JP3891844B2 - Oil-cooled compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oil-cooled compressor provided with an air-cooled oil cooler.
[0002]
[Prior art]
Conventionally, an oil-cooled compressor 20A shown in FIG. 8 is known. This oil-cooled compressor 20A has a compressor main body 22 driven by a motor 21, a suction flow path 23 is connected to the suction port, and an oil separation and recovery device 24 is interposed from the discharge port. The flow path 25 extends. A lower part of the oil separator / recovery unit 24 is an oil reservoir 24a, and a gas compression space in the compressor body 22 from the oil reservoir 24a via an oil filter 26, a temperature control valve 27, and an air-cooled oil cooler 28. An oil passage 29 extending to an oil supply location such as a bearing / shaft seal extends. Further, a bypass passage 31 that does not pass through the air-cooled oil cooler 28 is provided between the temperature control valve 27 and the oil passage 29 on the secondary side of the air-cooled oil cooler 28.
[0003]
The air-cooled oil cooler 28 is driven by an independent motor 32 and is supplied with a cooling fan 33 for sending air to the air-cooled oil cooler 28 and cooling it. 24 is provided with temperature detecting means 34 for detecting the temperature inside. A temperature signal indicating the temperature detected by the temperature detecting means 34 is input to the controller 35, and a control signal is output from the controller 35 to the temperature control valve 27 based on the temperature signal. The amount of oil flowing to the air-cooled oil cooler 28 and the oil flowing to the bypass flow path 31 is adjusted by the control valve 27.
[0004]
In the oil-cooled compressor 20A having the above-described configuration, the gas sucked into the compressor body 22 from the suction passage 23 is compressed in the gas compression space to be supplied and discharged to the discharge passage 25 with oil. To the oil separator / collector 24. In the oil separator / recovery unit 24, the compressed gas and the oil are separated, the compressed gas is sent out to the portion of the discharge passage 25 extending from the upper part of the oil separation / recovery unit 24, and the oil is temporarily stored in the oil reservoir 24a. The oil in the oil reservoir 24a reaches the temperature control valve 27 from the oil filter 26 in the oil passage 29, and is sent to the above-described oil supply location via the air-cooled oil cooler 28 or the bypass passage 31. Thereafter, the oil is returned from the discharge flow path 25 to the oil separator 24 and circulated. That is, in the temperature control valve 27 controlled by the controller 35, when the temperature detected by the temperature detecting means 34 is high, the amount of oil flowing to the air-cooled oil cooler 28 is increased, and conversely, the detected temperature is reduced. When it is low, the amount of oil flowing through the bypass passage 31 is increased.
[0005]
An oil-cooled compressor 20B shown in FIG. 9 is conventionally known. In FIG. 9, parts common to the oil-cooled compressor 20 </ b> A shown in FIG. 8 are given the same numbers, and description of these common parts is omitted.
In this oil-cooled compressor 20B, a temperature controller 41 is provided in a portion of the discharge passage 25 between the compressor main body 22 and the oil separator / collector 24 so that the temperature can be detected. Based on this, the temperature control valve 27 is controlled as described above. That is, in the temperature control valve 27 controlled by the temperature controller 41, when the temperature detected by the temperature controller 41 is high, the amount of oil flowing to the air-cooled oil cooler 28 is increased, and conversely, the detection When the temperature is low, the amount of oil flowing through the bypass passage 31 is increased.
[0006]
In these oil-cooled compressors 20A and 20B, the number of rotations of the cooling fan 33 is constant, and the amount of heat exchanged by the air-cooled oil cooler 28 is constant unless the atmospheric temperature changes. Will change with this. For this reason, the number of rotations of the cooling fan 33 is the same as the discharge temperature of the compressor body 22 when the cooling fan 33 is at the maximum load of the oil-cooled compressors 20A and 20B and the highest atmospheric temperature is assumed. It is determined so that the air volume that can be kept below the allowable value can be output.
[0007]
However, even if the load on the oil-cooled compressors 20A and 20B is reduced or the atmospheric temperature is lowered, the number of rotations of the cooling fan 33 is constant and the oil cooling capacity of the air-cooled oil cooler 28 is maintained. Therefore, when the bypass flow path 31 is not provided, the discharge temperature decreases together with the temperature of the oil passing through the air-cooled oil cooler 28. And when this discharge temperature falls below an allowable value, the water | moisture content in compressed gas will condense in the oil separation-and-recovery device 24, and drain, ie, water, will precipitate.
[0008]
That is, the water vapor contained in the suction gas is compressed together with the suction gas, and the pressure of the water vapor increases. If the pressure of the suction gas is Ps, the water vapor pressure in the suction gas is Hs, and the discharge pressure is Pd, the pressure Hd of the water vapor contained in the discharged compressed gas is expressed by the following equation.
Hd = Hs · Pd / Ps (1)
[0009]
On the other hand, when the discharge temperature is Td and the saturated water vapor pressure at this temperature is Hd ′, the water vapor is not condensed when Hd <Hd ′, and the water vapor is condensed and water is precipitated when Hd> Hd ′. . As a result, water mixes in the oil, causing poor lubrication and impairing the durability of the bearing. Further, when the discharge temperature Td is excessively increased, oil deterioration is accelerated. Therefore, if the above-mentioned allowable value is Td ′, the temperature control valve 27 increases the oil supply temperature when Td ′> Td and decreases the oil supply temperature when Td ′ <Td. The amount of oil flowing to 31 is adjusted.
[0010]
In addition, an oil-cooled compressor in which an inverter-controlled motor whose rotational speed changes according to a load is shared by a compressor body and a cooling fan is known (Japanese Patent Laid-Open No. 9-203385). In the case of this oil-cooled compressor, the rotational speed of the cooling fan is determined by the rotational speed of the compressor body.
[0011]
[Problems to be solved by the invention]
In the above-described oil-cooled compressors 20A and 20B, even if the load on the compressor body 22 or the atmospheric temperature is reduced and the increase in the discharge temperature is suppressed, the cooling fan 33 remains in a high rotational speed state. Since it is maintained, by increasing the amount of oil flowing through the bypass passage 31 that is not oil-cooled, an abnormal decrease in the oil temperature is prevented and the discharge temperature is maintained at a value within an appropriate range. ing. In this case, the cooling fan 33 continues to operate while consuming unnecessary energy that is not used for oil cooling, and there is a problem that wasted energy is large. Furthermore, there is a problem that noise is increased by rotating the cooling fan 33 at a higher speed than necessary.
[0012]
Further, when the amount of sucked gas is extremely reduced, the gas temperature at the time of gas compression does not rise so much, and even if the oil that has not been cooled via the bypass flow path 31 is supplied to the gas compression space, The discharge temperature becomes low, and it becomes impossible to maintain the discharge temperature at a value within the proper range, causing a problem that water condensed in the oil is deposited.
Furthermore, in order to increase the discharge temperature, the oil remaining in the air-cooled oil cooler 28 continues to be cooled unless the oil is allowed to flow through the bypass flow path 31 and the air-cooled oil cooler 28, and then the discharge temperature needs to be lowered. When this occurs, high-temperature oil newly flows into the air-cooled oil cooler 28, and as a result of a rapid temperature rise in the air-cooled oil cooler 28, stress fluctuation due to expansion occurs. Further, when expansion and contraction is repeated in the air-cooled oil cooler 28 due to such a temperature decrease due to cooling of the remaining oil and a temperature increase due to high-temperature oil, there is also a problem of causing destruction due to metal fatigue.
[0013]
On the other hand, an oil-cooled compressor that does not reduce the amount of sucked gas and avoids a decrease in the amount of heat generated at the time of gas compression while discharging an excessive part of the compressed gas from the discharge flow path to the atmosphere. Is also known, but in this case, there is a problem that energy is lost.
Furthermore, in the case of the oil-cooled compressor disclosed in Japanese Patent Application Laid-Open No. 9-203385, the compressor body and the cooling fan share a motor, and the cooling fan generates power from the cooling fan according to changes in the amount of heat generated in the compressor body. Even if the cooling air volume is adjusted and the fluid noise caused by the cooling air can be suppressed, the number of rotations of the cooling fan is determined regardless of the discharge temperature, and no oil temperature adjustment function is provided other than this cooling fan. Therefore, this oil-cooled compressor has a problem that the discharge temperature and the oil temperature cannot be properly managed.
The present invention has been made with the object of eliminating such conventional problems, and is an oil-cooled compression that enables proper management of the discharge temperature and suppresses noise without wasting energy. Is to provide a machine.
[0014]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the first invention is performed by an air-cooled oil cooler that is supplied to a gas compression space in a compressor body and then cooled for recovered oil and is blown from a cooling fan. In the oil-cooled compressor in which this oil is again supplied to the gas compression space and circulated, the cooling fan is driven, and the amount of air blown to the air-cooled oil cooler is increased or decreased by changing the number of revolutions. A motor that adjusts the oil temperature in the air-cooled oil cooler, a motor coil detector that detects the temperature of the motor coil of the motor that drives the compressor body, and a motor coil that is detected by the motor coil temperature detector In order to make the air flow rate to the air-cooled oil cooler that keeps the oil temperature within a temperature range in which the motor coil does not burn out, a control unit that controls the rotation speed of the motor is used.
[0015]
In the second invention, in addition to the configuration of the first invention, the control unit calculates a frequency corresponding to a difference from the set temperature based on the motor coil temperature detected by the motor coil detector, and passes through an inverter. The rotational speed is controlled based on the lever frequency.
[0016]
In a third aspect of the invention, the above-described components including the compressor body are accommodated in a package having at least an air inlet and an air outlet.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
Figure 1 shows an oil-cooled compressor devices 1A, the portions common to each other with the oil-cooled compressor 20A shown in FIG. 8 will be omitted given the same numbers.
This oil-cooled compressor 1A eliminates the temperature control valve 27 and the bypass passage 31 in the oil-cooled compressor 20A shown in FIG. 8, and the temperature and humidity on the suction side with respect to the motor 32 of the cooling fan 33, and the discharge side The number of revolutions is controlled based on the temperature and pressure at.
[0018]
That is, a suction temperature detector 2 and a suction humidity detector 3 are provided in the suction flow path 23, and a discharge temperature detector 4 and a discharge pressure detector 5 are provided in the oil separation and recovery device 24 as an example of the discharge side. A signal indicating the detected temperature and the like is input to the controller 6. Based on these detected temperatures and the like, the controller 6 controls the rotational speed of the cooling fan 33 as described below.
The suction gas containing moisture is compressed by the compressor main body 22, and the pressure is increased and the temperature is raised. The compressed gas is discharged in a saturated state and reaches the oil separator / collector 24. In the oil separator / recovery unit 24, in order to prevent condensation of moisture, it is necessary to maintain the moisture in a gas state, that is, a temperature at which the moisture is converted to water vapor.
[0019]
Suction gas of the compressor body 22, for example, when an air intake temperature Ts (° C.), the intake humidity and Ds (%), water content Ws (kg / m ³⁾ in the intake air per 1 m ³ is It is expressed by the following formula.
Ws = 0.622 × 1.293 × Hs ÷ 760 (2)
Hs (= Ds ÷ 100 × Hs'): Water vapor partial pressure (mmHg)
Hs' (= 10 ^ {8.884-2224.4 ÷ (273 + Ts)}): Saturated water vapor pressure (mmHg)
Note) “10 ^ X” means “10 to the power of X (= 10 ^X )”
Assuming that the pressure of compressed air is Pdkg / cm ² and this temperature is Td (° C), the amount of water Wd (kg / m ³ ) flowing out per 1 m ³ of saturated compressed air is expressed.
Wd = 0.622 × 1.293 × Hd ÷ {760 ÷ 1.033 × (1.033 + Pd)} (3)
Hd (= 100 ÷ 100 × Hd '= Hd'): Steam partial pressure (mmHg)
Hd '(= 10 ^ {8.884-2224.4 ÷ (273 + Td)}): saturated water vapor pressure (mmHg)
[0020]
In order to prevent the condensed water from precipitating from the compressed air, Ws <Wd may be set, and the discharge temperature Td of the compressor body 22 is maintained by the cooling fan 33 so that Ws <Wd. Yes. In order to suppress the noise most without wasting energy, it is desirable to set the discharge temperature as low as possible in a state where Ws <Wd.
Therefore, Ws = Wd, and the controller 6 calculates the temperature Td based on the temperature Ts, humidity Ds, and pressure Pd on the discharge side of the compressor body 22. Then, based on the difference between this temperature Td and the discharge temperature T detected by the discharge temperature detector 4 provided in the oil separator / collector 24, PID calculation is performed in the controller 6, and the rotational speed Y of the cooling fan 33 is calculated. The motor 32 of the cooling fan 33 is controlled based on the calculation result.
[0021]
Specifically, the PID calculation formula for calculating the rotational speed Y is, for example, the following formula.
_{Y = K p × (T-} Td) + {K 1 × (T-Td) / Ts + Y 1} + K d × (T-Td) (4)
K _p : proportional gain
K ₁ : Integral cane
K _d : differential gain
T ₁ : Integration time
Y ₁ : previous integral component [0022]
Fig. 2 shows the calculation result of the relationship between the discharge temperature and the water content when the pressure of 760mmHg, the temperature of 40 ° C, and the humidity of 75% is sucked and the discharge pressure is 7kg / cm ² G. Moisture content Ws (kg / m ³ ), curve II represents the moisture content Wd (kg / m ³ ), and curve III represents the moisture content (Ws−Wd) (kg / m ³ ) of the difference between the two. In this case, it can be seen that when the discharge temperature is 80 ° C. or higher, water condensed from moisture does not precipitate.
[0023]
It should be noted that the temperature detection on the discharge side of the compressor body 22 is necessary and the discharge temperature detector 4 is essential, but the other suction temperature detector 2, the suction humidity detector 3, and the discharge pressure detector 5 are not necessarily provided. Not necessary.
[0024]
For example, if the oil-cooled compressor 1 </ b> A sucks in the atmosphere and operates with the atmospheric humidity regarded as 100% of the maximum, the suction-side suction humidity detector 3 is not necessary. In this case, if the maximum temperature of the atmosphere can be assumed, for example, 40 ° C, the amount of moisture in the atmosphere is less than that at 40 ° C, as long as the operation is performed under the suction condition of 40 ° C or less. Since precipitation of condensed water in the air can be prevented, the suction temperature detector 2 on the suction side is also unnecessary.
[0025]
Further, if the suction pressure can be regarded as being constant as in the case of sucking in the atmosphere, the discharge pressure is uniquely determined by the specifications of the compressor body 22, and the discharge pressure detector 5 on the discharge side is also unnecessary.
As described above, in the oil-cooled compressor 1A, the rotation speed control of the cooling fan 33 is performed so that the air-cooled oil cooler 28 cools the oil in a range where water does not precipitate from the discharged gas corresponding to the state of the discharged gas. As a result, the discharge temperature is maintained within an appropriate range without wasting energy, and noise is also suppressed.
[0026]
FIG. 3 shows the oil- cooled compressor 1B, and portions common to the oil-cooled compressor 1A shown in FIG.
In the oil-cooled compressor 1 </ b> B, the discharge temperature detector 7 is provided in the discharge flow path 25, and a temperature signal indicating the temperature detected by the discharge temperature detector 7 is input to the temperature controller 8. Then, a temperature difference signal corresponding to the temperature difference between the preset discharge temperature input in advance and the detected temperature is output from the temperature controller 8 to the calculator 9, and the frequency corresponding to the temperature difference signal is output from the calculator 9. A signal is output to the inverter 11, and the rotational speed control for the cooling fan 33 is performed via the inverter 11. That is, the rotational speed of the cooling fan 33 is increased when the discharge temperature is high, and conversely when the discharge temperature is low.
[0027]
With this configuration, as described above, the rotation speed of the cooling fan 33 is controlled so that the air-cooled oil cooler 28 cools the oil in a range where water does not precipitate from the discharge gas, thereby wasting energy. Therefore, the discharge temperature is maintained within an appropriate range, and noise is also suppressed.
[0028]
Figure 4 shows an oil-cooled compressor 1C of package type, the parts common to each other with the oil-cooled compressor A shown in FIG. 1 will be omitted with denoted by the same numbers.
In the oil-cooled compressor 1C, the above-described oil-cooled compressor 1A is accommodated in a package 14 having an air inlet 12 on a side surface and an air outlet 13 on an upper surface. An air-cooled oil cooler 28 is disposed at the air outlet 13 so as to pass outflow air.
In FIG. 4, reference numeral 15 denotes a suction filter.
[0029]
As described above, the oil-cooled compressor 1 </ b> C enables noise suppression in addition to wasteful energy consumption, and preferably, a sound absorbing material is stretched on the inner surface of the package 14. Well, this can further suppress noise.
Further, a filter is provided at the normal air inlet 12, and clogging of the filter is unavoidable. If the number of rotations of the cooling fan 33 is constant, the air volume of the cooling air decreases. However, in the case of this oil-cooled compressor 1C, since the rotation speed of the cooling fan 33 is controlled so as to keep the discharge temperature within an appropriate range, the air volume does not decrease due to the clogging.
[0030]
Moreover, even if it replaces with the same component as the said oil-cooled compressor 1A including the compressor main body 22 in this oil-cooled compressor 1C, even if it provides the oil-cooled compressor 1B shown in FIG. no energy consumption, the reduction of noise, apply exactly the same thing, Fig. 5 shows an oil-cooled compressor 1D of package type provided with this oil-cooled compressor 1B in the package 14 . 5, parts common to the oil-cooled compressor 1B shown in FIG. 3 or the packaged oil-cooled compressor 1C shown in FIG. 4 are denoted by the same reference numerals.
[0031]
FIG. 6 shows the oil-cooled compressor 1E according to the first embodiment of the present invention, and parts common to the oil-cooled compressor 1A shown in FIG. .
In this oil-cooled compressor 1E, the motor 21 that detects the motor coil temperature is provided in the motor 21 that drives the compressor main body 22, and the motor coil temperature detector 16 indicates the detected motor coil temperature. A temperature signal is input to the temperature controller 8. Then, a temperature difference signal corresponding to the temperature difference between the preset motor coil temperature inputted in advance and the detected motor coil temperature is outputted from the temperature controller 8 to the calculator 9, and the calculator 9 converts the temperature difference signal to the temperature difference signal. A corresponding frequency signal is output to the inverter 11, and the rotational speed control for the cooling fan 33 is performed via the inverter 11. That is, the rotational speed of the cooling fan 33 is increased when the detected motor coil temperature is high, and conversely, it is decreased when the detected motor coil temperature is low.
[0032]
Even if water is condensed in the oil due to a decrease in the discharge temperature, there will be no immediate problem in continuing the compressor operation if the amount is small. Although it burns out and the compressor operation becomes impossible and a situation of an emergency stop is caused, in the oil-cooled compressor 1E, the occurrence of such an emergency stop is avoided. Further, similarly to the above, in the oil-cooled compressor 1E, the cooling fan 33 is not rotated at a higher speed than necessary, so that energy is not wasted and an abnormal increase in the discharge temperature is avoided. Noise is also reduced. In order to minimize the waste of energy and minimize the noise while avoiding an abnormal increase in the discharge temperature, the oil that can make the motor coil temperature as high as possible within the range where the motor coil does not burn out. It is desirable to control the amount of air blown to the air-cooled oil cooler and thus the rotational speed of the motor so as to keep the temperature.
[0033]
FIG. 7 shows a package-type oil-cooled compressor 1F according to the second embodiment of the present invention, and is common to the oil-cooled compressor 1E shown in FIG. 6 or the oil-cooled compressor 1C shown in FIG. About the part, the same number is attached | subjected and description is abbreviate | omitted.
Also in the case of this package-type oil-cooled compressor 1F, the above-described oil-cooled compressor 1E is housed in a package 14 having an air inlet 12 on the side surface and an air outlet 13 on the upper surface, as described above. Yes. An air-cooled oil cooler 28 is disposed at the air outlet 13 so as to pass outflow air.
[0034]
With this configuration, as with the oil-cooled compressor 1E shown in FIG. 6, in addition to preventing the occurrence of an emergency stop of the compressor due to motor coil burnout, etc., further noise suppression, the above-described filter It is possible to eliminate the adverse effects caused by clogging.
[0035]
【The invention's effect】
As is clear from the above description, according to the present invention, after the oil is supplied to the gas compression space in the compressor body, the recovered oil is cooled by the air-cooled oil cooler blown from the cooling fan. In an oil-cooled compressor in which this oil is again supplied to the gas compression space and circulated, the cooling fan is driven and the amount of air blown to the air-cooled oil cooler is increased or decreased by changing the rotational speed. The motor for adjusting the oil temperature in the air-cooled oil cooler, the motor coil detector for detecting the temperature of the motor coil of the motor driving the compressor body, and the motor coil temperature detector the motor coil temperature, and a control Gosuru controller the rotational speed of the motor to the air volume to the air-cooled oil cooler to maintain the oil temperature may be in the range of temperature in which the motor coil is not burned configuration When And Aru.
[0036]
Therefore, because there is no possibility to speed rotation of the cooling fan than necessary, wasting without consuming energy, together with abnormal increase in the discharge temperature is avoided, the noise also Ru reduced. In addition, the motor coil burns out due to the rise in the motor coil temperature, the compressor operation becomes impossible, and the occurrence of an emergency stop is avoided .
[0037]
Furthermore, according to this invention, it is set as the structure which accommodated the component mentioned above containing the said compressor main body in the package which has an air inflow port and an air outflow port at least.
For this reason, in addition to the above-described effects, when a filter is provided at the normal air inlet, the rotation speed of the cooling fan is controlled so as to keep the discharge temperature within an appropriate range. There is an effect that a decrease in the air volume of the cooling air is prevented.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of an oil- cooled compressor.
FIG. 2 is a diagram showing the relationship between the discharge temperature and the amount of water in the discharge gas in the oil-cooled compressor shown in FIG.
FIG. 3 is a diagram showing an overall configuration of another oil-cooled compressor.
4 is a diagram showing the overall configuration of the package type of the oil-cooled compressor.
FIG. 5 is a diagram showing the overall configuration of another packaged oil-cooled compressor.
6 is a diagram showing the overall configuration of the engagement Ru oil-cooled compressor of the present invention.
7 is a diagram showing the overall structure of the present invention to another packaged engaging Ru oil-cooled compressor.
FIG. 8 is a diagram showing an overall configuration of a conventional oil-cooled compressor.
FIG. 9 is a diagram showing an overall configuration of another conventional oil-cooled compressor.
[Explanation of symbols]
1A, 1B, 1C, 1D, 1E, 1F Oil-cooled compressor 2 Suction temperature detector 3 Suction humidity detector 4 Discharge temperature detector 5 Discharge pressure detector 6 Controller 7 Discharge temperature detector 8 Temperature controller 9 Calculator DESCRIPTION OF SYMBOLS 11 Inverter 12 Air inflow port 13 Air outflow port 14 Package 15 Suction filter 16 Motor coil temperature detector 21 Motor 22 Compressor main body 23 Suction channel 24 Oil separation and recovery device 24a Oil reservoir 25 Discharge channel 26 Oil filter 28 Air cooling type Oil cooler 29 Oil flow path 32 Motor 33 Cooling fan 34 Temperature detection means 35 Controller 41 Temperature controller

Claims (3)

After being supplied to the gas compression space in the compressor body, the recovered oil is cooled by an air-cooled oil cooler blown from a cooling fan, and this oil is supplied again to the gas compression space and circulated. In an oil-cooled compressor,
A motor that drives the cooling fan and increases or decreases the amount of air blown to the air-cooled oil cooler by changing the number of revolutions, and adjusts the oil temperature in the air-cooled oil cooler;
A motor coil detector that detects the temperature of the motor coil of the motor that drives the compressor body;
In order to set the motor coil temperature detected by the motor coil temperature detector to an air temperature that keeps the oil temperature within a range where the motor coil does not burn out, the rotation speed of the motor is An oil-cooled compressor comprising a control unit for controlling. The control unit calculates a frequency corresponding to a difference from a set temperature based on the motor coil temperature detected by the motor coil detector, and controls the rotation speed based on the frequency via an inverter. The oil-cooled compressor according to claim 1 . The oil-cooled compressor according to claim 1 or 2 , wherein the above-described components including the compressor body are accommodated in a package having at least an air inlet and an air outlet.

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