noted
that the edge welding portion 2a of the liner 2 is disposed in the
cold zone Z.
Referring now to FIG. 2, there is shown a process for forming a
trochoidal sheet metal liner 2. A sheet metal web 6 is drawn from a
roll 7 and passed through a straightening device 8 including a
plurality of rolls 8a into a scratching mechanism 9. The mechanism
9 includes a plurality of scratching edges 10a and 10b which are
arranged in two rows in staggered relationship. The scratching
edges 10a and 10b are carried by a bracket 11 which is pivotally
supported on a stationary frame F. The bracket 11 and the arm 12
are respectively connected with ends of links 13 and 14 which are
in turn connected together at 15. The link 13 is connected through
a third link 16 with a vertically movable press member 17. The
reference numeral 18 designates a return spring. When the press
member 17 is moved downwardly as shown by an arrow, the scratching
edges 10a and 10b bite into the upper surface of the web 6 so as to
provide a plurality of saw-teeth like projections 19 (FIG. 17)
disposed in staggered relation with each other on the surface of
the liner 2 to provide a rough surface 2b. The mechanism 9 further
includes a holding member 20 carried on a swingable arm 12 on the
frame F for holding the sheet metal web 6 stationary when the
scratching mechanism 9 is in operation.
Next to the scratching mechanism 9, there is provided a cutting
device 21 including a movable cutting blade 22 and a stationary
blade 23. The cutting device 21 severs the sheet metal web 6 into a
sheet 6a of a suitable length. Then, the sheet 6a is passed into a
punching die assembly 24 in which the sheet 6a is punched into a
desired shape by means of an upper and a lower dies 24a, 24b to
form a blank 6b. Therefore, the blank 6b is passed through a
forming roller assembly 25 in which it is formed into a circular
configuration as shown by 6c in FIG. 3.
The circular sheet metal blank 6c is then introduced into an edge
flattening press assembly 26 including an upper press member 27 and
a lower press member 28 as shown in FIG. 4, whereby the opposite
terminal edges 6d and 6e flush of the blank 6c are flattened as
shown in FIG. 5. The flattened edges 6d and 6e are then gripped by
pairs of electrodes 29a, 29b and 30a, 30b respectively, and
thereafter the movable pair of electrodes 30a and 30b are moved as
shown by an arrow in FIG. 6 until the edge 6e of the blank 6c is
brought into contact with the opposite edge 6d and welded thereto
in the manner of a flush butt welding so as to obtain a
substantially cylindrical part 6f with a welding burr 6g at the
welded portion. Then, the burr 6g is removed by suitable means to
obtain a sheet metal part 6h as shown in FIG. 8.
The sheet metal part 6h is then introduced into a liner former 31
comprising a pair of opposed outer dies 32 and a pair of opposed
inner dies 33 as shown in FIG. 9, and formed into a trochoidal
configuration as shown in FIG. 10. Thus, a trochoidal sheet metal
liner 2 can be obtained. Care must of course be taken so that the
welded portion of the liner 2 is disposed in the cold zone Z of the
completed rotor housing. The liner 2 is then pre-treated by for
example washing, steam degreasing, sand blasting, or the like and
placed in a male die 34 of a moulding die assembly and a female die
35 is placed against the male die 34 to define a moulding cavity 36
around the liner 2 (FIG. 18). Molten metal such as aluminum alloy
is then introduced under pressure into the cavity 36 of the
moulding die assembly and, after cooling, a rotor housing 1 as
shown in FIG. 1 can be obtained. As previously described, a
suitable metal such as chromium may be plated on the inner surface
of the liner 2 when desired.
FIGS. 11-14 show an alternative method for forming a trochoidal
sheet metal liner 2. As shown in FIG. 11 a sheet metal blank 106a
is formed into a waved configuration by a complementary forming
dies 37 and 38. Then, the blank (106a is formed by dies 39 and 40
as shown in FIGS. 12 and 13 into a substantially trochoidal
configuration. Thereafter the opposite edges of the blank is
gripped by pairs of electrodes 41a, 41b and 42a, 42b, respectively,
and welded together.
It has been found that when the housing substrate is moulded the
housing shrinks during cooling step in the direction of major axis
of the trochoidal configuration in a greater extent than in the
other directions due to the existence of cooling water passages in
the housing and the leg portion 3a and 3b, with the result that the
housing is rather bulged out in the direction of the minor axis of
the trochoidal configuration. Thus, in forming the liner 2, this
tendency of deformation should preferably be taken into account.
FIG. 15 shows a trochoid forming step similar to that shown in FIG.
9. The major axis L of the trochoid is made greater than that of a
nominal trochoid which is larger than a desired trochoidal
configuration by an average shrinkage of the housing during
manufacture while the minor axis 1 is smaller than that of the
nominal configuration. FIG. 7 shows the deviation F.sub.1 of the
trochoidal configuration of the liner 2 from the nominal
configuration F.sub.0, F.sub.2 shows a desired configuration. By
forming the liner 2 with this deviation, it is possible to obtain a
desired trochoidal configuration after cooling of the housing, so
that it is possible to reduce the amount of machining of the liner
surface after the moulding process.
According to the present invention, since the cast aluminum based
metal housing substrate is bonded to the outer surface of the liner
through a plurality of saw teeth like projections and any cracks
which may be present in the liner are filled by the aluminum based
metal during moulding process, it is possible to obtain a
substantially improved bonding strength between the liner and the
housing substrate. The staggered arrangement of the scratching
edges is effective to eliminate any direction characteristics in
the bonding strength between the liner and the substrate. The liner
itself and the boundary area between the liner and the substrate
can be free from any oxides which may have adverse effect on the
heat conductive property of the housing. Further, the saw teeth
like projections improves the heat transfer from the liner to the
substrate. When the liner is made of a steel plate, a metal plating
can be made thereon as desired without any particular pretreatment.
Since the liner can be made of a material such as a steel plate
which has a substantial thermal fatigue resistance, it is possible
to eliminate a thermal fatigue failure of the housing in the
vicinity of ignition plug hole as experienced in a rotor housing
having a plated layer directly formed on the housing substrate. By
disposing the welded portion of the liner in the cold zone of the
rotor housing, it is possible to prevent the relatively weak
bonding strength between the liner and the substrate around the
welded portion from having an adverse effect on the durability of
the housing. It is preferable that the welded portion of the liner
is disposed as close as possible within the cold zone to the minor
axis of trochoid since such an arrangement is effective to move the
welded portion apart from the core of the substrate moulding die
whereby any damage on the moulding die by the welded portion of the
liner during removal of the moulded part from the die.
The invention has thus been shown and described with reference to
particular embodiments, however, it should be noted that the
invention is in no way limited to the details of the illustrated
embodiments and changes and modifications may be made within the
scope of the appended claims.
* * * * *