Hydraulic braking systems for vehicles

Claim 2

In a control unit for an hydraulic braking system for a vehicle of the type including a slave cylinder for applying a wheel brake, a source of high-pressure fluid, and means for supplying fluid from said source to said slave cylinder, comprising a housing incorporating a bore, a piston assembly axially movable in said bore, means for moving the piston assembly axially in said bore, a first valve controlling communication between said bore and a first pAssage in said housing for connection to a return line to a reservoir, a second valve controlling communication between said bore and a second passage for connection to said high-pressure source, and an outlet connection leading from said bore for connection to said slave cylinder to apply said wheel brake, the arrangement being such that upon operation of said means for moving said piston assembly axially, said assembly is moved in said bore in one direction to close said first valve and open said second valve to permit high-pressure fluid to be supplied to said outlet connection, the invention comprising an antiskid device incorporated in said unit for sensing deceleration of said braked wheel, said antiskid device being adapted to move said piston assembly in a reverse direction to close said second valve and open said first valve when the deceleration of said braked wheel exceeds a predetermined value.

Claim 3

The invention as claimed in claim 1, wherein said means for moving said piston assembly axially in said bore comprises fluid pressure supplied from a master cylinder to the end of the bore remote from said antiskid device through a third passage in the housing.

Claim 4

The invention as claimed in claim 2, wherein a bypass passage in said housing connects the inlet from said second valve whereby, upon failure of the high-pressure source, said master cylinder pressure is delivered to said outlet connection through said second valve.

Claim 5

The invention as claimed in claim 3, wherein said bypass passage is normally closed by a third valve which opens automatically upon failure of the high-pressure source and when subjected to master cylinder pressure.

Claim 6

The invention as claimed in claim 4, incorporating means actuated by opening of said third valve to render said antiskid device inoperative.

Claim 7

The invention as claimed in claim 1, wherein said antiskid device comprises a solenoid-operated core, and an electrical pickup device sensing the deceleration of said baked wheel is adapted to produce a signal to move said core in the said reverse direction when said deceleration exceeds said predetermined value.

Claim 8

The invention as claimed in claim 1, wherein said antiskid device comprises an electrical pickup device sensing the deceleration of the braked wheel, a solenoid adapted to be energized in response to a signal received from said pickup device when said deceleration exceeds a predetermined value, and an angularly movable cam adapted to apply a thrust to said piston assembly when said solenoid is energized.

Claim 9

The invention as claimed in claim 7, wherein said cam is mounted on a disc, and said disc and an adjacent face of a stationary housing are provided with complementary inclined recesses, balls located in said recesses providing a camming action to move said cam angularly when said disc is moved axially towards said housing on energization of said solenoid.

Claim 10

The invention as claimed in claim 1, wherein said first and second valves each comprise a spring loaded tipping valve provided with a stem, and said stem extends into said bore into the path of an abutment movable upon movement of said piston assembly.

Claim 11

The invention as claimed in claim 9, wherein said bore in said housing is of stepped form and said piston assembly comprises a differential piston, and an axial extension on said differential piston has an end portion, and wherein a collar mounted on said extension through which projects said end portion carries said abutment, and an extension on the inner end of a core adapted to be operated upon energization of the solenoid of the antiskid device, has an inner end, a recessed head on said inner end of said last mentioned extension being adapted to engage the end of said collar remote from said differential piston.

Claim 12

The invention as claimed in claim 9, wherein said piston assembly comprises a plunger working through a sleeve in said bore, and said abutment comprises a radial flange on a spool working in said bore between adjacent ends on said plunger and a rod which is movable axially by said cam of the antiskid device to apply a thrust to the plunger through said spool.

Claim 13

A control unit for an hydraulic braking system for a vehicle of the type including a slave cylinder for apply a wheel brake, a source of high-pressure hydraulic fluid, and means for supplying fluid from said source to said slave cylinder, comprising a housing incorporating a first bore and a second bore communicating with said first bore, a piston assembly axially movable in said first bore, a first spring loaded tipping valve controlling communication between said first bore and a first passage in said housing for connection to a return line to a reservoir, a first sleeve housed within said second bore and having a closed inner end provided with a port, a second spring loaded tipping valve controlling communication between said second bore and said first bore through said port, an outlet connection leading from said first bore for connection to said slave cylinder to apply said wheel brake, a third passage communicating with one end of said first bore for connection to a master cylinder, a second sleeve located in said second bore against the end of said first sleeve remote from said second tipping valve, said second sleeve having a central longitudinal bore communicating with said first sleeve for connection to said high-pressure source and a check valve housed within said sleeve, said check valve comprising a head adapted to engage with a seating around said port, and a stem carrying said head and received in said longitudinal bore in said second sleeve, the arrangement being such that when subjected at one end to fluid under pressure through said third passage said piston assembly is movable in the bore in one direction to close said first tipping valve and open said second tipping valve to permit high-pressure fluid to be supplied to said outlet connection, and an antiskid device incorporated in said unit for sensing deceleration of said braked wheel, said antiskid device being adapted to move said piston assembly in a reverse direction to close said second tipping valve and open said first tipping valve when the deceleration of said braked wheel exceeds a predetermined value.

Claim 14

A control unit for an hydraulic braking system for a vehicle of the type including a slave cylinder for apply a wheel brake, a source of high-pressure hydraulic fluid, and means for supplying fluid from said source to said slave cylinder, comprising a housing incorporating a first bore and a second bore communicating with said first bore, a piston assembly axially movable in said first bore, a first spring loaded tipping valve controlling communication between said first bore and a first passage in said housing for connection to a return line to a reservoir, a first sleeve housed within said second bore and having a closed inner end provided with a port, a second spring loaded tipping valve controlling communication between said second bore and said first bore through said port, an outlet connection leading from said first bore for connection to said slave cylinder to apply said wheel brake, a third passage communicating with one end of said first bore for connection to a master cylinder, a second sleeve located in said second bore against the end of said first sleeve remote from said second tipping valve, said second sleeve having a central longitudinal bore communicating with said first sleeve for connection to said high-pressure source and a check valve housed within said sleeve, said check valve comprising a head adapted to engage with a seating around said port, and a stem carrying said head and received in said longitudinal bore in said second sleeve, the arrangement being such that when subjected at one end to fluid under pressure through said third passage said piston assembly is movable in the bore in one direction to close said first tipping valve and open said second tipping valve to permit high-pressure fluid to be supplied to said outlet connection, and an antiskid device incorporated in said unit for sensing deceleration of said braked wheel, said antiskid device being adapted to move said piston assembly in a reverse direction to close said second tipping valve and open said first tipping valve when the deceleration of said braked wheel exceeds a predetermined value.

Claim 15

A control unit as claimed in claim 12, wherein said seating and said head of said check valve are of complementary conical outline.

Claim 16

A control unit as claimed in claim 12, wherein said second sleeve has a conically shaped inner end and a first spring is adapted to urge said inner end in engagement with said adjacent end of first sleeve over an edge surrounding a bore in said first sleeve in which said head of said check valve is received, and wherein a second spring is adapted to urge the end of said head of said check valve remote from said seating into engagement with said inner conical end of said second sleeve.

Claim 17

A control unit as claimed in claim 14, wherein said second conical sleeve works in a central bore of a stepped sleeve of which the portion of said stepped sleeve of smaller diameter is received in a further sleeve which is in sealing engagement with a portion of the wall of said second bore in said housing.

Claim 18

A control unit as claimed in claim 15, wherein said second bore is a stepped form, and the said further sleeve is located in the portion of said stepped bore of greatest diameter.

Claim 19

A control unit as claimed in claim 12, wherein said second bore of stepped form, and said housing of said control unit has an inclined drilling which provides a connection between a portion of the stepped bore of greatest diameter and said third passage for connection to a master cylinder.

Claim 20

A control unit as claimed in claim 12, wherein said unit incorporates electrical brush gear and movement of said second sleeve in a direction away from said first sleeve is adapted to break contact with electrical brush gear to render said antiskid device inoperative.

Claim 21

In an hydraulic braking system for vehicles having a source of hydraulic fluid under pressure a slave cylinder for applying a wheel brake, and a pedal-operated master cylinder for controlling the supply of pressure fluid from said source to said slave cylinder through said control unit, said control unit comprises a housing incorporating a bore, a piston assembly axially movable in said bore, means for applying fluid pressure from said master cylinder to one end of said piston assembly to cause said assembly to move axially in said bore in one direction, a first valve controlling communication between said bore and a reservoir for said source, a second valve controlling communication between said source and said bore, and outlet connection between said bore and said slave cylinder whereby application of pressure from said master cylinder to said one end of said piston assembly is adapted to move said piston assembly in said one direction to close said first valve and open said second valve to permit high-pressure fluid to be supplied to said slave cylinder through said outlet connection, and said system incorporates an antiskid control device adapted to move said piston assembly in a reverse direction to close said second valve and open said first valve when the deceleration of said braked wheel exceeds a predetermined value.

Claim 22

In an hydraulic braking system for vehicles having a source of hydraulic fluid under pressure a slave cylinder for applying a wheel brake, and a pedal-operated master cylinder for controlling the supply of pressure fluid from said source to said slave cylinder through said control unit, said control unit comprises a housing incorporating a bore, a piston assembly axially movable in said bore, means for applying fluid pressure from said master cylinder to one end of said piston assembly to cause said assembly to move axially in said bore in one direction, a first valve controlling communication between said bore and a reservoir for said source, a second valve controlling communication between said source and said bore, and outlet connection between said bore and said slave cylinder whereby application of pressure from said master cylinder to said one end of said piston assembly is adapted to move said piston assembly in said one direction to close said first valve and open said second valve to permit high-pressure fluid to be supplied to said slave cylinder through said outlet connection, and said system incorporates an antiskid control device adapted to move said piston assembly in a reverse direction to close said second valve and open said first valve when the deceleration of said braked wheel exceeds a predetermined value.