JP2007212107A - Cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve effective cost reduction without causing differences of cooling capacities due to power supply frequencies, even when an alternating current motor is used in an air cooling fan. <P>SOLUTION: The alternating current motor 2s is used as a fan motor 2. A power supply frequency discriminating means M1 is provided for discriminating a power supply frequency fs of an AC power supply 4 feeding the alternating current motor 2s. A supply power setting means M2 is provided for setting data Tc determining supply power required in a predetermined rotational speed Rv of the alternating current motor 2s per power supply frequency fs. A supply power control means M3 is provided for applying supply power corresponding to the data Tc set by the supply power setting means M2 to the alternating current motor 2s, in correspondence to the power supply frequency fs discriminated by the power supply frequency discriminating means M1, when the predetermined rotational speed Rv is assigned. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling device having an air cooling fan driven by a fan motor.

  In general, in a laser processing machine, the load on the laser side varies greatly depending on the material of the workpiece, the plate thickness, the processing speed, the processed surface roughness, and the like. Therefore, the cooling device that supplies (circulates) the coolant to the laser processing machine is required to have a cooling performance that can sufficiently follow such load fluctuations, and in particular, such as a mirror that greatly affects the processing accuracy. In order to ensure the thermal stability of the optical parts and avoid the deterioration of the processing quality, a high degree of precision cooling accuracy with little temperature fluctuation is required.

Conventionally, a cooling device disclosed in Japanese Patent Application Laid-Open No. 2001-74318 is known as a cooling device for such applications. The cooling device includes a refrigeration unit, a cooling water supply unit, and a control system, and the refrigeration unit includes a compressor, a condenser, an electronic expansion valve, a heat exchanger, and an accumulator, thereby constituting a refrigeration cycle in which refrigerant circulates. The temperature of the cooling water is controlled by varying the rotation frequency of the compressor within a certain range by the inverter. In addition, the condenser is provided with a blower for air-cooling the condenser, and this blower is connected to an inverter. When the refrigerant pressure on the discharge side of the condenser becomes high, the rotational frequency of the blower is increased, and the refrigerant pressure If it becomes low, inverter control which lowers the rotation frequency of a fan is performed.
JP 2001-74318 A

  However, since the conventional cooling device described above requires a direct current motor and an inverter for controlling the direct current motor as a blower for air-cooling the condenser, there is a problem to be solved that causes a significant cost increase.

  That is, since the rotational frequency of the blower is variably controlled in accordance with the refrigerant pressure on the discharge side of the condenser, a fan motor capable of inverter control is required. In this case, an AC motor that is advantageous in terms of cost that can be driven by a commercial AC power supply has a different rotational speed depending on the power supply frequency (50 Hz / 60 Hz) in the region in which it is used. The difference in the power supply frequency cannot be ignored for this type of cooling device that requires a high degree of precision and cooling accuracy with a small amount of heat. Therefore, a DC motor and an inverter that do not cause a difference in cooling capacity depending on the power supply frequency are required. However, since both the DC motor and the inverter are expensive unit parts, there is a limit in realizing effective cost reduction.

  The object of the present invention is to provide a cooling device that solves the problems in the background art.

  In order to solve the above-described problems, the present invention uses an AC motor 2s as the fan motor 2 and supplies the AC motor 2s to the cooling device 1 having the air cooling fan 3 driven by the fan motor 2. The power supply frequency setting means M1 for determining the power supply frequency fs of the AC power supply 4 and the power supply setting for setting the data (Tc...) For determining the power supply required for the predetermined rotational speed Rv of the AC motor 2s for each power supply frequency fs. Supply power corresponding to the data (Tc...) Set in the supply power setting means M2 corresponding to the power supply frequency fs determined by the power supply frequency determination means M1 if the means M2 and the predetermined rotation speed Rv. Is provided with supply power control means M3 for applying to the AC motor 2s.

  In this case, it is desirable to apply the air cooling fan 3 to the condensing fan 3c used for cooling the condenser 5 in the refrigeration cycle C according to a preferred aspect of the invention. On the other hand, the power frequency discriminating means M1 detects the timing of the set voltage level (including 0) in the supplied AC power supply voltage Vi, and outputs a level detection signal St. The signal interval determining means M12 for detecting the power interval fs by detecting the signal interval Ts of St. Further, the supply power setting means M2 sets the OFF control time Tc with respect to the AC waveform Vw of the supply power as data for determining the supply power, corresponding to each power frequency fs, and for each of a plurality of different rotational speeds Rv. The database D can be configured. Further, the supply power control means M3 selects the OFF control time Tc from the supply power setting means M2 based on the power supply frequency fs determined by the power supply frequency determination means M1 and the designated rotation speed Rv, and the selected OFF control time. A function of controlling the AC waveform Vw to OFF by Tc can be provided.

  According to the cooling device 1 according to the present invention having such a configuration, the following remarkable effects can be obtained.

  (1) Even when the AC motor 2s is used for the air-cooling fan 3, the unit can be rotated at a predetermined rotational speed Rv... Without depending on the power source frequency fs of the AC power source 4, and thus expensive unit parts. This eliminates the need for DC motors and inverters. Therefore, an AC motor that is advantageous in terms of cost and simple control means can be used, and effective cost reduction can be realized without causing a difference in cooling capacity depending on the power supply frequency fs.

  (2) When applied to the condensing fan 3c used for cooling the condenser 5 in the refrigeration cycle C according to a preferred embodiment, both cost reduction and desirable air cooling control around the condenser 5 can be realized.

  (3) According to a preferred embodiment, the power frequency discriminating means M1 detects the timing of the set voltage level (including 0) in the supplied AC power supply voltage Vi and outputs the level detection signal St ... If the signal interval discriminating means M12 for detecting the signal interval Ts between the M11 and the level detection signal St... Is discriminated to determine the power source frequency fs, the power source frequency fs can be easily and reliably discriminated.

  (4) According to a preferred embodiment, the supply power setting means M2 uses the OFF control time Tc for the AC waveform Vw of the supply power as data for determining the supply power, corresponding to each power frequency fs, and a plurality of different rotations. If the database D set for each of the speeds Rv... Is configured, a relatively simple control system can be configured, which can contribute to further cost reduction.

  (5) According to a preferred embodiment, the supply power control means M3 selects the OFF control time Tc from the supply power setting means M2 based on the power supply frequency fs determined by the power supply frequency determination means M1 and the designated rotational speed Rv. If the function of controlling the AC waveform Vw to be OFF for the selected OFF control time Tc is provided, the designated rotational speed Rv... At each power supply frequency fs can be obtained easily and reliably.

  Next, the best embodiment according to the present invention will be given and described in detail with reference to the drawings.

  First, the configuration of the cooling device 1 according to the present embodiment will be specifically described with reference to FIGS. 1, 3, and 4.

  In FIG. 3, 1 shows the whole structure of the cooling device which concerns on this embodiment. The cooling device 1 includes a coolant tank 11 that stores the coolant L. The coolant tank 11 can be connected to an object to be cooled H such as a laser processing machine via a coolant supply line 12s and a coolant return line 12r. Further, in the middle of the coolant supply line 12s, the liquid feed pump 13 for supplying the coolant L stored in the coolant tank 11 to the object H to be cooled and the coolant L supplied by the liquid feed pump 13 are provided. A cooler (heat exchanger) 14 to be cooled is connected. Further, a liquid pressure meter 15 for detecting the pressure of the cooling liquid L and a liquid temperature sensor 16 for detecting the temperature of the cooling liquid L are attached to the cooling liquid supply line 12s, and the liquid supply line 17s is provided to the cooling liquid tank 11. , A drain line 17d, a liquid level gauge 18, a ball tap 19 and the like are provided.

  On the other hand, the cooler 14 is connected to a refrigeration cycle C that cools the coolant L flowing through the coolant supply line 12s by heat exchange. The refrigeration cycle C includes a compressor 20, a condenser 5, a refrigerant strainer 22, an electronic expansion valve 23, and the like as main functional units. The refrigerant inflow side of the cooler 14 is connected to the refrigerant outflow side of the electronic expansion valve 23. In addition to the connection, the refrigerant inflow side of the compressor 20 is connected to the refrigerant outflow side of the cooler 14. Thereby, the refrigerant circuit 24 in which the refrigerant circulates in the direction of the arrow Fc is configured. In addition, 27 is a bypass circuit connected between the refrigerant | coolant outflow side of the compressor 20, and the refrigerant | coolant outflow side of the electronic expansion valve 23, and this bypass circuit 27 is comprised by the serial circuit of the capillary tube 25 and the electromagnetic valve 26. FIG. The basic function of such a refrigeration cycle C is the same as that of a known refrigeration cycle.

  Further, the refrigerant circuit 24 in the refrigeration cycle C is provided with a low pressure switch 31, an intake temperature sensor 32, a condensation temperature sensor 33, an ambient temperature sensor 34, a high pressure switch 35, and a cooler inlet temperature sensor 36, respectively. In this case, the pressure switches 31 and 35 mainly function as protection switches. Further, the condenser 5 is a condensing fan 3 c (air cooling fan 3) that cools the condenser 5, and is driven by the fan motor 2. On the other hand, a DC motor 20 m is used to drive the compressor 20, and the DC motor 20 m is connected to the inverter 39. The sensors 32, the fan motor 2, the inverter 39, and the electronic expansion valve 23 and the electromagnetic valve 25 are connected to the controller 40, respectively. The controller 40 constitutes a main part of the control system K and has a function of controlling the entire cooling device 1 including the refrigeration cycle C.

  FIG. 4 shows a main configuration of the cooling device 1 according to the present embodiment. 4, the controller 40 includes a controller main body 41 using a microcomputer (microcomputer), an operation unit 42 using an operation panel connected to the controller main body 41, and a display unit 43 using a liquid crystal display panel. Prepare. Therefore, the controller main body 41 has a computer function with a built-in CPU 44 and memory 45, etc., executes various processing functions and control functions (sequence control) by a pre-stored control program, and meets communication functions and the like as required. It has various functions.

  A three-phase AC power supply (commercial power supply) 4 is input to the controller main body 41. In this case, one phase is used as a single phase of 200 volts. 2s is a single-phase AC motor used as the fan motor 2 described above. One connection terminal 46p is connected to the first line of the three-phase AC power supply 4, and the other connection terminal 46q is SSR (solid state). It connects to the output part of the controller main body 41 via a relay 47. As a result, the SSR 47 is connected to the second line of the three-phase AC power supply 4 inside the controller main body 41. Reference numeral 48 denotes an operating capacitor.

  FIG. 1 is a functional block diagram showing the main configuration of FIG. 3. The power source frequency discriminating means M 1 for discriminating the power source frequency fs of the three-phase AC power source 4 supplied to the AC motor 2 s and the AC motor 2 s are shown. Supply power setting means M2 for setting data (Tc...) For determining supply power required for the predetermined rotational speed Rv... For each power supply frequency fs, and if the predetermined rotational speed Rv. Supply power control means M3 is provided that supplies the AC motor 2s with supply power corresponding to the data (Tc...) Set in the supply power setting means M2 corresponding to the determined power frequency fs.

  In this case, the power frequency determining means M1 includes a voltage level detecting means M11 and a signal interval determining means M12. The voltage level detection means M11 detects a set voltage level (including 0) in the supplied AC power supply voltage Vi, that is, a zero cross point function that detects the timing of the zero cross point at which the zero level is reached and outputs a level detection signal St. Part 51. Further, the signal interval discriminating means M12 detects the signal interval Ts of the level detection signals St... Obtained from the zero cross detection function unit 51 with time, and the signal interval detected by the zero cross interval detection function unit 52 ( Period) A frequency discrimination function unit 53 that discriminates the power source frequency fs based on Ts, that is, discriminates whether the power source frequency fs is 50 Hz or 60 Hz. By configuring such a power supply frequency discriminating means M1, it is possible to easily and reliably discriminate the power supply frequency fs.

  The supplied power setting means M2 is a database in which the OFF control time Tc for the AC waveform Vw of the supplied power is set as data for determining the supplied power, corresponding to each power frequency fs, and set for each of a plurality of different rotational speeds Rv. D is provided. FIG. 5 shows the contents of the database D. As shown in FIG. 1-No. 13 steps up to 13 are set. No. 1 shows the data with the slowest rotation speed Rv. 13 is set to data with the fastest rotation speed Rv, that is, data for full rotation. FIG. 5 shows an excerpt of only some steps. 1 is a case where the rotational speed Rv is 294 rpm, and when the power supply frequency fs is 50 Hz, the OFF control time Tc is set to 7.29 ms, and at 60 Hz, the OFF control time Tc is set to 5.88 ms. . Similarly, no. 10 is the case where the rotational speed Rv is 735 rpm, and when the power supply frequency fs is 50 Hz, the OFF control time Tc is set to 5.79 ms, and at 60 Hz, the OFF control time Tc is set to 4.44 ms. . By configuring such supply power setting means M2, a relatively simple control system can be configured, which can contribute to further cost reduction.

  The supplied power control means M3 reads (selects) the OFF control time Tc from the database D based on the power supply frequency fs determined by the power supply frequency determination means M1 and the designated rotational speed Rv, and the read OFF control time Tc The drive signal generation function unit 54 generates a drive signal Sd from the level detection signal St obtained from the zero cross detection function unit 51, and the driver 55 controls the SSR 47 based on the drive signal Sd obtained from the drive signal generation function unit 54. . Thus, control is performed to turn off the AC waveform Vw for the OFF control time Tc. At the time of control, information related to the refrigerant pressure on the discharge side of the condenser 5 is given to the controller 40, and a rotation speed Rv corresponding to the information related to the refrigerant pressure is designated. By configuring such supply power control means M3, the designated rotation speed Rv at each power supply frequency fs can be obtained easily and reliably.

  Next, operation | movement (function) of the cooling device 1 which concerns on this embodiment is demonstrated with reference to FIGS.

  First, by operating the liquid feed pump 13, the coolant L stored in the coolant tank 11 is supplied to the object to be cooled H via the coolant supply line 12s, and the object to be cooled H is exchanged by heat exchange. The cooled coolant L is returned to the coolant tank 11 via the coolant return line 12r. At this time, the coolant L flowing through the coolant supply line 12 s is cooled by the cooler 14. That is, the coolant L flowing into the cooler 14 is cooled by heat exchange with the cooled refrigerant in the refrigeration cycle C. In FIG. 3, arrows Fw... Indicate the direction in which the coolant L flows.

  On the other hand, in the refrigeration cycle C, the refrigerant circulates in the refrigerant circuit 24 in the direction of the arrow Fc by the operation of the compressor 20, and the refrigerant is cooled by the refrigeration cycle C. Further, the temperature (liquid temperature) of the coolant L supplied to the object to be cooled H is detected by the liquid temperature sensor 16 and applied to the controller 40. As a result, the controller 40 gives a control command to the inverter 39 and controls the rotational speed of the DC motor 20m, thereby performing the foot-back control so that the liquid temperature becomes the set temperature.

  On the other hand, the rotational speed Rv of the condensing fan 3 c attached to the condenser 5 is controlled based on the refrigerant pressure on the discharge side of the condenser 5. In this case, the controller 40 increases the rotational speed Rv of the condensing fan 3c when the refrigerant pressure on the discharge side of the condenser 5 increases, and reduces the rotational speed Rv of the condensing fan 3c when the refrigerant pressure decreases. Take control. Note that the refrigerant pressure on the discharge side of the condenser 5 may be directly detected by a pressure sensor, or a physical quantity proportional to the refrigerant pressure, for example, the detection temperature of the condensation temperature sensor 33 or the detection temperature of the ambient temperature sensor 34 and the condensation. It may be detected indirectly from the difference in temperature detected by the temperature sensor 33 or the like, and information on the detected refrigerant pressure is given to the controller 40, whereby the rotational speed Rv of the condensing fan 3c is controlled. This control is the main operation of the cooling device 1 according to the present embodiment, and will be specifically described below.

  First, when power is supplied to the controller 40, the power frequency fs is determined simultaneously with the power supply. In this case, the AC power supply voltage Vi for one phase of the three-phase AC power supply 43 shown in FIG. 2A is applied to the zero cross detection function unit 51 shown in FIG. The zero-cross detection function unit 51 detects a zero-cross point (a point at which the AC voltage Vai becomes 0 level), and outputs a level detection signal St... Shown in FIG. Further, the zero-crossing interval detection function unit 52 detects the signal interval Ts of the level detection signals St... Obtained from the zero-crossing detection function unit 51 based on time and gives it to the frequency discrimination function unit 53. The frequency discriminating function unit 53 discriminates whether the power supply frequency fs is 50 Hz or 60 Hz from the signal interval (period) Ts detected by the zero cross interval detecting function unit 52. In this case, if the power supply frequency fs is 60 Hz, one cycle is 16.6 ms, the level detection signal St is generated every 8.3 ms, and if the power supply frequency fs is 50 Hz, one cycle is 20 ms, A level detection signal St... Is generated every 10 ms. Therefore, the power supply frequency fs can be easily and reliably determined by detecting the signal interval Ts. This determination process is performed when power is supplied to the controller 40. If the determination process is completed, the determination result is fixed until the next power supply.

  On the other hand, as described above, since the information related to the refrigerant pressure on the discharge side of the condenser 5 is given to the controller 40, the rotation speed Rv corresponding to the information related to the refrigerant pressure is specified at the start of the operation. The condensing fan 3c is controlled so as to achieve the rotated speed Rv. In this case, the supply power control means M3 reads (selects) the OFF control time Tc from the database D based on the determination result (power supply frequency fs) of the frequency determination function unit 53 and the designated rotational speed Rv, and generates a drive signal. It is given to the function unit 54. The drive signal generation function unit 54 is turned off at the timing of the rising edge of the level detection signal (pulse signal) St, as shown in FIG. Then, a drive signal Sd (pulse signal) that is turned on at the timing when the OFF control time Tc has elapsed from this point is generated. The drive signal Sd obtained from the drive signal generation function unit 54 is given to the driver 55, and the SSR 47 is controlled by the driver 55. That is, as shown in FIG. 2 (d), the AC waveform Vw is turned OFF for the time of the OFF control time Tc from the zero cross point, and the no-power period is set.

  For example, no. When the rotation speed Rv of 11 is designated, if the power supply frequency fs is 50 Hz, the OFF control time Tc is 5.22 ms, and if the power supply frequency fs is 60 Hz, the OFF control time Tc is 3.75 ms. Thus, the OFF control time Tc is set as different values for 50 Hz and 60 Hz, so that the supplied power is the same even if the power supply frequency fs is different, and the same rotation speed Rv (985 rpm) is obtained. The condensing fan 3c is No. at the start of operation (at startup). 13 is selected, and after full rotation for a certain time, the control operation is shifted to the designated rotational speed Rv.

  Thus, according to the cooling device 1 according to the present embodiment, even when the AC motor 2s is used for the air cooling fan 3, the predetermined rotation speed Rv is not affected by the power supply frequency fs of the AC power supply 4. Since it can be rotated by ..., a DC motor and an inverter which are expensive unit parts can be dispensed with. Therefore, an AC motor that is advantageous in terms of cost and simple control means can be used, and effective cost reduction can be realized without causing a difference in cooling capacity depending on the power supply frequency fs. In particular, since the present invention is applied to the condensing fan 3c used for cooling the condenser 5 in the refrigeration cycle C, it is possible to realize both cost reduction and desirable air cooling control around the periphery of the condenser 5.

  As described above, the best embodiment has been described in detail. However, the present invention is not limited to such an embodiment, and the detailed configuration, shape, quantity, and the like are within the scope not departing from the gist of the present invention. It can be changed, added, or deleted arbitrarily. For example, the case where the air cooling fan 3 is applied to the condensing fan 3c used for cooling the condenser 5 in the refrigeration cycle C is shown, but the air cooling fan 3 can be applied to various air cooling fans 3 in other uses. Further, although the case where the zero cross point in the AC power supply voltage Vi is detected and the level detection signal St... Is output is shown, the case where the timing of any set voltage level in the AC power supply voltage Vi is detected is not excluded. . Further, the supply power setting means M2 sets the OFF control time Tc for the AC waveform Vw of the supply power as data for determining the supply power, corresponding to each power frequency fs and for each of a plurality of different rotational speeds Rv. Although the case where the database D is used is shown, it does not exclude the case where it is obtained by an arithmetic expression or the OFF control time Tc is continuously varied. In addition, although the type shown in FIG. 3 was illustrated as the cooling device 1, this invention is applicable to various types of cooling devices other than illustration.

The functional block diagram which shows the principal part structure in the cooling device which concerns on the best embodiment of this invention, Timing chart of signals for explaining the operation of the main part of the cooling device, Overall configuration diagram of the cooling device, Main part configuration diagram of the cooling device, An explanatory diagram of a database provided in the cooling device,

Explanation of symbols

  1: cooling device, 2: fan motor, 2s: AC motor, 3: air cooling fan, 3c: condensing fan, 4: AC power supply, 5: condenser, C: refrigeration cycle, D: database, Rv: rotational speed, fs : Power supply frequency, M1: power supply frequency discrimination means, M2: supply power setting means, M3 supply power control means, M11: voltage level detection means, M12: signal interval discrimination means, Vi: AC power supply voltage, Vw: AC waveform, St : Level detection signal, Ts: Signal interval, Tc: OFF control time

Claims (5)

  In a cooling device having an air cooling fan driven by a fan motor, an AC motor is used as the fan motor, and a power frequency discriminating means for discriminating a power frequency of an AC power source supplied to the AC motor, a predetermined frequency of the AC motor Supply power setting means for setting data for determining the supply power required for the rotation speed for each power supply frequency, and the supply power corresponding to the power supply frequency determined by the power supply frequency determination means if a predetermined rotation speed is specified. A cooling apparatus comprising: a supply power control unit that applies supply power corresponding to data set in the setting unit to the AC motor.   The cooling device according to claim 1, wherein the air cooling fan is a condensing fan used for cooling a condenser in a refrigeration cycle.   The power frequency discriminating means detects the timing of a set voltage level (including 0) in the supplied AC power supply voltage and outputs a level detection signal, and detects the signal interval of the level detection signal The cooling apparatus according to claim 1, further comprising a signal interval determining unit that determines a power supply frequency.   The supply power setting means includes a database in which the OFF control time for the AC waveform of the supply power is set as data for determining the supply power, corresponding to each power frequency and set for each of a plurality of different rotation speeds. The cooling device according to claim 1.   The supply power control means selects an OFF control time from the supply power setting means based on the power supply frequency determined by the power supply frequency determination means and the specified rotation speed, and turns off the AC waveform for the selected OFF control time. The cooling device according to claim 4, further comprising a control function.

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