HOT BOX DETECTOR OPERABLE WITH DIVERSE TYPE BEARING ASSEMBLIES

• US 3,697,744 A
• Filed: 04/29/1970
• Issued: 10/10/1972
• Est. Priority Date: 04/29/1970
• Status: Expired due to Term

• Current Assignee: Roland A. Howell
• Original Assignee: Roland A. Howell
• Inventors: Howell, Roland A.
• Primary Examiner(s): Forlenza, Gerald M.
• Assistant Examiner(s): Libman, George H.
• Application Number:
  US05/032,909
• Time in Patent Office: 895 Days
• Field of Search: 246/169D,249
• US Class Current: 246/169.00D
• CPC Class Codes: B61K 9/06 by detecting or indicating heat radiation from overheated axles

Abstract

An electronic hot box detector provides for giving alarm signals in response to overheated bearings of moving railroad cars. Special electronic control circuits avoid either errors of omission of a reading when a bearing heated above a predetermined temperature is presented or false alarms from other heated bodies in the train. Nevertheless, the detector senses overheated bearings of different types that present diverse temperature ranges. Thus precisely controlled electronic gates are used to sense thermal samples which are processed through amplifier circuits providing non-linear amplification characteristics to establish a readable range encompassing the desired thermal variations of both roller bearing and friction bearing assemblies.

Claims

1. In a trackside hot box detector system for detecting heated bearings on a moving train, a heat detector directed to sense by looking upward from the ground on the outside of a wheel only the journal portion of the bearings on passing axles which in the case of friction bearings is the housing box and which in the case of roller bearings is the bearing assembly and to provide therefrom electrical signals, amplifying means coupled to said heat detector to process the electrical signals therefrom to produce output signals representing temperatures in a range including both overheated friction bearings and overheated roller bearings comprising a non-linear amplifier having a steep initial gain characteristic for lower temperatures of overheated friction bearings and a shallow further gain characteristic for higher temperatures of overheated roller bearings, and alarm means coupled to said amplifier operable in response to detected temperatures in two separated bands respectively for indicating overheating of said friction and roller bearings.

2. A system as defined in claim 1 wherein the non-linear amplifier comprises an operational amplifier circuit having a degenerative feedback loop with a breakdown diode therein.

3. A system as defined in claim 2 provided with a threshold control and a slope control in said feedback loop.

4. A system as defined in claim 1 including a wheel detector and a gating circuit adjusted for processing signals received from said wheel detector over approximately 10 inches of wheel travel in the vicinity of said wheel detector.

5. A system as defined in claim 4 including a circuit wherein the signals processed from said amplifier are squared and integrated, said gating circuit comprises a threshold operated trigger circuit responsive to the integrated signals, and including timing means storing signals read out by said gating circuit for a period of approximately 22 milliseconds.

6. A system as defined in claim 1 including means sensing the direction of the train.

7. A system as defined in claim 6 including a circuit processing a pulse for each passing train wheel and a storage capacitor receiving said pulses having a time constant circuit providing a time constant longer than the predetermined time between two successive wheels.