JPS60108649A - Refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a refrigeration system.

In general, container refrigeration equipment operates in two ways: refrigeration operation that controls the internal temperature of the container within the freezing range of -5°C to -6°C, and control operation that controls the internal temperature of the container in the chilled range of temperatures higher than -5°C to -6°C. Therefore, the capacity of the container refrigeration equipment is the required refrigeration capacity during refrigeration operation, for example, when the outside temperature is 38°C and the internal temperature is 118°C.
It is designed to have a refrigerating capacity that can hold 100 liters of water.

Therefore, when performing refrigeration operation that maintains the internal temperature in the chilled region, the capacity may be too high under conditions where the outside temperature is low.
A problem arises in that the temperature inside the refrigerator cannot be maintained at the desired temperature.

Therefore, in order to solve the envy problem more than before, a hot gas bypass pipe was installed between the high pressure gas pipe and the low pressure liquid pipe, and the hot gas was sent to the evaporator to control the temperature inside the refrigerator. Proposed.

This conventional refrigeration system is disclosed in U.S. Patent No. 6.692.1.
As shown in the specification and drawings of No. 00, and as shown in Fig. 6, the pressure gas 'FM' ( B) In the middle of the condenser (Qs), the water-cooled condenser (o2), dryer (R), and expansion valve CXV) connected in series with the condenser (Qs) are bypassed. . Connect the high-pressure liquid pipe (H) connecting the hot gas bypass pipe (H) to the outlet of the expansion valve (EV) D) Along with K connection tJ-, connect 'I'1f and magnetic valve (S) to the bot gas bypass pipe (H).
It is equipped with a temperature control valve (TV) that has a sensor ('I') that detects the temperature of the air being blown out. This has been made possible by the following.

That is, when performing refrigeration operation, the solenoid valve (s v )
f open W, when the blowing air temperature is below the set value, the temperature control valve (T'V) is opened and the hot gas is passed through the low pressure liquid pipe (
D), where it joins with the liquid refrigerant that has passed through the expansion valve (IDV) and is introduced into the evaporator (E) to adjust the temperature of the blown air and control the temperature inside the refrigerator to a chilled region.

However, according to the conventional device as described above, when the set temperature inside the refrigerator is low, or when the outside temperature is higher even if the set temperature is high, the temperature inside the refrigerator is controlled by the hot gas bypass described above. However, if you raise the set temperature and the outside air is 7M degrees lower than this set temperature,
), solenoid valve (S V ) 1< Even if the hot gas is bypassed, the internal temperature setting 'IM
The problem arises that it is not possible to control the degree.

The reason for this is that the thigh tension valve (KV) normally uses a temperature-sensitive expansion valve, so as the outside temperature drops, the opening of the solenoid valve (SV) increases and the hot gas The amount of bypass increases, but due to this increase in the amount of hot gas, the low pressure gas refrigerant on the outlet side of the evaporator (E) eventually becomes superheated gas, and therefore the low pressure gas pipe CG
), the opening degree of the expansion valve (EV) increases by 1 litf, and as a result, even if the outside temperature drops, the 4-3 generator (IC) & If the amount of liquid refrigerant supplied decreases (force), the amount of liquid refrigerant supplied increases,
The reason for ffs 2 is that when the outside temperature drops significantly, the air-cooled condenser (
The ambient temperature of the water-cooled condenser (Qz) decreases, and the temperature of the water (such as seawater) used in the water-cooled condenser (Qz) also decreases. This is because the condensing pressure (temperature) of the compressor (A) decreases, and as a result, the discharge pressure (α pressure) of the compressor (A) and the discharge gas temperature, i.e., the temperature of the hot gas, decrease, resulting in a lower heating capacity. It is believed that there is.

Invention X was invented in view of the above-mentioned problems of the conventional technology.
The degree of opening of the expansion valve is controlled to reduce the amount of liquid refrigerant passing through the expansion valve, and an electric heater is provided in the evaporator, and this electric heater is used to reduce the high pressure caused by the drop in outside air. The heating capacity of the hot gas is compensated for by reducing the heating capacity of the hot gas, thereby making it possible to widen the range of control of the temperature inside the refrigerator by the hot gas in the chill and cold regions. be.

Therefore, the configuration of invention
A hot gas bypass path is provided to guide the hot gas discharged from the compressor to the steamer by bypassing the condenser and the temperature-sensitive expansion valve, and a hot gas valve is provided in the hot gas bypass path. At the same time, a control passage is provided in the hot gas bypass passage on the outlet side of the hot gas valve to connect with the pressure equalization pipe described in iiJ and to control the opening degree of the tension valve iiJ according to the hot gas pressure, and 10,000, said evaporator. An air heater is attached to the air heater, and a detector is installed to detect the outside air temperature or the condensation temperature or high pressure of the sub-condenser indicated by fTI, and the operation of the air heater is controlled by the operation of this detector. When the hot gas bypass is performed, the opening degree of the expansion valve is controlled using the pressure of the hot gas so that the amount of liquid refrigerant passing through the expansion valve can be reduced. By enabling the electric heater to operate, the range of control over the temperature of the blown air using hot gas can be expanded.

Next, embodiments of the present invention will be described based on the drawings.

In Fig. 1, (1) is a compressor, (2) is an air-cooled condenser, (3) is a water-cooled condenser, (4) is an evaporator, (5) is a pressure equalization pipe (51) and a temperature sensing section. (52), and each of these devices is connected by a refrigerant pipe (6) to form a refrigeration cycle that cools the air in the refrigerator from the evaporator (4). .

In Fig. 1, (7) is an integrated accumulator receiver, (8) is a dryer, (9] is a solenoid valve for pump down, (10) is a liquid indicator, and (11) is
is the shunt, and (12) is the 1% low pressure switch (HLP
S), hydraulic protection switch (OPS), water pressure switch (
WPS), (16) is a safety device with two fans attached to the evaporator (4), (14a + 14b)
, 14c) are the six fans attached to the soul condenser [2].

In the refrigeration cycle configured as described above, the high-pressure gas pipe (6a) connecting the discharge side of the compressor (1) and the air-cooled condenser (2) is connected to a separate pressure machine (1). The discharged hot power is transferred to each of the condensers (2) and (3).
, connect the hot gas bypass path (20) that bypasses the liquid receiver of the accumulator liquid receiver (7) and the temperature-sensitive expansion valve (5) and leads to the evaporator [4) I, and the outlet side thereof is connected. A hot gas valve (21) is connected to the low pressure liquid pipe (6b) between the expansion valve (5) and the evaporator (4), and is interposed in the middle of this bot gas bypass path (20). At the same time, a low pressure gas pipe (6c) in the refrigeration cycle is connected to the hot gas bypass path (20) on the outlet side of the mI pot gas valve (21).
) A control passage (22) is provided which is connected to the pressure equalizing pipe (51) of the expansion valve (5) connected to the expansion valve (5) and controls the opening degree of the expansion valve (5) using hot gas. , the hot gas bypass path (20) and the pressure equalization pipe (51
) is provided with a communication cutoff valve (26) that cuts off communication with the air conditioner.

The hot gas valve (21) may be a solenoid valve with an on/off function, but it is mainly a 1L magnetic proportional control that can control the valve opening from 0% to 100% in proportion to the tortoise pressure. This is done using a valve and controlled by a controller (24) as described below.

In addition, the niJ communication cutoff valve (25) mainly uses a three-way switching valve as shown in FIG.
Connect the mJ control passage (22) to the other pressure equalization pipe (51).
At the same time, connect the first pressure equalizing pipe (51a) divided into the two, and connect the second pressure equalizing pipe (511) to the fixed boat,
A second pressure equalizing pipe (1-1) communicates with the pressure equalizing part of the expansion valve (5).
511)), the ffrJ control passage (22) and the first J@
This is done as if switching to a pressure pipe (51a).

Finally, the outlet side of the hot gas bypass path (20) is
As mentioned above, it is connected to the low pressure liquid pipe (6b), and although the connection position is not limited, it is preferably connected to the flow divider (11,).

Furthermore, a detector (HD!31) for detecting high pressure is connected to the high pressure gas discharge pipe, and the evaporator (
4] is provided with an electric heater (Hll H2) that is controlled by the operation of the detector (p st).

In addition to the electric heater (HBH), the evaporator (4) is provided with auxiliary electric heaters (Hx to H (not shown in FIG. 1)).

In addition, 7 amps (14a) for the condenser c2).

14b, 14c) 5 motors (MF2
-1, MF2-2, MF2-3), so that one motor (MF2-1) and the other two motors (M?2-2, MP2-3) can be operated independently. The two motors (MF2-2 and MF2-3) are connected to the power source via a high pressure switch (HPS), and a high pressure switch (HPSI) separate from the detector (HPSI) is connected to the power supply. It is controlled by the operation of St.

Next, the hot gas valve (21) and the communication cutoff valve (26)
The electrical circuit of a refrigeration system having a controller (24) that controls the blown air to a desired temperature of 7M degrees will be explained based on FIG. 2. The electric circuit of the refrigeration equipment shown in the figure is a three-phase power line I. A compressor motor (OM) is connected through the contacts of the relay (01).
Five motors (Jtge 2-1, M
F2-2, MF2-3) are connected in parallel.

In addition, two motors (M Fl, , M Fz) for the evaporator (4) are connected to two phases of the three-phase power supply line (M Fl, , M Fz).
A2] are connected in parallel through the contact point. In addition, the electric heater (H'' + H'') and the auxiliary electric heater (H~l(6)) are connected to the power supply line by a relay (H''), respectively.
It is connected through each contact of R (HR).
S) is the water pressure switch described above.

Furthermore, the controller (24) and the control relay circuit of the electrical equipment are connected to the controller (24) and the control relay circuit of the electric equipment by drawing out two power lines from the power source line (MF 2-1) through a switch (SW).
, MF 2-2, MF 2-33, drive circuit (7
1], evaporator (4) motor (MF 凰) drive and defrost control circuit (72), detector (HPS circuit (7)
6], a heater circuit (74) and the controller circuit (75) are connected. Each of these circuits will be explained below.

■ The drive circuit (71) is connected to the compressor motor (CM
) and motor (7M2-1, 7M2-2.7M2-
3) start/stop relay (01) and high/low pressure switch (HLP)
It consists of a series circuit of S) and an overflow relay (Oa).

■ Motor (F Ml, F
The upper movement and defrost control circuit (72) of Ml) is
A series 1u path between the parallel circuit of the start/stop relay (02) of the motor ('F Ml, F Ml) and the defrost timer (TR), and the normally closed contact (DR-2) of the defrost relay (DR). and the defrost IJL/-(D
R), a defrost temperature switch (TS), a normally open contact (DR-1) of a defrost relay (DR), and a parallel circuit of a normally open contact of the timer (TR) and a series circuit.

■ The detector (HP ss) circuit (76) consists of a detector (HP ss) which is a pressure switch that closes only when the high pressure (HP) is below the set pressure capo; and a relay (Xl). Normally open contact (XI -3') and the above 'g
Relay (OR) that controls the operation of electric heaters H1 and II
) consists of a series circuit power). Note that the relay (OR) has its normally open contact (OR-2) connected to the electric heaters (Hl, H
Relay (HR1) is connected to the 1st column.
In this way, the operation of the electric heaters ()it, )(t) can be controlled by excitation and demagnetization of the detector (the IJ-COR by the on/off operation of the HP S). The heater circuit (74) connects a parallel circuit between the electric heater (llt, Hz relay (HRI)) and the auxiliary electric heater (Hx~H relay (HRI) through a temperature fuse (FS). te differential 0 street relay (D
normally open contact (DR-3) of R), normally open contact COR-2) of the relay (OR), normally open contact of the relay (XS),
(2) Connect in series to the parallel circuit with A defrost relay (DR) connected in parallel to the relay (HR1) through a parallel circuit with a normally open contact (DR-4) and a normally closed contact (OR-1) of the relay (OR). It is.

O The controller circuit (75) connects the electric part (20M) of the hot gas valve (20) and the normally open contact (XI-) of the relay (XI) to the output end of the controller (24).
2) and the normally closed contact (DR) of the defrost relay (DR).
-5) in series circuit with the solenoid valve (9) for pump down.
) of the solenoid relay (20St) and the normally closed contact of the defrost relay (DR) (a series circuit with DR-63, the solenoid relay (20S of the communication cutoff valve (23)) and the normally open contact of the said relay (X!) Series circuit with contact (XI-1) and electric heater (lls, Hri, auxiliary electric heater (
The above-mentioned relay (X2
] are connected to each other.

The controller (24) includes a supply sensor (SS), a return sensor (R3), and four switches (1.≠2.+3, 4), and if the set temperature (SE! TI') of the internal temperature to be controlled by the controller (24) is manually set in advance, if the set temperature (5ETT) is in the refrigeration range, the switch ( reactor)
is closed, and the supply sensor (SS) operates to adjust the blowout air temperature (SUPT) and the set temperature (
SK'l"T), and the internal signal
It controls the output voltage to section J (20M) and also controls the opening and closing of the switches (see 1, 2, and 3), and the set temperature (SFt'F'l') is in the freezing range. If so, the switch (t3) is opened and the return sensor (R3) is activated.

Now, the refrigeration operation of the refrigeration system constructed as above will be explained based on the 70-chart and the M rotation pattern characteristic diagram in FIG. 3.4.

In this refrigeration operation, the controller (24) controls the set temperature (SKTT) and the blowing air temperature (SUPT).
The operation pattern of the refrigeration system can be changed in four ways by controlling the opening and closing of switches (≠1 to 4) using internal No. 1 according to the temperature difference between These operation patterns will be briefly explained in advance based on FIG. 4.

In FIG. 4, (Δtl to Δtz) is the blown air temperature (S
It shows the boundary temperature difference that changes the operation pattern when the temperature (UPT) decreases, and (Δt4 to Δts) similarly shows the boundary temperature difference when the discharge air temperature (SUPT) increases. The region (■ to IV) collectively indicates the temperature difference (Δt) that makes the operating pattern of the refrigeration system the same when the discharge air temperature (SUPT) decreases and when the discharge air temperature (SUPT) increases.

Hereinafter, the four driving patterns will be explained for each region [1 to ■].

■ In region (I), the controller (24) closes the switches (1. to 6) and opens the switches (2, +4) according to an internal signal, stops the hot gas bypass, and completely freezes. Performs refrigeration operation by making full use of its capacity. [Full operation range] ■ In range (II), all switches (
~≠4) is closed to control on/off of the electric heater (Hl, Hz) and fans (14b, 14c) for the coagulator (2), and control the opening degree of the hot gas valve (2o). and perform refrigeration operation. (Hot gas control operation region) ■ In region (I[), only the switch (≠3) is closed, the refrigeration system is maintained in a pump-down state, and the operation of the compressor (1) is stopped. (Bondown region) ■ In region (IV), only the switch (+6. to 4) is closed, and the electric heater (H
Heating operation is performed by the auxiliary electric heater (Hs to H). (Heating region) The control of the refrigeration operation based on the above operation pattern will be explained below.

Therefore, when the refrigeration system starts the refrigeration operation, the solenoid relay (20S is demagnetized 7:l) and the solenoid valve (9) remain closed, and the ni1
The pump is in a pump-down state during the pump-down operation that is performed after the previous operation.

Then, depending on which of the four ranges the blown air temperature (temperature inside the refrigerator) falls in at the beginning of the operation, the operating pattern is started.

1) The temperature difference (Δt=sUPT-8ETT) is the area (I
), only the switches (S1 and S3) are closed.The solenoid relay (20Sl) is energized and the pump down switch is activated.
Since the switch (2) is opened at the same time as the solenoid valve (9) 1 is opened, the switch/id relay (20S) is opened.
i) is held in the demagnetized state LQ i and the communication cutoff valve (2
3) is maintained while communicating the first pressure equalizing pipe (51a) and the second pressure equalizing pipe (52b). Also relay C01),
C02 is excited and the compression motor (OM) and condenser (
2) Each motor (7M2-1, 7M2-2, 7M2-3) of the six fans (14a; 14b, 14Q)
The motors (FMI□, FMS) of the two fans (13, 13) for the evaporator (4) are driven. At this time, the application to 'd electric part 20M) of the hot gas valve (20), 1
1 pressure is O, and the hot gas bypass amount is 60, so the refrigeration system ft is operated at full capacity to maximize its refrigeration capacity. As a result of this operation, when the blown air degree IIA decreases, the operation butter 2/l in the following region (II)
This transition Tru.

2) 77! When the degree difference (Δt) belongs to region (II),
Since the switch (+3) is also closed together with the switches (41, +22), the solenoid valve (9) is in an open state, and the solenoid relay (20Sx) is energized so that the communication cutoff valve (23) is closed. control passage (22) and the second
The pressure pipe (511) is switched so as to communicate with the pressure pipe (511).

Also, as in region (1), the compressor motor (OM) and the motors (FMI) for the evaporator (4) are driven, and the motor (7M2) for the condenser (2) is driven.
-1, 7M2-2, 7M2-3) are driven by one or three units, which will be described in detail later.

In addition, the controller (24) controls the temperature indicated by mJ (∆
Corresponding to t), the eye J7 to the '1 moving part (20M)
The opening degree of the hot gas valve (20) is adjusted by controlling the J[7 voltage, and the bypass amount of hot gas is reduced to N11. IJ, ■ When the temperature difference (Δt) is positive (Δt>0), the voltage applied to the electric part (20M) is reduced, the opening degree of the hot gas valve (20) is reduced, and the pot is closed. It reduces the amount of gas bypass, and ■ rioJ 77! When the temperature run (Δt) is O (Δ1 = 0), the above-mentioned application 'E' is maintained, the opening degree of the valve (20) is maintained, and the temperature difference (Δ1) shown in J is negative (Δb< 11), the applied voltage is increased and the hot gas valve (20)
By increasing the opening degree of the hot gas, the bypass amount of hot gas can be increased.

Furthermore, at the same time, the hot gas valve (21) (7
) During the opening operation, the hot gas flowing through the hot gas bypass path (20) is
At a pressure of 5 L, the second j4 of the nil expansion valve (5)
Also acting on fE%f (5l b ), the expansion valve (
5] to the valve opening IW corresponding to the pressure of the hot gas.

Therefore, the amount of liquid refrigerant passing through the MU expansion valve (5) decreases in accordance with the opening degree of the valve, and the desired flow hλ' of hot gas is introduced to the evaporator (4) via the flow divider (11). With the refrigeration capacity reduced by decreasing the opening degree of the expansion valve (5), heating by S&C becomes possible, and the temperature at which the air is blown out is controlled by bypassing the hot gas. can be performed with an accuracy of 1%.

Further, in area (1), in parallel with the above control,
A detector that operates by detecting high pressure (HPS) is activated, for example ■ If the outside air temperature decreases and the high pressure (HP) decreases below the set pressure (HP), 011
The gripping pressure switch (PS) closes and the nil relay (
OR) is excited to energize the heater (u'+Hx). As a result, the reduction in heating ability due to a decrease in the temperature of the hot gas is compensated for by heating by the electric heater (HIIHI).

In this case, the set pressure of the high pressure switch (HPS2) for controlling the 7 am (14b, 14c) is set by the detector (H
If the pressure is set higher than the set pressure on page 81), the high pressure switch (HPS2) will open first due to the drop in high pressure, and the fan (14'b) will open.

14C), and if the high pressure continues to drop even after this, the detector (HP Sl) will close and the hypocardial heater (Hl) will close.
, Hr is turned on, which is advantageous from the point of view of energy saving.
The set pressure of Sl) may be opposite to the above.

■ Also, when the output pressure (HP) is higher than the set pressure (HPo), the nil relay (OR) is demagnetized.

Therefore, the electric heater (Hll Hz) is de-energized.

As described above, the controller (24)≦controls the opening degree of the hot gas valve (20), and the expansion valve (20) controls the opening degree of the hot gas at the outlet side of the valve (20). 5) In parallel with the opening degree control, the electric heaters (L(l, H) are on/off controlled by the operation of the detector (HP Sl), so even in a range where the outside temperature is low, the The control range is expanded so that the controller (24) can accurately control the blowing air temperature (SVP'l').This point will be supplementarily explained based on FIG. 5.

Figure 5 shows the outlet air temperature (SUPT), which is determined by the operation control of the refrigeration system, with respect to the outside temperature. This shows the range of the set temperature (SETT) that can maintain the IJ temperature difference (Δ1) within the range (n). In the figure, the area (a) is the conventional one, and the area (b) is the new one An example of possible set temperature ranges is shown.

Furthermore, when the temperature difference (Δt) deviates from the region (I[)],
The operation control shifts to the above-mentioned region (I) or the region (■) described below.

(b) When the temperature difference (Δt) is in the range (I[), in this case, only the switch (6) of the controller (24) is closed and the switch (2) is open. The solenoid relay (20S) is held in a demagnetized state, resulting in the fan (F Ml, F
Only M is operated and the pump down state is maintained.

If the temperature difference (Δt) becomes a temperature difference in another area, the above area (]I) or the area below (■)
Shift to a driving pattern.

4] When the temperature difference (Δt) is in the region (IV ), the switch (+6.4) of the controller (24) is closed, and the switch (+2) remains open. Similarly to CII+, ), the fans (F Ml, F Ml) for steaming d (4) are operated, and the pump-down state is maintained, and at the same time, the relay (Xl) The normally open contact (Xl-
1), (xz-2) is closed and the mlt+air heater (H'' + H') and the auxiliary electric heater (H3~H
(a) are both electrically charged and heating operation is performed.

Incidentally, when the temperature difference (Δt) increases to reach the temperature difference in the region (■), the operation shifts to the operation control in the region (1111) marked nIJ.

In addition, the defrost timer (TR) operates at the same time as the start of the second series, and the normally open contact (TR) is closed at a predetermined 115 seconds to energize the defrost relay (DR). Close the normally open contacts (DR-3) and (DR-4) to connect the electric heaters (Hl, H, auxiliary 7u
(Hs to H6) This is performed by applying current to i.

In addition, the normally open contact (DR-1) constitutes a self-holding circuit, and the above +1111 income isochi (2
3D) is opened due to a temperature rise in the evaporator (4), and the defrost operation is terminated. In addition, the 4U timer (TFt) is the defrost (IJ Shire DR)
is energized and the normally closed contact (DR-2) is made R, so that it is reset.

Next, we will briefly explain how to control the number of runs in refrigeration operation.

In the controller (24), only the switch (2) is closed, the solenoid relay (20SIJ is energized &1, and the solenoid valve (9) is opened, and at the same time, the pressure sardine machine motor (OM) and the condensing 6 fans (14
a, 14b, 140) motor (FM2-1, FM
The motors (FMI, FM2-2, FM2-3) and the fans (13, 13) for the evaporator (4) are operated.

Incidentally, since the switch (2) is kept closed, the solenoid relay (20S) is demagnetized, and the communication cutoff valve (23) is connected to the first pressure equalization station (51a) and ii. 2 Connect the J@ pressure pipe (51b), and the iu pressure applied to the MJ moving parts (20M) in item 11 is maintained at 0, and the hot gas valve (2o) is fully closed. This allows normal refrigeration operation without bypassing hot gas.

In the above embodiment, in the operation control of the region (II), a pressure switch was used as a detector for controlling the operation of the electric heaters (Hl, Hl). (2) A temperature switch for detecting condensed humidity may be used.
l) I tried to operate only the electric heater (Ht, Hz), but the detector (HPSs) detected that the electric heater (Hl, H) and the condenser (2) fan γ7 were activated. (14b, 14c) motor (7M2-2,
F'M2-3) may be controlled on and off at the same time.

As described above, the present invention provides a hot gas bypass 5c2o]ic, s thermal expansion valve (5c) of the hot gas valve (21) according to Roy's law.
A control passage (22) is provided which is connected to the pressure equalizing pipe (51) of the expansion valve (5) and controls the opening degree of the expansion valve (5) using hot gas.
) is controlled by the pressure of the hot gas on the output side of the hot gas valve (21), the flow of liquid refrigerant passing through the expansion valve (5) can be reduced. too,
The decrease in heating capacity caused by the decrease in the outside air temperature, the decrease in the high pressure, and the decrease in the hot gas temperature is compensated for by the amount of heat of the electric heater (Hll H).
Compared to the conventional method, the liquid cooling tank passing through the expansion valve (5) can be reduced, and therefore, the accuracy of control by hot gas can be improved as well. The temperature of the outlet air can be controlled using hot gas even when the heat load is small, such as when the temperature is lower than the set temperature. This makes it possible to expand the operating range at a desired set temperature even under high temperatures.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant front W system diagram showing one embodiment of the refrigeration system of the present invention, Fig. 2 is an electric circuit diagram of the refrigeration system shown in Fig. 1, and Fig. 3 is the refrigeration system similarly shown in Fig. 1. 4 is an explanatory diagram showing the temperature difference region, FIG. 5 is a control characteristic diagram of the temperature of the blown air with respect to the outside temperature, and FIG. 6 is a refrigerant piping system diagram showing a conventional example. (1)...Compressor (2), (3)...Condenser (4)...Evaporator (5)...-Temperature-sensitive expansion valve (6c)...Low pressure gas pipe ( 20)...Hot gas bypass path (21)...Hot gas valve (22)...Control passage (51)...Pressure equalization pipe (HP Sl)...Detector (pressure switch) (Hu,
Hz)...'air heater

Claims (1)

[Claims] (1) In a refrigeration system comprising a compressor (1), condensers (2), (3), an evaporator (4), and a temperature-sensitive expansion valve (5) having a pressure equalizing pipe (51), the compressor (1) A hot gas bypass path that bypasses the condensers (2), (3) and the temperature-sensitive expansion valve (5) and leads the hot gas discharged from the evaporator (4) to the evaporator (4). (20), and a hot gas valve (21) is interposed in the hot gas bypass path (20), and the hot gas bypass path (20) on the outlet side of the hot gas valve (21) is connected to the hot gas bypass path (20). Connect with pressure pipe (51),
A control passage (22) is provided to control the opening degree of the expansion valve (5) using hot gas pressure, while an electric heater (Hl) is attached to the evaporator (4), and the outside air temperature or the condenser (2) is A refrigeration system characterized in that a detector (PS) is provided to detect the condensation temperature or high pressure of the electric heater (PS), and the operation of the electric heater (H) is controlled by the operation of the detector (PS). .