Patent Publication Number: US-2022214090-A1

Title: Expansion valve

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claim priority to International Patent Application No. PCT/EP2020/061842 filed Apr. 29, 2020, which also claims priority to German Patent Application DE 10 2019 206 197.4 filed Apr. 30, 2019, the contents of each of which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to an expansion valve for an air conditioning system of a motor vehicle. The invention moreover relates to a permanent magnet body for such an expansion valve as well as an air conditioning system of a motor vehicle comprising an expansion valve of this type. 
     BACKGROUND 
     Expansion valves, also referred to as throttle valves, are valves, which reduce the pressure of a fluid flowing through by means of a local narrowing of a flow cross section, and thus effect a volume increase or expansion, respectively. In air conditioning systems, in particular in motor vehicles, such an expansion valve reduces the pressure of a refrigerant, which usually penetrates into the expansion valve as virtually boiling liquid. It thereby experiences an isenthalpic change in state because the refrigerant relaxes when passing through the expansion valve (pressure drop of, e.g., 10 bar to 1 bar with simultaneous drop of the liquid temperature). The goal of the expansion in the valve is that the liquid reaches into the evaporator with low overheating (still liquid). The refrigerant subsequently reaches into the evaporator, in which the evaporation process of the liquid portion of the refrigerant absorbs heat from the surrounding area and thus evaporates. The fluid or air, respectively, which flows through the evaporator (heat exchanger), is cooled thereby. 
     However, in the case of the electric expansion valves known from the prior art, it is a disadvantage that, in order to detect a valve position, they usually have separate permanent magnets, which are arranged at a rotor of an expansion valve and which not only require an additional assembly effort, but also an additional installation space need. 
     The present invention thus deals with the problem of specifying an improved or at least an alternative embodiment for an electric expansion valve, which is characterized in particular by means of a compact construction. 
     This problem is solved according to the invention by means of the subject matter of the independent claim(s). Advantageous embodiments are subject matter of the dependent claims. 
     SUMMARY 
     The present invention is based on the general idea of integrating a permanent magnet, which determines a position of a valve body, into a permanent magnet, which effects the rotation of the valve body, and to thus attain a lower material usage as a whole, but to in particular also reduce the installation space need currently required for the position magnet. The expansion valve according to the invention, which can be used, for example, for an air conditioning system and/or also for a heat exchanger (chiller) for the battery cooling or oil cooling of a motor vehicle, has a housing, a sensor, a stepping motor or a brushless DC (BLDC) motor, a valve seat, as well as a valve body interacting therewith. The valve body is preferably formed as so-called valve needle and can be pre-tensioned into its closed position against the valve seat by means of a spring, wherein a spring of this type can in particular be used for the tolerance compensation. The stepping motor or the BLDC motor has a rotor as well as a stator surrounding said rotor, for example at least two electric coils, which surround said rotor and which are arranged spaced apart from one another in the axial direction of the rotor. An adjustment of the valve body and thus an opening or closing, respectively, of the expansion valve thereby takes place by means of a rotation of the rotor, whereupon the latter is adjusted in the axial direction together with the valve body. The rotor has a shaft as well as a permanent magnet body, which is connected thereto in a rotationally fixed manner. In response to a rotation of the shaft, an axial adjustment thereof takes place together with the valve body in the direction of the valve seat or away from the latter. An axial position and/or an angle of rotation of the permanent magnet body is/are detected via the sensor, and the opening position or the closing position, respectively, of the expansion valve are thus monitored. With the idea according to the invention, according to which the permanent magnets required for the rotation of the shaft as well as the permanent magnets required for detecting the position of the valve body and thus for detecting an opening state of the expansion valve, are integrated into the permanent magnet body, a permanent magnet body of a particularly compact construction can be attained, which does not only reduce an installation space need required for the expansion valve, but also the material usage for producing the permanent magnet body. The expansion valve according to the invention can thus be produced in a cost-efficient, resource-saving, and installation space-optimized manner. 
     In the case of an advantageous further development of the invention, the permanent magnet body is formed in a pot-shaped manner and has a signal generator region and a rotor region. The signal generator region thereby preferably faces the sensor, while the rotor region surrounds the shaft. Due to the fact that the rotor region of the permanent magnet body is arranged in a ring-shaped manner spaced apart around the shaft, a portion of the shaft can be arranged within the rotor region of the permanent magnet body and can thus be accommodated in a space-saving manner. 
     The shaft advantageously has a first longitudinal end region and a second longitudinal end region, and is arranged in a rotationally fixed manner with its first longitudinal end region in the signal generator region of the permanent magnet body, and has a blind hole-like recess at its second longitudinal end region for receiving the valve body. A particularly installation space-optimized embodiment can also be attained thereby. 
     The shaft and the valve body are advantageously at least partially arranged within a valve body guide, wherein the shaft has an external thread and the valve body guide has a corresponding internal thread, or vice versa, so that, in response to a rotation of the shaft, an axial adjustment of the latter takes place together with the permanent magnet body, and the valve body is thus pushed onto the valve seat or is lifted off from the latter. The sensor can thus detect an axial adjustment and/or a rotation of the permanent magnet body in this case because the latter adjusts axially together with the shaft in response to a rotation of the latter. It goes without saying that, in the alternative, it can also be provided that the shaft has an external thread and the valve body guide has a corresponding internal thread, or vice versa, wherein, in response to a rotation of the shaft, an axial adjustment of the latter takes place independently of the permanent magnet body, and the valve body is thus pushed onto the valve seat or is lifted off from the latter. The sensor thus detects only a rotation of the permanent magnet body in this case, because, in response to a rotation of the shaft, only the latter is adjusted axially in this case, but not the permanent magnet body, which remains axially in its place and thus at the same distance from the sensor. 
     The external thread at the shaft and the corresponding internal thread can generally be considered analogously to a threaded spindle, in the case of which a rotatory movement is converted into a translatory movement. Threaded spindles consist of a threaded rod, thus a cylindrical round bar, on which a trapezoidal, sharp, or flat thread is attached in simple applications. A sharp thread, in particular with the metric measurements M5×0.25, is thereby particularly advantageous for cost reasons. 
     In the case of an advantageous further development of the solution according to the invention, a split pot is provided, which surrounds the rotor and separates a rotor-side wet region from a stator-side dry region. The expansion valve according to the invention can thus be formed as so-called wet running meter, in the case of which the rotor is arranged in the refrigerant. By means of the split pot, however, the comparatively sensitive coils as well as the electronics of the control board can be kept dry reliably, whereby they are arranged in a protected manner, and the expansion valve according to the invention can thus be kept functional in the long term. 
     In its signal generator region, the permanent magnet body advantageously has at least one magnetic pole pair. A magnetic pole pair of this type, consisting of a north pole and a south pole, provides for a comparatively simple distance or range measurement, respectively, and/or an angle of rotation change, which can be converted directly into a degree of opening of the expansion valve, for a corresponding sensor, for example a 3D Hall sensor. A contactless and touchless distance detection can take place via a 3D Hall sensor of this type, which in particular provides the large advantage that the 3D Hall sensor can be arranged in the dry region of the expansion valve, while the rotor or the permanent magnet body, respectively, can be arranged in the wet region. Via a sensor of this type, it is possible to detect all spatial directions by means of a single sensor, which does not only offer cost advantages, but also installation space advantages. Hall sensors of this type furthermore offer the large advantage that they supply a signal even if the magnetic field, in which the respective Hall sensor is located, is constant. 
     According to this, an angle of rotation position or a distance of the rotor from the Hall sensor, respectively, and thus also an opening state of the expansion valve can be detected comparatively easily. 
     In the case of a further advantageous embodiment of the solution according to the invention, the shaft breaks through the signal generator region of the permanent magnet body. This provides the large advantage that in the case of an assembly of the expansion valve according to the invention, in the case of which the spring is initially (optionally) inserted into the blind hole-like recess at the second longitudinal end region of the shaft and the valve body is subsequently plugged in, a ring element, which limits a maximum extended position of the valve body from the blind hole-like recess, can also be pressed into the blind hole-like recess. For pressing in a ring element of this type, the shaft has to be pushed against an abutment, which is possible comparatively easily in the case of a shaft, which breaks through the permanent magnet body, because the shaft is not supported on the permanent magnet body in this case, but directly on a corresponding abutment. Significant assembly advantages of the rotor can be attained thereby. 
     In the case of a further advantageous embodiment of the solution according to the invention, the shaft is connected in a positive manner and/or by means of a substance-to-substance bond at its first longitudinal end region to the signal generator region of the permanent magnet body. It is conceivable thereby, for example, that the shaft has a corresponding recess or knurling, respectively, or a collar, wherein the signal generator region of the corresponding permanent magnet body has negative contours, which are formed complementary thereto. A positive connection between the permanent magnet body and the shaft, which can be additionally supported, for example, by using an adhesive, can be attained thereby. A comparatively simple positive and torque-transmitting connection between the shaft and the signal generator region of the permanent magnet can be attained by means of, for example, a non-round collar at the shaft. 
     The present invention is further based on the general idea of specifying a permanent magnet body for an expansion valve, which was described in the preceding paragraphs, which is formed in a pot-shaped manner and which has a signal generator region forming the pot base as well as a rotor region forming a pot wall, and which, in its rotor region, has several magnetic poles, which extend in the axial direction and which are additionally arranged so as to alternate in the circumferential direction. A permanent magnet body of this type can thereby be produced as pre-fabricated assembly or can be delivered in two pieces, wherein the two pieces can be attached comparatively easily in a positive manner to a corresponding shaft and can be connected to the latter in a positive manner. In the case of this version comprising the two half shells or in the case of the fully produced, i.e. one-piece version, of the permanent magnet body, an adhesive could additionally be used for the rotationally fixed fixation of the shaft in the signal generator region of the permanent magnet. A magnet with a particularly compact construction, which, due to its rotor region, is additionally able to receive a majority of the shaft as well as at least a portion of a needle-shaped valve body as well as of a valve body guide in its and to thus likewise arrange it in a particularly installation space-optimized manner, can be created by means of a permanent magnet body of this type according to the invention. 
     The present invention is further based on the general idea of specifying an air conditioning system of the motor vehicle comprising a compressor, an evaporator, a condenser, and an expansion valve described in the preceding paragraphs, in order to thus be able to transfer the advantages of the expansion valve described in the preceding paragraphs to the air conditioning system. 
     The invention is additionally based on the idea of using such an expansion valve in an oil cooler or a cooling system for batteries by means of heat exchanger (chiller refrigerant-cooling water circuit) and condenser in combination with the vehicle air conditioning system or also in an independent cooling circuit. 
     Further important features and advantages of the invention follow from the subclaims, from the drawings, and from the corresponding figure description on the basis of the drawings. 
     It goes without saying that the above-mentioned features and the features, which will be described below, cannot only be used in the respective specified combination, but also in other combinations or alone, without leaving the scope of the present invention. 
     Preferred exemplary embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, whereby identical reference numerals refer to identical or similar or functionally identical components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In each case schematically, 
         FIG. 1  shows a sectional illustration through an expansion valve according to the invention, 
         FIG. 2  shows a detailed sectional illustration through a permanent magnet body according to the invention, 
         FIG. 3  shows an air conditioning system comprising an expansion valve according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     According to  FIG. 1 , an expansion valve  1  according to the invention for an air conditioning system  2  of a motor vehicle  3  (see  FIG. 3 ) has a housing  4 , a sensor  29 , a control board  5 , a stepping motor  6  or a BLDC motor, a valve seat  7 , as well as a valve body  8  interacting therewith, and a valve body guide  9 , which is firmly connected to the housing  4 . The stepping motor  6  or the BLDC motor has a rotor  10  and, in this case, at least two coils  11 , which surround the rotor  10  and which form the stator. Viewed in the axial direction  12 , the coils  11  are thereby arranged offset or spaced apart from one another, respectively. The rotor  10 , in turn, has a shaft  13  as well as a permanent magnet body  14 , which is connected thereto in a rotationally fixed manner (see in particular  FIG. 2 ) and which is preferably formed in a pot-shaped manner and can have a signal generator region  15  as well as a rotor region  16 . The signal generator region  15  thereby faces the control board  5  or the sensor  29 , respectively, while the rotor region  16  surrounds a majority of the shaft  13 . According to the invention, the sensor  29  is formed to detect an axial position and/or an angle of rotation of the permanent magnet body  14 . In the shown case, the shaft  13  is also surrounded by the permanent magnet body  14  by the latter in the region of the signal generator region  15 . The shaft  13  has a first longitudinal end region  17  as well as a second longitudinal end region  18  (see also  FIG. 2 ) and is integrated firmly, in particular in a rotationally fixed manner, with its first longitudinal end region  17  into the signal generator region  15  of the permanent magnet body  14 , and additionally has a blind hole-like recess  19  at its second longitudinal end region  18  for receiving the valve body  8  as well as a spring  20 , which pre-tensions said valve body in the direction against the valve seat  7 . 
     As can thereby be gathered in particular from  FIG. 1 , the shaft  13  and the valve body  8  are at least partially arranged within the valve body guide  9 , which, in turn, is firmly connected to the housing  4 , in particular for example by means of a pressing or an adhesion. 
     For adjusting the valve body  8  in the axial direction  12  and thus for an opening or closing, respectively, of the expansion valve  1  according to the invention, a rotation of the rotor  10  takes place, wherein the axial adjustment can preferably be effected by means of a thread, which is arranged between the shaft  13  and the valve guide  9 . For this purpose, the shaft  13  has an external thread  21 , while the valve body guide  9  has a corresponding internal thread  22 , which interacts with the external thread  21 , so that, in response to a rotation of the shaft  13 , an axial adjustment of the latter takes place together with the permanent magnet body  14 , and the valve body  8  is thus pushed onto the valve seat  7  or is lifted off from the latter. A rotation of the rotor  10  is thereby effected by means of the corresponding supply of current to the stator or the coils  11 , respectively. If the rotor  10  is thus rotated, it is adjusted downwards, for example in the axial direction  12  according to  FIG. 1 , whereupon the spring  20 , which is arranged in the blind hole-like recess  19 , is pushed and is thus tensioned, and pre-tensions the valve body  8  against the housing-side valve seat  7 . If an opposite rotation of the rotor  10  takes place by means of a corresponding supply of current to the coils  11 , said rotor is adjusted upwards in the axial direction  12 , whereby the spring  20  relaxes, and the contact pressure of the valve body  8  on the valve seat  7  is initially reduced, until the valve body  8  abuts with its collar  24  against a ring element  23 , which is pressed into the blind hole-like recess  19 . The maximum extended state of the valve body  8  out of the blind hole-like recess  19  is attained in this state, so that a lift-off of the valve body  8  from the valve seat  7  takes place in response to a further adjustment of the rotor  10  to the top. 
     In response to a rotation of the shaft  13 , an axial adjustment of the latter can then take place together with the permanent magnet body  14  or separately therefrom, and the valve body  8  can thus be pushed onto the valve seat  7  or can be lifted off from the latter. 
     The ring element  23  can thereby be pressed into the blind hole-like recess  19 , wherein a radial distance to the valve body  8  remains at all times, so that the latter is arranged in a touchless manner to the ring element  23 . The shaft  13  can generally be slidingly mounted in the valve body guide  9  in an upper region, that is, in the region above the spring  20 . 
     When further looking at  FIG. 1 , it can be seen that a split pot  25 , which surrounds the rotor  10 , is provided, which separates a rotor-side wet region  26  from a coil-side/stator-side dry region  27 . The control board  5  as well as the stator or the coils  11 , respectively, is thus arranged in the dry region  27  and thus in a protected manner. 
     When looking at the permanent magnet body  14  according to the invention in more detail (see in particular  FIG. 2 ), it can be seen that the latter has, in its rotor region  16 , several magnetic poles  28  (north-south), which are radially spaced apart from the shaft  13  and which extend in the axial direction  12 , and which are additionally arranged so as to alternate in the circumferential direction. In its signal generator region  15 , the permanent magnet body  14  has at least one magnetic pole pair, which, according to  FIG. 2 , consists of a semi-circular north pole and a semi-circular south pole. A sensor  29 , in particular a 3D Hall sensor (see  FIG. 1 ), which faces the shaft  13  and which can detect a distance between a first longitudinal end  30  of the shaft  13  and the 3D Hall sensor, and thus an opening state of the expansion valve  1 , is additionally arranged at the control board  5 . 
     As can be gathered from  FIGS. 1 and 2  thereby, the shaft  13  of the rotor  10  breaks through the signal generator region  15  of the permanent magnet body  14 , which further provides the large advantage that, in response to a press-in of the ring element  23  into the blind hole-like recess  19  at the second longitudinal end region  18  of the shaft  13 , after the insertion of the spring  20  and of the valve body  8 , a support does not take place via the permanent magnet body  14 , but only via the shaft  13  itself, because the latter extends beyond the signal generator region  15  of the permanent magnet body  14  with its longitudinal end  30  according to  FIGS. 1 and 2 . 
     A connection between the permanent magnet body  14  and the shaft  13  thereby takes place via a positive connection and/or substance-to-substance bond, whereby it is conceivable that, at its first longitudinal end region  17 , the shaft  13  is connected in a positive manner and/or by means of a substance-to-substance bond to the signal generator region  15  of the permanent magnet body  14 . A positive connection, which furthermore allows for a torque transmission, is conceivable, for example, by means of a non-round positive connection body  31  and a negative contour  32  in the permanent magnet body  14 , which is formed complementary thereto. A torque transmission can take place between the permanent magnet body  14  and the shaft  13  via a positive connection of this type, wherein an axial adjustment between them can be permitted. It goes without saying that the rotationally fixed connection between the permanent magnet body  14  and the shaft  13  can be additionally supported by means of an adhesive and thus a substance-to-substance bond. An axial relative adjustment between permanent magnet body  14  and shaft  13  would be prevented in this case. In particular in this case, the permanent magnet body  14  would be fastened to the shaft  13  in such a way that both are coupled in the axial direction of movement. It is conceivable thereby, for example, that the signal generator region  15  consists of two semi-circular magnetic poles (north-south), which are attached to the positive connection body  31  of the shaft  13  in the radial direction, and which are firmly connected to said positive connection body subsequently. 
     It is also conceivable that the shaft  13  is extrusion-coated directly with a plastic, in particular thermoplastic, e.g. PA 6, to which magnetizable particles (ferrum, neodymium . . . ) are added, and the permanent magnet body  14  is thus produced. In contrast to sintered alternatives, this provides the advantage of a high strength and bond to the shaft  13 . 
     Due to the integration of the signal generator region  15  as well as of the rotor region  16  in a one-piece permanent magnet body  14 , a functional integration can be created, so that the rotor region  16  required for rotating the rotor  10  and thus for opening or closing, respectively, the expansion valve  1 , and the signal generator region  15  required for detecting an opening state or closing state, respectively, of the expansion valve  1 , can be integrated into a single, common permanent magnet body  14 , whereby the latter is of a more compact construction. 
     It is generally also conceivable that the signal generator region  15  and/or the permanent magnet body  14  have/has a constant distance from the sensor  29 . An adjustment of the expansion valve  1  thus takes place exclusively by means of a rotation of the permanent magnet body  14  in this case. The shaft  13  can thereby be supported in an axially movable manner in the permanent magnet body  14 . 
     The expansion valve  1  according to the invention, together with the permanent magnet body  14  according to the invention can be used, for example, in an air conditioning system  2  of a motor vehicle  3 , as it is illustrated according to  FIG. 3 , wherein an air conditioning system  2  of this type additionally comprises a compressor  33 , an evaporator  34 , as well as a condenser  35 . 
     A cost-efficient, functionally integrated, and additionally installation space-optimized expansion valve  1  can thus be created by means of the expansion valve  1  according to the invention.