Brake system with a torque limiter assembly

Abstract

The braking system (10) sets a torque limit and includes a torque limiter assembly (48) associated with the electromechanical actuation system. The torque limiter assembly (48) includes a ring gear (62) that meshes with a planetary gear set (70), and the ring gear (62) includes a first race (86) that extends circumferentially thereof. The torque limiter assembly (48) includes a preload member having a second race (88) that extends circumferentially thereof. Balls or rollers (84) are engaged between the first race (86) and the second race (88). The first race (86) and / or the second race (88) includes a series of peaks and valleys and slopes extending therebetween. Below the torque limit, the balls or rollers (84) are engaged within the valleys, keeping the ring gear (62) rotatably captured and causing the planetary gear (70) set to orbit. Above the torque limit, the balls or rollers (84) slide over the peaks, rotating the ring gear (62) and keeping the planetary gear set (70) rotatably captured.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the priority of U.S. Patent Application No. 17 / 878,518, filed on August 1, 2022, the entire content of which is incorporated herein by reference.

[0002] This disclosure relates to a torque limiter assembly operable with a braking system. The torque limiter assembly is related to an electromechanical actuation system.

Background Art

[0003] A braking system typically operates by two or more pistons acting on brake pads to apply the brake pads to engage with a rotor or to disengage the brake pads from the engagement with the rotor. The pistons generally act simultaneously to apply symmetric pressure to the rotor. Depending on the situation, one piston may have to move a longer distance than another piston acting on the same brake pad. Thus, the torque applied to the pistons during the "apply" or "release" operation must be applied asymmetrically until symmetric pressure is applied to the brake pads. If symmetric pressure is not applied to the brake pads, insufficient braking force and non - uniform wear of the friction material of the brake pads can occur.

[0004] One solution to asymmetric piston movement is to use a limited - slip differential such as that described in U.S. Patent No. 9,879,739 (B2). This solution requires package space, complex metal parts, and precise manufacturing and assembly methods to operate reliably. Additionally, small variations in the slip torque between different pistons can generate excessive loads on one or more pistons.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] It is necessary to operate the piston assembly asymmetrically.

[0007] It is necessary to provide a mechanism for operating the piston assembly asymmetrically within a smaller packaging space compared to the packaging space of a limited slip differential system.

[0008] It is necessary to address the operation of the asymmetric piston assembly using a solution that requires fewer parts compared to the complexity of a limited slip differential system.

[0009] It is necessary to address the operation of the asymmetric piston assembly using a manufacturing and assembly method that is relatively less complex for a limited slip differential system.

Means for Solving the Problems

[0010] The present disclosure provides a braking system that can address at least some of the above - identified needs. The braking system can include an electromechanical actuation system. The electromechanical actuation system can include a first part and a second part. Each part can include a torque limiter assembly. The torque limiter assembly can set a torque limit.

[0011] Each torque limiter assembly may comprise a planetary gear set, a ring gear, a preload member, and balls or rollers. The planetary gear set may mesh with a sun gear. The ring gear may mesh with the planetary gear set. The ring gear may comprise a first race extending in its circumferential direction. The preload member may comprise a second race extending in its circumferential direction. The balls or rollers may be engaged between the first race and the second race.

[0012] The first race and / or the second race may comprise a series of peaks and valleys, and slopes extending therebetween.

[0013] Below the torque limit, the balls or rollers may be engaged within the valleys, keeping the ring gear rotatably captured and allowing the planetary gear set to orbit around the sun gear.

[0014] Above the torque limit, the balls or rollers may slide over the peaks, rotating the ring gear and allowing the planetary gear set to be rotatably captured.

[0015] The angle of the slope may at least partially determine the torque limit. The angle of the slope may be between about 5° and about 45°.

[0016] The angle of the slope for the balls or rollers to move in the release direction may be the same as or different from the angle of the slope for the balls or rollers to move in the applied direction.

[0017] The angle of the slope for the balls or rollers to move in the release direction may be about 2% to 25% greater than the angle of the slope for the balls or rollers to move in the applied direction.

[0018] The torque limiter assembly may comprise a spring. The spring may be substantially circumferentially aligned with the first and second races. The spring may apply a force to the preload member such that the balls or rollers are compressed between the preload member and the ring gear.

[0019] The height of the mountain measured from the valley can determine the torque limit. The height of the mountain can determine how much the spring is compressed.

[0020] The force applied to the preload member can at least partially determine the torque limit.

[0021] The mountains, valleys, and inclines can be defined by wavy surfaces, jagged surfaces, or both.

[0022] Each part of the electromechanical actuation system can include a first plate carrier and / or a second plate carrier. The first plate carrier can engage with the first side of the planetary gear set such that the orbit of the planetary gear set rotates the first plate carrier. The second plate carrier can engage with the second side of the planetary gear set such that the orbit of the planetary gear set rotates the first plate carrier. The second side can be on the opposite side of the first side.

[0023] The first or second plate carrier can include an output shaft that mechanically cooperates with the spindle. The spindle can cooperate with the nut as a ball screw mechanism or a conventional screw mechanism. The nut can engage with the piston.

[0024] The rotation of the spindle can ultimately axially translate the piston in the application direction and / or the release direction.

[0025] The torque limit of the first part can be different from the torque limit of the second part.

[0026] Both the first part and the second part of the electromechanical actuation system can be actuated by the same motor.

[0027] The braking system may comprise a caliper. The caliper may comprise an inner body portion and an outer body portion. A bridge may extend between the inner body portion and the outer body portion, and the bridge may comprise one or more fingers that act on a brake pad associated with the outer body portion.

[0028] The braking system may comprise two or more pistons that are located entirely on the inner body portion or the outer body portion, or that are located on both the inner body portion and the outer body portion. Each of the first and second portions of the electromechanical actuation system may be associated with a respective one of the two or more pistons.

[0029] Each portion of the electromechanical actuation system may act symmetrically on two or more pistons until a torque limit is achieved by the resistance to at least one of the pistons. At that point, the electromechanical actuation system may act asymmetrically on the two or more pistons due to the rotational freedom of the ring gear.

[0030] The present disclosure provides an electromechanical actuation system that can address at least some of the needs identified above. The electromechanical actuation system may be for a vehicle brake. The electromechanical actuation system may comprise a nut and a spindle. Rotation of the spindle may actuate the nut in an application direction and / or a release direction. The electromechanical actuation system may comprise a motor. The motor may communicate mechanically with the spindle.

[0031] The electromechanical actuation system may comprise a torque limiter assembly. The torque limiter assembly may be disposed mechanically downstream of the motor and mechanically upstream of the spindle. The torque limiter assembly may be set to a torque limit. Below the torque limit, rotational movement may be transmitted to the spindle. Above the torque limit, rotational movement may not be transmitted to the spindle.

[0032] The torque limiter assembly can be a ball detent type torque limiter.

[0033] The torque limiter assembly can include a planetary gear set, a sun gear, and a ring gear. The planetary gear set can mesh with both the sun gear and the ring gear. Below the torque limit, the ring gear can remain rotatably captured, and the planetary gear set can orbit around the sun gear. Above the torque limit, the ring gear can rotate, and the planetary gear set can remain capturable in an orbiting manner.

[0034] The ring gear can include a race having a series of ridges and valleys and slopes extending therebetween. The electromechanical actuation system can include a ball or roller that engages with the race. Below the torque limit, the ball or roller can engage within the valley. Above the torque limit, the ball or roller can slide over the ridge.

[0035] The electromechanical actuation system can include two or more parts. Each part can be associated with a separate piston for engaging a brake pad. Each part can include a torque limiter assembly.

Brief Description of the Drawings

[0036]

Figure 1A

Figure 1B

Figure 1C

Figure 2A

Figure 2B

Figure 3A

Figure 3B

Figure 3C

DETAILED DESCRIPTION OF THE INVENTION

[0037] The present disclosure provides a torque limiter assembly operable with a braking system. The torque limiter assembly may be associated with an electromechanical actuation system. That is, the torque limiter assembly may be integrated into a mechanical drive mechanism of the electromechanical actuation system.

[0038] The braking system may include an electromechanical actuation system. The electromechanical actuation system may ultimately use a motor to move one or more pistons in an application direction and / or a release direction.

[0039] The electromechanical actuation system may be associated with a service brake operation and / or a parking brake operation. Preferably, the electromechanical actuation system may be associated with a parking brake operation.

[0040] The electromechanical actuation system may include one or more torque limiter assemblies. The torque limiter assembly may be provided mechanically downstream of the motor and mechanically upstream of the piston.

[0041] One torque limiter assembly may be provided for each piston, but the present disclosure anticipates that one torque limiter assembly may be associated with a plurality of pistons.

[0042] The braking system may include a hydraulic actuation system. The hydraulic actuation system may include a fluid that applies pressure to one or more pistons. The fluid may be disposed within a cylinder in which the piston is housed.

[0043] The hydraulic actuation system may be related to the service brake operation and / or the parking brake operation. Preferably, the hydraulic actuation system may be related to the service brake operation.

[0044] The electromechanical actuation system and the hydraulic actuation system may act to move the piston individually and / or in cooperation during the application operation and / or the release operation. During the application operation, the piston may be moved towards the rotor, and thus may affect the movement of one or more brake pads towards the rotor and / or into engagement with the rotor. During the release operation, the piston may be moved away from the rotor, and thus may affect the movement of one or more brake pads away from the rotor and / or out of engagement with the rotor.

[0045] The brake system may include a caliper. The caliper may house at least a portion of the electromechanical actuator system and / or the hydraulic actuator system, provide a mounting location for the brake pads, position the brake pads relative to the rotor, or any combination thereof. In this regard, the caliper may have an inner body portion and an outer body portion. The inner body portion may be located closer to the inside of the rotor. The outer body portion may be located closer to the outside of the rotor.

[0046] The caliper may be a floating caliper. That is, the caliper may be structurally separate from the electromechanical and / or hydraulic actuation system. The electromechanical and / or hydraulic actuation system may be fixed to the caliper. While being fixed, the electromechanical and / or hydraulic actuation system may be able to slide relative to the caliper.

[0047] The caliper may be a fixed caliper. That is, the caliper may be structurally integrated with an electromechanical and / or hydraulic actuation system. The electromechanical and / or hydraulic actuation system may remain fixed relative to the caliper.

[0048] The caliper may include both a floating part and a fixed part.

[0049] The braking system may include one or more brake pads. The brake pads may be configured to engage the rotor by friction. The brake pads may engage the rotor and decelerate and / or stop the rotor and / or the vehicle in which the rotor is used. That is, the rotational movement of the rotor may be decelerated and / or stopped, and the linear movement of the vehicle may be decelerated and / or stopped.

[0050] The brake pads may be fixed to the caliper with a clip or the like. The brake pads may engage one or more pistons and thereby be moved. Preferably, opposite ends of the brake pads may be symmetrically acted upon by the pistons. With respect to this, the entire surface area of the friction material on the brake pads, or at least a substantial portion of the surface area, is configured to engage the rotor. Thus, non-uniform wear of the brake pads may be avoided or at least mitigated, and the full intended braking load is achieved.

[0051] A pair of brake pads may be used. The brake pads may include an inner brake pad positioned on the inner body portion of the caliper and an outer brake pad positioned on the outer body portion of the caliper. The inner and outer brake pads may be able to clamp the rotor.

[0052] The caliper may include one or more cylinders. The cylinder may function to store a piston, fluid of a hydraulic actuation system, components of an electromechanical actuation system, or any combination thereof. The cylinder may be formed within the caliper by casting, machining, or both.

[0053] The brake system may include one or more pistons. The piston may function to cooperate with a hydraulic actuation system and / or an electromechanical actuation system to engage a brake pad and apply a load to the brake pad. One or more components (such as nuts and spindles) of the electromechanical actuation system, and / or the fluid located within the cylinder, can move the piston within the cylinder.

[0054] The piston may be located within the cylinder. The piston can move within the cylinder. The piston may include a portion that extends outside the cylinder. The portion that extends outside the cylinder can engage the brake pad.

[0055] One or more cylinders and associated pistons may be located in or near the inner body portion. These may be referred to herein as inner cylinders and inner pistons. One or more cylinders and associated pistons may be located in or near the outer body portion. These may be referred to herein as outer cylinders and outer pistons. One or more cylinders and associated pistons may be located in or near both the inner body portion and the outer body portion. Preferably, the cylinders and associated pistons are located in or near at least the inner body portion.

[0056] The inner cylinders and associated pistons can be coaxial with the outer cylinders and associated pistons. In this regard, the clamping forces applied by the opposing inner and outer pistons are coaxial. Such a pair of coaxial inner and outer cylinders and associated pistons may be referred to herein as a corresponding pair.

[0057] The brake system may not have one or more corresponding pairs of cylinders and associated pistons. By way of example, the brake system may include only the inner cylinders and associated pistons. As another example, a corresponding pair of cylinders and associated pistons may be located in or near a first portion of the caliper, and only one inner cylinder and associated piston may be located in or near a second portion of the caliper. Other configurations are contemplated by the present teachings.

[0058] If a portion of the caliper does not have a corresponding pair of cylinders and associated pistons, the brake system may include a bridge portion. The bridge portion may function to transmit a load from the inner side to the outer side of the brake system. The bridge portion may extend across the inner and outer body portions of the caliper.

[0059] A first end of the bridge portion may be coupled to the main body portion of the brake system or to other components coupled to the main body portion. The main body portion may be slidably coupled to the caliper. A second end of the bridge portion may include one or more fingers. The fingers may function to engage the brake pads. The fingers may extend at an angle (e.g., about 90 degrees) from the bridge.

[0060] In the inching operation, a load can be applied to the piston by either or both of an electromechanical actuation system and a hydraulic actuation system. Accordingly, the piston can be made to press a first brake pad against the rotor. Then, in response to this load, the bridge portion and the fingers can be shifted axially inward, and the fingers can press a second brake pad against the rotor. The first brake pad can be the inner brake pad, and the second brake pad can be the outer brake pad, or vice versa. In this regard, a load is applied to both sides of the rotor (i.e., a clamping action) to decelerate and / or stop the rotor and / or the vehicle.

[0061] The electromechanical actuator system can include a motor gear unit. The motor gear unit can function to move the piston in the application direction and / or the release direction. For this purpose, the motor gear unit can include an electrically driven motor and one or more link mechanisms between the motor and one or more pistons, whereby the motor drives one or more link mechanisms, and as a result, one or more pistons move.

[0062] The motor gear unit can include a motor, one or more torque limiter assemblies, or both.

[0063] The motor gear unit can include a motor gear unit housing. The motor gear unit housing can function to protect the internal mechanism of the motor gear unit. The motor gear unit housing can accommodate the motor, one or more torque limiter assemblies, or both. The motor gear unit housing may be provided as one or more components located around the motor gear unit.

[0064] The motor gear unit may include a motor. The motor may function to actuate the piston in the applied direction (i.e., toward the rotor) and / or in the release direction (i.e., away from the rotor). Non-limiting examples of suitable motors may include servo motors and stepper motors.

[0065] The motor gear unit may include a motor drive shaft. The motor drive shaft may be coupled to the motor. The motor drive shaft may extend a distance from the motor. The motor drive shaft may include a motor drive gear disposed along its length.

[0066] The motor gear unit may include one or more motor drive gears. The motor drive gears can function to transmit the torque generated by the motor and applied to the motor drive shaft to the torque limiter assembly. The motor drive gears can mesh with one or more torque limiter drive gears of one or more torque limiter assemblies. Non-limiting examples of suitable motor drive gears may include spur gears and helical gears.

[0067] One or more other link mechanisms may be disposed between the motor drive gears and the one or more torque limiter assemblies. The one or more other link mechanisms can include one or more gears, shafts, chains, belts, etc., or any combination thereof. The physical dimensions and / or arrangement of the one or more other link mechanisms can be selected to correspond to the packaging space of the brake system. By way of example, one or more gears may be disposed between the motor drive gears and the one or more torque limiter assemblies to package the motor on top of the main body portion and / or the inner body portion of the caliper while maintaining appropriate clearance therefrom and / or from the one or more torque limiter assemblies. The present teachings envision any other suitable configuration of link mechanisms that can mechanically connect the motor to the one or more torque limiter assemblies.

[0068] A helical gear and a pinion gear can be arranged between the motor-driven gear and one or more torque limiter assemblies. The helical gear and the pinion gear can share the same shaft. The helical gear and the pinion gear can rotate together. The helical gear can mesh with the motor-driven gear. The pinion can mesh with one or more torque limiter assemblies. The pinion can be a spur gear.

[0069] The electromechanical actuator system can include a spindle. The spindle is in mechanical communication with the torque limiter assembly and can function to axially translate the nut in the application direction and / or the release direction, or both. The spindle can have threads on its outer peripheral surface. The threads can be sized to receive balls or rollers.

[0070] The electromechanical actuator system can include a nut. The nut moves axially along the length of the spindle, engages a piston, and can function to move the piston in the application direction and / or the release direction, or any combination thereof. The nut can have threads on its inner peripheral surface. The threads can be sized to receive balls or rollers.

[0071] The nut can be disposed on the spindle. A plurality of balls or rollers and / or one or more springs can be disposed within the threads of both the spindle and the nut. The balls or rollers can provide a low-friction engagement between the nut and the spindle relative to their direct screwing engagement to assist in the movement of the nut in the application direction and / or the release direction.

[0072] The aforementioned nut and spindle can cooperate as a ball screw mechanism. However, the present teachings anticipate that other spindle and nut configurations, as well as other piston actuation mechanisms, may be used with the braking system. For example, the nut and spindle can cooperate as a conventional screw mechanism. In a conventional screw mechanism (i.e., a mechanism of a lead screw and a nut).

[0073] The electromechanical actuator system can include one or more torque limiter assemblies. The torque limiter assemblies can function to asymmetrically actuate different pistons. The torque limiter assemblies can be ball detent type torque limiters.

[0074] The electromechanical actuator system can include one or more portions. Each portion can actuate an individual piston. Preferably, two portions can be used to actuate pistons that engage two portions of a brake pad, but the present disclosure anticipates using fewer or more portions. Each portion can include a torque limiter assembly. A single torque limiter assembly can be associated with two or more portions, and thus two or more pistons.

[0075] Each portion can be actuated by the same motor or different motors. Preferably, each portion can be actuated by the same motor.

[0076] The torque limiter assembly can be set to a torque limit. The torque limit can be adjustable. Below the torque limit, a ring gear as described herein can remain rotatably captured, and a planetary gear can orbit around a sun gear. Above the torque limit, the ring gear can rotate and the planetary gear can remain captured rotatably relative to the sun gear. The ring gear can be rotated by balls or rollers that slide over teeth within a race of the ring gear and / or a preloading member. The ring gear can rotate relative to the preloading member.

[0077] When one or more parts of the electromechanical actuation system achieve a torque limit, the torque limiter can slip. In such a case, one or more other parts of the electromechanical actuation system can continue to operate the spindle until the torque limit is achieved. Thus, any axial position misalignment between the pistons of each part of the electromechanical actuation system can be eliminated, and the respective loads applied to different parts of the brake pads can be made substantially uniform.

[0078] If one or more pistons meet the torque limit by their engagement with one or more brake pads, the one or more pistons can stop moving (e.g., in the applied direction), and one or more other pistons can continue to move (e.g., in the applied direction) until each of the one or more other pistons meets the torque limit.

[0079] The applied operation of the piston can be held for a period of time. For example, the parking brake may be applied while the vehicle remains unoccupied. When the electromechanical actuation system operates in the applied direction, the motor can operate until a predetermined load applied to one or more brake pads is met. Then, the motor can stop operating, and the load can be held until the electromechanical actuation system is disengaged and one or more pistons are moved in the release direction. The torque limit may be applied in the release direction while the load is held for a period of time.

[0080] The torque limit in the applied direction and / or the release direction can be between about 5 Nm and 30 Nm, more preferably between about 10 Nm and 25 Nm, or even more preferably between about 15 Nm and 20 Nm.

[0081] The torque limit of one or more parts of the electromechanical actuation system may be the same as or different from the torque limit of one or more other parts of the electromechanical actuation system.

[0082] As described herein, the ring gear and / or preload member may comprise a serrated face and / or a corrugated face having a series of peaks and valleys, and balls or rollers located within one or more races between the ring gear and the preload member. Below the torque limit, the balls or rollers may engage within the valleys of the serrated face and / or the corrugated face. Above the torque limit, the balls or rollers slide over the peaks of the serrated face and / or the corrugated face.

[0083] Each part of the electromechanical actuation system may act symmetrically on one or more pistons until the torque limit is achieved by resistance to at least one of the pistons. At that point, the electromechanical actuation system may act asymmetrically on one or more pistons due to the rotational freedom of the ring gear.

[0084] The torque limiter assembly may comprise a torque limiter drive shaft and a torque limiter drive gear. The torque limiter drive shaft may function to transmit torque to the planetary gear set via the sun gear. The torque limiter drive gear may function to receive torque from the motor drive shaft and / or one or more gears of one or more other linkage mechanisms. The torque limiter drive gear may be fixed to the torque limiter drive shaft (e.g., via a keyway). The torque limiter drive shaft may be integrally formed with the torque limiter drive shaft (e.g., by casting a splined drive shaft).

[0085] The torque limiter drive shaft may include a sun gear. The sun gear may function to transmit torque from the torque limiter drive shaft to the planetary gear set. The sun gear may be mechanically disposed downstream of the torque limiter drive gear. The sun gear may be fixed to the torque limiter drive shaft (e.g., via a keyway). The sun gear may be integrally formed with the torque limiter drive shaft (e.g., by casting a splined drive shaft). The sun gear may be a spur gear. The sun gear may be capable of meshing with the planetary gear set.

[0086] The torque limiter assembly may include a planetary gear set. The planetary gears may function to selectively transmit torque from the torque limiter drive shaft to the output shaft. The planetary gears may be capable of orbiting around the sun gear. The planetary gears may be capable of meshing with the sun gear and / or the ring gear. The planetary gears may be spur gears.

[0087] The torque limiter assembly may include a first plate carrier and / or a second plate carrier. The first and / or second plate carrier may function to convert the orbital motion of the planetary gears into torque applied to the output shaft. The first plate carrier may be coupled to the second plate carrier. The planetary gears may be fixed between the first plate carrier and the second plate carrier. The first plate carrier may be disposed on a first side of the planetary gears, and the second plate carrier may be disposed on a second, opposite side of the planetary gears.

[0088] The first plate carrier and / or the second plate carrier may include one or more shafts. The planetary gears may be positioned on the shafts. The shafts may be circumferentially distributed around the first and / or second plate carrier. The planetary gears may be capable of rotating on the shafts.

[0089] One or more bushings may be positioned on the shaft between the shaft and the planetary gear. The bushing can assist in the rotation of the planetary gear. The bushing can provide a surface with less friction against the direct interface between the planetary gear and the shaft.

[0090] The first plate carrier or the second plate carrier may include an output shaft. The output shaft may be actuated by the orbital motion of the planetary gear set. The output shaft may be coupled to the spindle. The output shaft may be splined, the spindle may include a groove for receiving the spline, or vice versa.

[0091] The torque limiter assembly may include a ring gear. The ring gear may function to selectively rotate such that the orbit of the planetary gear may be provided or impeded. The ring gear may be an internal gear. The ring gear can mesh with the planetary gear set.

[0092] When the ring gear is rotatably captured, the planetary gear can orbit around the sun gear. When the ring gear is rotatably free, the torque applied to the planetary gear by the sun gear can be transmitted to the ring gear and the planetary gear can be rotatably captured. Thus, the torque limit can be met when the ring gear transitions from being rotatably captured to rotatably free.

[0093] The ring gear can be rotatably captured when a ball or roller engages within the valleys of the ring gear's race. The ring gear can be rotatably free when the ball or roller slides over the peaks of the ring gear's race.

[0094] The torque limiter assembly may include a preload member. The preload member may function to apply a predetermined force to the ball or roller, hold the ball or roller between the preload member and the ring gear, or both.

[0095] The preload member may include a groove. The groove may function to receive a portion of the spring. The groove can be located at the first end of the preload member opposite the second end, and the second end includes a race and is near the ring gear.

[0096] The torque limiter assembly may include a spring. The spring may function to apply a force to the preload member in the direction of the ball or roller and / or the ring gear. The spring may be circumferentially aligned with the first race of the ring gear and the second race of the preload member. The spring may have a first end engaging the preload member and a second end engaging the spring retainer.

[0097] The force applied to the preload member can determine the torque limit. The force can be adjusted by selecting springs with different spring constants, (e.g., by changing the distance between the preload member and the spring retainer) changing the preload of the spring, or both. The preload of the spring can be constant or adjustable. The preload of the spring may be actively adjusted.

[0098] The spring can be a coil spring, washer spring, spring stack, elastic element, etc., or any combination thereof.

[0099] The torque limiter assembly may include a spring retainer. The spring retaining member may function to preload the spring. The spring retainer may be a snap ring. The snap ring can engage the inner surface of the motor gear unit housing. For example, the snap ring can fit into a groove formed on the inner surface of the motor gear unit housing. The spring retainer may be integrally formed with the motor gear unit housing by molding, casting, machining, or any combination thereof.

[0100] The ring gear may include a first race. The first race may function to receive a ball or roller, set the torque limit, or both. The first race can extend circumferentially around the ring gear.

[0101] The preload member may comprise a second race. The second race may function to receive balls or rollers, set a torque limit, or both. The second race may extend circumferentially around the preload member.

[0102] The torque limiter assembly may comprise one or more balls or rollers. The balls or rollers may function to selectively engage a ring gear. At least a portion of the balls or rollers may be located within the first race and / or the second race. The balls or rollers may be disposed between the first race of the ring gear and the second race of the preload member.

[0103] The first race and / or the second race may comprise undulating surfaces and / or serrated surfaces. The undulating surfaces and serrated surfaces may comprise peaks and valleys. The balls or rollers may be captured within the valleys until the torque limit is achieved. When the torque limit is achieved or exceeded, the balls or rollers may be able to slide over the peaks.

[0104] The height of the peak measured from the valley can determine the torque limit. The balls or rollers may be able to move up the incline by the height before reaching the peak and sliding into the next valley. When the balls or rollers cross this height, the spring may be compressed.

[0105] The incline may extend between the peak and the valley. The incline may be defined by an angle and / or a curvature. A first portion of the incline may be defined by an angle and a second portion of the incline may be defined by a curvature.

[0106] The angle of inclination can determine the torque limit. The angle of inclination can be between about 5° and about 45°, more preferably between about 10° and about 45°, more preferably between about 15° and about 40°, or even more preferably between 20° and about 35°. Different portions of the inclination directed in the same direction (i.e., the application direction or the release direction) can be defined by different angles or the same angle. One or more inclinations directed in the same rotational direction can be defined by different angles or the same angle. The rotational direction referred to herein with respect to the race can mean the clockwise or counterclockwise direction in which the ball or roller moves relative to the race. The application operation can include a clockwise rotation, the release operation can include a counterclockwise rotation, or vice versa.

[0107] The curvature of the inclination can determine the torque limit. One or more inclinations directed in the same rotational direction can be defined by different curvatures or the same curvature.

[0108] The angle and / or curvature of the inclination in which the ball or roller moves in the release direction may be the same as the angle and / or curvature of the inclination in which the ball or roller moves in the application direction. In this regard, the torque limit in the release direction may be equal to the torque limit in the application direction.

[0109] The angle and / or curvature of the inclination in which the ball or roller moves in the release direction may be different from the angle and / or curvature of the inclination in which the ball or roller moves in the application direction. In this regard, the torque limit in the release direction may be greater than the torque limit in the application direction.

[0110] The angle of inclination and / or curvature for the ball or roller to move in the release direction may be about 2% or more, more preferably about 5% or more, or even more preferably about 10% or more greater than the angle of inclination and / or curvature for the ball or roller to move in the application direction. The angle of inclination and / or curvature for the ball or roller to move in the release direction may be about 25% or less, more preferably about 20% or less, or even more preferably about 15% or less greater than the angle of inclination and / or curvature for the ball or roller to move in the application direction.

[0111] Figures 1A - 1C show the brake system 10. The brake system 10 includes a caliper 12 that includes an inner body portion 14 and an outer body portion 16. Extending across the caliper 12 is a bridge portion 18 that extends from a main body portion 20. Extending from the bridge portion 18 are three fingers 22 that are located immediately adjacent to the outer body portion 16, although any number of fingers 22 are contemplated by the present teachings. Preferably, at least two fingers 22 are used such that two opposing ends of the brake pad are acted upon. The brake system 10 includes a pair of brake pads 24 that includes an inner brake pad 26 and an outer brake pad 28. The inner body portion 14 and the inner brake pad 26 are located closer to the inside of the rotor. The outer body portion 16 and the outer brake pad 28 are located closer to the outside of the rotor. Although a floating caliper design is shown, the present teachings may also apply to a fixed caliper design.

[0112] As shown in FIG. 1C, the braking system 10 includes two cylinders 30 defined within a main body portion 20, and associated pistons 32 are positioned therein and extend therefrom. The pistons 32 move within the cylinders 30 in an application direction and a release direction. The pistons 32 act on an inner brake pad 26. The present teachings anticipate that one or more cylinders 30 and associated pistons 32 can be positioned immediately adjacent to either or both of the inner body portion 14 and the outer body portion 16. By the actuation of the pistons 32 with respect to the inner brake pad 26, fingers 22 act on an outer brake pad 28. This is made possible by the main body portion 20, and an attached bridge portion 18 is slidably secured to the caliper 12, resulting in movement of the bridge portion 18 with respect to the caliper 12. Specifically, in the application operation, a load is applied to the pistons 32 by either or both of an electromechanical actuation system 34 and a hydraulic actuation system. Accordingly, the pistons 32 are caused to exert a load on the inner brake pad 26, and the inner brake pad 26 exerts a load on the rotor. Then, in response to the load exerted by the pistons 32, the bridge portion 18 and the fingers 22 are shifted axially inwardly with respect to the caliper 12, whereby the fingers 22 press the outer brake pad 28 against the rotor. Accordingly, loads are applied to opposite sides of the rotor to cause braking.

[0113] The braking system 10 of the present disclosure includes at least an electromechanical actuation system 34 and, optionally, a hydraulic actuation system. The torque limiter assembly of the present disclosure is associated with the electromechanical actuation system 34. The electromechanical actuation system 34 and / or the hydraulic actuation system act on the piston 32 to move the piston 32 within the cylinder 30. Specifically, the electromechanical actuation system 34 rotates the spindle 36 while keeping it axially trapped and axially moves the nut 38 toward and away from the inner brake pad 26, and the nut 38 engages the piston 32 to cause the movement of the piston 32. The hydraulic actuation system applies and releases hydraulic pressure to the piston 32 with respect to the fluid 40 present within the cylinder 30. The electromechanical actuation system 34 and the hydraulic actuation system can act individually and / or cooperate with each other during the application operation and the release operation. Typically, the electromechanical actuation system 34 operates the parking brake and the hydraulic actuation system operates the service brake, although other configurations are contemplated by the present disclosure.

[0114] The electromechanical actuation system 34 includes a motor gear unit 42, and the motor gear unit 42 is coupled to the main body portion 20 of the braking system 10. The motor gear unit 42 includes a motor gear unit housing 44 that covers and protects the internal mechanism of the motor gear unit 42.

[0115] Figures 2A and 2B show the motor gear unit 42 with the motor gear unit housing 44 removed as shown in FIGS. 1A - 1C. The motor gear unit 42 includes a motor 46 and two torque limiter assemblies 48. One torque limiter assembly 48 or three or more torque limiter assemblies 48 are also contemplated by the present teachings. Generally, one torque limiter assembly 48 is associated with each individual piston 32. The motor 46 includes a motor drive shaft 50 that includes a motor drive gear 52, and the motor drive gear 52 acts on a helical gear 54 that shares a common shaft with a pinion gear 56. Torque is transmitted from the motor drive shaft 50 to the torque limiter assembly 48 via the motor drive gear 52, the helical gear 54, and the pinion gear 56. The present disclosure contemplates that any number of link mechanisms (e.g., gears) may be used between the motor drive shaft 50 and the torque limiter assembly 48. By way of example, the motor drive shaft 50 may be splined and engage directly with the torque limiter assembly 48. The quantity and arrangement of the link mechanisms may be guided by the desired packaging space for the components of the brake system 10. As shown in FIGS. 2A and 2B, the helical gear and pinion gear 56 result in the motor 46 being packaged above the cylinder 30 shown in FIG. 1C.

[0116] Figure 2B provides an alternative view of the motor gear unit 42 shown in Figure 2A. Each torque limiter assembly 48 includes a torque limiter drive gear 58 coupled to a torque limiter drive shaft 60. Each torque limiter assembly 48 includes a ring gear 62 that cooperates with a planetary gear 70 driven by a sun gear 72 shown in Figure 3A, and the sun gear 72 is associated with the torque limiter drive shaft 60. The ring gear 62 engages a ball 84 shown in Figure 3A and is sandwiched between the ring gear 62 and a first side of a preload member 64. The preload member 64 is radially fixed within the motor gear unit housing 44 shown in Figure 1C. A spring 66 engages the preload member 64 on its corresponding second side. The spring 66 is held in engagement with the preload member 64 by a spring retainer 68. The spring retainer 68 is coupled to and extends from the inner surface of the motor gear unit housing 44 shown in Figures 1A - 1C to provide a surface for the spring 66 to engage.

[0117] Figure 3A shows the torque limiter assembly 48. The torque limiter assembly 48 includes a ring gear 62 that cooperates with three planetary gears 70 driven by a sun gear 72. The sun gear 72 is in the form of a spline with respect to the torque limiter drive shaft 60. The sun gear 72 may be integrally formed with (e.g., by casting and / or machining) or fixed thereto (e.g., by key engagement) the torque limiter drive shaft 60. The sun gear 72 actuates the planetary gears 70 with respect to the ring gear 62. Although three planetary gears 70 are shown, the present teachings anticipate a lesser or greater amount of planetary gears 70.

[0118] The planetary gears 70 are fixed between a first plate carrier 74 and a second plate carrier 76. The first plate carrier 74 includes three shafts 78 extending therefrom, and the shafts 78 include bushings 80 to facilitate rotation of the planetary gears 70. The present teachings anticipate that the shafts 78 may extend from either or both of the first plate carrier 74 and the second plate carrier 76. The second plate carrier 76 includes an output shaft 82.

[0119] The ring gear 62 engages with balls 84 sandwiched between the ring gear 62 and the first side of the preloading member 64. The spring 66 engages with the preloading member 64 on its opposite second side. The spring 66 is held in engagement with the preloading member 64 by a spring retainer 68. The spring retainer 68 is located in the immediate vicinity of the torque limiter drive gear 58.

[0120] The ring gear 62 includes a first race 86 that extends circumferentially around the ring gear 62. Adjacent to the ring gear 62, a preloading member 64 is disposed that includes a second race 88 that is in a facing relationship with the first race 86.

[0121] The preloading member 64 includes a groove 90 that faces the second race 88. The first end of the spring 66 is located within the groove 90. The second end of the spring 66, opposite the first end, abuts against the spring retainer 68.

[0122] As shown in FIGS. 3B and 3C, the first race 86 of the ring gear 62 includes a wavy surface 92. The present disclosure anticipates that the second race 88 associated with the preloading member 64 can include a wavy surface 92 in addition to or in place of the first race 86. The wavy surface 92 includes a series of peaks 94 and valleys 96 and an inclination 98 extending therebetween. The plurality of balls 84 shown in FIG. 3A can be located between and within the first race 86 and the second race 88. There may be a number of balls 84 corresponding to the number of valleys 96, or alternatively there may be a smaller number of balls relative to the number of valleys 96.

[0123] Returning to FIG. 3A, spring 66 applies a force to preload member 64, thereby holding ball 84 within valley 96. As described herein, the preload of spring 66, the angle of ramp 98, the number of balls 84, the dimensions of balls 84 (e.g., diameter), the height of peak 94 measured from valley 96, or any combination thereof can define the torque limit required for ball 84 to slide over peak 94 of the surface 92 on which it is undulating. Other configurations for defining the torque limit can be understood by the present teachings.

[0124] Below the torque limit, the engagement of ball 84 within valley 96 fixes the position of ring gear 62 and prevents it from rotating. In this configuration, planet gear 70 orbits around sun gear 72. Above the torque limit, ball 84 slides over peak 94 and ring gear 62 is allowed to rotate. In this configuration, planet gears 70 rotate with respect to their respective shafts 78, but they do not orbit around sun gear 72. Instead of the planet gears orbiting around sun gear 72, ring gear 62 orbits around sun gear 72.

[0125] The descriptions and illustrations presented herein are for the purpose of informing those skilled in the art of the invention, its principles, and its practical applications. Those skilled in the art can adapt and apply the invention in its numerous forms so as to best suit the requirements of a particular use.

[0126] It is to be understood that the above description is intended to be illustrative and not limiting. Many embodiments and many applications other than the given examples will be apparent to those skilled in the art upon reading the above description.

[0127] As can be found from the following claims, other combinations are possible and these are hereby incorporated by reference herein.

[0128] Accordingly, the scope of the invention should not be determined with reference to the above description, but rather should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0129] In the following claims of any aspect of the subject matter disclosed in this specification, an omission does not amount to a waiver of such subject matter, nor should it be considered that the inventors regarded such subject matter as not being part of the subject matter of the invention disclosed.

[0130] A plurality of elements may be provided by a single integrated element. Alternatively, one element may be divided into a plurality of elements.

[0131] The disclosure of "a" or "one" to describe an element is not intended to exclude additional elements.

[0132] Terms such as first, second, third, etc. may be used in this specification to describe various elements, components, regions, and / or sections, but these elements, components, regions, and / or sections should not be limited by these terms. These terms may be used to distinguish one element, component, region, and / or section from another. Terms such as "first", "second", etc., and other numerical terms, when used in this specification, do not imply an order or sequence unless clearly indicated by the context. Thus, a first element, component, region, and / or section described above or below may also be referred to as a second element, component, region, and / or section without departing from the present teachings.

[0133] Spatially relative terms such as "inner", "outer", "directly below", "below", "lower side", "above", "upper side", etc. may be used herein to facilitate the description of the relationship of one element or feature to another element or feature as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. For example, if the device in the figure is turned upside down, an element described as "below" or "directly below" another element or feature will then be oriented "above" the other element or feature. Thus, the exemplary term "below" can encompass both upward and downward orientations. The device may be oriented in other ways (rotated 90 degrees or otherwise), and the spatially relative descriptors used herein are to be interpreted accordingly.

[0134] The terms "substantially" or "about" used to describe an angular measurement may mean within about + / - 10° or less, about + / - 5° or less, or even about + / - 1° or less. The terms "substantially" or "about" used to describe an angular measurement may mean within about + / - 0.01° or more, about + / - 0.1° or more, or even about + / - 0.5° or more.

[0135] The use of "about" or "approximately" in connection with a range applies to both ends of the range. Thus, "about 20 to 30" is intended to encompass "about 20 to about 30" including at least the specified endpoints.

[0136] Unless otherwise indicated, any numerical value recited herein includes all values from the lower value to the higher value in increments of one unit, provided that there is a separation of at least two units between any lower value and any higher value. For example, if a value is stated to be, for example, from 1 to 90, from 20 to 80, or from 30 to 70, then values in the intermediate ranges (e.g., from 15 to 85, from 22 to 68, from 43 to 51, from 30 to 32, etc.) are intended to be within the scope of the teachings. For values less than 1, one unit is considered to be 0.0001, 0.001, 0.01, or 0.1 as appropriate. These are merely examples of what is specifically intended, and all possible combinations of numerical values between the recited lowest value and the highest value are to be considered as being explicitly recited in this application as well. Unless otherwise indicated, all ranges include both endpoints and all numbers between the endpoints.

[0137] The term "consisting essentially of" for describing a combination shall include the specified elements or components, and other elements or components that do not substantially affect the basic and novel features of the combination. The use of the terms "comprising" or "including" for describing a combination of elements or components herein also anticipates embodiments consisting essentially of the elements or components.

[0138] The disclosures of all articles and references, including patent applications and publications, are incorporated by reference for all purposes.

Explanation of Reference Numerals

[0139] 10 Brake system 12 Caliper 14 Inner body portion 16 Outer body portion 18 Bridge portion 20 Main body portion 22 Finger 24 Pair of brake pads 26 Inner brake pad 28 Outer brake pad 30 Cylinder 32 Piston 34 Electromechanical actuation system 36 Spindle 38 Nut 40 Fluid 42 Motor gear unit 44 Motor gear unit housing 46 Motor 48 Torque limiter assembly 50 Motor drive shaft 52 Motor drive gear 54 Spline gear 56 Pinion 58 Torque limiter drive gear 60 Torque limiter drive shaft 62 Ring gear 64 Preload member 66 Spring 68 Spring retainer 70 Planet gear 72 Sun gear 74 First plate carrier 76 Second plate carrier 78 Shaft 80 Bush 82 Output shaft 84 Ball 86 First race 88 Second race 90 Groove 92 Wavy surface 94 Crest 96 Trough 98 Inclination

Claims

1. In a braking system, the braking system comprises an electromechanical actuation system having at least a first part and a second part, each part comprising a torque limiter assembly for setting a torque limit, the torque limiter assembly comprising a planetary gear set meshing with a sun gear, a ring gear meshing with the planetary gear set and having a first race extending circumferentially, a preload member having a second race extending circumferentially, and balls or rollers engaged between the first race and the second race, wherein the first race and / or the second race comprises a series of ridges and valleys and inclines extending therebetween, below the torque limit, the balls or rollers are engaged within the valleys, allowing the ring gear to be rotatably captured and causing the planetary gear set to orbit around the sun gear, above the torque limit, the balls or rollers slide over the ridges, rotating the ring gear and allowing the planetary gear set to be captured in an orbiting manner, a braking system.

2. The angle of the incline at least partially determines the torque limit, and the angle of the incline is between about 5° and about 45°, the braking system according to claim 1.

3. The angle of the incline in the release direction of the balls or rollers is the same as or different from the angle of the incline in the application direction of the balls or rollers, the braking system according to claim 1 or 2.

4. The angle of the incline in the release direction of the balls or rollers is about 2% to 25% greater than the angle of the incline in the application direction of the balls or rollers, the braking system according to claim 1 or 2.

5. The torque limiter assembly comprises a spring substantially circumferentially aligned with the first and second races and applying a force to the preload member such that the balls or rollers are compressed between the preload member and the ring gear the braking system according to claim 1 or 2.

6. The height of the ridges measured from the valleys at least partially determines the torque limit, the braking system according to claim 5.

7. The brake system according to claim 1 or 2, wherein the hills, valleys, and inclines are defined by a wavy surface, a jagged surface, or both.

8. Each part of the electromechanical actuation system A first plate carrier that engages on a first side of the planetary gear set such that the orbit of the planetary gear set rotates the first plate carrier A second plate carrier that engages on a second side of the planetary gear set such that the orbit of the planetary gear set rotates the second plate carrier, the second side being opposite the first side The brake system according to claim 1 or 2.

9. The first or second plate carrier includes an output shaft that mechanically cooperates with a spindle, the spindle cooperating with a nut as a ball screw mechanism or a normal screw mechanism, and the nut engaging a piston. The brake system according to claim 8.

10. The rotation of the spindle ultimately axially translates the piston in the application direction and / or the release direction. The brake system according to claim 9.

11. The torque limit of the first part is different from the torque limit of the second part. The brake system according to claim 1 or 2.

12. Both the first part and the second part of the electromechanical actuation system are actuated by the same motor. The brake system according to claim 1 or 2.

13. Comprising a caliper having an inner body part and an outer body part A bridge extends between the inner body part and the outer body part The bridge includes one or more fingers that act on a brake pad associated with the outer body part The brake system according to claim 1 or 2.

14. Comprising two or more pistons located entirely on the inner body part or the outer body part, or on both the inner body part and the outer body part Each of the first part and the second part of the electromechanical actuation system is associated with a respective one of the two or more pistons The brake system according to claim 13.

15. Each part of the electromechanical actuation system acts symmetrically on the two or more pistons until the torque limit is achieved by the resistance to at least one of the pistons, at which point the electromechanical actuation system acts asymmetrically on the two or more pistons due to the rotational freedom of the ring gear. The braking system according to claim 14.

16. In an electromechanical actuation system for a vehicle brake, the electromechanical actuation system comprises a nut and a spindle, the rotation of the spindle actuating the nut in an application direction and a release direction, a motor in mechanical communication with the spindle, and a torque limiter assembly disposed mechanically downstream of the motor and mechanically upstream of the spindle and comprising an electromechanical actuation system, wherein the torque limiter assembly is set to a torque limit and below the torque limit, rotational movement is transmitted to the spindle, and above the torque limit, rotational movement is not transmitted to the spindle.

17. The electromechanical actuation system according to claim 16, wherein the torque limiter assembly is a ball detent type torque limiter.

18. The torque limiter assembly comprises a planetary gear set, a sun gear, and a ring gear, the planetary gear set meshing with both the sun gear and the ring gear, below the torque limit, the ring gear remains rotatably captured and the planetary gear set orbits around the sun gear, above the torque limit, the ring gear rotates and the planetary gear set remains capturable in an orbiting manner. The electromechanical actuation system according to claim 16 or 17.

19. The ring gear comprises a series of teeth and valleys and a race extending therebetween, the electromechanical actuation system comprising a ball or roller engaging the race, below the torque limit, the ball or roller engages within the valley, and above the torque limit, the ball or roller slides over the teeth. The electromechanical actuation system according to claim 16 or 17.

20. The electromechanical actuation system according to claim 16 or 17, comprising two or more parts, each part being associated with a separate piston for engaging a brake pad, each part comprising said torque limiter assembly.

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