Spot caliper having an internal actuator brake

Abstract

A spot caliper comprising a motor gear unit, a rotary-to-linear actuator, and an internal actuator brake. The internal actuator brake comprises a clutch that selectively engages one or more linkages of the motor gear unit. The motor gear unit is seizable by the internal actuator brake after a park brake has been applied to prevent back-driving. The motor gear unit comprises one or more gear stages including at least a first stage gear and one or more planetary gear assemblies.

Description

SPOT CALIPER HAVING AN INTERNAL ACTUATOR BRAKECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 607,170 filed December 7, 2024, and incorporated herein by reference in its entirety for all purposes.FIELD

[0002] The present teachings relate to a spot brake having an internal actuator brake for preventing back- driving of a rotary -to -linear actuator.BACKGROUND

[0003] Vehicle brake systems include both service brake and park brake functions. These functions may be provided by various mechanisms. One option is to integrate both functions into one caliper. Typically, this involves a caliper that is both hydraulically and electromechanically actuated. Hydraulics are often relied upon for service braking and electromechanical mechanisms are often relied upon for park braking. Another option is to separate the service brake and park brake functions into structurally separate calipers, which are circumferentially displaced around and act upon the same rotor. With this configuration, a caliper providing park braking may be referred to as a spot caliper.

[0004] Spot calipers may be advantageous for packaging flexibility, decoupling service and park brake functions, common design solutions across a variety of vehicle platforms (e.g., sedans, trucks, etc.), simplified construction by the exclusion of hydraulic elements, use of a dedicated lubricant with wide operating temperature range (e.g., -40°C to 85°C) as opposed to brake fluid, and low drag torque after park brake release due to low piston slide force and controlled retraction.

[0005] Typically, spot calipers employ a lead screw and nut to translate rotational motion of the lead screw into linear motion of the nut, the linear motion moving brake pads relative to a rotor. Lead screws simplify caliper construction and protect against back-driving due to their low thread efficiency, perhaps as low as about 30 %, or even lower. However, the low efficiency also requires greater capabilities from the motor gear unit that drives the lead screw, such as more powerful and accordingly larger motors, larger gears, expensive materials, and expensive manufacturing processes. As a result, the packaging size of the spot caliper increases to accommodate these larger components. These challenges are realized to a greater extent in larger vehicles (e.g., trucks) due to greater torque demands for keeping these vehicles parked. In another aspect, the thread shape and lubrication method of the lead screw should be carefully selected and maintained in order to maintain the requisite efficiency to avoid back-driving.

[0006] It would be desirable to provide a brake system comprising structurally separate service and spot calipers.

[0007] It would be desirable to provide a spot caliper with a packaging size that is smaller relative to conventional spot calipers.

[0008] It would be desirable to provide a spot caliper with a high-efficiency rotary -to -linear actuator mechanism, relative to conventional lead screw and nut mechanisms, thus allowing for smaller dimensions of at least some motor gear unit components.

[0009] It would be desirable to provide a spot caliper that prevents or at least substantially mitigates back- driving.SUMMARY

[0010] The present application provides for a spot caliper that may solve at least some of the challenges described above.

[0011] The spot caliper may comprise a motor gear unit, a rotary -to-linear actuator, and an internal actuator brake. The internal actuator brake may comprise a clutch that selectively engages one or more linkages of the motor gear unit. The motor gear unit is seizable by the internal actuator brake after a park brake has been applied to prevent back -driving of the rotary -to-linear actuator. The motor gear unit may comprise one or more gear stages including at least a first stage gear and one or more planetary gear assemblies.

[0012] The internal actuator brake may be electron! agnetically actuated.

[0013] The internal actuator brake may comprise a coil to which power may be provided to move the clutch to disengage from the one or more linkages and to which power provision may be ceased to engage the clutch with the one or more linkages and seize the motor gear unit.

[0014] The rotary -to-linear actuator may be a ball-nut assembly comprising: a nut; a spindle; one or more balls interfaced between the nut and the spindle. The nut may be linearly translatable along the spindle via the one or more balls providing rolling friction to transfer rotational motion provided by the motor gear unit to linear motion of the nut.

[0015] The ball-nut assembly may have an efficiency of about 70% or more.

[0016] The spot caliper may be an electromechanical park brake.

[0017] The spot caliper may be free of a hydraulic mechanism.

[0018] The spot caliper may be a sliding caliper.

[0019] The one or more gear stages may be spur gears or helical gears.

[0020] The motor gear unit may further comprise a second stage gear. The one or more planetary gear assemblies may comprise at least two planetary gear assemblies. The at least two planetary gear assemblies may be in a stacked arrangement with rotational axes of sun gears thereof being coaxial.

[0021] The rotational axes of the first and second stage gears may be parallel. The rotational axis of the second stage gear may be coaxial with the rotational axes of the sun gears of the at least two planetary gear assemblies.

[0022] The motor gear assembly may comprise: a motor and an output shaft connected to and rotated by the motor. The clutch may comprise a spline connected to the output shaft via their mutual rigid connection to a pinion.

[0023] The first stage gear may be engaged with the pinion and one of the at least two planetary gear assemblies may be engaged with the rotary-to-linear actuator.

[0024] The motor gear unit may further comprise one or more idler gears.

[0025] The one or more idler gears may be disposed between the first stage gear and the second stage gear.

[0026] The motor gear unit may comprise a housing that includes a first chamber and a second chamber. The second chamber may include the internal actuator brake.

[0027] The first chamber may be separated from the second chamber by a support plate to substantially prevent fluid transfer therebetween.

[0028] The spline of the internal actuator brake may extend through the support plate.

[0029] The present application provides for a brake system that may solve at least some of the challenges described above.

[0030] The brake system may comprise the spot caliper described above and a service caliper. The spot caliper may function as a park brake and the service caliper may function as a service brake.

[0031] The spot caliper and the service caliper may act upon a common rotor and may be circumferentially offset from one another relative to the common rotor.BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG.l is a plan view of a service caliper and a spot caliper on a rotor.

[0033] FIG. 2A is a perspective view of a spot caliper according to the present teachings.

[0034] FIG. 2B is a sectional view of the spot caliper in FIG. 2A along view A-A.

[0035] FIG. 3 is a sectional view of a motor gear unit according to the present teachings.

[0036] FIG. 4 is a sectional view of a spot caliper according to the present teachings.DETAILED DESCRIPTION

[0037] The present application relates to an improved spot caliper. The spot caliper may function as a park brake, an emergency service brake, or both. Preferably, the spot caliper may function at least as a park brake. In this regard, the spot caliper may be activated by the vehicle operator once the vehicle is at rest and the spot caliper may function to maintain the vehicle at rest.

[0038] The spot caliper may be included in a brake system. The brake system may be a disc brake system including a rotor, where the spot caliper has brake pads located on opposing sides of the rotor and adapted and configured to selectively apply and release a frictional force upon the rotor. The opposing brake pads may clamp the rotor and apply a force thereupon in an apply operation. The opposing brake pads may maintain said force after the park brake has been applied. The opposing brake pads may release from the rotor and relieve said force in a release operation.

[0039] The brake system may further comprise a service caliper. The service caliper may be structurally discrete from the spot caliper. The service caliper may function as a service brake. The service caliper may be hydraulically actuated, electromechanically actuated, or both. Typically, the service brake may be at least hydraulically actuated. The service caliper may comprise brake pads located on opposing sides of the rotor and adapted and configured to selectively apply and release a frictional force upon the rotor. The spot caliper and the service caliper may be circumferentially offset from each other relative to the rotor.

[0040] The spot caliper may include an electromechanical mechanism. In this regard, power may be supplied to the spot caliper to move one or more mechanical parts. The spot caliper may be free of a hydraulic actuation system, including brake fluid, fluid channels, fluid reservoirs, and the like. The spot caliper may be exclusively actuated electromechanically. In this regard, the complexity of the spot caliper may be reduced by the elimination of hydraulic elements, making its manufacture and assembly upon the vehicle simpler.

[0041] The spot caliper may comprise a motor gear unit. The motor gear unit may function to generate torque, transfer torque to a rotary-to-linear actuator, modulate the speed output of a motor, modulate the torque output of a motor, or any combination thereof. The motor gear unit may comprise a motor and one or more linkages. The motor may function to generate torque. The one or more linkages may function to translate torque from the motor, ultimately to a rotary-to-linear actuator (e.g., a ball-nut assembly).

[0042] The one or more linkages may include gears, friction discs, pulleys, belts, chains, cables, shafts, or any combination thereof. The gears may include spur gears, helical gears, bevel gears, worm gears, rack and pinions, planetary gears, intermediate gears, idler gears, the like, or any combination thereof. The gears may include teeth that mesh with teeth of other gears to transmit torque. The one or more linkages may engage one another surface-to-surface via a frictional engagement to transmit torque. For example, friction discs may selectively engage one another to transmit torque, and separate to cause slippage between the friction discs to cease torque transmission.

[0043] It is contemplated that any linkages (e.g., gears) presented in the illustrated examples may be replaced with any other type of gear or linkage described herein. It is contemplated that any linkages (e.g., gears) presented in the illustrated examples may be rearranged. The orientation of the rotational axis of any linkage being replaced or rearranged may or may not be the same as the linkage it is being replaced with.One or more bearings and / or bushings may be provided at any interface where one or more gears are described as rotating about a shaft or axis.

[0044] The gear train of the motor gear unit may mechanically communicate with an internal actuator brake and a rotary-to-linear actuator (e.g., a ball-nut assembly). Mutual mechanical communication with these two elements may allow the internal actuator brake to seize motion of the motor gear unit such that torque is no longer transferred between the motor gear unit and the rotary-to-linear actuator. It is contemplated that the internal actuator brake may selectively engage with one or any combination of linkages in the motor gear unit.

[0045] In this regard, the internal actuator brake may function to control back driving or unintentional release of a braking force. Back-driving refers to an axial force of a linear motion element (e.g., a nut), in the rotary-to-linear actuator (e.g., ball-nut assembly), creating rotational motion of a rotating element (e.g., a spindle). This occurrence during a park brake apply or after a park brake apply may result in a loss of braking force. This can be dangerous, particularly when the braking force loss is great enough to allow the vehicle to move when it is not intended to.

[0046] The internal actuator brake may be advantageous in cooperation with a high-efficiency rotary-to- linear actuator mechanism such as a ball-nut assembly. In this regard, the higher efficiency of the ball-nut assembly (relative to, e.g., lead screws) can make it susceptible to back-driving, but said back-driving may be at least substantially prevented by the internal actuator brake. The efficiency of the ball-nut assembly may be about 70% or more, more preferably about 75% or more, more preferably about 80% or more, more preferably about 85% or more, or even more preferably about 90% or more. The ball-nut assembly may have a greater efficiency relative to lead screws due to the rolling friction of balls disposed between the spindle and nut in the ball-nut assembly.

[0047] The cooperation of the ball-nut assembly and the internal actuator brake may adapt and configure the spot caliper for fitting within a small packaging space. Due to the higher efficiency of ball-nut assemblies, at least relative to lead screws, there may be a lesser torque demand from the motor and thus smaller motors may be used. Moreover, smaller linkages in the motor gear unit may also be used.

[0048] In an apply operation, the motor may rotate in a first direction (e.g., clockwise or counterclockwise) and generate torque. The torque may be translated through the motor gear unit ultimately to a rotary-to-linear actuator mechanism to drive a piston. The piston may axially translate a brake pad to exert a force upon a rotor, and accordingly a commensurate force may be applied by the rotor upon the brake pad and piston.

[0049] After an apply operation, motor operation may be ceased and torque may be maintained such that the vehicle remains parked. Torque may be maintained by the internal actuator brake activating to seize themotor gear unit and substantially maintain an axial position of the piston. In this regard, the applied force would be maintained as the back -driving of the ball-nut assembly is prevented.

[0050] In a release operation, the internal actuator brake may be deactivated and the motor may rotate in a second direction (e.g., clockwise or counter-clockwise) to release the force of the piston upon the rotor.

[0051] The motor gear unit may comprise a shaft extending from the motor, which is rotated by the motor. The shaft may engage with one or more linkages. The shaft may engage with a pinion. The internal actuator brake may interact with a spline that may engage with the pinion. The shaft and spline may be rigidly engaged with the pinion, such as pressed into an interference fit. The pinion may mechanically communicate with one or more other linkages of the motor gear unit. The pinion may mechanically communicate with a first stage gear.

[0052] The internal actuator brake may be electromagnetically actuated. The internal actuator brake may be an electromagnetic friction clutch. The internal actuator brake may comprise a first friction plate and a second friction plate, which, when pressed together, seize the shaft of the motor, preventing its rotation in any direction. The first and second friction plates may be moved together and apart by selectively powering a coil. The internal actuator brake may comprise one or more springs. The one or more springs may function to exert a force on one of the friction plates in a direction of the other of the friction plates. Power to the coil may cause the first friction plate to separate from the second friction plate, allowing the shaft of the motor to rotate. Said separation may cause the first friction plate to compress a spring. Power to the coil may be ceased to allow the spring to engage the first friction plate with the second friction plate, and seize rotation of the shaft of the motor. The present teachings contemplate that any number of friction plates may be located between the first and second friction plates, and may engage together by moving the first friction plate toward the second friction plate.

[0053] It is contemplated that the internal actuator brake may include other types of mechanisms, including parking pawls, dog clutches, friction cones, cam and follower, or the like.

[0054] The present teachings contemplate that the internal actuator brake may engage with any other linkages of the motor gear unit, described below (e.g., a first, second, third, or fourth stage linkage). Such engagements may be via meshed or surface-to-surface frictional engagements. The present teachings also contemplate that it is possible for two or more internal actuator brakes to be included in the spot caliper, each of the two or more internal actuator brakes engaging with different linkages.

[0055] The motor gear unit may comprise a first stage linkage, such as a first stage gear. The first stage linkage may engage with the pinion. Such engagement may be a meshed engagement. The first stage gear may have a rotational axis that is parallel with the rotational axis of the pinion.

[0056] The motor gear unit may comprise a second stage linkage. The second stage linkage may be a second stage gear. The second stage gear may have a rotational axis that is parallel with the rotational axis of the first stage gear.

[0057] The motor gear unit may comprise one or more idler gears. The idler gear may function to change the direction of rotation of an output shaft (e.g., to a rotary -to -linear actuator) relative to an input shaft (e.g., from a motor), provide spacing between gears, or both.

[0058] The motor gear unit may comprise one or more planetary gear stages. The planetary gear stages may comprise two or more planetary gears, typically three or more planetary gears, and a sun gear. The sun gear may engage with the second stage linkage via a shaft. Where two or more planetary gear stages are present, they may engage with one another via a shaft. The one or more planetary gear stages and the second stage gear may have sun gears with rotational axes that are co-axial.

[0059] The motor gear unit may amplify the rotational torque of the motor, reduce the rotational speed at the rotary -to-linear actuator (e.g., at the spindle of a ball-nut assembly) relative to the motor, or both. Such amplification and reduction may be realized by one or more of the aforementioned linkages, such as illustrated herein. Preferably, the motor gear unit comprises at least a first gear stage and at least one planetary gear assembly. More preferably, the motor gear unit comprises first and second stage spur or helical gears and at least two planetary gear assemblies, which may be referred to, respectively as third and fourth stages.

[0060] It is contemplated, in general, that the planetary gears can provide a higher gear reduction ratio than a spur or helical gears, given the same package space, and withstand a higher level of stress. For at least this reason it is preferred they are used as stages proximate to the rotary-to-linear actuator. It is contemplated that using at least one (preferably two or more) planetary gear stages allows for a relatively large gear reduction ratio in a small package.

[0061] The configuration and selection of linkages in the motor gear unit may provide for a desirable gear reduction ratio while also providing for a small packaging space of the spot caliper, including the size and overall quantity of gears, as well as the size of the motor.

[0062] The motor gear unit may have a gear reduction ratio of about 100 or more, 150 or more, 200 or more, 250 or more, 300 or more, 350 or more, or even 400 or more. The motor gear unit may have a gear reduction ratio of about 800 or less, 750 or less, 700 or less, 650 or less, 600 or less, about 550 or less, about 500 or less, or even 450 or less. The gear reduction ratio may be defined by any range between any of the foregoing values.

[0063] The motor may have a motor torque constant of about 0.01 newton -meter per ampere (Nm / A) or more, 0.015 Nm / A or more, 0.02 Nm / A or more, or even 0.025 Nm / A or more. The motor may have a motortorque constant of about 0.1 Nm / A or less, 0.05 Nm / A or less, 0.04 Nm / A or less, or even 0.03 Nm / A or less. The motor torque constant may be defined by any range between any of the foregoing values.

[0064] The motor may have a motor resistance of about 0.2 Ohms or more, 0.25 Ohms or more, or even 0.3 Ohms or more. The motor may have a motor resistance of about 0.45 Ohms or less, 0.4 Ohms or less, or even 0.35 Ohms or less. The motor resistance may be defined by any range between any of the foregoing values.

[0065] The spot caliper may comprise a rotary-to-linear actuator. The rotary-to-linear actuator may function to translate rotational movement of the motor gear unit to linear movement of a piston. The rotary- to-linear actuator may be a ball-nut assembly. The ball-nut assembly may drive a piston to interact with a brake pad.

[0066] The ball-nut assembly may comprise a spindle, which rotates, and a nut, which moves axially along the spindle. The spindle may mechanically communicate with the motor gear unit. A plurality of balls may be located between the spindle and the nut. The plurality of balls may provide for a rolling frictional relationship of the spindle and the nut.

[0067] The nut may mechanically communicate with a piston. The piston may move axially within a channel formed in the spot caliper. The piston may engage with a brake pad, to move the brake pad axially relative to a rotor to create a braking force.

[0068] FIG. 1 shows the spot caliper 10, in cooperation with a service caliper 12, engaging a rotor 14. That is, the spot caliper 10, the service caliper 12, or both are manipulable to generate frictional forces upon the rotor 14. The frictional forces may ultimately cause a vehicle to slow down, come to a stop, maintain the vehicle in a stopped position, or any combination thereof. In some aspects, the service caliper 12 may function to cause the vehicle to slow down and come to a stop, and the spot caliper may function to maintain the vehicle in a stopped position.

[0069] The spot caliper 10 may be configured and adapted to perform a park brake function, as described herein, and the service caliper 12 may be configured and adapted to perform a service brake function, as described herein. The present teachings contemplate that some service brake function may be performed by the spot caliper 10 and some park brake function may be performed by the service caliper 12. Preferably, the service and park brake functions are performed separately by the service caliper 12 and the spot caliper 10, respectively.

[0070] FIG. 2A and FIG. 2B show a spot caliper 10. The spot caliper 10 comprises a motor gear unit 16 configured and adapted to apply and release engagement of the spot caliper 10 with the rotor 14. The spot caliper 10 is illustrated as a floating type caliper, although any other type of caliper is contemplated by the present teachings. In this regard, the spot caliper 10 comprises a support bracket 18 and a sliding body 24. The support bracket 18 may be fastened to a knuckle. The sliding body 24 slides relative to the supportbracket 18. The sliding body 24 has a bridge 26 extending over the support bracket 18. A finger 28 extends from an end of the bridge 26.

[0071] The spot caliper 10 has inner and outer brake pads 30, 30' that apply frictional forces upon the rotor 14, as discussed with respect to FIG. 1. The motor gear unit 16 drives a piston 32 to move the inner brake pad 30 in an apply direction, toward a first surface of the rotor 14. In reaction to engagement of the inner brake pad 30 and the rotor 14 and an increased force applied thereupon, the sliding body 24 slides relative to the support bracket 18, and moves the outer brake pad 30' in an apply direction, toward a second surface of the rotor 14 that is in opposing relationship to the first surface. In this regard, the finger 28 engages with the brake pad 30'.

[0072] Turning now to the driving mechanism of the spot caliper 10, FIG. 2B shows the internals of the motor gear unit 16 with the housing 34 thereof removed. A motor 36 drives a shaft (see FIG. 3), which mechanically communicates with an internal actuator brake 38 and a first stage gear 40.

[0073] FIG. 3 shows the motor 36 and shaft 41 driven thereby. The shaft 41 is engaged with a pinion 42, which mechanically influences the first stage gear 40. A spline 43 is also engaged with the pinion 41, the spline 43 extends to the internal actuator brake 38 and engages matching splines of the plates 44, 44'. Friction plates 44, 44' of the internal actuator brake 38 may be influenced toward each other to engage the friction plates 44, 44' and intermediate friction plates located therebetween to seize the shaft 41. That is, the frictional torque may be high enough such that the motor cannot spin to overcome this frictional torque. In this regard, the internal actuator brake 38 may function as an electromagnetic friction clutch, whereby power application to a coil causes or allows the friction plate 44 to move in a first direction and power cessation to the coil causes or allows the friction plate 44 to move in a second direction, the second direction being in opposition to the first direction. More specifically, power application to the coil causes the friction plate 44 to move away from the friction plate 44', thus compressing a spring 45. This allows the friction plates 44, 44' and the spline 43 to rotate freely relative to each other. When power application is ceased, the spring 45 presses the friction plates 44, 44' and intermediate friction plates therebetween together and seizes the shaft 41, preventing the shaft 41 from rotating in any direction.

[0074] Power supply to the internal actuator brake 38 may be ceased after the application of a park brake (e.g., by an action or an input of a vehicle operator). That is, after an initial operation of the motor 36 to engage brake pads with a rotor. In this regard, back -driving of the piston 32 may be prevented.

[0075] The present teachings contemplate that the internal actuator brake 38 may be located elsewhere and engage with any other element of the presently described system. For instance, the internal actuator brake 38 may engage with the first stage gear, second stage gear, first planetary gear stage, second planetary gear stage, etc., described below.

[0076] In some aspects, the internal actuator brake 38 may be located such that it can be isolated from other elements of the motor gear unit 16 such that grease, oil, or otherwise are substantially prevented from contacting the internal actuator brake 38. In this regard, the other elements of the motor gear unit 16, described below, are located in a first chamber 46 of the housing 34 and the internal actuator brake 38 is located in a second chamber 48 of the housing 34. The first and second chambers 46, 48 are separated by a support plate 50.

[0077] The motor gear unit 16 further includes a first stage gear 40, a second stage gear 52, a first planetary gear stage 54, and a second planetary gear stage 56. Torque is transferred therethrough, from the motor 36 ultimately to an output shaft 58. The gear reduction ratio may be about 450 to 500 (e.g., about 480).

[0078] FIG. 4 shows a ball nut assembly 60 comprising a spindle 62 that mechanically communicates with the motor gear unit 16. The spindle 62 rotates via input from an output shaft 58 of the motor gear unit 16. The ball nut assembly 60 includes a nut 64 that moves axially as the spindle 62 rotates. Disposed between the spindle 62 and the nut 64 are a plurality of balls 66 providing for a rolling frictional engagement of the same. The nut 64 engages with a piston 68 that moves axially and engages with an inner brake pad 30. As discussed hereinbefore, movement of the inner brake pad 30, via the piston 68, causes a commensurate axial displacement of the outer brake pad 30', which both cooperate to clamp upon a rotor (as shown in FIG. 1)

[0079] Various embodiments are disclosed herein. It is within the scope of this disclosure that the elements of the embodiments may be combined, duplicated, or separated into additional embodiments. Also, any element disclosed herein may be eliminated from any of the assemblies disclosed herein, duplicated, and / or combined with other elements.

[0080] The explanations and illustrations presented herein are intended to acquaint others skilled in the art with the invention, its principles, and its practical application. The above description is intended to be illustrative and not restrictive. Those skilled in the art may adapt and apply the invention in its numerous forms, as may be best suited to the requirements of a particular use. Accordingly, the specific embodiments of the present invention as set forth are not intended as being exhaustive or limiting of the teachings.

[0081] The scope of the teachings should, therefore, be determined not with reference to this description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The omission in the following claims of any aspect of subject matter that is disclosed herein is not a disclaimer of such subject matter, nor should it be regarded that the inventors did not consider such subject matter to be part of the disclosed inventive subject matter.

[0082] Plural elements or steps can be provided by a single integrated element or step. Alternatively, a single element or step might be divided into separate plural elements or steps.

[0083] The disclosure of "a" or "one" to describe an element or step is not intended to foreclose additional elements or steps. For example, disclosure of “a motor” does not limit the teachings to a single motor. Instead, for example, disclosure of “a motor” may include “one or more motors.”

[0084] While the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms may be used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings.

[0085] Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0086] The subject matter illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein.

[0087] Any of the elements, components, regions, layers, and / or sections disclosed herein are not necessarily limited to a single embodiment. Instead, any of the elements, components, regions, layers, and / or sections disclosed herein may be substituted, combined, and / or modified with any of the elements, components, regions, layers, and / or sections disclosed herein to form one or more embodiments that may not be specifically illustrated or described herein.

[0088] The disclosures of all articles and references, including patent applications and publications, testing specifications, are incorporated by reference for all purposes. Other combinations are also possible as will be gleaned from the following claims, which are also hereby incorporated by reference into this written description.REFERENCE NUMERALS

[0089] 10 Spot caliper

[0090] 12 Service caliper

[0091] 14 Rotor

[0092] 16 Motor gear unit

[0093] 18 Support bracket

[0094] 24 Sliding body

[0095] 26 Bridge

[0096] 28 Finger

[0097] 30 Inner brake pad

[0098] 30' Outer brake pad

[0099] 32 Piston

[0100] 34 Housing

[0101] 36 Motor

[0102] 38 Internal actuator brake

[0103] 40 First stage gear

[0104] 41 Shaft

[0105] 42 Pinion

[0106] 43 Spline

[0107] 44 Friction plate

[0108] 44' Friction plate

[0109] 45 Spring

[0110] 46 First chamber[OHl] 48 Second chamber

[0112] 50 Support plate

[0113] 52 Second stage gear

[0114] 54 First planetary gear stage

[0115] 56 Second planetary gear stage

[0116] 58 Output shaft

[0117] 60 Ball nut assembly

[0118] 62 Spindle

[0119] 64 Nut

[0120] 66 Balls

[0121] 68 Piston

Claims

CLAIMSWhat is claimed is:Claim 1 : A spot caliper comprising a motor gear unit, a rotary -to-linear actuator, and an internal actuator brake; wherein the internal actuator brake comprises a clutch that selectively engages one or more linkages of the motor gear unit; wherein the motor gear unit is seizable by the internal actuator brake after a park brake has been applied to prevent back-driving of the rotary -to-linear actuator; and wherein the motor gear unit comprises one or more gear stages including at least a first stage gear and one or more planetary gear assemblies.Claim 2: The spot caliper according to Claim 1, wherein the internal actuator brake is electromagnetically actuated.Claim 3 : The spot caliper according to Claim 1 or Claim 2, wherein the internal actuator brake comprises a coil to which power is provided to move the clutch to disengage from the one or more linkages and to which power provision is ceased to engage the clutch with the one or more linkages and seize the motor gear unit.Claim 4: The spot caliper according to any one of the preceding claims, wherein the rotary-to-linear actuator is a ball-nut assembly comprising: a nut; a spindle; and one or more balls interfaced between the nut and the spindle; and wherein the nut is linearly translatable along the spindle via the one or more balls providing rolling friction to transfer rotational motion provided by the motor gear unit to linear motion of the nut.Claim 5 : The spot caliper according to Claim 4, wherein the ball -nut assembly has an efficiency of about 70% or more.Claim 6: The spot caliper according to any one of the preceding claims, wherein the spot caliper is an electromechanical park brake.Claim 7: The spot caliper according to any one of the preceding claims, wherein the spot caliper is free of a hydraulic mechanism.Claim 8: The spot caliper according to any one of the preceding claims, wherein the spot caliper is a sliding caliper.Claim 9: The spot caliper according to any one of the preceding claims, wherein the one or more gear stages are spur gears or helical gears.Claim 10: The spot caliper according to Claim 9, wherein the motor gear unit further comprises a second stage gear; and wherein the one or more planetary gear assemblies comprises at least two planetary gear assemblies; and wherein the at least two planetary gear assemblies are in a stacked arrangement with rotational axes of sun gears thereof being coaxial.Claim 11 : The spot caliper according to Claim 10, wherein the rotational axes of the first and second stage gears are parallel, and wherein the rotational axis of the second stage gear is coaxial with the rotational axes of the sun gears of the at least two planetary gear assemblies.Claim 12: The spot caliper according to Claim 11, wherein the motor gear assembly comprises: a motor and an output shaft connected to and rotated by the motor; wherein the clutch comprises a spline connected to the output shaft via their mutual rigid connection to a pinion.Claim 13: The spot caliper according to Claim 12, wherein the first stage gear is engaged with the pinion and one of the at least two planetary gear assemblies engages with the rotary -to -linear actuator.Claim 14: The spot caliper according to any one of the preceding claims, wherein the motor gear unit further comprises one or more idler gears.Claim 15: The spot caliper according to Claim 14, wherein the one or more idler gears are disposed between the first stage gear and the second stage gear.Claim 16: The spot caliper according to any one of the preceding claims, wherein the motor gear unit comprises a housing that includes a first chamber and a second chamber; and wherein the second chamber includes the internal actuator brake.Claim 17: The spot caliper according to Claim 16, wherein the first chamber is separated from the second chamber by a support plate to substantially prevent fluid transfer therebetween.Claim 18: The spot caliper according to Claim 17, wherein the spline of the internal actuator brake extends through the support plate.Claim 19: A brake system comprising the spot caliper according to any one of the preceding claims, and further including a service caliper; wherein the spot caliper functions as a park brake and the service caliper functions as a service brake.Claim 20: The brake system according to Claim 19, wherein the spot caliper and the service caliper act upon a common rotor and are circumferentially offset from one another relative to the common rotor.

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