JPH06341720A - Refrigerator - Google Patents

Abstract

PURPOSE:To prevent generation of foaming and to improve performance of an oil pump at a time of starting a refrigerator after it is disused for a long time. CONSTITUTION:At a time of starting an air conditioner after a long disuse, first a normal soft starting operation is carried out. After a finish of the soft starting operation, an upper limit frequency of a compressor 1 is regulated to 60Hz by an upper limit frequency setting means 15a for 5 minutes and 20 seconds, so that generation of foaming in the compressor 1 may be prevented. If a low pressure becomes lower than 1.5kg/cm<2> within 5 minutes after the finish of the soft starting operation, a low pressure raising means 15b opens a hot gas bypass valve 21, so that hot gas may be bypassed to a sunction side to reduce the lowering degree of the low pressure, thus lowering of performance of an oil pump can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus, and more particularly to a measure for improving the reliability of a compressor when the refrigerating apparatus is started after being stopped for a long time.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Publication No. 3-10865.
The refrigerating device provided in the air conditioner as disclosed in Japanese Patent Publication No. JP-A-2003-264, when the operation is started, performs so-called soft start for setting the operation frequency of the compressor to a low value for a predetermined time to return the liquid to the compressor. It is designed to prevent That is, for example, in a refrigeration apparatus including an inverter-controlled compressor, at the time of starting operation, soft start is performed by setting the operating frequency of the compressor to a low value such as 42 Hz for 1 minute after starting. After the soft start, the compressor is normally operated according to the air conditioning load.

[0003]

However, in this type of refrigerator, when the refrigerator is stopped for a long time (for example, several days), the liquid refrigerant in the refrigerant circuit returns to the compressor, A phenomenon called "sleeping" in which the liquid refrigerant dissolves in the lubricating oil may occur inside the compressor. Then, for example, when heating operation is started from a state where such "sleeping" has occurred, this sleeping state cannot be canceled only during the above-described soft start, and the compressor shifts to the normal operation in this state. Will be lost. Then, in normal operation in such a state, with the operating frequency of the compressor rapidly increasing until the high-pressure equivalent saturation temperature reaches a constant value, the occurrence of liquid refrigerant forming in the compressor occurs. As a result, a large amount of lubricating oil flows out to the discharge side, and the sudden drop in low pressure causes a drop in the oil pump's capacity, causing oil to run out in the compressor, and It may worsen and may interfere with the operation of the compressor.

When it is considered to avoid the occurrence of forming and the decrease in oil pump capacity as factors that have an adverse effect on the compressor, in order to suppress the occurrence of forming in the compressor. It is preferable that the operating frequency at start-up is as small as possible. On the other hand, in order to improve the performance of the oil pump, it is preferable to increase the pressure on the low pressure side as much as possible. However, the conventional configuration is not such that these two are compatible with each other, and the reliability at the time of startup cannot be ensured.

The present invention has been made in view of the above points, and suppresses the occurrence of forming at startup and improves the capacity of an oil pump when the refrigerator is stopped for a long period of time. It is an object of the present invention to obtain a configuration capable of avoiding the occurrence of oil shortage in the compressor.

[0006]

In order to achieve the above object, the present invention, after soft start, regulates the frequency of the compressor and bypasses the hot gas according to the stagnation state of the liquid refrigerant in the compressor. I was made to do. Specifically, the invention according to claim 1 is such that, as shown in FIG. 1, the compressor (1) is provided in the refrigerant circuit (14), and the discharge side and the suction side of the compressor (1) are provided. A bypass path (11d) for connecting with and is provided, and the opening / closing valve (21) that can be opened and closed is provided in the bypass path (11d).
On the other hand, a frequency adjusting means (2a) for adjusting the operating frequency of the compressor (1) is provided, and when the compressor (1) is started, the frequency adjusting means (2a) causes It is premised on the refrigeration system in which the operating frequency of the compressor (1) is fixed to the low first starting frequency for a predetermined time. Then, a low pressure detection means (P2) for detecting the pressure on the suction side of the compressor (1), a stop time recognition means (15c) for recognizing the operation stop time of the compressor (1), and the stop time recognition means ( 1
When the operation stop time of the compressor (1) is longer than a predetermined long time by receiving the output of 5c), the operation frequency of the compressor (1) becomes the first
After the end of the above-mentioned predetermined time fixed to the starting frequency, the upper limit frequency of the operating frequency of the compressor (1) is set to the second
Setting the starting frequency, transmitting the upper limit frequency setting signal to the frequency adjusting means (2a), and limiting the operating frequency of the compressor (1) to the second starting frequency or less only during this predetermined time. And means (15a). Further, receiving the output signal of the low pressure detecting means (P2), the suction side pressure of the compressor (1) is set to a predetermined value within a predetermined time when the upper limit frequency of the operating frequency of the compressor (1) is set to the second starting frequency. When the value falls below a certain value, the on-off valve (21) is opened to supply the discharge gas refrigerant of the compressor (1) to the suction side through the bypass passage (11d) to increase the pressure on the suction side. (15b) is provided.

According to a second aspect of the present invention, in the refrigerating apparatus according to the first aspect, the stop time recognizing means (15c) is the operation stop time of the compressor (1) at the first start after the main power is turned on. Is configured to output a signal to the upper limit frequency setting means (15a) by recognizing that the time is longer than a predetermined time.

According to a third aspect of the present invention, in the refrigerating apparatus according to the first or second aspect, the stop time recognizing means (15c) is provided.
When the operation stop time of the compressor (1) is longer than a predetermined long time, the operation frequency of the compressor (1) is fixed to the first starting frequency, and then only a predetermined time The lower limit frequency of the operating frequency of the compressor (1) is set to the third starting frequency lower than the second starting frequency, and the lower limit frequency setting signal is transmitted to the frequency adjusting means (2a), The lower limit frequency setting means (15d) for limiting the operating frequency of the compressor (1) to the third starting frequency or higher is provided only during the period.

[0009]

With the above construction, the present invention provides the following actions. In the invention according to claim 1, the compressor
When the operation stop time in (1) is longer than a predetermined long time, the upper limit frequency setting means (15a) receives the signal from the stop time recognition means (15c), and the upper limit frequency setting means (15a) causes the compressor to operate. After the predetermined time when the operating frequency of (1) is fixed to the first starting frequency, set the upper limit frequency of the operating frequency of the compressor (1) to the second starting frequency for a predetermined time.
The upper limit frequency setting signal is transmitted to the frequency adjusting means (2a), and the operating frequency of the compressor (1) is restricted to the second starting frequency or less only during this predetermined time. As a result, the forming of the liquid refrigerant inside the compressor (1) is suppressed.
Furthermore, in this way, within the predetermined time when the upper limit frequency of the operating frequency of the compressor (1) is set to the second starting frequency,
When the suction side pressure of the compressor (1) falls below a predetermined value, the signal from the low pressure detection means (P2) is sent to the low pressure rise means (15b).
The on-off valve (21) is opened by the low-pressure raising means (15b), and the discharge gas refrigerant of the compressor (1) is bypassed (11).
It is supplied to the suction side via d) and the pressure on the suction side is increased. As a result, it is possible to prevent the oil pump capacity from being lowered due to the decrease in the suction side pressure.

According to the second aspect of the invention, the stop time recognizing means (15c) at the time of the first start-up after turning on the main power source of the device.
Recognizes that the operation stop time of the compressor (1) is longer than a predetermined long time and outputs a signal to the upper limit frequency setting means (15a), as described in the operation of the invention according to claim 1. Activation control is performed.

According to the third aspect of the invention, when the operation stop time of the compressor (1) is longer than a predetermined long time, the signal from the stop time recognizing means (15c) is set to the lower limit frequency setting means (15).
d) is received, and by the lower limit frequency setting means (15d), the operating frequency of the compressor (1) is fixed to the first starting frequency, and after the predetermined time is finished, the operating frequency of the compressor (1) is further decreased by a predetermined time. The lower limit frequency is set to the third starting frequency, the lower limit frequency setting signal is transmitted to the frequency adjusting means (2a), and the operating frequency of the compressor (1) is restricted to the third starting frequency or higher only during this predetermined time. To do. As a result, the reduction in the capacity of the oil pump due to the operating frequency of the compressor (1) being too low is suppressed. That is, at this time, the compressor is set by the upper limit frequency setting means (15a) in the invention according to claim 1.
Since the upper limit frequency of the operating frequency of (1) is set to the second starting frequency, the operating frequency of the compressor (1) is set between the second starting frequency and the third starting frequency.

[0012]

EXAMPLE An example of the present invention will be described below with reference to FIG. FIG. 2 shows a refrigerant piping system of the outdoor unit (A) and the indoor unit (B) of the air conditioner according to the embodiment of the present invention. The units (A) and (B) will be described below. Inside the outdoor unit (A), a compressor (1) whose capacity is adjusted by an inverter (2a) as a frequency adjusting means capable of variably switching the output frequency in the range of 30 to 116 Hz every 4 to 10 Hz. , An oil separator (4) for separating the oil in the gas discharged from the compressor (1), and a four-way switching valve that switches as shown by the solid line in the figure during cooling operation and as shown by the broken line in the figure during heating operation (5) and a condenser during cooling operation,
An outdoor heat exchanger (6) as a heat source side heat exchanger that serves as an evaporator during heating operation and an outdoor fan (6a) attached to the outdoor heat exchanger (6), and perform a refrigerant throttling action during heating operation Outdoor electric expansion valve (8) and receiver for storing liquefied refrigerant
(9) and an accumulator (10) are built in as main equipment, and the respective equipments (1) to (10) are connected by a refrigerant pipe (11) so that the refrigerant can flow.

The indoor unit (B) includes an indoor heat exchanger (12) and its fan (12a) as a utilization side heat exchanger that serves as an evaporator during cooling operation and a condenser during heating operation.
Further, on the liquid pipe side of the indoor heat exchanger (12), an indoor electric expansion valve (13) for adjusting the refrigerant flow rate during the heating operation and performing the throttle action of the refrigerant during the cooling operation is provided. . In this way, each of the above devices is connected by a refrigerant pipe (11) so that the refrigerant can flow, and the main refrigerant circuit that releases the heat obtained by heat exchange with the outdoor air to the indoor air ( 14) is configured.

Further, (11e) is a bypass path for heating overload control that bypasses the outdoor heat exchanger (6), and the bypass path (11e) has the same air as the outdoor heat exchanger (6). Auxiliary heat exchanger (22) installed in the passage, capillary tube (28)
And the solenoid on-off valves (24) that open when the pressure of the refrigerant is high are connected in series and in parallel with the outdoor heat exchanger (6).
At the time of cooling operation at all times, at the time of heating operation at the time of high pressure excessive rise, the solenoid on-off valve (24) is turned on, that is, opened.
A part of the discharged gas is bypassed from the main refrigerant circuit (14) to the heating overload control bypass passage (11e). Then, at this time, a part of the discharged gas is condensed by the auxiliary heat exchanger (22).

Further, (40) is a liquid injection bypass passage for injecting a liquid refrigerant into the suction line during heating / cooling operation to adjust the degree of superheat of the suction gas, and includes a capillary tube (41) and a discharge pipe temperature excess. An electromagnetic valve (42) for injection that is opened when rising is interposed.

Also, (31) cools the suction refrigerant by heat exchange between the suction refrigerant in the suction pipe (11) and the liquid refrigerant in the liquid pipe (11), and the refrigerant overheats in the communication pipe (11b). It is a suction pipe heat exchanger for compensating the increase in temperature.

Further, many sensors are arranged in this device, (Th1) is a room temperature thermostat for detecting the room temperature, and (Th2) and (Th3) are respectively the liquid side of the indoor heat exchanger (12). And an indoor liquid temperature sensor and an indoor gas temperature sensor that detect the temperature of the refrigerant in the gas side pipe, (Th4) is the compressor (1)
A discharge pipe sensor that detects the discharge pipe temperature of (3), (Th5) is a defrost sensor that detects the frosting state from the outlet temperature of the outdoor heat exchanger (6) during heating operation, and (Th6) is the suction pipe heat exchanger (3).
A suction pipe sensor that is arranged in the suction pipe (11) on the downstream side of 1) and detects the suction pipe temperature, and (Th7) is arranged in the air suction port of the outdoor heat exchanger (6) to detect the suction air temperature. Outside temperature sensor, (P1) is installed in the discharge pipe, high pressure sensor that detects the high pressure side pressure of the main refrigerant circuit (14), (P2) is installed in the suction line, low pressure detection that detects the low pressure side pressure It is a low pressure sensor as a means.

In addition to the above-mentioned main devices, various auxiliary devices are provided. (21) is provided in the hot gas bypass passage (11d) connecting the discharge pipe and the suction pipe, and when the compressor (1) is stopped due to a thermo-off state or the like, the compressor is opened for a certain period of time before restarting. The hot gas bypass valve as an opening / closing valve, and (33) is an oil return pipe for returning the lubricating oil from the oil separator (4) to the compressor (1) via the capillary tube (32). Further, in the figure, (HPS) is a high-pressure pressure switch for protecting the compressor.

The above-mentioned motor-operated valves, solenoid valves and sensors are connected to the control unit (15) together with each main device by a signal line, and the control unit (15) receives signals from the sensors and each motor-operated valve. Also, the opening / closing control of the solenoid valve and the capacity control of the compressor are performed.

Further, a pressure equalizing passage (30) is provided between the receiver (9) and the hot gas bypass passage (11d).
One end of this pressure equalizing passage (30) is connected to the upper end surface of the receiver (9), while the other end is the pressure equalizing hot gas bypass passage.
It is connected to the upstream side of the hot gas bypass valve (21) of (11d), and from the receiver (9) to the pressure equalizing hot gas bypass line (1
A check valve (30a) is provided to allow only the flow of refrigerant in the direction toward 1d). With such a configuration, the gas refrigerant in the receiver (9) is protected from the hot gas bypass passage (11d).
As a result, it can be introduced to the suction side of the compressor (1), and the pressure in the entire circuit is equalized. Further, the control unit (15) includes an upper limit frequency setting means (1
5a), low pressure raising means (15b) and stop time recognition means (15c)
Is provided, and the operation control at the time of starting after the air conditioner is stopped for a long time is performed by each of these means. Below, as an example of this startup control, the procedure of startup control during heating startup will be described with reference to the flowchart in FIG. After the heating is started, first, the soft start of the compressor is started in step ST1, and the operation is performed at a fixed frequency of a low frequency (for example, 42 Hz) as the first starting frequency in the present invention for a predetermined time (for example, one minute). Done. Then, in step ST2, it is determined whether or not this software startup is completed.
The above software activation is continued until it is determined in ST2 that the software activation is completed. And this step ST
In the case of NO determined in step 2 that the software startup has ended, the process proceeds to step ST3 and it is determined whether or not the main startup is the first startup after the power is turned on. If YES in step ST3, that is, it is the first startup after the power is turned on, the process proceeds to step ST4.
The upper limit of the operating frequency of (1) is set to 60 Hz as the second starting frequency in the present invention to prohibit the compressor from operating at a frequency exceeding 60 Hz, and the hot gas bypass valve (21) To close. Then, the process proceeds to step ST5, the timer is set in this state, and the process proceeds to step ST6. That is, here, it is recognized that the air conditioner has been suspended for a long time by detecting that it is the first start-up after the power is turned on, and in such a case, the liquid refrigerant in the compressor (1a) is recognized. Since there is a possibility that "sleeping" may have occurred, it is detected that there is a risk of liquid refrigerant forming, and the operating frequency of the compressor (1a) is regulated to 60 Hz or less. It suppresses the occurrence of forming and prevents a large amount of lubricating oil from flowing out to the discharge side. Further, the duration of such control state is set by a timer. As a result, the stop time recognition means (15c) is constituted by the step ST3, and the step ST4
The upper limit frequency setting means (15a) is constituted by.
In this way, after the upper limit frequency of the compressor (1) is regulated and the hot gas bypass valve (21) is closed,
Move to ST6. In this step ST6, it is judged whether or not the low pressure (Lp) detected by the low pressure sensor (P2) has become smaller than 1.5 kg / cm ² , and in this step ST6 the low pressure (Lp) is 1.5 kg / cm2. In case of NO of cm ² or more, the hot gas bypass valve (21) is kept closed, and in case of YES where low pressure (Lp) is less than 1.5 kg / cm ² , step In ST7, hot gas bypass valve (2
1) is opened to bypass a part of the high pressure gas refrigerant discharged from the discharge side of the compressor (1) to the suction side via the hot gas bypass passage (11d) to increase the pressure on the low pressure side. This state is continued until the timer times out in step ST8. In this example,
The time-up time of this timer is set to 5 minutes. That is, here, in order to prevent the capacity of the oil pump from being lowered due to the low pressure on the low pressure side, the discharge pressure is used to prevent the low pressure side from being lowered. Then, when the timer times out in step ST8, the timer is set again in step ST9, and in this state the hot gas bypass valve (21) is returned to the normal control state in step ST10. That is, the hot gas bypass valve (21) is returned to the normal control state while the upper limit frequency of the compressor (1) is regulated to 60 Hz, and step ST
This state is continued until the timer times out at 11. In this example, the time-up time of this timer is set to 20 seconds. When the timer times out in step ST11, the main activation control is released in step ST12, and the normal operation of the compressor (1) according to the air conditioning load is performed. Thus, the low pressure increasing means (15b) is constituted by the step ST7. Even in the case of NO determined in step ST3 that it is not the first startup after the power is turned on, the operation is stopped or the thermostat is turned off in step ST13.
If the state has continued for 8 hours or more, it is possible that the liquid refrigerant has stagnated inside the compressor as in the first startup after the power is turned on. In ST4, the operation frequency of the compressor (1) and the control of the hot gas bypass valve (21) as described above after this step ST4 are similarly performed. That is,
Also in this step ST13, the stop time recognition means (15c)
Is configured. Also, step ST3 and step ST
If both are determined to be NO in 13, the compressor (1)
When it is judged that there is no stagnation in the house, it is possible to switch to normal operation immediately after the software startup is completed.
The above means (15a), so that the above operation is performed,
(15b) and (15c) are constructed.

Next, the operation of the air conditioner constructed as described above will be described. In Fig. 2, during the cooling operation of the air conditioner, the four-way switching valve (5) is switched to the solid line side in the figure, and the electromagnetic opening / closing valve (24) of the auxiliary heat exchanger (22) is always open, so that the compressor ( The refrigerant compressed in 1) is the outdoor heat exchanger.
(6) and auxiliary heat exchanger (22) condensed, connecting pipe (11a)
Sent to the indoor unit (B). In this indoor unit (B), the liquid refrigerant is decompressed by the indoor electric expansion valve (13) and evaporated in the indoor heat exchanger (12), and then the connecting pipe (11
Return to the outdoor unit (A) in the gas state via b)
Circulate so as to be inhaled in (1). That is, the liquid refrigerant cools the indoor air by exchanging heat with the indoor air in the indoor heat exchanger (12) and evaporating.
Also, during heating operation, the four-way switching valve (5) is switched to the side of the broken line in the figure, and the flow of refrigerant is the reverse of that during cooling operation,
The refrigerant compressed in the compressor (1) is condensed in the indoor heat exchanger (12), flows in the liquid state to the outdoor unit (A), is decompressed by the outdoor electric expansion valve (8), and is discharged into the outdoor heat exchanger ( After evaporating in 6), it circulates back to the compressor (1). That is, the gas refrigerant heats the indoor air by exchanging heat with the indoor air in the indoor heat exchanger (12) and condensing. Then, as a characteristic operation of this example, as described in the above-mentioned flowchart, there is operation control at the time of start-up after the air conditioner has been stopped for a long period of time or stopped for 8 hours or more. . This driving operation will be described with reference to the time charts of FIGS. First, when the heating operation is started, as shown in FIG. 4, the soft start operation is performed for a predetermined time (1 minute) at the same time as the heating operation is started. In other words, the operating frequency of the compressor (1) is 42Hz as the first starting frequency.
, And open the hot gas bypass valve (21). Then, the hot gas bypass valve (21) is closed at the same time as the end of the soft start operation, and the upper limit frequency of the compressor (1) is set to the second value.
The start-up frequency is regulated to 60 Hz, and the occurrence of forming of the liquefied liquid refrigerant is suppressed to regulate the outflow of the lubricating oil from the compressor (1). In the state shown in FIG. 4, the operating frequency is 48 Hz at the same time when the software startup is completed. Then, when the low pressure becomes less than 1.5 kg / cm ² in such an operating state (A in FIG. 4).
Position), the hot gas bypass valve (21) is opened again to bypass the discharged gas refrigerant to the low pressure side to raise the low pressure and prevent the oil pump from lowering its capacity. Also in this case, the upper limit frequency of the compressor (1) is regulated to 60 Hz. Furthermore, in this example, the lower limit frequency setting means (15d) provided in the control unit (15) regulates the lower limit frequency of the compressor (1) at this time to 54 Hz as the third starting frequency. As a result, the capacity of the oil pump is fully exerted. The hot gas bypass valve (21) is closed when 5 minutes have passed since the start (position B in FIG. 4), and when 20 seconds have passed thereafter (position C in FIG. 4), the compressor ( The operating frequency regulation in 1) is released and normal operation is resumed. In other words, the operating frequency of the compressor (1) is 6 until 5 minutes and 20 seconds have passed since the startup.
It is designed not to exceed 0Hz. In addition, the closing timing of the hot gas bypass valve (21) and the compressor
The reason for shifting the release timing of the operating frequency regulation in (1) is to suppress the sudden increase in the high-pressure side pressure. on the other hand,
During the cooling operation, as shown in FIG. 5, first, similarly to the heating operation, the soft start operation is performed for a predetermined time (1 minute) at the same time as the start. That is, the operating frequency of the compressor (1) is fixed at 42 Hz and the hot gas bypass valve (21) is opened. Then, the hot gas bypass valve (21) is closed at the same time as the end of the soft start operation, and the upper limit frequency of the compressor (1) is regulated to 60 Hz, thereby suppressing the occurrence of the forming of the liquefied liquid refrigerant. Control the outflow of lubricating oil from the compressor (1). Incidentally, in the state shown in FIG. 5, the operating frequency is at the upper limit value of 60 Hz at the same time when the software startup is completed.
In such an operating state, the low pressure is 1.5
When it becomes less than kg / cm ² (position A in FIG. 5), the hot gas bypass valve (21) is opened again to bypass the discharge gas refrigerant to the low pressure side to suppress the decrease in low pressure and Prevents deterioration of pump capacity. Also in this case, the lower limit frequency of the compressor (1) is regulated to 54 Hz by the lower limit frequency setting means (15d). And 5 from startup
When the minutes have passed (position B in FIG. 5), the hot gas bypass valve (21) is closed, and after a further 20 seconds have passed (position C in FIG. 5), the operating frequency of the compressor (1) The regulation is lifted and normal operation is resumed. That is, even during the cooling operation, the operating frequency of the compressor (1) does not exceed 60 Hz until 5 minutes and 20 seconds have passed since the startup.

Thus, in this example, the compressor (1)
In the situation where the liquid refrigerant is sunk inside, the operating frequency of the compressor (1) is regulated to a low value even after the completion of the soft start to prevent the occurrence of liquid refrigerant forming and to reduce the pressure on the low pressure side. In a situation where the oil pressure is low, the high-pressure discharge gas refrigerant is bypassed to the low-pressure side to suppress the decrease in low-pressure pressure and prevent the decrease in oil pump capacity. Can be avoided, and a good lubrication state can be obtained at the time of startup, so that the reliability of the compressor (1) can be improved.

In this example, the compressor (1) is described as an inverter-controlled type, but the present invention is not limited to this.
The present invention is not limited to this, and can also be applied to those equipped with an unloader mechanism. As the air conditioner, a multi-type air conditioner equipped with a plurality of indoor units is adopted, and as the refrigerant circuit, a differential pressure forced type compressor in which two compressors are arranged in the outdoor unit is provided. It can also be used in a refrigerant circuit.

[0024]

As described above, according to the present invention, the following effects are exhibited. According to the invention of claim 1, when the operation stop time of the compressor (1) is longer than a predetermined long time, after the end of the predetermined time when the operation frequency of the compressor (1) is fixed to the first start frequency. The upper limit of the operating frequency of the compressor (1) is set to the second starting frequency for a predetermined time, and the operating frequency of the compressor (1) is regulated to the second starting frequency or less for the predetermined time. When the suction side pressure of the compressor (1) becomes less than or equal to a predetermined value within a predetermined time when the upper limit frequency of the operating frequency of the frequency setting means (15a) and the compressor (1) is set to the second starting frequency, Open / close valve
(21) is opened and the discharge gas refrigerant of the compressor (1) is bypassed.
A low pressure increasing means (15b) for increasing the pressure on the suction side by supplying it to the suction side via (11d) is provided.
(1) In the situation where the liquid refrigerant is lying inside,
Even after the soft start is completed, the operating frequency of the compressor (1) is regulated to a low value to prevent the formation of liquid refrigerant, and when the pressure on the suction side is low, the high-pressure discharge gas refrigerant is turned to the low-pressure side. By-passing suppresses the pressure drop on the suction side and prevents the oil pump from decreasing in performance, so it is possible to avoid running out of oil in the compressor (1), and at the time of startup. A good lubrication state can be obtained, and the reliability of the compressor (1) can be improved.

According to the second aspect of the present invention, the stop time recognition means (15c) has the operation stop time of the compressor (1) for a predetermined long time or more at the first start after the main power is turned on. Therefore, even if the main power supply is turned off, where the actual stop time of the compressor (1) cannot be measured, the liquid refrigerant inside the compressor (1) cannot be measured. In the situation where sleeping is occurring, the conventional inconvenience of immediately shifting to normal operation after software startup can be avoided, and the reliability of the compressor (1) can be further improved.

According to the invention of claim 3, the compressor (1)
When the shutdown time of the
After the predetermined time when the operating frequency of (1) is fixed to the first starting frequency, the lower limit frequency of the operating frequency of the compressor (1) is set to the third starting frequency lower than the second starting frequency for a predetermined time. Since the lower limit frequency setting means (15d) for restricting the operating frequency of the compressor (1) to the third starting frequency or more is provided only during the predetermined time, the compressor is set.
It is possible to prevent the performance of the oil pump from being lowered due to the operating frequency of (1) being too low.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of the present invention.

FIG. 2 is a diagram showing a refrigerant piping system.

FIG. 3 is a flowchart showing a control procedure at the time of activation by the control unit.

FIG. 4 is a time chart showing the control of the compressor frequency and the hot gas bypass valve at the time of heating activation.

FIG. 5 is a time chart showing the control of the compressor frequency and the hot gas bypass valve at the time of cooling activation.

[Explanation of symbols]

 (1) Compressor (2a) Inverter (frequency adjusting means) (11d) Hot gas bypass path (14) Main refrigerant circuit (15a) Upper limit frequency setting means (15b) Low pressure raising means (15c) Stop time recognition means (15d) Lower limit frequency setting means (21) Hot gas bypass valve (open / close valve) (P2) Low pressure sensor (low pressure detection means)

Claims (3)

[Claims] 1. A refrigerant circuit (14) is provided with a compressor (1), and a bypass passage (11d) for connecting a discharge side and a suction side of the compressor (1) is provided. , The bypass path (1
1d) has an open / close valve (21) that can be opened and closed,
Frequency adjusting means (2a) for adjusting the operating frequency of the compressor (1)
When the compressor (1) is started, the frequency adjusting means (2a) causes the compressor (1) to operate for a predetermined time after the start.
Low pressure detecting means (P2) for detecting the pressure on the suction side of the compressor (1) in a refrigeration system in which the operating frequency of the compressor is fixed to a low first starting frequency
And a stop time recognition means for recognizing the operation stop time of the compressor (1).
(15c) and the output of the above stop time recognition means (15c), the compressor (1)
When the shutdown time of the
After the operation time of (1) is fixed to the first start frequency, the upper limit frequency of the operation frequency of the compressor (1) is set to the second start frequency for a further predetermined time, and the upper limit frequency is set. Send the signal to the frequency adjusting means (2a),
The compressor (1) receives the output signal of the upper limit frequency setting means (15a) for restricting the operating frequency of the compressor (1) to the second starting frequency or less only during this predetermined time and the low pressure detecting means (P2). When the suction side pressure of the compressor (1) becomes less than or equal to a predetermined value within the predetermined time when the upper limit frequency of the operating frequency is set to the second starting frequency, the on-off valve (21) is opened to open the compressor.
Low-pressure rising means (15b) that raises the suction side pressure by supplying the discharge gas refrigerant of (1) to the suction side through the bypass path (11d).
And a refrigerating device. 2. The stop time recognition means (15c) recognizes that the operation stop time of the compressor (1) is a predetermined long time or more at the first start after the main power is turned on, and sets the upper limit frequency. Refrigeration system according to claim 1, characterized in that it is arranged to output a signal to the means (15a). 3. Receiving the output of the stop time recognition means (15c),
When the operation stop time of the compressor (1) is more than a predetermined long time, the operation frequency of the compressor (1) is fixed to the first start frequency, and after the end of the predetermined time, the compressor (1) is further operated for a predetermined time. The lower limit frequency of the operating frequency is set to a third start frequency lower than the second start frequency, the lower limit frequency setting signal is transmitted to the frequency adjusting means (2a), and the compressor ( The refrigerating apparatus according to claim 1 or 2, further comprising: a lower limit frequency setting means (15d) for restricting the operating frequency of 1) to a third starting frequency or higher.