JP3490771B2 - Oil level control device for refrigeration equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil level control of a refrigeration system in which a plurality of compressors are connected in parallel by a refrigerant pipe. 2. Description of the Related Art Japanese Unexamined Utility Model Publication No. 53-109847 discloses a conventional technique relating to oil level control of a refrigeration system. A method of supplying an appropriate amount of oil to each compressor via an oil regulator after collecting the oil in a tank is described. Japanese Utility Model Publication No. Sho 56-8876 discloses an oil separated by an oil separator. It describes that the oil level is adjusted by an oil equalizing pipe connecting between the compressors after returning to the respective compressors via return pipes. In the conventional oil level control configured as described above, in the former case, the oil can be uniformly returned to each compressor. Since the parts are relatively large and expensive, there has been a problem that the refrigeration system is large and the manufacturing cost is high. In the latter case, since the oil equalizing pipe is used, if the capacity of each compressor is different, the oil level in each compressor is different due to the pressure difference in each compression period, so that the oil level can be controlled. In some cases, it disappeared. [0005] The present invention provides an oil level control device capable of constantly and stably managing the oil level with respect to such problems. SUMMARY OF THE INVENTION The present invention provides a refrigeration system having a refrigeration cycle in which a plurality of compressors, oil separators, condensers, decompression devices, and evaporators connected in parallel are connected by refrigerant piping. An oil level control device for controlling the oil level of the compressor,
An oil return pipe having an on-off valve and connecting between the oil separator and each of the compressors, provided on each of the compressors;
Float switch that outputs a signal according to the oil level
And the compression according to the signal from the float switch.
And a protection device for controlling the machine.
A float that moves up and down according to the level of the oil
And two on the top and bottom, ON / O according to this float
Providing upper and lower reed switches for FF
The height of the oil level by the upper reed switch
An upper area, the upper and lower reed switches,
Area below and below the lower reed switch
This reed switch is divided into three areas
The oil level above the upper reed switch.
From the area to the area between the upper and lower reed switches
Outputs a first signal to open the on-off valve when
The oil level is the area between the upper and lower reed switches.
From the area below the lower reed switch
At the time of outputting the second signal.
Protection device when the second signal continues for a predetermined time.
The operation of the compressor is stopped and a display signal is output.
It is configured to work . The reed switch is connected to a reed switch having an upper oil level.
From the area above the switch, the upper and lower reed switches
The first signal that opens the on-off valve when the area between
Output and the oil level is equal to the upper and lower reed switches.
Area below the lower reed switch from the area between
Is configured to output a second signal when the
Therefore, the control device of the present invention stops the operation of the corresponding compressor when the second signal continues for a predetermined time and outputs a display signal such as an alarm. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 is a schematic diagram of a refrigeration system. In this figure, a 6 hp fully enclosed scroll compressor 2 and a 10 hp fully enclosed scroll compressor 3, an oil separator 4, a condenser 5, a liquid receiver 6, an expansion valve 7, an evaporator 8 and the accumulator 9 are connected by piping to form a refrigeration cycle. Reference numeral 10 denotes an oil return pipe for connecting the oil separator 4 to each of the compressors 2 and 3, and this oil return pipe is branched from the middle and is connected to each of the branch pipes 10a and 10a which are connected to each of the compressors 2 and 3. 10
b. Numerals 11 and 12 are solenoid valves (open / close valves) attached to the branch pipes 10a and 10b. Reference numerals 13 and 14 are float switches attached to each compressor. Since the float switches 13 and 14 have the same structure, the structure will be described with reference to the float switch 13 shown in FIG. 2 as an example. A tubular support 16 fixed in a container 15 and an insert into the support A float 17 moving up and down, a magnet 18 mounted in the float, a reed switch 19 provided in the support 16, and a lead wire 20 connected to the reed switch and pulled out from the upper part of the support 16. An oil pipe 21 connecting the lower part of the container 15 and the lower part of the compressor 2 and a pressure equalizing pipe 22 connecting the upper part of the container 15 and the compressor 2. A control device 23 is electrically connected to the float switches 13 and 14, and controls the opening and closing operations of the solenoid valves 11 and 12 based on signals from the float switches. The float switch 13 is used when the oil in the container 15 is large, that is, when the oil level is A
If it is above the point, the reed switch (upper) 19-1 is excited, the contact is turned on, an OFF signal is output from the control device 23 to the solenoid valve 11, and the solenoid valve 11 is closed. When the oil gradually decreases and reaches the point A ′, the reed switch (upper) 19-1 is released from the excited state and generates an OFF signal, so that the controller 23 outputs an ON signal to the solenoid valve 11. Then, the solenoid valve 11 is opened. When oil is supplied from the solenoid valve 11 and reaches the point A again, the reed switch (upper side) 19-1 is in an excited state, so that the solenoid valve 11 is similarly closed and the oil supply is stopped. In this way, the oil level becomes AA '
Controlled in between. AA 'indicates the hysteresis of the reed switch. Here, in FIG. 2, the point A is the OF of the solenoid valve 11.
The position of the float 17 indicating the point F, and the point A ′ is the position of the float 17 indicating the ON point of the solenoid valve 11. The same oil level control is performed on the float switch 14. A reed switch (lower side) 19-2 is provided in the float switches 13 and 14, and a reed switch (upper side) is provided.
19-1, the oil is reduced and B
When the point is reached, the reed switch (lower side) 19-2 is excited and an ON signal is output. On the other hand, the control device 23 has a timer function and an alarm device 24, and the float switch 13,
When the ON signal from 14 continues for a predetermined time, the alarm device 24 is activated. That is, when the amount of oil in the compressors 2 and 3 is small, the float 17 descends and the reed switch (lower side) 19-2 is excited by the magnet 18 as shown by the broken line in FIG. Therefore, the timer of the control device 23 operates simultaneously with the ON signal. That is, as shown in the flowchart of FIG. 3, the float switches 13 and 14 are turned on in step N0.
When the point B (the level lower than the hysteresis) is reached, the process proceeds to step N1, and the timer of the control device 23 is activated simultaneously with the input of the ON signal to start counting. Next, the time T counted by the timer in step N2
Determines whether or not a preset time T0 has been reached,
If it has reached, it is considered that the oil circuit is abnormal, and in step N3, a signal is sent to the alarm device 24 to stop the compressor 2 or 3, and at the same time an alarm is sounded. If the count time T of the timer has not reached the set time T0 at step N2, it is determined whether or not the point B 'of the float switches 13 and 14 (the level above the hysteresis) has been reached (whether or not the oil level has increased). ) Is determined in step N4, and if it has not reached the point B ', the process returns to step N1 to start counting by the timer. If it reaches the point B '
In step N5 , the timer is reset. As described above, the float switches 13 and 14
When the oil level inside the compressor reaches a point B and the ON signal from the float switches 13 and 14 continues for a predetermined time, the compressor 2 or 3 is stopped and the alarm device 24 sounds simultaneously. . In this embodiment, the case where the alarm device 24 is provided has been described. However, the present invention is not limited to this. An external output terminal is provided in the control device 23, and an alarm lamp and an alarm display means are connected thereto. You may. In the oil level control device of the refrigeration system configured as described above, the oil level of each of the compressors 2 and 3 is
Float switches 13 and 14 provided for compressors 2 and 3 respectively
As a result, since the oil level of the compressor can be directly detected to control the opening and closing of the solenoid valves 11 and 12,
Even if there is a pressure difference between the compressors 2 and 3, the oil level of each of the compressors 2 and 3 can be independently adjusted to an appropriate amount without being affected by the pressure difference. Further, the oil level control device can be constituted by a simple system in which relatively small and inexpensive float switches 13 and 14 are attached to the compressors 2 and 3, respectively. As a result, relatively large and expensive parts such as an oil tank can be eliminated, the number of parts can be reduced, the size of the apparatus 1 can be promoted, the cost can be reduced, and the compressors 2, 3 can be reduced.
Can be controlled properly even when the fuel cell has different capacities. Further, when the amount of oil in the float switches 13 and 14 decreases and the ON signal of the reed switch 19-2 continues for a predetermined time, the corresponding compressor 2 or 3 is stopped and the alarm device 24 sounds. Therefore, when the amount of oil charged during the cycle of the refrigeration system 1 is small, or when the oil that has flowed out due to oil forming or the like does not return due to stagnation in each device, the compressor is stopped and the compressor due to insufficient lubrication is stopped. Failures can be prevented, and at the same time, an alarm can be immediately recognized for an abnormality in the oil system by an alarm, and prompt measures such as oil replenishment can be taken.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a refrigerant circuit diagram showing an oil level control device of a refrigeration apparatus of the present invention. FIG. 2 is a longitudinal sectional view showing a float switch according to the present invention. FIG. 3 is a flowchart showing the operation of the control device of the present invention. [Description of Signs] 2, 3 Compressor 10 Oil return pipe 11, 12 Solenoid valve 13, 14 Float switch 23 Control device 24 Alarm device

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Tatsuo Asai               2-5-5 Keihanhondori, Moriguchi-shi, Osaka               Sanyo Electric Co., Ltd. (72) Inventor Kenichi Yamagishi               2-5-5 Keihanhondori, Moriguchi-shi, Osaka               Sanyo Electric Co., Ltd.                (56) References JP-A-5-133627 (JP, A)                 JP-A-5-296583 (JP, A)

Claims (1)

(1) A refrigerating apparatus having a refrigerating cycle in which a plurality of compressors, an oil separator, a condenser, a decompression device, and an evaporator connected in parallel by refrigerant piping are provided. An oil level control device for controlling an oil level of the compressor, comprising: an oil return pipe having an on-off valve and connecting between the oil separator and each of the compressors; and an oil level provided in each of the compressors. Trust by height
Signal and the float switch
Protection device for controlling the compressor and the like in accordance with a signal from the
And the float switch is provided with an upper and lower surface of the oil level.
Float that moves up and down according to
Upper and lower resellers that turn ON / OFF according to the float
And the height of the oil level
A region above the upper reed switch;
An area between the upper and lower reed switches;
3 areas with the area below the lower reed switch
Area, and place the reed switch on the
From the area above the reed switch
When the area between the reed switch and the on-off valve
To output a first signal that the oil level is above and below this
From the area between the reed switch and the lower reed switch.
Outputs the second signal when the area is below the switch
And the protection device is connected to the second signal.
Operation of the compressor corresponding to when the signal has continued for a predetermined time.
Stop and output the display signal
Oil level control device of the refrigerator, wherein the door.