US3779018A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Master cylinders
Assignee: Fiat SpA
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Filing: 1972-03-15
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Granted: 1973-12-18
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Expires: 1992-03-15
Abstract
Abstract The invention relates to a master cylinder for a hydraulic fluid system such as the hydraulic braking system of a motor vehicle. The cylinder has a main piston and an auxiliary piston between which there is a precompressed spring which transmits movement of the auxiliary piston, caused by its engagement with a push rod operated by the brake pedal, to the main piston. The main piston has two passageways by means of which the space between the main and auxiliary pistons can communicate with a reservoir of hydraulic fluid for the circuit. One of the passageways is controlled by a valve which closes under the action of a flow of fluid from the said space toward the reservoir, and the other is controlled by a valve, linked to the auxiliary piston, which is closed after a predetermined approach of the auxiliary piston towards the main piston against the action of the precompressed spring.
Inventors
- 👤 P Baldwin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 07:43
CPC Classifications
B; B60; B60T; B60T11/00; B60T11/10; B60T11/16; B60T11/224
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
377 words
In a master cylinder for a fluid circuit such as a brake circuit, of the type comprising, a cylindrical body, a main piston sliding in a bore within said cylindrical body, a main spring biasing said main piston towards one end of said cylindrical body, an auxiliary piston in an extension of said bore in said one end of said cylindrical body, said auxiliary piston defining a space between itself and said main piston, a precompressed spring between said auxiliary piston and said main piston, said precompressed spring urging said main piston and said auxiliary piston apart, two parallel routes formed through said main piston and connecting said space in said cylinder between said main piston and said auxiliary piston with a reservoir of said fluid circuit, first valve means controlling one route through said piston, said first valve means being controlled exclusively by the fluid flow past said valve means to perMit the flow of fluid from said reservoir towards said space between said pistons when said main and auxiliary pistons are in their respective rest positions and prevent the flow of fluid from said space between said pistons towards said reservoir when said auxiliary pistons moves relative to said main piston, second valve means controlling the other said route through said piston, said second valve means being open when said main and auxiliary pistons are in their respective rest positions and closing after a predetermined relative movement between said auxiliary piston and said main piston against the action of said precompressed spring between said pistons, the improvement wherein said first valve means includes a substantially circular valve member, a rod mounted on said auxiliary piston, a chamber in said main piston, said rod extending into said chamber, said substantially circular valve member being slidably mounted on said rod and within said chamber, a first annular sealing ring between said valve member and said rod, passageways in said main piston, communicating with said chamber, an annular recess in said substantially circular valve member, a second annular sealing ring in said annular recess, said second sealing ring being shaped such that it is mounted with axial and radial play in said recess in said valve member and bears against the surface of said chamber in said piston.
Claim 2
Dependent Claim
377 words
In a master cylinder for a fluid circuit such as a brake circuit, of the type comprising, a cylindrical body, a main piston sliding in a bore within said cylindrical body, a main spring biasing said main piston towards one end of said cylindrical body, an auxiliary piston in an extension of said bore in said one end of said cylindrical body, said auxiliary piston defining a space between itself and said main piston, a precompressed spring between said auxiliary piston and said main piston, said precompressed spring urging said main piston and said auxiliary piston apart, two parallel routes formed through said main piston and connecting said space in said cylinder between said main piston and said auxiliary piston with a reservoir of said fluid circuit, first valve means controlling one route through said piston, said first valve means being controlled exclusively by the fluid flow past said valve means to perMit the flow of fluid from said reservoir towards said space between said pistons when said main and auxiliary pistons are in their respective rest positions and prevent the flow of fluid from said space between said pistons towards said reservoir when said auxiliary pistons moves relative to said main piston, second valve means controlling the other said route through said piston, said second valve means being open when said main and auxiliary pistons are in their respective rest positions and closing after a predetermined relative movement between said auxiliary piston and said main piston against the action of said precompressed spring between said pistons, the improvement wherein said first valve means includes a substantially circular valve member, a rod mounted on said auxiliary piston, a chamber in said main piston, said rod extending into said chamber, said substantially circular valve member being slidably mounted on said rod and within said chamber, a first annular sealing ring between said valve member and said rod, passageways in said main piston, communicating with said chamber, an annular recess in said substantially circular valve member, a second annular sealing ring in said annular recess, said second sealing ring being shaped such that it is mounted with axial and radial play in said recess in said valve member and bears against the surface of said chamber in said piston.
Claim 3
Dependent Claim
119 words
The master cylinder of claim 1 wherein said second valve means includes, an axial passageway in said rod, a radial passageway in said rod, said radial passageway communicating with said axial passageway, an annular groove in a radially inner face in said substantially circular valve member, said first annular sealing ring being located in said annular groove in said valve member, said first sealing ring contacting said rod adjacent the outlet of said radial passageway, partially covering said outlet when said main and auxiliary pistons are in their rest positions, and covering said outlet to seal said radial passageway when said auxiliary piston has moved a predetermined distance toward said main piston against the action of said precompressed spring.
Claim 4
Dependent Claim
116 words
The master cylinder of claim 2 wherein there is provided an annular washer on said rod adjacent said valve member and defining with said member said annular recess, the diameter of said washer being smaller than the diameter of said chamber in said main piston, said washer being positioned adjacent one end of said precompressed spring to receive the thrust therefrom and being provided with radial grooves on the side thereof facing said valve member, said grooves allowing said fluid to flow between said washer and said second sealing ring and said washer and said valve member such that said space between said main piston and said auxiliary piston communicates with said opening in said rod.
Claim 5
Dependent Claim
89 words
The master cylinder of claim 3 wherein said substantially circular valve member is provided with a plurality of radial recesses in the face thereof opposite that against which bears said annular washer, a radial shoulder in the wall of said chamber in said main piston, the larger diameter of said shoulder corresponding to the diameter of that part of said chamber in said cylinder, within which slides said auxiliary piston, said valve member being urged against said shoulder by the thrust of said precompressed spring transmitted by said washer.
Claim 6
Dependent Claim
35 words
The master cylinder of claim 1 wherein said rod has an enlarged head on the free end thereof, said head retaining said valve member and said washer in position during assembly of said master cylinder.
References Cited (Backward Citations)
US3191384A
Cited
US3487641A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-17 | 1977-06-18 | 1977-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-17 | 1981-06-18 | 1981-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-17 | 1985-06-18 | 1985-12-18 | $7700.00 | Window Closed / Lapsed |