JPH01196473A - Failure diagnosis method for pressure sensor and refrigeration equipment equipped with pressure sensor - Google Patents

Abstract

PURPOSE:To permit the specifying of a faulty pressure sensor through respective detecting values and the average value thereof upon stopping operation, by communicating a refrigerant circulating circuit and a hydraulic pressure circuit with each other in a compressor motor through a bypass circuit. CONSTITUTION:A refrigerating device is provided with a bypass circuit 31, bypassing one part of circulating refrigerant from a refrigerant circulating circuit 6 to circulate it to a motor 2, and a hydraulic pressure circuit 24 is communicated with the bypass circuit 31 in the motor 2 while the hydraulic pressure circuit 24 is also communicated with the refrigerant circulating circuit 6. The average value Pm of four pressure detecting values Pe, Pc, P01, P02 of pressure sensors PS1-PS4, which are attached to respective circuits 6, 24, is operated utilizing a fact that the refrigerant circulating circuit 6 and the hydraulic pressure circuit 24 are maintained in the condition of an equal pressure upon stopping operation. When all of respective pressure sensors are normal, the average value Pm becomes substantially equal to respective detecting values. Diagnosis of trouble in respective pressure sensors PS1-PS4 may be effected by a trouble diagnosis means based on the average value Pm.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method of diagnosing a failure of a pressure sensor in, for example, a centrifugal refrigerator or a screen refrigerator, and a refrigeration system equipped with a pressure sensor.

(Prior Art) For example, the operation of a centrifugal chiller used for air conditioning, etc., is mostly automated, including follow-up control for load fluctuations and start/stop operations. Devices that operate automatically in this way are equipped with various sensors that detect the pressure and temperature of the circulating refrigerant, or the supply pressure of lubricating oil to the compressor motor, and the values detected by these sensors are Operation is performed while confirming that it is within a preset normal operating range. In addition, pages 300 to 301 of "Turbo Refrigerator" [authored by Aki Takada, December 10, 1976, published by the Japan Refrigeration Association] describes, for example, the The causes and remedies are described, but in this way, the operation is controlled based on the values detected by the sensor, and if an abnormality is detected, the operation is automatically stopped before a serious accident occurs. Then, based on the detected value from the sensor, the fault location is discovered and necessary measures are taken.

(Problems to be Solved by the Invention) However, the above-mentioned sensors are naturally not semi-permanent, and their detection accuracy deteriorates after long-term use. If operation is performed based on the values detected by such deteriorated sensors, normal operation cannot be ensured, leading to inefficient operation and even the risk of serious accidents. Become. For this reason, regular inspections are necessary for the sensors mentioned above, but especially if there is not a large error in the early stages of deterioration, it is difficult to determine whether the sensor itself is good or bad. This is not easy and there are a large number of sensors, so in reality, the sensor continues to operate in an inefficient overloaded state that is outside the normal operating range, resulting in a failure, and in the process of investigating the cause, an abnormality in the sensor is discovered. As a result, there is a risk that the life of the entire device will be shortened or, in the case of deterioration of the pressure sensor, an abnormal rise in high pressure will lead to a serious accident.

This invention has been made in view of the above, and its purpose is to provide a failure diagnosis method for pressure sensors that can efficiently diagnose multiple pressure sensors at once and detect deterioration at an early stage. An object of the present invention is to provide a refrigeration system equipped with a pressure sensor that can further improve safety and maintain more efficient operating conditions.

(Means for solving the problem) Therefore, the method for diagnosing a pressure sensor according to the first claim is as follows:
A refrigerant circulation circuit 6 configured by connecting a condenser 4 and an evaporator 5 to the compressor 1, and a hydraulic circuit 2 for lubricating the compressor motor 2.
4, and a bypass circuit 31 for bypassing refrigerant from the refrigerant circulation circuit 6 to the compressor motor 2 in order to cool the compressor motor 2, and detect high and low pressure states in the refrigerant circulation circuit 6, respectively. A plurality of pressure sensors PSI and PS2 are attached to the hydraulic circuit 24.
A method for diagnosing pressure sensors in a refrigeration system in which pressure sensors PS3 and PS4 are installed in a refrigeration system and whose operation is controlled based on the detected values of these pressure sensors PS1 to PS4. At this time, the average of the detection values of the pressure sensors PS1 to PS4 is calculated, and then the absolute value of the difference between this average value and the detection value of each of the pressure sensors PS1 to PS4 is compared with a reference value. It is something.

Further, a refrigeration device equipped with a pressure sensor according to a second claim is provided with:
A refrigerant circulation circuit 6 configured by connecting a condenser 4 and an evaporator 5 to the compressor 1, and a hydraulic circuit 2 for lubricating the compressor motor 2.
4, and a bypass circuit 31 for bypassing refrigerant from the refrigerant circulation circuit 6 to the compressor motor 2 in order to cool the compressor motor 2, and detect high and low pressure states in the refrigerant circulation circuit 6, respectively. A plurality of pressure sensors ps1 and PS2 are attached to the hydraulic circuit 24.
This is a refrigeration system in which pressure sensors PS3 and PS4 are installed in the refrigeration system, and the operation is controlled based on the detection values of these pressure sensors PS1 to PS4, and furthermore, when the operation is stopped and the pressure is equalized, each of the above Calculating means 41 calculates the average of the detected values of the pressure sensors PS1 to PS4, and when the absolute value of the difference between this average value and each of the detected values of the pressure sensors PS1 to PS4 exceeds a reference value, the sensor A fault diagnosis means 42 that outputs an abnormality signal is provided.

(Function) In the above, the refrigerant circulation circuit 6 and the hydraulic circuit 24 are in communication with each other inside the compressor motor 2 through the bypass circuit 31, and therefore the refrigerant circulation circuit 6 and the hydraulic circuit 24 are balanced when the operation is stopped. It becomes a pressure state. Therefore, each detection value and their average value at the time of operation stoppage of the plurality of pressure sensors PS1 to PS4 provided in each of these circuits 6.24 will be the same as the normal value if each pressure sensor is normal. The value is within the allowable detection error range for the pressure sensor. By the way, since it is considered that multiple pressure sensors are unlikely to deteriorate at the same time, the absolute value of the difference between the above average value and each detected value is, for example, the permissible detection error of the above normal pressure sensor. When each of the pressure sensors PS1 to PS4 is smaller than a reference value set as a value corresponding to the pressure sensor PS1 to PS4, it can be assumed that all of the pressure sensors PS1 to PS4 are normal.

On the other hand, the value detected by one of the three or more pressure sensors, for example, pressure sensor PS1, is larger than the reference value, and the other pressure sensors ps2, PS3,
If each detected value in PS4 is within the reference value, it is determined that the detection error of the pressure sensor PSI is increasing and its deterioration is proceeding. In addition, if the degree of deterioration caused by one pressure sensor PSI progresses to zero and the detection error becomes even larger, the absolute value of the difference from the average value for the normal detection value will be the above reference value. In other words, using the above diagnostic method, it is possible to detect a defect in one pressure sensor at an early stage of deterioration, and in this case, it is possible to identify the defective pressure sensor. be able to.

In this way, the quality of the multiple pressure sensors provided in the refrigerant circulation circuit 6 and the hydraulic circuit 24 can be determined all at once, and defects can be detected at an early stage of deterioration, thereby improving safety. It also becomes possible to maintain a more efficient operating state.

(Example) Next, specific examples of the pressure sensor failure diagnosis method and the refrigeration system equipped with the pressure sensor of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing the configuration of a turbo chiller. In the figure, 1 is a turbo compressor, 2 is a liquid-cooled hermetic compressor motor (hereinafter referred to as the motor), and An impeller of the compressor 1 is connected to a rotational drive shaft of the electrically conductive machine 2 via a speed increasing device 3. The compressor 1 has a condenser 4
and the evaporator 5 are connected by refrigerant piping, and a refrigerant circulation circuit 6 is configured in which the refrigerant discharged from the compressor 1 passes through the condenser 4 and the evaporator 5 and returns to the compressor 1. There is. A suction vane 7 is provided on the suction side of the compressor 1 to vary the compression capacity of the compressor 1.

Cooling water flows into the condenser 4 through the cooling water pipe 8.
Further, within the evaporator 5, chilled water to be supplied to the outside for air conditioning, for example, is circulated through chilled water pipes 9, and the high-pressure gas refrigerant flowing from the compressor 1 to the condenser 4 is The refrigerant radiates heat to the cooling water circulating inside the condenser 4 and is condensed, and then this condensed liquid refrigerant is depressurized when being sent to the evaporator 5, where it absorbs heat from the cold water and evaporates. A refrigerant circulation cycle in which the evaporated low-pressure gas refrigerant is returned to the compressor 1 is used to cool the cold water. A cooling water circulation pump 10 is provided in the cooling water pipe 8, and a cold water circulation pump 11 is provided in the cold water pipe 9.

On the other hand, the lower side of the motor housing of the electric motor 2 is configured as an oil tank section, and an oil pump 21 is disposed in this oil tank section.

An oil filter 22 and an oil cooler 23 are sequentially connected to the discharge boat of this oil pump 21, and from this oil cooler 23, bearings and sliding parts of the electric motor 2 and the speed increaser 3 inside the motor housing are connected. A hydraulic circuit 24 is provided which communicates with the electric motor 2 by circulating lubricating oil through the hydraulic circuit 24.
Also, the speed increasing device 3 is lubricated.

Further, in the above device, a bypass circuit 31 is provided that bypasses a part of the circulating refrigerant from the refrigerant circulation circuit 6 and circulates it to the electric motor 2. That is, the liquid reservoir 32 on the lower side of the condenser 4 and the electric motor 2 are connected by a bypass outgoing pipe 33, and the electric motor 2 and the evaporator 5 are connected by a bypass return pipe 34. Therefore, a part of the condensed liquid refrigerant from the liquid reservoir 32 of the condenser 4 flows into the electric motor 2 through the bypass outgoing pipe 33, where it evaporates, and the evaporated gas refrigerant flows from the bypass returning pipe 34 to the evaporator 5. be returned. The electric motor 2 is cooled by this bypass flow. As a result of the circuit configurations described above, the hydraulic circuit 24 communicates with the bypass circuit 31 and the inside of the electric motor 2, and also communicates with the refrigerant circulation circuit 6. Therefore, when the operation is stopped, each of the circuits described above is maintained at the same pressure state, that is, at an equal pressure state.

Note that an oil cooling bypass circuit 35 for circulating refrigerant to the oil cooler 23 is further connected between the liquid reservoir 32 of the condenser 4 and the single generator 5. The oil cooler 23 cools the lubricating oil by exchanging heat with the circulating lubricating oil. Also, in FIG. 1, four pressure sensors PS1, P
S2, PS3, and PS4 are illustrated. The first pressure sensor PS1 is attached to the condenser 4, and the second pressure sensor PS2 is attached to the evaporator 5, respectively, so as to detect the condensing pressure and the evaporating pressure in the refrigerant circulation circuit 6, respectively. The third and fourth pressure sensors PS3 and PS4 are attached to the discharge pipe of the oil pump 21 in the hydraulic circuit 24 and the supply pipe leading from the oil cooler 23 to the electric motor 2, and are connected to the discharge pressure of the oil pump 21, respectively. The lubricating oil supply pressure to the electric motor 2 is detected. Furthermore, in the above device, although not shown in the drawings, temperature sensors for detecting various temperatures, such as discharge gas refrigerant temperature, condensate refrigerant temperature, oil tank temperature, and each inlet and outlet temperature of cooling water and chilled water, are installed at predetermined locations. are placed in each location.

The turbo chiller with the above configuration has an operation control device (not shown)
For example, the operation is performed such that the outlet temperature of chilled water is maintained at a set temperature, but even if the refrigeration load at that time fluctuates, the suction vane 7 is controlled to automatically change the compression capacity. The operation continues while this is being done. During this operation, the pressure and temperature detected by each of the pressure sensors and temperature sensors are input to the operation control device, and these detected values are constantly monitored to see if they are within normal ranges. ing. If the device deviates from the normal range, it will automatically stop operation and display an abnormality message to the user. In this way, the operating status is detected using various sensors, and the system automatically stops when an abnormality occurs, thereby preventing the risk of serious accidents.

Further, in the above embodiment, as described above, the refrigerant circulation circuit 6 and the hydraulic circuit 24 are connected to each circuit 6, 24 by taking advantage of the fact that the pressure is maintained in an equal pressure state when the operation is stopped. The pressure sensors Psi to PS4 are equipped with a function of automatically performing failure diagnosis of the pressure sensors Psi to PS4, and this function will be explained below with reference to the flowchart of FIG.

When the operation start switch is operated by the user, the operation control device first starts each of the pressure sensors PS1 to PS4 as shown in step S1 before starting the electric motor 2, oil pump 21, etc. Detected values, that is, the internal pressure Pe of the evaporator 5, the internal pressure Pc of the condenser 4, and the pressure P in the discharge pipe of the oil pump 21 in the hydraulic circuit 24.
O1 and the pressure PO2 in the piping from the oil cooler 23 to the electric motor 2 are read.

Next, in step S2 constituting the calculation means 41, the four pressure detection values Pe, Pc, POI,
The average of PO2 (iPm is calculated. As mentioned above, the refrigerant circulation circuit 6 and the hydraulic circuit 24 are maintained at an equal pressure state when the operation is stopped until they are started, so the above four detections The values Pe, Pc, POI, PO2 are
When the pressure sensors Psi, PS2, PS3, and PS4 are all normal, they are each read as a negative value, and more specifically, as a value within the detection error range allowed during normal operation. Therefore, the above-mentioned average value Pm also becomes a value between each detected value and the path when all the pressure sensors are normal. Based on this average value Pm, each of the pressure sensors PSI, PS2, PS3 is
, a failure diagnosis of the PS4 is performed. That is, step S
3, the absolute value of the difference between Pe and Pm is compared with a reference value E. This reference value E is set in advance to a value equivalent to the permissible detection error in normal conditions. At this time, four pressure sensors Psi, PS2, PS3, P
If S4 is all normal, the average value P
Since m is also the value between each detected value and the road distance, the above Pe and Pn
The absolute value of the difference from + becomes a value smaller than the above-mentioned tolerance E, and then the process moves to step S4, and then to step S5.
, S6, similarly to the above, each detected value Pc, POI,
The absolute value of the difference between PO2 and the average pH1 is sequentially compared with the reference value E, and if each is below the reference value E, all pressure sensors Psi, PS2, PS3, P
After determining that S4 is normal, the compressor 1, oil pump 21, etc. are started to start operation.

By the way, it is considered that it is almost impossible for a plurality of pressure sensors to deteriorate at exactly the same time, so one of the four pressure sensors Psi, PS2, PS3, PS4, for example pressure sensor PS1, gradually deteriorates. To explain the case of deterioration, the detected value Pe gradually becomes a value that is different from the detected values Pc, POI, PO2 of the other three normal pressure sensors PS2, PS3, PS4. It will be shown. The average value Pm at this time is given by a value shifted from the average of the three detected values Pc, POI, and PO2 on the normal side to the Pe side by one quarter of the difference between this average and Pe. Therefore, when the deterioration of the pressure sensor PS1 gradually progresses, both the difference between the average value Pm and the detected value on the normal side and the difference between the average value Pm and the detected value on the deteriorated side become larger. However, at the initial stage, when the normal side is within the reference value E, the deteriorated side will go through a state where it becomes larger than the reference value E. At this stage, it is determined in step S3 that the pressure sensor PS1 which has progressed to deterioration is defective. Displays a defect and maintains the stopped state of operation. In addition, other pressure sensors PS2, P
For S3 and PS4, each of the above steps S4
, S5, and S6, the process proceeds to steps S8, S9, and SIO, respectively, where a defective display is performed and the stopped state of operation is maintained.

As described above, in the above embodiment, the refrigerant circulation circuit 6 and the hydraulic circuit 24 are provided in each circuit 6 and 24, taking advantage of the fact that they are in an equal pressure state when the operation is stopped. Four pressure sensors Psi, PS2, PS
3. PS4 failure diagnosis is performed all at once at each startup. Moreover, the failure diagnosis can be performed for each pressure sensor P immediately before startup.
The detected values at S1, PS2, PS3, and PS4 are input to the operation control device only once, and based on the detected values at that time, the operation control device performs arithmetic processing in, for example, a microcomputer, in a very short period of time. It is possible to do so. Since defects can be detected at an early stage of deterioration, safety is improved and more efficient operating conditions can be maintained.

Note that the above embodiments do not limit the present invention, and various changes can be made within the scope of the present invention. For example, in the above embodiments, the reference value is set to a value equivalent to the permissible detection error E of the pressure sensor under normal conditions. However, it is also possible to set a different value as appropriate. In addition, although the above description has been made using a turbo chiller as an example, the present invention can be applied and configured in other refrigeration equipment, and in particular, pressure equalization of high and low pressure states occurs in a short time after the operation is stopped. It also provides a remarkable effect in screw refrigerators and the like. Further, in the above embodiment, a device equipped with four pressure sensors has been described, but the present invention can be applied to a device equipped with three or more pressure sensors.

(Effects of the Invention) As described above, in the pressure sensor failure diagnosis method and the refrigeration system equipped with the pressure sensor of the present invention, the quality of the plurality of pressure sensors provided in the refrigerant circulation circuit and the hydraulic circuit can be determined all at once. This can be done automatically, and defects can be detected at an early stage of deterioration, improving safety.
It also becomes possible to maintain more efficient operating conditions.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the overall configuration of a centrifugal chiller according to an embodiment of the present invention, and FIG. 2 is a control flowchart showing an example of the pressure sensor failure diagnosis method of the present invention. 1... Compressor, 2... Electric motor, 4... Condenser, 5
... Evaporator, 6... Refrigerant circulation circuit, 24... Hydraulic circuit, 31... Bypass circuit, 41... Calculating means,
42...Fault diagnosis means.

Claims (1)

[Claims] 1. A refrigerant circulation circuit (6) configured by connecting a condenser (4) and an evaporator (5) to a compressor (1), and a compressor electric motor (
a hydraulic circuit (24) for lubricating the compressor motor (2); and a bypass circuit (31) for bypassing refrigerant from the refrigerant circulation circuit (6) to the compressor motor (2) to cool the compressor motor (2). and the refrigerant circulation circuit (6).
Multiple pressure sensors that detect high and low pressure states (
PS1) (PS2) and the above hydraulic circuit (
24) also install pressure sensors (PS3) (PS4),
A method for diagnosing a failure of a pressure sensor in a refrigeration system whose operation is controlled based on the detection values of these pressure sensors (PS1) to (PS4), in which each of the pressure sensors (PS1) to (PS4) is The average of the detected values at PS1) to (PS4) is calculated, and then the absolute value of the difference between this average value and each detected value at each of the above pressure sensors (PS1) to (PS4) is compared with a reference value. A method for diagnosing a failure of a pressure sensor, characterized in that: 2. A refrigerant circulation circuit (6) configured by connecting a condenser (4) and an evaporator (5) to a compressor (1), and a compressor electric motor (
a hydraulic circuit (24) for lubricating the compressor motor (2); and a bypass circuit (31) for bypassing refrigerant from the refrigerant circulation circuit (6) to the compressor motor (2) to cool the compressor motor (2). and the refrigerant circulation circuit (6).
Multiple pressure sensors that detect high and low pressure states (
PS1) (PS2) and the above hydraulic circuit (
24) also install pressure sensors (PS3) (PS4),
It is a refrigeration system whose operation is controlled based on the detection values of these pressure sensors (PS1) to (PS4), and furthermore, when the operation is stopped and the pressure is equalized, each of the pressure sensors (PS4) is
a calculation means (41) that calculates the average of the detected values at PS1) to (PS4);
1) A pressure sensor characterized in that it is provided with a failure diagnosis means (42) that outputs a sensor abnormality signal when the absolute value of the difference with each detected value in (PS4) exceeds a reference value. Equipped with refrigeration equipment.