GB2540494A

GB2540494A - Electric-park-brake actuator with integrated motor

Info

Publication number: GB2540494A
Application number: GB1617625.7A
Authority: GB
Inventors: Bourqui Yvan
Original assignee: Johnson Electric SA
Current assignee: Johnson Electric SA
Priority date: 2016-10-18
Filing date: 2016-10-18
Publication date: 2017-01-18
Also published as: GB201617625D0

Abstract

An electric park brake (EPB) actuator unit 10 comprises an actuator housing 12 and a motor housing 14 integrally formed as one-piece with an actuator wall 18 of the actuator housing 12. The motor housing may include a stator 26 abutting the actuator wall and a rotor 24 received therein with a drive shaft 20 extending through the actuator wall into the interior of the actuator housing, wherein the shaft may be supported by a bearing 28 formed on the actuator wall. The EPB actuator may be used on a vehicle disc brake calliper and the actuator wall may support the drive shaft to inhibit any misalignment caused by relative movement between the motor and actuator.

Description

Electric-Park-Brake Actuator With Integrated Motor

The present invention relates to an Electric Park Brake, hereinafter EPB, actuator unit with integrated motor, to a vehicle-brake calliper having such an EPB actuator unit mounted thereon, and to a vehicle utilising the vehicle-brake calliper.

An EPB actuator unit is known which utilises a separate motor housing that abuts an EPB actuator housing. However, this can lead to the motor housing moving relative to the actuator housing, and also therefore a drive shaft of the motor which projects into the actuator housing moving laterally causing disengagement from a gear train mechanism within the actuator housing. This then results in inconsistent application of the required braking force to the brake calliper, and thus associated pistons and brake pads, to which the actuator housing is directly or indirectly attached.

The present invention seeks to provide a solution to these problems.

According to a first aspect of the invention, there is provided an EPB actuator unit comprising an actuator housing and a motor housing integrally formed as one-piece with an actuator wall of the actuator housing.

Preferably, the motor housing includes a stator abutable with the actuator wall, and a rotor receivable therein. In this case, a drive shaft is rotatable by the rotor and extends through the actuator wall into an interior of the actuator housing.

The actuator housing may include a bearing formed on an actuator wall, the bearing preventing or limiting deformation of the in use drive shaft when journaled therewith.

Additionally or alternatively, a gear mechanism may be located in the actuator housing.

Furthermore, an end cap of the motor housing preferably includes an electronic-control-module cavity for receiving activation signals to control a motor within the motor

According to a second aspect of the invention, there is provided a vehicle-brake calliper comprising an EPB actuator unit, preferably in accordance with the first aspect of the invention but in any event having an integrated motor housing, on a calliper wall thereof.

According to a third aspect of the invention, there is provided a vehicle including a vehicle-brake calliper preferably in accordance with the second aspect of the invention. Beneficially, such a vehicle may include a said vehicle-brake calliper corresponding to each brake disc on the vehicle.

The invention will now be more particularly described, with reference to the accompanying drawings, in which:

Figure 1 is an exploded view of a first embodiment an EPB actuator unit, in accordance with the invention and shown in isolation of a vehicle brake calliper to which the actuator unit is typically directly or indirectly mounted;

Figure 2 shows a side sectional view of the assembled EPB actuator unit shown in Figure 1, with internal gear mechanism omitted for clarity and in accordance with the first aspect of the invention; and

Figure 3 is an exploded view of a second embodiment an EPB actuator unit, similar to Figure 1 and again in accordance with the invention.

Referring to Figures 1 and 2 of the drawings, there is shown a first embodiment of an EPB actuator unit 10, typically directly or indirectly mounted to a vehicle brake calliper and arranged to operate one or more pistons to move the brake pads at least towards a brake disc.

Each EPB actuator unit 10, preferably includes an actuator housing 12 and a motor housing 14 for an integrated, preferably DC, electric motor 16 provided thereon. The attachment of the motor housing 14 is by way of integral forming, such as through plastics moulding or casting, as one-piece with an actuator wall 18, in this case being a side wall, of the actuator housing 12. The motor housing 14 is preferably cylindrical either entirely or along at least a majority of its longitudinal extent. However, other cross-sectional shapes may be envisaged, such as oval or with opposing flats. A proximal end of the motor housing 14 relative to the actuator housing 12 is at least in part open to provide an aperture for receiving a drive shaft 20 therethrough. A distal end opposite the proximal end closes the motor housing 14, for example, by way of an end cap 22 which may conveniently include an electrical connector to provide electrical power to the rotor 24 via a brushless arrangement. A, typically magnetic, stator 26 is receivable, typically as a sliding push or press fit, within the motor housing 14 abutable with the actuator wall 18, and the rotor 24 is rotatably receivable therein. The stator 26 is preferably cylindrical, but may be other shapes to accommodate the shape of the motor housing. The drive shaft 20 is rotatable by the rotor 24 and extends through the actuator wall 18 into an interior of the actuator housing 12.

The drive shaft 20 may be supported at the actuator wall 18 by a bearing 28. Additionally or alternatively, a further bearing, which is not shown, may be provided, either by way of integral forming or by being separately attached, on a further actuator wall 30 opposing the first above-mentioned actuator wall 18. A projecting distal end of the drive shaft in this case is journaled with the further bearing. This is particularly beneficial due to the further bearing preventing or limiting deformation of the in use drive shaft when supported thereby. A gear 32 is preferably provided on the drive shaft 20, and a gear train or gear mechanism, which is not shown, is preferably provided in the actuator housing 12, being drivable by the drive-shaft gear 32. The actuator housing 12 is then closed by an end cap 36 which comprises a cover housing 40, although a cover plate may be utilised where necessary. The closure may be permanent, for example, by welding or bonding, or releasable, for example, by screw-threaded fasteners and/or clips. An output opening, which is not shown, may be typically provided as discussed above, for example, in the cover housing 40, to form a further bearing surface in which an end of the drive shaft 20 can be journaled.

An electronic control module 44 may be provided on or adjacent to the cover plate in a, preferably liquid tight, cavity defined by the cover plate and cover housing 40, allowing parking brake application signals to be received and consequently control signals to be outputted to energise and deenergise the electric motor 16.

Referring to Figure 3 of the drawings, there is shown a second embodiment of an EPB actuator unit. Like references with 100 added refer to the same or similar parts, and therefore further detailed description will be omitted for brevity.

As before, the EPB actuator unit 110 includes an actuator housing 112 and a motor housing 114 for an integrated, preferably DC, electric motor 116 provided thereon. The attachment of the motor housing 114 is by way of integral forming as one-piece with an actuator wall 118 of the actuator housing 112. A drive shaft 120 engaged to be rotated by a rotor 124 of the electric motor 116 is journaled through a, preferably integrated, bearing, not shown but similar to that of the first embodiment, formed at an opening in the actuator housing 112.

The motor arrangement of the first embodiment is brushless. However, in this embodiment a commutator 146 and associated brushes are provided as part of the electric motor.

It is thus possible to provide an EPB actuator unit which utilises a reduced amount of material and is more robust due to the integrally formed motor housing. This also therefore improves longevity and slightly decreases vibrational noise during operation. It is also advantageous to include the internal drive-shaft support bearing as part of the actuator unit, which may be at the actuator wall and/or spaced from the motor housing to support the distal end of the drive shaft. This prevents or limits bending torque stress associated with the operation of the DC motor being transmitted to the drive shaft, and thus potentially undesirable drive shaft deformation causing disengagement or slippage of the drive gear from the rest of the gear train within the actuator housing.

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.

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.

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

1. An EPB actuator unit comprising an actuator housing and a motor housing integrally formed as one-piece with an actuator wall of the actuator housing.

2. An EPB actuator unit as claimed in claim 1, wherein the motor housing includes a stator abutable with the actuator wall, and a rotor receivable therein, a drive shaft being rotatable by the rotor and which extends through the actuator wall into an interior of the actuator housing.

3. An EPB actuator unit as claimed in claim 1 or claim 2, wherein the actuator housing includes a bearing formed on an actuator wall, the bearing preventing or limiting deformation of the in use drive shaft when journaled therewith.

4. An EPB actuator unit as claimed in any one of claims 1 to 3, wherein a gear mechanism is located in the actuator housing.

5. An EPB actuator unit as claimed in any one of claims 1 to 4, wherein an end cap of the motor housing includes an electronic-control-module cavity for receiving activation signals to control a motor within the motor housing.

6. A EPB actuator unit substantially as hereinbefore described with reference to the accompanying drawings.

7. A vehicle-brake calliper comprising an EPB actuator unit as claimed in any one of the preceding claims on a calliper wall thereof.

8. A vehicle including a vehicle-brake calliper as claimed in claim 7.