JP2006214602A - Refrigerating cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating cycle device capable of ensuring required amount of oil of two compressors without attaching an overflow pipe to a side face of the compressor and allowing use in common when used in a refrigerating cycle device having the same configuration of the inside of the compressor, constituted by one compressor, and having half of refrigerating capability and being manufacturable at low cost. <P>SOLUTION: This refrigerating cycle device is provided with oil separators arranged in discharge pipes of each of two compressors, two oil bypass circuits for returning oil separated from refrigerant by the oil separators into a suction pipe of the compressor on the other side through a pressure reducing means, two temperature sensors arranged on the downstream side of the pressure reducing means of each of two oil bypass circuits, two inverters for controlling operation speed of two compressors each independently, a compressor control means for deciding operation speed of two inverters, and a compressor operation compensating means for compensating operation speed of two inverters decided by the compressor control means based on difference in temperature detected by two temperature sensors. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a refrigeration cycle apparatus equipped with a plurality of hermetic compressors, and more particularly to oil level control of a compressor.

  Conventionally, in this type of refrigeration cycle apparatus, oil filled in a plurality of compressors is discharged together with the refrigerant, and while circulating in the refrigeration cycle, the oil level of each compressor is biased, reducing the amount of oil. Various oil leveling circuits have been proposed to ensure that the oil level in the compressor is uniform or that the minimum oil level is ensured in order to avoid problems such as poor lubrication and loss of reliability in the sliding parts of the compressor. It has been.

  For example, a float switch type oil level adjuster is known as a method for directly detecting the oil level inside the compressor.

  This oil level adjuster has a configuration in which oil in a compressor is taken into a container through an oil equalizing pipe and the oil level is detected by vertical movement of a float floating on the oil level in the container. In addition, as a premise that the oil in the refrigeration cycle is filled with an appropriate amount or more, an overflow pipe is attached to the side of the compressor container, and if the oil in the compressor container exceeds the predetermined amount, the oil overflows There is also a configuration that is taken out of the compressor container from the pipe and returned to the compressor that is deficient in oil through the decompression means (see, for example, Patent Document 1).

  FIG. 4 shows a conventional refrigeration cycle apparatus described in Patent Document 1. As shown in FIG.

  As shown in FIG. 4, the compressors 1a and 1b are connected in parallel to form one refrigeration cycle.

  The discharge pipes of the compressors 1a and 1b are joined via check valves 19a and 19b for preventing backflow, and an oil separator 2, a four-way valve 3, an outdoor heat exchanger 4, an expansion valve 5, and an indoor heat exchanger 6 are combined. Are connected in this order, and then branched to return to the suction pipes of the compressors 1a and 1b.

  In the oil separator 2, the gas refrigerant and the oil are separated, and the oil flows through the oil return pipe 21 and is connected to the suction pipe junction through the electromagnetic valve 22 and the pressure reducing means 23.

  Overflow pipes 11a and 11b are attached to the side surfaces of the compressors 1a and 1b, respectively, and are connected to the suction pipe merging portion via electromagnetic valves 12a and 12b and decompression means 13a and 13b.

  In the compressors 1a and 1b, the installation positions of the overflow pipes 11a and 11b are appropriate oil level positions, and when the oil level exceeds that, the excess oil can be obtained by opening the solenoid valves 12a and 12b. Is returned to the suction pipe junction and redistributed to the compressors 1a and 1b together with the gas refrigerant.

With the above operation, the oil level of the compressors 1a and 1b can be maintained at an appropriate oil level at the overflow pipe mounting position.
JP 2002-242833 A

  However, since the conventional configuration is provided with an overflow pipe on the side of the compressor, one of the two compressors is used and half of the refrigeration cycle in which the two compressors are mounted. It is impossible to configure a refrigeration cycle with the same capacity and use the same internal structure as the compressor. This will increase costs in terms of parts management and manufacturing man-hours in the manufacture of refrigeration cycle equipment. Had problems.

  The present invention solves the above-described conventional problems, and provides a refrigeration cycle apparatus that can be used in a refrigeration cycle having a half refrigeration capacity constituted by a single compressor and can be manufactured at low cost. The purpose is to provide.

  In order to solve the above-described conventional problems, a refrigeration cycle apparatus according to the present invention includes a refrigeration cycle having a configuration in which two compressors are connected in parallel, and oil disposed in a discharge pipe of each of the two compressors. A separator, two oil bypass circuits for returning the oil separated from the refrigerant by the oil separator to the suction pipe of the other compressor of the two compressors via a pressure reducing means, and the two compressors The discharge temperature sensor disposed in each discharge pipe, the bypass circuit temperature sensor disposed downstream of the pressure reducing means of each of the two oil bypass circuits, and the operating frequency of the two compressors are independent of each other. Two inverters to be controlled, compressor control means for determining the operating frequency of the two inverters, the pressure based on the detected temperatures of the discharge temperature sensor and the bypass circuit temperature sensor. Machine is obtained by a configuration having a compressor operation correction means for performing correction for the two inverters driving frequency determined in the control means.

  As a result, it is possible to share a refrigeration cycle apparatus that can be manufactured at a low cost, and can be shared with a refrigeration cycle that has half the refrigeration capacity constituted by one compressor.

  Further, the refrigeration cycle apparatus of the present invention includes a check valve disposed downstream of the oil separator and a compressor operating means for stopping one of the two compressors in addition to the above-described configuration. It is.

  As a result, when the required load of the refrigeration cycle apparatus is extremely small, it is possible to operate with only one compressor.

  In addition, the refrigeration cycle apparatus of the present invention includes a condensing temperature detecting means for detecting the discharge pressure or the condenser temperature, an evaporating temperature detecting means for detecting the suction pressure or the evaporator temperature, and a predetermined operating frequency based on the condensing temperature and the evaporating temperature. A refrigerant discharge amount calculating means for calculating the refrigerant discharge amount by calculating a refrigerant discharge amount at the engine frequency and multiplying by a coefficient corresponding to the operating frequency, and a preset refrigerant discharge amount of the compressor and an oil discharge amount with respect to the oil surface height. The compressor operation correction means corrects the operation frequency of the two inverters based on the calculation result of the correlation equation.

  As a result, the refrigerant circulation amount of the refrigeration cycle apparatus can be estimated more accurately, and the oil level height inside the compressor can be accurately estimated based on the correlation equation between the refrigerant discharge amount and the oil level height obtained in advance through experiments. become able to.

  The refrigeration cycle apparatus of the present invention can share these compressors when a single compressor is installed in a refrigeration cycle using two compressors and a refrigeration cycle having half the capacity. A refrigeration cycle apparatus that can be manufactured at low cost can be provided.

  1st invention separated the refrigerant | coolant with the refrigerating cycle which has the structure which connected the two compressors in parallel, the oil separator arrange | positioned at the discharge pipe of each of the said two compressors, and the said oil separator Two oil bypass circuits for returning oil to the suction pipe of the other compressor among the two compressors via a pressure reducing means, and discharge temperatures disposed in the discharge pipes of each of the two compressors A sensor, a bypass circuit temperature sensor disposed downstream of the pressure reducing means of each of the two oil bypass circuits, two inverters for independently controlling the operating frequencies of the two compressors, and the two inverters Compressor operating means for determining the operating frequency of the two inverters, and the operating cycles of the two inverters determined by the compressor controlling means based on the detected temperatures of the discharge temperature sensor and the bypass circuit temperature sensor Since it is equipped with compressor operation correction means that corrects the number, it can be shared with the use of a refrigeration cycle having half the refrigeration capacity constituted by one compressor, and can be manufactured at low cost. A refrigeration cycle apparatus can be provided.

  In particular, the second invention includes, in addition to the configuration of the first invention, a check valve disposed downstream of the oil separator and a compressor operating means for stopping one of the two compressors. As a result, when the required load of the refrigeration cycle apparatus is extremely small, it is possible to operate with only one compressor.

  In particular, the third aspect of the invention includes, in addition to the configuration of the first aspect of the invention, condensing temperature detecting means for detecting discharge pressure or condenser temperature, evaporating temperature detecting means for detecting suction pressure or evaporator temperature, condensing temperature, A refrigerant discharge amount calculating means for calculating a refrigerant discharge amount by calculating a refrigerant discharge amount at a predetermined operating frequency from the evaporation temperature and multiplying by a coefficient corresponding to the operating frequency, and a preset refrigerant discharge amount and oil level of the compressor The compressor operation correction means corrects the operation frequency of the two inverters based on the calculation result based on the correlation equation. The refrigerant circulation amount can be estimated more accurately, and the oil level height inside the compressor can be accurately estimated by a correlation equation between the refrigerant discharge amount and the oil level height obtained in advance through experiments.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a control block diagram of the refrigeration cycle apparatus in the first embodiment of the present invention.

  In FIG. 1, a compressor 1a and an oil separator 2a, a compressor 1b and an oil separator 2b are connected in series, and a four-way valve 3, an outdoor heat exchanger 4, an expansion valve 5 and an indoor heat exchanger 6 are connected in an annular shape. The refrigeration cycle is configured.

  Also, oil bypass circuits 31a and 31b are taken out from the oil separators 2a and 2b, the oil discharged together with the gas refrigerant from the compressors 1a and 1b is separated, and the other opposing one is connected via the decompression means 32a and 32b. It is connected to the suction pipes of the compressors 1b and 1a.

  Discharge temperature sensors 33a and 33b are attached to the discharge pipes of the compressors 1a and 1b to detect the discharge temperature of each compressor.

Further, before the oil bypass circuits 31a and 31b are connected to the suction pipes, bypass circuit temperature sensors 34a and 34b are attached to detect the pipe temperature of each oil bypass circuit. The compressor control means 41 outputs the outputs (compressors) of the inverters 43a and 43b so as to keep the refrigeration capacity of the refrigeration cycle apparatus (for example, the indoor temperature detected by the indoor temperature sensor 44 of the air conditioner) at a predetermined value. Is calculated to operate the two compressors at the same operating frequency.

  The compressor operation correction unit 42 corrects the result calculated by the compressor control unit 41 based on the detection values of the discharge temperature sensors 33a and 33b and the bypass circuit temperature sensors 34a and 34b, thereby converting the inverter 43a, It is comprised so that it may output to 43b.

The operation of the refrigeration cycle apparatus configured as described above will be described below.
Since the configuration of the present embodiment is not a configuration having an overflow pipe on the side surface of the compressor, the oil level in the compressor is determined by the oil discharge amount from the refrigerant discharge pipe and the oil return amount from the refrigerant suction pipe. Is done.

  That is, when the oil discharge amounts of the two compressors are equal and the oil return amount from the suction pipe is equal, the oil levels of the two compressors do not change.

  When the oil levels of the two compressors are equal and maintain an appropriate level, it is preferable to continue the operation state, and the oil levels of the two compressors are biased and the oil level is lowered. When the compressor is in a state that impedes reliability, it is necessary to change the operating state so that the oil level of the compressor is uniform.

  Generally, as shown in FIG. 2, the oil discharge amount of the compressor depends on the internal oil level and the operating frequency, and the oil return amount from the suction pipe tends to depend on the piping shape in the vicinity of the suction pipe. .

  The suction pipe shapes of the two compressors are designed so that the oil return amount is uniform, and if the compressor is operating at the same operating frequency, the oil discharge amount of the compressor with a high oil level is large, In addition, the oil discharge amount of a compressor having a low oil level is reduced.

  In the present embodiment, the oil bypass circuit is configured to return the oil to the suction pipe of the other compressor, and the oil discharge amount of each of the two compressors is further determined to determine the oil discharge amount. Adjust the oil level by returning the oil to the compressor with a low oil level by setting the operating frequency of the compressor with a lot of oil high and conversely setting the operating frequency of the compressor with a small oil discharge rate low. Makes it possible.

  As a means for determining the amount of oil discharged, it is determined whether the fluid flowing from the oil separator to the refrigerant suction pipe of the compressor through the oil bypass circuit is oil or refrigerant. It is determined that the oil discharge amount is large, and conversely, it is determined that the oil discharge amount of the compressor determined to be refrigerant is small, and based on the result, the compressor operation correction means 42 corrects the operation frequency. I am doing so.

  For example, the oil discharged from the compressor 1a is separated from the refrigerant by the oil separator 2a and flows to the suction pipe on the compressor 1b side through the oil bypass circuit 31a, but when the oil discharge amount is small, the oil bypass circuit The fluid flowing through 31a is in the state of gas refrigerant, and in the case of a large oil discharge amount, it is in the oil state.

  The temperature of the fluid immediately after being discharged from the compressor 1a is detected by the discharge temperature sensor 33a, and the temperature of the fluid after passing through the pressure reducing means 32a is detected by the bypass circuit temperature sensor 34b.

When the fluid flowing through the oil bypass circuit 31a is oil with a large oil discharge amount of the compressor 1a, even if the temperature of the fluid passes through the pressure reducing means 32a and is reduced in pressure, the heat release amount is small and the value detected by the discharge temperature sensor 33a When the fluid flowing through the oil bypass circuit 31a is a gas refrigerant, the temperature of the fluid passes through the decompression means 32a and is depressurized to dissipate heat and discharge temperature. The decrement from the value detected by the sensor 33a increases.

  That is, if the detection value of the discharge temperature sensor 33a is T1a, the detection value of the discharge temperature sensor 33b is T1b, the detection value of the bypass circuit temperature sensor 34a is T2a, and the detection value of the bypass circuit temperature sensor 34b is T2b, the compressor 1a The oil discharge amount can be estimated by T1a-T2b, and the oil discharge amount of the compressor 1b can be estimated by T1b-T2a.

  The compressor operation correction means 42 is calculated by the compressor control means 41 when the oil discharge amount of the compressor 1a is large, based on the oil discharge amount of the compressor 1a and the compressor 1b estimated by the above-described operation. A value obtained by adding a positive correction to the operating frequency is output to the inverter 43a, and a value obtained by adding a negative correction is output to the inverter 43b. Conversely, when the oil discharge amount of the compressor 1b is large, A value obtained by adding a positive correction to the operating frequency calculated by the compressor control means 41 is output to the inverter 43b, and a value obtained by adding a negative correction is output to the inverter 43a.

  As described above, in the present embodiment, the oil level of the two compressors can be evenly controlled using the compressor that does not have an overflow pipe on the side of the compressor. It is possible to share a refrigeration cycle apparatus that can be manufactured at a low cost by using the refrigeration cycle with half the refrigeration capacity.

  Further, in the present embodiment, as shown in FIG. 1, a check valve is provided downstream of the oil separator, and compressor operating means for stopping one of the two compressors is provided. When the required load of the cycle device is extremely small, it is possible to operate with only one compressor.

  In the present embodiment, an outdoor heat exchanger temperature sensor that detects the temperature of the outdoor heat exchanger 4 and an indoor heat exchanger temperature sensor that detects the temperature of the indoor heat exchanger 6 are provided, and the four-way valve 3 is cooled. When the four-way valve 3 is on the heating side, the outdoor heat exchanger temperature sensor evaporates when the outdoor heat exchanger temperature sensor is on the side, and the outdoor heat exchanger temperature sensor is the condensation temperature detection means and the indoor heat exchanger temperature sensor is the evaporation temperature detection means. The temperature detection means and the indoor heat exchanger temperature sensor are used as the condensation temperature detection means, and the function F1 (Tc, Te) of the refrigerant discharge amount based on the condensation temperature Tc and evaporation temperature Te of the compressor obtained in advance through experiments as shown in FIG. The refrigerant discharge amount G = F1 (Tc, Te) × F2 (f) is calculated from the function F2 (f) of the coefficient corresponding to the operating frequency f, and two variables of the refrigerant discharge amount G and the oil level height h are calculated. Correlation formula F3 ( H), and the compressor operation correction means corrects the operation frequency of the two inverters based on the calculation result by the correlation formula, so that the oil level inside the compressor is accurately determined. The oil level of the two compressors can be uniformly controlled with higher accuracy.

  As described above, the refrigeration cycle apparatus according to the present invention provides a refrigeration cycle apparatus that can be manufactured at a low cost in common with a case where the refrigeration cycle apparatus according to the present invention is used for a refrigeration cycle having a half refrigeration capacity constituted by one compressor. Therefore, it can be applied to technology development that achieves both expansion of the variable control range of refrigeration capacity and energy saving during low-load operation.

Control block diagram of refrigeration cycle apparatus in Embodiment 1 of the present invention The graph which shows the correlation of the operating frequency of the refrigeration cycle apparatus in Embodiment 1 of this invention, and oil level height The graph which shows the relationship which derives | leads-out oil level height from the evaporation temperature and condensation temperature of the refrigerating-cycle apparatus in Embodiment 1 of this invention. Control block diagram of conventional refrigeration cycle equipment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b Compressor 2a, 2b Oil separator 2 Oil separator 3 Four-way valve 4 Indoor heat exchanger 5 Expansion valve 6 Indoor heat exchanger 11a, 11b Oil bypass circuit 12a, 12b Electromagnetic valve 13a, 13b Pressure reducing means 19a, 19b Check Valve 21 Oil bypass circuit 22 Solenoid valve 23 Pressure reducing means 31a, 31b Oil bypass circuit 32a, 32b Pressure reducing means 33a, 33b Discharge temperature sensor 34a, 34b Bypass circuit temperature sensor 41 Compressor control means 42 Compressor operation correcting means 43a, 43b Inverter 44 Indoor temperature sensor

Claims (3)

A refrigeration cycle having a configuration in which two compressors are connected in parallel, an oil separator disposed in a discharge pipe of each of the two compressors, and oil separated from the refrigerant by the oil separator. Two oil bypass circuits for returning the suction pipes of the other compressor, which are opposite to each other, via a pressure reducing means, discharge temperature sensors disposed in the discharge pipes of the two compressors, and the two A bypass circuit temperature sensor disposed downstream of the decompression means of each oil bypass circuit, two inverters that independently control the operating frequencies of the two compressors, and the operating frequencies of the two inverters are determined. Compensation for the operating frequency of the two inverters determined by the compressor control means by the compressor control means and the detected temperatures of the discharge temperature sensor and the bypass circuit temperature sensor Refrigeration cycle apparatus comprising compressor operation correction means for applying. The refrigeration cycle apparatus according to claim 1, further comprising a check valve disposed downstream of the oil separator and compressor operating means for stopping one of the two compressors. A condensing temperature detecting means for detecting the discharge pressure or the condenser temperature, an evaporating temperature detecting means for detecting the suction pressure or the evaporator temperature, a refrigerant discharge amount at a predetermined operating frequency is obtained from the condensing temperature and the evaporating temperature, and the operating frequency is obtained. Compensation for compressor operation, comprising a refrigerant discharge amount calculation means for calculating a refrigerant discharge amount by multiplying a corresponding coefficient, and a correlation equation between a preset refrigerant discharge amount of the compressor and an oil discharge amount with respect to the oil level height 2. The refrigeration cycle apparatus according to claim 1, wherein the means corrects the operating frequency of the two inverters based on a calculation result of the correlation equation.

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