Positioning device and a method for producing the positioning device

A positioning device for mechanically actuating a component may include a housing with first and second housing parts welded to one another via an axial welded connection. The first and second housing parts may have integrally formed first and second bearing points, respectively, of a bearing within the housing. The positioning device may also include a gearing fixed in the housing, the gearing having an output shaft penetrating the second housing part and being drive-connectable with the component outside the housing, and an output wheel non-rotationally fixed on the output shaft and rotatably mounted in the bearing. The positioning device may further include a rotary position detector with a permanent magnet and a Hall sensor, the permanent magnet being arranged on a gear wheel of the output shaft or on the output shaft at an end face of the output shaft, and the Hall sensor being arranged on the first housing part. End faces of the first and second bearing points may interact axially with first and second bearing surfaces, respectively, of the output wheel located opposite each other. The bearing may have a predetermined axial play defined by a difference between an outer axial distance between the first and second bearing points and an inner axial distance between the first and second bearing surfaces.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to German Patent Application No. DE102018210130.2, filed Jun. 21, 2018, which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The invention relates to a positioning device for mechanically actuating a component and to a method for producing a positioning device.

SUMMARY

A positioning device usually comprises an output shaft and an output wheel of a gearing that is rotatably fixed on the output shaft. Here, the output shaft is rotatably mounted so that the output shaft is rotatably driveable by way of the gearing. The gearing, the output shaft and the output wheel are arranged in a housing, wherein the output shaft penetrates the housing and is drive connectable to a component outside the housing.

Here, the bearing has an axial play which is decisive for the functioning of the positioning device. In particular, various expansions of the individual constituent parts of the positioning device as a consequence of deviating heat expansion coefficients or temperature differences can be offset by the axial play and a jamming of the output wheel in the bearing prevented. Here, the axial play is determined by the distance by which the output shaft is freely shiftable axially in the bearing.

In order to be able to determine the rotary position of the output shaft, a permanent magnet and a Hall-sensor are usually fixed to the end face of the output shaft and to the housing respectively. Here, the permanent magnet serves as transducer for the Hall-sensor that can sense the rotary position of the output shaft at a sensing distance. The distance of the output shaft with the permanent magnet to the housing and to the Hall-sensor varies as a function of the axial play of the bearing, of the heat expansion of individual constituent parts of the positioning device and of individual tolerances such as for example of manufacturing tolerances. The sensing distance of the permanent magnet to the Hall-sensor however has to lie within a close tolerance field.

Thus, the axial play on the one hand has to be large enough for avoiding the jamming of the output wheel and on the other hand small enough for sensing the rotary position of the output shaft. In order to achieve this, the axial play is precisely predetermined and can only vary in a close tolerance range. This tolerance range is composed as a tolerance chain which is defined by manufacturing tolerances of the individual constituent parts in the positioning device—such as for example of the bearing, of the output shaft, of the output wheel, of the permanent magnet.

In order to be able to adhere to the tolerance range, manufacturing tolerances of the individual constituent parts can be reduced for example. Disadvantageously, this substantially increases the manufacturing costs of the individual constituent parts and thus of the positioning device. Alternatively or additionally, the operating temperature range of the positioning device can be restricted, but which is undesirable.

The object of the invention therefore is to state an improved or at least alternative embodiment for a positioning device of this type, with which the described disadvantages are overcome. The object of the invention also is to provide a suitable method for producing the positioning device.

According to the invention, these objects are solved through the subject of the independent claims. Advantageous embodiments are subject of the dependent claims.

A positioning device according to the invention for mechanically actuating a component comprises a housing with a first housing part and with a second housing part, which are welded to one another via an axial welded connection. Here, the first housing part comprises a first integrally formed bearing point of a bearing and the second housing part comprises a second integrally formed bearing point of said bearing within the housing. In the housing, a gearing with an output shaft is fixed which penetrates the second housing part and is drive-connectable to the component outside the housing to be mechanically actuated. The gearing comprises an output wheel that is non-rotatably fixed on the output shaft, which output wheel is rotatably mounted in the bearing. The first bearing point of the bearing interacts with a first bearing surface of the output wheel and the second bearing point of the bearing interacts with a second bearing surface of the output wheel located opposite the first bearing surface axially on the end face. In addition, the bearing has a predetermined axial play which is different from zero and which is defined by a difference between an outer axial distance between the two bearing points of the bearing and an inner axial distance between the two bearing surfaces of the output wheel. Furthermore, the positioning device comprises a rotary position detector with a permanent magnet and with a Hall-sensor. Here, the Hall-sensor can be arranged on the first housing part and the permanent magnet on a gear wheel of the output shaft or on the output shaft at the end face.

The output wheel is mounted in the bearing so as to be axially shiftable by the axial play, so that the output wheel can alternately interact with the first bearing surface on the first bearing point and with the second bearing surface on the second bearing point. Here, the axial play is predetermined in such a manner that the permanent magnet of the rotary position detector is sensible by the Hall-sensor both during the interaction of the first bearing surface of the output wheel with the first bearing point and also during the interaction of the second bearing surface with the second bearing point. Furthermore, the axial play is determined in such a manner that a jamming of the output wheel in the bearing as a consequence of deviating heat expansion coefficients or temperature differences in the positioning device is avoided. The permanent magnet of the rotary position detector and the Hall-sensor can be arranged within the first bearing point of the bearing and be enclosed by the same in the circumferential direction of the output shaft.

The output wheel interacts on both sides with the respective bearing point, which in each case can comprise an end face. Both the two bearing surfaces of the output wheel and also the corresponding end faces of the bearing points can be annular, so that during the interaction of the output wheel with the respective bearing points the respective bearing surface of the output wheel lies against the end face of the respective bearing point. The axial play can be defined by a difference of the outer axial distance between the end faces of the two bearing points and of the inner axial distance between the two bearing surfaces of the output wheel.

Advantageously it can be provided that the second housing part is formed by a housing cover for closing the housing. Furthermore, the second housing part can be formed by a support, which is arranged within the housing. The first housing part and the second housing part are connected to one another by way of an axial welded connection. Radially closed, the welded connection can circulate about the output shaft between the first housing part and the second housing part.

The invention also relates to a method for producing the positioning device described above. According to the invention, the second housing part, during the welding of the second housing part to the first housing part, and the first housing part are axially adjusted relative to one another until the predetermined axial play is present in the bearing. As already explained above, the axial play is defined by a difference of the outer axial distance and of the inner axial distance in the bearing. Here, the outer axial distance is given by the distance of the two bearing points or of the end faces of the two bearing points and the inner axial distance is given by the distance of the two bearing surfaces of the output wheel relative to one another. During the welding together, the first housing part with the first integrally formed bearing point and the second housing part with the second integrally formed bearing point are axially adjusted relative to one another so that between the first bearing point in the first housing part and the second bearing point in the second housing part the outer axial distance is adjusted. Here, the adjusted outer axial distance is adjusted as a function of the inner axial distance so that the predetermined axial play in the bearing is achieved.

In particular, the predetermined axial play can be advantageously adjusted in a close tolerance range in a simplified manner, wherein manufacturing tolerances of the individual constituent parts of the positioning device—such as for example of the bearing, of the output shaft, of the output wheel or of the rotary position detector need not be reduced. The positioning device can be cost-effectively produced with the method according to the invention and the operating temperature range of the positioning device can also be advantageously retained.

In a particularly advantageous embodiment of the method according to the invention, the second housing part, after the insertion of the output shaft with the output wheel into the housing and prior to the welding of the second housing part to the first housing part, can be brought into contact with the first housing part in a welding zone provided for forming the welded connection. Prior to welding the second housing part to the first housing part, an initial axial play that is present in the bearing can then be determined. Here, the initial axial play can be preferably determined by axially moving the output shaft with the output wheel in the bearing, wherein the output wheel with the respective bearing surface is alternately moved against the stop in the form of the end face of the first bearing point or against the end face of the second bearing point. Here, the shifting of the output shaft penetrating the housing and, correspondingly the initial axial play, be measured in an optical, tactile or other manner. As a function of the initial axial play, an axial adjusting travel can then be calculated by which the second housing part and the first housing part have to be axially adjusted relative to one another during the welding in order to achieve the predetermined axial play. The adjusting travel corresponds to a difference of the initial axial play and of the predetermined axial play in the bearing. Following this, the second housing part and the first housing part can be axially adjusted relative to one another by the calculated adjusting travel during the welding. Following the adjusting of the second housing part and of the first housing part relative to one another, the second housing part and the first housing part can then be welded to one another via the axial welded connection.

Alternatively, following the insertion of the output shaft with the output wheel into the first bearing point of the first housing part and prior to the welding of the second housing part to the first housing part, a first axial distance between the second bearing surface of the output wheel and of a first precalculated welding contour can be measured. Here, the first welding contour is formed on the first housing part in a welding zone provided for forming the welded connection. Furthermore, a second axial distance between the end face of the second bearing point of the bearing and a second precalculated welding contour can be measured. Here, the second welding contour is formed on the second housing part in a welding zone provided for forming the welded connection. Defining the two axial distances can be effected in an optical, tactile or other manner. From the first axial distance, from the second axial distance and from the predetermined axial play, an axial adjusting travel can then be calculated by which the second housing part and the first housing part have to be adjusted axially relative to one another for attaining the predetermined axial play during the welding. During the welding, the second housing part and the first housing part are then axially adjusted relative to one another by the calculated adjusting travel during the welding and subsequently welded to one another via the axial welded connection.

In a further alternative procedure it is provided in the method according to the invention that following the insertion of the output shaft with the output wheel into the first bearing point of the first housing part and prior to the welding of the second housing part to the first housing part, a first axial distance between the first bearing surface of the output wheel and a first precalculated welding contour is measured. Furthermore, a second axial distance between the end face of the second bearing point of the bearing and a second precalculated welding contour and an inner axial distance between the first bearing surface and the second bearing surface of the output wheel are measured. Here, the first welding contour is formed on the first housing part and the second welding contour on the second housing part in each case in a welding zone provided for forming the welded connection. Here, the relevant variables can also be determined in an optical, tactile or other manner. From the first axial distance, from the second axial distance, from the inner axial distance and from the predetermined axial play an axial adjusting travel can then be calculated, by which the second housing part and the first housing part have to be axially adjusted relative to one another during the welding for attaining the predetermined axial play. The second housing part and the first housing part are then axially adjusted relative to one another by the calculated adjusting travel during the welding and welded to one another via the axial welded connection.

Advantageously, the welding can be effected by laser welding or by ultrasound welding or by frictional welding, preferentially vibration welding.

In the method according to the invention, the positioning device can be produced with the predetermined axial play of the bearing in a simplified manner. In particular, manufacturing tolerances of the individual constituent parts of the positioning device—such as for example of the bearing, of the output shaft, of the output wheel or of the rotary position detector need not be reduced. Furthermore, the operating temperature range of the positioning device advantageously need not be restricted either in order to avoid a jamming of the output wheel in the bearing. Because of this, the positioning device can be cost-effectively produced.

Further important features and advantages of the invention are obtained from the subclaims, from the drawings and from the associated figure description by way of the drawings.

DETAILED DESCRIPTION

FIG. 1andFIG. 2show sectional views of a positioning device1according to the invention prior to and after the adjusting of a predetermined axial play S0, as it is shown inFIG. 2. The positioning device1comprises a housing2with a first housing part2aand with a second housing part2b, which inFIG. 2are already welded together via a welded connection3. Here, the first housing part2acomprises a first integrally formed bearing point4aand the second housing part2bcomprises a second integrally formed bearing point4b, which together form a bearing4within the housing2. In the housing2, an output shaft5and an output wheel6of a gearing—not shown here—are arranged. The output wheel6is non-rotationally connected to the output shaft5so that by driving the output wheel6the output shaft5is also driveable. The output shaft5penetrates the second housing part2band is drive-connectable to a component—not shown here—outside the housing2. Here, the output wheel6is rotatably mounted in the bearing4, wherein an end face7aof the first bearing point4ainteracts with a first bearing surface8aof the output wheel6and an end face7bof the second bearing point4bof the bearing4with a second bearing surface8bof the output wheel6axially at the end face—in this exemplary embodiment by lying against the same. Here, the end face7ais arranged located opposite the end face7band annular in shape and the first bearing surface8ais arranged located opposite the second bearing surface8band annular in shape. Furthermore, the positioning device1comprises a rotary position detector9with a Hall-sensor9aarranged on the first housing part2aand with a permanent magnet9barranged on the output shaft5at the end face. Here, the rotary position detector9is arranged within the first bearing point4aof the bearing4.

The output wheel6is mounted so as to be axially shiftable in the bearing4by the axial play S0, as shown inFIG. 2. The predetermined axial play S0is defined by a difference between an outer axial distance SA0between the two bearing points4aand4b—in this exemplary embodiment also between the two end faces7aand7bof the two bearing points4aand4bof the bearing4—and an inner axial distance SI0between the two bearing surfaces8aand8bof the output wheel6. The axial play S0is predetermined inFIG. 2in such a manner that the permanent magnet9bof the rotary position detector9is sensible by the Hall-sensor9aboth when the first bearing surface8aof the output wheel6lies against the end face7aof the first bearing point4aand also when the second bearing surface8bof the output wheel6lies against the end face7bof the second bearing point4b. Furthermore, the axial play S0is predetermined in such a manner that a jamming of the output wheel6in the bearing4and an exceeding of the sensing range of the Hall-sensor9aas a consequence of deviating heat expansion coefficients or temperature differences in the positioning device1is avoided.

The adjusting device shown inFIG. 1andFIG. 2can be produced in a method10according to the invention. Here, the second housing part2band the first housing part2aare axially adjusted relative to one another during the welding of the second housing part2bto the first housing part2a, as indicated by arrows inFIG. 1. As soon as the predetermined axial play S0is present in the bearing4, the second housing part2band the first housing part2aare welded to one another via the axial welded connection3, as shown inFIG. 2. Here, the first housing part2aand the second housing part2bcan be welded to one another by laser welding or by ultrasound welding or by frictional welding—preferentially vibration welding.

Advantageously, the predetermined axial play S0in the positioning device1according to the invention is adjustable in a close tolerance range. Here, the positioning device1can be produced in a simpler and more cost-effective manner by the method10according to the invention. In particular, manufacturing tolerances of the individual constituent parts of the positioning device1—such as for example of the bearing4, of the output shaft5, of the output wheel6or of the rotary position detector9need not be reduced. Furthermore, the positioning device1can be operated in a wide operating temperature range.

FIG. 3toFIG. 5show sectional views of the positioning device1with relevant variables for adjusting the predetermined axial play S0.

InFIG. 3, relevant variable in a particularly preferred procedure for adjusting the predetermined axial play S0in the bearing4are shown. Here, following the insertion of the output shaft5with the output wheel6into the housing2and prior to the welding of the second housing part2bto the first housing part2a, the second housing part2bis brought into contact with the first housing part2afor forming a welding zone11provided for the welded connection3. Prior to welding the second housing part2bto the first housing part2a, an initial axial play SANFpresent in the bearing4is determined. This is determinable particularly easily by axially moving the output shaft5and the output wheel6in the bearing4, wherein the output wheel6with the respective bearing surface8aor8bis alternately brought against a stop on the respective end face7aor7bof the respective bearing point4aor4b. As a function of the initial axial play SANF, an axial adjusting travel W0can then be calculated by which the second housing part2band the first housing part2ahave to be axially adjusted relative to one another for attaining the predetermined axial play S0. Following this, the second housing part2band the first housing part2acan be adjusted by the calculated adjusting travel W0and welded to one another via the axial welded connection3.

InFIG. 4, relevant variables during an alternative procedure for adjusting the predetermined axial play S0in the bearing4are shown. Here, after the insertion of the output shaft5with the output wheel6into the first bearing point4aof the first housing part2aand prior to the welding of the second housing part2bto the first housing part2a, a first axial distance S1and a second axial distance S2are determined. Here, the first axial distance S1will be measured between the second bearing surface8bof the output wheel6and a first precalculated welding contour12aand the second axial distance S2between the end face7bof the second bearing point4bof the bearing4and a second precalculated welding contour12bin an optical, tactile or other manner. Here, the first welding contour12ais formed on the first housing part2aand the second welding contour12bon the second housing part2bin a welding zone11provided for forming the welded connection3. From the first axial distance S1, from the second axial distance S2and from the predetermined axial play S0, an axial adjusting travel W0can then be calculated. During the welding, the second housing part2band the first housing part2aare then axially adjusted relative to one another by the calculated adjusting travel W0and can be welded to one another via the axial welded connection3thereafter.

InFIG. 5, relevant variables in a further alternative procedure for adjusting the predetermined axial play S0in the bearing4are shown. Here, following the insertion of the output shaft5with the output wheel6into the first bearing point4aof the first housing part2aand prior to the welding of the second housing part2bto the first housing part2a, a first axial distance S1and a second axial distance S2are measured. Here, the first axial distance S1is measured between the first bearing surface8aof the output wheel6and a first precalculated welding contour12a. The second axial distance S2is measured between the end face7bof the second bearing point4bof the bearing4and a second precalculated welding contour12b. The measurement of the two axial distances S1and S2can be effected in an optical, tactile or other manner. As also inFIG. 4, the first welding contour12ais formed on the first housing part2aand the second welding contour12bis formed on the second housing part2bin a welding zone11provided for forming the welded connection3. Furthermore, an inner axial distance SI0between the first bearing surface8aand the second bearing surface8bof the output wheel6is measured in a tactile, optical or other manner. From the first axial distance S1, from the second axial distance S2, from the inner axial distance SI0and from the predetermined axial play S0, an axial adjusting travel W0can then be calculated. During the welding, the second housing part2band the first housing part2acan then be axially adjusted relative to one another by the calculated adjusting travel W0and welded to one another via the axial welded connection3.

In a method10according to the invention, the positioning device1can be produced with the predetermined axial play S0in a simplified and cost-effective manner. In particular, manufacturing tolerances of the individual constituent parts of the positioning device1—such as for example of the bearing4, of the output shaft5, of the output wheel6, of the rotary position detector9—need not be reduced. Furthermore, the positioning device1can be operated in a wide operating temperature range.