Systems and methods for controlling trailer brakes as a function of trailer wheel rotation
First Claim
1. In a brake control system for use in an articulated system including a towing vehicle and a towed vehicle such as a trailer or the like of the type having first and second nondriven wheel units disposed at respective opposite sides of said towed vehicle, each wheel unit having at least one wheel therein, first and second brake means operatively associated with at least one wheel in each wheel unit, respectively, and brake activating means adapted to apply said first and said second brake means, the combination comprising first wheel sensing means responsive to rotation of at least a first wheel in at least a first of said wheel units for generating a first electrical signal which varies as a function of rotation of said first wheel, means responsive to said first signal when said towed vehicle is in a sway condition to provide a brake correction signal and brake regulating means operatively coupled to said brake activating means and responsive to said brake correction signal to apply said first brake means at one wheel in said first brake unit and simultaneously apply said second brake means at one wheel in said second unit to thereby increase the drag on said towed vehicle and correct said swaying condition.
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Accused Products
Abstract
Brake control systems and methods particularly suited for small trailers and the like wherein the angular velocity of each wheel in a selected pair of wheels is sensed and compared against each other to develop a control signal representing the differential in angular velocity between the respective paired wheels. In a skid control embodiment, while the brakes are being applied by the operator, the system automatically releases the brakes at both wheels in proportion to a velocity differential between the wheels indicating an impending skid. In the case of a trailer equipped with a sway control embodiment, the system automatically applies the brakes at both wheels in proportion to the wheel velocity differential representing excessive trailer sway. The respective skid control and sway control embodiments are useful alone or in a combined system. In a further modification, deceleration of the tractor-trailer unit when the tractor brakes are applied causes automatic trailer brake application proportional to trailer deceleration.
71 Citations
86 Claims
- 1. In a brake control system for use in an articulated system including a towing vehicle and a towed vehicle such as a trailer or the like of the type having first and second nondriven wheel units disposed at respective opposite sides of said towed vehicle, each wheel unit having at least one wheel therein, first and second brake means operatively associated with at least one wheel in each wheel unit, respectively, and brake activating means adapted to apply said first and said second brake means, the combination comprising first wheel sensing means responsive to rotation of at least a first wheel in at least a first of said wheel units for generating a first electrical signal which varies as a function of rotation of said first wheel, means responsive to said first signal when said towed vehicle is in a sway condition to provide a brake correction signal and brake regulating means operatively coupled to said brake activating means and responsive to said brake correction signal to apply said first brake means at one wheel in said first brake unit and simultaneously apply said second brake means at one wheel in said second unit to thereby increase the drag on said towed vehicle and correct said swaying condition.
- 34. In a brake control system for use in an articulated system including a towing vehicle and a towed vehicle such as a trailer or the like having towed vehicle operator responsive brake activating means for applying brake torque at each of a pair of wheel units located respectively at opposite sides of said towed vehicle, each of said pair of wheel units comprising at least one wheel, the combination for correcting sway of said towed vehicle comprising means generating first and second signals which vary as a function of wheel rotation of at least one wheel of each of said pair of units, respectively, means comparing said first and second signals to each other and providing a differential signal representing a difference between said first and second signals, and regulating means operatively coupled to said brake activating means and responsive to said differential signal to simultaneously apply brake torque at both wheel units substantially equally and in proportion to said differential signal.
- 39. The method of correcting for lateral sway of a towed vehicle of the type having a pair of wheel units disposed respectively at opposite sides of said towed vehicle, each unit having at least one wheel, comprising the steps of sensing wheel rotation of at least one wheel in a first of said wheel units, comparing said sensed wheel rotation with a reference to provide a correction indication when said wheel rotation of said one wheel in said first unit deviates from said reference and simultaneously applying braking forces to at least one wheel in each of said wheel units in response to said correction indication.
- 48. In a brake control system for use in an articulated vehicle system including a towing vehicle and a towed vehicle such as a trailer or the like having first and second nondriven wheel units disposed at respective opposite sides of said towed vehicle, each wheel unit having at least one wheel therein, first brake means operatively associated with at least one wheel in said first wheel unit, second brake means operatively associated with at least one wheel in said second unit, brake actuating means adapted to be controlled by an operator of a towing vehicle to apply said first and said second brake means, sway control means adapted to sense a sway condition at said trailer and operative to automatically apply said first and second brake means in response to said sway condition independent of said brake actuating means, skid control means adapted to sense an impending skid condition at one of said wheels occurring when the operator causes said brake actuating means to be actuated and operative to interrupt brake application at said first and second brake means, and selection means operative to disable said sway control means when said operator causes said brake actuating means to be actuated.
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54. In a brake control system for use in an articulated vehicle system including a towing vehicle and a towed vehicle such as a trailer or the like of the type having a first nondriven wheel unit at one side of said towed vehicle and a second nondriven wheel unit at an opposite side of said towed vehicle, first brake means operatively associated with one wheel in said first unit, second brake means operatively associated with a second wheel in said second wheel unit, first means for generating a brake correction signal which varies as a function of wheel rotation of at least one wheel in at least one of said wheel units, brake regulation means operable in a first mode to reduce brake application at one wheel in each wheel unit as a function of said correction signal and thereby correct for a skid condition and operable in a second mode to increase brake application at said one wheel in each wheel unit as a function of said correction signal and thereby correct for a sway condition, and mode selection means operable to switch said regulating means from one operating mode to the other operating mode depending on whether said correction signal is to be interpreted as representing a skid condition or a sway condition.
- 55. In a brake control system for use in an articulated system including a towing vehicle and a towed vehicle such as a trailer or the like of the type having first and second nondriven wheel units disposed at respective opposite sides of said towed vehicle, each wheel unit having at least one wheel therein, first and second brake means operatively associated with at least one wheel in each wheel unit, respectively, and brake activating means adapted to be activated by an operator of a towing vehicle to apply said first and said second brake means, the combination comprising first and second means for generating respective first and second signals which vary proportionally to the angular velocity of at least one wheel in each of said wheel units, respectively, means for comparing said first and second signals to each other and providing a differential signal representing a difference between said first and second signals, and means operatively coupled to said brake activating means and responsive to said differential signal for simultaneously regulating brake application by said first and said second brake means at one wheel in each wheel unit proportionally to said differential signal such that a change in wheel speed differential between one wheel in one unit and one wheel in the other unit causes a corresponding change in brake regulation, and wherein said regulating means is adapted to correct for an impending skid and said regulating means further comprises brake driver means operative when said operator has caused application of said brake means and responsive to an increase in said differential signal to decrease brake application automatically at both said first and said second brake means proportionally to said differential signal to thereby correct for an impending skid condition, and wherein said regulating means further comprises locked wheel circuit means for overriding release of said brake means and said locked wheel circuit means comprises first detection circuit means responsive to said first and said second signals for providing a third signal when either one of said first and second signals is less than a first predetermined minimum level, and output means coupled to said brake driver means to cause said brake driver means to completely release said first and second brake means in response to said third signal so that if one or both of said wheel locks, said first and second brake means are completely released to correct for an impending skid, said locked wheel circuit means further comprises arming circuit means for disabling said locked wheel circuit means until said towed vehicle reaches a predetermined speed, said arming circuit means comprises second detection circuit means responsive to said first and and said second signals for providing a fourth signal when at least one of said first and second signals is less than said second predetermined minimum level, and means connected to said output means to disable said output means in response to said fourth signal so that said output means cannot cause said brake driver means to completely release said brake means until after said towed vehicle reaches said predetermined speed.
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57. The method of correcting for skid of a towed vehicle while an operator of a towing vehicle is causing braking forces to be applied to at least one wheel in each of a pair of wheel units disposed relatively at opposite sides of said towed vehicle comprising the steps of sensing the angular velocity of at least one wheel in each wheel unit, comparing said angular velocities from each wheel unit to each other and simultaneously releasing said operator applied braking forces to at least one wheel in each unit proportionally to said velocity differential, and wherein said operator applied braking forces are released at a wheel in each wheel unit in linear proportion to said velocity differential.
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58. In a brake control system for use in an articulated system including a towing vehicle and a towed vehicle such as a trailer or the like of the type having first and second nondriven wheel units disposed at respective opposite sides of said towed vehicle, each wheel unit having at least one wheel therein, first and second brake means operatively associated with at least one wheel in each wheel unit, respectively, and brake activating means adapted to be activated by an operator of a towing vehicle to apply said first and said second brake means, the combination comprising first and second means for generating respective first and second signals which vary proportionally to the angular velocity of at least one wheel in each of said wheel units, respectively, means for comparing said first and second signals to each other and providing a differential signal representing a difference between said first and second signals, and means operatively coupled to said brake activating means and responsive to said differential signal for simultaneously regulating brake application by said first and said second brake means at one wheel in each wheel unit proportionally to said differential signal such that a change in wheel speed differential between one wheel in one unit and one wheel in the other unit causes a corresponding change in brake regulation, and wherein said regulating means regulates brake application at both wheel units in linear proportion to said differential signal.
- 59. In a brake control system for use in an articulated system including a towing vehicle and a towed vehicle such as a trailer or the like of the type having first and second nondriven wheels disposed at respective opposite sides of said towed vehicle and brake means for applying brake torque at both of said wheels and including at least one electrically operated brake actuator, means for providing an electrical signal for operating said electrically operated brake actuator, said last-mentioned means including an electric brake controller adapted for actuation by the operator of said towing vehicle to vary said electrical signal and thereby vary brake actuation, and automatic brake regulation means to correct for an impending skid condition at said trailer comprising first means for generating a first signal which varies proportionally to the angular velocity of a first of said towed vehicle wheels, second means for generating a second signal which varies proportionally to the angular velocity of said second trailer wheel, means for comparing said first and said second signals to each other and providing a differential correction signal representing a difference between said first and said second signals, and output means including a controlled conduction device responsive to said differential signal and connected in series between said controller and said electrically operated brake actuator to decrease said electrical signal proportionally to said differential signal such that an increase in wheel speed differential between said first and second wheels causes a corresponding proportional decrease in brake actuation independent of said electric brake controller.
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61. In a brake control system for use in an articulated system including a towing vehicle and a towed vehicle such as a trailer or the like of the type having first and second nondriven wheel units disposed at respective opposite sides of said towed vehicle, each wheel unit having at least one wheel therein, first and second brake means operatively associated with at least one wheel in each wheel unit, respectively, and brake activating means adapted to be activated by an operator of a towing vehicle to apply said first and said second brake means, the combination comprising first and second means for generating respective first and second signals which vary proportionally to the angular velocity of at least one wheel in each of said wheel units, respectively, means for comparing said first and second signals to each other and providing a differential signal representing a difference between said first and second signals, and means operatively coupled to said brake activating means and responsive to said differential signal for simultaneously regulating brake application by said first and said second brake means at one wheel in each wheel unit proportionally to said differential signal such that a change in wheel speed differential between one wheel in one unit and one wheel in the other unit causes a corresponding change in brake regulation.
- 62. In a brake control system for use in an articulated system including a towing vehicle and a towed vehicle such as a trailer or the like of the type having first and second nondriven wheel units disposed at respective opposite sides of said towed vehicle, each said wheel unit having at least one wheel therein, and brake means for applying brake torque at both of said wheel units and including at least one electrically operated brake actuator, means for providing an electrical signal for operating said electrically operated brake actuator, said last-mentioned means including an electric brake controller to vary said electrical signal and thereby vary brake actuation, and automatic brake regulation means to correct for an impending skid condition at said trailer comprising first means for generating a first signal which varies proportionally to the angular velocity of at least one wheel in at least a first of said towed vehicle wheel units, second means for generating a second signal which varies proportionally to the angular velocity of at least one wheel in said second trailer wheel unit, means for comparing said first and said second signals to each other and providing a differential correction signal representing a difference between said first and said second signals, and output means including a controlled conduction device responsive to said differential signal and connected in series with said controller and said electrically operated brake actuator to decrease said electrical signal proportionally to said differential signal such that an increase in wheel speed differential between said first and second wheel units causes a corresponding proportional decrease in brake actuation independent of said electric brake controller.
- 66. The method of controlling braking of a towed vehicle of the type having a pair of wheel units disposed respectively at opposite sides of said towed vehicle, each unit having at least one wheel, comprising the steps of sensing wheel rotation of at least one wheel in a first of said wheel units, comparing said sensed wheel rotation with a reference to provide a control signal when said wheel rotation of said one wheel in said first unit deviates from said reference and simultaneously applying braking forces to at least one wheel in each of said wheel units in response to said control signal.
- 75. In a brake control system for use in an articulated vehicle system including a towing vehicle and a towed vehicle such as a trailer or the like of the type having first and second nondriven wheel units disposed at respective opposite sides of said towed vehicle, each wheel unit having at least one wheel therein, first and second brake means operatively associated with at least one wheel in each wheel unit, respectively, and brake activating means adapted to apply said first and said second brake means, the combination comprising sensing means including first means responsive to rotation of at least a first wheel in at least a first of said wheel units for generating a first electrical signal which varies as a function of rotation of said first wheel, means responsive to said first signal when said towing vehicle is being braked to provide a brake signal, and brake regulating means operatively coupled to said brake activating means and responsive to said brake signal to apply said first brake means at one wheel in said first brake unit and simultaneously apply said second brake means at one wheel in said second unit as a function of said brake signal.
- 82. A brake control system for use in an articulated vehicle system including a towing vehicle and a towed vehicle such as a trailer or the like of the type having a first nondriven wheel unit at one side of said towed vehicle and a second nondriven wheel unit at an opposite side of said towed vehicle, first brake means operatively associated with one wheel in said first unit and second brake means operatively associated with a second wheel in said second wheel unit, said brake system comprising brake regulation means operable in a first mode to reduce brake application at one wheel in at least one wheel unit as a function of said correction signals and thereby correct for a skid condition and operable in a second mode to increase brake application at one wheel in at least one wheel unit as a function of said correction signals and thereby correct for a sway condition, first means for generating brake correction signals which vary as a function of trailer condition, and mode selection means operable to switch said regulating means from one operating mode to the other operating mode depending on whether said correction signals are to be interpreted as representing a skid condition or a sway condition.
- 84. In a brake control system for a vehicle adapted to be towed over a road surface and having at least first and second wheel units disposed on opposite sides of said vehicle and brake means disposed at each said wheel units for braking at least one wheel in each said wheel units, braking forces at said wheel units being respective functions of available coefficients of friction between each of said wheel units and a road surface, means responsive to angular velocity of at least one wheel in said first wheel unit to develop a first wheel speed signal, means responsive to angular velocity of at least one wheel in said second wheel unit to develop a second wheel speed signal, and means for controlling braking forces at said first and second wheel units substantially equally as a proportional function of said first and second wheel speed signals and at a uniform level consistent with the lowest coefficient of friction available between said first and second wheel units and a road surface.
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86. A method of correcting a skid condition as between first and second braked wheel units disposed on opposite sides of a towed vehicle and respectively in contact with surfaces having unequal first and second available coefficients of friction comprising the steps of sensing a difference in angular velocity between the braked wheel unit on the surface having the higher of said first and second available coefficients of friction and the wheel unit on the surface having the lower of said first and second available coefficients of friction, and reducing braking forces at both said wheel units substantially simultaneously in proportion to said difference to a highest uniform braking level at both said wheel units which is consistent with said lower available coefficient of friction.
Specification