Expansion valve

Abstract

Expansion valve (1) operable with a stepper motor, comprising: a housing (4); a hollow shaft (7) which is arranged in the housing (4); a valve base body (5) carrying the hollow shaft (7) which closes the housing (4); a rotor (6) which can be driven by means of a stator; a central spindle (8) which is arranged within the hollow shaft (7) and can be driven by the rotor (6) in such a way that a rotational movement of the spindle (8) can be converted via a threaded connection (9) into an axial movement for opening and closing the expansion valve (1); an adapter element (13) which is arranged between the rotor (6) and the spindle (8) for transmitting a torque from the rotor (6) to the spindle (8); and a spiral body (12) which is arranged on a lateral surface (10) of the hollow shaft (7) and can be set into a rotary movement by means of the adapter element (13), wherein the spiral body (12) has an axially extending first stop element (14) which is arranged in a decentralized opening (13c) of the adapter element (13).

Description

[0001] The invention relates to an expansion valve.

[0002] Expansion valves, also called throttle valves, are generally devices that reduce the pressure of a flowing fluid by locally constricting a flow cross-section, thereby causing an increase in volume or expansion. Expansion valves typically have a mechanism that converts a rotational movement into an axial movement to open and close the expansion valve. The axial movement required to open and close the expansion valve requires a limitation or the definition of two end points using a stopper structure.

[0003] Such expansion valves are well known in the prior art. For example, a known expansion valve is disclosed in WO 2020 / 083 065 A1 and comprises a rotor, a connecting base fixedly connected to the rotor, and a threaded rod whose first end penetrates and protrudes from the connecting base. A fixed cap of the expansion valve is fixedly connected to the first end of the threaded rod, and a rotation-stopping relationship exists between the fixed cap and the connecting base. In particular, the fixed cap is arranged such that a fixed connection relationship exists between the connecting base and the threaded rod by means of the cap.

[0004] JP 2014-142057 A relates to another known expansion valve with a stopper mechanism, which includes a spool element and a guide rail integrally formed with an outer peripheral surface of a holder member. Near a lower end portion and an upper end portion of the guide rail, a lower stopper surface and an upper stopper surface are provided on the outer peripheral surface of the holder member, with which one end or the other end of a spool part of the spool element screwed to the guide rail collides. An edge is provided on the inner peripheral surface of the magnet rotor, against which a pawl of the spool element abuts to regulate the rotation of the magnet rotor in one rotational direction when the spool element is rotated and one end or the other end of the spool part collides with the lower stopper surface or the upper stopper surface, and the rotation is regulated.

[0005] From CN 1 02 252 120 A, another electrically operated valve is known which has a sleeve and a valve base. A nut is arranged in the sleeve and a spring guide rail is arranged outside the nut. The spring guide rail is provided with an upper stop part and a lower stop part. The lower end of the sleeve is connected to the upper end of the valve base and the peripheral side wall of the upper end of the sleeve is provided with a protruding part. At least the underside of the protruding part and / or the upper side of the corresponding valve base is provided with a recessed part, and accordingly the upper stop part or the lower stop part is arranged in the recessed part.

[0006] For example, JP 3 328 530 B2 discloses a stopper structure for a motorized valve. In this valve, the degree of opening of a valve seat in a valve main body is controlled by rotating a rotor of a motor by electrifying a stator of the motor. The stator is attached to an outer periphery of a housing. The rotation of the rotor is converted into linear motion by a screw action of an inner screw and an outer screw.

[0007] The stopper structure, which is designed to determine the two end points when opening and closing the expansion valve, includes a stopper, an engaging part and an annular guide pin.

[0008] The stopper is arranged vertically at a position away from the center on a back side of a cover at an upper end portion of the housing.

[0009] The engagement member includes a long, narrow shaft extending on an opposite side of a valve stem integrally formed with the rotor. The shaft is inserted into a guide path having a helical center portion and protruding portions at the upper and lower ends, with the upper protruding portion being attached to an upper end portion of the shaft and the lower protruding portion being bent upward.

[0010] The stopper structure further includes an annular guide pin having a ring portion that is rotated approximately once around the helical center portion and an arm that extends in the outer circumferential direction below the ring portion so as to be able to make contact with the stopper disposed in a helical groove of the guide path.

[0011] At this time, an upper end portion of the annular portion of the guide pin contacts the protruding portion of the guide path when the annular guide pin moves along the helical groove of the guide path. Furthermore, the arm of the guide pin contacts the engaging part formed on the lower protruding portion when the guide pin moves downward along the helical groove of the guide path.

[0012] Overall, the structure of the expansion valve known from the state of the art, as described above, is extremely complex. However, this complexity is not an isolated problem. Rather, all expansion valves known from the state of the art have the disadvantage of requiring a complicated and complex structure to fulfill their function. This complex structure inevitably also makes it impossible to simply replace the expansion valve or its parts.

[0013] Furthermore, conventional expansion valves also have the problem that they are subject to significant wear. This means that conventional expansion valves have to be replaced relatively frequently, often completely.

[0014] In addition to a simpler design that allows for easier replacement of both the entire expansion valve and parts thereof, an expansion valve that is subject to less wear would also be desirable.

[0015] Another disadvantage of known expansion valves is that they are complex to manufacture.

[0016] The invention is therefore based on the object of providing an expansion valve that eliminates the above-mentioned problems and disadvantages of the prior art. In particular, the object of the present invention is to provide an expansion valve that is both low-wear and compact. Furthermore, the object of the present invention is to provide an expansion valve that is particularly easy to replace. A further object of the present invention is to provide a valve that enables pressure equalization between different spaces within the valve despite a low-wear, compact design and easy replaceability.

[0017] Furthermore, a further aspect is based on the object of specifying a method for producing an expansion valve which is less complex than the methods known from the prior art.

[0018] The object underlying the invention is achieved by an expansion valve according to the subject matter of independent claim 1. Advantageous further developments are specified in the dependent claims.

[0019] According to one aspect, the solution consists in specifying an expansion valve operable with a stepper motor, comprising the following: a housing; a hollow shaft arranged in the housing; a valve base body carrying the hollow shaft, which closes the housing; a rotor which can be driven by means of a stator; a central spindle which is arranged within the hollow shaft and can be driven by the rotor in such a way that a rotational movement of the spindle can be converted via a threaded connection into an axial movement for opening and closing the expansion valve;and a spiral body having a thread, which is arranged on a lateral surface of the hollow shaft and can be driven by means of the rotor, wherein a stop body is arranged on the hollow shaft, which is arranged to be movable in the thread of the spiral body and, as part of a spindle stopper structure, specifies an upper end position and a lower end position of the central spindle;

[0020] The central spindle is designed in particular as a threaded spindle, which together with other elements (here an internal thread of the hollow shaft) serves to convert a rotational movement of the rotor into a translational movement.

[0021] For this purpose, the central spindle is connected to the rotor. The spiral body is a separate element and not part of the hollow shaft. The spiral body is also connected to the rotor in such a way that the rotor can drive it.

[0022] The stop body is arranged, in particular, on the outer surface of the hollow shaft and preferably abuts a first (upper) stop element when the central spindle is in its lower end position, and a second (lower) stop element when the central spindle is in its upper end position. The stop body can, for example, be a rod-shaped element. Whether the upper or lower end position of the spindle is determined depends on the pitch of the spiral body and the pitch of the spindle.

[0023] Because the spiral body having the thread can be driven (separately) by means of the rotor and the stop body is arranged in such a way that it can be moved in this thread, a particularly compact design of the expansion valve is possible.

[0024] According to an advantageous further development, the hollow shaft has a longitudinal groove on the outer surface, wherein the stop body is designed as a sliding ring which is secured against rotation in the thread of the spiral body by means of the longitudinal groove and is arranged to be movable in the axial direction.

[0025] Depending on the direction of rotation, the sliding ring is moved axially up or down along the hollow shaft (within the longitudinal groove).

[0026] Because the sliding ring can move up and down within the longitudinal groove, the overall size of the expansion valve can be reduced, allowing it to be designed even more compactly. In particular, the longitudinal groove and sliding ring offer a simple design with high functional reliability.

[0027] Furthermore, by securing the sliding ring in the longitudinal groove, the assembly of the spiral body and sliding ring is also secured to the outer surface of the hollow shaft. Thus, the guide groove, together with the sliding ring, also acts as a loss protection.

[0028] According to an advantageous further development, the spindle stopper structure is formed by the interaction of the spiral body and the sliding ring.

[0029] According to an advantageous further development, the sliding ring has a radially inwardly extending extension which is designed to run in the longitudinal groove and to act there as an anti-twist device.

[0030] This radially inwardly extending extension offers a simple way to secure the sliding ring against twisting so that it can be reliably moved axially in the longitudinal groove.

[0031] According to an advantageous further development, the spiral body has a first stop element extending in the axial direction of the spiral body and a second stop element extending in the axial direction of the spiral body.

[0032] The axial direction of the spiral body is understood to be the direction extending along the axis around which the spiral body is wound. In the installed state, this axis is aligned at least substantially concentrically with the rotational axis of the hollow shaft and the rotational axis of the spindle. In particular, the first stop element extends in a direction opposite to the extension direction of the second spiral body. However, both directions are axial directions of the spiral body.

[0033] According to an advantageous further development, the lower end position of the spindle is fixed upon contact of the first stop element with the stop body, wherein the upper end position of the spindle is fixed upon contact of the second stop element with the stop body plus the maximum angle of rotation of the spiral body.

[0034] If the spiral body is a rigid or non-torsionally flexible body, the maximum angle of rotation of the spiral body is zero, so that the upper end position of the spindle is fixed when the second stop element comes into contact with the stop body.

[0035] However, if the spiral body is designed to be torsionally elastic, the spindle can still move as far as the elasticity of the spiral body allows, even after the second stop element comes into contact with the stop body. Upon contact of the second stop element with the stop body, the upward movement of the spindle is thus dampened.

[0036] Alternatively, the upper end position of the central spindle can also be fixed upon contact of the first stop element with the stop body, whereby the lower end position of the spindle is fixed upon contact of the second stop element with the stop body plus, if applicable, the maximum angle of rotation of the spiral body.

[0037] Whether the upper or lower end position of the central spindle is determined depends on the pitch of the spiral body and the pitch of the central spindle. This is particularly dependent on whether the thread is right-handed or left-handed. Only if the thread pitch of the central spindle is different from that of the spiral body does the first stop element also determine the upper spindle position. If the central spindle and the spiral body have the same pitch direction, the travel path of the central spindle and the slide ring is opposite. Accordingly, the first stop element also determines the lower spindle position.

[0038] According to an advantageous development, the sliding ring is designed as a cylindrical spiral and has an upper end and a lower end opposite the upper end, wherein the upper end comes into contact with the first stop element, and wherein the lower end comes into contact with the second stop element.

[0039] Because the sliding ring is designed as a cylindrical spiral, it is particularly well held within the spiral body. Furthermore, it is possible to design the sliding ring, i.e., the cylindrical spiral, so that the upper and lower ends overlap. This means that the cylindrical spiral is formed over an angular range greater than 360 degrees, with the overlap being the angular range that extends beyond 360 degrees. This overlap of the ends and the number of turns of the spiral body can be used to specify and / or limit the maximum number of possible revolutions.

[0040] According to an advantageous development, the spiral body is connected to an adapter element by means of the first stop element in order to be rotated during the rotation of the rotor, wherein the adapter element connects the rotor to the spindle in order to rotate the spindle during the rotation of the rotor.

[0041] The adapter element is connected to the spindle in a force-locking manner, for example, by a press connection, a weld connection, or a form-fitting connection. The adapter element can, for example, be connected to the rotor in a form-locking manner. For this purpose, the adapter element is not rotationally symmetrical when viewed in cross-section. For example, the outer shape of the adapter element, viewed in cross-section (i.e., viewed along the rotation axis R), can be triangular, square, or generally polygonal, for example, even toothed. Naturally, the inner shape of the rotor, viewed in cross-section, is then complementary to the shape of the adapter element.

[0042] This means that the first stop element of the spiral body fulfils a dual function and, in addition to its function as a stop element, also serves as a driver element (i.e. connecting element) to the rotor or adapter.

[0043] Because the rotation of the rotor is not transmitted directly but indirectly via the adapter, it is also possible, for example, to produce different expansion valves (with, for example, different rotors) with as many identical parts as possible.

[0044] According to an advantageous further development, the spiral body is a torsion spring which is designed in the form of a helical spring made of steel.

[0045] The steel is in particular a steel that has sufficient elasticity to form it into a spiral body.

[0046] This makes the production of the spiral body particularly cost-effective.

[0047] According to an advantageous development of the invention, the hollow shaft is made of a plastic, preferably of polyphenylene sulfide (PPS), or polyetheretherketone (PEEK), or of brass or bronze.

[0048] The use of plastic in the expansion valve saves weight compared to a metal material. Furthermore, PPS and PEEK are high-performance materials, allowing them to be used continuously in a high temperature range (up to 240 degrees Celsius) and even briefly at temperatures up to 300°C. Consequently, the expansion valve can be used even under extreme conditions without fear of valve failure.

[0049] According to an advantageous development, the expansion valve further comprises a sleeve element which has a receiving region and a valve needle, wherein a stamp-like end region of the central spindle, a compression spring and a force transmission element are completely received in the receiving region.

[0050] Because the expansion valve is designed with such a sleeve element, which fulfills the function of the valve needle on the one hand and provides a receiving area on the other, a particularly compact design of the expansion valve can be achieved. Despite the compact design, all of the expansion valve's functions can be reliably fulfilled.

[0051] According to an advantageous further development, the force transmission element is designed and arranged such that, through contact with the central spindle, it transmits axial forces from the central spindle via the compression spring to the sleeve element, wherein the force transmission element, viewed in cross section, is mushroom-shaped such that torques are not transmitted or are transmitted only to a limited extent from the central spindle to the force transmission element.

[0052] Because the force transmission element is mushroom-shaped, the contact point, i.e., the force transmission point, with the central spindle is small. At this point, torque is transmitted to the force transmission element only to a limited extent (via friction). Overall, this also results in a particularly low-wear expansion valve.

[0053] According to an advantageous development, the housing and a side of the valve base body facing the housing delimit a housing interior, wherein a hollow shaft interior is formed within the hollow shaft, wherein a fluid inlet chamber is arranged adjacent to a side of the valve base body facing away from the housing when the expansion valve is installed in a valve installation chamber, wherein a first pressure equalization channel is arranged for pressure equalization between the fluid inlet chamber and the housing interior, wherein the first pressure equalization channel has a first channel region and a second channel region, and wherein the second channel region is formed by the longitudinal groove.

[0054] This also allows for a particularly compact expansion valve design. In particular, components can be saved by assigning a second function to existing components.

[0055] The longitudinal groove not only guides the sliding ring, but also acts as a pressure equalization channel. The longitudinal groove thus fulfills a dual function, as it guides the sliding ring and also forms part of the second pressure equalization channel.

[0056] According to an advantageous further development, a second pressure equalization channel for pressure equalization between the hollow shaft interior and the housing interior is arranged in a region of maximum radial extension of the longitudinal groove and the hollow shaft interior.

[0057] This also enables a safe pressure equalization between the hollow shaft interior and the housing interior.

[0058] A solution according to the invention consists in specifying an expansion valve that can be operated with a stepper motor, which has the following: a housing; a hollow shaft that is arranged in the housing; a valve base body that carries the hollow shaft and closes the housing; a rotor that can be driven by means of a stator; a central spindle that is arranged within the hollow shaft and can be driven by the rotor in such a way that a rotational movement of the spindle can be converted via a threaded connection into an axial movement for opening and closing the expansion valve; an adapter element that is arranged between the rotor and the spindle for transmitting a torque from the rotor to the spindle;and a spiral body which is arranged on a shell side of the hollow shaft and can be set into a rotary movement by means of the adapter element, wherein the spiral body has an axially extending first stop element which is arranged in a decentralized opening of the adapter element;

[0059] Because the adapter element is located between the spindle and the rotor, the expansion valve's overall design is more versatile. This means, for example, that different rotors can be used. The adapter also performs a second function, as it drives the spiral body, i.e., sets it in rotation.

[0060] The adapter element has a central axis of rotation R, wherein the decentralized opening is defined such that it is formed decentrally from this central axis of rotation R.

[0061] According to an advantageous development of the invention, the adapter element has a plate-shaped base region and a receiving region for the central spindle extending axially centrally from the plate-shaped base region.

[0062] The axially extending receiving area has the advantage that the bore tolerance can be extended, since a long guide leads to less possible tilting of the components relative to one another.

[0063] The connection between the spindle and the adapter element is made, for example, after alignment on the top side of the spindle. The connection can be made by laser welding, preferably with several spot welds.

[0064] Since only the base area is plate-shaped, weight can also be saved compared to an adapter element that is completely plate-shaped.

[0065] According to an advantageous development of the invention, a central through-opening along a rotation axis R of the adapter element is designed to receive an upper region of the spindle.

[0066] The central through-opening thus extends along the rotational axis R of the adapter element. Viewed in cross-section, the central through-opening is preferably circular to enable particularly easy alignment of the spindle-stop structure or the upper stop.

[0067] However, the central through-hole does not have to be circular. Rather, the central through-hole could be non-rotationally symmetrical when viewed in cross-section. For example, the through-hole can be triangular, square, or generally polygonal, for example, even toothed, when viewed in cross-section (i.e., along the rotational axis R).

[0068] This would then enable particularly simple force transmission from the adapter element to the spindle, or more precisely, to the upper section of the spindle. Naturally, the upper section of the spindle, viewed in cross-section, is designed to complement the shape of the central through-hole.

[0069] According to an advantageous development of the invention, the outer shape of the adapter element is not rotationally symmetrical with respect to the rotation axis R.

[0070] According to an advantageous development of the invention, the decentralized opening is arranged in the plate-shaped base region, wherein the plate-shaped base region preferably has further decentralized openings.

[0071] Because the decentralized opening is located in the plate-shaped base area of ​​the adapter element, it can be positioned particularly far from the center (i.e., the rotational axis) of the adapter element. A greater distance between the decentralized opening and the rotational axis R enables better force transmission (lever arm).

[0072] By arranging additional decentralized openings, additional functions can be integrated into the adapter element.

[0073] According to an advantageous development of the invention, the decentralized openings are designed as elongated holes.

[0074] Slotted holes have the advantage that they are easier to manufacture, as they can be inserted from the side (i.e. at right angles to the axis of rotation) into the adapter element or into the plate-shaped base area of ​​the adapter element.

[0075] According to an advantageous development of the invention, at least one of the further decentralized openings is arranged such that it compensates for a pressure in the housing interior above the adapter element and below the adapter element.

[0076] The adapter element also fulfills a pressure equalization function. Since (once again) a component is designed to perform multiple functions, the total number of components can be (further) reduced.

[0077] According to an advantageous development of the invention, the spiral body has a thread, wherein the hollow shaft has a longitudinal groove on the outer surface, and wherein a sliding ring is arranged in the thread of the spiral body by means of the longitudinal groove so as to be secured against rotation and movable in the axial direction.

[0078] Because the sliding ring can move up and down within the longitudinal groove, the overall size of the expansion valve can be reduced, allowing for a more compact design. The longitudinal groove and sliding ring also offer a simple design with high functional reliability.

[0079] Because the sliding ring is secured in the longitudinal groove, the assembly of the spiral body and sliding ring is also secured to the outer surface of the hollow shaft. Thus, the guide groove, together with the sliding ring, also acts as a loss protection.

[0080] According to an advantageous development of the invention, a spindle stopper structure is formed by interactions of the spiral body and the sliding ring, which structure specifies an upper end position and a lower end position of the central spindle.

[0081] According to an advantageous development of the invention, the spiral body has a second stop element extending in the axial direction opposite to the first stop element.

[0082] According to an advantageous development of the invention, the sliding ring is designed as a cylindrical spiral and has an upper end and a lower end.

[0083] If the sliding ring is designed as a cylindrical spiral, it can be held particularly securely within the spiral body. Furthermore, it is possible to design the sliding ring, i.e., the cylindrical spiral, so that its upper and lower ends overlap. The cylindrical spiral is thus formed beyond a full circle (more than 360 degrees). The overlap is the area that extends beyond the full circle. Through this overlap of the ends and the number of turns of the spiral body, the maximum number of possible revolutions can be specified and / or limited.

[0084] According to an advantageous development of the invention, a radially inwardly extending extension is formed at one of the two ends.

[0085] This radially inwardly extending extension offers a simple way to secure the sliding ring against twisting so that it can be reliably moved axially in the longitudinal groove.

[0086] According to an advantageous development of the invention, the radially inwardly extending extension of the sliding ring is designed to run in the longitudinal groove of the hollow shaft and to act there as an anti-twist device.

[0087] According to an advantageous development of the invention, the lower end position of the spindle is fixed upon contact of the first stop element with the upper end and the upper end position of the spindle is fixed upon contact of the second stop element with the lower end plus the maximum angle of rotation of the spiral body.

[0088] If the spiral body is a body that cannot be preloaded in the direction of rotation (i.e., rigid and not torsionally flexible), the maximum angle of rotation of the spiral body is zero. Then, the upper end position of the spindle is determined when the second stop element contacts the stop body. However, if the spiral body is torsionally flexible (i.e., preloadable in the direction of rotation), the spindle can still move even after the second stop element contacts the stop body (because it preloads the spiral body).

[0089] This means that when the second stop element comes into contact with the stop body, the rotation of the spindle upwards is dampened (and then stops when the maximum preload is reached).

[0090] Alternatively, the upper end position of the spindle can also be fixed upon contact of the first stop element with the stop body, whereby the lower end position of the spindle is fixed upon contact of the second stop element with the stop body plus the maximum angle of rotation of the spiral body.

[0091] Whether the upper or lower end position of the spindle is determined depends on the pitch of the spiral body. This is particularly dependent on whether the thread is clockwise or counterclockwise. Only if the thread pitch of the spindle is different from that of the spiral body does the first stop element also determine the upper spindle position. If the spindle and spiral body have the same pitch direction, the travel of the spindle and the slide ring is opposite. Accordingly, the first stop element also determines the lower spindle position.

[0092] According to an advantageous development of the invention, the spiral body is a torsion spring which is designed in the form of a helical spring made of steel.

[0093] This makes the spiral body extremely easy (and inexpensive) to manufacture.

[0094] The solution further consists in specifying an expansion valve operable with a stepper motor, comprising the following: a housing; a hollow shaft arranged in the housing; a valve base body carrying the hollow shaft, which closes the housing; a rotor which can be driven by means of a stator; a central spindle which is arranged within the hollow shaft and can be driven by the rotor in such a way that a rotational movement of the spindle can be converted via a threaded connection into an axial movement for opening and closing the expansion valve;and a sleeve element having a receiving area in which the central spindle, a compression spring and a force transmission element are at least partially received, and a valve needle, wherein the receiving area of ​​the sleeve element is closed by means of a bushing, wherein the spindle is made of a first material and the bushing is made at least partially of a second material different from the first material, wherein the second material has a lower hardness than the first material;

[0095] Since the sleeve element has a valve needle and a receiving area, i.e., the valve needle body is sleeve-shaped, a particularly compact design of the expansion valve can be achieved. More precisely, this is due in particular to the fact that the elements required for force transmission to the valve needle can be arranged in the receiving area in a space-saving manner.

[0096] During operation, there are components that perform a rotational movement and those that do not. In particular, the spindle performs a rotational movement, whereas the sleeve element, if possible, does not perform any rotation. Contact between rotating elements and non-rotating elements causes wear on the elements.

[0097] In the expansion valve, this problem is solved by a selected tribological pairing between contacting and relatively moving elements. This allows wear to be controlled so that it primarily occurs on one of the components involved. Additionally, this component can optionally be designed as an easily replaceable wear part.

[0098] This allows the bushing that seals the sleeve element to be an easily replaceable wear part. If the bushing becomes worn, it can simply be replaced, eliminating the need to replace the entire sleeve element, including the valve needle. This significantly reduces maintenance costs.

[0099] The tribological pairing is selected so that the bushing is made of a softer material, i.e., a material with a lower hardness, than the first material. Thus, wear occurs primarily at the bushing. Although it may be possible to replace the bushing, the bushing is advantageously dimensioned to allow wear for the service life of the valve.

[0100] Overall, the expansion valve offers a compact design that ensures targeted and controlled wear. The wear parts themselves are easy to replace.

[0101] The bushing is in particular pressed into the sleeve element, i.e. connected by means of a press fit.

[0102] A bushing, as defined in the present application, is understood to be an annular or hollow-cylindrical element. However, the sleeve element is advantageously a hollow-cylindrical element, which is characterized by extending further in the axial direction (rotational axis) than the annular element. Accordingly, a hollow-cylindrical wear element offers more wearable material than an annular wear element.

[0103] According to an advantageous further development, the first and second materials are metals or metal alloys.

[0104] According to an advantageous development, the second material is a copper alloy, preferably brass, and the first material is a steel, in particular a stainless steel.

[0105] The second material is particularly preferably a sintered material.

[0106] For example, the material can be sintered bronze. Sintered materials are understood to be those that have a large number of pores that can be filled with lubricants. For example, 10 to 40 percent by volume, preferably 15 to 30 percent by volume, of the bushing can then be made up of pores.

[0107] In particular, the combination of stainless steel and brass can achieve a particularly good balance between wear and cost. On the one hand, the second material must not be too soft to prevent wear too quickly, and on the other hand, it must not be too hard to prevent damage to the element made of the first material.

[0108] Particularly preferably, the force transmission element is also made of the first material (e.g., stainless steel). Furthermore, the sleeve element is also preferably made of the first material (i.e., stainless steel).

[0109] According to an advantageous development, the force transmission element has a head region and a shaft region, wherein the force transmission element is arranged such that contact for transmitting axial forces from the central spindle takes place at a point in a central region of the head region.

[0110] This point-based transmission keeps the contact area (for transmitting torque) between the spindle and the power transmission element as small as possible. Due to the small, i.e., small, contact area, the spindle slips during rotation, preventing the power transmission element from rotating. On the other hand, axial forces can also be reliably transmitted from the spindle to the power transmission element via point-based contact.

[0111] This means that a torque interruption occurs at the contact surface between the power transmission element and the central spindle. This torque acts on the rotor, driven by the stator, and is transferred, for example, force-locked (via the adapter) to the spindle. The spindle's threaded connection translates the rotational movement into an axial movement of the spindle. Only this axial movement is desired at the valve needle; a rotational movement of the valve needle is not desired there.

[0112] According to an advantageous further development, the compression spring is arranged in regions on a lateral surface of the shaft region of the force transmission element.

[0113] Because the compression spring is arranged on the outer surface of the shaft portion, it is guided from the inside by the shaft portion. On the other hand, it is guided from the outside by the inner surface of the receiving portion of the sleeve element. This means that the compression spring is securely guided between the shaft portion of the force transmission element and the receiving portion of the sleeve element.

[0114] The compression spring doesn't necessarily have to touch the two elements. Rather, it's also conceivable that there's clearance between the outer surface of the shaft area and the compression spring, as well as between the compression spring and the inner surface of the receiving area. However, the compression spring is guided sufficiently to prevent tilting during compression.

[0115] According to an advantageous further development, the compression spring is a cylindrical spiral spring.

[0116] This makes the compression spring particularly inexpensive to manufacture and allows it to be securely positioned around the outer surface of the shaft area.

[0117] According to an advantageous further development, an axial length of the shaft region is designed to be so long that when an axial force is exceeded, which leads to a compression of the compression spring by a predefined spring travel, the shaft region comes into contact with a sleeve bottom of the sleeve element.

[0118] This means that when the compression spring is compressed by the predefined spring travel, an axial force can be transmitted directly from the force transmission element to the sleeve base. This allows for maximum stroke limitation in the event of failure of the mechanical stop, i.e., the spindle-stop structure, or if the valve is overloaded.

[0119] Thus, the force transmission element also fulfills several functions. First, the force transmission element enables torque decoupling of the sleeve element from the spindle. Furthermore, the force transmission element, or its shaft area, guides the compression spring in axial directions, thus preventing buckling or generally asymmetrical deformation of the compression spring. Furthermore, the shaft area ensures the maximum stroke limitation described above.

[0120] According to an advantageous further development, the spindle has a stamp-like end region which is designed and arranged such that it comes into contact with the force transmission element for transmitting axial forces, wherein an upper region of the stamp-like end region comes into frictional contact with the bushing.

[0121] This means that a lower area (more precisely, a bottom side) of the plunger-like end section comes into contact with the force-transmitting element, and an upper area of ​​the plunger-like end section comes into frictional contact with the bushing. The plunger-like end section is thus arranged between the bushing and the force-transmitting element.

[0122] According to an advantageous further development, the receiving area is designed such that it completely accommodates the bushing, the stamp-like end area, the compression spring and the force transmission element.

[0123] The compression spring is located at the bottom of the receiving area, i.e., directly above the sleeve base. The force transmission element is located above the compression spring, and the plunger-like end portion of the spindle is located above the plunger-like end portion. The bushing, in turn, is located above the plunger-like end portion, closing off the entire receiving area.

[0124] This results in a particularly compact design of the expansion valve.

[0125] According to an advantageous further development, the expansion valve has a valve seat, wherein the valve base body is a one-piece body which accommodates the valve seat, the sleeve element and the hollow shaft at least in regions.

[0126] The valve base body is thus designed as a type of replaceable valve cartridge. Since only the valve base body needs to be removed from the valve installation space, valve replacement is simplified. Furthermore, compactness is increased because a variety of functions are integrated into the valve base body.

[0127] Furthermore, such a one-piece valve base body offers the possibility of integrating the valve into a customer-specific installation space by adapting only one component (valve base body exterior). This can save costs, as identical parts can be used for different expansion valves. Furthermore, the variety of parts is reduced, thus resulting in further cost savings. The complexity of assembling the expansion valve is also reduced.

[0128] According to an advantageous development, the valve base body has a valve seat receiving area in a lower area and a receiving area in an upper area, which is designed to receive the hollow shaft and the sleeve element.

[0129] The valve base body thus has receiving areas that make it possible to integrate elements of the expansion valve into the valve base body as easily as possible.

[0130] According to an advantageous further development, the sleeve element is arranged in the receiving area at least partially within the hollow shaft.

[0131] The mounting area also reduces the installation space in the axial direction of the expansion valve.

[0132] According to an advantageous further development, the force transmission element is designed such that it absorbs no or only limited torque from the spindle.

[0133] This limitation occurs at the point-like contact surface between the force transmission element and the central spindle.

[0134] According to an advantageous development, the expansion valve has a spindle stopper structure which limits the rotational movement of the spindle between an upper end position and a lower end position.

[0135] According to an advantageous further development, the spindle stopper structure is formed by the interaction of a spiral body and a stop body.

[0136] The solution further consists in specifying an expansion valve operable with a stepper motor, comprising: a housing; a hollow shaft arranged on the housing; a valve base body carrying the hollow shaft and closing the housing; a rotor drivable by means of a stator; a central spindle arranged within the hollow shaft and drivable by the rotor such that a rotational movement of the spindle can be converted via a threaded connection into an axial movement for opening and closing the expansion valve; and a sleeve element having a valve needle that can be pressed into a valve seat, wherein the valve base body is a one-piece body that at least partially accommodates the valve seat, the sleeve element and the hollow shaft.

[0137] The valve base body is thus designed as a type of valve cartridge. On the one hand, this offers the advantage of simplified valve replacement, since only the valve base body needs to be removed from the valve installation space. On the other hand, a particularly high level of compactness can be achieved, since numerous functions are integrated into the valve cartridge, i.e., the valve base body.

[0138] Furthermore, such a one-piece valve base body offers the possibility of integrating the valve into a customer-specific installation space by adapting just one component. This results in a multitude of different valves that preferably differ only in the valve base body.

[0139] The interior of the various valve base bodies is always designed identically, allowing the functional components inside to be installed in a wide variety of expansion valves. The outer shape of the valve base bodies, however, can be adapted to the customer's specific installation space, so the various valve base bodies differ in this regard.

[0140] This allows for cost savings, especially in manufacturing, as identical parts can be used for different expansion valves. It also reduces the complexity of assembling the expansion valve.

[0141] According to an advantageous development, the valve base body has a valve seat receiving area in a lower area and a receiving area in an upper area, which is designed to receive the hollow shaft and the sleeve element.

[0142] The valve base body thus features mounting areas to allow the functionally necessary elements of the expansion valve to be integrated into the valve base body as easily as possible. This mounting area also reduces the installation space in the axial direction of the expansion valve.

[0143] According to an advantageous further development, the sleeve element is arranged in the receiving area at least partially within the hollow shaft.

[0144] This allows for further space savings. The receiving area can be arranged in a single plane (with the rotational axis R as the normal). The hollow shaft is initially arranged radially inward in the receiving area. Then, the sleeve element is arranged radially inward (i.e., within the hollow shaft). A part of the central spindle and / or a respective force transmission element, for example, are arranged radially inward again.

[0145] This results in an exceptionally compact design. Because multiple elements are placed in one plane, the axial length can be reduced accordingly. This means that the expansion valve can be shortened compared to the state of the art. Particularly in the automotive industry, installation space is often extremely limited, so shorter valves offer more configuration options.

[0146] According to an advantageous development of the invention, the valve base body has a housing seat which is arranged and designed radially circumferentially on one or the upper region of the valve base body in such a way that it finally receives the housing.

[0147] This allows the housing to securely enclose all components inside.

[0148] According to an advantageous development of the invention, the valve base body has a lower seal receiving area and an upper seal receiving area.

[0149] By arranging two different seal receiving areas, reliable sealing can be achieved even with a one-piece valve base body.

[0150] According to an advantageous further development, the valve base body has devices for pressure equalization.

[0151] This means that the valve base body is designed to incorporate pressure equalization devices (e.g., pressure equalization channels). Through the targeted integration of pressure equalization channels or pressure equalization devices, the valve base body can be realized as a single-piece component without compromising the functions of the expansion valve.

[0152] According to an advantageous further development, the housing and a side of the valve base body facing the housing delimit a housing interior, wherein a first device for pressure equalization is arranged as a first pressure equalization channel between the housing interior and the fluid inlet space.

[0153] The first pressure equalization channel preferably has a first channel region, which is arranged at least partially in the valve base body, and a second channel region, which is arranged at least partially in the hollow shaft, wherein the first channel region and the second channel region are connected to one another via a circumferentially surrounding connecting region.

[0154] During operation, an imbalance between the acting forces, especially above and below the components in between, must be prevented wherever possible. This can be achieved, for example, by directing high pressure at the inlet upwards. Overall, the pressure equalization channels are intended to prevent pressure buildup in one of the expansion valve's chambers, which could disrupt its function.

[0155] According to an advantageous further development, the expansion valve has a second pressure equalization channel for pressure equalization between a hollow shaft interior and the housing interior, wherein the hollow shaft interior is formed within the hollow shaft.

[0156] According to an advantageous further development, the sleeve element has a receiving area in which a stamp-like end area of ​​the central spindle, a compression spring and a force transmission element are completely received, wherein, viewed in cross section, the receiving area is arranged completely within the valve base body.

[0157] This saves installation space. The hollow shaft is initially arranged radially inward in the receiving area. Then, the sleeve element is arranged radially inward (i.e., within the hollow shaft). The stamp-like end portion of the central spindle, the compression spring, and the force transmission element are arranged radially inward again.

[0158] This results in an extremely compact structure. Since multiple elements are placed in one plane, the axial length can be reduced accordingly.

[0159] According to an advantageous development, the expansion valve has a third pressure equalization channel which is arranged between a receiving region of the sleeve element and a lower inner region of the valve base body, within which the valve needle is designed to be axially movable.

[0160] The third pressure equalization channel ensures pressure equalization between the space formed in the receiving area of ​​the sleeve element and a lower interior area of ​​the valve base body. The lower interior area of ​​the valve base body is in turn connected to the fluid inlet space via a fluid bore, so that pressure equalization can also take place here via the fluid bore.

[0161] In this way, a reliable and sufficient pressure equalization is achieved in a structurally simple manner between all spaces that are formed or arranged within and partly also adjacent to the expansion valve.

[0162] According to an advantageous further development, the force transmission element has a head region and a shaft region, wherein the force transmission element is arranged such that the contact with the central spindle occurs at a point in a central region of the head region.

[0163] Due to this point-like contact surface between the spindle and the power transmission element, little or no torque can be transmitted. Therefore, the spindle slips during rotation, preventing the power transmission element from rotating. However, axial forces can also be reliably transmitted from the spindle to the power transmission element through point-like contact. Consequently, a torque interruption occurs at the contact surface between the power transmission element and the central spindle.

[0164] According to an advantageous further development, the compression spring is arranged in regions on a lateral surface of the shaft region of the force transmission element.

[0165] Since the compression spring is arranged on the outer surface of the shaft area, it is guided on the one hand by the shaft area. On the other hand, it is guided from the outside by the inner surface of the receiving area of ​​the sleeve element.

[0166] The compression spring does not have to touch the two elements. Rather, it is also conceivable that there is clearance between the outer surface of the shaft area and the compression spring, as well as between the compression spring and the inner surface of the receiving area. However, the compression spring is guided sufficiently far enough to prevent jamming during compression of the spring.

[0167] According to an advantageous further development, the compression spring is a cylindrical spiral spring.

[0168] As a cylindrical spiral spring, the compression spring is particularly inexpensive to manufacture and can be securely arranged around the outer surface of the shaft area.

[0169] According to an advantageous further development, the length of the shaft region is designed so long that when an axial force is exceeded, which leads to a compression of the compression spring by a predefined spring travel, the shaft region comes into contact with a sleeve bottom of the sleeve element.

[0170] This means that when the compression spring is compressed by the predefined spring travel, an axial force can be transmitted directly from the force transmission element to the sleeve base. This allows for maximum stroke limitation in the event of failure of the mechanical stop, i.e., the spindle-stop structure, or if the valve is overloaded. Thus, the force transmission element also fulfills several functions. First, the force transmission element enables torque decoupling of the sleeve element from the spindle. Furthermore, the force transmission element or its shaft area guides the compression spring in axial directions, thus preventing buckling or generally asymmetrical deformation of the compression spring. Furthermore, the shaft area ensures the maximum stroke limitation described above.

[0171] The solution further consists in specifying an expansion valve operable with a stepper motor for installation in a valve installation space, comprising: a housing; a hollow shaft arranged on the housing; a valve base body carrying the hollow shaft, which closes the housing; a rotor which is drivable by means of a stator; and a central spindle which is arranged within the hollow shaft and is drivable by the rotor such that a rotational movement of the spindle can be converted via a threaded connection into an axial movement for opening and closing the expansion valve, wherein the housing and a side of the valve base body facing the housing delimit a housing interior, wherein a hollow shaft interior is formed within the hollow shaft,wherein a fluid inlet chamber is arranged adjacent to a side of the valve base body facing away from the housing when the expansion valve is installed in the valve installation chamber, wherein the housing interior is connected to the fluid inlet chamber via a first pressure equalization channel for pressure equalization, wherein the first pressure equalization channel has a first channel region which is arranged at least partially in the valve base body, and a second channel region which is arranged at least partially in the hollow shaft, wherein the first channel region and the second channel region are connected to one another via a circumferential connecting region.

[0172] The expansion valve thus has a multitude of chambers located within or adjacent to the expansion valve. During operation, an imbalance between the acting forces, especially above and below intervening components, must be prevented wherever possible. This is achieved, for example, by directing high pressure present at the inlet upwards. Overall, the pressure equalization channels are intended to prevent pressure buildup in one or more of the expansion valve chambers, which could impair the function of the expansion valve.

[0173] In the assembled state of the expansion valve, the hollow shaft is arranged in the valve base body (more precisely, in a receiving area of ​​the valve base body). The first channel area is arranged at least partially in the valve base body, and the second channel area is arranged at least partially in the hollow shaft.

[0174] For pressure equalization between the first channel area and the second channel area to occur, they must be fluidly connected. This fluid connection is established via the circumferential connecting area. Because the connecting area is designed as a circumferential connecting area that creates the necessary fluid connection between the two areas, the valve base body and the hollow shaft no longer need to be aligned during assembly. This simplifies assembly and helps prevent assembly errors that could lead to expansion valve failure.

[0175] According to an advantageous further development, the circumferential connection area is a circumferential undercut which is arranged on an inner circumference of a receiving area of ​​the valve base body.

[0176] The circumferential undercut enables a reliable (fluid) connection between the first channel area and the second channel area.

[0177] According to an advantageous further development, the circumferential connecting region is a circumferential chamfer which is arranged on an outer circumference of the hollow shaft.

[0178] This has the particular advantage that the chamfer is easier and therefore more cost-effective to produce than the circumferential undercut in the receiving area.

[0179] If particularly rapid pressure equalization is required, a circumferential undercut and a circumferential chamfer can also be arranged.

[0180] According to an advantageous further development, the second channel region is designed as a longitudinal groove which extends in the hollow shaft from a region arranged in the valve base body to a region not arranged in the valve base body.

[0181] The longitudinal groove is particularly easy to manufacture, and in particular, the longitudinal groove is one in which the previously described slide ring moves axially. The longitudinal groove thus also fulfills a dual function, as it is not only designed as a second channel area but also serves to guide the slide ring, which, as part of the spindle-stop structure, performs functions of the expansion valve.

[0182] According to an advantageous further development, the expansion valve has a second pressure equalization channel for pressure equalization between the hollow shaft interior and the housing interior, which is formed at least in regions by the second channel region.

[0183] In other words, areas of the second channel area also form areas of the second pressure equalization channel.

[0184] According to an advantageous development of the invention, the second pressure equalization channel is arranged in a region of maximum radial extension of the longitudinal groove and the hollow shaft interior.

[0185] This means that the second pressure equalization channel is formed at a bottom of the longitudinal groove. Specifically, it is an opening in the bottom of the longitudinal groove.

[0186] The longitudinal groove can thus provide pressure equalization between the hollow shaft interior and the housing interior not only as a second channel area, but also as part of the second pressure equalization channel in addition to the pressure equalization between the fluid inlet space and the housing interior.

[0187] When the longitudinal groove is introduced into the hollow shaft formed with the hollow shaft interior, the second channel region of the first pressure equalization channel and the second pressure equalization channel can be formed simultaneously.

[0188] According to an advantageous development, the expansion valve has an adapter element which is arranged between the rotor and the spindle for transmitting a torque from the rotor to the spindle, wherein the adapter element has at least one decentralized opening which is arranged such that it compensates for a pressure in the housing interior above the adapter element and below the adapter element.

[0189] The decentralized opening in the adapter element also allows the pressure within the housing's interior, namely between an upper area (above the adapter element) and a lower area (below the adapter element), to be quickly and easily equalized. This further increases the functional reliability of the expansion valve.

[0190] According to an advantageous development, the expansion valve has a third pressure equalization channel which is arranged between a receiving region of a sleeve element which has a valve needle of the expansion valve and a lower inner region of the valve base body, within which the valve needle is designed to be axially movable and which is connected to the fluid inlet space via a fluid bore.

[0191] The third pressure equalization channel thus ensures pressure equalization between the space formed in the receiving area of ​​the sleeve element and a lower interior area of ​​the valve base body. The lower interior area of ​​the valve base body is in turn connected to the fluid inlet space via a fluid bore, so that pressure equalization can also take place here via the fluid bore.

[0192] In this way, a reliable and sufficient pressure equalization is achieved in a structurally simple manner between all spaces that are formed or arranged within and partly also adjacent to (e.g. fluid inlet space) the expansion valve.

[0193] According to an advantageous further development, a stamp-like end region of the central spindle, a compression spring and a force transmission element are accommodated in the receiving region of the sleeve element.

[0194] This results in a particularly compact design of the expansion valve, which nevertheless allows all functions to be fulfilled.

[0195] According to an advantageous further development, the force transmission element is designed and arranged such that it transmits axial forces from the central spindle via the compression spring to the sleeve element through contact with the central spindle, wherein the force transmission element is mushroom-shaped when viewed in cross section.

[0196] According to an advantageous further development, the force transmission element has a head region and a shaft region, wherein the force transmission element is arranged such that the contact with the central spindle occurs at a point in a central region of the head region.

[0197] Due to this point-like contact surface between the spindle and the power transmission element, little or no torque can be transmitted. As a result, the spindle slips during rotation, preventing the power transmission element from rotating. However, axial forces can also be reliably transmitted from the spindle to the power transmission element via the point-like contact surface. Consequently, torque is interrupted at the contact surface between the power transmission element and the central spindle.

[0198] According to an advantageous further development, the expansion valve has a valve seat, wherein the valve base body is a one-piece body which accommodates the valve seat, the sleeve element and the hollow shaft at least in regions.

[0199] The valve base body is thus designed as a cartridge. On the one hand, this offers the advantage of simplified valve replacement, since only the valve base body needs to be removed from the valve installation space. On the other hand, a particularly high level of compactness can be achieved, since numerous functions are integrated into the valve cartridge, i.e., the valve base body.

[0200] Furthermore, such a one-piece valve base body offers the possibility of integrating the valve into a customer-specific installation space by adapting just one component. This can save costs, especially in manufacturing, as identical parts can be used for different expansion valves. It also reduces the complexity of assembling the expansion valve.

[0201] According to an advantageous development, the valve base body has a lower seal receiving area and an upper seal receiving area.

[0202] By arranging two different seal receiving areas, reliable sealing can be achieved even with a one-piece valve base body.

[0203] The solution further consists in providing a method for producing an expansion valve, which comprises the following steps: providing the hollow shaft; and introducing the longitudinal groove into the hollow shaft.

[0204] According to an advantageous further development, the second pressure equalization channel is formed in the hollow shaft when the longitudinal groove is introduced.

[0205] By simultaneously inserting the second pressure equalization channel, an additional work step that would otherwise be required to insert the second pressure equalization channel separately is eliminated.

[0206] The advantages of the invention will become apparent from the description and the drawings.

[0207] The invention will be explained in more detail below with reference to the description of exemplary embodiments and the accompanying drawings. The invention is defined in the claims.

[0208] The drawings used to explain the embodiments show: Fig. 1 shows a longitudinal section of an expansion valve according to the invention in a state installed in a valve installation space; Fig. 2 a detailed longitudinal section of a movement mechanism of the expansion valve according to the invention; Fig. 3 a schematic representation of an adapter element of the expansion valve according to the invention; Fig. 4 a detailed longitudinal section of an adapter element and a rotor of the expansion valve according to the invention; Fig. 5 a schematic representation of a guide spring of the expansion valve according to the invention; Fig. 6 a schematic representation of a sliding ring of the expansion valve according to the invention; Fig. 7 a top view of the sliding ring from Fig. 6; Fig. 8 a schematic representation of a hollow shaft of the expansion valve according to the invention; Fig. 9 a schematic representation of the spindle-stopper geometry of the expansion valve according to the invention; Fig. 10 shows a longitudinal section of a power transmission and torque limiting device of the expansion valve according to the invention; Fig. 11 a longitudinal section of a sleeve element of the expansion valve according to the invention; Fig. 12 a schematic representation of a force transmission element of the expansion valve according to the invention; Fig. 13 is a schematic representation of a compression spring of the expansion valve according to the invention; Fig. 14 a longitudinal section of a valve base body of the expansion valve according to the invention; Fig. 15 a schematic representation of the valve base body from Fig. 14; Fig. 16 a detailed longitudinal section of the valve base body of the expansion valve according to the invention; and Fig. 17 a detailed longitudinal section of a hollow shaft of the expansion valve according to the invention.

[0209] The Fig. 1 shows a longitudinal section of an expansion valve 1 according to the invention in an exemplary embodiment. For description purposes, Fig. 1 defines a top side 2 and a bottom side 3. The top side 2 and the bottom side 3 are also used to describe individual components, the overall arrangement of which is shown in Fig. 1 is recognizable.

[0210] The expansion valve 1 has a valve base body 5 and a housing 4. In Fig. 1, the expansion valve 1 is shown in a state in which it is installed in a valve installation space 43. The valve installation space 43 is generally understood to be a cavity into which the expansion valve 1 is to be or will be installed.

[0211] Since the valve base body 5 is a one-piece body, it can be inserted into the valve installation space 43 like a cartridge. Accordingly, the entire expansion valve 1 can be easily installed and removed from the valve installation space 43.

[0212] When the expansion valve 1 is installed in the valve installation space 43, a fluid channel 46 is formed. This extends in Fig. 1 from a lateral area (left side in Fig. 1) coming in the direction of the valve base body 5 and forms a fluid inlet chamber 27 around a lower region (i.e. towards the underside 3) of the valve base body 5.

[0213] The fluid inlet chamber 27 is connected to a lower inner region 42 of the valve base body 5 via fluid bores 40. A valve needle 20 of the expansion valve 1 is also arranged in this lower inner region 42.

[0214] When the expansion valve 1 is opened, the fluid channel 46 is formed from the lateral region of the expansion valve 1, through the fluid inlet chamber 27, through the fluid bore 40, through the lower inner region 42 of the valve base body 5 and through a valve opening which can be closed by means of the valve needle 20, to a region below the expansion valve 1.

[0215] The housing 4 is arranged on an upper side (i.e., toward the top side 2) of the valve base body 5. In particular, the housing 4 is sleeve-shaped.

[0216] All functional elements or components of the expansion valve 1 are arranged within the housing 4 or within the valve base body 5. The housing 4 is radially surrounded by a stepper motor (not shown here) or a stator thereof.

[0217] The valve base body 5 closes the housing 4 on the underside 3. A rotor 6 (of the stepper motor) is arranged in the housing 4, which transmits its rotation to a central spindle 8.

[0218] In Fig. 1, the rotation of the rotor 6 is transmitted to the central spindle 8 via an adapter element 13. The central spindle 8 has an external thread that is connected to an internal thread of a hollow shaft 7 as a threaded connection 9.

[0219] Through the threaded connection 9, the central spindle 8 moves axially downward (i.e., from the top side 2 to the bottom side 3) or upward (i.e., from the bottom side 3 to the top side 2) along a rotation axis R. Consequently, this movement mechanism can convert the rotational movement of the rotor 6 into an axial movement.

[0220] A spiral body 12 is formed around the hollow shaft 7. In the Fig. In the embodiment shown in Figure 1, this spiral body 12 is designed as a guide spring 12. Reference numeral 12 is used for the guide spring and the spiral body.

[0221] A stop body runs within the spiral body 12 (i.e., within a thread 16 thereof). Here, the stop body is designed as a sliding ring 17.

[0222] The guide spring 12 and the sliding ring 17 form a spindle-stopper geometry, which defines an upper (axial) end position and a lower (axial) end position of the central spindle 8. The function of the spindle-stopper structure will be described in more detail with reference to Fig. 2 and Fig. 9 explained.

[0223] A lower part (i.e., toward the underside 3) of the central spindle 8 is received in a sleeve element 21. The sleeve element 21 itself is received in the valve base body 5. Furthermore, a lower region of the hollow shaft 7 is also received in the valve base body 5.

[0224] In particular, the sleeve element 21, as shown in Fig. 1, is partially received in the hollow shaft 7, which in turn is partially received in the valve base body 5. This means that an inner peripheral surface of the valve base body 5 is in contact with an outer peripheral surface of the hollow shaft 7. Furthermore, an inner peripheral surface of the hollow shaft 7 is in contact with an outer peripheral surface of the sleeve element 21.

[0225] At a lower portion, the sleeve element 21 has the valve needle 20. The sleeve element 21 is a one-piece body, meaning that the valve needle 20 is sleeve-shaped.

[0226] The valve needle 20 sits in a valve seat 34, wherein by lifting (upwards, i.e. towards the top side 2) from the valve seat 34 an opening is released through the valve seat 34 and a fluid can flow through it.

[0227] In Fig. 1, the valve needle 20 is shown in its mounted state, in which it presses sealingly onto the valve seat 34.

[0228] Within the sleeve element 21, elements are arranged which serve to transmit force and limit the torque between the spindle 8 and the sleeve element 21. These elements are described in more detail with reference to Fig. 10 described.

[0229] The Fig. Figure 2 shows an upper part of the expansion valve 1 in more detail. In particular, Fig. 2 the rotor 6, which is connected via the adapter element 13 to the central spindle 8, which in turn is connected via the threaded connection 9 to the hollow shaft 7.

[0230] As in Fig. 2, the guide spring 12 is arranged on a lateral surface 10 of the hollow shaft 7. In particular, the guide spring 12 is the one shown in Fig. 5. This spiral spring has a first stop element 14 and a second stop element 15. The two stop elements 14, 15 are arranged at respective ends of the guide spring 12, which is designed as a spiral spring. In particular, the first stop element 14 extends axially upward from an upper end of the spiral spring, whereas the second stop element 15 extends axially downward from a lower end of the guide spring 12.

[0231] As in Fig. 2, the first stop element 14 is connected to the adapter element 13. This also means that the guide spring 12 or the spiral body 12 can rotate with the adapter element 13. For this purpose, the adapter element 13 has decentralized openings 13c (see Fig. 3) into which the first stop element 14 can be or is inserted.

[0232] The second stop element 15 is, as shown in Fig. 1, is oriented toward the valve base body 5. Preferably, the second stop element 15 can grind the latter against the valve base body 5 during operation. Alternatively, a circular groove could be formed in the valve base body 5, in which the second stop element 15 of the spiral body 12 or the guide spring 12 extends and is guided.

[0233] As in Fig. 3, the adapter element 13 has a plate-shaped base area 13a and a receiving area 13b for the central spindle 8. The receiving area 13b extends centrally from the plate-shaped base area 13a axially in the direction of the rotation axis R (see Fig. 4).

[0234] The rotor 6, the adapter element 13, the spiral body 12 and the central spindle 8 rotate around the rotation axis R.

[0235] The adapter element 13 has several decentralized openings 13c, which are formed decentrally, i.e. away from the center, in the plate-shaped base area 13a. In Fig. 3, four decentralized openings 13c in the form of elongated holes are formed on an outer periphery of the plate-shaped base region 13a. The design of the decentralized openings 13c as elongated holes provides particular manufacturing-related advantages.

[0236] The upper end region, i.e. the first stop element 14, of the guide spring 12 extends into one of the decentralized openings 13c. The remaining decentralized openings 13c in the plate-shaped base region 13a of the adapter element 13 can serve, for example, to ensure sufficient pressure equalization between a housing interior 28 above the adapter element 13 and a housing interior 28 below the adapter element 13.

[0237] Within the receiving area 13b of the adapter element 13, a central through-opening 13d is formed, into which an upper portion of the central spindle 8 can be received. This upper portion of the spindle 8, viewed in cross-section, is complementary to the central through-opening 13d. In this context, "viewed in cross-section" means that the two components are viewed along the rotational axis R.

[0238] For power transmission, it would be conceivable for the two elements to have a cross-sectional shape that is not circular, but rather non-rotationally symmetrical. This allows for easy transmission of torque from the adapter element 13 to the central spindle 8. For example, the central through-hole 13d can be polygonal, preferably square. However, any non-rotationally symmetrical configuration for easy torque transmission is conceivable.

[0239] Preferably, however, the cross-section is circular and the force is transmitted, for example, via a welded connection.

[0240] As in Fig. 4, an outer circumference of the plate-shaped base portion 13a is connected to the rotor 6. As a result, the torque of the rotor 6 is transmitted to the adapter element 13. As also shown in Fig. 4 and Fig. As can be seen in Figure 2, an upper portion of the rotor 6 has a stop so that the adapter element 13 cannot slip through the rotor 6. This is particularly advantageous during assembly and serves to prevent errors.

[0241] The connection between rotor 6 and adapter element 13 can be materially bonded, positively connected, or frictionally connected. It is essential here that torque can be transmitted from rotor 6 to adapter element 13. In principle, it would also be conceivable for adapter element 13 and rotor 6 to be formed as a single component.

[0242] In Fig. 2 shows a section through the sliding ring 17, which runs in the thread 16 of the guide spring 12.

[0243] A larger view of the sliding ring 17 is shown in the Fig. 6 and Fig. 7. Here, it can be seen that the sliding ring 17 is designed as a spiral element. In particular, the sliding ring 17 is designed as a cylindrical spiral that, when installed, is wound around the rotational axis R.

[0244] As in Fig. As shown in Figure 6, the sliding ring 17 has an upper end 17a and a lower end 17b. The upper end 17a and the lower end 17b can overlap, forming a spiral body with more than one winding. This overlap of the ends and the number of turns of the guide spring 12 limit the maximum number of possible revolutions of the central spindle 8.

[0245] At one of its ends, here at the lower end 17b, the sliding ring 17 has a radially inwardly extending extension 18. As in Fig. 2, this extension 18 runs in the hollow shaft 7. More precisely, the extension 18 of the sliding ring 17 can be inserted into a longitudinal groove 11 of the hollow shaft 7 or is inserted during use. This longitudinal groove 11 is particularly well suited to Fig. 8 and Fig. 9 can be seen.

[0246] Fig. Figure 8 shows the hollow shaft 7 in a schematic representation. The hollow shaft 7 is designed as a hollow cylinder that encloses a hollow shaft interior 29. As in Fig. 8, a hollow shaft bore 31 is arranged on an upper region of the hollow shaft 7, through which the central spindle 8 can be guided. The longitudinal groove 11 is arranged on the lateral surface 10 and extends axially (in the installed state parallel to the rotation axis R). The longitudinal groove 11 is preferably open downwards (i.e., towards the underside 3). Alternatively, however, it can be Fig. 9, be limited at the top and bottom.

[0247] When installed, the extension 18 of the sliding ring 17 is arranged in this longitudinal groove 11. This prevents the sliding ring 17 from rotating relative to the hollow shaft 7. This means that the longitudinal groove 11 and the extension 18 prevent the sliding ring 17 from rotating. Consequently, the sliding ring 17 can only move axially upwards (along the longitudinal groove 11) and axially downwards (also along the longitudinal groove 11).

[0248] When the rotor 6 rotates during operation and the adapter element 13 transmits this rotational movement to the guide spring 12 (via the decentralized opening 13c), the guide spring 12 rotates relative to the hollow shaft 7 and also relative to the sliding ring 17 axially secured in the hollow shaft 7 (i.e. in the longitudinal groove 11). However, the rotation of the guide spring 12 causes the sliding ring 17 to move in the thread 16 of the guide spring 12. Accordingly, the sliding ring 17 moves up and down along the thread 16. In particular in Fig. 9 it can be clearly seen that the spiral-shaped sliding ring 17 runs in the thread 16 of the guide spring 12.

[0249] The spindle stopper geometry of the present invention is now formed in that the sliding ring 17 can only move upwards along the thread 16 until the sliding ring 17 abuts with its upper end 17a against the first stop element 14 of the guide spring 12.

[0250] Whether the upper or lower end position of the central spindle 8 is determined depends on the pitch of the guide spring or the spiral body 12. If the thread pitch of the spindle 8 is different from that of the spiral body 12, the first stop element 14 serves to determine the upper end position of the central spindle 8. If the spindle 8 and the spiral body 12 have the same pitch direction, the first stop element 14 specifies the lower end position of the central spindle 8. Preferably, the thread pitch of the central spindle 8 and the thread pitch of the central spiral body 12 are the same.

[0251] As soon as the sliding ring 17 abuts the first stop element 14, no further rotation of the guide spring 12 relative to the sliding ring 17 is possible in this direction of rotation. More precisely, the rotation of the adapter element 13 is slowed down by the guide spring 12 being blocked, i.e., the guide spring 12 cannot rotate further because it is blocked by the sliding ring 17.

[0252] The braking force flow occurs from the longitudinal groove 11 of the hollow shaft 7 to the extension 18 of the sliding ring 17, and from the extension 18 to an upper end 17a of the sliding ring 17, to the first stop element 14 of the guide spring 12, and from the first stop element 14 to the decentralized opening 13c of the adapter element 13. Naturally, a certain degree of expansion of the individual elements can occur, leading to a dampening of the braking force, which may well be desired. This is particularly the case at the lower stop point.

[0253] Fig. 9 shows the sliding ring 17 at this lower stop point. As in Fig. 9, the guide spring 12 has rotated so far relative to the sliding ring 17 (and the hollow shaft 7) that the sliding ring 17 has moved to a lower end of the guide spring 12. There, the lower end 17b of the sliding ring 17 comes into contact with the second stop element 15 of the guide spring 12. The braking force flow now runs from the longitudinal groove 11 of the hollow shaft 7 to the lower end 17b of the sliding ring 17 and from the lower end 17b of the sliding ring 17 to the (lower) second stop element 15 of the guide spring 12. From this second stop element 15, the braking force flow runs along the entire guide spring 12 to the first stop element 14 and then back to the decentralized opening 13c of the adapter element 13.

[0254] This means that, in contrast to the upper stop point, the braking force flow here is along the entire guide spring 12. If the guide spring 12 is designed as a rigid spiral body, there is no or only negligible damping of the braking force acting on the central spindle 8.

[0255] Depending on the pitch of the spiral body, the lower or upper end position of the spindle 8 results when the first stop element 14 comes into contact with the upper end 17a of the sliding ring 17, and the upper or lower end position of the spindle 8 results when the second stop element 15 comes into contact with the lower end 17b (optionally plus the maximum angle of rotation of the spiral body 12).

[0256] In the Fig. Figures 10 to 13 illustrate the force transmission mechanism from the spindle 8 to the sleeve element 21 or the valve needle 20. The central spindle 8 has a stamp-like end portion 22 formed at a lower end of the spindle 8.

[0257] This stamp-like end portion 22 is received in the sleeve element 21. More precisely, the stamp-like end portion 22 is received in a receiving portion 21a of the sleeve element 21. As shown in Fig. 10, a compression spring 24 and a force transmission element 23 are further arranged in the receiving area 21a.

[0258] The compression spring 24, which is shown in an enlarged view in Fig. 13, is in contact with a sleeve bottom 21b of the sleeve element 21. The compression spring 24 is a cylindrical coil spring, the lower portion of which rests on the sleeve bottom 21b of the sleeve element 21.

[0259] As in Fig. As shown in Figure 12, the force transmission element 23 has a head region 23a and a shaft region 23b. The shaft region 23b, in turn, has a lateral surface 23c.

[0260] The shaft portion 23b can be arranged within the compression spring 24. In other words, the compression spring 24 is supported inwardly by the outer surface 23c of the shaft portion 23b. The force transmission element 23 thus also serves as a guide element for the compression spring 24, with buckling of the compression spring 24 also being prevented by the inner circumferential surface of the receiving portion 21a. Overall, the compression spring 24 is thus supported by the receiving portion 21a and the receiving portion 21a.

[0261] As in Fig. As can be seen in Figure 12, the force transmission element 23 has a mushroom shape overall. This means that the head region 23a is partially spherical, for example, hemispherical, and has an outer circumference that is larger than the outer circumference of the shaft region 23b. In other words, the head region 23a is mushroom-head-shaped, and the shaft region 23b is mushroom-stem-shaped.

[0262] Since the head portion 23a is wider, a contact area is formed between the force transmission element 23 and the compression spring 24. This means that an upper portion of the compression spring 24 can contact a lower portion of the head portion 23a.

[0263] However, the mushroom-shaped head portion 23a also has the advantage that the contact area with the plunger-like end portion 22 is essentially point-like. An axial force (i.e., from top (2) to bottom (3) or from bottom (3) to top (2)) can be transmitted effectively via this point-like contact area, whereas a torque is transmitted only very poorly. Thus, no significant torque is transmitted from the plunger-like end portion 22 to the force transmission element 23. Therefore, the force transmission element 23 can serve as a type of torque-limiting device.

[0264] When a rotary motion is transmitted from the rotor 6 to the central spindle 8 via the adapter element 13, the plunger-like end portion 22 moves upward or downward. When the plunger-like end portion 22 moves downward, it presses against the force transmission element 23, which in turn, damped by the compression spring 24, presses against the sleeve base 21b and thus against the sleeve element 21 and the valve needle 20. This means that the valve needle 20 is pressed toward the valve seat 34.

[0265] An upper region (toward the top side 2) of the sleeve element 21 is closed by a bushing 44. The bushing 44 is hollow-cylindrical and made of a different material than the spindle 8. In particular, the first material from which the spindle 8 is made is harder than the second material from which the bushing 44 is made. This allows for low friction between the spindle 8, i.e., the plunger-like end region 22, and the bushing 44 to be achieved. This is advantageous so that the valve needle 20 does not rotate for long periods in the valve seat 34.

[0266] Furthermore, this means that when friction occurs between the first material and the second material, targeted wear occurs on the (less hard) second material. This allows wear on the power transmission system or the affected components to be controlled.

[0267] The bushing 44, the sleeve element 21 with valve needle 20, and the force transmission element 23 rotate at the same speed as the spindle 8 until the valve needle 20 is impeded in its axial movement in the valve seat 34 and the prevailing torque is smaller than that between the contact point between the bushing 44 and the spindle 8. Only when the braked torque (static friction torque) in the valve seat 34 is large enough does the valve needle 20 stop. From then on, a relative movement takes place between the spindle 8 and the bushing 44. This movement takes place briefly on the end face (bush 44) and then only partially on the inner surface of the bushing 44.

[0268] The main reason for re-tightening the spindle 8 after the valve needle 20 is seated in the valve seat 34 is to ensure reliable closure even after extended service life. This ensures reliable valve closure even after years of wear. Therefore, the spindle 8 is re-tightened several times, for example, 10 times. This re-tightening requires reliable torque decoupling.

[0269] The advantage of using the bushing 44 is, in particular, that it can be subjected to targeted wear and ensures low friction with the spindle 8. Thus, neither the sleeve element 21 nor the (central) spindle 8 wears. Because the force transmission area between the force transmission element 23 and the central spindle 8 is kept as small as possible by the special shape of the head region 23a, particularly high friction does not occur here, so that the force transmission element 23 can also be made of the first material.

[0270] The first material is, for example, stainless steel, and the second material is, for example, a copper alloy, preferably brass. The material pairing of brass and stainless steel is particularly advantageous. Because the sleeve element 21 is relatively long in the longitudinal direction (i.e., along the rotation axis R), sufficient material is available that can be removed from it.

[0271] Fig. 14 shows a longitudinal section of the valve base body 5. The valve base body 5 has a side 5a facing the housing 4, which is an upper side (toward the top side 2) of the valve base body 5. On an opposite side to the side 5a facing the housing 4, the valve base body 5 has a side 5b facing away from the housing 4.

[0272] As in Fig. 1, the fluid inlet chamber 27 is formed adjacent to this side 5b of the valve base body 5 facing away from the housing 4 in the state installed in the valve installation chamber 43.

[0273] The valve base body 5 further comprises a receiving area 33 in which (in the assembled state), as shown in Fig. 1, first the hollow shaft 7 is received and the sleeve element 21 is received within the hollow shaft 7.

[0274] A circumferential undercut 32 is formed in a lower region of the receiving region 33.

[0275] A valve seat receiving area 35 is located further down in the valve base body 5. This valve seat receiving area 35 provides a stop for the valve seat 34 when it is pushed into the valve base body 5 from above. This ensures a secure and defined fit of the valve seat 34.

[0276] A lower seal receiving area 36 is formed on an outer lower area of ​​the valve base body 5. As shown in Fig. 1, an annular sealing body can be inserted into these in the assembled state. This seals the fluid inlet chamber 27 from a region of the fluid channel 46 located below the expansion valve 1, and vice versa.

[0277] Back to Fig. 14 - there, an upper seal receiving area 37 is formed in a middle to upper area of ​​the valve base body 5. As in Fig. 1, in the installed state, an annular sealing element is also arranged in this upper seal receiving area 37, which in particular seals the fluid inlet space 27 from the outside environment.

[0278] As further stated in the Fig. 14 to 16, a housing seat 39 is arranged on an upper side 2 of the valve base body 5. This is arranged, in particular, radially circumferentially on the upper region (on the side facing the housing 4) of the valve base body 5 so that it can finally accommodate the housing 4. As shown in Fig. 1, a closing element (for example in the form of a ring) can press the housing 4 radially inwards against the housing seat 39 from the outside.

[0279] A plurality of pressure equalization channels 25, 26, and 41 are formed within the expansion valve 1. A first pressure equalization channel 25 is arranged, connecting the housing interior 28 with the fluid inlet chamber 27 in order to establish pressure equalization between these two chambers.

[0280] This first pressure equalization channel 25 has a first channel region 25a and a second channel region 25b. The first channel region 25a is, as shown in Fig. 14 and Fig. 16, is formed within the valve base body 5. In particular, the first channel region 25a is a bore from the side 5b facing away from the housing 4 into the valve base body 5. The first channel region 25a is formed up to the circumferential undercut 32 of the valve base body 5. This means that the bore extends up to this undercut 32. Thus, the first channel region 25a itself creates a connection from the side 5b facing away from the housing 4 to the receiving region 33 of the base body 5.

[0281] In the assembled state of the expansion valve 1, in this receiving area 33 the Fig. 17. The hollow shaft 7 has the second channel region 25b, which extends upwardly from a lower end thereof in the form of the longitudinal groove 11.

[0282] Particularly preferably, the lower end of the hollow shaft 7 is designed as a circumferential chamfer 38, so that both the circumferential chamfer 38 and the circumferential undercut 32 serve as a connecting region between the first channel region 25a and the second channel region 25b.

[0283] In general, a circumferential connection area has the particular advantage that no alignment is required between the hollow shaft 7 and the valve base body 5. In principle, however, it would be sufficient if either the circumferential undercut 32 or the circumferential chamfer 38 were formed. However, the formation of both elements leads to faster pressure equalization.

[0284] The longitudinal groove 11 of the hollow shaft 7 thus has a dual function. On the one hand, it serves to guide the sliding ring 17, and on the other hand, it serves as a second channel area 25b to create pressure equalization. This is achieved in particular by the fact that the longitudinal groove 11 is open to the housing interior 28. Consequently, pressure equalization is achieved between the fluid inlet chamber 27 and the housing interior 28.

[0285] A second pressure equalization channel 26 ensures pressure equalization between the hollow shaft interior 29 and the housing interior 28. This second pressure equalization channel 26 is particularly well suited for Fig. 17. In this figure, it can be seen in particular that the second pressure equalization channel 26 is formed in the region of maximum radial extension of the longitudinal groove 11 and the hollow shaft interior 29. This has the particular advantage that when the longitudinal groove 11 is introduced into the hollow shaft 7 formed with the hollow shaft interior 29, the second pressure equalization channel 26 can also be created simultaneously, without the need for a separate work step.

[0286] In principle, the second pressure equalization channel 26 is an opening at the bottom of the longitudinal groove 11. This opening is connected to the hollow shaft interior 29 and the longitudinal groove 11 (and consequently also to the housing interior 28). Furthermore, the second pressure equalization channel 26 is partially formed by the second channel region 25b of the first pressure equalization channel 25, or the pressure equalization channels share common areas.

[0287] The expansion valve 1 further comprises a third pressure equalization channel 41. This third pressure equalization channel 41 is particularly well suited for Fig. 10 and connects the lower inner region 42 of the valve base body 5 with the receiving region 21a of the sleeve element 21. The lower inner region 42 of the valve base body 5 is further connected via the fluid bores 40, as in Fig. 1, connected to the fluid inlet chamber 27.

[0288] The scope of the present invention is given by the claims and is not limited by the features explained in the description or shown in the figures. List of reference symbols 1 expansion valve 2 Top 3 Bottom 4 housings 5 valve base body 5a side facing the housing (of the valve base body) 5b Side facing away from the housing (of the valve base body) 6 Rotor 7 hollow shaft 8 central spindle 9 Threaded connection 10 Shell surface (of the hollow shaft) 11 Longitudinal groove 12 spiral bodies 13 Adapter element 13a plate-shaped base area 13b Mounting area for central spindle 13c decentralized opening 13d central passage opening 14 first stop element 15 second stop element 16 threads (of the guide spring) 17 sliding ring 17a upper end (of the sliding ring) 17b lower end (of the sliding ring) 18 Extension 20 valve needle 21 Sleeve element 21a Receiving area (of the sleeve element) 21b Case base 22 stamp-like end area 23 Power transmission element 23a Head area 23b Shaft area 23c Shell surface (of the shaft area of ​​the power transmission element) 24 compression spring 25 first pressure equalization channel 25a first channel area (of the first pressure equalization channel) 25b second channel area (of the first pressure equalization channel) 26 second pressure equalization channel 27 Fluid inlet chamber 28 Housing interior 29 Hollow shaft interior 31 hollow shaft bore 32 circumferential undercut (of the valve base body) 33 Mounting area (of the valve base body) 34 Valve seat 35 Valve seat receiving area (of the valve base body) 36 lower seal receiving area 37 upper seal receiving area 38 circumferential chamfer (of the hollow shaft) 39 Housing seat 40 Fluid bore 41 third pressure equalization channel 42 lower interior area (of the valve base body) 43 Valve installation space 44 socket 46 Fluid channel R Rotationsachse

Claims

[1] Expansion valve (1) operable by a stepper motor, comprising the following: a housing (4); a hollow shaft (7) which is arranged in the housing (4); a valve base body (5) supporting the hollow shaft (7), which closes off the housing (4); a rotor (6) which can be driven by means of a stator; a central spindle (8) which is arranged inside the hollow shaft (7) and can be driven by the rotor (6) in such a way that a rotational movement of the spindle (8) can be converted into an axial movement for opening and closing the expansion valve (1) via a threaded connection (9); an adapter element (13) which is arranged between the rotor (6) and the spindle (8) for transmitting a torque from the rotor (6) to the spindle (8); and a spiral body (12) which is arranged on a cylindrical surface (10) of the hollow shaft (7) and can be set into a rotational movement by means of the adapter element (13), wherein the spiral body (12) has an axially extending first stop element (14) which is arranged in a decentralized opening (13c) of the adapter element (13). [2] Expansion valve (1) according to claim 1, wherein the adapter element (13) has a plate-shaped base area (13a) and a receiving area (13b) extending axially centrally from the plate-shaped base area (13a) for the central spindle (8). [3] Expansion valve (1) according to claim 2, wherein a central through-opening (13d) along an axis of rotation (R) of the adapter element (13) is designed to accommodate an upper region of the spindle (8). [4] Expansion valve (1) according to claim 3, wherein the adapter element (13) is rotationally symmetrical with respect to the axis of rotation (R). [5] Expansion valve (1) according to one of claims 2 to 4, wherein the decentralized opening (13c) is arranged in the plate-shaped base area (13a), and wherein the plate-shaped base area (13a) has further decentralized openings (13c). [6] Expansion valve (1) according to claim 5, wherein the decentralized openings (13c) are designed as elongated holes. [7] Expansion valve (1) according to one of claims 5 or 6, wherein at least one of the further decentralized openings (13c) is arranged such that it equalizes a pressure in the housing interior (28) above the adapter element (13) and below the adapter element (13). [8] Expansion valve (1) according to any one of the preceding claims, wherein the spiral body (12) has a thread (16), wherein the hollow shaft (7) has a longitudinal groove (11) on the outer surface (10), and wherein a sliding ring (17) is arranged in the thread (16) of the spiral body (12) so as to be secured against rotation by means of the longitudinal groove (11) and to be movable in the axial direction. [9] Expansion valve (1) according to claim 8, in which a spindle-stopper structure is formed by the interaction of the spiral body (12) and the sliding ring (17) which defines an upper end position and a lower end position of the central spindle (8). [10] Expansion valve (1) according to claim 8 or 9, wherein the spiral body (12) has a second stop element (15) extending in the axial direction opposite to the first stop element (14).

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