JPH0268456A - Cooling device - Google Patents

Abstract

PURPOSE:To improve a controlling characteristic of a cooling cycle by a method wherein when at least a thermal load is low, a variation of an opening area of a communication passage communicating between a high pressure side and a low pressure side of an expansion valve is made low. CONSTITUTION:In case that a discharging volume of a compressor is low, a pressure difference between a high pressure side and a low pressure side of an expansion valve 4 is low, a pressure difference valve 27 is not opened, only a main valve 13 is opened, a rate of variation of a degree of over-heating operation in respect to a variation of stroke is lowered, so that even if the degree of over-heating operation is varied due to a certain reason and the main valve 13 is substantially vibrated, the opening are is not varied much and a hunching is prevented. To the contrary, in case that an amount of discharging is increased as a thermal load is increased, a cooling capability is lacked due to the fact that the opening area is not increased even though a flow rate of coolant is tried to be adjusted only with the main valve 13. However, since a differential pressure of the coolant gas between its high pressure side and low pressure side is increased, the differential pressure valve 27 is also opened, a flow rate of the coolant flowing to the low pressure side is entirely increased and a lack of the cooling capability can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cooling device, and more particularly to an improvement in an expansion valve used in a cooling cycle having a variable capacity compressor.

(Prior Art) Recently, variable capacity compressors have been used in cooling cycles that are constructed by sequentially connecting a compressor, condenser, liquid receiver, expansion valve, and evaporator through piping. Even with such a cooling cycle, the expansion valve is disclosed in, for example, Japanese Patent Application Laid-open No. 6110506 or Japanese Utility Model Application No. 62-9.
As shown in Publication No. 3657, a main valve is provided in a communication passage that communicates the high pressure side leading to the discharge port of the compressor and the low pressure side leading to the suction port of the compressor, and this main valve controls the degree of superheating ( In order to maintain a constant amount of superheat (amount of superheat), a system is used that adjusts the aperture (opening area) of the communication path according to increases or decreases in heat load.

(Problem to be solved by the invention) For this reason, when the refrigerant flow rate is large, such as in a compressor whose capacity cannot be varied, the rate of change in the degree of superheat with respect to the change in the opening area of the expansion valve becomes small, as shown in Figure 6. However, when the discharge amount is small, the refrigerant flow rate decreases, so the rate of change in the degree of superheating with respect to the change in the opening amount becomes large. Therefore, if the degree of superheat fluctuates for some reason, the main valve vibrates in an attempt to maintain the predetermined degree of superheat, and in conventional expansion valves, the opening amount increases (varies) due to this vibration. If it is small, hunting occurs and the controllability of the cooling cycle becomes poor.

Therefore, an object of the present invention is to provide a cooling device that suppresses hunting when the discharge amount of the compressor is small and improves the controllability of the cooling cycle.

(Another Means to Solve the Problem) Therefore, the gist of the present invention is to construct a cooling cycle by sequentially connecting at least a variable capacity compressor, a condenser, an expansion valve, and an evaporator to the expansion valve. In a cooling device, the cooling device is provided with a communication path that communicates the high pressure side and the low pressure side, and a main valve that adjusts the degree of superheat of the evaporator by varying the opening area of the communication path so as to keep the degree of superheat of the evaporator constant. The present invention is characterized in that means is provided for reducing the change in the opening area of the communicating path at least when the heat load is small.

(Function) Therefore, when the degree of superheat of the evaporator fluctuates, the main valve operates in an attempt to maintain a predetermined degree of superheat, but if the heat load is small, the amount of change in the opening area of the communication passage slows down.
When the capacity of the compressor is small, large fluctuations in the opening area can be suppressed, and therefore, the problem described in item 1 can be achieved.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 2, an outline of the cooling cycle is shown.
, a temperature-operated expansion valve 4, and an evaporator 5 are connected by piping. The variable capacity compressor 1 is connected to an automobile engine (not shown) via an electromagnetic clutch 6.
Drive and stop are controlled by turning on and off the electromagnetic clutch 6. In addition, the capacity of the compressor is adjusted in relation to the heat load, and the smaller the heat load, the smaller the capacity is controlled. As a result, the discharge side (high pressure side) and suction side (low pressure side) are controlled approximately in proportion to the heat load. The differential pressure between the two sides) can be changed. In the condenser 2, the refrigerant gas discharged from the compressor 1 undergoes heat exchange with the air sent from the cooling fan 7, is condensed, is temporarily stored in the liquid receiver 3, becomes a liquid refrigerant, and is turned into a liquid refrigerant. 4, it becomes low temperature and low pressure moist steam, which is then sent to the evaporator 5 by the blower 8.
The refrigerant gas exchanges heat with the air from the refrigerant gas to become a refrigerant gas having a predetermined degree of superheating, and is sucked into the compressor 1 again.

In FIG. 1, a first embodiment of the expansion valve 4 is shown, in which a valve body 9 has a high pressure passage 10 and a low pressure passage 11 formed at right angles, and the high pressure passage 10 is connected to a liquid receiver 3 of a refrigeration cycle.
The low pressure passage 11 is also connected to the inlet pipe of the evaporator 5 of the refrigeration cycle. The high pressure passage 10 and the low pressure passage 11 are connected via a communication passage 12 formed in the valve body 9.

The main valve 13 has a main valve valve member 14, which includes a poppet-shaped valve body portion 14a and a stem portion 14b.
It is composed of. The valve body portion 14a is configured to sit on a valve seat 15 formed at the low-pressure side end of the communication passage 12 described above, and has an adjustment screw 16 screwed into the valve body 9.
It is pressed in three directions by the main valve spring 17, which is loaded between the main valve spring 17 and the main valve spring 17. The valve seat 15 and the portion of the valve body 14a that contacts the valve seat 15 are formed in a shape that has a steep slope and widens toward the end. Even if the main valve member 14 makes a large stroke compared to the above, the throttle (opening area) of the communication passage 12 does not change significantly. The stem portion 14b extends upward through the communicating path 12, and is inserted into the sliding hole 18. A sleeve 19 is lightly press-fitted into the upper end of the stem portion 14b. A sealing member 20 is provided between the bulging portion 31 of the portion 14b and the end of the sleeve 19.
is held, and this sealing member 20 slides through the sliding hole 18,
The second chamber 23b, which will be described below, is kept airtight.

The valve body portion 14a and the bulging portion 31 of the stem portion 14b have symmetrical flat surfaces 32a, 3 at opposing portions.
2b is formed to equalize the pressure received from the refrigerant gas in the high pressure passage 10, and to prevent the main valve valve member 14 from moving under this gas pressure.

The periphery of the diaphragm 21 is fixed by a cover body 22 caulked to the valve body 9 at the upper part of the valve body 9, and the space formed by the valve body 9 and the cover body 22 is divided into first and second chambers. It is divided into two parts, 23a and 23b. One end of the connecting pipe 24 is connected to the first chamber 23a, and the first chamber 23a is connected to one end of the connecting pipe 24.
The other end of 4 is connected to a temperature-sensitive cylinder provided on the outlet side of the evaporator 5, and the temperature of the first chamber 23 is adjusted according to the temperature on the outlet side of the evaporator 5.
The pressure at a is changed. Further, the second chamber 23b is connected to the low pressure side piping via an external pressure equalizing pipe 25, and is of a so-called external pressure equalizing type in which the pressure in the second chamber 23b is made equal to the pressure in the low pressure passage 11.

Therefore, the main valve valve member 14 moves to a position where the pressure relative to the temperature from the temperature sensing cylinder, the low pressure side refrigerant pressure from the external pressure equalizing pipe 25, and the pressing force of the main valve spring 17 are balanced, and the valve member 14 is connected. The flow rate of refrigerant passing through the passage 12 is adjusted to keep the degree of superheat of the evaporator 5 constant.

The main valve member 14 also includes a first horizontal hole 26a formed in the radial direction of the stem portion 14b, and a vertical hole 26b provided from the horizontal hole 26a to the lower end of the valve body portions 14,1.
, and a second horizontal hole 26C provided perpendicular to the vertical hole 26b, a differential pressure opening/closing passage 26 is formed, and a differential pressure valve 27 is provided in this differential pressure opening/closing passage 26.

The differential pressure valve 27 has a differential pressure valve valve member 30 disposed in the vertical hole 26b, and a spherical valve body portion 3 formed at the upper end thereof.
0a is seated on a differential pressure valve valve seat 33 formed inside the valve body portion 14a of the main valve valve member 14. A differential pressure valve spring 29 is elastically mounted between the spring receiver 28 screwed below the valve body 14a of the main valve valve member 14 and the base of the differential pressure valve valve member 30. The spring 29 keeps the valve body 30a of the differential pressure valve valve member 30 at a predetermined pressure PI (for example, 3 kg/c).
is pressed against the differential pressure valve seat 33.

Therefore, as shown in FIG. 4, in the differential pressure valve valve member 30, the differential pressure ΔP between the high pressure side and the low pressure side is
9, the pressure starts to lift downward, and the opening area increases as the differential pressure ΔP increases. Valve member 3 for differential pressure valve with stopper 28a
It is limited by regulating the lift amount of 0, and the main valve 13
The sum S2+S3 of the maximum opening area S2 of the differential pressure valve and the maximum opening area S3 of the differential pressure valve is made to match the maximum opening area SI of the conventional expansion valve (Sl = 32 + 33).

In the above configuration, when the discharge capacity of the compressor 1 is small, the pressure difference between the high pressure side and the low pressure side is small, the differential pressure valve 27 is not opened, only the main valve 13 is opened, and the differential pressure ΔP
As long as is smaller than P, the characteristics of the solid line in Fig. 3 are maintained (
Figure 5). For this reason, as shown in Figure 6, the rate of change in the degree of superheat with respect to the change in stroke is smaller than in the conventional case, as shown by the broken line, so the degree of superheat changes for some reason and the main valve vibrates greatly. However, the opening area does not change much, which prevents hunting.

On the other hand, when the discharge amount of the compressor 1 increases due to an increase in heat load, even if an attempt is made to adjust the refrigerant flow rate using only the main valve 13, the opening area will not become large, resulting in insufficient cooling capacity. However, in such a case, the differential pressure ΔP of the refrigerant gas between the high-pressure side and the low-pressure side increases, so the differential pressure valve 27 also opens, and the overall flow rate of refrigerant flowing to the low-pressure side increases, resulting in the characteristic line in FIG. 5. moves upward.

Thereby, even if the discharge amount increases, insufficient cooling capacity can be prevented.

In FIG. 7, a second embodiment of the expansion valve 4 is shown, in which the valve body 9 is formed with a high pressure passage 10 divided into two and a common low pressure passage 11, which are connected to a communication passage 12.35. connected via. A communication passage 12 connecting one shunt 10a of the high-pressure passage 10 and the low-pressure passage 11 is opened and closed by a main valve 13 similar to the embodiment described above, and connects the other shunt 10b of the high-pressure passage IO and the low-pressure passage 11. The connecting communication path 35 is opened and closed by a differential pressure valve 27 described below.

The differential pressure valve 27 has a differential pressure valve valve member 30, and this valve member 30 has a rod 14C extending downward from the main valve valve member 14.
is fitted externally. A spring receiver 37 is brought into contact with the lower end of the rod 14C, and a spring 39 is interposed between the spring receiver 37 and a lid 38 that closes off the valve body 9.
0 is pressed upward together with the main valve valve member 14. A valve seat body 40 is disposed in the communication passage 35 and extends downward through a through hole 41 formed in the valve seat body 40 of the rod 14C. This valve seat body 40 is
- The valve seat 43 can be slid in the communication path 35 via the ring 42, and the valve seat 43 on which the differential pressure valve valve member 30 is seated is formed around the lower end of the through hole 41. The valve seat 43 and the differential pressure valve member 30 are strongly pressed by the differential pressure valve spring 45 provided between the step portion 44 formed in the communication passage 35 and the valve seat body 40 .

Even in this configuration, when the differential pressure between the high pressure side and the low pressure side is small, that is, when the discharge amount of the compressor is small, only the main valve 13 opens, and as shown in Fig. 8, even if the stroke increases, the opening area remains small. does not become too large, so hunting can be prevented. When the differential pressure is large, that is, when the discharge amount of the compressor is large, the valve seat body 40 is pushed upward and the differential pressure valve 27 is also opened, so the opening area becomes large and cooling is facilitated. Capacity is ensured.

In FIG. 9, a third embodiment of the expansion valve 4 is shown, and in this expansion valve 4, the main valve valve member 14 and the differential pressure valve valve member 30 are composed of ball valve bodies 14d, 30d and the ball valve body. It is composed of rotors F14e and 30e extending from 14d and 30d. A valve seat body 50 for the main valve is fixedly mounted in the valve body 9, and a communication passage 51 formed in the valve seat body 50 for the main valve has a valve member 14 for the main valve at its high pressure side end. A valve seat 52 is formed on which the ball valve body 14d is seated.

The main valve valve member 14 is pressed upward by a main valve spring 53 disposed on the high pressure side.
e, it extends upward through the communication path 51 and abuts against a stem 54 that is press-fitted into the sleeve 19 .

Further, a barrel 56 is fixed to the main valve seat body 50, and a differential pressure opening/closing passage 59 is formed via a differential pressure valve seat body 57 provided on the barrel 56 and an adjustment screw 58. .

The valve seat body 57 for the differential pressure valve is slidably inserted into a hole 60 formed in the barrel 56, and is pressed downward by a spring 61 disposed between the adjustment screw 58 and the valve seat body 57. The base portion 57a is brought into contact with a stepped portion within the barrel 56.

A valve seat 62 is formed at the high-pressure side end of the differential pressure valve seat body 57, and a differential pressure valve spring 63 in which the ball valve body 30d of the differential pressure valve valve member 30 is disposed on the high pressure side is formed on the valve seat 62.
is pressed by.

Further, the rod 30e of the differential pressure valve member 30 extends upward through the differential pressure opening/closing passage 59 and is in contact with the stem 54.

The diameter of the rod 14e of the main valve valve member 14 is the same as that of the third valve member 14.
It is predetermined to obtain the characteristics shown by the solid line in the figure.
Moreover, when the differential pressure is small, the main valve valve member 1 of the main valve 13
4 is not stroked by a predetermined amount β or more, the differential pressure valve 27 will not open.

However, when the differential pressure is small, only the main valve 13 is opened and the opening area gradually increases until the stroke amount reaches a predetermined amount l, as shown in FIG. If the pressure difference is higher than that, the differential pressure valve 27 will also open and the opening area will increase rapidly.
The differential pressure valve opens without a single stroke, and the opening area rapidly increases, increasing the flow rate of refrigerant to the low pressure side.

In FIG. 11 a fourth embodiment of the expansion valve 4 is shown. This expansion valve 4 has a main valve 1 of the same structure inside the valve body 9.
3 and an auxiliary valve 70 are provided, and each valve has characteristics as shown by the solid line in FIG. ing. The high pressure connection path 71 has a differential pressure opening/closing mechanism 73.
is provided, and this differential pressure opening/closing mechanism 73 is connected to connecting paths 71 and 72.
The valve body 75 is slidably disposed in the insertion hole 74, and the valve body 75 is installed on the low pressure connection path side. The passage 71 is biased in the direction of closing, and moved to a position where the refrigerant gas pressure on the high pressure side and the spring pressure are balanced.

Each valve member 14 that constitutes the main valve 13 and the sub-valve 70
．． 77 is lightly press-fitted into the sleeves 19.78, and each sleeve 19.78 is separately abutted on diaphragms 21 and 79 provided on the valve body 9. The first chamber 23 is formed by the diaphragm and the lid 22°80.
a, 81a is connected to the diaphragm 2 via the communication pipe 82.
1.79 and the second chamber 23b, 81 formed by the valve body 9
b are connected to each other via a pressure equalizing passage 83, and are connected to the main valve 13.
and the sub-valve 70 are opened and closed at the same time.

In such a configuration, when the differential pressure is small, the high pressure connecting path 71 is closed by the valve body 75 of the differential pressure opening/closing mechanism 73, so the refrigerant flows only from the main valve 13, and when the differential pressure is large, the high pressure connecting path 71 is closed. In this case, the valve body 75 is moved by the spring 76 due to the gas pressure on the high pressure side.
The refrigerant gas is pushed down against the main valve 13 and the sub valve 7o.
flows to the low pressure side through both. Therefore, also in this case, the characteristics shown in FIG. 8 are obtained.

In FIG. 12 a fifth embodiment of the expansion valve 4 is shown. In this expansion valve 4, the outer shape of the valve body portion 14a of the main valve valve member 14 constituting the main valve 13 is slightly different from that of the first embodiment, and The flat surface 32b of the body portion 14a is made large so that the differential pressure between the high pressure side and the low pressure side directly affects the flat surface 32b. Therefore, if the rate of change in the opening area with respect to the stroke change of the main valve valve member 14 is made smaller than in the past, the 13th
As can be seen from the figure, when the differential pressure is small, the stroke amount is also small, so the opening area is not very large, and when the differential pressure is large, the stroke amount is also large, so the opening area becomes large. Therefore, in order to increase the opening area, it is necessary to increase the stroke amount than before, but the same effect as in the previous embodiments can be obtained without changing the change characteristics of the opening area depending on the differential pressure. It's something you can get]
5.

In FIG. 14 a sixth embodiment of the expansion valve 4 is shown,
A spring receiver 90 is installed on the low pressure side of the conventional main valve valve member 14.
A main valve spring 17 is mounted between the spring receiver 90 and the adjusting screw 16, and the main valve spring 17 presses the valve body portion 14a toward the valve seat 15. Further, an adjustment spring 91 is elastically mounted between the valve body portion 9 and the spring receiver 90, and this adjustment spring 9
1, the valve body portion 14a is pressed in a direction away from the valve seat 15.

Therefore, the pressure difference Δ between the first chamber 23a and the second chamber 23b
When P is small and the main valve valve member 14 is not refluxed much, the opposing forces of the main valve spring 17 and the adjustment spring 91 are applied to the spring receiver 90, as shown in FIG. Compared to the conventional expansion valve without the adjustment spring 91, even if ΔP'' changes somewhat, the fluctuation of the main valve valve member 14 can be suppressed to a small level. On the other hand, when ΔP'' becomes large and the stroke amount of the main valve valve member 14 becomes large, the adjustment spring 91 is fully extended and no longer presses the spring receiver 9o, so it maintains the same characteristics as the conventional expansion valve. have

(Effects of the Invention) As described above, according to the present invention, when the heat load is small, the change in the opening area of the communication passage of the expansion valve is reduced, so that when the capacity of the compressor is small, large fluctuations in the opening area can be prevented. This prevents hunting and improves the controllability of the cooling cycle.

[Brief explanation of the drawing]

FIG. 1 shows the first expansion valve used in the cooling device of the present invention.
Fig. 2 is a configuration diagram showing the cooling cycle, Fig. 3 is a diagram showing the characteristics of the opening area with respect to the stroke amount of the main valve, and Fig. 4 shows the high pressure side and low pressure side of the differential pressure valve. Figure 5 is a diagram showing the opening area characteristics of the entire expansion valve, Figure 6 is a diagram showing the superheat degree characteristics, and Figure 7 is a diagram showing the characteristics of the opening area of the entire expansion valve. A cross-sectional view showing a second embodiment of an expansion valve used in a cooling device, FIG. 8 is a line diagram showing characteristics of the opening area of the expansion valve in the above, and FIG. 9 shows a third embodiment of the expansion valve. A sectional view, FIG. 10 is a diagram showing the characteristics of the opening area of the expansion valve in the same as above, the 11th leap is a sectional view showing the fourth embodiment of the expansion valve, and FIG. 12 is a diagram showing the fifth embodiment of the expansion valve. 13 is a diagram showing the characteristics of the opening area of the expansion valve in the same as above, FIG. 14 is a sectional view showing the sixth embodiment of the expansion valve, and FIG. 15 is a diagram showing the opening area of the expansion valve in the same as above. FIG. 3 is a diagram showing characteristics of area. 1...Compressor, 2..., Condenser, 401. Expansion valve, 5... Evaporator, 12... Communication path, 13... Main valve. Patent applicant: Diesel Equipment Co., Ltd. 108
Leprosy storage - Condyle mouth 18 houses 13 Figure 15 Figure 14

Claims (1)

[Claims] At least a variable capacity compressor, a condenser, an expansion valve, and an evaporator are sequentially connected via piping to form a cooling cycle, and the expansion valve has a communication passage communicating its high pressure side and low pressure side;
In a cooling device that is provided with a main valve that adjusts the opening area of the communication passage to maintain a constant degree of superheating of the evaporator, the change in the opening area of the communication passage is controlled at least when the heat load is small. A cooling device characterized by being provided with a means for reducing the size.