JPH03125861A - Refrigerator - Google Patents

Abstract

PURPOSE:To prevent the faulty insulation of a motor winding and deterioration of lubricating oil in a compressor by installing detectors individually detecting the outlet temp. of refrigerant and controllers sending signals decreasing the capacities of compressors on the basis of the signals from the detectors at protection networks. CONSTITUTION:At the protection networks of a plurality of compressors 3, 4 installed in parallel, detectors 27a, 27b detecting individually the outlet refrigerant temp. of respective compressors are installed and the refrigerant temp. T in either of the two outlet pipes (9a), (9b) is higher than the first set temp. T1, both compressors (3), (4) are stopped to operate an alarmer (30), on the contrary, when the temp. T is lower than the temp. T1, and for the temp. T2 and T3 (T1>T2>T3) the temp. T is in the range T2>=T>=T3 the rising of the operation frequency of a variable capacity type compressor (3) is prohibited and its capacity is maintained by a controller 21 as it is. In case of the range T>T2, the operation frequency of the compressor (3) is decreased to reduce down the capacity. Thereby, the outlet refrigerant temp. of the compressor (3) is reduced and following this reduction, the refrigerant temp. of a refrigerant outlet pipe (9b) of a constant capacity type compressor (4) which is interconnected by a collecting pipe (9) for the refrigerant is also reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION B) Industrial Application Field The present invention relates to a refrigeration system suitable for a heat pump type air conditioner that cools and heats multiple rooms.

(b) Conventional technology A refrigeration system in which a variable capacity compressor and a constant capacity compressor are connected in parallel, and these compressors, condensers, pressure reducers, and evaporators are connected in sequence to form a refrigerant circuit. was published in 1988-
It is presented in Publication No. 221349.

(c) Problems to be Solved by the Invention In the device presented in the above publication, the temperature of the discharged refrigerant is detected at the discharge pipe gathering part where the refrigerants discharged from the variable capacity compressor and the constant capacity compressor join together. If the discharge refrigerant temperature rises above abnormal temperature, malfunctions such as poor insulation of the compressor motor windings and accelerated deterioration of the lubricating oil will occur. An attempt was made to prevent insulation failure in the compressor motor windings and deterioration of the lubricating oil by reducing the capacity of the compressor.

Generally, the discharge refrigerant temperature of a compressor is determined by the high and low pressures and the degree of superheating of the suction refrigerant, but when a variable capacity compressor and a constant capacity compressor are operated simultaneously, the capacity of the variable capacity compressor is determined by the variable capacity compressor. This causes a difference in the discharge refrigerant temperature of both compressors, and detecting the discharge refrigerant temperature at the discharge pipe collection section as described above captures the average value of the discharge refrigerant temperatures of both compressors, so the discharge refrigerant temperature It turned out that it was not possible to accurately control the

We also attempted to detect the temperature of each compressor and/or the discharge refrigerant pressure of each compressor and stop multiple compressors at the same time if one of the compressors reached an abnormal state. It was found that it was not possible to determine which compressor was in an abnormal state, and inspection and repair required time and effort.

In view of these two points, it is an object of the present invention to provide a refrigeration system equipped with a protection circuit that can accurately control the temperature of the discharged refrigerant and determine which compressor is on the abnormal side.

2) Means for Solving the Problems The present invention provides a refrigerant circuit in which a plurality of compressors, a condenser, a refrigerant pressure reducer, and an evaporator are sequentially connected in a ring in parallel, and protection of the plurality of compressors. In a refrigeration system equipped with a circuit,
The protection circuit is provided with a detector that individually detects the discharge refrigerant temperature of each compressor, and a controller that issues a signal to reduce the capacity of the compressor based on the signals from each detector. It is.

Further, the present invention provides a refrigeration system including a refrigerant circuit in which a plurality of compressors, a condenser, a refrigerant pressure reducer, and an evaporator are sequentially connected in an annular manner connected in parallel, and a protection circuit for the plurality of compressors. , the protection circuit includes a detector that individually detects the temperature of each compressor and/or the discharge refrigerant pressure of each compressor, and an indicator that indicates the abnormal compressor based on the signal from each detector. , and a controller that issues a stop signal to each compressor based on the signal.

(*) When a variable capacity compressor and a constant capacity compressor are operated at the same time, the variable capacity compressor is operated to compensate for the lack of capacity with the constant capacity compressor. Therefore, the discharge refrigerant temperature of a constant capacity compressor usually tends to be higher than the discharge refrigerant temperature of a variable capacity compressor, and the discharge refrigerant temperature of a constant capacity compressor increases. When the set temperature is reached, the capacity of the variable capacity compressor is reduced based on a signal from a detector installed in the refrigerant discharge pipe of the constant capacity compressor, thereby reducing the temperature of the refrigerant discharged from the variable capacity compressor.
Along with this decrease, the refrigerant temperature in the refrigerant discharge pipe of the constant capacity compressor, which is connected through the refrigerant discharge collecting pipe, also decreases, which may cause insulation failure in the motor windings of the constant capacity compressor or lubricant leakage. Deterioration is prevented.

In addition, the temperature of each compressor and/or the discharge refrigerant pressure of each compressor is individually detected by a detector, and the display indicates the abnormal compressor based on this detection signal, so the operation of each compressor is controlled. Inspection and repair after stopping becomes easier.

(F) Embodiment To explain the present invention in detail, in Fig. 1, (1) is a variable capacity type in which the operating frequency is changed by an inverter device (2), and the minimum capacity is 2 horsepower and the maximum trench force is 5 horsepower. A compressor (3) and a constant capacity compressor (with a rated capacity of 5 horsepower)
4), a heat source side unit having a heat source side heat exchanger (5), and a gas-liquid separator (6), (7a) (7b) (7c) are user side heat exchangers (8a) (8b) < 8c) and 2
A user unit with the capacity of horsepower, 3 horsepower, and 5 horsepower.
A switching valve (ll
a) Branch connection via (llb), while heat source side unit (1) and user side unit (7a) (7b) (7c)
A high-pressure gas pipe (13) is branch-connected to the refrigerant discharge collecting pipe (9), and a low-pressure gas pipe (14) is branch-connected to the refrigerant suction pipe (10).
Consisting of a heat source side heat exchanger (5) and a connected liquid pipe (15), each user side heat exchanger (8a) (8b) (8c)
The high pressure gas pipe (13) and the low pressure gas pipe (14) are equipped with switching valves (16a) (17a), (16b) (17b), respectively.
), (16c) and (17c), and the liquid pipe (15) is connected to a refrigerant pressure reducer (15) such as an electric expansion valve.
8a) (18b)<18c).

(19) is the refrigerant discharge pipe (9b) of the constant capacity compressor (4)
(20) is the refrigerant discharge collecting pipe (9)
This is a bypass path provided across the refrigerant suction pipe (10), and the constant capacity compressor (4) is operated in this bypass path by a signal from the controller (21) as shown in Fig. 2. Bypass valves (22) (23) and a capillary tube (24) are provided which are closed when the compressor (4) is stopped and later than when the compressor (4) starts operating.

(25a) (25b) (25c) are branching units, (2
6) is a heating refrigerant pressure reducer such as an electric expansion valve.

<27a) (27b) are first detectors that detect the temperature of the discharge refrigerant flowing through each compressor (3), (4), and (7) refrigerant discharge pipe (9a) (9b), and (28a) and (28b) are each Compressor (
3) The second unit detects the motor windings and case temperature, etc. in (4).
Detectors (29a) and (29b) are for each compressor (3) and (4).
) The third detector detects the pressure of the discharged refrigerant flowing through the refrigerant discharge pipes (9a) (9b) of the first detector (27a) (
27b) is input to the controller (21), the inverter device (2) lowers the operating frequency of the variable capacity compressor (3) to lower the capacity, and finally both compressors (3) ( 4)
The operation of the detector is stopped and the alarm (3o) is emitted, and the second detector (28a) (28b) or the third detector (29
When any one of the compressors a) and (29b) is activated, the controller (21) inputs this signal to stop both compressors (3) and (4) simultaneously, and simultaneously stops the second compressor (3) and (4). Based on the signal from the third detector, an indicator (31) indicates the abnormal compressor, and these controllers (21) and the first to third detectors (27a) (27b) , (28a) (28b)
, (29a>(29c), alarm (3o), and display (
31) and protection circuit for both compressors (3) and (4) (32)
is configured.

Next, the driving operation will be explained. When cooling all rooms at the same time, open one switching valve (11a) of the heat source side heat exchanger (5), close the other switching valve (llb>), and close the user side heat exchanger (7a) (7b). (7c) (7) One switching valve (
16a) (16b) < 16c) and open the other switching valve (17a) (17b) (17c), the refrigerant discharged from the compressor (3) (4) flows into the discharge pipe (9
a) (9b), discharge collecting pipe (9), switching valve (lla),
After passing through the heat R side heat exchanger (5) and condensing and liquefying there, it passes through the liquid pipe (15) to each user side unit (7a) (7
b) (7c) Refrigerant pressure reducer (18a) (18b) (18
c), where it is depressurized. After that, after being evaporated in each user side heat exchanger (8a) (8b) (8c), the switching valve (17a) (17b) (17c), low pressure gas pipe (14), and suction pipe (10) are removed. , gas-liquid separator (6), and is sucked into the compressor (3) and (4). In this way, each user-side heat exchanger (8a) (8b) acts as an evaporator.
) All rooms are cooled at the same time in (8c).

Conversely, if you want to heat all rooms at the same time, use the heat source side heat exchanger (5
) closes one switching valve (lla) and opens the other switching valve (llb), and closes one switching valve (lla) of the heat exchanger (8a) (s
One of the switching valves (16a) (16b) (16
c) and open the other switching valve (17a) (17b) (
17c), the refrigerant discharged from the compressors (3) and (4) passes through the discharge pipes (9a) (9b), the discharge collecting pipe (9), and the high-pressure gas pipe (13) in sequence, and then passes through the switching valve (16a).
) (16b) (16c), each user side heat exchanger (8a) (
8b) (8c), and after being condensed and liquefied here, the pressure is reduced in each refrigerant pressure reducer (18a), (18b), and (18c), and they are merged in the liquid pipe (15), and then the heat source side After being evaporated in the heat exchanger (5), it passes through the switching valve (llb), the suction pipe (10), and the gas-liquid separator (6) in order to the compressor (3).
) (4). In this way, all the rooms are heated simultaneously by each user side heat exchanger (8a) (8b) (8c) acting as a condenser.

During such simultaneous cooling operation and simultaneous heating operation, the bypass valves (22) and (23) are closed so that the constant capacity compressor (4) has a rated output of 5 horsepower, and the variable capacity compressor (3) has a maximum output of 5 horsepower.
Each is driven by horsepower.

For example, if only the user unit (7b) is operated to cool or heat only this one room, a variable capacity compressor (3
) is in operation, and the constant capacity compressor (4) is stopped.

During such indoor operation, the bypass valves (22) and (23) are opened to prevent the refrigerant pressure in the discharge pipe (9b) of the constant capacity compressor (4) from increasing through the capillary tube (24). At the same time, the variable capacity compressor (
The discharge refrigerant pressure of 3) is prevented from being applied to the inside of the discharge pipe (9b), so that the constant capacity compressor (4) is smoothly started by opening the discharge vanes therein.

Such activation is performed when transitioning from single-room operation to dual-unit operation to the above-mentioned all-room operation, and as shown in FIG. 2, the bypass valve (22
)<23) is opened until the required horsepower of the user unit reaches 7 horsepower, and a part of the refrigerant discharged from the constant power compressor (4) is guided to the low pressure side via the bypass path (20). After reducing the output of the 5 horsepower constant capacity compressor (4) to 3 horsepower and reducing the capacity of the variable capacity compressor (3) to 2 horsepower to prevent the output from increasing rapidly, gradually Then, the power of this compressor (3) is increased, and then, at the same time as the bypass valves (23) and (24) are closed, the capacity of the variable capacity compressor (3) is again lowered to 2 horsepower and the output is suddenly increased. After making sure that the amount does not increase, the capacity of this compressor (3) is gradually increased. Therefore, when the variable capacity compressor (3) is operated independently to the simultaneous operation of the variable capacity compressor (3) and the constant capacity compressor (4), the output does not fluctuate rapidly.

In addition, if you want to simultaneously cool two units and heat one room at the same time, one switching valve (11a,
) and closes the other switching valve (Ilb>), and closes one switching valve (16b) <16c) of the cooling user unit <7b) (7c) while closing the other switching valve (17b) (17c). ), and when one switching valve (16a) of the heating user unit <7a) is opened and the other switching valve (17a) is closed, the compressor <3) (4)
A part of the refrigerant discharged from the refrigerant passes through the discharge collecting pipe (9) and the switching valve (lla) in order and flows to the heat source side heat exchanger (5), and the remaining refrigerant passes through the high pressure gas pipe (13) for heating. It flows to the switching valve (16a) of the usage side unit (7a) and the usage side heat exchanger (8a), and is condensed and liquefied in the usage side heat exchanger (8a) and the heat source side heat exchanger (5). The refrigerant condensed and liquefied in the heat exchangers (8a) and (5) passes through the liquid pipes (15) and is depressurized in the refrigerant pressure reducers (18b) (18c) of the user units (7b) (7c). , is evaporated in the respective user-side heat exchangers (8b) (8c), and then passes through each switching valve <17b) (17c) to the low-pressure gas pipe (
14), suction pipe (10), gas-liquid separator (6)
are sequentially sucked into the compressors (3) and (4). In this way, the user-side heat exchanger (8a) that functions as a condenser heats the room, and the other user-side heat exchanger (sb) (8c) that functions as an evaporator cools the two rooms.

During such simultaneous heating and cooling operation, the bypass valve (22) (23
) is closed and the user unit (7a) is heating.
The operating capacity is 2 horsepower and the cooling user unit (7b
) (7c), the constant capacity compressor (4) has 5 horsepower and the variable capacity compressor (3) has 3 horsepower to match the larger 8 horsepower. It is being driven by.

During the above-mentioned cooling operation, heating operation, and simultaneous cooling and heating operation, the temperature of the discharge refrigerant flowing through the discharge pipe (9a) and the discharge pipe (
The temperature of the discharge refrigerant flowing through the discharge collecting pipe (9b) and the temperature of the discharge refrigerant flowing through the discharge manifold pipe (9) change as shown in FIG.
When both compressors (3) and (4) are operated simultaneously, the refrigerant temperature in the collective discharge pipe (9) corresponds to the average value of the refrigerant temperature in the discharge pipe (9a) and the refrigerant temperature in the discharge pipe (9b). are doing. Therefore, by detecting the refrigerant temperature in the collective discharge pipe (9), it cannot be determined even if the refrigerant temperature in the discharge pipe (9b) reaches an abnormal temperature. The temperature is individually detected by first detectors (27a)<27b) and controlled based on the flowchart shown in FIG.

That is, when the refrigerant temperature T of either one of the discharge pipes (9a) (9b) is higher than the first set temperature T, both compressors (3)
('4) is stopped, the alarm (30) is activated, and the first
The capacity is lower than the set temperature TI, and when the refrigerant temperature T is in the range of T, ≧T≧T, with respect to T2, the third set temperature T*, Ts (T, > Tt > T3). Capacity is maintained by preventing an increase in the operating frequency of the variable compressor (3).

On the other hand, when the range is 'r>'rz, the variable capacity compressor (
By lowering the operating frequency of 3) to lower the capacity, the temperature of the refrigerant discharged from the variable capacity compressor (3) decreases,
Along with this decrease, the refrigerant temperature in the refrigerant discharge pipe (9b) of the constant capacity compressor (4), which is communicated with the refrigerant discharge manifold pipe (9), also decreases. When the variable capacity compressor (3) drops to the lowest operating frequency (minimum capacity), the constant capacity compressor (
4) stops. Despite this stoppage, if the variable capacity compressor (3) is operated at the lowest operating frequency (minimum capacity), the variable capacity compressor (3) will also stop, and the alarm (30) will be activated.
is activated.

In this way, the refrigerant temperatures in the discharge pipes (9a) (9b) are individually detected by the first detectors (27a) (27b), and as the refrigerant temperature in either one increases, the variable capacity compressor (
By controlling the operation of both compressors (3) and (4), such as reducing the capacity of 3) and stopping the constant capacity compressor (4), the discharge refrigerant temperature is kept within the permissible temperature range.

At the same time, there is a second problem when operating cooling, heating, or simultaneous heating and cooling operation. Third detector (28a) (28b), (
29a) (z9b) detects the temperature of both compressors <3) (4) and the discharge refrigerant pressure of the discharge pipes <9a) (9b). Temperature is set value 13
The temperature exceeds 5°C or the discharge refrigerant pressure reaches the set value of 28.5k.
g/Cm", either of the detectors (26a)
Since the contacts (26b), (27g) and (27b) are opened and the alarm signal is input to the controller (21),
Both compressors (3) and (4) stop operating with a signal from the controller (21), and at the same time an alarm is issued to indicate which compressor is on the abnormal side and exceeds the set value, as shown in the flowchart shown in Figure 4. Since the indicator (31) indicates based on the signal, inspection and repair after the compressors (3) and (4) have stopped operating becomes easier.

In addition, in the above embodiment, the inter-unit piping (12) is composed of three high-pressure gas pipes (13), low-pressure gas pipes (14), and liquid pipes (15).
Since it is constructed with wooden refrigerant pipes, it has a simple circuit configuration using a single-function heat source side heat exchanger, and can perform simultaneous cooling and heating operations of multiple user-side units as well as simultaneous cooling and heating operations. It can be freely selected and performed on any user unit, and the user heat exchanger, which acts as a condenser, and the user heat exchanger, which acts as an evaporator, are connected in series during simultaneous heating and cooling operation. Although efficient operation can be performed by heat recovery, the present invention is not limited to such a refrigerant circuit.

In addition to the variable capacity compressor (3), in addition to the inverter type in which the operating frequency changes, the variable capacity compressor (3) may also be one in which the capacity changes in multiple stages, such as a pole conversion type or an unloader type.
Further, all of the plurality of compressors may be of variable capacity type.

(G) Effects of the Invention According to the present invention, a detector for individually detecting the discharge refrigerant temperature of each compressor is provided in the protection circuit of a plurality of compressors connected in parallel. The possibility that an abnormality cannot be detected even if the discharge refrigerant temperature of the other compressor exceeds an abnormal temperature due to the influence of the refrigerant temperature that fluctuates due to a change in the capacity of the compressor is eliminated, and the discharge refrigerant Since the capacity of the variable capacity compressor is reduced when the temperature rises to the set temperature, it is possible to prevent insulation failure in the motor windings of the compressor and prevent deterioration of the lubricating oil while continuing operation.

In addition, a protection circuit for multiple compressors connected in parallel,
A detector that individually detects the temperature of each compressor and/or the discharge refrigerant pressure of each compressor, and an indicator that indicates the abnormal compressor based on the signals from each detector are provided.
When inspecting and repairing a plurality of compressors after the operation is stopped, it is possible to identify which compressor is abnormal on the display, so that inspection and repair work can be easily carried out.

[Brief explanation of the drawing]

FIG. 1 is a refrigerant circuit diagram of a refrigeration system showing an embodiment of the present invention;
Fig. 2 is an explanatory diagram showing the operating pattern of the compressor and changes in refrigerant discharge temperature, Fig. 3 is a flowchart showing the operating operation,
FIG. 4 is a flowchart showing the abnormality display operation. (3)...variable capacity compressor, (4)...constant capacity compressor, (9g) (9b)-refrigerant discharge pipe, (18
a) (18b) (18C)... Refrigerant pressure reducer, (21
)...controller, (27a) (z7b), (28
a) (28b), (29a) (29b)...detector, (31)--indicator.

Claims (2)

[Claims] (1) In a refrigeration system comprising a refrigerant circuit in which a plurality of compressors, a condenser, a refrigerant pressure reducer, and an evaporator are sequentially connected in an annular manner connected in parallel, and a protection circuit for the plurality of compressors, The protection circuit is equipped with a detector that individually detects the discharge refrigerant temperature of each compressor, and a controller that issues a signal to reduce the capacity of the compressor based on the signals from each detector. refrigeration equipment. (2) In a refrigeration system comprising a refrigerant circuit in which a plurality of compressors, a condenser, a refrigerant pressure reducer, and an evaporator are sequentially connected in an annular manner connected in parallel, and a protection circuit for the plurality of compressors, The protection circuit includes a detector that individually detects the temperature of each compressor and/or the discharge refrigerant pressure of each compressor, an indicator that indicates the abnormal compressor based on the signal from each detector, and the A refrigeration system comprising a controller that issues a stop signal to each compressor based on the signal.