JP4336603B2 - Cooling device operation control method - Google Patents

Description

  The present invention relates to an operation control method for a cooling device that cools an object to be cooled by circulating a coolant cooled by a cooler connected to a refrigeration cycle to the object to be cooled.

  In general, in a laser processing machine, it is necessary to ensure thermal stability for optical components such as mirrors, which greatly affect the processing accuracy, and to avoid deterioration in processing quality. High cooling accuracy and cooling performance that can sufficiently follow relatively large load fluctuations due to workpiece material, plate thickness, machining speed, and machined surface roughness, etc. are required. Japanese Patent Laid-Open No. 9-134220 proposed a cooling device (temperature control method for a cooling device) that meets such requirements. In this cooling device, a liquid feed pump is connected to a supply port of a coolant tank that stores a coolant, and a coolant inlet of an object to be cooled such as a laser processing machine is connected to a discharge port of the liquid feed pump. A cooler is connected to the return port of the coolant tank, and the coolant outlet of the object to be cooled is connected to the inlet of the cooler.

  However, since this cooling device stores the cooled cooling liquid in the cooling liquid tank, there is an advantage that a cooling liquid with a stable temperature can always be supplied to the object to be cooled. Are limited, there is a problem to be solved such as a reduction in COP (coefficient of performance = cooling capacity / input power) of the refrigerant circuit, a relatively large pressure resistance required on the object to be cooled, The present applicant has already proposed a cooling device that has solved this problem in Japanese Patent Laid-Open No. 2003-329355.

The cooling device includes a cooling liquid tank that stores the cooling liquid returned from the object to be cooled, a liquid feeding pump that sends out the cooling liquid flowing out from the supply port of the cooling liquid tank, and a cooling liquid that is discharged from the liquid feeding pump. A cooler that cools the liquid by heat exchange and supplies it to the object to be cooled is provided. The temperature of the coolant flowing out of the cooler is detected by a temperature sensor, and the cooling temperature of the cooler is controlled based on the detected temperature. A control system, more specifically, a control system having an inverter control of the rotation frequency of the compressor in the refrigeration cycle for circulating the refrigerant in the cooler based on the temperature detected by the temperature sensor is provided.
JP-A-9-134220 JP 2003-329355 A

  However, the conventional operation control method for inverter-controlling the rotation frequency of the compressor in the refrigeration cycle of such a cooling device has the following problems to be solved.

  First, when cooling the condenser provided for the refrigeration cycle, the temperature of the refrigerant discharged from the condenser (condensed refrigerant temperature) is monitored, and if it is higher than the set value, the rotation frequency of the cooling fan that air-cools the condenser is set. Since the control is performed to increase the rotation frequency and decrease the rotation frequency when it is low, there is no problem when controlling the rotation frequency of the compressor by an inverter. In this case, since the refrigerant temperature fluctuates rapidly and becomes large, the temperature control for the coolant becomes unstable, and a highly accurate and stable cooling temperature cannot be obtained.

  Second, the inverter control of the compressor varies the rotation frequency of the compressor by a control signal given to the inverter circuit from the control unit, so there is a limit to the range of the rotation frequency that can be controlled, and usually 30 [ %] In the low load region below, inverter control becomes difficult. For this reason, in the low load region, the actual situation is that the hot gas bypass circuit is controlled by opening and closing, which causes a decrease in the overall operation efficiency, and there are difficulties in energy saving and controllability.

  An object of the present invention is to provide an operation control method for a cooling device that solves the problems existing in the background art.

  In order to solve the above-described problem, the operation control method of the cooling device 1 according to the present invention cools the coolant W by the cooler 3 connected to the refrigeration cycle 2 and supplies the cooled coolant W to the object to be cooled M. When the object to be cooled M is cooled by being circulated, the digital switching mechanism unit switches to a loaded state in which refrigerant compression is performed when the compressor motor 6 is operated or an unloaded state in which refrigerant compression is released when the compressor motor 6 is operated. Is provided with a refrigeration cycle 2 having a digitally controlled refrigerant compressor 8 provided with 7, and in advance, one or more temperature regions Za, Zb... With respect to the ambient temperature Tr that is the ambient temperature around the condenser 4 in the refrigeration cycle 2. For each temperature region Za, Zb..., With respect to the deviation Ec between the condensed refrigerant temperature Tc which is the temperature of the refrigerant K discharged from the condenser 4 and the ambient temperature Tr The subranges Txa, Txb,... Are set, and the ambient temperature Tr and the condensed refrigerant temperature Tc are detected during operation. The deviation Ec between the detected condensed refrigerant temperature Tc and the ambient temperature Tr is in the corresponding temperature region Za, Zb,. When the temperature is higher than the reference range Txa, Txb..., The cooling degree of the condenser 4 is increased, and when it is lower, the cooling degree is decreased.

  In this case, according to a preferred aspect of the invention, the cooling frequency of the condenser 4 can be applied to the rotational frequency f of the condenser fan 5 that air-cools the condenser 4.

  According to the operation control method of the cooling device 1 according to the present invention having such a method, the following remarkable effects are obtained.

  (1) Even when a refrigerant compressor having a steep fluctuation in refrigerant pressure and a large operating characteristic is used, the condensed refrigerant temperature Tc can always be stabilized within the reference ranges Txa, Txb, etc. Stable temperature control can be performed on the liquid W, and a highly accurate and stable cooling temperature can be obtained.

  (2) It has a digitally controlled refrigerant compressor 8 provided with a digital switching mechanism section 7 for switching to a loaded state in which refrigerant compression is performed during operation of the compressor motor 6 or an unloaded state in which refrigerant compression is released during operation of the compressor motor 6. Since the refrigeration cycle 2 is used, the control range can be greatly expanded. In particular, control is possible even in a low load region of 30% or less with respect to the maximum cooling capacity, which was the limit in the conventional inverter control, and since no inverter circuit is required, the overall operating efficiency is reduced. Thus, energy saving and controllability can be improved.

  (3) Digitally controlled refrigerant compression having a digital switching mechanism 7 that switches the refrigeration cycle 2 to a loaded state in which refrigerant compression is performed during operation of the compressor motor 6 or an unloaded state in which refrigerant compression is released during operation of the compressor motor 6 In particular, when the machine 8 is used, steep fluctuations in refrigerant pressure occur due to repeated loading and unloading conditions. However, the operation control method according to the present invention uses such a digitally controlled refrigerant compressor 8. It is an effective measure when used.

  (4) If the rotation frequency f of the condenser fan 5 that air-cools the condenser 4 is applied to the cooling degree of the condenser 4 according to a preferred aspect, the existing configuration is used as it is, and the control method is changed. It can contribute to ease of implementation and low cost.

  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 capable of performing the operation control method according to the present embodiment will be specifically described with reference to FIGS.

  In FIG. 2, 1 indicates a cooling device, and M indicates an object to be cooled such as a laser processing machine connected to the cooling device 1. The cooling device 1 is connected to the object to be cooled M, and the object to be cooled M can be cooled by circulating the coolant W through the object to be cooled M. The cooling device 1 includes a coolant tank 11 that stores the coolant W, a liquid feed pump 12 that supplies the coolant W stored in the coolant tank 11 to the object M to be cooled, and a coolant tank from the object M to be cooled. A cooler 3 such as a plate heat exchanger that cools the coolant W returned to 11, and a refrigeration cycle 2 that is connected to the cooler 3 and cools the coolant W passing through the cooler 3 by heat exchange; And a control system 13 that controls the entire cooling device 1.

  In this case, the cooling liquid tank 11 stores the cooling liquid W such as cooling water, and includes a liquid supply port, a drain port, a liquid level gauge, a ball tap, and the like which are not shown. Further, as shown in FIG. 2, a hydraulic pressure gauge 21, a liquid temperature sensor 22, a bypass valve 23, pipe joints 24 a and 24 b, etc. connected to the water supply path are provided between the coolant tank 11 and the object M to be cooled. .

  On the other hand, as shown in FIG. 2, the refrigeration cycle 2 includes a condenser 4, a refrigerant dryer 26, an electronic expansion valve 27, an accumulator 28, and a digital control refrigerant compressor 8 as main functional units. The refrigerant inflow side of the electronic expansion valve 27 is connected to the refrigerant inflow side, and the refrigerant inflow side of the accumulator 28 is connected to the refrigerant outflow side of the cooler 3. Thereby, a refrigerant circuit in which the refrigerant K circulates in the direction of the arrow Fk is configured. The basic function of the refrigeration cycle 2 is the same as a known refrigeration cycle.

  In addition, in the refrigeration cycle 2 shown in FIG. 2, 31 is a low pressure switch, 32 is a low pressure gauge, 33 is a suction temperature sensor, 34 is a high pressure switch, 35 is a clogging alarm pressure switch, 36 is a high pressure gauge, Reference numeral 37 denotes a condenser outlet temperature sensor, and 38 denotes an evaporator inlet temperature sensor. Each of these pressure switches 31... Mainly functions as a protection switch. Reference numeral 5 denotes a condenser fan for air-cooling the condenser 4, 40 denotes an inverter connected to the condenser fan 5, and 41 denotes an ambient temperature sensor.

  On the other hand, as shown in FIGS. 3 to 5, the digitally controlled refrigerant compressor 8 includes a refrigerant compression unit 16 having an orbiting scroll 17 and a fixed scroll 18 and is also loaded by displacing the fixed scroll 18 in the axial direction Fc. A digital switching mechanism 7 for switching to a state (see FIG. 3) or an unload state (see FIG. 4) is provided. As the digitally controlled refrigerant compressor 8 having such a function, a “scroll machine having a capacity adjusting mechanism” disclosed in Japanese Patent Application Laid-Open No. 8-33494 can be used.

  Next, the structure of the digital control refrigerant compressor 8 provided with such a digital switching mechanism part 7 is demonstrated with reference to FIGS. Reference numeral 45 denotes a compressor body. The compressor main body 45 includes a sealed casing 46, and a compressor motor 6 having a rotary shaft 6s protruding upward is built in a lower portion of the casing 46. A refrigerant compressor 16 and a digital switching mechanism 7 are disposed above the compressor motor 6. In this case, the upper space of the compressor motor 6 is partitioned into upper and lower spaces by a partition wall 48, and has a discharge chamber Co on the upper side of the partition wall 48 and a suction chamber Ci on the lower side. The casing 46 has a refrigerant discharge port 49 facing the discharge chamber Co and a refrigerant suction port 50 facing the suction chamber Ci on the peripheral surface of the casing 46.

  Further, a fixed support plate 51 is disposed inside the suction chamber Ci, and the orbiting scroll 17 is placed on the upper surface of the support plate 51, and the fixed scroll 18 is placed on the orbiting scroll 17 to compress the refrigerant. Part 16 is configured. In this case, the orbiting scroll 17 has the spiral blade 12f on the upper surface and the engaged portion 52 at the center of the lower surface. The engaged portion 53 is engaged with an engaging portion 53 at the upper end eccentric position of the rotating shaft 6s. Thereby, if the rotating shaft 6s rotates, the orbital scroll 17 turns on the orbit. On the other hand, the fixed scroll 18 is supported so as to be displaceable in the axial direction Fc by a plurality of guide posts 54 provided on the support plate 51, and the position in the direction perpendicular to the axial direction Fc is fixed. The fixed scroll 18 has a spiral wing 13f on the lower surface and a protruding portion 55 at the center of the upper surface. The projecting portion 55 reaches the discharge chamber Co through an insertion hole 48 s provided at the center of the partition wall 48. Inside the protruding portion 55, there is an air passage 55r for communicating the central space Pc existing below the fixed scroll 18 and the discharge chamber Co, and a ram portion 56 is integrally formed at the upper end of the protruding portion 55, The ram portion 56 is accommodated in a cylinder portion 57 attached to the upper surface of the casing 46. Thus, a cylinder chamber 57r is provided between the cylinder portion 57 and the ram portion 56. The ram portion 56 has a bleed hole 56s that allows the cylinder chamber 57r and the discharge chamber Co to communicate with each other.

  On the other hand, the cylinder chamber 57r and the refrigerant suction port 50 are connected by a communication pipe 58, and an electromagnetic valve 59 for opening and closing the communication pipe 58 is connected in the middle of the communication pipe 58, and between the electromagnetic valve 59 and the cylinder chamber 57r. A spare valve 60 that opens and closes the communication pipe 58 is connected to the communication pipe 58. The spare valve 60 may be an electromagnetic valve as illustrated or a manual valve. Reference numeral 61 denotes a discharge temperature sensor that detects the temperature of the refrigerant K discharged from the digital control refrigerant compressor 8. The refrigerant suction port 50 in the compressor main body 45 is connected to the refrigerant outlet side of the accumulator 28 via the series-connected check valve 14, and the refrigerant discharge port 49 in the compressor main body 45 is connected in series to the check valve. It is connected to the refrigerant inflow side of the condenser 4 via the valve 15.

  In addition, the control system 13 includes a control unit 65, and the control unit 65 can perform the operation control method according to the present embodiment. The control unit 65 mainly has a function of performing sequence control on the actuators of each unit based on detection results obtained from sensors such as temperature and pressure. Therefore, the liquid temperature sensor 22, the suction temperature sensor 33, the discharge temperature sensor 61, the ambient temperature sensor 41, the condenser outlet temperature sensor 37, the evaporator inlet temperature sensor 38, and the like are connected to the input port of the control unit 65, respectively. At the same time, the compressor motor 6, the electromagnetic valve 59, the spare valve 60, the inverter 40, the electromagnetic expansion valve 27, and the like of the compressor main body 45 are connected to the output port of the control unit 65, respectively. Furthermore, the control unit 65 has a computer function and a communication function that can execute various processes and controls.

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

  First, the operation (principle) of the digitally controlled refrigerant compressor 8 used in the cooling device 1 will be described with reference to FIGS. As described above, the digitally controlled refrigerant compressor 8 includes the refrigerant compression unit 16 having the orbiting scroll 17 and the fixed scroll 18, and displaces the fixed scroll 18 in the axial direction Fc, thereby operating the compressor motor 6. A digital switching mechanism 7 is provided for switching to a load state (FIG. 3) where refrigerant compression is sometimes performed or an unload state (FIG. 4) where refrigerant compression is released when the compressor motor 6 is operated.

  In the digitally controlled refrigerant compressor 8, the rotation shaft 6s is rotated by operating the compressor motor 6, and the engaging portion 53 at the eccentric position at the upper end of the rotation shaft 6s pivots around the rotation shaft 6s. To do. As a result, the engaged portion 52 that engages and follows the engaging portion 53 and the orbital scroll 17 also orbit on the orbit. On the other hand, since the fixed scroll 18 is fixed (regulated) at a position perpendicular to the axial direction Fc, the spiral wing 12f of the orbiting scroll 17 and the spiral wing 13f of the fixed scroll 18 are shown in FIG. Relative motion as shown in (b) is performed.

  On the other hand, the refrigerant K is supplied from the refrigerant suction port 50 to the suction chamber Ci. Now, as shown in FIG. 3, it is assumed that the plunger 59p of the electromagnetic valve 59 protrudes, that is, the communication pipe 58 is in a closed state. The spare valve 60 is set in an open state. In this state, since the internal pressure of the cylinder chamber 57r is higher than the internal pressure of the suction chamber Ci on the low pressure side, the urging force by a spring (not shown) that pushes up the ram portion 56 is overcome and the spiral blade 13f of the fixed scroll 18 , Press against the orbiting scroll 17. FIG. 3 shows this state.

  Therefore, if the relative position of the spiral wing 12f of the orbiting scroll 17 with respect to the spiral wing 13f of the fixed scroll 18 is in the state shown in FIG. 5A, the refrigerant K present in the suction chamber Ci follows the direction of the dotted arrow. It enters between the spiral wings 12f and 13f from the outside. When the orbiting scroll 17 orbits on the orbit and the relative position of the spiral blade 12f with respect to the spiral blade 13f is in the state shown in FIG. 5B, the refrigerant K that has entered between the spiral blades 12f and 13f is It is enclosed in a crescent-shaped sealed space Pm ... formed between 12f and 13f. As the orbiting scroll 17 rotates, the volume of the crescent-shaped sealed space Pm... Gradually decreases, the refrigerant K is compressed, and when the refrigerant K reaches the central space Pc, the pressure of the refrigerant K is increased. Become the maximum. Thereafter, the compressed refrigerant K in the central space Pc reaches the discharge chamber Co through the air passage 55 r and is discharged from the refrigerant discharge port 49. The distribution path of the refrigerant K at this time is indicated by a dotted arrow in FIG. Therefore, this state becomes a load state in which the refrigerant is compressed by the digitally controlled refrigerant compressor 8, and the output is 100%.

  On the other hand, it is assumed that the electromagnetic valve 59 is controlled and the communication pipe 58 is switched to the open state by retracting the plunger 59p as shown in FIG. In this state, the suction chamber Ci on the low pressure side and the cylinder chamber 57r communicate with each other through the communication pipe 58, and the internal pressure of the cylinder chamber 57r and the internal pressure of the suction chamber Ci become the same pressure. 56 is displaced upward. As a result, as shown in FIG. 4, the spiral wing 13 f of the fixed scroll 18 is separated from the orbiting scroll 17, and a gap G is generated between the orbiting scroll 17 and the fixed scroll 18. As a result, the refrigerant K is not compressed. The distribution path of the refrigerant K at this time is indicated by a dotted arrow in FIG. Therefore, this state becomes an unload state in which the refrigerant compression by the digital control refrigerant compressor 8 is released, and the output is 0 [%].

  FIG. 6 shows a valve control signal Sp applied to the electromagnetic valve 59. In FIG. 6, tr represents a control section (time) in the load state (100 [%] output state), tn represents a control section (time) in the unload state (0 [%] output state), Control of the digitally controlled refrigerant compressor 8 is performed by changing the load rate Rr (= Tr / (Tr + Tn)). As described above, the control for the digitally controlled refrigerant compressor 8 is digital control in which the time axis of the load state “1” and the unload state “0” is varied, and the conventional inverter control, that is, the rotation frequency (magnitude of the compressor) The control mode is fundamentally different from the analog control that can be varied).

  Next, the overall operation (usage method) of the cooling device 1 will be described. First, as shown in FIG. 2, the cooling device 1 is connected to an object to be cooled M via pipe joints 24 a and 24 b, and the coolant (cooling water or the like) W is accommodated in the coolant tank 11. . Accordingly, when the liquid feeding pump 12 is operated, the cooling liquid W in the cooling liquid tank 11 is sent out from the supply port 11s by the liquid feeding pump 12 and supplied to the object to be cooled M through the pipe joint 24a. Then, the object to be cooled M is cooled. On the other hand, the coolant W warmed by cooling (heat exchange) of the object to be cooled M is supplied to the cooler 3 through the pipe joint 24b. In the cooler 3, heat exchange is performed between the supplied coolant W and the coolant K cooled in the refrigeration cycle 2, and the coolant W is cooled by the coolant K. Then, the coolant W cooled by the cooler 3 is returned to the return port 11 r of the coolant tank 11 and stored in the coolant tank 11. In FIG. 2, the arrow Fw indicates the flow direction of the coolant W.

  On the other hand, the temperature (liquid temperature Tw) of the coolant W supplied to the object to be cooled M is detected by the liquid temperature sensor 22, and this detection signal is given to the controller 65. The control unit 65 controls the digital control refrigerant compressor 8 based on the detection signal, that is, performs digital control for opening and closing the electromagnetic valve 59 described above, and performs feedback control so that the liquid temperature Tw becomes the target temperature.

  Therefore, according to such a cooling device 1, the temperature control for the coolant W uses digital control that controls the time axis so that the digitally controlled refrigerant compressor 8 is in the loaded state or the unloaded state. The range can be expanded dramatically. In particular, control is possible even in a low load region of 30% or less with respect to the maximum cooling capacity, which was the limit in the conventional inverter control, and since no inverter circuit is required, the overall operating efficiency is reduced. Will improve dramatically. As a result, energy saving and controllability were improved, and improvement of about 65 [%] at maximum was achieved with respect to conventional inverter control.

  By the way, in the cooling device 1, the digital control which selectively switches on the time axis so that the digitally controlled refrigerant compressor 8 is in a load state (100 [%] output state) or an unload state (0 [%] output state). Therefore, the temperature of the coolant W flowing out of the cooler 3 has a large amplitude and fluctuates with a frequent cycle (control frequency) as shown by a temperature change characteristic Qs indicated by a virtual line in FIG. Therefore, in such a cooling device 1, when a configuration in which the cooler 3 is connected in front of the object to be cooled M as in JP-A-2003-329355, the coolant W cooled by the cooler 3 is used. Is supplied to the cooled object M as it is, and the cooling characteristic (behavior) of the cooler 3 directly affects the temperature of the coolant W. In particular, when the digital control frequency is high (the cycle is short), the liquid temperature is also averaged due to the responsiveness, but the cycle is set to be relatively long in consideration of energy saving and controllability. In such a case, the influence on the coolant W is increased. However, in the cooling device 1, the configuration of temporarily storing the coolant W in the coolant tank 11 is combined with the cooler 3 to which the refrigeration cycle 2 including the digitally controlled refrigerant compressor 8 is connected. 7 can be reliably averaged, and the above-described effect, that is, the basic operation effect that the overall operation efficiency is drastically improved and the energy saving and controllability is improved is shown by a solid line in FIG. Like the temperature change characteristic Ps, it is possible to obtain the cooling liquid W with high cooling accuracy and stable liquid temperature Tw.

  In addition, the digital switching mechanism 7 that has the refrigerant compression unit 16 using the orbiting scroll 17 and the fixed scroll 18 and that switches the fixed scroll 18 or the orbiting scroll 17 in the axial direction Fc to switch to the loaded state or the unloaded state. Since the digitally controlled refrigerant compressor 8 is used, the cooling device 1 that can perform the operation control method according to the present embodiment can be realized easily and at low cost with a relatively simple configuration (principle).

  The above description is the basic operation of the cooling device 1, but the cooling device 1 further has the following unique configuration and functions, and performs unique control.

  First, rapid fluctuations in the refrigerant pressure are reduced by the check valves 14 and 15 connected in series to the upstream side and the downstream side of the digitally controlled refrigerant compressor 8. The digital control refrigerant compressor 8 is switched to a load state (100 [%] output state) or an unload state (0 [%] output state) by the digital switching mechanism unit 7, whereby temperature control for the coolant W is performed. Done. In this case, when switching from the load state to the unload state or from the unload state to the load state, the refrigerant pressure fluctuates abruptly, and this fluctuation frequently occurs. Therefore, the pressure gauges 32 and 36 in the refrigerant circuit, etc. Inconveniences such as shortening of the service life of the parts used, and deterioration of detection accuracy of the temperature sensors 61, 37, etc. occur. Therefore, in order to eliminate this problem, check valves 14 and 15 are connected in series on the upstream side and the downstream side of the digitally controlled refrigerant compressor 8 to reduce sudden fluctuations in the refrigerant pressure. As a result, the refrigerant pressure and the refrigerant temperature can be stabilized, and the service life of the parts used in the refrigerant circuit can be extended, and further, the detection accuracy can be improved and stabilized.

  On the other hand, by the inverter control of the condenser fan 4 that air-cools the condenser 4 by the operation control method according to the present embodiment, the temperature of the refrigerant K discharged from the condenser 4 (condensed refrigerant temperature Tc) is stably maintained, The control accuracy with respect to the cooling temperature of the object to be cooled M can be secured. That is, when the digitally controlled refrigerant compressor 8 is used, the refrigerant K flows or stops, so that the pressure fluctuation (temperature fluctuation) of the refrigerant K is steep and large as in the temperature change characteristic Qs shown in FIG. However, by controlling so that the condensed refrigerant temperature Tc detected from the condenser outlet temperature sensor 37 is kept stable, the cooling temperature of the object to be cooled M can be stabilized.

  Normally, the condenser 4 is cooled by setting the basic rotation frequency of the condenser fan corresponding to the ambient temperature Tr to about three stages, and when the condensed refrigerant temperature Tc becomes equal to or higher than the set value, the basic rotation frequency one stage higher. Control to switch to. However, in such a control, the evaporative refrigerant temperature also fluctuates due to a change in the condensing refrigerant temperature Tc (supercooling degree) at the time of loading due to a change in the load rate Rr, so that the control over the cooling temperature of the object M to be cooled becomes unstable. Prone.

  Therefore, one or more temperature regions Za, Zb... For the outside air temperature (ambient temperature Tr) around the condenser 4 in the refrigeration cycle 2 are set in advance, and the condenser 4 is set for each temperature region Za, Zb. A reference range Txa, Txb,... Is set with respect to a deviation Ec between the condensed refrigerant temperature Tc, which is the temperature of the refrigerant K discharged from the ambient temperature Tr, and the ambient temperature Tr, and the ambient temperature Tr and the condensed refrigerant temperature Tc are detected during operation. When the deviation Ec between the refrigerant temperature Tc and the ambient temperature Tr is higher than the reference range Txa, Txb... In the corresponding temperature range Za, Zb..., The rotational frequency f of the condenser fan 5 that air-cools the condenser 4 is increased. Thus, the degree of cooling of the condenser 4 is increased, and when it is low, the rotation frequency f of the condenser fan 5 is lowered to control the degree of cooling of the condenser 4.

  Hereinafter, a method for controlling the condenser fan 5 by the operation control method according to the present embodiment will be described with reference to the flowchart shown in FIG. 1 and the control characteristic diagram shown in FIG.

  First, as shown in FIG. 8, the temperature range with respect to the ambient temperature Tr is, for example, a first temperature range Za of 20 [° C.] or less, a second temperature range Zb of less than 30 [° C.] exceeding 20 [° C.], The third temperature region Zc is set to 30 [° C.] or more, and for each temperature region Za, Zb..., A reference range Txa, Txb with respect to the condensed refrigerant temperature Tc or a deviation Ec between the condensed refrigerant temperature Tc and the ambient temperature Tr. Set…. In FIG. 1, Txa is set to 25 [° C.] or more and less than 35 [° C.] as a reference range for the condensed refrigerant temperature Tc, and Txb is set to 2 as a reference range for the deviation Ec between the condensed refrigerant temperature Tc and the ambient temperature Tr. A case where the temperature is set to [° C.] or more and less than 7 [° C.] is exemplified.

  It is assumed that the cooling device 1 is now operating. During operation, the ambient temperature Tr and the condensed refrigerant temperature Tc are detected. At this time, if the ambient temperature Tr is in the third temperature region Zc of 30 [° C.] or higher, the control unit 65 controls the rotation frequency f of the condenser fan 5 to be maximum (steps S1 and S2). The maximum rotation frequency f is 60 [Hz].

  On the other hand, if the ambient temperature Tr is in the second temperature region Zb exceeding 20 ° C. and less than 30 ° C., a deviation Ec between the condensed refrigerant temperature Tc and the ambient temperature Tr is obtained, and the deviation Ec and the reference range Txb ( 2 [° C.] or higher and lower than 7 [° C.]). If the deviation Ec is in the range of 2 [° C.] or higher and less than 7 [° C.] set as the reference range Txb, the rotational frequency f is not changed (steps S3, S4, S5). When the deviation Ec is less than the reference range Txb, that is, less than 2 [° C.], control is performed to reduce the rotational frequency f of the condenser fan 5 (steps S3, S4, S6). Further, when the deviation Ec is not less than the reference range Txb, that is, not less than 7 [° C.], control is performed to increase the rotational frequency f of the condenser fan 5 (steps S3, S4, S5, S7).

  On the other hand, if the ambient temperature Tr is in the first temperature range Za of 20 [° C.] or lower, the relationship between the condensed refrigerant temperature Tc and the reference range Txa (25 [° C.] or higher and lower than 35 [° C.]) is determined. At this time, if the condensed refrigerant temperature Tc is in the range of 25 [° C.] or higher and lower than 35 [° C.], the rotation frequency f is not changed (steps S8, S9, S10). When the condensing refrigerant temperature Tc is less than 25 [° C.] set as the reference range Txa, control is performed to reduce the rotational frequency f of the condenser fan 5 (steps S8 and S9). Further, when the condensed refrigerant temperature Tc is equal to or higher than 35 [° C.] set as the reference range Txa, control is performed to increase the rotational frequency f of the condenser fan 5 (steps S8, S9, S10, S7). In this case, the increase / decrease of the rotation frequency f in the condenser fan 4 is controlled to be stepwise by dividing 1 to 60 [Hz] into a plurality of steps (n stages). Note that the rotation frequency f may be increased or decreased continuously (steplessly) around the reference range of the condensed refrigerant temperature Tc. Further, even if the reference range of the condensed refrigerant temperature Tc is replaced with the refrigerant condensation pressure (or discharge pressure), the same control can be performed and the same effect can be obtained. Although a method of monitoring the discharge pressure is possible, since the pressure fluctuation increases, the control tends to become unstable.

  According to such an operation control method, the condensed refrigerant temperature Tc is always stabilized within the reference ranges Txa, Txb,..., Even when a refrigerant compressor having steep fluctuations in refrigerant pressure and a large operating characteristic is used. be able to. Therefore, a stable cooling temperature with high accuracy can be obtained by performing stable temperature control on the coolant W. Moreover, if the rotational frequency f of the condenser fan 5 is applied as the degree of cooling of the condenser 4, it is possible to use the existing configuration as it is and to change the control method, thereby contributing to ease of implementation and low cost. . Further, the refrigeration cycle 2 is provided with a digital switching mechanism 7 that is provided with a digital switching mechanism 7 for switching to a loaded state in which refrigerant compression is performed when the compressor motor 12 is operated or an unloaded state in which refrigerant compression is released when the compressor motor 12 is operated. In particular, when the machine 8 is used, steep fluctuations in the refrigerant pressure occur due to repeated loading and unloading conditions. This is an effective measure when the digitally controlled refrigerant compressor 8 is used.

  On the other hand, even when the heat dissipation efficiency of the condenser 4 is reduced, that is, when the ambient temperature Tr (the outside air temperature around the condenser 4) is high, by reducing the load rate Rr of the digitally controlled refrigerant compressor 8, The operation of the cooling device 1 can be continued. In a conventional compressor using inverter control, if the ambient temperature Tr increases during operation (cooling operation), the heat dissipation efficiency of the condenser 4 decreases, the condensation pressure increases, and the discharge refrigerant temperature To of the compressor increases. To rise. In this case, in the conventional compressor, the operation is stopped in order to prevent overloading. However, in the cooling device 1, the use of the digitally controlled refrigerant compressor 8 allows the unload state even in the no-load state. Therefore, the ambient temperature Tr detected from the ambient temperature sensor 41 and the discharge refrigerant temperature To detected from the discharge temperature sensor 61 are monitored. When the ambient temperature Tr increases, the ambient temperature Tr is monitored. The load rate Rr is reduced, and the heat dissipation amount of the condenser 4 is reduced. Thereby, the rise in the pressure of the condenser 4 and the discharge refrigerant temperature To of the digital control refrigerant compressor 8 can be suppressed, and the operation can be continued even in an environment where the ambient temperature Tr is high.

  FIG. 9 shows an example of control characteristics in this case. In the figure, Tr indicates the ambient temperature, TA indicates the protective device operating temperature, and Ts indicates the threshold value. In addition, an ambient temperature of 40 [° C.] and a discharge refrigerant temperature of 120 [° C.] are set as judgment values, and if either temperature reaches the judgment value, control is performed to reduce the load rate Rr. In FIG. 9, if the ambient temperature Tr is 32 [° C.] lower than the determination value, the operation is continued at the load rate Rr of 100% unless the discharge refrigerant temperature To reaches the determination value. However, when the discharge refrigerant temperature To reaches the judgment value (120 [° C.]), the discharge refrigerant temperature To is lowered by performing control to gradually reduce the load rate Rr. On the other hand, if the ambient temperature Tr gradually rises and the control characteristic line in FIG. 9 rises to a temperature that intersects the threshold value Ts, control is performed to decrease the load rate Rr so that the intersecting load rate Rr is obtained. . For example, in FIG. 9, when the ambient temperature Tr reaches 45 [° C.], control is performed to reduce the load rate Rr so that the load rate Rr becomes 70 [%]. Further, when the ambient temperature Tr suddenly rises for some reason and reaches 50 [° C.], the load rate Rr cannot keep up, that is, in FIG. 9, the ambient temperature Tr is 50 [° C.]. In some cases, the load rate Rr must be 50%, but if it exceeds 60%, the control characteristic line will exceed the protection device operating temperature TA. Controls such as stopping operation by operating. Therefore, even when the ambient temperature Tr becomes high, the amount of heat released from the condenser 4 can be reduced by reducing the load rate Rr. Therefore, the discharge refrigerant temperature To of the condenser 4 and the digital control refrigerant compressor 8 is reduced. And the operation can be continued without stopping even at a high ambient temperature Tr.

  Further, the spare valve 60 is connected as a countermeasure against failure of the electromagnetic valve 59. Since the electromagnetic valve 59 is used for digital control, the ON / OFF operation is repeated at a considerable frequency and is a part whose durability is questioned. However, if this electromagnetic valve 59 breaks down, the digitally controlled refrigerant compressor 8 Is substantially inoperable. Therefore, the spare valve 60 is provided as a countermeasure. Now, when the electromagnetic valve 59 fails in the open state, the liquid temperature Tw detected by the liquid temperature sensor 22 rises and exceeds the upper limit value, so that it is detected as an abnormality. Therefore, the control unit 65 controls the spare valve 60 to the closed side and switches to the ON / OFF control of the compressor motor 6. On the other hand, when the electromagnetic valve 59 fails in the closed state, the liquid temperature Tw detected by the liquid temperature sensor 22 falls and exceeds the lower limit value, so that it is detected as abnormal. Therefore, the control unit 65 switches to ON / OFF control of the compressor motor 6. In this case, the failure is notified by turning on an alarm lamp or the like, but in any case, the operation can be continued temporarily.

  In addition, in FIG. 10, the cooling device 1 which concerns on the modified embodiment of this invention is shown. The cooling device 1 according to this modified embodiment is obtained by changing the connection part of the cooler 3 with respect to the cooling device 1 according to the embodiment shown in FIG. That is, in the cooling device 1 according to the modified embodiment, the cooling liquid W supplied from the cooling liquid tank 11 to the object M to be cooled is cooled by the cooler 3. In the cooling device 1 according to the modified embodiment, the cooling liquid W can be quickly cooled if the setting such as increasing the control frequency of digital control is performed on the cooling device 1 according to the embodiment shown in FIG. Or the cooling of the coolant W can be stopped quickly, and when the object to be cooled M is required to have a sophisticated and complicated cooling characteristic, or when a sudden temperature fluctuation occurs for some reason, it is appropriate. Control responsiveness can be ensured. As a result, accurate and flexible control can be performed, and advanced cooling characteristics corresponding to the object to be cooled M can be easily realized. In addition, in FIG. 10, the code | symbol 2m has shown the refrigeration cycle main body except the cooler 3 from the refrigeration cycle 2 shown in FIG. In addition, in FIG. 10, the same code | symbol is attached | subjected to FIG. 2 and an identical part, and while the structure is clarified, the detailed description is abbreviate | omitted.

  Although the best embodiment has been described in detail above, the present invention is not limited to such an embodiment, and departs from the gist of the present invention in the detailed configuration, shape, material, quantity, numerical value, and the like. It can be changed, added, or deleted as long as it is not. For example, the digitally-controlled refrigerant compressor 8 may be a digitally-controlled refrigerant compressor that includes the digital switching mechanism unit 7 in a refrigerant compressor other than that illustrated. Further, the set number and range of the temperature regions Za, Zb... Can be arbitrarily selected. Furthermore, although the rotation frequency f of the condenser fan 5 was applied to the cooling degree of the condenser 4, when the water cooling type cooling unit is used, a change in water temperature may be applied. In addition, the compressor motor 6 in the present invention is a concept that includes not only an electric motor but also all devices that are rotated by various types of power such as an internal combustion engine (engine).

The flowchart which shows the process sequence of the operation | movement control method which concerns on the best embodiment of this invention, A circuit configuration diagram of a cooling device capable of performing the operation control method, A cross-sectional configuration diagram in a load state showing a part of a digitally controlled refrigerant compressor included in the refrigeration cycle of the cooling device, A cross-sectional configuration diagram in an unloaded state showing a part of the digitally controlled refrigerant compressor, Action explanatory diagram showing the relationship between the start scroll and the fixed scroll in the digital control refrigerant compressor, Signal waveform diagram of valve control signal to be given to the digitally controlled refrigerant compressor, Liquid temperature change characteristic diagram with respect to time when using the cooling device, Control characteristic diagram showing the relationship of the rotation frequency of the condenser fan with respect to the ambient temperature when using the cooling device, Control characteristic diagram showing the relationship of the discharge refrigerant temperature with respect to the load rate when using the cooling device, The circuit block diagram of the cooling device which concerns on the modified embodiment of this invention,

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cooling device 2 Refrigeration cycle 3 Cooler 4 Condenser 5 Condenser fan 6 Compressor motor 7 Digital switching mechanism part 8 Digital control refrigerant compressor W Coolant M Cooled object Tr Ambient temperature Tc Condensation refrigerant temperature K Refrigerant Ec Condensation refrigerant Deviation between temperature and ambient temperature Za ... Temperature range

Claims (2)

  In the operation control method of the cooling device that cools the coolant by cooling the coolant with the cooler connected to the refrigeration cycle and circulating the cooled coolant to the material to be cooled. The refrigeration cycle includes the digital control refrigerant compressor provided with a digital switching mechanism that switches to a load state for performing refrigerant compression or an unload state for releasing refrigerant compression during operation of the compressor motor. One or two or more temperature ranges with respect to the ambient temperature that is the ambient temperature around the condenser are set, and for each temperature range, a standard for the deviation between the condensed refrigerant temperature that is the temperature of the refrigerant discharged from the condenser and the ambient temperature While setting the range, the ambient temperature and the condensed refrigerant temperature are detected during operation, and the detected condensed refrigerant temperature and the ambient temperature are detected. Operation control of a cooling device, characterized in that when the temperature deviation is higher than the reference range in the corresponding temperature region, the cooling degree of the condenser is increased, and when the deviation is lower, the cooling degree is decreased. Method.   2. The operation control method for a cooling device according to claim 1, wherein the cooling degree of the condenser is a rotational frequency of a condenser fan for air-cooling the condenser.

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