JPS594867A - Controller for flow rate of refrigerant - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refrigerant flow rate control device for a refrigeration cycle. A capillary tube or a thermostatic automatic expansion valve is known as a refrigerant flow rate control device for a refrigeration cycle. Capillary tubes adjust the flow rate of refrigerant using the flow resistance of the capillary tubes, and are suitable for cleaning when the condensation pressure and evaporation pressure of the refrigeration cycle do not change significantly from the design point. It is impossible to control the flow rate, and there are problems in that excessive refrigerant overheating or liquid back up occurs.

On the other hand, a thermostatic automatic expansion valve, as shown in Figure 1, consists of a temperature-sensitive tube 1 filled with the same type of refrigerant as the refrigerant in the refrigeration cycle, a diaphragm 2, a diaphragm upper pressure chamber 3, and a diaphragm lower pressure chamber. 4, spring 5, valve stem 6, pressure equalizing hole 7,
and a capillary tube 8, and performs more advanced refrigerant flow rate control than a capillary tube. The temperature sensing cylinder 1 is attached to the evaporator coil outlet (not shown) and transmits a pressure corresponding to the temperature of the coil outlet to the upper pressure chamber 3 of the diaphragm via the capillary tube 8. In addition, the pressure equalization hole 7 transmits the pressure at the evaporator coil outlet (in the case of external pressure equalization) or the evaporator inlet (in the case of internal pressure equalization) to the diaphragm lower pressure chamber 4,
Determine the position of the valve stem 6 by balancing the force of the spring 5,
It controls the flow rate of refrigerant. However, even in such thermostatic automatic expansion valves, there is a limit to the deformation of the diaphragm, and the signals that control the flow rate are all downstream (low-pressure) side signals of the expansion valve, and are not connected to the refrigeration cycle. If the condensing pressure drops significantly, the differential pressure before and after the valve becomes small, making the control system uncertain, making it impossible to supply the appropriate amount of refrigerant to the downstream side, and causing the refrigeration system to fail to achieve its full performance. The present invention was invented in view of the above-mentioned problems, and it is possible to flow an appropriate flow rate of refrigerant even if the condensing pressure decreases significantly. That is, an object of the present invention is to provide a refrigerant flow rate control device that is capable of controlling refrigerant flow rate over a wide operating range.

In order to achieve the above object, the present invention forms the flow path of the side leg refrigerant in a curved shape, and changes the flow path resistance by changing the curvature of the curved flow path in accordance with the pressure difference between high and low pressures of the refrigeration cycle. When the pressure difference becomes smaller, the curvature becomes thicker to reduce the flow path resistance.

The present invention will be described in detail below based on side views.

First, FIG. 2 shows a basic embodiment of the refrigerant control device of the present invention. Two movable plates 9.1o and a spring 11 are housed in a container 14 having an inlet/outlet opening 12.13. The movable plates 9.1o each have a small hole 15.16, which holes 15.16 are bored eccentrically at a distance X from each other. When the refrigerant flow control device having such a structure is used as a refrigerant flow control mechanism of a refrigeration cycle, the opening 12 is connected to the condenser force side and the opening 13 is connected to the evaporation pressure side. (The evaporation pressure is kept constant.) When the condensation pressure is high and the difference between high and low pressures is large, a large amount of refrigerant tries to flow downstream through the holes 15, causing the movable plate 9
As a result, as shown in FIG. 3, the movable plate 9 moves downstream, creating a displacement Δy1 in balance with the spring 11 (not shown), causing a large pressure difference between the movable plates 9 and 10. The distance is reduced to yl=3'0-Δy+ (yo is the distance between the plates 9 and 10 when no pressure is applied to the container 14).

At this time, since the small holes 15 and 16id are not on a straight line but are separated by a distance
5 to the small hole 16 with a small curvature, the flow resistance becomes large.

Next, consider the case where the condensing pressure drops significantly.

In this case, since the difference between high and low pressures is small, the flow rate of refrigerant flowing through the small holes 15 is small, and the pressure loss occurring before and after the movable plate 9 is small, so the pressure difference causes the right side plate 9 to be moved downstream. The force trying to displace it becomes smaller. As shown in FIG. 4, the displacement △y2 caused by the balance with the force of the spring 11 (not shown) is equal to the displacement △y1 when the condensation pressure is high.
Since it becomes smaller, the distance between movable plates 9 and 10 is y2=7
0-Δy2 (>y+), and the fluid flowing from the small hole 15 to the small hole 16 can flow with a large curvature as shown by the solid arrow, so the flow path resistance becomes small.

That is, while the conventional throttling mechanism has a characteristic that the flow rate passing through the throttling decreases when the differential pressure before and after the throttling decreases, the control device of the present invention has the characteristic that the flow rate passing through the throttling decreases when the differential pressure before and after the throttling decreases.
16) Characteristics when the above-mentioned refrigerant flow rate control device is incorporated into a refrigeration cycle, which can have the opposite characteristic that the flow rate passing through the throttle does not change even if the differential pressure before and after becomes small, but on the contrary, it increases. will be explained based on FIG.

In FIG. 5, the horizontal axis shows the differential pressure ΔP before and after the throttle, and the vertical axis shows the flow rate Gr passing through the throttle υ. Curve A shows the refrigeration cycle characteristics when the refrigerant flow rate is appropriately controlled according to the load, and generally has an upward trend to the left where a large refrigerant flow rate is required as the differential pressure becomes smaller. Curve B is the resistance characteristic of a general throttle mechanism, and shows an upward-sloping characteristic (Gr section, rKl) proportional to the square root of the differential pressure. The intersection a of these curves represents the differential pressure ΔPO1 refrigerant flow rate GrO at the design point.

Now, considering the case where the load situation changes, the condensing pressure decreases, and the differential pressure becomes Δp+, which is smaller than the differential pressure at the design point, the refrigerant flow rate required from the refrigeration cycle side is GA. , the flow rate of the aperture with the characteristic of the conventional curve B is GB (GB (GA), ΔG I=GA−
Due to the insufficient flow rate of GB refrigerant, the performance of the refrigeration cycle is significantly reduced. On the other hand, if the pressure difference in the low pressure of the refrigerant flow control device of the present invention becomes smaller, the flow path resistance decreases and the differential pressure Δ
Since the refrigerant flow rate of Gc can be made to flow with Pl, the insufficient flow rate ΔG2 = GA - Gc ((ΔGl), and compared to the case of using the conventional throttling mechanism, the insufficient flow rate can be reduced, so the refrigeration cycle Deterioration in performance can be prevented. By changing the diameter and eccentricity X of the small holes 15 and 16, it is possible to create embodiments with various characteristics.

Next, another embodiment is shown in FIG. This example has multiple @(
4@) movable plate 17a% 171) 1 t7c, 17
d and multiple flim (3 oka) springs t8aq t8b,
This is an example in which 18C is combined, and 4 movable plates 17a, +7
b% 17Cs By changing the number and position of small holes 19 provided in 17'i for each movable plate, and by changing the strength of each spring 18 aN I 8 bs I 8 C, various characteristics can be obtained. This makes it possible to approach the characteristic shown by A in FIG. In other words, it is possible to create a diaphragm mechanism that is close to the ideal.

Still another embodiment is shown in FIG. In this embodiment, the movable plate 9
．． The end face of 10 is shaped like a flange 9.10 to stabilize the position of the movable plate. (Illustration of the spring is omitted) Still another embodiment is shown in FIG. In this embodiment, a seal ring 20 (for example, a Teflon ring) is fitted around the outer circumference of the movable plate 9.10 to reduce leakage from the movable plate 9.10 and the inner wall of the container 14. (The spring is not shown.) As explained above, according to the present invention, even if the pressure difference between high and low pressures in the refrigeration cycle becomes small, the refrigerant flow rate does not decrease.
A throttling characteristic is obtained in which the refrigerant flow rate increases, and the characteristics and efficiency of the refrigeration cycle are greatly improved when the operating conditions of the refrigeration cycle change, especially when the condensing pressure decreases significantly. I can do it.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional thermostatic automatic expansion valve, and Fig. 2 shows an example of the refrigerant flow rate of the present invention. A cross-sectional view of the control device, FIGS. 3 and 4 are explanatory diagrams of the operation of the implementation ψ1j of FIG. 2, respectively.
Figure 5 is a diagram showing the characteristics of the refrigerant storage unit 1j control device, Figure 6
9 to 8 are cross-sectional views of the refrigerant flow rate control device showing other implementations f1j.
', 10'...Flange plate 11...Spring 12.
13...Opening 14...Container 15.16...
Small holes 17a, 171), 170, 17d...Movable plate 18a, 18bs 18a...Spring 19...
73% hole 20... Seal ring agent Patent attorney Sui 1) Li' Yasaya Yai Yaibai m Now hat Junyangsu Seki 2

Claims (1)

[Claims] A plurality of movable plates with small holes are placed in a container with openings connected to the high-pressure side and low-pressure side of the refrigeration cycle, with springs inserted between the movable plates so that they can slide inside the container. However, the small holes in the adjacent movable plate are provided at different positions, and the curvature of the curved flow path formed by the small holes changes according to the pressure difference between high and low pressures of the refrigeration cycle, and the above pressure difference A refrigerant flow rate control device characterized in that the curvature of the flow path increases as the curvature of the flow path decreases.