JP4787794B2 - Oil level detection mechanism and air conditioner in low-pressure vessel compressor - Google Patents

Description

  The present invention relates to an oil level detection mechanism of a lubricating oil storage container in a compressor of a refrigeration apparatus or an air conditioner, and more particularly to a mechanism for detecting an oil level using a temperature sensor.

  As a conventional oil level detection mechanism of this type, as shown in Patent Document 1, for example, a mechanism utilizing the fact that a refrigerant is dissolved in lubricating oil is known. In Patent Document 1, a communication pipe with a heating mechanism is provided between a bottom portion in which a lubricating oil in a compressor container is stored and an upper portion in which refrigerant gas is filled, and the bottom portion and the communication pipe are provided with the bottom portion and the communication pipe. Each of the first and second temperature sensors is arranged, and as a heating mechanism, a heater is connected to the communication pipe, or high-temperature lubricating oil is passed from the oil separator through the capillary tube. The configuration of returning to the communication pipe is introduced.

  According to such a configuration, when the amount of oil is standard, i.e., when the oil level of the lubricating oil in the communication pipe is above the second temperature sensor, the refrigerant dissolved in the lubricating oil evaporates, so the temperature rise is small. Thus, while the temperature difference between the first temperature sensor and the second temperature sensor becomes small, when the oil level is low, that is, when the oil level is below the second temperature sensor, the communication pipe is a gas refrigerant and the temperature rises. The temperature difference between the first temperature sensor and the second temperature sensor increases. From this, it is possible to detect a decrease in the oil level by determining the temperature difference between the first temperature sensor and the second temperature sensor.

  Further, Patent Document 2 provides a bypass path from the high-pressure container of the compressor to the low-pressure refrigerant suction pipe so that the bypass path is closed with lubricating oil when the standard oil amount is used, and is opened when the oil amount is low. In addition, there is described an oil level detection mechanism in which a cooling part is provided in the middle of the bypass path and the cooling part is cooled by a refrigerant from a suction pipe. Then, first and second temperature sensors are provided on the upstream side and the downstream side of the cooling unit on the bypass path, respectively, so that the temperature of the part can be sensed.

According to such a configuration, when the standard oil amount is reached, only the downstream of the bypass path is cooled, and the temperature difference between the first and second temperature sensors is increased. On the other hand, when the oil amount is low, the high-temperature refrigerant from the high-pressure vessel is bypassed. And the entire bypass path is warmed, and the temperature difference between the first and second temperature sensors becomes small. Therefore, the oil level drop can be detected by detecting the temperature difference.
JP 2003-97443 A JP 2004-85083 A

  However, since the conventional ones use two temperature sensors, when the errors of the respective sensors are superimposed, an accurate temperature difference cannot be detected and there is a risk of malfunction. In addition, since a plurality of temperature sensors are used, the cost increases.

  In addition, as in Patent Document 1, the method of heating the communication pipe not only requires a dedicated heating mechanism, resulting in a complicated structure, but also in the presence of lubricating oil, the communication pipe (copper pipe) Since the temperature of the communication pipe rises due to its own heat conduction, there may be a case where a clear temperature difference cannot be obtained as compared with the case where there is no lubricating oil. Furthermore, in the case of heating the communication pipe by returning the oil from the capillary tube, because of the bypass from the high pressure side, even if there is lubricating oil in the communication pipe, the flow of the lubricating oil from the capillary tube occurs in the communication pipe, There is also the risk of detecting high temperatures regardless of the oil level.

  On the other hand, in Patent Document 2, since the bypass is made from the high pressure side (high pressure vessel) to the low pressure side (suction pipe), an energy loss correspondingly occurs, and the efficiency of the entire system such as the refrigeration apparatus and the air conditioner is reduced. There is a problem of inviting.

  In order to solve these problems, the present invention is intended to solve them all at once. The main purpose of the present invention is to provide a simple structure using a single temperature sensor with high accuracy and the efficiency of the entire thermal system. The object is to provide an oil level detection mechanism that does not cause a drop.

  That is, the oil level detection mechanism according to the present invention is used in a low pressure container compressor having a low pressure container for storing lubricating oil and a suction pipe for introducing a refrigerant into the low pressure container. An upper connecting pipe and a lower connecting pipe drawn from an upper position and a lower position of the low-pressure container on the basis of the oil level height at the time of the standard oil amount in the container, the upper connecting pipe and the lower connecting pipe, respectively. A communication pipe having an internal space in which the oil level displacement is the same as the oil level displacement in the low-pressure vessel in the internal space, and a base end portion branches from the suction pipe and a distal end opening is the communication pipe A branch pipe that opens at a position higher than the oil level height at the time of the standard oil amount in the internal space of the engine, and when the standard oil quantity is reached, the lower connecting pipe is filled with lubricating oil to block the refrigerant flow When the oil level is low, Was drained lubricating oil from the pipe is characterized in that so as to circulate coolant therein.

  If this is the case, when the amount of oil is low, the lower connecting pipe is cooled by the flow of the low-temperature refrigerant introduced from the suction pipe, so the temperature of the lower connecting pipe is filled with lubricating oil and the refrigerant flows. It becomes lower than the temperature at the time of standard oil amount that is blocked. Therefore, for example, by monitoring the temperature of the lower connecting pipe at any time with the temperature sensor and detecting the temperature drop, it is possible to accurately detect the oil quantity drop.

  In addition, by adopting time series measurement, the temperature sensor can be integrated into one, and only a branch pipe or connecting pipe is installed, and no other special mechanism such as a heating mechanism is required. It can be realized and cost increase can be suppressed.

  Furthermore, the low-temperature refrigerant in the suction process into the low-pressure container, that is, the refrigerant in the suction pipe is used as a low-temperature heat source for ensuring a temperature difference, and there is no need to provide a bypass passage between high and low pressures as in the prior art. It is possible to prevent performance degradation due to a decrease in the amount of refrigerant circulation in the entire system such as a device or an air conditioner.

  A preferred specific configuration that can be configured with a single temperature sensor and that can be measured in a short time includes a temperature sensor that detects the surface temperature of the lower connecting pipe, and an on-off valve provided in the branch pipe, An oil level judgment means for judging the oil level height of the lubricating oil in the low-pressure vessel based on the detection result of the temperature sensor when the on-off valve is opened and closed is mentioned. Can do. In such a case, at the time of standard oil amount, the lower connecting pipe is closed by the lubricating oil, so that the low temperature gas does not flow through the lower connecting pipe regardless of opening / closing of the on / off valve, and the temperature difference is Although it does not occur, when the amount of oil is low, by opening the on-off valve, low-temperature refrigerant from the suction pipe flows into the lower connection pipe and the temperature decreases in a short time. Temperature difference between the two. Therefore, by monitoring this temperature difference, it is possible to accurately detect the oil level drop.

  If an extremely large amount of refrigerant flows into the lower connecting pipe, the effect of pushing down the oil level due to the dynamic pressure works and causes malfunction. In order to prevent this, optimize the inflow amount of the refrigerant, and improve the oil level detection accuracy, it is preferable to provide a flow rate adjusting unit for adjusting the flow rate of the refrigerant in the branch pipe.

  In order to further reduce the influence of dynamic pressure, it is desirable to set the direction of the distal end opening of the branch pipe to an angle at which no dynamic pressure is directly applied to the oil level in the communication pipe. As the direction, for example, a vertically upward direction is suitable.

  As described above, according to the present invention, the oil level can be detected with high accuracy only by adding a single temperature sensor and a piping structure, and cost increase can be minimized. Furthermore, since there is no bypass path from the high pressure side to the low pressure side, it is possible to prevent performance degradation in the entire system such as the refrigeration apparatus and the air conditioner.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the oil level detection mechanism 4 according to the present embodiment is provided in a low-pressure container compressor 1 that constitutes a power-heat conversion system (not shown) such as a refrigeration apparatus or an air conditioner. More specifically, it is for detecting the lubricating oil surface stored in the low-pressure vessel 2 of the compressor 1.

  First, the low-pressure vessel compressor 1 will be briefly described. The compressor 1 includes a low-pressure vessel 2 in which the internal pressure is set at least lower than the discharge pressure, and the gas refrigerant into the low-pressure vessel 2. A suction port PI that is an inflow port, a compression means (not shown) including a rotary pump disposed inside the low-pressure vessel 2, and a discharge port PO that discharges the refrigerant compressed by the compression means. Is. In FIG. 1, reference numeral 3 denotes a suction pipe for introducing a refrigerant connected to the suction port PI.

  Next, the oil level detection mechanism 4 according to the present embodiment will be described in detail. The oil level detection mechanism 4 is provided in an oil level detection flow path 5 that branches from the suction pipe 3 and communicates with the low pressure vessel 2 in parallel with the suction pipe 3 and the oil level detection flow path 5. A single temperature sensor 6 and an information processing unit 7 are provided.

  The oil level detection flow path 5 includes an upper connection pipe 54 and a lower connection pipe 53 drawn from the low-pressure vessel 2, a communication pipe 52 that connects the upper connection pipe 54 and the lower connection pipe 53, and a suction pipe. The branch pipe 51 is branched from the pipe 3 and connected to the communication pipe 52.

  The upper connection pipe 54 is drawn from a position (upper connection port 54a) higher than the standard oil level H (1) of the low-pressure vessel 2, and in a normal use, the upper connection pipe 54 is placed in the low-pressure vessel 2 in the upper connection pipe 54. It is configured so that the lubricating oil from

  The lower connecting pipe 53 is drawn from a position lower than the standard oil level H (1) of the low-pressure vessel 2. More specifically, at the time of standard oil amount, as shown in FIG. 1, the connection port 53a of the lower connection pipe 53 with respect to the low pressure vessel 2 is completely buried under the oil level H (1), While the side connecting pipe 53 is closed with lubricating oil, when the amount of oil is low, at least a part of the connecting port 53a appears on the oil surface H (2) as shown in FIG. Is configured to open. The connection port 53a is provided at a position as close as possible to the connection port 54a for the low-pressure vessel 2 of the upper connection pipe 54 (for example, substantially directly below).

  The communication pipe 52 has a predetermined length in the vertical direction. The upper connection pipe 54 is connected to the upper end of the communication pipe 52, and the lower connection pipe 53 is connected to the lower end of the communication pipe 52. The oil level displacement is the same as the oil level displacement in the low-pressure vessel 2. In addition, the connection site | part with respect to the said communication pipe | tube 52 of the upper side connection pipe 54 is set above the standard oil level H (1), and as above-mentioned, lubricating oil infiltrates into the upper side connection pipe | tube 54, and it obstruct | occludes. It is configured so that there is no. Moreover, the connection site | part with respect to the said communication pipe | tube 52 of the lower side connection pipe | tube 53 is set below the standard oil level H (1).

  The branch pipe 51 is connected to the communication pipe 52 at its tip opening 51a set at least above the standard oil level H (1), and in a normal use, the branch pipe 51 has a low-pressure container. It is comprised so that the lubricating oil from 2 may not permeate. Further, in this embodiment, the branch pipe 51 is configured to be inserted into the communication pipe 52 from the bottom surface of the communication pipe 52 to form a double pipe structure, and the tip opening 51a is vertically upward. It is set so as to be located in the communication pipe 52. Further, on the branch pipe 51, an on-off valve 55 and a capillary 56 which is a flow rate adjusting unit for adjusting the flow rate of the refrigerant are provided in series.

  The temperature sensor 6 is attached to the outer peripheral surface of the lower connection pipe 53, and the height of the attachment site is set below the standard oil level H (1).

  The information processing unit 7 is physically constituted by an analog electric circuit or a digital electric circuit composed of a CPU, a memory, etc., and the on-off valve that outputs a drive signal of the on-off valve 55 based on the circuit configuration. Drive unit, signal receiving unit that receives an output signal from the temperature sensor 6, a value of the output signal, that is, a storage unit that stores the measured temperature, a measured temperature when the on-off valve 55 is opened, and an on-off valve 55 when the on-off valve 55 is closed Based on each temperature measured by the temperature sensor 6, it functions as an oil level detector for determining the oil level of the lubricating oil in the low pressure vessel 2.

  Next, the operation of the oil level detection mechanism 4 configured as described above will be briefly described.

  The on-off valve 55 is repeatedly opened and closed periodically or irregularly according to a drive signal from the information processing unit 7. The length of the opening period and the closing period is set at least to a time that the temperature of the lower connecting pipe 53 is stabilized to some extent (specifically, 5 minutes to 20 minutes). Then, the signal receiving unit receives the output signal from the temperature sensor 6, and the storage unit acquires a measured temperature (hereinafter also referred to as an open period temperature) acquired at the end of the open period, for example, and a close period following the open time. For example, the measured temperature acquired at the end (hereinafter also referred to as a closing period temperature) is stored.

  At this time, when a standard amount of lubricating oil is stored, as shown in FIG. 1, the lower connecting pipe 53 is closed with the lubricating oil. Therefore, when the on-off valve 55 is opened in this state, the low-temperature refrigerant from the suction pipe 3 flows into the communication pipe 52 through the branch pipe 51, but does not flow into the lower connection pipe 53, but all of the upper connection pipe. 54 is led to the low-pressure vessel 2. Therefore, the temperature of the lower connection pipe 53 hardly changes regardless of whether the on-off valve 55 is opened or closed. FIG. 3 shows a time variation graph of the actually measured temperature. As is apparent from FIG. 3, there is almost no difference between the opening period temperature and the closing period temperature. As a result, the oil level detection unit compares the opening period temperature and the closing period temperature, determines that the difference is smaller than a predetermined value, and outputs a detection signal indicating that the oil level is normal.

  On the other hand, when the amount of oil is low, that is, when the surface of the lubricating oil decreases and becomes lower than the connection port 53a of the lower connection pipe 53, the lubricating oil is discharged from the lower connection pipe 53 as shown in FIG. Thus, the lower connection pipe 53 is opened. Even in this state, when the on-off valve 55 is in the closed state, the low-temperature refrigerant from the suction pipe 3 does not flow into the lower connection pipe 53, so the lower connection pipe 53 is heated from the low-pressure vessel 2. Under the influence of conduction, it is kept at the same temperature as when it is filled with lubricating oil. However, when the on-off valve 55 is opened from this state, the low-temperature refrigerant flows from the suction pipe 3 to the lower connection pipe 53 via the branch pipe 51 and the communication pipe 52, and the upper connection port 54a and the lower connection port 53a. Therefore, the low-temperature refrigerant flows from the upper connection pipe 54 through the low-pressure vessel 2 and flows in, so that the lower connection pipe 53 is rapidly cooled and the temperature is short (5 to 10 minutes). Decrease. FIG. 4 shows a time variation graph of the actually measured temperature. As is apparent from FIG. 4, there is a clear difference between the opening period temperature and the closing period temperature. As a result, the detection output unit compares the open period temperature with the close period temperature, determines that the difference is equal to or greater than a predetermined value, and outputs a detection signal indicating that an abnormal oil level drop has occurred. .

  Therefore, according to the oil level detection mechanism 4 according to this embodiment, as is apparent from FIGS. 3 and 4, the oil level can be detected in a short time and with high accuracy.

  In addition, since temperature comparison is performed by time series measurement, only one temperature sensor 6 is required, and only the oil level detection flow path 5 is provided, and no other dedicated mechanism such as a heating mechanism is required. It can be realized with a simple structure, and the increase in cost can be suppressed.

  Furthermore, the low-temperature refrigerant in the process of sucking into the low-pressure vessel 2 is used as a low-temperature heat source for securing a temperature difference, and there is no need to provide a bypass passage between high and low pressures as in the prior art. Performance degradation of the entire system can be prevented. Furthermore, since there is no energy loss in this way, according to the oil level detection mechanism 4, the oil level can be monitored at intervals of about 10 to 20 minutes which can be said to be always constant, and the reliability is improved. On the other hand, when the bypass passage between the high and low pressures is provided as in the prior art, the performance of the entire system is significantly deteriorated by constantly monitoring the oil level, so at most every 2 to 3 hours. The oil level cannot be monitored. In addition, since the oil level can be constantly monitored, the amount of lubricating oil returned from the oil separator can be feedback controlled to return to the standard oil amount with high accuracy.

  In addition, since the capillary 56 is provided in the branch pipe 51 to optimize the inflow amount of the gas refrigerant, the oil level depression due to the dynamic pressure can be reduced, and the oil level detection accuracy can be improved. In this embodiment, the direction of the tip opening 51a of the branch pipe 51 is set to an angle at which no direct dynamic pressure is applied to the oil level in the communication pipe 52, specifically, vertically upward opposite to the oil level. Thus, the oil level depression due to the dynamic pressure can be further reduced.

The present invention is not limited to the above embodiment.
FIG. 5 shows the most basic configuration of the present invention in which the on-off valve and the flow path adjusting unit are omitted. In the case of such a configuration, the temperature measured by the temperature sensor 6 at the time of the standard oil amount is stored, and the temperature of the lower connecting pipe 53 may be measured and compared as needed based on the temperature. In FIG. 5, the branch pipe 51 is connected to the upper end of the communication pipe 52, and the opening 51a faces downward.

  6 and 7 show an example in which only the on-off valve 55 is provided on the branch pipe 51 in FIG. 5, and an example in which the on-off valve 55 and the flow rate adjusting unit 56 are provided.

  FIG. 8 shows an example in which the branch pipe 51 is connected to the side surface of the communication pipe 52, and the tip opening 51a is oriented horizontally.

  FIG. 9 shows an example in which the branch pipe 51 is inserted from the side surface of the communication pipe 52 and bent inside thereof so that the tip opening 51a is vertically upward. With such a configuration, not only the tip opening 51a can be set in an ideal direction, but also the branch pipe 51 can be inserted into the upper part of the communication pipe 52. Can be prevented. In addition, in FIGS. 5-9 demonstrated above, the same code | symbol is attached | subjected about the member and site | part corresponding to the said embodiment.

  In addition, the flow rate adjusting unit may have not only a choke structure such as a capillary but also a throttle structure, and the flow rate may be made variable using a flow rate adjusting valve.

  In addition, the present invention is not limited to the above-described embodiment and the like, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

  By applying the present invention, it is possible to provide an oil level detection mechanism with a simple structure using a single temperature sensor with high accuracy and without causing a decrease in the efficiency of the entire thermal system.

The schematic diagram which shows the oil level detection mechanism at the time of the standard oil amount in one Embodiment of this invention. The typical schematic diagram which shows the oil level detection mechanism etc. at the time of the low oil amount in the same embodiment. The temperature change graph which shows the time-dependent change of the temperature which arises with opening and closing of the on-off valve at the time of the standard oil amount of the embodiment. The temperature change graph which shows the time-dependent change of the temperature which arises with opening and closing of the on-off valve at the time of the low oil amount of the embodiment. The schematic schematic diagram which shows the oil level detection mechanism etc. in other embodiment of this invention. The schematic schematic diagram which shows the oil level detection mechanism etc. in other embodiment of this invention. The schematic schematic diagram which shows the oil level detection mechanism etc. in other embodiment of this invention. The schematic schematic diagram which shows the oil level detection mechanism etc. in other embodiment of this invention. The schematic schematic diagram which shows the oil level detection mechanism etc. in other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Low pressure vessel type compressor 2 ... Low pressure vessel 3 ... Suction pipe 4 ... Oil level detection mechanism 51 ... Branch pipe 51a ... End opening 52 ... Communication pipe 53 ... Lower connection pipe 54 Upper connection pipe 55 Open / close valve 56 Flow rate adjustment unit (capillary)
6 ... Temperature sensor 7 ... Information processing section H (1) ... Standard oil level

Claims (6)

A low-pressure container for storing the lubricating oil and a low-pressure container type compressor equipped with a suction pipe for introducing a refrigerant into the low-pressure container,
The upper connecting pipe and the lower connecting pipe drawn from the upper position and the lower position of the low pressure container with reference to the oil level height at the time of the standard oil amount in the low pressure container, the upper connecting pipe and the lower side, respectively. A connecting pipe is connected, and a communicating pipe having an internal space in which the same oil level displacement as that in the low-pressure vessel is made in the internal space, a base end portion branches from the suction pipe, and a distal end opening is A branch pipe that is hermetically housed so as to be higher than the oil level height at the time of the standard oil amount in the internal space of the communication pipe, a temperature sensor that detects the surface temperature of the lower connection pipe, and detection of the temperature sensor And an oil level judgment part for judging the oil level height of the lubricating oil in the low-pressure vessel based on the result, and the lower connecting pipe is filled with the lubricating oil when the standard oil amount is reached, and the refrigerant flows. On the other hand, when the oil level is low, the lower connecting pipe It drained lubricating oil oil level detection mechanism, characterized in that so as to circulate coolant therein. Further comprising an on-off valve provided in the branch pipe, and the oil level judgment unit determines the oil level of the lubricating oil in the low-pressure vessel based on the detection results of the temperature sensor when the on-off valve is opened and closed. The oil level detection mechanism according to claim 1, wherein the height is determined .   The oil level detection mechanism according to claim 1, wherein a flow rate adjusting unit that adjusts a flow rate of the refrigerant is provided in the branch pipe.   The oil level detection mechanism according to any one of claims 1 to 3, wherein the direction of the tip opening of the branch pipe is set to an angle that does not directly apply dynamic pressure to the oil level in the communication pipe.   The oil level detection mechanism according to any one of claims 1 to 4, wherein a direction of a tip opening of the branch pipe is set to be vertically upward.   An air conditioner equipped with a low-pressure vessel type compressor having the oil level detection mechanism according to claim 1.