JPH0552445A - Low pressure monitoring control for engine-driven heat pump - Google Patents

Abstract

PURPOSE:To prevent the generation of a negative pressure through the rapid increase of the pressure on the suction side of a compressor by a method wherein, when the pressure on the suction side of the compressor is reduced, a bypass valve is opened and a high-pressure refrigerant flows to the suction side of the compressor. CONSTITUTION:In an engine-driven heat pump comprising outdoor and indoor units 5A and 5B, a refrigerant pressure on the suction side of a compressor 52 is measured by a pressure sensor 4. The pressure is lower than a given pressure. The lower the pressure is, the more bypass valves 2 and 3 located between a refrigerant pipe 1 on the inlet side of an accumulator 58 and the refrigerant pipe 1 on the outlet side of the compressor 52 are opened. A high- pressure refrigerant compressed and discharged by means of the compressor 52 is caused to flow in through the bypass, and the pressure on the suction side of the compressor 52 is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to operation control of a heat pump type cooling and heating device for driving a compressor by a gas engine or the like to compress and circulate a refrigerant.

[0002]

2. Description of the Related Art Conventionally, an engine-driven heat pump formed by sequentially connecting a compressor driven by an engine, a four-way valve, an indoor heat exchanger, a receiver tank, an outdoor electric valve, an outdoor heat exchanger, an accumulator, etc. It is commonly used for air conditioning and heating and hot water heating.

In the conventional engine-driven heat pump described above, no control is performed to prevent an abnormal decrease in the pressure on the low pressure side of the refrigerant circulation system, that is, the pressure on the suction side of the compressor. In the past, it has been controlled using a low-voltage switch, but it often malfunctions. The engine is stopped and an alarm is issued each time, so there are many inconveniences, such as the cause of complaints. Since the low-pressure side pressure is not controlled, for example, when the low-pressure side pressure is abnormally reduced to below atmospheric pressure, air is introduced into the refrigerant circulation system from the gap between the shaft and the body of the compressor driven by the engine. There was also a problem that it penetrated and reduced the refrigeration capacity.

On the other hand, the presence or absence of refrigerant leakage is still detected by the low-voltage switch. However, the pressure on the low-pressure side may drop temporarily during warm-up operation when the outside air temperature is low, or when the number of operating indoor units is switched, etc. There was such a drawback, and the work had to be troublesome because the engine had to be stopped and then inspected.

[0005]

That is, in the conventional engine-driven heat pump, the control for preventing the abnormal decrease of the low-pressure side pressure is not performed, and even if the operation for detecting the leakage of the refrigerant cannot be detected while the engine is operating. However, there was a problem to solve this point.

[0006]

As a concrete means for solving the above-mentioned problems of the prior art, the present invention provides a compressor driven by an engine, a four-way valve, an indoor heat exchanger, a receiver tank, an outdoor electric valve, In an engine-driven heat pump in which an outdoor heat exchanger, an accumulator, and the like are sequentially connected via a refrigerant pipe to form a cooling / heating circuit, the heat exchanger is provided between the refrigerant pipe on the inlet side of the accumulator and the refrigerant pipe on the outlet side of the compressor. Low-pressure monitoring control in an engine-driven heat pump characterized by opening and closing the bypass valve based on the refrigerant pressure on the compressor suction side, recovering the set value even if the refrigerant pressure on the compressor suction side opens the bypass valve. If not, it is a low pressure monitoring control in the engine-driven heat pump that gives a warning display of refrigerant leakage, and the refrigerant pressure on the compressor suction side opens the bypass valve. When a predetermined pressure or less even after the lapse of the predetermined time Te, by providing a low pressure monitoring control in an engine driven heat pump to stop the engine, is to solve the problems of the aforementioned prior art.

[0007]

[Function] When the refrigerant pressure on the suction side of the compressor falls below a predetermined pressure, the bypass valve provided between the refrigerant pipe on the inlet side of the accumulator and the refrigerant pipe on the outlet side of the compressor opens, and the compressor compresses and discharges it. Since a part of the high pressure refrigerant that has been discharged is sent to the suction side of the compressor through this open bypass valve and the pressure in this part rises and the prescribed pressure is restored, a negative pressure (state lower than atmospheric pressure) Never be.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an example of a system diagram of an engine driven heat pump adopting the low pressure monitoring control according to the present invention. In the figure, 51 is, for example, a gas engine that uses city gas as fuel (hereinafter simply referred to as engine), 52 is a compressor, and 53
Is a four-way valve, 54 is an indoor heat exchanger, 55 is a receiver tank, 56 is an outdoor electric valve, 57 is an outdoor heat exchanger, and 58 is an accumulator. These device units are not different from those conventionally known, A refrigerant circuit 1 shown by a solid line and a heating circuit B shown by a broken line are sequentially connected via a refrigerant pipe 1, and a refrigerant pipe 1 on the inlet side of the accumulator 58 and an outlet side refrigerant pipe of the compressor 52. 1, a relatively large main bypass valve 2 and a smaller sub bypass valve 3 are provided, and the pressure sensor 4 is provided in the refrigerant pipe 1 between the accumulator 58 and the compressor 52 and the compressor 52. It is installed so that the pressure of the refrigerant (steam) sucked into (hereinafter, referred to as the low-pressure side pressure) can be measured. In addition, 5A shows an outdoor unit and 5B shows an indoor unit.

In the system configuration described above, the low pressure side pressure level of the refrigerant measured by the pressure sensor 4 is classified into grades, and the bypass valves 2 and 3 are automatically controlled to open and close based on this grade. Therefore, for example, electromagnetically driven bypass valves are selected as the bypass valves 2 and 3. The control device for classifying the low-pressure side pressure measured by the pressure sensor 4 and opening / closing the bypass valves 2 and 3 based on the result is either an outdoor controller or an indoor controller (both not shown). It is provided.

The degree of low pressure on the low pressure side measured by the pressure sensor 4 is, for example, LL. Then, the range of LL is set to, for example, 0 ≦ LL ≦ 3, and it is promised that the higher the value, the higher the low-pressure grade (the lower the pressure). As an initial value, for example, 2 seconds after the engine is started, the low pressure side pressure <0.6Kg
If f / cm ² , LL = 3, low pressure side >> 0.6Kg
If f / cm ² , LL = 0, and then LL is fixed, for example, for 1 minute. The subsequent LL is obtained as follows based on the low-pressure side pressure measured by the pressure sensor 4 every one minute, for example. If the pressure on the low pressure side is <0.6 Kgf / cm ² , then LL = LL +
1 0.6 Kgf / cm ² ≦ low pressure side pressure <1.4 Kgf / cm ² LL = LL 1.4 Kgf / cm ² ≦ low pressure side pressure LL = LL−
1

The opening / closing of the bypass valves 2 and 3 is automatically controlled as follows according to the magnitude of LL obtained as described above. When LL = 0, both bypass valves 2 and 3 are closed When LL = 1, bypass valve 2 is closed and 3 is opened When LL = 2, bypass valve 2 is opened and 3 is closed When LL = 3 By opening and closing both the bypass valves 2 and 3, by controlling the opening and closing of the bypass valves 2 and 3 in this way, the high-pressure refrigerant compressed and discharged by the compressor 52 (during rated operation, for example, 19 Kgf / cm ² ) As the low-pressure side pressure (at rated operation, for example, 3.8 Kgf / cm ² ) decreases, a large amount of gas flows into the compressor suction side through the bypass valves 2 and 3, so the pressure in this part rises, and the prescribed pressure rapidly increases. It will never be restored to negative pressure. ..

However, if the low-pressure side pressure does not recover to the predetermined pressure despite the above control, there is a risk that the refrigerant will leak and decrease, or the refrigerant will have completely disappeared. Carry out.

When the engine is started, for example, the pressure on the low-pressure side is ≤1 Kgf / cm ² , and if this pressure state is maintained for a certain time (for example, 3 minutes), it is judged that the refrigerant is completely leaked, The engine 51 is stopped, and a warning signal is transmitted from the control device to display a refrigerant leak alarm on a display unit such as the indoor unit 54 or a remote controller (not shown).

At engine startup, low pressure side> 1 kgf / cm
If it is ² , the display of the low pressure side pressure is ignored for a fixed time (for example, 20 minutes), and then, if the above-mentioned low pressure level LL is LL = 3 continuously for a fixed time (for example, 3 minutes), once, The engine is stopped and restarted after a fixed time (for example, 3 minutes). When the above state (LL = 3 for 3 minutes) is reached again, it is determined that the refrigerant has completely leaked, the engine is stopped, and a caution signal is issued in the same manner as described above to display an alarm for refrigerant leakage.

Since the present invention is not limited to the above-mentioned embodiment, the low pressure side pressure is graded and the length of observation time when inspecting the refrigerant leakage is taken into consideration in the required accuracy of control. It may be determined appropriately. Further, in the above embodiment, two main bypass valves 2 and sub bypass valves 3 are installed, but one large bypass valve whose opening can be adjusted is installed, and this opening is controlled according to the pressure level. It is also possible to

[0016]

As described above, according to the present invention, the bypass valve provided between the refrigerant pipe on the inlet side of the accumulator and the refrigerant pipe on the outlet side of the compressor reduces the pressure on the suction side of the compressor to a low pressure or less. It is a control method that causes the high-pressure refrigerant that is sometimes opened and compressed / discharged by the compressor through this bypass valve to flow into the compressor suction side to recover the pressure in this part. Even if the low-pressure side pressure drops due to changes, it is possible to quickly respond. Therefore, it becomes possible to completely solve the problem of the conventional device that the low-pressure side pressure is abnormally lowered to the atmospheric pressure or less, and the atmosphere invades the refrigerant circulation system to deteriorate the refrigerating capacity. In addition, it is possible to prevent erroneous detection due to temporary fluctuations in the indoor heat exchanger temperature and compressor suction pressure, and it is possible to reliably detect refrigerant leakage, so stop the device one by one each time the pressure drops abnormally. It is no longer necessary to investigate the cause.

[Brief description of drawings]

FIG. 1 is a system diagram of an engine-driven heat pump.

[Explanation of symbols]

 1 Refrigerant Pipe 2 (Main) Bypass Valve 3 (Sub) Bypass Valve 4 Pressure Sensor 51 (Gas) Engine 52 Compressor 53 Four-way Flight 54 Indoor Heat Exchanger 55 Receiver Tank 56 Outdoor Motorized Valve 57 Outdoor Heat Exchanger 58 Accumulator 5A Outdoor Unit 5B Indoor unit A Cooling circuit B Heating circuit

Claims (3)

[Claims] 1. A compressor driven by an engine, a four-way valve, an indoor heat exchanger, a receiver tank, an outdoor electric valve, an outdoor heat exchanger, an accumulator, etc. are sequentially connected via a refrigerant pipe, and a cooling / heating circuit is formed. In the engine-driven heat pump that is formed, the bypass valve provided between the refrigerant pipe on the inlet side of the accumulator and the refrigerant pipe on the outlet side of the compressor is opened and closed based on the refrigerant pressure on the suction side of the compressor. Low pressure monitoring control for engine driven heat pump. 2. The low-pressure monitoring control for an engine-driven heat pump according to claim 1, wherein when the refrigerant pressure on the suction side of the compressor does not recover the set value even if the bypass valve is opened, a warning of refrigerant leakage is displayed. 3. The low pressure monitoring control for an engine driven heat pump according to claim 1, wherein the engine is stopped when the refrigerant pressure on the suction side of the compressor is equal to or lower than a predetermined pressure even after a predetermined time has elapsed since the bypass valve was opened.