Environmental test equipment

Abstract

To provide an environment test device with which it is possible to suppress the excessive heating, etc., of a compressor motor.SOLUTION: Provided is an environment test device comprising a test chamber, heating means 8, and cooling means 7, and capable of creating a prescribed environment in the test chamber. The cooling means 7 includes a freezing circuit 21 having a compressor 35, a condenser 28, expansion means 38, and an evaporator 40, with a phase-changing coolant circuiting therein. The freezing circuit 21 includes a first bypass passage 42 that connects the discharge side of the condenser 28 and the suction side of the compressor 35, with first flowrate control means 51 provided on the first bypass passage 42, and has temperature measurement means 82 that measures the temperature of the compressor 35, and control means. The control means controls the inside of the test chamber to a prescribed environment, with the practical opening of the first flowrate control means 51 controlled in accordance with the detection value of the temperature measurement means 82.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an environmental test apparatus that can create a specific environment in a test chamber and expose a test object to the desired environment.

Background Art

[0002] An environmental test is known as a test for examining the performance and durability of products, parts, etc. The environmental test is carried out using equipment called an environmental test apparatus. Generally, an environmental test apparatus has a test chamber and an air-conditioning section. The air-conditioning section is equipped with air-conditioning equipment such as a blower, a heating device, and a cooling device. The test chamber and the air-conditioning section constitute, for example, a series of circulating air ducts. The air in the test chamber is introduced into the air-conditioning section, where the temperature and humidity are adjusted, and the adjusted air is returned to the test chamber, thereby creating a desired temperature environment and humidity environment in the test chamber.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The environmental test apparatus may be continuously operated for a long time. Also, during continuous operation, the cooling device of the environmental test apparatus may be operated under temporarily severe conditions. Therefore, in the environmental test apparatus of the prior art, the motor that drives the compressor may generate heat during operation, and there is a concern of causing burnout of the motor winding, reduction in the viscosity of the oil and early deterioration, and damage to the compression part caused by these, which is a factor reducing the reliability of the environmental test apparatus.

[0005] The present invention solves the above-described problems of the prior art, and an object thereof is to provide an environmental test apparatus capable of suppressing excessive heat generation of a motor of a compressor and the like.

Means for Solving the Problems

[0006] An aspect for solving the above-described problems is an environmental test apparatus having a test chamber for arranging an object to be tested, a heating means, and a cooling means, capable of creating a predetermined environment in the test chamber, wherein the cooling means includes a compressor, a condenser, an expansion means, and an evaporator, and has a refrigeration circuit in which a refrigerant undergoing a phase change circulates, the refrigeration circuit has a first bypass flow path connecting the discharge side of the condenser and the suction side of the compressor, and a first flow rate control means is provided in the first bypass flow path, and has a temperature measuring means for measuring the temperature of the compressor and a control means, and the control means controls the inside of the test chamber to a predetermined environment and controls the substantial opening degree of the first flow rate control means according to the detection value of the temperature measuring means. A specific embodiment for solving the above problems is an environmental test apparatus having a test chamber for arranging a test object, a heating means, and a cooling means, and capable of creating a predetermined environment in the test chamber. The cooling means has a refrigeration circuit in which a refrigerant that undergoes a phase change circulates, having a compressor, a condenser, an expansion means, and an evaporator. The refrigeration circuit has a first bypass flow path connecting the discharge side of the condenser and the suction side of the compressor, and a first flow rate control means is provided in the first bypass flow path. The apparatus also has a temperature measuring means for measuring the temperature of the compressor and a control means. The control means controls the test chamber to a predetermined environment and controls the substantial opening degree of the first flow rate control means according to the detected value of the temperature measuring means. When the temperature measuring means detects a high temperature, the environmental test apparatus is characterized in that the opening degree of the first flow rate control means is increased.

[0007] Here, "controlling the substantial opening degree of the first flow rate control means" means, for example, controlling the actual valve opening degree to increase or decrease by an actuator such as a motor, and controlling the opening and closing intervals or the opening and closing times of an on-off valve to change the time in the open state and the time in the closed state. The refrigeration circuit employed by the environmental test apparatus of this aspect has a first bypass flow path connecting the discharge side of the condenser and the suction side of the compressor, and a first flow rate control means is provided in the first bypass flow path. Therefore, when the first flow rate control means is opened, at least a part of the refrigerant condensed in the condenser is introduced into the compressor via the first bypass flow path. Here, the refrigerant passing through the first bypass flow path is a refrigerant in a liquid phase or a gas-liquid mixed state and retains a high cooling capacity. Therefore, when the first flow rate control means is opened and the refrigerant in the liquid phase or the gas-liquid mixed state is introduced into the compressor, the compressor is cooled by the cooling capacity of the refrigerant. In the environmental test apparatus of this aspect, it has temperature measuring means for measuring the temperature of the compressor, and the opening degree of the first flow control means is controlled according to the detected value of the temperature measuring means. Specifically, when the temperature of the compressor rises, the first flow control means opens or the opening degree of the first flow control means substantially expands, and the refrigerant flowing through the first bypass flow path is introduced into the compressor to cool the motor and the like.

[0008] In the above-described aspect, the compressor is a hermetic compressor in which a motor and compression means are built in a sealed container, lubricating oil is built in the sealed container, and it is desirable that the temperature measuring means is attached to an outer surface of the sealed container in a region where the lubricating oil is built in.

[0009] In a hermetic compressor, there is a correlation between the temperature of the internal lubricating oil and the heat generation of the motor. In the environmental test apparatus of this aspect, since the temperature measuring means is attached to an outer surface of the sealed container in a region where the lubricating oil is built in, the temperature and temperature change of the lubricating oil can be known by the temperature measuring means, and the heat generation situation of the motor can be accurately detected.

[0010] In the above-described aspect, the compressor is a hermetic compressor in which a motor and compression means are built in a sealed container, lubricating oil is built in the sealed container, the compressor has a refrigerant suction port into which the refrigerant is introduced, and it is desirable that the temperature measuring means is attached to an outer surface of the sealed container in a region on the side opposite to the refrigerant suction port with respect to a virtual plane A parallel to a vertical cross section of the refrigerant suction port and including the center of the sealed container and a virtual plane B including the center of the sealed container.

[0011] In the environmental test apparatus of this aspect, the temperature measuring means is parallel to a virtual plane A including the vertical cross-section of the refrigerant suction port, and is attached to a region on the side opposite to the refrigerant suction port with respect to a virtual plane B including the center of the sealed container. That is, in the environmental test apparatus of this aspect, the temperature measuring means is attached at a position far from the refrigerant suction port. Therefore, according to this aspect, the temperature measuring means is less likely to be affected by the cold and heat of the refrigerant introduced from the refrigerant suction port. Therefore, the temperature measuring means can more accurately detect the temperature of the compressor.

[0012] In the above-described aspect, it is desirable that the refrigeration circuit has a second bypass flow path connecting the discharge side of the condenser and the suction side of the compressor, and the second bypass flow path is provided with second flow control means whose opening degree substantially changes according to the temperature of the refrigerant introduced into the compressor.

[0013] The environmental test apparatus of this aspect has a second bypass flow path, and the opening degree of the second flow control means provided in the second bypass flow path substantially changes according to the temperature of the refrigerant introduced into the compressor. Specifically, when the refrigerant in a high-temperature state returns to the compressor, the second flow control means opens, or the opening degree of the second flow control means substantially expands, and the refrigerant flowing through the second bypass flow path is introduced into the compressor to cool the motor and the like.

[0014] In the above-described aspect, the refrigeration circuit may have a dual cooling structure including a primary-side refrigeration circuit and a secondary-side refrigeration circuit. The primary-side refrigeration circuit has a high-temperature-side compressor, a high-temperature-side condensation section, high-temperature-side expansion means, and the primary side of a cascade condenser sequentially piped in a loop to circulate a refrigerant that undergoes a phase change therein. The secondary-side refrigeration circuit may have a low-temperature-side compressor, the secondary side of the cascade condenser, low-temperature-side expansion means, and a low-temperature-side evaporator sequentially piped in a loop to circulate a refrigerant that undergoes a phase change therein.

[0015] The environmental test apparatus of this aspect is provided with a refrigeration circuit having a dual cooling structure. Generally, an environmental test apparatus equipped with a refrigeration circuit having a binary cooling structure can create a considerably low-temperature environment in the test chamber. However, on the other hand, the cooling means of the binary cooling structure may be in a severe operating condition. The environmental test apparatus of this embodiment is equipped with a refrigeration circuit having a binary cooling structure and can create a considerably low-temperature environment in the test chamber. Further, in the environmental test apparatus of this embodiment, since a refrigerant having an appropriate cooling capacity is introduced into the compressor and the motor is cooled, it is difficult for the motor to burn out or the like.

Effect of the Invention

[0016] In the environmental test apparatus of the present invention, a refrigerant having a cooling capacity is appropriately introduced into the compressor, and there is an effect that excessive heat generation of the motor of the compressor can be suppressed.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described. The environmental test apparatus 1 of this embodiment has a heat insulation tank 3 covered by a heat insulation wall 2 as shown in FIG. 1. And a test chamber 5 is formed in a part of the heat insulation tank 3. The test chamber 5 is a space for installing the object under test 100. The environmental test apparatus 1 further includes a humidifying device 6, a cooling device (cooling means) 7, a heating heater (heating means) 8, and a blower 10. The environmental test apparatus 1 has an air flow path 15 communicating with the test chamber 5, and the air flow path 15 is provided with the humidifying device 6, the cooling device 7, the heating heater 8, and the blower 10 described above. Also, a temperature sensor (in-tank temperature detection means) 12 and a humidity sensor 13 are provided on the outlet side of the air flow path 15. In the environmental test apparatus 1, the air conditioning device 17 is constituted by the members in the air flow path 15 described above, the temperature sensor 12, and the humidity sensor 13. The air conditioning device 17 is controlled by a control device (control means) 16. The environmental test apparatus 1 can create a desired temperature and humidity environment in the test chamber 5 by the air conditioning device 17 controlled by the control device 16. That is, the control device 16 controls the inside of the test chamber 5 to a predetermined environment.

[0019] The cooling device 7 employed in the environmental test apparatus 1 of this embodiment includes a refrigeration circuit 18 as shown in FIG. 2. Hereinafter, the refrigeration circuit 18 of the cooling device (cooling means) 7 will be described. The cooling device 7 has a two-stage cooling structure including a primary-side refrigeration circuit 20 and a secondary-side refrigeration circuit 21. The primary-side refrigeration circuit 20 is one in which the refrigerant discharge port 32 of the high-temperature-side compressor 25, the high-temperature-side condenser 26, the high-temperature-side expansion means 27, the primary-side flow path 30 of the cascade condenser 28, and the refrigerant suction port 33 of the high-temperature-side compressor 25 are sequentially piped in a loop. And a high-temperature-side refrigerant that undergoes a phase change is enclosed in the primary-side refrigeration circuit 20 described above. The primary-side refrigeration circuit 20 realizes a refrigeration cycle in the same manner as a known one.

[0020] The secondary-side refrigeration circuit 21 is one in which the refrigerant discharge port 73 of the low-temperature-side compressor 35, the secondary-side flow path 37 of the cascade condenser 28, the low-temperature-side expansion means 38, the low-temperature-side evaporator (cooler) 40, and the refrigerant suction port 75 of the low-temperature-side compressor 35 are sequentially piped in a loop. Note that the cascade condenser 28 functions as a condenser of the secondary-side refrigeration circuit 21. The low-temperature-side evaporator (cooler) 40 is installed in the air flow path 15 as shown in FIG. 1. The low-temperature side expansion means 38 is an expansion valve and can have its opening degree adjusted by an actuator such as a motor.

[0021] The low-temperature side refrigerant that undergoes a phase change is enclosed in the above-described secondary side refrigeration circuit 21. The refrigerant enclosed in the secondary side refrigeration circuit 21 can create a low temperature of, for example, -70°C. The secondary side refrigeration circuit 21 realizes a refrigeration cycle in the same manner as the known one. And similar to the known dual cooling structure, the refrigerant in the primary side refrigeration circuit 20 is evaporated in the primary side flow path 30 of the cascade condenser 28 of the primary side refrigeration circuit 20 to lower the temperature of the cascade condenser 28. The refrigerant passing through the cascade condenser (condenser) 28 of the secondary side refrigeration circuit 21 is condensed by the low temperature generated at this time.

[0022] The secondary side refrigeration circuit 21 also has three bypass flow paths 42, 43, and 45. The first bypass flow path 42 branches off between the cascade condenser (condenser) 28 and the low-temperature side expansion means 38 and connects between the low-temperature side evaporator 40 and the refrigerant suction port 75 of the low-temperature side compressor 35. That is, the first bypass flow path 42 is a flow path connecting the discharge side of the cascade condenser (condenser) 28 and the suction side of the low-temperature side compressor 35.

[0023] The first bypass flow path 42 is provided with the first bypass expansion means 51. The first bypass expansion means 51 is a control valve equipped with an actuator such as a motor and can have its opening degree arbitrarily changed by an electric signal. It is desirable that the first bypass expansion means 51 can also be in a fully closed state.

[0024] In this embodiment, temperature detection means 82 is attached to the low-temperature side compressor 35, and the control device 16 adjusts the opening degree of the first bypass expansion means 51 according to the detected temperature of the temperature detection means 82. Specifically, when the detected temperature of the temperature detection means 82 increases, the control device 16 increases the opening degree of the first bypass expansion means 51, and when the detected temperature decreases, the control device 16 decreases the opening degree. For example, the first bypass expansion means 51 is normally in a fully closed state and opens when the detected temperature of the temperature detection means 82 exceeds a certain threshold value. Then, as the detected temperature rises, the opening degree of the first bypass expansion means 51 increases.

[0025] Similar to the first bypass flow path 42, the second bypass flow path 43 branches off from between the cascade condenser 28 and the low-temperature side expansion means 38 and connects to the low-temperature side evaporator 40 and the refrigerant suction port 75 of the low-temperature side compressor 35. That is, the second bypass flow path 43 is a flow path that connects the discharge side of the cascade condenser 28 and the suction side of the low-temperature side compressor 35. The second bypass flow path 43 is provided with the second bypass expansion means 52.

[0026] The second bypass expansion means 52 is a so-called temperature type expansion valve. The temperature type expansion valve is also called a temperature automatic expansion valve or a heat-sensitive expansion valve and includes a temperature sensing cylinder 55. The temperature type expansion valve has a plunger inside, and the opening degree of the orifice changes according to the temperature of the temperature sensing cylinder 55 and the temperature near the outlet of the second bypass expansion means 52. That is, a charge medium is enclosed inside the temperature sensing cylinder 55, and the charge medium expands and contracts according to the temperature of the temperature sensing cylinder 55. Then, the pressure of the temperature sensing cylinder 55 acts on the plunger via a flange or the like, and as a result, a force acts on the plunger in the temperature type expansion valve according to the detected temperature of the temperature sensing cylinder 55. On the other hand, since the refrigerant pressure on the outlet side of the orifice is also configured to act on the plunger via a flange or the like, a force also acts on the plunger according to the refrigerant temperature on the outlet side of the orifice. And when the two are balanced, the orifice stops, so as a result, the second bypass expansion means 52 is controlled based on the temperature around the temperature sensing cylinder 55 and the temperature near the second bypass expansion means 52. And the opening degree of the second bypass expansion means 52 changes so that the difference between the temperature of the temperature sensing cylinder 55 and the temperature near the outlet of the second bypass expansion means 52 becomes a predetermined temperature.

[0027] It is also desirable that the expansion means 52 for the second bypass can also be brought into a fully closed state. For example, the expansion means 52 for the second bypass is normally in a fully closed state and opens when the detected temperature of the temperature sensing cylinder 55 exceeds a certain threshold value. Then, as the detected temperature rises, the opening degree gradually increases.

[0028] In this embodiment, as shown in FIG. 2, the temperature sensing cylinder 55 is disposed near the refrigerant suction port 75 of the low-temperature side compressor 35, and the temperature sensing cylinder 55 senses the temperature of the refrigerant introduced into the low-temperature side compressor 35. Accordingly, the opening degree of the expansion means 52 for the second bypass is adjusted according to the temperature of the refrigerant introduced into the low-temperature side compressor 35. Specifically, when the temperature of the refrigerant introduced into the low-temperature side compressor 35 rises, the opening degree of the expansion means 52 for the second bypass increases, and when the detected temperature decreases, the opening degree decreases.

[0029] In this embodiment, there is a branch portion 56 between the cascade condenser 28 and the low-temperature side expansion means 38, and further, the leading end thereof is branched into a first bypass flow path 42 and a second bypass flow path 43. Also, the flow path where the first bypass flow path 42 and the second bypass flow path 43 merge is connected to the flow path reaching between the low-temperature side evaporator 40 and the refrigerant suction port 75 of the low-temperature side compressor 35. The flow path configuration of the bypass flow path is not limited to the configuration of FIG. 2, and there may be a plurality of branch portions between the cascade condenser 28 and the low-temperature side expansion means 38, and one of the branch portions serves as the starting point of the first bypass flow path 42, and the other branch portion serves as the starting point of the second bypass flow path 43. The same applies to the end sides of the first bypass flow path 42 and the second bypass flow path 43. There are a plurality of merging portions between the low-temperature side evaporator 40 and the refrigerant suction port 75 of the low-temperature side compressor 35, and the first bypass flow path 42 is connected to one merging portion, and the second bypass flow path 43 is connected to the other merging portion.

[0030] Since the refrigerant flowing through the first bypass passage 42 and the second bypass passage 43 is in a liquid phase or a gas-liquid mixed state, it has sufficient cooling capacity. Therefore, the first bypass passage 42 and the second bypass passage 43 can function as refrigerant cooling means for reducing the temperature of the low-temperature side compressor 35.

[0031] The third bypass passage 45 branches off from between the cascade condenser 28 and the low-temperature side expansion means 38 and is a passage leading to the intermediate cooling port 47 of the low-temperature side compressor 35. The third bypass passage 45 is provided with a third bypass expansion means 58. The third bypass expansion means 58 is a control valve provided with an actuator such as a motor and capable of arbitrarily changing the opening degree by an electric signal. It is desirable that the third bypass expansion means 58 can also be in a fully closed state. The third bypass expansion means 58 is not limited to a configuration having a function of adjusting the opening degree, and may not have a function of adjusting the opening degree of the valve itself, such as a combination of a capillary tube and an electromagnetic valve. In this case, the refrigerant flow rate is adjusted by controlling the opening and closing interval of the electromagnetic valve. As a result, the opening degree of the third bypass expansion means 58 is substantially adjusted. The refrigerant flowing through the third bypass passage is also in a liquid phase or a gas-liquid mixed state and has sufficient cooling capacity.

[0032] The low-temperature side compressor 35 employed in the present embodiment is a hermetic compressor, and a compression mechanism (compression means) 71, a motor 72, and an oil pump (not shown) are built in the hermetic container 70 of the low-temperature side compressor 35. Then, power is supplied from a power supply unit (not shown) to the motor 72 in the hermetic container 70, and the motor 72 rotates in the hermetic container 70. A compression mechanism 71 is connected to the rotating shaft of the motor 72, and the compression mechanism 71 in the hermetic container 70 is driven by the rotation of the motor 72. The type of the compression mechanism 71 is not limited, and may be, for example, a reciprocating type, a rotary type, a scroll type, or the like. The high-temperature-side compressor 25, similar to the low-temperature-side compressor 35, has a compression mechanism (compression means), a motor, and an oil pump (not shown) built into its sealed container.

[0033] In the sealed container 70, a refrigerant suction port 75, a refrigerant discharge port 73, and an intermediate cooling port 47 are open. The refrigerant suction port 75 is a pipe connecting the inside and outside of the sealed container 70. The refrigerant discharge port 73 is a pipe connecting the discharge part of the compression mechanism 71 to the outside. The intermediate cooling port 47 is a pipe connecting the inside and outside of the sealed container 70 and is open near the outer part of the compression mechanism 71.

[0034] The refrigerant is introduced into the sealed container 70 from the refrigerant suction port 75. The refrigerant diffuses inside the sealed container 70. Then, by driving the motor 72, the compression mechanism 71 is driven to suck and compress the refrigerant inside the sealed container 70, and the refrigerant is discharged from the refrigerant discharge port 73. Also, the refrigerant introduced from the third bypass flow path 45 is injected into the compression mechanism 71 from the intermediate cooling port 47 to cool the compression mechanism 71.

[0035] Inside the sealed container 70, there is an oil tank part 81 as shown in FIG. 3, and lubricating oil 80 is stored in the oil tank part 81. Inside the sealed container 70, there is an oil pump (not shown). When the motor 72 rotates, the oil pump rotates to suck the lubricating oil 80 in the oil tank part 81 and supply the lubricating oil 80 to each part inside the sealed container 70. The lubricating oil 80 supplied to each part returns to the oil tank part 81. That is, the lubricating oil 80 circulates inside the sealed container 70.

[0036] In the low-temperature-side compressor 35 adopted in this embodiment, temperature detection means 82 is attached to the outer surface of the sealed container 70. The temperature detection means 82 is, for example, a thermistor or a thermocouple. The attachment position of the temperature detection means 82 is at a height corresponding to the oil tank part 81 in the height direction. That is, the attachment position of the temperature detection means 82 is the height at which the lubricating oil 80 accumulates in the sealed container 70.

[0037] Although the liquid level of the lubricating oil 80 changes by driving the oil pump, at least a part of the temperature detecting portion of the temperature detecting means 82 should be at a height equal to or lower than the height of the oil level (hereinafter referred to as the maximum height H) when the oil pump is stopped and most of the lubricating oil 80 has accumulated downward. A more desirable height is such that all of the temperature detecting portion of the temperature detecting means 82 is below the maximum height H. When the oil pump is driven, the oil level drops, and it is desirable that at least a part of the temperature detecting portion of the temperature detecting means 82 is at a height equal to or lower than the height of the oil level (hereinafter referred to as the minimum height L) when the oil pump is driven. A more desirable height is such that all of the temperature detecting portion of the temperature detecting means 82 is below the minimum height L.

[0038] Also, the mounting position of the temperature detecting means 82 is preferably in a region opposite to the refrigerant suction port 75 in the circumferential direction. That is, assuming a virtual plane A including the vertical plane C of the refrigerant suction port 75 as shown in FIGS. 3 and 4, the circumferential mounting position of the temperature detecting means 82 is preferably in a region opposite to the refrigerant suction port 75 with respect to a virtual plane B that is parallel to the virtual plane A and includes the center 76 of the sealed container 70. The virtual plane A is a plane that becomes a vertical plane when the low-temperature side compressor 35 is installed on a horizontal floor surface and includes the vertical plane C of the refrigerant suction port 75. The virtual plane B is a plane that becomes a vertical plane when the low-temperature side compressor 35 is installed on a horizontal floor surface, is parallel to the vertical plane C of the refrigerant suction port 75, and passes through the center 76 of the sealed container 70. The circumferential mounting position of the temperature detecting means 82 is preferably in a region opposite to the refrigerant suction port 75 with respect to the virtual plane B.

[0039] In other words, when the position of the refrigerant suction port 75 is regarded as 12 o'clock on a clock, it is preferably in the region from 3 o'clock to 9 o'clock. In terms of angles, with the position of the refrigerant suction port 75 as the origin, it is in the range of 90 degrees to 270 degrees. The more recommended range is the position from 5 o'clock to 7 o'clock. In terms of angle, with the position of the refrigerant suction port 75 as the origin, it is the range from 150 degrees to 210 degrees.

[0040] When the low-temperature side compressor 35 is driven, the lubricating oil 80 circulates in the sealed container 70 as described above. Since the lubricating oil 80 also flows into the motor 72, the temperature of the lubricating oil 80 has a high correlation with the temperature of the motor 72. Therefore, the temperature of the lubricating oil 80 reflects the temperature of the motor 72. In this embodiment, since the temperature detection means 82 is installed on the outer surface of the sealed container 70 at the height where the lubricating oil 80 accumulates, the temperature detection means 82 detects the temperature of the lubricating oil 80 in the sealed container 70. Since the temperature of the lubricating oil 80 reflects the temperature of the motor 72, the detected temperature of the temperature detection means 82 has a high correlation with the temperature of the motor 72.

[0041] In this embodiment, the position in the circumferential direction where the temperature detection means 82 is attached is the region on the opposite side of the refrigerant suction port 75. Therefore, the detected temperature of the temperature detection means 82 is hardly affected by the refrigerant introduced into the sealed container 70. That is, the refrigerant introduced into the sealed container 70 generally has a low temperature. Therefore, if the temperature detection means 82 is located close to the refrigerant suction port 75, there is a possibility of detecting a low temperature under the influence of the introduced refrigerant, and the correlation with the temperature of the motor 72 decreases. In this embodiment, since the attachment position of the temperature detection means 82 is away from the refrigerant suction port 75, it is hardly affected by the refrigerant, and a temperature highly correlated with the temperature of the motor 72 can be detected.

[0042] Next, the function of the cooling device 7 will be described. The cooling device 7 starts and operates the high-temperature side compressor 25 of the primary side refrigeration circuit 20 and the low-temperature side compressor 35 of the secondary side refrigeration circuit 21. In the primary-side refrigeration circuit 20, the refrigerant is compressed by the high-temperature-side compressor 25, and the refrigerant is cooled and condensed by the high-temperature-side condenser 26. Then, the liquefied refrigerant passes through the narrow gap of the high-temperature-side expansion means 27 and enters the primary-side flow path 30 of the cascade condenser 28 to vaporize, reducing the temperature of the cascade condenser 28. The refrigerant discharged from the primary-side flow path 30 of the cascade condenser 28 returns to the high-temperature-side compressor 25 and is compressed again.

[0043] In the secondary-side refrigeration circuit 21, the refrigerant is compressed by the low-temperature-side compressor 35, and the refrigerant is cooled and condensed by the secondary-side flow path 37 of the cascade condenser (condenser) 28. Then, the liquefied refrigerant passes through the narrow gap of the low-temperature-side expansion means 38 and enters the low-temperature-side evaporator (cooler) 40 to vaporize, reducing the temperature of the low-temperature-side evaporator (cooler) 40. The refrigerant discharged from the low-temperature-side evaporator (cooler) 40 returns to the low-temperature-side compressor 35 and is compressed again.

[0044] The cooling device 7 is controlled by the control device 16 and is operated so that the temperature in the test chamber 5 is maintained at the set temperature. In the present embodiment, the low-temperature-side expansion means 38 is controlled by the control device 16 so that the temperature in the test chamber 5 approaches the set temperature. That is, the opening degree of the low-temperature-side expansion means 38 increases when the difference between the temperature in the test chamber 5 and the set temperature is large, and the opening degree decreases when the temperature in the test chamber 5 approaches the set temperature and the refrigeration load decreases.

[0045] In the present embodiment, when the inside of the low-temperature-side compressor 35 becomes excessively high in temperature or there is a concern that it may become excessively high in temperature, refrigerant having a cooling capacity is supplied to the low-temperature-side compressor 35 from the first bypass flow path 42 or the second bypass flow path 43, preventing overload operation of the motor 72, burnout of the coil, decrease in viscosity of the lubricating oil, and deterioration of the lubricating oil.

[0046] The following two examples can be cited as the causes for the inside of the low-temperature-side compressor 35 to become excessively high in temperature. (1) In the case of overload operation The environmental test device 1 can create a high-temperature environment or a low-temperature environment in the test chamber 5. For example, when the control device 16 receives an instruction to change to a lower set temperature when the temperature in the laboratory 5 is high, the cooling device 7 is activated. And when the temperature in the laboratory 5 is rapidly decreased, the inside of the low-temperature side compressor 35 may become excessively hot. That is, since the temperature in the laboratory 5 is high, the liquid refrigerant introduced into the low-temperature side evaporator (cooler) 40 immediately vaporizes, and further, after the gas temperature of the refrigerant rises by receiving the heat of the laboratory 5, the refrigerant returns to the low-temperature side compressor 35. Therefore, the inside of the low-temperature side compressor 35 may become excessively hot.

[0047] (2) When the cooling load is small When the temperature in the laboratory 5 is stable in the low-temperature state and the cooling load becomes small, the opening degree of the low-temperature side expansion means 38 is narrowed by a signal from the control device 16, and the amount of refrigerant supplied to the low-temperature side evaporator (cooler) 40 decreases. As a result, the amount of cooling heat for cooling the low-temperature side compressor 35 decreases. On the other hand, since the motor 72 continues to rotate, the heat generated by the motor 72 is accumulated in the sealed container 70, and the temperature inside the low-temperature side compressor 35 rises. Here, the low-temperature state includes, for example, the range from -70°C to -40°C, -40°C to -20°C, or -20°C to +30°C.

[0048] Next, the functions of the first bypass flow path 42 and the second bypass flow path 43 will be described. (1) In the case of overload operation As described above, when in the state of overload operation, the refrigerant returns to the low-temperature side compressor 35 in a high-temperature state. In the cooling device 7 of the present embodiment, the temperature sensing cylinder 55 of the second bypass expansion means 52 is arranged near the refrigerant suction port 75 of the low-temperature side compressor 35, and the temperature sensing cylinder 55 senses the temperature of the refrigerant introduced into the low-temperature side compressor 35. When the temperature of the refrigerant returning to the low-temperature side compressor 35 becomes high, the temperature is detected by the temperature sensing cylinder 55, and the opening degree of the second bypass expansion means 52 becomes large. As a result, the opening degree of the second bypass expansion means 52 increases, the refrigerant having a cooling capacity flows through the second bypass flow path 43, and the refrigerant is introduced into the sealed container 70 to suppress the temperature rise of the low-temperature side compressor 35. When the opening degree of the second bypass expansion means 52 increases, there is no or only a small amount of refrigerant supplied from the first bypass flow path 42 to the low-temperature side compressor 35.

[0049] (2) When the cooling load is small As described above, when the temperature in the test chamber 5 is stable at a low temperature and the cooling load is small, the opening degree of the low-temperature side expansion means 38 becomes small. As a result, the amount of refrigerant returning from the low-temperature side evaporator (cooler) 40 to the low-temperature side compressor 35 is small, but the temperature of the returning refrigerant itself is low. In this case, the temperature detected by the temperature sensing cylinder 55 is low, and the second bypass expansion means 52 is in a state where the opening degree is small or remains closed. Therefore, the inflow of refrigerant from the second bypass flow path 43 into the sealed container 70 cannot be expected. In the environmental test apparatus 1 of the present embodiment, when the cooling load is small, instead of the second bypass flow path 43, refrigerant is introduced from the first bypass flow path 42 into the sealed container 70. That is, in the present embodiment, the temperature detection means 82 is attached to the outer surface of the sealed container 70, and the temperature detection means 82 substantially monitors the temperature of the lubricating oil 80 in the sealed container 70. When the temperature detection means 82 detects a high temperature, the control device 16 increases the opening degree of the first bypass expansion means 51. As a result, even when the temperature detected by the temperature sensing cylinder 55 is low and the second bypass flow path 43 is not opened, refrigerant having a cooling capacity flows through the first bypass flow path 42, and the refrigerant is introduced into the sealed container 70 to suppress the temperature rise of the low-temperature side compressor 35.

[0050] That is, in the environmental test apparatus 1 of the present embodiment, when the inside of the test chamber 5 is in a stable state, the control device 16 (control unit) controls the opening degree of the first bypass expansion means 51 according to the detection value of the temperature detection means 82. Here, as an example of the stable state, a state where the temperature inside the test chamber 5 has reached the set temperature or a predetermined allowable range of the set temperature is included. Further, as another example of the stable state, a state where the output value of the heater 8 calculated by the control device 16 or its change amount is within a predetermined range, a state where the cooling output value calculated by the control device 16 or its change amount is within a predetermined range, or a state where the opening degree of the low-temperature side expansion means 38 calculated by the control device 16 or its change amount is within a predetermined range is included.

[0051] As described above, when the cooling device 7 of the present embodiment is forced into an overload operation that rapidly drops the temperature inside the test chamber 5, the second bypass flow path 43 opens to suppress the temperature rise of the low-temperature side compressor 35. Further, when the amount of the refrigerant returning is small as in the case where the cooling load is small, the cooling device 7 of the present embodiment opens the first bypass flow path 42 to suppress the temperature rise of the low-temperature side compressor 35. As described above, in any aspect of the assumed usage state, the environmental test apparatus of the present embodiment suppresses an excessive temperature rise of the low-temperature side compressor 35, preventing an overload operation of the motor 72, burnout of the coil, a decrease in the viscosity of the lubricating oil, and deterioration of the lubricating oil.

[0052] Further, the environmental test apparatus 1 of the present embodiment has a third bypass flow path 45, and since the refrigerant is supplied from the third bypass flow path 45 to the intermediate cooling port 47 of the low-temperature side compressor 35, the inside of the sealed container 70 is also cooled by the refrigerant supplied from the intermediate cooling port 47.

[0053] The third bypass expansion means 58 of the third bypass flow path 45 substantially increases the opening degree when the load on the motor 72 increases.

[0054] The environmental test apparatus 1 shown in FIG. 1 is merely an example of the present invention, and the layout and the presence or absence of equipment are not limited. For example, there may be an air conditioner 17 below the laboratory 5. If it is solely for creating a temperature environment, the humidifying device 6 and the humidity sensor 13 may not be necessary.

[0055] The embodiments described above are mainly environmental test devices used for exposing test objects to high-temperature or low-temperature environments. However, the present invention is not limited to this type of environmental test device, and the present invention can also be applied to environmental test devices called thermal shock test devices and thermal cycle test devices.

[0056] In the embodiments described above, as the first flow rate control means, an electronic control valve whose opening degree can be arbitrarily changed by an electric signal is adopted. However, the present invention does not limit the first flow rate control means to an electronic expansion valve. For example, a combination of a throttling member such as a capillary tube and an on-off valve such as an electromagnetic valve may be used as the first flow rate control means. In this case, a configuration in which the substantial opening degree is controlled by controlling the time interval of opening and closing of the electromagnetic valve can be considered. A sub-bypass flow path in which a plurality of throttling members such as capillary tubes are arranged in parallel can be provided, and an on-off valve can be provided in each sub-bypass flow path to serve as the first flow rate control means. In this case, by changing the number of on-off valves in the open state, the substantial opening degree of the entire sub-bypass flow path is controlled. The same applies to the third flow rate control means, and it may be a combination of a throttling member such as a capillary tube and an on-off valve such as an electromagnetic valve, or one provided with a sub-bypass flow path in which a plurality of throttling members such as capillary tubes are arranged in parallel.

[0057] In the embodiments described above, in addition to the first bypass flow path 42, a second bypass flow path 43 and a third bypass flow path 45 are provided. However, the second bypass flow path 43 and the third bypass flow path 45 are not essential, and either one of the second bypass flow path 43 and the third bypass flow path 45 may be absent. Also, both the second bypass flow path 43 and the third bypass flow path 45 may be absent.

[0058] As described above, in the environmental test apparatus 1, when the inside of the test chamber 5 is in a stable state, the control device 16 (control means) controls the opening degree of the first bypass expansion means 51 according to the detected value of the temperature detection means 82. Here, a determination means for determining whether or not the inside of the test chamber 5 is in a stable state may be provided, and the opening degree of the first bypass expansion means 51 may be controlled according to the detected value of the temperature detection means 82 on the condition that the determination means determines that it is in a stable state. Also, the first bypass expansion means 51 may be operated without providing the determination means.

[0059] The attachment position of the temperature detection means 82 is desirably at a height corresponding to the oil tank portion 81 in the height direction and in a region on the opposite side of the refrigerant suction port 75 from the virtual plane B in the circumferential direction. However, the present invention does not limit the attachment position of the temperature detection means 82 to this position, and the temperature detection means 82 may be at any position.

[0060] The environmental test apparatus 1 described above employs a cooling device (cooling means) 7 having a two-stage cooling structure. However, the present invention is not limited to this configuration, and a cooling device (cooling means) having a single-stage cooling structure may be employed. A typical cooling device having a single-stage cooling structure has one compressor, one condenser, one expansion means, and one evaporator, and a refrigerant that undergoes a phase change circulates therein. The cooling device having a single-stage cooling structure adopting the present invention has a first bypass flow path connecting the discharge side of the condenser and the suction side of the compressor, and a first flow rate control means is provided in the first bypass flow path. A temperature measurement means is provided in the one compressor, and the substantial opening degree of the first flow rate control means is controlled according to the detected value of the temperature measurement means. Also, it is desirable that the cooling device having a single-stage cooling structure adopting the present invention includes a second bypass flow path and a third bypass flow path in addition to the first bypass flow path. Also, in the cooling device with a single-stage cooling structure adopting the present invention, it is desirable that the position where the temperature measuring means is attached to the compressor is the same as the position in the case of the low-temperature side compressor 35 of the cooling device (cooling means) 7 with a two-stage cooling structure in the present embodiment.

Explanation of Signs

[0061] 1 Environmental test device 5 Test chamber 7 Cooling device (cooling means) 16 Control device (control means) 18 Refrigeration circuit 20 Primary side refrigeration circuit 21 Secondary side refrigeration circuit 28 Cascade condenser (condenser) 35 Low-temperature side compressor 38 Low-temperature side expansion means 40 Low-temperature side evaporator (cooler) 42 First bypass flow path 43 Second bypass flow path 45 Third bypass flow path 45 Bypass flow path 51 First bypass expansion means (first flow rate control means) 52 Second bypass expansion means (second flow rate control means) 55 Thermosiphon 58 Third bypass expansion means 70 Sealed container 71 Compression mechanism (compression means) 72 Motor 73 Refrigerant discharge port 75 Refrigerant suction port 80 Lubricating oil 82 Temperature detection means (temperature measuring means) 100 Test object A Virtual plane B Virtual plane

Claims

1. An environmental test apparatus having a test chamber for placing a test object, heating means, and cooling means, capable of creating a predetermined environment in the test chamber, wherein the cooling means has a compressor, a condenser, expansion means, and an evaporator, and has a refrigeration circuit in which a refrigerant undergoing a phase change circulates, the refrigeration circuit has a first bypass flow path connecting the discharge side of the condenser and the suction side of the compressor, and first flow rate control means is provided in the first bypass flow path, and has temperature measuring means for measuring the temperature of the compressor and control means, wherein the control means controls the inside of the test chamber to a predetermined environment and controls the substantial opening degree of the first flow rate control means according to the detected value of the temperature measuring means, and when the temperature measuring means detects a high temperature, the opening degree of the first flow rate control means is increased. An environmental test apparatus characterized by this.

2. The compressor is a hermetic compressor having a motor and compression means built in a hermetic container, lubricating oil is built in the hermetic container, and the temperature measuring means is attached to the outer surface of the hermetic container in a region where the lubricating oil is built in. The environmental test apparatus according to claim 1, characterized by this.

3. The compressor is a hermetic compressor having a motor and compression means built in a hermetic container, lubricating oil is built in the hermetic container, and the compressor has a refrigerant suction port into which refrigerant is introduced, wherein the temperature measuring means is attached to the outer surface of the hermetic container in a region on the side opposite to the refrigerant suction port with respect to a virtual plane A parallel to a virtual plane B including the vertical cross section of the refrigerant suction port and including the center of the hermetic container. The environmental test apparatus according to claim 1, characterized by this.

4. The refrigeration circuit has a second bypass flow path connecting the discharge side of the condenser and the suction side of the compressor, and second flow rate control means whose opening degree substantially changes according to the temperature of the refrigerant introduced into the compressor is provided in the second bypass flow path. The environmental test apparatus according to claim 1, characterized by this.

5. The refrigeration circuit has a two-stage cooling structure including a primary refrigeration circuit and a secondary refrigeration circuit, wherein in the primary refrigeration circuit, a high-temperature side compressor, a high-temperature side condensation section, high-temperature side expansion means, and the primary side of a cascade condenser are sequentially piped in a loop, and a refrigerant undergoing a phase change is circulated therein. The secondary-side refrigeration circuit according to any one of claims 1 to 4, characterized in that a low-temperature-side compressor, the secondary side of a cascade condenser, low-temperature-side expansion means, and a low-temperature-side evaporator are sequentially and annularly piped, and a refrigerant that undergoes a phase change is circulated therein.

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