Shaft passage and valve having such a shaft passage and method for the production of a shaft passage

The invention relates to a shaft passage and a valve having such a shaft passage, as well as a method for producing a shaft passage, in which the shaft (21) has at least one drive portion (24) to which a drive for controlling the shaft (21) can be connected and has a connecting portion (25) opposite the drive portion (24), to which an actuating member (64) can be connected, and an inner shaft portion (26) in the through-bore (22) extending at least partially in the through bore (22), and having an inner shaft seal (36) to which an operating pressure of a medium to be controlled by the actuating member (64) is applied, and having a fluid shaft seal (34) which extends in the direction of the drive portion (24), and which is arranged between the inner shaft seal (34) and the outer shaft seal (42), wherein the fluid shaft seal (34) is formed between the through bore (22) and the inner shaft portion (26) of the shaft (21) and is pressure-relieved against an operating pressure of the medium to be controlled.

This application claims priority of German Patent Application No. 10 2017 102 842.0 filed Feb. 13, 2017, which is hereby incorporated herein by reference.

The invention relates to a shaft passage consisting of a housing having a through bore and a shaft which is rotatably mounted in the through bore, as well as a valve having such a shaft passage for controlling an actuating member, in particular valve closure member, and a method for the production of such a shaft passage.

A shaft passage for controlling a ball valve is known from DE 10 2012 111 467 A1. A shaft for transmitting an actuating movement to the ball valve is driven in rotation by means of a drive, said shaft being mounted in a shaft bearing and penetrating this valve. The shaft has a connecting element on the opposite end of the drive, by which a ball valve is opened and closed by a rotational movement. The shaft is sealed in the shaft housing by an inner and outer or lower and upper shaft seal. A fluid shaft seal is provided therebetween which is supplied with an oil reservoir via transverse bores which are directed radially outwards, said reservoir being bordered by a separate sealing membrane outside the shaft housing. This sealing membrane communicates with a chamber in which the ball valve is arranged, such that this sealing membrane is acted upon by the system pressure of the fluid flowing through the ball valve.

Such an arrangement has the disadvantage that the oil reservoir in the sealing membrane expands during thermal exposure and the sealing membrane is additionally acted upon by the system pressure of the fluid flowing through the ball valve, such that this outer shaft seal of the shaft passage must be designed for sealing the shaft passage and at most cannot seal sufficiently securely.

The object of the invention is to create a shaft passage and a valve having a shaft passage and a method for producing a shaft passage which enables a good seal tightness under pressure, in particular for refrigerant, and preferably requires a relatively low torque to move the shaft.

This object is solved by a shaft passage in which the shaft is rotatably mounted in a through bore of the housing and has an inner and outer shaft seal as well as a fluid shaft seal therebetween, wherein the fluid shaft seal is formed in a region between the through bore of the housing and an inner shaft portion of the shaft and the fluid shaft sealing is depressurised compared with an operating pressure of the medium to be controlled. Only the inner or lower shaft seal, which is assigned, for example, to a regulating chamber or a pressure chamber of a medium to be controlled, is acted upon by the pressure of the medium flowing through or to be controlled. The fluid shaft seal itself, however, is arranged separately to the operating pressure of the medium to be controlled behind the inner shaft seal or opposite the side of the inner shaft seal which is acted upon by the fluid pressure, so that an additional compression load of the fluid to be controlled does not act on the fluid shaft seal. The through bore is preferably formed continuously—i.e. without interruption—in the region of the fluid shaft seal. The outer or upper shaft seal thus acts as a type of replacement seal for the lower or inner shaft seal. Good seal tightness on the one hand and a well-lubricated mounting of the shaft in the through bore on the other hand can thus be achieved.

A preferred embodiment of the shaft passage provides that the fluid seal is limited relative to the operating pressure of the medium to be controlled in the axial direction by the inner and outer shaft seal and in the radial direction by the shaft portion of the shaft and the through bore, in particular the inner wall of the through bore. The inner shaft seal, the fluid shaft seal and the outer shaft seal are thus connected in series, so that exclusively the inner shaft seal absorbs the operating pressure of the medium to be controlled.

At least one axial and/or radial bearing is provided for mounting of the shaft in the through bore, which is arranged adjacent to the fluid shaft seal or adjoins the fluid shaft seal. This has the advantage that the axial and/or radial bearing is lubricated simultaneously by the fluid in the fluid shaft seal, in particular oil, such as refrigerator oil or compressor oil.

Furthermore, at least one annular gap having a constant gap width for forming the fluid shaft seal is preferably formed within the inner shaft portion of the shaft. An additional radial mounting of the shaft in the through bore can thus be supported.

Furthermore, the inner shaft seal is preferably secured pointing in the axial direction relative to the medium to be controlled by at least one inner bearing or a support disc or an inner shoulder of the housing. A simple construction can thus be created, wherein a first pressure drop in the operating pressure of the medium to be controlled is enabled by the inner bearing, the support disc or the shoulder of the housing.

Furthermore, the inner bearing arranged relative to the inner shaft seal and/or the inner support disc are preferably fixedly arranged on the shaft. This enables a simple assembly of the shaft in the through bore.

In a first embodiment of the shaft passage, a bearing is preferably provided on an inner and outer end of the fluid shaft seal respectively, which preferably adjoins the fluid shaft seal directly. The bearings can thus be directly moistened with the fluid and the shaft seals arranged respectively outside the bearing can preferably enable an axial sealing inwardly and outwardly towards the housing.

Furthermore, a compensating chamber opposite the fluid shaft seal is preferably assigned respectively to one of the two bearings or to both bearings which border the fluid shaft seal or are arranged on the fluid shaft seal. This compensation chamber is formed by an annular gap which is preferably filled with a compressible fluid, in particular air. The fluid expanding during thermal exposure can pass into this annular gap and form volume compensation.

Furthermore, the first embodiment advantageously has at least one support disc which is assigned to the inner and/or outer shaft seal and the inner and/or outer shaft seal and the respective support disc is displaceably bordered in the axial direction between the bearing adjoining the fluid shaft seal and a further bearing or a housing portion of the housing. This displaceability of the inner and/or outer shaft seal and the respectively assigned support disc relative to the fluid shaft seal has the advantage that, during thermal exposure from the outside and an expansion of the fluid in the gap of the fluid shaft seal, a compensation can be created by the support disc being axially moveable with the outer shaft seal. Overpressure in the annular gap of the fluid shaft seal can thus be prevented. By the assignment of the support disc to the shaft seal, a secured travelling movement of the shaft seal along the shaft portion of the shaft is enabled.

According to a further alternative embodiment of the invention, an axial and/or radial bearing is arranged on an inner end of the inwardly directed shaft portion of the shaft, said bearing interacting with a housing portion in the through bore as a guide for the inner shaft seal and with at least one support disc. This enables a simple assembly and a compact construction.

A support disc and an inner shaft seal, as well as preferably a free annular gap, are preferably provided in the through bore between the axial and/or radial bearing and a shoulder bordering the guide, and the support disc and the inner shaft seal are displaceably mounted. This in turn enables a compensation volume to be created in the fluid shaft seal in the event of thermal expansion of the fluid. Additionally, by limiting the axial displaceability of the inner shaft seal towards the outer shaft seal by the shoulder in the through bore, it can in turn be ensured that an operating pressure acting on the inner seal is not transmitted to the outer shaft seal, rather this operating pressure is kept away from the outer shaft seal.

A further preferred embodiment of this second alternative embodiment provides the fluid shaft seal between the housing portion in the through bore and an outer stopper arranged on the through bore of the housing, said fluid shaft seal being bordered outwardly by the outer shaft seal and a further outer support disc, wherein a free annular gap for a compensation chamber is formed in particular between the outer support disc and/or the outer shaft seal on one hand and the stopper on the other hand. Firstly, the closed chamber for the fluid shaft seal can thus in turn be formed, which is arranged separately from the operating pressure of the medium to be controlled. Furthermore, an in particular second free annular gap can additionally be created, in order to enable a compensating volume during thermal heating of the medium of the fluid shaft seal.

In this second alternative embodiment it is thus preferably provided that the outer shaft seal adjoining the fluid shaft seal and the support disc assigned to the outer shaft seal are displaceable in the axial direction and their displaceability is limited by the housing portion or the adjoining fluid and an outer stopper.

A further alternative embodiment of the shaft passage advantageously provides that a fluid shaft seal is created between the inner and outer shaft seal, in which the full volume of the fluid is lower than the volume of the chamber which is formed between the inner and outer shaft seal and the through bore of the shaft. A compensation volume is thus provided within the two shaft seals. Preferably, a radial and/or axial bearing is provided outside the inner and outer shaft seal respectively. The internal shaft seals can thus be secured in the axial direction.

Furthermore, the first and second shaft seal are preferably formed as an O-ring seal, an X-ring seal or as a groove ring seal. The X-ring seal in particular has the advantage that two seals connected in series are effectively created, by means of which good seal tightness is achieved.

An assembly portion is preferably provided on the housing of the shaft passage, which comprises at least one sealing element. The interface between the shaft passage and the actuating member to be controlled by the shaft, said member being in turn arranged in a housing, can thus be sealed.

Furthermore, the fluid shaft seal preferably has a ratio of a length to a width of the annular gap in a range of 25:1 to 1:1. Additional friction minimisation, in particular for very long and narrow gaps for the fluid shaft seal, can be achieved with a simultaneously rotating drive of the shaft in the shaft passage. The mounting can also simultaneously be improved.

The object of the invention is further solved by a valve, in particular for a cooling system, which comprises a housing having an inlet opening and an outlet opening, which are connected to one another by a canal which comprises a flow opening and is in communication with a regulating chamber or pressure chamber. The through-opening can be controlled by an actuating member or a valve closure member, wherein an activating device is provided, by means of which the valve closure member can be driven into an open and closed position relative to a valve seat which is provided in the through-opening. This activating device comprises at least one valve passage according to one of the embodiments described above, which can be disposed on the housing of the valve, wherein the valve closure member is arranged on the connecting portion of the shaft from the shaft passage. An opening and closing movement of the valve closure member can thus be controlled by the shaft and the connection point in the housing for receiving the shaft passage can simultaneously be sealed. An operating pressure of the medium to be controlled is applied to this connection point.

The activating device preferably comprises a drive which engages the drive portion of the shaft. This drive is arranged outside the valve and preferably also outside the shaft passage, whereby a simple accessibility and construction independent of the medium or fluid to be controlled, in particular refrigerant, is possible.

Furthermore, the valve closure member is preferably guided with axial displacement and with rotation prevention in a pressure chamber which is in communication with the through bore. A rotating drive of the shaft can thus be converted to an axial movement component along the longitudinal axis of the shaft for opening and closing the valve closure member. The valve closure member is preferably provided by means of a thread on the connection portion of the shaft.

A further advantageous embodiment of the valve provides that the valve closure member can be disposed on the high pressure side or the low pressure side relative to the through bore and can be controlled with the shaft passage according to one of the preceding claims. This shaft guide can be assigned to either a high pressure side or a low pressure side pressure chamber in order to enable a corresponding control of the valve.

The object of the invention is further solved by a method for producing a shaft passage, in particular according to one of the preceding embodiments of the shaft passage, which comprises a shaft which is rotatably mounted in a through-bore in the housing, and comprises at least one inner and outer shaft seal and a fluid shaft seal which is arranged therebetween, in which an inner shaft seal is inserted into the through bore or an inner shaft seal is applied to the shaft, in which the shaft is introduced into the through bore of the housing, such that the inner shaft seal is positioned between the housing and the shaft, in which an annular gap which is formed between the through bore and the shaft portion and which is defined by the inner shaft seal is filled with a predetermined volume of fluid, in which the annular gap filled with fluid is subsequently closed by an outer shaft seal acting between the through bore and the shaft portion and the shaft is moved into an end position within the housing. This sequence of work steps has the advantage of enabling a quick filling of the chamber of the fluid shaft seal with a fluid as well as a secure assembly.

A further preferred embodiment of the method provides that, before the insertion of the shaft into the through bore, the inner shaft seal, preferably a support portion and an inner bearing are applied to the shaft or inserted into the through bore, and after the filling of the annular gap, the outer bearing is applied to the shaft and, according to a first alternative, the shaft is pushed into an end position, in order to subsequently introduce the outer shaft seal to at least one support disc assigned to this shaft seal, an axial bearing and preferably a stop ring. The second alternative provides that the outer shaft seal, preferably at least one support disc and an axial bearing, as well as preferably a stop ring, are applied to the shaft after the filling of the annular gap or even before the filling of the annular gap, though only when the positioning of the shaft for filling has been carried out, and the shaft is filled and finally pushed into the end position.

A further alternative embodiment of the method provides that the shaft is fully pre-assembled and afterwards inserted into the through bore. Here the pre-assembled shaft is at least equipped with an inner and outer bearing which adjoin the fluid seal. Furthermore, at least one inner and outer shaft seal as well as preferably at least one support disc assigned respectively to this inner and outer seal are preferably applied. Furthermore, an axial bearing ring and preferably a stop ring are applied in the direction of the drive portion after the application of the outer shaft seal and the support ring, which preferably fixes the axial bearing ring in the position relative to the shaft.

Provided that the pre-assembled shaft is inserted into the through bore according to this embodiment, the fluid can be introduced into the annular gap before the outer bearing on the shaft is introduced into the through bore and closes the annular gap between the shaft portion and the through bore. Alternatively, it can be provided that, with a pre-assembled shaft, this is fully inserted into the through bore until it reaches its end position, so that the annular gap is subsequently filled with fluid via a cross bore in the housing and after the filling this cross bore is closed. This can be take place, for example, by compression by means of a stopper, a ball or the like.

A further advantageous embodiment of the method provides that at least one axial and/or radial bearing is applied to the stop portion on to the shaft portion facing the stop portion before the transfer of the shaft into the end position. Such an arrangement has the advantage that the length of the mounting can be formed to be shorter and nevertheless enables a simplified assembly.

Furthermore, at least one free annular gap is formed in the axial direction between the shaft portion of the shaft and the through bore as a compensation volume or compensation chamber. This enables the expanding fluid to be able to be collected in the compensation chamber during thermal exposure without additional forces on the inner and outer shaft seal being generated, whereby an increased torque would be required during the control of the shaft.

Furthermore, after the shaft assumes the end position, a stopper is introduced or pressed into the through bore of the housing. A further axial securing of the shaft to the housing can thus take place or of the components applied to the shaft can be enabled.

A further alternative embodiment of the method provides that, after the filling of the annular gap with a fluid, the outer shaft seal is positioned relative to the inner shaft seal in such a way that a free annular gap is formed between the fluid provided in the annular gap and the outer shaft seal. A compensation volume between two seals can thus be created in a simple manner.

InFIG. 1, a schematic side view of a shaft passage11is depicted.FIG. 2shows a schematic sectional view of the shaft passage11according toFIG. 1.

The shaft passage11comprises a housing12, which comprises, for example, an assembly portion14which is provided for connection to a further component such as, for example, a valve15according toFIGS. 3 to 5. This assembly portion14can have one or several grooves16for receiving sealing elements53. Furthermore, the housing12has a tubular body18, which can have various cross-sections. For example, a flange portion19with increased diameter is provided, to which, for example, a drive54(FIG. 3) can be fastened. This flange portion19can likewise have an auxiliary bore20or similar for assembly of the shaft passage11.

The shaft passage11has a shaft21which is rotatably mounted in a through bore22of the housing12. The shaft21advantageously extends fully through the housing12and has an upwardly protruding or outer drive portion24. Opposite, a connecting portion25is provided, which protrudes inwards relative to the housing12or protrudes downwardly. A shaft portion26is formed therebetween which extends in the region of the through bore22. The rotatable bearing of the shaft21as well as its sealing inwards or downwards in the axial direction along the longitudinal axis23and upwards or outwards is described in detail below.

When specifying the direction, “inwards” or “inner” should be understood to mean that the connecting portion25is arranged in a housing51of a further component such as, for example, a valve15, by which a mass flow of a pressurised medium is to be controlled. When specifying “outwards” or “outer”, this means the direction in which the drive portion24of the shaft21is provided or an ambient pressure acts.

The housing12preferably has a stepped through bore22, wherein the through bore22is bordered in the direction towards the connecting portion25of the shaft21by an inner shoulder27protruding radially inwards.

The shaft21is guided by two bearings28,29within the through bore22. These bearings28,29can be formed as axial and/or radial bearings. These two bearings28,29each engage a shoulder31on an inner shaft portion26of the shaft21. An annular gap33is formed therebetween. This annular gap33is filled with a medium, in particular oil. A fluid shaft seal34is thus formed. An inner shaft seal36and preferably a support disc37or support ring are joined to the inner bearing29in the direction of the connecting portion25. In addition, a further support disc37can also be arranged between the inner shaft seal36and the bearing29. At least the support disc37and the inner shaft seal36are axially displaceably mounted. A compensation chamber39in the form of a gap can be formed between the support disc37and the shoulder27of the housing12.

During thermal heating of the fluid in the fluid shaft seal34, the fluid can pass the bearing29at least partially, and act in the direction of the inner shaft seal36. An overpressure in the fluid shaft seal34which can act disadvantageously on the friction between the inner shaft seal36and the shaft21or the through bore22can be prevented by the displaceable arrangement of the inner shaft seal36in the direction of the compensation chamber39.

An analogous construction to the bearing29is provided to the outer bearing28in the direction of the drive portion24. An outer shaft seal42and an adjoining further support disc43are preferably provided. In the axial direction as seen outwardly, an operating chamber39can in turn be provided.

In this embodiment of the shaft passage11, a further radial and/or axial bearing45, in particular an axial bearing45, is furthermore advantageously provided. This abuts a shoulder46of the shaft21. The size of the operating chamber39can be determined by the axial distance of the shoulder46on the shaft portion26of the shaft21from the shoulder31or the components arranged therebetween. In addition, another stop ring44can be provided between a stopper47and the bearing45. The axial bearing25can be fixed by the stopper47in a defined position within the through bore22by means of the stop ring44. The stopper47is preferably pressed into the through bore22.

The connecting portion25of the shaft21can be formed, for example, as a thread. The drive portion24can be formed, for example, as a polygon or square or comprise further connection or coupling elements.

A closed chamber is formed together with the through bore22by the fixed positioning of the bearing28,29relative to the respective shoulder31of the shaft21, in order to form the fluid shaft seal34. A pressure applied to an inner side of the housing12or to an inner side of the through bore22is received exclusively by the inner shaft seal36, which is braced against the bearing29. The fluid shaft seal34is pressure-relieved against this pressure which is applied. The outer shaft seal42can thus serve as a so-called replacement seal and assume a safety function.

InFIG. 3, a schematic side view of the shaft passage11according toFIGS. 1 and 2is depicted, which is fastened with the assembly portion14to a housing51of the valve15. A flange plate52, for example, is provided for this purpose, for which the assembly portion14is arranged in a corresponding portion of the housing51. Sealing elements53, in particular sealing rings, are received by the grooves16in order to seal these connection interfaces.

FIG. 4shows a schematic sectional view of the valve15having the shaft passage11and an actuating member arranged thereon or valve closure member64in a closed position55.FIG. 5shows the valve15having the shaft passage11in an open position56.

The valve15has an inlet opening58and an outlet opening59in the housing51, which are connected to each other by a channel61. A filter60can preferably be provided in the inlet opening58and/or in the outlet opening59. This comprises a through-flow opening62, which is enclosed by a valve seat63. A valve closure member64abuts this valve seat63in the closed position55. The valve closure member64is received via a fastening sleeve66, which has a thread opposite this member, said thread engaging a thread formed as connecting portion25. The fastening sleeve66is displaceably guided in a pressure chamber67which communicates with the through-opening62along a longitudinal axis which preferably corresponds to the longitudinal axis of the shaft21. The fastening sleeve66is simultaneously non-rotatably received in the pressure chamber67. A return spring68acts on the fastening sleeve66, said return spring supporting an opening movement of the valve closure member64and acting in the direction of the shaft passage11.

An activating device50is provided for activating the valve15from the closed position55according toFIG. 4into the open position56according toFIG. 5. This comprises, for example, the shaft passage opening11as well as a drive54. This drive54can be formed as an electric drive, in particular an electric motor or a drive which is otherwise controlled. A rotational movement of the shaft21around the longitudinal axis23is controlled by the drive54. Due to this rotational movement, the fastening sleeve66is moved in the direction of the shaft passage11, because the anti-rotation means prevents the fastening sleeve66from rotating, such that a clean axial movement is produced and the valve closure member64is lifted from the valve seat63and opens the through-opening62.

In the opening position56of the valve15, the high pressure of a medium to be controlled, in particular a refrigerant, acting on the inlet opening58abuts an inner side of the shaft passage11. This high pressure of the medium acts on the support surface27and afterwards on the inner shaft seal36. The fluid shaft34is not directly subjected to the pressure of the medium to be controlled which is applied in the valve15.

In an alternative embodiment, not depicted in more detail, of the valve15having the shaft passage11, the valve closure member64and the control via the shaft passage11can be provided on the low pressure side, i.e. the valve closure member64is arranged within the outlet opening59and opens and closes the through-opening62.

The valve15according toFIGS. 4 and 5can also be flowed through in the opposite direction, i.e. the medium to be controlled flows from the outlet opening59to the inlet opening58.

InFIG. 6a schematic side view and inFIG. 7a schematic sectional view of the shaft passage11according toFIG. 6along the line VII-VII are depicted. This alternative embodiment differs from the embodiment described above in that the housing12has a tubular body18which is shortened compared toFIG. 1.

In this embodiment, the shaft21can have, for example, a continuously cylindrical outer periphery over the entire length. The through bore22in the housing12comprises a housing portion71in the form of a constriction of the through bore22. On an inner portion of the through bore22, an axial and radial bearing72is provided on the shaft21, which is secured in the axial direction by the one axial securing means73that engages the shaft21directly. Between the axial and radial bearing72and the housing portion71, a support disc37as well as an inner shaft seal36are provided in the through bore22. Outside the housing portion71, the annular gap33is provided for forming the fluid shaft seal34. The annular gap33is in turn bordered by a support disc37and an outer shaft seal42.

The outer shaft seal42and the adjacent support disc43are in turn axially secured by the stopper47in the through bore22.

In this embodiment, an operating chamber39can be formed adjacent to the inner shaft seal36and/or outer shaft seal42, said operating chamber having the same function as in the shaft passage11according toFIGS. 1 and 2.

InFIG. 8, a further schematic side view of the shaft passage11toFIG. 1is depicted.FIG. 9shows a schematic sectional view along the line IX-IX inFIG. 8.

In this embodiment, a simplified structure is provided. The annular gap33is formed between the shaft21and the through bore22, said annular gap being bordered by an inner shaft seal36and an outer shaft seal42.

In this embodiment, the amount of fluid introduced into the annular gap33for forming the fluid shaft seal34is lower than the total volume which is enclosed by the shaft seals36,42, such that a compensation chamber39for the fluid of the fluid shaft seal34is simultaneously also provided within the annular gap33during thermal expansion. The bearing28,29is provided outside the inner shaft seal36and the outer shaft seal42respectively. The inner shaft seal36and the outer shaft seal42bear respectively against this if an increased pressure in the fluid shaft seal34should arise. The inner and/or outer shaft seal36,42are preferably axially displaceable. One or both shaft seals36,42can also be secured axially with respect to the shaft21.

The inner and outer shaft seal36,42is preferably formed as a groove ring in this embodiment.

InFIGS. 10ato 10d, schematic sectional views of individual steps for the production of the shaft passage11according to the embodiments ofFIGS. 6 and 7are depicted.

FIG. 10ashows a first step. First, the inner shaft seal36and preferably the support disc37are inserted into the inner portion of the through bore22, or the inner shaft seal36and preferably the support disc37are applied to the shaft portion26of the shaft21. The shaft21is subsequently inserted into the through bore22and is introduced until a drive portion24is positioned above the housing portion71but still within the through bore22. A filling of the remaining annular gap33between the through bore22and the shaft21with a fluid then takes place.

In a subsequent step according toFIG. 10b, the outer shaft seal42and the support disc43are inserted and are axially secured by means of the stopper47in the through bore22.

Subsequently, in a further step according toFIG. 10c, the shaft21is first pushed further in the direction of the stopper47until an end face of the shaft21is flush with the support disc43. The region E is subsequently cleaned by the medium which is introduced for the fluid shaft seal34. The axial and radial bearing72is subsequently assembled on the opposite connecting portion25and is secured on the shaft21by the axial securing means73. Finally, the shaft21is guided further through the through bore22until the axial and radial bearing72engages the through bore22and is fixed in particular on the inner portion of the through bore22.

By the selection of the length of the axial and radial mounting72or the corresponding matching portion of the through bore22or the shaft portion26, the size of the compensation chamber39adjacent to the inner shaft seal36can be determined.