actuator

Abstract

An actuator (10) for an electronic parking brake assembly, the actuator (10) having a housing (12); a motor (60) located within the housing (12), the motor (60) having an output shaft (32); a gear assembly (14) located within the housing (12) and spaced apart from the motor (60), the output shaft (32) of the motor (60) being configured to drive the gear assembly (14); a motor damping element (36) mounted adjacent to the output shaft (32) and engaging the housing (12); and a gear-assembly damping element (48) mounted to the gear assembly (14) and engaging the housing (12), wherein the motor damping element (36) and the gear-assembly damping element (48) are spaced apart from one another. A dampener assembly is also provided.

Description

[0001] Actuator

[0002] The present invention relates to an actuator for an electronic parking brake assembly.

[0003] The invention further relates to a dampener assembly for an actuator.

[0004] An actuator of an electrical or electronic parking brake generally comprises of a motor and a gear assembly, or gear box.

[0005] When the electronic parking brake is activated, for example by pressing a button, the motor rotates and the rotational motion is transmitted to an idler 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 output gear is transmitted, transferred and / or converted to ultimately result in the brakes being actuated and prevent the wheels from rotating.

[0006] The motor and the gear assembly are generally housed within a casing or housing. The movement of the motor and the gear assembly causes the housing and any other internal features of the electronic parking brake to vibrate and generate noise, vibration, and / or harshness (NVH).

[0007] NVH is undesirable, particularly in high-end vehicles. A single spacing plate is conventionally used to space the gear assembly and the motor, and a dampener is mounted between the spacing plate and the housing in an attempt to reduce the NVH. The dampener is generally one piece of rubber or other elastomeric material which extends between the housing and both of the motor and the gear assembly.

[0008] However, it has been determined that such an arrangement still generates an undesirable amount of NVH.

[0009] It is an object of the present invention to reduce or substantially obviate the above problems.

[0010] According to a first aspect of the invention, there is provided an actuator for an electronic parking brake assembly, the actuator comprising: a housing; a motor located within the housing, the motor having an output shaft; a gear assembly located within the housing and spaced apart from the motor, the output shaft of the motor being configured to drive the gear assembly; a motor damping element mounted adjacent to the output shaft and engaging the housing; and a gear-assembly damping element mounted to the gear assembly and engaging the housing, wherein the motor damping element and the gear-assembly damping element are spaced apart from one another. Providing a motor damping element which is separate to a gear-assembly damping element, rather than a single spacing plate, reduces overall NVH. It is thought that this may be due to allowing individual, and so more effective, damping of the motor and gear assembly, since these components may vibrate at different frequencies to each other. The motor damping element and gear-assembly damping element may be referred to as damping plates.

[0011] Preferably, the motor comprises a motor body having an output-shaft surface from which the output shaft extends, the motor damping element comprises an elongate member extending between the output-shaft surface of the motor and the housing. The elongate member provides the motor damping element with a means for securing the motor damping element against the housing and further prevents the motor damping element from vibrating and producing NVH.

[0012] Advantageously, at least one of a group consisting of a first motor-damping resiliently flexible member and a second motor-damping resiliently flexible member is positioned on the motor damping element, the first and second motor-damping resiliently flexible member engaging the housing. The first and second motor-damping resiliently flexible members advantageously engage the housing to absorb and reduce NVH. The motordamping resiliently flexible member may comprise an elastomeric material.

[0013] Preferably, the first motor-damping resiliently flexible member is mounted to the elongate member and engages the housing. The first motor-damping resiliently flexible member advantageously engages the housing to absorb and reduce NVH.

[0014] Preferably, the first motor-damping resiliently flexible member is endless. In other words, the motor-damping resiliently flexible member is continuous, such as being elliptical or circular.

[0015] Optionally, a shaft gear is positioned around the output shaft, the first and second motor-damping resiliently flexible members are at opposite ends of a diameter of the circular cross section of the shaft gear to each other. The shaft gear rotates with the output shaft which in turn rotates the gear assembly and activates the brakes.

[0016] Advantageously, the motor damping element has a plate-like body and two walls extending from the plate-like body, the second motor-damping resiliently flexible member being positioned between the two walls. Beneficially, the second motor-damping resiliently flexible member has a T-shaped cross-section, a groove is defined in a middle of a vertical arm to divide a horizontal arm of the second motor-damping resiliently flexible member into left and right side arms, a seated-member portion extends from a portion of the housing and is configured to enter the groove and press the left and right side arms of the second motor-damping resiliently flexible member.

[0017] Preferably, the gear assembly comprises at least one drive gear. The drive gear is an input gear which when rotated allows the further gears within the gear assembly to rotate also.

[0018] Advantageously, the shaft gear is configured to drive the gear assembly via a belt extending between the shaft gear and the drive gear. The shaft gear and drive gear are connected to one another via the belt which allows the shaft gear and drive gear to rotate at the same time.

[0019] Optionally, the drive gear is rotatably mounted to the gear-assembly damping element. As the drive gear rotates, this may result in vibration. Having the gear-assembly damping element mounted to the drive gear allows for NVH to be reduced. Additionally, the drive gear may be the closest gear to the housing, and so it may be most convenient to mount the damping element to the drive gear.

[0020] Preferably, the gear-assembly damping element further comprises a gear-assembly resiliently flexible member thereon, the gear-assembly resiliently flexible member contacting the housing. As the drive gear rotates, this may result in vibration and so having the gear-assembly resiliently flexible member mounted thereon will reduce the NVH.

[0021] Optionally, the gear-assembly resiliently flexible member is endless. Since the resiliently flexible member is endless, it may be less likely to be displaced from the gear-assembly damping element.

[0022] Preferably, the actuator further comprises a motor-mounting element fixed on the housing adjacent to the motor which receives a portion of the motor damping element. The motor-mounting element receives a portion of the motor damping element and element provides the motor damping element with a point of fixation so that preferably no other fixation means, such as screws, are required to fix the motor damping element to the output-shaft surface of the motor. NVH is reduced as the motor damping element is secured to the motor-mounting element. Advantageously, a housing-contact surface of the motor damping element is offset to a housing-contact surface of the gear-assembly damping element relative to an axis of the gear assembly. The offset allows the features to be correctly positioned within the actuator.

[0023] According to a second aspect of the invention, there is provided a dampener assembly for an actuator as claimed in any of the preceding claims, the dampener assembly comprising: a motor damping element mounted adjacent to the output shaft of the motor and engaging the housing; and a gear-assembly damping element mounted to the gear assembly and engaging the housing, wherein the motor damping element and the gear-assembly damping element are spaced apart from one another.

[0024] Reference will now be made by way of example only to the accompanying drawings, in which:

[0025] Figure 1 is a perspective view of an actuator for electronic parking brake assembly, in accordance with a first aspect of the invention, the actuator omitting a portion of a housing;

[0026] Figure 2 is a further view of the actuator of Figure 1 ;

[0027] Figure 3 is a perspective view of the actuator of Figure 1 not omitting the portion of the housing but with internal features exposed;

[0028] Figure 4 is a cross sectional view of the actuator along line A-A of Figure 2 and including the portion of the housing; and

[0029] Figure 5 is an exploded view of the actuator of Figure 3.

[0030] Referring firstly to Figures 1 and 2, there is shown an actuator, referenced globally at 10, for an electrical or electronic vehicle parking brake. The actuator 10 has a housing 12 which houses a motor (not shown in Figures 1 and 2) and a gear assembly 14, the motor and gear assembly 14 being spaced apart from one another.

[0031] A first portion 16 of the housing 12 is dimensioned to receive the motor and the gear assembly 14. A second portion 18 of the housing 12 is omitted in Figures 1 and 2 for clarity, the second portion 18 being shown in Figure 3. The housing 12 has a larger width at a gear-assembly portion 20 than at a motor portion 22, and may be made of an insulating material, such as plastic. A sleeve 24 extends from the first portion 16 of the housing 12 for containing an electricity input (not shown) to provide electricity to the motor.

[0032] The motor is disposed within the housing 12, a body of the motor being cylindrical in shape. The motor has two electrical terminals 26 extending from the body of the motor, specifically extending from an output-shaft surface 28 of the body. The electrical terminals 26 are at opposite ends of a diameter of the circular cross section of the motor to each other.

[0033] The electrical terminals 26 are in contact with the electricity input via electrical connections 30, which are here shown as wires.

[0034] An output shaft 32 of the motor extends from the output-shaft surface 28, particularly from a central portion of the output-shaft surface 28. The output shaft 32 is configured to rotate when the motor is activated, and is configured to drive the gear assembly 14.

[0035] A gear is located around the output shaft 32 such that the gear rotates with the rotating output shaft 32. Said gear may be referred to as a shaft gear 34.

[0036] A motor damping element 36 is located between the output-shaft surface 28 and the shaft gear 34 and is adjacent to the output shaft 32. The motor damping element 36 is mounted onto the output-shaft surface 28 of the motor. The motor damping element 36 covers substantially all of the output-shaft surface 28 of the motor.

[0037] The motor damping element 36 has a generally plate-like body 38 and an elongate member 40 extending from the said plate-like body 38. Two walls 42 extend from the plate-like body 38. The elongate member 40 is spaced apart from the output shaft 32.

[0038] The elongate member 40 of the motor damping element 36 extends between the output-shaft surface 28 of the motor and the second portion 18 of the housing 12. The elongate member 40 may contact the second portion 18 of the housing 12 to restrict the motor and the motor damping element 36 vibrating.

[0039] At least one motor-damping resiliently flexible member 44a, 44b is located on the motor damping element 36. The at least one motor-damping resiliently flexible member 44a, 44b is made of an elastomeric material such as rubber.

[0040] The at least one motor-damping resiliently flexible member 44a, 44b contacts the second portion 18 of the housing 12 to restrict the vibration of the actuator 10. The motor-damping resiliently flexible members 44a, 44b are located between the motor damping element 36 and second portion 18 of the housing 12.

[0041] One of the said motor-damping resiliently flexible members 44a is mounted on the elongate member 40 and engages the housing 12. The motor-damping resiliently flexible member 44a absorbs vibration and resonance created from the moving motor. The motor-damping resiliently flexible member 44a is oval or elliptical in shape and is therefore endless.

[0042] One of the motor-damping resiliently flexible members 44b is a seated resiliently flexible member 44b. A portion of the seated resiliently flexible member 44b is mounted on a surface of the motor damping element 36 parallel to the output-shaft surface 28.

[0043] The two walls 42 extend from the motor damping element 36 and effectively sandwich the seated resiliently flexible member 44b between the said walls 42.

[0044] The gear assembly 14 comprises at least one drive gear 46. A gear-assembly damping element 48 is mounted on the drive gear 46 which remains stationary when the drive gear 46 is rotated. The gear-assembly damping element 48 has a substantially circular cross section. The gear-assembly damping element 48 is spaced apart from the motor damping element 36. The gear-assembly damping element 48 is generally plate-like.

[0045] The gear-assembly damping element 48 and the motor damping element 36 are spaced apart from one another. Vibration from the motor is therefore not transmitted to the gear-assembly damping element 48 from the motor damping element 36 and / or vice versa, resulting in an actuator 10 with less NVH.

[0046] A gear-assembly resiliently flexible member 49 is mounted on the gear-assembly damping element 48. The gear-assembly resiliently flexible member 49 is a ring and is therefore endless. The gear-assembly resiliently flexible member 49 is made of an elastomeric material such as rubber. The gear-assembly resiliently flexible member 49 is located between the gear-assembly damping element 48 and second portion 18 of the housing 12.

[0047] A belt 50 extends between and around the shaft gear 34 and the drive gear 46 such that, in use, when the shaft gear 34 rotates, the belt 50 moves and rotates the drive gear 46. The belt 50 is endless and made of a flexible material such as rubber.

[0048] Referring to Figure 3, the internal elements of the actuator 10 are exposed within the housing 12. The housing 12 is shown to further comprise the second portion 18 which acts as a cap to substantially enclose the elements within the housing 12. The second portion 18 is dimensioned to receive the motor damping element 36, the drive gear 46 and the gear-assembly damping element 48.

[0049] The first portion 16 comprises an opening 52 at the gear-assembly portion 20. A rotary output 54 of the gear assembly 14 extends through the opening 52 to allow onward transmission of rotational forces outside of the housing 12. The rotary output 54 is at an opposite end of the gear assembly 14 to the drive gear 46, as more clearly seen in Figure 5.

[0050] A motor-mounting element 56 is at or adjacent to the body 58 of the motor 60, the motor-mounting element 56 being in contact with the first portion 16 of the housing 12. The motor-mounting element 56 may be fixed to, or integrally formed with, the first portion 16. The motor-mounting element 56 receives a portion of the motor damping element 36, the portion of the motor damping element 36 extends away from the output-shaft surface 28 of the motor 60. The motor-mounting element 56 provides the motor damping element 36 with a point of fixation so that preferably no other fixation means, such as screws, are required to fix the motor damping element 36 to the outputshaft surface 28 of the motor 60.

[0051] Referring to Figure 4, there is shown a cross sectional view of the actuator 10 along line A-A of Figure 2 and including the second portion 18 of the housing 12. Such a view more clearly shows the relative positioning of some features of the actuator 10, as will be described below.

[0052] The motor damping element 36 has a housing-contact surface 62 and the gearassembly damping element 48 has a housing-contact surface 64. The housing-contact surface 62 of the motor damping element 36 is offset to the housing-contact surface 64 of the gear-assembly damping element 48 relative to an axis of the gear assembly 14. In other words, the housing-contact surface 64 of the gear-assembly damping element 48 is elevated, from the perspective of Figure 4, relative to the housing-contact surface 62 of the motor damping element 36.

[0053] The output shaft 32 extends through the motor damping element 36, the motor damping element 36 having a through hole 66 for receiving the output shaft 32.

[0054] The shaft gear 34 is spaced apart from the motor body 58 of the motor 60 and thus surrounds a portion of the output shaft 32 distal from the motor 60. The drive gear 46 and the shaft gear 34 are aligned with one another such that the belt 50 remains and rotates in one plane.

[0055] The second portion 18 of the housing 12 has a seated-member portion 68 which extends from the second portion 18 to the seated resiliently flexible member 44b. The seated resiliently flexible member 44b is therefore kept in place and restricts the vibration transferred from the vibrating motor 60 to the housing 12.

[0056] The gear assembly 14 comprises a plurality of gears 70 which rotate with the drive gear 46 and drive the rotary output 54.

[0057] Referring to Figure 5, there is shown an exploded view of the actuator 10.

[0058] Situated at a motor-support surface 72 opposite to the output-shaft surface 28 of the motor 60, there is a motor support 74 located between the motor-support surface 72 and the first portion 16 of the housing 12. The motor support 74 acts as a further dampener and thus restricts vibration of the actuator 10.

[0059] The motor-mounting element 56 has two dampener receivers 76, or apertures, for receiving two motor-damping protrusions 78. The motor-damping protrusions 78 protrude from the plate-like body 38 of the motor damping element 36 in an opposing direction to the elongate member 40. This interaction between the dampener receivers 76 and the motor-damping protrusions 78 secures the motor damping element 36 to the housing 12.

[0060] The plurality of gears 70 of the gear assembly 14 are visible in Figure 5. The rotation of the drive gear 46 causes the plurality of gears 70 to rotate the rotary output 54 which drives a rotating output shaft or rod located at the output surface of the gear assembly 14. The plurality of gears 70 is rotationally communicable with the rotating output shaft or rod.

[0061] In use, a user presses a button in the vehicle to apply the parking brake. An electric signal is sent to the electricity input which activates the motor 60 via the electrical connections 30.

[0062] The motor 60 rotates within the body 58, which in turn rotates the output shaft 32 and the shaft gear 34 attached thereto. Any vibration generated from the movement of the motor 60 is restricted due to the motor damping element 36 and at least one motordamping resiliently flexible member 44a, 44b. The output shaft 32 is configured to drive the gear assembly 14 via the belt 50. The belt 50 is located around the shaft gear 34 and the drive gear 46 such that as the shaft gear 34 rotates, the belt 50 moves and causes the drive gear 46 to rotate. The gearassembly damping element 48 is mounted on the drive gear 46 and remains stationary as the drive gear 46 rotates. The gear-assembly resiliently flexible member 49 is mounted on the gear-assembly damping element 48 and any vibration generated from the movement of the drive gear 46 and gear assembly 14 is restricted.

[0063] As the drive gear 46 rotates, the plurality of gears 70 within the gear assembly 14 also rotate. The rotary output 54 rotates and drives the rotating output shaft or rod located at the output surface of the gear assembly 14.

[0064] The rotating output shaft or rod, and thus output surface, is connectable to a brake piston. The rotational movement of the gear assembly 14 is converted to thrust which pushes the brake piston against the brake pads and brake discs of the vehicle and prevents the wheels from moving.

[0065] In an alternative embodiment, the sleeve may extend from the second portion or first and second portion of the housing.

[0066] In an alternative embodiment, the motor damping element does not cover substantially all of the output-shaft surface of the motor and instead covers a portion, less than half, half, or more than half of the output-shaft surface.

[0067] In an alternative embodiment, there may not be a belt and instead an idler gear may be used to transfer the rotation of the shaft gear to the drive gear. In this alternative embodiment, the elongate member may be removed, and an idler dampener may be mounted on the idler gear to restrict the vibration of the actuator.

[0068] In an alternative embodiment, the housing may be formed of one piece of material.

[0069] In an alternative embodiment, the housing contact surface of the motor damping element is level with the housing-contact surface of the gear-assembly damping element.

[0070] In an alternative embodiment, the motor-mounting element is attached to the body of the motor.

[0071] It is therefore possible to provide an actuator comprising a dampener on the motor and a dampener on the gear assembly, the dampeners being spaced apart from one another and therefore restrict the amount of vibration which is transferred from one dampener to another. This restriction of vibration results in a quieter braking mechanism which is more desirable for vehicles, particularly high-end vehicles.

[0072] 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.

[0073] 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.

[0074] The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.

Claims

Claims1. An actuator (10) for an electronic parking brake assembly, the actuator (10) comprising: a housing (12); a motor (60) located within the housing (12), the motor (60) having an output shaft (32); a gear assembly (14) located within the housing (12) and spaced apart from the motor (60), the output shaft (32) of the motor (60) being configured to drive the gear assembly (14); a motor damping element (36) mounted adjacent to the output shaft (32) and engaging the housing; and a gear-assembly damping element (48) mounted to the gear assembly (14) and engaging the housing (12), wherein the motor damping element (36) and the gear-assembly damping element (48) are spaced apart from one another.

2. An actuator (10) as claimed in claim 1 , wherein the motor (60) comprises a motor body (58) having an output-shaft surface (28) from which the output shaft (32) extends, the motor damping element (36) comprises an elongate member (40) extending between the output-shaft surface (28) of the motor (60) and the housing (12).

3. An actuator (10) as claimed in any of the preceding claims, wherein at least one of a group consisting of a first motor-damping resiliently flexible member (44a) and a second motor-damping resiliently flexible member (44b) is positioned on the motor damping element (36), the first and second motordamping resiliently flexible member (44a, 44b) engaging the housing (12).

4. An actuator (10) as claimed in claim 3, wherein the first motor-damping resiliently flexible member (44a) is mounted to the elongate member (40) and engages the housing (12).

5. An actuator (10) as claimed in claim 4, wherein the first motor-damping resiliently flexible member (44a) is endless.

6. An actuator (10) as claimed in any of the preceding claims, wherein a shaft gear (34) is positioned around the output shaft (32), the first and second motordamping resiliently flexible members (44a, 44b) are at opposite ends of a diameter of the circular cross section of the shaft gear (34) to each other.

7. An actuator (10) as claimed in any one of claims 3 to 6, wherein the motor damping element (36) has a plate-like body (38) and two walls (42) extending from the plate-like body (38), the second motor-damping resiliently flexible member (44b) being positioned between the two walls (42).

8. An actuator (10) as claimed in claim 7, wherein the second motor-damping resiliently flexible member (44b) has a T-shaped cross-section, a groove is defined in a middle of a vertical arm to divide a horizontal arm of the second motor-damping resiliently flexible member (44b) into left and right side arms, a seated-member portion (68) extends from a portion (18) of the housing (12) and is configured to enter the groove and press the left and right side arms of the second motor-damping resiliently flexible member (44b).

9. An actuator (10) as claimed in any of the preceding claims, wherein the gear assembly (14) comprises at least one drive gear (46), the shaft gear (34) is configured to drive the gear assembly (14) via a belt (50) extending between the shaft gear (34) and the drive gear (46).

10. An actuator (10) as claimed in claim 9, wherein the drive gear (46) is rotatably mounted to the gear-assembly damping element (48).

11. An actuator (10) as claimed in any of the preceding claims, wherein the gearassembly damping element (48) further comprises a gear-assembly resiliently flexible member (49) thereon, the gear-assembly resiliently flexible member (49) contacting the housing (12).

12. An actuator (10) as claimed in claim 11 , wherein the gear-assembly resiliently flexible member (49) is endless.

13. An actuator (10) as claimed in any of the preceding claims, further comprising a motor-mounting element (56) fixed on the housing (16) and adjacent to the motor (60) which receives a portion of the motor damping element (36).

14. An actuator (10) as claimed in any of the preceding claims, wherein a housingcontact surface (62) of the motor damping element (36) is offset to a housing-contact surface (64) of the gear-assembly damping element (48) relative to an axis of the gear assembly (14).

15. A dampener assembly for an actuator (10) as claimed in any of the preceding claims, the dampener assembly comprising: a motor damping element (36) mounted adjacent to the output shaft (32) of the motor (60) and engaging the housing (12); and a gear-assembly damping element (48) mounted to the gear assembly(14) and engaging the housing (12), wherein the motor damping element (36) and the gear-assembly damping element (48) are spaced apart from one another.

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