JPH0820132B2 - Refrigeration equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a refrigerating apparatus including a compressor having a variable compression capacity and a compressor having a constant compression capacity.

(Prior Art) As a conventional example of the refrigerating apparatus as described above, for example, the apparatus described in JP-A-58-221349 can be cited.
In this apparatus, a first compressor of variable rotation speed controlled by an inverter and a second compressor of constant rotation speed are connected in parallel to each other to form a compressor unit, and a condenser and an expansion valve are provided in the compressor unit. , An evaporator is sequentially connected to form an air conditioner.

In the above device, while only the first compressor is operated in the range where the air conditioning load is small, the above is performed when a large air conditioning load that requires a compression capacity exceeding the maximum value of the compression capacity variable width of the first compressor occurs. Switch to simultaneous operation of the first and second compressors. By using such switching control and the compression capacity control of the first compressor together, the variable width of the compression capacity of the first compressor can be made relatively small. Therefore, even if the inverter control device is configured with a small capacity, control corresponding to a load with a large fluctuation range is possible, and compared with the case where it is configured with one compressor equipped with a large capacity inverter control device, There is an advantage that the manufacturing cost of the compressor unit can be reduced.

The operation control of the first and second compressors will be described with reference to the drawings of the embodiment of the present invention. This operation control is as shown in the graph of FIG. 6 showing the relationship between high pressure HP and compressor frequency f. In the region A, only the first compressor is operated, and in the region B, both the first and second compressors are operated. In such an operating region, the compressor frequency f is controlled so that the high pressure HP does not exceed the constant pressure W1.
High voltage cut regions 90 and 91 for controlling the current control and current cut regions 92 and 93 for controlling the frequency in consideration of the breaker capacity of the inverter control device and the heat generation of the power transistor are set.

The prior art relating to the capacity control operation of the first and second compressors as described above is disclosed in Japanese Patent Laid-Open Nos. 63-73056 and 63.
It is known as −73057.

(Problems to be Solved by the Invention) In the compressor unit, the first compressor is operated independently when the load demand is small, while the first compression is performed when the load demand exceeds the capacity f1 of the first compressor. The control is performed such that the compressor and the second compressor are simultaneously operated, but under certain conditions, there are cases in which a compression capacity commensurate with the required load cannot be obtained.
That is, when operating at point 96 on the load characteristic 95 in FIG. 6, for example, when a load corresponding to point 97 is required, the first compressor has a protection function by current cut, Only the operating state at the point 96 is obtained, and as a result, the state of insufficient capacity continues even though the second compressor is stopped.

Such an inconvenient phenomenon is particularly likely to occur when the first compressor is PI-controlled. That is, as shown in FIG. 4, P control (proportional control) is performed when the fluctuation of the air conditioning load is large, and I control (integral control) is performed when the fluctuation of the air conditioning load is small. When the frequency increase request Δf at time is small, the protection function by the current cut acts to suppress the frequency increase of the first compressor 1, but the second compressor is not started. This is because such a state continues for a long time.

The present invention has been made in order to solve the above-mentioned conventional drawbacks, and an object thereof is to improve the operation control system of the first compressor and the second compressor, and to appropriately cope with fluctuations in load demand. It is an object of the present invention to provide a refrigeration system capable of performing a compressor operation corresponding to.

(Means for Solving the Problem) Therefore, in the refrigeration apparatus of the present invention, an inverter-type first compressor 1 having a variable compression capacity and a second compressor 2 having a constant compression capacity are connected in parallel to each other in a refrigerant circulation circuit. And the simultaneous operation of the first compressor 1 and the simultaneous operation of the first and second compressors 1 and 2, and the change of the compression capacity of the first compressor 1 together. Is a refrigerating apparatus provided with an operation control means 25 for controlling the compression capacity of the first compressor 1 so as to respond to fluctuations in the refrigeration load.
Input current detecting means 40 for detecting the input current value to the input current value, and the reference current for detecting the input current value by the input amount detecting means 4 for defining the regulated operation range for controlling the further increase of the input current value for protection of the inverter. A determination means 42 that outputs a reference value signal 41 when the value is equal to or more than a value, a timer means 44 that outputs a time-over signal 43 when the reference value signal 41 is input for a predetermined reference time or more, and a time-over signal 43. It is characterized in that a simultaneous operation means 45 is provided for controlling the simultaneous operation of both the compressors 1 and 2 when is inputted.

(Operation) In the above configuration, first, when the refrigeration load is small,
Only the first compressor 1 is inverter-controlled by the operation control means 25. When the input current value to the first compressor 1 increases due to an increase in the refrigeration load, and is equal to or greater than a reference current value that defines a regulated operation range that regulates a further increase in the input current value to protect the inverter. The determination means 42 outputs the reference value signal. Specifically, when the input current value to the first compressor 1 reaches the current cut region 96 shown in FIG. 6, for example, the compression capacity of the first compressor 1, for example, the operating frequency is lowered and the determination is made. The reference value signal 41 is output from the means 42. Then, thereafter, when the input current value to the first compressor 1 becomes lower than the lower limit current value 98 of the regulated operation range in FIG. 6 by this processing, the output of the reference value signal 41 is stopped while the input If the current value is equal to or more than the lower limit current value 98, the output of the reference value signal 41 is continued. That is, the reference value signal 41 is output when the input current value to the first compressor 1 continues to be equal to or more than the reference current value (the lower limit current value 98) for protecting the inverter. The reference value signal 41 is input to the timer means 44, and the timer means 44 outputs the time-over signal 43 when the reference value signal 41 continues for the reference time or longer. Based on this time-over signal 43, the simultaneous operation means 44 controls the operation of both compressors 1 and 2 simultaneously.

(Examples) Next, specific examples of the refrigerating apparatus of the present invention will be described.
A detailed description will be given with reference to the drawings.

First, FIG. 2 shows a refrigerant circuit diagram of a refrigerating apparatus in one embodiment of the present invention configured as a multi-type air conditioner. In the figure, X is an outdoor unit, and this outdoor unit X is Is four indoor units A ~
D is connected.

2 connected in parallel to each other to the outdoor unit X
The compressors 1 and 2 of the stand are installed. The first compressor 1
It has an inverter 3 for controlling its rotational speed, that is, its compression capacity, and the second compressor 2 is driven at a constant rotational speed according to the commercial frequency. The pipe 4 on the discharge side and the pipe 5 on the suction side of the compressors 1 and 2 are connected to a four-way switching valve 6, and the four-way switching valve 6 further includes a first gas pipe 7 and a second gas pipe. And 8 are connected. An accumulator 9 is provided in the suction side pipe 5. The first gas pipe 7 is connected to the outdoor heat exchanger 10, the second gas pipe 8 is connected to the header 11, and a gas shutoff valve 12 is provided midway. An outdoor fan 13 is attached to the outdoor heat exchanger 10 and a liquid pipe 14 is further connected to the outdoor heat exchanger 10. The dryer pipe 15 and the first electric expansion are sequentially connected to the liquid pipe 14 from the outdoor heat exchanger 10 side. A valve 16, a liquid receiver 17, and a liquid closing valve 18 are interposed. The tip of the liquid pipe 14 has a second electric expansion valve 19
・ 19 (4 in the figure) liquid branch pipes 20
.. While branching to 20, the above header 11 has four gas branch pipes 22..22 with mufflers 21.
Are connected to these gas branch pipes 22 and the above liquid branch pipes.
An indoor heat exchanger 23 (only the indoor unit A is shown in the figure) is connected to each other in parallel with each other by connecting pipes 24. In addition, each indoor unit AD
Are constituted by the indoor heat exchanger 23 and the indoor fan 23a, respectively.

In the heating operation in the air conditioner having the above-described configuration, the four-way switching valve 6 is positioned at the switching position indicated by the solid line in the figure, and the refrigerant discharged from the compressors 1 and 2 is transferred to the four-way switching valve 6 and the second gas pipe 8 respectively. To be condensed in each indoor heat exchanger 23, and then the liquid pipe 14
After being vaporized in the outdoor heat exchanger 10 via the first gas pipe 7, the first gas pipe 7 and the four-way switching valve 6 are returned to the compressor 1. In this case, first control the degree of superheat of the evaporating refrigerant.
The electric expansion valve 16 controls the second electric expansion valve 19, and the second electric expansion valve 19 controls the amount of refrigerant distributed to the indoor heat exchangers 23.

On the other hand, in the cooling operation, the four-way switching valve 6 is switched to the switching position shown by the solid line in the figure, and the refrigerant discharged from the compressors 1 and 2 is circulated from the outdoor heat exchanger 10 side to each indoor heat exchanger 23. Done by. At this time, the first electric expansion valve 16 is fully opened,
Each second electric expansion valve 19 controls the degree of superheat of the refrigerant.

Next, the operation control circuit of the air conditioner will be described with reference to FIG. As shown in the figure, the outdoor unit X has an outdoor control device (operation control means) 25. The outdoor control device 25 is connected to the inverter 3 and the drive motor 52 of the second compressor 2, and the inverter 3 is a drive motor 51 of the compressor 1.
It is connected to the. The outdoor control device 25 includes a total temperature difference detection circuit 31, a ΔT value detection circuit 35, and a frequency control circuit 37.
Also, a storage unit 38 is provided. On the other hand, indoor unit A ~
Although each D has an indoor control device 27 (only one indoor unit A is shown in the figure, the same applies hereinafter), a remote controller 28 and an indoor thermostat 29 are connected to this indoor control device 27, respectively. . The remote controller 28 is the indoor unit A
It has an operation switch for performing the operations of to D and a temperature setting unit for setting a desired temperature.

Further, the outdoor control device 25 includes an input amount detection means 40, a determination means 42, a timer means 44, and a simultaneous operation means 45. First, the input amount detecting means 40 has a function of detecting the input current value to the inverter 3 as an input amount. Then, the determination means 42 determines that the detected amount of the input amount detection means 40 defines the regulated operation range by the inverter protection function, that is, the current cut (drooping region) 98 and the lower limit setting characteristic (no change region) 80 of FIG.
It is configured to output the reference value signal 41 when it is within the range L between and. The reference value is not limited to the range L, and the reference value signal 41 may be output when the input current value corresponding to the point 96 in FIG. 6 is reached.
Further, the timer means 44 outputs the time-over signal 43 when the reference value signal 41 is input for a predetermined reference time or longer, and the simultaneous operation means 45 outputs the time-out signal 43 when both the compressors 1 are input. 2 has a function of controlling the frequency control circuit 37 so as to operate the two simultaneously.

Next, the outline of the frequency control of the inverter 3 will be described.
The inverter frequency is controlled by the total temperature difference detection circuit 32 to the frequency control circuit 37 while the initial setting frequency stored in the storage unit 38 is set. Specifically, this frequency control is proportional control (hereinafter referred to as P control).
And integral control (hereinafter referred to as I control). The operating state of the air conditioner by the P control and the I control will be described with reference to FIG. 4 with time. First, the air conditioner is operated to gradually increase the room temperature and the air conditioning load (absolute value of ΣΔT). In the case where the fluctuation occurs, the P control is repeatedly performed every predetermined time (30 seconds) (fourth
Figure, period T1).

Then, in a steady operation state where the room temperature hardly changes, the I control is performed every predetermined time (3 minutes). As shown in the figure, the inverter frequency gradually increases by Δf (FIG. 4, period T2).

Then, when the detected load changes again, P control is performed again, and the inverter frequency increases and decreases every predetermined time (30 seconds) (FIG. 4, period T3).

Next, the functions of the input amount detection means 40 to the simultaneous operation means 45 will be described with reference to FIG. 5. First, when the air conditioning load is small,
Only the first compressor 1 is controlled by the operation control means 25 by the P control and I
Control (step S1). Next, in step S2, the input amount detection means 40 detects the input current value to the inverter 3, and in step S3 the determination means 42 determines the input current value. When the input current value corresponding to point 96 in FIG. 6 which is the upper limit set value is reached in this step S3 (NO), the judging means 42 outputs the reference value signal 41 to the timer means 44, while If the input current value equivalent to 96 is not reached (YES), go to step S
Return to 1. The reference value signal 41 is input to the timer means 44, at which time the operating frequency of the first compressor 1 reaches a predetermined frequency determined by the input current control (step S4).
In step S5, the time counting by the timer means 44 is started. Then, in the next step S6, the determination means 42 determines whether or not the input current value is equal to or lower than the lower limit set value corresponding to point 98 in FIG. 6, and when the lower limit current set value is exceeded (N
If the answer is YES, the process returns to step S1. In step S7, when the timer means 44 continues the reference value signal 41 for the reference time or more (YE
S), go to the next step S8 and set the time over signal 43
Is output, and when the reference time has not been reached (NO), the process returns to step S4. Then, in step S8, the simultaneous operation means 45
On the basis of the time-over signal 43, the first and second compressors 1 and 2 are simultaneously operated and controlled in a state commensurate with the load. Therefore, after the air conditioning load reaches the point 96 in the single operation of the first compressor 1 and then the air conditioning load gradually increases, the first and second compressors 1 and 2 are simultaneously operated after a certain period of time. Therefore, it is possible to appropriately cope with an increase in the air conditioning load. Particularly when the increase request frequency Δf is small as in the P control or I control described above, the load request is included in the protection area S in FIG. 6, and that state is often maintained for a long time. However, according to the above, such a drawback can be solved.

Although the specific embodiments of the refrigerating apparatus of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be carried out within the scope of the present invention. For example, in the above-described embodiment, the heating operation is described, but the same operation can be performed during the cooling operation, and the air conditioners other than the multi-air conditioner can also be executed similarly.

(Effects of the Invention) As described above, in the refrigeration apparatus of the present invention, even if the refrigeration load gradually increases during the protective function of the inverter, for example, the regulated operation by the current cut, after the fixed time, the first and second compressions are performed. Since the machines can be operated at the same time, it is possible to appropriately cope with an increase in refrigeration load.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of the present invention, FIG. 2 is a refrigerant circuit diagram showing a refrigerant circuit in an embodiment of the present invention, FIG. 3 is a block diagram of a control mechanism, and FIG. FIG. 5 is a flow chart of the operation control method, and FIG. 6 is a graph showing changes in compressor output with respect to operating frequency. 1 ... First compressor, 2 ... Second compressor, 3 ... Inverter, 25 ... Outdoor control device (operation control means), 40 ... Input amount detection means, 42 ... Determination means, 44 ... Timer means, 45 ...
… Simultaneous driving means.

Claims (1)

[Claims] 1. A refrigerant circulation circuit is provided with an inverter-type first compressor (1) having a variable compression capacity and a second compressor (2) having a constant compression capacity, which are connected in parallel to each other and are interposed. By switching the single operation of the first compressor (1) and the simultaneous operation of the first and second compressors (1) and (2) and changing the compression capacity of the first compressor (1), Operation control means (25) for controlling the compression capacity to respond to fluctuations in the refrigeration load
A refrigeration system provided with the operation control means (2
5) Input amount detecting means (40) for detecting the input current value to the first compressor (1), and input amount detecting means (4).
And a determination means (42) for outputting a reference value signal (41) when the detected current value at is greater than or equal to a reference current value that defines a regulated operation range that regulates a further increase in the input current value for protection of the inverter. , A timer means (44) for outputting a time-over signal (43) when the reference value signal (41) is input for a predetermined reference time or longer, and a time-over signal (4).
A refrigerating apparatus comprising: a simultaneous operation means (45) for controlling the simultaneous operation of both the compressors (1) and (2) when 3) is input.