KR101132186B1 - Temparature control system for the industrial cooler - Google Patents

Abstract

The present invention relates to a temperature control system of an industrial cooler, and more particularly, to cool a heat load generated in a processing part of an industrial machine used in a production process of various industries such as a machine tool or a precision machining machine by using oil. The present invention relates to a temperature control system of an industrial chiller capable of precisely controlling the coolant temperature of an industrial chiller used for the purpose.
The present invention provides a temperature control system for a chiller including a condenser, an expansion valve, an evaporator, and a compressor, wherein a discharge gas bypass valve is connected between an outlet of the compressor and an inlet of the evaporator, and the discharge gas bypass valve is installed. The cooler is characterized in that the temperature control unit for controlling the temperature of the cooling fluid is installed.

Description

Temperature control system for industrial chillers {Temparature control system for the industrial cooler}

The present invention relates to a temperature control system of an industrial cooler, and more particularly, to cool a heat load generated in a processing part of an industrial machine used in a production process of various industries such as a machine tool or a precision machining machine by using oil. The present invention relates to a temperature control system of an industrial chiller capable of precisely controlling the coolant temperature of an industrial chiller used for the purpose.

In recent years, as the production process of high-tech industrial machines has been gradually speeded up, automated, and precisionized, various industrial technologies have been actively developed, ranging from energy-saving function, productivity, high quality, and eco-friendly equipment in all industrial machines.

Due to the high speed and high precision of such industrial machines, the necessity of a precision cooler for preventing thermal deformation is required for driving system, heat exchange equipment, mold, product cooling, and the like.

In the modern production system, unlike in the past, high insulation cutting speed and feed rate are frequently generated in the processing equipment, which causes considerable heat generation in the workpiece and the processing position, and heat generated by friction in the guide surface due to the high-speed transfer. The structure is severely deformed.

Due to the high speed technology of the machine tool, heat is generated in the drive system, and this heat spreads to the machine tool structure to produce non-uniform temperature distribution, resulting in thermal deformation of the machine tool parts, and as a result, processing precision and machine It is a major obstacle to reliability.

As a method for suppressing irregular heat generation in the machine tool, a cooler such as an oil cooler or a water cooler is used for the main shaft, the ball screw, the guide way, and the like, which are high-speed movement parts of the machine tool.

Among these, the oil cooler maintains hydraulic oil or cutting oil at a constant temperature of the driving part of the machine tool, thereby minimizing thermal deformation, thereby improving processing precision and enabling high-speed processing.

In general, the cooling of a machine tool using an oil cooler uses a method of maintaining the temperature of the main shaft within a certain range by supplying a constant low temperature oil of the oil tank to the main shaft regardless of the change in calorific value in the main shaft.

However, such a cooling method has a limitation in keeping the temperature of the main shaft constant, and thus there is a problem that thermal deformation occurs in the structure due to the temperature rising or falling according to the load condition of the main shaft.

Since the temperature of the main shaft of the machine tool changes rapidly due to the heat generation according to the operating conditions, the temperature of the cooling oil passing through the main shaft can be actively cooled according to the heating condition by adjusting the temperature of the cooling oil accordingly to the optimum state. Is a very important factor.

The control method applied to a conventional machine tool cooler is mostly an on-off control method that turns on a compressor to obtain a desired temperature.

However, the on-off control method does not adequately respond to the load that continuously changes over time, so that precise temperature control is impossible, and there is a problem that the power consumption can be increased and the compressor life can be shortened by repeating the start and stop.

In addition, the on-off control method has a problem in that responsiveness is slow due to oil temperature characteristics, and stabilization time is long due to overshoot.

The present invention has been made to solve the above problems, the object of the present invention is not only to reduce the power consumption increase due to the starting torque generated during the start and stop of the compressor, but also precisely by responding to the external heat load fluctuations every time It is to provide a temperature control system of an industrial cooler capable of temperature control.

In addition, the present invention uses the discharge gas bypass method to control the temperature of the cooling oil oil temperature control of the industrial cooler that can reduce the outlet temperature deviation of the cooling fluid discharged from the compressor and shorten the response to the set temperature There is another purpose in providing a system.

The present invention for achieving the above objects,

In a temperature control system of a cooler including a condenser, an expansion valve, an evaporator, and a compressor, a discharge gas bypass valve is connected between an outlet of the compressor and an inlet of the evaporator, and a cooler in which the discharge gas bypass valve is installed is cooled. The temperature control unit for controlling the temperature of the fluid is characterized in that the connection is installed.

At this time, the discharge gas bypass valve is characterized in that the electronic expansion valve with a stepping motor.

The temperature control unit may include a power control unit for supplying power, and a temperature control unit configured to adjust the opening degree of the discharge gas bypass valve by sensing the temperature of the cooling fluid.

The temperature control unit may further include a display and an operation unit configured to display the present temperature and the set temperature of the cooling fluid and to manually adjust the opening degree of the discharge gas bypass valve.

Here, the temperature control unit is a stepping motor driving unit for driving the stepping motor provided in the electronic expansion valve, a temperature measuring unit for measuring the refrigerant temperature of the compressor outlet, and stepping in accordance with the refrigerant temperature of the compressor outlet measured from the temperature measuring unit It is characterized in that it comprises a PLC (PLC) for controlling the motor drive unit and a power supply for converting an AC voltage into a DC voltage.

The temperature measuring unit may include a thermocouple installed at an outlet of the compressor and a temperature converter configured to convert a resistance value measured by the thermocouple into temperature.

The PLC may control the stepping motor driving unit by any one of a proportional controller, a proportional integration controller, and a controller combining a proportional integration controller and a fuzzy control.

According to the present invention, by installing a discharge gas bypass valve between the outlet of the compressor and the inlet of the evaporator, the outlet temperature of the cooling fluid discharged from the compressor can be reduced and the response to the set temperature can be shortened. Has an effect.

In addition, according to the present invention, it is possible to continuously operate the compressor regardless of the load of the evaporator, thereby reducing power consumption increase due to starting torque generated when the compressor is started and stopped, and precisely responding to external heat load fluctuations every time. The temperature control further has a possible effect.

1 is a conceptual diagram conceptually showing the components of a cooler used in a temperature control system of an industrial cooler according to the present invention.
2 is a conceptual diagram conceptually showing a temperature control system of an industrial cooler according to the present invention.
3 is a plan view showing an embodiment of the display and the operation unit of the present invention shown in FIG.
4 is a configuration diagram showing in detail the temperature control unit of the present invention shown in FIG.
5 is a block diagram showing the configuration of an electromagnetic expansion valve of one embodiment of the discharge gas bypass valve of the present invention shown in FIG.
Figure 6 (a), (b) is a graph showing the control temperature change characteristics by the temperature control system of the industrial cooler according to the present invention in comparison with the conventional method.
7 to 9 are graphs showing the results of temperature control by a control method combining a proportional integral controller and a purge control in a temperature control system of an industrial cooler according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the temperature control system of the industrial cooler according to the present invention.

1 is a conceptual view showing the components of the cooler used in the temperature control system of the industrial cooler according to the present invention, Figure 2 is a conceptual view showing a temperature control system of the industrial cooler according to the present invention, Figure 3 2 is a plan view showing an embodiment of the display and the operation unit of the present invention shown in Figure 2, Figure 4 is a configuration diagram showing the temperature control unit in detail in the present invention shown in Figure 2, Figure 5 is a discharge gas of the present invention shown in Figure 2 6 is a block diagram illustrating a configuration of an electronic expansion valve, which is one embodiment of a bypass valve. FIGS. 6 (a) and 6 (b) illustrate changes in control temperature by a temperature control system of an industrial cooler according to the present invention. 7 to 9 are graphs comparing and controlling a combination of a proportional integral controller and a purge control in a temperature control system of an industrial cooler according to the present invention. A graph showing the results of temperature control by the method.

The present invention precisely cools the temperature of the cooling oil of the industrial cooler 100 used to cool the heat load generated in the processing part of the industrial machine used in the production process of various industries, such as machine tools, precision machining machines, using oil. It relates to a temperature control system of the industrial cooler that can be controlled easily, the configuration is largely the hot-gas bypass valve (hot-gas bypass valve) 200 and the temperature installed inside the cooler 100 and the cooler 100 It is configured to include a control unit 300.

In more detail, first, the cooler 100 is used to cool a heat load generated in a processing part of an industrial machine used in a production process of various industries, such as a machine tool, a precision processing machine, using oil, As shown in FIG. 1 and FIG. 2, the condenser 110, the receiver 120, the expansion valve 130, the evaporator 140, and the compressor 150 are configured.

That is, it is possible to cool the heat load generated in the processing part of the industrial machine by circulating the refrigerant through the above components, which are the same as the components of the cooler 100 currently being used in general Detailed description of the configuration and the effect and the like will be omitted.

Next, as shown in FIGS. 1 and 2, the discharge gas bypass valve 200 is connected between the outlet of the compressor 150 and the inlet of the evaporator 140 to compress the high temperature and high pressure of the compressor 150. By bypassing the refrigerant (eject gas) to the inlet of the evaporator 140 serves to mix with the low temperature and low pressure refrigerant.

That is, by bypassing the high temperature and high pressure refrigerant by the discharge gas bypass valve 200 as described above, the temperature of the evaporator 140 is increased and the cooling capacity is decreased, so that the discharge gas bypass valve 200 By controlling the opening degree by controlling the cooling capacity of the evaporator 140, it is possible to control the temperature of the cooling oil without the on-off operation of the cooler 100.

In this case, it is preferable to use an electronic expansion valve (EEV) 200 which is driven by the stepping motor 210 as the discharge gas bypass valve 200. The reason is that the electronic expansion valve 200 This is because it is driven by the stepping motor 210, it is easy to control, it is easy to switch to manual and automatic as well as precise driving is possible to improve the reliability.

The electromagnetic expansion valve 200 used in the present invention is configured as shown in FIG. 5, which will be briefly described. The stator 202 rotates the rotor 204 clockwise by the driving of the stepping motor 210. When rotated counterclockwise, the needle 206 having a small thread of friction moves up and down, and is configured to adjust the opening amount of the electromagnetic expansion valve 200.

On the other hand, the cooler 100 in which the discharge gas bypass valve 200 is installed is connected to the temperature control unit 300 to control the temperature of the cooling fluid, the temperature control unit 300 is largely the power control unit 310 ) And a temperature control unit 320 is configured.

In more detail, the power controller 310 serves to supply power to each component of the cooler 100 and the temperature controller 300 by receiving power from the outside, as shown in FIG. Power is supplied to the fan 112 provided in the condenser 110 of the cooler 100, the discharge gas bypass valve 200, the compressor 150, and a circulation pump (not shown) for circulating the cooling fluid. Also, power is supplied to the temperature controller 320 to be described later.

In this case, the power control unit 310 may be configured to control the rotational speed of the fan 112 provided in the condenser 110, which is a pressure sensor (not shown) at the inlet / outlet of the condenser 110, respectively. ) And to detect the high pressure side of the pressure measured by the pressure sensor to control the rotation speed, that is, the rotation speed of the fan (112).

Therefore, the condensation pressure can be stabilized by the rotation speed control of the fan 112 as described above, and the supercooling degree of the refrigerant can be maintained at the inlet of the expansion valve 130, thereby not only stabilizing the cooling system but also allowing more precise temperature control. Done.

Next, the temperature controller 320 adjusts the opening amount of the discharge gas bypass valve 200, that is, the electronic expansion valve 200 by sensing the temperature of the cooling fluid measured by the temperature measuring unit 324 which will be described later. As shown in FIG. 4, a stepping motor driving unit 322, a temperature measuring unit 324, a programmable logic controller (PLC) 326, and a power supply 328 are largely configured. do.

In more detail, the stepping motor driver 322 serves to drive the stepping motor 210 provided in the electronic expansion valve 200 by receiving power from the power control unit 310, and the PLC 326. It can be driven up to 0 ~ 500 steps in the forward or reverse direction by the control of the control) is configured to precisely adjust the opening degree of the electromagnetic expansion valve (200).

Next, the temperature measuring unit 324 serves to compare the actual temperature of the refrigerant with the set temperature to control the temperature of the refrigerant (discharge gas) discharged to the outlet of the compressor 150, thermocouple ( thermo couple) 324a and a temperature converter 324b.

That is, the thermocouple 324a is installed at the outlet of the compressor 150 to change the resistance value according to the change in the refrigerant temperature, and the temperature converter 324b is connected to the thermocouple 324a and installed in the thermocouple 324a. It measures the resistance value appearing at and converts it to temperature.

Next, the PLC 326 replaces a relay, a timer, a counter, and the like in a conventional control panel with a semiconductor device such as an IC or a transistor, and adds an arithmetic function to a basic sequence control function to control a program. Means a general-purpose control device to enable the opening amount of the electronic expansion valve 200 by controlling the stepping motor drive unit 322 in accordance with the refrigerant temperature of the outlet of the compressor 150 measured from the temperature measuring unit 324. To control the

In this case, the PLC 326 is a stepping motor driving unit 322 by any one of a proportional controller (Proportional controller), a proportional integral controller (Proportional-integral controller), and a controller combining the proportional integral controller and the fuzzy control (322). The proportional controller multiplies the error signal, which is the difference between the reference signal and the feedback signal, to produce a control signal. The proportional integral controller provides an error. Integral control, which integrates signals to produce control signals, is used in parallel with proportional control. Its advantage is that control gain adjustment is relatively easy and the control performance is excellent. Fuzzy control is a linguistic form of expert control knowledge. A mathematical model that allows the controller to operate based on the described control rules There is no need, in the knowledge of experts has the advantage of ease of control on the number of systems nonlinear systems and control variables.

Such control methods are conventionally used, and detailed descriptions including a transfer function for the control methods will be omitted since the present invention is not intended to be claimed in detail.

Accordingly, the PLC 326 transmits a control signal to the stepping motor driver 322 through the above-described control methods, which are programmed through the TRILOGI program, and the PLC (326) is used. 326).

Next, the power supply 328 converts the 220V AC current coming from the external or power control unit 310 into 24V DC so as to be stably used by the PLC 326 and the stepping motor driver 322. It is to play a role.

Briefly introducing the operation of the temperature control unit 320 configured as described above are as follows.

First, the thermocouple 324a installed at the outlet of the compressor 150 causes a change in the resistance value according to the temperature change of the cooling fluid, and the temperature converter 324b installed at the thermocouple 324a measures the resistance value to a temperature. After the conversion, the converted temperature value is transmitted to the PLC 326.

The PLC 326 receives a pulse according to the transmitted temperature value by receiving any one method of the proportional controller, the proportional integral controller, and the controller combining the proportional integral controller and the fuzzy control programmed through the TRILOGI program from the computer 327. The pulse signal is transmitted to the stepping motor driver 322 by calculating the value.

The stepping motor driving unit 322 receiving the pulse signal drives the stepping motor 210 in one step per pulse. In the present invention, the electronic expansion valve 200 used as the discharge gas bypass valve 200 is 0 to 0. Since driving in 500 steps is possible, the stepping motor 210 rotates by 0.72 degrees per step. That is, in step 0, when the electromagnetic expansion valve 200 is completely closed, the discharge gas discharged to the outlet of the compressor 150 is not bypassed. In case of 500 steps, the electromagnetic expansion valve 200 is completely opened and discharged. The gas is bypassed entirely without moving to the condenser 140.

Meanwhile, the temperature control unit 300 may further include a display and an operation unit 330. The display and operation unit 330 may display the present temperature and the set temperature of the cooling fluid as shown in FIG. At the same time, the setting button 332 serves to adjust the opening amount of the discharge gas bypass valve 200 manually or automatically.

As such, the temperature change characteristics of the cooling fluid using the temperature control system of the industrial cooler according to the present invention are compared with the temperature change characteristics of the cooling fluid by the conventional compressor on-off method. Shown in

As shown in (a) and (b) of FIG. 6, when the discharge gas discharged from the compressor 150 is controlled by the present invention, more precise temperature control is achieved by converging precisely to the target temperature as compared to the conventional on-off method. It can be confirmed that is possible.

값과

값은 각각 PI제어에서의 비례상수와 적분계수를 나타낸다.Meanwhile, in FIGS. 7 to 9, a temperature control system of an industrial cooler according to the present invention is applied by applying a control method combining a proportional integral controller (PI control) and a fuzzy control among temperature control methods by PLC 326. The applied test results are shown. First, FIG. 7 shows the test results when an external air temperature of 30 ° C. is applied to an external load of 2 kW.

Value and

The values represent proportional constants and integral coefficients in PI control, respectively.

값과

값은, 지글러-니콜스(Ziegler-Nichols)의 계단응답법과 임계진동법에 의해 구해진 값으로 계수를 조정하여 선정하였으며,

값이 417인 경우

값의 2배 차이에 따른 결과를 보여준다.At this time,

Value and

The values were selected by adjusting the coefficients to the values obtained by Ziegler-Nichols step response method and critical vibration method.

If the value is 417

It shows the result of the difference of 2 times.

값이 4.17인 경우, 0.61℃의 오버슈트(overshoot)가 발생하였고, 0.1℃의 오차가 발생하였다. 또한,

값이 2.08인 경우 오버슈트가 발생하지 않았으며 0.2℃의 오차가 발생하였다.That is, when looking at the experimental results, when the control result target temperature is 25 ℃,

When the value was 4.17, overshoot of 0.61 ° C. occurred and an error of 0.1 ° C. occurred. Also,

When the value was 2.08, no overshoot occurred and an error of 0.2 ° C occurred.

값이 4.17인 경우 1.18℃의 오버슈트가 발생하였고,

값이 2.08인 경우 0.50℃의 오버슈트와 0.1℃의 오차가 발생하였다.8 shows an experimental result when the external load is 3 kW under the same control conditions as in FIG. 7.

When the value is 4.17, overshoot of 1.18 ° C occurred.

If the value is 2.08, an overshoot of 0.50 ° C and an error of 0.1 ° C occur.

값을 2.08로 하는 경우

값을 4.17로 하는 경우보다 오버슈트가 적게 발생하여 안정적인 제어가 가능하므로 2.08이 보다 좋은 제어변수임을 확인할 수 있다.therefore,

If the value is 2.08

It is confirmed that 2.08 is a better control variable because less overshoot occurs and the stable control is possible than the value is set to 4.17.

인 경우, 외부부하를 2kW에서 갑자기 3kW로 변화시키는 경우의 실험 결과를 나타낸 것으로, 부하 변동시 약간의 진동이 생기다가 시간이 지나면 다시 수렴하는 것을 확인할 수 있었다. In addition, FIG. 9 shows the same control conditions as FIGS. 7 and 8.

In the case of, the experimental result of suddenly changing the external load from 2kW to 3kW was shown. When the load fluctuated, a slight vibration occurred and then converged again after time.

Therefore, when the control method combining the proportional integral controller (PI control) and the fuzzy control (fussy control) is applied to the present invention, it can be seen that a control result that is quite close to the target temperature can be obtained.

Therefore, according to the temperature control system of the industrial cooler according to the present invention configured as described above, the discharge gas bypass valve 200 is installed between the outlet of the compressor 150 constituting the cooler 100 and the inlet of the evaporator 140. As a result, the outlet temperature of the cooling fluid discharged from the compressor 150 can be reduced and the response to the set temperature can be shortened, and the compressor 150 can be continuously operated regardless of the load of the evaporator 140. Therefore, not only the power consumption increase due to the starting torque generated when the compressor 150 is started and stopped can be reduced, but also various effects such as precise temperature control are made possible by responding to the external heat load fluctuations every time.

The above embodiments have been described with respect to the most preferred example of the present invention, but are not limited to the above embodiments, and change the installation position of the discharge gas bypass valve 200, or the power control unit 310 and the power supply ( It is apparent to those skilled in the art that various modifications can be made without departing from the technical spirit of the present invention, such that the configuration of 328) can be used in one configuration.

The present invention relates to a temperature control system of an industrial cooler, and more particularly, to cool a heat load generated in a processing part of an industrial machine used in a production process of various industries such as a machine tool or a precision machining machine by using oil. The present invention relates to a temperature control system of an industrial chiller capable of precisely controlling the coolant temperature of an industrial chiller used for the purpose.

100: cooler 110: condenser
112: fan 120: receiver
130: expansion valve 140: evaporator
150: compressor
200: discharge gas bypass valve (electromagnetic expansion valve)
202: stator 204: rotor
206: needle 210: stepping motor
300: temperature control unit 310: power control unit
320: temperature control unit 322: stepping motor drive unit
324: temperature measuring unit 324a: thermocouple
324b: temperature converter 326: PLC (PLC)
327 Computer 328 Power Supply
330: display and control panel 332: setting button

Claims (7)

In a temperature control system of a chiller comprising a condenser, an expansion valve, an evaporator and a compressor,
Between the outlet of the compressor and the inlet of the evaporator is connected to the discharge gas bypass valve consisting of an electronic expansion valve with a stepping motor,
The cooler in which the discharge gas bypass valve is installed is connected to a temperature control unit for controlling the temperature of the cooling fluid.
The temperature control unit is configured to include a power control unit for controlling the rotational speed of the fan provided at the same time while supplying power, and a temperature control unit for controlling the opening degree of the discharge gas bypass valve by sensing the temperature of the cooling fluid,
The temperature control unit is a stepping motor driving unit for driving a stepping motor provided in the electronic expansion valve, a temperature measuring unit for measuring the refrigerant temperature of the compressor outlet, and stepping motor driving unit according to the refrigerant temperature of the compressor outlet measured from the temperature measuring unit It is configured to include a power supply for controlling the PLC (PLC) and the AC voltage to control the DC voltage,
The temperature measuring unit is a temperature control system of the industrial cooler, characterized in that composed of a thermocouple installed at the outlet of the compressor and a temperature converter for converting the resistance value measured by the thermocouple into temperature.
delete delete The method of claim 1,
The temperature control unit further comprises a display and an operation unit for displaying a current temperature and a set temperature of the cooling fluid and manually adjusting the opening degree of the discharge gas bypass valve.
delete delete The method of claim 1,
The PLC controls the stepping motor driving unit by any one of a proportional controller, a proportional integral controller, and a controller combining a proportional integral controller and a fuzzy control.

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