JPH0418149B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a refrigeration system, and is particularly applicable to a refrigeration system that performs hydraulic protection by detecting the hydraulic pressure of a compressor that incorporates a pump that supplies lubricating oil to bearings, etc. The present invention relates to a control device for a refrigeration system.

As mentioned above, some conventional compressors used in refrigerators have a built-in pump that supplies lubricating oil to the bearings, etc., for the purpose of lubricating the bearings. In this case, if the pressure for supplying lubricating oil (hereinafter referred to as "hydraulic pressure") drops below a certain value, there is a risk that the lubricating effect that is the purpose of the lubricating oil will not be achieved sufficiently, and in extreme cases, the bearing part may be damaged. This may lead to burnout. For this reason, a hydraulic protection switch is provided to stop the compressor when the oil pressure drops and prevent the bearing from burning out. This switch is configured to issue a command to stop the compressor when the oil pressure falls below a predetermined value for a predetermined period of time or more. FIG. 1 shows an example of a hydraulic protection device in a conventional refrigerator control device.
When the power supply 10 is applied to the compressor 1, the control device 5 starts operating, and the refrigeration operation instruction device 6 normally issues an operation command to the compressor 1. The high temperature and high pressure refrigerant gas compressed by the compressor 1 is transferred to the condenser 2.
It radiates heat, condenses and liquefies, and reaches the expansion device 3. The depressurized refrigerant enters the evaporator 4, absorbs heat from the surroundings, evaporates and vaporizes, and returns to the compressor 1, completing the refrigeration cycle. Here, the oil pressure generated by the operation of the compressor 1 is detected by the oil pressure detection device 8.
is detected and transmitted to the oil pressure abnormality determination device 7, and it is determined whether the abnormal condition matches the abnormal condition set in the oil pressure abnormality condition setting device 11, for example, whether or not operation with oil pressure below a predetermined value has been continued for a predetermined time. , determine whether there is any abnormality in the hydraulic pressure. If it is determined that the refrigeration operation is normal, the refrigeration operation instruction device 6 does not issue a stop command to the refrigeration machine, and the operation continues as it is. On the other hand, if it is determined to be abnormal,
The refrigeration operation instruction device 6 issues a command to stop the operation of the refrigerator, and the compressor 1 stops its operation.

FIG. 2 shows an example of an internal wiring diagram of a hydraulic protection switch, in which terminals 12 and 13 are connected to a circuit that drives a compressor, and terminals 14 and 15 are connected to a power source. The contact 18 is a contact that opens when the oil pressure is high, and closes when the oil pressure is low, energizing the heater 17. When this low oil pressure state continues and a predetermined period of time has elapsed, the contact 16 is opened by the heat of the heater 17, and when the contact 16 is opened, the circuit that drives the compressor is cut off and the compressor is stopped. If the oil pressure rises above a predetermined value before the contact 16 opens, the contact 18 will open, so the supply to the heater 17 will normally be stopped, the contact 16 will not open, and the compressor will not operate. will continue.

In the case of the above-mentioned hydraulic protection device, it is customary to investigate the cause of the oil pressure drop and eliminate the cause, and then wait for the temperature of the lubricated parts to drop sufficiently before restarting the refrigerator. A manual reset switch 6 is provided, and refrigeration operation is restarted by turning on this reset switch 9.

However, refrigeration equipment is not always monitored, and the activation of the protection device is often left unnoticed. There is a risk of serious consequences, such as problems such as thawing of frozen products. On the other hand, if automatic recovery is performed immediately after the protection device is activated or within the cooling time of the heater 17 shown in FIG. The disadvantage is that it becomes something that cannot fulfill its role.

Furthermore, the cause of the activation of the hydraulic protection device is not necessarily limited to insufficient hydraulic pressure, but also, for example, when the compressor
Even though a drive command is issued to the compressor 1, the compressor 1 itself stops and no oil pressure is generated because the compressor motor protection device, such as the motor protector, is activated. Since the device may operate, even if this motor protector is designed to automatically return, it is of no use; in other words, even if the motor protector is intended to return automatically, it cannot be realized.

The present invention has been proposed in view of the above-mentioned circumstances, and its purpose is to provide a control device for a refrigeration system that can eliminate the above-mentioned conventional drawbacks and enable maintenance-free operation.

A control device for a refrigeration device according to the present invention is a control device for a refrigeration device that issues a stop command to the compressor when the hydraulic pressure of the compressor continues to be lower than a predetermined value for a predetermined time or more. The stop command to the compressor is released after a predetermined time period corresponding to the number of times the stop command to the compressor has been issued, and the reset for the operation of the hydraulic protection device is This is done automatically when the lubricating part is sufficiently cooled, thereby solving the above-mentioned drawbacks of the prior art and making it easier to put it into practical use.

An embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 4 is a flowchart showing the operation of the embodiment shown in FIG.

Regarding FIG. 3, the same parts as those shown in FIG. 1 will be described with the same reference numerals. In the embodiment of the present invention shown in FIG. 3, components that do not affect the present invention, such as a dryer in the refrigerant circuit and a temperature control device in the control circuit, are omitted.

1 is a compressor, 2 is a condenser, 3 is a throttle device, 4 is an evaporator, 6 is a refrigeration operation instruction device, 7 is a hydraulic abnormality determination device, 8 is a hydraulic pressure detection device, 9 is a reset switch, 10 is a power source, 19 is a hydraulic abnormal condition setting device,
12 is a control device, 21 is a hydraulic abnormal operation frequency counting device, 22 is a timer, 23 is a timer, and 24 is a reset signal generating device.

The operation of the above embodiment of the present invention will be explained.

When the power supply 10 is applied to the control device 20, the control device 20 starts operating, and the refrigeration operation instruction device 6 normally issues an operation command to the compressor 1.
The refrigerant circulates from compressor 1 → condenser 2 → expansion device 3 → evaporator 4 → compressor 1, completing the refrigerant cycle,
During this time, the oil pressure generated by the operation of the compressor 1 is detected by the oil pressure detection device 8 and transmitted to the oil pressure abnormality determination device 7, and whether or not it matches the abnormal condition set in the oil pressure abnormality condition setting device 19. If it is determined to be normal, the operation continues as it is, and if it is determined to be abnormal, the refrigeration operation instruction device 6
issues a stop command and compressor 1 stops as follows:
This is as described in the section "Summary of the conventional method and its drawbacks." Here, the hydraulic abnormality condition setting device 19
The abnormal condition set in 1 is whether operation with oil pressure below a predetermined value has been continued for a predetermined period of time. The time depends on the number of operations, and when the number of operations is zero, it is a preset time.

If the oil pressure abnormality determining device 7 determines that the hydraulic pressure is abnormal, the compressor 1 is sent to the refrigeration operation instruction device 6.
At the same time, the count of the hydraulic abnormal operation count device 21 is incremented by 1, and in this case becomes "1", and the reset signal generator 24 is set to receive the reset signal. At the same time, timers 22 and 23 start counting. The timer 22 counts a sufficient amount of time to cool the lubricated part according to the number of abnormal oil pressure operations counted by the abnormal oil pressure operation number counting device 21 . For example, when the hydraulic abnormal operation count device 21 counts "1", the timer 22 counts 30 minutes, and if it counts "2", the timer 22 counts 60 minutes.
Count the minutes. The timer 23 is
This is a delay timer for resetting by the reset switch 9, and is a short time of about 150 seconds. When the timer 22 times up when the reset switch 9 is not turned on, the reset signal generator 24 issues a reset signal, the oil pressure abnormality determination means 7 returns to normal, and the refrigeration operation instruction device 6
The compressor 1 is instructed to cancel the stop command to the compressor 1. The oil pressure generated as a result of driving the compressor 1 due to this return to normality is detected by the oil pressure detection device 8 and transmitted to the oil pressure abnormality determination device 7, which is set in the oil pressure abnormality condition setting device 19. Abnormal conditions according to the number of hydraulic abnormal operation operations counted in 21 (denoted as N below), for example, operation with hydraulic pressure below a predetermined value, for a preset time divided by (N + 1). In other words, if the abnormal hydraulic pressure has already stopped once, whether the abnormal hydraulic pressure has continued or not is determined based on whether it has continued for half the preset time. It will continue to operate, and if there is an abnormality, it will stop operating again. If the reset switch 9 is turned on before the timer 22 times up while the compressor 1 is operating and then stopped due to a hydraulic abnormality, the count value in the hydraulic abnormality operation count device 21 will be After being cleared to zero, the reset signal generator 24 receives the input from the reset switch 9, and if the timer 23 has timed up, it immediately sends a reset signal, or if the timer 23 has not timed up, it waits for the timer to time up and then sends a reset signal to the hydraulic abnormality determination means 7. It will be released. In addition, once the oil pressure is abnormal and the machine is stopped, it is restarted due to time-up of the timer 22, and the normal operation is continued for a predetermined period without the oil pressure abnormality.
For example, when the regularly performed defrosting operation is repeated several times, when the compressor 1 is started and stopped several times to maintain temperature, or when a predetermined period of time has elapsed, the hydraulic Abnormal operation number counting device 21
The count value at is cleared to zero. The above operation is shown in a flowchart as shown in Fig. 4.

As described above, according to the present invention, even if the hydraulic protection device is activated, it will automatically return to normal unless the failure is due to an abnormality in the hydraulic circuit, so it will not remain stopped and the quality of the product will be maintained. It becomes effective. This is, for example, compressor 1
Even when an operation command is issued for the compressor 1, the motor is stopped to protect the motor for compressor 1, and the oil pressure may suddenly become abnormal due to an abnormality in oil pressure, or due to a temporary tilt of the refrigeration equipment itself. This enables automatic recovery in such situations.

Further, according to the present invention, from the operation of the hydraulic protection device,
By setting the time until automatic return to allow enough time for lubricated parts such as bearings to cool down, the system can be restarted from the state it was in before it was deemed to be a hydraulic abnormality, almost immediately after the power was turned on. Even if some kind of abnormality actually occurs in the hydraulic system, such as a lack of oil, the risk of damage to the compressor 1 will be the same as during the initial operation, and the function as a protection device will not be impaired.

Furthermore, according to the present invention, the operating conditions of the protective device and the time until restart are adjusted according to the number of times the protective device is activated, thereby shortening the time until the protective device is activated.
By lengthening the time until recovery, the function as a conventional protection device can be maintained.

Furthermore, according to the present invention, after restarting, the hydraulic circuit is determined to be normal, and when this continues for a certain period of time, it recovers to the state before the protective device was activated. This provides excellent effects such as being able to return the protective device operating conditions to their original state.

In the above-mentioned embodiment of the present invention, there is no limit to the number of times the protection device is activated that is counted by the hydraulic abnormality operation number counting device 21, but a maximum value is set thereto so that automatic recovery does not occur after this value is reached. It is also possible to do so.

Further, in the embodiment described above, the timer 23 is provided and the reset switch 9 is not reset until a predetermined delay time has elapsed, but the predetermined time may be zero, that is, the timer 23 may not be provided.

Further, in the above embodiment, a hydraulic abnormality operation frequency counting device 21 is provided, but this is not necessarily necessary, and for example, the predetermined time until the protection device is activated and the predetermined time until recovery can be made constant.

Furthermore, in the above-mentioned embodiment, a function is provided to clear the count of the hydraulic abnormality operation count device 21 to zero, but this is not necessarily necessary.
It may be cleared to zero only when the power is removed. Conversely, counting may be continued during the life cycle of the refrigeration device.

Furthermore, in the present invention, the predetermined time until activation of the protective device and the predetermined time until recovery may be set in any manner depending on the number of abnormal hydraulic pressure operations, and it goes without saying that the predetermined time may be changed every time the count increases by one.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of a conventional example;
3 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 4 is a flowchart showing the operation of the embodiment shown in FIG. 3. 19... Hydraulic abnormality condition setting device, 20... Control device, 21... Hydraulic abnormal operation number counting device, 22, 2
3...Timer, 24...Reset signal generator.

Claims (1)

[Claims] 1. In a refrigeration equipment control device that issues a stop command to the compressor when the hydraulic pressure of the compressor continues to be lower than a predetermined value for a predetermined time or more, after the stop command to the compressor is issued, the compressor A control device for a refrigeration system, characterized in that the stop command for the compressor is canceled after a predetermined time period corresponding to the number of times the stop command has been issued for the compressor.