Compressor and control method thereof

Abstract

A compressor (1) is provided with: a compressor main body (2) that sucks and compresses a gas to be compressed; heat exchangers (11, 12) that cool a cooling object while circulating the cooling object inside; a fan (14) that is driven by a fan motor (13) and blows cooling gas against the heat exchangers (11, 12) to exhaust heat therefrom; a temperature sensor (21) that detects a temperature of the cooling gas, i.e., a cooling gas initial temperature, which has not yet been subjected to heat exhaust by the heat exchangers (11, 12); and a control unit (5) that can set an upper limit frequency as an upper limit of a rotation frequency of the fan motor (13). The control unit (5) sets the upper limit frequency so that, at each cooling gas initial temperature detected by the temperature sensor (21), the upper limit frequency is a rotation frequency at which a current supplied to the fan motor (13) becomes a permissible current value or less.

Description

TECHNICAL FIELD

[0001] The present application relates to a compressor and a control method thereof. BACKGROUND

[0002] There is known a compressor provided with an air-cooled cooler (see, for example, Patent Literature 1) having a cooling fan having a fan motor capable of controlling the rotation speed of the fan and a heat exchanger (gas cooler or oil cooler) that performs heat exchange between a cooling target and outside air by driving the cooling fan.

[0003] In such an air-cooled cooler, in order to prevent overloading of the fan motor, a measure of setting an upper limit frequency so that the rotation speed of the fan motor does not rise above a certain value is generally taken. This is intended to prevent tripping of the fan motor (cut-off of power supply to the fan motor for fan motor protection) due to overcurrent (overload) by preventing over-rotation of the fan motor.

[0004] Further, in general, even if the rotation frequency of the fan motor is constant, the power for driving the fan is proportional to the air density, so the lower the ambient temperature of the place where the fan is installed, the higher the load on the fan motor. Also, the load on the fan motor varies due to changes in the flow path resistance from the suction to the discharge of the fan. Therefore, when the rotation speed of the fan motor is controlled, by setting the allowable current value of the fan motor, in the case where a current value exceeding the allowable value is output, the power supply to the fan motor is cut off in order to protect the fan motor.

[0005] PRIOR ART DOCUMENTS

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2005-61402 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] Although not shown in the above Patent Literature 1, it is more common in compressors to configure the heat exchanger and the fan to take away a certain amount of heat. The exchange heat quantity Q of the cooling air in the heat exchanger can be calculated using the following (1).

[0009] [Formula 1]

[0010] Q = p - c - V (T o - T a ) · · · (1)

[0011] In the above formula (1), p is the air density, c is the specific heat ratio, V is the cooling air amount, To is the cooling air temperature after passing through the heat exchanger, and Ta is the cooling air temperature before passing through the heat exchanger (ambient temperature). As can be well understood from the above formula (1), in the case where the cooling air temperature To after passing through the heat exchanger is constant and the ambient temperature Ta rises, in order to make the heat exchange amount constant, the cooling air amount V needs to be increased. Further, the cooling air temperature To after passing through the heat exchanger rises as the ambient temperature Ta rises, but is affected by the temperature of the cooling target. Therefore, in reality, the rise in the cooling air temperature To is smaller than the rise in the ambient temperature Ta. The cooling air amount V is proportional to the rotation frequency of the fan, so the upper limit of the rotation frequency of the fan is often determined in the condition where the ambient temperature Ta is the largest. On the other hand, the fan power for driving the fan is proportional to the cube of the rotation frequency, and the current value of the fan motor is proportional to the fan power, so an increase in the rotation frequency of the fan results in a large increase in the current value of the fan motor. Further, in the case where the ambient temperature falls, the air density increases and the fan power increases, so the fan motor can become overcurrent.

[0012] The present application has an object to prevent occurrence of overcurrent in a fan motor due to a change in ambient temperature in a compressor.

[0013] Means for solving the problem

[0014] The first technical solution of the present application provides a compressor, comprising: a compressor main body that sucks and compresses a gas to be compressed; a heat exchanger that cools a cooling target while allowing the cooling target to flow inside; a fan that is driven by a fan motor to flow cooling gas on the outer surface of the heat exchanger to perform heat dissipation; a temperature sensor that detects the temperature of the cooling gas that has not yet been subjected to heat dissipation by the heat exchanger, i.e., a cooling gas initial temperature; and a control unit that can set an upper limit frequency as a control upper limit of the rotation frequency of the fan motor; the control unit sets the upper limit frequency in such a manner that the current supplied to the fan motor becomes a permissible current value or less at each of the cooling gas initial temperatures detected by the temperature sensor.

[0015] Generally, even if the rotation frequency of the fan motor is constant, the power for driving the fan is proportional to the air density, so the lower the ambient temperature, the higher the load on the fan motor. The control unit sets the upper limit frequency of the fan motor so that it is a rotation frequency at which the current supplied to the fan motor becomes a permissible current value or less at each of the cooling gas initial temperatures detected by the temperature sensor. Therefore, overcurrent in the fan motor due to a change in ambient temperature can be prevented.

[0016] The aforementioned control section stores a relationship between the aforementioned cooling gas initial temperature and the aforementioned upper limit frequency, and the aforementioned relationship is set such that the lower the aforementioned cooling gas initial temperature, the lower the aforementioned upper limit frequency.

[0017] The aforementioned control section stores a relationship between the aforementioned cooling gas initial temperature and the aforementioned upper limit frequency, and the aforementioned relationship is set such that the aforementioned upper limit frequency continuously or stepwise decreases as the aforementioned cooling gas initial temperature decreases.

[0018] The aforementioned control section stores a relationship between the aforementioned cooling gas initial temperature and the aforementioned upper limit frequency, and the aforementioned relationship is set such that the aforementioned upper limit frequency is set in a manner that the aforementioned current supplied to the fan motor becomes a constant value at each of the aforementioned cooling gas initial temperatures.

[0019] The compressor can include a frame that houses the aforementioned compressor main body, the aforementioned fan, the aforementioned fan motor, and the aforementioned heat exchanger.

[0020] The aforementioned temperature sensor can be disposed at an air intake opening of the aforementioned frame, and measure a temperature of the aforementioned cooling gas taken in from the aforementioned air intake opening as the cooling gas initial temperature.

[0021] The aforementioned temperature sensor can be disposed on an upstream side of the aforementioned fan, and measure a temperature of the cooling gas sucked by the aforementioned fan.

[0022] The aforementioned temperature sensor can be disposed on a downstream side of the aforementioned fan until the aforementioned heat exchanger, and measure a temperature of the cooling gas ejected from the aforementioned fan.

[0023] The aforementioned compressed gas and the aforementioned cooling gas can be the same gas, and the aforementioned temperature sensor can be disposed in a suction flow path of the aforementioned compressor main body, and measure a temperature of the aforementioned same gas sucked into the aforementioned compressor main body from the aforementioned suction flow path.

[0024] The compressor can include a gas cooler that cools the ejected gas from the aforementioned compressor main body as the aforementioned cooling target, and the aforementioned gas cooler can include the aforementioned heat exchanger.

[0025] The compressor can include an oil cooler that cools oil supplied to the aforementioned compressor main body as the aforementioned cooling target, and the aforementioned oil cooler can include the aforementioned heat exchanger.

[0026] The second aspect of the present application provides a control method for a compressor, the compressor including: a compressor main body that sucks and compresses a gas to be compressed; a heat exchanger that cools a cooling target while allowing the cooling target to flow inside the heat exchanger; and a fan that is driven by a fan motor and causes cooling gas to flow on an outer surface of the heat exchanger to discharge heat from the heat exchanger; a temperature sensor that detects a temperature of the cooling gas that has not yet been subjected to heat discharge from the heat exchanger, i.e., a cooling gas initial temperature; and an upper limit frequency that is set as an upper limit of a rotation frequency of the fan motor in such a manner that the rotation frequency becomes lower than a current value that is supplied to the fan motor at each of the cooling gas initial temperatures detected by the temperature sensor.

[0027] Effects of Invention

[0028] According to the present application, overcurrent in the fan motor due to a change in ambient temperature in the compressor can be prevented. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a schematic system diagram of the compressor of the first embodiment of the present application.

[0030] Figure 2 is a block diagram for explaining a concept of control in the compressor of the first embodiment of the present application.

[0031] Figure 3 is a block diagram for explaining a concept of control in a conventional compressor.

[0032] Figure 4 is a schematic graph showing a relationship between a cooling gas initial temperature and a fan upper limit frequency.

[0033] Figure 5 is a schematic system diagram of the compressor of the second embodiment of the present application.

[0034] Figure 6 is a schematic system diagram of the compressor of the third embodiment of the present application.

[0035] Figure 7 is a schematic system diagram of the compressor of the fourth embodiment of the present application.

[0036] Figure 8 is a schematic view showing a modification example with respect to a structure of an inside of a case.

[0037] Figure 9 is a schematic view showing a modification example with respect to a structure of an inside of a case.

[0038] Figure 10 is a schematic view showing a modification example with respect to a structure of an inside of a case. DETAILED DESCRIPTION

[0039] Embodiments of the present application will be described with reference to the accompanying drawings.

[0040] (First Embodiment)

[0041] With reference to Figure 1 The compressor 1 of the first embodiment has a compressor main body 2, an oil separation and recovery device 3, a tank 4, a controller (control unit) 5, and a frame 6 that houses them.

[0042] The compressor main body 2 is an oil-cooled screw compressor in the present embodiment. The compressor main body 2 has a pair of screw rotors 2b that are rotationally driven by a main motor 2a. The rotational speed of the main motor 2a is controlled by a main inverter 7. The rotor shafts 2c of the respective screw rotors 2b are rotatably supported by bearings 2d. Compressed gas (air in the present embodiment) that is sucked from a suction flow path 2g via a filter 2e and a suction valve 2f is compressed by the pair of screw rotors 2b and is ejected from a discharge port 2h. The compressed gas is not limited to air, and can be nitrogen or the like other than air. In the present specification, the gas that is sucked from the suction flow path 2g is referred to as "compressed gas" for convenience, and the gas that is ejected from the discharge port 2h is referred to as "ejected gas".

[0043] The oil separation and recovery device 3 is connected to the discharge port 2h of the compressor main body 2 via a gas flow path 8a, and is connected to a heat exchanger 11 included in a rear cooler, which is a gas cooler, via a gas flow path 8b. The ejected gas from the discharge port 2h of the compressor main body 2 is transported to the oil separation and recovery device 3 via the gas flow path 8a. The oil included in the ejected gas from the discharge port 2h of the compressor main body 2 is separated from the ejected gas by the oil separation and recovery device 3, and is accumulated in an oil accumulation portion 3a at the bottom of the oil separation and recovery device 3. The ejected gas from the oil separation and recovery device 3 is transported to the heat exchanger 11 via the gas flow path 8b, is cooled by the heat exchanger 11, and is then transported to a supply destination (not shown) via a gas flow path 8c.

[0044] The oil accumulation portion 3a of the oil separation and recovery device 3 is connected to a heat exchanger 12 included in an oil cooler via an oil flow path 9a. The oil of the oil accumulation portion 3a is transported to the heat exchanger 12 via the oil flow path 9a, is cooled by the heat exchanger 12, and is then supplied to a supply target, specifically, to the main motor 2a, the bearings 2d, and a rotor chamber 2j that houses the screw rotors 2b of the compressor main body 2, via an oil flow path 9b. The oil supplied to the main motor 2a and the bearings 2d eventually flows into the rotor chamber 2j. The oil that flows into the rotor chamber 2j is transported to the oil separation and recovery device 3 together with the ejected gas.

[0045] The controller 5 comprehensively controls the controllable elements of the compressor 1 including the fan inverter 15 based on the input from various sensors including the case intake temperature sensor 21 and the oil temperature sensor 22 described later and the instruction input by the higher-level control device or the operator.

[0046] In the case 6, there are provided an intake opening 6a for taking in the cooling gas and the compressed gas from the setting place of the compressor 1 into the case 6, and an exhaust opening 6b for exhausting the gas in the case 6 to the outside of the case 6. An intake opening for taking in the cooling gas from the outside of the case 6 and an intake opening for taking in the compressed gas from the outside of the case 6 can be provided separately.

[0047] The case 4 houses the heat exchangers 11, 12 and the fan 14. The heat exchangers 11, 12 cool the cooling target while allowing the cooling target to flow through the inside. More specifically, the heat exchangers 11, 12 cool the cooling target by allowing the cooling gas taken in from the outside of the case 4 to flow on the outer surface and exchange heat with the cooling target flowing through the inside. In the present embodiment, the post-cooler includes the heat exchanger 11, and the oil cooler includes the heat exchanger 12. The post-cooler cools the discharge gas from the aforementioned compressor main body 2 as the cooling target. The oil cooler cools the oil supplied to the aforementioned compressor main body 2 as the cooling target. The fan 14 is rotated by the fan motor 13 as an alternating-current motor to suck in the cooling gas (air in the present embodiment) from a suction port 14a and discharge it from a discharge port 14b. The fan 14 is a servo fan in the present embodiment, but can be a fan of another form such as a sirocco fan. In addition, the cooling gas is not limited to air, but can be nitrogen or the like.

[0048] In the present embodiment, the fan 14 is driven by the fan motor 13 to send the cooling gas toward the heat exchangers 11, 12 to take away heat. That is, the fan 14 of the present embodiment is a fan of the sending type. The fan 14 is surrounded by a fan case, and takes in the cooling gas from the outside of the case 4 from a suction port 14a of the fan case. In the present embodiment, the cooling gas that is ejected from an ejection port 14b of the fan case takes away heat (cools) from the cooling objects while flowing over the outer surfaces of the rear cooler 11 and the oil cooler 12, and is then discharged to the outside of the case 4. That is, in the present embodiment, the heat exchanger 11 included in the rear cooler and the heat exchanger 12 included in the oil cooler are disposed downstream of the fan 14. In the heat exchanger 11, heat is exchanged between the cooling gas taken in from the outside of the case 4 that is supplied from the fan 14 and the ejected gas, and the ejected gas is cooled. In the oil cooler 12, heat is exchanged between the cooling gas taken in from the outside of the case 4 that is supplied from the fan 14 and the oil, and the oil is cooled. In the present embodiment, since the fan 14 is disposed on the upstream side of the heat exchangers 11, 12, the density of the cooling gas (in the present embodiment, the density of air) around the fan is not easily affected by heat exchange. Therefore, the practicality is higher in the case where the present application is applied, as compared with a structure in which the fan 14 is disposed on the downstream side of the heat exchangers 11, 12.

[0049] The rotational speed of the fan motor 13, and consequently the fan 14, can be controlled by the fan inverter 15. As will be described later, the fan inverter 15 can set an upper limit frequency of the electric current supplied to the fan motor 13.

[0050] As a temperature sensor for detecting the temperature of the cooling gas (in the present embodiment, air) taken in from the outside of the frame 6 (hereinafter referred to as the ambient temperature), that is, the temperature of the cooling gas before passing through the heat exchangers 11, 12 (hereinafter referred to as the initial temperature of the cooling gas), the compressor 1 is provided with a frame intake temperature sensor 21. The frame intake temperature sensor 21 is disposed at the intake opening 6a of the frame 6, and measures the temperature of the cooling gas taken in from the intake opening 6a as the initial temperature of the cooling gas. In the present embodiment in which the cooling gas is air, the temperature of the outside air is directly detected by the frame intake temperature sensor 21. The gas temperature T al measured by the frame intake temperature sensor 21 (an example of the initial temperature of the cooling gas) is sent to the controller 5.

[0051] As the discharge temperature sensor for detecting the temperature of the discharged gas from the discharge port 2h of the compressor main body 2, the compressor 1 is provided with an oil temperature sensor 22 that measures the oil temperature of the oil accumulation portion 3a of the oil separation and recovery device 3. That is, in the present embodiment, the temperature of the discharged gas from the compressor main body 2 is indirectly detected by the oil temperature sensor 22. The oil temperature Td1 measured by the oil temperature sensor 22 is sent to the controller 5. Instead of the oil temperature sensor 22, a discharge temperature sensor 23 that is provided at the discharge port 2h of the compressor main body 2, measures the temperature of the discharged gas, i.e., the discharge temperature Td2, and sends it to the controller 5 can also be used.

[0052] Next, the control performed by the controller 5 and the fan inverter 15 will be described.

[0053] If referring to Figure 2 together, the controller 5 stores a lower limit value (lower limit frequency) and an upper limit value (upper limit frequency) of the frequency of the current supplied to the fan motor 13 by the fan inverter 15, and controls the frequency of the fan inverter 15, i.e., the rotational speed of the fan motor 13, between the lower limit frequency and the upper limit frequency. In the present embodiment, the controller 5 controls the frequency of the fan inverter 15 in accordance with the oil temperature Td1 input from the oil temperature sensor 22. For example, in the case where the oil temperature Td1 is higher than a prescribed temperature, the controller 5 increases the frequency of the fan inverter 15 (increases the rotational speed of the fan motor 13), and increases the cooling capacity of the aftercooler 11 and the oil cooler 12. On the contrary, in the case where the oil temperature Td1 is lower than the prescribed temperature, the controller 5 decreases the frequency of the fan inverter 15 (decreases the rotational speed of the fan motor 13), and suppresses the cooling capacity of the aftercooler 11 and the oil cooler 12.

[0054] The fan inverter 15 compares the current value of the supply current from the fan inverter 15 to the fan motor 13 with a threshold value (for example, a value obtained by adding a margin to the rated current value of the fan motor 13) that is set in advance. If the current value of the supply current to the fan motor 13 reaches the threshold value, the fan inverter 15 performs tripping (cut-off of the power supply from the fan inverter 15 to the fan motor 13) for the purpose of protecting the fan motor 13.

[0055] As for the control up to this point, the control performed by the controller 5 in the present embodiment shown in Figure 2 is the same as the conventional control shown in Figure 3 . In particular, the point that the lower limit frequency of the fan inverter 15 is fixed (i.e., is constant regardless of the oil temperature Td1, the gas temperature Ta1, etc.) is common to the control performed by the controller 5 in the present embodiment shown in Figure 2 and the conventional control shown in Figure 3 . However, the point that the upper limit frequency of the fan inverter 15 is variable in accordance with the oil temperature Td1, the gas temperature Ta1, etc. is different between the control performed by the controller 5 in the present embodiment shown in Figure 3In the conventional control shown, the upper limit frequency of the fan inverter 15 is also fixed (i.e., is not dependent on the oil temperature Td1, the gas temperature Ta1, etc. and is constant), and in relation to this, in the control performed by the controller 5 in the present embodiment Figure 2 In the control performed by the controller 5 in the present embodiment shown, the upper limit frequency of the fan inverter 15 is variable. This will be described below.

[0056] Even if the rotational frequency of the fan motor 13 is constant, the temperature (ambient temperature) of the external gas outside the frame 6 in the installation site of the compressor 1, i.e., the temperature of the external gas used as the cooling gas (corresponding to the cooling gas initial temperature) is lower, the load of the fan motor 13 is higher, and tripping is more likely to occur. This is because the higher the gas density of the cooling gas blown by the fan 14, the more the power increases, and the lower the temperature of the cooling gas, the higher the gas density of the cooling gas. Therefore, the lower the detected cooling gas initial temperature (the gas temperature Ta1 measured by the frame intake temperature sensor 21 in the present embodiment), i.e., the higher the gas density and the more the power increases, the lower the upper limit frequency of the fan inverter 15 is set by the controller 5. Thus, it is possible to prevent tripping due to overcurrent of the fan motor 13 in the tank 4 caused by a change in the ambient temperature of the installation site of the compressor 1.

[0057] Figure 4 Various examples (relationships L1 to L5) of the relationship between the cooling gas initial temperature and the upper limit frequency of the fan inverter 15 stored by the controller 5 are shown.

[0058] In the relationships L1 to L5, in the range of the cooling gas initial temperatures t0 to t4, the upper limit frequency is set so that the current supplied to the fan motor 13 is below the allowable current value at each cooling gas initial temperature. In the relationships L1 to L3, the upper limit frequency is set to continuously decrease as the ambient temperature decreases. In the relationship L5, the upper limit frequency is set to decrease in stages as the cooling gas initial temperature decreases.

[0059] The relationship L1 is that, in the range of the cooling gas initial temperatures t0 to t4, the cooling gas initial temperature and the upper limit frequency of the fan inverter 15 are set so that, at each cooling gas initial temperature, the upper limit frequency is a value at which the current supplied to the fan motor 13 is the allowable current value. The relationship L1 is a first order function that includes the upper limit frequency fl at which the current supplied to the fan motor 13 is the allowable current value at the cooling gas initial temperature t0 and the upper limit frequency f5 at which the current supplied to the fan motor 13 is the allowable current value at the cooling gas initial temperature t4. In the relationship L1, the upper limit frequency is set to continuously decrease as the ambient temperature decreases. Figure 4In the graph of the relationship between the cooling gas initial temperature and the upper limit frequency of the fan inverter 15, in a region on the lower side of the thick solid line showing the relationship LI, the upper limit frequency corresponding to each cooling gas initial temperature is a value lower than the allowable current value of the current supplied to the fan motor 13. Thus, as long as the cooling gas initial temperature and the upper limit frequency satisfy the relationship LI, or the relationship of the two is set within this region, overcurrent occurrence in the fan motor 13 due to a decrease in the cooling gas initial temperature in the range of t0 to t4 can be prevented. The relationships L2 to L5 are all within this region.

[0060] In the relationship L2, as with the relationship LI, the cooling gas initial temperature and the upper limit frequency of the fan inverter 15 are set as a linear function. Further, in the relationship L2, the upper limit frequency is set at each cooling gas initial temperature so that the current supplied to the fan motor 13 becomes a constant value.

[0061] In the relationship L3, the relationship between the cooling gas initial temperature and the upper limit frequency of the fan inverter 15 is set with two linear functions. That is, the relationship L3 is determined by a linear function including the upper limit frequency fl at the cooling gas initial temperature t0 and the upper limit frequency f2 at the cooling gas initial temperature t2, and a linear function including the upper limit frequency f2 at the cooling gas initial temperature t2 and the upper limit frequency f4 at the cooling gas initial temperature t3.

[0062] In the relationship L4, the relationship between the cooling gas initial temperature and the upper limit frequency of the fan inverter 15 is set as a smoothly convex downward function, that is, a convex downward polynomial function, which connects the upper limit frequency fl at the cooling gas initial temperature t0 and the upper limit frequency f4 at the cooling gas initial temperature t3.

[0063] In the relationship L5, the relationship between the cooling gas initial temperature and the upper limit frequency of the fan inverter 15 changes in 3 stages or in a step function shape. First, at the cooling gas initial temperature t3 to t4, it is a constant upper limit frequency f4. Further, in the temperature range of the cooling gas initial temperature tl to t3 lower than this temperature range, it is a constant upper limit frequency f3 lower than the upper limit frequency f4. Further, in the temperature range of the cooling gas initial temperature t0 to tl lower than this temperature range, it is a constant upper limit frequency fl lower than the upper limit frequency f3.

[0064] Hereinafter, the second and third embodiments of the present application will be described. As for these embodiments, points not particularly mentioned are the same as the first embodiment.

[0065] (Second Embodiment)

[0066] Figure 5In the second embodiment of this application shown, the compressor 1 serves as an air temperature sensor for detecting the initial temperature of the cooling gas, replacing the housing intake air temperature sensor 21 (see reference). Figure 1 The fan inverter 15 is equipped with a fan gas temperature sensor 24A, which is located upstream of the fan 14 (e.g., slightly in front of the intake port 14a) to measure the temperature of the cooling gas drawn into the fan 14 from the intake port 14a. Based on the gas temperature Ta2 (an example of the initial temperature of the cooling gas) measured by the fan gas temperature sensor 24A, the controller 5 sets the upper limit frequency of the fan inverter 15 in the same manner as in the first embodiment.

[0067] (Third Implementation)

[0068] exist Figure 6 In the compressor 1 of the third embodiment of this application shown, an air temperature sensor used to detect the initial temperature of the cooling gas is used instead of the housing intake air temperature sensor 21 (see reference). Figure 1 Downstream of fan 14, up to between heat exchangers 11 and 12 (e.g., slightly behind nozzle 14a), a fan gas temperature sensor 24B is configured to measure the temperature of the cooling gas ejected from nozzle 14b of fan 14. The controller 5 sets the upper limit frequency of fan inverter 15 based on the gas temperature Ta3 (an example of the initial cooling gas temperature) measured by fan gas temperature sensor 24B, in the same manner as in the first embodiment.

[0069] (Fourth Implementation)

[0070] Figure 7 The compressor 1 shown in the fourth embodiment of this application serves as an air temperature sensor for detecting the initial temperature of the cooling gas, replacing the housing intake air temperature sensor 21 (see reference). Figure 1 The compressor inverter 15 is equipped with a compressor intake temperature sensor 25, which is installed in the suction flow path 2g of the compressor body 2 to measure the temperature of the compressed gas drawn into the compressor body 2 from the suction flow path 2g. In this embodiment, the compressed gas and the cooling gas are the same gas, so the controller 5 sets the upper limit frequency of the fan inverter 15 based on the gas temperature Ta4 (an example of the initial temperature of the cooling gas) measured by the compressor intake temperature sensor 25, in the same manner as in the first embodiment.

[0071] Figures 8 to 10 Various variations of the internal structure of housing 4 are shown. These variations can be applied to the first through fourth embodiments.

[0072] exist Figure 8In the modification shown, the heat exchangers 11, 12 are not disposed on the side of the blowout port 14b of the fan 14, but on the side of the suction port 14a. The cooling gas introduced into the casing 4 and sucked into the suction port 14a of the fan 14 flows on the outer surfaces of the aftercooler 11 and the oil cooler 12 for heat exchange. That is, in the present embodiment, the aftercooler 11 and the oil cooler 12 are disposed upstream of the fan 14.

[0073] In Figure 9 In the modification shown, the cooling gas blown out from the blowout ports 14b of the two fans 14 flows on the outer surfaces of the aftercooler 11 and the oil cooler 12 for heat exchange. The number of fans 14 can also be three or more.

[0074] In Figure 10 In the modification shown, the heat exchangers 11, 12 are not disposed on the side of the blowout port 14b of the fan 14, but on the side of the suction port 14a. The cooling gas introduced into the casing 4 and sucked into the suction port 14a of the fan 14 flows on the outer surfaces of the aftercooler 11 and the oil cooler 12 for heat exchange. That is, in the present embodiment, the aftercooler 11 and the oil cooler 12 are disposed upstream of the fan 14.

[0075] The above describes the specific embodiments of the present application and modifications thereof, but the present application is not limited to the above-described modes, and can be variously modified within the scope of the present application. For example, in other embodiments of the present application, the compressor main body 2 can also be an oil-free screw compressor. Further, in the embodiments of the present application, the external gas (air) is described as an example of the cooling gas, but the cooling gas can also be other than the external gas. Further, in the embodiments of the present application, the structure in which the frame 6 houses the compressor main body 2, the oil separation and recovery device 3, the casing 4, and the controller 5 is described, but the compressor 1 can also not have the frame 6. Furthermore, as the rotation speed control unit that controls the rotation speed of the fan motor 13 and can set the upper limit frequency, a component other than the inverter 15 can also be used.

[0076] Explanation of Reference Numerals

[0077] 1 compressor

[0078] 2 compressor main body

[0079] 2a main motor

[0080] 2b screw rotor

[0081] 2c rotor shaft

[0082] 2d bearing

[0083] 2e filter

[0084] 2f intake valve

[0085] 2g suction flow path

[0086] 2h blowout port

[0087] 2j rotor chamber

[0088] 3 oil separation and recovery device

[0089] 3a oil storage portion

[0090] 4 case

[0091] 5 controller

[0092] 6 frame

[0093] 6a intake opening

[0094] 6b discharge opening

[0095] 7 main inverter

[0096] 8a gas flow path (compressor main body ~ oil separation and recovery device)

[0097] 8b gas flow path (oil separation and recovery device ~ aftercooler)

[0098] 8c gas flow path (aftercooler ~ supply destination)

[0099] 9a oil flow path (oil storage portion ~ oil cooler)

[0100] 9b oil flow path (oil cooler ~ lubrication target)

[0101] 11 heat exchanger (aftercooler)

[0102] 12 heat exchanger (oil cooler)

[0103] 13 fan motor

[0104] 14 fan

[0105] 14a suction port

[0106] 14b discharge port

[0107] 15 fan inverter

[0108] 21 frame intake temperature sensor

[0109] 22 oil temperature sensor

[0110] 23 discharge temperature sensor

[0111] 24A, 24B fan gas temperature sensor

[0112] 25 compressor intake temperature sensor

Claims

1. A compressor, characterized in that, have: The compressor body draws in and compresses the gas to be compressed. A heat exchanger is used to cool an object while allowing air to circulate inside it. A fan, driven by a fan motor, causes cooling gas to flow across the outer surface of the aforementioned heat exchanger to dissipate heat. A temperature sensor detects the temperature of the cooling gas before it is supplied with heat to the aforementioned heat exchanger, i.e., the initial temperature of the cooling gas. as well as The control unit is capable of setting an upper limit frequency, which serves as the upper limit for the rotational frequency of the aforementioned fan motor. The aforementioned control unit sets the aforementioned upper limit frequency so that, at the initial temperature of each of the aforementioned cooling gases detected by the aforementioned temperature sensor, the upper limit frequency is below the rotational frequency at which the current supplied to the aforementioned fan motor becomes an allowable current value.

2. The compressor as described in claim 1, characterized in that, The aforementioned control unit stores the relationship between the initial temperature of the aforementioned cooling gas and the aforementioned upper limit frequency. The aforementioned relationship is set such that the lower the initial temperature of the cooling gas, the lower the aforementioned upper limit frequency.

3. The compressor as described in claim 1, characterized in that, The aforementioned control unit stores the relationship between the initial temperature of the aforementioned cooling gas and the aforementioned upper limit frequency. The aforementioned relationship is set such that as the initial temperature of the aforementioned cooling gas decreases, the aforementioned upper limit frequency decreases continuously or in stages.

4. The compressor as described in claim 1, characterized in that, The aforementioned control unit stores the relationship between the initial temperature of the aforementioned cooling gas and the aforementioned upper limit frequency. The aforementioned relationship sets the aforementioned upper limit frequency to a certain value for the current supplied to the aforementioned fan motor at the initial temperature of each of the aforementioned cooling gases.

5. The compressor as described in any one of claims 1 to 4, characterized in that, It has a frame that houses the aforementioned compressor body, the aforementioned fan, the aforementioned fan motor and the aforementioned heat exchanger.

6. The compressor as described in claim 5, characterized in that, The aforementioned temperature sensor is disposed at the air inlet of the aforementioned frame to measure the temperature of the aforementioned cooling gas taken in from the aforementioned air inlet, which is the initial temperature of the aforementioned cooling gas.

7. The compressor as described in any one of claims 1 to 4, characterized in that, The aforementioned temperature sensor is positioned upstream of the aforementioned fan to measure the temperature of the cooling gas drawn in by the aforementioned fan, serving as the initial temperature of the cooling gas.

8. The compressor as described in any one of claims 1 to 4, characterized in that, The aforementioned temperature sensor is positioned downstream of the aforementioned fan and between it and the aforementioned heat exchanger to measure the temperature of the cooling gas ejected from the aforementioned fan, which is the initial temperature of the aforementioned cooling gas.

9. The compressor as described in any one of claims 1 to 4, characterized in that, The aforementioned compressed gas and the aforementioned cooling gas are the same gas. The aforementioned temperature sensor is configured in the suction flow path of the aforementioned compressor body to measure the temperature of the aforementioned same gas drawn into the aforementioned compressor body from the aforementioned suction flow path, as the initial temperature of the aforementioned cooling gas.

10. The compressor according to any one of claims 1 to 4, characterized in that, It is equipped with a gas cooler for cooling the ejected gas from the compressor body as the aforementioned object of cooling. The aforementioned gas cooler includes the aforementioned heat exchanger.

11. The compressor as claimed in any one of claims 1 to 4, characterized in that, It is equipped with an oil cooler for cooling the oil supplied to the compressor body as the aforementioned cooling object. The aforementioned oil cooler includes the aforementioned heat exchanger.

12. A control method for a compressor, The compressor includes: The compressor body draws in and compresses the gas to be compressed. A heat exchanger is used to cool an object while allowing airflow through it; and A fan, driven by a fan motor, directs cooling air towards the aforementioned heat exchanger, thereby dissipating heat from the cooling air. The control method for the compressor is characterized in that... The initial temperature of the cooling gas is detected by a temperature sensor when it is not yet supplied with heat to the aforementioned heat exchanger. An upper limit frequency is set as the control upper limit of the rotational frequency of the aforementioned fan motor, such that at the initial temperature of each of the aforementioned cooling gases detected by the aforementioned temperature sensor, the upper limit frequency is below the rotational frequency at which the current supplied to the aforementioned fan motor is an allowable current value.

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