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US 2003/0192744 A1Published application
Method and apparatus for synchronizing a vehicle lift
AssigneeDelaware Capital Formation, Inc.
InventorsSteven D. Green, David P. Porter
Life of this patent
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AssigneeDelaware Capital Formation, Inc.
InventorsSteven D. Green, David P. Porter
Estimating the term…
A vehicle lift control maintains multiple points of a lift system within the same horizontal plane during vertical movement of the lift engagement structure by synchronizing the movement thereof. A vertical trajectory is compared to actual positions to generate a raise signal. A position synchronization circuit synchronizes the vertical actuation of the moveable lift components by determining a proportional-integral error signal.
A controller for a vehicle lift, said vehicle lift having a first pair formed of a first vertically moveable superstructure and a second vertically moveable superstructure, each of said first and second vertically moveable superstructures having respective vertical positions which vary when said first and second vertically moveable superstructures are respectively moved, said controller comprising:
A control system for a vehicle lift, said vehicle lift having a first pair formed of a first vertically moveable superstructure and a second vertically moveable superstructure, said control system comprising:
The controller of claim 26, further comprising a raise circuit responsive to said first and second position signals and to said vertical trajectory signal and operably configured to generate a first raise signal for said first vertically moveable superstructure and to generate a second raise signal for said second vertically moveable superstructure.
A hydraulic fluid control system for a vehicle lift comprising:
A hydraulic fluid control system for a vehicle lift comprising:
A controller for a vehicle lift, said vehicle lift having a first vertically moveable superstructure and a second vertically moveable superstructure, each of said first and second vertically moveable superstructures having respective vertical positions which vary when said first and second vertically moveable superstructures are respectively moved, said controller comprising:
A vehicle lift having a first pair formed of a first vertically moveable superstructure and a second vertically moveable superstructure, each of said first and second vertically moveable superstructures having respective vertical positions which vary when said first and second vertically moveable superstructures are respectively moved, said vehicle lift comprising:
A controller for a vehicle lift, said vehicle lift having a first pair formed of a first vertically moveable superstructure and a second vertically moveable superstructure, each of said first and second vertically moveable superstructures having respective vertical positions which vary when said first and second vertically moveable superstructures are respectively moved, said controller comprising:
A vehicle lift comprising:
A vehicle lift comprising:
A controller for a vehicle lift, said vehicle lift having a first pair formed of a first vertically moveable superstructure and a second vertically moveable superstructure, each of said first and second vertically moveable superstructures having respective vertical positions which vary when said first and second vertically moveable superstructures are respectively moved, said controller comprising:
Dependencies are inferred from the claim text.
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With two or more servomotors: synchronisation of the movement of two or more servomotors
By one or more hydraulic or pneumatic jacks: by several jacks with means for maintaining the platforms horizontal during movement
Systems essentially having two or more interacting servomotors , e.g. multi-stage: with electrical control means
Position sensing, i.e. means for continuous measurement of position, e.g. LVDT: using a cable wrapped on a drum and attached to the piston
Term end not estimated
This invention relates generally to vehicle lifts and their controls, and more particularly to a vehicle lift control adapted for maintaining multiple points of a lift system within the same horizontal plane during vertical movement of the lift superstructure by synchronizing the movement thereof. The invention is disclosed in conjunction with a hydraulic fluid control system, although equally applicable to an electrically actuated system.
There are a variety of vehicle lift types which have more than one independent vertically movable superstructure. Examples of such lifts are those commonly referred to as two post and four post lifts. Other examples of such lifts include parallelogram lifts, scissors lifts and portable lifts. The movement of the superstructure may be linear or non-linear, and may have a horizontal motion component in addition to the vertical movement component. As defined by the Automotive Lift Institute ALI ALCTV-1998 standards, the types of vehicle lift superstructures include frame engaging type, axle engaging type, roll on/drive on type and fork type. As used herein, superstructure includes all vehicle lifting interfaces between the lifting apparatus and the vehicle, of any configuration now known or later developed.
Such lifts include respective actuators for each independently moveable superstructure to effect the vertical movement. Although typically the actuators are hydraulic, electromechanical actuators, such as a screw type, are also used.
The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention. In the drawings:
FIG. 1 is a schematic diagram of an embodiment of a control in accordance with the present invention, embodied as a hydraulic fluid control system including the controller and hydraulic circuit.
FIG. 2 is a control diagram showing the complete raise control including the raise circuit and the position synchronization circuit for a pair of superstructures.
Reference will now be made in detail to the present preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings.
Referring now to the drawings in detail, wherein like numerals indicate the same elements throughout the views, FIG. 1 illustrates a vehicle lift, generally indicated at 2. Lift 2 is illustrated as a two post lift, including a pair of independently moveable actuators 4 and 6 which cause the respective superstructures (not shown) to move. In the depicted embodiment, first and second actuators 4 and 6 are illustrated as respective hydraulic cylinders, although they may be any actuator suitable for the control system. First and second actuators 4 and 6 are in fluid communication with a source of hydraulic fluid 8. Pressurized hydraulic fluid is provided by pump 10 at discharge 10a. Each actuator 4 and 6 has a respective proportional flow control valve 12 and 14 interposed between its actuator and source of hydraulic fluid 8.
The hydraulic fluid flow is divided at 16, with a portion of the flow going to (from, when lowered) each respective actuator 4 and 6 as controlled by first and second proportional flow control valves 12 and 14. As illustrated, isolation check valve 18 is located in the hydraulic line of either actuator 4 or 6 (shown in FIG. 1 in hydraulic line 20 of actuator 6), between 16 and second flow control valve 14 to prevent potential leakage from either actuator 4 or 6 through the respective flow control valve 12 and 14 from affecting the position of the other actuator.