28-01-2013, 11:22 AM
Audio Visual Warning Device (T-72)
[attachment=48547]
Introduction
Based on CQA (HV) information, many engine failures in T-72 are due to either low oil pressure or high coolant temperature (and coolant fan not working). Though the temperature gauge and oil gauge have been provided on the driver instrument panel board to monitor oil pressure and engine coolant temperature, it was felt that driver could not pay attention due to posture of the driver while driving.
Hence it was felt that such a device should be introduced which will draw the attention of driver and take remedial measure to save the engine.
An AVWD (Audio Visual Warning Device with Real Time Clock) consists of temperature sending unit for coolant temperature, pressure switch for engine oil pressure and control panel for audio-visual warning. Seven-segment display is used to display real time. Toggle switch is provided to set the device according to coolant used (water/anti-freeze). The audio warning (100 db) and visual indication will be operative when the coolant temperature reaches up to 115(-3)OC for water as a coolant or 105(-3)OC for antifreeze as a coolant and low engine oil Pressure below 4.5(+0.25)kg/cm2. If in case the audio warning is not required, then Stop Sound switch is provided on control panel to stop the sound for approx. 60 sec.
Block Diagram Description
Temperature sending unit:
The temperature sending unit is used in the system for sensing the temperature when engine is filled with normal coolant or antifreeze coolant. The temperature-sending unit is of PT-100 types with 2-pin male Military Grade connector, encapsulated in stainless steel body. The sending units are highly reliable, accurate, and durable. The resistance value of the temperature unit changes as per temperature variation. The resistance – temperature characteristic is linear throughout its operating range.
Pressure Switch:
The pressure switch used in the system is electro-mechanical type. For increase and decrease of pressure there is mechanical motion. The mechanical motion operates the electrical snap switch, which is inside the pressure switch assembly. The set point is pre-set at factory end at 4.5Kg/cm².The pressure switch is in brass body.
Fan Neutral Status:
The status of cooling fan (Engaged/Neutral) is sensed by tapping the electrical connection from existing fan neutral switch.
CONTROL UNIT:
24-Hour Digital Clock:
A 24-hour digital clock is provided on control panel of Audio Visual Warning Device. Bright red coloured 7-segment LED’s are used for clock display. User can set Hour/Minutes using keys provided on control panel. To set required hours press SET key and increment hours key similarly to set required minutes press SET key and increment minutes by MINUTES key.
As soon as the power (24V DC) is given to control panel digital clock will display the current time.
To set Hours, Keep Set key pressed and press Hours key to increment hours. Similarly keep Set key pressed and press Minutes key to increment minutes.
System Operation
When the Power (24V±10% DC) is given to the system the system operate after seven seconds delay.
Select the mode with water/antifreeze selection switch depending on the type of coolant used.
The warning will be operative when the coolant temperature reaches up to (115˚C - 3˚C) for water coolant and (105˚C - 3˚C) for antifreeze coolant. High coolant temperature indicator window starts blinking along with an audio buzzer.
When the engine oil Pressure falls to 4.5kg/cm² the Low Oil pressure window starts blinking along with Buzzer.
When the radiator Fan is at neutral position window starts blinking along with Buzzer.
If in case the audio alarm is not required, the stop sound facility is provided on the control panel with a timer function, which mutes buzzer for 60-sec.
[attachment=48547]
Introduction
Based on CQA (HV) information, many engine failures in T-72 are due to either low oil pressure or high coolant temperature (and coolant fan not working). Though the temperature gauge and oil gauge have been provided on the driver instrument panel board to monitor oil pressure and engine coolant temperature, it was felt that driver could not pay attention due to posture of the driver while driving.
Hence it was felt that such a device should be introduced which will draw the attention of driver and take remedial measure to save the engine.
An AVWD (Audio Visual Warning Device with Real Time Clock) consists of temperature sending unit for coolant temperature, pressure switch for engine oil pressure and control panel for audio-visual warning. Seven-segment display is used to display real time. Toggle switch is provided to set the device according to coolant used (water/anti-freeze). The audio warning (100 db) and visual indication will be operative when the coolant temperature reaches up to 115(-3)OC for water as a coolant or 105(-3)OC for antifreeze as a coolant and low engine oil Pressure below 4.5(+0.25)kg/cm2. If in case the audio warning is not required, then Stop Sound switch is provided on control panel to stop the sound for approx. 60 sec.
Block Diagram Description
Temperature sending unit:
The temperature sending unit is used in the system for sensing the temperature when engine is filled with normal coolant or antifreeze coolant. The temperature-sending unit is of PT-100 types with 2-pin male Military Grade connector, encapsulated in stainless steel body. The sending units are highly reliable, accurate, and durable. The resistance value of the temperature unit changes as per temperature variation. The resistance – temperature characteristic is linear throughout its operating range.
Pressure Switch:
The pressure switch used in the system is electro-mechanical type. For increase and decrease of pressure there is mechanical motion. The mechanical motion operates the electrical snap switch, which is inside the pressure switch assembly. The set point is pre-set at factory end at 4.5Kg/cm².The pressure switch is in brass body.
Fan Neutral Status:
The status of cooling fan (Engaged/Neutral) is sensed by tapping the electrical connection from existing fan neutral switch.
CONTROL UNIT:
24-Hour Digital Clock:
A 24-hour digital clock is provided on control panel of Audio Visual Warning Device. Bright red coloured 7-segment LED’s are used for clock display. User can set Hour/Minutes using keys provided on control panel. To set required hours press SET key and increment hours key similarly to set required minutes press SET key and increment minutes by MINUTES key.
As soon as the power (24V DC) is given to control panel digital clock will display the current time.
To set Hours, Keep Set key pressed and press Hours key to increment hours. Similarly keep Set key pressed and press Minutes key to increment minutes.
System Operation
When the Power (24V±10% DC) is given to the system the system operate after seven seconds delay.
Select the mode with water/antifreeze selection switch depending on the type of coolant used.
The warning will be operative when the coolant temperature reaches up to (115˚C - 3˚C) for water coolant and (105˚C - 3˚C) for antifreeze coolant. High coolant temperature indicator window starts blinking along with an audio buzzer.
When the engine oil Pressure falls to 4.5kg/cm² the Low Oil pressure window starts blinking along with Buzzer.
When the radiator Fan is at neutral position window starts blinking along with Buzzer.
If in case the audio alarm is not required, the stop sound facility is provided on the control panel with a timer function, which mutes buzzer for 60-sec.