JP4720923B2 - Refrigeration equipment - Google Patents

Description

  The present invention relates to a refrigeration apparatus including a refrigerant circuit provided with an expansion valve having a variable opening.

  Conventionally, a refrigeration apparatus including a refrigerant circuit provided with an expansion valve having a variable opening is known. Patent Document 1 discloses an air conditioner as this type of refrigeration apparatus. This air conditioner includes a superheat degree control device. The control unit of the superheat degree control device calculates the difference between the inlet temperature of the outdoor heat exchanger and the outlet temperature of the outdoor heat exchanger during heating as the superheat degree of the outlet of the outdoor heat exchanger, and calculates the calculated superheat degree and the target superheat. The difference from the degree is calculated as a deviation E. And the valve control part of a superheat degree control apparatus controls the opening degree of an electric expansion valve so that the deviation E may be set to zero.

Japanese Patent Laid-Open No. 7-225058

  By the way, the variable opening degree expansion valve used in this type of refrigeration apparatus has individual differences in opening degree, and even when the input opening degree command value is the same, the actual opening degree varies. For this reason, in a conventional refrigeration apparatus using an expansion valve having a variable opening, the actual valve of the expansion valve is controlled with respect to the control opening that the valve control means that outputs the command value of the opening to the expansion valve attempts to set. There is a case where the opening degree is deviated, and there is a problem that appropriate flow rate control cannot be performed in such a case.

  This invention is made | formed in view of this point, The objective is to optimize the flow control by an expansion valve in a refrigeration apparatus provided with the refrigerant circuit provided with the expansion valve of variable opening degree.

A first aspect of the present invention is a refrigerant circuit (20) that is provided with a compressor (11) and an expansion valve (13) having a variable opening, and that performs a refrigeration cycle, and a valve that controls the opening of the expansion valve (13). The refrigeration apparatus (10) provided with the control means (33) is an object. The refrigeration apparatus (10) includes the expansion valve (10) in a state in which the compressor (11) is stopped after the pump down operation in which the compressor (11) is operated with the expansion valve (13) closed. 13) while gradually increasing the command value of the opening degree output to the expansion valve (13) based on the change in the state of the low-pressure side refrigerant between the expansion valve (13) and the suction side of the compressor (11) By determining whether or not 13) is in an open state, an opening degree that detects a valve opening degree that is an opening degree command value when the expansion valve (13) changes from a closed state to an open state is detected. Valve opening degree detecting means (32, 34) for performing the valve opening degree detecting operation is provided, and the valve control means (33) uses the valve opening degree detected by the valve opening degree detecting operation to expand the expansion valve ( while controlling the 13), the valve opening degree detection means (32, 34) is first pressure reference value from the first pressure reference value during the pump down operation Remote to adjust the high pressure of the refrigeration cycle within a certain range of small to the second pressure reference value, the pressure of the low-pressure refrigerant to terminate the pump-down operation becomes below a predetermined low pressure reference value.

  In the first invention, the opening degree detecting means (32, 34) detects the opening degree that is the opening degree command value when the expansion valve (13) changes from the closed state to the open state. The valve opening detection operation is performed. The opening degree detection operation is performed after the pump-down operation in which the compressor (11) is operated with the expansion valve (13) closed. The opening degree detection means (32, 34) expands when the compressor (11) is stopped from a state where almost no refrigerant exists between the expansion valve (13) and the suction side of the compressor (11). While gradually increasing the command value of the opening to be output to the valve (13), the expansion valve (13) is expanded based on the change in the state of the low-pressure side refrigerant between the expansion valve (13) and the suction side of the compressor (11). It is determined whether or not 13) is open. When the expansion valve (13) changes from the closed state to the open state, the state of the low-pressure side refrigerant (for example, pressure or temperature) changes, so that the valve opening degree detection means (32, 34) A valve opening degree is detected based on a change in the state. In the first aspect of the invention, the opening degree of opening that varies depending on the expansion valve (13) is detected. According to this opening degree, the opening degree characteristic of the expansion valve (13) such as a difference between the actual opening degree and the control opening degree is grasped. For this reason, when the expansion valve (13) is controlled using the valve opening degree, the opening characteristic of the expansion valve (13) is reflected in the control of the expansion valve (13).

In the first invention, during the pump-down operation, the high pressure of the refrigeration cycle is adjusted within a certain range. For this reason, the high pressure of the refrigeration cycle when performing the opening degree detection operation is made constant.

In a second aspect of the invention, an external heat exchanger (12) for exchanging heat between the high-pressure refrigerant discharged from the compressor (11) and external air during the pump-down operation, and the external heat exchange An outside fan (21) for sending outside air to the chamber (12), while the valve opening degree detecting means (32, 34) is configured so that the high pressure of the refrigeration cycle is the above during the pump down operation. By starting the external fan (21) when the first high pressure reference value is exceeded, and stopping the external fan (21) when the high pressure of the refrigeration cycle is below the second high pressure reference value, The high pressure of the refrigeration cycle is adjusted within a certain range from the first high pressure reference value to the second high pressure reference value.

According to a third aspect of the present invention, in the first or second aspect of the invention, the valve opening degree is adjusted while the compressor (11) is operated with the expansion valve (13) opened before the pump-down operation. A preparatory operation is performed in which the detection means (32, 34) adjusts the high pressure of the refrigeration cycle within a certain range from the first high pressure reference value to the second high pressure reference value .

  In the third invention, the preparatory operation is performed before the pump-down operation. In the preparatory operation, the valve opening degree detection means (32, 34) adjusts the high pressure of the refrigeration cycle within a certain range. Therefore, the high pressure of the refrigeration cycle when performing the opening degree detection operation is made constant.

  According to a fourth invention, in any one of the first to third inventions, the valve opening degree detecting means (32, 34) opens when the pressure of the low-pressure side refrigerant exceeds a predetermined low-pressure threshold. The command value of the degree is detected as the valve opening degree.

  In the fourth invention, the command value of the opening when the pressure of the low-pressure side refrigerant exceeds a predetermined low-pressure threshold is detected as the valve opening degree. When the expansion valve (13) changes from the closed state to the open state, the pressure of the low-pressure side refrigerant increases and the temperature of the low-pressure side refrigerant decreases. The pressure of the low-pressure side refrigerant changes faster than the temperature. In the fourth aspect of the invention, the pressure value that changes more rapidly than the temperature is used to detect the valve opening degree.

  In the present invention, the valve opening degree that is the command value of the opening when the expansion valve (13) changes from the open state to the closed state is detected, and the detected opening degree of the expansion valve (13) is detected. Since the control is performed, the opening characteristic of the expansion valve (13) is reflected in the control of the expansion valve (13). That is, the control of the expansion valve (13) is performed in consideration of individual differences of the expansion valve (13). Therefore, individual differences of the expansion valve (13) are reflected in the flow rate of the refrigerant passing through the expansion valve (13), so that the flow control by the expansion valve (13) can be optimized.

Moreover, in this invention , the high pressure of the refrigerating cycle at the time of performing valve opening degree detection operation is made constant. Here, in the case where the high pressure of the refrigeration cycle is not adjusted before the valve opening degree detection operation, the refrigeration cycle when the valve opening degree detection operation is performed depending on operating conditions such as the temperature of the air sent to the condenser, for example. Therefore, the pressure of the refrigerant acting on the expansion valve (13) varies depending on the operating conditions. For this reason, the degree of change in the state of the low-pressure refrigerant when the expansion valve (13) changes to the open state is not constant depending on the operating conditions, making it difficult to accurately detect the valve opening. On the other hand, in the present invention , since the high pressure of the refrigeration cycle when performing the opening degree detection operation is made constant, the pressure of the refrigerant acting on the expansion valve (13) is constant regardless of the operating conditions. become. Therefore, since the degree of change in the state of the low-pressure refrigerant when the expansion valve (13) changes to the open state is constant regardless of the operating conditions, the valve opening degree can be accurately detected.

  In the fourth aspect of the invention, the pressure value that changes more rapidly than the temperature is used to detect the valve opening degree. For this reason, it is possible to perform the valve opening degree detection operation in a relatively short time.

1 is a schematic configuration diagram of a refrigeration apparatus according to an embodiment of the present invention. It is a longitudinal cross-sectional view of the expansion valve which concerns on embodiment of this invention. It is a chart showing the flow characteristic of the expansion valve concerning the embodiment of the present invention. It is a chart showing the setting situation of the lower limit command value set to the valve control part concerning the embodiment of the present invention. It is a flowchart showing the flow of the valve opening degree detection operation | movement and 1st correction | amendment operation | movement in the freezing apparatus which concerns on embodiment of this invention. It is a flowchart showing the flow of the 2nd correction | amendment operation | movement in the freezing apparatus which concerns on embodiment of this invention. It is a schematic block diagram of the freezing apparatus which concerns on the modification of embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  This embodiment is a refrigeration apparatus (10) according to the present invention. The refrigeration apparatus (10) of the present embodiment is configured as a container refrigeration apparatus (10) that cools the inside of a container. The refrigeration apparatus (10) is configured such that the set temperature in the refrigerator can be selected from a relatively wide temperature range (for example, -30 ° C to 46 ° C).

  As shown in FIG. 1, the refrigeration apparatus (10) includes a refrigerant circuit (20) filled with a refrigerant. The refrigerant circuit (20) is connected to the compressor (11), the external heat exchanger (12), the expansion valve (13), and the internal heat exchanger (14). In the refrigerant circuit (20), the vapor compression refrigeration cycle is performed by circulating the refrigerant.

  The compressor (11) is configured as a high-pressure dome type compressor, for example. The discharge side of the compressor (11) is connected to the gas side of the external heat exchanger (12). The suction side of the compressor (11) is connected to the gas side of the internal heat exchanger (14).

  The external heat exchanger (12) is configured by a cross fin type fin-and-tube heat exchanger. In the vicinity of the external heat exchanger (12), an external fan (21) for sending external air to the external heat exchanger (12) is installed. In the external heat exchanger (12), heat is exchanged between the external air and the refrigerant. The liquid side of the external heat exchanger (12) is connected to the expansion valve (13). A receiver (15) for temporarily storing the refrigerant is provided between the external heat exchanger (12) and the expansion valve (13).

  The internal heat exchanger (14) is configured by a cross fin type fin-and-tube heat exchanger. In the vicinity of the internal heat exchanger (14), an internal fan (22) for sending internal air to the internal heat exchanger (14) is installed. In the internal heat exchanger (14), heat is exchanged between the internal air and the refrigerant. The liquid side of the internal heat exchanger (14) is connected to the expansion valve (13).

  The expansion valve (13) is an electric expansion valve with a variable opening. The opening degree of the expansion valve (13) is adjusted according to a control pulse (opening command value) of a pulse signal output by a valve control unit (33) described later. Details of the expansion valve (13) will be described later.

  The refrigeration apparatus (10) is provided with a controller (30). The controller (30) includes a compressor control unit (31), a fan control unit (32), a valve control unit (33), and a control opening correction unit (34). Details of the controller (30) will be described later.

  The refrigeration apparatus (10) of the present embodiment is provided with a plurality of sensors. Specifically, a high pressure sensor (23) for detecting the pressure of the high pressure refrigerant discharged from the compressor (11) is provided on the discharge side of the compressor (11) of the refrigerant circuit (20). On the suction side of the compressor (11), a low-pressure sensor (24) that detects the pressure of the low-pressure refrigerant sucked into the compressor (11) is provided. The measured values of the high pressure sensor (23) and the low pressure sensor (24) are detected by gauge pressure.

  An inlet temperature sensor (25) for detecting the temperature of the refrigerant flowing into the internal heat exchanger (14) is provided on the inlet side of the internal heat exchanger (14) serving as an evaporator. An outlet temperature sensor (26) for detecting the temperature of the refrigerant flowing out of the internal heat exchanger (14) is provided on the outlet side of the internal heat exchanger (14). A suction temperature sensor (27) for measuring the temperature of the air flowing into the internal heat exchanger (14) is provided in the vicinity of the internal heat exchanger (14). The measurement values of these sensors (23 to 27) are input to the controller (30).

-Expansion valve structure-
The expansion valve (13) of the refrigerant circuit (20) is a direct acting electric expansion valve. Here, the expansion valve (13) will be described with reference to FIG.

  In the expansion valve (13), a solenoid (72) as a stator disposed on the outer peripheral side of a cylindrical motor casing (71), and a rotor (73) as a rotor located in the casing (71) ) Constitutes a pulse motor (75). The expansion valve (13) is configured to move up and down a needle (76) provided with a valve portion (76a) at the tip according to the rotation of the rotor (73).

  The rotor (73) includes a cylindrical bush (77) and a magnet (74) disposed on the outer peripheral side thereof. The bush (77) has a hole (77a) that opens downward near the center of rotation. The hole (77a) is a female screw having a thread formed on its inner peripheral surface. In the hole (77a), a needle (76) whose upper end is fixed to the rotor (73) is disposed so as to extend downward.

  A columnar main body (78) is integrally provided below the motor casing (71). Inside the main body (78), holes (78a, 78b) as flow passages that open to the side and downward are formed so as to be orthogonal to each other. The main body portion (78) is connected to the hole portions (78a, 78b), respectively, so as to form first and second pipes (85, 86). ) Is connected. A valve seat (81) for receiving the valve portion (76a) is provided in the hole portion (78b) to which the second joint (80) is connected.

  Further, a hole (78c) extending upward from the hole (78b) provided with the valve seat (81) is also formed in the main body (78). A cylindrical member (82) extending upward is disposed above the main body (78) so as to communicate with the internal space of the hole (78c). A threaded portion is formed on the outer peripheral surface of the cylindrical member (82) and is screwed into the hole (77a) of the rotor (73). Thus, when the rotor (73) rotates, the rotor (73) moves up and down with respect to the main body (78) fixed to the motor casing (71).

  Inside the cylindrical member (82), the needle (76) is arranged in such a posture that the upper end side is fixed to the rotor (73) and extends downward in the hole (77a). The needle (76) is also inserted into the hole (78c) of the main body (78) communicating with the internal space of the cylindrical member (82). The valve portion (76a) at the lower end of the needle (76) is a portion where the hole portions (78a, 78b) of the main body portion (78) are orthogonal to each other (that is, the communication portion (87)). Opposite the provided valve seat (81). Thus, as described above, when the rotor (73) moves up and down, the needle (76) moves up and down in the cylindrical member (82) and the hole (78c) of the main body (78) accordingly. The valve portion (76a) at the lower end of the needle (76) moves up and down with respect to the valve seat (81) (moves in the longitudinal direction of the second conduit), thereby opening and closing the expansion valve (13). Will be done.

  The expansion valve (13) used in the refrigeration apparatus (10) is a product in which the maximum value of the control pulse (EV) is EV_max pulse (for example, EV_max = 2000). In this product, as shown in FIG. 3, the flow characteristic representing the relationship between the control pulse (EV) and the passage flow rate of the expansion valve (13) has a variation in the range from the characteristic line A to the characteristic line C. The characteristic line A represents the flow rate characteristic of the expansion valve (13) that maximizes the flow rate of the expansion valve (13) in this product. A characteristic line B represents a flow rate characteristic of the expansion valve (13) in which the passage flow rate of the expansion valve (13) is an average value in this product. A characteristic line C represents a flow rate characteristic of the expansion valve (13) in which the passage flow rate of the expansion valve (13) is minimized in this product. In this product, EV_Llim (A) pulse (for example, the range of variation due to individual differences in valve opening (EV_Llim), which is the control pulse (EV) when the expansion valve (13) changes from the open state to the closed state, is used. A range of EV_Llim (A) = 50) to EV_Llim (C) pulses (for example, EV_Llim (C) = 150) is assumed. In addition, in the standard of the expansion valve (13), the flow rate when fully opened is determined in accordance with conditions (for example, 30 ° C.) in which the set temperature in the refrigerator is relatively high.

-Driving action-
As the operation of the refrigeration apparatus (10) of the present embodiment, a cooling operation for cooling the interior of the container will be described. The cooling operation is a normal operation that adjusts the temperature of the interior of the storage space. The cooling operation is started when the compressor (11) is started. At that time, in the refrigerant circuit (20), a refrigeration cycle is performed in which the external heat exchanger (12) operates as a condenser and the internal heat exchanger (14) operates as an evaporator.

  Specifically, the refrigerant discharged from the compressor (11) dissipates heat to the outside air and condenses in the outside heat exchanger (12). The refrigerant condensed in the external heat exchanger (12) is decompressed by the expansion valve (13) and then flows into the internal heat exchanger (14). In the internal heat exchanger (14), the refrigerant absorbs heat from the internal air and evaporates. On the other hand, the in-compartment air cooled by the in-compartment heat exchanger (14) is supplied into the interior. The refrigerant evaporated in the internal heat exchanger (14) is sucked into the compressor (11) and compressed.

-Controller configuration-
As described above, the controller (30) includes the compressor control unit (31), the fan control unit (32), the valve control unit (33), and the control opening correction unit (34). The valve control unit (33) constitutes a valve control means. The control opening degree correction unit (34) constitutes a valve opening degree detecting means.

  Specifically, the compressor control unit (31) is configured to control the operating state of the compressor (11). The compressor control unit (31) controls the operating capacity of the compressor (11) so that the measured value (LPT) of the low pressure sensor (24) becomes a predetermined target value, for example.

  The fan control unit (32) is configured to control the operation state of the external fan (21) and the internal fan (22). The fan control unit (32) controls the high pressure of the refrigeration cycle by controlling the operating state of the external fan (21). Specifically, the fan control unit (32) determines that the external fan (21) when the measured value (HPT) of the high pressure sensor (23) exceeds the first high pressure reference value during operation of the compressor (11). Start up. On the other hand, the fan control unit (32) stops the outside fan (21) when the measured value (HPT) of the high pressure sensor (23) is lower than the second high pressure reference value. The fan control unit (32) stops the external fan (21) even when the compressor (11) stops. Note that these high-pressure reference values are set higher in the preparatory operation and the pump-down operation described later than in the normal operation.

  The valve control unit (33) is configured to control the opening degree of the expansion valve (13) during the cooling operation. The valve control unit (33) adjusts the opening of the expansion valve (13) so that the superheat degree (SH) of the refrigerant at the outlet of the internal heat exchanger (14) becomes a predetermined target superheat degree (for example, 5 ° C.). Perform superheat control. However, when the detected value (HPT) of the high pressure sensor (23) is equal to or higher than a predetermined third high pressure reference value (for example, 2100 kPa), the valve control unit (33) prioritizes superheat control and expands. The opening degree of the valve (13) is reduced by a predetermined opening degree to reduce the high pressure of the refrigeration cycle.

  Specifically, in the superheat control, the valve controller (33) determines the control pulse (EV) so that the superheat (SH) of the refrigerant at the outlet of the internal heat exchanger (14) approaches the target superheat. Then, the determined pulse signal of the control pulse (EV) is output to the pulse motor (75) of the expansion valve (13). The valve control unit (33) increases the control pulse (EV) when the superheat degree (SH) of the refrigerant at the outlet of the internal heat exchanger (14) is larger than the target superheat degree. On the other hand, the valve control unit (33) decreases the control pulse (EV) when the superheat degree (SH) of the refrigerant at the outlet of the internal heat exchanger (14) is smaller than the target superheat degree.

  As shown in FIG. 4, the valve control unit (33) has a lower limit command value (EVL) that is a lower limit value of the control pulse according to the measured value (RS) of the suction temperature sensor (27) among the operating conditions. ) Is preset. The lower limit command value (EVL) is set for each temperature range of the measured value (RS) of the suction temperature sensor (27). The lower limit command value (EVL) is set to be larger as the measured value (RS) of the suction temperature sensor (27) is larger. In the valve control unit (33), the control pulse (EV) is determined in a range not less than the lower limit command value (EVL) and not more than the maximum value (EV_max).

  The control opening correction unit (34) uses the valve opening detection operation for detecting the valve opening (EV_Llim) and the lower limit command value (EVL) using the detected valve opening (EV_Llim). The first correction operation to be corrected and the second correction operation to recorrect the lower limit command value (EVL) corrected by the first correction operation are performed. The control opening correction unit (34) performs a valve opening degree detection operation when the refrigeration apparatus (10) is started, and performs a first correction operation immediately after the valve opening degree detection operation. The control opening correction unit (34) performs the second correction operation during the cooling operation. In the first correction operation, a correction value (EV_adj) for correcting the lower limit command value (EVL) is calculated. In the second correction operation, the correction value (EV_adj) is corrected together with the lower limit command value (EVL).

  The control opening correction unit (34) includes a storage unit (35) for storing a correction value (EV_adj). The storage unit (35) is configured as a memory that can store the correction value (EV_adj). The storage unit (35) is configured by an SRAM (Static Random Access Memory) that does not erase the stored contents even when the refrigeration apparatus (10) is powered off.

-Controller operation-
Of the operations of the controller (30), the valve opening degree detection operation, the first correction operation, and the second correction operation will be described. Since the opening degree detection operation and the first correction operation are performed as a series of operations, the opening degree detection operation and the first correction operation will be described below with reference to FIG. . In this refrigeration apparatus (10), when the refrigeration apparatus (10) is started, the preparatory operation and the pump-down operation are performed before the valve opening degree detection operation. Next, the preparation operation and the pump down operation will be described.

  First, when the refrigeration apparatus (10) is activated, in step 1 (ST1), the controller (30) causes the refrigeration apparatus (10) to perform a preparatory operation. In step 1 (ST1), the compressor control unit (31) activates the compressor (11), and the fan control unit (32) activates the internal fan (22). Further, the valve control unit (33) outputs a pulse signal having a predetermined set value (for example, 800 pulses) as a control pulse (EV) to the expansion valve (13) to adjust the opening degree of the expansion valve (13). To do. Moreover, in the controller (30), simultaneously with the start of the start of the compressor (11), a first timer, for example, a 90 second timer is started.

  Further, the fan control unit (32) during the preparatory operation controls the operation and stop of the external fan (21) based on the detection value (HPT) of the high pressure sensor (23). Specifically, the fan control unit (32) activates the external fan (21) when the detection value (HPT) of the high pressure sensor (23) exceeds a predetermined first high pressure reference value (for example, 1800 kPa), When the detected value (HPT) of the high pressure sensor (23) is below a predetermined second high pressure reference value (for example, 1600 kPa), the outside fan (21) is stopped. In the preparatory operation, the high pressure of the refrigeration cycle is adjusted within a certain range from the first high pressure reference value to the second high pressure reference value. In this embodiment, the fan control unit (32) that performs such high pressure control before the valve opening degree detection operation constitutes the valve opening degree detection means together with the control opening degree correction unit (34).

  In Step 2 (ST2), the controller (30) performs a first timer determination for determining whether or not there is a remaining time of the first timer. When there is no remaining time of the first timer, the controller (30) determines the end of the preparatory operation, resets the first timer, and then performs step 3 (ST3). When there is remaining time of the first timer, the controller (30) repeats Step 2 (ST2) until the remaining time of the first timer runs out.

  In step 3 (ST3), the controller (30) causes the refrigeration apparatus (10) to perform a pump-down operation. In step 3 (ST3), the valve control unit (33) sets the expansion valve (13) to be fully closed, and a second timer that is a 120-second timer, for example, is started. The pump-down operation is started when the expansion valve (13) is closed. The operation of the compressor (11) is continued from the preparation operation. In the pump down operation, the compressor (11) is operated with the expansion valve (13) closed, and the refrigerant does not flow into the internal heat exchanger (14), and the internal heat exchanger (14) The refrigerant is sucked into the compressor (11). In the pump down operation, as in the preparation operation, the high pressure of the refrigeration cycle is adjusted by the fan control unit (32) within a certain range from the first high pressure reference value to the second high pressure reference value. When step 3 (ST3) is completed, step 4 (ST4) is performed.

  In step 4 (ST4), the controller (30) performs second timer determination for determining whether there is a remaining time of the second timer. When there is no remaining time of the second timer, the controller (30) determines that it is necessary to abnormally stop the refrigeration apparatus (10), and proceeds to step 6 (ST6), where the refrigeration apparatus (10) Is stopped abnormally. On the other hand, when there is a remaining time of the second timer, the controller (30) performs Step 5 (ST5).

  In step 5 (ST5), it is determined whether or not the pump-down operation is to be terminated. When the measured value (LPT) of the low pressure sensor (24) is equal to or lower than a predetermined first low pressure reference value (for example, −55 kPa), the controller (30) determines the end of the pump down operation, and 2 Step 7 (ST7) is performed after the timer is reset. On the other hand, if the measured value (LPT) of the low pressure sensor (24) is not less than or equal to the predetermined first low pressure reference value, the controller (30) returns to step 4 (ST4) and returns to the second timer. Make a decision. The refrigeration apparatus (10) of the present embodiment is abnormally stopped when the measured value (LPT) of the low pressure sensor (24) does not fall below the first low pressure reference value before the remaining time of the second timer runs out.

  From step 7 (ST7), the controller (30) starts the valve opening degree detection operation by the control opening degree correction unit (34). In step 7 (ST7), the control opening correction unit (34) stops the compressor (11) and stops the outside fan (21) if the outside fan (21) is in an operating state. The operation of the internal fan (22) is continued. In step 7 (ST7), the control opening correction unit (34) outputs a pulse signal having a predetermined initial value (for example, 50 pulses) as a control pulse (EV) to the expansion valve (13), thereby expanding the expansion valve (13). Adjust the opening of the valve (13). This slightly raises the needle (76) of the expansion valve (13). The initial value is set to the lower limit value (EV_Llim (A)) of the range assumed as a variation range due to individual differences in the opening degree (EV_Llim) of the expansion valve (13). When step 7 (ST7) ends, in step 8 (ST8), a third timer, for example a 20-second timer, is started.

  In step 9 (ST9), the control opening correction unit (34) performs a third timer determination for determining whether or not there is a remaining time of the third timer. When there is a remaining time of the third timer, the control opening correction unit (34) sequentially performs Step 10 (ST10) and Step 11 (ST11). On the other hand, when there is no remaining time of the third timer, the control opening correction unit (34) performs Step 13 (ST13).

  In step 10 (ST10), the control opening correction unit (34) calculates a low pressure threshold (Pjdg) for determining whether or not the expansion valve (13) is open. The low pressure threshold value (Pjdg) is calculated using the following equation 1. When step 10 (ST10) is completed, step 11 (ST11) is performed.

Formula 1: Pjdg = Ref (RS) × F
In the above formula 1, Pjdg represents a low pressure threshold, RS represents a measured value of the suction temperature sensor (27), and F represents a safety factor (for example, F = 0.5). Ref is a function for obtaining the saturation pressure of the refrigerant to be used from the temperature with a gauge pressure. When the above equation 1 is used, a pressure in which the safety factor is taken into account at the saturation pressure at the temperature of the measured value (RS) of the suction temperature sensor (27) is obtained as the low pressure threshold value.

  In step 11 (ST11), a determination operation (second operation) is performed to determine whether or not the expansion valve (13) is open, that is, whether or not the refrigerant is passing through the expansion valve (13). When the measured value (LPT) of the low pressure sensor (24) exceeds the low pressure threshold (Pjdg), the control opening correction unit (34) determines that the expansion valve (13) is open, and step 12 (ST12 )I do. On the other hand, when the measured value (LPT) of the low pressure sensor (24) is equal to or lower than the low pressure threshold (Pjdg), the control opening correction unit (34) determines that the expansion valve (13) is not open, Return to 9 (ST9).

  In step 12 (ST12), the control opening correction unit (34) detects the current control pulse (EV) value of the expansion valve (13) as the valve opening (EV_Llim). The detected valve opening degree (EV_Llim) is temporarily stored in the storage unit (35). When step 12 (ST12) is completed, step 16 (ST16) is performed. The valve opening degree detection operation ends in step 12 (ST12), and the first correction operation starts from step 16 (ST16).

  In step 13 (ST13), it is determined whether or not the current control pulse (EV) of the expansion valve (13) is below a predetermined upper limit value (Hlim) (for example, Hlim = 150 pulses). The upper limit value (Hlim) is a value of the upper limit value of a range assumed as a variation range due to individual differences in the valve opening degree (EV_Llim).

  In step 13 (ST13), when the current control pulse (EV) is equal to or higher than the upper limit value (Hlim), the control opening correction unit (34) performs step 14 (ST14) to perform the valve opening degree detection operation. Exit. In step 14 (ST14), the control opening correction unit (34) detects the upper limit value (Hlim) as the valve opening degree (EV_Llim). The detected valve opening degree (EV_Llim) is temporarily stored in the storage unit (35). In the opening degree detection operation, when the current control pulse (EV) reaches a predetermined upper limit value (Hlim), even if the measured value (LPT) of the low pressure sensor (24) is less than the low pressure threshold (Pjdg) It is determined that the expansion valve (13) is open.

  On the other hand, in step 13 (ST13), when the current control pulse (EV) is below the predetermined upper limit value (Hlim), the control opening correction unit (34) still opens the expansion valve (13). It is determined that the state has not been reached, and the process returns to step 8 (ST8) through step 15 (ST15). In step 15 (ST15), the control opening correction unit (34) adds a predetermined set value (ΔEV) (eg, ΔEV = 20 pulses) to the current control pulse (EV) of the expansion valve (13). A pulse signal as a control pulse (EV ′) is output to the expansion valve (13) to perform an opening increase operation (first operation) for adjusting the opening of the expansion valve (13). After the opening increase operation, the control pulse (EV ′) of the pulse signal output in the opening increase operation becomes the current control pulse (EV) of the expansion valve (13).

  From step 16 (ST16), as described above, the first correction operation is performed. In step 16 (ST16), the control opening correction unit (34) calculates a correction value (EV_adj) for correcting the lower limit command value (EVL). The correction value (EV_adj) is calculated using Expression 2 shown below.

Formula 2: EV_adj = EV_Llim−EV_ave
In Equation 2, EV_adj represents a correction value, and EV_ave represents an assumed value (for example, EV_ave = 100) of the opening degree (EV_Llim) of the expansion valve (13) used in the refrigeration apparatus (10). As an assumed value of this embodiment, an average value of an upper limit value and a lower limit value of a range assumed as a variation range due to individual differences in the valve opening degree (EV_Llim) is used. The correction value (EV_adj) is a negative value when the average value (EV_ave) is larger than the valve opening degree (EV_Llim). The correction value (EV_adj) calculated by Equation 2 is stored in the storage unit (35). Note that when the correction value (EV_adj) previously stored in the storage unit (35) exists, the new correction value (EV_adj) is overwritten and stored in the storage unit (35). When step 16 (ST16) is completed, step 17 (ST17) is performed.

  In step 17 (ST17), the control opening correction unit (34) corrects the lower limit command value (EVL) using the correction value (EV_adj). The lower limit value (EVL ′) of the corrected control pulse is a value obtained by adding the correction value (EV_adj) to the lower limit value (EVL) set in the valve control unit (33). In step 17 (ST17), each lower limit (EVL) is corrected for each operating condition. When step 17 (ST17) ends, the first correction operation ends. When the first operation ends, the compressor (11) is started and the external fan (21) is started, and the cooling operation which is a normal operation is started.

  Next, the second correction operation will be described with reference to FIG. During the second correction operation, the superheat degree control by the valve control unit (33) is interrupted.

  In this refrigeration system (10), when adjusting the superheat degree (SH) of the refrigerant at the outlet of the internal heat exchanger (14), the valve control unit (33) sets the lower limit command value (EVL) to the control pulse ( EV) may be output to forcibly reduce the opening of the expansion valve (13). The second correction operation is performed, for example, immediately after the valve control unit (33) outputs a pulse signal having the lower limit command value (EVL) as a control pulse (EV).

  In the second correction operation, first, in step 21 (ST21), the control opening correction unit (34) determines whether or not the current control pulse (EV) of the expansion valve (13) is at the lower limit command value (EVL). Judgment is made. When the current control pulse (EV) of the expansion valve (13) is in the lower limit control state in which the control valve correction unit (34) is equal to the lower limit command value (EVL), the control opening correction unit (34) performs step 22 (ST22). Do. On the other hand, when the current control pulse (EV) of the expansion valve (13) is not equal to the lower limit command value (EVL), the control opening correction unit (34) activates a fourth timer that is a 120-second timer, for example. If it is in the middle, the fourth timer is stopped and reset in step 23 (ST23), and then the second correction operation is terminated. When the second correction operation ends, the superheat degree control by the valve control unit (33) is resumed.

  In step 22 (ST22), the control opening correction unit (34) determines whether or not the fourth timer has already been started, that is, whether or not the fourth timer is being activated. If the fourth timer has not yet been started, the control opening correction unit (34) activates the fourth timer in step 24 (ST24) and then performs step 25 (ST25). On the other hand, if the fourth timer has already been started, the control opening correction unit (34) performs step 25 (ST25) without performing step 24 (ST24).

  In step 25 (ST25), the control opening correction unit (34) performs measurement value (LPT) of the low pressure sensor (24), measurement value of the inlet temperature sensor (25), and measurement value of the outlet temperature sensor (26). And the degree of superheat (SH) of the refrigerant at the outlet of the internal heat exchanger (14) is calculated. The control opening correction unit (34) calculates the difference between the measured value of the inlet temperature sensor (25) and the measured value of the outlet temperature sensor (26) as the degree of superheat (SH). When step 25 (ST25) is completed, step 26 (ST26) is performed.

  In step 26 (ST26), the control opening correction unit (34) determines whether to correct the lower limit command value (EVL) to the open side. The control opening correction unit (34) has a first-first condition that the measured value (LPT) of the low-pressure sensor (24) falls below a predetermined second low-pressure reference value (for example, −60 kPa), and step 25 (ST25). When at least one of the first to second conditions that the degree of superheat (SH) of the refrigerant calculated in (1) exceeds a predetermined first reference superheat degree (for example, 10 ° C.) is satisfied, the lower limit command value (EVL) is moved to the opening side. Since it is determined that correction is necessary, step 27 (ST27) and step 28 (ST28) are sequentially performed. On the other hand, the control opening correction unit (34) performs Step 29 (ST29) when neither the 1-1 condition nor the 1-2 condition is satisfied. The 1-1 condition and the 1-2 condition are that the refrigerant flow rate that passes through the expansion valve (13) in the lower limit control state is a predetermined low state, that is, the refrigerant flow rate that passes through the expansion valve (13) is an appropriate flow rate. This is a determination condition for determining whether or not there are fewer states.

  In step 27 (ST27), the control opening correction unit (34) corrects the lower limit command value (EVL) using Equation 3 shown below. Further, in step 28 (ST28), the control opening correction unit (34) corrects the correction value (EV_adj) using Equation 4 shown below. The corrected correction value (EV_adj ′) is overwritten and stored in the storage unit (35).

Formula 3: EVL '= EVL + E1
Formula 4: EV_adj '= EV_adj + E1
In Equation 3, EVL ′ represents a corrected lower limit command value, EVL represents a lower limit command value before correction, and E1 represents a first corrected opening (for example, E1 = 4 pulses). In Equation 4, EV_adj ′ represents a corrected value after correction, and EV_adj represents a corrected value stored in the storage unit (35). The first correction opening (E1) is set in advance in the control opening correction unit (34). A value smaller than the set value (ΔEV) is used for the first correction opening (E1).

  When step 28 (ST28) ends, the second correction operation ends. The valve control unit (33) restarts the superheat control after the end of the second correction operation, and outputs a pulse signal having the corrected lower limit command value (EVL ′) as a control pulse to the expansion valve (13), Adjust the opening of the expansion valve (13) to the open side. When the opening degree of the expansion valve (13) is adjusted, the flow rate of the refrigerant passing through the expansion valve (13) increases, so that the low pressure of the refrigeration cycle increases and the outlet of the internal heat exchanger (14) Refrigerant superheat decreases.

  In step 29 (ST29), the control opening correction unit (34) performs a fourth timer determination for determining whether or not there is a remaining time of the fourth timer started in step 24 (ST24). When step 29 (ST29) ends, step 30 (ST30) is performed. If there is no remaining time of the fourth timer, the control opening correction unit (34) proceeds to step 30 (ST30). On the other hand, the control opening correction unit (34) ends the second correction operation when there is a remaining time of the fourth timer.

  In step 30 (ST30), the control opening correction unit (34) determines whether or not the lower limit command value (EVL) is corrected to the closing side. When the second condition that the degree of superheat (SH) of the refrigerant calculated in step 25 (ST25) falls below a predetermined second reference superheat degree (for example, 0 ° C.) is satisfied, Since the refrigerant sucked into the compressor (11) is in a wet state, it is determined that the lower limit command value (EVL) needs to be corrected to the close side, and step 31 (ST31) and step 32 (ST32 ) In order. On the other hand, if the second condition is not satisfied, the control opening correction unit (34) ends the second correction operation as it is. The second condition is that the refrigerant flow rate passing through the expansion valve (13) in the lower limit control state is in a predetermined excess state, that is, the refrigerant flow rate passing through the expansion valve (13) is larger than the appropriate flow rate. This is a determination condition for determining whether or not.

  In step 31 (ST31), the control opening correction unit (34) corrects the lower limit command value (EVL) using Equation 5 shown below. Further, in step 32 (ST32), the control opening correction unit (34) corrects the correction value (EV_adj) using Equation 6 shown below. The corrected correction value (EV_adj ′) is overwritten and stored in the storage unit (35).

Formula 5: EVL '= EVL-E2
Formula 6: EV_adj ′ = EV_adj−E2
In Equation 5, EVL ′ represents a corrected lower limit command value, EVL represents a lower limit command value before correction, and E2 represents a second corrected opening (for example, E2 = 2 pulses). In Equation 6, EV_adj ′ represents a corrected value after correction, and EV_adj represents a corrected value stored in the storage unit (35). The second correction opening (E2) is preset in the control opening correction unit (34). A value smaller than the first correction opening (E1) is used for the second correction opening (E2).

  When step 32 (ST32) ends, the second correction operation ends. The valve control unit (33) restarts the superheat control after the end of the second correction operation, and outputs a pulse signal having the corrected lower limit command value (EVL ′) as a control pulse to the expansion valve (13), Adjust the opening of the expansion valve (13) to the closed side. When the opening degree of the expansion valve (13) is adjusted, the flow rate of the refrigerant passing through the expansion valve (13) decreases, so the degree of superheat of the refrigerant at the outlet of the internal heat exchanger (14) increases, and the compressor (11) avoids wet conditions that are easily damaged. The control opening correction unit (34) starts the second correction operation again after a predetermined time (for example, 1 minute) has elapsed since the end of the second correction operation.

-Effect of the embodiment-
In this embodiment, the valve opening degree which is the command value of the opening degree when the expansion valve (13) changes from the closed state to the open state is detected, and the expansion valve (13) is detected using the detected valve opening degree. Therefore, the opening characteristic of the expansion valve (13) is reflected in the control of the expansion valve (13). That is, the control of the expansion valve (13) is performed in consideration of individual differences of the expansion valve (13). Therefore, individual differences of the expansion valve (13) are reflected in the flow rate of the refrigerant passing through the expansion valve (13), so that the flow control by the expansion valve (13) can be optimized.

  Moreover, in this embodiment, the high pressure of the refrigeration cycle when performing the valve opening degree detection operation is made constant. Here, in the case where the high pressure of the refrigeration cycle is not adjusted before the valve opening degree detection operation, the refrigeration cycle when the valve opening degree detection operation is performed depending on operating conditions such as the temperature of the air sent to the condenser, for example. Therefore, the pressure of the refrigerant acting on the expansion valve (13) varies depending on the operating conditions. For this reason, the degree of change in the state of the low-pressure refrigerant when the expansion valve (13) changes to the open state is not constant depending on the operating conditions, making it difficult to accurately detect the valve opening. On the other hand, in this embodiment, since the high pressure of the refrigeration cycle at the time of performing the opening degree detection operation is made constant, the pressure of the refrigerant acting on the expansion valve (13) is independent of the operating conditions. It becomes constant. Therefore, since the degree of change in the state of the low-pressure refrigerant when the expansion valve (13) changes to the open state is constant regardless of the operating conditions, the valve opening degree can be accurately detected.

  In the present embodiment, a pressure value that changes more rapidly than the temperature is used to detect the valve opening degree. For this reason, it is possible to perform the valve opening degree detection operation in a relatively short time.

  In the present embodiment, when the opening command value reaches the upper limit, the upper limit is detected as the valve opening regardless of the state of the low-pressure refrigerant. The valve opening is always a value that does not exceed the range assumed as the variation range due to individual differences in the valve opening. Therefore, even when the change in the state of the low-pressure refrigerant when the expansion valve (13) is changed to the open state does not change, the value of the valve opening degree is Therefore, it is possible to prevent the variation range from becoming too large beyond the range assumed.

  Moreover, in this embodiment, since the control opening correction | amendment part (34) correct | amends a minimum command value using a valve opening degree, the opening characteristic of an expansion valve (13) is reflected in a minimum command value. Here, in the container refrigeration apparatus (10) having a wide range of the set temperature in the warehouse, the standard of the expansion valve (13) is determined in accordance with the condition where the set temperature in the warehouse is relatively high (for example, 30 ° C.). Is common. For this reason, the opening degree of the expansion valve (13) is controlled in the vicinity of the lower limit value of the control pulse (EV) when the set temperature in the chamber is set to a low condition (for example, −30 ° C.). Accordingly, in the conventional refrigeration apparatus (10) that does not correct the lower limit command value, for example, when the opening degree of the expansion valve (13) is shifted to the opening side with respect to the opening degree command value, the compressor (11) When the superheat degree of the intake refrigerant of the engine is lower than the target superheat degree, even if the opening degree of the expansion valve (13) is reduced until the opening degree command value reaches the lower limit command value, The actual opening of (13) cannot be reduced. For this reason, the refrigerant | coolant flow rate which passes an expansion valve (13) increases more than an appropriate flow rate, and there exists a possibility that it cannot cancel that the suction | inhalation refrigerant | coolant of a compressor (11) will be in a wet state. On the other hand, in the present embodiment, the opening degree characteristic of the expansion valve (13) is reflected in the lower limit command value, and the lower limit command value is a value considering individual differences of the expansion valve (13). For this reason, when the degree of superheat of the refrigerant sucked in the compressor (11) decreases, the expansion valve (13) can be throttled to an opening degree that is assumed in the control or an opening degree close thereto. Therefore, since it can suppress that the refrigerant | coolant flow rate which passes an expansion valve (13) becomes larger than an appropriate flow rate, since the expansion valve (13) cannot be throttled, the suction | inhalation refrigerant | coolant of a compressor (11) Can be prevented from becoming wet.

  In the present embodiment, the refrigerant flow rate that actually passes through the expansion valve (13) in the lower limit control state is determined, and it is determined whether or not the lower limit command value corrected by the valve opening degree is an appropriate value. In the above, the lower limit command value is corrected again when correction is necessary. Therefore, since the lower limit command value corrected by the valve opening degree can be corrected to a more appropriate value, the flow control by the expansion valve (13) in the lower limit control state can be further optimized.

  Further, in this embodiment, when it is determined that the refrigerant flow rate that actually passes through the expansion valve (13) is lower than the proper flow rate in the control in the lower limit control state, the opening degree is corrected using the valve opening degree. The lower limit command value is corrected to a value larger than the lower limit command value. Therefore, when the lower limit command value corrected using the valve opening degree is smaller than an appropriate value, the lower limit command value can be brought close to an appropriate value.

  Further, in this embodiment, when it is determined that the refrigerant flow rate that actually passes through the expansion valve (13) is higher than the appropriate flow rate in the control in the lower limit control state, the opening degree is corrected using the valve opening degree. The lower limit command value is corrected to a value smaller than the lower limit command value. Therefore, when the lower limit command value corrected using the valve opening degree is larger than an appropriate value, the lower limit command value can be brought close to an appropriate value.

-Modification of the embodiment-
A modification of the embodiment will be described. In this modified example, the control opening correction unit (34) is configured to perform the valve opening opening detection operation when the refrigeration apparatus (10) is activated only when a predetermined condition is satisfied.

  Specifically, as shown in FIG. 7, the refrigeration apparatus (10) includes a selection button (a user can select whether or not to perform the valve opening degree detection operation when the refrigeration apparatus (10) is started up). 36) is provided. The control opening correction unit (34) performs the opening degree detection operation when the refrigeration apparatus (10) is activated when the selection button (36) for selecting execution of the opening degree detection operation is input. It is configured. That is, the predetermined condition is a condition that there is an input of the selection button (36) for selecting execution of the valve opening degree detection operation.

  When there is an input of the selection button (36) for selecting execution of the opening degree detection operation, the control opening correction unit (34) sets the correction value (EV_adj) stored in the storage unit (35). to erase. The control opening correction unit (34) performs the valve opening degree detection operation and the first correction operation after the preparation operation and the pump down operation. In the opening degree detection operation, the opening degree (EV_Llim) is detected. In the first correction operation, the lower limit command value (EVL) is corrected using the valve opening degree (EV_Llim) detected in the valve opening degree detection operation, and is calculated using the valve opening degree (EV_Llim). The corrected value (EV_adj) is stored. Then, when the first correction operation is finished, the valve control unit (33) performs superheat control.

  On the other hand, in the controller (30), when there is no input of the selection button (36) for selecting execution of the opening degree detection operation, the control opening correction unit (34) is activated after the refrigeration apparatus (10) is started. Only the first correction operation is performed. In the first correction operation, the lower limit command value (EVL) is corrected using the correction value (EV_adj) stored in the storage unit (35). Then, when the first correction operation is finished, the valve control unit (33) performs superheat control.

  In this modification, whether or not the valve opening degree detection operation is performed is determined depending on whether or not the selection button (36) is input when the refrigeration apparatus (10) is started. Therefore, by executing the valve opening degree detection operation, it is possible to prevent an increase in the time until the start of normal operation every time the refrigeration apparatus (10) is started.

  In this modified example, even when the opening degree detection operation is not executed when the refrigeration apparatus (10) is started, the lower limit command value (EV_adj) is stored using the correction value (EV_adj) stored in the storage unit (35). EVL) is corrected. Therefore, even if the opening degree detection operation is not executed when the refrigeration system (10) is started, the flow rate control by the expansion valve (13) reflects the opening characteristic of the expansion valve (13) in the lower limit command value (EVL). Can be optimized.

<< Other Embodiments >>
About the said embodiment, it is good also as the following structures.

  In the above embodiment, the control opening correction unit (34) controls the control pulse (EV) so that the actual opening of the expansion valve (13) approaches the control opening determined by the control pulse (EV). The control pulse (EV) may be corrected using the valve opening degree (EV_Llim) in the entire control region from the lower limit value to the maximum value.

  In the above embodiment, the opening degree detection operation and the first correction operation may be performed before shipping the refrigeration apparatus (10) at a factory that manufactures the refrigeration apparatus (10).

  Moreover, about the said embodiment, the control opening correction | amendment part (34) may be comprised so that valve opening opening degree (EV_Llim) may be memorize | stored instead of correction value (EV_adj).

  In the above embodiment, the refrigeration apparatus (10) may be configured to perform a supercritical cycle in which the high pressure of the refrigeration cycle is set to a value higher than the critical pressure of the refrigerant. In that case, one of the external heat exchanger (12) and the internal heat exchanger (14) operates as a gas cooler, and the other operates as an evaporator.

  In the above embodiment, the refrigeration apparatus (10) may be a refrigeration apparatus other than the container refrigeration apparatus (for example, an air conditioner).

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention is useful for a refrigeration apparatus including a refrigerant circuit provided with an expansion valve having a variable opening.

DESCRIPTION OF SYMBOLS 10 Refrigeration apparatus 11 Compressor 12 External heat exchanger 13 Expansion valve 14 Internal heat exchanger 20 Refrigerant circuit 21 External fan 22 Internal fan 30 Controller 31 Compressor control part 32 Fan control part (valve opening degree detection means) )
33 Valve control unit (valve control means)
34 Control opening correction part (valve opening detection means)

Claims (4)

A refrigerant circuit (20) that is provided with a compressor (11) and an expansion valve (13) having a variable opening, and that performs a refrigeration cycle;
A refrigeration apparatus comprising valve control means (33) for controlling the opening of the expansion valve (13),
The command value of the opening degree output to the expansion valve (13) with the compressor (11) stopped after the pump down operation for operating the compressor (11) with the expansion valve (13) closed Whether or not the expansion valve (13) is open based on a change in the state of the low-pressure refrigerant between the expansion valve (13) and the suction side of the compressor (11). The valve opening opening detection operation for detecting the valve opening degree that is the command value of the opening degree when the expansion valve (13) changes from the closed state to the open state is performed. Degree detection means (32, 34),
While the valve control means (33) controls the expansion valve (13) using the valve opening detected by the valve opening detection operation ,
The valve opening degree detecting means (32, 34) has a refrigeration cycle within a certain range from a first high pressure reference value to a second high pressure reference value smaller than the first high pressure reference value during the pump down operation. The refrigeration apparatus is characterized in that the pump-down operation is ended when the high-pressure pressure of the low-pressure side refrigerant is adjusted to be equal to or lower than a predetermined low-pressure reference value . In claim 1,
An external heat exchanger (12) for exchanging heat between the high-pressure refrigerant discharged from the compressor (11) and the external air during the pump-down operation;
While having an external fan (21) for sending external air to the external heat exchanger (12),
The valve opening degree detecting means (32, 34) activates the external fan (21) when the high pressure of the refrigeration cycle exceeds the first high pressure reference value during the pump down operation, When the high pressure of the refrigeration cycle falls below the second high pressure reference value, the outside fan (21) is stopped, so that the high pressure of the refrigeration cycle is changed from the first high pressure reference value to the second high pressure reference value. The refrigeration apparatus characterized by adjusting within a certain range. In claim 1 or 2,
Prior to the pump-down operation, the valve opening degree detection means (32, 34) controls the high pressure of the refrigeration cycle while operating the compressor (11) with the expansion valve (13) open . A refrigeration apparatus characterized in that a preparatory operation is performed to adjust within a certain range from one high pressure reference value to the second high pressure reference value . In any one of Claims 1 thru | or 3,
The valve opening degree detection means (32, 34) detects a command value of the degree of opening when the pressure of the low-pressure side refrigerant exceeds a predetermined low pressure threshold as the valve opening degree. .

Images