Equalizer

Motors: expansible chamber type – Plural relatively movable or rigidly interconnected working... – Condition responsive means for modifying working member...

Reexamination Certificate

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Details

C091S459000

Reexamination Certificate

active

06321634

ABSTRACT:

FIELD OF INVENTION
This invention relates generally to a method and apparatus for controlling the movement of a vehicle lift and particularly relates to the uniform movement of the support platform supporting the vehicle in a vehicle lift. More specifically this invention relates to the method and apparatus of utilizing circuitry including an equalizing valve to monitor and control the lifting characteristics of a vehicle lift.
BACKGROUND ART
Hydraulic vehicle lifts are available in a variety of forms including two post, four posts, inground, parallelogram, scissor and portable type.
Generally speaking such vehicle lifts move from a first ground contacting position to a second raised position whereby a vehicle driven unto the lift may be raised from the ground to a raised position permitting wheel alignment, oil change, and other work to be conducted on the vehicle.
Such vehicle lifts generally include a pair of spaced-apart support platforms or rails for supporting the wheels or frame of a vehicle. These support platforms are adapted to be moved by hydraulic cylinders which raise and lower the support platforms as stated. Some vehicle lifts include one cylinder while others may include two cylinders where one of said cylinders is adapted to move one of the support platforms and the other cylinder is adapted to move the other support platform.
Accordingly when using a pair of hydraulic cylinders to move one pair of spaced-apart platforms, it is necessary that the cylinders with the support platforms move in a uniform fashion. If one of the support platforms does not move in unison with the other, a dangerous situation can occur whereby one of the support platforms or tracks is either higher or lower than the other which can cause the vehicle to fall off the lift from a raised position and produce damage to the car and potential hazard to any individuals in the vicinity.
Accordingly various attempts have heretofore been made in the prior art in order to equalize the ascent and descent of the first and second cylinder which moves a first and second vehicle support. Such prior art devices include manually operated circuitry which must be manually operated in order to attempt to adjust the hydraulic cylinders and therefore the height levels of the vehicle supports. However, manual adjustment is prone to error and if the wrong buttons are pushed may actually worsen the situation.
Other prior art devices are shown for example in U.S. Pat. No. 5,833,260 which includes a gyro leveling sensor mounted between and below the level of the support tracks with data transmitted to an assembly of display lights which indicate a high portion of the unit. The unit may then be leveled by initiating hydraulic pressure or release of pressure on one of the link support hydraulic cylinders disclosed therewith.
Another equalizing system is shown in U.S. Pat. No. 5,783,755 which illustrates a lifting device that has a carriage supported by a chain which passes over a sprocket-wheel disposed to rotate about an axis and includes an equalizer system that reduces variations in the measurement, by a load cell, of a load supported by the carriage.
Another arrangement is shown in U.S. Pat. No. 5,800,000 which provides a load adjusting device for use with a lifting unit where the device includes a load spreader or spreader bar supported from a single lift point lift.
Such prior art devices as well as others utilized in vehicle lifts are relatively complicated.
It is an object of this invention to provide an improved method and apparatus for monitoring and controlling the uniform movement of the support platforms in a vehicle lift.
DISCLOSURE OF INVENTION
It is an aspect of this invention to provide an apparatus for equalizing pressure between two conduits including means for sensing pressure in said conduits; valve means communicating between said conduits, said valve means adapted to open so as to equalize pressure between said conduits.
It is a further aspect of this invention to provide electrical circuitry for controlling the pressure of fluid in two conduits comprising sensors means associated with said conduits so as to generate a signal in response to the pressure of a fluid in said conduits; relay means associated with said conduit means so as to control fluid passage through said conduits; adjustable relay means associated with said relay means so as to permit equalization of pressure of said fluid in said conduits.
Yet another aspect of this invention provides a method of equalizing pressure of fluid between a first and second conduit comprising sensing the pressure of fluid in each of said conduits; activating an equalizing valve when one of said sensors senses that the pressure of the fluid has dropped below a preselected level.
It is yet another aspect of this invention to provide a method of controlling the uniform movement of two support platforms of a vehicle lift comprising activating a first and second hydraulic cylinder so as to move first and second support platforms; sensing the pressure of fluid to said first and second cylinders; activating electrical circuitry when said sensing means senses the pressure fluid at a preselected level; stopping said movement of said cylinders when said preselected level has been sensed by said sensors; raising said first and second platforms for a preselected time duration; lowering said first and second platforms so as to activate an equalizing valve to equalize the pressure in said first and second conduits; wherein said flow of fluid in said conduits controlled by said first and second valve means.


REFERENCES:
patent: 4023650 (1977-05-01), Pleier
patent: 4187763 (1980-02-01), Nanda
patent: 5012898 (1991-05-01), Tsymberov
patent: 5072584 (1991-12-01), Mauch et al.
patent: 5076380 (1991-12-01), Tanabe et al.
patent: 5783755 (1998-07-01), Bruns
patent: 5800000 (1998-09-01), Shockley
patent: 5824963 (1998-10-01), Bruns et al.
patent: 5833260 (1998-11-01), York
patent: 6189432 (2001-02-01), Colarelli et al.
patent: 1373911 A1 (1988-02-01), None

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