JPH03134436A - Operation control device in freezer device - Google Patents

Abstract

PURPOSE:To extend an operable range of a compressor by forcedly interrupting control of opening control means once high pressure side pressure of a refrigerant circuit exceeds a predetermined value and increasing the opening of a motor driven expansion valve beyond present opening. CONSTITUTION:Detected by high pressure excess rise detector means Ps the time high pressure side pressure exceeds a predetermined value, opening alteration means 52, as receiving an output signal from said means, forcedly interrupts control of opening control means 51 for a predetermined time and alter opening of a motor driven expansion vale 5(7) such that it more increases than upon ordinary excess heating control. Accordingly, a compressor 1 is prevented from being abnormally interrupted owing to temperature rise of the high pressure side pressure. Hereby, an operable range of the compressor can be extended.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an operation control device for a refrigeration system that controls the opening degree of an electric expansion valve based on the degree of superheat, and particularly relates to an operation control device for a refrigeration system that controls the opening degree of an electric expansion valve based on the degree of superheat. Regarding measures to expand the

(Prior Art) Conventionally, as disclosed in, for example, Japanese Unexamined Patent Publication No. 63-73059, a refrigeration system equipped with a refrigerant circuit in which a compressor, a condenser, an electric expansion valve, and an evaporator are sequentially connected,
A known technique attempts to maintain the refrigerating capacity corresponding to the air conditioning load by performing so-called superheat degree control in which the opening degree of an electric expansion valve is adjusted so that the suction superheat degree matches a target value.

(Problem to be Solved by the Invention) However, during heating operation when the above-mentioned refrigeration system is used as an air conditioner, the electric expansion valve on the indoor side is normally fully open, and the refrigerant is in a state where it is easy to flow. However, because the degree of superheating is controlled on the electric expansion valve on the outdoor side, which serves as a pressure reducing valve, the opening degree of the outdoor electric expansion valve is restricted, and the pressure in the liquid line in front of it is high. During overload operation, while controlling the degree of superheating of the outdoor electric expansion valve, if the pressure on the high pressure side rises due to a rise in indoor or outdoor temperature, there will be almost no liquid refrigerant in the suction pipe. If left as is, the high-pressure side pressure may temporarily rise, leading to an abnormal stop of the compressor.

The present invention has been made in view of the above, and its purpose is to prevent the high pressure from increasing when the high pressure side pressure increases due to overload etc. while controlling the degree of superheating of the electric expansion valve as described above. The purpose is to effectively prevent abnormal stoppage of the compressor by providing a means for releasing the compressor to the low pressure side, thereby expanding the operable range of the compressor.

(Means for Solving the Problem) In order to achieve the above object, the solution of the present invention is to forcibly reduce the opening of the electric expansion valve, which serves as a pressure reducing valve, when the pressure on the high pressure side rises excessively, before causing a high pressure cut. The aim is to increase the

Specifically, as shown in Fig. 1, a compressor (1), a condenser (8 or 4), and an electric expansion valve (5 or 7) serving as a pressure reducing valve are used.
and an evaporator (4 or 8) connected in sequence (
11) is assumed.

As an operation control device for the refrigeration system, a suction superheat degree detection means (50) for detecting the degree of superheat of the suction refrigerant, and an output of the suction superheat degree detection means (50) are received, and the electric expansion is performed based on the suction superheat degree. Opening degree control means (51) for controlling the opening degree of the valve (5 or 7) shall be provided.

Furthermore, high pressure overrise detection means (Ps
) and the output signal of the high pressure overrise detection means (Ps), the opening control means (51) is activated for a certain period of time.
) is configured to forcibly stop the control of the electric expansion valve (5 or 7) to change the opening degree of the electric expansion valve (5 or 7) to be greater than the current opening degree. .

(Function) With the above configuration, in the present invention, during normal operation, the opening control means (51) opens the electric expansion valve (5 or 7) based on the degree of superheat detected by the degree of superheat detection means (50). The air conditioning temperature is controlled to ensure capacity according to the air conditioning load.

In that case, the pressure is high just before the electric expansion valve (5 or 7), but the opening degree of the electric expansion valve (5 or 7) is adjusted based on the degree of superheat, so for example during overload operation during heating operation. etc., the opening degree is restricted, and if the high-pressure side pressure increases due to a rise in air temperature indoors or outdoors, the high-pressure side pressure will temporarily rise excessively and the high pressure will be cut. This may cause the compressor (1) to stop abnormally.

However, in the present invention, when the high pressure overrise detection means (PS) detects that the high pressure side pressure has increased to a predetermined value or more, in response to the output signal, the opening degree changing means (52) adjusts the pressure for a certain period of time. During this period, the control of the opening degree control means (51) is forcibly stopped, and the opening degree of the electric expansion valve (5 or 7) is changed to be greater than that during normal superheat degree control.
The high pressure will escape to the low pressure side, and abnormal stoppage of the compressor (1) due to a temporary increase in the pressure on the high pressure side will be prevented.

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

FIG. 2 shows a refrigerant piping system of an air conditioner according to an embodiment of the present invention, in which two indoor units (A) and (B) are connected in parallel to one outdoor unit (X). It is multi-type.

In the above outdoor unit (X), (1) is a compressor, (
2) is a demister that collects the oil in the discharged refrigerant, (3) is a four-way switching valve that switches as shown in the solid line in the figure during cooling operation, and as shown in the broken line in the figure during heating operation, and (4) is a four-way switching valve that switches as shown in the broken line in the figure during heating operation. an outdoor heat exchanger (4) equipped with an outdoor fan (12) consisting of outdoor fans (12a) and (12b), which functions as a condenser during cooling operation and as an evaporator during heating operation;
a) is an auxiliary heat exchanger for the outdoor heat exchanger (4), (5) is an outdoor electric expansion valve that adjusts the refrigerant flow rate during cooling operation and reduces the pressure of the refrigerant during heating operation, and (9) is an auxiliary heat exchanger for the outdoor heat exchanger (4). This is an accumulator for removing liquid refrigerant.

Furthermore, the indoor units (A) and (B) have the same configuration, and both include an indoor electric expansion valve (7) that reduces the pressure of the refrigerant during cooling operation and adjusts the refrigerant flow rate during heating operation; The main equipment includes an indoor fan (13) and an indoor heat exchanger (8) which functions as an evaporator during cooling operation and as a condenser during heating operation.

Each of the above devices (1) to (9) is connected to a refrigerant pipe (10).
A main refrigerant circuit (11) is configured, which is connected to allow the flow of refrigerant and transfers heat (or cold heat) obtained through heat exchange with outdoor air and imparts it to indoor air.

Although not shown, the compressor (1) includes a scroll mechanism that discharges the sucked refrigerant at high pressure by the relative revolution of two opposing scrolls, and a fixed scroll in the middle of the scroll mechanism. It has a built-in unloader mechanism with a bypass hole that bypasses a portion of the discharged refrigerant.

A capillary tube (16) is connected from the discharge pipe (10a) to the back pressure side of the unloader piston of the unloader mechanism.
), and an unloader passage (17) that connects the middle of the high pressure supply passage (15) and the suction pipe (10b) via an on-off valve (18).
When the on-off valve (18) is closed, high pressure is supplied to the unloader mechanism to bring the operating capacity of the compressor (1) to 100% full load.
8) is opened, low pressure is supplied to the unloader mechanism so that the operating capacity of the compressor (1) becomes unloaded, which is 50% of the full load.

Furthermore, the device is equipped with many sensors (
T hd) is a discharge pipe sensor arranged in the discharge pipe (10a) and detects the discharge pipe temperature, and (T hs) is a discharge pipe sensor arranged in the discharge pipe (10a).
b) a suction pipe sensor for detecting the suction pipe temperature;
(T hl) is an outside temperature sensor placed at the air intake port of the outdoor heat exchanger (4) and detects the outside air temperature; (T h2)
is an outdoor liquid pipe sensor that is arranged on the liquid pipe side of the outdoor heat exchanger (4) and detects the liquid pipe temperature of the outdoor heat exchanger (4), which is detected by the suction pipe sensor (T hd). Temperature deviation (T
The suction superheat degree sh is determined from the suction superheat degree sh (s-T2), and the suction superheat degree detection means (5) detects the suction superheat degree sh using the outdoor liquid pipe sensor (Thd) and the suction pipe sensor (Th2).
0) is configured.

Next, (T h3) is a room temperature thermometer that is placed at the air inlet of the indoor heat exchanger (8) and detects the indoor air temperature;
h4) is an indoor liquid pipe sensor that is arranged in the liquid pipe of the indoor heat exchanger (8) and detects the liquid pipe temperature of the indoor heat exchanger (8);
(T h5) is an indoor gas pipe sensor that is placed on the gas pipe of the indoor heat exchanger (8) and detects the gas pipe temperature of the indoor heat exchanger (8), and (Hps) is placed on the discharge pipe (10a). ,
A high pressure switch (L ps) is placed in the suction pipe (10b) to stop the compressor (1) when the high pressure side pressure rises excessively, and when the low pressure side pressure drops too much, the high pressure switch (L ps) stops the compressor (1).
A low-pressure switch (Ps) for stopping the operation is arranged in the discharge pipe (10a), and when the discharge pressure reaches a predetermined pressure value (for example, a value of about 24 kg/cIi!), it changes from the on state to the off state. This control pressure switch serves as a high pressure overrise detection means for detecting when the high pressure side pressure has increased excessively. Each of the above-mentioned sensors is signal-connected to a controller (not shown) that controls the operation of the device, and the operation of the air conditioner is controlled according to the signals from each sensor.

In the figure, (19) indicates the demister (2) and the compressor (
The oil return pipe (21) is connected between the suction pipe (10b) of 1) via a capillary (20) to return the oil, and (21) is connected between the liquid pipe (10c) and the suction pipe (10b). An injection bypass path connected to allow liquid refrigerant to bypass, and the injection bypass path (21) includes an injection on-off valve (22) and a capillary tube (
23) are interposed in order from the liquid pipe (10c) side,
At the start of cooling operation under low outside temperature conditions, when the low pressure drops excessively, the injection bypass passage (21) is opened to bypass the liquid refrigerant to the suction pipe (10b), so that the low pressure switch (L ps) is activated. It is designed to prevent it from operating. Also, (24), (24)
is a closing valve interposed in the connecting pipe between the outdoor unit (A) and the indoor side.

During heating operation of the air conditioner, the refrigerant discharged from the compressor (1) is divided into each indoor unit (A), (B), condensed in each indoor heat exchanger (8), (8), and then merged. It then returns to the outdoor unit (X), is depressurized by the outdoor electric expansion valve (5), is evaporated in the outdoor heat exchanger (5), and then circulates back to the compressor (1). In that case, each indoor unit (A).

The air conditioning status in each room is adjusted to 3 depending on the value of the temperature difference ΔT between the room temperature and the set temperature detected by the room temperature thermometer (T h3) in (B).
Each indoor unit (A), (B
) The operating capacity of the compressor (1) is controlled to three states: full load, unload, or stop, depending on the combination of air conditioning zones.

Here, the control contents of the controller during the heating operation will be explained based on the flowchart of FIG. 3 and the time chart of FIG. 4. However, Fig. 4(a)~
The time chart in (C) shows the control pressure switch (Ps
), the opening degree of the indoor electric expansion valve (7), and the change in the opening degree of the outdoor electric expansion valve (5) over time, respectively.

First, in step S1, it is determined whether or not the device is in operation, and if it is not in operation, the process moves to step S2 and the outdoor electric expansion valve (5) is closed. On the other hand, if the operation is in progress, the process proceeds to step S3, where it is determined whether the pressure switch (Ps) is in the on state or not.
In other words, it is determined whether the pressure on the high pressure side has increased excessively, and if the pressure switch (Ps) is on and the pressure on the high pressure side has not increased excessively, the process proceeds to step S4 and the outdoor electric expansion valve (
5) is adjusted by controlling the degree of superheating (see Fig. 4(c)).
) until time t1). In addition, since heating operation is in progress, each indoor electric expansion valve (7), (7) is fully open (200°C).
0 pulse).

On the other hand, when the pressure switch (Ps) is off and the pressure on the high pressure side has increased excessively (time t1 in Fig. 4(a)), the process proceeds to step S5, and the set time tQ (for example, about 5 minutes) is reached. If a timer (not shown) is set, the timer remains as is; if the timer is not set, the timer is set in step S6, and then the process is performed in step S7.
, and until the timer counts up, the process proceeds to step S8, where the outdoor electric expansion valve (5) is fully opened (2).
000 Hull:z,) J:tRuyo*ltRuUT4Figure(
C) time 1+). Thereafter, when the timer counts up in the determination in step S7, the timer counts up in step S4.
Then, the opening degree of the outdoor electric expansion valve (5) is adjusted by controlling the degree of superheating (after time t2 in FIG. 4(c)).

In the above flow, step S4 configures the opening degree control means (51) that controls the opening degree A of the outdoor electric expansion valve (5) based on the suction superheat degree sh, and step S8 configures the pressure switch (high pressure overrise). When receiving the signal from the detection means (Ps), the opening control means (5) is activated for a certain period of time.
1) is forcibly stopped and the outdoor electric expansion valve (5
) is configured with opening degree changing means (52) for changing the opening degree of the opening to be more open than the current opening degree.

Therefore, in the present invention, during normal operation, the opening control means (
51), the opening degree of the electric expansion valve (5 or 7) is controlled based on the degree of superheat sh detected by the degree of superheat detection means (50), and the capacity according to the air conditioning load is ensured.

In that case, the pressure is high immediately before the electric expansion valve (5 or 7), and the opening degree of the electric expansion valve (5 or 7) is adjusted based on the degree of superheat sh, so for example, during overload operation during heating operation etc., when the high-pressure side pressure increases due to an increase in air temperature indoors or outdoors, the high-pressure side pressure temporarily rises too much, and the compressor (1) is cut off due to high pressure.
There is a risk of abnormal stoppage.

However, in the present invention, when the pressure switch (high pressure overrise detection means) (Ps) detects that the high pressure side pressure has increased to a predetermined value or more, the opening degree changing means (
52), the opening control means (51) is controlled for a certain period of time.
) is forcibly stopped, and the electric expansion valve (5 or 7)
Since the opening degree of is controlled to be greater than that during normal superheat degree control, high pressure will escape to the low pressure side, making it possible for the compressor (1) to stop abnormally due to a temporary excessive rise in the pressure on the high pressure side. This can be effectively prevented.

In addition, in the above embodiment, the outdoor electric expansion valve (5) is fully opened when the high pressure rises excessively, but it is not necessarily necessary to fully open it, and the opening value may be increased to some extent than the opening value by superheat degree control. This will allow high pressure to escape to the low pressure side.

Further, in the above embodiment, the receiver is not arranged in the refrigerant circuit (11), but the present invention is not necessarily limited to such an embodiment, and even if the receiver is arranged, the high pressure side of the refrigerant can be Escape to the side is guaranteed to some extent. However, when the receiver is removed, the refrigerant flows more smoothly from the high pressure side to the low pressure side.
When the electric expansion valve (5 or 7) is opened, escape of high pressure to the low pressure side is promoted. In that case, even if the receiver is not arranged, the accumulator (9) will ensure the storage function of the liquid refrigerant to some extent, so the refrigerant circulation will not be hindered, and therefore, the present invention will be highly effective. Can be done.

(Effects of the Invention) As explained above, according to the present invention, in a refrigeration system, during normal operation, the opening degree of the electric expansion valve serving as the pressure reducing valve of the evaporator is controlled based on the value of the suction superheat degree. When the high-pressure side pressure rises above a predetermined value, the opening degree of the electric expansion valve is increased more than the opening degree by superheat degree control, so the high pressure escapes to the low-pressure side and prevents the high-pressure side pressure from rising excessively. It is possible to avoid abnormal stoppage of the compressor caused by
Reliability can be improved. Moreover, thereby, the operable range of the compressor can be expanded.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention. Figure 2 and the following diagrams show embodiments of the present invention. Figure 2 is a refrigerant piping system diagram of an air conditioner, Figure 3 is a flow chart showing the control details of the controller, and Figures 4 (a) to (c) are FIG. 3 is a time chart diagram showing temporal changes in the opening degree of the pressure switch, the indoor electric expansion valve, and the outdoor electric expansion valve, respectively. 1 Compressor 4 Outdoor heat exchanger (evaporator or condenser) 5 Outdoor electric expansion valve 7 Indoor electric expansion valve 8 Indoor heat exchanger (condenser or evaporator) 11 Refrigerant circuit 50 Suction superheat degree detection means 51 Opening degree control Means 52 Opening degree changing means Ps Pressure switch (high pressure overrise detection means) Fig. 4 Time

Claims (1)

[Claims] (1) Equipped with a refrigerant circuit (11) in which a compressor (1), a condenser (8 or 4), an electric expansion valve (5 or 7) serving as a pressure reducing valve, and an evaporator (4 or 8) are connected in sequence. In the refrigeration system, a suction superheat degree detection means (50
), and an opening control means (51) that receives the output of the suction superheat degree detection means (50) and controls the opening degree of the electric expansion valve (5 or 7) based on the suction superheat degree, and A high pressure overrise detection means (Ps) detects when the high pressure side pressure of the refrigerant circuit (11) exceeds a predetermined value, and when an output signal from the high pressure overrise detection means (Ps) is received, an opening degree changing means (52) for forcibly stopping the control of the opening degree control means (51) and changing the opening degree of the electric expansion valve (5 or 7) to be greater than the current opening degree; An operation control device for a refrigeration system, comprising: