JP2005282935A - Cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve energy saving characteristic and controllability by improving operation efficiency as a whole and to easily realize high cooling characteristic corresponding to a cooled object. <P>SOLUTION: This cooling device comprises a cooling liquid tank 2 for storing the cooling liquid W returned from the cooled object M, a liquid feed pump 3 for supplying the cooling liquid W stored in the cooling liquid tank 2 to the cooled object M, a cooling part 4 having a cooler 4c connected with a refrigerating cycle 8 comprising a digital control refrigerant compressor 7 mounted on a digital switching mechanism part 6, and cooling the cooling liquid W supplied to the cooled object M by heat exchanging, and a control system 9 for switching and controlling the digital switching mechanism part 6 on the basis of, at least, a temperature of the cooling liquid W supplied to the cooled object M and variably controlling the temperature of the cooling liquid W. The digital switching mechanism part 6 switches a loading state for compressing the refrigerant in operating a compressor motor 5, and an unloading state for releasing the compression of the refrigerant in operating the compressor motor 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cooling device that cools an object to be cooled by circulating a coolant 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 cooling device using the refrigeration cycle in which the rotation frequency of the compressor is inverter-controlled has the following problems to be solved.

  First, 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. %] 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.

  Secondly, since temperature control is performed by changing the rotation frequency of the compressor, there is a limit to ensuring accurate control responsiveness when cooling the coolant quickly or when cooling to the coolant is stopped quickly. is there. Therefore, accurate and flexible control cannot be performed when the object to be cooled requires sophisticated and complicated cooling characteristics or when a sudden temperature fluctuation occurs due to some cause. It is difficult to realize advanced cooling characteristics corresponding to

  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 problem, the present invention returns from the object to be cooled M when configuring the cooling device 1 that cools the object to be cooled M by circulating the coolant W to the object to be cooled M. The coolant is stored in the coolant tank 2 for storing the coolant W, the liquid feed pump 3 for supplying the coolant W stored in the coolant tank 2 to the object to be cooled M, and the compressor motor 5 during refrigerant operation. A cooler 4c connected to a refrigeration cycle 8 provided with a digitally controlled refrigerant compressor 7 provided with a digital switching mechanism section 6 for switching to an unloaded state in which refrigerant compression is released when the compressor motor 5 is in operation in the loaded state or A cooling unit 4 that cools the coolant W supplied to the object to be cooled M by heat exchange, and at least the digital switching mechanism 6 based on the temperature of the coolant W supplied to the object to be cooled M to control the coolant W Temperature Characterized by comprising a control system 9 to change control.

  In this case, according to a preferred aspect of the invention, the digitally-controlled refrigerant compressor 7 has the refrigerant compression unit 11 using the orbiting scroll 12 and the fixed scroll 13 and displaces the fixed scroll 13 or the orbiting scroll 12 in the axial direction Fc. And a digital switching mechanism 6 for switching to a loaded state or an unloaded state. Further, check valves 14 and 15 are connected in series on the upstream side and / or the downstream side of the digitally controlled refrigerant compressor 7.

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

  (1) The temperature control for the coolant W uses digital control that switches the digitally controlled refrigerant compressor 7 according to a time axis so as to be in a loaded state or an unloaded state, so that the control range can be dramatically 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.

  (2) Since it becomes possible to cool the coolant quickly or to stop cooling the coolant quickly, the cooling target M is required to have a sophisticated and complicated cooling characteristic or is sharp due to some cause. Even when temperature fluctuations occur, accurate control response can be ensured. Thereby, accurate and flexible control becomes possible, and advanced cooling characteristics corresponding to the object to be cooled M can be easily realized.

  (3) According to a preferred aspect, the refrigerant compression unit 11 using the orbiting scroll 12 and the fixed scroll 13 is provided, and the digital that switches the fixed scroll 13 or the orbiting scroll 12 in the axial direction Fc and switches to the loaded state or the unloaded state. If the digitally controlled refrigerant compressor 7 provided with the switching mechanism unit 6 is used, the target cooling device 1 can be realized easily and at low cost with a relatively simple configuration (principle).

  (4) According to a preferred embodiment, if the check valves 14 and 15 are connected in series on the upstream side and / or the downstream side of the digitally controlled refrigerant compressor 7, the refrigerant generated when switching to the loaded state or unloaded state. The refrigerant pressure and the refrigerant temperature can be stabilized by suppressing the pressure fluctuation.

  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.

  In FIG. 1, 1 indicates a cooling device according to the present embodiment, 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 2 that stores the coolant W returned from the object to be cooled M, a liquid feed pump 3 that supplies the coolant W stored in the coolant tank 2 to the object to be cooled M, It has a cooler 4c such as a plate heat exchanger connected to the refrigeration cycle 8, and controls the cooling unit 4 that cools the coolant W supplied to the object to be cooled M by heat exchange, and the overall control of the cooling device 1. A control system 9 is provided.

  In this case, the cooling liquid tank 2 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. 1, a hydraulic pressure gauge 21, a liquid temperature sensor 22, a bypass valve 23, pipe joints 24a and 24b, etc. connected to the water supply path are provided between the coolant tank 2 and the object M to be cooled. .

  On the other hand, the cooling unit 4 includes a cooler 4c and a refrigeration cycle 8 connected to the cooler 4c. Thereby, in the cooler 4c, heat exchange between the refrigerant K and the coolant W of the refrigeration cycle 8 is performed, and the coolant W is cooled. As shown in FIG. 1, the refrigeration cycle 8 includes a condenser 25, a refrigerant dryer 26, an electronic expansion valve 27, an accumulator 28, and a digital control refrigerant compressor 7 as main functional units, and the refrigerant flow into the cooler 4c. The refrigerant outflow side of the electronic expansion valve 27 is connected to the side, and the refrigerant inflow side of the accumulator 28 is connected to the refrigerant outflow side of the cooler 4c. 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 8 is the same as that of a known refrigeration cycle.

  In addition, in the refrigeration cycle 8 shown in FIG. 1, 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 39 denotes a condenser fan for cooling the condenser 25 by air, 40 denotes an inverter connected to the condenser fan 39, and 41 denotes an ambient temperature sensor.

  On the other hand, as shown in FIGS. 2 to 4, the digitally controlled refrigerant compressor 7 includes a refrigerant compression unit 11 having an orbiting scroll 12 and a fixed scroll 13 and is loaded by displacing the fixed scroll 13 in the axial direction Fc. A digital switching mechanism 6 for switching to a state (see FIG. 2) or an unloading state (see FIG. 3) is provided. As the digitally controlled refrigerant compressor 7 having such a function, a “scroll machine having a capacity adjusting mechanism” disclosed in Japanese Patent Laid-Open No. 8-334940 can be used.

  Next, the structure of the digital control refrigerant compressor 7 provided with such a digital switching mechanism part 6 is demonstrated with reference to FIGS. Reference numeral 45 denotes a compressor body. The compressor main body 45 includes a hermetically sealed casing 46, and a compressor motor 5 having a rotary shaft 5s protruding upward is built in a lower portion of the casing 46. In addition, a refrigerant compressor 11 and a digital switching mechanism 6 are disposed above the compressor motor 5. In this case, the upper space of the compressor motor 5 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 12 is placed on the upper surface of the support plate 51, and the fixed scroll 13 is placed on the orbiting scroll 12 to compress the refrigerant. Part 11 is configured. In this case, the orbiting scroll 12 has a spiral blade 12f on the upper surface and an engaged portion 52 at the center of the lower surface. The engaged portion 53 is engaged with an engaging portion 53 that is located at the upper end eccentric position of the rotating shaft 5s. Thereby, if the rotating shaft 5s rotates, the orbital scroll 12 turns on the orbit. On the other hand, the fixed scroll 13 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 13 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 13 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 7. 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 25 via the valve 15.

  The control system 9 includes a control unit 65. The controller 65 mainly has a function of controlling 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 5, 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, operation | movement (usage method) of the cooling device 1 which concerns on this embodiment is demonstrated with reference to FIGS.

  First, the operation (principle) of the digitally controlled refrigerant compressor 7 used in the cooling device 1 according to this embodiment will be described with reference to FIGS. As described above, the digitally-controlled refrigerant compressor 7 includes the refrigerant compressor 11 having the orbiting scroll 12 and the fixed scroll 13, and the operation of the compressor motor 5 is performed by displacing the fixed scroll 13 in the axial direction Fc. A digital switching mechanism 6 is provided for switching to a load state (FIG. 2) where refrigerant compression is sometimes performed or an unload state (FIG. 3) where refrigerant compression is released when the compressor motor 5 is operated.

  In the digitally controlled refrigerant compressor 7, the rotating shaft 5s rotates by operating the compressor motor 5, and the engaging portion 53 at the upper end eccentric position of the rotating shaft 5s is swiveled around the rotating shaft 5s. To do. As a result, the engaged portion 52 that engages and follows the engaging portion 53 and the orbital scroll 12 also orbit on the orbit. On the other hand, since the fixed scroll 13 is fixed (regulated) at a position perpendicular to the axial direction Fc, the spiral wing 12f of the orbiting scroll 12 and the spiral wing 13f of the fixed scroll 13 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. 2, 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 13 , Press against the orbiting scroll 12. FIG. 2 shows this state.

  Therefore, if the relative position of the spiral blade 12f of the orbiting scroll 12 with respect to the spiral blade 13f of the fixed scroll 13 is in the state shown in FIG. 4A, the refrigerant K present in the suction chamber Ci is along the direction of the dotted arrow. It enters between the spiral wings 12f and 13f from the outside. When the orbiting scroll 12 orbits on the orbit and the relative position of the spiral blade 12f with respect to the spiral blade 13f reaches the state shown in FIG. 4B, 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. Then, as the orbiting scroll 12 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 becomes 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 flow 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 7, 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, the spiral wing 13 f of the fixed scroll 13 is separated from the orbiting scroll 12 as shown in FIG. 3, and a gap G is generated between the orbiting scroll 12 and the fixed scroll 13. 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 7 is released, and the output is 0 [%].

  FIG. 5 shows a valve control signal Sp applied to the electromagnetic valve 59. In FIG. 5, tr indicates a control section in the load state (100 [%] output state), and tn indicates a control section in the unload state (0 [%] output state), and the cooling according to the present embodiment. Control of the digitally controlled refrigerant compressor 7 used in the apparatus 1 is performed by changing the load rate Rr (= Tr / (Tr + Tn)). As described above, the control for the digital control refrigerant compressor 7 used in the cooling device 1 according to the present embodiment is a 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 control form is fundamentally different from the analog control that varies the rotation frequency (size) of the compressor.

  Next, the overall operation (usage method) of the cooling device 1 will be described. First, as shown in FIG. 1, the cooling device 1 is connected to an object to be cooled M via pipe joints 24 a and 24 b, and a cooling liquid (cooling water or the like) W is accommodated in the cooling liquid tank 2. . Thus, when the liquid feed pump 3 is operated, the coolant W in the coolant tank 2 is sent out from the supply port 2s by the liquid feed pump 3 and supplied to the cooler 4c. In the cooler 4 c, heat exchange is performed between the supplied coolant W and the coolant K cooled in the refrigeration cycle 8, and the coolant W is cooled by the coolant K. The coolant W cooled by the cooler 4c is supplied to the object to be cooled M through the pipe joint 24b, and the object to be cooled M is cooled. Then, the coolant W warmed by the cooling (heat exchange) of the cooled object M is returned to the return port 2r of the coolant tank 2 through the pipe joint 24a and stored in the coolant tank 2 as it is. In FIG. 1, an arrow Fw indicates the flow direction of the coolant W.

  On the other hand, the temperature (liquid temperature Tw) of the coolant W flowing out from the cooler 4 c 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 7 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 the cooling device 1 according to the present embodiment, for the temperature control on the coolant W, the digital control that controls the time axis so that the digitally controlled refrigerant compressor 7 is in the loaded state or the unloaded state. Therefore, 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. 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, the change of the liquid temperature Tw detected from the liquid temperature sensor 22 when the digital control refrigerant compressor 7 is digitally controlled is as shown in FIG. 6, and the liquid temperature Tw is finely controlled with high response. . Therefore, when the cooler 4c is connected in front of the object to be cooled M (immediately before), and the setting of increasing the control frequency of the digital control is performed, the coolant W can be cooled quickly or the coolant W Cooling can be stopped quickly, and accurate control responsiveness can be achieved even when the object to be cooled M requires sophisticated and complex cooling characteristics, or when sudden temperature fluctuations occur for some reason. Can be secured. 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, the digital switching mechanism 6 that has the refrigerant compression unit 11 using the orbiting scroll 12 and the fixed scroll 13 and switches the fixed scroll 13 or the orbiting scroll 12 in the axial direction Fc to switch to the loaded state or the unloaded state. Since the digitally controlled refrigerant compressor 7 is used, the target cooling device 1 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 according to the present embodiment, but the cooling device 1 further includes 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 digital control refrigerant compressor 7. The digitally controlled refrigerant compressor 7 is switched to a load state (100 [%] output state) or an unload state (0 [%] output state) by the digital switching mechanism unit 6, 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 7, respectively, to reduce rapid 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, the load rate Rr is monitored, and as shown in FIG. 7, when the load rate Rr falls below the set value Xc (illustration is 30 [%]), two control modes can be selected. Since the cooling device 1 uses the digitally controlled refrigerant compressor 7, unlike the conventional inverter control, the cooling device 1 is switched to a low load state of 30% or less, and further to an unload state even in a no-load state. This makes it possible to control the temperature. In this case, high accuracy and controllability with respect to temperature control can be obtained even in the low load region, but the compressor motor 5 is in an operating state, so that power consumption increases. Therefore, when the accuracy and controllability of temperature control are more important than ensuring energy saving in the low load region, the first control mode in which the switching control between the unload state and the load state is continuously performed can be selected. In addition, in the case where energy saving is more important than the accuracy and controllability of temperature control in the low load region, the second control mode for ON / OFF control of the compressor motor 5 can be selected. Note that the load [%] in FIG. 7 is the ratio of the maximum cooling capacity of the cooling device 1 to the amount of heat exchanged in the cooler 4c.

  Further, even when the heat dissipation efficiency of the condenser 25 is reduced, that is, when the ambient temperature Tr (the outside air temperature around the condenser 25) is high, by reducing the load rate Rr of the digitally controlled refrigerant compressor 7, The operation of the cooling device 1 can be continued. In a conventional compressor using inverter control, if the ambient temperature Tr rises during operation (cooling operation), the heat dissipation efficiency of the condenser 25 decreases, the condensation pressure increases, and the discharge refrigerant temperature To of the compressor increases. Rise. In this case, in the conventional compressor, the operation was stopped in order to prevent overload. However, in the cooling device 1 according to the present embodiment, the use of the digitally controlled refrigerant compressor 7 causes no load. However, since the temperature can be controlled by switching to the unloaded state, 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, and the ambient temperature Tr is high. When it becomes, the load rate Rr is lowered and the heat radiation amount of the condenser 25 is reduced. Thereby, the rise of the pressure of the condenser 25 and the discharge refrigerant temperature To of the digitally controlled refrigerant compressor 7 can be suppressed, and the operation can be continued even in an environment where the ambient temperature Tr is high.

  FIG. 8 shows an example of control characteristics in this case. In the figure, Tr represents the ambient temperature, TA represents the protective device operating temperature, and Ts represents the threshold value. Further, 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. 8, 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, when the ambient temperature Tr rises gradually and the control characteristic line in FIG. 8 rises to a temperature that intersects the threshold value Ts, control is performed to lower the load rate Rr so that the intersecting load rate Rr is obtained. . For example, in FIG. 8, 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. 8, 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 25 can be reduced by reducing the load rate Rr. Therefore, the discharge refrigerant temperature To of the condenser 25 and the digitally controlled refrigerant compressor 7 is reduced. And the operation can be continued without stopping even at a high ambient temperature Tr.

  On the other hand, by controlling the condenser fan 39 that cools the condenser 25 by air, the temperature of the refrigerant K discharged from the condenser 25 (condensed refrigerant temperature Tp) is kept constant, and the control accuracy with respect to the cooling temperature of the object to be cooled M is controlled. Was able to be secured. When the digitally controlled refrigerant compressor 7 is used, the refrigerant K flows or stops, so the temperature fluctuation of the refrigerant K increases, but the condensed refrigerant temperature Tp detected from the condenser outlet temperature sensor 37 is kept constant. By controlling so as to sag, the cooling temperature of the object M to be cooled can be stabilized. By the way, conventionally, the condenser 25 is cooled by setting the basic rotational frequency of the condenser fan corresponding to the ambient temperature Tr to about three stages, and when the condensed refrigerant temperature Tp becomes equal to or higher than the reference value, the basic rotational frequency one stage higher. However, when the condensing refrigerant temperature Tp (degree of supercooling) at the time of loading changes due to the change in the load rate Rr, the evaporating refrigerant temperature also changes accordingly. The control over the cooling temperature of the object M is likely to be unstable. Therefore, in the cooling device 1 according to the present embodiment, as shown in FIG. 9, the range of the ambient temperature Tr is, for example, a first temperature range from −10 ° C. to 20 ° C., 20 ° C. or more. The second temperature region is set up to 30 [° C.], and the reference value of the condensed refrigerant temperature Tp is set for each range. When the condensed refrigerant temperature Tp becomes higher than the reference value, the condenser fan 39 rotates. When the control for increasing the frequency is performed and the control frequency is lower than the reference value, the condensing refrigerant temperature Tp is always stabilized near the reference value by performing the control for decreasing the rotational frequency of the condenser fan 39. In FIG. 9, 30 [° C.] or more is the third temperature region, and is fixed at the maximum rotation frequency (60 [Hz]) of the condenser fan 39. In this case, the rotation frequency of the condenser fan 39 may be divided into a plurality of steps (n stages) from 1 to 60 [Hz], and may be increased or decreased in stages, or centered on the reference value of the condensed refrigerant temperature Tp. You may increase / decrease continuously (steplessly). Further, even if the reference value of the condensed refrigerant temperature Tp 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.

  Further, when the electronic expansion valve 27 is controlled, a target superheat degree based on the load rate Rr and the liquid temperature Tw of the digital control refrigerant compressor 7 is obtained in advance, and the opening degree of the electronic expansion valve 27 for obtaining the target superheat degree is obtained. N is set, and at the time of operation, the liquid temperature Tw and the load rate Rr are detected, and the electronic expansion valve 27 is controlled so that the opening degree N corresponds to the liquid temperature Tw and the load rate Rr. In this case, the opening degree N is set by the number of control pulses corresponding to the opening degree of the electronic expansion valve 27. The degree of superheat is a deviation between the inflow side refrigerant temperature and the outflow side refrigerant temperature with respect to the cooler (evaporator) 4c. In the case of the cooling device 1, the cooling temperature of the object to be cooled M is in a wide range, so that it is impossible to maintain an appropriate refrigeration cycle 8 even if the target superheat degree is set only with a single parameter. Therefore, as shown in FIG. 10, the target superheat degree is set by using the liquid temperature Tw and the load rate Rr, and the target superheat degree is changed by the liquid temperature Tw even at the same load rate Rr. Thereby, an appropriate refrigeration cycle 8 can be secured for any cooling temperature region of the object M to be cooled. And if the target superheat degree is calculated | required, the opening degree N of the electronic expansion valve 27 for obtaining this target superheat degree is set.

  In actual control of the electronic expansion valve 27, the preset opening degree N is quickly set from the liquid temperature Tw and the load rate Rr so that the temperature control is accurately performed. Conventionally, the opening degree N of the electronic expansion valve 27 has been a method of gradually adjusting the basic opening degree to the appropriate opening degree N while detecting the temperature of the refrigerant K after starting the refrigerant compressor. However, in this method, when the load fluctuation is large, the follow-up of the opening degree N of the electronic expansion valve 27 is delayed, and the temperature change of the object to be cooled M becomes large. Therefore, in the cooling device 1 according to this embodiment, as shown in FIG. 11, for example, the load rate Rr is 80 [%], the liquid temperature Tw is 20 [° C.], and the opening degree N of the electronic expansion valve 27 is 200 [ When the load decreases and the load rate Rr suddenly changes to 10 [%] during stable operation with the pulse], the opening degree N of the electronic expansion valve 27 is such that the load rate Rr is 10 [%] and the liquid temperature Tw is Transition was made unconditionally so that the opening degree (appropriate opening degree) N of 70 [pulses] set in advance corresponding to 20 [° C.] N was obtained. In order to increase the accuracy, in the case of the condensed refrigerant temperature Tp, the ambient temperature Tr, or the water cooling type, more effective control can be performed by adding the cooling water temperature or the like as a parameter. Further, if the opening degree is finely adjusted according to the refrigerant temperature or the refrigerant pressure, a more appropriate opening degree N can be set, and the opening degree N of the electronic expansion valve 27 can be instantaneously set even during a large load fluctuation. It can shift to the proper opening.

  On the other hand, 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 with considerable frequency, and it is a part whose durability is questioned. However, when the electromagnetic valve 59 breaks down, the refrigerant compressor 7 It becomes virtually 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 ON / OFF control of the compressor motor 5. 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 5. 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.

  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 7 may be a digitally-controlled refrigerant compressor that includes the digital switching mechanism 6 in a refrigerant compressor other than that illustrated. Moreover, although the case where the check valves 14 and 15 were respectively connected in series to the upstream side and the downstream side of the digital control refrigerant compressor 7 was shown, the check valve 14 or 15 is provided on either the upstream side or the downstream side. You may connect. In addition, the compressor motor 5 in the present invention is a concept that includes not only an electric motor but also all devices that are rotated by various powers such as an internal combustion engine (engine).

The circuit block diagram of the cooling device which concerns on the best embodiment of this invention, 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, Load rate vs. load characteristic diagram when using the same cooling device, Control characteristic diagram showing the relationship of the discharge refrigerant temperature with respect to the load rate 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, The characteristic diagram of the target superheat degree with respect to the load rate when the liquid temperature in the cooling device is used as a parameter, The characteristic diagram of the opening of the electronic expansion valve with respect to the load rate when the liquid temperature in the cooling device is used as a parameter,

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cooling device 2 Coolant tank 3 Liquid feed pump 4 Cooling part 4c Cooler 5 Compressor motor 6 Digital switching mechanism part 7 Digital control refrigerant compressor 8 Refrigeration cycle 9 Control system 11 Refrigerant compression part 12 Orbit scroll 13 Fixed scroll 14 Reverse Stop valve 15 Check valve M Object to be cooled W Coolant Fc Axial direction

Claims (3)

  In the cooling device that cools the object to be cooled by circulating the coolant to the object to be cooled, the coolant tank that stores the coolant returned from the object to be cooled, and the coolant stored in the coolant tank A liquid feed pump that supplies cooling liquid to the object to be cooled and a digital switching mechanism that switches to a loaded state in which refrigerant compression is performed during operation of the compressor motor or an unloaded state in which refrigerant compression is released during operation of the compressor motor are provided. A cooling unit connected to a refrigeration cycle including a digitally controlled refrigerant compressor, and a cooling unit that cools the coolant supplied to the object to be cooled by heat exchange, and at least a coolant supplied to the object to be cooled A cooling system comprising: a control system that variably controls the temperature of the coolant by switching and controlling the digital switching mechanism based on the temperature.   The digital control refrigerant compressor includes a refrigerant compression unit using an orbiting scroll and a fixed scroll, and a digital switching mechanism that switches the fixed scroll or the orbiting scroll in the axial direction to switch to the loading state or the unloading state. The cooling device according to claim 1, further comprising a portion.   The cooling device according to claim 1, wherein a check valve is connected in series to the upstream side and / or the downstream side of the digitally controlled refrigerant compressor.

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