JP2006189240A - Expansion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an expansion device capable of reducing the generation of untoward noise caused by vibration of a valve element, and reducing sucking phenomenon of the valve element generated by flowing of refrigerant of high pressure in a variable orifice formed between a valve seat and the valve element. <P>SOLUTION: A damper chamber 23 is composed of a cylinder 16 in a housing 10 defining the valve seat 14, a piston 17 formed integrally with the valve element 15, and an adjusting screw 22. When the valve element 15 undergoes a sudden pressure change of the introduced refrigerant, a volume of the damper chamber 23 changes to absorb sudden motion of the valve element 15, whereby vibrations of the valve element 15 are suppressed, and the generation of untoward noise is reduced. A ratio (b/a) of a port diameter (a) of a valve hole to a valve element diameter (b) of the valve element 15 is set to 1.5 or less so as to suppress a valve element suction phenomenon and to establish a flow rate corresponding to differential pressure between primary and secondary pressures. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an expansion device used in a refrigeration cycle of a vehicle air conditioner, and more particularly to an expansion device suitable for application to a refrigeration cycle using carbon dioxide (CO ₂ ) as a refrigerant.

  As a refrigeration cycle for a vehicle air conditioner, a refrigeration cycle using a receiver that performs gas-liquid separation of refrigerant condensed by a condenser and a temperature type expansion valve that expands the separated liquid refrigerant is generally used. On the other hand, a refrigeration cycle using an expansion device (orifice) that squeezes and expands the refrigerant condensed by the condenser and an accumulator that performs gas-liquid separation of the refrigerant evaporated by the evaporator is also known.

As the expansion device, an orifice tube that does not have a refrigerant flow rate control function, such as a temperature type expansion valve, or a variable orifice that has a control function is used. The variable orifice expansion device has a differential pressure valve structure in which the valve body is urged in the valve closing direction by a spring. When the differential pressure between the refrigerant inlet and outlet is small, the valve is closed and the differential pressure is a predetermined value. If it becomes above, it has the characteristic of opening. Since the differential pressure valve opens when the differential pressure before and after it reaches a predetermined value, the differential pressure decreases and moves in the valve closing direction, and when it moves in the valve closing direction, the differential pressure increases and moves in the valve opening direction. In order to repeat the above operations, the valve body vibrates in the opening / closing direction, which may cause abnormal noise. In particular, in an expansion device applied to a refrigeration cycle using CO ₂ as a refrigerant, a very small stroke of the valve body is controlled with a very large differential pressure. It is difficult to stop immediately, and the valve body inevitably vibrates in the opening and closing direction and generates abnormal noise. If the valve body vibrates, the flow rate of the refrigerant increases, the evaporation temperature in the evaporator increases, the temperature of the air in the passenger compartment that has passed through the evaporator rises, and the valve operation becomes unstable. The cycle may cause hunting and the temperature of the blowout from the evaporator may not be stable.

On the other hand, an expansion device has been proposed that suppresses vibration of the valve body (see, for example, Patent Document 1). According to this expansion device, a vibration-proof spring is attached to the valve body, and the valve body is slidably operated while being pressed against the inner wall surface of the housing that houses the valve body. As a result, the valve body is restricted from moving in the opening and closing direction by the sliding resistance, so that vibration is suppressed, and generation of abnormal noise due to vibration can be prevented.
JP 2004-218918 A (paragraph numbers [0022] to [0023], FIG. 4)

  However, the conventional expansion device has a structure in which the anti-vibration spring attached to the valve body is pressed against the inner wall surface of the housing as a measure against abnormal noise, so that the frictional force between the wall surface and the valve increases. There is a problem that a large hysteresis occurs in the flow rate characteristic, which causes the valve body to deviate from a set position designed as an optimum position, and the efficiency of the refrigeration cycle is deteriorated.

Further, in a conventional expansion device constituted by a differential pressure valve applied to a refrigeration cycle using CO ₂ as a refrigerant, the diameter of the valve body that opens and closes the valve hole so that it can be fully closed in a region where the differential pressure is small. Since it is designed to be larger than the port diameter of the valve hole and the wrap allowance between the valve hole and the valve body is large, the flow rate increases when the high-pressure CO ₂ refrigerant passes through the orifice formed by them. As a result, the suction phenomenon of the valve body occurs, the valve body moves in the valve closing direction, the flow rate becomes insufficient than the set flow rate, and sufficient cooling power cannot be obtained.

  This invention is made in view of such a point, and it aims at providing the expansion apparatus which can reduce generation | occurrence | production of abnormal noise and can reduce the suction phenomenon of a valve body.

  In the present invention, in order to solve the above problem, the valve body is arranged in a state of being biased in the valve closing direction by the spring on the downstream side of the valve seat, and the primary pressure of the refrigerant inlet and the secondary pressure of the refrigerant outlet are In the expansion device capable of flowing a refrigerant at a flow rate corresponding to the differential pressure, a damper means provided on the valve body for absorbing the movement of the valve body in an opening / closing direction when the valve body receives a sudden pressure fluctuation of the refrigerant. An inflating device is provided.

  According to such an expansion device, by providing the damper means on the valve body, the damper means does not function when the primary pressure change of the introduced refrigerant is small, but when there is a sudden pressure fluctuation, The means absorbs sudden pressure fluctuations and attenuates vibrations that cause the valve body to move in the opening and closing direction, thereby reducing the occurrence of abnormal noise.

  Further, in the present invention, the ratio (b / a) of the port diameter (a) of the valve hole to the valve body diameter (b) of the valve body is set to 1.5 or less, and it is formed between the valve seat and the valve body. This reduces the suction phenomenon of the valve body that occurs when high-pressure refrigerant flows through the variable orifice at a high speed, and allows the refrigerant to flow at a flow rate corresponding to the differential pressure between the primary pressure and the secondary pressure.

  Since the expansion device of the present invention has damper means on the valve body, vibrations in the opening and closing direction of the valve body can be suppressed even when subjected to a sudden pressure change of the refrigerant, thereby reducing the occurrence of abnormal noise. Since an increase in the flow rate due to vibration can be prevented, an increase in the blowing temperature can be suppressed.

Further, by suppressing the vibration of the valve body by the damper means, it is possible to reduce the occurrence of hunting and to stabilize the blowing temperature.
Furthermore, since the noise countermeasures by the damper means are used, the hysteresis can be greatly reduced compared to the noise countermeasures by the sliding resistance, so that stable characteristics can be obtained and the refrigeration cycle is operated efficiently. be able to.

  In addition, since the valve body diameter is brought close to the port diameter and the ratio of the port diameter to the valve body diameter is 1.5 or less, the suction phenomenon of the valve body can be reduced. Since the characteristics can be set to some extent by only the calculated value of the balance with the load, the adjustment of the characteristics becomes easy, and the flow rate of the refrigerant is not reduced by the reduction of the suction phenomenon, so that the cooling power can be secured.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, taking as an example a case where the present invention is applied to a refrigeration cycle of a vehicle air conditioner using CO ₂ as a refrigerant.
FIG. 1 is a schematic diagram of a refrigeration cycle to which an expansion device according to the present invention is applied.

  This refrigeration cycle includes a compressor 1 that compresses refrigerant, a gas cooler 2 that cools the compressed refrigerant, an expansion device 3 that adiabatically expands the cooled refrigerant, an evaporator 4 that evaporates the adiabatic expanded refrigerant, An accumulator 5 that stores excess refrigerant downstream of the evaporator 4 and an internal heat exchanger 6 that cools the refrigerant cooled by the gas cooler 2 with the refrigerant sent from the accumulator 5 to the compressor 1 are provided.

  The expansion device 3 is installed inside the cylindrical body 7. The body 7 has an upstream end connected to a pipe extending from the internal heat exchanger 6 by a joint, and a downstream end connected to a pipe directed to the evaporator 4 by a joint.

In principle, the operation of the refrigeration cycle using CO ₂ as the refrigerant operates in substantially the same manner as the refrigeration cycle using CFCs. In other words, the compressor 1 sucks and compresses the gas-phase refrigerant separated by the accumulator 5 and discharges it as a high-temperature / high-pressure gas-phase or supercritical refrigerant. The refrigerant discharged from the compressor 1 is cooled by the gas cooler 2 and sent to the expansion device 3 via the internal heat exchanger 6. In the expansion device 3, the introduced high-temperature / high-pressure supercritical or liquid-phase refrigerant is adiabatically expanded into a low-temperature / low-pressure gas-liquid two-phase state, and is sent to the evaporator 4. In the evaporator 4, the gas-liquid two-phase refrigerant is evaporated by the air in the passenger compartment. When the gas-liquid two-phase refrigerant evaporates, the latent heat of vaporization is taken from the air in the passenger compartment to cool the air in the passenger compartment. The refrigerant evaporated by the evaporator 4 is sent to the accumulator 5, where it is temporarily stored. Of the refrigerant stored in the accumulator 5, the gas-phase refrigerant is returned to the compressor 1 via the internal heat exchanger 6. In the case of a refrigeration cycle using CO ₂ as the refrigerant, the internal heat exchanger 6 further cools the high-temperature refrigerant cooled by the gas cooler 2 with the low-temperature refrigerant sent from the accumulator 5 to the compressor 1, or The low temperature refrigerant sent from the accumulator 5 to the compressor 1 is further heated by the high temperature refrigerant discharged from the gas cooler 2.

FIG. 2 is a central longitudinal sectional view showing the configuration of the expansion device.
The expansion device 3 has a cylindrical housing 10. In the housing 10, the upper open end in the figure constitutes a primary refrigerant inlet 11 into which a high-pressure refrigerant is introduced, and a strainer 12 is fitted into the refrigerant inlet 11. A valve hole 13 is formed in the axial center of the housing 10, and a lower peripheral edge of the valve hole 13 in the figure constitutes a valve seat 14. A valve body 15 is arranged in the lower part of the figure so as to face the valve seat 14. The valve body 15 is formed integrally with a piston 17 which is slidably disposed in the axial direction on a cylinder 16 formed in the housing 10 extending in the same axial direction as the valve body 15. The valve body 15 is provided with a fixed orifice 18 in the axial direction, and communicates with a lateral hole 19 formed to penetrate in a direction perpendicular to the axial line. The fixed orifice 18 allows a minute amount of refrigerant to flow when the valve body 15 is seated on the valve seat 14 and is closed. The fixed orifice 18 is the most necessary for the compressor 1 that is dissolved in the refrigerant. This is to enable a small amount of lubricating oil to be circulated.

  The secondary-side chamber in which the valve body 15 is disposed communicates with the outside through a refrigerant outlet 20 formed in the housing 10. The piston 17 is biased by the spring 21 in the valve closing direction. As a result, the valve composed of the valve seat 14 and the valve body 15 is a differential pressure valve that operates by the balance between the differential pressure between the primary pressure upstream of the valve hole 13 and the secondary pressure downstream, and the load of the spring 21. It is composed. The spring 21 is received by an adjusting screw 22 screwed into the lower opening of the housing 10 in the figure, and the load of the spring 21 is adjusted by the screwing amount of the adjusting screw 22.

  A room surrounded by the housing 10, the piston 17, and the adjustment screw 22 constitutes a damper chamber 23. The damper chamber 23 communicates with the secondary side of the expansion device by a fixed orifice 24 provided on the adjustment screw 22. As a result, the damper chamber 23 allows the refrigerant to enter and exit from the secondary side of the expansion device via the clearance between the housing 10 and the piston 17 and the fixed orifice 24 provided in the adjustment screw 22. ing. Further, an O-ring 25 is provided on the outer periphery of the housing 10 to perform a fluid seal between the primary side and the secondary side when the expansion device 3 is inserted into the body 7.

  In the expansion device having such a configuration, when the differential pressure between the primary pressure of the refrigerant introduced into the refrigerant inlet 11 and the secondary pressure of the refrigerant at the refrigerant outlet 20 is smaller than a predetermined value determined by the load of the spring 21, 15 is seated on the valve seat 14 and the expansion device is closed. For this reason, the refrigerant introduced into the refrigerant outlet 20 flows through the fixed orifice 24 formed in the valve body 15 with the necessary minimum flow rate.

  Here, when the primary pressure of the refrigerant received by the valve body 15 increases against the load of the spring 21, the valve body 15 moves away from the valve seat 14 and the expansion device opens. As a result, the primary refrigerant flows to the secondary side through the orifice between the valve seat 14 and the valve body 15, and at this time, the high-temperature and high-pressure gas-phase refrigerant is adiabatically expanded to generate a low-temperature and low-pressure refrigerant. It becomes a gas-liquid mixed refrigerant and flows out from the refrigerant outlet 20. Thereafter, the valve body 15 is lifted to a position where the differential pressure between the primary pressure and the secondary pressure and the load of the spring 21 are balanced, and the expansion device stops at the differential pressure between the primary pressure and the secondary pressure. A refrigerant having a corresponding flow rate can be flowed. When the primary pressure is slowly changing, the valve body 15 moves following the change in the primary pressure without accompanying a large sliding resistance, so that the hysteresis of the flow rate characteristic can be reduced.

  Further, when the pressure of the refrigerant introduced into the refrigerant inlet 11 suddenly rises, the valve body 15 receives the pressure and promptly moves in the valve opening direction. However, since the piston 17 integrated with the valve body 15 also operates in the valve opening direction to reduce the volume of the damper chamber 23, the pressure in the damper chamber 23 rises and the piston 17 moves in the valve closing direction. Try to push back. As a result, the valve body 15 absorbs the rapid operation in the valve opening direction, and cannot operate in the valve opening direction following the rapid increase in the primary pressure. Thereafter, the increased pressure in the damper chamber 23 is released through the clearance between the cylinder 16 and the piston 17 and the fixed orifice 24 provided in the adjustment screw 22, and the force for pushing the piston 17 back in the valve closing direction is It will disappear. On the contrary, when the pressure of the refrigerant introduced into the refrigerant inlet 11 suddenly decreases, the valve body 15 and the piston 17 integrated with the valve body 15 perform the reverse operation, and similarly, the valve body 15 has a sudden primary pressure. The valve closing direction cannot follow the decrease. In this way, even when the primary pressure is greatly increased or decreased, rapid movement of the valve element 15 can be suppressed, so that the vibration of the valve element 15 can be suppressed, and therefore the occurrence of abnormal noise is greatly reduced. Can be reduced.

FIG. 3 is an enlarged cross-sectional view of the main part of the differential pressure valve, and FIG. 4 is a diagram showing a change in the suction force of the valve body in the differential pressure valve.
In this expansion device, as shown in FIG. 3, a variable orifice is constituted by a valve seat 14 formed by a housing 10 and a valve body 15 disposed so as to be able to contact with and separate from the valve seat 14, and is fully closed. The valve body 15 has a valve body diameter b larger than the port diameter a of the valve hole so that a wrap allowance (ba) exists on the secondary side of the variable orifice.

For this reason, when the high-pressure CO ₂ refrigerant passes through the variable orifice at a high speed, a vortex flow is generated on the secondary side, and a suction phenomenon that draws the valve body 15 toward the valve seat 14 occurs. When this suction phenomenon occurs, the valve body 15 moves in the valve closing direction. Therefore, in the differential pressure valve in which the valve lift is determined by the differential pressure, the flow rate is insufficient compared to the flow rate corresponding to the differential pressure.

  It has been found that the suction phenomenon is greatly related to the ratio of the port diameter a to the valve body diameter b (b / a). That is, according to FIG. 4 in which the horizontal axis is the ratio (b / a) of the port diameter a to the valve body diameter b and the vertical axis is the suction force, the suction is performed in the region where the ratio (b / a) is small but small. As the force decreases and the ratio (b / a) increases, the suction force increases. This is considered to be due to the small influence of the vortex flow that the valve body 15 receives in the region where the ratio (b / a) is small but small. From the relationship shown in FIG. 4, when the ratio (b / a) of the port diameter a to the valve body diameter b is 1.5 or less, the suction force is small and the influence of the suction phenomenon on the valve body 15 is small. I understand. In this preferred embodiment, the ratio (b / a) of the port diameter a to the valve body diameter b is set to about 1.16 by reducing the wrap allowance by bringing the valve body diameter b closer to the port diameter a. .

  By reducing the suction phenomenon of the valve body 15 due to the flow of the refrigerant, the characteristics of the expansion device can be set to some extent only by calculating the balance between the pressure received by the valve body 15 and the load of the spring 21. Further, during operation, since there is no operation in the valve closing direction due to the suction phenomenon of the valve body 15, a predetermined flow rate of refrigerant can be flowed, and the cooling power will not be insufficient.

  The expansion device 3 described above has a characteristic change point that has a characteristic of flowing through the fixed orifice 18 provided in the valve element 15 when the valve is closed and a characteristic of the valve element 15 being lifted according to the differential pressure after the valve is opened. Is a variable orifice of one point, but next, the characteristic change point is set to two points so as to have a three-stage characteristic, which can improve the degree of freedom of setting when applied to the refrigeration cycle. The apparatus will be described.

  FIG. 5 is a central longitudinal sectional view showing another configuration example of the expansion device, and FIG. 6 is a diagram showing an example of the valve opening characteristic of the expansion device. In FIG. 5, components having the same or equivalent functions as the components of the expansion device shown in FIG. 2 are given the same reference numerals, and detailed descriptions thereof are omitted.

  As shown in FIG. 5, the expansion device 3 a includes a stopper 26 that is screwed to an adjustment screw 22 that adjusts the load of the spring 21 so as to advance and retreat in the axial direction. This stopper 26 is for restricting the stroke of the piston 17 in the valve opening direction, thereby restricting the maximum lift amount of the valve body 15 formed integrally with the piston 17. The maximum lift amount can be achieved by adjusting the screwing of the stopper 26 after adjusting the load of the spring 21 by the adjusting screw 22.

  The stopper 26 has a hollow portion opened on the same secondary side as the refrigerant outlet 20, and a fixed orifice 24 of the damper chamber 23 is provided on an end surface facing the piston 17. Of course, for example, a groove that passes through the axis of the fixed orifice 24 is formed on the opposed end surface of the piston 17 or the stopper 26 so that the fixed orifice 24 is not blocked when the piston 17 abuts against the stopper 26.

  As described above, after the differential pressure valve is opened, when the piston 17 integrated with the valve body 15 reaches the valve opening stroke determined by the screwing position of the stopper 26, the piston 17 comes into contact with the stopper 26 and cannot be stroked any further. By doing so, as shown in FIG. 6, the change point of the valve opening characteristic can be made two points.

  In this valve opening characteristic, the horizontal axis indicates the differential pressure before and after the valve body 15, and the vertical axis indicates the opening area when the valve body 15 is lifted by the diameter of a circle having the same area. Here, when the differential pressure is small and the valve is closed, a constant opening diameter by the fixed orifice 18 is maintained even if the differential pressure changes. When the differential pressure rises and reaches a valve opening point (3 MPa in the illustrated example) determined by adjustment of the spring 21 by the adjusting screw 22, the differential pressure valve starts to open, and thereafter the opening diameter is increased according to the differential pressure. It becomes a changing characteristic. When the differential pressure further increases and the valve body 15 is lifted, the piston 17 integrated with the valve body 15 eventually comes into contact with the stopper 26 (a point of 6 MPa in the illustrated example). Thereby, even if the differential pressure increases further, the valve body 15 cannot stroke in the valve opening direction, so that the opening diameter does not change even if the differential pressure increases. The changing point on the high differential pressure side can be varied by adjusting the stopper 26.

  For this reason, the expansion device 3a can individually adjust two change points of the valve opening characteristic by the adjusting screw 22 and the stopper 26. As a result, when the characteristics of the expansion device 3a are applied to the refrigeration cycle and the characteristics of the expansion device 3a are adjusted to the points with good system efficiency, the two change points can be adjusted. The degree of freedom can be improved. Further, when the differential pressure exceeds a predetermined value, the opening diameter does not increase even if the differential pressure increases, and the refrigerant does not flow excessively in a region where the differential pressure is large, so that adjustment to an efficient region becomes possible. .

  In the configuration example of the expansion device 3 illustrated in FIG. 2 and the expansion device 3 a illustrated in FIG. 5, an adjustment screw 22 is provided as an adjustment member that adjusts the load of the spring 21. It is also possible to use a press-fitting member that is press-fitted into and to adjust the load of the spring 21 according to the press-fitting amount. Similarly, the stopper 26 screwed to the adjusting screw 22 of the expansion device 3a is also configured to press fit the adjusting screw 22, and the maximum stroke position of the piston 17 in the valve opening direction is adjusted by the press fitting amount. Also good.

It is a schematic diagram of the refrigerating cycle to which the expansion device according to the present invention is applied. It is a center longitudinal cross-sectional view which shows the structure of an expansion | swelling apparatus. It is a principal part expanded sectional view of a differential pressure valve. It is a figure which shows the change of the suction force of the valve body in a differential pressure valve. It is a center longitudinal cross-sectional view which shows another structural example of an expansion | swelling apparatus. It is a figure which shows an example of the valve opening characteristic of an expansion apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Gas cooler 3, 3a Expansion apparatus 4 Evaporator 5 Accumulator 6 Internal heat exchanger 7 Body 10 Housing 11 Refrigerant inlet 12 Strainer 13 Valve hole 14 Valve seat 15 Valve body 16 Cylinder 17 Piston 18 Fixed orifice 19 Side hole 20 Refrigerant outlet 21 Spring 22 Adjustment screw 23 Damper chamber 24 Fixed orifice 25 O-ring 26 Stopper a Port diameter b Valve body diameter

Claims (8)

The valve body is arranged in a state of being biased in the valve closing direction by a spring on the downstream side of the valve seat, and flows a refrigerant at a flow rate corresponding to the differential pressure between the primary pressure at the refrigerant inlet and the secondary pressure at the refrigerant outlet. In an expansion device capable of
An expansion device comprising a damper means provided on the valve body and absorbing a movement of the valve body in an opening / closing direction when the valve body receives a sudden pressure fluctuation of the refrigerant.   The damper means includes a cylinder formed in a housing extending in the same axial direction as the valve body and forming the valve seat, and a piston disposed in the cylinder and integrally formed with the valve body. The expansion device according to claim 1, further comprising a damper chamber whose volume is variable by the piston.   The damper chamber is closed by an adjustment member screwed or press-fitted into an opening end of the cylinder, and the spring is interposed between the piston and the adjustment member. Item 3. The expansion device according to Item 2.   The expansion device according to claim 3, wherein the adjustment member is provided with a fixed orifice communicating with the damper chamber.   The expansion device according to claim 3, further comprising a stopper that is screwed into the adjustment member so as to be movable back and forth in the axial direction or press-fitted in the axial direction, and restricts a stroke of the piston in a valve opening direction.   The expansion device according to claim 5, wherein the stopper is provided with a fixed orifice communicating with the damper chamber.   The expansion device according to claim 1, wherein the ratio (b / a) of the port diameter (a) of the valve hole to the valve body diameter (b) of the valve body is 1.5 or less. The expansion device according to claim 1, wherein the expansion device is applied to a refrigeration cycle in which the refrigerant is carbon dioxide.

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