PNEUMATIC WHEEL LIFT SYNCHRONIZATION

• US 20150232309A1
• Filed: 02/13/2015
• Published: 08/20/2015
• Est. Priority Date: 02/20/2014
• Status: Active Grant

• Current Assignee: Gray Manufacturing Company Incorporated
• Original Assignee: Gray Manufacturing Company Incorporated
• Inventors: Jaipaul, Larry M., Helmich, Seth A.
• Granted Patent: US 9,950,916 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B66F 3/46 Combinations of several jacks with means for interrelating lifting or lowering movements
• CPC Class Codes: B66F 7/04 hydraulically or pneumatically operated

Abstract

A self-synchronizing wheel lift system configured to lift a vehicle using compressed air. The lift system comprises a plurality of pneumatic wheel lifts and a lift control system. The lift control system is configured to automatically synchronize the heights of the wheel lifts during vehicle lifting without causing any of the wheel lifts to completely stop during vehicle lifting.

Claims

1. A self-synchronizing wheel lift system configured to lift a vehicle using compressed air, said lift system comprising:

a plurality of pneumatic wheel lifts; and

a lift control system configured to automatically synchronize the heights of said wheel lifts during vehicle lifting without causing any of said wheel lifts to completely stop during vehicle lifting.

2. The wheel lift system of claim 1, wherein the lift control system is configured to automatically synchronize the heights of said wheel lifts during vehicle lowering without causing any of said wheel lifts to completely stop during vehicle lowering.

3. The wheel lift system of claim 1, wherein the lift control system comprises a position indication system, a pneumatic control system, and an electrical control system, wherein said position indication system is configured to provide an indication of the heights of said wheel lifts during vehicle lifting, wherein said pneumatic power control system is configured to control the flow of compressed air to said wheel lifts during lifting, and wherein said electrical control system is configured to control said pneumatic control system based on said indication of heights provided by said position indication system.

4. The wheel lift system of claim 3, wherein each of said wheel lifts comprises a pneumatic main cylinder, wherein said pneumatic control system comprises a plurality of pneumatic valves each associated with one of said main cylinders, wherein each of said pneumatic valves is configured to control air flow into and/or out of one of said main cylinders.

5. The wheel lift system of claim 4, wherein said electrical control system is configured to generate a valve control signal for each of said pneumatic valves, wherein each of said valve control signals controls the position of one of said pneumatic valves, and wherein said electrical control system is configured to adjust said valve control signals based on said indication of heights provided by said position indication system.

6. The wheel lift system of claim 5, wherein each of said valve control signals is a pulse-width modulated signal comprising a series of duty cycles, wherein each duty cycle comprises one on signal and one off signal, wherein said valve control signal shifts said pneumatic valve into said on position during said on signal and into said off position during said off signal.

7. The wheel lift system of claim 6, wherein said electrical control system is configured to control the speed of each of said wheel lifts by changing the relative duration of said on and off signals of said duty cycles.

8. The wheel lift system of claim 6, wherein said electrical control system is configured to limit the duration of said off signals of said duty cycles to prevent any of said wheel lifts from completely stopping while said vehicle is being lifted.

9. The wheel lift system of claim 1, wherein said electrical control system is a wireless control module configured to communicate wirelessly with each of the wheel lifts in the wheel lift system.

10. The wheel lift system of claim 9, wherein said position indication system includes a plurality of position sensors, with each wheel lift in said wheel lift system including at least one position sensor, and wherein said position indication system is configured to communicate wirelessly with said wireless control module.

11. The wheel lift system of claim 10, wherein said position sensors comprise string potentiometers.

12. The wheel lift system of claim 1, wherein said wheel lift system comprises at least four wheel lifts.

13. A vehicle lifting method comprising:

(a) lifting at least one end of a vehicle using a plurality of pneumatically powered wheel lifts, each comprising a pneumatic cylinder; and

(b) during said lifting of step (a), synchronizing the heights of said wheel lifts using a lift control system, wherein said lift control system is configured to automatically synchronize the heights of said wheel lifts during said lifting without causing any of said wheel lifts to completely stop its lifting.

14. The method of claim 13, wherein said synchronizing of step (b) includes (i) identifying a lowest one of said plurality of wheel lifts and (ii) reducing compressed air flow to at least one of the other wheel lifts.

15. The method of claim 14, wherein said reducing of step (ii) is carried out by adjusting a duty cycle of a valve control signal that controls the supply of compressed air to a pneumatic main cylinder of said at least one of the other wheel lifts, wherein said duty cycle includes one off signal which instructs a pneumatic valve to not provide compressed air into said main cylinder and one on signal which instructs the pneumatic valve to provide compressed air into said main cylinder.

16. The method of claim 15, wherein said reducing of step (ii) includes adjusting said duty cycle by reducing the duration of said on signal relative to said off signal.

17. A non-transitory computer readable storage medium with an executable program stored thereon for adjusting control signals in a pneumatic lift system, wherein the program instructs a processor to perform the steps of:

(a) receive vertical position information for two or more pneumatic lifts in the lift system;

(b) compare the vertical position information of said two or more pneumatic lifts to determine a first lift that has a highest vertical position and a second lift that has a lower vertical position than the first lift;

(c) determine a duty cycle of a control signal for controlling air flow relative to the second lift, said duty cycle having an on portion and an off portion; and

(d) adjust the duty cycle of the control signal for the second lift by reducing the on portion and increasing the off portion, such that the rate at which the second lift is being lowered is reduced,

wherein the rate at which the second lift is being lowered during the adjust step (d) is always greater than zero.

18. The computer readable storage medium of claim 17, wherein the processor further performs the step of sending the control signal with the adjusted duty cycle to a pneumatic control system associated with the second lift.

19. The computer readable storage medium of claim 18, wherein pneumatic control system includes a pneumatic valve associated with the second lift.

20. The computer readable storage medium of claim 19, wherein when the pneumatic control system receives the control signal, the pneumatic control system opens the pneumatic valve during the on portion of the duty signal and closes the pneumatic valve during the off portion of the duty signal.