Supercooling degree-controlled expansion valve

Abstract: To achieve a silent, noiseless operating supercooling degree-controlled expansion valve 10 wherein vibration of a valve element 14 induced by refrigerant flow changes is suppressed a resilient urging means 18 presses valve element 14 in an oblique direction inclined with respect to an axial direction thereof against a surrounding member 12 to thereby restrict vibration of the valve element.

Description: The invention relates to a supercooling degree-controlled expansion valve according to the preamble parts of claims 1 and 9. In refrigerating cycles so-called thermostatic expansion valves are widely used. Thermostatic expansion valves are designed to control the flow rate of the refrigerant being introduced into an evaporator in accordance with the temperature and pressure of the low-pressure refrigerant exiting the evaporator. Another possibility to control the flow rate of the refrigerant flowing into the evaporator is to use a so-called supercooling degree-controlled expansion valve, which in contrast to said thermostatic expansion valve detects and controls the degree of supercooling of the high-pressure refrigerant supplied to the evaporator. A supercooling degree-controlled expansion valve performs all required operations at the inlet side of the evaporator without needing any thermostatic equipment or additional temperature or pressure transmitting passages. This is advantageous because a supercooling degree-controlled expansion valve can be made extremely compact. In a supercooling degree-controlled expansion valve (US 4,324,112 A) the valve seat is arranged in a high-pressure refrigerant passage through which the refrigerant is supplied to the evaporator and at a location of an upstream side of a restricted portion formed by narrowing an intermediate portion of the refrigerant passage. The valve element for opening and closing the refrigerant passage faces the valve seat and is urged towards the valve seat by urging means from a downstream side. This valve type is structurally simple and compact and yet is capable of controlling the degree of supercooling of the high-pressure refrigerant at a constant level. However, in said known supercooling degree-controlled expansion valves the valve element freely vibrates due to the refrigerant flow and repeatedly collides against its surrounding member thus producing noise. US-A-5,004,008 discloses a refrigerant flow metering device the metering piston of which is loaded by a coil spring symmetrically surrounding the longitudinal axis of the metering piston. In an open state of the metering piston the flow dynamics of the refrigerant may cause lateral vibrations of the metering piston. US-A-4,194,527 discloses a pressure limiting valve for general hydraulic applications. A valve disk secured to a guide rod is moveable in relation to a valve seat opening. The guide rod is guided in a stationary abutment and is tilted sidewardly relative to the abutment to apply an eccentric force on the valve disk in order to achieve a damping effect. DE-A-30 45 892 discloses an expansion valve for a refrigerating system. Vibrations of a valve body in relation to a stationary valve seat are suppressed by a liquid cushion generated at the upstream side of the expansion valve by at least one throttling line. Further prior art is to be found in US-A-5,264,438, US-A-4,614,327, US-A-4,896,696 and EP-A-0 987 505. However, supercooling degree-controlled expansion valves need to operate reliably, extremely sensitive and in an environment (most often in the motor compartment of a vehicle) where permanently external vibration and considerable temperature changes occur. For this reason it was believed that the performance of such supercooling degree-controlled expansion valves would unduly suffer when implementing any vibration attenuating measures. It is an object of the invention to provide a structurally simple noiseless, silent supercooling degree-controlled expansion valve in which vibrations of the valve element induced by the refrigerant flow are suppressed sufficiently without deteriorating the valve performance, i.e. without harming the capacity of the valve to control an essential constant degree of supercooling. Said object is achieved with the feature combinations of claim 1, claim 2 and claim 5. Since the urging means in the supercooling degree-controlled expansion valve is pressing the valve element in an oblique direction inclined with respect to the axial direction of said valve element against a surrounding member or the surrounding when said valve member is moving in relation to said valve seat, noise is prevented from being produced as soon as the valve element has the tendency to collide during vibration under the influence of the refrigerant flow, etc. with its surrounding. Alternatively, a liquid damper using the refrigerant as a vibration absorbing material is coupled to the valve element to restrict vibrations of the valve element. A silent, high-quality supercooling degree-controlled expansion valve can be achieved. A particular simple structure of said expansion valve with a vibration safe valve element is achieved by determining the mechanical co-operation between the compression coil spring and the valve member such that the compression coil spring maintains the valve element during its motions in contact with the lateral surroundings. This either is achieved by a protruding spring turn end contacting the valve element offset to its longitudinal axis or by arranging the active compression coil spring end portion laterally offset with respect to the longitudinal axis of the valve element. Said predetermined co-operation suppresses particularly lateral vibrations of the valve element, because this is maintained in contact with the lateral surroundings while moving in relation to the valve seat, advantageously, said measure does not lead to any detrimental effect on the valve performance. When alternatively coupling the valve element with a liquid damper the refrigerant efficiently can be used to absorb vibrations of the valve element, particularly axial vibrations. The motion of the valve element during operation of the expansion valve sucks in or pumps out refrigerant into or from the cylinder chamber and through a narrow gap. The flow through said narrow gap is restricted and thus suppresses the vibration. Embodiments of the invention will be described with the help of the drawing. In the drawing is: Fig. 1 a longitudinal section of a first embodiment of an expansion valve in a state where a valve element is lifted from a valve seat, Fig. 2 a longitudinal section as in Fig. 1 with the valve element seated on said valve seat, Fig. 3 a cross-sectional view in section plane III - III of Fig. 2, Fig. 4 a longitudinal section of a refrigerant pipe receiving said expansion valve of Figs 1 to 3, Fig. 5 a longitudinal section of a second embodiment of an expansion valve, Fig. 6 a side view of a third embodiment of a supercooling degree-controlled expansion valve, Fig. 7 a longitudinal section of the third embodiment illustrating a flow direction from the right to the left, Fig. 8 a longitudinal section similar to Fig. 7 illustrating a flow direction from the left to the right, Fig. 9 an enlarged sectional side view of a detail of said third embodiment, Fig. 10 an enlarged sectional side view of another detail of said third embodiment, Fig. 11 a cross-section taken in plane XI - XI in Fig. 9, Fig. 12 a cross-section taken in plane XII - XII in Fig. 9, Fig. 13 a longitudinal sectional view of a fourth embodiment, and Fig. 14 a longitudinal sectional view of a fifth embodiment of a supercooling degree-controlled expansion valve. Figs 1 to 3 illustrate a first embodiment of a supercooling degree-controlled expansion valve 10. Fig. 4 shows said expansion valve 10 fitted into a refrigerant pipe 1 of an automobile cooling system, for example. In Fig. 4 high-pressure refrigerant is introduced from an upstream (left) side into refrigerant pipe 1. Expansion valve 10 abuts against a waist 1a formed, e.g. by crimping said refrigerant pipe 1. A dust-removing filter 11 is attached to an upstream-side half of expansion valve. In Fig. 2 expansion valve 10 is closed. A valve element 14 is resiliently urged from downstream against a valve seat 13 formed in a cylindrical case 12. Said dust-removing filter 11 (a cap made of fine meshed net) is attached to said cylindrical case 12. A downstream restricted passage 22 is provided. Dust-removing filter 11 catches impurities greater than a certain size. Accordingly, rubbish, etc. contained in the refrigerant is held back by the filter 11 and is prevented from flowing into the expansion valve or into said restricted passage 22. O-rings 15 fitted onto cylindrical case 12 seal between said case and the inner surface of refrigerant pipe 1. Valve seat 13 has inner circular edge at a stepped portion of a refrigerant passage 16 formed in cylindrical case 12. Said refrigerant passage 16 has an upstream-side passage 16a with a small diameter and a downstream-side passage 16b with a large diameter. Valve element 14 (Fig. 1) has a closing part 14a fitted into the valve seat 13, a conical part 14b facing said valve seat edge from a downstream side, three guide legs 14c extending through valve seat 13 and along the inner peripheral surface of the upstream-side passage 16a, and three supporting legs 14d protruding downstream and extending along the inner peripheral surface of downstream-side passage 16b. Valve element 14 faces valve seat 13 while being urged from downstream by a compression coil spring 18, defining said resilient urging means of the expansion valve 10. Depending on the relative magnitude of the refrigerant pressure difference between the upstream and downstream sides of valve seat 13 and on the urging force of compression coil spring 18, valve element 14 comes in contact with or is separated from said valve seat edge, in order to control the flow rate of the refrigerant passing through said refrigerant pipe 1. Said compression coil spring 18 does not have end turns at its opposite ends which end turns would define a plane perpendicular to the longitudinal spring axis, but each end portion is formed by simply cutting the wire member constituting the spring turns. Particularly, a freely terminating turn end is made by cutting the end turn, e.g., perpendicular to the core line of said end turn. Said end turn may extend towards said free turn end with at least essentially the same turn pitch as other spring turns in said compression coil spring. Consequently, the urging force of the compression coil spring 18 acts upon the valve element 14 in a oblique direction inclined with respect thereto. The free turn end of compression coil spring 18 contacts an abutment surface of said valve element 14 which is surrounded by said legs 14d and at a force transmission spot which is offset with respect to the longitudinal axis of valve element 14. Instead or in addition, said abutment surface could be inclined with respect to the longitudinal axis of said valve element 14 by an angle differing from 90°. A spring seat member 20 receives a fixed end portion of said compression coil spring 18. Seat member 20 is secured to a downstream-side end of cylindrical case 12. In Fig. 3 spring seat member 20 has an annular restriction defining said restricted passage 22. It has a small cross-sectional area and is continuing circumferentially distributed refrigerant passage holes 21. The refrigerant passing therethrough adiabatically expands on the downstream side of said restricted passage 22. An evaporator (not shown) is connected to the downstream side of expansion valve 10, so that the refrigerant is introduced into the evaporator while being adiabatically expanded. The high-pressure refrigerant at the upstream side of valve seat 13 is in a supercooled liquid state. After passing the gap between the valve seat edge and lifted valve element 14, however, it is no longer supercooled but develops bubbles. If the degree of supercooling of the high-pressure refrigerant at the upstream side decreases, more bubbles are produced in the refrigerant on the downstream side of the valve seat 13, causing a consequent reduction in the refrigerant flow rate. Valve element 14, therefore, is moved in closing direction (Fig. 2) with the result that the degree of supercooling of the refrigerant at the upstream side does increase again. If the degree of supercooling of the high-pressure refrigerant at the upstream side increases, less bubbles are produced in the refrigerant at the downstream side of valve seat 13. The refrigerant flow rate increases as well. Valve element 14, therefore, is moved in opening direction (Fig. 1) thus reducing the degree of supercooling at the upstream side. Thanks to these valve element motions, the degree of supercooling of the high-pressure refrigerant is maintained constant at the upstream side. During its motion valve element 14 remains pressed against the inner peripheral surface of refrigerant passage 16, since the urging force of compression coil spring 18 is acting upon the valve element 14 in an oblique direction, i.e. , is inclined with respect to its axial direction or the direction of its longitudinal axis, respectively. As a result, valve element 14 is never allowed to vibrate freely in lateral directions even if the refrigerant flow changes or more or less bubbles occur, or like occurs, and thus no noise is produced. Fig. 5 (a second embodiment) closing part 14a of valve element 14 is not fitted into valve seat 13 (as in Fig. 1), but directly abuts against the valve seat 13 from the downstream side to close the refrigerant passage 16. Valve seat 13 is constituted by an annular, axially extending rib. Closing part 14a here is made of an elastic material such as rubber. Other structural features in the operation are the same as with the first embodiment. In Figs 7 through 12 a third embodiment is a bi-directional supercooling degree-controlled expansion valve 10 (the refrigerant can flow in opposite directions). In Fig. 6 dust-removing filters 11 are attached to both, front and rear ends of the expansion valve 10, respectively. In Figs 7 and 8 two valve seats 13 are arranged in series and two valve elements 14 are arranged back-to-back between valve seats 13. Compression coil spring 18 constituting the urging means for both valve elements is interposed between both valve elements 14. Restricted passages 22 each for adiabatically expanding the refrigerant depending on the flow direction are defined by spherical valve elements 30 arranged within said valve elements 14. In Figs 9 and 10 each valve element 14 has a spherical-valve receiving chamber 32 formed in an intermediate portion of an axially extending refrigerant passage 31 receiving the corresponding spherical valve element 30. Of the two spherical valve elements 30, that valve element 30 in the respective upstream-side valve element 14 closes the refrigerant passage 31, as shown in Fig. 9. The spherical-valve receiving chamber 32 has a diameter size larger than the diameter of the spherical valve element 30. A gap is formed around the downstream-side spherical valve element 30, while this is in contact with and centred by three small protuberances 34 (Fig. 10). Restricted passage 22 is defined by said gap in the respective downstream-side valve element 14. Compression coil spring 18 does not have flattened end turns at its opposite ends but each end portion is formed by simply cutting a wire member, as has been explained in detail in connection with the first embodiment. Consequently, the urging force of compression coil spring 18 acts upon each valve element 14 in an oblique direction inclined with respect to the axial direction of the expansion valve 10. Thus, the valve elements 14 never are allowed to laterally vibrate when opened or closed due to a change of the refrigerant flow, so that no noise is produced. Instead, they are laterally held in contact with their respective valve seat 13. In Fig. 13 in a fourth embodiment compression coil spring 18 and valve element 14 are arranged eccentrically with respect to each other, i.e., the longitudinal axis of compression coil spring 18 or at least of its end portion and the longitudinal axis of valve element 14 are offset in lateral direction relative to another. With this eccentric arrangement, even when compression coil spring 18 should have normal flattened end turns formed at its opposite ends, i.e., end turns in planes perpendicular to the longitudinal axes of the coil spring and the valve element, the urging force of the compression coil spring 18 acts upon valve element 14 in an oblique direction inclined with respect to the axial direction thereof. Accordingly, valve element 14 is always pressed against the inner peripheral surface of refrigerant passage 16 and thus is never allowed to vibrate laterally, so that no noise is produced. In Fig. 14 in a fifth embodiment a hydraulic vibration suppressing means is provided. A piston-like part 14e formed at the head of valve element 14 is received with a narrow radial gap in a cylinder 40 provided at the upstream-side refrigerant passage 16a. With valve element 14 moving, the refrigerant flows into and out of cylinder 40 through said gap defined between piston-like part 14a and its cylinder 40, thus forming a liquid damper using the refrigerant itself as a damping material. Thus, even fine axial vibrations of valve element 14 can be suppressed.

Claims: A supercooling degree-controlled expansion valve (10) comprising a refrigerant passage (16) through which a refrigerant is supplied to an evaporator, a restricted portion (22) formed by a narrowed intermediate portion of said refrigerant passage, a valve seat (13) arranged upstream of said restricted portion (22), a valve element (14) for opening and closing said refrigerant passage arranged facing said valve seat at the downstream side, and resilient urging means at said downstream side urging said valve element (14) towards said valve seat (13) such that the refrigerant is supplied to the evaporator while being adiabatically expanded with a degree of supercooling, said degree of supercooling being maintained essentially constant at the upstream side of said valve seat (13), characterised in that an in-built mechanical valve element vibration suppressing means is constituted by said urging means (18) pressing said valve element (14) in an oblique direction inclined relative to an axial direction thereof against a surrounding member (12) to thereby restrict vibration of said valve element (14). The supercooling degree-controlled expansion valve (10) as in claim 1, characterised in that said-urging means (18) comprises a compression coil spring having no end turn formed therein such that the urging force thereof acts upon said valve element (14) in said oblique direction inclined with respect to said valve element (14). The supercooling degree-controlled expansion valve as in claim 1, characterised in that said urging means (18) is arranged eccentrically with respect to said valve element (14) such that the urging force thereof acts upon said valve element (14) in said oblique direction inclined with respect to said valve element (14). The supercooling degree-controlled expansion valve as in claim 1, characterised in that said urging means is a compression coil spring abutting with its one end portion directly against an abutment surface of said valve element (14), said compression coil spring (18) and said valve element (14) each having a longitudinal axis, said compression spring (18) transmitting an urging force onto said valve element (14) in a direction at least essentially parallel to said longitudinal axes and at a single urging force transmission spot located sidewardly offset with respect to said longitudinal axes of said valve element (14). The supercooling degree-controlled expansion valve (10) as in claim 1, characterised in that said urging means is a compression coil spring (18) having a spring end turn freely terminating at a cut-off turn end, said end turn extending said cut-off turn end with at least the same turn pitch as further turns of said compression spring. The supercooling degree-controlled expansion valve as in claim 5, characterised in that said spring turn end is cut-off essentially perpendicular to the spring end turn core line. The supercooling degree-controlled expansion valve as in claim 4, characterised in that said abutment surface of said valve element (14) is inclined by an angle differing from 90° with respect to said longitudinal axis of said valve element. The supercooling degree-controlled expansion valve as in claim 1, characterised in that said urging means is a compression spring the end turns at both end portions of which have freely terminating cut-off turn ends, and that each end turn is extending towards its cut-off turn end with essentially the same turn pitch as further turns of the compression coil spring between both end portions. A supercooling degree-controlled expansion valve (10) comprising a refrigerant passage (16) through which a refrigerant is supplied to an evaporator, a restricted portion (22) formed by a narrowed intermediate portion of said refrigerant passage, a valve seat (13) arranged upstream of said restricted portion (22), a valve element (14) for opening and closing said refrigerant passage arranged facing said valve seat at the downstream side, and resilient urging means at said downstream side urging said valve element (14) towards said valve seat (13) such that the refrigerant is supplied to the evaporator while being adiabatically expanded with a degree of supercooling, said degree of supercooling being maintained essentially constant at the upstream side of said valve seat (13), characterised in that an in-built hydraulic valve element vibration suppressing means is provided with a liquid damper (14, 40) using said refrigerant as a vibration absorbing material, said liquid damper being coupled to said valve element (14) to thereby restrict vibration of said valve element (14), and that inside said valve seat (13) at its upstream side a cylinder chamber (40) is provided extending parallel to a central axis of said valve seat (13) and parallel to said longitudinal axis of said valve element (14), said valve element (14) having a coaxial piston-like part (14e) being received in said cylinder chamber (40) with a radial gap, said cylinder chamber (40) communicating with the upstream side of said valve seat (13) via said radial gap. The supercooling degree-controlled expansion valve as in claims 1 to 8, characterised In that said valve seat (13) comprises two valve seats arranged in series, that said valve element (14) is constituted by two valve elements arranged at locations between said two valve seats, each valve element (14) facing one of said valve seats such that, regardless of whether the refrigerant is made to flow in a forward or backward direction, the refrigerant is supplied while being adiabatically expanded with the degree of supercooling maintained constant at an upstream side of the respective valve seat.

Inventors: HIROTA HISATOSHI, INOUE YUSUKE, TSUGAWA TOKUMI, HIROTA, HISATOSHI, INOUE, YUSUKE, TSUGAWA, TOKUMI, Hirota, Hisatoshi, c/o TGK Co., Ltd., Inoue, Yusuke, c/o TGK Co., Ltd., Tsugawa, Tokumi, c/o TGK Co., Ltd.
Applicants: TGK CO LTD, TGK CO., LTD.
Application year: 2000
Main classification: F25B41
IPC codes: G05D7, F25B41, F16K17, F25B43