Rotary actuator, and beverage filling system

In a rotary actuator comprising a housing containing a piston and having a cover and a base, thread-like guide grooves in the piston, a shaft having a transverse axis and being rotatable about an axis of the rotary actuator which transverse axis engages into the guide grooves, and torque support engaging into guides in the piston, which torque supports are anchored in the housing, wherein the transverse axis on both ends comprises bushes contacting raceways of the guide grooves, each bush is cambered and each raceway is configured with an undercut corresponding to the cambering.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to German Patent Application No. 10 2016 203 873.7, entitled “Rotary Actuator, and Beverage Filling System,” filed on Mar. 9, 2016, the entire contents of which are hereby incorporated by reference for all purposes.

TECHNICAL FIELD

The present disclosure relates to a rotary actuator and a beverage filling system.

BACKGROUND AND SUMMARY

Regarding the rotary actuators known from DE 19950582 C1 and DE 102010002621 A1 for e.g. disk valves in beverage filling systems of this type, the raceways in the guide grooves of the piston are planar and the bushes arranged on the ends of the transverse axis are configured with a cylindrical external circumference. This principle requires positioning the bushes and, if appropriate their bearings on the ends of the transverse axis, for example by means of securing rings or the like so that the bushes during operation of the rotary actuator do not exit e.g. outwardly from the guide grooves. During operation, however, high specific surface pressure occurs between each bush and the raceways of the guide groove. The high surface pressure may result in an early wear. The assembly effort for the required axial securing of the bushes is inappropriate.

The object of the present disclosure is to provide a rotary actuator of the type mentioned in the introductory part, which is characterized by a reduced surface pressure of the bushes and a reduced assembly effort as well as a disk valve with improved operating behavior and a beverage filling system with a reduced maintenance effort.

The cambering and the undercut of the raceway interacting with the cambering increase the contact area between the bush and the raceway, resulting in reduced surface pressure and less wear. Further, during operation, a secure positioning of the bush and an extensive force transfer between large areas occur, which as well has a positive effect on wear and durability. Due to the form-fit between the cambering and the undercut, a separate axial securing of the bushes is omitted, which considerably reduces the assembly effort.

The beverage filling system in relation to the disk valve with this rotary actuator, among other things requires low maintenance.

Regarding an appropriate embodiment, the bush is either double-conically or convexly, and in at least one example, spherically cambered, and the undercut of the raceways either runs double-conically or concavely curved, and in some examples, following a circular arc section. This geometric configuration is simple in terms of manufacturing, contributes to the optimum reduction of the surface pressure and to the reliable axial guidance of the bush.

Regarding an appropriate embodiment, the bush, may via a roller bearing or plain bearing, only be loosely fitted to the end of the transverse axis, e.g. up to a transverse axis shoulder. The bush is axially positioned on the end by form-fitting between the cambering and at least one raceway undercut, without additional aids or assembly steps during the assembly of the rotary actuator.

The track roller with pressed-in plain bearing only needs to be fitted on the transverse axis, which causes less assembly effort.

Particularly appropriate, approximately in the middle between both guide groove ends, each guide groove may have a bush assembly opening, which is at least accessible from the outer circumference of the piston. The assembly opening is usable in order to mount at least the bush on the end of the transverse axis or to replace it rapidly in the event of wear, without having to manipulate tools or securing elements. Thereby, the assembly opening is practically placed approximately in the middle between the two guide grooves, thus, in a region of the guide grooves, in which due to the course of the guide grooves the torque to be transmitted is relatively moderate so that there, the problem of the surface pressure between the raceway and the bush is non-critical, although there the contact area in the raceway somewhat decreases.

The assembly opening is appropriately configured in such a manner that one side of the undercut is removed arcuately in each raceway up to approximately the base of the undercut and corresponding to the contour of the outer circumference of the bush. The temporary lateral interruption of the undercut of the raceway at this point, approximately in the middle between the guide groove ends, has no negative effect on the functionality, since the bushes are moved through this area under relatively moderate load and cannot drop out.

The piston may be appropriately a plastic molded part, and in at least on example, an injection molded part, for example of reinforced polyoxymethylene. This plastic is only an example of a plurality of possibilities and in addition to high wear resistance, offers favorable friction conditions.

In a symmetrical configuration of the rotary actuator, for example, the effective distance of the torque supports from the axis is enlarged for receiving the torques generated by the cambered bushes and the undercut raceways by an approximately rectangular outer cross section of the torque supports with longer rectangular sides, which are approximately tangential to the axis, by parallel shorter rectangular sides, and by guides open to the outer circumference of the piston. The rectangular outer cross-section increases the bending resistance modulus in the direction tangential to the axis, strengthens the anchorage area of the torque support, and increases in interaction with the open guide in the outer circumference of the piston the effective distance to the axis, by means of which distance the torques are received and removed, which are transferred, for example in case of an axis-symmetrical configuration of the rotary actuator, having two bushes, from the cambered bushes and the undercut raceways into the piston.

The torque support, if appropriate, could be fixed at the inner wall of the housing, namely either only there or also on the cover and/or base of the housing. Furthermore, in a different embodiment of the rotary actuator, a single torque support and/or only one bush engaging the guide groove on the transverse axis could be sufficient.

DETAILED DESCRIPTION

As non-limiting example,FIG. 1shows a disk valve V with a closing element G, shown in dashed lines, and which is rotatable back and forth about an axis X, and which can be actuated by means of a rotary actuator D over a pivot angle of, for example, approximately 90° between an open and a closed position. The disk valve V is, for example, installed in a beverage filling system (not shown).

The rotary actuator D is mounted with a foot part5on the disk valve V and comprises a housing4, here for example cylindrical, with a cover1and a base3. The rotary actuator D here is for example pneumatically actuated via a connection port2in the cover1, for example against a spring, which is not shown inFIG. 1, or electromagnetically actuated by a linear drive, which is not shown (for example even in both actuation directions). In the longitudinal section view inFIG. 2, a shaft6is rotatable in the base3about the axis X, which extends upwardly into the rotary actuator D and which comprises at the lower end a coupling part7for connecting to the closing element G of the disk valve V.

In the upper end of the shaft6, a transverse axis8, which is perpendicular to the axis X, and engages here with both its ends24(FIG. 3) into diametrically opposite thread-like guide grooves9in a skirt16of a piston10, which is configured here as a piston tube. The piston10is sealed but slidable in the housing4, and is loaded by a spring11. The piston10is pressurized or discharged through the connection port2by pressurized medium, for example compressed air, and is, thus, shifted back and forth in the direction of the axis X, whereby the transverse axis8applies a rotational movement to the shaft6via the guide grooves9. In order to be able to generate this rotational movement, the piston10must be supported against rotation in the housing4and thereby occurring torques must be absorbed.

The anti-rotation support of the piston10in the shown embodiment is achieved by two torque supports12, which extend from the anchoring points13, here, for example, on the base3, upwardly into guides15of the piston apron16(i.e., piston skirt) and support the piston10against rotation or transfer torques arising from the movement of the transverse axis8in the guide grooves9into the base3, which is fixedly connected to the disk valve V via the foot part5. Free ends14of the torque supports12extend upwardly up to the position of the transverse axis8. Alternatively, one torque support12could be fixed to the base3and the other torque support12to the cover1, whereby, the free ends14of the torque support12may then overlap at the height position of the transverse axis8. In a further alternative, the torque supports12could be fixed only to the cover1, or more than two axially parallel torque supports12and guides15could be provided. Furthermore, the respective torque support12could be additionally or exclusively fixed to the inner wall of the housing4.

In the side view of the rotary actuator D inFIG. 3, for clarity purposes, the housing4is omitted, in order to clarify the interaction between the torque supports12and the guides15, as well as the ends24of the transverse axis8and the guide grooves9. Each torque support may be a type of a guide bar or a guide web.

With regard to the torques or reaction forces from the torques to be transmitted, each torque support12is load-specifically configured and has an optimally high bending modulus in the effective direction of the torques and may provide a great effective distance from the axis X, which reduces component loads. In detail, the torque support12has an approximately rectangular outer cross-section with longer rectangle sides28lying tangentially to the axis X and planar, shorter rectangle sides29which are substantially perpendicular to the longer rectangle sides. The length ratio between the longer rectangle sides28and the shorter rectangle sides29may amount approximately to 2:1. In the shown embodiment, additionally, the longer rectangle sides28of the outer cross-section are cambered (30) or convexly rounded (alternatively double-conically) in order to further increase the bending modulus. Between the longer rectangle side28pointing to the axis X and a groove base33of the guide15, an intermediate distance31can be provided in order to minimize the extent of the contact areas, which are in frictional contact during the torque transmission.

The torque support12and the base3or the torque support12and the cover1are configured unitarily, for example as castings.

FIGS. 2, 3, and 4in conjunction withFIGS. 5 and 6illustrate the interaction between the transverse axis8and the thread-like guide grooves9in the piston10. The piston10may be a plastic molded part, for example an injection-molded part of reinforced polyoxymethylene.

Each guide groove9forms two opposing raceways17and18for a bush26, which is rotatably arranged on the end24of the transverse axis8. Each bush26is mounted on the end24with a bearing25(shown as a plain bearing, or a roller bearing, such as a needle bearing), wherein the bearing25may be fixed non-rotatably on the end24. The bearings25shown inFIG. 4extend up to shoulders35between the ends24and the middle part of the transverse axis8and in this region comprise ring flanges36, which project outwardly, whereFIG. 4shows a sectional view of the section plane IV-IV ofFIG. 3. The bush26is pushed loosely onto the bearing25in the axial direction of the transverse axis8and is axially positioned in the working position by form-fitting between a cambering34of the bush26and an undercut19,20of the raceways17,18of the guide grooves9, without having to mount additional machine elements for this purpose.

The cambering34of the bushes26in the embodiment shown is spherical, but may be double-conical (not shown). Consistent with the cambering, the undercut19,20of the raceways17,18is either concavely curved following a circular arc section or is double-conical (not shown).

In order to be able to push the bushes26onto the ends24during the assembly of the rotary actuator D, in each guide groove9in the region of the bush assembly opening21, the sides of the undercut19,20running to the outside of the piston skirt16are removed arcuately at removals22,23, for this purpose approximately in the middle between the guide groove ends, i.e. in a region, in which torques to be transmitted are a minimum. The removals22,23are shaped correspondingly to the outer circumference of the bushes26. Alternatively, the bushes26may be preassembled with the bearings25and, if appropriate, then pushed or pressed on. During operation of the rotary actuator, the removals22,23are not critical, since this area is quickly passed over by the bushes26without a risk of slipping, e.g. outwardly.

The configuration of the bush assembly opening21is indicated inFIGS. 5 and 6. Each removal23,22extends approximately to half the depth of each undercut19,20and runs essentially without transition into the deepest region or bottom of the undercut19,20. According toFIG. 6, the removal22,23is designed corresponding to the circular outer circumference of the bush26. Optionally, the removals22,23of both guide grooves9are diametrically opposite in relation to the axis X in order to be able to mount both bushes26(with or without bearing25) in the same position of the piston10(optionally). The bushes26may be made of plastic or a metal or an alloy, for example with sliding and rolling characteristics corresponding to the plastic material of the piston10.

The load-specific configuration of the outer cross-section of the torque support12and the corresponding guides15increase the precision of the interaction, minimize the surface pressure and ensure a stable transmission of torques into the base3(or the cover1). The form-fit between the cambering34and the undercuts19,20, which positions the bushes axially on the transverse axis8, offers the advantage of a reduced surface pressure, since the contacting surfaces are enlarged, and which facilitates the assembly by omitting machine elements for the axial securing of the bushes26(with or without the bearings25).

Further, not shown embodiments of the rotary actuator D as part of disk valves V are appropriate, which only provide one torque support12and one guide15in the piston10and/or only one guide groove9in the piston with only one bush26on the transverse axis. If the piston10is actuated in both directions, for example by an electromagnetic linear drive (spring11is omitted), the effective distance of the torque support12from the axis X may even be further enlarged by anchoring the torque support12in the housing4or the outer dimension of the rotary actuator D showing equal capabilities may be reduced.

The disk valve V equipped with the rotary actuator D as well is part of the present disclosure and shows an improved operating behavior and is easy to mount. In a beverage filling system, the disk valve requires low maintenance.

Further,FIGS. 1-6show the relative positioning of various components of the receiver assembly. If shown directly contacting each other, or directly coupled, then such components may be referred to as directly contacting or directly coupled, respectively, at least in one example. Similarly, components shown contiguous or adjacent to one another may be contiguous or adjacent to each other, respectively, at least in one example. As an example, components lying in face-sharing contact with each other may be referred to as in face-sharing contact or physically contacting one another. As another example, elements positioned apart from each other with only a space there-between and no other components may be referred to as such, in at least one example.

As yet another example, elements shown above/below one another, at opposite sides to one another, or to the left/right of one another may be referred to as such, relative to one another. Further, as shown in the figures, a topmost element or point of element may be referred to as a “top” of the component and a bottommost element or point of the element may be referred to as a “bottom” of the component, in at least one example. As used herein, top/bottom, upper/lower, above/below, may be relative to a vertical axis of the figures and used to describe positioning of elements of the figures relative to one another. As such, elements shown above other elements are positioned vertically above the other elements, in one example. As yet another example, shapes of the elements depicted within the figures may be referred to as having those shapes (e.g., such as being circular, straight, planar, curved, rounded, chamfered, angled, or the like). Further, elements shown intersecting one another may be referred to as intersecting elements or intersecting one another, in at least one example. Further still, an element shown within another element or shown outside of another element may be referred as such, in one example.