Process control apparatus for temperature control

• US 3,922,535 A
• Filed: 11/12/1970
• Issued: 11/25/1975
• Est. Priority Date: 11/12/1970
• Status: Expired due to Term

• Current Assignee: John H. Randolph
• Original Assignee: John H. Randolph
• Inventors: Randolph, John H.
• Primary Examiner(s): Ruggiero, Joseph F.
• Application Number:
  US05/088,588
• Time in Patent Office: 1,839 Days
• Field of Search: 235/151.1,150.5 236/46 165/64,169
• US Class Current: 700/40
• CPC Class Codes: G05B 19/075 for delivering a step function, a slope or a continuous function G05B19/06 takes precedence
• CPC Class Codes: G05D 23/1904 variable in time
• CPC Class Codes: G05D 23/20 with sensing elements having variation of electric or magnetic properties with change of temperature G05D23/13 takes precedence

Abstract

An apparatus for controlling the operation process of a physical system according to a predetermined operating cycle. The apparatus includes a digital register, a digital to analogue converter, and an integrator which produces a signal corresponding to the desired slope or change in said process. Another means is provided for generating a steady state signal indicating the end point of the change. A comparator is provided for comparing the integrated signal with the steady state signal for generating a compared signal for determining whether the steady state signal or the integrated signal will be coupled to the controller for controlling the operation thereof. The apparatus is also provided with a sign indicating means for generating a signal indicating the direction that the process is to be varied and means for causing the integrator to begin integrating at a value where it left off at the end of the previous cycle.

Claims

1. An apparatus for controlling the operation process of a system according to a predetermined operating cycle comprising a first means providing a slope signal representing a rate of change that said process is to be varied during Said operating cycle, an integrator coupled to said first means for generating an integrated signal having an amplitude proportional to the time integral of said slope signal, second means providing a steady state signal representing the end point of said operating cycle, a comparator, means for supplying said integrated signal to said comparator, means for supplying said steady state signal representing said end point to said comparator to be compared with said integrated signal, said comparator including means for generating a compared signal indicating whether said integrated signal is as large as said steady state signal, a switching circuit having an output, a controller coupled between said output of said switching circuit and said physical system, means for coupling said means to said switching circuit, means for coupling said integrator to said switching circuit, means for coupling said comparator to said switching circuit for causing said switching circuit to couple either said integrated signal or said steady state signal representing said end point to said controller, and said controller varying the operation of said physical system according to said signal supplied thereto.

2. An apparatus for controlling the operation of a device according to a predetermined program comprising:

means for generating an analogue rate of change signal indicating the desired rate at which the operation of said device is to be varied;

means for generating a steady state signal indicating a particular state at which said operation of said device is to be held constant;

a comparator having an input and an output;

means for coupling said rate of change signal and said steady state signal to said input of said comparator causing said comparator to generate a compared signal indicating whether said rate of change signal has reached a magnitude equal to said steady state signal;

a switching circuit coupled to said means for generating said analogue rate of change signal and said means for generating said steady state signal;

a controller coupled between said switching circuit and said device;

means for coupling said output of said comparator to said switching means for supplying said compared signal to said switching means for causing said switching means to couple either said steady state signal or said analogue rate of change signal to said controller;

whereby said analogue rate of change signal is supplied to said controller for varying the operation of said device and said steady state signal is supplied to said controller for holding the operation of said device constant.

3. An apparatus for controlling temperature variations of a medium during a process according to a predetermined program comprising:

a first digital register for storing information in the form of a rate of change signal indicative of the desired rate of change in temperture of said medium during said process;

a second digital register for storing information in the form of a steady state signal representing the end point of said rate of change of said temperature of said medium;

a first digital to analogue converter coupled to the output of said first digital register for converting said rate of change signal to an analogue signal representing rate of change, an integrating means coupled to the output of said first digital to analogue converter for integrating said analogue signal representing rate of change producing an integrated signal;

a second digital to analogue converter coupled to the output of said second digital register producing a second analogue signal representing the end point of said change of said temperature of said medium;

a comparator coupled to the output of said integrator and said second digital to analogue converter for generating a compared signal indicating whether said integrated signal or said steady state signal is larger;

a switching circuit coupled to said integrating means and said second digital to analogue converter;

a controller coupled between said switching circuit and said medium whose temperature is being controlled;

means for coupling said comparator to said switching circuit for causing said integrated signal or said second analogue signal to be coupled to said controller depending on the compared signal, and said controller including means for varying the temperature of said medium according to said integrated signal and holding said temperature steady according to said second analogue signal.

4. The apparatus as set forth in claim 3, wherein said comparator includes means for generating a sign indicating signal which indicated whether said integrated signal must increase or decrease to become equal to said second analogue signal, means coupled to said first digital to analogue converter for receiving said sign indicating signal for causing said signal representing change of temperature produced by said first digital to analogue converter to have a polarity determined by said sign indicating signal.

5. The apparatus as set forth in claim 3, further comprising:

means for supplying new information to said first and second registers directing a new rate of change of said temperature of said medium and a new end point for said new rte of change.

6. The apparatus according to claim 5, wherein said integrator includes;

an operational amplifier and a capacitor;

means for coupling said capacitor to said second digital to analogue converter when said second analogue signal is coupled to said controller for maintaining a charge on said capacitor substantially equal to the potential of said second analogue signal;

whereby when new information is supplied to said registers said integrator begins integrating at the previous end point.

7. An apparatus for controlling the temperature variation of a medium during an operational process comprising:

a switching circuit;

means for supplying analogue information to said switching circuit indicating the desired change of said temperature of said medium during a given period of time;

means for supplying steady state information to said switching circuit indicating the end point of said change of said temperature of said medium;

a comparator;

means for supplying said analogue information and said steady state information to said comparator;

said comparator including means for generating a compared signal indicating whether said amplitude of said analogue information representing the desired change has reached the end point represented by said steady state signal;

a controller coupled between said switching circuit and said medium provided for receiving information from said switching circuit, and means for coupling said compared signal from said comparator to said switching circuit for causing said analogue information representing change of temperature to be coupled through said switching circuit to said controller when it is desired to change the temperature of said medium and for causing said steady state information to be coupled through said switching circuit to said controller when it is desired to hold the temperature of said medium constant.

8. An apparatus for controlling the operating process of a device comprising:

an integrator for generating integrated information representing a desired change in said process;

means for generating steady state information of a predetermined potential indicating the desired end point of said change in said process;

a switching circuit having an output coupled to said device;

a comparator having inputs and an output;

means for coupling said integrator to said comparator and said switching circuit;

means for coupling said means for generating steady state information to said comparator and said switching circuit;

said comparator indlcuing means for generating a compared signal indicating whether said integrated signal is equal to said steady state signal;

means for coupling said compared signal to said switching circuit for causing said integrated information to be coupled through said switching circuit when it is desired to change the operating process of said device and for causing said steady state information to be coupled through said switching circuit to said device when it is desired to hold the operating process constant.

9. The apparatus as set forth in claim 8 wherein;

said integrator includes a capacitor, means for coupling said capacitor to said steady state information when said steady state information is coupled to said device for maintaining a potential on said capacitor substantially equal to said steady state information.

10. The apparatus as set forth in claim 7 further comprising:

a resistor network coupled to an input of said integrator;

means for decreasing the resistance of said resistor network responsive to receiving a predetermined signal for causing said integrator to produce an integrated signal of substantially infinite slope.