US3827242A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Master cylinder for a two-circuit brake system
Assignee: PTT IND Inc
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Filing: 1972-11-20
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Granted: 1974-08-06
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Expires: 1992-11-20
Abstract
Abstract This relates to a master cylinder for a two-circuit system having a brake pressure medium accumulator. More particularly there is provided an arrangement for such a master cylinder that will prevent the brake pedal from traveling a great distance upon failure of one brake circuit. The master cylinder includes a master piston operating on one chamber to hydraulically apply brake pressure to said one brake circuit. The master piston is at first mechanically actuated by the brake pedal to actuate said one brake circuit. The outer surface of the master piston includes an inclined ramp that opens a valve and permits the accumulator pressure to be applied to the brake-pedal-applied end of the master piston. To prevent travel of the brake pedal upon failure of said one brake circuit, a freely axially displaceable secondary piston is provided in said one chamber. The transverse surface of the secondary piston opposite the adjacent end of the master piston is supplied with brake pressure from the accumulator via the brake-pedal-applied end of the master piston upon failure of said one brake circuit. This will move the secondary piston against the adjacent end of the master piston and prevent movement of the master piston thereby preventing undesired brake pedal travel.
Inventors
- 👤 J Belart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:54
CPC Classifications
B; B60; B60T; B60T13/00; B60T13/10; B60T13/12; B60T13/14; B60T13/142; B60T13/145; B60T13/146
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
438 words
A master cylinder for a two-circuit brake system comprising: a cylindrical housing having a longitudinal axis; a master piston disposed within said housing coaxial of said axis, said master piston having a primary collar disposed adjacent one end of said master piston between said master piston and the inner surface of said housing; a brake pedal; a push rod disposed adjacent the end of said master piston opposite said one end of said master piston connected to said brake pedal to advance said mAster piston upon actuating said brake pedal; a first chamber disposed in said housing between said primary collar and a bottom wall of said housing disposed transverse to said axis; a first brake circuit connected to said first chamber through a first bore through the wall of said housing, said first bore being spaced from both said primary collar and said bottom wall, said first brake circuit having pressure applied thereto upon advance of said master piston; a first source of pressurized brake pressure medium; a second source of brake pressure medium; a supply bore extending through the wall of said housing adjacent said first chamber in communication with said second source and said first chamber to supply brake pressure medium to said first chamber; a compensating bore extending through the wall of said housing in said first chamber spaced a first given distance from said primary collar, said compensating bore being connected to said second source; a first valve having a tappet connected thereto extending through a second bore through the wall of said housing adjacent said opposite end of said master piston; first means to connect said first valve to said first source; said tappet engaging the outer surface of said master piston, said first valve being opened by said tappet upon advance of said master piston to couple said pressurized brake pressure medium from said first source to said opposite end of said master piston; a secondary piston disposed in said first chamber, said secondary piston being freely axially displaceable in said first chamber and having a first surface transverse to said axis and remote from said master piston; an arrangement connected between said opposite end of said master piston and a point between said bottom wall and said first surface to supply said pressurized brake pressure medium to said first surface when said first valve is opened and said primary collar has slid over said compensating bore; and second means disposed adjacent said opposite end of said master piston in association with said arrangement to control the supplying of said pressurized brake pressure medium to said first surface through said arrangement.
Claim 2
Dependent Claim
438 words
A master cylinder for a two-circuit brake system comprising: a cylindrical housing having a longitudinal axis; a master piston disposed within said housing coaxial of said axis, said master piston having a primary collar disposed adjacent one end of said master piston between said master piston and the inner surface of said housing; a brake pedal; a push rod disposed adjacent the end of said master piston opposite said one end of said master piston connected to said brake pedal to advance said mAster piston upon actuating said brake pedal; a first chamber disposed in said housing between said primary collar and a bottom wall of said housing disposed transverse to said axis; a first brake circuit connected to said first chamber through a first bore through the wall of said housing, said first bore being spaced from both said primary collar and said bottom wall, said first brake circuit having pressure applied thereto upon advance of said master piston; a first source of pressurized brake pressure medium; a second source of brake pressure medium; a supply bore extending through the wall of said housing adjacent said first chamber in communication with said second source and said first chamber to supply brake pressure medium to said first chamber; a compensating bore extending through the wall of said housing in said first chamber spaced a first given distance from said primary collar, said compensating bore being connected to said second source; a first valve having a tappet connected thereto extending through a second bore through the wall of said housing adjacent said opposite end of said master piston; first means to connect said first valve to said first source; said tappet engaging the outer surface of said master piston, said first valve being opened by said tappet upon advance of said master piston to couple said pressurized brake pressure medium from said first source to said opposite end of said master piston; a secondary piston disposed in said first chamber, said secondary piston being freely axially displaceable in said first chamber and having a first surface transverse to said axis and remote from said master piston; an arrangement connected between said opposite end of said master piston and a point between said bottom wall and said first surface to supply said pressurized brake pressure medium to said first surface when said first valve is opened and said primary collar has slid over said compensating bore; and second means disposed adjacent said opposite end of said master piston in association with said arrangement to control the supplying of said pressurized brake pressure medium to said first surface through said arrangement.
Claim 3
Dependent Claim
25 words
A master cylinder according to claim 1, wherein said secondary piston is disposed in said first chamber between said first bore and said bottom wall.
Claim 4
Dependent Claim
78 words
A master cylinder according to claim 2, wherein said secondary piston includes a pin extending parallel to said axis from said first surface of said secondary piston to ensure the formation of a second chamber defined by said first surface of said secondary piston, said bottom wall and the inner surface of said housing parallel to said axis between said first surface of said secondary piston and said bottom wall when said pin rests against said bottom wall.
Claim 5
Dependent Claim
89 words
A master cylinder according to claim 3, further including a valve arrangement disposed adjacent said opposite end of said master piston between the inner surface of said housing and the outer surface of said master piston; a third bore through the wall of said housing communicating with said piston arrangement; and a pressure medium line connected between said third bore and said second chamber to supply said pressurized brake pressure medium to said first surface of said secondary piston when said first valve opens and said valve arrangement opens.
Claim 6
Dependent Claim
33 words
A master cylinder according to claim 4, wherein said third bore is spaced axially from said opposite end of said master piston by a second given distance greater than said first given distance.
Claim 7
Dependent Claim
25 words
A master cylinder according to claim 5, wherein said valve arrangement opens immediately after said compensation bore has been slid over by said compensating bore.
Claim 8
Dependent Claim
181 words
A master cylinder according to claim 6, further including a first longitudinal bore disposed in said master piston adjacent said opposite end of said master piston and coaxial of said axis; a control piston disposed in a longitudinally displaceable manner in said first longitudinal bore; said control piston being actuated by said push rod to advance said master piston upon actuation of said brake pedal; a first spring interconnected between said master piston and said control piston to control the relative motion of said master piston and said control piston; a second longitudinal bore disposed within and coextensive with said control piston; a fourth bore through the wall of said master piston in communication with said valve; and a first transverse bore disposed within said control piston in communication with said second longitudinal bore and capable of being aligned with said fourth bore upon advance of said control piston; said fourth bore, said first transverse bore and said second longitudinal bore supplying said pressurized brake pressure medium to said opposite end of said master piston when said first valve is opened.
Claim 9
Dependent Claim
38 words
A master cylinder according to claim 7, wherein said master piston includes a piston section carrying said primary collar, and a control section disposed in tandem relation with said piston section, said control section containing said control piston.
Claim 10
Dependent Claim
31 words
A master cylinder according to claim 8, wherein both of said piston section and said control section are cylindrical; and said control section is concentric with respect to said control piston.
Claim 11
Dependent Claim
41 words
A master cylinder according to claim 9, further including an annular cam area disposed in the outer surface of said master piston engaging said tappet, said cam area having a ramp portion ascending toward said opposite end of said master piston.
Claim 12
Dependent Claim
15 words
A master cylinder according to claim 10, wherein said first source includes a hydropneumatic accumulator.
Claim 13
Dependent Claim
111 words
A master cylinder according to claim 11, further including a third chamber disposed between the outer surface of said master cylinder and the inner surface of said housing embracing said cam area, said second bore and said fourth bore; a first seal disposed between the outer surface of said master piston and the inner surface of said housing adjacent one end of said control section corresponding to said opposite end of said master piston; and a second seal disposed between the outer surface of said master piston and the inner surface of said housing adjacent the other end of said control section; said first and second seals sealing said third chamber.
Claim 14
Dependent Claim
89 words
A master cylinder according to claim 12, wherein said first source includes a return reservoir, and a pump connected between said return reservoir and said accumulator; said master piston further includes a cylindrical connection piece disposed between adjacent ends of said piston section and said control section; and further including a fourth chamber disposed between the outer surface of said connection piece and the inner surface of said housing; and fifth bore extending through the wall of said housing in communication with said return reservoir and said fourth chamber.
Claim 15
Dependent Claim
42 words
A master cylinder according to claim 13, wherein said first longitudinal bore extends into said connection piece; and further including a sixth bore extending through the wall of said connection piece in communication with said fourth chamber and said first longitudinal bore.
Claim 16
Dependent Claim
61 words
A master cylinder according to claim 14, wherein said sixth bore is axially spaced a given amount from the adjacent end of said control section to enable said control section to slide over and block said sixth bore before said first valve opens, and said sixth bore communicates with said second longitudinal bore in the rest position of said master piston.
Claim 17
Dependent Claim
40 words
A master cylinder according to claim 15, further including a cavity formed in a portion of the inner surface of said control section and a corresponding portion of the outer surface of said control piston to reCeive said first spring.
Claim 18
Dependent Claim
41 words
A master cylinder according to claim 16, further including a second spring disposed between the adjacent ends of said piston section and said secondary piston to return said master piston to its rest position after the completion of a braking operation.
Claim 19
Dependent Claim
75 words
A master cylinder according to claim 17, further including a stop surface disposed in said first longitudinal bore transverse of said axis and spaced from the end of said control piston opposite said push rod a predetermined amount; and wherein said second spring is stronger than said first spring so that upon braking said master piston will not move before said first spring has been totally compressed and said control piston abuts said stop surface.
Claim 20
Dependent Claim
28 words
A master cylinder according to claim 18, further including an abutment extending axially from the end of said piston section adjacent said secondary piston toward said secondary piston.
Claim 21
Dependent Claim
50 words
A master cylinder according to claim 19, further including a fifth chamber defined by said opposite end of said master piston, the inner surface of said housing parallel to said axis and said push rod; and wherein said control piston protrudes out of said control section into said fifth chamber.
Claim 22
Dependent Claim
37 words
A master cylinder according to claim 20, further including a second transverse bore disposed in that portion of said control piston protruding into said fifth chamber in communication with said second longitudinal bore and said fifth chamber.
Claim 23
Dependent Claim
38 words
A master cylinder according to claim 21, further including an annular abutment extending radially from the inner surface of said housing adjacent said opposite end of said master piston to determine the rest position of said master piston.
Claim 24
Dependent Claim
31 words
A master cylinder according to claim 22, wherein said annular abutment is spaced said second given distance from said third bore and cooperates with said opposite end of said master piston.
Claim 25
Dependent Claim
33 words
A master cylinder according to claim 23, further including a second brake circuit connected to said fifth chamber having brake pressure applied thereto from said first source when said first valve is opened.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-05 | 1978-02-04 | 1978-08-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-05 | 1982-02-04 | 1982-08-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-05 | 1986-02-04 | 1986-08-06 | $7700.00 | Window Closed / Lapsed |