JP5167299B2 - Low noise type liquid cooling compressor - Google Patents

Description

  In the liquid-cooled screw compressor having a pair of male and female screw rotors that mesh with each other, the present invention reduces the amplitude of noise that is emitted to the outside mainly through the suction passage of the compressor, particularly the pulsation amplitude on the suction side of the compressor body. The present invention relates to a low-noise liquid-cooled compressor that suppresses noise level.

  The temperature of the screw rotor (hereinafter also referred to as the rotor) of the screw compressor increases as the fluid is compressed. Therefore, a cooling mechanism for cooling the screw rotor is essential. As such a cooling mechanism, supply of cooling air or cooling liquid by an external cooling device has been conventionally used.

  First, a general cooling mechanism of an oil-cooled screw compressor using cooling oil (hereinafter also simply referred to as oil) as the cooling liquid will be described with reference to FIG. FIG. 7 is a cross-sectional view of a main body of a conventional general oil-cooled screw compressor.

  The oil-cooled screw compressor 31 includes a pair of male and female screw rotors 32 that mesh with each other in a rotor casing 30. The screw rotor 32 is rotatably supported by a bearing portion 33 on the suction side and a bearing portion 34 on the discharge side. Between the bearing portions 33 and 34 and the screw rotor 32, shaft seal portions 35 and 36 are provided. Are provided respectively. Also, lubrication holes 38, 39, and 40 are provided for lubricating the bearing portions 33, 34, the shaft seal portions 35, 36, and the lubrication locations such as the rotor chamber 37 that is the gas compression space in the screw compressor 31. Yes.

  The gas sucked from the suction port 41 of the screw compressor 31 is compressed while receiving oil injection from the oil supply holes 38, 39 and 40, and is discharged from the discharge port 42 as compressed gas together with the oil. The discharged compressed gas and oil are separated from each other in an oil separation / recovery unit (not shown), and the compressed gas is sent out to the discharge channel 43. Here, the oil injected into the rotor chamber 37 functions as cooling of the gas compression part, sealing between the screw rotors 32, and sealing between the screw rotor 32 and the inner wall part of the rotor casing 30 and lubrication. Yes.

  Next, noise countermeasure technology according to a conventional example of a compressor will be described with reference to FIGS. FIG. 8 is a system diagram showing an embodiment of a two-stage oil-free compressor according to a conventional example, and FIG. 9 is a cross-sectional view showing an embodiment of a silencer of the compressor according to the conventional example.

  As a noise countermeasure for the compressor according to the conventional example, although not shown, there is a weight, and the vibration amplitude is reduced by supporting the compressor main body and the electric motor, which are the excitation sources, rigidly on the floor surface by the gantry and the column. There is a packaged screw compressor that suppresses vibration propagation to the base plate and cover of the package (see Patent Document 1). However, this conventional example suppresses the propagation of the vibration vibration of the compressor main body and the electric motor, and does not consider suppressing the noise itself generated by the compressor main body. In particular, since the compressor has to suck in the outside air, it is difficult to make the pulsation sound from the suction port difficult to leak to the outside.

  Next, as shown in FIG. 8, the conventional two-stage oil-free compressor is divided into a plurality of discharge pipes over its main length, for example, two discharge pipes of the low-stage compressor 50 are discharged. By using the pipes 51 and 52, the transmission loss is increased, and the noise value caused by the pulsation of the discharge pressure of the compressor is reduced (see Patent Document 2). This compressor is effective for the noise caused by the pulsation of the discharge pressure in a fixed frequency component of 2 kHz or more. However, when the screw rotation speed is changed, the frequency of the generated noise changes, and the noise is low in all operating conditions. It is impossible to get an effect.

  Further, as shown in FIG. 9, a silencer of a compressor according to another conventional example communicates via a first silencer 54 that communicates with a discharge hole of the compressor, and a first silencer 54 and a connection pipe 53. A second silencer 55, and a chamber 56 in the connecting pipe 53, whereby the pulsation of the discharge pressure of the compressor, the air column resonance frequency generated between the silencers in the multistage silencer structure, and the basic pressure artery By avoiding the frequency, it is intended to prevent a decrease in the silencing effect (see Patent Document 3). Even in this conventional example, as in the above conventional example, it is effective in reducing the pulsation noise of the discharge pressure in a fixed frequency band, but the frequency of the generated noise changes when the rotation speed of the compressor is changed, and all the operations are performed. The low noise effect cannot be obtained in the state.

JP-A-7-208361 JP-A-7-133774 JP-A-6-10875

  Therefore, an object of the present invention is to obtain a low noise effect in various operating conditions even if the rotation speed of the compressor changes and the frequency of the generated noise changes, mainly through the suction passage of the compressor. It is an object of the present invention to provide a low-noise liquid-cooled compressor that suppresses the noise level by reducing the amplitude of noise generated in the compressor, particularly the pulsation amplitude on the suction side of the compressor body.

In order to achieve the above object, the low-noise liquid-cooled compressor according to claim 1 of the present invention employs a liquid-cooled screw compressor having a pair of male and female screw rotors that mesh with each other. A liquid injection hole is provided in the suction flow path for sucking in the gas supplied to the pipe, and is configured to inject liquid from the liquid injection hole into the suction flow path to act as a heavy object and reduce noise. The liquid is configured to be able to be injected into a rotor chamber that houses the screw rotor, and the compressed gas and the liquid are separated into a discharge passage that discharges the compressed gas, and the separated liquid is recovered. And a liquid injection line for injecting the liquid separated and recovered by the liquid separation and recovery means is connected to the liquid injection hole provided in the suction flow path, and the screw rotor. Drive An inverter is provided in the drive motor, and a flow rate adjusting means for adjusting the liquid flow rate is provided in the liquid injection line, respectively, and a frequency signal commanded to the drive motor by the inverter is received, and based on this frequency signal, Control means for controlling the flow rate adjusting means is provided.

  According to the low-noise type liquid-cooled compressor according to claim 1 of the present invention, in the liquid-cooled screw compressor having a pair of male and female screw rotors meshing with each other, the suction flow path for sucking the gas supplied to the screw rotor Injecting liquid into the suction flow path from this liquid injection hole, the liquid injected into the liquid injection hole acts as a heavy object in the suction flow path of the compressor, The noise value can be reduced by lowering the amplitude of noise that mainly comes out through the suction passage of the compressor, particularly the vibration amplitude of the pulsating sound on the suction side of the compressor.

Further, the liquid is configured to be able to be injected into a rotor chamber that houses the screw rotor, and the compressed gas and the liquid are separated into a discharge passage that discharges the compressed gas. Since a liquid separation / recovery means for recovery is provided, a liquid injection line for injecting the liquid separated and recovered by the liquid separation / recovery means is connected to the liquid injection hole provided in the suction channel. Without using a separate liquid supply means, the cooling liquid used for cooling and lubricating the screw rotor and sealing between the rotors can be used as a liquid for reducing the noise value.

  Further, an inverter is provided in the drive motor for driving the screw rotor, and a flow rate adjusting means for adjusting the liquid flow rate is provided in the liquid injection line, and a frequency signal commanded to the drive motor by the inverter is received. Since the control means for controlling the flow rate adjusting means is provided based on this frequency signal, an appropriate amount of liquid can be supplied for each pulsation sound in the suction flow path, and for each rotation speed of the compressor, An effective low noise effect can be realized.

It is a systematic diagram for demonstrating the low noise type liquid cooling compressor which concerns on embodiment of this invention. It is an example of the pulsation sound detected by the sound pressure sensor according to the comparative example of the present invention. 6 is a comparison data of sound pressure levels at a screw rotation speed of 1000 r / min according to an embodiment of the present invention. 6 is a comparison data of sound pressure levels at a screw rotation speed of 2500 r / min according to an embodiment of the present invention. 6 is a comparison data of sound pressure levels at a screw rotation speed of 4000 r / min according to an embodiment of the present invention. It is a comparison data of a sound pressure level according to the embodiment of the present invention at a screw rotation speed of 5410 r / min. It is a main body sectional view of the conventional general oil-cooled screw compressor. It is a systematic diagram which shows one Example of the two-stage oil free compressor which concerns on a prior art example. It is sectional drawing which shows one Example of the silencer of the compressor which concerns on a prior art example.

  Next, a liquid-cooled screw compressor according to an embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a system diagram for explaining a low-noise liquid-cooled compressor according to an embodiment of the present invention.

  The low noise type liquid cooling type compressor according to the embodiment of the present invention will be described by taking a low noise type oil cooling type screw compressor using a cooling oil as a cooling liquid as an example. This low noise type oil-cooled screw compressor includes a compressor main body 1 that is engaged with a pair of male and female screw rotors 2 a and 2 b and is rotatably accommodated in a rotor chamber 4 formed in a rotor casing 3. ing. A suction flow path 5 is connected to the suction port 1a of the compressor body 1, and one end side of the discharge flow path 6 is connected to the discharge port 1b. Only one male rotor 2 a of the pair of male and female screw rotors 2 a and 2 b constituting the compressor body 1 is connected to the drive shaft 7 of the drive motor M.

  By rotating the screw rotors 2a, 2b by the drive motor M, the gas supplied from the suction flow path 5 is sucked from the suction port 1a of the compressor body 1, compressed, and discharged as high-pressure fluid from the discharge port 1b. Discharge into the flow path 6. The drive motor M is housed in a motor housing inside the motor casing 8, and the motor casing 8 is integrally coupled to the rotor casing 3.

  The drive motor M includes a stator (not shown) fixed to the inner surface of the motor casing 8 and a rotor 7a that rotates about the drive shaft 7. The control means 21a built in the controller 21 is connected to the inverter 22 by the controller 21a. Rotation is controlled by a predetermined frequency signal transmitted to. The drive motor M transmits the rotational force of the drive shaft 7 supported by the suction side bearing 9a and the discharge side bearing 9b to the screw rotors 2a and 2b of the compressor body 1.

  On the other hand, the suction flow path 5 is provided with a suction adjustment valve 5a for adjusting the flow rate of the gas passing through the suction flow path 5, and the valve opening degree is controlled by the control means 21a in the controller 21. The An oil separation / recovery device (liquid separation / recovery means) 10 is interposed in the discharge flow path 6, and an oil separation element 10 a is provided inside the oil separation / recovery device 10. Since the oil is slightly mixed in the high-pressure gas flowing into the oil separation / recovery device 10, the oil is captured by the oil separation element 10 a provided in the oil separation / recovery device 10. The oil trapped by the oil separation element 10a is dropped by its own weight, and an oil reservoir 10b is formed below the oil separation / recovery device 10 inside.

  The oil recovered in the oil reservoir 10b in this manner is circulated by an oil pump (not shown) through an oil circulation passage 11 communicating from the oil separator / collector 10 to the compressor body 1. An oil cooler 12 is interposed in the oil circulation channel 11, and the passing oil is cooled by controlling the temperature by the control means 21 a in the controller 21. And the oil cooled by the oil cooler 12 is supplied to the site | part which needs supply of oil through the oil supply flow path provided in the rotor casing 3. FIG. Such an oil supply passage includes an oil supply passage to the suction side bearing (and shaft seal portion) 9a, an oil supply passage to the discharge side bearing (and shaft seal portion) 9b, and the screw rotors 2a and 2b and the rotor casing 3. It consists of an oil injection channel to the compression space to be formed.

  Further, an oil injection hole 20 is provided in the suction flow path 5 for sucking the gas supplied to the rotor chamber 4, and cooling oil can be injected into the oil injection hole 20. That is, the oil injection hole 20 provided in the suction flow path 5 is supplied with oil separated and recovered by the oil separator / collector 10 and cooled by the oil cooler 12 interposed in the oil circulation flow path 11. Are connected so that cooling oil can be injected into the suction flow path 5. The injection hole 20 is disposed in the suction flow path 5 between the suction adjustment valve 5 a provided in the suction portion of the suction flow path 5 and the suction port 1 a of the compressor body 1.

  In this way, by injecting the cooling liquid from the oil injection hole 20 into the suction flow path 5, the cooling liquid injected from the liquid injection hole 20 acts as a heavy object in the suction flow path 5 of the compressor, Decreasing the amplitude of noise that comes out to the outside (for example, the outside of a package (not shown) housing each component of the compressor), especially the vibration amplitude of the pulsating sound on the compressor suction side, mainly through the compressor suction passage 5 Thus, the noise level can be reduced. Further, a part of the cooling oil (cooling liquid) used for cooling, lubrication, sealing, etc. of the screw rotors 2a, 2b can be used as a liquid for reducing the noise value.

  At the same time, a flow rate adjusting valve 24 for adjusting the amount of cooling oil is interposed in the oil supply line 11a, and the drive motor M or the screw rotor 2a, A frequency signal corresponding to the rotational speed of 2b is transmitted to the controller 21, and the opening degree of the flow rate adjusting valve 24 can be controlled by the control means 21a built in the controller 21 based on this frequency signal. Has been.

  That is, in addition to the control means 21a, the controller 21 includes a storage means 21b and a calculation means 21c. On the other hand, the pulsation sound (or its frequency spectrum) on the suction side of the compressor similarly changes according to the change in the rotational speed of the compressor body 1. The storage means 21b in the controller 21 stores in advance reference data of integrated values in a predetermined frequency band of the power spectrum corresponding to the change in the rotational speed of the compressor body 1, and the power spectrum of the power spectrum. Reference data for an appropriate amount of lubrication corresponding to the integrated value level and an appropriate opening of the flow rate adjusting valve 24 is stored in advance.

  The controller 21 receives a frequency signal corresponding to the rotational speed of the drive motor M or the screw rotors 2a and 2b from the inverter 22, and performs an arithmetic operation such as FFT (Fast Fourier Transform) by an internal arithmetic means 21c. The data of the frequency spectrum (horizontal axis: frequency (Hz), vertical axis: sound pressure level (dB)) is calculated. From this data, the calculation means 21c calculates the integrated value of the power spectrum in a predetermined frequency band, for example, 125 Hz to 4 kHz, and compares the calculated value with the reference data stored in advance in the storage means 21b. A proper opening degree of the flow rate adjusting valve 24 is derived, and the control means 21a adjusts and controls the opening degree of the flow rate adjusting valve 24.

  As described above, in a liquid-cooled screw compressor having a pair of male and female screw rotors 2a and 2b meshing with each other, a liquid injection hole 20 is provided in the suction flow path 5 for sucking the gas supplied to the screw rotors 2a and 2b. By injecting the cooling liquid from the liquid injection hole 20 into the suction flow path 5, the cooling liquid injected from the liquid injection hole 20 acts as a heavy object in the suction flow path 5 of the compressor and is mainly compressed. The noise value can be reduced by lowering the amplitude of noise coming out through the suction passage of the compressor, particularly the vibration amplitude of the pulsating sound on the suction side of the compressor.

  At the same time, an inverter 22 is provided in the drive motor M that drives the screw rotors 2a and 2b, and a flow rate adjusting valve (flow rate adjusting means) 24 for adjusting the coolant flow rate is provided in the liquid injection line 11a. The control means 21a is provided which receives the frequency signal commanded to the drive motor M by the inverter 22 and can control the flow rate adjusting valve 24 based on this frequency signal, so that an appropriate amount is provided for each rotation speed of the compressor. The most effective low noise effect can be realized.

<Example>
Next, the conventional oil-cooled screw compressor was modified so as to correspond to the embodiment of the present invention, and an example in which oil was injected from an oil injection hole provided in a suction flow path and a comparative example in which oil was not supplied were attached. This will be described with reference to 2 and 3-6. FIG. 2 relates to a comparative example of the present invention, and shows an example of a pulsating sound detected by a sound pressure sensor provided in the suction flow path. FIG. 3 relates to an embodiment of the present invention, and the sound pressure at a screw rotation speed of 1000 r / min. FIG. 4 shows comparison data of sound pressure levels at a screw speed of 2500 r / min, FIG. 5 shows comparison data of sound pressure levels at a screw speed of 4000 r / min, and FIG. 6 shows sound at a screw speed of 5410 r / min. Comparison data of pressure level.

  In the comparative example that does not lubricate from the lubrication hole 20 provided in the suction flow path 5, the time waveform of the pulsation sound in the suction flow path 5 detected by the sound pressure sensor 23 becomes a saw-shaped waveform as shown in FIG. This is the cause of pulsation due to volume change. As shown in FIGS. 3 to 6, the sound pressure level of such pulsating sound is as follows at all frequencies except the frequency band where the 1/1 octave frequency is 250 to 500 Hz when the screw rotation speed is 4000 r / min to 5410 r / min. The sound pressure level of the example in which oil was injected from the oil supply hole was lower than that of the comparative example in which oil was not supplied.

  That is, by injecting the cooling oil from the oil injection hole 20 provided in the suction flow path 5, the cooling oil injected into the oil injection hole 20 acts as a heavy object in the suction flow path 5 of the compressor, and the compressor It can be seen that the noise value is reduced by reducing the vibration amplitude of the pulsating sound on the suction side.

  In the embodiment of the present invention, the example of the oil-cooled screw compressor using the cooling oil as the coolant has been described. However, the liquid used for injection into the suction channel of the liquid-cooled screw compressor according to the present invention is not limited to oil. The present invention is also applicable to a screw compressor using a refrigerant (in the case of a heat pump or a refrigerator) or cooling water.

  The present invention can also be applied to, for example, a heat pump and a refrigerator.

M: drive motor,
1: compressor body, 1a: suction port, 1b: discharge port,
2a: male rotor, 2b: female rotor,
3: Rotor housing, 4: Rotor chamber,
5: Suction flow path, 5a: Suction adjustment valve,
6: Discharge flow path,
7: Drive shaft, 7a: Rotor,
8: Motor casing,
9a: suction side bearing, 9b: discharge side bearing,
10: Oil separation and recovery device (liquid separation and recovery means), 10a: Oil separation element,
10b: oil sump,
11: Oil circulation passage, 11a: Oil supply line,
12: Oil cooler,
20: Lubrication hole,
21: Controller, 21a; Control means, 21b: Storage means, 21c: Calculation means,
22: Inverter, 23: Sound pressure sensor, 24: Flow rate adjusting valve (flow rate adjusting means)

Claims (1)

In a liquid-cooled screw compressor having a pair of male and female screw rotors that mesh with each other,
A liquid injection hole is provided in the suction flow path for sucking the gas supplied to the screw rotor, and a liquid that acts as a heavy object and reduces noise is injected into the suction flow path from the liquid injection hole. Configured,
The liquid is configured to be able to be injected into a rotor chamber that houses the screw rotor,
On the other hand, the discharge flow path for discharging the compressed gas is provided with liquid separation / recovery means for separating the compressed gas and the liquid and recovering the separated liquid,
A liquid injection line for injecting the liquid separated and recovered by the liquid separation and recovery means is connected to the liquid injection hole provided in the suction channel,
The drive motor that drives the screw rotor is provided with an inverter, and the liquid injection line is provided with flow rate adjusting means for adjusting the liquid flow rate, respectively.
A low-noise liquid-cooled compressor comprising a control means for receiving a frequency signal commanded to the drive motor by the inverter and controlling the flow rate adjusting means based on the frequency signal.