Browse Prior Art Database

Control System for Liquid Cooling Equipment

IP.com Disclosure Number: IPCOM000074712D
Original Publication Date: 1971-Jun-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Lewkowicz, J: AUTHOR [+3]

Abstract

This bridge circuit 10 controls the three-way mix valve 12 via the control amplifier circuit 14 in response to the temperatures sensed by sensors S1 and S2. For very low system heat loads, the preference is that sensor S2 provides little, if any, input to the control amplifier 14 to actuate the valve motor 16, thus changing the valve 12 position and consequently changing the temperature at S1. When high heat loads are encountered in the system, it is desirable to change the valve 12 position such that S2 is providing cursory positioning and S1 the final valve position. Accordingly, S2 drives the motor a percentage of what S1 would drive at the same delta T per sensor, or S2 is to have a percentage authority compared to S1. This percentage authority is provided by introducing a variable resistive load circuit 18.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 83% of the total text.

Page 1 of 2

Control System for Liquid Cooling Equipment

This bridge circuit 10 controls the three-way mix valve 12 via the control amplifier circuit 14 in response to the temperatures sensed by sensors S1 and S2. For very low system heat loads, the preference is that sensor S2 provides little, if any, input to the control amplifier 14 to actuate the valve motor 16, thus changing the valve 12 position and consequently changing the temperature at S1. When high heat loads are encountered in the system, it is desirable to change the valve 12 position such that S2 is providing cursory positioning and S1 the final valve position. Accordingly, S2 drives the motor a percentage of what S1 would drive at the same delta T per sensor, or S2 is to have a percentage authority compared to S1. This percentage authority is provided by introducing a variable resistive load circuit 18.

The automatic authority adjustment is applied thru the DC bridge 10 in which the output sensor S2 is modified by the control circuitry 18. The heat load is measured by comparing the voltage across S2 (Point A) with a reference voltage E ref. A current Icl is fed back to point B, which modifies the authority of S2. The feedback current Ic1 should be a given function of amplifier output voltage V2 independent of temperature. However, for a given V2, Ic1 is dependent upon VBE1 which varies with temperature. It is, therefore, necessary to use a voltage source at the base of TX1, which compensates for temperature var...