SU792225A1 - Temperature control apparatus - Google Patents

Description

(54) DEVICE FOR REGULATING TEMPERATURE

The invention relates to the field of temperature control using electrical means and can be used in various industries, in particular, in the automation of technological processes to maintain a given temperature level with a very high degree of accuracy. Such devices arose in connection with increased requirements for product quality. Their use increases the yield of products, reduces the time needed to manufacture products of high quality. Devices in which the temperature is maintained within the dead zone are widely known. A device for automatic temperature control is known, comprising a sensor, a setting device, a comparison unit, a key, a zero-organ, a reversing counter, a forcing device, a first generator, a second generator, an actuator, an electric heater. The disadvantage of such a device is the presence of an adjustment error even under stable external conditions. Of the known devices, the system of automatic temperature control 2 is the closest to the technical essence. This device has a two-type signal generation circuit, a shift register, a pulse generator, a pulse generation circuit at the time of a network voltage zero crossing, several thyristor trigger circuits, several power T1fistor keys, a transformer with several taps, scheme, vfa .-. the pilot signals corresponding to the set temperature, the heater, the starting circuit, forcing the power thyristor keys to be started only when the network voltage goes through zero, the power supply breaker in case of overheating. The disadvantages of the device include the presence of additional components of the error in maintaining a given

temperature level and technical complexity.

The aim of the invention is to increase the accuracy of the device.

The goal is achieved by the fact that the temperature control device contains a block for changing the cut-off angle and a second temperature setting device connected in series, a second comparison unit and a cut-off angle control unit, the second input of which is connected to the output of the first comparison unit and the second input of the second comparison unit, the third input with the output of the pulse generator, and the output of the control unit for the cut-off angle is connected to the second input of the reversible counter, the output of which is connected to the first input of the block for changing the cut-off angle, in The input is connected to the output of the synchronization unit, and the output is to the INPUT of the thyristor triggering unit, the second output of the temperature measuring unit is connected to the third input of the second comparator unit, the cut-off angle control unit contains a series-connected trigger and the first And element, the output of which is connected with the output of the block, the second and third inputs of the first element I are connected respectively to the first and third inputs of the block, and the trigger input to the second input, the second comparison block contains a series-connected comparator BToipoA element And the output of which is connected with the output of the block, the inputs of the comparator are connected to the first 1M and the third inputs of the block, the second input of which is connected to the second input of the second element AND, and also, for the sake of simplicity, the block for changing the cut-off angle contains series-connected a generator, a counter, a zero-organ and a one-shot, the output of which is connected to the output of the block, the second input of the zero-organ is connected to the first M input of the block, the second 1 inlet of which is connected to the second input of the counter.

FIG. t is represented by a device for temperature control; FIG. 2 shows the cut-off angle control unit of FIG. 3 - the second comparison block; .on FIG. 4 - block change UCP cutoff.

The device contains a second comparison unit I, a first comparison unit 2, a temperature measurement unit 3, a heater 4, a pulse generator 5, a cut-off angle control unit, a switch 7, a thyristor switch 8, a reversible counter 9, a cut-off angle change block iO, a block of synchronization II, a block 12 launch

thyristors, the first setting to t3 temperature and the second setting 14 temperature.

The BLOCK 6 control of the cut-off angle. Contains a trigger 15 and the first element AND 16.

The comparison block I contains a comparator 17 and the second element AND 18.

The block 10 for changing the cut-off angle comprises a generator 19, a null organ 2O, a counter 21 and a one-shot 22.

FIG. 1-4 accept the following letter designations:

f-i frequency generator 5 pulses;

 oscillator frequency 19; N is a sequence of pulses arriving on the counting input of the reversible counter 9;

W - direction control signal

reversible counter 9; 6 - potential outputs of the reversible counter 9, A - potential outputs of the counter 21; 3 y - fixed recording signal

the numbers in the reversible counter 9i M are the signal of the actual topics. perature;

U - the signal of a given temperature; U) is a signal about a given temperature, which is negative for the dead zone;

N-J - thyristor trigger pulses; Na. by pushing thyristor triggering pulses; ULr - initial setup pulses

the numbers in the counter 21; B is the voltage applied to

heaters; C - equality signal; - signal of equality of actual and set temperature; Y - a signal of exceeding a given

temperature on the value of L T; K - signal of emergency overheating; p is the power supply voltage that is turned off during emergency overheating;

bk - set trigger signal to

initial state when power on.

The temperature control device operates as follows.

The device for temperature control uses the signals W and V, defined as follows. The signal W has two logical states, described by the following simulation: fO, if Г С-г- (addition), if -fc Лт (subtraction), tv is the target temperature of the object; fc-j- - the actual temperature of the object. The W / 1 signal is described by the following expression; (b if tt-C 1o, if F fc-f Signal W is used to control the direction C40ia of the reversing chuck E. Signal W / is used to enable the reversal counter 9 of the pulse sequence H defined by the relation; b ttr to feed to the counting input. , ecnH-fc tr. (3) The expression (3 / is true when the initial temperature is reached. As follows from relations (l) and (3) in the reversible counter 9, the recorded number is stored, which is added or subtracted from the sequence depending on the action ratio - telnaya b- and set. In the case of equality of the actual and set temperatures (ty - t), the counting input of the reversible counter 9 does not receive pulses, the reversing counter 9 stores the accumulated number obtained when the set temperature is reached. With external disturbances (change in supply voltages, external conditions etc.) equal temperatures are violated, the pulses L arrive at the counting input of the reversible counter 9, changing the number accumulated in it in the required direction until a new equilibrium state is obtained. Information about the phase shift of the cut-off angle is used, block измен change of cut-off angle; (Fig. 4). The pb scheme is as follows. The counting input of the counter 21 receives pulses from the generator 19. The installation input of the counter 21. Pulses are given. The HL pulses are generated every time the amplitude of the supply voltage is zero. Each pulse from the sequence of GP sets in the counter 21 a preselected floating number. The sequence of impulses f 2. about the generator 19 is subtracted from the fixed number recorded in the counter 21, reducing its content to 256 zero. The contents of the reversible counter 9 and the counter 21 are fed to a null organ 2O. As a result of comparing the number recorded in the reversible counter 9 with the sequence of numbers of the counter 21 at the input of the null organ 2O, a signal C t is generated that determines the firing angle T1 of the fistors. This signal is formed at the output of the null organ 2O with a equality of the numbers coming from the reversing counter 9 and counting 21. Changing the accumulated number in the reverth counter 9 causes the ignition of the thyristor key 8 to change. The quality of temperature control depends on the selected frequency range ff of the 5 pulse generator. The problem of choosing the frequency range f is solved in the theory of automatic control. . As follows: from the description of the action, the proposed device for temperature control, unlike the prototype, has a long-term stable equilibrium state, which is achieved in the system by using the cut-off angle control unit 6, the signal generation scheme of equality of the actual and set temperatures and the corresponding Bi i6opOM of the counter of 21 pulses of the unit Yu of the change of the angle from -. chaff. Next, a practical implementation of the block 6 controlling the cut-off angle and generating a signal about the equality of the actual and predetermined temperatures will be considered, and a criterion for choosing the volume of the counter 21 pulses of the block is given. The cut-off angle control unit shown in FIG. 2, works as follows. When 1W power is turned on, the trigger 16 is set to the initial state, prohibiting the passing-i.e. pulses F through the first element 16. The trigger 15 is set to the state allowing the pulses to pass at 1, i.e. W 1. Thus, from the moment of switching on until the moment the set temperature reaches the counting input of the reversible counter 9, the pulses from the generator of 5 pulses do not arrive, and by recording different fixed numbers to the reversing counter 9 (as a function of time), heating is achieved according to any given law . With this technical solution, it is possible to ensure the fastest 77 achievement of the desired temperature upon initial activation. After reaching the specified temperature, the operation of the reversible counter 1ka 9 is determined by the signals W and, which are defined by the expressions (l) and (3). Below will be considered the operation of the device while maintaining a given temperature level in cases where -t.-t-T-. those. set temperature is more than valid; -J T, i.e. set temperature is equal to real; If, i.e. set temperature is less than actual. In the first case (, N - i) Signal). W 0 defines an add operation. The sequence of pulses from the first element 16 goes to the counting input of the reversible counter 9. As a result of increasing the number in the reversing counter 9 at the output of the nullane 2O, the cut-off angle of the thyristor switch 8, which leads to an increase in the voltage supplied on the heater 4. Thus, for the considered case; when the t i system is created, the conditions under which C-f rises. In the second case (W / j l, Ns O), the reversible counter 9 stores the number accumulated by it until the equilibrium Go state is obtained. The cut-off cut-off angle of the histories does not change, therefore, Hte changes and the voltage applied to heater 4. In this way, for the case in the device, conditions are created to maintain a given temperature level. In the third case (W l,) 4sf j) signal W -1 determines the operation of subtracting pulses. And in the reversible counter 9 As a result of decreasing the number in the reverse reader 9, the cut-off angle of the thyristor switching on the tafistor key increases, which leads to a decrease in the voltage supplied to the heater 4. Thus, for case 11 - CONDITIONS are created in the system under which 6 decreases. The second comparison block I (FIG. 3) outputs the signal W-t, described by the expression (2). Wy signal generation | is achieved by using the second element 18 and the comparator 17, whose ndpor is different from the threshold of the first comparison unit 2 by the required deadband. Co 8 arator 17 is signaled as follows: if (l, D-1. E., R if tj- t tA-fc As follows from the description of the operation of the second comparison unit 1, the cut-off angle control unit 6 in the demanded system a necessary condition is provided for obtaining a long-term equilibrium state. However, without the correct choice of the volume of the counter 21, this condition is not sufficient. Obviously, to obtain a long-term equilibrium state, it is necessary to select the required cut-off angle to turn on the thyristors Cha 8. To ensure the entire working temperature range, it is desirable to have a continuous adjustment characteristic. In discrete systems, this can be achieved by a high degree of approximation of the continuous adjustment characteristic. The degree of approximation in the proposed device is determined by a given amount of information (the number of bits in the meter -21). Thus, in the inventive temperature control device, necessary and sufficient conditions are provided for obtaining a long-term equilibrium state. no. While in the prototype, additional components of the maintenance of a given temperature are caused by the application of a two-level signal processing circuit and a step-by-step voltage supply to the heater, leading to the absence of a stable equilibrium state. In the scheme happens. temperature control even in the absence of external disturbances, which leads to the appearance of additional components of the error of maintaining a given temperature. The inventive temperature control device is less complicated than the prototype. In devices for temperature control, using W and VVj or VV signals directly to control, it is not possible to obtain an integral control law. To achieve this goal, in the prototype, a shift register is used, which includes alternately Tiris. torches that supply the power voltage of the network in the form of a step on the heater, while using a power transformer with several taps to obtain a stepped voltage.

In the inventive system, this goal is achieved, as shown above, otherwise. Due to the construction of the above schemes, the rpaHc4iopmator with five taps was excluded in the inventive system, four starting schemes for the thyristors and a couple of power t;

In the device claimed, the initial heating is achieved according to a predetermined law by recording a fixed number in the reversible counter 9 and the operation of the trigger 15. This eliminates the use of a controlled oscillator in the prototype.

The proposed device is made on the integral elements of the industrial series, which makes it possible to master its implementation in mass production.

Claims (3)

Invention Formula t. A device for controlling a generator containing a pulse generator, a synchronization unit, a thyristor startup unit, a first setpoint temperature controller, a first comparison unit and a reversible counter, a temperature measuring unit connected in series, a switch, a chip switch and a heater, and a second measuring unit output temperature is connected to the second input of the first comparison unit, and the output of the thyristor triggering unit - to the second input of the thyristor key, characterized in that, in order to increase the accuracy This includes a block for changing the cut-off angle and a second temperature setting unit connected in series, a second comparison unit and a cut-off angle control unit, the second input of which is connected to the output of the first comparison unit and the second input of the second comparison unit, the third input - to the output of the pulse generator, A B151 inlet of the cut-off angle control unit is connected to the second input of the reversible counter, the output of which is connected to the first input of the block of change 5 of the cut-off angle, the second input of which is connected to the output of the synchronization block, and the output (d) to the input of the Tfisto launcher, with the second output of the temperature measuring unit being connected to the third input. Q of the second comparison block. 2. The device according to claim 1, characterized by the fact that the control unit for the cut-off angle comprises a series-connected trigger and the first element I, 5, the output of which is connected to the output of the block, the second and third inputs of the first element I are connected respectively to the first and third inputs of the block, and the trigger input to the second input. „ 3. Device pop. 1, characterized in that the second comparator unit comprises a series-connected comparator and a second AND, the output of which is associated with the output of the unit,  the inputs of the Comparator are connected to the first and the third inputs of the unit, the second input of which is the second input of the second element I. 4, The device according to p. I, o h-l and cha eu e with the fact that, in order to simplify Uh The cut-off angle change unit contains a generator connected in series, a counter, a null organ, and a one-shot, the output of which is connected to the output of the unit, a second input of the null organ connected to the input of the unit, the second input of which is connected to the second input of the counter. Sources of information taken into account in the examination 1. USSR author's certificate No. 224933, cl. Cr 05 D 23/19, 1967. 2. Accepted UK application No. 126163, cl. dr 3 R published, 1972. (prototype). Phi.1 17 w. nineteen Wi 18 Puz with r Ni go 22 21 FIG.