Electric trailer brake controller

• US 20050127747A1
• Filed: 02/01/2005
• Published: 06/16/2005
• Est. Priority Date: 10/09/2003
• Status: Active Grant

• Current Assignee: Hopkins Manufacturing Corporation (Hoppy Holdings Corp.)
• Original Assignee: Hayes Brake Controller Co. LLC (Syncro Corp.)
• Inventors: Robertson, Charles L.
• Granted Patent: US 7,311,364 B2
• Time in Patent Office: Days
• US Class Current: 303/20
• CPC Class Codes: B60T 13/74 with electrical assistance or drive
• CPC Class Codes: B60T 7/20 specially for trailers, e.g. in case of uncoupling of or overrunning by trailer inertia-actuated overrun brakes B60T13/08

Abstract

A micro processor based electric brake controller includes a multi-axis accelerometer that senses deceleration of a towing vehicle along a plurality of directional axes. The controller also includes a microprocessor that is responsive to the sensed decelerations to supply power to trailer brakes that is a function of the deceleration.

Claims

1. A trailer brake controller comprising:

a multi-axis accelerometer that generates a plurality of deceleration signals;

a microprocessor connected to said accelerometer and responsive to said deceleration signals to generate an output brake actuation signal which is related to said deceleration signals; and

at least one pushbutton connected to said microprocessor, said pushbutton being operative to change selected operating parameters of said microprocessor.

2. The trailer brake controller according to claim 1 wherein said multi-axis accelerometer is a two axis that includes first and second sensor devices for sensing deceleration along first and second axes, said second axis being perpendicular to said first axis, and further wherein said accelerometer generates a pair of deceleration signals that are a function the deceleration of a towing vehicle.

3. The trailer brake controller according to claim 2 wherein said microprocessor combines said deceleration signals in accordance with the following formula:

Deceleration=1 g times arctan(A_OUTY/A_OUTX), where

g=the force of gravity,

A_OUTY is the output of said second sensor device,

A_OUTX is the output of said first sensor device, and

arctan(A_OUTY/A_OUTX) is the angle between the controller and a reference plane in radian degrees.

4. The trailer brake controller according to claim 3 wherein said reference plane is vertical.

5. The trailer brake controller according to claim 3 wherein said reference plane is horizontal.

6. The trailer brake controller according to claim 3 further including a compensating factor in accordance with the following formula:

Deceleration=1 g times{arctan(A_OUTY/A_OUTX)−

arctan(A_OUTY/A_OUTX0)},

where

g=the force of gravity,

A_OUTY is the output of said second sensor device,

A_OUTX is the output of said first sensor device,

arctan(A_OUTY/A_OUTX) is the angle between the controller and said reference plane plane in radian degrees.

A_OUTY0 is the “

zero”

output of said second sensor device,

A_OUTX0 is the “

zero”

output of said first sensor device, and

arctan(A_OUTY0/A_OUTX0) is a mounting angle between the controller and said reference plane in radian degrees.

7. The trailer brake controller according to claim 6 wherein said zero outputs are calculated from a rolling weighted average of sensor outputs by said microprocessor in accordance with a stored algorithm.

8. The trailer brake controller according to claim 7 wherein said rolling weighted average of sensor outputs begins with initial sensor output values sensed upon an initial brake application.

9. The trailer brake controller according to claim 6 wherein said zero outputs are initially set for the controller by depressing said pushbutton, said zero outputs being stored by said microprocessor.

10. The trailer brake controller according to claim 2 wherein said microprocessor combines said deceleration signals in accordance with the following formula:

Deceleration={{square root}(A_OUTX²+A_OUTY²)|+1 g times sin{arctan(A_OPUTY/A_OUTX)−

arctan(A_OUTY0/A_OUTX0)}, where

g=the force of gravity,

A_OUTY is the output of said second sensor device,

A_OUTX is the output of said first sensor device,

arctan(A_OUTY/A_OUTX) is the angle between the controller and a reference plane in radian degrees, and

sin represents the sine of the angle determined within the brackets.

11. The trailer brake controller according to claim 1 wherein said multi-axis accelerometer is a three axis that includes first, second and third sensor devices for sensing deceleration along first, second and third axes, said second axis being perpendicular to said first axis, and said third axis being perpendicular to a plane defined by said first and second axes, and further wherein said accelerometer generates a three deceleration signals that are a function the deceleration of a towing vehicle.

12. The trailer brake controller according to claim 11 wherein said microprocessor combines said deceleration signals in accordance with the following formulas:

Deceleration(X,Y)=1 g times arctan(A_OUTY/A_OUTX), and
Deceleration(Y,Z)=1 g times arctan(A_OUTY/A_OUTZ),
Deceleration(X,Y,Z)=1 g times arctan(Deceleration(X,Y)/Deceleration(Y,Z),

where

g=the force of gravity,

A_OUTY is the output of said second sensor device,

A_OUTX is the output of said first sensor device,

A_OUTX is the output of said third sensor device,

arctan(A_OUTY/A_OUTX) is an angle between the controller and a horizontal plane in radian degrees, and

arctan(A_OUTY/A_OUTZ) is an angle between the controller and a vertical plane in radian degrees.

13. The trailer brake controller according to claim 11 wherein said microprocessor combines said deceleration signals in accordance with the following formulas:

Deceleration(X,Y)={square root}(A_OUTX²+A_OUTY²)|+1 g times(A_OUTY/A_OUTX),
Deceleration(Z,Y)={square root}(A_OUTZ²+A_OUTY²)|+1 g times(A_OUTZ/A_OUTX), and
Deceleration(X,Y,Z)={{square root}(Deceleration(X,Y)²+Deceleration(Y,Z)²)|+1 g times[Deceleration(X,Y)/Deceleration(Y,Z)],

where g=the force of gravity,

A_OUTY is the output of said second sensor device,

A_OUTX is the output of said first sensor device,

A_OUTX is the output of said third sensor device,

arctan(A_OUTY/A_OUTX) is an angle between the controller and a horizontal plane in radian degrees, and

arctan(A_OUTY/A_OUTZ) is an angle between the controller and a vertical plane in radian degrees.

14. The trailer brake controller according to claim 6 further including a power switch which is adapted to be connected between a power supply and a set of trailer brake coils, said power switch also connected to an output pin of said microprocessor and responsive to said brake control signal to supply power to said trailer brake coils that is a function of said brake control signal.

15. The trailer brake controller according to claim 14 wherein said power switch is a programmable current sensing power switch.

16. The trailer brake controller according to claim 15 wherein said power switch is also connected to a current feedback port of said microprocessor, said microprocessor being operative to monitor the current being supplied to said trailer brake coils and being further operative, upon the brake coil current exceeding a predetermined threshold, to cause said power switch to change to a non-conducting state for a predetermined period of time.

17. The trailer brake controller according to claim 14 wherein said power supplied by said power switch to said trailer brake coils is bounded by a minimum limit and a maximum limit.

18. The trailer brake controller according to claim 17 including a pair of pushbuttons that are selectively operative to select said minimum and maximum brake power limits.

19. The trailer brake controller according to claim 18 wherein adjustment of said maximum brake power limit adjusts the maximum power to be delivered to said brake coils and also adjusts the slope of a brake power output curve that relates the power delivered to said trailer brake coils to the deceleration sensed by said accelerometer.

20. The trailer brake controller according to claim 19 wherein adjustment of said minimum brake power limit adjusts the minimum power to be delivered to said trailer brake coils and also vertically shifts said brake power output curve.

21. The trailer brake controller according to claim 20 wherein at least one minimum brake power limit adjustment supplies a minimum power to said brake coils while also delaying application of increased brake power in accordance with said output curve.

22. The trailer brake controller according to claim 14 wherein said microprocessor includes an internal ROM that stores coding for an algorithm that controls the operation of the brake controller and further wherein said microprocessor also includes an internal EEPROM that receives and stores said selected minimum and maximum brake power limits.

23. The trailer brake controller according to claim 22 further including a visual display, said microprocessor being operative to monitor parameters within the trailer brake circuit and, upon detection of a problem, to illuminate said display to inform the operator of the towing vehicle of the problem.

24. The trailer brake controller according to claim 23 wherein said microprocessor is further operative to monitor output parameters of the controller and further wherein selective manipulation of said pushbuttons will display a selected parameter to the operator of the towing vehicle.

25. The trailer brake controller according to claim 24 wherein said selected parameter is one of percent controller power output, controller voltage output and controller current output.

26. The trailer brake controller according to claim 25 wherein said selected parameter is stored in said microprocessor EEPROM.