JPH0160848B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention supplies compressed gas from one compressor to multiple evaporators (or condensers) to cool (or heat) multiple loads, respectively. The present invention relates to a device for controlling cooling (or heating) of a cooling (or heating) device configured to perform cooling (or heating).

[Prior Art] Generally, there is a cooling system as shown in FIG. 1 in which a plurality of evaporators provided in a plurality of refrigerators are operated in parallel by one compressor. In Figure 1, 1,
Reference numerals 2, 3, and 4 are evaporators provided in different freezing or refrigerating cases. The high temperature, high pressure gaseous refrigerant discharged from the compressor 5 is led to a condenser 6 and liquefied. The liquid refrigerant that has passed through the condenser 6 passes through the liquid pipe 8 to the evaporators 1, 2, 3, 4.
Four solenoid valves SV ₁ , SV ₂ , SV ₃ ,
Branch input to SV ₄ . 4 solenoid valves SV ₁ ~ _{SV 4}
Each refrigerant passing through the evaporators 1, 2, 3, and 4 is led to the corresponding evaporator 1, 2, 3, and 4 after being reduced in pressure by the expansion valve 7, respectively. In the evaporators 1, 2, 3, and 4, the refrigerant evaporates and removes heat from the surroundings, thereby cooling the interior of each case. The refrigerants that have passed through the evaporators 1, 2, 3, and 4 are led to the suction side of the compressor 5 through a common suction pipe 9. When the electromagnetic valves SV ₁ , SV ₂ , SV ₃ , and SV ₄ are energized, they open to allow refrigerant to pass through.

Conventionally, there are the following devices for controlling the solenoid valves SV ₁ , SV ₂ , SV ₃ , and SV ₄ in a cooling device capable of forming such a refrigerant circulation route. That is, a thermostat is provided in each of the show cases to perform the following temperature control. When the interior of a given case is sufficiently cooled, a thermostat contact opens, de-energizing the corresponding solenoid valve, stopping refrigerant from flowing into the evaporator, and raising the temperature. Once the temperature is high enough, the thermostat contacts close, allowing refrigerant to flow through the corresponding solenoid valve to cool the system again. In such a control circuit, the four solenoid valves are not related to each other and are independently controlled by their corresponding thermostat contacts.

[Problems to be Solved by the Invention] Therefore, in the conventional control device, the load of the cooling device is distributed, resulting in low load and low efficiency operation.

An object of the present invention is to provide a control device that synchronizes the opening and closing timing of each of the above-mentioned solenoid valves as much as possible, thereby preventing the load from being distributed and resulting in low load and low efficiency operation, and concentrating the load. The aim is to achieve high-load, high-efficiency operation and save energy.

[Means for Solving the Problems] According to the present invention, compressed gas is supplied from one compressor to a plurality of evaporators (or condensers) to cool (or heat) a plurality of loads, respectively. In a control device for a cooling (or heating) device, a plurality of solenoid valves are inserted and connected to the input sides of the plurality of evaporators (or condensers), and a plurality of solenoid valves are installed in each of the plurality of loads, and the temperature of each load is controlled. When the temperature drops below the lower limit of the predetermined temperature (or rises above the upper limit of the predetermined temperature), the first
a plurality of thermostats that enter a second state when the temperature rises above the upper limit of the predetermined temperature (or falls below the lower limit of the predetermined temperature); and the plurality of thermostats; multiple solenoid valves,
and detecting a point in time when any one of the plurality of thermostats enters the first state while the compressor is activated, and detecting the point in time. and a control circuit that closes all of the solenoid valves and stops the compressor after a first predetermined time has elapsed from The time selected is shorter than the time required for the predetermined temperature to rise from the lower limit to the upper limit (or to fall from the upper limit to the lower limit) when the supply of compressed gas is stopped. The control circuit further opens all the electromagnetic valves and restarts the compressor after a second predetermined time has elapsed since the compressor was stopped; A control device is obtained in which the second predetermined time is selected to be shorter than the required time.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows the control device on which the present invention is based. This control device controls the opening and closing of four electromagnetic valves SV ₁ , SV ₂ , SV ₃ , and SV ₄ shown in FIG. In the figure, TH ₁ , TH ₂ , TH ₃ ,
TH ₄ is a contact point of a thermostat installed in a show case equipped with evaporators 1, 2, 3, and 4, respectively. A thermostat opens a contact when the temperature inside the refrigerator drops below a predetermined lower limit (thermostat off value), and closes when the temperature inside the refrigerator rises above a predetermined upper limit (thermostat on value). It is. Initially, if the temperature inside the case is high, the thermostat contact
TH ₁ , TH ₂ , TH ₃ , and TH ₄ are all closed.
Therefore, relays RL ₁ , RL ₂ , RL ₃ , RL ₄ are all energized and operational, and their normally closed contacts RL ₁ , RL ₂ , RL ₃ , RL ₄ are all open, so
Delay relay (i.e. timer) TM ₁ is not activated. Contact tm ₁ of delay relay TM ₁ is therefore closed. The contact tm ₁ is a normally closed contact that opens after a predetermined time (ie, a first predetermined time) when the delay relay TM ₁ is activated. At this time, the solenoid valves SV ₁ to SV ₄ are energized by the power supply 10 through the thermostat contacts TH ₁ to _{TH 4} and the normally closed contact tm ₁ , so all the solenoid valves are open.

Next, when the interior of one show case (for example, a show case equipped with evaporator ₁ ) is sufficiently cooled, thermostat contact TH 1 of thermostat contacts TH ₁ to TH ₄ opens, so that the solenoid valve Solenoid valve SV ₁ of SV ₁ to _{SV 4} is closed to stop the flow of refrigerant. At the same time, relay RL ₁ of relays RL ₁ to RL ₄ becomes inactive, its normally closed contact rl ₁ closes, and delay relay TM ₁ becomes active. Other loads (show case) during activation of delay relay TM ₁
are cooled and the thermostat contacts TH ₂ , TH ₃ ,
Alternatively, even if TH ₄ is opened, the corresponding solenoid valve SV ₂ , SV ₃ or SV ₄ is closed and the corresponding relay RL ₂ , RL ₃ or RL ₄ is only deactivated and the timer or delay relay There is no effect on the operation of TM ₁ .

When the set time of the delay relay or timer TM ₁ has elapsed, its normally closed contact tm ₁ opens to cut off the power to all the solenoid valves SV ₁ to _{SV 4} . Therefore, as the refrigerant stops flowing, the internal temperature of all the cases rises, causing the thermostat contacts to close.
TH ₁ to TH ₄ close one after another. However, since the normally closed contact tm ₁ of the delay relay TM ₁ remains open, the solenoid valves SV ₁ to _{SV 4} are not energized. At this time,
Thermostat contacts in the case that have not cooled down to the thermostat off value remain closed.

When all thermostat contacts TH ₁ to TH ₄ close, all relays RL ₁ to RL ₄ operate and all normally closed contacts RL ₁ to RL ₄ open, so delay relay TM ₁
is de-energized, the normally open contact tm ₁ is closed, and the solenoid valve
SV ₁ to _{SV 4} are energized again. In this way, we return to the starting state.

If all thermostat contacts TM ₁ to _{TM 4} open while delay relay TM ₁ is operating, delay relay TM ₁ continues to operate, but contacts TM ₁ open while the temperature inside the show case increases. In either case, the solenoid valves SV ₁ to _{SV 4} are not energized, so the same thing happens. Even if all thermostat contacts TH ₁ to TH 4 open during activation of delay relay TM ₁ , and all thermostat contacts TH ₁ to _{TH 4 close} due to subsequent rise in temperature in the show case, the delay will not occur. The power to relay TM ₁ is cut off and it returns to its initial state.

On the other hand, the normally open contact RL ₅ of the compressor relay RL ₅ is inserted and connected to the power supply circuit 11 of the compressor 5, and when the relay RL ₅ operates, the compressor 5 rotates, and when the relay RL ₅ becomes inactive, the compressor 5 will stop. Compressor relay RL ₅ is the normally open contact rl′ ₁ of relays RL ₁ to _{RL 4} .
Since it is sandwiched between the parallel circuit of ~rl′ ₄ and the contact tm ₁ of delay relay TM ₁ , it operates only when one or more of the solenoid valves SV ₁ to _{SV 4} is open, and the compressor Turn 5.

Figure 3 shows the temperature change inside the show case using this control circuit. In this example, there are two cases of loads, but the same applies even if there are more cases. First, the internal temperature of case 1 (solid curve) drops sufficiently and thermostat TH ₁ turns off.
As a result, the temperature inside the storage case 1 (solid line curve) starts to rise, but the inside temperature of the storage case 2 (broken line curve) continues to decrease. When the thermostat TH ₁ of the case 1 is turned off and the set time t ₁ of the delay relay TM ₁ has elapsed, cooling of the case 2 is also stopped. However, at this time, the temperature inside the case 2 has not fallen to the thermostat off value, so the thermostat contact
TH ₂ remains closed. The temperature of both cases 1 and 2 increases and when the temperature of case 1 reaches the thermostat on value, the thermostat contact TH ₁ closes. At this time, the thermostat contact TH ₂ of the case 2 remains closed, so the delay relay TM ₁ is disconnected from the power supply 10, and the temperature of the cases 1 and 2 begins to drop (see Figure 3). Since the temperature of the case 2 was lower than that of the case 1, the temperature of the case 2 reached the thermostat off value earlier than that of the case 1, and the thermostat TH ₂ was opened to stop cooling. From this point on, delay relay TM ₁ starts working, but the set time t ₁
If the temperature of the case 1 reaches the thermostat off value within a short period of time, the thermostat TH1 of the case ₁ will also open, and the thermostat contacts of both cases 1 and 2 will be open. Since case 2 turned off earlier, the temperature rose faster and reached the thermostat on value first. However, delay relay TM ₁ will not open unless all thermostats are turned on, so
The case 2 is not cooled. The temperature of the case 1 gradually rises and when the thermostat reaches the ON value, the delay relay _TM1 is also opened, and the temperature of both the cases 1 and 2 begins to decrease. (3rd
(See figure) Thereafter, the temperature changes in the same way, and the cases 1 and 2 are cooled at almost the same time.

Next, a control device according to an embodiment of the present invention shown in FIG. 4 will be explained. In the case of FIG. 2, when the temperature rises, the thermostat waits until all the thermostats are closed, but in the case of this embodiment, the thermostats are turned off after a certain period of time. In FIG. 4, the portion designated by 100 is the same as the portion designated by 100 in FIG. Also, tm′ ₁ is a delay relay (i.e. timer)
TM ₁ is a normally open contact that is activated and closes after a first predetermined time t ₁ . When the set time t ₁ of the delay relay TM ₁ has elapsed, the normally open contact tm′ ₁ closes and the other delay relay (ie timer) TM ₂ and the relay RL ₆ are energized. The contact _tm2 is activated for a second predetermined time _t2 after the delay relay _TM2 is energized.
It is a normally closed contact that opens later. Since relay RL ₆ is energized, its normally closed contact RL ₆ opens and solenoid valve SV ₁ ~
Power to SV ₄ is cut off. Delay relay at the same time
TM ₂ has started to operate and will maintain the current state until the set time t ₂ has elapsed. After t ₂ , delay relay
Normally closed contact tm ₂ of TM ₂ opens, de-energizing delay relay TM ₂ and relay RL ₆ , normally closed contact rl ₆ closes, solenoid valves SV ₁ to _{SV 4} open thermostat contact TH ₁
~TH When ₄ is closed, it becomes open.

If all thermostats are turned off during the elapse of the timer TM ₁ set time t ₁ , then
After the elapse of time t ₁ , further setting time t ₂ of timer TM ₂
It may not be possible to cool down for a very long time. Therefore, when all thermostats are turned off, all normally closed contacts RL _{'' 1} to RL'_{' 4 of} relays RL ₁ to RL ₄ are closed, so that delay relay TM ₂ and relay RL ₆ are turned off regardless of delay relay TM 1. Turn on electricity, and prevent cooling from that point until after t ₂ has elapsed. The normally open contact rl′ ₆ of relay RL ₆ is for self-holding; without this contact rl′ ₆ ,
When one of the thermostats turns on, the delay relay TM ₂ is opened, the relay RL ₆ becomes inactive, and the solenoid valve SV ₁ ~ via the normally closed contact RL ₆ is opened.
It becomes possible to energize SV ₄ .

FIG. 5 shows the temperature change inside the show case using this embodiment. First, the temperature inside the case 1 (solid curve) drops to the thermostat off value. By the time t ₁ has elapsed, the internal temperature of case 2 (dashed curve) has not fallen to the thermostat off value, and even after time t ₁ has elapsed, the thermostat of case 2 remains on. It remains as it is. After time t ₁ has elapsed, cooling is stopped for time t ₂ . After time _t2 , since the thermostat of case 1 has been turned on and the thermostat of case 2 has remained on, both cases 1 and 2 begin to cool down. (See Figure 5) Next, during the lapse of time t ₁ , cases 1 and 2
When both have cooled down to the thermostat off value, cooling is stopped for a time t ₂ from that point on. (5th
(See figure) Thereafter, the temperature changes in a similar manner, and the cases 1 and 2 are cooled at approximately the same time.

The embodiment shown in Fig. 4 takes more time to adjust than the case shown in Fig. 2 because the number of delay relays (timers) is increased by one, but compared to the case shown in Fig. 2, the following There are merits.

That is, in the case of FIG. 2, the compressor is stopped and then restarted after a short stop period as shown in E of FIG. 3 (this is called a compressor short cycle). ), which is unfavorable in terms of compressor durability. However, in the case of FIG. 4, the second set time t2 can be selected in advance to be longer than the minimum stop time that does not impair the durability of the compressor. It is possible to prevent restarting after such a short stop time E.

The features of this embodiment will be explained with reference to FIGS. 4 and 5. Relays RL ₁ to _{RL 4} (shown in Figure 2)
, their normally closed contacts rl ₁ to rl ₄ , their normally open contacts rl′ ₁ to rl′ ₄ (shown in FIG. 2), a delay relay (i.e. timer) TM ₁ and its contacts tm′ ₁ and,
Relay RL ₅ (shown in Figure 2) and its normally open contact rl ₅
(shown in Figure 2), relay RL ₆ , and its contact rl ₆
, delay relay (timer) TM ₂ , and its contacts
tm ₂ includes multiple thermostat contacts TH ₁ to TH ₄ (shown in Figure 2), multiple solenoid valves SV ₁
~SV ₄ (shown in Figure 2), and compressor power supply circuit 1
1 (shown in FIG. 2), detects the point in time when the contact point of any one of the plurality of thermostats becomes closed while the compressor is activated, and After the first predetermined time t ₁ has elapsed since the detection, all solenoid valves SV ₁ ~
It acts as a control circuit that closes SV ₄ and stops the compressor.

As is clear from FIG. 5, the first predetermined time _t1 is a state in which the supply of compressed gas from the compressor is stopped to each of the plurality of refrigeration or refrigerated cases (i.e., loads). The time is selected to be shorter than the time required for the thermostat to rise from the thermostat OFF value to the thermostat ON value shown in FIG.

The control circuit further opens all the solenoid valves SV ₁ to _{SV 4} and restarts the compressor after a second predetermined time t ₂ has elapsed since the compressor was stopped. let

As is clear from FIG. 5, this second predetermined time t ₂ also occurs when the supply of compressed gas from the compressor to each of the plurality of refrigeration or refrigerating cases is stopped, as is clear from FIG. The time is selected to be shorter than the time required to rise from the thermo-OFF value to the thermo-ON value.

In a cooling device that forms a refrigeration circulation cycle, even if the load is halved, the power consumption is not halved.
It will be around 60-70%. The compressor is selected according to the maximum load, so it has surplus capacity during normal times, and is kept at a constant temperature by repeatedly turning it on and off using a thermostat. Since the compressor is at its maximum efficiency when it is at maximum load, it becomes less efficient when the compressor is turned on and off repeatedly by the thermostat. In the conventional example shown in Fig. 6, solenoid valves SV ₁ and SV ₂ open and close independently, so
Half load (one of the cases is not cooled,
In many cases, only one case is cooled. However, when the systems are operated synchronously as shown in FIGS. 3 and 5, both cases are often cooled. Therefore, what was conventionally a low-load operation becomes a high-load operation due to the temporal concentration of the load according to the present invention.

FIG. 7 is an example of forced intermittent operation, which is one means of achieving energy savings. This is a method in which the device is kept in operation for a certain period of time (operation is stopped when the thermostat is turned off) and then forced to stop for a certain period of time. If the operating time and stop time are appropriately set, a certain degree of synchronous operation will be achieved as shown in FIG. 7, and energy savings will be achieved.
However, the biggest problem is that the thermostat is useless during a forced stop.

First, at maximum load, the compressor operates at full capacity to maintain a certain temperature, but if the compressor stops at that time, the temperature rises. In the present invention, the operation does not stop until the thermostat off value is reached, so the above problem does not occur.

Next, when the load is slightly high, if the forced stop time is long, the temperature will rise in the same way. In the case of Figure 2, which is the basis of the present invention, it takes time for the temperature to drop and it takes a short time for the temperature to rise.
Run for a relatively long time and stop for a relatively short time. In the present invention (FIG. 4), the stop time is fixed, but the operating time is similarly long.

In the case of extremely light loads, if the stop time is less than necessary during forced intermittent operation, the temperature will not rise sufficiently during that time and synchronous operation will not occur. In the case of FIG. 2, which is the basis of the present invention, the temperature decreases for a short period of time, so the operation is performed for a short period of time, and the temperature increases for a long period of time, so the operation is stopped for a long period of time. Even in the case of FIG. 4 of the present invention, the operating time is shortened.

In this way, in forced intermittent operation, the operating time setting must be changed depending on the load. For example, it must be changed depending on the season or time of day. However, in the present invention, the operating time can be adjusted to match any load fluctuations, and the energy saving effect can be increased through synchronous operation without the need for adjustment.

In addition, in FIG. 2, malfunction may occur depending on how the electrical resistances of the relays RL ₁ to RL ₄ and the electrical resistances of the solenoid valves SV ₁ to _{SV 4} are selected. For example, if contact tm ₁ is open and only thermostat contact TH ₁ is closed, only relay RL ₁ should operate, but other relays may also operate. In other words, a circuit (that is, a current loop circuit) is formed in which a current flows through the thermostat contact _TH1 , the solenoid valve _SV1 , the solenoid valve _SV2 , and the relay _RL2 . At this time, if the electrical resistance of the solenoid valves SV ₁ and SV ₂ is large, the voltage applied to the relay RL ₂ will be lower than the operating voltage of the relay RL ₂ , and the relay RL ₂ will not operate. However, as the electrical resistance of solenoid valves SV ₁ and SV ₂ decreases, the voltage applied to relay RV ₂ increases and eventually reaches the operating voltage. In order to operate relays RL ₁ to RL ₄ accurately without malfunction under any conditions, it is necessary to do as shown in FIG. 8. In Figure 8, relay RL ₇ is a timer
Activated by contact tm ₁ of TM ₁ . The normally open contact rl ₇ of relay RL ₇ closes when relay RL ₇ is activated, so when contact tm ₁ closes, rl ₇ also closes. Therefore, in the same way as when the contact tm ₁ in FIG. 2 is opened, when the contact tm ₁ opens, the relay contact rl ₇ opens, and the energization to the electromagnetic valves SV ₁ to _{SV 4} and the relay RL ₅ is cut off. In the circuit shown in FIG. 8, the current loop circuit described above is not formed.

FIG. 9 shows an embodiment in which the present invention is applied to the circuit shown in FIG. 8. In FIG. 9, the portion designated by 100' is the same as the portion designated by 100' in FIG. In FIG. 9, a normally closed contact rl ₆ of a relay RL ₆ is connected in place of the contact tm ₁ in FIG. 8. The circuit of FIG. 9 also operates essentially the same as the embodiment of FIG.

The control device of the present invention can be used in a cooling device in which a compressor and a condenser are combined into one unit and a plurality of evaporators are connected, such as a refrigerator, a refrigerator, a room cooler for cooling multiple rooms, and the like.

Furthermore, the control device of the present invention is of a heat pump type that releases heat, and the compressor and evaporator are combined into one unit, and can be used in a heating device in which a plurality of condensers are connected, such as a multi-room heating device. . In this case, contrary to the above embodiment, the thermostat is turned off when the temperature rises above the upper limit of a predetermined temperature and turned on when the temperature falls below the lower limit of the predetermined temperature.

[Effects of the Invention] As explained above, according to the present invention, a control device is obtained in which the opening and closing timings of each of a plurality of solenoid valves are synchronized as much as possible, and the load is distributed to achieve low-load and low-efficiency operation. It is possible to prevent this from happening, concentrate the load, achieve high load, high efficiency operation, and save energy.

[Brief explanation of drawings]

Figure 1 is a refrigerant circulation system diagram of a cooling system in which multiple evaporators installed in multiple refrigerators are operated in parallel by one compressor, and Figure 2 is a circuit diagram of the control device that is the basis of the present invention. , FIG. 3 is a time chart showing control by the control device shown in FIG. 2, FIG. 4 is a circuit diagram of a control device according to an embodiment of the present invention, and FIG. 5 shows control by the control device shown in FIG. Figures 6 and 7 are time charts showing conventional control, Figure 8 is a circuit diagram showing a modification of Figure 2,
FIG. 9 is a circuit diagram of a control device according to another embodiment of the present invention. 1, 2, 3, 4...evaporator, 5...compressor, 6...condenser, 7...expansion valve, 8...liquid pipe, 9...suction pipe, 10
…Power supply, 11…Compressor power supply circuit, SV ₁ to SV ₄ …Solenoid valve, TH ₁ to _{TH 4} …Thermostat contact, RL ₁ to
RL ₅ ...Relay, rl ₁ to rl ₅ ...Normally closed contact of relay RL ₁ to RL ₅ , rl' to rl' ₅ , rl ₅ ...Normally open contact of relay RL ₁ to RL ₅ , rl'' ₁ to rl'' ₄ …Normally closed contacts of relays RL ₁ to RL ₄ ,
TM ₁ …Timer (delay relay), tm ₁ and tm′ ₁
…contact of timer TM ₁ , TM ₂ …timer (delay relay), tm ₂ …contact of timer TM ₂ , RL ₆ …relay, rl ₆ …normally closed contact of relay RL ₆ , rl′ ₆ …relay
Normally open contact of RL ₆ , RL ₇ … relay, RL ₇ … relay RL ₇
Normally open contact.

Claims (1)

[Claims] 1. A plurality of solenoid valves are inserted and connected between one compressor and a plurality of evaporators (or condensers) that respectively cool (or heat) a plurality of loads, and When the temperature of each load falls below the lower limit of the predetermined temperature (or rises above the upper limit of the predetermined temperature), the plurality of loads mentioned above become in the first state, and conversely, when the temperature of each load falls below the lower limit of the predetermined temperature. A plurality of thermostats are provided that enter a second state when the temperature rises (or when the temperature falls below the lower limit of the predetermined temperature), and the corresponding solenoid valves are controlled to open and close according to the state of the plurality of thermostats. , in a control device for a cooling (or heating) device equipped with a drive circuit that controls starting and stopping of the compressor, detecting a point in time when any one of the plurality of thermostats enters the first state; , a control circuit is provided that stops the drive circuit, closes all the electromagnetic valves, and stops the compressor after a first predetermined time has elapsed since detecting the time, The time is defined as the time for each load to rise from the lower limit of the predetermined temperature to the upper limit (or to fall from the upper limit to the lower limit of the predetermined temperature) while the supply of compressed gas from the compressor is stopped. ), and the control circuit further operates the drive circuit after a second predetermined time has elapsed since the compressor was stopped; A control device characterized in that the second predetermined time is selected to be shorter than the required time.