JPH0327251Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Field of Application> The present invention relates to a refrigeration circuit for an air conditioner that can be used as both a cooling device and a heating device through a switching operation.

<Prior art> The refrigeration circuit in a conventional heat pump type air conditioner is configured as shown in FIG. Pirareach Yube 6 ₁ , 6 ₂
A cooling capillary reach tube 5 and a check valve 8 are connected in series between the same outlet and inlet sides of both heat exchangers 2 and 3, Furthermore, the delivery side (high pressure side) and the return side (low pressure side) of the compressor 1 are connected via the four-way valve 4 between the inlet of the outdoor heat exchanger 2 and the outlet of the indoor heat exchanger 3, respectively, and at the same time the compression An injection capillary reach tube 7 was inserted between the machine 1 and the connection point of the first and second heating capillary reach tubes 6 ₁ and 6 ₂ . In addition, the solid line arrow _D1 in the figure indicates the medium return direction during cooling, and the dotted line arrow _D2 indicates the medium circulation direction during heating.

Therefore, the air conditioner usually operates until the set temperature is reached, and when the set temperature is reached, the compressor 1 is automatically stopped, and this operation is repeated.
When the compressor 1 stops operating, a large vibration is generated, and especially in an air conditioner with an integral structure where the compressor 1 is installed indoors, the vibration is felt to be even larger. The vibrations caused ornaments on shelves to vibrate, and the noise was particularly loud in aging wooden houses, which was one of the complaints from users.

There are various causes of vibrations that occur when the compressor 1 is stopped, and the main cause is the magnitude of the load on the compressor, as is clear from the distribution diagram of pressure difference versus vibration level in Figure 8. This is generally related to the size of the pressure difference between the high pressure side and the low pressure side of the compressor itself.

Therefore, if the state of vibration is examined in more detail, the damping time of the medium when the compressor 1 is stopped is different depending on whether the compressor 1 is operated as a heater or a cooler. For example, the load voltage fluctuation characteristic diagram in Figure 9 clearly shows that impact vibrations persist for a long time when the compressor is abruptly stopped when the compressor is only used for heating, and Figure 10 shows that the same machine The vibration voltage fluctuation characteristic diagram when the compressor is abruptly stopped in the same way as above when switched to cooling mode shows that the shock vibration damps quickly, but the amplitude of the initial vibration is still large, and it is clear that this is the cause of the vibration. It is.

<Problems to be solved by the invention> The invention solves the problem of shocking vibrations that occur when the compressor of a heat pump air conditioner stops by eliminating the excessive pressure difference between the sending side and the return side. The purpose is to provide air conditioners that are not available in Japan.

<Means for solving the problem> The present invention provides a bypass circuit in parallel with the on-off valve connected to the return side of the compressor that constitutes the heat pump type air conditioner, and opens and closes it when only for cooling and when only for heating. By changing the closing time of the valve, the load is gradually reduced and the pressure difference is reduced.

<Function> The time from the start of the closing operation of the on-off valve connected in parallel with the capillary reach tube on the return side of the compressor to the stop operation of the compressor is made longer during heating and shorter during cooling. In a refrigeration cycle circuit that has different attenuation times depending on the time and cooling time, the return pressure acting on the compressor is received by the capillary reach tube and reduced, reducing the delivery capacity and reducing the difference between the delivery pressure and the return pressure. After that, the on-off valve is opened for a certain period of time, and then the compressor is stopped.

<Example> Below, an example of the present invention shown in the drawings will be described. FIG. 1 shows a circuit of a refrigeration cycle, and the outlet side (solid line direction) of the outdoor heat exchanger 2 and the inlet side of the indoor heat exchanger 3 are shown. (solid line direction)
The capillary reach tube 6 ₁ and the second capillary reach tube 6 ₂ for heating are connected in series, and the first and second capillary reach tubes 6 ₁ for heating are connected in series.
A cooling _capillary reach tube 5 and a check valve 8 are connected in series between one end of each of the outdoor heat exchanger 2 and an indoor heat exchanger via branch valves 12 ₁ and 12 ₂ . A four-way valve 4 is connected between the four-way valve 4 and the outlet side of the compressor 1, and the four-way valve 4 is connected to the delivery side of the compressor 1, and an accumulator 11 is connected to the four-way valve 4 and the return side of the compressor 1. In between, the on-off valve 9 and the bypass capillary reach tube 10 are connected in parallel. Incidentally, an injection capillary reach tube 7 is connected to the compressor 1 by branching from the connecting portion of the heating first and second capillary reach tubes 6 ₁ and 6 ₂ .

Note that the on-off valve 9 is an electromagnetic on-off valve, etc.
The circuit configuration is designed so that when the operation panel on the front of the air conditioner is set for heating only or cooling only, the control circuits are switched to the respective dedicated control circuits and the respective closing times are set according to the heating mode. ing.

Therefore, while the compressor 1 is in operation, the pressure at point A on the delivery side is high pressure _P2 , and the pressure at points B and C on the return side is at low pressure _P1 due to the load.

At this time, if the compressor 1 is stopped, there will be a considerable pressure difference between the pressure at points B and C on the return side and the pressure at point A on the delivery side at that moment, which will cause large vibrations. , the present invention first closes the on-off valve 9 for a certain period of time at time t ₀ before stopping the compressor 1 (several seconds before) during cooling operation, converts the feedback circuit to a bypass capillary reach tube 10, and operates as indicated by arrow D ₃ . As a result of this feedback, the pressure at point C increases (dotted line in FIG. 2). On the other hand, the pressure at point B is the bypass capillary reach tube 1
0, and the return pressure to the compressor 1 eventually decreases, so the pressure at point A on the delivery side is not increased due to the feedback amount, that is, the decrease in back pressure, and continues to decrease. When the on-off valve 9 is opened at time t ₁ , the pressure at point B becomes equal to the pressure at point C in an instant at t ₂ , and the pressure at point A also starts to rise, but is initially high. Return pressure acts on point B.

Therefore, the difference ΔP between the pressure on the delivery side and the pressure on the return side becomes sufficiently small, and if the compressor is stopped at this time, the impulsive initial vibration disappears and at the same time quickly attenuates and disappears as shown in FIG.

Furthermore, when the air conditioner is operated as a heater, unless the on _- off valve ₉ is closed for a long time as shown in FIG. cannot be approximately equal to .

As shown in Fig. 4, during heating, by setting the closing time of the on-off valve 9 to about 90 seconds and the opening time to about 5 seconds, the vibration is significantly reduced;
As shown in the figure, when the closing time during cooling is the same as during heating, when the closing time is 90 seconds, and the opening time is given for 5 seconds, a sufficient effect cannot be expected.
By setting the pressure to 180 seconds and opening it for 5 seconds, a sufficient damping effect can be obtained and a result approximately equal to the pressure difference during heating can be obtained.

<Effects of the invention> As mentioned above, the present invention reduces the pressure difference between the circulating medium on the delivery side and the return side of the compressor, thereby reducing the impact vibration when the compressor is stopped and the accompanying noise. can be significantly reduced.

In addition, by reducing vibration, each set screw of the air conditioner is prevented from loosening, maintaining the stability of the equipment over a long period of time, and preventing the occurrence of failures by eliminating disconnections in electrical circuits. be able to. Furthermore, by extending the closing time of the on-off valve during heating to a longer time than the closing time during cooling, the closing time of the on-off valve is shifted, thereby eliminating the large difference in pressure difference in heat pump air conditioners.
This is a highly practical idea with many excellent effects, including the ability to dampen vibrations even during heating.

[Brief explanation of drawings]

Figure 1 is a refrigeration cycle circuit diagram of the heat pump air conditioner of the present invention, and Figure 2 is the pressure on the high-pressure side and low-pressure side of the compressor that occurs when the refrigeration cycle circuit in Figure 1 is operated as a refrigerator. Characteristic diagram, Figure 3 is a pressure characteristic diagram on the high pressure side and low pressure side of the compressor that occurs when the above air conditioner is operated as a heater, Figure 4 is a load voltage attenuation characteristic diagram during heating operation, FIG. 5 is a load voltage attenuation characteristic diagram during cooling operation, and FIG. 6 is a load voltage attenuation characteristic diagram when the closing time of the on-off valve is changed during cooling operation.
Figure 7 is a refrigeration cycle circuit diagram of a conventional heat pump air conditioner, Figure 8 is a distribution diagram of the pressure difference and vibration level between the high pressure side and low pressure side of the compressor, and Figure 9 is a diagram of the vibration level during heating operation. FIG. 10 is a load voltage attenuation characteristic diagram of the conventional machine during cooling operation. 1...Compressor, 2...Outdoor heat exchanger, 3...Indoor heat exchanger, 9...Open/close switching valve, 10...Bypass capillary reach tube.

Claims (1)

[Scope of utility model registration request] In a heat pump type air conditioner, a compressor is connected between an outdoor heat exchanger and an indoor heat exchanger via a four-way switching valve, and the return path of the compressor has a closing time during heating and cooling. Different electromagnetic on-off valves and a bypass capillary reach tube are connected in parallel, and an on-off valve control means is provided which temporarily closes the on-off valve prior to the stop operation of the compressor and then opens the on-off valve again. A refrigeration circuit for an air conditioner, characterized in that the closing time of the on-off valve of the control means is set longer during heating operation than during cooling operation.