US3815364A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Master cylinder for a two-circuit brake system
Assignee: TDK Micronas GmbH
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Filing: 1972-11-20
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Granted: 1974-06-11
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Expires: 1992-11-20
Abstract
Abstract This relates to a master cylinder for a two-circuit brake system having a hydropneumatic accumulator connected thereto. The master cylinder includes a master piston having coaxially disposed therein an axially displaceable control piston. A spring controls the relative motion of the master piston and control piston. The control piston includes a longitudinal bore and a transverse bore in communication. The transverse bore will line up with the accumulator valve and apply pressure from the accumulator through the longitudinal bore to the working surface of the master piston. Upon actuation of the brake pedal, at first a certain pressure is applied to at least one of the two brake circuits by the master piston. Further advance of the brake pedal causes relative displacement between the two pistons until the transverse bore is aligned with the valve which is opened by an inclined surface contained in the outer surface of the master piston. Immediately the pressure delivered by the accumulator through the open valve is applied to the working surface of the master piston so that the brake force to both brake circuits is now provided by the accumulator.
Inventors
- 👤 J Belart
- 👤 W Volkmar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:06
CPC Classifications
B; B60; B60T; B60T13/00; B60T13/10; B60T13/12; B60T13/14; B60T13/142; B60T13/145; B60T13/146
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
469 words
A master cylinder for a two-circuit brake system comprising: a source of pressurized brake pressure medium; a cylindrical housing having a longitudinal axis; a master piston disposed coaxially of said axis within said housing, said master piston having a first longitudinal bore in a portion thereof adjacent one end of said master piston; a control piston disposed in said first longitudinal bore coaxial of said axis and longitudinally displaceable in said first longitudinal bore; a valve having a tappet extending through a first bore in the wall of said housing transverse to said axis, the end of said tappet engaging a cam area disposed on the outer surface of said master piston to open said valve upon advance of said master piston during all braking operations; a first spring disposed to interact with said master piston and said control piston to control the relative motion of said master piston and said control piston; a brake pedal; a push rod connecting said brake pedal to one end of said control piston adjacent said one end of said master piston; a first chamber defined by said one end of said master piston, the adjacent end of said push rod and the inner surface of said housing; a first brake circuit extending through a second bore in the wall of said housing actuated by the opposite end of said master piston upon advance of said master piston; said one end of said master piston providing a working surface for said master piston in said first chamber; said control piston including a second longitudinal bore therethrough coaxial of said axis and in communication with said first chamber, and a first transverse bore spaced from said first chamber directly connected to said second longitudinal bore and in communication with a third bore through the wall of said master piston upon an advance of said control piston relative to said master piston to allign said first transverse bore with said third bore, said third bore being in communication with said source when said valve is open; said brake pedal actuating said control piston to advance said master piston by means of said first spring to actuate said first brake circuit and open said valve, said control piston advancing relative to said master piston to align said first transverse bore with said third bore and apply pressure from said source to said working surface through said second longitudinal bore; said master piston including a piston section adjacent said first brake circuit, and a control section disposed in tandem relation with said piston section between said piston section and said push rod; and an annular cavity formed in a portion of the inner circumferential wall of said control section and a corresponding portion of the outer circumferential wall of said control piston to receive said first spring.
Claim 2
Dependent Claim
469 words
A master cylinder for a two-circuit brake system comprising: a source of pressurized brake pressure medium; a cylindrical housing having a longitudinal axis; a master piston disposed coaxially of said axis within said housing, said master piston having a first longitudinal bore in a portion thereof adjacent one end of said master piston; a control piston disposed in said first longitudinal bore coaxial of said axis and longitudinally displaceable in said first longitudinal bore; a valve having a tappet extending through a first bore in the wall of said housing transverse to said axis, the end of said tappet engaging a cam area disposed on the outer surface of said master piston to open said valve upon advance of said master piston during all braking operations; a first spring disposed to interact with said master piston and said control piston to control the relative motion of said master piston and said control piston; a brake pedal; a push rod connecting said brake pedal to one end of said control piston adjacent said one end of said master piston; a first chamber defined by said one end of said master piston, the adjacent end of said push rod and the inner surface of said housing; a first brake circuit extending through a second bore in the wall of said housing actuated by the opposite end of said master piston upon advance of said master piston; said one end of said master piston providing a working surface for said master piston in said first chamber; said control piston including a second longitudinal bore therethrough coaxial of said axis and in communication with said first chamber, and a first transverse bore spaced from said first chamber directly connected to said second longitudinal bore and in communication with a third bore through the wall of said master piston upon an advance of said control piston relative to said master piston to allign said first transverse bore with said third bore, said third bore being in communication with said source when said valve is open; said brake pedal actuating said control piston to advance said master piston by means of said first spring to actuate said first brake circuit and open said valve, said control piston advancing relative to said master piston to align said first transverse bore with said third bore and apply pressure from said source to said working surface through said second longitudinal bore; said master piston including a piston section adjacent said first brake circuit, and a control section disposed in tandem relation with said piston section between said piston section and said push rod; and an annular cavity formed in a portion of the inner circumferential wall of said control section and a corresponding portion of the outer circumferential wall of said control piston to receive said first spring.
Claim 3
Dependent Claim
30 words
A master cylinder according to claim 1, wherein said control section and said piston section are both cylindrical, and said control section contains and is concentric with said control piston.
Claim 4
Dependent Claim
45 words
A master cylinder according to claim 2, wherein said control section includes said cam area on the outer surface thereof and said working surface on one end thereof adjacent said push rod; and said cam area includes an inclined surface ascending toward said working surface.
Claim 5
Dependent Claim
14 words
A master cylinder according to claim 3, wherein said source includes a hydropneumatic accumulator.
Claim 6
Dependent Claim
50 words
A master cylinder according to claim 4, wherein said valve includes a ball valve having a second spring to close said ball valve when said tappet is at the bottom of said inclined surface, said ball valve being opened when said tappet moves a predetermined distance up said inclined surface.
Claim 7
Dependent Claim
129 words
A master cylinder according to claim 5, further including a first annular chamber between the outer surface of said control section and the inner surface of said housing embracing said cam area, said first annular chamber being sealed by a first seal between the outer surface of said control section and the inner surface of said housing adjacent said one end of said control section and a second seal between the outer surface of said control section and the inner surface of said housing adjacent the opposite end of said control section, said first annular chamber being in communication with said valve through said first bore and in communication with said first transverse bore upon advance of said control piston relative to said master piston, through said third bore.
Claim 8
Dependent Claim
94 words
A master cylinder according to claim 6, wherein said master piston further includes a cylindrical connection piece connecting said piston section and said control section; and said source includes a return tank, a brake pressure medium accumulator, and a pump disposed between said return tank and said accumulator; and further including a second annular chamber disposed between said outer surface of said connection piece and the inner surface of said housing, and a fourth bore extending through the wall of said housing in communication with said second annular chamber connected to said return tank.
Claim 9
Dependent Claim
38 words
A master cylinder according to claim 7, further including a fifth bore extending through the wall of said connecting piece in communication with said Second longitudinal bore through said first longitudinal bore and with said second annular chamber.
Claim 10
Dependent Claim
42 words
A master cylinder according to claim 8, wherein said fifth bore is spaced from the end of said control piston opposite said push rod a predetermined amount to enable said control piston to block said fifth bore before said valve is opened.
Claim 11
Dependent Claim
42 words
A master cylinder according to claim 9, wherein said second annular chamber is sealed by said second seal and a third seal disposed between the inner surface of said housing and the outer surface of said connection piece adjacent said piston section.
Claim 12
Dependent Claim
27 words
A master cylinder according to claim 10, further including an annular groove in the outer surface of said control piston in communication with said first transverse bore.
Claim 13
Dependent Claim
45 words
A master cylinder according to claim 11, wherein in the rest position the axial spacing of said first transverse bore and said third bore is greater than the axial spacing of said fifth bore and the end of said control piston opposite said push rod.
Claim 14
Dependent Claim
49 words
A master cylinder according to claim 12, further including a third spring coupled between said master piston and a wall of said housing transverse to said axis to return said master piston to its rest position after a braking operation, said third spring being weaker than said first spring.
Claim 15
Dependent Claim
24 words
A master cylinder according to claim 13, wherein said control piston extends from said one end of said control section into said first chamber.
Claim 16
Dependent Claim
64 words
A master cylinder according to claim 14, further including a seal arrangement to provide a seal between the outer surface of said push rod and the inner surface of said housing, said push rod extending into said first chamber to rest against the end of that portion of said control piston extending into said first chamber in the rest position of said master cylinder.
Claim 17
Dependent Claim
19 words
A master cylinder according to claim 15, wherein said tappet is cylindrical in shape having grooves extending lengthwise thereof.
Claim 18
Dependent Claim
19 words
A master cylinder according to claim 16, wherein a second brake circuit is connected to said second longitudinal bore.
Claim 19
Dependent Claim
37 words
A master cylinder according to claim 17, further including a second transverse bore disposed in that portion of said control piston extending into said first chamber in communication with said second longitudinal bore and said first chamber.
Claim 20
Dependent Claim
18 words
A master cylinder according to claim 18, wherein said second brake circuit is connected to said first chamber.
Claim 21
Dependent Claim
54 words
A master cylinder according to claim 16, further including an additional piston disposed in said housing connected to said piston section remote from said push rod; and wherein a second brake circuit is connected to a sixth bore in the wall of said housing, said second brake circuit being actuated by said additional piston.
References Cited (Backward Citations)
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US2775957A
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US2916882A
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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) | 1977-06-10 | 1977-12-10 | 1978-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-10 | 1981-12-10 | 1982-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-10 | 1985-12-10 | 1986-06-11 | $7700.00 | Window Closed / Lapsed |