Method of and Apparatus for Braking a Tractor-Trailer Combination

• US 20140343813A1
• Filed: 11/10/2011
• Published: 11/20/2014
• Est. Priority Date: 07/04/2011
• Status: Active Grant

• Current Assignee: Blue Leaf IP Incorporated (CNH Industrial N.V.)
• Original Assignee: CNH Industrial America LLC (CNH Industrial N.V.)
• Inventors: Morselli, Riccardo, Canuto, Francesco, Paravizzini, Pier Paolo
• Granted Patent: US 9,481,346 B2
• Time in Patent Office: Days
• US Class Current: 701/70
• CPC Class Codes: B60T 13/08 Overrun brakes
• CPC Class Codes: B60T 13/662 characterised by specified functions of the control system components
• CPC Class Codes: B60T 13/686 in hydraulic systems or parts thereof
• CPC Class Codes: B60T 2230/06 Tractor-trailer swaying
• 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
• CPC Class Codes: B60T 8/1708 for lorries or tractor-trailer combinations
• CPC Class Codes: B60T 8/176 Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS B60T8/1755 takes precedence
• CPC Class Codes: B60T 8/248 Trailer sway, e.g. for preventing jackknifing
• CPC Class Codes: B62D 53/00 Tractor-trailer combinations; Road trains traction couplings other than fifth wheel coupling B60D ; tracked vehicles comprising at least two articulated parts B62D55/0655

Abstract

A method of controlling the braking of a tractor-trailer combination (10) in which the tractor (11) includes a drive train having an engine and at least one ground-engaging member (14, 16) driveably connected thereto via an adjustable-ratio transmission; at least one ground-engaging member (14, 16) of the tractor includes at least one tractor brake; and at least one ground-engaging member (17) of the trailer (12) includes at least one further, trailer brake, comprises the steps of determining (i) the deceleration of the tractor-trailer combination (10) resulting from braking effort applied via the tractor brake and/or (ii) the deceleration of the tractor-trailer combination resulting from engine braking. The method also includes establishing from one or both the said, determined decelerations as a target value in a control system a braking effort of the trailer brake that approximates the braking of the tractor-trailer combination (10) to the braking of the tractor (11) when considered alone.

Claims

1. A method of controlling the braking of a coupled tractor-trailer combination in which the tractor includes a drive train having an engine and at least one ground-engaging member driveably connected thereto via an adjustable-ratio transmission;

at least one ground-engaging member of the tractor includes at least one tractor brake; and

at least one ground-engaging member of the trailer includes at least one further, trailer brake, the method comprising;

determining a reference deceleration value AX_REF derived from (i) the deceleration of the tractor, when considered alone, resulting from braking effort applied via the tractor brake and/or (ii) the deceleration of the tractor, when considered alone, resulting from engine braking; and

using the reference value as a control input in an open-loop control to control the braking effort of the trailer brake so that the braking of the tractor-trailer combination approximates to the braking of the tractor when considered alone.

2. A method according to claim 1 including the steps of determining from the reference deceleration value, in accordance with a predetermined relation, a target value of the braking effort of the trailer brake.

3. A method according to claim 2, wherein the reference deceleration value is calculated in accordance with the expression

4. A method according to claim 3, wherein the target value of the braking effect of the trailer brake is F_TRACTOR—

<sub>BRAKES—

OPEN—

LOOP</sub> and is related to the reference deceleration value AX_REF by the expression;

5. A method according to claim 2 wherein the target value is generated as a fluid pressure value, wherein the method includes inputting the target value into a control system controlling the pressure of fluid in the trailer brake valve and activating at least one said trailer brake in dependence on the target value;

and wherein the target value of the braking effort of the trailer brake(s) is calculated based on an average value of fluid pressure in a circuit including at least one trailer brake.

6. A method according to claim 5 wherein the average value of fluid pressure is an average of a time-varying pressure value or a time-invariant pressure value.

7. A method according to claim 2 wherein the trailer brake includes a trailer brake fluid line and the predetermined relation is a combination of:

(i) a function relating on the one hand the pressure of fluid in the tractor brake fluid line resulting from the application of the tractor brake and on the other hand the braking effort of the trailer brake; and

(ii) a function relating on the one hand the braking effort resulting from engine braking and on the other hand the pressure of fluid in the trailer brake fluid line.

8. A method according to claim 5, wherein when the reference deceleration value is determined from the deceleration of the tractor resulting from braking effort applied via the tractor brake the pressure of fluid in the trailer brake valve is controlled to be the prevailing maximum based on the difference between the reference braking effort value and the value of the braking effort applied via the tractor brake, the said controlling terminating if the difference between the reference braking effort value and the value of the braking effort applied via the tractor brake is less than a chosen threshold value.

9. A method according to claim 1 including the steps of measuring or sensing one or more of the following values and determining the reference value in dependence thereon:

a) the torque developed by the engine;

b) the prevailing ratio of the transmission;

c) the steering angle, as defined herein, of the tractor;

d) the slope on which the tractor-trailer combination moves; and

e) the vehicle speed.

10. A method according to claim 1 wherein the transmission is a step ratio transmission or wherein the transmission is a continuously variable transmission.

11. A method according to claim 1 wherein the reference deceleration value calculated during deceleration resulting from the braking effort applied via the tractor brake is calculated at least in part in proportion to a measurable setting of the tractor brake;

wherein the tractor brake includes at least one fluid line; and

wherein the measurable setting of the tractor brake is or is proportional to the pressure of fluid in the fluid line.

12. A method according to claim 1 wherein the reference deceleration value calculated during engine braking is calculated in proportion to the transmission ratio of the transmission and in proportion to the torque developed by the engine.

13. A method according to claim 1 including the step of determining the deceleration of the tractor-trailer combination resulting from braking effort applied via the tractor brake and/or the deceleration of the tractor-trailer combination resulting from engine braking using one or more of an accelerometer that measures deceleration of the tractor and/or a force transducer that measures forces in one or more of the drive train of the tractor and/or the connection between the tractor and trailer of the combination, and/or a sensor sensing a change in the ratio of the transmission.

14. A method according to claim 1 wherein the deceleration of the tractor-trailer combination for a braking effort applied via the tractor brakes is less than when the same braking effort is applied via the tractor brakes in the absence of a trailer.

15. A method according to claim 3 including calculation of the reference deceleration value AX_REF in a form A_X—

<sub>REF—

COMP</sub> that is a reference deceleration value compensated for the angle α

of a slope on which the tractor-trailer combination operates, A<sub>X—

REF—

COMP</sub> being determined in accordance with the expression

16. An apparatus, comprising:

a) a tractor having a drive train including an engine and at least one ground-engaging member driveably connected thereto via an adjustable-ratio transmission, at least one ground-engaging member of the tractor including at least one tractor brake;

b) a trailer having at least one ground-engaging member that includes at least one further, trailer brake;

c) an activator for the at least one tractor brake;

d) an activator for the at least one trailer brake;

e) at least one sensor for sensing one or more variables giving rise to deceleration of the tractor-trailer combination resulting from braking effort applied via the tractor brake;

f) at least one sensor for sensing one or more variables giving rise to deceleration of the tractor-trailer combination resulting from engine braking; and

g) at least one preferably programmable control device for establishing from the outputs of one or more said the said sensor devices a target value in a control system corresponding to a braking effort of the trailer brake that approximates the braking of the tractor-trailer combination to the braking of the tractor when considered alone, wherein the activator for the trailer brake is connected to operate in dependence on the target value.

17. An apparatus according to claim 16 including an open control loop to which the sensed values of the variables giving rise to deceleration of the tractor-trailer combination resulting from engine braking and/or pedal braking are input.

18. An apparatus according to claim 16 wherein the control device is programmable and includes programmed therein a function that maps the target braking effort of the trailer brake to a value of brake fluid pressure in the activator for the at least one trailer brake.

19. An apparatus according to claim 16 wherein the tractor brake and/or the trailer brake includes or is operatively connected to an antilock braking system (ABS).