CONTROL DEVICE, COMPRESSION SYSTEM AND CONTROL METHOD

Abstract

A control device is provided, comprising: a control unit configured to, when a solenoid valve provided in a circuit through which oil discharged from a compressor together with a refrigerant is returned to the interior of the compressor, turn on or off depending on an amount of oil inside the compressor, turn on the solenoid valve when the amount of oil is equal to or less than a first threshold, and turn off the solenoid valve when the amount of oil is equal to or greater than a second threshold that is greater than the first threshold and an elapsed time after the solenoid valve is turned on exceeds a minimum on time.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a control device, a compression system and a control method.

[0002] Priority is claimed for Japanese Patent Application No. 2022-198499, filed on December 13, 2022, the contents of which are hereby incorporated by reference. STATE OF THE ART

[0003] In an air conditioning machine described in Patent Document 1, a predetermined plurality of types of oil return conditions are set, and when one of the oil return conditions is met, an oil return operation is started to collect lubricating oil flowing through one side of the refrigerant circuit and secure a predetermined amount of oil in a compressor. Furthermore, in this air conditioning machine, the oil return operation is terminated when a predetermined end condition is met. Furthermore, in this air conditioning machine, when the oil return operation is performed under the oil return condition where an outside air temperature is high, the execution of the oil return operation is prohibited for a certain time. Citation listPatent document

[0004] Patent Document 1: Unexamined Japanese Patent Application, First Publication No. 2011-149659 SUMMARY OF THE INVENTIONTechnical Problem

[0005] Meanwhile, among the many types of oil return conditions described in Patent Document 1, there are some conditions where the frequency of start and stop is not limited. Therefore, there is a problem that, depending on the operating situation or the like, the start and stop of the oil return operation may be repeated frequently.

[0006] The present disclosure has been made to solve the above-described problem, and an object of the present disclosure is to provide a control device, a compression system, and a control method capable of reducing an execution frequency of an oil return operation. Solution to the problem

[0007] To solve the above-described problem, according to the present disclosure, there is provided a control device comprising: a control unit configured to, when a solenoid valve provided in a circuit through which oil discharged from a compressor together with a refrigerant is returned to an interior of the compressor, turn on or off depending on an amount of oil inside the compressor, turn on the solenoid valve when the amount of oil is equal to or less than a first threshold, and turn off the solenoid valve when the amount of oil is equal to or greater than a second threshold that is greater than the first threshold and an elapsed time after the solenoid valve is turned on exceeds a minimum on-time.

[0008] According to the present disclosure, a compression system is provided, comprising: a compressor configured to compress a refrigerant and discharge the refrigerant along with oil stored in the compressor; a tank configured to store the oil separated from the refrigerant;and a control unit configured to, when a solenoid valve provided in a circuit through which the oil is returned from the tank to the interior of the compressor is turned on or off depending on an amount of oil inside the compressor, turn on the solenoid valve when the amount of oil is equal to or less than a first threshold, and turn off the solenoid valve when the amount of oil is equal to or greater than a second threshold that is greater than the first threshold, and an elapsed time after turning on the solenoid valve exceeds a minimum on time;

[0009] According to the present disclosure, there is provided a control method comprising: when a solenoid valve provided in a circuit through which oil discharged from a compressor together with a refrigerant is returned to the interior of the compressor, is turned on or off depending on an amount of oil inside the compressor, turning on the solenoid valve when the amount of oil is equal to or less than a first threshold; and turning on the solenoid valve when the amount of oil is equal to or greater than a second threshold that is greater than the first threshold and an elapsed time after turning on the solenoid valve exceeds a minimum on time. Advantageous effects of the invention

[0010] According to a control device, a compression system, and a control method of the present disclosure, it is possible to reduce the execution frequency of an oil return operation. BRIEF DESCRIPTION OF THE DRAWINGS [ Fig. 1] A diagram showing a configuration example of a compression system according to an embodiment of the present disclosure. [ Fig. 2] A flowchart showing an operation example of the compression system according to the embodiment of the present disclosure. [ Fig. 3] A timing chart showing an operation example of the compression system according to the present embodiment. [ Fig. 4] A flowchart showing another operation example of the compression system according to the present embodiment. [ Fig. 5] A schematic block diagram showing a configuration of a computer according to at least one embodiment. DESCRIPTION OF THE EMBODIMENTS

[0011] Hereinafter, a control device, a compression system and a control method according to an embodiment of the present disclosure will be described with reference to Fig. 1 to 4 described. Fig. 1 is a diagram showing a configuration example of the compression system according to an embodiment of the present disclosure. Fig. 2 is a flowchart showing an operation example of the compression system according to the present embodiment. Fig. 3 is a timing chart showing an operation example of the compression system according to the embodiment of the present disclosure. Fig. 4 is a flowchart showing another example of operation of the compression system according to the present embodiment. In each drawing, the same reference numerals are used for the same or corresponding components, and descriptions thereof are omitted where appropriate. (Compression system configuration)

[0012] The Fig. The compression system 1 shown in FIG. 1 is, for example, a compression system provided in a large-capacity CO2 refrigeration device, and includes a high-pressure compressor 11, a low-pressure compressor 21, a control board 3, a separator 4, an oil tank 5, a normal oil return circuit 61, a return oil amount adjustment capillary circuit 63, a normal oil return circuit 71, a return oil amount adjustment capillary circuit 73, a peripheral device thereof, and the like. In the present embodiment, the refrigerant is carbon dioxide. However, the embodiment of the present disclosure is not limited thereto.

[0013] The high-pressure compressor 11 is a compressor that compresses a refrigerant, and to which an oil capsule 12, which stores oil (also called lubricating oil, refrigeration oil, or the like) with which an interior of the high-pressure compressor 11 is filled, is connected through a pipe 13. An oil level in the oil capsule 12 corresponds to the oil level in the high-pressure compressor 11. The oil level in the oil capsule 12 is detected by a level sensor 14. The refrigerant compressed by the low-pressure compressor 21 is introduced into the high-pressure compressor 11 via a charge air cooler, an accumulator, a capillary, a strainer, etc. (not shown).

[0014] The low-pressure compressor 21 is a compressor that compresses the refrigerant and is connected to an oil capsule 22, which stores oil with which the interior of the low-pressure compressor 21 is filled, via a line 23. The oil level in the oil capsule 22 corresponds to the oil level in the low-pressure compressor 21. The oil level in the oil capsule 22 is measured by a level sensor 24. The refrigerant is supplied to the low-pressure compressor 21 via a pressure accumulator or the like (not shown).

[0015] The oil is discharged from the high-pressure compressor 11 along with the refrigerant. The oil discharged along with the refrigerant is separated by the separator 4, and the separated oil is stored in the oil tank 5. The oil stored in the oil tank 5 is returned to the high-pressure compressor 11 and the low-pressure compressor 21 via the normal oil return circuit 61 and the normal oil return circuit 71. In addition, the amount of oil discharged from the high-pressure compressor 11 and the low-pressure compressor 21 changes due to startup of the high-pressure compressor 11 and the low-pressure compressor 21 or load fluctuation.For example, in a case where oil cannot be returned through the normal oil return circuit 61 and the normal oil return circuit 71, the return oil amount is adjusted by controlling the opening and closing of a solenoid valve 64 or a solenoid valve 74 provided in the return oil amount adjustment capillary circuit 63 or the return oil amount adjustment capillary circuit 73. In the present embodiment, turning on the solenoid valve 64 or the solenoid valve 74 corresponds to an oil return operation.

[0016] The separator 4 and the oil tank 5 are connected to each other by a pressure equalization line 41. The normal oil return circuit 61 contains a capillary 62. The normal oil return circuit 71 contains a capillary 72. The return oil quantity adjustment capillary circuit 63 contains the solenoid valve 64 and a capillary 65. The return oil quantity adjustment capillary circuit 73 contains the solenoid valve 74 and a capillary 75. The solenoid valve 64 is controlled to open and close by the control board 3. The opening and closing of the solenoid valve 74 is controlled by the control board 3. A detection signal indicating an oil level detected by the level sensor 14 is output to the control board 3. A detection signal indicating an oil level detected by the level sensor 24 is output to the control board 3.

[0017] On the other hand, the control board 3 controls each unit of the compression system 1 (or a refrigerator including the compression system 1). The control board 3 is an embodiment of a control device according to the present disclosure. In the present embodiment, the control board 3 includes a solenoid valve control unit 31, a solenoid valve control unit 32, a time update unit 33, and a time update unit 34.

[0018] The solenoid valve control unit 31 controls the opening and closing (turning on and off) of the solenoid valve 64 based on a detection signal from the level sensor 14. The detection signal from the level sensor 14 is, for example, a signal indicating the oil level. The oil level can be converted into the oil quantity based on the internal structure of the high-pressure compressor 11. Therefore, the solenoid valve control unit 31 can turn the solenoid valve 64 on or off according to the oil quantity in the high-pressure compressor 11, or turn the solenoid valve 64 on or off according to the oil level. For example, the solenoid valve control unit 31 turns the solenoid valve 64 on when the oil quantity is equal to or less than a first threshold value corresponding to a dry oil level.Furthermore, the solenoid valve control unit 31 turns off the solenoid valve 64, for example, when the oil amount is equal to or greater than a second threshold corresponding to a full oil level, which is greater than the first threshold corresponding to the dry oil level, and an elapsed time after the solenoid valve 64 is turned on exceeds the minimum ON time. The minimum ON time is a value determined based on an upper limit number (the number of continuous operations) of an ON / OFF cycle of the solenoid valve 64 and a predicted operating time of the solenoid valve 64. The predicted operating time is as follows. The predicted operating time is a normal replacement time or a product life (or service life) of the solenoid valve 64, or a product life of the high-pressure compressor 11.The minimum on-time is set such that a value resulting from dividing the predicted operating time by the minimum on-time does not exceed the upper limit number (the number of lifetimes) of the on-and-off cycle of the solenoid valve 64.

[0019] Furthermore, the time update unit 33 updates the minimum on-time in the solenoid valve control unit 31 when a predetermined update condition is met. The update condition may be, for example, that an elapsed time from a time of factory shipment or the previous update of the minimum on-time, or an operation time from the previous update of the minimum on-time of the high-pressure compressor 11 reaches a predetermined time, and the like. The time update unit 33 updates the minimum on-time such that a value obtained by dividing the predicted operation time at a time when the update condition is met by the minimum on-time does not exceed the upper limit number (the number of durability times) of the on-and-off cycle of the solenoid valve 64.

[0020] In addition, the solenoid valve control unit 32 controls the opening and closing of the solenoid valve 74 (controls the turning on or off of the solenoid valve 74) based on a detection signal of the level sensor 24 in the same manner as the solenoid valve control unit 31. In addition, the time updating unit 34 updates the minimum turn-on time in the solenoid valve control unit 32 in a case where a predetermined update condition is satisfied, in the same manner as the time updating unit 33. (Operating example of a compression system)

[0021] An operation example of the solenoid valve control unit 31 and the time update unit 33 in the compression system 1 will be described with reference to FIG. Fig. 2 to 4. The operations of the solenoid valve control unit 32 and the time update unit 34 are the same as the operations of the solenoid valve control unit 31 and the time update unit 33.

[0022] One in Fig. The process shown in Figure 2 is carried out repeatedly within a specified period of time after activation of the control board 3. In a case where the Fig. 2 is started, the solenoid valve control unit 31 determines whether the solenoid valve 64 is off or not (in a closed state) (S11). In a case where the solenoid valve 64 is off (YES in S11), the solenoid valve control unit 31 determines whether a state in which an oil level is equal to or less than a dry oil level continues for a predetermined time or longer (S12). Continuing for the predetermined time or longer ensures that the state in which the oil level is equal to or less than the dry oil level is stable. If the state in which the oil level is equal to or less than the dry oil level continues for the predetermined time or longer (YES in S12), the solenoid valve control unit 31 turns on the solenoid valve 64 (establishes an open state) (S13) and ends the process in Fig. 2. In a case where the state in which the oil level is equal to or less than the dry oil level does not continue for the predetermined time or longer (NO in S12), the solenoid valve control unit 31 terminates the process shown in Fig. 2 process shown.

[0023] On the other hand, when the solenoid valve 64 is turned on (NO in S11), the solenoid valve control unit 31 determines whether a state in which the oil level is equal to or greater than the full oil level continues for a predetermined time or longer (S14). For the solenoid valve control unit 31, in a case where the state in which the oil level is equal to or greater than the full oil level continues for the predetermined time or longer (YES in S14), the solenoid valve control unit 31 determines whether an on-time (elapsed time after turning on) of the solenoid valve 64 is equal to or greater than the minimum on-time (S15). If the on-time of the solenoid valve 64 is equal to or greater than the minimum on-time (YES in S15), the solenoid valve control unit 31 turns off the solenoid valve 64 (sets a closed state) (S16) and ends the Fig. 2. In a case where the state in which the oil level is equal to or greater than the full oil level does not last for the predetermined time or longer (NO in S14), or in a case where the ON time of the solenoid valve 64 is not equal to or greater than the minimum ON time (NO in S15), the solenoid valve control unit 31 ends the process shown in Fig. 2 process shown.

[0024] Fig. Figure 3 shows an example of an oil quantity and a solenoid valve operation. In the Fig. In the example shown in Figure 3, the oil quantity is in a dry oil level state at time t1, and the solenoid valve 64 is switched on at time t2 after a predetermined time has elapsed. At time t3, the oil quantity is then in a full oil level state. At time t3, the minimum switch-on time since time t2 has not yet elapsed. At time t4, the minimum switch-on time has elapsed, and the solenoid valve 64 is switched off.

[0025] Furthermore, at time t5, the oil quantity is in the dry oil level state, and the solenoid valve 64 is turned on at time t6. At time t7, the minimum turn-on time has elapsed, and the oil quantity is not yet in the full oil level state. At time t8, the oil quantity is in the full oil level state, and the solenoid valve 64 is turned off at time t9 after a predetermined time has elapsed.

[0026] As in Fig. As shown in Figure 3, the oil quantity is in the full oil level state at time t3, and the solenoid valve 64 is not deactivated at this time, but the oil quantity continues to increase. An increase in the oil quantity beyond the full oil level state reduces the compression efficiency of the high-pressure compressor 11. Since the frequency of on-off operation of the solenoid valve 64 can be reduced, the service life of the solenoid valve 64 can be maintained at a predetermined value.

[0027] Next, an operation example of the time update unit 33 will be described with reference to Fig. 4. A Fig. The process shown in Fig. 4 is repeatedly executed in a predetermined period of time after activation of the control board 3. In a case where the Fig. 4 is started, the time update unit 33 determines whether a predetermined update condition is met or not (S21). In a case where the update condition is met, the time update unit 33 calculates the minimum on-time based on, for example, a drive time of the compressor, an assumed remaining drive time, the number of openings and closings of the solenoid valve, and an upper limit of the number of openings and closings of the solenoid valve, updates a target value of the minimum on-time (S22), and ends the process shown in Fig. 4 process shown. (Actions and effects)

[0028] In the present embodiment, a solenoid valve control unit is configured to turn on or off a solenoid valve provided in a circuit through which oil discharged from a compressor, along with refrigerant, is returned to the compressor interior depending on the amount of oil in the compressor. The solenoid valve is turned on when the oil amount is equal to or less than a first threshold, and to turn off the solenoid valve when the oil amount is equal to or greater than a second threshold that is greater than the first threshold, and an elapsed time after the solenoid valve is turned on exceeds a minimum on time. With this configuration, it is possible to reduce the frequency of performing an oil return operation (turning on and off of the solenoid valve 64 and the solenoid valve 74, which are the oil return valves). (Other embodiments)

[0029] The embodiment of the present disclosure is described above in detail with reference to the drawings, and specific configurations are not limited to the embodiment and include a design change or the like within a scope that does not deviate from the gist of the present disclosure. <computer-konfiguration>

[0030] Fig. 5 is a schematic block diagram showing a configuration of a computer according to at least one embodiment.

[0031] A computer 90 includes a processor 91, a main memory 92, a storage 93, and an interface 94.

[0032] The above-described control board 3 is implemented in the computer 90. The operation of each unit described above is stored in the memory 93 in the form of a program. The processor 91 reads the program from the memory 93, stores the program in the main memory 92, and executes the above-described process according to the program. Furthermore, the processor 91 saves a memory area in the main memory 92 corresponding to each unit described above, according to the program.

[0033] The program may partially execute functions performed by the computer 90. For example, the program may execute the functions in combination with another program already stored in memory or in combination with another program installed in another device. In another embodiment, the computer may include, in addition to the configuration described above or instead of the configuration described above, a customized large-scale integrated circuit (LSI) such as a programmable logic device (PLD). A programmable array logic (PAL), a generic array logic (GAL), a complex programmable logic device (CPLD), a field programmable gate array (FPGA), and the like are exemplary examples of a PLD. In this case, part or all of a function realized by a processor may be realized by the integrated circuit.

[0034] Examples of memory 93 include a hard disk drive (HDD), a solid-state drive (SSD), a magnetic disk, a magneto-optical disk, a compact disc read-only memory (CD-ROM), a digital versatile disc read-only memory (DVD-ROM), and a semiconductor memory. Memory 93 may be an internal medium connected directly to a bus of computer 90 or an external medium connected to computer 90 via interface 94 or a communications line. When this program is distributed to computer 90 via the communications line, computer 90, having received the distributed program, may deploy the program in main memory 92 to perform the process described above. In at least one embodiment, memory 93 is a non-transitory, tangible storage medium. <Anhänge>

[0035] The control device (control board 3) described in the individual embodiments is to be understood as follows, for example: (1) According to a first aspect, there is provided a control device (control board 3) comprising: a control unit (solenoid valve control units 31 and 32) configured to, when solenoid valves 64 and 74 provided in a circuit (return oil amount adjustment capillary circuits 63 and 73) through which oil discharged together with a refrigerant from a compressor (high-pressure compressor 11 and low-pressure compressor 21) is returned to the interior of the compressor, turn on or turn off depending on an amount of oil in the compressor, turn on the solenoid valve when the amount of oil is equal to or less than a first threshold, and turn off the solenoid valve when the amount of oil is equal to or greater than a second threshold that is greater than the first threshold, and an elapsed time after the solenoid valve is turned on exceeds a minimum on time.With the present aspect and each of the following aspects, it is possible to reduce the execution frequency of an oil return operation (turning on and off operation of the solenoid valve 64 and the solenoid valve 74, which are the oil return valves). (2) A control device (control board 3) according to a second aspect is the control device (control board 3) according to (1), in which the minimum duty cycle is a value determined based on an upper limit for the number of on-off cycles of the solenoid valve and a predicted operating time of the solenoid valve. With this aspect, for example, a maintenance frequency of the control valve can be reliably reduced. (3) A control device (control board 3) according to a third aspect is the control device (control board 3) according to (1) or (2), in which the minimum duty cycle is updated when a predetermined update condition is met. With this aspect, it is possible to appropriately achieve both a reduction in frequency and suppression of a decrease in compressor efficiency. (4) According to a fourth aspect, there is provided a compression system comprising: a compressor (high-pressure compressor 11 and low-pressure compressor 21) configured to compress a refrigerant and discharge the refrigerant together with oil stored in the compressor; a tank (oil tank 5) configured to store the oil separated from the refrigerant;and a control unit (solenoid valve control units 31 and 32) configured to, when solenoid valves 64 or 74 provided in a circuit (return oil amount adjustment capillary circuits 63 and 73) through which the oil is returned from the tank to the interior of the compressor are turned on or off according to an amount of oil inside the compressor, turn on the solenoid valve when the oil amount is equal to or less than a first threshold, and turn off the solenoid valve when the oil amount is equal to or greater than a second threshold that is greater than the first threshold, and an elapsed time after the solenoid valve is turned on exceeds a minimum on time; (5) According to a fifth aspect, there is provided a control method comprising: when a solenoid valve provided in a circuit through which oil discharged from a compressor together with a refrigerant is returned to the inside of the compressor, is turned on or off depending on an amount of oil inside the compressor, turning on the solenoid valve when the amount of oil is equal to or less than a first threshold; and turning off the solenoid valve when the amount of oil is equal to or greater than a second threshold which is greater than the first threshold and an elapsed time after the solenoid valve is turned on exceeds a minimum on time. INDUSTRIAL APPLICABILITY

[0036] With the aspect described above, it is possible to reduce the frequency of execution of an oil return operation. REFERENCE SYMBOL LIST 1 compression system 11 High-pressure compressor 12 oil capsules 21 Low-pressure compressor 22 oil capsules 14, 24 Oil level sensor 3 Control board 31 Solenoid valve control unit 32 Solenoid valve control unit 33 Time update unit 34 Time update unit QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2022-198499

[0002] JP 2011-149659

[0004]

Claims

[1] A control device comprising: a control unit configured to when a solenoid valve provided in a circuit through which oil discharged from a compressor together with a refrigerant is returned to an interior of the compressor is switched on or off depending on an amount of oil in the compressor, the solenoid valve switches on when the oil quantity is equal to or less than a first threshold value and the solenoid valve switches off when the oil quantity is equal to or greater than a second threshold which is greater than the first threshold and an elapsed time after switching on the solenoid valve exceeds a minimum switch-on time. [2] The control device according to claim 1, wherein the minimum on-time is a value determined based on an upper limit number for the number of on-and-off cycles of the solenoid valve and a predicted operation time of the solenoid valve. [3] The control device according to claim 1 or 2, wherein the minimum on-time is updated in a case where a predetermined update condition is satisfied. [4] A compression system comprising: a compressor configured to compress a refrigerant and discharge the refrigerant together with oil stored in the compressor; a tank configured to store the oil separated from the refrigerant; and a control unit configured to when a solenoid valve provided in a circuit through which the oil is returned from the tank to the interior of the compressor is switched on or off depending on the amount of oil in the compressor, the solenoid valve switches on when the oil quantity is equal to or less than a first threshold value, and the solenoid valve switches off when the oil quantity is equal to or greater than a second threshold which is greater than the first threshold and an elapsed time after switching on the solenoid valve exceeds a minimum switch-on time. [5] A control method comprising: when a solenoid valve provided in a circuit through which oil discharged from a compressor together with a refrigerant is returned to the interior of the compressor is switched on or off depending on an amount of oil in the compressor, Switching on the solenoid valve in a case where the oil quantity is equal to or less than a first threshold value; and Turning off the solenoid valve in a case where the oil quantity is equal to or greater than a second threshold value which is greater than the first threshold value and an elapsed time after turning on the solenoid valve exceeds a minimum on time.

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