Gabelwelle

Abstract

The invention relates to a shaft 1 with a device for the indirect acquisition and transmission of measurement data from the shaft 1 resulting from a mechanical stress on the shaft 1, wherein the shaft 1, with a central axis M as part of a cardan shaft, has a first end section 1.2 and the shaft 1 is combined with a fork 2 for transmitting torques to a cross pin 2.1, and the shaft 1 and the fork 2 form a shaft end E. The device is intended to be easier to manufacture and, at the same time, to better protect the sensor against external influences. A recess 1.1 for receiving at least part of a sensor arrangement 3 is provided in the shaft 1, wherein the recess 1.1 is introduced into the shaft end E from the outside, from the side of the fork 2 and coaxially with the central axis M.

Description

The invention relates to a shaft with a device for indirectly acquiring and transmitting measurement data from the shaft which result from a mechanical stress on the shaft, wherein the shaft has a first end section with a central axis as part of a cardan shaft, and the shaft is combined with a fork for transmitting torques to a cross pin, and the shaft forms a shaft end with the fork.Universal joints of the generic type as a special form of the universal joints comprise one or two universal joints (universal joints) for bending, angling or bending the shaft strand and for forwarding and transmitting a torque to shafts adjoining the universal joint on both sides. The universal joint comprises in the preferred embodiments two forks which are connected to one another via a universal joint with two pairs of pins crossed at right angles. A shaft connects to the respective fork, which shaft transmits the torque via the second end section of the shaft opposite the fork to a further component in the drive train via a toothing or a flange. In most embodiments, the fork is adjoined by a fork shaft, that is to say a shaft with an external toothing or a hollow shaft with an internal toothing. A fork shaft and a hollow shaft are mounted so as to be displaceable with respect to one another for the purpose of length compensation and together form a slide bearing or a displacement.WO 2022 / 017928 A1 already discloses a universal joint with a adjoining hollow shaft, in which a sensor is arranged in the cavity of the hollow shaft adjoining the toothing. The arrangement of the sensor in the cavity of a hollow shaft requires an extension of the hollow shaft by the structural dimension for the sensor arrangement in the axial direction. In addition, the hollow shaft is partially filled with lubricant as part of the displacement, so that the sensor arrangement has to be sealed against the lubricant and is exposed to the lubricant without or in the case of inadequate sealing. According to DE 11 2017 000 605 T5, a generic fork shaft is known in which the sensor is arranged on the outer side of the toothed shaft in the region of the fork in a depression provided for the sensor. The positioning of the sensor arrangement on the outer side of a shaft in a region in the axial direction between the external toothing and the fork requires a complicated machining of the shaft for the purpose of a depression for the sensor and offers little protection for the sensor arrangement. In addition, due to the reduced diameter of the shaft due to the depression for the sensor, the strength and thus the torque capacity of the shaft is limited compared to the normal state.The invention is based on the object of configuring and arranging a device for capturing and transmitting measurement data from a shaft in such a way that it is simple to produce and the sensor is at the same time better protected against external influences.The object is achieved according to the invention in that a recess for receiving at least a part of a sensor arrangement is provided in the shaft, wherein the recess is introduced into the shaft end from the outside from the side of the fork and in the direction of the central axis. This ensures that the sensor arrangement can be introduced into the shaft from the fork side, for example, by a simple bore. Due to the front recess from the fork side, the space for the sensor arrangement around the central axis is protected from mechanical influences by the shaft and also in both axial directions and is not impaired by operating materials or dirt. On the side of the universal joint on which the recess opens out at the shaft end, the universal joint and the two forks engaging on the universal joint protect against mechanical influences from the outside. Due to its arrangement according to the invention, the recess is independent in its size of the size or the type of shaft, because the recess does not influence the other geometry of the shaft and the fork. It has been found that by such a positioning of the recess it is also possible to position a sensor arrangement in very short shafts and in applications without a hollow shaft. The subject matter of the invention is initially not yet covered by a sensor arrangement.For the solution according to the invention, essentially two designs of shafts with a fork are considered. In the most common design, the shaft forms with the fork a one-piece forged part, in which the fork adjoins the shaft in the axial direction, wherein the recess is guided through the fork coaxially with the central axis and is introduced at the end side into the first end section of the shaft. In principle, the recess is introduced into the shaft end from the outside from the side of the fork and in the direction of the central axis. To achieve the object, however, it is not absolutely necessary for the recess to be arranged coaxially with respect to the central axis. In technically advantageous embodiments, however, the recess is additionally arranged coaxially to the central axis. The arrangement of the recess coaxial to the central axis enables a correspondingly coaxial positioning of the sensor arrangement. This coaxial arrangement has the advantage that extremely low imbalance arises due to the mass of the sensor arrangement. Due to the penetration of the fork, the sensor can be inserted into the shaft from the shaft end. For this purpose, it is necessary to provide a recess also in the fork. The part of the recess in the fork offers storage space for parts of the sensor arrangement according to the invention.In an alternative generic, but two-part design of cardan shafts, the fork is placed on the shaft, so that the shaft dips into the fork. The shaft is coupled to the fork via a toothing in the circumferential direction. For positioning the sensor arrangement, it is advantageous that the recess is introduced directly at the end face and coaxially to the central axis into the first end section of the shaft. Machining of the fork is not necessary in this case. Also in this embodiment, coaxial alignment is required in addition to the direction from the fork side. Axial and coaxial directions and arrangements are to be understood within the scope of the invention in principle with respect to the central axis of the shaft. The axial direction from the fork toward the shaft is referred to as the direction from the outside. The substantially smaller installation space available in the fork-side recess compared to the known solutions can be compensated for according to the invention in the one-piece design by positioning parts of the sensor arrangement, such as the antenna and / or a battery as an energy supply at least partially directly at the end face in front of the shaft in the fork. The recess in the fork can be dimensioned substantially larger in diameter toward the open side or toward the outside than in the shaft, because in this front region of the fork no substantial transmission of the torque takes place from the shaft via the fork to the cross pin. The torque is transmitted substantially immediately after the transition from the shaft to the fork in the rear region of the fork. Due to the larger diameter, it is possible to use an antenna having a larger surface area, so that the data transmission can be optimized.Due to the production-related geometry in a universal joint with a cross pin, a distance of on average more than one centimeter is provided along the central axis between the fork or the end face of the shaft at the first end section and the cross pin. This spacing provides clearance for the transmission of electromagnetic signals transmitted through the antenna without interference. This free space also makes it possible, for example, to service the sensor arrangement without dismantling the universal joint. Via this free space, a closure for the recess can be mounted and disassembled, for example in the form of a cover and parts of the sensor arrangement. The accessibility of a charging socket of a rechargeable battery as an energy supply of the sensor and in particular the placing of a plug is ensured by this free space. According to the invention, the advantage is made usable by the selection of the position of the recess, because the accessibility to the cardan joint and to the free space is ensured in any case in this region when the fork shaft is installed. The bearings of the cross pin are easily accessible for servicing for smearing with a grease gun.For measuring and acquiring data, it is advantageous in a further step of the invention if the device comprises a sensor arrangement for acquiring and transmitting the measurement data, wherein a sensor is positioned as part of the sensor arrangement in the recess and is fastened to the surface of the recess. The recess is basically suitable for positioning a sensor arrangement. The combination of such a shaft with a sensor arrangement makes it possible to record measured values and to protect the sensor arrangement.With regard to data acquisition, it can advantageously be provided that the sensor arrangement also has an antenna and a power supply as a component, wherein at least the antenna is arranged in a region of the recess which lies in the axial direction at the front end of the recess and within the fork. The antenna is provided for transmitting the measurement data. In preferred embodiments, a charging cable with a charging bushing for a rechargeable battery is additionally provided as an energy supply. In the recess, a wide variety of components can be positioned one behind the other in the axial direction. Of great interest are the measurement data of the wave immediately at the end before the transition to the fork. The positioning of the sensor at this location allows the antenna to be placed even further outwards directly at the opening of the recess in the area of the fork. For the power supply, the position at the rear in the recess behind the sensor is provided.With regard to data transmission, it may be advantageous for the present invention if the recess has a larger diameter in the region inside the fork than in the shaft. By increasing the diameter, a larger antenna can be used, the size of which makes the data transmission more precise and more powerful.In connection with the production of a simple recess, it can be advantageous if the recess is formed as a hole, as a blind bore or as a through bore, wherein the recess has a length between 20 mm and 280 mm or between 160 mm and 200 mm. A bore as the simplest embodiment can be made as a blind bore or as a through bore. Through-holes can be used in very short shafts, so that the bore is guided as far as the end of the shaft which is arranged opposite the fork. In addition to bores, it would also be possible to produce the recess by erosion.With regard to the best possible measurement results, it can be advantageous if the inner surface of the recess has a dimensional tolerance of on average between +1 / 100 mm and +6 / 100 mm with respect to the diameter. The dimensional tolerance preferably corresponds to the value H7 of the common tolerance tables. It is also advantageous that the inner surface of the recess has a dimensional tolerance of at most 0.03 mm to 0.2 mm with respect to roundness and / or a dimensional tolerance of at most 0.05 mm to 0.2 mm with respect to coaxiality and / or a mean roughness value Ra of between 0.4 μm and 32 μm with respect to roughness.With regard to the design of the shaft, there are no limits according to the invention, which is why it is advantageous for the shaft to be designed as a fork shaft or as a hollow shaft or as a shaft without a toothing or to form a component of a double joint shaft. The recess from the fork side can be made in almost any desired shaft.With regard to the use of the shaft for transmitting torques, it is provided that a cross pin is mounted in the fork and a flange with a fork is mounted on the cross pin. The shaft itself is combined via a displacement with a further shaft, via which the torque is transmitted via a further universal joint or another connection.Further advantages and details of the invention are explained in the patent claims and in the description and are illustrated in the figures. They show FIG. 1 is a sectional view of a fork shaft with a recess; FIG. 2 shows a view according to FIG. 1 with a sensor arrangement; FIG. 3 is a perspective view of a fork shaft looking at the shaft end; FIG. 4 is a view of a complete cardan shaft with a fork shaft and a hollow shaft; and FIG. 4a shows an enlarged detail according to FIG. 4.FIGS. 1-3 show, by way of example, a fork shaft in which a recess 1.1 for the introduction of a sensor arrangement 3 is provided from the shaft end E. The fork shaft as a forged part consists of a shaft 1 and a fork 2. in the region of the fork shaft shown in section, the fork 2 connects to the shaft 1 at a first end section 1.2 of the shaft 1. The end of the shaft 1 is illustrated in the figures by the dashed line running at right angles to the central axis M of the shaft 1. The first end section 1.2, together with the fork 2, defines the shaft end E of the fork shaft that is relevant for the positioning of the sensor arrangement 3. The end of the shaft 1 opposite the fork 2 forms a second end section of the shaft 1. The fork shaft and the hollow shaft are mounted so as to be displaceable relative to one another via the tooth arrangements.The fork shaft according to FIGS. 1-4 is a one-piece forged part consisting of the shaft 1 and the fork 2. fork shafts can also be formed as two-piece components (not shown), in which the fork is placed on the first end section of the shaft and the fork is connected to the shaft via an internal toothing.According to the exemplary embodiments shown here, the recess 1.1 is positioned in the form of a bore coaxial to the central axis M of the shaft 1 and was introduced from the outside from the shaft end E through the fork 2 and into the first end section 1.2 of the shaft 1. The recess 1.1 has a length L of 180 mm. To this end of the shaft 1 the fork 2 physically adjoins as part of the forged part.The further solution to the object comprises the positioning of a sensor directly at the end of the first end section 1.2 of the shaft 1. In FIGS. 2 and 3 a sensor arrangement 3 is shown which is introduced into the recess 1.1. The sensor arrangement 3 comprises a sensor 3.1, an antenna 3.2 and a power supply 3.3 in the form of a rechargeable battery. For charging the battery 3.3, a charging socket 3.4 with a charging cable is provided, which is positioned outwards at the beginning of the recess 1.1. The sensor is positioned directly at the end of the first end section 1.2, at which the shaft 1 merges into the fork 2. For the sensor arrangement 3 shown here, the recess 1.1 in the fork according to FIG. 1 has, in a region (G) at the beginning of the recess 1.1, a diameter Dg which is greater than the diameter Dw of the recess 1.1 in the shaft. This larger diameter allows the positioning of an antenna 3.2 of larger diameter, as shown in FIGS. 2 and 3.FIG. 4 shows a complete cardan shaft, in which the fork 2 is adjoined by a cross pin 2.1, which in turn is coupled to a flange 5 via a further fork 5.1. On the end of the shaft 1 opposite the shaft end E, a hollow shaft 4 with an internal toothing is pushed onto the shaft 1. At the end of the hollow shaft 4 a fork 4.1 is provided which is coupled via a further cross pin 2.1 to a further fork 6.1 and a further flange 6 adjoining it.The region highlighted in the left-hand region of FIG. 4 by a dashed circle is depicted in FIG. 4 ain an enlarged manner. In such conventional arrangements of cardan shafts, a distance of several millimeters or usually more than one centimeter is provided in the axial direction in the region of the central axis M between the fork 2 and the cross pin 2.1. In this region, designated as free space F, lubricating nipples are usually also arranged for the maintenance of the bearings of the cross-pins 2.1. Due to the clearance F provided by the distance, the recess 1.1 is very easily accessible at the end face at the shaft end E. This ensures access to the sensor arrangement 3, for example in order to connect the charging cable positioned in the recess 1.1 to a charger via the charging socket 3.4 for the battery 3.3. For this purpose, the charging socket 3.4 is provided directly at the beginning of the recess 1.1 in the region of the antenna 3.2. Furthermore, this free space F allows interference-free transmission of the electromagnetic signals of the antenna 3.2.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedWO 2022 / 017928 A1

[0003] DE 11 2017 000 605 T5

[0003]

Claims

Shaft (1) having a device for indirectly recording and transmitting measurement data from the shaft (1) which result from mechanical stressing of the shaft (1), wherein the shaft (1) has a first end section (1.2) with a central axis (M) as part of a cardan shaft and the shaft (1) is combined with a fork (2) for transmitting torques to a cross pin (2.1) and the shaft (1) forms a shaft end (E) with the fork (2), characterized in that a recess (1.1) for receiving at least part of a sensor arrangement (3) is provided in the shaft (1), wherein the recess (1.1) is introduced from the outside from the side of the fork (2) and in the direction of the central axis (M) into the shaft end (E).Device according to claim 1, characterised in that the fork (2) adjoins the shaft (1) in the axial direction and forms a one-piece forged part with the shaft (1), wherein the recess (1.1) is guided through the fork (2) coaxially to the central axis (M) and is introduced at the end side into the first end section (1.2) of the shaft (1).Device according to claim 1, characterised in that the fork (2) is placed on the shaft (1) and the recess (1.1) is introduced directly at the end face and coaxially to the central axis (M) into the first end section (1.2) of the shaft (1).Device according to one of the preceding claims, characterized in that the device comprises a sensor arrangement (3) for recording and transmitting the measurement data, wherein a sensor (3.1) is fastened as part of the sensor arrangement (3) in the recess (1.1).Device according to claim 4, characterised in that the sensor arrangement (3) also has an antenna (3.2) and an energy supply (3.3) as a component, wherein at least the antenna (3.2) is arranged in a region (G) of the recess (1.1) which lies in the axial direction at the front end of the recess (1.1) and within the fork (2).Device according to claim 5, characterised in that the recess (1.1) has a diameter (Dg) at least partially in the region (G) within the fork (2) and a diameter (Dw) within the shaft (1), wherein the diameter (Dg) is greater than the diameter (Dw).Device according to one of the preceding claims, characterized in that the recess (1.1) is designed as a hole, as a blind bore or as a through bore, wherein the recess (1.1) has a length (L) of between 20 mm and 280 mm or between 160 mm and 200 mm.Device according to one of the preceding claims, characterized in that the inner surface of the recess (1.1) has a dimensional tolerance of on average between + 1 / 100 mm and + 6 / 100 mm with respect to a) of the diameter (Dw) and / or b) of the roundness has a dimensional tolerance of at most 0.03 mm to 0.2 mm and / or c) of the coaxiality has a dimensional tolerance of at most 0.05 mm to 0.2 mm and / or d) of the roughness has a mean roughness value Ra of between 0.4 μm and 32 μm.Device according to one of the preceding claims, characterized in that the shaft (1) is designed as a fork shaft or as a hollow shaft or as a shaft (1) without a toothing or forms a component of a double joint shaft.Device according to one of the preceding claims, characterized in that a cross pin (2.1) is mounted in the fork (2) and a flange (5) with a fork (5.1) is mounted on the cross pin (2.1).A system comprising a shaft (1) according to any one of the preceding claims and one or more components for connection to the shaft (1) in the form of cross-pins, fork shafts, hollow shafts, transmission shafts, universal joints, flanges and transmissions for transmitting torques.Use of a recess (1.1) in a shaft (1) for receiving at least part of a sensor arrangement (3), wherein the shaft (1) has a first end section (1.2) with a central axis (M) as part of a cardan shaft and the shaft (1) is combined with a fork (2) for transmitting torques to a cross pin (2.1) in such a way that the shaft (1) with the fork (2) form a shaft end (E) and the recess (1.1) is introduced from the outside and coaxially to the central axis (M) at the end face into the shaft end (E) into the first end section (1.2) of the shaft (1).

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