JP2011089714A - Refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve convergency of an operation capacity in a refrigerating device including a variable capacity type compressor. <P>SOLUTION: The refrigerating device is composed by including at least one variable capacity type compressor varying an operation capacity in a compression part of a refrigerating cycle, or alternatively, the refrigerating device is composed by including at least one variable capacity type compressor varying an operation capacity and at least one constant speed compressor with a certain operation capacity in the compression part of the refrigerating cycle. It includes a pressure sensor detecting a low pressure of the refrigerating cycle, and a controller determining change characteristics of an operation capacity of the compression part with respect to a pressure difference between a pressure value detected by the pressure sensor and a preset target low pressure. In the controller, fluctuation of the low pressure is monitored, and the change characteristics of the operation capacity is adjusted on the basis of determination with respect to a fluctuation state of the low pressure. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a refrigeration apparatus including a variable capacity compressor that can change an operating capacity.

  The conventional refrigeration apparatus calculates a reference low pressure from the current low pressure and the past low pressure, as in Patent Document 1, for example, and determines the operating capacity of the compressor so that the low pressure becomes a preset value. It was.

JP 2008-309383 A

  However, in the refrigeration apparatus of Patent Document 1, since the change rate of the operating capacity is calculated by a preset calculation formula based on the change tendency of the low pressure, depending on the characteristics of the low pressure device unit and the installation environment of the refrigeration apparatus, Convergence of the operating capacity may be deteriorated and energy saving may be impaired.

  An object of the present invention is to improve the convergence of the operation capacity in a refrigeration apparatus including a variable capacity compressor.

  In order to achieve the above-described object, the present invention provides a refrigeration system in which a compression unit of a refrigeration cycle is provided with at least one variable capacity compressor whose operating capacity is variable. And a controller for determining a change characteristic of the operating capacity of the compression unit with respect to a pressure difference between a pressure value detected by the pressure sensor and a preset target low pressure, the controller comprising: It is characterized in that the fluctuation of the low-pressure pressure is monitored and the change characteristic of the operating capacity is adjusted based on the judgment on the fluctuation state of the low-pressure pressure.

  Alternatively, the present invention provides a refrigeration apparatus including at least one variable capacity compressor whose operating capacity is variable and at least one constant speed compressor whose operating capacity is constant, in which the compressor of the refrigeration cycle is variable. A pressure sensor for detecting a low pressure of the refrigeration cycle, and a controller for determining a change characteristic of an operating capacity of the compression unit with respect to a pressure difference between a pressure value detected by the pressure sensor and a preset target low pressure And the controller monitors a change in the low-pressure pressure and adjusts the change characteristic of the operating capacity based on the determination on the fluctuation state of the low-pressure pressure.

  According to the refrigeration apparatus of the present invention, even when the convergence rate is deteriorated at a preset change rate of the operating capacity, the change rate of the operating capacity is automatically adjusted to improve the convergence and improve the energy saving performance. it can.

It is a cycle block diagram which shows the whole structure of the freezing apparatus concerning Example 1 of this invention. It is a graph which shows the detected value of the low pressure sensor concerning Example 1 of the present invention. It is a flowchart figure which shows control operation of the freezing apparatus concerning Example 1 of this invention. It is a graph which shows the change of the low pressure pressure at the time of performing the convergence determination A concerning Example 1 of this invention. It is a graph which shows the change of the low pressure pressure at the time of performing the convergence determination B concerning Example 1 of this invention. It is a graph which shows the change rate of the operation capacity of the compression part concerning Example 1 of the present invention. It is a flowchart figure which shows control operation of the freezing apparatus concerning Example 2 of this invention.

  A refrigerating apparatus according to an embodiment of the present invention will be described.

  The refrigeration apparatus includes at least one variable capacity compressor in which a compression section of a refrigeration cycle has a variable operation capacity, and detects a low pressure of the refrigeration cycle and a pressure sensor A controller for determining a change characteristic of the operating capacity of the compression unit with respect to a pressure difference between the set pressure value and a preset target low pressure, and the controller monitors a change in the low pressure and changes the low pressure The change characteristic of the operating capacity is adjusted based on the judgment on the state.

  In addition, this refrigeration apparatus includes at least one variable capacity compressor whose operating capacity is variable and at least one constant speed compressor whose operating capacity is constant. It may be.

  Further, the controller determines whether or not the low pressure pressure hunting frequency is equal to or higher than a predetermined reference. If the low pressure pressure hunting frequency is equal to or higher than the predetermined reference, the change rate of the operating capacity of the compression unit is reduced. Adjust the change characteristics as follows.

  In addition, the controller determines whether or not the low pressure pressure hunting is equal to or greater than a predetermined reference. If the low pressure pressure hunting is smaller than the predetermined reference, whether or not the time change of the pressure difference is larger than the predetermined reference. If the pressure change over time is greater than a predetermined reference, the change characteristic is adjusted so that the rate of change in the operating capacity of the compression unit is increased.

  Further, when the pressure difference is smaller than a predetermined value, the operating capacity is not changed.

  Further, the controller changes the operating capacity without making a judgment on the fluctuation state of the low pressure when the difference between the pressure value detected by the pressure sensor and the target low pressure is larger than a predetermined value. .

  Next, the refrigeration apparatus according to Example 1 will be described with reference to FIGS.

  First, the entire refrigeration apparatus according to Embodiment 1 will be described with reference to FIG. FIG. 1 is a diagram showing the overall configuration of the refrigeration apparatus of this embodiment. The refrigeration apparatus of the present embodiment is an example of a multi-refrigerator for large stores such as a supermarket where the load greatly fluctuates.

  The refrigeration apparatus includes an apparatus main body unit 10 disposed outdoors and a plurality of low-pressure equipment units 12a and 12b disposed indoors. These units 10, 12a, 12b are connected via a refrigerant pipe 9 to constitute a refrigeration cycle. The plurality of low-voltage equipment units 12a and 12b are connected in parallel.

  The gas refrigerant discharged from the compressors 1a and 1b is cooled and condensed by the condenser 2 and the cooling fan 6 to become liquid refrigerant, but once condensed, the liquid refrigerant is temporarily stored in the receiver 5. Yes. Thereafter, the liquid refrigerant cooled again by the supercooler 3 integrated with the condenser 2 is evaporated by the decompression mechanisms 11a and 11b and the evaporators 4a and 4b via the refrigerant pipe 9. Then, after becoming the gas refrigerant again, it is sucked into the compressors 1a and 1b.

  At least one of the compressors 1a and 1b is constituted by a variable operating capacity scroll compressor or a rotary compressor that is controlled by an inverter. These variable operating capacity compressors have variable operating capacity by controlling the driving frequency. The compressor may be a single variable operating capacity compressor that is inverter-controlled. When a plurality of units are combined, all may be variable capacity compressors, or a variable capacity compressor and a constant speed compressor having a constant operating capacity may be combined. Specifically, a variable operating capacity compressor is used as the compressor 1a, and a constant speed compressor having a constant operating capacity is used as the compressor 1b.

  The decompression mechanisms 11a and 11b are constituted by expansion valves and are disposed in the low-pressure equipment units 12a and 12b, respectively. The evaporators 4a and 4b are disposed in the low-pressure equipment units 12a and 12b, respectively, and cool an object to be cooled such as food. The decompression mechanism 11a and the evaporator 4a are connected in series, the decompression mechanism 11b and the evaporator 4b are connected in series, and these series circuits are connected in parallel.

  The pressure sensor 7 is provided to detect the load of the refrigeration apparatus (load in the low-pressure equipment units 12a and 12b), and detects the low-pressure pressure of the refrigeration cycle (that is, the pressure on the suction side of the compressor 1). Then, it is configured to input to the controller 8. The controller 8 controls the compressors 1 a and 1 b based on the pressure detected by the pressure sensor 7. The low pressure of the refrigeration cycle may be the refrigerant evaporation pressure.

  Next, the detection value of the pressure sensor 7 and the control operation of the controller 8 based thereon will be described with reference to FIGS. FIG. 2 is a diagram for explaining an example of a detection value of the pressure sensor 7 provided for detecting the load of the refrigeration apparatus of FIG. 1, and FIG. FIG.

  When the load fluctuation of the refrigeration apparatus (that is, the load fluctuation of the low-pressure equipment units 12a and 12b) occurs, the low-pressure pressure detection value Ps (t) of the pressure sensor 7 is detected (step S1), and the past detection value is referred to Then, the estimated pressure value Ps (t2) after t2 seconds is calculated (step S2).

  Here, the past low-pressure pressure detection value may be simply calculated from the low-pressure pressure detection value Ps (−t1) t1 seconds ago and the current low-pressure pressure detection value Ps (0), or two or more past It may be estimated based on the detected low pressure value. The low pressure detection value Ps (t) is detected every predetermined sampling time t1.

  Further, the target low pressure value PsT corresponding to the low pressure side equipment cooling temperature set by the low pressure equipment units 12a and 12b is fetched (step S3). A pressure difference ΔPs = Ps (t2) −PsT between the target low pressure value PsT and the estimated pressure value Ps (t2) after t2 seconds is calculated (step S4).

  Next, after determining convergence (steps S7 to S10) based on the pressure difference ΔPs, the capacity change amount ΔV is calculated in step S11, and the operating capacity is changed in step S12.

  Note that the low-pressure detection value Ps (t) always varies. Accordingly, in order to improve the convergence of the low pressure to the target low pressure value PsT, a dead zone region (see FIG. 6) having a certain width with respect to the pressure difference ΔPs calculated in step S4 is set. That is, when the pressure difference is smaller than a predetermined value, the operating capacity is not changed. Specifically, for the pressure difference ΔPs calculated in step S4, a dead zone area where the operating capacity is not changed is set to “−0.02 <ΔPs <0.02”, for example, and the dead zone area is out of the dead zone area. The operating capacity is changed.

  FIG. 6 is a graph showing the change rate of the operating capacity of the compression unit. Based on this, control is performed to bring the low pressure detection value Ps (t) of the pressure sensor 7 close to the target low pressure value PsT by changing the current operating capacity of the compressors 1a and 1b by the capacity change amount ΔV. .

  Hereinafter, the determination of convergence (steps S7 to S10), the calculation of the capacity change amount ΔV (step S11), and the change of the operating capacity (step S12) will be described in detail.

  The operating capacity change rate characteristic in the capacity change amount ΔV calculation (step S11) is adjusted by determining convergence (steps S7 and S9). First, in the convergence determination A (step S7), it is determined whether or not hunting is large. For example, when the pressure difference is ΔPs1, the capacity change amount is ΔV1 in the initial setting, but the hunting is large in the convergence determination A (step S7) (Yes in step S7), and the capacity change rate is small in step S8. When the change is made (DOWN) in this way, the capacity change amount is set to ΔV1 ′ in step S11, thereby reducing the hunting and improving the convergence.

  FIG. 4 is a graph showing a change in low-pressure pressure when the convergence determination A (step S7) of the control operation of the refrigeration apparatus is performed.

  Determination method A1 shows an example of a hunting determination method in determination A of convergence of the control operation of the refrigeration apparatus. In the determination method A1, the number of passes of the target low pressure value PsT in a preset hunting sampling time Th is counted, and if it passes a certain number of times, it is determined that hunting is large (Yes in step S7), and the capacity is determined in step S8. Change (DOWN) is performed so that the rate of change is small, and the capacitance change amount ΔV is reduced in step S11.

  Here, when counting the number of times the target low-pressure pressure value PsT passes, the convergence of the low-pressure pressure to the target low-pressure value PsT can be improved by giving a certain width to the target low-pressure pressure value PsT. it can. Specifically, a certain width with respect to the target low pressure value PsT when counting the number of times of passage is a dead zone region where the operating capacity is not changed as shown in FIG.

  For example, if the lower limit value PsD = PsT−0.02 MPa, the upper limit value PsU = PsT + 0.02 MPa for the target low pressure value PsT and the dead zone region is passed 10 times or more in a hunting sampling time of 10 minutes, the operating capacity The rate of change characteristic is reduced to 50%. Once the operating capacity change rate characteristic is changed, the dead zone area passing frequency count is reset to zero and counting is started again. Similarly, if the dead zone area is passed 10 times or more again during the hunting sampling time of 10 minutes, the operating capacity changes. The rate characteristic is further reduced by 50%.

  The determination method A2 is an example different from the determination method A1 of the hunting determination method in the determination A of the convergence of the control operation of the refrigeration apparatus. When the current low pressure detection value Ps (0) passes the target low pressure PsT with respect to the low pressure detection value Ps (−t3) before the convergence determination time t3 seconds, the pressure difference ΔPs with the target low pressure PsT. When the absolute value ratio is larger than the preset determination value ΔPs1, it is determined that hunting is large (Yes in step S7), and the capacity change rate is changed (DOWN) in step S8 so that the capacity change rate becomes small. The change amount ΔV is reduced.

  For example, when the convergence determination time t3 = 30 seconds and the absolute value ratio determination value ΔPs1 = 1.0 of the pressure difference ΔPs, the pressure difference ΔPs (−30) = 0.05 from the target low pressure PsT 30 seconds before. A specific calculation method for the case where the pressure difference ΔPs (0) = − 0.06 from the current target low pressure PsT will be described below.

  Since the pressure difference product ΔPs (−t3) × ΔPs (0) = 0.05 × (−0.06) <0, minus pressure detection value Ps (−t3) before convergence determination time t3 seconds On the other hand, it can be determined that the current low pressure detection value Ps (0) passes the target low pressure PsT. Furthermore, the absolute value ratio of the pressure difference ΔPs | ΔPs (0) | / | ΔPs (−t3) | = 0.06 / 0.05 = 1.2> 1.0, which is compared with the convergence determination time t3 seconds before. It is far from the target low pressure PsT, and it can be determined that hunting is large.

  Here, when the capacity change rate is changed (DOWN) so as to decrease in step S8 and the capacity change amount ΔV is reduced in step S11, the reciprocal of the absolute value ratio of the pressure difference ΔPs is 1 / 1.2 = 0.83. Is used to set the capacity change amount after adjustment ΔV ′ = ΔV (capacity change amount before adjustment) × 0.83 (reciprocal of the absolute value ratio of the pressure difference ΔPs) × 0.8 (adjustment coefficient). Hunting can be reduced and convergence can be improved.

  The capacity change amount ΔV in step S11 may be adjusted stepwise by the absolute value ratio of the pressure difference ΔPs or may be adjusted by a preset constant change amount.

  On the other hand, if the hunting is small in the convergence determination A (step S7) (No in step S7), it is determined in the convergence determination B (step S9) whether the accessibility is poor.

  FIG. 5 is a graph showing a change in the low-pressure pressure when the convergence determination B (step S9) of the control operation of the refrigeration apparatus is performed.

  For example, in the determination method A2 of the convergence determination A (step S7), the current low pressure detection value Ps (0) is the target low pressure relative to the low pressure detection value Ps (−t3) before the convergence determination time t3 seconds. When the pressure PsT is not passed (No in step S7), if the absolute value ratio of the pressure difference ΔPs with respect to the target low pressure PsT is larger than a preset determination value ΔPs2, it is determined that the accessibility is poor (in step S9). Yes), the capacity change rate is changed (UP) so as to increase in step S10, and the capacity change amount ΔV is increased in step S12.

  For example, when the convergence determination time t3 = 30 seconds and the absolute value ratio determination value ΔPs2 = 0.7 of the pressure difference ΔPs, the pressure difference ΔPs (−30) = − 0.0 from the target low pressure PsT 30 seconds before. A specific calculation method for the case where the pressure difference ΔPs (0) = − 0.05 from the current target low pressure PsT is shown below.

  Since the product of pressure difference ΔPs (−t3) × ΔPs (0) = (− 0.06) × (−0.05)> 0 is positive, the low pressure detection value Ps (3) before the convergence determination time t3 seconds With respect to -t3), it can be determined that the current low pressure detection value Ps (0) does not pass the target low pressure PsT. Further, the absolute value ratio of the pressure difference ΔPs | ΔPs (0) | / | ΔPs (−t3) | = 0.05 / 0.06 = 0.83> 0.7, and the convergence determination time t3 is 1 or less. Although it is closer to the target low pressure PsT than before 2 seconds, it can be determined that the accessibility is poor because it is larger than the determination value ΔPs2.

  Here, when the capacity change rate is increased (UP) to increase the capacity change amount ΔV, the capacity change amount after adjustment ΔV ′ = ΔV (capacity change amount before adjustment) × 0.83 (pressure difference) By setting (absolute value ratio of ΔPs) × 1.5 (adjustment coefficient), the accessibility can be improved and the convergence can be enhanced. The capacity change amount ΔV may be adjusted stepwise by the absolute value ratio of the pressure difference ΔPs, or may be adjusted by a preset constant change amount.

  On the other hand, in the case of No in step S9, the capacity change rate is not adjusted, and the current capacity change rate is maintained, and the process proceeds to calculation of the capacity change amount ΔV (step S11).

  As described above, according to the present embodiment, the operating capacity of the operating capacity is automatically adjusted even when the convergence is deteriorated with the preset operating capacity due to the characteristics of the low-pressure equipment units 12a and 12b and the installation environment of the refrigeration apparatus. The rate of change can be adjusted to improve convergence and improve energy savings.

  Next, a refrigeration apparatus according to Embodiment 2 will be described with reference to FIG.

  In the second embodiment, when the difference between the pressure value detected by the pressure sensor and the target low-pressure pressure is larger than a predetermined value, the operating capacity is changed without making a determination on the fluctuation state of the low-pressure pressure. .

  In the flowchart showing the control operation of the refrigeration apparatus of FIG. 7, when the target low pressure value PsT corresponding to the low pressure side equipment cooling temperature set by the low pressure equipment units 12a and 12b is taken in, the low pressure upper limit Lu and the low pressure The lower limit Ld is also taken in (step S3).

  The low pressure upper limit Lu and the low pressure lower limit Ld are values set in advance. For example, when the target low pressure PsT = 0.33 MPa, the low pressure upper limit Lu is 0.46 MPa, and the low pressure lower limit Ld is 0.26 MPa. Further, energy saving can be improved by setting the difference between the target low pressure PsT and the low pressure upper limit Lu to be larger than the difference between the target low pressure PsT and the low pressure lower limit Ld.

  Next, as a second pressure determination, it is determined whether or not the detected value of the pressure sensor 7 is between the low pressure upper limit value Lu and the low pressure lower limit Ld (step S5). Here, the detected value of the pressure sensor 7 may use not only the current low-pressure pressure detection value Ps (0) but also the estimated pressure value Ps (t2) after t2 seconds and the past low-pressure pressure detection value. . For example, an average value of a plurality of past low-pressure pressure detection values may be used. Further, the determination is made based on whether or not a predetermined number or more (for example, half or more) of low pressure detection values among a plurality of past low pressure detection values are between the low pressure upper limit Lu and the low pressure lower limit Ld. May be.

  In the second pressure determination (step S5), if the detected value of the pressure sensor 7 is not within the determination range, a second operating capacity change is performed (step S6).

  The second operating capacity change (step S6) is set so that, for example, when three compressors 1 are installed, a large operating capacity change of about “33%” corresponding to one compressor is performed. It is desirable that Alternatively, the number of operating compressors may be increased or decreased by one.

  According to the present embodiment, even if the convergence of the preset operating capacity deteriorates due to the characteristics of the low-pressure equipment unit and the installation environment of the refrigeration apparatus, the convergence rate is automatically adjusted by adjusting the change rate of the operating capacity. The energy saving can be improved. That is, it is possible to improve energy saving while ensuring followability when the cooling load of the low-pressure equipment units 12a and 52b varies greatly.

DESCRIPTION OF SYMBOLS 1a, 1b Compressor 2 Condenser 3 Supercooler 4a, 4b Evaporator 5 Receiving device 6 Cooling fan 7 Pressure sensor 8 Controller 9 Refrigerant piping 10 Apparatus main body unit 11a, 11b Decompression mechanism 12a, 12b Low-pressure apparatus unit

Claims (6)

In the refrigeration apparatus configured by including at least one variable capacity compressor in which the compression unit of the refrigeration cycle makes the operation capacity variable,
A pressure sensor for detecting a low pressure of the refrigeration cycle;
A controller for determining a change characteristic of an operating capacity of the compression unit with respect to a pressure difference between a pressure value detected by the pressure sensor and a preset target low pressure,
The said controller monitors the fluctuation | variation of a low pressure, and adjusts the change characteristic of the said operating capacity based on the judgment with respect to the fluctuation state of a low pressure. In the refrigeration apparatus configured by including at least one variable capacity compressor in which the compression section of the refrigeration cycle has variable operating capacity and at least one constant speed compressor having a constant operating capacity,
A pressure sensor for detecting a low pressure of the refrigeration cycle;
A controller for determining a change characteristic of an operating capacity of the compression unit with respect to a pressure difference between a pressure value detected by the pressure sensor and a preset target low pressure,
The said controller monitors the fluctuation | variation of a low pressure, and adjusts the change characteristic of the said operating capacity based on the judgment with respect to the fluctuation state of a low pressure. The refrigeration apparatus according to claim 1 or 2,
The controller determines whether the low pressure pressure hunting frequency is equal to or higher than a predetermined reference,
When the hunting frequency of the low-pressure pressure is equal to or higher than a predetermined reference, the change characteristic is adjusted so that the change rate of the operation capacity of the compression unit is reduced. The refrigeration apparatus according to claim 1 or 2,
The controller determines whether the low pressure pressure hunting is equal to or higher than a predetermined reference,
When the low pressure pressure hunting is smaller than the predetermined reference, it is determined whether or not the time change of the pressure difference is larger than the predetermined reference.
A refrigeration apparatus characterized by adjusting a change characteristic so that a change rate of an operating capacity of the compression unit is increased when a time change of the pressure difference is larger than a predetermined reference. The refrigeration apparatus according to claim 1 or 2,
When the pressure difference is smaller than a predetermined value, the operating capacity is not changed. The refrigeration apparatus according to claim 1 or 2,
The controller, when the difference between the pressure value detected by the pressure sensor and the target low pressure is larger than a predetermined value,
A refrigerating apparatus characterized in that the operating capacity is changed without making a judgment on the fluctuation state of the low pressure.

Images