GB2592977A

GB2592977A - Generator accessory drive

Info

Publication number: GB2592977A
Application number: GB2003624.0A
Authority: GB
Inventors: Kelly Anthony
Original assignee: Safran Electrical and Power SAS
Current assignee: Safran Electrical and Power SAS
Priority date: 2020-03-12
Filing date: 2020-03-12
Publication date: 2021-09-15
Anticipated expiration: 2040-03-12
Also published as: GB202003624D0; GB2592977B

Abstract

An input drive arrangement 1 of a generator 3 arranged to be driven by an aircraft engine 2 such as a gas turbine engine. The input drive arrangement comprises a disconnect device 100, such as a clutch, comprising a drive transfer means having a connected configuration and a disconnected configuration. The drive transfer means is configured to transfer a rotational drive between an input shaft of the generator and a rotor of the generator when in the connected configuration, and to disconnect the input shaft from the rotor when in the disconnected configuration. The input drive arrangement further comprises an accessory drive member 128, arranged to rotate with the input shaft to output power to at least one accessory of the generator; wherein the accessory drive member is connected to the input shaft such that it continues to rotate with the input shaft when the drive transfer means is in the disconnected configuration. The accessory drive member may drive a fluid pump, a further generator 194 or a pulley. The pump may be used for providing lubricating or cooling fluid to the system. A further aspect of the present invention provides an aircraft engine assembly and an aircraft comprising the input drive arrangement.

Description

Generator Accessory Drive

Technical Field

The invention relates to a disconnect device for disconnecting a rotational drive of an aircraft engine from a generator driven by the aircraft engine.

Background of the Invention

Aircraft engines, such as jet or turbojet engines, can comprise electrical generators which generate electricity used by the aircraft during operation. Typically, the electrical generators are driven by a drive shaft which is connected, directly or indirectly (e.g. via a gearbox), to the main turbine of the aircraft engine.

As with any mechanical system, mechanical failures can happen in the electrical generators of aircraft engines. A disconnect device which can mechanically decouple the electrical generator from the engine's turbine must therefore be provided. Even though the loss of electrical generation capacity through disconnection can be serious, if a malfunctioning generator is not disconnected from the turbine, the aircraft engine as a whole may be damaged or its performance hindered.

There are, however, drawbacks to disconnecting a generator from the aircraft engine while the aircraft is operational, and improvements to existing generator arrangements would be desirable.

Summary of the Invention

The inventors have determined that most known disconnect devices suffer from one or more problems.

One problem that can arise with current disconnect devices is that the bearings that support the input shaft of the generator are no longer lubricated following disconnection. Regulatory bodies require that the input shaft must be capable of being driven for an extended period of time following disconnection and typical high speed oil-lubricated bearings incur damage when driven for especially long periods without oil. Worn input shaft bearings can result in loss of location of the input shaft, which could result in leakage of oil, causing an increased burden of repair and maintenance operations. To mitigate this, bearings which are over-specified for general use can be implemented, in order to cater for this failure mode, but this results in higher costs and weight of the bearings in question.

Another problem is that once the generator is disconnected, a means of power for the hydraulic, electrical and pneumatic systems may also be disconnected when the electric rotor is disconnected. For example, oil pumps -which facilitate the lubrication and cooling of the input shaft bearings -can no longer be operated following disconnection. If backup generators and permanent magnet generators installed in the main generator for powering flight control systems are disconnected when a problem with the main generator or the generator control unit is detected, further issues can arise. Further, if it is anticipated that cooling pump functionality may be lost once a generator is disconnected, due to a fire for example, it may be necessary to compensate by adding additional fireproofing in the generator housing, increasing weight, which is undesirable in aircraft. If the pump is able to keep running then the generator housing will be more likely to survive the environment because of the continued heat exchange provided by the circulating oil.

According to the invention, there is provided an input drive arrangement, of a generator arranged to be driven by a prime mover of an aircraft, the input drive arrangement comprising: a disconnect device comprising: a drive transfer means having a connected configuration and a disconnected configuration, configured to transfer a rotational drive between an input shaft and a rotor of the generator when in the connected configuration, and to disconnect the input shaft from the rotor when in the disconnected configuration; and an accessory drive member, arranged to rotate with the input shaft to output power to at least one accessory; wherein the accessory drive member is connected to the input shaft such that it continues to rotate with the input shaft when the drive transfer means is in the disconnected configuration.

This has the advantage of providing a generator input drive disconnect device which, when in its disconnected configuration, enables the continued use of the accessory systems.

The accessory drive member may be configured to drive a fluid pump.

The fluid pump may be connected to a fluid circuit of the generator and is arranged to circulate fluid in the fluid circuit.

The input shaft may be supported by at least one bearing and the fluid pump may be configured to provide a lubricant to the at least one bearing.

The accessory drive member may be configured to transfer drive from the input shaft to the fluid pump when the drive transfer means is in the disconnected configuration.

The accessory drive member may configured to actuate a pulley.

The accessory drive member may be configured to drive a rotor of a second generator.

The accessory drive member may be configured to drive a geared arrangement.

The accessory drive member may be substantially annular and may be fixedly connected to an outer annular surface of the input shaft.

The accessory drive member may comprise a toothed gear arrangement.

The oil pump may be configured to lubricate the one or more bearings when the drive transfer means is in the disconnected configuration.

The accessory drive member may be configured to deliver power to at least one accessory.

The at least one accessory being powered by the accessory drive member may be, but is not limited to being a high pressure fuel pump, a low pressure fuel pump, a permanent magnet generator, a rotor for a second generator, a belt system, an oil pump, a constant speed drive, a hydraulic pump, a high-pressure air compressor, a low-pressure air compressor, an engine starter, a tachometer sensor drive or an auxiliary gearbox drive.

In alternative embodiments, the input shaft may be mechanically coupled to a disconnect input shaft. The disconnect input shaft may be configured to transfer a rotational drive between an input shaft and the drive transfer means when in the connected configuration, and to disconnect the input shaft from the rotor when in the disconnected configuration.

The disconnect input shaft may be rotatable about the rotor axis A. The generator input shaft may be configured to float axially relative to the disconnect input shaft.

The mechanical coupling between the input shaft and the disconnect input shaft may be articulable.

The mechanical coupling between the input shaft and the disconnect input shaft may be a splined connection.

According to a further aspect of the invention, there is provided an aircraft engine assembly comprising an input drive arrangement as described hereinabove.

According to a further aspect of the invention, there is provided an aircraft comprising an aircraft engine assembly as described hereinabove.

Brief Description of the Drawings

Further features and advantages of the present invention will become apparent from the following description of embodiments thereof, presented by way of example only, and by reference to the drawings, wherein: Figure 1 is a schematic diagram illustrating a disconnect device according to one embodiment of the present invention.

Figure 2 is a perspective view of the disconnect device of Figure 1.

Figure 3 is a schematic diagram illustrating an aircraft and an aircraft engine assembly according to embodiments of the present invention.

Detailed Description

Turning to Figures 1 and 3, there will now be described embodiments of a disconnect device 100 according to embodiments of the invention. With reference to Figure 3, the generator drive disconnect device 100 can be comprised in a generator 3, arranged to be driven by a prime mover of an aircraft such as an aircraft engine 2, of an aircraft 1. The generator 3 comprises a rotor 110, rotatable about a rotor axis A. The generator 3 further comprises a disconnect input shaft 120, rotatable about the rotor axis A. The disconnect input shaft 120 may be comprised in a generator input shaft assembly 129. The generator input shaft assembly may be configured to transfer drive from the engine 2, optionally via an output gearbox (not shown), to an input drive arrangement 4. An aircraft engine assembly can therefore comprise a prime mover, a generator and the input drive arrangement 4.

Figure 1 illustrates one embodiment of the disconnect device 100. A disconnect input shaft 120 is rotatably mounted in a generator housing 150, journaled to rotate about rotor axis A by a bearing 127. In this embodiment, the disconnect input shaft 120 is comprised in a generator input shaft assembly 129. In this way, the input shaft assembly 129 transfers rotational drive from the aircraft engine to drive the disconnect device 100 to rotate about rotor axis A. The rotor 110 of the generator is rotatably mounted in the housing 150, journaled by a rotor bearing 117. The rotor comprises splines 114 arranged to mesh with splines 104 of a first disconnect member 101. Therefore, the first disconnect member 101 is able to rotate with the rotor 110 via meshed splines 104, 114 and can move along rotor axis A relative to the rotor 110. The disconnect device 100 comprises a disconnectable drive transfer means 116 arranged to transfer rotational drive between the first disconnect member 101 and a second disconnect member 121. The second disconnect member 121 is arranged to rotate with the disconnect input shaft 120. Although the second disconnect member 121 is shown in Figure 1 to be an integral part of the disconnect input shaft 120, it will be appreciated that this component may instead be distinct from the disconnect input shaft 120 while still being able to rotate therewith. The first and second disconnect members 101, 121 comprise first and second clutch members 105, 125, respectively, that are axially separable from one another. When engaged, the clutch members 105, 125 facilitate the transfer of rotational drive in the drive transfer means 116 such that the drive transfer means 116 is in a connected configuration. In the connected configuration, the drive transfer means 116 transfers rotational drive from the disconnect input shaft 120 to the rotor 110, via the first and second disconnect members 101, 121. When the clutch members 105, 125 are axially separated by the relative axial separation of the first and second disconnect members 101, 121, the drive transfer means is in a disconnected configuration. Such separation may be achieved by any suitable disconnect mechanism. For example, a ramp member 130 may be provided, able to rotate with the drive transfer means 116 and comprising a ramp 131. A disconnect actuating member 140 may be mounted to the housing 150 and can be actuated towards the rotor axis A, that is, towards the ramp member 130. After actuation of the disconnect actuating member 140, it engages the ramp 131 to axially move the first disconnect member 101 away from the second disconnect member 121 to thereby move the drive transfer means 116 to its disconnected configuration. An accessory drive member 128 is fixedly mounted on the disconnect input shaft 120. As such, the accessory drive member 128 is configured to rotate with the disconnect input shaft 120 and transfers torque to an accessory, not shown. In Figures 1 and 2, the accessory drive member 128 is fixed to the disconnect input shaft at a position along the rotor axis A that is between the axial positions of the bearing 127 and the rotor 110.

The clutch members 105, 125 are together configured as a dog clutch and are axially separable along rotor axis A, but it will be appreciated that other suitable forms of drive transfer means, such as a friction clutch, may be employed. The first disconnect member 101 is moveable along rotor axis A between a first axial position and a second axial position. In the first axial position of the first disconnect member 101, the first clutch member 105 is engaged with the second clutch member 125 such that the drive transfer means 116 is in its connected configuration. In the second axial position of the first disconnect member 101, the first clutch member 105 is disengaged from the second clutch member 125 such that the drive transfer means 116 is in its disconnected configuration. In Figure 1, the first disconnect member 101 is shown to be positioned in its first axial position such that the drive transfer means 116 is in its connected configuration. In the connected configuration of the drive transfer means 116, the clutch members 105, 125 cause the first disconnect member 101 and the second disconnect member 121 to rotate together at the same speed. In the disconnected configuration of the drive transfer means 116, the clutch members 105, 125 are separated along rotor axis A such that the first disconnect member 101 and the second disconnect member 121 rotate independently of each another.

In the arrangement shown in Figure 1, the second disconnect member 121 is not moveable along the rotor axis A relative to the disconnect input shaft 120. In another arrangement, the second disconnect member 121 may be an independent component to the disconnect input shaft 120 and may be configured to rotate therewith by, for example, a set of meshing teeth. In a further arrangement, the second disconnect member 121 is an independent component to the disconnect input shaft 120 and can, for example by the provision of meshing splines, move along the rotor axis A relative to the disconnect input shaft 120. Therefore, while the figures referenced herein illustrate an embodiment in which only the first disconnect member 101 is moveable along rotor axis A, it will be understood that modifications to this arrangement could be made such that the second disconnect member 121 were also, or solely, able to move along rotor axis A, in order to move the drive transfer means 116 into and out of the disconnected configuration.

The rotor 110 is rotatable within the housing 150, journaled by a bearing 117. The rotor comprises a plurality of splines 114 on an inner circumferential surface thereof. These may be provided on a flange 111. The first disconnect member 101 comprises a plurality of splines 104 disposed around an outer circumferential surface of a second end 107 of the first disconnect member 101. The splines 104 engage the splines 114 such that rotational drive can be transferred between the first disconnect member 101 and the rotor 110. The splines 104, 114 allow the first disconnect member 101 to translate along the rotor axis A between the first axial position and the second axial position. Therefore, the first disconnect member 101 can rotate with the rotor 110, relative to the housing 150, while being axially moveable relative to the rotor 101. In the connected configuration, rotational drive is transferred from the disconnect input shaft 120 to the rotor 110 via the drive transfer means 116 and the splines 104, 114. The rotor 110 further comprises a rotor shaft 112, fixedly mounted to the rotor 110. The rotor shaft 112 extends axially from the rotor 110 along the rotor axis A towards the drive transfer means 116.

The disconnect device 100 may further comprise a biasing means 119. The biasing means 119 can be arranged to bias the drive transfer means 116 to its connected configuration. In Figure 1, the biasing means is shown to be a coiled spring disposed around rotor axis A, but it will be understood that other suitable biasing means may be employed instead of, or in addition to, a spring. The biasing means 119 is arranged to be in compression such that it exerts a force to bias the first disconnect member 101 away from the rotor 110. Therefore, the biasing means 119 biases the first disconnect member 101 towards the second disconnect member 121, thereby biasing the first clutch member 105 towards engagement with the second clutch member 125, to thereby bias the drive transfer means 116 to its connected configuration. As such, the biasing means 119 is a connection biasing means.

The disconnect device 100 further comprises a disconnect mechanism. The disconnect mechanism comprises any suitable mechanism capable of moving the drive transfer means 116 into the disconnected configuration. Such separation may be achieved by moving the first disconnect member 101 axially relative to the second disconnect member 121.

Figures 1 and 2 described herein refer to one possible example of a known disconnect mechanism that may be employed in the disconnect device 100, which is described in more detail in the following. In this example, the ramp member 130 is disposed around an outer circumferential surface of the first end 106 of the first disconnect member 101. The ramp member comprises a ramp 131 extending around at least a part of the angular extent of the ramp member 130. The ramp member 130 comprises an inner flat section 133 that comprises an annular surface disposed around rotor axis A, extending around the full angular extent of the first disconnect member 101. The ramp member 130 further comprises an outer flat section 132, disposed at least part way around the rotor axis A, that is, extending around at least a part of the angular extent of the first disconnect member 101. The ramp 131 and the outer flat section 132 are disposed radially outwards of the inner flat section 133. The outer flat section 132 is axially offset, along the rotor axis A, from the inner flat section 133. In this embodiment, the outer flat section 132 is offset from the inner flat section 133 towards the flange 111, but it will be understood by the skilled person that a different arrangement may be employed in different embodiments, such as in an embodiment in which the ramp member is instead disposed around the second disconnect member 121. The ramp 131 of the ramp member 130 begins at an axial position of the outer flat section 132 and ramps in a helical manner towards the axial position of the inner flat section 133, that is, towards the disconnect input shaft 120 in this embodiment. Therefore, the ramp 131 provides a substantially axially-oriented incline extending from the axial position of the outer flat section 132 towards the axial position of the inner flat section 133.

The disconnect mechanism of this example further comprises a disconnect actuating member 140. In Figure 1, the disconnect actuating member 140 is shown to have a cylindrical portion slideably receivable by a bore or an extension 142 of the housing 150, but it will be appreciated that other suitable means for mounting the disconnect actuating member 140 to the housing 150 may be employed. Furthermore, while the disconnect actuating member is shown in Figure 1 to have an axis of motion perpendicular to the rotor axis A, it will be appreciated that the disconnect actuating member 140 may instead be oblique to the rotor axis A. The disconnect actuating member 140 is moveable between a de-activated position and an activated position. A spring 144 is provided between the disconnect actuating member 140 and the housing 150, but it will be appreciated that other suitable biasing means may be employed. The spring 144 biases the disconnect actuating member 140 towards its activated position, that is, towards the rotor axis A in a direction that may be perpendicular to the rotor axis A. In Figure 1, the disconnect actuating member 140 is in its de-activated position. The disconnect actuating member 140 is maintained in its de-activated position, against the force of the spring 144, by a retaining means (not shown). It will be understood by the skilled person that any such retaining means capable of enabling the disconnect actuating means 140 to be spring-loaded will be suitable. The retaining means may comprise a mechanical latching mechanism, or any suitable pneumatic, hydraulic or magnetic mechanism, for example, capable of holding the disconnect actuating member 140 in its de-activated position, against the force of the spring 144. It will be understood by the skilled person that upon releasing the retaining mechanism, the disconnect actuating member 140 will be forced, by the spring 144, towards the rotor axis A into an activated position, in which it can activate the disconnect mechanism. Alternatively, the biasing and retaining means may be replaced or supplemented by an active actuation means (not shown), capable of moving the disconnect actuating member 140 between its de-activated and activated positions. Such an active actuation means may comprise a solenoid, hydraulic or pneumatic arrangement, or any other arrangement capable of actuating the disconnect actuating member 140 towards the ramp member 131 and further towards the rotor axis A. In the de-activated position, the disconnect actuating member 140 of the disconnect mechanism of this example is positioned in proximity to, and radially outward of, the ramp member 130, but not in contact therewith. Movement of the disconnect actuating member 140 into the activated position, that is, towards the rotor axis A, allows it to engage the ramp member 130. When the disconnect actuating member 140 engages the ramp 131 on the ramp member 130, the interaction between the disconnect actuating member 140 and the ramp 131 forces the ramp member 130 along rotor axis A to move the first disconnect member 101 from its first axial position to its second axial position, thereby moving the drive transfer means 116 into its disconnected configuration.

As shown in Figures 1 and 2, the disconnect actuating member 140 is in its de-activated position. The first disconnect member 101 is held in its first axial position by the biasing means 119. Therefore, the drive transfer means 116 is in its connected configuration such that rotational drive is transferred from the disconnect input shaft 120 via the drive transfer means 116 to the first disconnect member 101 and to the rotor 110. As such, the disconnect input shaft 120, first disconnect member 101, ramp member 130 and the rotor 110 rotate together with respect to the disconnect actuating member 140.

Upon release of the retaining mechanism of the disconnect actuating member 140, the disconnect actuating member 140 is biased by the spring 144 towards its activated position, that is, towards the ramp member 130. Depending upon the rotational position of the ramp member 130 when the disconnect actuating member 140 is moved to its activated position, the disconnect actuating member 140 will either contact an outer circumferential surface of the ramp 131 or engage the outer flat section 132. In the former case, the ramp member 131 will rotate with respect to the disconnect actuating member until the outer flat section 132 is brought into rotational alignment with the disconnect actuating member 140, at which point the spring 144 continues to bias the disconnect actuating member 140 towards rotor axis A and into engagement with the outer flat section 132. In any case, the disconnect actuating member 140 will engage the outer flat section 132 within one revolution of the ramp member 130 about rotor axis A. As the ramp member 130 continues to rotate with respect to the disconnect actuating member 140, so too does the outer flat section 132, until the disconnect actuating member eventually engages the ramp 131. At this point, continued rotation of the ramp member 130 with respect to the disconnect actuating member 140 forces the ramp member 130 in a axial direction to thereby move the first disconnect member 101 from its first axial position to its second axial position, thereby disengaging the drive transfer means 116. Once the ramp member 130 has been forced a sufficient distance along rotor axis A, the continued biasing of the disconnect actuating member 140 towards the rotor axis A allows the disconnect actuating member 140 to move radially inwards towards rotor axis A to thereby bring the disconnect actuating member 140 into engagement with the inner flat section 133. The engagement of the disconnect actuating member 140 with the inner flat section 133 holds the ramp member 130 at an axial position that maintains the first disconnect mechanism 101 at its second axial position, against the action of the biasing means 119.

As shown in Figures land 2, the accessory drive member 128 may be substantially annular and may be disposed around an annular surface of the disconnect input shaft 120. The accessory drive member 128 can be mounted on the input side of the disconnect device, that is, on the engine side of the disconnect device, as opposed to the rotor side of the disconnect device. The accessory drive member 128 may be fixedly mounted to the disconnect input shaft 120. Although the figures illustrate that the accessory drive member 128 is fixed to the disconnect input shaft 120 at a position along the rotor axis A that is between the axial positions of the bearing 127 and the rotor 110, it will be appreciated that the accessory drive member 128 may be positioned at any suitable point on the generator input shaft assembly 129. The accessory drive member 128 may be fixed to the disconnect input shaft 120 by an interference fit, or any other suitable fixing means, or may be integrally formed with the input shaft 120. The accessory drive member 128 is arranged to rotate with the disconnect input shaft 120. As shown in Figure 2, the accessory drive member 128 comprises a set of teeth 128a disposed around its outer annular surface. Such teeth 128a are provided as a means to transfer rotational drive from the generator input shaft assembly 129 to one or more accessory components (not shown). In this way, rotational drive may be transferred from the generator input shaft assembly 129 to one or more accessories via the accessory drive member 128. In this way, the accessory drive member 128 may power at least one accessory. The at least one accessory being powered by the accessory drive member 128 may include, but is not limited to, a fuel pump, a permanent magnet generator, a rotor for a second generator, a belt system, an oil pump, a constant speed drive, a hydraulic pump, a high-pressure air compressor, a low-pressure air compressor, an engine starter, a tachometer sensor drive or an auxiliary gearbox drive.

As the skilled person will appreciate, the arrangement described may be employed to provide rotational drive to power other suitable accessory components. Indeed, the accessory drive member 128 may be arranged to transfer rotational drive to one or more secondary drive members 193. In such an example, the secondary drive member 193 is itself arranged to power at least one accessory component. Therefore, this arrangement provides the possibility of powering at least one accessory component, directly or indirectly, from the accessory drive member 128. It will be understood that references to the accessory drive member 128 powering an accessory component includes arrangements in which rotational drive is transferred to an accessory component via one or more secondary drive members, such as a secondary gear or secondary pulley, arranged to be driven by the accessory drive member 128. The secondary drive member may also be a stator comprising windings disposed in the region of its inner circumference. The accessory drive member 128 may be a rotor arranged to rotate within the secondary drive member. It will be further understood by the person skilled in the art that although the accessory drive member 128 is depicted in Figure 2 as a toothed gear, it is not limited to this configuration. The accessory drive member 128 may be arranged to transfer torque to an accessory component via a mechanical belt or a pulley system, for example.

In one embodiment, the accessory drive member 128 may be a rotor arranged to rotate within a stator of secondary generator (not shown). The accessory drive member 128 may, for example, have a plurality of permanent magnets disposed in the region of its outer circumference. The accessory drive member 128 may therefore be arranged as a rotor arranged to rotate relative to a stator. The accessory drive member 128 may instead, or additionally, be configured to transfer rotational drive directly to any component that requires such a drive, such as a fluid pump for example. It will be appreciated that the structure and position of the accessory drive member 128 may be suitably adapted to power a variety of accessory components.

The bearing 127 is arranged to rotatably mount the input shaft 120 in the housing 150. In this way, the bearing 127 provides a means for rotatably mounting the generator input shaft assembly 129 in the housing 150. Although the figures illustrate a single bearing, there may be more than one bearing arranged to rotatably mount the input shaft 120 in the housing. The bearing 127 is arranged to journal the input shaft 120 such that it radially supports the generator input shaft assembly 129 whether the drive transfer means 116 of the generator drive disconnect device 100 is in its connected or disconnected configuration. The accessory drive member 128 may be configured to drive an oil pump (not shown). The oil pump may be configured to lubricate the bearing 127. Furthermore, the oil pump may be configured to lubricate and/or provide cooling to one or more accessory components, or to any part of the generator or related systems or components.

In certain prior disconnect devices, accessory drive members are mounted to a component on the output side of the disconnect device, that is, on the rotor side of the disconnect device, as opposed to the engine side of the disconnect device. In an example of such a known disconnect device, once the disconnect device is moved into its disconnected configuration such that the rotor of the generator is no longer driven by the input shaft and begins to idle, the accessory drive member will be driven only by the idling rotor, until such time as the rotor becomes stationary, which may be very rapidly in the event of a bearing failure. Therefore, from the moment of disconnection of the drive transfer means, such accessory drive members receive a reduced drive, quickly diminishing to zero. In this way, the rotational drive available to power any accessories driven by the accessory drive member will be similarly reduced. For example, certain prior arrangements employ a pump, powered by an accessory drive member on the output side of the disconnect device, wherein the pump is configured to provide lubrication to a bearing, such as a bearing configured to journal the input shaft to the disconnect device. After disconnection, the accessory drive member may no longer be able to provide the power required by the pump; this would cause a reduction in the lubrication available to the bearing and would increase the likelihood of failure of the bearing due to its decreased wear resistance from lack of lubrication. Instead of lubricating the bearing with a pump, some prior disconnect devices employ bearings that do not require lubrication, such as grease-packed bearings or other long-lasting bearings. In addition to increasing manufacturing costs, the lubrication in such bearings has been shown to escape from the bearing due to the high centrifugal forces experienced therein, especially in disconnect devices of generators that operate at high speed. Similarly, this results in reduced wear resistance.

In the present invention, the accessory drive member 128 is connected to the input side of the disconnect device 100. Therefore, even when the disconnect device 100 is in its disconnected configuration, it continues to receive rotational drive from the input shaft 120. In this way, the drive received by the accessory drive member is not substantially reduced following disconnection. This configuration enables the at least one accessory to be operated after disconnection of the drive transfer means, without suffering from a reduced power input. In particular, when the accessory drive member 128 is arranged to power a pump to lubricate the bearing 127, it will be understood that even after disconnection, the bearing 127 may continue to be lubricated. This provides the advantage of reducing wear of the bearing 127, whether the drive transfer means 116 is in the connected or disconnected configuration. Therefore, this arrangement provides the bearing 127 with a longer service life while improving the reliability of the disconnect device 100. As will be understood, an oil pump powered by the accessory drive member 128 in this way may also continue to provide lubrication and/or cooling to one or more accessory components, even after disconnection, such that the accessory components may continue to operate as normal.

Figure 3 schematically illustrates an aircraft 1 comprising an aircraft engine 2 and a generator 3. The aircraft engine 2 is able to transfer drive to the generator 3 via a generator input shaft assembly 129. The generator input shaft assembly 129 is able to transfer drive to the rotor 110 via a disconnect device 100 as described hereinabove.

The generator 3 further comprises accessory drive member 128, which may transfer drive to at least one secondary drive member 193. The at least one secondary drive member 193 or 193' may be a secondary gear or a secondary pulley. In Figure 3, the at least one secondary drive member 193' transfers drive to a generator 194, which may be a permanent magnet generator. An additional or alternative secondary drive member 193 may transfer drive to a fluid pump 184 of a fluid circuit 185, which may be a coolant or lubrication circuit, for example. The permanent magnet generator 194 may be configured to provide a secondary power output to an electrical sub-system 195. The electrical sub-system 195 may comprise avionics or any auxiliary power bus or power system requiring electrical power, for example. The skilled person will appreciate that, in light of the input drive arrangement 4 comprising an accessory drive member 128 on the input side of the disconnect device, the electrical sub-system 195 may continue to be powered even after disconnection of the disconnect device, when the main rotor and thus the main power output of the generator is thus deactivated.

In an optional arrangement, the secondary drive member 193 may comprise all, or part of a, preferably annular, stator for a secondary generator. For example, stator windings may be disposed in the region of an inner circumference of the secondary drive member 193. Such windings may interact with permanent magnets in order to generate power for the fluid pump 184, for example.

The fluid pump 184 may be configured to deliver lubricating fluid and/or cooling fluid to the rotor 110 and/or the disconnect device 100. Further, the circuit 185 may be configured to deliver lubricating fluid or cooling fluid to the accessory drive member 128. It will be appreciated that, whilst the circuit is depicted to operate between the pump 184, rotor 110 and the disconnect device 100, it could extend to any of the components or systems in the aircraft 1.

Various modifications, whether by way of addition, deletion and/or substitution, may be made to all of the above described embodiments to provide further embodiments, any and/or all of which are intended to be encompassed by the appended claims.

Claims

Claims 1. An input drive arrangement, of a generator arranged to be driven by a prime mover of an aircraft, the input drive arrangement comprising: a disconnect device comprising: a drive transfer means having a connected configuration and a disconnected configuration and being configured to transfer a rotational drive between an input shaft of the generator and a rotor of the generator when in the connected configuration, and to disconnect the input shaft from the rotor when in the disconnected configuration; and an accessory drive member, arranged to rotate with the input shaft to output power to at least one accessory of the generator; wherein the accessory drive member is connected to the input shaft such that it continues to rotate with the input shaft when the drive transfer means is in the disconnected configuration.
2. The input drive arrangement of claim 1, wherein the accessory drive member is configured to drive a fluid pump.
3. The input drive arrangement of claim 2, wherein the fluid pump is connected to a fluid circuit of the generator and is arranged to circulate fluid in the fluid circuit.
4. The input drive arrangement of claim 3, wherein the fluid circuit is a cooling fluid circuit, or a lubricating fluid circuit.
5. The input drive arrangement according to any of claims 2 to 4, wherein the input shaft is supported by at least one bearing and the fluid pump is configured to provide a lubricant to the at least one bearing.
6. The input drive arrangement according to any of claims 2 to 5, wherein the accessory drive member is configured to transfer drive from the input shaft to the fluid pump when the drive transfer means is in the disconnected configuration.
7. The input drive arrangement of any preceding claim, wherein the accessory drive member is configured to actuate a pulley.
8. The input drive arrangement of any preceding claim, wherein the accessory drive member is configured to drive a rotor of a second generator.
9. The input drive arrangement of any preceding claim, wherein the accessory drive member is configured to drive a geared arrangement.
10. The input drive arrangement of any preceding claim, wherein the accessory drive member is substantially annular and is fixedly connected to an outer annular surface of the input shaft.
11. The input drive arrangement of any preceding claim, wherein the accessory drive member comprises a toothed gear arrangement.
12. An aircraft engine assembly comprising an input drive arrangement in accordance with any of claims 1 to 11.
13. An aircraft comprising an aircraft engine assembly in accordance with claim 12.