Electric brake actuator

#The present invention relates to an electric brake actuator for actuating a brake arrangement. It will be convenient to describe the invention in relation to its application to the parking brake arrangement of a vehicle, although it is to be appreciated that the invention could have other applications, such as its actuating of brake arrangements in general.

#Electric brake actuators have been considered in recent times as being attractive for parking brake actuation, by facilitating removal of the need for manual parking brake actuation by the vehicle driver and by providing greater control of the braking force which is applied. As yet however, an electric parking brake actuator that is generally acceptable to the automotive industry has not been provided.

#It is an object of the present invention to provide an electric parking brake actuator for use in the automobile industry and which meets with general acceptance in that industry.

#The attached drawings show example embodiments of the invention of the foregoing kind. The particularity of those drawings and the associated description does not supersede the generality of the preceding broad description of the invention.

#FIG. 1 is schematic view of a vehicle cabin which includes an electric parking brake actuator according to the invention.

#FIG. 2 shows a load multiplier for use in an electric parking brake actuator according to the invention.

#FIG. 1 is a schematic view of the vehicle cabin 10 of a right hand drive automobile and shows the location of an electric parking brake actuator according to the invention. The vehicle cabin 10 includes a driver's seat 11, a centre console 12, a dash board 13 and a steering wheel 14. The electric parking brake actuator according to this embodiment of the invention includes an electric motor 15 which is mounted on or below the dash board 13, or the motor can be mounted below the seat 11 at 15′. In either case, a cable 16, 16′ extends between the motor 15, 15′ and a load multiplier 17, that is fixed to the undercarriage 18 of the automobile, outside the cabin 10.

#A pair of cables 19 extend from the load multiplier 17 to parking brake assemblies mounted to act on each of the rear wheels of the automobile. The load multiplier is effective to multiply the load applied to the cable 16, 16′ by an appropriate amount suitable to effectively actuate the parking brake assemblies. Thus, the cable 16, 16′ undergoes reduced loading compared to the cables 19 and can therefore be a light grade cable. Conversely, the cables 19 are of a heavier grade suitable for the greater load applied thereto through the load multiplier. Accordingly, the cable 16, 16′ has greater flexibility compared to the cables 19 and can be easily routed through the cabin 10 to position the motor 15, 15′ and the load multiplier 17 where desirable. As shown in FIG. 1, the load multiplier 17 is mounted toward the end of the drive shaft channel 20, whereby the cables 19 can each extend substantially directly to the parking brake assemblies (not shown).

#The electric parking brake actuator shown in FIG. 1 further includes facility for manual actuation of the parking brake assemblies as a safety feature should there be a failure that disables the electric operation of the actuator. Such failure could occur for example, in the electric motor 15, 15′, or the power supply, or in the actuator control system. As shown in FIG. 1, the electric motors 15, 15′ each include a rotatable wheel or handle 21, 21′ and while the mechanism is not apparent from FIG. 1, rotation of the wheel 21, 21′ is such as to pull on the cable 16, 16′ and manually actuate or release the parking brake assemblies. Conveniently, the wheel 21, 21′ is easily accessible to the driver who would manually engage and actuate the parking brake assemblies in the event of electric motor failure or power failure. It is preferred that the wheel 21, 21′ be moved into an actuating position only when needed, so that at other times, it is disengaged from operation. That is preferred, because otherwise the wheel 21, 21′ will rotate upon every actuation of the electric parking brake and the wheel would then be required to be carefully positioned, so as not to catch on anything within the cabin, such as driver clothing. Engagement of the wheel might be arranged simply by pushing it inwards against a biasing spring, that returns it to a disengaged position when released. A catch mechanism may be employed to maintain the wheel in the engaged position when necessary.