US4276994A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Composite power cylinder
Assignee: Diemakers Inc
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Filing: 1978-08-28
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Granted: 1981-07-07
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Expires: 1998-08-28
Abstract
Abstract Strong, light weight master cylinders for hydraulic braking systems are produced by incasing a section of steel tubing within a diecasting of metal such as an alloy of magnesium or aluminum. Master cylinders can thus be produced by diecasting the metal in situ around a seamless tube having a smooth accurately oversized bore so that it incases the exterior surface and extends over one end thereof and through predetermined shrinkage produces a final uniform bore diameter and operating surface. Tooling requirements are minimal, with little if any machining being needed following the diecasting operation. Unit production cost is thus lower than that of castings made with permanent molds. Light weight diecastable metals can thus be used in combination with strong but relatively thin steel tubing to provide durable master cylinders that are lighter, simpler and less expensive to make than cast iron cylinders. This composite construction can be used in power cylinders for numerous light weight applications.
Inventors
- 👤 George Spalding
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 14:35
CPC Classifications
B; B60; B60T; B60T11/00; B60T11/10; B60T11/16; B60T11/22; B22; B22D; B22D19/00; B22D19/02
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
99 words
A composite hydraulic brake master cylinder comprising a preformed oversized tubular steel sleeve having a bore therein for at least one hydraulic piston, a metal die casting having a generally cylindrical configuration surrounding and concentric with said sleeve exerting a substantially uniform shrinkage force on the entire exterior cylindrical surface of said sleeve, said sleeve having an operating cylinder bore diameter sized by said shrinkage force of the casting placing the sleeve under predetermined compression, and said sleeve having an exterior surface with an end closure over which said casting extends and which is thereby encased by said casting.
Claim 2
Dependent Claim
99 words
A composite hydraulic brake master cylinder comprising a preformed oversized tubular steel sleeve having a bore therein for at least one hydraulic piston, a metal die casting having a generally cylindrical configuration surrounding and concentric with said sleeve exerting a substantially uniform shrinkage force on the entire exterior cylindrical surface of said sleeve, said sleeve having an operating cylinder bore diameter sized by said shrinkage force of the casting placing the sleeve under predetermined compression, and said sleeve having an exterior surface with an end closure over which said casting extends and which is thereby encased by said casting.
Claim 3
Dependent Claim
54 words
A composite power cylinder as set forth in claim 1 wherein a preheated tubular sleeve is cast in place with a differential temperature less than the die casting metal temperature to provide a controlled shrinkage stress in the final composite cylinder less than would result from a room temperature tubular sleeve cast in place.
Claim 4
Dependent Claim
21 words
A composite power cylinder as set forth in either claim 1 or 2 wherein said die casting material is predominantly magnesium.
Claim 5
Dependent Claim
31 words
A composite power cylinder as set forth in claim 2 wherein said die casting material is predominantly magnesium, and said temperature differential at the time of casting is approximately 600° F.
Claim 6
Dependent Claim
42 words
A composite power cylinder as set forth in claim 4 wherein said magnesium is cast at a temperature of approximately 900° F. in the die and said tubular sleeve is preheated to a temperature of approximately 300° F. as cast in place.
Claim 7
Dependent Claim
30 words
A composite power cylinder as set forth in claim 1 or 2 wherein said casting material is selected from a group of relatively light metals such as aluminum and magnesium.
Claim 8
Dependent Claim
35 words
A composite power cylinder as set forth in claim 6 wherein said die cast metal has a cast thickness generally similar to that of said tubular sleeve and has external ribs to provide additional strength.
Claim 9
Dependent Claim
46 words
A composite power cylinder as set forth in claim 7 wherein said general die cast metal thickness is in the order of 0.090", said ribs are in the order of 1/10" wide and high, and said tube has a mean diameter in the order of 1".
Claim 10
Dependent Claim
21 words
A composite power cylinder as set forth in claim 8 including circumferential ribs spaced approximately 3/4" apart in a longitudinal direction.
Claim 11
Dependent Claim
22 words
A composite power cylinder as set forth in claim 9 including longitudinally extending ribs spaced approximately 90° apart in a circumferential direction.
Claim 12
Dependent Claim
20 words
A composite power cylinder as set forth in claim 10, wherein said tubular sleeve has a thickness of approximately 0.083".
Claim 13
Dependent Claim
25 words
A composite power cylinder as set forth in claim 11 wherein said tubular sleeve comprises a cold drawn steel having a specification of SAE 1015.
Claim 14
Dependent Claim
34 words
A composite power cylinder as set forth in claim 1 or 2 including a third material interface between said tubular sleeve and die cast metal providing an additional bond for resisting relative longitudinal displacement.
Claim 15
Dependent Claim
25 words
A composite power cylinder as set forth in claim 13 wherein said third material comprises a nickel aluminide flame spray precoating on said tubular sleeve.
Claim 16
Dependent Claim
29 words
A composite power cylinder as set forth in claim 13 wherein said third material comprises successively applied flame spray nickel aluminide and stainless steel precoatings on said tubular sleeve.
Claim 17
Dependent Claim
31 words
A hydraulic cylinder as in claim 1 wherein said tubular sleeve is a section of drawn tubing and the internal surface thereof which surrounds said piston bore is smoothed by drawing.
Claim 18
Dependent Claim
18 words
A hydraulic cylinder as in claim 1 wherein the diecast metal has a specific gravity below about 3.
Claim 19
Dependent Claim
26 words
A hydraulic cylinder as in claim 1 including at least two channels formed by diecasting which extend through said casting from said bore to the outside.
Claim 20
Dependent Claim
25 words
A hydraulic cylinder as in claim 1 wherein said casting further comprises integral flange means for attaching said cylinder to a vehicle having hydraulic brakes.
Claim 21
Dependent Claim
25 words
A hydraulic cylinder as in claim 19 wherein said casting further comprises at least one integral wall which extends around a reservoir for brake fluid.
Claim 22
Dependent Claim
16 words
A hydraulic cylinder as in claim 19 wherein said wall includes integral bosses for a bail.
Claim 23
Dependent Claim
35 words
A hydraulic cylinder as in claim 18 and further comprising a threaded tubing connector which leads from said channel, said connector having been rigidly emplaced in the casting by the contraction of the diecast metal.
Claim 24
Dependent Claim
42 words
A composite power cylinder as set forth in claim 1 wherein the interface between said exterior cylindrical surface of said sleeve and said die casting material includes an intimate uniform shrinkage pressure fully engaging surface contact throughout the length of said cylinder.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-07-06 | 1985-01-05 | 1985-07-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-07-06 | 1989-01-05 | 1989-07-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-07-06 | 1993-01-05 | 1993-07-07 | $7700.00 | Window Closed / Lapsed |