EXPANSION VALVE

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 art (see, for example, CN 102 252 120 A). For example, a stopper structure for a motorized valve is known from JP 3328530 B2. 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 a linear motion by a screw action of an inner screw and an outer screw.

[0004] 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.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] Another disadvantage of known expansion valves is that they are complex to manufacture.

[0013] 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.

[0014] Furthermore, the invention is based on the object of enabling a method for producing an expansion valve which is less complex than the methods known from the prior art.

[0015] The solution according to the invention consists in specifying an expansion valve operable with a stepper motor, which has the following: a housing; a hollow shaft which is arranged in the housing; a valve base body which carries the hollow shaft and closes the housing; a rotor which is drivable by means of a stator; a central spindle which is arranged within the hollow shaft and is drivable 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;

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] According to an advantageous development of the invention, 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.

[0021] Depending on the direction of rotation, the sliding ring is moved axially up or down along the hollow shaft (within the longitudinal groove).

[0022] 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.

[0023] Furthermore, the fact that the sliding ring is secured in the longitudinal groove also secures the assembly consisting of the spiral body and sliding ring to the outer surface of the hollow shaft. Thus, the guide groove, together with the sliding ring, also acts as a loss protection.

[0024] According to an advantageous development of the invention, the spindle stopper structure is formed by the interaction of the spiral body and the sliding ring.

[0025] According to an advantageous development of the invention, the sliding ring has a radially inwardly extending extension which is designed to run in the longitudinal groove and act there as an anti-twist device.

[0026] 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.

[0027] According to an advantageous development of the invention, 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.

[0028] 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.

[0029] 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 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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 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.

[0035] 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.

[0036] According to an advantageous development of the invention, 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.

[0037] The adapter element is connected to the spindle in a force-locking manner, for example, by a press connection, welded connection, or 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] The steel is in particular a steel that has sufficient elasticity to form it into a spiral body.

[0042] This makes the production of the spiral body particularly cost-effective.

[0043] 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.

[0044] The use of plastic in the expansion valve saves weight compared to a metallic 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 failure.

[0045] According to an advantageous development of the invention, 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.

[0046] 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.

[0047] According to an advantageous development of the invention, 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.

[0048] 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.

[0049] According to an advantageous development of the invention, 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.

[0050] This also allows for a particularly compact expansion valve design. In particular, components can be saved by assigning a second function to existing components.

[0051] 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.

[0052] According to an advantageous development of the invention, 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.

[0053] This also enables a safe pressure equalization between the hollow shaft interior and the housing interior.

[0054] Further advantages of the invention will become apparent from the description and the drawings. The invention will be explained in more detail below with reference to the description of exemplary embodiments and the accompanying drawings.

[0055] 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 shows a detailed longitudinal section of a movement mechanism of the expansion valve according to the invention; Fig. 3 shows a schematic representation of an adapter element of the expansion valve according to the invention; Fig. 4 shows a detailed longitudinal section of an adapter element and a rotor of the expansion valve according to the invention; Fig. 5 shows a schematic representation of a guide spring of the expansion valve according to the invention; Fig. 6 shows a schematic representation of a sliding ring of the expansion valve according to the invention; Fig. 7 shows a plan view of the sliding ring 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 a longitudinal section of a force 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 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 of 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.

[0056] 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 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 Fig. 1 is recognizable.

[0057] 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.

[0058] 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.

[0059] 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 ) in the direction of the valve base body 5 and forms a fluid inlet space 27 around a lower region (i.e. towards the underside 3) of the valve base body 5.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] In Figur 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.

[0066] 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.

[0067] A spiral body 12 is formed around the hollow shaft 7. In the Fig. 1 In the embodiment shown, this spiral body 12 is designed as a guide spring 12. Reference numeral 12 is used for the guide spring and the spiral body.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] In particular, the sleeve element 21, as shown in Fig. 1 shown, 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.

[0072] 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.

[0073] 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.

[0074] In Fig. 1 the valve needle 20 is shown in its mounted state, in which it presses sealingly onto the valve seat 34.

[0075] 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.

[0076] The Fig. 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 13 to the central spindle 8, which in turn is connected via the threaded connection 9 to the hollow shaft 7.

[0077] As in Fig. 2 As can be seen, 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.

[0078] As in Fig. 2 As can be seen, 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.

[0079] The second stop element 15 is, as shown in Fig. 1 shown, oriented in the direction of the valve base body 5. Preferably, the second stop element 15 can rub against the base body 5 during operation. Alternatively, a circular groove could be formed in the base body 5, in which the second stop element 15 of the spiral body 12 or the guide spring 12 extends and is guided.

[0080] As in Fig. 3 As shown, 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 ).

[0081] The rotor 6, the adapter element 13, the spiral body 12 and the central spindle 8 rotate around the rotation axis R.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] For power transmission, it would be conceivable for the two elements to have a cross-section 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. Preferably, however, the cross-section is circular, and the power is transmitted, for example, via a welded joint.

[0086] As in Fig. 4 As shown, 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. 2 As can be seen, an upper area 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.

[0087] 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.

[0088] In Fig. 2 In section, the sliding ring 17 can be seen, which runs in the thread 16 of the guide spring 12.

[0089] A larger view of the sliding ring 17 is shown in the Fig. 6 und 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 rotation axis R.

[0090] As in Fig. 6 As shown, 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.

[0091] 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 As can be seen, 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 und Fig. 9 to recognize.

[0092] Fig. 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 As can be seen, a hollow shaft bore 31 is arranged on an upper area 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 shown, be limited at the top and bottom.

[0093] 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).

[0094] 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.

[0095] 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.

[0096] 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, however, 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. According to the invention, the sliding ring or stop body 17, as part of the spindle stopper structure, specifies an upper and a lower end position of the central spindle 8.

[0097] 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.

[0098] 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.

[0099] Figur 9 shows the sliding ring 17 at this lower stop point. As in Fig. 9 As can be seen, 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 17. 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.

[0100] 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.

[0101] 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).

[0102] In the Fig. 10 bis 13 The force transmission mechanism from the spindle 8 to the sleeve element 21 or the valve needle 20 is shown. The central spindle 8 has a stamp-like end portion 22 formed at a lower end of the spindle 8.

[0103] 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 As shown, a compression spring 24 and a force transmission element 23 are also arranged in the receiving area 21a.

[0104] The compression spring 24, which is shown in an enlarged view in Fig. 13 is shown, is in contact with a sleeve bottom 21b of the sleeve element 21. The compression spring 24 is a cylindrical spiral spring, the lower portion of which rests on the sleeve bottom 21b of the sleeve element 21.

[0105] As in Fig. 12 As shown, 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.

[0106] 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.

[0107] As in Fig. 12 As can be seen, 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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. This is advantageous because the valve needle 20 does not rotate for long periods in the valve seat 34.

[0112] 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.

[0113] 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 of the bushing 44 and the spindle 22.

[0114] 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 occurs between the spindle 22 and the bushing 44. This movement occurs briefly on the front side (bush 44) and then only partially on the inner surface of the bushing 44.

[0115] 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.

[0116] 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.

[0117] 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 44 is relatively long in the longitudinal direction (i.e., along the rotation axis R), sufficient material is available that can be removed from it.

[0118] 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 (towards 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.

[0119] As in Fig. 1 As can be seen, 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.

[0120] The valve base body 5 further comprises a receiving area 33 in which (in the assembled state), as shown in Fig. 1 shown, first the hollow shaft 7 is received and within the hollow shaft 7 the sleeve element 21 is received.

[0121] A circumferential undercut 32 is formed in a lower region of the receiving region 33.

[0122] 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.

[0123] A lower seal receiving area 36 is formed on an outer lower area of ​​the valve base body 5. As shown in Fig. 1 As can be seen, 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.

[0124] Back to Fig. 14 - there, in a middle to upper area of ​​the valve base body 5, an upper seal receiving area 37 is formed. As in Fig. 1 As can be seen, in this upper seal receiving area 37, in the installed state, an annular sealing element is also arranged, which in particular seals the fluid inlet space 27 from the outside environment.

[0125] As further stated in the Fig. 14 bis 16 As can be seen, 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 area (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 As shown, 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.

[0126] 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.

[0127] 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 16shown, 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.

[0128] In the assembled state of the expansion valve 1, in this receiving area 33 the Fig. 17 shown hollow shaft 7. The hollow shaft 7 has the second channel region 25b, which extends upwards from a lower end thereof in the form of the longitudinal groove 11.

[0129] 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.

[0130] 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.

[0131] 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 acts 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.

[0132] 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 This figure particularly shows 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.

[0133] 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.

[0134] 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 35 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 can be seen, connected to the fluid inlet chamber 27.

[0135] rerrThe 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.

[0136] In particular, the description describes many individual aspects of the expansion valve 1.

Claims

1. An expansion valve (1) operable by a stepper motor, comprising: a housing (4); a hollow shaft (7) which is arranged in the housing (4); a valve base body (5) which supports the hollow shaft (7) and which closes the housing (4); a rotor (6) which is configured to be driven by means of a stator; a central spindle (8), which is arranged within the hollow shaft (7) and is configured to be driven by the rotor (6) in such a way that a rotational movement of the spindle (8) is convertible into an axial movement for opening and closing the expansion valve (1) via a threaded connection (9); characterized by a spiral body (12) which comprises a thread (16), which is arranged around a lateral surface (10) of the hollow shaft (7) and which is configured to be driven by means of the rotor (6), wherein a stop body is arranged on the hollow shaft (7), said stop body is arranged so as to be movable in the thread (16) of the spiral body (12) and, as part of a spindle-stopper structure, predefines an upper end position and a lower end position of the central spindle (8).

2. The expansion valve (1) according to claim 1, wherein the hollow shaft (7) comprises a longitudinal groove (11) on the lateral surface (10), and wherein the stop body is configured as a sliding ring (17) which 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 so as to be movable in an axial direction.

3. The expansion valve (1) according to claim 2, wherein the spindle-stopper structure is configured by interaction of the spiral body (12) and the sliding ring (17).

4. The expansion valve (1) according to one of claims 2 to 3, wherein the sliding ring (17) comprises an extension (18) extending radially inwards, which is configured to extend in the longitudinal groove (11) and to act there as an anti-rotation means.

5. The expansion valve (1) according to one of the preceding claims, wherein the spiral body (12) comprises a first stop element (14) extending in an axial direction of the spiral body (12) and a second stop element (15) extending in an axial direction of the spiral body (12).

6. The expansion valve (1) according to claim 5, wherein, upon contact of the first stop element (14) with the stop body, the lower end position of the spindle (8) is fixed, and wherein, upon contact of the second stop element (15) with the stop body plus the maximum angle of rotation of the spiral body (12), the upper end position of the spindle (8) is fixed.

7. The expansion valve (1) according to one of claims 2 to 4, and 5 or 6, wherein the sliding ring (17) is configured as a cylindrical spiral and comprises an upper end (17a) and a lower end (17b) opposite the upper end (17a), wherein the upper end (17a) comes into contact with the first stop element (14), and wherein the lower end (17b) comes into contact with the second stop element (15).

8. The expansion valve (1) according to one of claims 5 to 7, wherein the spiral body (12) is connected to an adapter element (13) by means of the first stop element (14) in order to be co-rotated upon rotation of the rotor (6), and wherein the adapter element (13) connects the rotor (6) to the spindle (8) in order to co-rotate the spindle (8) upon rotation of the rotor (6).

9. The expansion valve (1) according to one of the preceding claims, wherein the spiral body (12) is a torsion spring which is configured in the form of a helical spring made of steel.

10. The expansion valve (1) according to one of the preceding claims, wherein the hollow shaft (7) is made of a plastic, preferably of polyphenylene sulfide, PPS, or polyether ether ketone, PEEK, or of brass or bronze.

11. The expansion valve (1) according to one of the preceding claims, wherein the expansion valve (1) further comprises a sleeve element (21) which comprises a receiving region (21a) in which a plunger-like end region (22) of the central spindle (8), a compression spring (24) and a force transmission element (23) are fully accommodated, and a valve needle (20),12. The expansion valve (1) according to claim 11, wherein the force transmission element (23) is configured and arranged in such a way that, upon contact with the central spindle (8), said force transmission element transmits axial forces from the central spindle (8) via the compression spring (24) to the sleeve element (21), wherein the force transmission element (23), when viewed in cross section, is mushroom-shaped in such a way that torques are not transmitted to the force transmission element (23) or are transmitted only to a limited extent from the central spindle (8).

13. The expansion valve (1) according to one of the preceding claims, wherein the housing (4) and a side (5a) of the valve base body (5) facing the housing (4) delimit a housing interior (28), wherein a hollow shaft interior (29) is configured within the hollow shaft (7), wherein a fluid inlet chamber (27) is arranged adjacent to a side (5b) of the valve base body (1) facing away from the housing (4) when the expansion valve (1) is installed in a valve installation chamber (43), wherein a first pressure equalization channel (25) for pressure equalization is arranged between the fluid inlet chamber (27) and the housing interior (28), wherein the first pressure equalization channel (25) comprises a first channel region (25a) and a second channel region (25b), wherein the second channel region (25b) is formed by the longitudinal groove 11.

14. The expansion valve (1) according to claim 13, wherein a second pressure equalization channel (26) for pressure equalization is arranged between the hollow shaft interior (29) and the housing interior (28) in a region of a maximum radial extent of the longitudinal groove (11) and of the hollow shaft interior (29).