Two-level multiplex alarm monitor for hot box detector system

• US 3,872,456 A
• Filed: 03/06/1974
• Issued: 03/18/1975
• Est. Priority Date: 03/06/1974
• Status: Expired due to Term

• Current Assignee: Arthur J. Glazar
• Original Assignee: Arthur J. Glazar
• Inventors: Glazar, Arthur J.
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US05/448,668
• Time in Patent Office: 377 Days
• Field of Search: 340/231,269,47 246/169A,169D 308/1A
• US Class Current: 246/169.00A
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 3/00 Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption methods or circuit arrangements for monitoring or controlling batteries or fuel cells B60L58/00
• CPC Class Codes: B61K 9/06 by detecting or indicating heat radiation from overheated axles
• CPC Class Codes: H03K 5/24 the characteristic being amplitude

Abstract

A two-level alarm monitor for use with a hot box detector system of the type having first and second sensors each associated with a rail of a track is provided. The monitor includes means connected to the outputs of the sensors for obtaining the difference between the output signals of the sensors and for comparing the difference alternately to first and second predetermined levels which may, for example, represent '"'"''"'"''"'"''"'"'warm'"'"''"'"''"'"''"'"' and '"'"''"'"''"'"''"'"'hot'"'"''"'"''"'"''"'"' differential alarm levels or differential alarm levels for friction and roller bearings. The outputs of the sensors are also alternately compared with third and fourth predetermined levels which could, for example, represent '"'"''"'"''"'"''"'"'warm'"'"''"'"''"'"''"'"' and '"'"''"'"''"'"''"'"'hot'"'"''"'"''"'"''"'"' absolute alarm levels or absolute alarm levels for friction or roller bearings. The output signals from the comparators are demultiplexed and utilized to generate an alarm signal in the event differential signals or absolute alarm signals exceed associated predetermined levels.

Claims

1. A two-level alarm monitor for use with a hot box detector system having a first sensor and a second sensor each associated with a rail of a track and each adapted to generate an output electrical signal responsive to the heat generated by a bearing passing on its associated rail, said alarm monitor comprising:

a. means connected to the outputs of said sensors for alternately obtaining the difference between (1) said first sensor signal and said second sensor signal and (2) said second sensor signal and said first sensor signal;

b. first comparator means interconnected to said aforementioned means for comparing the difference between said sensor signals alternately to (1) a first predetermined signal level and (2) a second predetermined signal level;

c. second comparator means connected to the outputs of said sensors for alternately comparing (1) the output of said first sensor and (2) the output of said second sensor to (3) a third predetermined level and (4) a fourth predetermined level; and

, d. demultiplexing means connected to said first and second comparators for generating an alarm signal in the event (1) the difference between said sensor signals exceeds one or both of said first or second predetermined levels and/or (2) one or both of said sensor output signals exceeds one or both of said third or fourth predetermined levels.

2. The invention in accordance with claim 1 wherein said difference obtaining means comprises:

a. a differential amplifier adapted to receive two input signals and to generate an output signal proportional to the difference between said input signals;

b. first switch means having a first state interconnecting the output signal of one of said sensors with one of said differential amplifier inputs and the output of the other of said sensors with the other of said amplifier inputs and a second state wherein said interconnections are reversed; and

, c. means for driving said first switch means alternately between said first and second states.

3. The invention in accordance with claim 2 wherein said first comparator means includes:

a. a first differential comparator adapted to receive two input signals and to generate an output signal, only if the signal applied to one input exceeds a reference voltage applied to the second input;

b. means interconnecting one of said first differential comparator inputs to the output of said differential amplifier;

c. second switch means having a first state interconnecting the other of said second differential comparator inputs to said first predetermined level and a second state interconnecting the other of said second differential comparator inputs to said second predetermined level; and

d. means for driving said second switch alternately between said first and second states.

4. The invention in accordance with claim 3 wherein said driving means for said second switch drives said second switch between its states at half the frequency of the driving means for said first switch.

5. The invention in accordance with claim 3 wherein said second comparator means comprises:

a. a second differential comparator adapted to receive two input signals and to generate an output signal only if the signal applied to one input exceeds a reference voltage applied to a second input;

b. third switch means having a first state interconnecting the output signal of one of said sensors to one of said second differential comparator inputs and a second state interconnecting the output signal of the other of said sensors to said one of the second differential comparator inputs;

c. means for driving said third switch means between its first and second states;

d. fourth switch means having a first state interconnecting the other of said second differential comparator inputs with said third predetermined level and a second state interconnecting the other of said second differential comparator inputs with said fourth predetermined level; and

, e. means for alternately driving said fourth switch means between its first and second states.

6. The invention in accordance with claim 5 wherein said third switch means alternates between its states at the same frequency as said first switch means and said fourth switch means alternates between its states at the same frequency as said second switch means.

7. The invention in accordance with claim 5 wherein said first predetermined level comprises a maximum allowable differential alarm level for a friction bearing;

said second predetermined level comprises a maximum allowable differential alarm level for a roller bearing;

said third predetermined level comprises a maximum allowable absolute alarm level for a friction bearing, said fourth predetermined level comprises a maximum allowable absolute alarm level for a roller bearing and said second and fourth switch driving means comprises the output of a roller bearing discriminator.