Communications: electrical – Land vehicle alarms or indicators – Internal alarm or indicator responsive to a condition of the...
Patent
1987-11-03
1989-09-12
Orsino, Joseph A.
Communications: electrical
Land vehicle alarms or indicators
Internal alarm or indicator responsive to a condition of the...
B60C 2300
Patent
active
048664197
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates generally to a method for automatically determining the condition of a work vehicle suspension, and more particularly, to a method which detects an underinflated tire by monitoring strut pressures.
BACKGROUND ART
In the field of off-highway trucks used in mining operations, for example, it is desirable that an accurate record be kept of the quantity of material removed from the mining site. This information can be used to calculate mine and truck productivity as well as aid in forecasting profitability and work schedules.
Other systems, as disclosed in U.S. Pat. No. 4,635,739 issued to D. Foley et al. on Jan. 3, 1987, have shown that strut pressure can be an accurate indicator of payload. The apparatus disclosed therein includes an electronic control which monitors each of the strut pressures, compensates for various inaccuracies introduced by load distribution and vehicle attitude, and correlates this information into actual payload. This payload information allows the truck to be operated efficiently near its maximum capacity without promoting undue vehicle wear. An overloaded vehicle hastens tire and frame damage.
Operation of the vehicle with a collapsing strut will have detrimental effects on the accuracy of the payload monitor because of the change in the relationship between strut pressure and payload. Other serious consequences also result from such operation. For example, uneven tire wear is an undesirable result of extended vehicle operation with a collapsed strut. Tires are a major operating expense of off-highway trucks and any increase in their replacement schedule impacts on profitability. Thus a collapsed strut can have economic impact other than replacement of the damaged strut. Moreover, a completely collapsed strut results in repeated metal-to-metal contact which can cause frame damage in relatively short periods of operation. Resultant repair costs are exorbitant.
Operation of the vehicle with an underinflated tire, while not necessarily causing payload inaccuracies, results in tire damage because it wears at an accelerated rate. Additionally, tires on off-highway trucks tend to have very stiff sidewalls, so visual inspection rarely detects an underinflated condition.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In accordance with one aspect of the present invention, there is provided a method for detecting an underinflated tire of a work vehicle. The pneumatic tires are mounted on a plurality of opposed wheels which are mounted on hydraulic struts. The method includes the steps of sensing the internal pressure of preselected struts and delivering a plurality of first signals each having a value responsive to the internal pressure of a respective strut. A signal indicative of relative inflation pressures of at least a portion of the tires is derived in response to the first signals. The relative inflation pressure signal is compared with a preselected setpoint, and an underinflation signal is delivered in response a preselected difference between the compared signals.
In accordance with another aspect of the present invention, the step of deriving a signal indicative of relative inflation pressures of at least a portion of the tires includes the following steps. The first signals are converted to second signals, each responsive to the axial displacement of a respective strut. Preselected second signals are compared one with another. A signal indicative of relative inflation pressures of associated tires is delivered in response to the compared second signals.
In accordance with yet another aspect of the present invention, the step of driving a signal indicative of relative inflation pressures of at least a portion of the tires includes the following steps. The first signals are converted to second signals which are responsive to a kinetic energy transfer from the tires to an associated strut. Preselected second signals are compared with one another and a relative i
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patent: 3900828 (1975-08-01), Lage et al.
patent: 4459579 (1984-07-01), David et al.
patent: 4550385 (1985-10-01), Pulk et al.
patent: 4574267 (1986-03-01), Jones
patent: 4635739 (1987-01-01), Foley et al.
patent: 4744239 (1988-05-01), Kyrtsos et al.
Kyrtsos Christos T.
Long Gregory E.
Caterpillar Inc.
Morgan Terry D.
Muir Robert E.
Orsino Joseph A.
Tumm Brian R.
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