APPARATUS FOR PRECISELY INDICATING POSITION OF ROTATIONAL MACHINERY

• US 3,813,931 A
• Filed: 03/15/1973
• Issued: 06/04/1974
• Est. Priority Date: 03/15/1973
• Status: Expired due to Term

• Current Assignee: Northrop Corporation (Northrop Grumman Corporation)
• Original Assignee: Lyle V. Rennick, William L. Mitchael
• Inventors: Rennick, Lyle V., Mitchael, William L.
• Primary Examiner(s): Myracle, Jerry W.
• Application Number:
  US05/341,703
• Time in Patent Office: 446 Days
• Field of Search: 73/116,117.3 324/16T 356/23 315/149 307/266
• US Class Current: 73/114.28
• CPC Class Codes: G01M 15/06 by monitoring positions of pistons or cranks

Abstract

A rotating portion such as a drive shaft of a machine has a marker placed thereon to indicate a predetermined portion of the rotation cycle. A signal from this marker is sensed by a sensor each time the machinery passes through this portion of the rotation cycle. A ramp generator develops a ramp signal in response to the output of the sensor. The peak of the ramp signal is detected and this peak signal fed to a calibration potentiometer by means of which a percentage of the peak signal can be selected. The output of the potentiometer and that of the ramp generator are fed to a voltage comparator which triggers a pulse generator when the ramp reaches the voltage set on the potentiometer. The output of the pulse generator actuates a strobe light which is used to detect a marker on the machinery indicative of a precise rotational position, the potentiometer being adjusted until the strobe light is precisely synchronized with this marker. Thus a calibration is achieved whereby the output pulse precisely indicates a predetermined rotational position of the machinery. This output pulse can then be used with other measurement circuitry, without further requirement of the strobe light.

Claims

1. In combination, an internal combustion engine having rotating parts and a device for generating a synchronization pulse precisely indicating a predetermined position in the rotation cycle of the rotating parts of said internal combustion engine, said device comprising:

a marker on one of said rotating parts, sensor means responsive to said marker for generating a pulse signal when the rotating parts are in the vicinity of said predetermined position, means responsive to the output of the sensor means for generating a synchronization pulse which occupies a fraction of the time cycle of the pulse output signal of said sensor means, said last mentioned means comprising a ramp generator for generating a ramp signal in response to the output of said sensor means, means for selecting a DC signal which is a percentage of the peak of the ramp signal, and a voltage comparator receiving said ramp signal and the selected DC signal for providing said synchronization pulse at a point on the ramp signal equal to the selected DC signal, visual marker means on said engine indicative of said predetermined position, a strobe lamp for strobing said marker means, the synchronization pulses being used to ignite the strobe lamp, and means for adjusting the timing of said synchronization pulse within the range of the pulse signal output of said sensor means to synchronization with the strobing of the visual marker means, said adjusting means comprising a peak detector and hold circuit for detecting the peak of the ramp signal and holding a voltage corresponding to said peak signal and a potentiometer for selecting a percentage of said peak signal to provide the selected DC signal, the selected DC signal being fed from the potentiometer to the comparator for comparison with the ramp signal.

2. In combination, a machine having a rotor member and a device for generating a pulse precisely indicative of a predetermined position in the rotation cycle of the rotor member of said machine, said device comprising:

marker means on said rotor member, sensor means responsive to said marker means for generating a pulse signal when the rotor member of said machine is in the vicinity of said predetermined position, means for generating a ramp signal in response to said pulse signal, peak detector and hold circuit for detecting the peak of said ramp signal and holding a voltage corresponding to said peak, calibration means for selectively providing a signal which is a percentage of the voltage corresponding to said peak, voltage comparator means for comparing the selected percentage signal with said ramp signal and generating an output when the ramp signal reaches the same value as said percentage signal, means for generating a pulse in response to the output of said voltage comparator means, a strobe lamp, there being visual marker means on said machine indicative of said predetermined position, the output of said pulse generator being fed to said strobe lamp to ignite said lamp in response thereto, whereby said visual marker means on said machine can be stroboscopically made to indicate said predetermined position by adjusting said calibration means, thereby calibrating the output of the pulse generator with the visual marker means on said machine.

3. The device of claim 2 wherein said marker means comprises a reflective tape and said sEnsor means comprises a photo sensor.

4. The device of claim 2 wherein said calibration means comprises a potentiometer, the arm of said potentiometer being adjusted to provide said percentage signal.

5. The device of claim 2 wherein said machine is an internal combustion engine, said predetermined position comprising the top dead center position of the engine.