Multi-stage planetary gear assembly

Abstract

A multi-stage planetary gear assembly (10) for a parking brake actuator which is devoid of a centring means which is both on an axis of the input gear (22), sun gear (36) and / or rotary output (18) and which extends continuously from a housing (12), or adjacent thereto, of the parking brake actuator to the rotary output (18).

Description

[0001] Multi-Stage Planetary Gear Assembly

[0002] The present invention relates to a multi-stage planetary gear assembly for a parking brake actuator. The invention further relates to a parking brake actuator.

[0003] An actuator of an electrical or electronic parking brake generally comprises of a motor and a gear assembly, or gear box.

[0004] When the electronic parking brake is activated, for example by pressing a button, the motor rotates and the rotational motion is transmitted to an idle gear or belt which allows a drive gear or input gear of the gear assembly to rotate. The gear assembly increases the torque, and the motion of the rotary output is transmitted, transferred and / or converted to ultimately result in the brakes being actuated and stopping the wheels from rotating.

[0005] The gear assembly typically includes a single centring shaft or pin which extends through the stages of the gear box and centres the gears.

[0006] The rotation of the gear assembly can generate noise, vibration, and / or harshness (NVH) which is undesirable, particularly in high-end vehicles.

[0007] It is an object of the present invention to reduce or substantially obviate the above problem. The present invention seeks to provide a solution to this problem.

[0008] The present invention achieves this via a number of solutions which are all devoid of a centring means which is both on an axis of the input gear, sun gear and / or rotary output and which extends continuously from a housing of the parking brake actuator to a rotary output.

[0009] According to a first aspect of the present invention, there is provided a multi-stage planetary gear assembly for a parking brake actuator, the multi-stage planetary gear assembly comprising: a first planetary stage including an input gear; a second planetary stage including a sun gear, the first planetary stage for driving said sun gear; a rotary output, the second planetary stage for driving the rotary output; and a centring means for centring said sun gear relative to the input gear and / or rotary output, the centring means being positioned on an axis of rotation of said sun gear and terminating in said sun gear. Since the centring means terminates in the sun gear, and therefore does not extend between the housing, or adjacent there to, and the rotary output, the NVH of the gear assembly and parking brake actuator is improved. This may be due to vibrations being prevented or limited from passing from the rotary output to the sun gear, and / or from the sun gear to the input gear.

[0010] Preferably, the centring means may comprise a shaft, the shaft receivable in at least one axially extending hole of the input gear, sun gear, and / or rotary output. The shaft may also be referred to as a pin.

[0011] Beneficially, the centring means may comprise a plurality of discontinuous shafts. This allows for centring of a plurality of the different gears, without requiring a continuous shaft between the housing, or adjacent thereto, and the rotary output. The separation between the shafts may prevent or limit vibrations from passing from the rotary output to the sun gear, and so reduce NVH.

[0012] Advantageously, the centring means may comprise at least three discontinuous shafts.

[0013] In a preferable embodiment, the gear assembly further comprises a housing for the gear assembly. The housing may be the housing or case of the parking brake actuator, and may provide a convenient body for use in centring the gears, as well as containing and protecting the components.

[0014] Optionally, the centring means may extend between the housing, or adjacent thereto, and the input gear. As such, the centring means may interengage between the housing, or adjacent thereto, and the input gear.

[0015] Preferably, the centring means may comprise a single shaft which extends from the housing, or adjacent thereto, through the input gear, and terminates in the sun gear.

[0016] Advantageously, a first shaft may extend between the housing, or adjacent thereto, and the input gear, a second shaft may extend between the input gear and the sun gear, and a third shaft may extend between the sun gear and the rotary output.

[0017] Beneficially, there may be no centring means positioned between the input gear and the housing, or adjacent thereto, on an axis of rotation of the input gear. As such, the input gear may be centred by a centring means between the input gear and the sun gear, or by other centring forces. Therefore, vibrations may be prevented or limited from passing from the input gear to the housing, or vice versa. Optionally, there is no centring means positioned between the sun gear and the rotary output on an axis of rotation of the sun gear and / or the rotary output. As such, the sun gear may be centred by a centring means between the input gear and the sun gear, or by other centring forces. Therefore, vibrations may be prevented or limited from passing from the rotary output to the sun gear, or vice versa.

[0018] Additionally, there may be no centring means positioned between the sun gear and the input gear on an axis of rotation of the sun gear and / or the input gear. As such, the sun gear may be centred by a centring means between the rotary output and the sun gear, or by other centring forces. The input gear may be centred by a centring means between the input gear and the housing, or by other centring forces. Therefore, vibrations may be prevented or limited from passing from the input gear to the sun gear, or vice versa.

[0019] Preferably, the centring means may comprise an axial protrusion integral with the input gear and / or rotary output and receivable by the sun gear. As such, instead of a separate centring shaft, a co-formed axial protrusion may act as the centring means on the axis.

[0020] Additionally, the multi-stage planetary gear assembly may further comprise an axial protrusion integral with the sun gear and receivable by the rotary output for centring the sun gear relative to the rotary output.

[0021] According to a second aspect of the present invention, there is provided a multi-stage planetary gear assembly for a parking brake actuator, the planetary gear assembly comprising: a housing; a first planetary stage including an input gear; a second planetary stage including a sun gear, the first planetary stage for driving said sun gear; a rotary output, the second planetary stage for driving the rotary output; and wherein there is no centring means which engages at or adjacent to the housing and which is positioned on an axis of rotation of the input gear.

[0022] Since there is no centring means which engages at or adjacent to the housing, the NVH of the gear assembly and parking brake actuator is improved. This may be due to vibrations being prevented or limited from passing between the gears and the housing.

[0023] Preferably, the multi-stage planetary gear assembly may further comprise a centring means for centring the input gear, sun gear, and / or rotary output on an axis of rotation of the input gear, sun gear, and / or rotary output.

[0024] Beneficially, the centring means may comprise a shaft, the shaft receivable in at least one axially extending hole of the input gear, sun gear, and / or rotary output. Optionally, the centring means may comprise a plurality of discontinuous shafts.

[0025] Advantageously, the centring means may comprise a single shaft which extends between the input gear, sun gear, and rotary output.

[0026] In a preferable embodiment, the centring means may comprise an axial protrusion integral with the input gear, sun gear, and / or rotary output.

[0027] Optionally, there may be no centring means positioned between the sun gear and the rotary output on an axis of rotation of the sun gear and / or the rotary output.

[0028] Additionally or alternatively, there may be no centring means positioned between the sun gear and the input gear on an axis of rotation of the sun gear and / or the input gear.

[0029] Beneficially, the centring means may terminate in the sun gear.

[0030] According to a third aspect of the invention, there is provided a multi-stage planetary gear assembly for a parking brake actuator, the multi-stage planetary gear assembly comprising: a first planetary stage including an input gear; a second planetary stage including a sun gear, the first planetary stage for driving said sun gear; a rotary output, the second planetary stage for driving the rotary output; and a centring means for centring said sun gear and / or the input gear, the centring means being positioned on an axis of the sun gear and / or the input gear; wherein there is no centring means positioned between the sun gear and the rotary output on an axis of rotation of the sun gear and / or the rotary output.

[0031] Since there is no centring means between the sun gear and rotary output, the NVH of the gear assembly and parking brake actuator is improved. This may be due to vibrations being prevented or limited from passing between the sun gear and rotary output.

[0032] Preferably, the centring means may comprise a shaft, the shaft receivable in at least one axially extending hole of the input gear and / or sun gear.

[0033] Advantageously, the centring means may comprise a plurality of discontinuous shafts.

[0034] Additionally, the multi-stage planetary gear assembly may further comprise a housing for the gear assembly.

[0035] Beneficially, the centring means may extend between the housing, or adjacent thereto, and the input gear. Optionally, a first shaft may extend between the housing, or adjacent thereto, and the input gear, and a second shaft may extend between the input gear and the sun gear.

[0036] Preferably, there may be no centring means positioned between the input gear and the housing, or adjacent thereto, on an axis of rotation of the input gear.

[0037] Advantageously, the centring means may terminate in the sun gear.

[0038] Beneficially, the shaft may engage at or adjacent to the housing, extend through an axially extending hole of the input gear, and terminate in the sun gear.

[0039] Alternatively, the centring means may comprise an axial protrusion integral with the input gear or sun gear.

[0040] According to a fourth aspect of the invention, there is provided a multi-stage planetary gear assembly for a parking brake actuator, the multi-stage planetary gear assembly comprising: a first planetary stage including an input gear; a second planetary stage including a sun gear, the first planetary stage for driving said sun gear; a rotary output, the second planetary stage for driving the rotary output; and a centring means for centring the sun gear and / or rotary output which is positioned on an axis of rotation of the input gear and / or rotary output but which is not between the input gear and the sun gear.

[0041] According to a fifth aspect of the invention, there may be provided a parking brake actuator comprising the multi-stage planetary gear assembly of any of the first to fourth aspects of the invention.

[0042] The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which:

[0043] Figure 1 shows a first embodiment of a multi-stage planetary gear assembly in accordance with first and third aspects of the invention;

[0044] Figure 2 shows an exploded view of the multi-stage planetary gear assembly of Figure 1 , with a housing removed;

[0045] Figure 3 shows a side view of the multi-stage planetary gear assembly of Figure 1 ;

[0046] Figure 4 shows a second embodiment of a multi-stage planetary gear assembly in accordance with first and third aspects of the invention; Figure 5 shows a third embodiment of a multi-stage planetary gear assembly in accordance with a first aspect of the invention;

[0047] Figure 6 shows a fourth embodiment of a multi-stage planetary gear assembly in accordance with first and fourth aspects of the invention;

[0048] Figure 7 shows a fifth embodiment of a multi-stage planetary gear assembly in accordance with a first aspect of the invention;

[0049] Figure 8 shows a sixth embodiment of a multi-stage planetary gear assembly in accordance with second and third aspects of the invention;

[0050] Figure 9 shows a seventh embodiment of a multi-stage planetary gear assembly in accordance with first and second aspects of the invention;

[0051] Figure 10 shows an eighth embodiment of a multi-stage planetary gear assembly in accordance with first, second, and fourth aspects of the invention;

[0052] Figure 11 shows a ninth embodiment of a multi-stage planetary gear assembly in accordance with a second aspect of the invention;

[0053] Figure 12 shows a tenth embodiment of a multi-stage planetary gear assembly in accordance with a second aspect of the invention; and

[0054] Figure 13 shows an eleventh embodiment of a multi-stage planetary gear assembly in accordance with a first aspect of the invention.

[0055] The embodiments are all devoid of a centring means which is both on an axis of the input gear, sun gear and / or rotary output and which extends continuously from a housing of the parking brake actuator to a rotary output.

[0056] Referring firstly to Figures 1 to 3, there is shown a first embodiment of a multi-stage planetary gear assembly 10 for an electrical or electronic parking brake actuator. The multi-stage planetary gear assembly 10 is here shown in-situ in a housing 12 of an electronic parking brake actuator.

[0057] The gear assembly 10 includes a first planetary stage 14, a second planetary stage 16, a rotary output 18 and a centring means, which is here provided by a centring shaft 20 or centring pin. The first planetary stage 14 includes an input gear 22 or drive gear and is for providing a rotational input for the gear assembly 10. The input gear may be driven by a toothed belt 24 which may in turn be driven by an electrical motor. However, it will be appreciated that non-belt driven arrangements may be considered, such as driving via an idler gear or a direct drive arrangement.

[0058] The input gear 22 includes a greater diameter outer toothed portion 26 which is for engagement by the belt 24. The input gear 22 further includes a lesser diameter inner toothed portion 28 which forms a sun gear of the first planetary stage 14, and which may hereafter be referred to as the first sun gear 28. The lesser diameter inner toothed portion 28 is received within and fixed relative to the greater diameter outer toothed portion 26, and so rotates therewith.

[0059] The input gear 22 includes a bore 30 or aperture therethrough for receiving the centring shaft 20. The bore 30 may be counterbored, such that the input gear 22 includes a recess 32 at an upper surface from the perspective of Figures 1 to 3.

[0060] The first planetary stage 14 further includes a plurality of first planet gears 34 which are toothed and so configured to be driven by, revolve around, the first sun gear 28. Here there are three such first planet gears 34, although it will be appreciated that other numbers of gears may be considered. Each of the first planet gears 34 includes a connecting means for connecting with a sun gear of the second planetary stage 16, which may hereafter be referred to as the second sun gear 36. The connecting means may be connecting shafts 38, pins or dowels each of which are received in a hole 40 of the first planet gears 34, the hole preferably being a central hole.

[0061] The second sun gear 36 includes a plate 42 or portion for receiving the connecting shafts 38. As such, there are here three holes 44, recesses or bores, for this purpose; one for each of the connecting shafts 38. The connecting shafts 38 therefore bridge the first planet gears 34 and the second sun gear 36. The plate 42 may be generally triangular in shape, with a hole 44 in each corner.

[0062] Whilst separate connecting shafts 38 are described, it will be appreciated that these may be replaced by connecting protrusions which are co-formed or unitarily formed as a one piece with either of the second sun gear or the first planet gear.

[0063] The plate 42 may also include a centring hole 46, such as a recess or bore for receiving the centring shaft 20. Here the centring hole 46 is a recess, such that there is an end which the centring shaft 20 may engage. As such, the centring hole 46 does not extend all the way through the second sun gear 36, and so terminates within the second sun gear 36. The centring hole 46 is preferably at an axial centre or centre portion of the second sun gear 36.

[0064] The second sun gear 36 also includes a depending toothed portion 48 for driving planet gears of the second planetary stage 16, which may be referred to as second planet gears 50. There are here four such second planet gears 50, although it will be appreciated that other numbers of gears may be appreciated. Each of the second planet gears 50 are toothed, and include a hole 52, which is here an aperture for connecting to the rotary output 18.

[0065] The rotary output 18 includes an output portion 54 for connecting to and rotating a rod or shaft. The output portion 54 may be toothed, and so the rotary output 18 may be an output gear.

[0066] The rotary output 18 includes a plate 56 which includes a plurality of connecting protrusions 58 for connecting with the second planet gears 50. Here there is a connecting protrusion 58 for each of the second planet gears 50, and therefore there are four connecting protrusions 58. Each connecting protrusion 58 is received within the hole 52 of one of the second planet gears 50. The connecting protrusions 58 may each include a void or aperture. The plate 42 is here circular although it will be appreciated that other shapes may be considered.

[0067] Although connecting protrusions 58 of the rotary output 18 being received in holes 52 of the second planet gears 50 are disclosed, it will be appreciated that this arrangement may be reversed. Alternatively, there may be connecting shafts, pins or dowels bridging the second planet gears and the rotary output.

[0068] The rotary output 18 does not engage with the centring shaft 20. Additionally, there is no other centring shaft 20 or other centring means between the sun gear and the rotary output 18 on an axis of rotation of the sun gear and / or the rotary output 18. As such, there may not necessarily be a central hole in the rotary output 18 for connecting with the second sun gear 36. The rotary output 18 may be centred solely by centring forces provided by the second planet gears 50, for example.

[0069] The centring shaft 20 is preferably the only centring shaft of the gear arrangement, and as such it is a sole or single centring shaft. The centring shaft 20 is a separate component to each of the sun gear, input gear 22, and housing 12. A first end 60 of the centring shaft 20 engages with, and / or is mounted to, the housing 12 of the parking brake actuator. There may be a bearing between the first end 60 and the housing 12 so that the centring shaft 20 may freely rotate relative to the housing 12.

[0070] Whilst engaging with the housing is shown and described in this embodiment, it will be appreciated that the first end of the centring shaft may in fact be only adjacent to the housing. In this regard, the centring shaft may terminate just short of, and adjacent to, the housing.

[0071] A second end 62 of the centring shaft 20 may terminate in the second sun gear 36. As such, the second end 62 is received in the second sun gear 36. There may similarly be a bearing between the second end 62 and the second sun gear 36.

[0072] There is therefore a centring means for centring the second sun gear 36 relative to the first sun gear 28 or input gear 22 and / or rotary output 18, the centring means being positioned on an axis of the second sun gear 36.

[0073] The first and second planetary stages 14, 16 may be received in a sub-housing 64 or box.

[0074] The sub-housing 64 may be open at each axial end. The first and second planetary stages 14, 16 may be retained in the sub-housing 64 via a retaining ring 66, which has projecting connectors 68 for connecting to the sub-housing 64. Here there are three such projecting connectors 68.

[0075] The interior of the housing 12 may be toothed, for example to mesh with the teeth of the first and second planet gears 50.

[0076] The greater diameter outer toother portion 26 of the input gear 22 may not be in the subhousing 64, and instead may be seated at an exterior of the sub-housing 64. The outer surface of the sub-housing 64 may act as a plain bearing for the input gear 22.

[0077] The parking brake actuator may further include a spacing plate 70 mounted in between the input gear 22 and the housing 12. The spacing plate 70 is mounted at an axial end of the input gear 22 which is distal to the first planetary stage 14.

[0078] The spacing plate 70 preferably includes a connecting protrusion 72 to connect the input gear 22 and the spacing plate 70. The spacing plate 70 is received in the recess 32 which forms a counterbore of the bore of the input gear 22. The spacing plate 70 may additionally include a bore 74 or aperture extending therethrough for receiving the centring shaft 20, since the centring shaft 20 may extend through the spacing plate 70.

[0079] In the instance that the centring shaft extends from adjacent to the housing, rather than from the housing itself, the centring shaft may terminate in the spacing plate, for example. As such the first end of the centring shaft may be at or in the spacing plate.

[0080] There is preferably a resiliently flexible member 76 at the spacing plate 70 and the housing 12, which helps to damp vibration and so reduce NVH. The resiliently flexible member 76 may comprise an elastomer, such as rubber, and may be endless, such as being circular, for example being an O-ring.

[0081] In use, when the parking brake is activated, the electrical motor may operate, causing the belt 24 to turn the input gear 22, which rotates around the centring shaft 20 and drives the first planet gears 34. The first planet gears 34 revolve around the first sun gear 28 which drives the second sun gear 36 to rotate. The rotation of the second sun gear 36 in turn drives the second planet gears 50 around the second sun gear 36 which in turn causes the rotary output 18 to rotate.

[0082] NVH is reduced since there is no continuous centring shaft 20 which extends through the gear assembly 10. In particular, the centring shaft 20 terminates in the second sun gear 36 and there is no centring means between the second sun gear 36 and the output.

[0083] Subsequent embodiments are used in a similar or identical way as the first embodiment.

[0084] Referring now to Figure 4, there is shown a second embodiment of the multi-stage planetary gear assembly 210. Similar or identical reference numerals are used in the second embodiment as in preceding embodiments, except having reference numerals starting with “2”.

[0085] The second embodiment is similar or identical to the second embodiment. However, in the second embodiment, the single centring shaft is replaced by two centring shafts. Additionally, neither of the two centring shafts engages the housing itself.

[0086] A first centring shaft 220a extends from the spacing plate 270, adjacent to the housing, and terminates in the input gear 222. The first centring shaft 220a centres the input gear 222 with the housing 212 and / or the spacing plate 270. It will be appreciated that the first centring shaft may in fact extend from and engage the housing.

[0087] A second centring shaft 220b bridges between the input gear 222 and the second sun gear 236, and so terminates in each. The second centring shaft 220b centres the second sun gear 236 using the input gear 222.

[0088] The second centring shaft 220b is shown as being smaller than the first centring shaft 220, for example being substantially half of the length of the first centring shaft 220. However, it will be appreciated that this may be inverted or the shafts 220a, 220b may be of substantially equal length.

[0089] The input gear 222 may have a continuous bore, or may have two spaced apart axial recesses for receiving each of the centring shafts.

[0090] There is therefore a centring means for centring the second sun gear 236 relative to the input gear 222 and / or rotary output 218, the centring means being positioned on an axis of rotation of the second sun gear 236 and terminating in the second sun gear 236. There is no centring means positioned between the second sun gear 236 and the rotary output 218 on an axis of rotation of the second sun gear 236 and / or the rotary output 218.

[0091] Referring now to Figure 5, there is shown a third embodiment of the multi-stage planetary gear assembly 310. Similar or identical reference numerals are used in the third embodiment as in preceding embodiments, except having reference numerals starting with “3”.

[0092] The third embodiment is similar or identical to the second embodiment, except that a third centring shaft 320c is used which extends between the second sun gear 336 and the rotary output 318. The third centring shaft 320c therefore terminates in both the second sun gear 336 and the rotary output 318. The second sun gear 336 and / or the rotary output 318 may include a continuous bore or may include separate recesses for receiving separate shafts.

[0093] The third centring shaft 320c may be of similar or identical length as the first and / or second centring shafts 320a, 320b.

[0094] There is therefore a centring means for centring the second sun gear 336 relative to the input gear 322 and / or rotary output 318, the centring means being positioned on an axis of rotation of the second sun gear 336 and terminating in the second sun gear 336. Referring now to Figure 6, there is shown a fourth embodiment of the multi-stage planetary gear assembly 410. Similar or identical reference numerals are used in the fourth embodiment as in preceding embodiments, except having reference numerals starting with “4”.

[0095] The fourth embodiment is similar or identical to the third embodiment, except that the second centring shaft is omitted.

[0096] The third centring shaft 420c terminates in the second sun gear 436, and there is no centring means between the input gear 422 and the second sun gear 436 and at an axis of the input gear 422 and / or the second sun gear 436.

[0097] As such, there is a centring means for centring the second sun gear 436 and / or rotary output 418 which is positioned on an axis of rotation of the input gear 422 and / or rotary output 418 but which is not between the input gear 422 and the second sun gear 436.

[0098] Referring now to Figure 7, there is shown a fifth embodiment of the multi-stage planetary gear assembly 510. Similar or identical reference numerals are used in the fifth embodiment as in preceding embodiments, except having reference numerals starting with “5”.

[0099] The fifth embodiment is similar or identical to the third embodiment, except that the first and second centring shafts are a single shaft 520 which extends from the housing 512, as per the first embodiment. This centring shaft 520, along with what was referred to as the third centring shaft 520c in some preceding embodiments, terminates in the second sun gear 536.

[0100] It will be appreciated that the single shaft may extend from the spacing plate.

[0101] Referring now to Figure 8, there is shown a sixth embodiment of the multi-stage planetary gear assembly 610. Similar or identical reference numerals are used in the sixth embodiment as in preceding embodiments, except having reference numerals starting with “6”.

[0102] The sixth embodiment is similar or identical to the first embodiment except that the centring shaft 620 does not engage the housing 612, and / or the spacing plate 670. As such, there is no centring means which engages at or adjacent to the housing 612 and which is positioned on an axis of rotation of the input gear 622. Additionally, there is no centring means positioned between the second sun gear 636 and the rotary output 618 on an axis of rotation of the second sun gear 636 and / or the rotary output 618. The centring shaft 620 terminates in the second sun gear 636.

[0103] Referring now to Figure 9, there is shown an seventh embodiment of the multi-stage planetary gear assembly 710. Similar or identical reference numerals are used in the seventh embodiment as in preceding embodiments, except having reference numerals starting with an “7”.

[0104] The seventh embodiment is similar or identical to the sixth embodiment, except that there is a further centring shaft 720c, which is similar or identical to the third centring shaft of some of the preceding embodiments, between the second sun gear 736 and the rotary output 718.

[0105] There is no centring means which engages the housing 712, and / or the spacing plate 770, and which is positioned on an axis of rotation of the input gear 722.

[0106] The centring shaft 720 and further centring shaft 720c terminate in the second sun gear 736.

[0107] The centring shaft 720 of the seventh embodiment may be shorter than that of the sixth embodiment.

[0108] Referring now to Figure 10, there is shown a eighth embodiment of the multi-stage planetary gear assembly 810.

[0109] Similar or identical reference numerals are used in the eighth embodiment as in preceding embodiments, except having reference numerals starting with “8”.

[0110] The eighth embodiment is similar or identical to the fourth embodiment, except that the first centring shaft is also omitted. As such, the arrangement has only a sole centring shaft 820. The centring shaft 820 extends between the second sun gear 836 and the rotary output 818.

[0111] As such, there is a centring means for centring the sun gear and / or rotary output 818 which is positioned on an axis of rotation of the input gear 822 and / or rotary output 818, and which terminates in the second sun gear 836, but which is not between the input gear 822 and the second sun gear 836. Additionally, there is no centring means which engages the housing 812, and / or the spacing plate 870, and which is positioned on an axis of rotation of the input gear 822. Referring now to Figure 11 , there is shown a ninth embodiment of the multi-stage planetary gear assembly 910.

[0112] Similar or identical reference numerals are used in the ninth embodiment as in preceding embodiments, except having reference numerals starting with “9”.

[0113] The ninth embodiment is similar or identical to the seventh embodiment, except that the centring shaft and the further centring shaft of the seventh embodiment are provided as a single centring shaft 920.

[0114] There is no centring means which engages the housing 912, and / or the spacing plate 970, and which is positioned on an axis of rotation of the input gear 922.

[0115] Referring now to Figure 12, there is shown a tenth embodiment of the multi-stage planetary gear assembly 1010.

[0116] Similar or identical reference numerals are used in the ninth embodiment as in preceding embodiments, except having reference numerals starting with “10”.

[0117] The ninth embodiment is similar or identical to the preceding embodiments, except that there is no centring shaft, or any centring means provided on an axis of any of the gears.

[0118] As such, there is no centring means which engages the housing 1012, and / or the spacing plate 1070, and which is positioned on an axis of rotation of the input gear 1022. There is also no centring means positioned between the second sun gear 1036 and the rotary output 1018 on an axis of rotation of the sun gear and / or the rotary output 1018.

[0119] It will be appreciated that any rotary component, in any of the embodiments, which does not have a centring means on an axis of rotation of the component, may be centred by centring forces provided by other rotary components, for example.

[0120] It will be appreciated that there may be a bearing received between the end or a surface of any of the shafts of any of the embodiments, and the component at or in which the end or surface is received.

[0121] Throughout the description, the centring means positioned on the axis of rotation of the rotary parts is described as a centring shaft or pin. However, it will be appreciated that such a centring shaft or pin may be replaced with an axial protrusion integral with the input gear or first sun gear, second sun gear and / or rotary output, and received by an adjacent gear or output. An example of this is shown in Figure 13, in an eleventh embodiment of the multi-stage planetary gear assembly 1110. The eleventh embodiment is similar or identical to the fifth embodiment, except that the centring shaft between the second sun gear and the rotary output is replaced by an axial protrusion 1120c integral with the second sun gear 1136 and which is received by a hole or recess in the rotary output 1118.

[0122] It is therefore possible to provide a variety of gear box arrangements for a parking brake actuator which are devoid of a centring means which is both on an axis of the input gear, sun gear and / or rotary output and which extends continuously from a housing of the parking brake actuator to a rotary output. This improves the NVH of the parking brake actuator.

[0123] The words ‘comprises / comprising’ and the words ‘having / including’ when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0124] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

[0125] The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein.

Claims

Claims1. A multi-stage planetary gear assembly (10) for a parking brake actuator, the multi-stage planetary gear assembly (10) comprising: a first planetary stage (14) including an input gear (22); a second planetary stage (16) including a sun gear (36), the first planetary stage (14) for driving said sun gear (36); a rotary output (18), the second planetary stage (16) for driving the rotary output (18); and a centring means for centring said sun gear (36) relative to the input gear (22) and / or rotary output (18), the centring means being positioned on an axis of rotation of said sun gear (36) and terminating in said sun gear (36).

2. A multi-stage planetary gear assembly (10) as claimed in claim 1 , wherein the centring means comprises a shaft (20), the shaft (20) receivable in at least one axially extending hole (30, 46) of the input gear (22), sun gear (36), and / or rotary output (18).

3. A multi-stage planetary gear assembly (210) as claimed in claim 2, wherein the centring means comprises a plurality of discontinuous shafts (220a, 220b).

4. A multi-stage planetary gear assembly (310) as claimed in claim 3, wherein the centring means comprises at least three discontinuous shafts (320a, 320b, 320c).

5. A multi-stage planetary gear assembly (10) as claimed in any one of the preceding claims, further comprising a housing (12) for the gear assembly (10).

6. A multi-stage planetary gear assembly (10) as claimed in claim 5, wherein the centring means extends between the housing (12), or adjacent thereto, and the input gear (22).

7. A multi-stage planetary gear assembly (10) as claimed in claim 2 and claim 6, wherein the centring means comprises a single shaft (20) which extends from the housing (12), or adjacent thereto, through the input gear (22), and terminates in the sun gear (36).

8. A multi-stage planetary gear assembly (310) as claimed in claim 4 and claim 6, wherein a first shaft (320a) extends between the housing (312), or adjacent thereto, and the input gear, a second shaft (320b) extends between the input gear and the sun gear (336), and a third shaft (320c) extends between the sun gear (336) and the rotary output (318).

9. A multi-stage planetary gear assembly (710) as claimed in any one of claims 1 to 5, wherein there is no centring means positioned between the input gear (722) and at or adjacent to the housing (712) on an axis of rotation of the input gear (722).

10. A multi-stage planetary gear assembly (10) as claimed in any one of the preceding claims, wherein there is no centring means positioned between the sun gear (36) and the rotary output (18) on an axis of rotation of the sun gear (36) and / or the rotary output (18).11 . A multi-stage planetary gear assembly (410) as claimed in any one of claims 1 to 6 and 9, wherein there is no centring means positioned between the sun gear (436) and the input gear (422) on an axis of rotation of the sun gear (436) and / or the input gear (422).

12. A multi-stage planetary gear assembly as claimed in any one of claims 1 to 9 and 11 , further comprising an axial protrusion integral with the sun gear and receivable by the rotary output for centring the sun gear relative to the rotary output.

13. A multi-stage planetary gear assembly (610) for a parking brake actuator, the planetary gear assembly (610) comprising: a housing (612); a first planetary stage including an input gear (622); a second planetary stage including a sun gear (636), the first planetary stage for driving said sun gear (636); a rotary output (618), the second planetary stage (616) for driving the rotary output (618); andwherein there is no centring means which engages at or adjacent to the housing (612) and which is positioned on an axis of rotation of the input gear (622).

14. A multi-stage planetary gear assembly (610) as claimed in claim 13, further comprising a centring means for centring the input gear (622), sun gear (636), and / or rotary output (618) on an axis of rotation of the input gear (622), sun gear (636), and / or rotary output (618).

15. A multi-stage planetary gear assembly (610) as claimed in claim 14, wherein the centring means comprises a shaft (620), the shaft (620) receivable in at least one axially extending hole of the input gear (622), sun gear (636), and / or rotary output (618).

16. A multi-stage planetary gear assembly (710) as claimed in claim 15, wherein the centring means comprises a plurality of discontinuous shafts (720, 720c).

17. A multi-stage planetary gear assembly (910) as claimed in claim 15, wherein the centring means comprises a single shaft (920) which extends between the input gear (922), sun gear, and rotary output.

18. A multi-stage planetary gear assembly (610) as claimed in any one of claims 13 to 16, wherein there is no centring means positioned between the sun gear (636) and the rotary output (618) on an axis of rotation of the sun gear (636) and / or the rotary output (618).

19. A multi-stage planetary gear assembly (810) as claimed in any one of claims 13 to 16 and 18, wherein there is no centring means positioned between the sun gear (836) and the input gear (822) on an axis of rotation of the sun gear (836) and / or the input gear (822).

20. A multi-stage planetary gear assembly (710) as claimed in any one of claims 13 to 16 and 18 to 19, wherein the centring means terminates in the sun gear (736).

21. A multi-stage planetary gear assembly as claimed in claim 14 and 18 to 20, wherein the centring means comprises an axial protrusion integral with the input gear, sun gear, and / or rotary output.

22. A multi-stage planetary gear assembly (10) for a parking brake actuator, the multi-stage planetary gear assembly (10) comprising: a first planetary stage (14) including an input gear (22); a second planetary stage (16) including a sun gear (36), the first planetary stage (14) for driving said sun gear (36); a rotary output (18), the second planetary stage (16) for driving the rotary output (18); and a centring means for centring said sun gear (36) and / or the input gear (22), the centring means being positioned on an axis of the sun gear (36) and / or the input gear (22); wherein there is no centring means positioned between the sun gear (36) and the rotary output (18) on an axis of rotation of the sun gear (36) and / or the rotary output (18).

23. A multi-stage planetary gear assembly (10) as claimed in claim 22, wherein the centring means comprises a shaft (20), the shaft (20) receivable in at least one axially extending hole (30) of the input gear (22) and / or sun gear (36).

24. A multi-stage planetary gear assembly (210) as claimed in claim 23, wherein the centring means comprises a plurality of discontinuous shafts (220a, 220b).

25. A multi-stage planetary gear assembly (10) as claimed in any one of claims 22 to 24, further comprising a housing (12) for the gear assembly (10).

26. A multi-stage planetary gear assembly (10) as claimed in claim 25, wherein the centring means extends between the housing (12), or adjacent thereto, and the input gear (22).

27. A multi-stage planetary gear assembly (210) as claimed in claim 24 and claim 26, wherein a first shaft (220a) extends between the housing (212), or adjacent thereto, and the input gear (222), and a second shaft (220b) extends between the input gear (222) and the sun gear (236).

28. A multi-stage planetary gear assembly (10) as claimed in any one of claims 22 to 27, wherein the centring means terminates in the sun gear (36).

29. A multi-stage planetary gear assembly (10) as claimed in claim 23, claim 26, and claim 28 when not dependent on claim 24, wherein the shaft (20) engages at or adjacent to the housing (12), extends through an axially extending hole of the input gear (22), and terminates in the sun gear (36).

30. A multi-stage planetary gear assembly (610) as claimed in any one of claims 22 to 26, and 28 when not dependent on claim 27, wherein there is no centring means positioned between the input gear (622) and the housing (612), or adjacent thereto, on an axis of rotation of the input gear (622).31 . A multi-stage planetary gear assembly as claimed in any one of claims 22,25, 26, 28 and 30, when not dependent on claims 23, 24, 27 and 29 wherein the centring means comprises an axial protrusion integral with the input gear or sun gear.

32. A parking brake actuator comprising the multi-stage planetary gear assembly (10) as claimed in any one of the preceding claims.

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