The present invention relates to a device, in particular a device for transmitting rotary motion from an input to an output.

Large commercial aircraft include multiple control surfaces such as wing leading edge slats or wing trailing edge flaps. Typically a particular wing will have a plurality of control surfaces, all of which need to be moved in unison. Each control surface may be moved via an actuator. In some circumstances each control surface is moved by two actuators, one at each end thereof. The plurality of control surfaces on the right wing need to be moved in unison with the plurality of control surfaces on the left wing. Under these circumstances a power drive unit (PDU) may be positioned in a fuselage of the aircraft with left and right drive shafts extending therefrom. Each driveshaft drives multiple actuators in series.

The actuators may comprise gear rotary actuators (GRA).

Thus according to the present invention there is provided a device having an input element, an output element, and a drive element, the device having a first position configured such that the drive element is engaged with the input element and the output element to prevent movement of the input element in a first direction relative to the output element, the device having a second position configured such that the drive element is engaged with the input element and a further element to prevent movement of the input element in the first direction relative to the further element.

According to another aspect of the present invention there is provided a device having an input element, an output element, a first drive element and a second drive element, the device having a first position configured such that the first drive element is engaged with the input element and the output element to prevent movement of the input element in a first direction relative to the output element, the device having a second position configured such that the second drive element is engaged with the input element and a further element to prevent movement of the input element in the first direction relative to the further element.

Advantageously in the first position, under normal operation, the input element drives the output element and, with the device in the second position, the input element is prevented from moving relative to the further element.

The invention will now be described, by way of example only, with reference to the accompanying drawings in which:-

Figure 1 is a cross-section of a device according to the present invention shown in a first position,

Figure 2 is an isometric cut away view of part of figure 1,

Figure 3 is a cross-section view of part of figure 1,

Figures 4, 5 and 6 are isometric views of certain components of figure 1, Figure 7 is an isometric cut-away view of the device of figure 1 at a first intermediary position,

Figure 8 is a cross-section view of figure 7,

Figure 9 is an isometric cut-away view of the device of figure 1 shown in a second intermediary position,

Figure 10 is a cross-section view of figure 9,

Figure 11 is a cross-section view similar to figure 10 but in a third intermediary position,

Figure 12 is an axial view of figure 11,

Figure 13 is an isometric view of the device of figure 1 in a second position, Figure 14 is an axial view of figure 13,

Figure 15 is a cross-section view of a further device according to the present invention shown in a first position,

Figure 16 is an axial cut away view of figure 15,

Figure 17 is an axial cross-section view of the device of figure 15 shown in a second position,

Figure 18 is an alternative component for use in the devices of figures 1 and 15,

Figure 19 is an isometric view of an alternative cam plate and coupling sleeve arrangement, and

Figure 20 is an end view of the arrangement of figure 19. With reference to figures 1 to 14 there is shown an input shaft 10 which may drive a gear rotary actuator (GRA) 12 via a device 14. Input shaft 10 has an axis A. Input shaft 10 is rotationally fast with a first coupling sleeve 20 which is secured thereto via a nut 21. Input shaft 10 is also secured rotationally fast to a second coupling sleeve 22 which is secured thereto by a nut 21A. The input shaft 10 includes an abutment 23, a shoulder 24 and a splined portion 25 (see figure 2). The main components of the device 14 are a housing 30 (best seen in figure 4), an output cam plate 40 (best seen in figure 5) and an input cam plate 50 (best seen in figure 6). The device 14 also includes at least one drive element, in this example three drive elements in the form of balls 60 (only one of which 60A) is shown). The balls 60 are spherical. Housing 30 has a generally cylindrical portion 32 with four lugs 31 depending therefrom, each lug having a corresponding hole 31A. The generally cylindrical portion 32 has a first recess 33 and a second recess 34.

The second recess has three inwardly facing projections 35, 36 and 37, each having abutments 35A, 36A, 37A, 35B, 36B, 37B ( see figures 4 and 12). Each projection also includes inwardly facing surface 35C, 36C and 37C. Inwardly facing surfaces 35C, 36C, and 37C are all positioned at radius R7 from axis A (see figure 12).

Between projections 37, 35 and 36 the second recess 34 has inwardly facing surfaces 34A, 34B and 34C. Inwardly facing surfaces 34A, 34B, 34C are all positioned at radius R8 from axis A (see figure 12).

The input cam plate 50 is generally cylindrical and includes internal splines 51 (see figure 6). The input cam plate includes first axially orientated face 52, second axially orientated face 53 and outer surface 54.

The first axially orientated face 52 includes three first recesses 55A, 55B and 55C, three second recesses 56A, 56B, 56C and three third recesses 57A, 57B, 57C. All first recesses 55A, 55B and 55C are identical. As best seen in figure 3 first recess 55A is sized to partially receive ball 60A. The second recesses 56A, 56B and 56C are all identical. As best seen in figure 2, second recess 56A includes an axially orientated portion 70 and a circumferentially orientated portion 71.

Figure 10 is a cross section taken along the axially orientated portion 70 and it can be seen that the second recess 56A has an opening 72 in the first axially orientated face 52 of the input cam plate 50. As best seen in figure 10, at the first axially orientated face 52, the opening 72 has a radius Rl. However, remote from the first axially orientated face 52, the second recess 56A has a second radius R2 which is larger than the first radius Rl. Accordingly the axially orientated portion 70 of the second recess 56A defines a first ramp 73 that is orientated radially outwardly in the longitudinal direction. Compare and contrast the radial position of ball 60A as shown in figure 3 where the radially inner portion of the ball is proximate the input shaft 10 versus the radial position of the ball 60A in figure 10 whereupon the ball has moved in an axial direction to the left when viewing figure 10 and consequently up the ramp 73 to a radially outer position. Note a detailed explanation of operation of the device will be described further below.

The axially orientated portion 70 also defines a cylindrical portion 73A, the axis of the cylinder being parallel to axis A and passing through the centre of ball 60A when positioned as show in fig 11.

The circumferentially orientated portion 71 of the second recess 56A includes a second ramp 74 that is orientated radially outwardly in the circumferential direction. Compare and contrast the radial position of ball 60A in figure 12 where it is at the radially inner part of ramp 74 and its position as further shown in figure 14 where it is at the radially outer part of ramp 74. Note a detailed explanation of the operation of the device will be described below.

The third recesses 57A, 57B and 57C are all identical. The third recess 57A is a mirror image of recess 56A. Thus the third recess 57A has an axially orientated portion 75, a circumferentially oriented portion 76, an opening 77, a first ramp 78, a cylindrical portion 78A and a second ramp 79. The difference between the third recess 57A and second recess 56A is that the circumferentially orientated portion 71 of the second recess 56A is orientated in a first circumferential direction whereas the circumferential orientated portion 76 of the third recess 57A is orientated in an opposite circumferential direction. The output cam plate 40 is generally cylindrical and includes a flange 41 which includes three pockets 42A, 42B, 42C in an axially oriented surface 43. The output cam plate 40 also includes an external spline 44, an end surface 45 and a recess 46 (see figure 3). The internal bore 47 of the output cam plate 40 is a plain bore, i.e. it does not include any splines or the like and hence is freely rotatable about shaft 10.

As best seen in figure 2 and 3 there is included a helical spring 80, a thrust washer 81 and five bellville springs 82. The five bellville springs 82 form a bellville spring stack 83.

Figures 1, 2 and 3 show the device assembled for normal operation. The five bellville springs have been assembled onto the input shaft 10 to form the stack 83 and one end of the stack abuts abutment 23 of the input shaft. At the opposite end of the stack is positioned the thrust washer 81. The end surface 45 of the output cam plate 40 is engaged with the thrust washer 81. The three balls 60 are partially received in respective pockets 42A, 42B and 42C of the output cam plate 40. Opposite sides of the three balls 60 are partially received in corresponding first recesses 55A, 55B, 55C.

The radially innermost part of the first axially orientated face 52 of the input cam plate 50 is engaged with shoulder 24 of the input shaft 10 by virtue of nut 21A being tightened against the second coupling sleeve 22 which in turn presses the input cam plate 50 against the shoulder 24 of the input shaft 10. In this position (as shown in figures 1 and 2) the Bellville stack is under compression and the helical spring is under compression. The spring rate of the Belleville stack is greater than the spring rate of the helical spring 80.

The input cam plate 50 is rotationally fast with the input shaft 10 by virtue of engagement between the internal splines 51 of the input cam plate 50 and the splined portion 25 of the input shaft 10. The input shaft 10 is rotatably supported by bearings 84 and 85 (see figure 1). Bearing 84 is received within the first recess 33 of housing 30. Housing 30 is secured rotationally fast to support structure (not shown) via fixings which pass through holes 31A in lugs 31.

The external spline 44 of the output cam plate 40 drives the GRA 12. The GRA has an output shaft 13, the operation of which will be further described below.

Operation of the device 14 is as follows:-

The device 14 operates under normal running conditions as shown in figures 1, 2 and 3. Under these circumstances each ball 60 is partially received in its associated pocket 42A, 42 B or 42C and also partially received in its associated first recess 55A, 55B or 55C. Bellville spring stack 83 is under compression and as such balls 60 are squeezed between the input cam plate 50 and the output cam plate 40. Under these circumstances the device 14 is capable of transmitting rotary motion and torque from the input shaft 10 to the external spline 44 of the output cam plate. Thus in one example a power drive unit (PDU) drives first coupling sleeve 20 via a drive shaft (not shown) which causes rotation of the input shaft 10 in the direction of arrow B of figure 2 about axis A causes the input cam plate 50 to rotate in the direction of arrow B which in turn causes the balls 60 to rotate about axis A in the direction of arrow B which in turn causes the output cam plate 40 to rotate in the direction of arrow B which in turn causes the external spline 44 to rotate in the direction of arrow B. Note under these circumstances the input shaft 10 and the external spline 44 of the output cam plate 40 all rotate at the same speed.

As described above, the external spline 44 acts as an input to the GRA which in turn drives the output shaft 13. However, due to the gear ratio of the GRA, the output shaft 13 rotates slower than the external spline 44 of the output cam plate 40 of the device 14. In one example output shaft 13 rotates 40 times slower than the external spline 44.

The output shaft 13 of the GRA drives a control surface of an aircraft.

If during rotation of the input shaft 10 in the direction of arrow B an event occurs to prevent further rotation of the output cam plate 40, then continued rotation of input shaft 10 in the direction of arrow B will cause the balls 60 to ride out of their associated pockets 42A, 42B and 42C and ride out of their associated first recesses 55A, 55B and 55C, as shown in figure 7 and 8. As will be appreciated, the input cam plate 50 continues to rotate in the direction of arrow B at the same speed as input shaft 10 but the output cam plate 40 is now stationary and hence the balls 60 rotate in the direction of arrow B around axis A, but at half the speed of rotation of the input shaft 10. Thus under these circumstances, whilst the balls themselves are rotating about axis A in the direction of arrow B relative to the output cam plate 40 (which is stationary), they are rotating in the direction of arrow C relative to the input cam plate 50 (because the input cam plate 50 is rotating faster in the direction of arrow B than are the balls 60).

During this process, as best seen in figure 8, the Bellville spring stack 83 has been compressed when compared with figure 3 and the output cam plate 40 has been displaced to the right when compared with figure 3.

As will be appreciated, when moving from the figure 2/3 position to the figure 7/8 position, the balls 60, input cam plate 50, output cam plate 40, and Bellville spring stack 83 act as a torque limiting clutch initially allowing the input cam plate 50 to transfer torque to the output cam plate 40 up to a certain torque limit, following which torque can no longer be transferred since the balls move out of their associated pockets 42A, 42B, 42C and first recesses 55A, 55B, 55C, as shown in figures 7 and 8.

Continued rotation of the input shaft 10 in the direction of arrow B will cause balls 60 to move into associated second recesses 56A, 56B, 56C. Taking the example of balls 60A as shown in figure 7 it has moved out of first recess 55A and is moving towards second recess 56A (or putting it another way, second recess 56A is moving towards ball 60A). Continued rotation of the input shaft 10 in the direction of arrow B causes ball 60A to move into pocket 56A as shown in figure 10.

Figure 10 shows ball 60A partially received in the axially orientated portion 70 and figure 11 shows ball 60A fully received in the axially oriented portion 70. The ball 60A is moved from the axial position shown in figure 8 to the axial position shown in figure 10 then to the axial position shown in figure 11 by virtue of being biased initially by the Bellville spring stack 83, and finally by the helical spring 80. See in particular the gap between end surface 45 and thrust washer 81 shown in figure 11 and note this gap is not present in figures 10 and 8. As mentioned above the axially orientated portion has a first ramp 73 that is orientated radially outwardly in the longitudinal direction, and hence as ball 60A moves axially to the left when viewing figures 10 and 11, simultaneously it initially moves radially outwardly as it travels along first ramp 73 and then moves parallel to axis A as it moves along cylindrical portion 73A. Note once the ball 60A is on the cylindrical portion 73A there is no tendency for the ball to move to the right when viewing figure 11

Outer surface 54 of the input cam plate 50 is positioned at radius R3 (see figure 3 and 12) from axis A. Note from figure 12 that radius R8 is larger than radius R7. Note also that radius R7 is larger than radius R3.

As mentioned above, radius R3, the outer radius of the input cam plate 40 is smaller than radius R7 of the inwardly facing surfaces 35C, 36C, 37C of projections 35, 36, 37. As shown in figures 3 and 8 the radially outer part of ball 60A is positioned at radius R4 which is smaller than radius R3 of the input cam plate and hence smaller than radius R7 of projections 35, 36 and 37. As shown in figure 10 the radially outermost portion of ball 60A is the positioned at radius R5 since the ball has moved partially along the first ramp 73 and as shown in figure 11 the radially outermost portion of ball 60A is now at radius R6 which is larger than radius R5 because the ball 60A has moved beyond the end of the first ramp 73. Significantly, radius R6 is larger than radius R7, see in particular figure 12. Continued rotation of input shaft 10 in the direction of arrow B as shown in figure 12 results in an outer portion of ball 60A engaging abutment 35A of projection 35 and yet further rotation of the input shaft 10 in the direction of arrow B causes abutment 35A to drive ball 60A up the second ramp 74 to the position shown in figure 14 wherein the outermost portion of ball 60A is at radius R8, the radius of the inwardly facing surface 34A of the second recess 34. Under these circumstances it is no longer possible for the input shaft 10 to rotate in the direction of arrow B relative to the housing 30 (i.e. the device is jammed), and hence it is no longer possible for the input shaft to rotate in the direction of arrow B relative to the support structure (not shown). At this point, the torque in the input shaft 10 will increase and this increased torque will be seen at the power drive unit (PDU) whereupon, upon seeing the increased torque, the PDU shuts down.

The above description of balls 60A moving from the first recess 55A to the second recess 56A is in respect of when the input shaft 10 is turning in the direction of arrow B. As will be appreciated, in the event that the input shaft 10 is turning in the opposite direction, i.e. in the direction of arrow C when an event occurs to prevent further rotation of the output cam plate 40, then ball 60A will move from the first recess 55A into the third recess 57A in a similar manner, ultimately resulting in an outer portion of ball 60A engaging abutment 37B of projection 37, thereby preventing further relative rotation.

Figure 15-17 show a second embodiment of a device 114 in which components that fulfil substantially the same function as those of figures 1 to 14 are labelled 100 greater.

Input shaft 110, second coupling sleeve 122, nut 121A, output cam plate 140, input cam plate 150, balls 160, helical spring 180, bellville springs 182, bellville spring stack 183 and bearing 184 are all identical to their corresponding components shown in figures 1 to 14.

Whereas housing 30 is a single unitary component, housing 130 is in two parts. The first part 191 includes lugs 131 with associated holes 131A, the lugs 131 depend from cylindrical portion 132. Cylindrical portion 132 includes first recess 133 which receives bearing 184.

The second part 192 of housing 130 includes second recess 134.

The second recess 134 has three inwardly facing projections 135, 136 and 137, each having abutments 135A, 136A, 137A, 135B, 136B and 137B. Each projection also includes inwardly facing surface 135C, 136C and 137C. Inwardly facing surfaces 135C, 136C and 137C are positioned at radius R7 from axis A.

Between projections 137, 135 and 136 the second recess 134 has inwardly facing surfaces 134A, 134B and 134C. Inwardly facing surfaces 34A, 34B, 34C are all positioned to radius R8 from axis A. The above mentioned components of the second part 192 are provided on a ring like body 192A of the second part 192. The body 192A includes radially outwardly orientated projections 193A, 193B and 193C. Each projection 193A, 193B and 193C includes a respective recess 194A, 194B, 194C. The projections 193A, 193B, 193C are received in recesses 195A, 195B, 195C respectively of the first part 191. The first part 191 includes a radially orientated hole 196. The device 114 includes an indicator pin 197 having a narrow portion 197A and an indicator portion 197B. The narrow portion has a smaller diameter than the indicator portion.

Operation of the device 114 is as follows:-

The device 114 operates under normal running conditions as shown in figures 15 and 16. Note the indicator pin is biased via a biasing device (not shown) downwardly when viewing figure 16 such that the indicator portion 197B is received within the cylindrical portion 132 and is therefore not visible. The indicator pin 197 is engaged in recess 194A. The circumferential width of the projections 193A, 193B, 193C is less than the circumferential width of the recesses 195A, 195B and 195C. As can be seen in figure 16, the circumferential ends of projections 193A/B/C are all spaced from the circumferential ends of the corresponding recess 195A/B/C within which they sit. Accordingly, and as will be further described below, the second part 192 can rotate either clockwise or anticlockwise to a limited extent when viewing figure 16 relative to the first part 191.

During normal running, the relative positions of the first part, second part and indicator pin remain as shown in figure 16. Torque is transmitted from the input shaft 110 to the output cam plate 40 similarly to as described above, in particular with reference to figures 2 and 3.

If during rotation of the input shaft 110 in the direction of arrow B an event occurs to prevent further rotation of the output cam plate 140, then continued rotation of input shaft 110 in the direction of arrow B will cause the balls 160 to ride out of their associated pockets similarly to as described above with reference to figures 7 and 8.

Continued rotation of the input shaft 110 in the direction of arrow B will cause balls 160 to move into associated second recesses similarly to as described above with reference to figures 9 to 14.

As will be appreciated, once the balls 160 achieve a position equivalent to balls 60 as shown in figure 14, then, contrary to device 14, device 114 allows continued rotation of input shaft 10 in the direction of arrow B because the balls 160 drive the body 192A of the second part 192 in a clockwise direction when viewing figure 16 relative to the first part 191. However, only a limited rotation of the second part 192 relative to the first part 191 is possible, see in particular figure 17 where continued clockwise rotation of the ring like body 192A of the second part 192 is prevented relative to the first part 191 by virtue of the projections 193A/B/C circumferentially engaging the ends of corresponding recesses 195A/B/C.

As can be seen from figure 17, by virtue of the relative rotation of the first part relative to the second part the indicator pin 197 is no longer engaged with recess 194C and consequently has moved radially outwardly. This causes the previously hidden indicator portion 197B to become exposed and visible. Thus, it will be apparent to maintenance personnel that an over torque event will have occurred if indicator portion 197B is visible and appropriate maintenance action can then take place.

Clearly, in the event the input shaft is turning in an opposite direction when an event occurs to prevent further rotation of the output cam plate then the opposite circumferential ends of projections 193A/B/C will ultimately engage the opposite circumferential ends of corresponding recesses 195A/B/C.

With reference to figure 18 there is shown an alternative input cam plate 250 with features that fulfil the same function as those shown in input cam plate 50 labelled 200 greater.

Comparing and contrasting figure 18 with figure 6 it will be appreciated that the second recess 56A and third recess 57C have been combined to form recess 258'. Similarly, second recess 56B and third recess 57A have been combined to form recess 258" and second recess 56C and third recess 57B have been combined to form recess 258"'.

Input cam plate 250 can be used in place of input cam plate 50 or input cam plate 150 and will operate in substantially the same way with balls moving from first recesses 255A/B/C into recessed 258', 258" and 258'" and up first ramps 273, along cylindrical portions 273A and up either second ramp 273 or second ramp 297, depending on the direction of rotation of input shaft 10. Note that input cam plate 250 is stronger than input cam plate 50 since it increases the material available to react loads in jam case (i.e. there is more material behind ball when jammed).

It also has fewer (three) entry holes into the ramp features than input cam plate 50 (which has six openings 72/75).

It is bidirectional, since if the system tries to back out of a jam the geometry of the ramps causes the device to jam in the opposite direction within a fraction of a rev. Thus if the device jams when the input shaft 10 is rotating in direction B, then a ball will have ridden up first ramp 273 and up second ramp 274. In the event that the input shaft 10 is then driven in direction C, then the ball will be "reversed" down second ramp 274 and will immediately be driven up second ramp 279 where upon the device will jam again. Under certain circumstanced this can be advantageous.

Referring now to figures 19 and 20 there is shown an alternative arrangement for the cam plate 350 and second coupling sleeve 322. In the arrangement shown, the cam plate 350 is provided with ramps and recesses corresponding to those shown in and described with reference to figure 18. Features common to the cam plate 350 and second coupling sleeve 322 of figure 18 are identified with like reference numerals. It will further be appreciated that the additional features of the cam plate 350 and second coupling sleeve 322 described below may equally be used in conjunction with the other cam plate configurations described herein.

As will be understood from the description of figure 1, the second coupling sleeve 322 is rotationally fixed to the cam plate 350 via the input shaft 10. More specifically, splines of both the second coupling sleeve 322 and cam plate 350 are engaged by a splined portion 25 of the input shaft 10.

During a lock-out event when the system is stalled, the torque transmitted from the second coupling sleeve 322 to the cam plate 350 via the splined portion 25 of the input shaft 10 is significant. As such, there may exist the possibility, in extreme circumstances, of the splines deforming or failing and thus the second coupling sleeve 322 being able to rotate relative to the cam plate 350.

So as to ensure the transmission of torque from the second coupling sleeve 322 to the cam plate 350 in the event that the splines deform or fail, a secondary connection may be provided between the second coupling sleeve 322 and the cam plate 350. As shown in figures 19 and 20, such a secondary connection 410 may be provided by formations 410 provided on the respective facing end faces of the second coupling sleeve 322 and cam plate 350. The cam plate end face is identified with reference numeral 414, whereas the coupling sleeve end face is hidden from view. More specifically, the formations of the coupling sleeve end face comprise a plurality of alternating axial extensions 416 and axial recesses 418. The formations of the cam plate end face 414 comprise a complementary plurality of alternating axial extensions 416' and axial recesses 418'. The extensions 416 of the second coupling sleeve 322 are received in the recesses 418' of the cam plate 350, and the extensions 416' of the cam plate 350 in the recesses 418 of the second coupling sleeve 322.

The extensions 416, 416' and recesses 418, 418' are dimensioned such that each extension 416, 416' is received in its respective recess 418, 418' with a clearance therearound. As such, it will be understood that there is no torque transmission path between the second coupling sleeve 322 and cam plate 350 through the formations 410. The clearance between the extensions 416,416' and recesses 418,418' remains during normal operation.

In the instance that that during a lockout event there is deformation or failure of the splines, then rotational movement of the second coupling sleeve 322 relative to the cam plate 350 results in the extensions 416, 416' being moved into contact with one another. The second coupling sleeve 322 is thus able to transmit torque directly to the cam plate 350.

It will be appreciated that the interaction of the splined portion 25 of the input shaft 10 with the splines on the cam plate 350 define a primary torque transmission path. The extensions and recesses 461, 416', 418, 418' of the second coupling sleeve 322 and cam plate 350 define a secondary torque transmission path in the event of the failure of the primary torque transmission path.

As shown in the figures, each device 14 and 114 includes three drive elements 60/160. In further embodiments there may be more or less than three drive elements. In the devices 14 and 114, all three drive elements engage with the input cam plate and output cam plate so as to transfer torque from the input cam plate to the output cam plate. Similarly, all three drive elements engage with the input element and further element to prevent movement of the input element relative to the further element. In further embodiments the device may include a first drive element and a second drive element. The first drive element may be engaged with the input element and the output element to prevent movement of the input element in the first direction of the output element. The second drive element may be engaged with the input element and a further element to prevent movement of the input element in the first direction relative to the further element. In particular, the first drive element may not engage with the input element and the further element. Furthermore, the second drive element may not engage with the input element and the output element. As such, the first drive element may transmit torque from the input element to the output element but may not be involved with preventing movement of the input element relative to the further element. Conversely the second drive element may be engaged with the input element and the further element to prevent movement of the input element relative to the further element but the second drive element may not be involved in preventing movement of the input element relative to the output element. As such the first drive element and second drive element perform distinct functions.