Fluid-pressure operated anti-skid braking systems for vehicles
First Claim
1. A fluid-pressure operated braking system for vehicles comprising first and second wheels provided at each end of a common axle, first and second wheel brakes for said first and second wheels respectively, a supply for providing brake-applying operating fluid to each wheel brake, an operating fluid supply line between said supply and each said brake, respective first and second separate independently operable skid control units interposed respectively in said line between said supply and said first and second brakes, sensors provided to detect the skid point of wheel skids and to provide a skid signal when a skid point is detected, means responsive to a skid signal produced by any of said sensors, valve means provided to relieve independently the pressure of the fluid supplied to said first and second brakes at a skid point, each said skid control unit comprising a part of a control fluid circuit and each incorporating a memory chamber for storing a memory pressure dependent upon the brake pressure occurring at said skid point to provide a datum or knee point between first and second stages of brake re-application, said valve means being controlled by said means responsive to a skid signal, wherein said first and second brakes on said respective first and second wheels are each controlled by one of said separate respective independently operable skid control units, and a single latch valve is provided common to both units, said latch valve closing at the first skid point to be sensed by one of said sensors on either wheel, whereafter said rate of re-application of each of said first and said second brakes is controlled in response to signals from the individual sensors at a respective initial rate and thereafter at a subsequent rate, said initial rate of brake pressure increase of said first brake being determined by said memory chamber of said first skid control unit and said initial rate of brake pressure increase of said second brake being determined by said memory chamber of said second skid control unit, said subsequent rate of brake re-application of said first and said second brake being controlled by a common restricted flow of said brake-applying fluid.
2 Assignments
0 Petitions
Accused Products
Abstract
Brakes (3, 4) on the wheels (7, 8) on a common axle are each controlled by a separate skid control unit (16, 17) each including a memory chamber (33, 34), and a single latch valve (21) common to both units closes at the first skid point to be sensed by a sensor (11, 12) on each wheel. The rate of re-application of the two brakes is controlled in response to signals from the individual sensors, but at rates of pressure increase determined by each respective memory chamber, and by flows of pressure controlled by restrictors (47).
21 Citations
12 Claims
- 1. A fluid-pressure operated braking system for vehicles comprising first and second wheels provided at each end of a common axle, first and second wheel brakes for said first and second wheels respectively, a supply for providing brake-applying operating fluid to each wheel brake, an operating fluid supply line between said supply and each said brake, respective first and second separate independently operable skid control units interposed respectively in said line between said supply and said first and second brakes, sensors provided to detect the skid point of wheel skids and to provide a skid signal when a skid point is detected, means responsive to a skid signal produced by any of said sensors, valve means provided to relieve independently the pressure of the fluid supplied to said first and second brakes at a skid point, each said skid control unit comprising a part of a control fluid circuit and each incorporating a memory chamber for storing a memory pressure dependent upon the brake pressure occurring at said skid point to provide a datum or knee point between first and second stages of brake re-application, said valve means being controlled by said means responsive to a skid signal, wherein said first and second brakes on said respective first and second wheels are each controlled by one of said separate respective independently operable skid control units, and a single latch valve is provided common to both units, said latch valve closing at the first skid point to be sensed by one of said sensors on either wheel, whereafter said rate of re-application of each of said first and said second brakes is controlled in response to signals from the individual sensors at a respective initial rate and thereafter at a subsequent rate, said initial rate of brake pressure increase of said first brake being determined by said memory chamber of said first skid control unit and said initial rate of brake pressure increase of said second brake being determined by said memory chamber of said second skid control unit, said subsequent rate of brake re-application of said first and said second brake being controlled by a common restricted flow of said brake-applying fluid.
- 10. A fluid-pressure operated braking system for vehicles comprising first and second wheel brakes at opposite ends of a common axle, a supply for providing brake-applying operating fluid to said first and second wheel brakes, first and second fluid supply lines leading from said supply to said first and second brakes respectively, first and second skid control units interposed respectively in said first and second lines between said supply and said first and second brakes, sensors provided to detect wheel skids and to provide skid signals in response to wheel skids, first and second respective valve means provided to relieve the pressure of said fluid supplied to said first and second brakes at a skid point, means responsive to a said skid signal provided to control said first and second valve means, each said skid control unit comprising a part of a control fluid circuit and incorporating a memory chamber for storing a memory pressure dependant upon the brake pressure occurring at said skid point to provide a datum or knee point between first and second stages of brake re-application, wherein during said first stage of brake re-application said brake pressure is increased at a rate dependant on said memory pressure and during said second stage of brake re-application said brake pressure is increased at a slower rate than that at which it is increased during said first stage, and wherein each skid control unit incorporates means for producing the second stage of brake re-application which means comprising a restricted flow valve adapted to be installed in a by-pass passage for control fluid and located between a source of control fluid pressure and the downstream side of a latch valve which determines said skid point, said flow valve comprising a seating, a valve member, and a restricted orifice defined between said seating and said valve member, said valve member having a first position when said control fluid flows in one direction in said by-pass passage towards said skid control unit to apply said brake, in which said first position said valve member engages said seating to define said restricted orifice and permit a restricted flow of control fluid through said restricted orifice, and said valve member having a second position when said control fluid flows in the opposite direction in said by-pass passage to relieve the pressure in said skid control unit during normal braking when no skid point has been detected, in which said second position said valve member is spaced from said seating to define a larger orifice than said restricted orifice, a greater flow rate in said opposite direction being possible through said flow valve when said valve member is in said second position than is possible in said one direction when said valve member is in said first position, and wherein said latch valve of said first skid control unit and said latch valve of said second skid control comprise a single, common, latch valve, the rate of said second stage of brake re-application being independent from said single, common, latch valve since said brake-applying fluid flows through said by-pass passages of said first and second skid control units to completely by-pass said single, common, latch valve during said second stage of brake re-application.
Specification