SU883879A1 - Temperature change rate regulator - Google Patents

Description

 The invention relates to automatic temperature control devices in closed volumes, mainly in techo cameras, and is intended for use in testing equipment and in a process control system. Digital temperature controllers for temperature changes l are used which are used in. composition of programmable regulators. Such controllers have a high accuracy ClJ. A disadvantage of the known regulators is the need for a constant setting of the initial conditions during the transition from one temperature to another. The closest to the proposed technical entity is a controller containing a master oscillator, digital frequency dividers, a reversible counter, a digital-to-analog converter that compares the device and the control circuit 12. However, in the known device, the regulation of the rate of change in temperature can be made only from the same temperature value, which is set by the trans. key to return. For an autonomous speed controller, it is necessary that the regulation be made not from a predetermined value, but from the existing temperature value in a controlled volume. Digital controllers can cause malfunctions, which leads to disruption of the entire process. The purpose of the invention is to expand the scope of digital. The goal is achieved by the fact that the temperature rate regulator contains a temperature sensor, a first master pulse generator and a digital frequency divider connected in series, as well as a series-connected reversing counter, a digital-to-analog converter, a reference element and a control unit, and the second input of the comparison element is It is connected to the output of the temperature sensor, as well as a compass & torus with the dead zone and the second master oscillator and the unit n in series switch, the second input of which is connected to the output of the digital frequency divider, and the output to the input of the reversible counter, and the inputs of the comparator are connected to

the inputs of the reference element and the output. with the third input of the switching unit. In addition, the switching unit contains the element NOT and element 2I-OR, whose input is connected to the output of the switching unit, the first inputs to the first and second inputs of the switching unit, and the second inputs to the output and input of the KB element, whose input is connected to the third input switching unit.

Lig.1 shows the block diagram of the proposed controller; 2 a hysteresis curve.

The controller contains serially connected first master oscillator 1 pulses, a frequency divider 2 one of whose outputs is connected via a switch to the second input of switching unit 3 connected through a switch to a reversible counter 4, whose outputs are connected to the corresponding inputs of a digital-analog converter 5 that is connected to one of the inputs of the comparison element b and the Comparator 7 with the dead zone. Other inputs of the comparison element b and comparator 7 are hooked up to the signal input bus from sensor 8, and the outputs, respectively, to control unit 9 and to: the executive unit and to the third input switching unit, the first input of which is connected to the output of the second master oscillator 10 pulses. The switching unit contains logic elements 2I-OR 11 and NOT 12. The first and second inputs of switching unit 3 are simultaneously the first inputs of logic element 2I-CLI 11, the second inputs of which are connected to input 1 and the third input switching unit. The output of logic element 11 is the simultaneous output of switching unit 3. Block 3 is associated with blocks 2 and 4. Through switches 13 and 14.

The regulator works as follows. the image.

The stable frequency signal from the first master oscillator 1 is fed to the input of a divider 2, which has seven outputs to form different rates of temperature change. Switching to the desired speed is carried out using switch 13, from the output of which the signal goes to switching unit 3, and from its output to switch 2, which changes the counting direction of the reversing counter 4. From the output of the reversing counter, the binary code goes to the corresponding the inputs of the digital-to-analog converter 5, at the output of which a linearly varying voltage is formed, is appropriate

set rate of temperature change. From the output of a digital-to-analog converter, the signal is fed to the single input of the comparison element b, to another input of which a signal is received from the sensor 8. At the output of the b element: the comparison, a voltage level is formed corresponding to the difference of the sensor signals and the diffraction analogue converter. This voltage is supplied to the heater control unit 9 or the refrigeration unit, depending on the type of temperature chamber and the method for controlling the temperature in it. From the output of the control circuit, the signal goes to the executive body, in particular, to the heater.

In addition, signals from the sensor and the digital-to-analog converter are fed to the input of the comparator 7.

If the absolute value of the difference of the input signals does not exceed the critical value D U ,,. CR, then the logical unit is present at the output of the comparator. At D & et-Kf. the comparator goes to the state of logical zero and is not in until AUg, becomes equal to zero, i.e. until the signals from the sensor and the digital-to-analog converter are equalized (FIG. 2),. Thus, by setting the comparator to the value of D U. p, more than the magnitude of possible temperature fluctuations in the chamber, one can achieve the exception of its influence on the process of controlling the rate of temperature change.

When the regulator is turned on, when the reversible counter is in an arbitrary state, and consequently, AUgj (to have a value greater than ih-krch, the comparator is triggered and switches the output of the switching circuit from the digital divider to the output of the second master oscillator 10. As a result, a quick recalculation occurs. reversible counter until AUg) becomes zero, i.e. until the output of the D / A converter establishes a signal corresponding to the temperature in the camera at a given time. The comparator will set the state of the logical unit and connect the output of the switching circuit to the output of the digital divider, the output of the digital-to-analog converter will begin to change at a predetermined speed, which corresponds to the normal operation of the controller.

Comparator works similarly to the occurrence of malfunctions in the controller operation, exceeding D Uj, p. The regulation error is automatically compensated, which increases the reliability of the controller.

Claims (2)

The maximum error of setting the initial condition and the compensation of failures is determined by the size of the zone. those. . The value of L Ugx. cr. It is set a little more than the value of the maximum permissible temperature fluctuations in the chamber, and consequently, the .cr, is the permissible error for this chamber. If the permissible temperature fluctuations in the chamber tend to zero, then and. Strives to zero. Probability of an error equal to AUgy. KR is very small. In the regulated temperature range Of600C, the probability of an error equal to uUg.p, while regulating the rate of temperature change through 1 is P 0.001 The proposed set of the comparator in the speed regulator of the comparator temperature change, with the dead zone of the second master pulse generator and switching unit, distinguishes the proposed the rate of change of temperature from the known, as the scope of application of the controller is expanded, which can be used not only as part of the program controller, but also About and autonomously, without operative intervention in the regulation process. Increased reliability avoids failures in the operation of the regulator, which is especially important when it is used in chambers designed for climatic testing of various products. Malfunctions of the regulator can lead to thermal shock, which is unacceptable for a number of tested products. Claim 1. Temperature rate regulator containing a temperature sensor, a first master pulse generator and a digital frequency divider serially connected, as well as a successively connected reversible counter, a digital-analog converter, a reference element, and a control unit, the second input of the comparison element being connected to sensor output temperature, characterized in that, in order to expand the scope of application, it contains a comparator with the dead zone and sequentially connect The second master pulse generator and the switching unit, the second input of which is connected to the output of the digital frequency divider, and the output to the input of the reversible counter, the comparator inputs are connected to the inputs of the reference element and the output to the third input of the switching unit. 2. The regulator according to claim 1, in which the switching unit contains the NOT element and the 2I-OR element, the output of which is connected to the output of the switching unit, the first inputs are from the first and second inputs of the unit switching, and the second inputs to the output and input of the element, whose input is connected to the third input of the switching unit. Sources of information taken into account during the examination 1. US Patent No. 3321608, cl. G 05 D 23/19, 1971. 2. Instruments for scientific research. 1972, 7, p. 56-58 (prototype.). oW | A% .KDlt | AUe, | | Fmgg