DE102020209660A1 - shaft-hub connection - Google Patents

Abstract

The present invention relates to a shaft-hub connection (1) with a shaft (10) with at least one shaft groove (10a), with a hub (11) with at least one hub groove (11a) and with at least one feather key (12), which is received in sections by the shaft groove (10a) and in sections by the hub groove (11a). The shaft-hub connection (1) is characterized in that the feather key (12) has an elastomer element (12b) at least in sections, which is accommodated both in sections by the shaft groove (10a) and in sections by the hub groove (11a).

Description

The present invention relates to a shaft-hub connection according to the preamble of patent claim 1.

For the rotational transmission of forces or torques, shafts can be used on the input or output side, which are connected to another machine element such as a gear wheel, a V-ribbed pulley or the like to a machine element such as a toothed belt, a V-belt, another gear wheel or the like are connected. Such machine elements can also be referred to as a hub.

The hub can be fixedly connected to the shaft, for example by surface pressure. Here, a frictional connection applied over the circumference between shaft and hub is used as a shaft connection, in that the applied pressure and the friction pairing caused thereby prevent a relative movement between shaft and hub in the circumferential direction and thereby enable torque transmission.

The disadvantage here is that such a non-positive connection has its limits when a maximum permissible torque is exceeded as the maximum load. Then the non-positive connection is released "suddenly", which turns into sliding friction and thus enables a relative movement of shaft and hub to each other. This leads to a strong reduction in the torques that can then be transmitted between shaft and hub via sliding friction.

An alternative possibility of power/torque transmission of a shaft-hub connection can be a form fit between shaft and hub by means of a third element such as a feather key or a shear pin or bolt. The key is usually a solid, elongated piece of metal with a rectangular cross-section, which is inserted into a corresponding keyway in the shaft and protrudes radially therefrom. The associated hub has a continuous groove and is pushed axially over the feather key for assembly. The feather key acts as a driver due to the positive fit on its flanks in the circumferential direction and, in the case of a drive shaft, transmits the torque of the shaft via the hub to the component to be driven or, in the case of an output shaft, the torque of the driving component via the hub to the shaft to be driven. In the axial direction, the hub can be secured against shifting on the shaft for axial fixation on the shaft shoulder, for example by means of a retaining ring or slotted nut.

Since such a form-fitting shaft-hub connection using a feather key can, with appropriate dimensioning or design, transmit very high torques, which can be higher than the permissible torques of the shaft, the hub or other machine elements, such feather keys can also be used as a shear pin, or shear pin for short , be educated. Such shear pins are designed, for example, by means of a notch as a material weakening at a predetermined point as a predetermined breaking point to break when a predetermined excessive torque is reached between the shaft and hub due to the excessive shearing stress then occurring. A shear pin as a mechanical lock then breaks, so that the shaft and hub can move freely relative to one another in the circumferential direction and torque can no longer be transmitted, but the shaft and hub remain guided towards one another. In this way, the shaft, hub and other machine elements can be protected against overload.

However, the disadvantage of a form fit between the shaft and hub using a feather key is that this results in a firm, direct or rigid and therefore dynamically “hard” connection. This allows neither a certain tolerance in the angular position between the shaft and hub nor a certain decoupling in the event of overload or an oscillating additional load application around a peak value. The use of bolts or shear pins also corresponds to a hard load transfer.

In other words, the form-fitting connection between the hub and the shaft precludes a decoupling that is sought as a safety solution in the event of overload by means of the feather key that transmits the load. As a safety component, a suitable overload protection such as a slipping clutch or a flexible plate must therefore be provided elsewhere as an element that secures the entire shaft.

A targeted decoupling of individual load strands driven via a central shaft is therefore only possible at said load application point by using a shear pin or shear bolt. Shear pins or shear bolts generally have a predetermined breaking point defined by a notch, which fails if the maximum shear stress is exceeded by sliding in the notch and thus implements an additional safety function in addition to load transfer. However, since a notch can be regarded as the classic starting point of a dynamically induced crack, a swelling dynamic upper load in combination with a base load that is applied anyway must be regarded as detrimental to the service life of the shear pin or shear bolt. It consists of unfavorable conditions, there is always a risk of the shear pin or shear bolt failing before the upper load actually defined in the design is reached in continuous operation.

Another disadvantage is that neither a force-locking shaft-hub connection nor a form-locking shaft-hub connection allows damping of higher-frequency load peaks and/or load shocks introduced into the load transmission system - both from the driving and from the driven side. without the need for a considerable design effort for the individual drive or driven element applied to a main shaft, for example by means of torsion dampers or springs applied to the shaft as a temporary energy store.

An object of the present invention is to provide a shaft-hub connection of the type described at the outset, which can offer both reliable and dynamic torque transmission with overload protection. In other words, a shaft-hub connection with increased dynamic suitability and overload protection should be made available, i.e. a combination of the design features of a metal feather key with those of a shear pin and additional dynamic damping. This should be able to take place as simply as possible, in a space-saving, cost-effective manner and/or with little maintenance. At the very least, an alternative to known shaft-hub connections of this type should be created.

The object is achieved according to the invention by a shaft-hub connection with the features according to claim 1. Advantageous developments are described in the dependent claims.

The present invention thus relates to a shaft-hub connection with a shaft with at least one shaft keyway, with a hub with at least one hub keyway and with at least one feather key, which is partially accommodated by the shaft keyway and partially by the hub keyway.

The shaft-hub connection according to the invention is characterized in that the feather key has an elastomer element, at least in sections, which is accommodated both in sections by the shaft groove and in sections by the hub groove. In other words, a previously known rigid, for example purely metallic, feather key is replaced by a component which assumes the function of the feather key and is at least partially made of an elastomeric material.

The present invention is based on the knowledge that in the case of known rigid feather keys, the torques are transmitted in a correspondingly direct or hard manner, which does not permit any damping. This also applies to shear pins or shear bolts.

According to the invention, at least one elastomer element is therefore introduced at least in sections into the power flow between the shaft and the hub, which elastomer element can enable a damping effect between the shaft and the hub due to the properties of its elastomeric material. In this way, damping can be introduced into the power flow between the shaft and the hub, so that in particular higher-frequency excitations can be at least partially damped directly at the transition between the shaft and the hub. This can introduce an elastomeric damping effect in the power flow between shaft and hub and avoid the need for damping in the power flow elsewhere or at least reduce or supplement it.

In other words, by integrating an elastomer body within a form-fitting connection, this connection can be given a soft characteristic due to the elastic properties of the elastomer body, which can cushion peak loads, comparable to the principle of shock absorption.

It is also advantageous that the feather key according to the invention can be designed as a shear pin at the same time, in that the elastomeric element of the feather key is arranged and designed in such a way that shear forces act on the elastomeric element due to the transmission of the torques between the shaft and the hub and this is released when it is reached or can shear off when a predetermined shearing force is exceeded. As a result, the safety function of a shear pin can also be taken over by the feather key according to the invention. This safety function can prevent overloading in a predetermined manner due to a shear strength that can be adjusted by the material properties and/or by the shape of the elastomer body and is significantly lower than, for example, metals. In this way, protection against any machine damage in the further course of the drive train due to an overload that would otherwise be introduced can be achieved.

In other words, according to the invention, a dynamic damper element with implemented overload protection can be arranged in the respective drive train, which is used to reduce load peaks and their retransmission to the drive through a short-term storage of the introduced impulse energy in the event of a load input from the output side and can thus serve to protect the system. Thus, by using the significantly lower shear strength of an elastomeric material as a feather key compared to metal, this feather key according to the invention can also be used as overload protection in addition to the actual load transmission. By using, for example, an elastomer-metal connection as a load transfer element, it can be possible to create a certain bandwidth of deformation in relation to the damping properties of a load transfer element created in this way by using different elastomers in the actual shear field.

In other words, by using appropriate rubber elements or rubber-metal elements within the form fit, vibration-related decoupling of individual drive trains from a central drive shaft unit can be created in the smallest of spaces. By using a shaft-hub connection according to the invention, individual output lines, which are driven by means of a central shaft, can be integrated both in a form-fitting manner and at the same time in an elastic and therefore dynamically “soft” manner. The flat construction element pressed in the shear plane or under load can counteract dynamic load peaks within certain limits through a certain elastic deformation and decouple them from the system.

According to one aspect of the invention, the elastomer element is arranged at least in the plane between the shaft and the hub. This can promote or enable the design of the feather key as a shear pin.

According to a further aspect of the invention, the feather key is formed entirely by the elastomeric element. This can simplify the implementation of the feather key or make it more cost-effective. This can also increase the absorption of dynamic loads on the part of the feather key, since a correspondingly large amount of elastomeric material is available for the elastic storage of energy.

According to a further aspect of the invention, the key has a key element on the shaft side, which is received by the shaft groove, and the key has a key element on the hub side, which is received by the keyway, the elastomer element, preferably at least essentially, particularly preferably completely, radially, is arranged between the shaft-side key element and the hub-side key element. The shaft-side feather key element and the hub-side feather key element can be designed rigidly, for example as a metal plate, in order to achieve a firm hold in relation to the shaft groove or hub groove. This can improve or ensure the positioning or retention of the feather key both in the shaft groove and in the hub groove.

According to a further aspect of the invention, the shaft-side key element is held in a form-fitting manner in the shaft groove and/or the hub-side key element is held in a form-fitting manner in the hub groove. This can be achieved by a corresponding design or contouring of the shaft-side feather key element and shaft groove to one another and/or of the hub-side feather key element and hub groove to one another. In this way, a form-fitting positioning of the feather key in the shaft groove and/or in the hub groove can be achieved as easily but reliably as possible.

According to a further aspect of the invention, the shaft-side key element is held in the shaft groove by means of a pin and/or the hub-side key element is held in the hub groove by means of a pin. Although this can increase the expense of fastening the feather key in the shaft groove and/or in the hub groove, it improves the positioning accuracy and/or the hold of the feather key.

According to a further aspect of the invention, the feather key has at least one shear force sensor which is at least partially in contact with the elastomer element, the shear force sensor being arranged at least substantially perpendicularly to the radial direction of the shaft-hub connection. In other words, a sensor element is integrated into the feather key according to the invention in such a way that loads acting on the feather key, at least essentially as shearing forces, can be detected by sensors. For this purpose, the sensor element can be completely embedded in the elastomeric material or arranged at the edge of the elastomeric material at the transition to a feather key element as described above.

Such loads can occur in particular as a result of torques in the circumferential direction between the shaft and the hub and thus act in the cylindrical plane which runs in the circumferential direction at a constant radius around the longitudinal axis of the shaft. Correspondingly, the shear force sensor can be arranged at least essentially and preferably precisely in this cylindrical plane in order to at least essentially extend to out finally to detect the loads acting in the cylindrical plane as shear forces using sensors.

The shearing forces detected by sensors can be made available, for example, to a control unit of the device, such as a machine or plant, which uses the shaft-hub connection according to the invention, as will be described in more detail below. This information can be further processed there and used, for example, to monitor the device with regard to overloads and to react in the event of an imminent overload by reducing the power to be transmitted or even by stopping the device. Additionally or alternatively, this information can be used for servicing and maintenance and in particular for predictive maintenance.

This aspect of the invention is based on the knowledge that a determination of the respective proportionally tapped shaft power is generally only possible directly in the respective load trains, but not on the central shaft unit per se. This leads to the fact that the corresponding space for the necessary sensors must be created at various points in the system.

A central recording of the torque values delivered in relation to the total power along the shaft as the main shaft or as the vertical shaft can therefore make the problem much easier. When a device such as a machine or plant is in operation, knowledge of the loads occurring within different load chains that do not act independently of one another can provide information as to whether it is being used as intended, or whether wear and tear or increased external loads are causing wear on individual components due to overloading of the respective drive or output train.

Therefore, the implementation of at least one load sensor can be provided according to the invention, which allows conclusions to be drawn about the locally transmitted current torque component of the output train by determining the elastic deformation occurring during operation of the output trains placed on a main shaft, preferably under load. By integrating a flat shear sensor horizontally in the elastomer, it is then possible to use the elastic deformations, which are much larger than in metals, for example, with the same tension for a signal pick-up by means of the sensor. As a result, an overall finer resolution can also be made possible with relatively inexpensive sensor technology.

According to a further aspect of the invention, the shear force sensor is arranged between the shaft-side key element and the elastomer element, or the shear force sensor is arranged between the hub-side key element and the elastomer element. This can enable the sensory detection of loads at the transition between the elastomeric element and the corresponding feather key element.

According to a further aspect of the invention, the shear force sensor is designed to receive electrical energy wirelessly and/or to generate electrical energy. In this way, at least the shear force sensor and possibly additional electronics can be operated without using a wired supply of electrical energy and/or having to provide an electrical energy store for this purpose. This can avoid a corresponding expense for the cable routing, which can be disruptive or expensive, particularly on the rotating shaft. Likewise, an electrical energy store can be avoided, which can require additional installation space.

A wireless transmission of electrical energy by the device that uses the shaft-hub connection according to the invention can take place, for example, by means of electromagnetic fields. A corresponding transmitter can be provided by the device in the vicinity of the shaft without affecting the shaft-hub connection. Nevertheless, a certain distance between the transmitter and the key cannot be avoided, which can lead to losses in wireless energy transmission.

The generation of electrical energy on the part of the feather key can be obtained, for example, from the movements which can be caused within the elastomeric material of the feather key by dynamic loads. This can be done, for example, by means of at least one piezoelectric element. Additionally or alternatively, electrical energy can be obtained from the feather key from the temperature or from the temperature change, which can arise in the feather key, in particular when there is a change in the power to be transmitted. This can enable the generation of electrical energy exactly there, namely on the feather key, where the electrical energy is also required. As a result, losses in the energy transmission, whether wired or wireless, can be avoided. There is no need for the feather key to store electrical energy or at least be lower in capacity and thus in costs and space. On the other hand, the generation of electrical energy by the feather key can require additional installation space there and/or lead to additional costs for the feather key.

According to a further aspect of the invention, the shear force sensor is designed to receive and/or transmit information wirelessly. This can avoid the use of cables, in particular on the rotating shaft, for the transmission of information or data, in particular of the shear force sensor. The wireless data transmission can take place in one direction or in both directions by means of electromagnetic waves.

According to a further aspect of the invention, the feather key has at least one pressure sensor which is at least partially in contact with the elastomer element, the pressure sensor being arranged at least essentially in the radial direction of the shaft-hub connection.

In addition or as an alternative to the shear force sensor described above, the feather key can thus have a further or alternative sensor element, which is designed and aligned accordingly to detect loads at least essentially in the radial direction and thus at least essentially perpendicular to the cylindrical plane of the shaft. This can enable the collection and use of corresponding information about the loads, at least essentially in the radial direction. This can also serve the purposes described above. In other words, by installing a flat pressure sensor, particularly on the contact surface between the elastomer body and the shaft groove and/or the hub groove, it can be made possible to determine the applied load via the pressure detected by sensors.

According to a further aspect of the invention, the pressure sensor is designed to receive electrical energy wirelessly and/or to generate electrical energy. As a result, the corresponding aspects of the shear force sensor described above can also be transferred to the pressure sensor.

According to a further aspect of the invention, the pressure sensor is designed to receive and/or transmit information wirelessly. As a result, the corresponding aspects of the shear force sensor described above can also be transferred to the pressure sensor.

The present invention can be applied to any type of torque transmission by means of a shaft with tapping of the same via at least one hub applied by positive locking, in which it is of interest to transmit said torque "softly" and thereby achieve a certain dynamic decoupling of the strands, ie between the drive train and the driven train. In addition, through the corresponding deformation, a possibility can be created to implement a shear force sensor and/or a pressure sensor and to combine this possibility for sensory load detection with an overload protection.

• 1 einen schematische Längsschnitt durch eine erfindungsgemäße Welle-Nabe-Verbindung; und
• 2 einen schematische Längsschnitt durch eine Passfeder der erfindungsgemäßen Welle-Nabe-Verbindung.

An exemplary embodiment and further advantages of the invention are explained below in connection with the following figures. It shows:

• 1 a schematic longitudinal section through an inventive shaft-hub connection; and
• 2 a schematic longitudinal section through a key of the shaft-hub connection according to the invention.

The above figures are described in cylindrical coordinates with a longitudinal axis X, a radial direction R perpendicular to the longitudinal axis X and a circumferential direction U running around the longitudinal axis X.

A shaft-hub connection 1 according to the invention has a shaft 10, for example in the form of a drive shaft 10, and a hub 11, for example as a machine element 11, which can be designed as a gear wheel 11 or as a shaft washer 11, for example. In the cylindrical surface of the shaft 10, a shaft groove 10a is formed as a radial depression, which extends in the longitudinal direction X substantially. Facing the shaft 10, a hub groove 11a is formed as a radial depression in the cylindrical surface of the hub 11, which likewise extends essentially in the longitudinal direction X. The shaft groove 10a of the shaft 10 and the hub groove 11a of the hub 11 are designed and arranged to correspond to one another in terms of shape or contour.

The shaft groove 10a of the shaft 10 and the hub groove 11a of the hub 11 jointly accommodate a feather key 12 . The hub groove 11a of the hub 11 extends in the representation of 1 to the left in the longitudinal direction X up to the edge of the hub 11, so that the feather key 12 is inserted in the shaft groove 10a of the shaft 10 in the radial direction R and then the hub 11 in the longitudinal direction X in the representation of FIG 1 from the right over the Shaft 10 together with the feather key 12 can be guided and secured (not shown).

According to the invention, the key 12 is designed in such a way that a key element 12a on the shaft side is designed in the form of a base plate 12a on the shaft side of the key 12 as a rigid metal plate, which is held with a precise fit or positive fit by the bottom of the shaft groove 10a of the shaft 10. A corresponding hub-side feather key element 12c in the form of a hub-side base plate 12c of the feather key 12 is also accommodated by the hub groove 11a of the hub 11 . In the radial direction R, an elastomer element 12b or an elastomeric element 12b in the form of an elastomer body 12b is arranged between the shaft-side key element 12a and the hub-side key element 12c and is connected to these in a materially bonded manner by vulcanization. The feather key 12 is essentially formed by the elastomeric element 12b, which therefore also runs completely in the cylindrical plane that forms the transition from the shaft 10 and the hub 11.

Dynamic loads in the circumferential direction U can be partially absorbed by means of the elastomeric element 12b of the feather key 12 and, as a result, high-frequency vibrations between the shaft 10 and the hub 11 in particular can be at least partially damped. This can enable or improve the vibration damping of the shaft-hub connection 1 and/or keep the effort required for this low. In particular, this dynamic vibration damping can take place precisely at the transition between shaft 10 and hub 11, which can be particularly effective.

According to the invention, a shear force sensor 12d is also provided at the transition between the elastomeric element 12b and the shaft-side key element 12a of the key 12 . The sensor element of the shear force sensor 12d is connected to the shaft-side feather key element 12a by adhesive bonding, for example, and to the elastomeric element 12b of the feather key 12, for example by vulcanization. The sensor element of shear force sensor 12d runs in the cylindrical plane of shaft 10, so that shear forces resulting from the loads between shaft 10 and hub 11 can be detected directly at the transition between shaft 10 and hub 11 by means of shear force sensor 12d. This information can be used for monitoring or predictive maintenance of the shaft-hub connection 1 according to the invention.

According to the invention, on the other hand, a pressure sensor 12e is embedded within the material of the elastomeric element 12b. The pressure sensor 12e is aligned in the circumferential direction U in order to detect pressure forces by sensors, which can result from the loads on the intermediate shaft 10 and hub 11 . This information can also be used for monitoring or predictive maintenance of the shaft-hub connection 1 according to the invention.

Reference List

R

radial direction

u

circumferential direction

X

longitudinal axis

1

shaft-hub connection

10

Wave; drive shaft

10a

Shaft groove of the feather key 12

11

Hub; machine element; Gear; wave washer

11a

Keyway of the key 12

12

Adjusting spring

12a

shaft-side key element; shaft-side base plate of the feather key 12

12b

Elastomeric element or elastomeric element of the feather key 12; Elastomer body of the feather key 12

12c

hub-side key element; hub-side base plate of the feather key 12

12d

Key shear force sensor 12

12e

Key pressure sensor 12

Claims (13)

Shaft-hub connection (1) with a shaft (10) with at least one shaft groove (10a), with a hub (11) with at least one hub groove (11a) and with at least one feather key (12), which extends from the shaft groove ( 10a) and is received in sections by the hub groove (11a), characterized in that the feather key (12) has at least in sections an elastomer element (12b) which is received both in sections by the shaft groove (10a) and in sections by the hub groove (11a). will. Shaft-hub connection (1) according to claim 1 , characterized in that the elastomeric element (12b) is arranged at least in the plane between the shaft (10) and the hub (11). Shaft-hub connection (1) according to claim 1 or 2 , characterized in that the feather key (12) is formed entirely by the elastomeric element (12b). Shaft-hub connection (1) according to claim 1 or 2 , characterized in that the feather key (12) has a shaft-side feather key element (12a) which is received by the shaft groove (10a), and in that the feather key (12) has a hub-side feather key element (12c) which is received from the hub groove (11a) is received, wherein the elastomer element (12b) is arranged, preferably at least essentially, particularly preferably completely, radially between the shaft-side key element (12a) and the hub-side key element (12c). Shaft-hub connection (1) according to claim 4 , characterized in that the shaft-side key element (12a) is held positively in the shaft groove (10a) and/or that the hub-side key element (12c) is held positively in the hub groove (11a). Shaft-hub connection (1) according to claim 4 , characterized in that the shaft-side feather key element (12a) is held in the shaft groove (10a) by means of a pin and/or that the hub-side feather key element (12c) is held in the hub groove (11a) by means of a pin. Shaft-hub connection (1) according to one of the preceding claims, characterized in that the feather key (12) has at least one shear force sensor (12d) which is in contact with the elastomer element (12b) at least in sections, the shear force sensor (12d) is arranged at least essentially perpendicular to the radial direction (R) of the shaft-hub connection (1). Shaft-hub connection (1) according to one of Claims 4 until 6 and after claim 7 , characterized in that the shear force sensor (12d) is arranged between the shaft-side key element (12a) and the elastomer element (12b) or that the shear force sensor (12d) is arranged between the hub-side key element (12c) and the elastomer element (12b). Shaft-hub connection (1) according to claim 7 or 8th , characterized in that the shear force sensor (12d) is designed to receive electrical energy wirelessly and / or to generate electrical energy. Shaft-hub connection (1) according to one of Claims 7 until 9 , characterized in that the shear force sensor (12d) is designed to receive and / or send information wirelessly. Shaft-hub connection (1) according to one of the preceding claims, characterized in that the feather key (12) has at least one pressure sensor (12e) which is in contact with the elastomer element (12b) at least in sections, the pressure sensor (12e) is arranged at least essentially in the radial direction (R) of the shaft-hub connection (1). Shaft-hub connection (1) according to claim 11 , characterized in that the pressure sensor (12e) is designed to receive electrical energy wirelessly and / or to generate electrical energy. Shaft-hub connection (1) according to claim 11 or 12 , characterized in that the pressure sensor (12e) is designed to receive and / or send information wirelessly.

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