Torque-measuring coupling

Abstract

The invention describes a torque-measuring coupling which consists of a stator, a strain gauge sleeve and optionally hubs connected to the latter via disc attachments. The torque-measuring coupling is suitable for transmitting torque, for compensating for shaft offset and for measuring the transmitted torque. The strain gauge sleeve is of multiple-part construction, wherein, in particular, the expanding sleeve is enclosed radially by a coil ring and is connected in a positively locking manner to a flange. Here, the coil ring has an internal diameter which is smaller than the external diameter of the flange, and receives a protective tube.

Description

Torque measuring clutch

[0001] The invention relates to a torque measuring coupling suitable for transmitting and measuring torque and for adaptation to a drive train. The torque measuring coupling comprises a strain gauge sleeve and preferably two torsionally rigid, flexible shaft couplings. The strain gauge sleeve measures the torque-proportional surface strain using strain gauges. The strain is then converted into a torque value. The shaft couplings serve to adapt the torque measuring coupling to the drive train and to compensate for any axial, angular, and lateral misalignments.

[0002] Such torque measuring couplings are used in industrial applications for monitoring and measuring torque in drive trains.

[0003] Patent application DE 102017 004 680 A1 is known from the prior art. This describes a strain gauge sleeve suitable for precise torque measurement using strain gauges. By arranging these strain gauges in the area of ​​the tapered cross-section and on the described spring elements, accurate measurement is possible even if the shaft axes are misaligned. A disadvantage of this design is the large number of strain gauges and spring elements required, which leads to high costs. Furthermore, the delicate spring elements and the strain gauges applied to them are not protected from potentially damaging external mechanical influences. The design of the strain gauge sleeve connection is largely left open.

[0004] EP 1 074 826 B1 also describes a strain gauge sleeve which, through its design and the use of shear force transducers, is intended to achieve high measuring accuracy. The shear force transducers are to be optionally mounted on the outer or inner diameter in areas with reduced wall thickness. Furthermore, it is described that one of the flanges is designed as a closed part without a through-hole. Applying the shear force transducers to the inner diameter is more complex and therefore more expensive due to the poorer accessibility. Moreover, the closed design of one of the flanges precludes axial penetration through the strain gauge sleeve. In addition, the areas containing the elements intended for torque measurement are not protected from external influences.

[0005] Furthermore, DE 101 14 338 B4 describes a torque measuring coupling which includes a specially designed adaptation flange that serves as a link between the strain gauge sleeve and the shaft coupling. The adaptation flange is intended to reduce parasitic forces caused by shaft displacement, which act on the strain gauge sleeve and reduce the measurement accuracy. A disadvantage of the described design is that the adaptation flange design is associated with high manufacturing costs. Furthermore, the strain gauge sleeve is almost completely exposed, meaning that its areas for torque measurement are not protected from external influences.

[0006] The object of the present invention is to design a torque measuring coupling in such a way that it is cost-effective, suitable for use in process monitoring in industrial applications, and correspondingly robust. Furthermore, simple shaft connection and axial routing through the torque measuring coupling should be possible.

[0007] According to the invention, the problem is solved by the features of the main claim and the dependent claim. Furthermore, additional advantageous embodiments are described in the dependent claims.

[0008] The torque measuring coupling consists of several components. The central component is the strain gauge sleeve, which in turn has an expansion sleeve. The expansion sleeve has a sectionally tapered cross-section, referred to as the sleeve section, along its axial extent. When torque is transmitted with the torque measuring coupling, a change occurs in the area of ​​theThe tapered sleeve section experiences its greatest elastic deformation, which is detected and measured by strain gauges applied to the outer diameter in this area. At one end of its axial extension, the expansion sleeve features a flange suitable for attaching a laminate pack. This flange has alternating recesses and threaded holes with a countersink radius on a circumferential pitch circle. On the other side, the expansion sleeve has threaded holes on its end face with a smaller pitch circle than that of the laminate pack. This side also features a centering pin. A flange is centered over this pin and securely fastened to the expansion sleeve with mounting screws.This flange also features threaded holes with countersinks and recesses suitable for connecting the friction plate assembly. Alternatively, both the expansion sleeve and the flange can be designed with holes without countersinks, which are suitable for direct bolting to another component without intervening friction plate assemblies. To avoid reducing the transmissible torques of the torque measuring coupling due to the smaller pitch circle of the flange connection between the expansion sleeve and the flange compared to the pitch circle of the friction plate assemblies, one or both contact surfaces can be shot-blasted, which increases the transmissible torques. Alternatively, a washer with increased surface roughness can be used, thus increasing the transmissible torques of this flange connection.

[0009] Furthermore, a coil ring, preferably made of a plastic, a fiber-reinforced material, or an aluminum alloy, is pressed onto or bonded to the expansion sleeve. The coil ring has an inner diameter that is smaller than the outer diameter of the flange connected to the expansion sleeve. The coil ring performs several functions, but is not involved in torque transmission. It serves to hold a protective tube, the outer diameter of which, in the area of ​​the coil ring, is fitted with an absorber film. The protective tube is pressed onto or bonded to a receptacle in the coil ring. On the other side of the protective tube, it projects axially into a tube receptacle in the expansion sleeve. Within this receptacle, the protective tube is embedded in a substantially U-shaped plastic or rubber ring, or a ring made of another sealing material.The protective tube does not transmit torque. It serves as contact protection and, in combination with the pipe fitting, as a seal for the strain gauges. Thus, they are... Strain gauges are protected from contact and contamination. The protective tube is preferably made of an aluminum alloy, a plastic, or a fiber-reinforced material.

[0010] Furthermore, the coil ring serves as a carrier for a magnetic coil, which is firmly embedded and sealed within the coil ring using a potting compound. The magnetic coil is electrically connected to a printed circuit board (PCB), which is also embedded and sealed within the coil ring using a potting compound. For easier assembly, the PCB can be pre-mounted using plastic expansion rivets. The magnetic coil supplies power to the PCB, which in turn is connected to the strain gauges. For this purpose, the coil ring has at least one recess on its inner diameter, which serves as a cable entry point.

[0011] A stator is located radially spaced at the level of the coil ring. The radial distance between the coil ring and the stator is preferably 1 mm to 10 mm. The stator contains a magnetic circuit suitable for inductive energy transfer to the coil in the coil ring. Furthermore, the stator contains a radio receiver for receiving data transmitted from the circuit board. The data can be read from the stator as an analog signal and / or as a digital signal via Ethernet connection. Wireless connections via Wi-Fi or Bluetooth are also possible.

[0012] The circuit board includes a voltage regulator for powering the strain gauges. It also includes a controller that processes the signals transmitted from the strain gauges to the board. These processed signals are then transmitted wirelessly to the stator. Furthermore, the board can also incorporate an accelerometer, preferably capable of measuring accelerations along three axes. This allows the torque-measuring coupling to monitor and measure not only the transmitted torque but also vibrations and rotational accelerations.

[0013] In the axial direction, the strain gauge sleeve can be screwed to a lamellar assembly on one or both sides. The lamellar assembly consists of at least one lamellar, each with several equally spaced bores on a pitch circle. The bores are alternately fitted with flanged bushings and rings. These serve as centering elements for the alternating screw connections of the lamellar assemblies to the strain gauge sleeve and to the hubs. The configuration of each hub, together with the lamellar assembly and the strain gauge sleeve, forms a flexible shaft coupling that is torsionally rigid in the area of ​​the respective lamellar assembly but axially elastic and flexurally elastic. This allows axial, lateral, and angular misalignment between the shafts to be compensated for.

[0014] The hubs, which connect the torque measuring coupling to the shafts, can be of various designs. It is crucial that backlash-free connections to the shafts are used. This prevents torque surges caused by backlash and increases the service life of the torque measuring coupling. Clamping ring hubs, clamping ring hubs, clamping hubs, or shrink disc hubs are particularly well-suited. Half-shell hubs or simple flange connections can also be used.

[0015] Furthermore, it is also possible to connect the strain gauge sleeve, with or without a lamellar connection, to an overload clutch, which then protects not only the drive train but also the torque measuring clutch from overload. Both disengaging overload clutches and slip clutches are suitable for this purpose. Additionally, helical spring clutches, detent clutches, or synchronous clutches can also be used.

[0016] The small number of components and, in particular, the divisible design of the strain gauge sleeve, consisting of an expansion sleeve and flange, result in a particularly cost-effective assembly with reduced susceptibility to external influences. The divisible design allows the strain gauges to be applied to the expansion sleeve early in the assembly process, while the sleeve's outer diameter is still easily accessible. Only later is the coil ring, along with its protective tube (which improves protection against external influences), mounted on the expansion sleeve. Similarly, the protective tube can be pre-mounted on the loose coil ring, and the coil can be installed and potted beforehand. These steps are particularly easy and cost-effective to perform when the coil ring is not yet mounted. Subsequently, once the coil ring is attached to the expansion sleeve, the circuit board is pre-mounted and held in position using expansion rivets.At this stage, the wiring on the circuit board, i.e., its connection to the strain gauges and the coil, can be carried out before it is also potted. Only after these assembly steps is the flange connected to the expansion sleeve. The strain gauge sleeve is then bolted to the lamellar packs and the hub flanges.

[0017] Any shaft misalignment can be compensated for by the single-joint or double-joint design of the torque measuring coupling with one or two lamellar packs. Despite this compensation, resulting reaction forces occur in the expansion sleeve, which affect the measuring accuracy of the strain gauges. To counteract this, one, two, three, or preferably four or more strain gauges are provided on the circumference of the expansion sleeve in the sleeve section. The use of multiple strain gauges further improves the measuring accuracy.

[0018] The strain gauges are located on the outer diameter of the expansion sleeve in the area of ​​the sleeve section. They are protected from accidental contact or ingress of media by the expansion sleeve itself, as well as by the protective tube and its seal provided by the tube receptacle. There are no strain gauges or wiring on the inner diameter of the expansion sleeve, so that, for example, wiring can be routed axially through the interior of the torque measuring coupling without compromising its function through accidental contact with the strain gauges.

[0019] Since the coil ring is designed as a closed and indivisible ring and has a relatively low moment of inertia due to the materials used, the permissible rotational speed of the coil ring is not limited, or only to a small extent, compared to the permissible rotational speed of the hubs and lamella packs.

[0020] They show:

[0021] Figure 1 Torque measuring coupling with clamping ring hubs in full section

[0022] Figure 1.1 Detail view of the lamella connection in full section

[0023] Figure 1.2 Detail view of the coil ring in full section

[0024] Figure 2 Torque measuring coupling with a clamping ring hub and a clamping hub in full section, as well as the full sections BB and CC of the hubs

[0025] Figure 1 shows a full-section view of a torque measuring coupling (1). This coupling consists of a strain gauge sleeve (1.1) and hubs (3) connected to it via lamellar connections (2). In the depicted form, the hubs (3) are designed as so-called clamping ring hubs, which form the connecting element to the shaft ends (not shown). The stator (4) is arranged at a radial distance (S) from the coil ring (1.4).

[0026] The hubs (3) are provided with a hub flange (3.1) towards the strain gauge sleeve (1.1), which is suitable for a lamellar connection (2). The clamping ring (3.3) is pulled onto the conical section of the clamping ring hub (3.2) by means of the clamping screws (3.4), so that the clamping ring hub (3.2) deforms elastically and tapers radially. In this way, the shaft ends (not shown) are clamped in the hubs (3) without play.

[0027] The lamellar connections (2) are formed by mutually screwing the lamellar packages (2.1) to the hub flanges (3.1) and the strain gauge sleeve (1.1) and the flange (1.13) via the threaded bores with radius countersinks provided for this purpose (1.18).

[0028] The strain gauge sleeve (1.1) is a multi-part assembly consisting of a strain gauge sleeve (1.2) and a flange (1.13). The strain gauge sleeve (1.2) is provided with threaded bores (1.14) and a pin (1.19) facing the flange (1.13). The flange (1.13) is centered on the pin (1.19) and screwed to the strain gauge sleeve (1.2) using the fastening screws (1.15). To increase the transmissible torque of the connection between the strain gauge sleeve (1.2) and the flange (1.13), a friction-enhancing washer, not shown in Figure 1, can be inserted between the components. It is also possible to modify the roughness of the flange (1.13) and / or the expansion sleeve (1.2) in the area of ​​the contact surface (1.16) during surface treatment in such a way that a higher coefficient of friction is also achieved, which leads to a higher transmissible torque.

[0029] The coil ring (1.4) is rigidly connected to the expansion sleeve (1.2). The protective tube (1.5) is in turn rigidly connected to the coil ring (1.4). On the side of the expansion sleeve (1.2) facing away from the coil ring (1.4), the protective tube (1.5) projects axially into the tube receptacle (1.6) of the expansion sleeve (1.2). The protective tube (1.5) is provided with a contact seal or elastically potted within the tube receptacle (1.6).

[0030] The protective tube (1.5) together with the tube holder (1.6), the expansion sleeve (1.2) and the coil ring (1.4) thus form a Contact-protected and sealed space around the outer diameter of the expansion sleeve (1.2) in the area of ​​the sleeve section (1.3). In this area of ​​the sleeve section (1.3), the strain gauges (1.12) are located on the outer diameter of the expansion sleeve. (1 .2) applied. The wiring of the strain gauges (1.12) to the circuit board (1.10), which is not shown in Figure 1, runs through the cable entry (1.20) of the coil ring (1.4).

[0031] The coil ring (1.4) has an inner diameter that is smaller than the outer diameter of the flange (1.13). Furthermore, the coil ring (1.4) is a closed and non-divisible ring.

[0032] Figure 1.1 shows detail section A from Figure 1, which illustrates details of the coil ring assembly. The protective tube (1.5), which is rigidly connected to the coil ring (1.4), has an absorber film (1.7) on its outer diameter in the area of ​​the coil ring (1.4). The printed circuit board (1.10), which was fixed in the coil ring (1.4) during the assembly process using expansion rivets (1.11), is potted with a potting compound (1.9). The coil (1.8) is also inserted into the coil ring (1.4) and potted with the potting compound (1.9). The coil (1.8) is wired to the printed circuit board (1.10), which is not shown in Figure 1.1.

[0033] Figure 1.2 shows detail B from Figure 1, which illustrates an exemplary lamellar connection (2). The lamellar assembly (2.1) is bolted to the hub flange (3.1) by screws (2.5) and nuts (2.6). The lamellar assembly (2.1) is composed of at least one, but preferably two or more, lamellars (2.2). The lamellars (2.2) are connected without play via the flanged bushings. (2.3) and the rings (2.4) connected to each other.

[0034] Figure 2 also shows a full section view of a torque measuring coupling (1), along with full sections BB and CC through the clamping hub (5) and the clamping ring hub (6). The construction of the strain gauge sleeve (1.1) with the expansion sleeve (1.2), the flange (1.3), the coil ring (1.4), and the protective tube (1.5) does not differ from the construction described in Figure 1. However, Figure 2 shows alternatives to the hubs (3) for connecting the torque measuring coupling (1) to the shaft ends. On the left side, a clamping hub (5) is connected to the strain gauge sleeve (1.1) via a lamellar connection (2). The clamping hub (5) has a clamping hub slot (5.1) which extends section by section through the clamping hub flange (5.4) in both the axial and radial directions. Furthermore, the clamping hub flange (5.4) a clamping hub bore (5.3) with internal thread. Under the By using the clamping hub screw (5.2), the clamping hub flange (5.4) can be elastically deformed, so that the inner diameter of the clamping hub (5) narrows and thus a shaft, which is not shown in Figure 2, is clamped without play in the clamping hub (5). A clamping ring hub (6) is shown on the right side of the torque measuring coupling (1). This hub consists of a clamping ring hub flange (6.1), which is connected to the strain gauge sleeve (1.1) via a lamellar connection (2), and a clamping ring (6.3). The clamping ring hub flange (6.1) has at least one axially extending clamping ring hub slot (6.2). A clamping ring (6.3) is mounted on the clamping ring hub flange (6.1) in the area of ​​the clamping ring hub slot (6.2). The clamping ring (6.3) is interrupted by a clamping ring slot (6.6). At least one clamping ring bore (6.5) with an internal thread is arranged in the area of ​​the clamping ring slot (6.6). The clamping ring screw (6.4) allows the clamping ring (6.3) and, consequently, the clamping ring hub flange (6.1) to be elastically deformed and thus tapered. In this way, a shaft (not shown in Figure 2) can be clamped without backlash. Reference symbol list: A shaft axis S distance 1 Torque measuring coupling 1.1 Strain gauge sleeve 1.2 Expansion sleeve 1.3 Sleeve section 1.4 Coil ring 1.5 Protective tube 1.6 Pipe mounting 1.7 Absorber film 1.8 coil 1.9 Potting compound 1.10 Printed circuit board 1.11 Expansion rivet 1.12 Strain gauges 1.13 Flange 1.14 Threaded hole 1.15 Mounting screw 1.16 Contact area 1.17 Exclusion 1.18 Threaded hole with radius countersink 1.19 Cones 1.20 Cable feedthrough 2 lamella connection 2.1 Slat package 2.2 Lamella 2.3 Flanged bushing 2.4 Ring 2.5 screw 2.6 Mother 3 hub 3.1 Hub flange 3.2 Tension ring hub 3.3 Tension ring 3.4 Tensioning screw 4 Stator 5 clamping hub 5.1 Clamping hub slot 5.2 Clamping hub screw 5.3 Clamping hub bore 5.4 Clamping hub flange 6 Clamping ring hub 6.1 Clamping ring hub flange 6.2 Clamping ring hub slot 6.3 Clamping ring 6.4 Clamping ring screw 6.5 Clamping ring bore 6.6 Clamping ring slot

Claims

AMENDED CLAIMS received by the International Bureau on 11 October 2023 (11.10.2023) Claim 1 Torque measuring coupling (1 ) consisting of a stator (4) and a torque-transmitting strain gauge sleeve (1.1 ), characterized in that the strain gauge sleeve (1.1 ) is constructed in multiple parts from a strain gauge sleeve (1.2) and a flange (1.13) attached thereto, wherein a coil ring (1.4) axially surrounds the strain gauge sleeve (1.2) section by section and radially and has an inner diameter which is smaller than the outer diameter of the flange (1.13), wherein the coil ring (1.4) is a closed, non-divisible ring and wherein the coil ring (1.4) accommodates a protective tube (1.5). Claim 2 Torque measuring coupling (1 ) according to claim 1 , characterized in that the strain measuring sleeve (1.1 ) is connected on one or both sides to a hub (3, 5, 6) via a lamellar connection (2). Claim 3 Torque measuring coupling (1 ) according to at least one of the preceding claims, characterized in that the coil ring (1.4) is made of an aluminum alloy or of a plastic or of a fiber-reinforced material. Claim 4 Torque measuring coupling (1 ) according to at least one of the preceding claims, characterized in that the coil ring (1.4) is pressed or glued onto the expansion sleeve (1 .2). Claim 5 Torque measuring coupling (1 ) according to at least one of the preceding claims, characterized in that the coil ring (1.4) serves as a support for a coil (1 .8) and for a printed circuit board (1.10). Claim 6 Torque measuring coupling (1) according to at least one of the preceding claims, characterized in that the AMENDED SHEET (ARTICLE 19) The protective tube (1.5) is arranged concentrically to the expansion sleeve (1.2) between the coil ring (1.4) and the expansion sleeve (1.2) and surrounds the sleeve section (1.3) radially outwards. Claim 7 Torque measuring coupling (1 ) according to claim 6, characterized in that the protective tube (1 .5) together with a tube receptacle (1 .6) of the expansion sleeve (1.2) and by means of a potting compound (1 .9) in the coil ring (1.4) seals tightly, so that no liquid, dust-like or viscous substances can penetrate into the space between the protective tube (1 .5) and the expansion sleeve (1.2). Claim 8 Torque measuring coupling (1 ) according to claim 2, characterized in that the torsionally stiff and flexurally elastic lamellar connection (2) between the hubs (3, 5, 6) and the strain measuring sleeve (1.1 ) enables angular, lateral and axial offset compensation. Claim 9 Torque measuring coupling (1 ) according to claim 2, characterized in that the lamellar connection (2) between the hubs (3, 5, 6) and the strain measuring sleeve (1.1 ) is free of play. Claim 10 Torque measuring coupling (1 ) according to at least one of the preceding claims, characterized in that the circuit board (1.10) includes an acceleration sensor which is suitable for measuring vibrations. Claim 11 Method for assembling a torque measuring coupling (1 ) consisting of a stator (4) and a torque-transmitting component constructed from an expansion sleeve (1.2) and a flange (1.13) attached thereto Strain gauge sleeve (1.1) characterized in that a protective tube (1.5) is first connected to a closed, non-divisible coil ring (1.4), then a coil (1.8) is inserted into the coil ring (1.4) and potted with a potting compound (1.9), only then is the coil ring (1.4) positioned on the expansion sleeve (1.2), whereupon a circuit board (1.10) is inserted into the coil ring (1.4) and wired to the coil (1.8) and strain gauges (1.12), before the circuit board (1.10) is also potted with the potting compound (1.9), and subsequently a flange (1.13) is connected to the expansion sleeve (1.2) in a torque-transmitting manner. AMENDED SHEET (ARTICLE 19)

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