GB2159240A

GB2159240A - Flexible shaft couplings

Info

Publication number: GB2159240A
Application number: GB08511719A
Authority: GB
Inventors: Harald Hoffeld
Original assignee: Voith Turbo GmbH and Co KG
Current assignee: Voith Turbo GmbH and Co KG
Priority date: 1984-05-14
Filing date: 1985-05-09
Publication date: 1985-11-27
Also published as: GB8511719D0; ATA109985A; AT391002B; DE8414654U1

Abstract

In a shaft coupling 10 of the type comprising at least one transfer element between its two coupling halves 11 and 12, consisting of annular discs 20, 21, fixed by screw connections with interposed tightening discs 22 and 23 on flanges 13, 14 of the coupling halves wherein on both side of the transfer element is disposed an annular safety disc 26,27 respectively, which is held on the opposite coupling half, while it encases the tightening discs of the adjacent coupling half with play, a shoulder 37 of a coupling half 12 engages in the circular inner bore 28 of an adjacent safety disc with slight radial play, and the tightening discs 22,23, the transfer element 20,21 and the safety discs 26,27 are held together in the region of each screw connection by a connecting element, such as a shoulder casing 33, rivet, or the like, and consequently form a structural unit, the shoulder casing receiving the shank 34 of a tight-fit screw 17 of the screw connection. <IMAGE>

Description

SPECIFICATION Shaft coupling which is torsionally stiff yet flexible The invention relates to a shaft coupling of the type which is torsionally stiff yet flexible and which comprises at least one transfer element disposed between its coupling halves at right angles to the axis of rotation, consisting of an annular disc or plates, which is fixed by screw connections and interposing tightening discs disposed on both sides alternately on flanges of the coupling halves, whereby on both sides of the transfer element between the screw head or nut and the tightening disc is disposed an annular safety disc respectively and it is held form-locking and/or force-locking by the screw connecticas of the opposite coupling halves, while the tightening discs of the adjacent coupling half are encased by the respective safety disc with play.

Such a shaft coupling is known from Germany Offenlegungsschrift 16 75 257. There the flanges of both coupling halves have a greater diameter than the transfer element which is shaped like an annular disc. This results in an increased external diameter of the shaft coupling but without increasing its transmitting capacity. The transfer element in the known shaft coupling is fixed with tight-fit screws to both the coupling halves. The nuts fitted on the tight-fit screws of one coupling half engage with clearance in an assigned bore in the flange of the other coupling half.

The purpose of this is to provide an emergency drive for the shaft coupling if the transfer element fails. However, this measure is detrimental to the accessibility of the screw connections and consequently to the installation or exchange of the transfer element.

Moreover the screw connections hold safety discs on the respective coupling half so as to ensure centrifugal protection if a transfer element breaks. For this purpose the safety discs are provided with axially projecting shoulders which interlock with little clearance. Such discs are, however, particularly expensive in manufacture. Finally the known shaft coupling has the disadvantage that the transfer element and the safety discs, and also the tightening discs acting on both sides of the transfer element, do not become mutually assigned until assembly by the tight-fit screws. However this considerably hinders assembly work.

The object of the invention is to create a compact method of construction from simply constructed components suitable for assembly with a shaft coupling of the type discussed above.

According to this invention, a shaft coupling of the type discussed above is characterised by the features set out in Claim 1.

The invention provides the advantage that on the one hand the centrifugal protection of the shaft coupling is achieved by simply constructed discs and on the other hand all components to be inserted between the two coupling halves are combined to make one structural unit which can be fixed to the respective coupling halves with little work being required.

Advantageous refinements of the invention are provided by the features characterised in the sub-claims.

With the feature of Claim 2 the outer diameter of the shaft coupling is limited to the smallest possible dimension prescribed by the transfer element.

With the feature of Claim 3 good accessibility to the screw connections is attained.

The feature of Claim 4 has the purpose of bringing about the correct positioning of the mentioned components with regard to one another and preventing a locating pin leaving its bore during the operation of the shaft coupling.

The feature of Claim 5 brings about a favourable stress pattern on the transfer element in the clamping area at the respective coupling half.

An exemplified embodiment of the invention is explained in more detail below with reference to the drawings, in which: Figure 1 is an axial section of a shaft coupling having a structural unit disposed between the coupling halves and consisting substantially of annular disc-shaped transfer elements, safety discs and tightening discs, the said unit being alternately fixed to the coupling halves.

Figure 2 is a view of the shaft coupling seen in the direction of arrow Il in Fig. 1, Figure 3 is an axial section through the mentioned structural unit, Figure 4 is a section of the annular discshaped transfer element seen in the direction of arrow IV in Fig. 3, Figure 5 is a view according to Fig. 4 of a safety disc on the structural unit and Figure 6 is a view of a tightening disc of the structural unit, also seen in the direction of arrow IV in Fig. 3.

A shaft coupling marked by 10 has two coupling halves 11 and 12, which are provided with a flange 1 3 or 14 on their side turned towards one another (Fig. 1). Between the flanges 1 3 and 14 of the two coupling halves 11 and 1 2 extends a structural unit 1 6 disposed at right angles to the axis of rotation 1 5 of the shaft coupling 10, the said unit connecting the coupling halves with each other stiff against torsion but flexibly.The structural unit 1 6 is fixed with tight-fit screws 1 7 disposed uniformly on the peripheral side every 60 with nuts 1 8 alternately on flanges 1 3 and 14 of the two coupling halves 11 and 1 2 (Fig. 2). So that the screw connections are easily accessible, each flange 1 3 or 1 4 is shortened in the radial direction in the region of the screw coupling sitting on the other flange, so that it ends with clearance in front of the respective head 1 9 of the tight-fit screw 17.

The structural unit 1 6 represented in section in Fig. 3 has as a transfer element two annular discs 20 and 21 covering one another (Fig. 4). In the region of each screw connection two tightening discs 22 and 23 abut the outer sides of the two annular discs 20 and 21 turned away from one another. The tightening discs 22 and 23 are approx. triangular and are constructed symmetrically along their longitudinal axis 24 (Fig. 6). This axis 24 coincides with the respective radial 25 proceeding from the axis of rotation 1 5 of the shaft coupling 10 and running through one of the six screw connections of the structural unit 16.The two tightening discs 22 and 23 provided for each screw connection have different thickness: The tightening disc 22 disposed towards the screw head 1 9 is very much thinner than the other tightening disc 23 assigned to the corresponding coupling flange 1 3 or 14.

The structural unit 1 6 is, moreover, provided with two safety discs 26 and 27, which are supported by interposing the thin tightening discs 22 against the adjacent annular discs 20 and 21. The completely flat safety discs 26 and 27 manufactured from sheets and also the annular discs 20 and 21 have the same external diameter as flanges 13 and 14 of the two coupling halves 11 and 1 2.

The safety discs 26 and 27 represented in Fig. 5 in front view have a circular inner bore 28. Moreover they are provided with a pinhole image from a large bore 29 and a smaller bore 30 spaced every 1 20'. The same pinhole image is also achieved with the tightening discs 22 and 23 and also with the annular discs 20 and 21 spaced every 60 .

The safety discs 26 and 27 have open recesses 32 towards their outer edge 31, and these are also spaced every 120 and displaced by 60 in relation to the pinhole images. These are proportioned so that they partly encase a tightening disc with little play, as is shown in Fig. 5 with dot-dash lines.

The two annular discs 20 and 21, the tightening discs 22 and 23 as well as the safety discs 26 and 27 are placed on top of the other with aligning bores 29 and 30. Only the safety discs 26 and 27 are rotated from their coincident position by 60 , so that the recesses 32 surround the assigned thicker tightening discs 23 with play. In each bore 29 sits a shoulder casing 33 which is flanged at the end in the tightening disc 23. This casing 33 assists the mutual assignment and centring of the individual parts of the structural unit 16. At the same time the casings 33 serve to receive the shank 34 of the tight-fit screws 1 7 In the small bores 30 of the discs sits a pin 35, which secures the tightening discs 22 and 23 against torsion.So that the pin 35 can not leave its bore 30, the bore is covered on the side turned away from the respective coupling flange 1 3 or 14 by the shoulder 36 of the casing 33.

As is seen in Fig. 1, the flange 14 of the coupling half 1 2 has an axially projecting shoulder 37. This shoulder 37 engages in the internal bore 28 of the safety disc 27 with little radial play in the case of structural unit 1 6 mounted on both coupling halves 11 and 1 2. In the event of the fracture of the annular discs 20 and 21 the shoulder 37 of the coupling half 1 2 comes to abut the safety disc 27 so that centrifugal protection is provided.

With broken annular discs 20 and 21 a mutual rotation of the two coupling halves 11 and 1 2 occurs, which results in the thick tightening discs 23 abutting the edge of the assigned recess 32 of the safety discs 26 and 27. This guarantees emergency drive. Moreover the safety discs 26 and 27 fulfill the task of receiving a part of the centrifugal forces acting on the tight-fit screws 1 7 with the operation of the shaft coupling 10, and in fact with coupling half 11 by the safety disc 27 and with coupling half 1 2 by the safety disc 26.

With the design of the structural unit 1 6 described it is possible to fasten any side of it to the respectively coupling half 11 or 1 2. If necessary only a slight rotation of the structural unit 1 6 is required in order to insert the tight-fit screws 1 7 through the shoulder casing 33.

Instead of shoulder casings 33 and pins 35, as an alternative to the exemplified embodiment described the annular discs 20 and 21, the tightening discs 22 and 23 and also the safety discs 26 and 27 may also be penetrated by rivets or rivets and pins in the region of the fixings. These elements also serve to assign and centre the individual parts of the structural unit 1 6 and also to protect the tightening discs against torsion.

Claims

1. A shaft coupling of the type which is torsionally stiff yet flexible and which comprises at least one transfer element disposed between its coupling halves at right angles to the axis of rotation, consisting of an annular disc or plates, which is fixed by screw connections and interposing tightening discs disposed on both sides alternately on flanges of the coupling halves, whereby on both sides of the transfer element between the screw head or nut and the tightening disc is disposed an annular safety disc respectively and it is held form-locking and/or force-locking by the screw connections of the opposite coupling halves, while the tightening discs of the adjacent coupling half are encased by the respective safety disc with play, characterised in that the safety discs (26,27) are flat, in that a shoulder (37) of the adjacent coupling half (12) engages with slight radial play in the circular inner bore (28) of a safety disc (27), and in that the tightening discs (22,23), the transfer element (20, 21) and the safety discs (26,27) are held together form-locking in the region of each screw connection by at least one conncting element, such as a shoulder casing (33), rivet or the like, whereby the shoulder casing receives the shank (34) of a tight-fit screw (17) of the screw connection.

2. A shaft coupling according to Claim 1, characterised in that the safety discs (26,27) and the transfer element (20,21) have the same external diameter as the flanges (13,14) of the coupling halves (11,12).

3. A shaft coupling according to Claim 1 or 2, characterised in that the flanges (1 3,14) of the coupling halves (11, 12) are shortened in the radial direction in the region of the screw connection (17,18) of the other respective coupling half, so that they end with clearance in front of the free end of the screw connection.

4. A shaft coupling according to Claim 1, characterised in that the tightening discs (22,23) are constructed non-circular and together with the transfer element (20,21) and a safety disc (26,27) are penetrated by a pin (35), whose bore (30) is covered on the side turned away from the flange by the edge (36) of the shoulder casing (33).

5. A shaft coupling according to Claim 4, characterised in that the tightening discs (22,23) are roughly triangular with the axis of symmetry (24) lying on the radial (25).

6. A shaft coupling constructed, arranged and adapted for use substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.