DE102016110577B4 - Key for determining a transmitted torque - Google Patents

Abstract

Key for determining a transmitted torque between a shaft (50) and a hub (60), each having a groove (55, 65), comprising: a main body (100) having a first limiting portion (110), a second Limiting portion (120) and a connecting portion (130), wherein the connecting portion (130) connects the first limiting portion (110) with the second limiting portion (120) and the base body (100) in the groove (55) of the shaft (50) and the groove (65) of the hub (60) is insertable to transmit the torque via the connecting portion (130); anda sensor assembly (200) configured to generate a sensor signal in response to a deformation of the connecting portion (130) that depends on the transmitted torque, the first limiting portion (110) and the second limiting portion (120) being monolithically formed, and the first restricting portion (110) and the second restricting portion (120) are located at different angular positions of the shaft (50) or the hub (60) after insertion of the key.

Description

The present invention relates to a feather key for determining a transmitted torque, and more particularly to a modified feather key which is capable of detecting transverse forces transmitted therefrom and thus torques.

background

A feather key produces a positive shaft-hub connections and serves to transmit torques between the shaft (eg a drive) and the hub (eg a component or a pickup). Frequently coupled to a shaft a plurality of components to be driven by the shaft. In such configurations, however, it is generally not known which torque is transmitted to which component of the shaft. The same applies to the opposite case, when the components transmit torques or when a part of the components receive a torque, while other components exert a reverse torque. The prior art includes the following torque rims. In the DE 10 2010 045 449 B4 An arrangement for detecting the torque transmitted by a shaft is disclosed. DE 102 05 089 A1 discloses a measuring device for relatively guided components. DE 10 2004 057 148 A1 discloses a feather key for non-rotatably connecting a shaft to a hub. DE 10 2006 052 529 A1 discloses a device for detecting an overload of a shaft-hub connection and DD 245 931 A1 discloses a keyway connection for transmitting torques.

In such applications, often only the total torque can be measured, but not the transmitted torque to individual components.

Therefore, there is a need for a torque measurement that can locally determine for a given device which torque is being transferred between the shaft and the device (i.e., the corresponding hub).

Summary

The above object is achieved by a feather key according to claim 1. The dependent claims relate to advantageous developments of the feather key according to claim 1.

The present invention relates to a key for determining a transmitted torque between a shaft and a hub, each having a groove. The feather key comprises a base body and a sensor arrangement. The main body comprises a first limiting section, a second limiting section and a connecting section, wherein the connecting section connects the first limiting section to the second limiting section. The main body can be inserted in the groove of the shaft and in the groove of the hub in order to transmit the torque via the connecting section. The sensor assembly is configured to generate a sensor signal in response to deformations of the connection portion, which depends on the transmitted torque. The first boundary portion and the second boundary portion are monolithically formed and are located at various angular positions of the shaft or hub after insertion, the angle being measured, for example, about the axis of rotation.

In particular, the key may be capable of transmitting torque in both directions (e.g., from and to the shaft) and determining their value, the two cases being different by the sign or direction of the torque vector. According to embodiments, the torques are determined by deformations of the connecting portion. Transmitted torques lead to expansions or compressions of the connecting section, which can be detected by the sensor arrangement. If the sensor arrangement is designed to detect both a compression and an expansion, a single sensor element can already be sufficient to detect torques in both directions. In further embodiments, the sensor assembly is accordingly configured to detect a direction of transmitted torque.

Often, however, it is advantageous if the sensor arrangement has a plurality of sensor elements. For example, the sensitivity can be increased when bending stresses are detected instead of uniaxial compressions. In order to take advantage of this effect, the connecting portion may be formed to expand at different surface areas depending on the transmitted torque (particularly, its direction). Then various sensor elements can be attached to these surface areas. In other embodiments, this is accomplished by a sensor assembly having a plurality of sensor elements along the connecting portion at positions that vary differently depending on the direction of the torque to thereby determine the direction of the torque.

It is also possible for at least two sensor elements to be arranged on two sections of a surface region of the connection section, in regions which occur at a torque transmission in the same direction or in the opposite direction deform (eg wave-shaped). Thereby, the mean value of the obtained sensor signals or a difference signal can be used as a sensor signal for the determination or the determination of the torque. Therefore, in other embodiments, the sensor assembly includes a plurality of sensor elements formed on a same surface or on opposite surfaces of the connection portion.

In embodiments, the said deformations are achieved by a base body having a N-shape or an H-shape in a cross-section perpendicular to the torque. In particular, the N-shape can offer the advantage that, in the case of loads in one direction, it comes to pure compressive stresses and, in the case of a load in the opposite direction, to an additional bending. This achieves high sensitivity in this direction. The angle between the connecting portion and the first limiting portion and / or the second limiting portion may in particular be non-rectangular. In further embodiments, however, any intermediate shape may be formed, wherein the connecting portion may be at any angle to the parallel formed boundary sections. Therefore, the connection portion may contact the first restriction portion (or the second restriction portion) either centrally or at one of its end points or at any intermediate point. This is advantageous if the transmitted torque is mainly in one direction or in one direction is typically greater than in the opposite direction and so an excessive deformation can be avoided.

In further embodiments, the sensor assembly includes at least one strain gauge or piezo element configured to detect a deformation of the connection portion in response to a transmitted torque.

For example, the strain gauges or piezo elements can be formed at positions that deform particularly strongly during the transmission of the torque, thereby achieving a high sensitivity. In addition, transducers of the strain gauges or piezo elements can be arranged in different directions (also as superposition or intersecting) so as to be able to detect deflections in different directions (about different axes) at one position.

In further exemplary embodiments, the first limiting section and the second limiting section comprise at least one line-shaped contact zone, so that during the transmission of the torque the shaft and the hub only come into contact with the main body along the line-shaped contact zone. These contact zones make it possible to precisely define the load introduction points.

The line-shaped contact zones may, for example, be formed in an end region along the radial direction of the shaft. However, it is also possible to consciously not form the line-shaped portions at the end portions, but at any other position along the first and second limit portions, thereby utilizing a lifting action and thus enhancing or weakening the bending of the connecting portion.

In further embodiments, the base body includes at least one spacer that protrudes in a direction parallel (or antiparallel) to the transmitted torque from the body to maintain a distance to a neighboring component. This makes it possible to arrange a plurality of keys along the shaft and the hub (in the respective grooves) so as to keep a space between them. In this way, if several components are driven by the shaft, the feather keys can not slip, so that their position is fixed along the shaft. The spacers can therefore ensure the most correct positioning of the individual feather keys for driving the individual components. For example, it may be advantageous to arrange the feather keys as centrally as possible along the hub or to keep a minimum distance from an edge. In addition, the spacers may be offset from one another on opposite sides of the base body, so that the spacers are not in contact with each other in adjacent keyways, but contact the base body.

In further embodiments, the base body is monolithically formed from a material. Thus, embodiments achieve a higher stiffness and a better load capacity (especially in connection with the N-shape). In addition, the main body may extend homogeneously in a direction parallel to a direction of the torque.

1. (i) Vermeidung von Störeinflüssen auf die Messung aufgrund von anderen Drehmomenten (zum Beispiel aus Lagern);
2. (ii) eine lokale Auflösung der anfallenden Drehmomente je Bauelement ist möglich - nicht nur die Erfassung des Gesamtdrehmomentes je Achse; und
3. (iii) der einfache Aufbau ermöglicht geringe Fertigungskosten.

Compared to conventional methods of torque measurement, feather keys offer the advantage that the torque can be detected directly at the point of torque transmission. Conventional measuring methods measure only that resulting total torque per shaft. The direct measurement at the point of transmission offers the following advantages:

1. (i) avoiding interference with the measurement due to other torques (for example, from bearings);
2. (ii) a local resolution of the resulting torques per component is possible - not only the detection of the total torque per axis; and
3. (iii) the simple construction allows low manufacturing costs.

Thus, a spatial distribution of the transmitted torques along the components, which are arranged on a given shaft, is achieved inexpensively by simple means.

list of figures

• 1 zeigt eine Passfeder gemäß einem Ausführungsbeispiel der vorliegenden Erfindung.
• 2A zeigt eine Welle und eine Nabe mit jeweils einer Nut.
• 2B zeigt eine in die Nut der Welle/Nabe eingesetzte Passfeder.
• 3A zeigt eine Draufsicht auf die Passfeder mit der Sensoranordnung gemäß einem Ausführungsbeispiel.
• 3B zeigt eine Aufreihung von Passfedern entlang der Drehmomentrichtung, wobei die Passfedern durch Abstandshalter auf Abstand gehalten werden.

The embodiments of the present invention will be better understood from the following detailed description and the accompanying drawings of the different embodiments, which should not be construed as limiting the disclosure to the specific embodiments, but for explanation and understanding only.

• 1 shows a feather key according to an embodiment of the present invention.
• 2A shows a shaft and a hub, each with a groove.
• 2 B shows a key inserted in the groove of the shaft / hub.
• 3A shows a plan view of the feather key with the sensor arrangement according to an embodiment.
• 3B shows an alignment of feather keys along the torque direction, wherein the feather keys are held by spacers at a distance.

Detailed description

1 shows a feather key according to an embodiment of the present invention. The feather key has a base body 100 and a sensor arrangement 200 on. The main body 100 includes a first limiting section 110 , a second limiting section 120 and a connection section 130 , The connecting section 130 connects the first boundary section 110 with the second boundary section 120 , The sensor arrangement 200 is adapted to be responsive to deformations of the connecting portion 130 to generate a sensor signal which depends on a transmitted torque (eg degree of bending). The first boundary section 110 and the second boundary section 120 are monolithic.

The main body 100 can be made of any material which is capable of transmitting torques and at the same time being able to deform (without breaking) so as to measure the value of the torque. Advantageously, the material should readily enable attachment of exemplary strain gages or piezo sensors at various locations. Steel would be an example material that can meet these requirements.

The geometry of the key is chosen such that expansions can be detected by the exemplary strain gauges. Optionally, in addition to the amount of torque and the direction of rotation can be determined. This can be done, for example, by arranging the sensor arrangement at a predetermined position on the connecting section. The predetermined position may be a position that deforms in a certain way when transmitting a torque depending on the transmitted torque. Thus, torque in one direction can cause elongation and compression in the opposite direction.

The embodiment of the 1 further shows that a first line-shaped contact zone 111 and a second line-shaped contact zone 112 on a tangential outer surface of the first restriction section 110 are formed. In the same way, a first line-shaped contact zone 121 and a second line-shaped contact zone 122 also on a tangentially outwardly directed surface of the second boundary section 120 educated. The tangential direction refers to a tangential direction of the rotational movement, when the exemplary key was inserted into the grooves of the shaft or hub. The contact zones 111 . 112 . 121 . 122 are thus opposite to those surfaces on which the force point of the connecting portion 130 to the respective limiting section 110 . 120 coupled.

The linear contact zones 111 . 112 . 121 . 122 are used to load application in the exemplary key and ensure that the transmitted torques reproducible signals in the sensor array 200 cause, as the force acting on the exemplary key always at a fixed position, at which the line-shaped contact zones 111 . 112 . 121 . 122 take place.

In the embodiment of the 1 includes the first limiting section 110 also a first spacer 115 and the second boundary section 120 a second spacer 125 in the direction of the transmitted torque (or opposite thereto) from the main body 100 protrude. The spacers 115 . 125 serve to ensure a distance between a plurality of successively arranged feather keys or from an edge.

2A shows a cross-sectional view through a shaft 50 and by a radially outer hub 60 , where the wave 50 a groove 55 and the hub 60 a groove 65 and the cross-sectional view is shown perpendicular to the torque direction. The exemplary key from the 1 is in the grooves 55 . 65 Can be used to torque over the connecting section 130 transferred to. The result is in the 2 B shown. The first boundary section 110 and the second boundary section 120 extend radially outward and contact at tangentially opposite portions of the groove 55 the wave 50 and the groove 65 the hub 60 , After insertion, thus are the first limiting section 110 and the second boundary section 120 at different angular positions of the shaft 50 or the hub 60 ,

In the embodiment shown, moreover, several sensor elements 210 . 220 . 230 . 240 at different positions on the connecting section 130 arranged. When the wave 50 a torque on the hub 60 transmits acts, for example, a force F on the second line-shaped contact zone 122 , which is equal to the counterforce F, which points to the second linear contact zone 112 the first limiting section 110 acts. This force has the consequence that on the connecting section 130 in a first area a first force F1 and in a second area, a second force F2 acts, with the first area closer to the second contact zone 112 the first limiting section 110 is considered the second area. The first force F1 and the second force F2 cause the deformation of the connecting portion 130 passing through the sensor elements 210 . 220 . 230 . 240 can be found as strains and / or compressions.

The four sensor elements shown 210 . 220 . 230 . 240 are shown only by way of example. In further embodiments, more or less sensor elements may be present. For example, one or two sensor elements are sufficient for many applications 210 . 240 to determine the effective torque with sufficient accuracy. In particular, if only one direction of torque is to be expected, in the simplest embodiment only one sensor element is needed 210 be present, the position of which may advantageously comprise a point of greatest deformation.

In addition, the shows 2 an optional opening 140 through the connecting section 130 , By the example, wiring for contacting the sensor elements 210 , ..., 240 can be placed. The wirings may also extend to a control module (not shown) that receives the sensor signals from the sensor elements 210 ... 240 evaluates and forward a result to a central control unit. For example, the control module may be in one of the cavities 150 on both sides of the connecting section 130 accommodated and at the connecting sections 130 be attached.

In many applications, it is sufficient to measure the deformations in the transmission of torque by means of strain gauges as sensor element (s). As a result, deformations can be determined directly and closed based on the applied load.

In the embodiment shown, the key in the cross-sectional view has an N-shape, wherein the positions of the line-shaped contact zones 111 . 112 . 121 . 122 the force points and thus also the deformations of the connecting section 130 influence. However, this form can also be chosen differently. For example, an H-shape or an N-shape with non-linear connection portion 130 to get voted. It is advantageous in any case to choose a shape that meets the desired requirements and still deformed sufficiently, thereby measuring the torque can.

The positions of the linear contact zones 111 . 112 . 121 . 122 can also be chosen such that for different torques to be transmitted, a leverage is provided, which can be adjusted depending on the expected torques. This allows for a desired deformation of the connecting portion 130 Be influenced. For example, the amount or location of the deformation can be controlled.

3A shows a plan view of the feather key from the 1 , so that on the surface area of the connecting portion 130 the sensor arrangement 200 becomes visible. The sensor arrangement shown 200 may in turn comprise one or more sensor elements, which in the 3A not shown. In addition, the shows 3A the two spacers 115 . 125 extending on opposite sides along the torque direction (perpendicular to the plane of the drawing 2A . 2 B) protrude from the body. The spacers serve to position the feather key along the shaft or to ensure a minimum distance to adjacent components or an edge.

3B shows an arrangement with three feather keys along the shaft 50 (The torque direction therefore extends horizontally in the 3B) , The spacers 115 . 125 are thus suitable for multiple components, each with a hub 60 over a wave 50 drive. Embodiments allow the transmitted torques between the shaft 50 and the individual components can be detected separately by the individual feather keys.

In contrast to conventional feather keys, the embodiments thus offer the advantage that not only the resulting total torque is detected, but all transmitted torques can be spatially resolved. This is especially an advantage when on the shaft 50 several components / consumers are arranged in parallel, all of which are to be driven by the shaft and where other torque measurements are difficult to perform (eg in rolls of roll forming). In addition, by directly detecting the torques disturbing influences in the joining zones, which is caused for example by a friction in the bearings, can be minimized.

In further embodiments, a control unit (not shown) may further be provided, which controls the sensor signals of the sensor arrangement 200 evaluates and based on a feedback for the drive of the shaft 60 provides. However, these sensor signals can also be used for fault detection if, for example, one of the components receives an unexpectedly high torque.

Embodiments of the present invention may be summarized as follows:

Embodiments relate to feather keys for transmitting forces between a shaft 50 and a hub 60 , which are characterized in that the feather key a gutter (connecting portion 130 ) and two flanges (first and second boundary sections 110 . 120 ) having. In addition, at least one linear contact surface on the feather key 111 . 112 . .. , be formed, which protrudes from a flange of the key so that a contact for transmitting tangential forces F between the key and the hub 60 there comes about. The second linear contact zone 122 may protrude from the key so that a contact surface between the key and the shaft 50 can be used to transmit the tangential forces.

The key may for example comprise a steel material to transmit the torque safely.

In addition, the shape of the feather key can be chosen so that when loaded in at least one direction between the shaft 50 and the hub 60 to be transmitted force in addition to a compressive force and an optional bend in the web (connecting portion 130 ). Thus, it can (eg when using the N-shape) depending on the stresses to pure compressive stresses or to additional bends, whereby a high sensitivity in this direction can be achieved. This stress of the web can then be detected by means of a local measurement of the deformation. Therefore, the key is modified such that at least a part thereof provides deformation in the transmission of the torque. For example, strain gauges can be used as a direct measuring body for determining the transmitted torque. Therefore, the direct measurement of loads in a keyway connection by the key according to the present invention is possible.

The features of the invention disclosed in the description, the claims and the figures may be essential for the realization of the invention either individually or in any combination.

LIST OF REFERENCE NUMBERS

50

wave

55

Groove on the shaft

60

hub

65

Groove on the hub

100

body

110, 120

first, second limiting section

111,112

line-shaped contact zones on the first limiting section

121.122

line-shaped contact zones on the second boundary section

115.125

spacer

130

connecting portion

140

Opening through the connecting portion

150

Cavities on both sides of the connecting section

200

sensor arrangement

210, 220, ...

first, second, ... sensor element of the sensor arrangement

Claims (11)

Key for determining a transmitted torque between a shaft (50) and a hub (60), each having a groove (55, 65), having the following features: a base body (100) having a first restriction portion (110), a second restriction portion (120), and a connection portion (130), wherein the connection portion (130) connects the first restriction portion (110) to the second restriction portion (120), and the Main body (100) in the groove (55) of the shaft (50) and the groove (65) of the hub (60) is insertable to transmit the torque via the connecting portion (130); and a sensor arrangement (200) which is designed to generate a sensor signal which depends on the transmitted torque in response to a deformation of the connection section (130), wherein the first restricting portion (110) and the second restricting portion (120) are monolithic, and the first restricting portion (110) and the second restricting portion (120) are at different angular positions of the shaft (50) or the hub (60) after insertion of the key ) are located. Feather key Claim 1 wherein the base body (100) has an N-shape or an H-shape in a cross-section perpendicular to the torque, or the connecting portion (130) has a non-right angle with the first restriction portion (110) and / or with the second restriction portion (120) forms. Feather key Claim 1 or Claim 2 wherein the sensor assembly (200) is configured to detect a direction of transmitted torque. Key according to one of the preceding claims, wherein the sensor arrangement (200) a plurality of sensor elements (210, 220, 230, ...), which are arranged along the connecting portion (130) at different positions, wherein at the different positions different deformations due to transmitted torque occur. Key according to one of the preceding claims, wherein the sensor arrangement (200) comprises a plurality of sensor elements (210, 220, 230, ...) which are formed on a same surface or on opposite surfaces of the connecting portion (130). Key according to one of the preceding claims, wherein the sensor arrangement (200) comprises at least one strain gauge, which is designed to detect a deformation of the connecting portion (130) in response to the transmitted torque. Key according to one of the preceding claims, wherein the first limiting section (110) and / or the second limiting section (120) at least one line-shaped contact zone (111, 121, ...), so that when transmitting the torque, the shaft ( 50) and / or the hub (60) only come into contact with the base body (100) along the line-shaped contact zone (s) (111, 121,...) And thus define defined load introduction points. Key according to one of the preceding claims, wherein the base body (100) has at least one spacer (115, 125, ...) which protrudes in parallel to a transmitted torque from the main body (100) to a position of the key along the shaft ( 50) or to define a distance to a neighboring device. Key according to one of the preceding claims, wherein the base body (100) is monolithically formed from a material. Key according to one of the preceding claims, wherein the base body (100) extends homogeneously parallel to a direction of the torque. Key according to one of the preceding claims, wherein the sensor arrangement further comprises a control module for evaluating the sensor signal and the connecting portion comprises an opening (140), wherein a connection for transmitting the sensor signal through the opening (140) extends.

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