WHEEL BALANCING APPARATUS

• US 3,675,495 A
• Filed: 02/25/1970
• Issued: 07/11/1972
• Est. Priority Date: 02/25/1970
• Status: Expired due to Term

• Current Assignee: Bear Automotive Service Equipment Company (SPX Corporation)
• Original Assignee: Charles W. Macmillan
• Inventors: MacMillan, Charles W.
• Primary Examiner(s): Myracle, Jerry W.
• Application Number:
  US05/014,073
• Time in Patent Office: 867 Days
• Field of Search: 73/466,457,459,71.4 200/61.45
• US Class Current: 73/466
• CPC Class Codes: G01M 1/28 with special adaptations for determining imbalance of the body in situ, e.g. of vehicle wheels

Abstract

Method and apparatus for balancing vehicle wheels by stroboscopic light balancing means wherein the vehicle wheel is freely suspended and driven up to high speed, the vibrations of the rotating wheel are sensed, and the stroboscopic light is flashed on the wheel in timed relationship to the vibrations thereof to given an indication of the location of the imbalance causing the vibration; characterized by improved pick-up means consisting essentially of a housing adapted to be adhered to a part of the vehicle that is normally stationary but which vibrates responsively to the vibrations caused by wheel imbalance, and accelerometer means mounted in said housing having a plane of sensivity adapted to be disposed in the vertical direction for picking up static imbalance and in the horizontal direction for picking up dynamic imbalance; and further characterized by derivation of signals from said accelerometer means at a position remote from the rotating wheel, coupling each derived signal to a pulse counter for determining wheel speed, and determining wheel imbalance at a pre-selected speed.

Claims

1. In a stroboscopic balancer for balancing the wheels of vehicles when the wheels are elevated above the ground and spun at high speed, a pick-up unit to be connected with a normally stationary part of the vehicle, means in the pick-up unit for generating a pulse-type electric signal corresponding to the vibrations produced in said vehicle part by the spinning wheel if the wheel is unbalanced, and an electric circuit including a stroboscopic light and means connected with said pick-up unit for flashing said light onto the spinning wheel in synchronism with the electrical impulses produced by said pick-up unit in response to the vibrations created by the spinning unbalanced wheel, the improvement comprising a self-contained pick-up unit consisting essentially of a housing adapted to be adhered to a part of the vehicle that is normally stationary but which vibrates responsively to the vibrations caused by wheel imbalance, means for adhering said housing solely to the vehicle part so that housing is supported solely by the vehicle part and has no contact or engagement with the ground or other fixed reference, and accelerometer means mounted in said housing having a plane of sensitivity disposed in the vertical direction for picking up static imbalance and a plane of sensitivity disposed in the horizontal direction for picking up dynamic imbalance.

2. In a balancer as set forth in claim 1, said accelerometer means being of miniature size and said housing being in the order of 1 to 2 inches in diameter and 1 to 2 inches long.

3. In a balancer as set forth in claim 1, said housing comprising a tubular feRromagnetic shell enclosing said accelerometer means, said securing means comprising magnetic pole pieces at one end of said housing for detachably adhering said housing to a ferromagnetic part of the vehicle.

4. In a balancer as set forth in claim 3, said accelerometer means being mounted in said shell and encapsulated therein by an epoxy filling in said shell.

5. In a balancer as set forth in claim 1, said accelerometer means consisting of a first accelerometer mounted in said housing with its plane of sensitivity in the vertical direction, a second accelerometer mounted in said housing with its plane of sensitivity in the horizontal direction, a multiple conductor lead extending from said housing for supplying power to and deriving signals from said accelerometers, and switch means connected to said lead remotely of said housing for selectively deriving signals from each of said accelerometers.

6. In a balancer as set forth in claim 1, pulse counting means coupled to the output of said accelerometer means and speed determining means driven by said pulse counting means for determining the speed of rotation of a spinning unbalanced wheel.

7. In a balancer as set forth in claim 6 phase shifting means associated with said pulse counting means and coupled in the circuit of said stroboscopic light for compensating for the phase angle between wheel displacement and the locus of imbalance of the rotating wheel.

8. In a balancer as set forth in claim 7, means in the circuit of said pulse counting means and said stroboscopic light for accommodating flashing of said light only in a predetermined speed range.

9. In a balancer as set forth in claim 7, meter means coupled to the output of said accelerometer means for measuring the magnitude of the signal derived therefrom and for indicating approximately the amount of imbalance of the wheel.