Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
1999-12-20
2001-04-10
Estremsky, Sherry (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
C192S003550, C074S336001
Reexamination Certificate
active
06212966
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a control system for a power shuttle transmission.
BACKGROUND TO THE INVENTION
Tractors are often used in applications, for example loading work or cultivation work, where frequent changes between forward and reverse gears are required. To avoid repeated de-clutching the power shuttle gearbox was developed.
The power shuttle gearbox allows the driver of a vehicle, for example an agricultural tractor, to change the direction of travel from forward to reverse or vice versa simply by pressing a button or pulling a lever. It is not necessary for the driver to use the clutch pedal at all to initiate a change of direction gear change. Some power shuttle gearboxes also allow gearshifts from neutral to a forward gear, or neutral to a reverse gear to be executed.
One type of power shuttle gearbox requires the hydraulic actuation of the clutch. The performance of such a power shuttle gearbox is influenced by the time taken for the hydraulic actuator to move the clutch pack from its biting point to it fully engaged positions. This is known as clutch take up. Changing the duration of this period changes the aggressiveness of clutch take up, and therefore the aggressiveness with which drive is taken up.
Tractors generally have a plurality of gears and gear ranges. For example, a transmission may comprise a four-speed gearbox coupled to a three-speed range change, thereby giving twelve gear ratios. The provision of a power shuttle gives the transmission twelve forward and twelve reverse gear ratios.
It is known to program the power shuttle so that for each gear ratio the time taken for the clutch take up differs. Whilst this may provide a smooth transition during shuttling, a smooth transition is not always required.
One problem associated with the above-mentioned type of power shuttle is that a tractor may be required to do two different jobs using the same gear ratio, but the jobs may have different requirements for aggressiveness of clutch take up.
Another problem associated with the above-mentioned type of power shuttle is that different drivers have different personal requirements from a tractor. Whilst one driver may not mind aggressive clutch take up, another my find this uncomfortable.
It would therefore be desirable to provide a control system for a power shuttle gearbox which does not suffer from the problems associated with the above-mentioned prior art.
SUMMARY OF THE INVENTION
The invention provides a control system for a power shuttle transmission, the transmission comprising a first clutch pack engagement of which drives a transmission output in a first direction, and a second clutch pack engagement of which drives the transmission output in a second direction, and means to engage and disengage the first and/or second clutch pack, wherein the control system comprises control means to initiate and complete engagement and/or disengagement cycles of the first and/or second clutch pack, and wherein the control system comprises adjustment means for actuation by an operator of the transmission to adjust the said engagement/disengagement cycle.
Preferably, the control means comprises a gear sensor means to sense an engaged gear ratio in the transmission. The transmission may comprise a plurality of gear sets each comprising a plurality of engageable gear ratios. The gear sensor means may be arranged to sense the engaged gear ratio in one of the said gear sets. Alternatively, the gear sensor means may be arranged to sense the engaged gear ratio in more than one of the plurality of gear sets.
Preferably, the control means is programmed with a plurality of different program cycles for initiating and completing engagement/disengagement cycles of the clutch packs.
Advantageously, the control means comprises a shuttle position sensor which senses the state of engagement of the clutch packs, i.e. first clutch pack engaged, second clutch pack disengaged; first clutch pack disengaged, second clutch pack engaged; neutral, with both clutch packs disengaged.
Preferably, the adjustment means allows the period of any one engagement/disengagement cycle to be adjusted between a minimum of 0.01 seconds and a maximum of 20 seconds, and more preferably between a minimum of 1 second and a maximum of 6 seconds.
The adjustment means may comprise a rotatable member, such as a potentiometer, and may further comprise means to rotate the said member, such as a knob, or a lever. Advantageously, rotation of the adjustment means increases or decreases the time period of the engagement and/or disengagement cycle of the first and/or second clutch packs, thereby increasing or decreasing the aggressiveness of clutch take up. More advantageously, rotation of the adjustment means in one direction decreases the time period of the engagement and/or disengagement cycle of the first and/or second clutch packs, thereby increasing the aggressiveness of clutch take up, and rotation in the other direction increases the time period of the engagement and/or disengagement cycle of the first and/or second clutch packs, thereby decreasing the aggressiveness of clutch take. Alternatively, the adjustment means may comprise a plurality of buttons, or keypads, wherein depressing one of the buttons or keypads decreases the time period of the engagement and/or disengagement cycle of the first and/or second clutch packs, and depressing another of the buttons or keypads increases the time period of the engagement and/or disengagement cycle of the first and/or second clutch packs.
Preferably, the control means comprises an electrical or electronic controller.
The means to engage and disengage the first and/or second clutch pack may comprise a source of pressurised fluid, and a valve block including a plurality of valves controlled by the control means, wherein upon receiving a signal from the control means a valve is opened or closed in accordance with an engagement/disengagement program cycle to supply or with hold pressurised fluid from one of the said clutch packs to engage or disengage the said clutch pack.
Preferably, the pressurised fluid is hydraulic fluid.
The clutch packs of the power shuttle may be of the pressure on type, where fluid pressure is applied to engage the clutch packs, and spring force is used to bring the clutch packs to their disengaged position when the fluid pressure is removed. Alternatively, the clutch packs may be of the pressure off type, where the clutch packs are engaged by spring force, and fluid pressure is applied to disengage the clutch packs.
REFERENCES:
patent: 5012416 (1991-04-01), Bulgrien et al.
patent: 5053960 (1991-10-01), Brekkestran et al.
patent: 5459658 (1995-10-01), Morey et al.
patent: 5608917 (1997-03-01), Landis et al.
patent: 5609068 (1997-03-01), Gruhle et al.
patent: 5845224 (1998-12-01), McKee
patent: 5996435 (1999-12-01), Riedhammer
patent: 2315826 (1998-02-01), None
Barton John Robert
Owen Sion Morgan
AGCO Limited
Estremsky Sherry
Lewis Tisha D.
MacMillan Sobanski & Todd LLC
LandOfFree
Control system for a power shuttle gearbox does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control system for a power shuttle gearbox, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control system for a power shuttle gearbox will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2493385