Method of and apparatus for braking a tractor-trailer combination

• US 9,162,659 B2
• Filed: 11/10/2011
• Issued: 10/20/2015
• 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
• Primary Examiner(s): Nguyen, Cuong H
• Application Number:
  US14/126,025
• Publication Number:
  US 20140200786A1
• Time in Patent Office: 1,440 Days
• Field of Search: 701/74, 701 70- 71, 703/79, 703/36, 303/20, 303123-124
• US Class Current: 1/1
• CPC Class Codes: B60T 2230/06 Tractor-trailer swaying
• CPC Class Codes: B60T 8/1708 for lorries or tractor-trailer combinations
• CPC Class Codes: B60T 8/1887 especially adapted for tractor-trailer combinations
• CPC Class Codes: B60T 8/245 Longitudinal vehicle inclination
• CPC Class Codes: B60T 8/248 Trailer sway, e.g. for preventing jackknifing
• CPC Class Codes: B60T 8/72 responsive to a difference between a speed condition, e.g. deceleration, and a fixed reference

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 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 A<sub>X—

REF</sub> 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;

measuring a value A<sub>X—

MEASURED</sub> of the deceleration of the tractor-trailer combination; and

comparing in a closed-loop control arrangement the reference and measured deceleration values and establishing therefrom a target value of 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 reference deceleration value is calculated in accordance with the expression

2. A method according to claim 1, wherein the target value of deceleration 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 line.

3. A method according to claim 1, wherein the target value of deceleration 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.

4. A method according to claim 1, wherein the step of measuring a value of deceleration of the tractor-trailer combination includes 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 the trailer of the combination;

and/or a sensor for sensing a change in the ratio of the transmission and/or an inclinometer for measuring the inclination of the tractor-trailer combination.

5. 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.

6. A method according to claim 1, further comprising 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.

7. A method according to claim 1, wherein calculation of the reference deceleration value A_X—

_REF is in a form A<sub>X—

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

8. A method according to claim 1, wherein the target value is generated as a brake fluid pressure value and 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 trailer brake in dependence on the target value, wherein the target value of the braking effort of the trailer brakes is calculated in dependence on an average value of fluid pressure in a circuit including at least one trailer brake.

9. A method according to claim 2, wherein the average value of fluid pressure is an average of a time-varying pressure value or a time-invariant pressure value.

10. A method according to claim 1, wherein when the target value of deceleration 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.

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

12. 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 deceleration of the tractor-trailer combination resulting from braking effort applied via the tractor brake as a result of engine braking and/or as a result of pedal braking; and

f) at least one preferably programmable control device for establishing in a closed-loop control system from the output(s) of the said sensor device(s) a target value of 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 said target value.

13. An apparatus according to claim 12, further including a closed control loop to which the sensed values of variables giving rise to deceleration of the tractor-trailer combination resulting from engine braking and/or pedal braking are input.

14. An apparatus according to claim 12, wherein the tractor brake and/or the trailer brake includes or is operatively connected to an antilock braking system (ABS).