JPH0330778Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of the invention] This invention relates to an outdoor unit that constitutes a heat pump type refrigeration cycle that can be operated for cooling and heating.
In particular, the present invention relates to improvements in the mounting structure of a temperature sensor that detects defrosting.

[Technical background of the invention and its problems]

Some outdoor units that constitute a heat pump type refrigeration cycle are equipped with an outdoor heat exchanger in which a plurality of completely separated paths are arranged in the vertical direction.

By the way, in such an outdoor unit, it is known that the condensate forms frost on the outdoor heat exchanger during heating operation. This kind of frost formation has the problem of abnormally lowering the heat exchange efficiency of the outdoor heat exchanger, and conventionally, as a means to remove this kind of frost formation, from heating operation to
A different cycle operation, so-called defrosting operation, is used to melt the drain.

Defrosting is generally performed by installing a defrosting temperature sensor on the inlet side (during defrosting operation; outlet side) of the pipe during heating operation to detect defrosting or recovery. The system detects the occurrence of frost and the disappearance of frost based on this temperature change, performs defrosting operation, and then returns to heating operation from defrosting operation. I'm trying to control it.

Conventionally, as shown in Figure 3, such a temperature sensor was installed on the outdoor heat exchanger a during defrosting operation.
A temperature sensor e is attached to a confluence section d where the refrigerants flowing out from paths b and c are combined.

However, the structure in which the temperature sensor e is provided at the confluence part d is affected by the high temperature refrigerant temperature on the path b side, which starts defrosting first among paths b and c, and the temperature sensor e detects that defrosting has finished. There is a problem that it cannot be detected reliably, and residual frost often occurs.

Therefore, in view of this, as shown in Fig. 4, a capillary tube (decompression device) f is interposed at the ends of paths b and c, and the temperature sensor e is provided on the upstream side. Proposed.
However, although this allows the temperature of the refrigerant from path b to be detected accurately, the capillary tube f has a small diameter and is therefore susceptible to freezing due to frost formation. For this reason, there is a risk that defrosting may not be possible due to clogging, and there is a need for something that can completely defrost without using a pressure reducing device that requires a large number of parts.

(Purpose of the invention) This invention was made in view of the above-mentioned circumstances, and its purpose is to provide an outdoor unit that can completely defrost.

(Summary of the invention) In other words, this invention is based on an outdoor heat exchanger that, during defrosting operation, connects the outlet pipe of the outdoor heat exchanger to the outlet pipe located at the lowest position in the vertical direction among the exit pipes of the exit path. A bent part is provided by bending a pipe part near the main body approximately at right angles, and when the defrosting operation is performed using this bent part as a boundary, the defrosting is performed at the outlet pipe part after the bent part which is downstream in the flow direction. It is equipped with a temperature sensor for use. With this configuration, during defrosting operation, the refrigerant in the outlet pipe located at the lowest position, which flows as a two-phase flow of gas and liquid, is mixed at the bending part due to collision with the same bending part. . As a result, the temperature sensor detects the accurate refrigerant temperature at the exit side, which is not biased toward the gas phase temperature or the liquid phase temperature, that is, the temperature of the two-phase mixed refrigerant, as the refrigerant temperature that remains low until the end. There is. In other words, during defrosting operation, the temperature of the refrigerant can be accurately detected from the lowest outlet pipe, where the temperature is the lowest until the end.

(Embodiment of the invention) This invention will be described below based on an embodiment shown in FIGS. 1 and 2. FIG. 2 shows the entire outdoor unit, where 1 is a main body and 2 is an outdoor heat exchanger installed within the main body 1. Also, main body 1
In addition to the outdoor heat exchanger 2, outdoor equipment such as a compressor, four-way valve, and pressure reducing device (not shown) are installed inside the room, and these equipment and a room (not shown) installed on the indoor side are installed. Together with the inner unit, a heat pump type refrigeration cycle capable of heating and cooling operation is configured.

On the other hand, the outdoor heat exchanger 2 is provided with a temperature sensor 3 for defrosting. The mounting structure of this temperature sensor 3 is shown in FIG.

Here, before explaining the mounting structure of the temperature sensor 3, which is the main part of this invention, the outdoor heat exchanger 2 will be explained. 4 is a refrigerant distribution pipe,
5 is a T-joint connected to the end of the pipe 4. The T-joint 5 is disposed on the side of the outdoor heat exchanger 2 along the vertical direction. On the other hand, the outdoor heat exchanger 2 has a main body 2a with completely separate paths 5a and 5b arranged on the vertically upper and lower sides, respectively. The outdoor heat exchanger 2 has a main body 2a connected to the lower end of the path 5a and the upper end of the path 5b.
The pipes projecting laterally are used as outlet pipes 6a and 6b through which the refrigerant flows out during defrosting operation. These outlet pipes 6a and 6b are respectively connected to the ends of the T-joint 5 in a U-shape, and the outlet pipes 6a and 6b are connected to the pipe portions near the main body 2a in an L-shape, that is, at a substantially right angle. A bent portion 7 is formed by bending in the direction. However,
With this piping, each path 5a, 5b from the pipe 4
The outdoor heat exchanger 2 acts as an evaporator as the refrigerant flows toward each path 5, and vice versa.
By flowing the refrigerant from a and 5b toward the pipe 4, the outdoor heat exchanger 2 functions as a condenser. During these defrosting operations, among the outlet pipes 6a and 6b, which are the outlets, the outlet pipe 6b, which is disposed lowest in the vertical direction, has a gap between the bending part 7 and the U-shaped bending part. The temperature sensor 3 is attached to the outlet pipe 6b in close contact with the pipe section, that is, the pipe section after the bending part 7 which is downstream in the flow direction during defrosting operation.

Therefore, when performing heating in the above-described configuration, by setting the four-way valve (not shown) to the heating side and operating the compressor, the refrigerant flows through the indoor unit and the refrigerant flows through the outdoor heat exchanger 2 as indicated by the broken line. It flows as shown and heats the room.

During such heating operation, if frost formation occurs on the outdoor heat exchanger 2, the temperature sensor 3 detects the temperature change and switches from the heating operation to the defrosting sensor. As a result, the outdoor heat exchanger 2
However, there is a concern that the defrost may not be completely defrosted.

However, according to this invention, a bending part 7 that is bent approximately at right angles is provided on the outlet pipe 6b located at the lowest position in the vertical direction, and a temperature sensor 3 for defrosting is provided after the bending part 7. Therefore, the temperature sensor 3 detects the lowest and most accurate refrigerant temperature until defrosting is completely completed. To explain why the temperature of the outlet pipe 6b is the lowest, when the defrosting operation starts, as shown in the embodiment of FIG.
In path 5b, the high temperature gas refrigerant discharged from the compressor flows from the top to the bottom, and in path 5b, the refrigerant flows from the bottom to the top.
When passing through a and 5b, the refrigerant exchanges heat and becomes a liquid refrigerant. At this time, the frost on the upper stage side melts and naturally falls to the lower stage side path 5b, increasing the heat exchange efficiency on the path 5b side, thereby causing the path 5b to become undercooled. In other words, the outlet pipe 6b has the lowest temperature in the outdoor heat exchanger 2 until defrosting is finished. Moreover, at this time, the liquid refrigerant flows along the direction of gravity in path 5a, so the inertia force is small, whereas in path 5b, it flows against the direction of gravity, so the inertia force becomes large, so the liquid refrigerant in path 5b The amount of refrigerant gradually increases, and the difference in outlet temperature between the outlet pipe 6b and the outlet pipe 6a becomes larger. This is because the imbalance in the flow rate of the refrigerant during defrosting increases over time. Also, to explain why the refrigerant temperature is accurate, during defrosting operation, the refrigerant enters the outlet port 6a in two phases: a liquid phase flowing along the lower part of the pipe and a gas phase flowing along the upper part of the pipe. It flows with the flow. Here, the temperature of the liquid refrigerant and the gas refrigerant are different, so if the temperature is detected from the outer circumference of the pipe along which the gas flow follows, the temperature of the gas flow will be detected, and if the temperature is detected from the outer circumference of the pipe along which the liquid flow follows. The temperature of the liquid stream is sensed. In other words,
Since it is not an accurate refrigerant temperature, this temperature detection cannot accurately determine whether defrosting is on or off. but,
According to this invention, the refrigerant in the two-phase flow of gas and liquid is mixed at the bending part 7 as it collides with the bending part 7. Then, the accurate refrigerant temperature on the outlet side that is not biased toward the gas phase temperature or the liquid phase temperature, that is, the temperature of the two-phase mixed refrigerant, is determined as the refrigerant temperature that remains low until the end at the downstream stage of the bending part 7. temperature sensor 3 is detected. However, during the defrosting operation, it is possible to accurately detect the temperature of the refrigerant from the lowest outlet pipe 6b where the temperature is the lowest until the end. Therefore, complete and reliable defrosting control can be performed without any need for a pressure reducing device such as a capillary tube that causes clogging and an increase in the number of parts as in the prior art.

(Effects of the invention) As explained above, according to this invention, complete defrosting can be performed without using a decompression device that clogs and increases the number of parts as in the past.

[Brief explanation of drawings]

1 and 2 show an embodiment of this invention, and FIG. 1 is a perspective view showing the installation of a temperature sensor;
Figure 2 is a perspective view showing the entire outdoor unit, Figure 3 is a perspective view showing the entire outdoor unit.
This figure is a perspective view showing how a temperature sensor is installed in a conventional outdoor unit, and FIG. 4 is a perspective view showing how a different conventional temperature sensor is installed. 2... Outdoor heat exchanger, 3... Temperature sensor for defrosting, 5a, 5b... Pass, 6a, 6b... Outlet pipe, 7... Bent portion.

Claims (1)

[Scope of utility model registration request] The main body is constructed by vertically arranging multiple completely separated paths, and includes an outdoor heat exchanger that constitutes a heat pump type refrigeration cycle, and an outlet and an outlet during defrosting operation in this outdoor heat exchanger. Among the outlet pipes of the path, there is a bent part provided in the outlet pipe located at the lowest position in the vertical direction and formed by bending the pipe part near the main body in a substantially right angle direction, and 1. An outdoor unit characterized by comprising: a temperature sensor for defrosting provided at a portion of the outlet pipe downstream of the bending portion in the flow direction during frost operation.