JPH0612197B2 - Refrigeration equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a refrigeration system that heats air in a refrigerator by using a hot gas refrigerant from a compressor.

(Prior Art) Conventionally, a compressor, a condenser,
A circulating refrigerant circuit configured by connecting an expansion mechanism and an evaporator in series in a closed circuit is provided with a bypass passage branched from the compressor discharge side to bypass the condenser and the expansion mechanism, and the bypass passage is provided in the bypass passage. When a heating operation is performed through an electromagnetic on-off valve, the electromagnetic on-off valve is opened to guide the hot gas refrigerant from the compressor directly to the evaporator through the bypass passage, and the hot gas refrigerant stores the hot gas refrigerant. It is well known that the inner air is heated (see, for example, JP-A-59-122863).

(Problems to be Solved by the Invention) However, in the above-mentioned case, when the heating operation is performed,
The electromagnetic on-off valve is opened to send the hot gas refrigerant from the compressor directly to the evaporator through the bypass passage, but the refrigerant amount at that time depends on the state immediately before starting the heating operation. The amount is large or small. Therefore, when the amount of refrigerant is large, the compression work of the refrigerant in the compressor becomes large, so if the heating operation continues for a long time, the compressor will be in an overload operation state and the high pressure switch and the overcurrent relay will operate. Then the compressor will stop,
Since continuous operation cannot be performed and the reliability of the device is low, and the compressor stops frequently, it is necessary to repeat intermittent heating operation, and it takes a long time to converge to the set temperature in the refrigerator. there were.

The present invention has been made in view of the above points, and in the heating operation in which the air temperature is equal to or lower than the reference temperature, it is possible to control the amount of the refrigerant circulated between the compressor and the evaporator to an optimum fixed amount. This enables continuous operation of the compressor while suppressing the overload operation state of the compressor due to long-time heating operation, while when the air temperature is higher than the reference temperature, heating operation is performed with all refrigerants, etc. The purpose is to improve the property and quickly bring the internal temperature to a desired temperature.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention is
As shown in the figure, first, a circulating refrigerant circuit (closed circuit) formed by sequentially connecting a compressor (1), a condenser (2 or 3), an expansion mechanism (4) and an evaporator (5) in series ( 7), a bypass that is branched from the discharge side of the compressor (1) and bypasses the condenser (2 or 3) and the expansion mechanism (4) and is connected to the upstream side of the evaporator (5). A refrigerating apparatus provided with a passage (8) and a switching means (9) for switching the flow of the refrigerant from the compressor (1) to the condenser (2 or 3) side and the bypass passage (8) side. I am trying.

And the condenser (2 or 3) of the circulating refrigerant circuit (7)
And an on-off valve (11) provided between the fuel cell and the evaporator (5)
And a temperature detecting means (13a or 13b) for detecting the air temperature of the space to be cooled are provided. In addition, when the detected air temperature detected by the temperature detecting means (13a or 13) becomes lower than the reference temperature lower than the set temperature, the switching means (9) is moved from the compressor (1) before the heating operation is started. The refrigerant is a condenser (2 or 3)
The on-off valve (11) is closed in a state where the circulation refrigerant circuit (7) is placed in the liquid reservoir (B).
The pump down operation control means (C3) for performing a pump down operation for a predetermined time so as to store the refrigerant therein, and after the pump down operation by the pump down operation control means (C3), the opening / closing valve (11) is controlled to be opened. Heating operation control means (C) for executing a metering type heating operation in which a fixed amount of refrigerant flows from the liquid reservoir (B) to the low pressure side of the circulating refrigerant circuit (7).
4) is provided with a first heating means (C1). Further, when the detected air temperature detected by the temperature detecting means (13a or 13b) is lower than the set temperature and higher than the reference temperature, a heating operation different from the metering type heating operation of the first heating means (C1) is performed. The second heating means (C2) for executing the heating to heat the cooled space is provided.

(Operation) With the above configuration, in the present invention, when the air temperature of the cooled space is lower than the set temperature and higher than the reference temperature, for example, when the temperature is lower than the set temperature by −6 ° C., the second
The heating means (C2) performs a heating operation, for example, the entire amount of the refrigerant from the compressor (1) is circulated in the bypass passage (8), a so-called normal heating operation is performed, and rapid heating is performed.

On the other hand, when the air temperature of the cooled space becomes lower than the reference temperature, the first heating means (C1) executes the heating operation, and first, before the heating operation is started, the pump down operation control means (C3). ), The refrigerant from the compressor (1) is guided to the condenser (2 or 3) side and the on-off valve (1
When the pump down operation is performed for a predetermined time while 1) is closed, the refrigerant is retained in the liquid reservoir (B). After the pump down operation, the opening / closing valve (11) is controlled to be opened by the heating operation control means (C4) so that only a certain amount of the refrigerant from the liquid reservoir (B) is stored in the circulating refrigerant circuit (7). It flows to the low pressure side. As a result, a certain amount of the refrigerant from the liquid reservoir (B) is introduced to the low pressure evaporator (5) side, the heating operation is started by the constant amount of the refrigerant, and the inside of the refrigerator is heated. , Even if the heating operation is performed for a long time, the compressor (1) does not become the overload operation state, and it is possible to prevent the compressor from frequently stopping.
By continuous operation, the inside of the refrigerator can be quickly brought to the set temperature.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 2 to 4.

FIG. 2 shows an embodiment in which the present invention is applied to a refrigeration system (A) for a marine container. In the figure, (1) is a compressor,
(2) is a water-cooled condenser, (3) is the water-cooled condenser (2), and three blower fans (3) are operated when cooling water does not circulate.
a) ... Attached air-cooled condenser, (4) expansion valve as expansion mechanism, (5) two blower fans (5a), (5)
a) attached with a). Each of these devices (1)
Each of (5) is connected in series by a refrigerant pipe (6) so that the refrigerant can be circulated to form a closed circuit circulating refrigerant circuit (7). The refrigerant is sequentially cooled by an air-cooled condenser (3) by a compressor (1). ), A water-cooled condenser (2), an expansion valve (4), and an evaporator (5) to circulate and circulate through the compressor (1), so that the heat quantity of the gas refrigerant in the water-cooled or air-cooled condenser (2 or 3). Is discharged to the outside of the refrigerator and the evaporator (5)
In the above, the liquid refrigerant is made to absorb the amount of heat in the interior (cooled space) to cool the interior.

Further, (8) is branched from the discharge side of the compressor (1) in the circulating refrigerant circuit (7), and the water-cooled and air-cooled condenser (2),
(3) and expansion valve (4) bypassing evaporator (5)
A bypass passage (9) connected to the upstream side of the compressor (1) is arranged at a branch portion of the circulation refrigerant circuit (7) with the bypass passage (B) to condense the refrigerant flow from the compressor (1). It is an electrically operated three-way valve as a switching means for switching between the device (2 or 3) side and the bypass passage (8) side. By switching the three-way valve (9), hot gas refrigerant from the compressor (1) is directly guided to the evaporator (5) through the bypass passage (8) during the heating operation. In addition, the water cooling,
In the refrigerant pipe (6) between the air-cooled condensers (2) and (3) and the expansion valve (4), a pair of electromagnetic upstream side opening / closing valves (10) are provided.
And a downstream opening / closing valve (11) are provided with a predetermined pipe length interposed therebetween, and constitute a liquid reservoir (B) for storing a certain amount of refrigerant by the pump down operation of the compressor (1). is doing. (12) is an inside temperature setter that presets a desired inside temperature at the time of inspection immediately before navigation of a marine container (PTI (pre-trip inspection), etc.), and (13a) is blown air that is the air temperature of the cooled space. Temperature sensor for detecting temperature (for refrigerating operation), (13b) is temperature sensor for detecting intake air temperature which is the air temperature of the space to be cooled (for freezing operation)
The temperature sensors (13a) and (13b) form temperature detecting means.

Further, the three-way valve (9), the upstream side opening / closing valve (10), the downstream side opening / closing valve (11), the internal temperature setting device (12), and the temperature sensors (13a) and (13b) are the refrigeration system (A). Is connected to a controller (14) for controlling the operation of the device so that signals can be exchanged.

Inside the controller (14), as shown in FIG. 3, a CPU (21), a RAM (22), an RO.
An M (23), an I / O port (24) and an A / D converter (25) are provided.

Further, the controller (14) includes a first heating means (C
1) and a second heating means (C2) are provided, and the first heating means (C1) further comprises a pump down operation control means (C3) and a heating operation control means (C4). . Then, the second heating means (C2) receives each output signal from the temperature sensor (13a) or (13b), the internal temperature (T) is lower than the set temperature (SP), and the internal temperature is (T) is a reference temperature, for example, a set temperature (S
If the temperature is 6 ° C lower than P), the above three-way valve (9)
Is switched from the condenser (2), (3) side to the bypass passage (8) side, and the bypass passage (8) is fully opened so that the entire amount of the refrigerant from the compressor (1) flows to the bypass passage (8) side. By doing so, it is configured to perform an operation that does not depend on the measured constant amount of refrigerant, that is, a normal heating operation.

Further, the pump down operation control means (C3) receives each output signal from the temperature sensor (13a) or (13b), and the inside temperature (T) is the temperature reference temperature (the set temperature (S
P) to -6 ° C or less), the refrigerant from the compressor (1) flows through the three-way valve (7) to the condensers (2) and (3) side before the heating operation is started. Switch to
In addition, the upstream side opening / closing valve (10) is opened and the downstream side opening / closing valve (11) is closed to perform a pump down operation for a predetermined time so as to store the refrigerant in the liquid reservoir (B). Further, the heating operation control means (C4) switches the three-way valve (7) so that the refrigerant from the compressor (1) flows to the bypass passage (8) side after the pump down operation, and the upstream side. By closing the side opening / closing valve (10) and opening the downstream side opening / closing valve (11), the liquid reservoir (B) is formed.
A certain amount of the refrigerant is discharged to the low pressure side of the circulation refrigerant circuit (7) to perform the metering type heating operation.

The internal structure of the controller (14) is shown in FIG. In the figure, (MC) is a compressor motor, (MF1) is a blower fan motor of the evaporator (5),
(MF2) is a fan motor for the air-cooled condenser (3),
(10c) is a blower fan motor (MF2) of the air-cooled condenser (3) at the same time as operating the compressor motor (MC).
, A compressor relay having a normally open contact (10C-1) for allowing energization to, an evaporator (10F) having a normally open contact (10F-1) for operating the blower fan motor (MF1) of the evaporator (5) The fan fan relay (20S1) is an electromagnetic valve that is provided in the refrigerant pipe (6) and allows or blocks the refrigerant flow in the circulating refrigerant circuit (7).

Further, (31) is a high pressure switch, (32) is an overcurrent relay, the high pressure switch (31) and the overcurrent relay (32) are connected in series to the compressor relay (10C), The operation of the compressor (1) is stopped when the load of the compressor (1) becomes larger than a predetermined value or when an overcurrent flows through the compressor (1). Also (4
1) is a low-pressure pressure switch for pump down motion control.

In FIGS. 2 and 3, (35) is an accumulator with a heat exchanger, (Tr) is a transformer, (S) is a start / stop switch, (37) is a hydraulic protective pressure switch, and (38) ) Is a lamp switch, (39) is a hydraulic reset switch,
(40) is a compressor protection thermometer, and (42) to (45) are main switching switches, which are all interlocked with each other.
Is for voltage switching, (43) is for switching connection of the transformer (Tr), and (44) and (45) are for compressor motor (MC). Further, (60W) is a water pressure switch that is opened when circulating the cooling water to the water-cooled condenser (3), and that stops the blower fan motor (MF2) of the air-cooled condenser (3) during the opening operation. Is.

Next, the operation of the above-described embodiment will be described. When the heating operation is performed by the refrigerating apparatus (A), a desired set temperature (SP) is set in advance by the inside temperature setting device (12).
Then, the temperature inside the storage (T) is detected by the temperature sensor (13a or 13b), and the temperature inside the storage (T) is lower than the set temperature (SP) by 6 ° C. or more as shown in FIG. In this case, the first heating means (C1) executes the heating operation with the hot gas refrigerant as follows. That is, the controller (14) closes the downstream opening / closing valve (11),
The upstream side opening / closing valve (10) is opened, and the three-way valve (9) is closed by the hot gas refrigerant.
Switching operation is performed so that it is guided to the 1) side.

When the compressor (1) is pumped down in this state, the refrigerant from the compressor (1) is discharged from the downstream side opening / closing valve (11).
It will stay in the liquefied state in the refrigerant pipe (6) on the more upstream side. Next, when the low pressure switch (41) is opened and the pump down operation is completed, the controller (1
4), the downstream side on-off valve (11) is opened, the upstream side on-off valve (10) is closed, and the three-way switching valve (9) causes the refrigerant from the compressor (1) to flow to the bypass passage (6) side. Switch to be guided. As a result, only a certain amount of the refrigerant accumulated in the refrigerant pipe (6) having a predetermined pipe length between the upstream side opening / closing valve (10) and the downstream side opening / closing valve (11) is transferred to the low pressure evaporator (5) side. Therefore, the heating operation with the constant amount of the refrigerant, that is, the metering type heating operation is performed.

Then, the internal temperature (T) is lower than the set temperature (SP) by 1.
When heated to a temperature 5 ° C lower, the capacity of the compressor (1) is 33
% Operation, and thereafter the PID control of the three-way valve (9) causes the internal temperature (T) to converge to the set temperature (SP). That is, by calculating the proportional value (P), the integral value (I), and the differential value (D) with respect to the in-compartment temperature signal, it is possible to suppress an excessive temperature change and reduce the offset amount to reduce the in-compartment temperature. (T) is the set temperature (S
P) is quickly converged.

When the compressor (1) has insufficient capacity (33% capacity operation) and the internal temperature (T) is higher than the set temperature (SP) by 2.5 ° C or more, the three-way valve (9) causes the bypass passage (8). ) Is fully closed and the capacity of the compressor (1) is increased (100% operation)
Then, the internal temperature (T) is lowered. By this, when the internal temperature (T) is pulled down to a temperature higher than the set temperature (SP) by 1 ° C., the internal temperature (T) is set to the preset temperature (SP) by performing the PID control of the three-way valve (9) again. Controlled to approach.

On the other hand, when the internal temperature (T) is within the temperature range of 6 ° C. lower than the set temperature (SP), the second heating means (C2)
The heating operation is performed as follows. That is, the three-way valve (9) is switched from the condensers (2) and (3) side to the bypass passage (8) side, and the entire amount of the refrigerant from the compressor (1) flows to the bypass passage (8) side. By fully opening the bypass passage (8) as described above, an operation that does not rely on the measured constant amount of refrigerant, that is, a normal heating operation is performed, so that the inside of the refrigerator is quickly heated.

Therefore, in the above-described embodiment, when the temperature in the refrigerator is 6 ° C or more lower than the set temperature (SP) during the heating operation, the metering type heating operation is performed, so that the compressor (1) is operated for a long time. However, the compressor (1) never goes into the overload operation state. Therefore, the high pressure switch (31) operates,
Excessive current flows through the overcurrent relay (32) and the compressor (1)
Since it does not stop, the continuous operation becomes possible and the internal temperature (T) can be quickly converged to the set temperature (SP). Furthermore, when the temperature difference between the internal temperature (T) and the set temperature is less than 6 ° C, normal heating operation can be performed, and the internal temperature (T) quickly converges to the set temperature (SP). Can be made.

In this way, when the difference between the internal temperature (T) and the set temperature is larger than 6 ° C., the measurement type heating operation is performed.
To improve the durability of the on-off valves by reducing the number of times of opening / closing control of the two on-off valves (10) and (11) as much as possible, and when the difference is less than 6 ° C., the heating load is small. This is because it is considered that the high-pressure pressure switch (31) and the like will not operate because the normal heating operation time is short.

Although the three-way valve (9) is used as the switching means in the above embodiment, the bypass passage (8) of the circulating refrigerant circuit (7) is used.
An electromagnetic on-off valve may be provided on each of the downstream side of the branch point and the bypass passage (8) and the on-off valve provided on the bypass passage (8) may be opened freely. Naturally, it is possible to exert the action and effect.

As a modification of the second heating means (C2) in the above embodiment, as shown in FIG. 5, when the temperature difference between the internal temperature (T) and the set temperature (SP) is less than 6 ° C. Compressor (1) instead of heating operation with hot gas refrigerant
Is stopped and the evaporator fan motor exposed to the inside of the refrigerator is operated to heat the inside of the refrigerator by utilizing the heat generated by the fan motor. In addition to the performance, the operation of the compressor (1) and the operation of switching the three-way valve (9) are not necessary, and the durability of the compressor (1) is improved and the reliability of the device is further improved. improves.

(Effects of the Invention) As described above, in the present invention, when the air temperature is lower than the reference temperature, the pump down operation is performed at the start of the heating operation, and only a certain amount of the refrigerant stored in the liquid reservoir (B) is circulated as the refrigerant. Since the refrigerant is caused to flow out to the low pressure side of the circuit (7) and the heating operation is performed by the constant amount of the refrigerant, the amount of the refrigerant can be suppressed to be small by the metering type heating operation. As a result, even if the heating operation is continued for a long time, the compressor (1) is in an overload operation state, the high pressure switch (31) and the overcurrent relay (32) are activated, and the compressor (1) is stopped. The continuous operation can be performed without doing so, the reliability of the apparatus is improved, and the inside of the refrigerator can be quickly converged to the set temperature.

Further, when the air temperature is higher than the reference temperature, the first heating means (C1) performs the heating operation different from the metering type heating operation, so that the opening / closing control frequency of the opening / closing valve (11) can be minimized. Therefore, the on-off valve (1
The durability of 1) can be improved. Further, since the decrease in the air temperature is small and the heating load is small, the heating operation time which does not depend on the measurement is short, and the high pressure switch (31)
Since the above does not operate, it is possible to perform quick heating with all the refrigerant and heating with the compressor stopped due to heat generation of the fan motor.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 4 show an embodiment of the present invention, FIG. 2 is a refrigerant piping system diagram of a marine container refrigerating apparatus, FIG. 3 is an electric circuit diagram thereof, and FIG. 4 is a temperature inside a refrigerator during heating operation. It is a figure which shows the change of. Further, FIG. 5 is a view corresponding to FIG. 4 showing a modification of the present invention. (1) …… Compressor, (2) …… Water-cooled condenser, (3) ……
Air-cooled condenser, (4) ... Expansion valve, (5) ... Evaporator,
(7) …… Refrigerant circuit, (8) …… Bypass passage, (9)
...... Three-way switching valve, (10) …… Upstream on-off valve, (11)
...... Downstream side open / close valve, (13a, 13b) ...... Temperature sensor, (14) ...... Controller, (B) Liquid reservoir, (C
1) ... first heating means, (C2) ... second heating means,
(C3) ... pump down operation control means, (C4) ...
Heating operation control means.

Claims (1)

[Claims] 1. A circulating refrigerant circuit (7) formed in a closed circuit by sequentially connecting a compressor (1), a condenser (2 or 3), an expansion mechanism (4) and an evaporator (5) in series. Be prepared
A bypass passage (8) branched from the discharge side of the compressor (1) and bypassing the condenser (2 or 3) and the expansion mechanism (4) and connected to the upstream side of the evaporator (5); In the refrigeration system provided with a switching means (9) for switching the flow of the refrigerant from the compressor (1) to the condenser (2 or 3) side and the bypass passage (8) side, the circulating refrigerant circuit (7) ), A liquid reservoir (B) provided between the condenser (2 or 3) and the evaporator (5) and having an opening / closing valve (11), and a temperature detecting means for detecting the air temperature of the cooled space. (13a
Or 13b), and when the detected air temperature detected by the temperature detecting means (13a or 13b) becomes lower than the reference temperature lower than the set temperature, the switching means (9) is compressed before the heating operation is started. In the circulating refrigerant circuit (7), the on-off valve (11) is closed in a state where the refrigerant from the machine (1) is switched to flow to the condenser (2 or 3) side and the liquid reservoir (B) is closed. The pump down operation control means (C3) for performing a pump down operation for a predetermined time so as to store the refrigerant, and the on-off valve (1) after the pump down operation by the pump down operation control means (C3).
The heating operation control means (C4) for controlling the opening of (1) to execute a metering type heating operation in which a constant amount of refrigerant is discharged from the liquid reservoir (B) to the low pressure side of the circulating refrigerant circuit (7). When the detected air temperature detected by the first heating means (C1) and the temperature detection means (13a or 13b) is lower than the set temperature and higher than the reference temperature, the measurement formula of the first heating means (C1) The second for heating the space to be cooled by executing a heating operation different from the heating operation
A refrigerating apparatus comprising: a heating means (C2).