Trailer brake control system
First Claim
1. A brake control system for applying brakes at trailer wheels as a function of trailer acceleration comprising variable frequency oscillator means having a nominal output frequency and an output frequency range both substantially greater than one hertz, sensor means adapted to be disposed on a trailer and responsive when so disposed to acceleration of said trailer for varying the output frequency of said oscillator means from said nominal frequency as a function of such acceleration, and means for regulating braking at the trailer wheels as a function of a difference between said oscillator output frequency frequency and said nominal frequency;
- said regulating means comprising converter means for receiving said oscillator output and providing a d.c. control signal as a function of said difference between said oscillator output and said nominal output, and brake control means for controlling braking at the trailer wheels as a proportional function of said d.c. control signal.
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Accused Products
Abstract
A trailer brake control system which includes a variable frequency oscillator, an electromagnetic inertial sensor adapted to detect either lateral acceleration or longitudinal deceleration of a trailer and to vary the output frequency of the oscillator in accordance therewith, and a circuit for applying trailer brakes as a function of such frequency variation either to correct a trailer sway condition indicated by lateral trailer acceleration or when tractor brakes have been applied as indicated by longitudinal deceleration of the tractor/trailer combination.
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Citations
22 Claims
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1. A brake control system for applying brakes at trailer wheels as a function of trailer acceleration comprising variable frequency oscillator means having a nominal output frequency and an output frequency range both substantially greater than one hertz, sensor means adapted to be disposed on a trailer and responsive when so disposed to acceleration of said trailer for varying the output frequency of said oscillator means from said nominal frequency as a function of such acceleration, and means for regulating braking at the trailer wheels as a function of a difference between said oscillator output frequency frequency and said nominal frequency;
- said regulating means comprising converter means for receiving said oscillator output and providing a d.c. control signal as a function of said difference between said oscillator output and said nominal output, and brake control means for controlling braking at the trailer wheels as a proportional function of said d.c. control signal.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- 13. A brake control system for correcting a sway condition on trailers having at least one braked wheel comprising variable frequency oscillator means having a nominal output frequency, sensor means adapted to be disposed on a trailer and responsive when so disposed to acceleration of said trailer in a direction transverse to the direction of forward trailer travel for varying the output frequency of said oscillator means from said nominal frequency as a function of said acceleration, regulating means for applying brakes at the trailer wheels as a function of a difference between said oscillator output frequency and said nominal frequency, and low speed lockout means for inhibiting operation of said regulating means when the traveling speed of a said trailer is below a first preselected threshold, said low speed lockout means including means for sensing angular velocity of a trailer wheel comprising magnet means rotatably carried by said trailer wheel and switch means fixedly carried with respect to said wheel adjacent the path of said magnet means on said wheel and responsive to passage of said magnet means thereby to provide a wheel speed signal as a periodic function of said wheel angular velocity.
- 16. A brake control system for correcting a sway condition on trailers having at least one braked wheel comprising variable frequency oscillator means having a nominal output frequency, sensor means adapted to be disposed on a trailer and responsive when so disposed to acceleration of said trailer in a direction transverse to the direction of forward trailer travel for varying the output frequency of said oscillator means from said nominal frequency as a function of said acceleration, regulating means for applying brakes at the trailer wheels as a function of a difference between said oscillator output frequency and said nominal frequency, and low speed lockout means for inhibiting operation of said regulating means when the traveling speed of a said trailer is below a first preselected threshold, said regulating means including means responsive to said difference for applying said trailer brakes only when said difference exceeds a second preselected threshold.
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18. A brake control system for use on trailers having at least one braked wheel comprising oscillator means having a variable output frequency, sensor means adapted to be disposed on a trailer and responsive when so disposed to acceleration of said trailer for varying the output frequency of said oscillator means as a function of said acceleration, and means for regulating braking at the trailer wheels as a function of said oscillator output frequency;
- said sensor means comprising an electrical coil adapted to be mounted in fixed position with an axis oriented substantially horizontally relative to a trailer and operatively connected to said oscillator means such that said oscillator output frequency varies with the inductance of said coil, and a core of magnetically permeable material disposed internally of said coil and movable substantially axially with respect to said coil to vary the inductance of said coil as a function of trailer acceleration.
- View Dependent Claims (19)
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20. In combination with a braked vehicle wheel which includes a brake drum providing a braking surface carried by the wheel for corotation therewith and a backing plate for mounting brake application means adjacent said braking surface and in fixed position relative to the vehicle, a transducer for sensing angular velocity of the wheel and comprising magnet means carried at a peripheral edge of said brake drum closely adjacent said backing plate to rotate with the wheel in a fixed path relative to said plate, a reed switch carried by said plate at substantially the radius of said adjacent peripheral edge and adapted to assume a closed conductive condition when said magnet means is adjacent said switch and an open conductive condition when said magnet means is remote from said switch, and circuit means responsive to successive periodic changes in said conductive conditions of said switch to provide an indication of wheel angular velocity, said circuit means including a source of electrical energy, means for storing electrical energy from said source in said closed conductive condition of said switch and blocking energy from said storage means in said open conductive condition of said switch, and means for bleeding stored energy from said storage means directly electrically connected in parallel with said storage means so as to bleed energy from said storage means independently of said switch such that the average energy level on said storage means increases in direct proportion to said angular velocity.
- 21. A transducer for sensing acceleration of a movable body comprising an electrical coil adapted to be mounted in fixed position relative to a said body and having a coil axis, a core of magnetic material magnetically coupled to said coil such that inductance of said coil varies as a function of the position of said core relative to said coil, and spring means mounting said core internally of said coil for resilient movement with respect to said coil substantially in the direction of said coil axis such that said coil inductance varies as a function of acceleration of the movable body in the direction of said coil axis.
Specification