JPS6332272A - 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 a refrigeration system, and more particularly to a refrigeration system having a function of determining whether the amount of circulating refrigerant is depleted of gas.

(Prior Art) As a conventional example of determining whether the amount of circulating refrigerant is out of gas, for example, the applicant's earlier application (Japanese Patent Application No. 40741/1983)
(No.). This device will be explained based on FIG. 2, which is an embodiment of the present invention. As shown in the figure, this device has a configuration in which one outdoor unit X is connected to a plurality of indoor units A-D. , each indoor heat exchanger 18 has a flow side branch pipe 15...15 and a gas side branch pipe 17...
17. Also, the first liquid pipe 10 and the second
A liquid receiver 11 is interposed between the liquid pipe 12,
This liquid receiver 11 is connected to the suction pipe 4 of the compression tJ311 via a capillary tube 21 and a pipe 20. Note that a first electric expansion valve 13 is installed in the first liquid pipe 10, and a second electric expansion valve 16 is installed in each downstream branch pipe 15.
...16 are interposed respectively. In addition, the above piping 20
A first temperature sensor 31 is attached to the compression till suction pipe 4, a second temperature sensor +-32 is attached to the compression till suction pipe 4, and a fourth temperature sensor 34 is attached to the gas side branch pipe 17, respectively.

The first temperature sensor 31 is for detecting the pressure-equivalent saturation temperature T1 of the low-pressure gas refrigerant.

In the above-mentioned apparatus, during cooling operation, the temperature of the evaporative refrigerant at the outlet of the indoor heat exchanger 18 serving as an evaporator is detected by the fourth temperature sensor 34, and this detected temperature T4 and the above-mentioned The degree of superheat of the evaporative refrigerant is determined from the detected temperature T1 of the first temperature sensor 31, and each of the second electric expansion valves 16...1
6 opening degree control is performed. On the other hand, during heating operation, the degree of superheat is determined from the temperature T2 detected by the second temperature sensor 32 and the temperature T1 detected by the first temperature sensor 31, and the opening degree of the first electric expansion valve 13 is controlled in the same manner as above. Do the following. When the detected degree of superheat is greater than the reference degree of superheat, each electric expansion valve 6, j3 is operated to the open side in order to increase the amount of circulating refrigerant; If the detected degree of superheat does not decrease even if the temperature is continued, and each electric expansion valve 16.13 continues to be at or above the set upper limit opening for a certain period of time, abnormal dryness will be determined, and even gas shortage will occur. The system determines this and outputs an abnormal signal.

(Problems to be Solved by the Invention) By the way, in the above device, each electric expansion valve 16.1
3 as the initial opening degree and start operation, and then when controlling the opening degree of the electric expansion valve 16 and 13 by successively determining the degree of superheating, a limit is set on the additional opening degree per - times. For example, if there is a leak from the refrigerant piping while the equipment is stopped, and this causes a large amount of gas to be depleted, the opening will reach the set upper limit opening corresponding to this gas depletion condition. It takes a long time to complete the process, and in addition, the lack of gas is determined after a certain period of time has elapsed, resulting in problems such as burnout of the compressor coil during this time. Furthermore, in the case of a state in which the refrigerant in the liquid pipe 10.12 is not liquefied, or in the case of a large gas shortage state where liquefaction is insufficient, the first temperature sensor 31 cannot detect the temperature as the pressure equivalent saturation temperature. Therefore, the above-mentioned opening degree control based on the detection of the degree of superheating cannot be performed, so there is a problem that the abnormality of the gas shortage state cannot be detected.

In addition, the temperature sensor 30, which is generally attached to the discharge pipe of the compressor, is provided for the purpose of preventing abnormal temperature rise inside the compressor in such a gas starvation state. This method assumes a temperature correlation between the inside of the compressor and the discharge piping due to heat transfer from the refrigerant, such as the amount of heat generated in the compressor being transferred to the discharge piping by the internally circulating refrigerant. If the amount of refrigerant decreases significantly and the above temperature correlation is no longer obtained, it is not possible to automatically detect a gas shortage, especially if the gas shortage is greater than at startup. There was a problem.

This invention was made in order to solve the above-mentioned conventional problems, and even when a large gas shortage occurs, it can be determined and prevent troubles such as compressor coil burnout from occurring. An object of the present invention is to provide a refrigeration device that can prevent the above problems.

(Means for Solving the Problems) Therefore, as shown in FIG. 1, the refrigeration system of the present invention includes a compressor 1 whose capacity is controlled by the compression capacity according to the required load of 18 heat exchangers on the user side. The refrigeration system has input amount detection means 48 for detecting the input amount to the compressor 1, and storage means 52 for storing in advance a reference input amount according to the compression capacity.
and a determining means 50 that determines the amount of circulating refrigerant to be in a gas-deficient state when the input amount detected above is equal to or less than the reference input amount corresponding to the compression capacity for a predetermined period of time, and an output of the determining means 50. An abnormality signal output means 51 is provided for receiving the abnormality signal and outputting an abnormality signal.

(Function) In the above device, in the compressor 1 which is driven to provide the required compression capacity, the input amount corresponding to the required compression work is applied to the circulating refrigerant during normal operation. The standard input amount set based on the total input amount is
It is stored in the storage means 52 in advance. On the other hand, when there is a gas shortage, in the compressor 1 that is driven to provide the same compression capacity as described above, the amount of input required for compression work for a smaller amount of circulating refrigerant than in normal times becomes smaller than in normal times. Therefore, by comparing the input amount during actual operation with the reference input amount, it is possible to determine whether the gas is out of gas. In particular, in the above case, the larger the out-of-gas condition, the larger the difference between the normal input amount and the input amount at the time of out-of-gas, and therefore, it is possible to distinguish even in a completely out-of-gas condition. It is. Therefore, the input amount detection means 4B and the determination means 50 for comparing and determining the detected input amount and the reference input amount.
By providing the abnormality signal output means 51, it is possible to automatically detect even an excessively low gas condition, and it is possible to prevent troubles such as burnout of the coils of the compressor 1.

(Example) Next, a refrigeration system of the present invention will be described in detail using an air conditioner as an example with reference to the drawings.

First, Figure 2 shows a refrigerant circuit diagram of a multi-model air conditioner equipped with four indoor units.
1 indicates an outdoor unit, and A to D indicate the first to fourth indoor units, respectively. The outdoor unit X has a compressor 1
The compressor 1 has a capacity controlled by an inverter 2, and its discharge pipe 3 and suction pipe 4 are connected to a four-way switching valve 5. A first gas pipe 6 and a second gas pipe 7 are connected to the four-way switching valve 5, respectively, and an outdoor heat exchanger 8 is connected to the second gas pipe 7. Note that an outdoor fan 9 is attached to the outdoor heat exchanger 8. Further, a first liquid pipe 10, a liquid receiver 11, and a second liquid pipe 12 are sequentially connected to the outdoor heat exchanger 8, and a first electric expansion valve 13 is interposed in the first liquid pipe 10. has been done.

The second liquid pipe 12 is connected to the header 14,
A plurality of (in the case of the figure, four) downstream branch pipes 15...15 branch from this header 14, and each downstream branch pipe 15...15 branches off from this header 14.
・Second electric expansion valves 16, . . . 16 are interposed in each of the valves 15. On the other hand, four gas side branch pipes 17, . 18 are connected. Note that an indoor fan 19 is attached to each indoor heat exchanger 18, and both 18.1
9 constitute indoor units A-D. Further, the liquid receiver 11 and the suction pipe 4 of the compressor 1 are connected by a pipe 20, and a capillary tube 21 is interposed in the pipe 20. In the figure, 22 represents a gas shutoff valve, 23 represents a liquid shutoff valve, 24.25 represents a muffler, and 26 represents an accumulator.

In the above air conditioner, as shown by the solid line arrow in the figure, the refrigerant discharged from the compressor 1 is transferred from the outdoor heat exchanger 8, which serves as a condenser, to the indoor heat exchangers 18, which serve as evaporators. Cooling operation is performed by circulating the refrigerant, and conversely, heating is performed by circulating the refrigerant discharged from the compressor 1 from the indoor heat exchanger 18, which serves as a condenser, to the outdoor heat exchanger 8, which serves as an evaporator. The vehicle is operated (dashed line arrow in the figure).

In the refrigerant circuit, a first temperature sensor 31 is attached to the outlet side of the capillary tube 21, and this first temperature sensor 31 detects the pressure-equivalent saturation temperature T1 of the low-pressure gas refrigerant. It is for the purpose of Further, a second temperature sensor 32 is installed in the suction pipe 4 of the compressor 1, third temperature sensors 33, . . . 33 are installed in each of the liquid side branch pipes 15, .
6...16 has a fourth temperature sensor 34...34, and the compression tJ311 discharge pipe 3 has a fifth temperature sensor 30.
The functions of each of these temperature sensors will be described later.

FIG. 3 shows a block diagram of the control system of the air conditioner. As shown in the figure, outdoor unisex) X has an outdoor control device 35, and indoor unisex) A to D each have an indoor control device 36. An operation switch 37 and an indoor thermostat 38 are respectively connected to the indoor control device 36, and the following three signals are sent from the indoor control device 3G to the outdoor control device 35, namely, (1) the operation switch 37 is ON; , and an operation command signal issued when the room temperature has not reached the set temperature; (2) a ΔT multiplication signal corresponding to the temperature difference between the detected room temperature and the set temperature; and (2) a model code signal.

On the other hand, the outdoor control device 35 includes a load capacity value grasping section 39 that grasps the total load capacity value ΣS of the indoor units A-D with the operation command, and a load capacity value grasping section 39 that grasps the total load capacity value ΣS of the indoor units A-D with the operation command
Temperature difference detection unit 40 that calculates ΣΔT by integrating the ΔT times signal of
and a frequency control unit 41 that issues an operating frequency command signal based on the above ΣS and ΣΔT, and upon receiving this command signal,
The compressor 1 has an inverter control section 43 that controls the inverter 2 to which the drive motor 1a of the compressor 1 is connected.

Further, the outdoor control device 35 further includes a valve control unit 42 that controls the opening degrees of the first and second electric expansion valves 13, 16, . . . 16 based on the temperatures detected by the first to fourth temperature sensors 31 to 34. have. Furthermore, the outdoor control device 35
As will be described later, the refrigerant refrigerant flow rate determining section 46 includes a circulating refrigerant state determining section 46, a discharge pipe temperature monitoring section 47, and a determining section 50, each having a function of determining whether or not the amount of circulating refrigerant is out of gas.

In the control circuit having the above configuration, control of the compression capacity of the compressor 1, that is, control of the inverter frequency will first be explained.

In the outdoor control device 35, as described above, based on the model code signal output from each indoor control device 36... The load capacity ΣS is determined by the following procedure. First, the model code signal output from the indoor control devices 36...36 is determined according to the capacity of each of the 18 indoor heat exchangers, and is, for example, 2240 kcal.
For the capacity of / h, the code of rooo J is 28
roll J for 00kcal/h, 3550kcal
Rolo J for l/h, also 4500kcal
/ h is defined as roll J, respectively, and these codes are stored for each indoor unit A to D. Furthermore, in the load capacity grasping section 39, the storage section 44 stores the load capacity value S corresponding to the above-mentioned model code. (7) Load capacity value S is capacity 2240
kcal/h (tJM type code rooo J) is the standard value "1", 2800 kcal/h (model code r001 J) is rl, 25J, 3550 kcal
/ h (model code ro10 J) to rl, 5 J
, 4500kcal/h (model code roll
J) is set as "2", and
The load capacity understanding circuit 45 reads out the load capacity value S for each indoor unit A to D for which an operation command is given, and
The sum of these ΣS is calculated.

In the outdoor control device 35, the total load capacity value ΣS of the indoor units A-D with the operation command is grasped as described above, and this is combined with the room temperature and set temperature according to the indoor number-mo 38. The frequency of the compressor 1 is controlled by the frequency control section 41 based on the signal ΣΔT corresponding to the difference.

That is, an initial setting frequency corresponding to the above ΣS and ΣΔT is stored, and operation is performed at the above-mentioned initial setting frequency at the start of operation and when the number of operating rooms is increased, and after a predetermined period of time, P is set based on ΣΔT. The frequency is changed by control, PID control, etc.

Therefore, for example, indoor units A-D with operation commands
When the number of units is large, the total load capacity value ΣS becomes large, and in this case, the compressor 1 is driven at a high frequency, thereby increasing the air conditioning capacity and simultaneously air conditioning each room with the capacity that meets the demand. That's what I do.

Next, a method of controlling the first and second electric expansion valves 13, 16, . . . 16 by the valve control section 42 will be explained. First, during cooling operation, the first electric expansion valve 13 is maintained fully open, and the opening degree of each second electric expansion valve 16 is controlled, so that the gas refrigerant evaporates in each indoor heat exchanger 18. The degree of superheating is controlled to be approximately constant. in this case,
The difference between the low pressure equivalent saturation temperature T1 detected by the first temperature sensor 31 and the vaporized refrigerant i degree T4...↑4 detected by the fourth temperature sensor 4, that is, the detected superheat degree (T4-TI)
and the deviation from the reference superheat degree SHO = (T4-TI)-
The opening degree of each second electric expansion valve 16...16 is increased or decreased by the opening degree P=C-E (C is a positive constant) proportional to SHO (P>0 is open, p<o is closed), so-called It performs P control.

On the other hand, during heating operation, the degree of superheating of the refrigerant evaporating in the outdoor heat exchanger 8 is controlled by PID using the first electric expansion valve 13, and each of the covered second electric expansion valves 16... Control (referred to as Frl control) is performed to equalize the condensed refrigerant temperature at the outlet of each indoor heat exchanger 18. The former is the difference between the low pressure equivalent saturation temperature T1 detected by the first temperature sensor 31 and the evaporative refrigerant temperature T2 detected by the second temperature sensor 32, that is, the detected superheat degree (T2-
TI') and this detected superheat degree (T2-
TI ) and reference superheat degree 5IIO tonnage deviation E = (TI
-T1. )-5t(0 at each predetermined sampling time, and the deviation EO1E1, [!2,...
This is a system in which the opening degree of the first electric expansion valve 13 is controlled based on the following equation.

P = KO-EO+ to 1・(EO-El,)+ to 2・
(EO-2El + E2) (However, KO, Kl,
(K2 is a constant) In other words, if P>0, the first electric expansion valve 13 is activated only by P pulse.
Control is performed such that the valve is opened, and if p<o, the valve is closed by P (absolute value) pulse.

Further, the Frl control by each of the second electric expansion valves 16...16 is performed using each of the third temperature sensors 33...33 to determine the condensed refrigerant temperature T3...T at the outlet of the indoor heat exchanger 18...18 during operation.
3 is detected, and the average temperature Tl11 of these detected temperatures T3...T3 is determined, and each of the second electric expansion valves 16...
16, the above average temperature Tl11 and detected temperature T3.
・Quantity P-D proportional to the temperature difference with T3 (Tm-73)
This is done by increasing or decreasing (Tm-T3) (where D is a positive constant) (P>0 is open, P<0 is closed).

The opening degree control signals of the electric expansion valves 13, 16 as described above are also input to the circulating refrigerant state determination unit 46 that determines abnormally wet operation or abnormally dry operation. For example, if the opening degree of the first electric expansion valve 13 continues to be equal to or higher than the set upper limit value during heating for 20 minutes or more, the opening degree of each second electric expansion valve 16 in the driver's cab during cooling will similarly change. If the condition at or above the set upper limit continues for 20 minutes or more, this is determined to be a gas shortage condition, and an abnormal signal is input from the circulating refrigerant condition determination section 46 to the frequency control section 41, and the frequency control section 41 , a signal to stop the compressor 1 is output.

Furthermore, the temperature signal detected by the fifth temperature sensor 30 attached to the discharge pipe 3 of the compressor 1 is transmitted to the discharge pipe monitoring unit 4.
7, and when the detected temperature exceeds 120° C., the discharge pipe temperature monitoring section 47 outputs an actual status signal, and this abnormal signal causes the frequency control section 41 to issue a forced frequency reduction command signal or Even with this process,
If the abnormality signal is not released, a compressor 1 stop signal is output.

The circulating refrigerant state determination unit 46 determines that the liquid pipe 10.1
The circulating refrigerant in 2 is in a liquid state, so it is possible to determine a low-level gas-starvation state within a range in which pressure-equivalent saturation temperature can be detected through the pipe 20. Furthermore, due to the refrigerant flowing in the compressor 1, the temperature within the compressor and the temperature detected by the fifth temperature sensor 30 attached to the discharge pipe are in a range where there is a substantially proportional relationship. Moderate out-of-gas conditions can be automatically detected by the discharge pipe temperature monitoring section 47.However, even more severe out-of-gas conditions,
In other words, the state of the circulating refrigerant in the liquid pipes 10 and 12 is no longer liquid, and therefore the pressure equivalent saturation temperature cannot be detected.
In a gas-deficient state where the amount of circulating refrigerant is below that which can maintain the temperature correlation between the two, the circulating refrigerant state determining section 46 and the discharge pipe temperature monitoring section 47 determine this. will no longer be able to do so. Therefore, in this air conditioner, in order to automatically detect the above-mentioned excessive gas shortage state, a power supply line for driving the compressor 1 to the inverter 2 is provided to detect the supply current value ■i. A determination unit (i.e., determination means) that converts the detected value of the current transformer (i.e., input amount detection means) 48 into a digital signal via the A/I converter 49, and determines the gas shortage state based on this signal. 50, and in response to the output of this determination section 50, an abnormal signal is sent to the frequency control section 41.
An abnormal signal output section (i.e., abnormal signal output means) 51 for inputting to the compressor 1 and a storage section (i.e., storage means) 52 in which a reference current value corresponding to the compression capacity of the compressor 1 is stored in advance are provided. Control is performed as shown in the flowchart in the figure.

First, after the start of operation, as will be described later, a timer T that counts the duration of time during which the input current value H to the inverter 2 is below a set value is reset (step S1), and the following gas shortage determination step is executed. That is, in step S2, the input current value Ii;t- is detected, and then the command frequency output from the frequency control section 41 to the inverter control section 43 at this time is read. Then, in step S4,
The reference input current value 11 for the command frequency is read out from the storage section 44. The storage unit 44 is input with relational data between the frequency and the lower limit current value Il as a data table based on the graph shown in FIG. In FIG. 5, the horizontal axis is the compressor drive frequency, and the vertical axis is the inverter input current value.

In the figure, the shaded area is the normal operating range that takes into account the fluctuation range during normal operation, and its center reference line is 0. IF+0.6
(A) (F is frequency). As shown in the figure, the higher the frequency, the greater the compression capacity, and therefore the greater the input current.

Here, if there is a gas shortage, the compression work of the compressor will decrease, and therefore the power consumption, that is, the input current value during constant voltage drive will be smaller than the above normal state. Gas shortage judgment line I7 is on the lower current side than the normal operating range! has been established. This judgment line Il! 55) +2 is set as the lower limit judgment frequency, and 55)
This method attempts to make a determination at Hz or higher. This is because the IN line is close to the normal operating range at low frequencies,
This is because there is a risk of erroneous determination. On the other hand, as the frequency increases, the proportion of the work required to compress the circulating refrigerant increases in the total power consumption of the compressor. Become. Since the compressor's frequency is controlled according to the load required from the heat exchanger on the user side, even if operation is started with a low frequency as the initial value, if there is a gas shortage, the heat exchanger on the user side will This requirement is not satisfied, and therefore frequency control is performed in the direction of increasing the frequency. From this, even if we cant the judgment line Il on the low frequency side, which tends to cause false judgments, the control frequency will inevitably increase when we run out of gas. The settings enable reliable determination without causing false determination.

Based on the determination line IJ as described above, in step S4 in FIG. 4, the reference current value II corresponding to the current command frequency detected in step S3! is read out from the storage section 52.

Then, the input current value If to the inverter 2 at that time and the above rI! If If exceeds 1 (step 55), it is determined that the condition is normal, and the process returns to step S1, and the above-mentioned monitoring steps 82 to S5 are continued. If Ii is equal to or less than In in step S5, the process moves to step S6, and the timer T starts counting.

This timer T is provided to determine whether the low current input state corresponding to the gas shortage continues for a certain period of time Tc. This is provided to prevent the phenomenon from being judged as a gas shortage. In the above embodiment, Tc is set to a value of 24 minutes based on the time required for the coil of the compressor 1 to burn out when the compressor 1 is completely out of gas. Therefore, in step S7, the process returns to step S2 until the count value of T exceeds Tc, and I
The state determination of t and IJ is repeated. If the time value of the timer T exceeds Tc in step S7, the process moves to step S8, where an abnormal signal is output from the abnormal signal output section 51 to the frequency control section 41, and this signal causes the compressor to
will be suspended. In addition, during the continuation determination step of the low current input state, if It exceeds IN, it is determined that the decrease in the input current value 1i is the above-mentioned temporary transient phenomenon, and the process moves from step S5 to step S1. ,
The time value of the timer T up to that point will be reset and the gas shortage monitoring step will be executed again.

As mentioned above, along with the frequency control operation of the compressor 1, the fourth
By monitoring the input current value to the inverter 2 in parallel as shown in the figure, it is possible to determine whether there is a lack of gas, thereby preventing troubles such as burnout of the coils of the compressor 1. This makes it possible to prevent

In addition, although the above example shows the implementation in an inverter-type multi-type air conditioner, it can also be applied to an air conditioner with only one indoor unit or a refrigeration system with a compression capacity control method of other configurations. It is possible to implement. Furthermore, in the above embodiment, the amount of input to the compressor 1 is the input current value, and the detection means is configured with a current transformer. In the case of a variable capacity compressor with a voltage control configuration, it is also possible to have a configuration that detects the input power amount, or the input voltage value, etc. In these cases, it is possible to detect the input amount such as the input power amount or input voltage value. What is necessary is to adopt a configuration in which a detecting means is provided.

(Effects of the Invention) As explained above, in the refrigeration system of the present invention, when there is a flow rate of refrigerant during normal operation, the amount of input required to provide the required compression capacity is By comparing the reference input amount and the actually detected input amount, if the detected input amount continues to be smaller than the reference input amount, a determination means is provided to determine that the gas is out of gas. In particular, even when an excessive gas shortage occurs, this can be automatically detected, and troubles such as compressor coil burnout can be prevented.

[Brief explanation of drawings]

The figures show an embodiment of the refrigeration system of the present invention. Figure 1 is a functional system diagram, Figure 2 is a refrigerant circuit diagram, Figure 3 is a block diagram of the operation control system, and Figure 4 is a gas shortage determination system. The flowchart diagram, FIG. 5, is a graph showing the relationship between the inverter frequency and the input current value. DESCRIPTION OF SYMBOLS 1... Compressor, 18... Indoor heat exchanger (utilization side heat exchanger), 48... Current transformer (input amount detection means), 50... Judgment part (judgment means), 51... - Abnormal signal output section (abnormal signal output means), 52... storage section (storage means).

Claims (1)

[Claims] 1. A refrigeration system having a compressor (1) whose capacity is controlled by the compression capacity according to the required load on the user side heat exchanger (18) side, which detects the amount of input to the compressor (1). An input amount detection means (48), a storage means (52) for storing in advance a reference input amount according to the compression capacity, and a storage means (52) for storing in advance a reference input amount according to the compression capacity, and a state in which the input amount detected above is equal to or less than the reference input amount according to the compression capacity for a predetermined period of time. determination means (50) for determining the amount of circulating refrigerant to be in a gas-depleted state when the condition continues; and abnormality signal output means (51) for outputting an abnormality signal in response to the output of the determination means (50).
).