JPS6375445A - Pump-down operation controller for refrigerator - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a pump-down operation control device for a compressor included in a refrigeration system.

<Conventional technology> Conventionally, when relocating or replacing the indoor unit of a refrigeration system,
When performing pump-down operation to recover refrigeration to the receiver or condenser in the refrigeration system, close the shutoff valve on the liquid side, operate the compressor, and wait until it appears that most of the refrigerant has been recovered. The procedure is to close the shutoff valve on the gas side and stop the compressor.

(Problems to be Solved by the Invention) However, in the conventional method described above, the determination when refrigerant recovery is complete relies only on the skill level of the operator, and for this purpose, the gas side shutoff valve is closed. If the compressor is shut down too early, refrigerant recovery may be insufficient, or conversely, if the pump-down operation time is too long in an attempt to increase the refrigerant recovery rate, the refrigerant sucked into the compressor may be If it decreases too much, the cooling effect of the refrigerant on the compressor decreases, and the pressure fIUN decreases too much.
Because the internal temperature of the compressor rises rapidly, there are problems such as primary compression seizures.

The present invention has been made in view of this point, and its purpose is to reliably recover refrigerant by accurately informing the operator of when to open and close the closing valve during pump down operation. Another object of the present invention is to stop the operation of the compressor before it reaches a dangerous overheating temperature, thereby effectively preventing accidents such as seizure of the compressor.

(Means for solving the problem) In order to achieve the above object, the solving means of the present invention includes a refrigerant storage device (4), a liquid side closing valve (10a), The target is a refrigeration system equipped with a gas-side shutoff valve (10b).

When the liquid side closing valve (10a) is closed, the compressor (1
); and a suction gas pressure detection means (LPS) for detecting the suction gas pressure of the refrigerant into the refrigerant.
and a compressor (1), which outputs an alarm to the workbench to close the gas side shutoff valve (10b) when the suction gas pressure of the refrigerant falls below a predetermined value in response to the signal. The invention includes an operation control means (12) for stopping the operation of the pressure bit machine (1) before the internal temperature reaches the overheating danger value.

(Function) With the above configuration, in the present invention, when performing pump down operation when relocating the refrigeration equipment, the liquid side closing valve (10a)
The compressor (1) is operated in a closed state, and refrigerant is stored in the refrigerant storage device (4). When the recovered refrigerant decreases and the suction gas pressure falls below a predetermined value, this is detected by the suction gas pressure detection means (LPS), and an alarm is output to work 6 by the alarm output means (BZ). Therefore, the gas side shutoff valve (10b) must be closed by the operator.
will be closed. After that, the compressor (1
) and the operation control means (12) stops the operation of the compressor (1) before the internal temperature of the compressor (1) reaches the overheating danger value. ), it is possible to perform pump-down operation that reliably recovers the refrigerant while effectively preventing seizure accidents.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings from FIG. 2 onwards.

FIG. 2 shows a refrigerant piping system when the present invention is applied to a separate air conditioner, where (A> is an outdoor unit, (
B) is an indoor unit, and the outdoor unit (A) includes a compressor (1) whose capacity is adjusted by an inverter (9) that makes the frequency variable, and a compressor (1) whose capacity is adjusted by an inverter (9) that makes the frequency variable, and a compressor (1) as shown in the solid line in Figure 2 during cooling operation. A four-way switching valve (2) that switches as shown by the broken line during heating operation, an accumulator (3), and an outdoor valve that functions as a condenser during cooling operation, an evaporator during heating operation, and a refrigerant storage during pump-down operation. Heat exchanger(
4), an electric expansion valve (5) that adjusts the refrigerant flow rate and throttles the refrigerant, and a capillary tube (7) as the main equipment. An indoor heat exchanger (6), which functions as an evaporator during operation and a condenser during heating operation, is installed as the main equipment, and each of the above-mentioned main equipment includes a liquid side closing valve <10a) with a service port and a gas The refrigerant pipes (8) are connected to each other through a side closing valve (10b) so that refrigerant can flow therethrough. In addition, (TI-11) is a room temperature thermostat that detects the indoor temperature, and (TH,2) is placed in the discharge pipe of the compressor (1) to detect the temperature of the discharged gas refrigerant T2 (hereinafter referred to as the discharge pipe temperature). A temperature sensor (LPS) detects the pressure LP of the suction gas refrigerant and indicates that LP is at a predetermined value Po.
The pressure switch (11) is a control unit which closes when the pressure becomes lower than (about 0.9-/c+Jg) and is normally in an open state.

FIG. 3 is a schematic wiring diagram showing the connection of the printed circuit board of the control unit (11) with the main equipment, and the control unit (11) includes a room temperature thermostat (THl), a temperature sensor (TI2), a pressure Switch (L
PS) and an external switch (SWl) that issues a command during pump-down operation are connected to the input side. A microcomputer (12) as an operation control means is built into the controller I-roll unit (11), and the memory section of the microcomputer (12) stores information that the compressor is at an overheating danger temperature during normal operation. Discharge pipe temperature TO+ (first setting value) when reaching (for example, about 130°C), upper limit setting value T in the appropriate range
C2 (e.g. about 120'C), the lower limit set value TC3 of the appropriate range (e.g. 110°C), and the superheating limit temperature at low pressure TLI (second set value) of the discharge pipe temperature when LP<PO (e.g. 110°C) degree) is stored in advance. In addition, the output side terminal is equipped with a pulse motor (EV) that controls the opening degree of the electric expansion valve (5) at vIJ, an inverter (9), and a buzzer (B) as an alarm output means that continuously emits an alarm sound.
Z) and a timer (13) for the set time to (about 30 seconds)
are connected. Then, the microcomputer (12) receives the outputs of the sensors and the external switch (SWl>), and controls the pulse motor (Ev) of the electric expansion valve (5), the inverter (9), and the pump connected to the output side terminal. It is designed to control the operation of a down warning buzzer (BZ).

During cooling operation, the flow of refrigerant becomes as shown by the solid arrow in Figure 2, and the refrigerant discharged from the compressor (1) is condensed and liquefied in the outdoor heat exchanger (4) (condenser). After that, it is subjected to a throttling action by the electric expansion valve (5) and the kit/pillar tube (7), and is vaporized in the indoor heat exchanger (6) (evaporator), and then passed through the accumulator (3) and returned to the compressor (1). ). Also, during heating operation, the flow of refrigerant is as shown by the broken line arrow, and the refrigerant discharged from the compressor (1) is condensed and liquefied in the indoor heat exchanger (6), and then the electric expansion valve (
5) and the capillary tube (7), is vaporized in the outdoor heat exchanger (4), and returns to the compressor (1) via the accumulator (3).

In normal operation during cooling/heating operation of the air conditioner, the frequency of the inverter (9) is changed according to the deviation (Ts - Tn) between the set value of the room temperature thermostat (TI-11>) and the humidity of the suction air. 1 (1) is performed.Furthermore, depending on the value of the output frequency, the opening degree of the electric expansion valve (5) is set to a value stored in advance in the memory section of the microcomputer (12), and operation is started. Since then, the system has always been designed to prevent the system from entering the Q operating range.At this time, during the above-mentioned normal operation, the degree of superheating of the refrigerant increases, resulting in a situation where the air conditioning capacity is not fully utilized or pressure 11 & I (1) seizes up. Therefore, the control unit (11) controls the discharge pipe m fJ, T 2 (7)
According to the signal, the superheating limit temperature T C+ of the discharge pipe temperature set in advance is compared with the upper limit setting value TC21 of the appropriate range and the lower limit setting value TC3 of the appropriate range, and T2>Te3, and the refrigerant has entered the overheating region. In this case, the opening degree of the electric expansion valve (5) is increased from the set value determined by the frequency of the inverter (9), and the refrigerant is controlled to eliminate overheating so that the discharge pipe temperature falls within the appropriate range of TO3 to TC2. It is made to be done.

In addition, when Lll≧PO, in which the suction gas pressure L11 is greater than or equal to the set value 00 of the pressure switch (LPS), the discharge gas temperature T2 is greater than or equal to TC+, and when Lp<PO, when T2≧TC3, Each compressor (1) is stopped to prevent seizure or the like due to overheating of the compressor (1).

Then, when it becomes necessary to relocate or replace the indoor unit (B) of the refrigeration system, and it becomes necessary to recover the refrigerant, the pump-down operation is performed according to the procedure shown in the flowchart of Fig. M4.

In the flowchart of FIG. 4, when the switch (SWl> is closed in step S1 and a pump-down command is issued, the liquid side open-close valve (10a>, etc.) is manually closed to start pump-down operation. Then, Step S2
It is determined whether or not the suction gas pressure LP of the compressor (1) is smaller than a predetermined value Po. If LP<Po (YES), the process moves to step S3 and the pressure switch (LPS) is turned on. At this time, an alarm buzzer sounds at the same time in step S4, so the operator must close the gas side shutoff valve (10b).
Alternatively, the refrigerant recovery operation can be completed by sequentially closing the suction side closing valves of the compressor (1), etc. Then, in step $5, it is determined whether the set time to (approximately 30 degrees) has elapsed, and the timer (13) sets the set time to after activation.
When YES is reached after seconds have elapsed, the buzzer (BZ) stops emitting the alarm +11 sound, and both output a stop signal and proceed to step S6.
Proceed to step 1 to stop the compressor (1) and complete the pump-down operation.

In the above embodiment, the danger of overheating of the compressor (1) is detected based on when the suction gas pressure saw reaches a predetermined value PO during pump-down operation and the passage of time from that point. In other words, the change characteristics of the suction gas pressure, discharge pipe temperature, and discharge boat temperature over time after the start of pump down have a constant characteristic curve depending on the model and the type of refrigerant, as shown in Figure 5. are doing. Fifth
In the figure, TM+ indicates the time when the intake gas pressure becomes lower than PO after closing the liquid side closing valve (10a), and TM2
indicates the time when t0 seconds have passed since TMI. In FIG. 5, TM+ is not necessarily constant because it varies depending on conditions such as the refrigerant m present in the indoor unit (B) before the start of pump-down operation, but the time to from TM+ to TM2 is It has been experimentally confirmed that the temperature of the discharge boat is almost constant, and that when the suction gas pressure LP reaches PO, the temperature of the discharge boat reaches the danger of overheating 10 seconds later. Therefore, by stopping the compression 1 (1) 10 seconds after LP<PO, it is possible to effectively prevent a seizure accident due to the upper limit of overheating of the compressor (1).

In addition, 10 seconds is determined as a sufficient time to perform the final operation of refrigerant recovery such as closing the gas side shutoff valve (10b), and by issuing an alarm at TM+, the operator can compress m<1> The necessary operations can be performed reliably until the system stops.

Note that the warning output means is not limited to the above embodiment, and may be any means that provides some kind of warning to the operator, such as an indicator lamp. Further, as shown in FIG. 5, a similar effect can be obtained by installing a pressure sensor for measuring the suction gas pressure in order to detect when the compressor is in danger of overheating.

(Effects of the Invention) As explained above, in the present invention, when the suction gas pressure decreases during pump-down operation of the refrigeration system, an alarm is issued,
In addition to having the operator complete the refrigerant recovery operation, the compressor operation is stopped before the temperature inside the compressor reaches the dangerous overheating temperature value, thereby preventing the compressor from overheating due to insufficient refrigerant and causing a seizure accident. It is possible to reliably recover the refrigerant while effectively preventing the refrigerant from occurring.

[Brief explanation of the drawing]

FIG. 1 is a block diagram that does not show the configuration of the present invention. Figures 2 to 5 show an embodiment of the present invention, with Figure 2 being a refrigerant system diagram, Figure 3 being a wiring diagram for the control unit's printed circuit board, and Figure 4 being a flowchart showing the pump-down operation procedure. FIG. 5 is a characteristic diagram showing the change in state quantity of the refrigerant with respect to time after the start of pump down. <1) Compressor, (4) Outdoor heat exchanger (refrigerant storage), (10a) Liquid side closing valve, (10b)
... Gas side closing valve, (12) ... Microcomputer (operation control means), (LPS) ... Pressure switch (suction gas pressure detection means), BZ ... Buzzer (blow alarm output means). Figure 1 Figure 3 '14: ('Ficon 2

Claims (1)

[Claims] (1) Refrigerant storage equipment (4) and liquid side shutoff valve (1) in the refrigerant circuit.
0a) and a gas side closing valve (10b), the suction gas pressure detection means (1) detects the pressure of suction gas refrigerant to the compressor (1) when the liquid side closing valve (10a) is closed. LPS) and the suction gas pressure detection means (LPS)
an alarm output means (BZ) which receives a signal from PS) and outputs an alarm to the operator to close the gas side shutoff valve (10b) when the suction gas pressure is below a predetermined value;
A refrigeration system characterized by comprising: an operation control means (12) for stopping the operation of the compressor (1) after the alarm is output from the compressor (1) and before the internal temperature of the compressor (1) reaches the overheating danger value. Pump down operation control device.