Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication
Reexamination Certificate
1999-02-26
2001-05-29
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
C701S069000, C701S072000, C701S079000, C280S405100, C280S407100, C303S123000
Reexamination Certificate
active
06240339
ABSTRACT:
BACKGROUND
The present invention relates to selectively relieving the load on a rear axle of a vehicle, such as the rearmost axle of a trailer having at least two rear axles.
In a truck-trailer combination, the wheel base of a trailer having a single rear axle may be defined to be the distance from the pivot or king pin, where the trailer is pivoted to a vehicle, to the rear load-bearing axle of the trailer. In the case of a trailer having at least two rear load-bearing axles, the wheel base may be defined to be the distance from the king pin to the centroid of such plurality of axles. It is common for trailers to have relatively large wheel bases. When a truck-trailer combination is turned, for example, at an intersection, the rear of the trailer tends to follow a path which is inside the path followed by the vehicle during the turn rather than following the precise path of the vehicle. This is known as “off-tracking”. The offset between the vehicle and trailer travel paths through a turn is greater for trailers with larger wheel bases in comparison to trailers with relatively smaller wheel bases. Also, off-tracking tends to be greater when a vehicle-trailer combination is making sharp turns in comparison to wider turns. Thus, in tight turns, such as at city intersections, the “off-tracking” trailer may be offset enough to impact street curbs or other objects at intersection corners.
It would be desirable to compensate or minimize this offset during selected vehicle operating conditions. It would particularly be useful to reduce off-tracking without requiring the vehicle to stop.
SUMMARY
In accordance with one aspect of a specific embodiment, the rearmost load-bearing location at which a trailer is supported may be shifted forwardly to thereby shorten the effective wheel base of the trailer and reduce off-tracking. This may be accomplished under selected conditions, such as when the vehicle is moving and turning.
As another aspect of an embodiment, the trailer may have at least two rear wheel supporting axles, one of the two rear wheel supporting axles being a rearmost axle. The speed of the vehicle may be determined and a determination may be made as to whether the vehicle is turning. In addition, the load on the rearmost axle may be relieved to shorten the trailer wheel base when the speed of the vehicle is determined to be no greater than a first speed and the vehicle is determined to be turning at least at a first angle. The first speed, the first angle, or both, may be predetermined and may be variable. For example, they may comprise software programmable variable values.
In one specific example, the load on the rearmost axle may be relieved by elevating the rearmost axle to lift the wheel supported by the rearmost axle. For example, the rearmost axle may be lifted sufficiently for the wheels to clear the roadway or a lesser extent so the wheels drag lightly on the roadway, in which case the wheels will provide little, if any, support to the trailer. Alternatively, the rear axles may be supported by an air bag suspension system with pressure in the system being varied, such as relieved, to thereby relieve the load carried by the rearmost axle. In this latter case, the wheels typically would remain in contact with the roadway, although they provide little, if any, support to the trailer.
The above steps may be accomplished automatically whenever selected conditions are determined to exist, without driver intervention. Alternatively, semi-automatic operation may be implemented, for example, requiring a driver to intervene (such as by activating a switch) in order for the load on the rearmost axle to be relieved.
Thereafter, the load on the rearmost axle may be selectively increased. For example, the load on this axle may be increased when the speed of the vehicle is determined to be at least at a second speed which is greater than the first speed and the vehicle is determined to be turning at a second angle which is less than the first angle. In other words, after a vehicle has turned a corner and again increased its speed the rearmost axle may again be shifted to a load supporting mode of operation. This shifting is preferably automatic if the prescribed conditions are met, although a less preferred semi-automatic operation may be implemented. Also, as an alternative, once the conditions are met for relieving the load on the rearmost axle, the rearmost axle may be automatically reloaded after a period of time. Although this may be varied, thirty seconds would be a specific example. As another option, the vehicle operator may activate an over-ride to prevent reloading of the axle, for example, while the vehicle is still turning, even though this time period has elapsed.
As a specific example, the first speed may be predetermined and between ten and fifteen miles per hour (although it may be more or less), and the second speed may be predetermined and may be at least at, for example, twenty-five miles per hour (although it may be more or less). As another specific example, the first predetermined angle may be five degrees (although this may vary), and the second predetermined angle may be a straight line (although this may vary), that is, corresponding to the vehicle traveling forwardly without turning.
In addition, the step of increasing the load on the rearmost axle may be delayed until such time as the speed of the vehicle is determined to be at least at the second speed for a predetermined period of time, such as thirty seconds. This period of time may be varied, and may be a software programmable variable.
In a specific approach, an air bag suspension system may be vented to relieve the load on the rearmost axle. Venting may then be ceased or interrupted when it is again desired to increase the load on the rearmost axle.
In addition, a vehicle operator actuated over-ride may be monitored along with monitoring whether a parking brake for the vehicle is engaged. In this case, the load on the rearmost axle may be relieved, for example, automatically, when the speed of the vehicle is no greater than a first speed and the vehicle is turning at least at a first angle, unless the parking brake of the vehicle is engaged or the over-ride is activated or set. In addition, relieving of the load may be blocked, for example, regardless of vehicle conditions when the vehicle operator actuated over-ride is activated. In addition, the load may be relieved in response to a vehicle operated actuated action or instruction, for example, in the event the vehicle is traveling at a speed which is no greater than the first speed and regardless of whether the vehicle is determined to be turning. In this latter case, the system may decline to relieve the load in response to the operator actuated instruction if other conditions exist, for example, the parking brake is engaged.
The system may include a processor coupled to a speed sensor and to a turn detector so as to receive speed signals and turn signals corresponding to the speed and turning of the vehicle. The processor may be responsive to the speed signals and turn signals to selectively cause the delivery of a relieve axle load signal to a suspension controller in the event certain conditions are met. For example, a relieve axle load signal may be delivered to a suspension controller in the event the speed signals indicate the vehicle is (a) traveling at a speed which is no greater than a first speed; and (b) the vehicle is turning at an angle which is at least as sharp as a first angle. The processor may also be responsive to the speed signals and turn signals so as to cause the delivery of a reload axle signal in the event the speed signals indicate that the vehicle is traveling at a second speed which is not less than the first speed and the vehicle is turning at a second angle which is not sharper than the first angle. Again, reloading may occur automatically under other conditions, such as after a time delay from relieving of the load unless a vehicle operator indicates the axle is to remain unloaded.
In response to the relieve axle
Coverdill Cary
Estep Judith
Loutzenheiser Doug
Mayenburg Michael von
Nguyen Long V.
Arthur Gertrude
Cuchlinski Jr. William A.
Freightliner LLC
Klarquist Sparkman Campbell & Leigh & Whinston, LLP
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