Patent Description:
Couplings for connecting two rotating elements in a drive train, comprising a main coupling device configured to be connected to each of said rotating elements and including at least one membrane made of fibre-reinforced plastic for transmitting torque and for compensating axial and/or radial and/or angular displacement between said rotating elements, are known e.g., from <CIT> and <CIT>. Compensating couplings allow for compensation of axial, radial and/or axial displacements between the axes of rotation of rotating elements of a drive train through at least one membrane. The membrane is usually arranged in a plane substantially perpendicular to the axis of rotation and on the one hand sufficiently stiff for transmitting torque but on the other hand flexible enough to deform elastically thereby providing the desired compensating effect. The membrane may have a corrugated or wavy structure for enhancing the intended deformation.

Typical applications of such compensating couplings include drive trains of ships and the like requiring transmission of high torque while attenuating transmission of vibrations. Compensation couplings may for example be arranged in a drive shaft of a maritime application between an engine and a gearbox. Such applications are characterised by rugged environment. In the event of failure of the main coupling device, manoeuvrability of a vessel may be impaired since the gear box could be cut off from the engine.

A compensating coupling for connecting two rotating elements in a drive train, comprising the features of the preamble portion of claim <NUM> is known from <CIT>. Further couplings are known from<CIT> and <CIT>.

The object of the present invention is to provide an alternative compensating compling that allays safety concerns about the ability to transmit torque especially in respect of the membrane.

Accordingly, the present invention provides a compensating coupling for connecting two rotating elements in a drive train, comprising the features of claim <NUM>.

The auxiliary coupling device adds a take-me-home function to a compensating coupling having a membrane of fibre-reinforced plastic.

In the first position, the protrusions are spaced apart from the openings e.g. by a gap in circumferential direction. The gap is dimensioned to avoid contact as long as the main coupling device remains working for torque transmission, and to enable engagement upon failure or breakage of the main coupling device.

In the event of failure of the membrane or any other portion of the main coupling device, the auxiliary coupling device is able to provide torque transmission, which for a maritime application means maintaining manoeuvrability. Under normal operation, however, the auxiliary coupling device is disengaged so that the main coupling device can show its full potential of compensating displacements and torque will be transmitted solely via the main coupling device.

In one preferred embodiment, the first and second auxiliary coupling members include sleeve portions, which together radially encapsulate the main coupling device. This will in addition protect the main coupling device against damage from outside, for example during maintenance work in an area around the coupling.

In a further preferred embodiment, a fire-resistant fibre-reinforced layer is laminated on the outer circumference of the first and second auxiliary members to further protect the main coupling device against damage, in particular fire, to thereby increase reliability of the compensating coupling.

In another preferred embodiment, the sleeve portions are made of fibre-reinforced plastic to thereby keep the weight of the rotating parts low. This is also beneficial for implementation of a fire-resistant fibre-reinforced layer as an outer layer.

Furthermore, each of the first and second auxiliary coupling members may comprise two or more segments forming said sleeve portions, the segments being detachably connected with each other in circumferential direction of the main coupling device. This simplifies assembly and disassembly of the auxiliary coupling device. The auxiliary coupling may thus be fitted on a main coupling device which has already been mounted in a drive train. Considering the size of compensation couplings, space considerations may require a segmented auxiliary coupling device. A segmented auxiliary coupling device may also be passed through narrow openings more easily. The sleeve portion of either of the first or second axillary coupling members may be segmented in two three, four or even more parts.

In a further preferred embodiment, the segments have axial flanges extending radially from the sleeve portion, neighbouring segments contacting each other and being connected with each other at their axial flanges. The axial flanges not only simplify connection of the segments for forming the sleeves but also define ribs in lengthwise direction of the coupling, parallel to the axis of rotation, increasing the rigidity of the respective first and second auxiliary coupling members.

According to yet another preferred embodiment the projections may be formed by cylindrical bolts secured to the first auxiliary coupling member. Such bolts can be easily mounted on a first auxiliary coupling member even when made of fibre-reinforced plastic.

In particular, the first auxiliary coupling member may have a radial flange portion at an axial end of its sleeve portion while the projections protrude axially from said radial flange portion.

Preferably, the openings are formed by holes on a radial flange portion at an axial end of the sleeve portion of the second auxiliary coupling member. Such holes can be provided easily in a second auxiliary coupling member when made of fibre-reinforced plastic.

The bolts are preferably made of steel and are thus built to last under high-torque.

In a further preferred embodiment, each bolt has a rubber sleeve for contacting the rim of the corresponding hole in the second position. The rubber sleeve may reduce the impact on the rim of the hole and also attenuate the transmission of vibrations when the compensating coupling is operated via the auxiliary coupling device.

Additionally, the rim of each hole may be reinforced by a metal ring, respectively, which is embedded in the fibre-reinforced plastic material of the flange portion of the second axillary coupling member.

In a further preferred embodiment, the arrangement of bolts and holes may be replaced by a formation of toothed edges on the first and second auxiliary coupling members to form the projections and openings of the auxiliary coupling device.

In a further preferred embodiment, connection holes on the main coupling device and on the auxiliary coupling device for connecting same to one of the flanges of the drive train are aligned with each other. It is thus possible to mount the main coupling device and the auxiliary coupling device with the same connectors on the corresponding rotating element, e.g., flange of the drive train. Accordingly, the structure of the rotating element of the drive train remains simple and does not require any separate means for mounting the auxiliary coupling device.

It is, however, also possible to provide individual means for connecting the main coupling device and the axillary coupling device separately on a rotating element of a drive train. In other words, in another embodiment, the main coupling device and the auxiliary coupling device are separately secured to the rotating elements by individual connection means, so that the auxiliary coupling device can be mounted later than the main coupling device or be removed independently.

The invention will be described in greater detail hereinafter with reference to the accompanying drawings in which:.

<FIG> and <FIG> show a compensating coupling <NUM> for connecting two rotating elements <NUM> and <NUM> of a drive train. The compensating coupling <NUM> is arranged between said rotating elements <NUM> and <NUM> and configured to connect to a first rotating element <NUM>, e.g. a flange or shaft, and to a second rotating element <NUM>, e.g. a flange or shaft, of the drive train. One of the rotating elements <NUM> may be coupled to an engine while the other of said rotating elements <NUM> may be coupled to a gear box.

The compensating coupling <NUM> comprises a main coupling device <NUM> and an auxiliary coupling device <NUM>. The main coupling device <NUM> is intended to transmit torque under normal operation conditions whereas the auxiliary coupling device <NUM> is disengaged as long as the main coupling device <NUM> remains to be working. Under normal operation conditions the auxiliary coupling device <NUM> does not transmit torque. The auxiliary coupling device <NUM> provides an emergency function in the event the main coupling device <NUM> fails, i.e. is no longer able to sufficiently transmit torque. In this case the auxiliary coupling device <NUM> engages to bypass the main coupling device <NUM> and thereby maintain torque transmission of the drive train.

The main coupling device <NUM> of the embodiment in <FIG> includes at least one membrane <NUM> made of fibre-reinforced plastic for transmitting torque and for compensating axial and/or radial and/or angular displacement between said rotating elements <NUM> and <NUM> of the drive train. Thus at least one membrane <NUM> is arranged in a plane substantially perpendicular to the axis A of rotation of the drive train and sufficiently stiff for transmitting torque but flexible enough to deform elastically and thereby provide the desired compensating effect. The membrane <NUM> may have a corrugated or wavy structure for enhancing the intended deformation. If the membrane <NUM> fails, torque transmission via the main coupling device may be disrupted.

In the embodiment shown in <FIG> the main coupling device <NUM> includes two membranes <NUM> at axial end portions of two axial tubes <NUM> which in turn are connected at their ends opposite to the membranes <NUM> with each other by bolts <NUM>. Each of the membranes <NUM> is surrounded radially by an annular connecting portion <NUM> having openings <NUM> for securing the main coupling device <NUM> to the respective rotating element <NUM> and <NUM>. The ends opposite to the membranes <NUM> are bent radially outwardly to define flanges <NUM> for the bolts <NUM>.

One membrane <NUM>, one axial tube <NUM>, one annular connecting portion <NUM> and one flange <NUM> may be integrally formed from fibre-reinforced plastic material. Two of such structures are connected by the bolts <NUM>.

It is however to be emphasised, that the structure of the main coupling device <NUM> as shown in <FIG> is of exemplary nature only and may be replaced by any other type of coupling having at least one membrane <NUM> for compensating axial, radial and/or angular displacements. For example, the main coupling device <NUM> maybe one as shown in <CIT> or <CIT>, though the invention is not limited to any of these main coupling devices <NUM> either.

The auxiliary coupling device <NUM> includes a first auxiliary coupling member <NUM> configured to be connected to one of said rotating elements <NUM> and a second auxiliary coupling member <NUM> configured to be coupled to the other of said two rotating elements <NUM> of the drive train.

The first auxiliary coupling member <NUM> and the second auxiliary coupling member <NUM> are arranged around the radial outer circumference of the main coupling device <NUM>. In order to protect the main coupling device <NUM> against damage from outside, the first auxiliary coupling member <NUM> and the second auxiliary coupling member <NUM> may radially encapsulate the main coupling device.

Further, the first auxiliary coupling member <NUM> has projections <NUM> extending axially into openings <NUM> provided on the second auxiliary coupling member <NUM>. The projections <NUM> and openings <NUM> are arranged in a way that in a first position the projections <NUM> and openings <NUM> are disengaged, i.e., do not contact each other, thereby disabling torque transmission via the auxiliary coupling device <NUM>. In a second position however, which is obtained through rotation of the first and second auxiliary coupling members <NUM>, <NUM> relative to each other e.g. in the event of breakage or failure of the main coupling device <NUM>, the projections <NUM> and the openings <NUM> engage in circumferential direction for enabling torque transmission via the auxiliary coupling device <NUM>.

Each of the first auxiliary coupling member <NUM> and the second auxiliary coupling member <NUM> includes a tubular sleeve portion <NUM>, <NUM> extending around a portion of the main coupling device <NUM> and terminating at both axial ends in radial flange portions <NUM>, <NUM>, <NUM> and <NUM> that are bent radially outwardly from the tubular sleeve porti24ns <NUM>, <NUM>. Preferably, the first and second auxiliary coupling members <NUM> and <NUM>, in particular their tubular sleeve portions <NUM>, <NUM> as well as their radial flange portions <NUM> to <NUM> are made of fibre-reinforced plastic.

Further, each of the first and second auxiliary coupling members <NUM> and <NUM> may be subdivided in two or more segments 21A, 21B, 21C, 21D, 22A, 22B, 22C, 22D that together form the sleeve portions <NUM>, <NUM>, respectively and may as well include the radial flange portions <NUM> to <NUM>. The segments 21A, 21B, 21C, 21D, 22A, 22B, 22C, 22D of each of the first and second auxiliary coupling members <NUM> and <NUM> are detachably connected with each other in circumferential direction of the main coupling device <NUM>. It is therefore possible to mount the auxiliary coupling device <NUM> on a main coupling device <NUM> that is already connected to the first and second rotating elements <NUM> and <NUM>.

The segments 21A, 21B, 21C, 21D, 22A, 22B, 22C, 22D may be provided with axial flanges <NUM> extending radially from the sleeve portions <NUM>, <NUM>. Neighbouring segments 21A, 21B, 21C, 21D, 22A, 22B, 22C, 22D contact each other and are connected with each other at their axial flanges <NUM>.

Pairs of axial flanges <NUM>, which may be connected by bolts <NUM>, define outer ribs <NUM> extending in lengthwise direction of the auxiliary coupling device <NUM> in parallel to the axis of rotation A of the compensating coupling <NUM> to thereby reinforce the structure of the respective first and second auxiliary coupling members <NUM> and <NUM>.

Together with the radial flange portions <NUM> to <NUM>, the axial flanges <NUM> define pockets at the outer circumference of the sleeve portions <NUM> and <NUM>.

The radial flange portions <NUM> and <NUM> at the opposite axial ends of the auxiliary coupling device <NUM> are secured to the respective rotating elements <NUM> and <NUM> of the drivetrain, e.g. by sandwiching the annular portions <NUM> of the main coupling device <NUM> in between. Corresponding connection holes on the main coupling device <NUM> and the auxiliary coupling device <NUM> for connecting same to one of the rotating elements <NUM>, <NUM> of the drive train may be aligned with each other so that they can be mounted together via the same connectors <NUM>. It is, however, also possible, to connect the radial flange portions <NUM> and <NUM> of the auxiliary coupling device <NUM> separately from the main coupling device <NUM> to the rotating elements <NUM> and <NUM>.

The inner radial flange portions <NUM> and <NUM> of the first and second auxiliary coupling members <NUM> and <NUM> do not contact each other but in fact are axially spaced apart from each other.

In the embodiment shown in <FIG> and <FIG>, these inner radial flange portions <NUM> and <NUM> are provided with the said projections <NUM> and openings <NUM>.

The projections <NUM> may be formed by bolts, preferably cylindrical bolts <NUM> that are secured to the first auxiliary coupling member <NUM>, in particular its inner radial flange portion <NUM> and arranged in a way to protrude axially towards the second auxiliary coupling member <NUM>.

The openings <NUM> may be formed by holes <NUM> on the inner radial flange portion <NUM> of the second auxiliary coupling member <NUM>. Each of the holes <NUM> receives one of the bolts <NUM>. However, since the diameter of the bolts <NUM> is smaller than that of the holes <NUM>, a radial gap <NUM> remains between the outer circumference of the bolt <NUM> and the inner rim <NUM> of the corresponding hole <NUM> in the first position, as already mentioned above. In other words, in the first position the bolts <NUM> do not contact the rims <NUM> of the holes <NUM> or any further portion of the second auxiliary coupling member <NUM>, so that no torque will be transmitted in this disengaged state of the auxiliary coupling device <NUM> which is shown in <FIG>. In the event of failure of the main coupling device <NUM>, the first and second auxiliary coupling members <NUM> and <NUM> may rotate relative to each other so that the bolts <NUM> will contact the rims <NUM> of the holes <NUM> to thereby transmit torque and thus bypass the main coupling device <NUM> as shown in <FIG>.

The bolts <NUM> may be made of steel and optionally may further include an outer rubber sleeve <NUM> to reduce impact forces on the rim <NUM> and attenuate vibrations in the bypass mode of the compensating coupling <NUM>.

Further each of the holes <NUM> may be reinforced by a metal ring <NUM> defining the corresponding rim <NUM> and preferably embedded in the fibre-reinforced plastic material of the corresponding radial flange <NUM>.

In an alternative embodiment, the bolts <NUM> and openings <NUM> are replaced by an alternative engagement structure for defining the projections <NUM> and openings <NUM> of the auxiliary coupling device <NUM>. As shown in <FIG>, projections <NUM> and openings <NUM> may as well be formed e.g. by toothed edges <NUM> and <NUM> on the first and second auxiliary coupling members <NUM> and <NUM>. In the first position, again, the teeth of these edges <NUM> and <NUM> are spaced apart from each other, i.e. are disengaged for avoiding the transmission of any torque via the auxiliary coupling device <NUM>, whereas in the second position the teeth engage in circumferential direction to thereby transmit torque and bypass the main coupling device <NUM>.

Finally, a fire-resistant fibre-reinforced layer <NUM> may be laminated on the outer circumference of the first and second auxiliary members <NUM>, <NUM> to further protect the main coupling device <NUM> against damage, in particular fire, to thereby increase reliability of the compensating coupling <NUM>. The fire-resistant fibre-reinforced layer may be included as outer layer in a multi-layered fibre-reinforced structure of the first and second auxiliary coupling members <NUM> and <NUM>.

Claim 1:
Compensating coupling (<NUM>) for connecting to two rotating elements (<NUM>, <NUM>) of a drive train, comprising:
a main coupling device (<NUM>) configured to be connected to each of said rotating elements (<NUM>, <NUM>) and including at least one membrane (<NUM>) for transmitting torque and for compensating axial and/or radial and/or angular displacement between said rotating elements (<NUM>, <NUM>), and
an auxiliary coupling device (<NUM>) having a first auxiliary coupling member (<NUM>) configured to be connected to one of said two rotating elements (<NUM>) and a second auxiliary coupling member (<NUM>) configured to be coupled to the other of said two rotating elements (<NUM>),
wherein the first auxiliary coupling member (<NUM>) has projections (<NUM>) extending axially into openings (<NUM>) provided on the second auxiliary coupling member (<NUM>) such that in a first position the projections (<NUM>) and openings (<NUM>) are disengaged thereby disabling torque transmission via the auxiliary coupling device (<NUM>), and in a second position,
obtainable through rotation of the first and second auxiliary coupling members (<NUM>, <NUM>) relative to each other, the projections (<NUM>) and openings (<NUM>) engage in circumferential direction for enabling torque transmission via the auxiliary coupling device (<NUM>),
characterized in that
said at least one membrane (<NUM>) is made of fibre reinforced plastic,
the first auxiliary coupling member (<NUM>) and the second auxiliary coupling member (<NUM>) are respectively arranged around the outer radial circumference of the main coupling device (<NUM>).