JP3146722B2 - Expansion valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an expansion valve.
In particular, the present invention relates to an expansion valve used for a refrigeration cycle of an automotive air conditioner.

[0002]

2. Description of the Related Art Conventionally, an expansion valve for a refrigeration cycle of this type constantly controls the superheat of the refrigerant at the evaporator outlet in accordance with fluctuations in the cooling load determined by the temperature inside the vehicle, the outside air temperature, the number of occupants, humidity, and the like. It is configured to perform superheat control for supplying an appropriate amount of refrigerant to the evaporator to keep it.

For example, when the temperature in the cabin is high and the cooling load is large, the superheat of the refrigerant at the evaporator outlet also increases unless the opening of the expansion valve is changed. And the amount of refrigerant supplied to the evaporator is increased. On the other hand, when the cooling load becomes small, the superheat of the refrigerant at the evaporator outlet also becomes low, so the amount of the refrigerant supplied to the evaporator is reduced by narrowing the opening of the expansion valve to keep the superheat constant. .

[0004]

As described above, in the superheat constant control, when the cooling load is small, the degree of opening of the expansion valve is reduced, and since the high pressure of the refrigerant is also reduced, the flow rate of the refrigerant that can flow is reduced. Would. When the low pressure is kept constant as shown in FIG. 10, the high pressure becomes 15 → 10 →
As the pressure decreases to 5 kgf / cm ² G, the differential pressure across the expansion valve decreases, and the flow rate of the refrigerant that can flow a → b → c decreases even when the valve is fully opened.

Particularly, in an air conditioner for an automobile, as in the case of the inside air mode in winter, the inside air introduced into the evaporator is at a high temperature of about 25 ° C., and the cooling load of the evaporator is high. The outside air is low and the condenser has a low temperature and low pressure,
Since the high pressure of the refrigerant introduced into the expansion valve is reduced, the differential pressure across the expansion valve is reduced, and the same superheat cannot ensure the same flow rate as when the high pressure is high. Therefore, the amount of the refrigerant flowing into the compressor also decreases, and it becomes difficult to secure the circulation rate of the lubricating oil mixed in the refrigerant, and the sliding parts of the compressor may not be sufficiently lubricated and may cause burning. .

For this reason, it is possible to increase the degree of opening of the expansion valve in the same superheat by changing the temperature-sensitive cylinder characteristics of the expansion valve, increase the flow rate of the refrigerant, and maintain the lubrication of the sliding portion of the compressor. However, when the high pressure in summer is high, the gain of the flow rate for the superheat becomes very high, and hunting occurs, which is difficult to realize. Here, the gain of the flow rate is gain = flow rate / superheat. On the other hand, in order to increase the degree of opening of the expansion valve with the same gain, the flow rate of the refrigerant cannot be increased unless the balance is at a large level of superheat, so that the efficiency and temperature distribution of the evaporator are deteriorated, and Since the refrigerant cannot be heated to a temperature higher than the temperature, there is a limit even if the superheat is increased.

[0007] Therefore, it is desired to achieve a balance with a lower superheat . However, as shown at point d in FIG. In view of the above problems, the present invention can supply a sufficient amount of refrigerant flow even when the cooling load is small, such as in winter, when the high pressure of the refrigerant is low, and at the same time, ensures the amount of lubricating oil to be returned to the compressor. It is an object of the present invention to provide an expansion valve that can prevent such an expansion valve.

[0008]

In order to achieve the above object, an expansion valve according to the present invention is an expansion valve constituting a refrigeration cycle together with a compressor, a condenser and an evaporator. An expansion valve body to be formed, an inlet refrigerant passage formed in the expansion valve body, communicating with the condenser and introducing a refrigerant condensed in the condenser, and formed in the expansion valve body, A flow passage restricting portion for adiabatically expanding the refrigerant introduced from the inlet refrigerant passage, and an outlet refrigerant passage formed in the expansion valve body and supplying the refrigerant adiabatically expanded in the flow passage restricting portion to the evaporator. Formed in the expansion valve body
One end is connected to the evaporator, and the other end is the compressor
Open and close the suction refrigerant passage connected to the
Made of a material having good heat conductivity,
A temperature sensing rod movably disposed through a refrigerant passage;
The evaporator passing through the suction refrigerant passage by a temperature sensing rod
A heat-sensitive chamber to which the temperature of the refrigerant at the outlet side is transmitted;
The pressure of the refrigerant at the evaporator outlet side passing through the medium passage is introduced.
Pressure equalizing chamber, and the pressure of the heat-sensitive chamber and the pressure equalizing chamber.
A pressure responsive member for moving the temperature sensing rod;
A pressure chamber that is disposed adjacent to the hot rod, and into which the pressure of the high-pressure side refrigerant upstream of the flow path constriction section is introduced, and as the pressure of the high-pressure refrigerant decreases, the valve element opens in the opening direction. The pressure chamber employs technical means for applying the pressure of the high-pressure side refrigerant to the temperature sensing rod so as to receive a force.

[0009]

According to the present invention, by employing the above means, when the cooling load is large and the compressor operates at a high load and the high pressure of the refrigerant introduced into the expansion valve becomes high, the expansion valve evaporates. The valve opening is controlled so that the superheat of the refrigerant at the outlet of the vessel is kept within a certain range (5 ° C. to 10 ° C.). On the other hand, when the cooling load is small, the compressor operates at a low load, and the high pressure introduced to the expansion valve decreases, and the opening of the flow path restricting portion increases due to the force in the direction in which the valve element opens. Therefore, even if the high-pressure pressure of the refrigerant decreases, the flow rate of the refrigerant introduced into the evaporator does not significantly decrease as shown in FIG. Therefore, even when the high pressure is low in winter or the like, a sufficient flow rate of the refrigerant can be supplied to the evaporator, and sufficient dehumidifying performance and a good discharge temperature distribution can be obtained. At the same time, it is possible to secure the flow rate of the refrigerant necessary for lubrication of the compressor and prevent burning of the compressor.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to an expansion valve of an automotive air conditioner will be described below with reference to the drawings.

FIG. 1 schematically shows a refrigeration cycle of an air conditioner for a vehicle according to an embodiment. Automotive air conditioners
The system includes a compressor 1, a condenser 2, a receiver 3, an expansion valve 4, and an evaporator 5.

The compressor 1 is driven by receiving the rotational force of an automobile engine via an electromagnetic clutch (not shown). Condenser 2
The high-temperature and high-pressure gaseous refrigerant adiabatically compressed by the compressor 1 is condensed by heat exchange with air outside the vehicle compartment to form a liquid refrigerant. The receiver 3 has a built-in dryer (not shown) for temporarily storing the liquid refrigerant condensed in the condenser 2 and removing moisture and dust in the refrigerant. The expansion valve 4 adiabatically expands the liquid refrigerant into a low-temperature and low-pressure mist refrigerant. The evaporator 5 vaporizes this mist refrigerant by heat exchange with air sent into the vehicle interior.

In the expansion valve 4, a liquid refrigerant passage 8 communicating with the condenser 2 via the receiver 3 is formed substantially in the center of the expansion valve body 6. Further, a mist-like refrigerant passage 9 for supplying a refrigerant to the evaporator 5 is formed in the expansion valve body 6 at a position slightly below the liquid refrigerant passage 8 and at a position facing the passage 8. The liquid refrigerant passage 8 and the mist-like refrigerant passage 9 constitute an inlet refrigerant passage and an outlet refrigerant passage, respectively.
A valve chamber 7 is formed between the liquid refrigerant passage 8 and the mist refrigerant passage 9. An expansion orifice 10 constituting a flow path restricting portion for adiabatically expanding the refrigerant is provided at an upper portion of the valve chamber 7. The liquid refrigerant passage 8 and the mist-like refrigerant passage 9 are connected via the expansion orifice 10 and the valve chamber 7. Communicating.
On the valve chamber 7 side of the expansion orifice 10, a valve seat 11 is formed.

An adjustment screw 14 having a cylindrical portion 14a at an upper portion also serving as a cap is screwed below the valve chamber 7, and is fixed to the expansion valve body 6 by a hexagon screw 15. Inside the cylindrical portion 14a of the adjusting screw 14, an aluminum spool 12 having a bottomed cylindrical shape and having a circular convex portion 12a at the bottom is provided so as to be vertically movable. A spool holder 37 is provided above the cylindrical portion 14a of the adjusting screw 14 to prevent the spool 12 from moving too far upward. This spool 12 constitutes the valve support member according to the first aspect.

A pressure chamber 13 is formed by the spool 12 and the adjusting screw 14. The pressure chamber 13 has a communication hole 16 opened in the cylindrical portion 14 a of the adjusting screw 14, a space 18 defined by the adjusting screw 14 and the expansion valve body 6, and an introduction hole 17 opened in the expansion valve body 6. It communicates with the liquid refrigerant passage 8 through the above. Therefore, the pressure chamber 13 is filled with the liquid refrigerant before being adiabatically expanded by the expansion orifice 10. Further, since the spool 12 is provided with the circular projection 12a as described above, the volume of the pressure chamber 13 filled with the liquid refrigerant is always ensured even when the spool 12 is lowered to the lowest point.

A compression coil spring 19 is disposed inside the cylinder of the spool 12, and a spring seat 20 is attached to an upper end of the compression coil spring 19. And the valve seat 11
The spherical valve element 2 is provided on the spring seat 20 so as to face from below.
1 is fixed to open and close the expansion orifice 10.

Therefore, the valve element 21 is supported by the spool 12 and pressed against the valve seat 11 by the urging force of the compression coil spring 19. Then, the position of the spool 12 determined by the set length of the compression coil spring 19 by the adjusting screw 14 and the pressure difference between the pressure of the atomized refrigerant in the valve chamber 7 and the pressure of the liquid refrigerant in the pressure chamber 13 is determined with respect to the valve seat 11. The pressing force or the positional relationship of the valve body 21 is determined. The adjusting screw 14 has an O-ring 22
Is provided, and the airtightness in the valve chamber 7 is maintained.

At a position above the liquid refrigerant passage 8 and the mist refrigerant passage 9 in the expansion valve body 6, a low-pressure refrigerant passage 23 constituting a suction refrigerant passage is formed so as to penetrate therethrough. One end of the low-pressure refrigerant passage 23 is connected to the compressor 1.
And the compressor 1 is connected to the liquid refrigerant passage 8 via the condenser 2 and the receiver 3. The other end of the low-pressure refrigerant passage 23 is connected to the evaporator 5, and the evaporator 5 is connected to the mist refrigerant passage 9.

A screw hole 24 is formed in the upper part of the expansion valve body 6, and a lower housing 25 is screwed into the screw hole 24 via an O-ring 26 in a state of keeping airtight. An upper housing 28 is disposed and fixed above the lower housing 25 with a diaphragm 27 which is displaced in response to a thin stainless steel pressure. And
A heat-sensitive chamber 29 is formed above the diaphragm 27 in the lower housing 25 and the upper housing 28, and a pressure equalizing chamber 30 including the screw hole 24 is formed below the diaphragm 27. Further, a capillary 36 is attached to the upper part of the thermosensitive chamber 29, and the thermosensitive chamber 29 and the capillary 36 have an R as a temperature responsive body.
Twelve refrigerants are sealed.

A first plunger hole 31a is formed in the expansion valve body 6 upward from the center of the low-pressure refrigerant passage 23, and the first plunger hole 31a is formed between the pressure equalizing chamber 30 and the low-pressure refrigerant passage. It communicates with the refrigerant passage 23.

A second plunger hole 31b is formed downward from the center of the low-pressure refrigerant passage 23 so as to face the first plunger hole 31a, and a lower end of the second plunger hole 31b is formed. A rod hole 32 is formed between the liquid refrigerant passage 8. A temperature-sensitive rod 33 made of aluminum is vertically movably disposed in the plunger holes 31a and 31b. A stopper 33a at the upper end of the temperature-sensitive rod 33 is disposed in the pressure-equalizing chamber 30 so that a diaphragm is provided. 27 is in contact with the lower surface. The center of the temperature sensing rod 33 is exposed inside the low-pressure refrigerant passage 23. Further, the low-pressure refrigerant passage 23, the liquid refrigerant passage 8, and the mist-like refrigerant passage 9 are kept airtight by an O-ring 34 mounted on a temperature sensing rod 33.

An operating rod 35 made of stainless steel is vertically movably disposed inside the rod hole 32.
Has an upper end in contact with the temperature sensing rod 33, an intermediate portion exposed in the liquid refrigerant passage 8, and a lower end in contact with the valve body 21 in the expansion orifice 10. The control mechanism for controlling the opening and closing of the valve element 21 by the diaphragm 27, the heat sensing chamber 29, the pressure equalizing chamber 30, the temperature sensing rod 33, the operating rod 35, and the like is configured.

Next, the operation of this embodiment in the above configuration will be described with reference to FIG. The high-temperature and high-pressure gaseous refrigerant adiabatically compressed by the compressor 1 of the refrigeration cycle is condensed by the condenser 2 to become a liquid refrigerant, and then introduced into the liquid refrigerant passage 8 of the expansion valve 4 via the receiver 3. You. Further, the liquid refrigerant passes through the expansion orifice 10 and is adiabatically expanded at this time to become a low-temperature mist refrigerant and introduced into the valve chamber 7. Then, this refrigerant passes through the mist refrigerant passage 9 from the inside of the valve chamber 7 and is introduced into the evaporator 5 to be vaporized to become a gaseous refrigerant. Further, the gaseous refrigerant discharged from the evaporator 5 returns to the compressor 1 again through the low-pressure refrigerant passage 23.

On the other hand, the temperature sensing rod 33 includes the spring seat 20 and the valve body 21.
And by the compression coil spring 19 via the operating rod 35. Therefore, the expansion orifice 1
The position of the valve body 21 with respect to the valve seat 11 that determines the opening degree of 0 is maintained at a position where the urging force of the compression coil spring 19, the refrigerant pressure in the pressure equalizing chamber 30, and the gas pressure in the heat sensitive chamber 29 are balanced. Dripping. The pressure of the refrigerant in the pressure equalizing chamber 30 is the pressure of the gaseous refrigerant evaporated in the evaporator 5.

Since the temperature-sensitive rod 33 is exposed in the low-pressure refrigerant passage 23, the heat of the gaseous refrigerant passing through the low-pressure refrigerant passage 23 is reduced by the aluminum temperature-sensitive rod 33 having a high thermal conductivity. Through the diaphragm 27, and further transmitted from the diaphragm 27 to the refrigerant of R12 in the heat-sensitive chamber 29, and the refrigerant is liquefied and gasified. Therefore, the pressure in the heat-sensitive chamber 29 changes according to the refrigerant temperature at the outlet side of the evaporator 5, and the pressure is changed via the diaphragm 27 to the temperature-sensitive rod 3.
3 acts on the upper surface and further acts on the operating rod 35. As a result, the opening and closing of the valve body 21 is controlled, and the superheat is controlled so that the superheat of the refrigerant at the outlet of the evaporator 5 becomes constant.

The operation of the spool 12 disposed in the valve chamber 7 will be described with reference to FIGS.
As shown in FIG. 2, the displacement amount of the spool 12 changes linearly due to a pressure difference ΔP between the high pressure P ₁ of the liquid refrigerant in the liquid refrigerant passage 8 and the low pressure P ₂ of the mist refrigerant in the valve chamber 7. I do.
Note that the differential pressure ΔP is represented by the following equation.

[0027]

ΔP = P ₁ −P _{2 In} this embodiment, when the differential pressure ΔP is 2 kgf / cm ² or more,
The upper portion of the spool 12 is located at the uppermost point where it contacts the spool retainer 37, and when the differential pressure ΔP is 1 kgf / cm ² or less, the lower surface of the convex portion of the spool 12 contacts the upper surface of the cylindrical portion of the adjusting screw 14. It is set to be located at the lowest point.

Therefore, as shown in FIG. 3, when the load is medium and high, the compressor 1 operates at a high load, the high pressure P _{1 of the} liquid refrigerant supplied from the condenser 2 is high, and the differential pressure ΔP is 2 kgf / cm.
² and the spool 12 remains stopped at the highest point, but at low load, the compressor 1 operates at low load, the low pressure P _{1 of the} liquid refrigerant decreases, and the differential pressure ΔP becomes 2 kgf / cm ²
When it becomes less than 1, the spool 12 moves downward, so that the valve body 21 moves in the opening direction via the compression coil spring 19, and as a result, the opening degree of the expansion orifice 10 increases, and the flow rate of the refrigerant decreases. More.

As described above, when the medium pressure is high and the high pressure P ₁ of the liquid refrigerant is high and the differential pressure ΔP is 2 kgf / cm ² or more, the spool 12 remains stopped at the uppermost point and does not move downward. The body 21 opens and closes the expansion orifice 10 in accordance with the displacement of the diaphragm 27.

For example, when the temperature in the passenger compartment increases and the cooling load increases, the temperature of the refrigerant flowing through the low-pressure refrigerant passage 23 also increases. Then, R12 in the heat-sensitive chamber 29 that has received heat transfer via the temperature-sensitive rod 33 and the diaphragm 27 is gasified, and the diaphragm 27 is displaced downward. This displacement is the temperature sensing rod 3
3, transmitted to the operating rod 35, the valve body 21 moves downward, and as a result, the opening degree of the expansion orifice 10 increases, the amount of refrigerant flowing into the inlet of the evaporator 5 increases, and the refrigerant at the evaporator outlet increases. Is kept at 5 ° C to 10 ° C. on the other hand,
When the vehicle interior temperature decreases and the cooling load decreases, the temperature of the refrigerant flowing through the low-pressure refrigerant passage 23 also decreases. As a result, R12 of the heat sensitive chamber 29 is liquefied, and the operating rod 35 moves upward to reduce the opening degree of the expansion orifice 10, reduce the flow rate of the refrigerant toward the inlet of the evaporator 5, and reduce the refrigerant flow at the evaporator outlet. Keep the heat at 5-10 ° C.

Next, the high pressure P ₁ of the liquid refrigerant is low and the differential pressure Δ
The operation at a low load when P becomes less than 2 kgf / cm ² will be described. When the cabin temperature is low and the cooling load is small, the compressor 1
Becomes a low-load operation, and the temperature and pressure of the liquid refrigerant supplied from the condenser 2 to the expansion valve 4 decrease. Accordingly, the differential pressure ΔP between the pressure chamber 13 and the valve chamber 7 decreases, and when ΔP becomes less than 2 kgf / cm ² , the spool 12 moves downward, the valve element 21 moves in the opening direction, and the evaporator 5 can increase the refrigerant flow rate on the inlet side. The amount of displacement of the spool 12 is determined by the differential pressure ΔP as shown in FIG. Then, the superheat of the refrigerant at the outlet of the evaporator decreases as the spool 12 is located at a lower position, eventually reaches 0 ° C., and the refrigerant introduced into the evaporator becomes a gas-liquid two-phase refrigerant that has not completely evaporated.

In this way, the flow rate of the refrigerant is adjusted so that the amount of lubricating oil returned to the compressor 1 can be ensured at a low load, and the superheat of the refrigerant at the evaporator outlet is reduced by the increase in the refrigerant flow, but the cooling load is increased. Is not a problem because it is small. Therefore, the supply of the lubricating oil to the compressor 1 is reliably performed, and there is no risk of burning.

Here, when the load is low, more refrigerant than necessary is sent to the evaporator 5 by the action of the spool 12, but the excess refrigerant is not evaporated in the evaporator 5 and There is no problem in cooling performance only by returning the liquid refrigerant to 1. Further, since the ratio of the liquid refrigerant flowing into the compressor to the gaseous refrigerant is sufficiently small, there is no fear of liquid compression in the compressor 1.

In the first embodiment described above, the box-type expansion valve in which the low-pressure refrigerant passage is integrated has been described. However, an expansion valve having no low-pressure refrigerant passage may be used. For example,
The expansion valve 4 of the first embodiment is an external pressure equalizing type which takes the refrigerant pressure at the evaporator outlet as the pressure of the pressure equalizing chamber 26, but is an internal pressure equalizing type expansion valve which takes the refrigerant pressure at the evaporator inlet. May be. Further, a type in which a heat-sensitive cylinder for detecting heat transferred to the heat-sensitive chamber 29 is provided at the tip of the capillary 36 may be used. Furthermore, the expansion valve of the present invention can be used not only for a cycle via a receiver between the condenser and the expansion valve, but also for a cycle having an accumulator for directly connecting the condenser and the expansion valve and separating gas and liquid at the evaporator outlet. It can also be applied to the refrigeration cycle. Further, a variable displacement compressor may be used.

Next, a second embodiment of the present invention will be described. FIG. 4 schematically shows a refrigeration cycle of the automotive air conditioner according to the second embodiment, which includes a compressor 1, a condenser 2, a receiver 3, an expansion valve 4, and an evaporator 5.

In the expansion valve 4, a liquid refrigerant passage 8 that communicates with the condenser 2 via the receiver 3 is formed below the expansion valve body 6. Further, a mist-like refrigerant passage 9 for supplying a refrigerant to the evaporator 5 is formed in the expansion valve body 6 at a position slightly above the liquid refrigerant passage 8 and at a position opposed to the passage 8. These liquid refrigerants 8
The mist refrigerant passage 9 constitutes an inlet refrigerant passage 8 and an outlet refrigerant passage according to the first aspect, respectively.

A valve chamber 7 communicating with the liquid refrigerant passage 8 is formed slightly below the center of the expansion valve body 6. An expansion orifice 10 for adiabatically expanding the refrigerant is provided above the valve chamber 7, and the valve chamber 7 and the mist-like refrigerant passage 9 communicate with each other through the expansion orifice 10. On the valve chamber 7 side of the expansion orifice 10, a valve seat 11 is formed. An adjustment screw 40 having a cylindrical concave portion 40 a on the upper surface also serving as a cap is screwed below the valve chamber 7, and is fixed to the expansion valve body 6 by a hexagon screw 15.

A compression coil spring 19 is disposed in the cylindrical recess 40 a of the adjusting screw 40, and a spring seat 20 is attached to an upper end of the compression coil spring 19. A spherical valve element 21 is spot-welded to the spring seat 20 so as to oppose the valve seat 11 from below to open and close the expansion orifice 10. Therefore, the valve element 21 is pressed against the valve seat 11 by the urging force of the compression coil spring 19. The pressure contact force or the positional relationship of the valve body 21 to the valve seat 11 is determined by the set length of the compression coil spring 19 by the adjusting screw 40. The adjusting screw 40 is provided with an O-ring 22 to maintain airtightness in the valve chamber 7.

At a position above the liquid refrigerant passage 8 and the mist-like refrigerant passage 9 in the expansion valve body 6, a low-pressure refrigerant passage 23 constituting a suction refrigerant passage according to the third aspect is formed so as to penetrate therethrough. One end of the low-pressure refrigerant passage 23 is connected to the compressor 1, and the compressor 1 is connected to the liquid refrigerant passage 8 via the condenser 2 and the receiver 3. The other end of the low-pressure refrigerant passage 23 is connected to the evaporator 5, and the evaporator 5 is connected to the mist refrigerant passage 9.

A screw hole 24 is formed in the upper part of the expansion valve body 6, and a lower housing 25 is screwed into the screw hole 24 via an O-ring 26 in a state of maintaining airtightness. An upper housing 28 is disposed and fixed above the lower housing 25 with a diaphragm 27 which is displaced in response to a thin stainless steel pressure. And
A heat-sensitive chamber 29 is formed above the diaphragm 27 in the lower housing 25 and the upper housing 28, and a pressure equalizing chamber 30 including the screw hole 24 is formed below the diaphragm 27. A capillary 36 is mounted on the upper part of the heat-sensitive chamber 29, and the heat-sensitive chamber 29 and the capillary 36 are filled with activated carbon that adsorbs or desorbs the gas inside according to the temperature.

A first plunger hole 31a is formed in the expansion valve body 6 from the center of the low-pressure refrigerant passage 23 upward, and the first plunger hole 31a is formed between the pressure equalizing chamber 30 and the low-pressure refrigerant passage. It communicates with the refrigerant passage 23.

Further, a second plunger hole 31b is formed downward from the center of the low-pressure refrigerant passage 23 so as to face the first plunger hole 31a, and a lower end of the second plunger hole 31b is formed. Rod holes 32 a and 32 b are formed between the valve chamber 7 and the valve chamber 7 at positions not intersecting with the mist refrigerant passage 9. A temperature-sensitive rod 33 made of aluminum is vertically movably disposed in the plunger holes 31a and 31b. A stopper 33a on the upper part of the temperature-sensitive rod 33 is disposed in the pressure equalizing chamber 30 and has a diaphragm. 27 is in contact with the lower surface. The center of the temperature sensing rod 33 is exposed inside the low-pressure refrigerant passage 23. Further, the low-pressure refrigerant passage 23 and the liquid refrigerant passage 8 are kept airtight by a bush 41, a seal 42, and an O-ring 43 mounted on the temperature sensing rod 33.

Operating rods 35a and 35b made of stainless steel are vertically movably disposed inside the rod holes 32a and 32b, and upper ends of the operating rods 35a and 35b abut on the temperature sensing rod 33. The lower end is in contact with the spring seat 20 in the valve chamber 7. A pressure chamber 44 is formed by the lower end surface of the temperature sensing rod 33 and the bottom surface of the second plunger hole 31b. The pressure chamber 44 communicates with the pressure chamber 7 through the rod holes 32a and 32b.
The high-pressure liquid refrigerant before being adiabatically expanded by the expansion orifice 10 is filled in the pressure chamber 44 through the gap between the rod holes 32a and 32b. As described above, the diaphragm 27,
Heat sensing chamber 29, pressure equalizing chamber 30, temperature sensing rod 33, operating rod 35a,
A control mechanism for controlling the opening and closing of the valve element 21 is constituted by 35b and the like.

Next, the operation of the second embodiment in the above configuration will be described with reference to FIG. Refrigeration cycle compressor 1
The high-temperature and high-pressure gaseous refrigerant adiabatically compressed in the condenser 2
After being condensed to become a liquid refrigerant, the liquid refrigerant passes through the liquid refrigerant passage 8 of the expansion valve 4 via the receiver 3 and is introduced into the valve chamber 7.
Further, the liquid refrigerant passes through the expansion orifice 10 and is adiabatically expanded at this time to become a low-temperature mist refrigerant, passes through the mist refrigerant passage 9 and is introduced into the evaporator 5 to be vaporized to become a gaseous refrigerant. . Thereafter, the gaseous refrigerant discharged from the evaporator 5 returns to the compressor 1 again through the low-pressure refrigerant passage 23.

On the other hand, the temperature sensing rod 33 is constantly urged upward by the compression coil spring 19 via the spring seat 20 and the operating rod 35. Therefore, the position of the valve body 21 with respect to the valve seat 11 that determines the opening degree of the expansion orifice 10 is determined by the biasing pressure P ₁ of the compression coil spring 19, the high-pressure refrigerant pressure P ₂ in the pressure chamber 44, and the low pressure in the pressure equalizing chamber 30. The refrigerant pressure P ₃ and the gas pressure P ₄ in the heat-sensitive chamber 29 are maintained at balanced positions. In other words, the balance of the pressure has a _{P 1 + P 2 + P 3} = P 4. The low pressure refrigerant pressure in the pressure equalizing chamber 30 is controlled by the evaporator 5
Is the pressure of the gaseous refrigerant evaporated.

Since the temperature-sensitive rod 33 is exposed in the low-pressure refrigerant passage 23, the heat of the gaseous refrigerant passing through the low-pressure refrigerant passage 23 is reduced by the aluminum temperature-sensitive rod 3 having a high thermal conductivity.
3 and is transmitted to the diaphragm 27, and further transmitted from the diaphragm 27 to the activated carbon in the heat-sensitive chamber 29.
The activated carbon adsorbs or desorbs the gas in the heat-sensitive chamber 29 in accordance with the temperature. The activated carbon adsorbs the gas when the ambient temperature decreases, and desorbs the gas when the temperature increases. Therefore, the gas pressure in the heat-sensitive chamber 29 changes according to the refrigerant temperature at the outlet side of the evaporator 5, and the gas pressure acts on the upper surface of the temperature-sensitive rod 33 via the diaphragm 27 and further acts on the operation rod 35. As a result, the opening and closing of the valve body 21 is controlled, and the superheat is controlled so that the superheat of the refrigerant at the outlet of the evaporator 5 becomes constant.

For example, when the low-pressure pressure of the refrigerant is constant at ² kgf / cm ² and the high-pressure pressure of the refrigerant is 4 kgf / cm ² or higher and the load in the vehicle interior rises and the cooling load increases, the low-pressure refrigerant passage 23 increases. The temperature of the refrigerant flowing through the air also increases.
Then, the activated carbon in the heat-sensitive chamber 29 which has received the heat transfer through the temperature-sensitive rod 33 and the diaphragm 27 releases the gas, so that the pressure P ₄ in the heat-sensitive chamber 29 increases, and the pressure balance becomes P ₁ +.
P ₂ + P ₃ <P ₄ , and the diaphragm 27 is displaced downward. This displacement is transmitted to the temperature sensing rod 33 and the operating rods 35a and 35b, and the valve body 21 moves downward. As a result, the opening degree of the expansion orifice 10 increases, the amount of refrigerant flowing into the inlet of the evaporator 5 increases, and the superheat of the refrigerant at the evaporator outlet is kept at 5 ° C to 10 ° C.

On the other hand, when the vehicle interior temperature decreases and the cooling load decreases, the temperature of the refrigerant flowing through the low-pressure refrigerant passage 23 also decreases. As a result, the activated carbon of the thermal chamber 29 adsorbs gas, the pressure balance reduces the pressure P ₄ of the heat chamber 29 is _{P 1 + P 2 + P 3} > P 4 and the actuating rod 35 since moves upward Thus, the opening degree of the expansion orifice 10 is reduced.
Then, the flow rate of the refrigerant toward the inlet of the evaporator 5 is reduced,
The superheat of the refrigerant at the outlet of the evaporator is kept at 5 ° C to 10 ° C.

Next, the high pressure of the liquid refrigerant is reduced to 4 kgf / cm.
The operation at a low load of less than ² will be described. Since the cooling load is small, the compressor 1 operates at a low load, and when the high pressure of the liquid refrigerant supplied from the condenser 2 to the expansion valve 4 decreases, the pressure P ₂ in the pressure chamber 44 filled with the liquid refrigerant decreases. Therefore, the pressure balance becomes P ₁ + P ₂ + P ₃ <P ₄ , the valve body 21 moves downward, and the opening degree of the expansion orifice 10 increases, so that the flow rate of refrigerant on the inlet side of the evaporator 5 can be increased. it can. Then, the superheat of the refrigerant at the evaporator outlet decreases as the valve body 21 is positioned downward,
Eventually, the temperature of the refrigerant reaches 0 ° C. and the refrigerant introduced into the evaporator 5 becomes a gas-liquid two-phase refrigerant that has not completely evaporated. This is shown in FIG. 11 in comparison with the characteristics of the conventional expansion valve shown in FIG.
As the high pressure Ph decreases from 15 to 10 to 5 kgf / cm ² , the superheat at the same valve opening decreases,
The flow rate of the refrigerant in the same superheat can be increased. For example, at around 1.5 ° C. of superheat in which the refrigerant is backed up by the compressor, as shown at point d in FIG.
1 can secure the refrigerant flow rate more than in FIG. Here, a, b, and c in FIG. 11 are the fully open points of the valve at each high pressure, and a ′, b ′, and c ′ are the points at which the valve starts to open.

As described above, when the load is low, the superheat control is stopped by the increase in the flow rate of the refrigerant, and the flow rate of the refrigerant is adjusted so that the recirculation amount of the lubricating oil to the compressor 1 can be secured. Therefore, the supply of the lubricating oil to the compressor 1 is ensured, and there is no risk of burning. In addition, a sufficient flow rate of the refrigerant can be supplied to the evaporator 5, and a sufficient dehumidifying performance and a good blowing temperature distribution can be obtained.

Here, when the load is low, more refrigerant than necessary is sent to the evaporator 5, but the excess refrigerant does not evaporate in the evaporator 5 and the liquid refrigerant returns to the compressor 1. There is no problem with cooling performance only. Further, since the ratio of the liquid refrigerant flowing into the compressor to the gaseous refrigerant is sufficiently small, there is no concern about liquid compression in the compressor 1.

Next, a third embodiment of the present invention will be described with reference to FIG. In the expansion valve 4 of the second embodiment shown in FIG. 4, when a high-pressure high-pressure liquid refrigerant is introduced into the pressure chamber 44 on the lower surface of the temperature sensing rod 33, the temperature detected by the temperature sensing rod 33 should be transmitted to the heat sensing chamber 29. , The temperature of the gaseous refrigerant at the evaporator outlet may be higher than that of the evaporator, and the accurate temperature may not be transmitted. Therefore, in the third embodiment shown in FIG. 5, the above problem is solved by making the lower part of the temperature sensing rod 33 a temperature sensing part 33b made of a heat insulating material.

In the expansion valve 4 of the second embodiment shown in FIG. 4, when the high-pressure of the liquid refrigerant filled in the pressure chamber 44 is about 15 kgf / cm ² G, the super- Even if the heat is set to 5 ° C. to 10 ° C., when the high pressure reaches a very high pressure of about 30 kgf / cm ² G, the value of the pressure P ₂ in the pressure chamber 44 increases, and the pressure balance is reduced. Since P ₁ + P ₂ + P ₃ > P ₄ , the valve body 21 moves upward and the opening degree of the expansion orifice 10 becomes small, so that the superheat of the refrigerant at the evaporator outlet is controlled at almost twice the value. .

In order to prevent this, the fourth type shown in FIG.
In the embodiment, the sub-valve 54 is constituted by the sub-valve body 50, the orifice 51, the ball valve 52, and the compression spring 53, and is disposed below the pressure chamber 44. When the pressure P ₂ of the liquid refrigerant in the pressure chamber 44 becomes excessively large, the pressure of the refrigerant is reduced by the sub-valve 54, and the pressure is released to the mist refrigerant passage 9. Adjust so that it does not become too high.

In the fifth embodiment shown in FIG.
By utilizing the fact that the sub-valve 54 is arranged below the pressure chamber 44 in the embodiment, the projection 55 is attached to the sub-valve. The projection 55 eliminates the jet core of the gas refrigerant jet generated downstream of the expansion orifice 10 and reduces the turbulent diffusion layer of the jet as a whole. This can reduce noise caused by jet core generation due to gas refrigerant jets at the time of starting a refrigeration cycle or the like.

In the sixth embodiment, as shown in FIG. 8, even in an expansion valve of the type in which the operating rod 35 passes through the valve opening, the pressure chamber 44 and the low-pressure refrigerant passage 23 are formed by the bush 41 and the seal 4.
2 and the O-ring 43 to maintain airtightness. The pressure chamber 44 and the mist refrigerant passage 9 are
2, and the O-ring 73 keeps airtight. By opening a communication hole 56 that does not intersect with the mist refrigerant passage 9 that communicates the pressure chamber 44 with the valve chamber 7, the high pressure of the refrigerant introduced into the expansion valve 4 as shown in the above embodiment is obtained. As the pressure is lower, it is possible to realize an expansion valve that can secure a sufficient refrigerant flow rate even with the same superheat.

The expansion valve of the present invention can be implemented in a refrigeration cycle having an EPR (evaporation pressure regulating valve) 65 downstream of the evaporator as in the seventh embodiment shown in FIG. Here, the EPR is a pressure reducing valve for preventing the frost of the evaporator by keeping the evaporation pressure of the evaporator at a certain value or more.
In this case, a sufficient flow rate of the refrigerant can be secured by utilizing the decompression of the refrigerant by the EPR 65. That is, in order to move the valve element 21 of the expansion valve 4 downward, the diaphragm 27 is moved.
The pressure of the refrigerant depressurized by the EPR 65 is led to the lower pressure equalizing chamber 30. Therefore, the pressure measurement pipe 6
0, and one end of the outer equalizing pipe 61 is connected to the pressure measuring pipe 60. The expansion valve body 6 has a through-hole 62 communicating the other end of the outer equalizing pipe 61 and the equalizing chamber 30. Then, the pressure of the refrigerant after the pressure is reduced by the EPR is measured by the pressure measurement pipe 6.
The value is measured at 0, and is guided to the pressure equalizing chamber 30 via the outer equalizing pipe 61 and the through hole 62. At this time, the pressure equalizing chamber 30 and the low-pressure refrigerant passage 23
Is sealed by a bush 63 and an O-ring 64,
The refrigerant upstream of the EPR 65 and the refrigerant downstream of the EPR 65 are prevented from mixing.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of an expansion valve and a refrigeration cycle according to a first embodiment of the present invention.

FIG. 2 is a view showing characteristics of a displacement amount of a spool according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an operation state of a spool according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an outline of an expansion valve and a refrigeration cycle according to a second embodiment of the present invention.

FIG. 5 is a diagram showing an outline of an expansion valve and a refrigeration cycle according to a third embodiment of the present invention.

FIG. 6 is a diagram showing an outline of an expansion valve and a refrigeration cycle according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing an outline of an expansion valve and a refrigeration cycle according to a fifth embodiment of the present invention.

FIG. 8 is a diagram showing an outline of an expansion valve and a refrigeration cycle according to a sixth embodiment of the present invention.

FIG. 9 is a diagram showing an outline of an expansion valve and a refrigeration cycle according to a seventh embodiment of the present invention.

FIG. 10 is a diagram showing a flow rate characteristic of a conventional expansion valve.

FIG. 11 is a view showing a flow rate characteristic of the expansion valve of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 4 Expansion valve 5 Evaporator 6 Expansion valve main body 7 Valve room 8 Liquid refrigerant passage 9 Mist refrigerant passage 10 Expansion orifice 12 Spool 13 Pressure chamber 21 Valve 23 Low pressure refrigerant passage 44 Pressure chamber

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 54-99160 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F25B 41/06

Claims (1)

(57) [Claims] 1. An expansion valve constituting a refrigeration cycle together with a compressor, a condenser, and an evaporator, comprising: an expansion valve main body forming an outer frame of the expansion valve; and an expansion valve main body formed in the expansion valve main body; An inlet refrigerant passage in which the refrigerant condensed in the condenser is introduced in communication with the condenser; and a flow passage restricting portion formed in the expansion valve body and adiabatically expanding the refrigerant introduced from the inlet refrigerant passage. An outlet refrigerant passage formed in the expansion valve main body and supplying the refrigerant adiabatically expanded in the flow path restricting portion to the evaporator; and an outlet refrigerant passage formed in the expansion valve main body, one end of which is connected to the evaporator. The other end is formed of a material having good heat conductivity, and is provided so as to be movable through the suction refrigerant passage. With the installed temperature sensor and the temperature sensor, A heat-sensitive chamber in which the temperature of the refrigerant at the evaporator outlet side passing through the suction refrigerant passage is transmitted; a pressure equalizing chamber into which the pressure of the refrigerant at the evaporator outlet side passing through the suction refrigerant passage is introduced; A pressure responsive member that moves the temperature sensing rod in accordance with the pressure of the pressure equalizing chamber; and a pressure responsive member that is disposed adjacent to the temperature sensing rod and that receives the pressure of the high-pressure side refrigerant upstream of the flow path throttle unit. The pressure chamber applies the pressure of the high-pressure side refrigerant to the temperature-sensitive rod so that the valve body receives a force in the opening direction as the pressure of the high-pressure refrigerant decreases. An expansion valve, characterized in that: