JPH03274358A - Refrigerating machine - Google Patents

Abstract

PURPOSE:To operate compressors adequately corresponding to fluctuation in the load demand by a method wherein a time-over signal is outputted when a reference value signal, which is outputted when a detected value reaches the reference value, is outputted for a reference time period or longer, and both compressors are simultaneously brought in operation and controlled. CONSTITUTION:When the refrigerating load is small, only a first compressor 1 is inverter-controlled by an operating controller 25. When the input amount to the first compressor 1 increases with an increase in the refrigerating load and reaches a reference value which specifies the restricted operation range by an inverter protection function, for example, when it reaches an electric current cut-off zone, a judgement device 42 outputs a reference value signal 41. When the reference value signal 41 is input to a timer 44 and the input lasts for a reference time period of longer, the timer 44 outputs a time-over signal 43. A simultaneous operation device 45 brings both compressors 1 and 2 into simultaneous operation in response to the time-over signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a refrigeration system equipped with a compressor with variable compression capacity and a compressor with constant compression capacity.

(Prior Art) As a conventional example of the above-mentioned refrigeration apparatus, there can be mentioned, for example, the apparatus described in Japanese Patent Application Laid-Open No. 58-221349. In this device, a compressor unit is configured by connecting in parallel a first compressor with a variable rotation speed controlled by an inverter and a second compressor with a constant rotation speed,
A condenser, an expansion valve, and an evaporator are sequentially connected to this to form an air conditioner.

In the above device, only the first compressor is operated in a range where the air conditioning load is small, but when a large air conditioning load is generated that requires a compression capacity exceeding the maximum value of the compression capacity variable width of the first compressor, the first compressor is operated. Switch to simultaneous operation of the first and second compressors. By using such switching control together with the compression capacity control of the first compressor, the variable range of the compression capacity of the first compressor can be made relatively small. Therefore, even if a small-capacity inverter control device is installed at the bottom of the tank, it is possible to control a load that has a large fluctuation range, compared to when a single compressor equipped with a large-capacity inverter control device is installed at the bottom of the tank. Therefore, there is an advantage that the manufacturing cost of the compressor unit can be reduced.

Further, the operation control of the first and second compressors will be explained with reference to the drawings of the embodiments of the present invention. In region A, only the first compressor is operated, and in region B, both the first and second compressors are operated. In such an operating region, there is a high pressure cut region 90.91 in which the compressor frequency f is controlled so that the high pressure HP does not exceed a constant pressure of 1, and the breaker capacity of the inverter control device and the heat generation of the power transistor are taken into consideration. SIN area 92
．． 93 are set respectively.

Incidentally, prior art related to the capacity control operation of the first and second compressors as described above is known from Japanese Patent Laid-Open Nos. 63-73056 and 63-73057.

(Problem to be solved by the invention!!) In the above compressor unit, when the load request is small, the first compressor operates independently, but when the load request exceeds the capacity f1 of the first compressor, the first compressor operates independently. Control is performed so that the first compressor and the second compressor operate simultaneously, but under certain conditions, it may not be possible to obtain enough compression capacity to meet the required load. .

That is, when operating at point 96 on the load characteristic 95 in FIG. 6, for example, if a load corresponding to point 97 is required, a protection function by current cut is applied to the first compressor, Only the operating state at point 96 can be obtained,
As a result, a 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 under PI control. In other words, as shown in Fig. 4, when the fluctuation of air conditioning load is large, P control (
(proportional control) is carried out, and when the fluctuation of the air conditioning load is small, ■ control (integral side control) is carried out. However, when the frequency increase request Δf during these PI controls is small, the protection function by current cut is performed. This is because, although the frequency increase of the first compressor 1 is suppressed, the second compressor is not activated, and this state continues for a long time.

This invention has been made in order to solve the above-mentioned conventional drawbacks, and its purpose is to improve the operation control method of the first compressor and the second compressor, and to provide appropriate An object of the present invention is to provide a refrigeration system capable of operating a compressor corresponding to the above.

(Means for Solving the Problems) Therefore, in the refrigeration system of the present invention, an inverter-type first compressor 1 with a variable compression capacity and a second compressor 2 with a constant compression capacity are connected in parallel to each other in a refrigerant circulation circuit. At the same time, the first compressor 1 is operated independently and the first and second compressors 1
．． 2 and changing the compression capacity of the first compressor 1 to control the overall compression capacity in response to refrigeration load fluctuations. The operation control means 25 includes an input amount detection means 40 for detecting the input amount to the compressor 1, and a detection value of the input amount detection means 4 that reaches a reference value that defines a regulated operation range by the inverter protection function. When the reference value signal 41
a timer means 44 that outputs a time-over signal 43 when the reference value signal 41 is manually inputted for a predetermined reference time or more; The present invention is characterized in that it is provided with a simultaneous operation means 45 for controlling the simultaneous operation of 1.2 and 2.

(Function) At the bottom of the tank, first, when the refrigeration load is small, only the first compressor 1 is inverter-controlled by the operation control means 25. Eventually, when the amount of input to the first compressor 1 increases due to an increase in the refrigeration load and reaches a reference value that defines the regulated operation range by the inverter protection function, for example, the current cut fJ range 96, the determination means 42 determines the reference value. A signal 41 is output. This reference value signal 41 is input to a timer means 44, and the timer means 44 outputs a time-over signal 43 when the reference value signal 41 continues for a reference time or longer. Based on this time-over signal 43, the simultaneous operation means 44 controls the simultaneous operation of both regular compressors 1.2.

(Example) Next, a specific example of the refrigeration apparatus of the present invention will be described in detail with reference to the drawings.

First, Figure 2 shows ms as a multi-type air conditioner.
This figure shows a refrigerant circuit diagram of a refrigeration system according to an embodiment of the present invention, in which X is an outdoor unit, and this outdoor unit X includes four indoor units) A-D.
is connected.

The outdoor unit) X is equipped with two compressors 1.2 connected in parallel to each other. The first compressor 1 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 discharge side piping 4 and the suction side piping 5 of these compressors 1.2 are each connected to a four-way switching valve 6, and the four-way switching valve 6 is further connected to a first gas pipe 7 and a second gas pipe. 8 is connected. Note that an accumulator 9 is interposed in the suction side pipe 5. The first gas pipe 7 is connected to an outdoor heat exchanger 10, and the second gas pipe 8 is connected to a header 11, with a gas shutoff valve 12 interposed therebetween.

An outdoor fan 13 is attached to the outdoor heat exchanger 10, and a liquid pipe 14 is also connected to the liquid pipe 14.
In order from the outdoor heat exchanger 10 side, a dryer filter 15, a first electric expansion valve 16, a liquid receiver 17, and a liquid closing valve 1 are installed.
8 is interposed. The tip of the liquid pipe 14 is connected to a plurality of second electric expansion valves 19...19, respectively.
In the case of the figure, it is branched into four liquid branch pipes 20...20, while the header 11 has mufflers 21...
21 are connected, and an indoor heat exchanger 23 (only the indoor unit A is shown) is connected between these gas branch pipes 22 and each of the liquid branch pipes 20. are connected in parallel to each other by connecting pipes 24, . . . 24, respectively. In addition, each indoor unit A-D
are the indoor heat exchanger 23 and the indoor fan 23a, respectively.
It is composed of.

For heating operation in the air conditioner having the above configuration, the four-way switching valve 6 is located at the switching position shown by the solid line in the figure, and the compressor 1.
The refrigerant discharged from 2 is passed through the four-way switching valve 6 and the second gas pipe 8 to be condensed in each indoor heat exchanger 23, and then to the liquid pipe 14.
After evaporating in the outdoor heat exchanger 10 through
This is done by returning the flow from the gas pipe 7 and the four-way switching valve 6 to the compressor 1. In this case, the degree of superheating of the evaporative refrigerant is controlled by the first electric expansion valve 16, and each twenty-first dynamic expansion valve 19 controls the amount of refrigerant distributed to each indoor heat exchanger 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, number one! The dynamic expansion valve 16 is fully opened, and each second electric expansion valve 19 controls the degree of superheating of the refrigerant.

Next, the operation control circuit of the air conditioner will be explained based on FIG. 3. As shown in the figure, the outdoor unit χ has an outdoor control device (operation control means) 25, and this outdoor control device 25 has an inverter 3 and a drive motor 52 for the second compressor 2.
The inverter 3 is connected to the drive motor 51 of the compressor l. Note that this outdoor control device 25 is provided with a total temperature difference detection circuit 31, a ΔTri detection circuit 36, a frequency control circuit 37, and a storage section 38.

On the other hand, the indoor units A to D each have an indoor control device 27.
(Only one indoor unit A is shown, hereinafter); however, this indoor control device 27 includes a remote controller 2.
8. Indoor thermostats 29 are connected respectively. The remote controller 28 has an operation switch for operating the indoor units A to D, and a temperature setting section for setting a desired temperature.

Further, the outdoor control device 25 includes an input amount detection means 40,
Judgment means 42, timer means 44, and simultaneous operation means 45
It is equipped with First, the input amount detection means 40 has a function of detecting the input current value to the inverter 3 as an input amount. The determining means 42 determines that the detected value of the input amount detecting means 40 is between the current cut (dripping region) 92 and the lower limit setting characteristic (no change region) 80 in FIG. It is configured to output a reference value signal 41 when the value is within the range of . Note that the reference value is not limited to the above range, and the reference value signal 41 may be output when the input current value corresponding to point 96 in FIG. 6 is reached.

Further, the timer means 44 generates a time-over signal 4 when the reference value signal 41 is input for a predetermined reference time or more.
3, and the simultaneous operation means 45 outputs a time over signal 4.
It functions to control the frequency 117m times 1B57 so that both the compressors 1.2 are operated simultaneously when the compressor 3 is manually operated.

Next, an outline of frequency control of the inverter 3 will be described. In a state where the initial setting frequency stored in the storage section 38 is set, the inverter frequency is controlled by the total temperature difference detection circuit 32 to the frequency control circuit 37. Specifically, this frequency control is divided into proportional control W (hereinafter referred to as P@comb) and integral control (hereinafter referred to as ■ control). The operational status of the air conditioner under the above-mentioned P control and (2) control will be explained over time using FIG.
If the absolute value of ΣΔT) fluctuates, the P@ control described above is repeated at predetermined intervals (30 seconds).
Figure, period TI).

Then, when the room temperature reaches a steady operating state where there is almost no change, the above-mentioned I control is performed every predetermined time (3 minutes). As shown in the figure, the inverter frequency gradually increases by Δτ (4th
Figure, period T2).

Then, when the detected load changes again, the P control is performed again, and the inverter frequency increases or 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 explained with reference to FIG. 5. First, when the air conditioning load is small, the operation control means 25 performs the P control and I control on only the first compressor 1. (Step S1). Then step S2
The input amount detection means 40 detects the input current value to the inverter 3, and the determination means 42 determines the input current value in step S3. In this step S3, the sixth value, which is the upper limit setting value, is
When the input current value corresponding to point 96 in the diagram is reached (No)
In this case, the determination means 42 outputs the reference value signal 41 to the timer means 44.
On the other hand, if the input current value corresponding to point 96 is not reached (YES), the process returns to step Sl.

The reference value signal 41 is inputted to the timer means 44, and in order to reach the operating frequency of the first compressor 1 to a predetermined frequency determined by the input current control at step S4), the timer means 44 starts measuring time in step S5. Start. Then, in the next step S6, the determining means 42 determines whether or not the input current value is less than or equal to the input current value corresponding to point 98 in FIG. 6, which is the lower limit setting value, and if it exceeds the lower limit current setting value (NO) If so, proceed to the next step S7, otherwise Y
When the result is ES, the process returns to step S1. In the above step s7, when the reference value signal 41 continues for more than the reference time (YES), the timer means 44 proceeds to the next step S8 and outputs the time over signal 43, and when the reference value signal 41 does not reach the reference time (NO) , return to step S4 above. Then, in step S8, the simultaneous operation means 45 controls the simultaneous operation of both the first and second compressors 1.2 in a state appropriate to the load based on the time-over signal 43. Therefore, if the air conditioning load gradually increases after reaching the above-mentioned point 96 when the first compressor 1 is operating independently, the first and second compressors 1.2 will be operated simultaneously after a certain period of time. Therefore, it becomes possible to appropriately respond to an increase in air conditioning load. In particular, when the increase request frequency Δf is small as in the above-mentioned P control or I control, the load request is included in the protection eJ[1s in FIG. 6, and this state is often maintained for a long time. Although it is easy to encounter a situation in which requests cannot be appropriately met, the above disadvantages can be overcome.

Although specific embodiments of the refrigeration system of the present invention have been described above, the present invention is not limited to the above embodiments, and can be implemented with various modifications within the scope of the present invention. For example, in the above-mentioned embodiment, the explanation was given regarding the heating operation, but it can be implemented in substantially the same way during the cooling operation, and furthermore, it can be implemented in the same way in air conditioners other than multi-air conditioners.

(Effects of the Invention) As described above, in the refrigeration system of the present invention, even if the refrigeration load gradually increases during regulated operation using the inverter's protection function, for example, current cant, the first and second cars Since it becomes possible to operate the compressors simultaneously, it becomes possible to appropriately respond to an increase in refrigeration load.

[Brief explanation 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 invention, Fig. 3 is a block diagram of the control mechanism, and Fig. 4 is the operating state time. FIG. 5 is a flowchart 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... Judgment means, 44
...Timer means, 45... Simultaneous operation means.

Claims (1)

[Claims] 1. A first compressor (1) of an inverter type with a variable compression capacity and a second compressor (2) with a constant compression capacity are connected in parallel to each other in the refrigerant circulation circuit, and the above-mentioned first compression The overall compression capacity is increased by switching between independent operation of the compressor (1) and simultaneous operation of the first and second compressors (1) and (2), and changing the compression capacity of the first compressor (1). A refrigeration system comprising an operation control means (25) for controlling in response to refrigeration load fluctuations, the operation control means (25) having an input amount detection device for detecting an input amount to the compressor (1). Means (40)
and determining means (42) for outputting a reference value signal (41) when the detected value of the input amount detection means (4) reaches a reference value that defines the regulated operation range by the inverter protection function; timer means (44) for outputting a time-over signal (43) when the signal (41) is input for a predetermined reference time or longer; and both compressors (1) when the time-over signal (43) is input. (2) Simultaneous operation means (45) for controlling simultaneous operation.