JPH11170850A - Cooling device for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device for an automobile having an orifice part which can guide a refrigerant of desired flow amount and pressure to an evaporator in a stable manner and good controllability over a total range of car speed. SOLUTION: An orifice part 4b is formed into a double structure of a main tube 30 having an orifice 32 of large diameter and an inner tube 40 having an orifice 41 of small diameter, the inner tube 40 is forward/backward moved by balance of a pressure difference between an inlet/outlet determined by a load and elastic force of a spring 50, an operating orifice diameter is switched. In the inner tube 40, a slide moving part 43 is provided, deflection in a tip end, when the refrigerant is jetted, is prevented. A total opening area of the second orifice 41 and a communication hole 44 is set to an opening area or more of a refrigerant introducing passage 42, a pressure drop of the refrigerant at passing time of the inner tube 40 is eliminated. The communication hole 44 is formed to be uniformly distributed in three directions or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle cooling system having an orifice portion for expanding a refrigerant in a refrigeration cycle.

[0002]

2. Description of the Related Art Some cooling systems for automobiles use a refrigerating cycle using an orifice portion having no function of adjusting a valve opening in place of a temperature-type expansion valve to perform expansion and contraction of a refrigerant. There is. As shown in FIG. 9, a refrigeration cycle 1 of this type of vehicle air-conditioning system has a compressor 2 driven by a traveling engine (not shown) via a belt or the like, and is compressed by the compressor 2 to high temperature and high pressure. A condenser 3 for cooling and condensing and liquefying the refrigerant by running wind or the like; an orifice portion 4 for constricting and expanding the refrigerant from the condenser 3; an evaporator 5 for evaporating the refrigerant and cooling the air blown into the vehicle cabin; And an accumulator 6 for separating gas and liquid and returning only the gas refrigerant to the compressor 2.

The fixed orifice system is a system employing a fixed orifice (for example, an orifice tube made of a small-diameter tube is used as the orifice portion 4) for expanding the refrigerant. Usually, it is designed based on the maximum cooling time. That is, the inside diameter of the orifice tube is designed so that the refrigerant pressure in the evaporator 5 can be maintained at a low pressure required for the maximum cooling, and the flow rate of the refrigerant required for the maximum cooling in the evaporator 5 is reduced. It is flowing to. Such a system is advantageous in that it has a simple structure and a low manufacturing cost, and is therefore used in some car air conditioners in Europe and the United States.

[0004] However, the fixed orifice system is generally designed based on the normal running time (during medium-high speed running), and the inner diameter of the orifice tube is set so as to obtain the refrigerant flow rate at which the maximum cooling state is obtained at this time. Therefore, in terms of performance, it has sufficient cooling capacity at low load, high speed running etc., but there is a defect that cooling capacity at high load, idling etc. is insufficient because there is no refrigerant flow adjustment function originally. . Such a drawback is not really a problem in an environment where there is no traffic congestion, but becomes a serious problem in an environment where traffic congestion frequently occurs.

Therefore, in order to compensate for the lack of cooling power during idling and maintain the cooling capacity corresponding to the entire range of vehicle speed from high-speed running to idling, the pressure difference between the inlet and the outlet is sensed and the refrigerant flow rate is controlled in two steps. A refrigerant expansion system (double orifice system) has been devised. The operating principle of this double orifice system is that the flow rate of the refrigerant is adjusted by using orifices of different diameters depending on environmental conditions. As a result, an inexpensive system that can replace the system using the thermal expansion valve can be provided.

As such a double orifice system, for example, the one shown in FIG. 10 has been proposed (Japanese Utility Model Laid-Open No. 2-73569).

The orifice portion 4a has a casing 10 in which an inlet port 11 communicating with the condenser 3 and an outlet port 12 communicating with the evaporator 5 are formed. A chamber 13 is formed. A valve body 14 to which a first orifice tube 17 is attached is inserted into the valve storage chamber 13 so as to be able to advance and retreat. The valve body 14 is constantly biased toward the high pressure side by a spring 15. A valve body 14 is provided between the valve body 14 and a valve port 18 provided on the inner peripheral wall of the casing 10.
A throat portion 19 is formed as a refrigerant flow passage that is opened and closed by the forward and backward movements. In addition, a second orifice tube 21 having a larger diameter than the first orifice tube 17 and having a larger diameter than the first orifice tube 17 is fixed through the partition wall portion 20 that partitions the valve housing chamber 13 from the low-pressure side circuit. When the pressure difference between the high-pressure side circuit and the low-pressure side circuit is less than a predetermined value, such as when the traveling wind passing through the condenser is large and the amount of refrigerant cooling and condensing in the condenser is large, such as during high-speed traveling, or when the cooling load is small. , The valve body 14 is a throat portion 19
, The refrigerant that has been pressure-fed to the inlet port 11 is squeezed and expanded through the throat portion 19 and the second orifice tube 21, and is ejected to the outlet port 12. On the other hand, when the traveling wind passing through the condenser is small, such as during idling during traffic congestion, and the amount of refrigerant condensed in the condenser is small, or when the pressure difference is equal to or greater than a predetermined value, such as when the cooling load is large, the valve element 14 The throat portion 19 is closed, and the refrigerant pressure-fed to the inlet port 11 is squeezed and expanded through the first orifice tube 17. As a result, the pressure of the refrigerant in the evaporator 5 is sufficiently reduced, and the evaporation temperature of the refrigerant is reduced, so that the lack of cooling power during idling is eliminated. In FIG. 1, reference numeral 16 denotes stoppers provided at a plurality of locations on the inner peripheral wall of the casing 10.

[0008]

However, such a conventional double orifice system (orifice section 4)
In the structure of a), the first orifice tube 17 is simply connected to the central axis of the valve element 14 by extending downstream, and its distal end located on the downstream side (the refrigerant outlet side). Since 17a is in a so-called free state without support, there is a possibility that the tip portion 17a of the first orifice tube 17 swings during passage of the refrigerant and the flow of the refrigerant becomes unstable.

As described above, the throat portion 19 is open during high-speed running or the like, and most of the refrigerant pressure-fed to the inlet port 11 passes through the throat portion 19 and blows out to the valve accommodating chamber 13. Then, the first stage of expansion is performed, and further, the second stage of expansion is performed by passing through the second orifice tube 21 and squirting toward the output port 12 side. On the other hand, during idling, etc. The throat portion 19 is closed, and the refrigerant pressure-fed to the inlet port 11 is to pass through only the first orifice tube 17 to be squeezed and expanded. In fact, even in the latter case, The refrigerant may be throttled at the throat portion 19 and cause a pressure drop. Therefore, in any case, since the refrigerant may cause a pressure drop in the throat portion 19, it is difficult to control the flow rate by the pressure difference, so that the target control may not be performed.

The present invention relates to the conventional orifice portion 4 described above.
a cooling system for an automobile having an orifice portion capable of guiding a refrigerant having a desired flow rate and pressure to an evaporator stably and with good controllability over the entire range of vehicle speed. It is intended to provide a device.

[0011]

In order to achieve the above object, an invention according to a first aspect of the present invention is directed to an orifice portion for squeezing and expanding refrigerant circulating from a high pressure side circuit to a low pressure side circuit of a refrigeration cycle and flowing into an evaporator. Wherein the orifice portion has a main tube fixed to a refrigerant pipe, and an inner tube accommodated in a housing of the main tube so as to be able to move forward and backward. A first orifice for communicating the storage chamber with the low-pressure side circuit and performing expansion and contraction of the refrigerant is formed, and the inner tube has an opening area smaller than that of the first orifice and has a restriction area for restricting and expanding the refrigerant. A second orifice to perform, and a refrigerant having a larger opening area than the second orifice and being pumped from the high-pressure side circuit to the second orifice. , A sliding portion that slides on the inner peripheral wall of the storage chamber, and a communication hole that is located on a lower pressure side than the slide portion and communicates the refrigerant introduction passage with the storage chamber. The inner tube opens and closes a refrigerant flow passage from the accommodation chamber to the first orifice, and moves forward in the direction of the low pressure side when the pressure difference between the high pressure side circuit and the low pressure side circuit becomes a predetermined value or more. And closing the refrigerant flow passage so that a total opening area of the second orifice and the communication hole is equal to or larger than an opening area of the refrigerant introduction passage.

According to the present invention, when the pressure difference between the high-pressure side circuit and the low-pressure side circuit, which is determined by the running state of the vehicle, is equal to or smaller than a predetermined value (during normal running), the inner tube opens the refrigerant flow passage. The refrigerant that has been pressure-fed to the refrigerant inlet of the orifice portion passes through the refrigerant introduction passage of the inner tube, flows through the second orifice and the communication hole into the housing chamber of the main tube, and then flows into the first tube of the main tube. The throttle expands through the orifice and is ejected to the refrigerant outlet of the orifice. At this time, since the total opening area of the second orifice and the communication hole is larger than the opening area of the refrigerant introduction passage, there is no pressure drop when the refrigerant passes from the inner tube to the main tube.
That is, in this case, only the first orifice of the main tube works.

On the other hand, when the pressure difference between the two circuits is equal to or greater than a predetermined value, such as during idling, the inner tube closes the refrigerant flow passage, and the refrigerant pressure-fed to the refrigerant inlet passes through the refrigerant introduction passage of the inner tube. After passing through and passing through only the second orifice of the inner tube and being squeezed and expanded, it is ejected to the refrigerant outlet through the first orifice of the main tube. At this time, since the opening area of the first orifice is larger than the opening area of the second orifice,
The refrigerant depressurized in the second orifice is not further depressurized in the first orifice thereafter. That is, in this case, only the second orifice of the inner tube works.

Further, since the sliding portion of the inner tube slides on the inner peripheral wall of the housing chamber of the main tube, that is, the inner tube has a thickness (outer diameter) corresponding to the inner diameter of the housing chamber of the main tube. The sliding portion is supported by the inner peripheral wall of the housing chamber of the main tube.
For this reason, the tip of the inner tube does not swing when the refrigerant is ejected from the second orifice of the inner tube, and the operation of the inner tube is stabilized.

According to a second aspect of the present invention, in the first aspect of the present invention, the communication holes are equally distributed in three or more directions around the axial direction.

In the present invention, since the communication holes of the inner tube are formed so as to be equally distributed in three or more directions, for example, in a direction perpendicular to the axial direction, the main tube extends from the refrigerant introduction passage of the inner tube. The refrigerant flowing into the storage chamber is evenly distributed in three or more directions from the refrigerant introduction passage of the inner tube, so that the balance of the force around the axis when the refrigerant passes is ensured. For this reason, the deflection of the tip of the inner tube is more reliably prevented, and the operation of the inner tube is further stabilized.

[0017]

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

FIG. 1 is a schematic longitudinal sectional view showing the structure of an orifice portion used in a vehicle cooling system according to an embodiment of the present invention, and FIG. 1A shows a state during normal running or the like. FIG. 7B shows a state at the time of idling or the like.

The orifice portion 4b has a function of adiabatically expanding the refrigerant in the refrigeration cycle 1 shown in FIG. 9 into a low-temperature and low-pressure mist-like refrigerant, and controls the flow rate and pressure of the refrigerant guided to the evaporator 5 at the inlet and outlet. (Double orifice tube) that senses the pressure difference between the main tube and the main tube 3 and is fixed to the refrigerant pipe.
0, an inner tube 40 slidably (slidably) inserted into the main tube 30 in the axial direction, a spring (elastic body) 50 interposed between the main tube 30 and the inner tube 40, This spring 50
Stopper 60 for regulating the spring bias of the orifice 4
b) and an O-ring 70 for sealing the flow of the refrigerant on the outer peripheral portion. The orifice portion 4b is used, for example, by press-fitting the inside of the refrigerant pipe with the O-ring 70 attached to the main tube 30.

The main tube 30 has a storage chamber 31 provided on the condenser 3 side for storing the inner tube 40.
And a first refrigerant communicating with the evaporator 5 to perform throttle expansion of the refrigerant.
An orifice 32 is formed. The capacitor 3 forms a part of a high-voltage side circuit, and the evaporator 5 forms a part of a low-voltage side circuit.

FIG. 2 is a detailed view of the main tube 30. FIG. 2A is a plan view, FIG. 2B is an end view of the main tube 30 viewed from the front, and FIG. FIG. 4D is an end view, and FIG. 4D is a sectional view taken along line DD of FIG. Here, a case in which an adjustment screw, which will be described later, is employed for the stopper portion is shown.
A screw portion 33 is formed on the inner peripheral surface of the end portion on the high pressure side of No. 1. In the figure, reference numeral 34 denotes a groove for mounting the O-ring 70.

The inner tube 40 is slidably fitted in the housing 31 of the main tube 30 in the axial direction. The inner orifice 40 has a first
A second orifice 41 having an inner diameter (opening area) smaller than the orifice 32 and a refrigerant having an inner diameter (opening area) larger than the second orifice 41 and being pumped from the condenser 3 toward the second orifice 41. The leading refrigerant passage 42, a sliding part 43 that slides on the inner peripheral wall of the housing chamber 31 of the main tube 30, and the refrigerant introducing passage 42 that is located on a lower pressure side than the sliding part 43 and communicates with the housing chamber 31. Communication hole 44 is formed. Second orifice 41
Exit faces the entrance of the first orifice 32.

The inner tube 40 has a sliding portion 43 of the inner tube 40 and the accommodation chamber 3 of the main tube 30.
The spring 50 is always biased toward the high pressure side, that is, in the direction of the upstream side of the flow of the refrigerant, by the spring 50 interposed between the first and the low pressure side bottom. Such an inner tube 40
The refrigerant flowing out (bypassed) from the refrigerant introduction passage 42 of the inner tube 40 into the storage chamber 31 through the communication hole 44 between the tapered portion 45 provided at the lower pressure end of the first orifice 32 and the inlet of the first orifice 32. Is formed to the first orifice 32, and the inner tube 40 moves forward and backward to open and close the refrigerant flow passage 35. That is, when the inner tube 40 is at the retracted position (the position where the sliding portion 43 of the inner tube 40 comes into contact with the stopper 60), as shown in FIG.
Are separated, the refrigerant flow passage 35 is in an open state, and therefore, the refrigerant introduction passage 4 of the inner tube 40 is open.
A part of the refrigerant pressure-fed to 2 passes through the communication hole 44 (bypass). When the inner tube 40 moves forward from this state, as shown in FIG.
Since the tapered portion 45 at the tip of the inner tube 40 abuts on the inlet of the first orifice 32 and closes the refrigerant flow passage 35, all the refrigerant pressure-fed to the refrigerant introduction passage 42 of the inner tube 40 passes through the second orifice 41. Will do.

The stopper 60 has, for example, an annular shape, is located at the end on the high pressure side in the housing chamber 31 of the main tube 30, is fitted and fixed by press-fitting, and has a sliding portion 43 of the inner tube 40. The contact of the spring 50 regulates the spring bias of the spring 50.

As described above, the orifice portion 4b has a variable (two-stage) structure in which the main tube 30 and the inner tube 40 are combined, and the inner tube 40 is operated (movable) by the pressure difference between the inlet and the outlet and the spring load. )
When the condensing pressure rises, for example, during idling, the refrigerant moves forward on the low pressure side, that is, in the direction of the flow of the refrigerant, and closes the refrigerant flow passage 35.

That is, the opening and closing of the refrigerant flow passage 35 by the inner tube 40 is performed by three forces acting on the inner tube 40, namely, the pressure of the high pressure side circuit and the spring 5
This is achieved by the balance between the resilience of 0 and the pressure in the storage chamber 31 determined by the pressure of the low-pressure side circuit. In particular, in the present embodiment, when the pressure difference between the pressure of the high-pressure side circuit (condensation pressure in the condenser 3) and the pressure of the low-pressure side circuit (evaporation pressure in the evaporator 5) becomes equal to or greater than a predetermined value, the inner tube 40 The value of the spring force of the spring 50 is set such that the spring 50 moves forward against the elastic force and closes the refrigerant passage 35. Here, the condensing pressure of the refrigerant in the condenser 3 is determined by the circulating refrigerant flow rate due to the capacity of the compressor 2 and the heat load in the condenser 3, and the evaporating pressure of the refrigerant in the evaporator 5 is equal to the circulating refrigerant flow rate. The predetermined value is determined by the heat load on the evaporator 5, and the predetermined value means a pressure difference generated when the vehicle cooling device 1 is operated in an idling state of the engine.

As described above, the opening area (orifice diameter) of the second orifice 41 of the inner tube 40 is set smaller than the opening area (orifice diameter) of the first orifice 32 of the main tube 30. How to set the values of the orifice diameters of these two types depends on the refrigerant pressure and the circulating refrigerant flow rate of the evaporator 5 required during normal running (for example, during middle-high speed running) and during idling at the time of maximum cooling. Is set to obtain. Here, for example, the orifice diameter of the first orifice 32 is φ1.4 mm, and the second orifice 4
Each orifice diameter is set to φ1.0 mm. As will be described later, only the first orifice 32 acts during normal traveling, so that the diameter of the first orifice 32 has the same performance as a general fixed orifice system, including reliability such as oil return as a system. Has a diameter.

The resilience of the spring 50 should be finely adjusted for each vehicle type so as to obtain the most suitable operating characteristics for that vehicle type. Here, for example, as shown in FIG. Operating characteristics, ie, the pressure difference is 16.0 kg /
When it rises above cm ² (predetermined value), the inner tube 40
Is moved forward to close the refrigerant flow passage 35, and when the pressure difference drops from this state to 14.5 kg / cm ² or less, the inner tube 40 is moved backward to open the refrigerant flow passage 35. As described later, in the former case, only the second orifice 41 (orifice diameter φ1.0 mm) acts, and in the latter case, the first orifice 32 exclusively.
(Orifice diameter φ1.4mm) only works.

In addition to the elasticity of the first orifice 32, the second orifice 41, and the spring 50, the amount of sliding of the inner tube 40 is appropriately set according to the required performance.

The sliding portion 43 of the inner tube 40
Has a thickness (outer diameter) corresponding to the inner diameter of the storage chamber 31 of the main tube 30 in order to slide with the inner peripheral wall of the storage chamber 31 of the main tube 30. This allows
The inner tube 40 is supported by the inner peripheral wall of the housing chamber 31 of the main tube 30 at the sliding portion 43. Therefore, when the refrigerant is ejected from the second orifice 41 of the inner tube 40, the inner tube 4
The deflection of the leading end of the inner tube 40 is prevented, and the operation of the inner tube 40 is stabilized.

The communication hole 44 allows the refrigerant, which has been pressure-fed to the refrigerant introduction passage 42 of the inner tube 40 when the inner tube 40 is at the retracted position, to be sent to the first orifice 32 of the main tube 30 with the same pressure. It is preferable to have as large an opening area as possible, since it functions as a through hole or a relief hole. Specifically, the total opening area of the second orifice 41 and the communication hole 44 is preferably equal to or larger than the opening area of the refrigerant introduction passage 42. Here, for example, the inside diameter of the communication hole 44 is set to φ1.0 mm (three communication holes 44 are formed as described later), and the inside diameter of the refrigerant introduction passage 42 is set to φ2.0 mm.

As shown in FIG. 4B of the detailed view of FIG. 4, the communication holes 44 are equally distributed in three places, specifically, in a direction perpendicular to the axial direction (120 (At an angle of °) and formed in three directions. As a result, a part of the refrigerant that has been pressure-fed to the refrigerant introduction passage 42 of the inner tube 40 passes through the communication hole 44 and is contained in the storage chamber 31.
The refrigerant is evenly distributed in three directions when the refrigerant is jetted into the inside, so that the balance of the force around the axis when the refrigerant is jetted from the communication hole 44 is secured, and the operation stability of the inner tube 40 is obtained. Can be FIG. 4 is a detailed view of the inner tube 40. FIG. 4A is a sectional view, and FIG.
Is a sectional view taken along the line BB.

Next, before describing the operation, the operating principle of the automotive cooling system 1 will be briefly described based on the Mollier diagram shown in FIG.

The refrigeration cycle indicated by a solid line in the figure shows a case where the vehicle is running normally. A high-temperature and high-pressure gas refrigerant (position A) adiabatically compressed by a compressor is heated by a condenser 3 to the outside. To release the medium-temperature high-pressure liquid refrigerant (B
Position). This liquid refrigerant passes through the orifice portion 4b, is throttled and expanded, and is a low-temperature and low-pressure mist refrigerant (position C).
Becomes The mist refrigerant exchanges heat with air in the evaporator 5 to cool the air, and becomes superheated steam (D position) and is sucked into the compressor 2. At this time, since the rotational speed of the compressor 2 driven by the engine is high, the amount of refrigerant to be pumped and sucked (that is, the circulating refrigerant flow rate) is large, and the suction pressure is low. Further, since the amount of wind that hits the condenser 3 is large, the refrigerant is sufficiently condensed, and the condensing pressure is reduced.

On the other hand, the refrigeration cycle indicated by broken lines a → b → c → d in the figure shows a case where the engine is in an idling state. At this time, since the rotation speed of the compressor 2 driven by the engine is low, the amount of refrigerant to be pumped and sucked (that is, the circulating refrigerant flow rate) is small, and the suction pressure is high. Also, since the amount of wind that hits the condenser 3 is small,
The refrigerant is not sufficiently condensed and the condensing pressure increases.

Therefore, during idling, the pressure difference ΔP ₂ between the high-pressure side circuit and the low-pressure side circuit is generally larger than the pressure difference ΔP ₁ during normal running. The predetermined value corresponds to ΔP ₂ .

Next, the operation of the present embodiment will be described.

First, during normal running, since the pressure difference ΔP ₁ between the high-pressure side circuit and the low-pressure side circuit is equal to or smaller than a predetermined value, the inner tube 40 is moved to the retreat position as shown in FIG. Accordingly, the refrigerant flow passage 35 is maintained in the open state. That is, the refrigerant pressure in the storage chamber 31 and the spring 50
The force in the opening direction due to the combined force with the elasticity of the inner tube 40 is larger than the force in the closing direction acting on the inner tube 40 by the pressure of the high-pressure side circuit.

Accordingly, the refrigerant which has been pressure-fed to the refrigerant inlet of the orifice portion 4b passes through the refrigerant introduction passage 42 of the inner tube 40, passes through the second orifice 41 and the three communication holes 44, and the accommodating chamber 31 of the main tube 30. After flowing into the inside, the first orifice 3 of the main tube 30
The orifice 4 passes through the nozzle 2 and expands and is ejected to the refrigerant outlet of the orifice 4b. At this time, the second orifice 4
The total opening area of the one and three communication holes 44 is the refrigerant introduction passage 4
Since the opening area is equal to or larger than 2, the pressure drop of the refrigerant when passing through the inner tube 40 and reaching the inlet of the first orifice 32 of the main tube 30 does not exist. That is,
In this case, only the first orifice 32 (orifice diameter φ1.4 mm) of the main tube 30 works. Then, the refrigerant jetted to the refrigerant outlet is sent to the evaporator 5 through the refrigerant pipe, and exchanges heat with air to cool the air.

As described above, during normal traveling, the orifice diameter is large (φ1.4 m) with the refrigerant flow passage 35 opened.
m) Since the throttle expansion is performed by the first orifice 32, the flow rate of the refrigerant reaching the evaporator 5 increases,
A predetermined cooling performance can be exhibited.

On the other hand, when the vehicle enters an idling state due to, for example, traffic congestion from such a state, the pressure difference ΔP ₁ between the high-pressure side circuit and the low-pressure side circuit becomes a predetermined value or more according to the above principle. The force in the closing direction that acts on the inner tube 40 due to the pressure of the high-pressure side circuit is larger than the force in the opening direction due to the combined force of the refrigerant pressure in the storage chamber 31 and the resilience of the spring 50. , FIG.
As shown in (B), the inner tube 40 moves forward and closes the refrigerant flow passage 35.

Accordingly, the refrigerant that has been pressure-fed to the refrigerant inlet of the orifice portion 4b passes through the refrigerant introduction passage 42 of the inner tube 40, and further passes through the inner tube 40.
After the squeeze expansion is performed only through the second orifice 41, the refrigerant is ejected through the first orifice 32 of the main tube 30 to the refrigerant outlet of the orifice portion 4b. At this time, the opening area of the first orifice 32 is
Since the opening area is larger than the opening area of the first orifice, the refrigerant depressurized by the second orifice 41 is not further depressurized by the first orifice 32 thereafter. That is, in this case, only the second orifice 41 (orifice diameter φ1.0 mm) of the inner tube 40 is exclusively used. Then, the refrigerant jetted to the refrigerant outlet is sent to the evaporator 5 through the refrigerant pipe, and exchanges heat with air to cool the air.

As described above, when idling, the refrigerant flow passage 35 is closed and the orifice diameter is small (φ1.0 m).
m) Since the expansion is performed by the second orifice 41,
The pressure of the refrigerant in the evaporator 5 decreases. In the state where the evaporation pressure of the refrigerant is low as described above, the evaporation temperature of the refrigerant is also low, and the cooling performance of the automotive cooling device exhibits a relatively high value. Is maintained, and the desired cooling capacity is maintained.

Therefore, even in a vehicle cooling system having an orifice portion, it is possible to maintain a desired cooling capacity not only during normal running but also during idling.

The orifice portion used in the automotive cooling system according to the present invention is not limited to the above-described shape, and may be, for example, a communication hole having a shape as shown in FIG.

In this embodiment, the communication holes 44a
In order to obtain the stability of the operation of the inner tube 40a, in order to obtain the stability of the operation of the inner tube 40a, the inner tube 40a is equally distributed in four directions at right angles to each other (at an angle of 90 ° to each other). And each is in the form of a slot that is long in the axial direction, rather than a circular hole. Also in this case, in order that the refrigerant that has been pressure-fed to the refrigerant introduction passage 42 of the inner tube 40a when the inner tube 40a is at the retracted position is sent to the first orifice 32 of the main tube 30 at the same pressure, The total opening area of the second orifice 41 and the four communication holes 44a is larger than the opening area of the refrigerant introduction passage 42. FIG. 6 is a detailed view of the inner tube 40a according to the present embodiment. FIG. 6A is a cross-sectional view, and FIG. 6B is a BB cross-sectional view.

Also, instead of the annular stopper 60 shown in FIG. 1, an adjustment screw as shown in FIGS. 7 and 8 can be used to adjust the displacement of the inner tube 40 and the switching pressure in the operating characteristics. You can also. Here, FIG.
Is a detailed view of still another orifice portion 4c using an adjusting screw. FIG. 4A is a partially cutaway sectional view, and FIG.
Is an end view as seen from the low pressure side, and FIG. 2C is an end view as seen from the high pressure side. FIG. 8 is a detailed view of still another orifice portion 4d using an adjusting screw. FIG. 8 (A) is a partially cutaway sectional view, and FIG. 8 (B) is an end view of the same viewed from a low pressure side. (C) is an end view as viewed from the high pressure side. The orifice portion 4c has three communication holes 44 (see FIGS. 1 and 4), and the orifice portion 4d has four communication holes 44a (see FIG. 6).

As described above, the adjusting screw 80 shown in FIGS. 7 and 8 is used to adjust the displacement of the inner tube 40 and the switching pressure (see FIG. 3) in the operating characteristics. Then, in a state of being in contact with the inner tube 40, the screw portion 81 formed on the outer peripheral surface thereof is screwed with the screw portion 33 (see FIG. 2) of the main tube 30, and is attached to the high-pressure end of the main tube 30. It is fixed by fitting.

Therefore, by turning the adjusting screw 80 with a hexagon wrench or the like to change the screwing position (displacement adjustment),
By changing the length of the spring 50 when the inner tube 40 is at the retracted position, it is possible to adjust the magnitude of the resilience of the spring 50 and, consequently, the operation switching pressure. As described above, the resilience of the spring 50 should be finely adjusted for each vehicle type so as to obtain the most suitable operating characteristics for that vehicle type.
By providing 0, it is possible to cope with various types of vehicles using the same spring 50 very easily.

[0050]

Therefore, according to the first aspect of the present invention, the orifice diameter acting by sliding the inner tube by the pressure difference and the spring load is made variable, and the orifice diameter (opening area) during normal running is reduced. The larger one
Since the orifice is actuated and the second orifice having a smaller orifice diameter (opening area) is actuated during idling, the pressure of the refrigerant in the evaporator decreases during idling, and the amount of circulating refrigerant at this time is small. And the desired cooling capacity can be maintained even during idling. At this time, since the total opening area of the second orifice and the communication hole is equal to or larger than the opening area of the refrigerant introduction passage, there is no pressure drop when the refrigerant passes from the inner tube to the main tube. Flow rate control can be easily performed. Further, since the inner tube is supported by the sliding portion, the tip of the inner tube is prevented from swinging when the refrigerant is blown out from the second orifice of the inner tube, and the operation stability of the inner tube is improved.

According to the second aspect of the present invention, in addition to the effects of the first aspect, the communication holes of the inner tube are equally distributed in three or more directions around the axial direction. The balance of the force around the axis at the time of passage is ensured, the deflection of the tip of the inner tube is more reliably prevented, and the operation of the inner tube is further stabilized.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing a structure of an orifice portion used in a vehicle cooling device according to an embodiment of the present invention.

FIG. 2 is a detailed view of a main tube of the orifice portion.

FIG. 3 is an operation characteristic diagram of the orifice portion.

FIG. 4 is a detailed view of an inner tube of the orifice portion.

FIG. 5 is a graph showing a refrigeration cycle on a Mollier diagram.

FIG. 6 is a detailed view of an inner tube of an orifice portion according to another embodiment of the present invention.

FIG. 7 is a detailed view showing an orifice portion according to still another embodiment of the present invention.

FIG. 8 is a detailed view showing an orifice portion according to still another embodiment of the present invention.

FIG. 9 is a circuit diagram of a refrigeration cycle of a vehicle cooling device having an orifice portion.

FIG. 10 is a longitudinal sectional view showing a conventional orifice portion.

[Explanation of symbols]

 4b, 4c, 4d orifice section 5 evaporator 30 main tube 31 accommodating chamber 32 first orifice 35 refrigerant passage 40 inner tube 41 second orifice 42 refrigerant introduction passage 43 sliding part 44 44a communication hole 50 spring (spring) 60 stopper 70 O-ring 80 adjustment screw

Claims (2)

[Claims] 1. An automobile cooling system comprising an orifice section (4) for squeezing and expanding refrigerant flowing from a high-pressure side circuit to a low-pressure side circuit of a refrigeration cycle and flowing into an evaporator (5). (4) includes a main tube (30) fixed to the refrigerant pipe, and an inner tube (40) housed in the housing chamber (31) of the main tube (31) so as to be movable back and forth in the axial direction. The main tube (30) has a first orifice (32) that communicates with the housing chamber (31) and the low-pressure side circuit and performs throttle expansion of the refrigerant, and is formed in the inner tube (40). The second orifice (41) has an opening area smaller than that of the first orifice (32) and performs throttle expansion of the refrigerant.
A refrigerant introduction passageway (42) having an opening area larger than that of the second orifice (41) and guiding a refrigerant fed from the high-pressure side circuit to the second orifice (41); )
A sliding part (43) that slides on the inner peripheral wall of the refrigerant chamber, the refrigerant introduction passage (42) located on a lower pressure side than the sliding part (43), and the housing chamber (31).
The inner tube (40) is connected to the first orifice from the housing chamber (31).
The refrigerant flow passage (35) to (32) is opened and closed, and when the pressure difference between the high-pressure side circuit and the low-pressure side circuit becomes a predetermined value or more, the refrigerant moves forward in the direction of the low-pressure side and the refrigerant flow passage (35) is moved. Close the second
A cooling device for an automobile, wherein a total opening area of the orifice (41) and the communication hole (44) is equal to or larger than an opening area of the refrigerant introduction passage (42). 2. The cooling device for a vehicle according to claim 1, wherein said communication holes (44) are equally distributed in three or more directions around said axial direction.