Lift valve for a refrigeration or air conditioning circuit of a motor vehicle

Abstract

A globe valve for a refrigeration circuit or air-conditioning circuit of a motor vehicle, with a drive unit (12), a valve body (66) which is operatively connected to the drive unit (12) and can be moved translationally between different positions in the case of an actuation of the drive unit (12), a valve seat (68) which delimits a throughflow cross section together with the valve body (66), and a sensor device (82) which comprises a stroke sensor (83), wherein the stroke sensor (83) interacts with a permanent magnet (86) which can be moved translationally together with the valve body (66) by the drive unit (12), wherein an additional permanent magnet (88) is arranged rigidly in the region of the stroke sensor (83) in such a way that the stroke sensor (83) detects an overlap of the magnetic field of the permanent magnet (86) which can be moved translationally together with the valve body (66) and the magnetic field of the additional permanent magnet (88).

Description

[0001] DESCRIPTION

[0002] Lift valve for a refrigeration or air conditioning circuit of a motor vehicle

[0003] The invention relates to a lift valve for a refrigeration or air conditioning circuit of a motor vehicle, comprising a drive unit, a valve body which is operatively connected to the drive unit and is translationally adjustable between different positions upon actuation of the drive unit, a valve seat which, together with the valve body, delimits a flow cross-section, and a sensor device which has a lift sensor, wherein the lift sensor interacts with a permanent magnet which, together with the valve body, is translationally displaceable by the drive unit.

[0004] Such globe valves are generally known from the prior art, particularly for refrigeration or air conditioning circuits. For example, such globe valves are known in the form of expansion valves, which serve to reduce the pressure of the working fluid by throttling the available flow cross-section and to increase the volume of the working fluid, i.e. to expand it. By using controlled expansion valves, both the pressure drop and thus the volume increase can be controlled and the fluid flow can be almost completely interrupted. In refrigeration or air conditioning circuits, these valves are arranged upstream of the evaporators and downstream of the condensers. Due to the increase in volume, the working fluid is partially evaporated, while the still liquid working fluid in the evaporator absorbs heat, causing the liquid part to also evaporate.This now gaseous working fluid is fed to a compressor and compressed, before being converted back into the liquid state in the condenser, forming a closed circuit. Heat or cold can be extracted from this circuit in the evaporator and condenser areas.

[0005] In order to be able to regulate the pressure drop at the expansion valve and the associated volume increase as precisely as possible, it is desirable to know the position of the valve body relative to the valve seat as precisely as possible and to be able to regulate it accordingly.

[0006] For this purpose, a stroke sensor is usually provided which interacts with a permanent magnet, whereby the permanent magnet at an axial end of the valve body or a component firmly connected to the valve body moves translationally together with the valve body. The stroke sensor has a predefined measuring range. The measuring range is divided into two areas in order to measure the magnetic flux density in both directions. By arranging the permanent magnet at the axial end of the valve body or the component attached to it and by arranging the stroke sensor in the area of ​​the front end of the valve body or the component, the stroke sensor measures the magnetic flux density exclusively in one of the two directions that can be measured by the stroke sensor, so that the measuring range is only partially utilized and the resolution of the measurement signal from the stroke sensor is reduced.The reduced usable measuring range of the stroke sensor is particularly disadvantageous in the range of large strokes of the valve body, i.e. when there is a relatively large distance between the permanent magnet and the stroke sensor, since an inverse relationship between the distance between the permanent magnet and the stroke sensor and the magnetic flux density means that, in contrast to the range of small strokes, i.e. when there is a relatively small distance between the permanent magnet and the stroke sensor, the change in magnetic flux density is relatively small in the range of large strokes. In combination with the reduced resolution of the stroke sensor, i.e. the use of a partial range of the available measuring range of the stroke sensor, this means that the position of the valve body relative to the valve seat cannot be reliably detected.

[0007] The task therefore arises to provide a lift valve for a refrigeration or air conditioning circuit of a motor vehicle in which the position of the valve body can be detected as accurately and reliably as possible.

[0008] This object is achieved by a lift valve for a refrigeration or air conditioning circuit of a motor vehicle having the features of claim 1.

[0009] The lift valve has a drive unit for the translational displacement of a valve body, whereby the valve body can be adjusted between different positions, preferably continuously, by actuating the drive unit.

[0010] The globe valve further comprises a sensor device for detecting the position of the valve body, wherein with the aid of the sensor device, the valve body can be adjusted to different positions with a high degree of accuracy and thus a flow cross-section limited by the valve body and a valve seat can be adjusted as required. The sensor device comprises a stroke sensor and a permanent magnet. The stroke sensor is rigid, for example arranged on a valve housing or on another component of the globe valve. The permanent magnet is arranged at an axial end, in particular on the front side, on the valve body or on a component fastened to the valve body. During a translational movement of the valve body, ieIn the axial direction, the permanent magnet moves with the valve body. With the movement of the permanent magnet, the distance between the permanent magnet and the stroke sensor, which is a magnetic field sensor, in particular a Hall sensor, changes, thereby also changing the magnetic flux density detected by the stroke sensor. The stroke sensor has a defined measuring range, wherein the measuring range is preferably divided into two equal areas for detecting the magnetic flux density in both directions.

[0011] According to the invention, an additional permanent magnet is arranged in the region of the stroke sensor, i.e., in the region detectable by the stroke sensor, which is rigidly arranged, whereby the magnetic flux density of the additional permanent magnet detectable by the stroke sensor remains unchanged. The stroke sensor thus detects a superimposed magnetic flux density from the constant magnetic flux density of the additional permanent magnet and the magnetic flux density of the permanent magnet, which fluctuates during a stroke movement. Preferably, the additional permanent magnet is arranged rotated by 180° relative to the permanent magnet such that the north pole of the additional permanent magnet faces the north pole of the permanent magnet or the south pole of the additional permanent magnet faces the south pole of the permanent magnet.As a result, the stroke sensor detects a superimposed magnetic flux density from the constant magnetic flux density of the additional permanent magnet and the magnetic flux density of the permanent magnet, which changes during a stroke movement, whereby the direction of the superimposed magnetic flux density reverses at a certain stroke.

[0012] This allows the entire measuring range of the stroke sensor to be used to detect the magnetic flux density during the adjustment of the valve body, which improves the resolution of the stroke sensor and reduces the susceptibility of the stroke sensor to interference.

[0013] Preferably, the additional permanent magnet is arranged on a side of the stroke sensor opposite the permanent magnet. This allows both magnets, i.e., the permanent magnet and the additional permanent magnet, to be arranged relatively close to the stroke sensor in the axial direction, allowing the use of smaller magnets to reliably detect the magnetic flux density with the stroke sensor.

[0014] In a preferred embodiment, the additional permanent magnet is arranged in alignment with the permanent magnet in the axial direction of the valve body. As a result, the magnetic flux density and the measurement signal of the stroke sensor are shifted exclusively parallel over the stroke of the valve body, resulting in a magnetic flux density in both directions over the travel path of the valve body. Alternatively, the additional permanent magnet can be arranged radially offset, i.e., transversely to the axial direction.

[0015] The stroke sensor is preferably arranged offset from the permanent magnet in the radial direction of the valve body. The relationship between the distance between the permanent magnet and the stroke sensor and the magnetic flux density is inversely proportional, with the decrease in magnetic flux density occurring exponentially with increasing stroke, i.e. with an increase in the distance between the stroke sensor and the permanent magnet. As a result, in the range of small strokes, i.e. for strokes in which the permanent magnet is relatively close to the stroke sensor, a change in the distance between the permanent magnet and the stroke sensor results in a large change in the magnetic flux density. In the range of large strokes, i.e. with a relatively large distance between the permanent magnet and the stroke sensor, the magnetic flux density changes only very slightly with an increase in the stroke.Due to the offset displacement of the stroke sensor in the radial direction, the curve representing the relationship between the stroke and the magnetic flux density flattens, causing the magnetic flux density to change evenly with the progressive stroke of the valve body and the permanent magnet. This improves stroke detection across the entire measuring range. Preferably, the additional permanent magnet and the stroke sensor are arranged on a circuit board. This allows for easy installation of the stroke sensor and the additional permanent magnet. The circuit board also allows the additional permanent magnet and the stroke sensor to be installed. This reduces the assembly effort for the stroke valve.

[0016] In a preferred embodiment, the drive unit is a spindle motor comprising a spindle nut and a spindle rod that interacts with the spindle nut. The valve body is firmly connected to the spindle rod, and the permanent magnet is arranged at an axial end of the spindle rod. The spindle motor has the advantage that the valve body can be adjusted reliably and with high precision.

[0017] Preferably, the spindle rod is manufactured in one piece with the valve body. This reduces manufacturing and assembly costs.

[0018] Preferably, a containment shell is provided, which has a base and a radially delimiting surface arranged between the radially outer stator and the radially inner rotor, with the base being arranged between the permanent magnet and the stroke sensor. The containment shell reliably shields the stator and thus the stator windings from fluids.

[0019] In a preferred embodiment, a magnetized cylindrical pin is arranged at the bottom of the containment shell. This cylindrical pin concentrates the field lines of the permanent magnet, so that a stronger magnetic field is available to the stroke sensor for generating the voltage signal, even at greater distances between the permanent magnet and the stroke sensor. The cylindrical pin is preferably arranged on a side of the containment shell bottom facing the valve body, with the rotor mounted on the magnetizable cylindrical pin, so that the cylindrical pin fulfills two functions: as an amplifier of the magnetic field and as a plain bearing for the rotating rotor. This allows for component savings and thus cost reduction.

[0020] In a preferred embodiment, the cylindrical pin is arranged axially between the permanent magnet and the stroke sensor. This ensures good focusing of the magnetic field lines, especially for smaller strokes.

[0021] Thus, a lift valve with a sensor device is created, wherein the lift sensor of the sensor device has an improved resolution and a reduced susceptibility to failure.

[0022] Two embodiments of a lift valve according to the invention for refrigeration or air conditioning circuits of a motor vehicle are shown in the figures and are described below.

[0023] Figure 1 shows a side view of a lift valve according to the invention in a sectional view.

[0024] Figure 2 shows a comparison of an embodiment known from the prior art with two different embodiments according to the invention.

[0025] The lift valve 10 shown in Figure 1 for a refrigerant or air conditioning circuit has a drive unit 12 in the form of a permanent-magnet synchronous motor 14 designed as a claw-pole motor. This permanent-magnet synchronous motor 14 consists of a radially outer stator 16 and a radially inner rotor 18, which carries several permanent magnets or has magnetized regions. An outer chamber 20, in which the stator 16 is arranged, is separated from an inner chamber 22, in which the rotor 18 is arranged, by a containment shell 24.

[0026] The containment shell 24 has an axially defining base 26, from which a cylindrical outer surface 28 extends axially. A stationary housing part 32 of a valve housing 34 projects into the containment shell 24 or into its cylindrical outer surface 28. A radial groove 38 is formed on a radially outer wall 36 of the housing part 32, in which groove a sealing ring 40 is arranged, which bears radially against the outer surface 28 of the containment shell 24. In addition, a shoulder 42 is formed on the radially outer defining wall 36, with which shoulder the housing part 32 bears against a collar 44 at the axial end of the containment shell 24, which bears with its opposite axial side against a shoulder 46 on a drive housing part 50. Accordingly, the stator 16 is separated from the rotor 18 in a fluid-tight manner by the containment shell 24.

[0027] The drive housing part 50 radially surrounds the stator 16 and the containment shell 24. On the side axially opposite the housing part 32, the drive housing part 50 projects beyond the stator 16 and forms a chamber 54 beyond the bottom 26 of the containment shell 24. This chamber is closed by a cover 56 and serves as a receptacle for an electronics unit 58, which is arranged axially opposite the bottom 26 of the containment shell 24.

[0028] The rotor 18 has a radially inner receiving opening 60 directed towards the open side of the containment shell 24, in which a spindle nut 62 is fastened, which has an internal thread which corresponds to an external thread of a spindle rod 64.

[0029] At the end of the spindle rod 64 remote from the bottom 26 of the containment shell, a valve body 66 is arranged on the spindle rod 64, which interacts with a valve seat 68 formed on the housing part 32 of the expansion valve 10 and onto which the valve body 66 is placed when the rotor 18 rotates or from which the valve body 66 is lifted off, so that a precise control of a free flow cross-section between the valve seat 68 and the valve body 66 takes place depending on the rotational position of the rotor 18. For this purpose, the spindle rod 64 is mounted via the valve body 66 in a plain bearing 69 so that it can be axially displaced, wherein axially extending webs 71 are formed on the valve body 66 outside the valve seat 68, which engage in grooves 73 in the plain bearing 69 and by means of which the spindle rod 64 is secured against rotation.Accordingly, the rotation of the rotor 18 and with it the spindle nut 62 is converted into a translational movement of the spindle rod 64 and the valve body 66.

[0030] The rotor 18 and the spindle nut 62 are supported on the one hand by a ball bearing 70 and on the other hand by a cylindrical pin 80 arranged on an axial end of the spindle nut 62 facing away from the valve seat 68 and acting as a plain bearing. The cylindrical pin 80 is arranged in a corresponding central opening 81 of the rotor 18 and is fixed, in particular welded, to the bottom 26 of the containment shell 24. The cylindrical pin 80 is made of a magnetizable material and is thus suitable for focusing magnetic field lines. This is done to improve the signal of a stroke sensor 83 of a sensor device 82, which is arranged on a circuit board 84 of the electronics unit 58 directly axially opposite the cylindrical pin 80 and interacts with a permanent magnet 86 arranged on the axial end of the spindle rod 64 opposite the valve body 66.

[0031] According to the invention, an additional permanent magnet 88 is arranged in the region of the stroke sensor 83, wherein the stroke sensor 83 detects a superposition of the magnetic field of the permanent magnet 86, which can be translationally displaced together with the valve body 66 and the spindle rod 64, and the magnetic field of the additional permanent magnet 88. The additional permanent magnet 88 is fastened to a side of the circuit board 84 facing away from the stroke sensor 83. In other words, the stroke sensor 83 is fastened to a first side of the circuit board 84 facing towards the rotor 18, and the additional permanent magnet 88 is fastened to a second side of the circuit board 84 facing away from the rotor 18. The additional permanent magnet 88 is oriented opposite to the permanent magnet 86. The permanent magnet 86 is arranged with its south pole on the spindle rod 64, and its north pole facing the stroke sensor 83. The additional permanent magnet 88 is arranged with the north pole on the circuit board 84 and the south pole faces the cover 56.Both magnets 86, 88 can also be rotated by 180°, whereby it is crucial that the two magnets 86, 88 are oriented opposite each other. The crucial point is that the north pole of the additional permanent magnet 88 faces the north pole of the permanent magnet 86, or the south pole of the additional permanent magnet 88 faces the south pole of the permanent magnet 86.

[0032] Alternatively, the additional permanent magnet 88 could also be aligned such that the north pole of the additional permanent magnet 88 faces the south pole of the permanent magnet 86 or the south pole of the additional permanent magnet 88 faces the north pole of the permanent magnet 86, wherein with such an alignment the resulting magnetic field detectable by the stroke sensor can also be changed such that the measuring range of a stroke sensor used can be utilized in the best possible way.

[0033] Figure 2a shows an embodiment known from the prior art with a sensor device 82, consisting of the stroke sensor 83 and the permanent magnet 86 fastened to the spindle rod 64. Figure 2a also shows a first diagram with a plotted profile of the magnetic flux density in relation to the stroke of the spindle rod 64 and the valve body 66, as well as a second diagram representing the output signal of the stroke sensor 83. In the first diagram in Figure 2a, the detected magnetic flux density runs exclusively through the positive range, with the magnetic flux density decreasing exponentially with an increase in the stroke of the spindle rod 64, i.e. with an increase in the distance between the permanent magnet 86 and the stroke sensor 83, so that the magnetic flux density changes greatly in the range of small strokes and changes only slightly in the range of large strokes.The corresponding output signal of stroke sensor 83, shown in the second diagram, runs exclusively in the upper range, while in the lower range the magnetic flux density would be displayed in the opposite direction. The crucial point is that the entire measuring range of stroke sensor 83 is not utilized, thus reducing the resolution of stroke sensor 83 and thus the accuracy of detecting the magnetic flux density.

[0034] Figure 2b shows a first embodiment of the lift valve 10 with an additional permanent magnet 88 according to the invention, which is arranged on the circuit board 84. During operation of the lift valve 10, the stroke sensor 83 continuously detects the magnetic field or the magnetic flux density of the additional permanent magnet 88, whereby the detected magnetic flux density of the additional permanent magnet 88 remains constant. The magnetic flux density of the permanent magnet 86 detected by the stroke sensor 83 varies depending on the stroke of the spindle rod 64. The stroke sensor 83 thus detects a superposition of the magnetic flux density of the additional permanent magnet 88 and the magnetic flux density of the permanent magnet 86. The provision of the additional permanent magnet 88 results in the course of the magnetic flux density detected by the stroke sensor 83 being shifted parallel to the curve shown in Figure 2a.As a result, the magnetic flux density detected by the stroke sensor 83 initially passes through the positive range, i.e., in a first direction, and then through the negative range, i.e., in a second direction opposite to the first direction. The output signal of the stroke sensor passes through the upper and lower ranges, utilizing the entire measuring range of the stroke sensor 83 and thereby increasing the resolution of the stroke sensor 83.

[0035] Figure 2c shows a second embodiment of the lift valve 10 with the additional permanent magnet 88 according to the invention, wherein the lift sensor 83 is no longer arranged in alignment with the permanent magnet 86 and the additional permanent magnet 88, but is arranged off-center, i.e., displaced in the radial direction, on the circuit board 84. The profile of the detectable magnetic flux density remains virtually unchanged in the region of the large lifts, while the detectable magnetic flux density flattens out in the region of the small lifts. This results in a substantially uniform profile of the magnetic flux density to be detected and the output signal of the lift sensor 83.

[0036] In the two embodiments according to the invention, the signal amplification of the stroke sensor 83 is increased compared to the embodiment known from the prior art.

[0037] Accordingly, a lift valve for a refrigeration or air conditioning circuit of a motor vehicle is provided, wherein the lift sensor 83 has an improved resolution and a reduced susceptibility to failure.

[0038] It should be clear that the scope of the main claim is not limited to the described embodiment, but various modifications are possible. For example, the drive unit 12 or the sensor device 82 may be designed differently.

Claims

PATENT CLAIMS A lift valve for a refrigeration or air conditioning circuit of a motor vehicle, comprising a drive unit (12), a valve body (66) which is operatively connected to the drive unit (12) and which, when the drive unit (12) is actuated, is translationally adjustable between different positions, a valve seat (68) which, together with the valve body (66), defines a flow cross-section, and a sensor device (82) which has a lift sensor (83), wherein the lift sensor (83) interacts with a permanent magnet (86) which, together with the valve body (66), is translationally displaceable by the drive unit (12), characterized in that an additional permanent magnet (88) is rigidly arranged in the area of ​​the lift sensor (83), such thatthat the stroke sensor (83) detects a superposition of the magnetic field of the permanent magnet (86), which is translationally displaceable together with the valve body (66), and the magnetic field of the additional permanent magnet (88). Stroke valve according to claim 1, characterized in that the additional permanent magnet (88) is arranged rotated by 180° relative to the permanent magnet (86) such that the north pole of the additional permanent magnet (88) faces the north pole of the permanent magnet (86) or the south pole of the additional permanent magnet (88) faces the south pole of the permanent magnet (86). Stroke valve according to claim 1 or 2, characterized in that, The additional permanent magnet (88) is arranged on a side of the stroke sensor (83) opposite the permanent magnet (86). A stroke valve according to one of the preceding claims, characterized in that the additional permanent magnet (88) is arranged in the axial direction of the valve body (66) aligned with the permanent magnet (86). A stroke valve according to one of the preceding claims, characterized in that the stroke sensor (83) is arranged offset in the radial direction of the valve body (66) from the permanent magnet (86). A stroke valve according to one of the preceding claims, characterized in that the additional permanent magnet (88) and the stroke sensor (83) are arranged on a circuit board (84).A lift valve according to any one of the preceding claims, characterized in that the drive unit (12) is a spindle motor comprising a spindle nut (62) and a spindle rod (64) cooperating with the spindle nut (62), wherein the valve body (66) is rigidly connected to the spindle rod (62), and wherein the permanent magnet (86) is arranged at an axial end of the spindle rod (62). A lift valve according to claim 7, characterized in that the spindle rod (62) is integrally formed with the valve body (66). A lift valve according to any one of the preceding claims. characterized in that a containment cup (24) is provided, which has a base (26) and a radially bounding outer surface (28) arranged between the radially outer stator (16) and the radially inner rotor (18), wherein the base (26) is arranged between the permanent magnet (86) and the stroke sensor (83). Stroke valve according to claim 9, characterized in that a magnetized cylindrical pin (80) is arranged on the base (26) of the containment cup (24). Stroke valve according to claim 10, characterized in that the cylindrical pin (80) is arranged on a side of the base (26) of the containment cup (24) facing the valve body (66), wherein the rotor (18) is mounted on the magnetizable cylindrical pin (80). Stroke valve according to claim 10 or 11, characterized in that the cylindrical pin (80) is arranged axially between the permanent magnet (86) and the stroke sensor (83).