Brake system with torque limiter assembly

Abstract

The brake system (10) includes a torque limiter assembly (48) that sets a torque limit and is associated with the electromechanical actuation system. The torque limiter assembly (48) includes a ring gear (62) engaged with the planetary gear set (70), the ring gear (62) including a first race (86) extending circumferentially thereabout. The torque limiter assembly (48) includes a preload member including a second race (88) extending circumferentially thereabout. A ball or roller (84) is engaged between the first and second races (86, 88). The first and / or second races (86, 88) include a series of peaks and valleys and ramps extending between the peaks and valleys. At or below the torque limit, the balls or rollers (84) engage within the valleys, causing the ring gear (62) to remain rotationally constrained and the planetary gear set (70) to be set to orbital operation. At and above torque limits, the balls or rollers (84) slip over a peak, causing the ring gear (62) to rotate and the planetary gear set (70) to remain orbitally constrained.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Application No. 17 / 878,518, filed on August 1, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a torque limiter assembly operable with a braking system. The torque limiter assembly is associated with an electromechanical actuation system. Background Art

[0004] Braking systems are typically used to operate two or more pistons on a brake pad to apply it into engagement with the rotor or release it from engagement with the rotor. The pistons generally work together to apply symmetrical pressure to the rotor. In some cases, one piston must travel a longer distance than another piston acting on the same brake pad. Thus, the torque applied to the pistons in the "apply" or "release" operation must be applied asymmetrically until symmetrical pressure is applied to the brake pad. If symmetrical pressure is not applied to the brake pad, insufficient braking force and uneven wear of the brake pad friction material may result.

[0005] One solution to asymmetric piston travel is to use a limited slip differential, as described in U.S. Patent No. 9,879,739 B2. This solution requires packaging space, complex metal parts, and precise manufacturing and assembly methods to operate consistently. Moreover, small variations in sliding torque between different pistons can produce excessive loads on one or more pistons.

[0006] It is desirable to actuate the piston assembly asymmetrically.

[0007] The mechanism for asymmetrically actuating the piston assembly needs to be assembled in a smaller packaging space than that of a limited slip differential system.

[0008] There is a need for a solution to asymmetric piston assembly actuation that requires fewer parts than the complexity of limited slip differential systems.

[0009] Asymmetric piston assembly actuation needs to be addressed with relatively less complex manufacturing and assembly methods relative to limited slip differential systems. Summary of the invention

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

[0011] Each torque limiter assembly may include a planetary gear set, a ring gear, a preload member, and a ball or roller. The planetary gear set may be meshed with a sun gear. The ring gear may be meshed with the planetary gear set. The ring gear may include a first race extending circumferentially therearound. The preload member may include a second race extending circumferentially therearound. The ball or roller may be engaged between the first race and the second race.

[0012] The first race and / or the second race may include a series of peaks and valleys and a slope extending between the peaks and valleys.

[0013] Below the torque limit, the balls or rollers may engage within the valleys, causing the ring gear to remain rotationally constrained and the planetary gearset to orbit about the sun gear.

[0014] At and above the torque limit, the balls or rollers may slide over the peaks, causing the ring gear to rotate and the planetary gearset to maintain orbital constraint.

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

[0016] The angle at which the ball or roller travels across the ramp in the release direction may be the same as or different than the angle at which the ball or roller travels across the ramp in the apply direction.

[0017] The angle at which the ball or roller travels across the ramp in the release direction may be approximately 2% to 25% greater than the angle at which the ball or roller travels across the ramp in the apply direction.

[0018] The torque limiter assembly may include a spring. The spring may be generally circumferentially aligned with the first race and the second race. The spring may apply a force to the preload member such that the ball or roller is compressed between the preload member and the gear ring.

[0019] The height of the peak measured from the valley may determine the torque limit. The height of the peak may determine the degree to which the spring is compressed.

[0020] The force exerted on the preload member may at least partially determine the torque limit.

[0021] The peaks, valleys, and slopes may be defined by wavy surfaces, serrated surfaces, or both.

[0022] Each portion of the electromechanical actuation system may include a first plate carrier and / or a second plate carrier. The first plate carrier may engage a first side of the planetary gear set such that orbiting of the planetary gear set causes the first plate carrier to rotate. The second plate carrier may engage a second side of the planetary gear set such that orbiting of the planetary gear set causes the first plate carrier to rotate. The second side may be opposite the first side.

[0023] The first plate carrier or the second plate carrier may include an output shaft mechanically cooperating with a main shaft. The main shaft may cooperate with a nut as a ball screw mechanism or a normal screw mechanism. The nut may engage a piston.

[0024] Rotation of the spindle may ultimately result in axial translation of the piston in an apply direction and / or a release direction.

[0025] The torque limit of the first portion may be different than the torque limit of the second portion.

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

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

[0028] The brake system may include two or more pistons located entirely on the inner body portion or the outer body portion, or on both the inner body portion and the outer body portion. Each of the first and second parts of the electromechanical actuation system may be associated with each of the two or more pistons.

[0029] Each part of the electromechanical actuation system can act symmetrically on the two or more pistons until the resistance to at least one of the pistons causes the torque limit to be reached. At this point, the electromechanical actuation system can 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 above needs. The electromechanical actuation system can be used for vehicle brakes. The electromechanical actuation system can include a nut and a spindle. Rotation of the spindle can actuate the nut in an application direction and / or a release direction. The electromechanical actuation system can include a motor. The motor can be mechanically connected to the spindle.

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

[0032] The torque limiter assembly may be a ball and pawl type torque limiter.

[0033] The torque limiter assembly may include a planetary gear set, a sun gear, and a ring gear. The planetary gear set may mesh with both the sun gear and the ring gear. Below the torque limit, the ring gear may remain constrained to rotation, and the planetary gear set may run around the sun gear. At and above the torque limit, the ring gear may rotate, and the planetary gear set may remain constrained to orbit.

[0034] The gear ring may include a race having a series of peaks and valleys and a ramp extending between the peaks and valleys. The electromechanical actuation system may include a ball or roller engaged with the race. Below the torque limit, the ball or roller may engage within the valleys. At and above the torque limit, the ball or roller may slide over the peaks.

[0035] The electromechanical actuation system may comprise two or more parts. Each part may be associated with a separate piston to engage a brake pad. Each part may be provided with the torque limiter assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1A is a perspective view of a brake system according to the present teachings.

[0037] Figure 1B is a perspective view of a brake system according to the present teachings.

[0038] Figure 1C It is taken along line AA Figure 1A A cross-sectional view of the brake system shown in FIG.

[0039] Figure 2A is a perspective view of a motor gear unit and a piston according to the present teachings.

[0040] Figure 2B is a plan view of a motor gear unit and a piston according to the present teachings.

[0041] Figure 3A is an exploded view of a torque limiter assembly according to the present teachings.

[0042] Figure 3B is a perspective view of a ring gear according to the present teachings.

[0043] Figure 3C It is taken along line BB Figure 3B A cross-sectional view of the ring gear shown in FIG. DETAILED DESCRIPTION

[0044] The present teaching provides a torque limiter assembly that can be operated with a braking system. The torque limiter assembly can be associated with an electromechanical actuation system. That is, the torque limiter assembly can be integrated into a mechanical drive mechanism of the electromechanical actuation system.

[0045] The brake system may include an electromechanical actuation system. The electromechanical actuation system may employ a motor to ultimately move one or more pistons in an apply direction and / or a release direction.

[0046] 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.

[0047] The electromechanical actuation system may include one or more torque limiter assemblies.The torque limiter assembly may be mechanically located downstream of the motor and mechanically located upstream of the piston.

[0048] One torque limiter assembly may be provided for each piston, but the present teachings contemplate that one torque limiter assembly may be associated with multiple pistons.

[0049] The brake 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 in a cylinder containing the piston.

[0050] The hydraulic actuation system may be associated with a service brake operation and / or a parking brake operation. Preferably, the hydraulic actuation system may be associated with a service brake operation.

[0051] The electromechanical and hydraulic actuation systems may act individually and / or in conjunction to move the piston in an application operation and / or a release operation. In an application operation, the piston may move toward the rotor, thereby affecting movement of one or more brake pads toward and / or engaging with the rotor. In a release operation, the piston may move away from the rotor, thereby affecting movement of one or more brake pads away from and / or disengaging from the rotor.

[0052] The brake system may include a caliper. The caliper may be used to house at least a portion of an electromechanical actuator system and / or a hydraulic actuator system, provide a mounting point for a brake pad, position the brake pad relative to a 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 on an inner side of the rotor. The outer body portion may be located on an outer side of the rotor.

[0053] 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 fastened to the caliper. When fastened, the electromechanical and / or hydraulic actuation system may slide relative to the caliper.

[0054] 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.

[0055] The caliper may include both a floating portion and a fixed portion.

[0056] The braking system may include one or more brake pads. The brake pads may be used to frictionally engage the rotor. The brake pads may engage the rotor and cause the rotor and / or a vehicle employing the rotor to decelerate and / or stop. That is, the rotational motion of the rotor may be decelerated and / or stopped, and the linear motion of the vehicle may be decelerated and / or stopped.

[0057] The brake pad may be fastened to the caliper, for example, with a clip. The brake pad may engage with and be moved by one or more pistons. Preferably, the pistons may act symmetrically on opposite ends of the brake pad. In this regard, the entire surface area, or at least a majority of the surface area, of the friction material on the brake pad is brought into engagement with the rotor. Thereby, uneven wear on the brake pad may be avoided or at least mitigated, and the full intended braking load may be achieved.

[0058] A pair of brake pads may be used. The brake pads may include an inner brake pad positioned on an inner body portion of the caliper and an outer brake pad positioned on an outer body portion of the caliper. The inner brake pad and the outer brake pad may clamp the rotor.

[0059] The caliper may include one or more cylinders. The cylinder may be used to contain a piston, a fluid of a hydraulic actuation system, a component of an electromechanical actuation system, or any combination thereof. The cylinder may be formed in the caliper, for example, by casting, machining, or both.

[0060] The brake system may include one or more pistons. The piston may be used to cooperate with a hydraulic actuation system and / or an electromechanical actuation system to engage and apply a load to the brake pad. One or more components of the electromechanical actuation system (e.g., a nut and a spindle) and / or a fluid located within the cylinder may cause the piston to move within the cylinder.

[0061] The piston may be located within the cylinder. The piston may be movable within the cylinder. The piston may include a portion extending outside the cylinder. The portion extending outside the cylinder may engage the brake pad.

[0062] One or more cylinders and associated pistons may be located in or near the inner body portion. These may be referred to herein as the inner cylinder and inner piston. One or more cylinders and associated pistons may be located in or near the outer body portion. These may be referred to herein as the outer cylinder and outer piston. 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 cylinder and associated piston are located at least in or near the inner body portion.

[0063] The inner cylinder and the associated piston may be coaxial with the outer cylinder and the associated piston. In this regard, the clamping force applied by the relative inner and outer pistons is coaxial. Such paired coaxial inner and outer cylinders and the associated pistons may be referred to herein as corresponding pairs.

[0064] The brake system may not have one or more pairs of corresponding cylinders and associated pistons. For example, the brake system may include only the inner cylinder and associated piston. By way of another example, the corresponding pair of cylinders and associated pistons may be located in or near a first portion of the caliper, and only the inner cylinder and associated piston are located in or near a second portion of the caliper. Other arrangements are contemplated by the present teachings.

[0065] In the case where a portion of the caliper is devoid of a corresponding pair of cylinders and associated pistons, the brake system may include a bridge portion. The bridge portion may be used to transfer loads from the inside of the brake system to the outside of the brake system. The bridge portion may extend over both the inner body portion and the outer body portion of the caliper.

[0066] The first end of the bridge portion may be coupled to the main body portion of the brake system or any other component coupled to the main body portion. The main body portion may be slidably coupled to the caliper. The second end of the bridge portion may be provided with one or more fingers. The fingers may be used to engage the brake pad. The fingers may extend from the bridge at an angle (e.g., about 90 degrees).

[0067] In an application operation, a load may be applied to the piston by one or both of the electromechanical actuation system and the hydraulic actuation system. As a result, the piston may be caused to press the first brake pad against the rotor. Then, in order to cope with the load, the bridge portion and the finger may be displaced axially inward, and the finger may press the second brake pad against the rotor. The first brake pad may be the inner brake pad, and the second brake pad may be the outer brake pad, or vice versa. In this regard, the load is applied to opposite sides of the rotor (i.e., a clamping action), causing the rotor and / or the vehicle to slow down and / or stop.

[0068] The electromechanical actuator system may include a motor-gear unit. The motor-gear unit may be used to move the piston in an application direction and / or a release direction. To this end, the motor-gear unit may include an electric drive motor and one or more connecting rods located between the motor and the one or more pistons, so that the motor drives the one or more connecting rods, resulting in the movement of the one or more pistons.

[0069] The motor-gear unit may include a motor, one or more torque limiter assemblies, or both.

[0070] The motor gear unit may include a motor gear unit housing. The motor gear unit housing may be used to protect the internal mechanism of the motor gear unit. The motor gear unit housing may contain a motor, one or more torque limiter assemblies, or both. The motor gear unit housing may be configured as one or more components located around the motor gear unit.

[0071] The motor gear unit may include a motor. The motor may be used to actuate the piston in an application direction (ie, toward the rotor) and / or a release direction (ie, away from the rotor). Non-limiting examples of suitable motors may include servomotors and stepper motors.

[0072] 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 be provided with a motor drive gear arranged along its length.

[0073] The motor gear unit may include one or more motor drive gears. The motor drive gear may be used to transfer the torque generated by the motor and provided to the motor drive shaft to the torque limiter assembly. The motor drive gear may 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.

[0074] One or more other connecting rods may be arranged between the motor drive gear and one or more torque limiter assemblies. One or more other connecting rods may include one or more gears, shafts, chains, belts, etc., or any combination thereof. The physical size and / or arrangement of one or more other connecting rods may be selected to adapt to the packaging space of the braking system. For example, in order to package the motor on the main body portion and / or the inner body portion of the caliper while maintaining a suitable gap with them and / or with one or more torque limiter assemblies, one or more gears may be arranged between the motor drive gear and one or more torque limiter assemblies. The present teaching contemplates any other suitable connecting rod arrangement that can mechanically connect the motor to one or more torque limiter assemblies.

[0075] The bevel gear and pinion gear may be disposed between the motor drive gear and one or more torque limiter assemblies. The bevel gear and pinion gear may share a common shaft. The bevel gear and pinion gear may rotate in unison. The bevel gear may mesh with the motor drive gear. The pinion gear may mesh with one or more torque limiter assemblies. The pinion gear may be a spur gear.

[0076] The electromechanical actuator system may include a spindle. The spindle may be used to mechanically communicate with the torque limiter assembly to cause the nut to axially translate in an apply direction and / or a release direction, or both. The spindle may be threaded on its outer peripheral surface. The thread may be sized to receive a ball or a roller.

[0077] The electromechanical actuator system may include a nut. The nut may be configured to move axially along the length of the spindle, engage the piston, move the piston in an application direction and / or a release direction, or any combination thereof. The nut may be threaded on an inner circumferential surface thereof. The thread may be sized to receive a ball or roller.

[0078] The nut may be disposed on the spindle. A plurality of balls or rollers and / or one or more springs may be disposed within the threads of both the spindle and the nut. The balls or rollers may provide a low friction engagement of the nut with the spindle relative to a direct threaded engagement of the nut with the spindle to assist in moving the nut in the application and / or release directions.

[0079] The nut and spindle described above may cooperate as a ball screw mechanism. However, the present teachings contemplate that the brake system may employ other spindle and nut arrangements or other piston actuation mechanisms. For example, the nut and spindle may cooperate as a common screw mechanism. In a common screw mechanism (i.e., a screw and nut mechanism).

[0080] The electromechanical actuator system may include one or more torque limiter assemblies. The torque limiter assemblies may be used to actuate different pistons asymmetrically. The torque limiter assemblies may be ball-pawl type torque limiters.

[0081] The electromechanical actuator system may include one or more parts. Each part may actuate a separate piston. Preferably, two parts may be used to actuate a piston that engages two parts of a brake pad, but the present disclosure also contemplates the use of fewer or more parts. Each part may include a torque limiter assembly. A single torque limiter assembly may be associated with two or more parts, and thus with two or more pistons.

[0082] Each part can be actuated by the same motor or a different motor. Preferably, each part can be actuated by the same motor.

[0083] The torque limiter assembly may be set to a torque limit. The torque limit may be adjustable. Below the torque limit, the ring gear described herein may remain constrained in rotation and the planet gears may orbit around the sun gear. At and above the torque limit, the ring gear may rotate and the planet gears may remain constrained in orbit relative to the sun gear. The ring gear may rotate by means of balls or rollers sliding over peaks in the preload member and / or raceway of the ring gear. The ring gear may rotate relative to the preload member.

[0084] When one or more parts of the electromechanical actuation system reach the torque limit, its torque limiter may slip. At this point, one or more other parts of the electromechanical actuation system may continue to actuate the spindle until the torque limit is reached. Thus, any axial position differences between the pistons of each part of the electromechanical actuation system may be eliminated, and the respective loads applied to different parts of the brake pad may be substantially uniform.

[0085] When one or more pistons reach a torque limit through their engagement with one or more brake pads, one or more pistons may cease moving (e.g., in an apply direction) and one or more other pistons may continue moving (e.g., in an apply direction) until they respectively reach a torque limit.

[0086] The application operation of the piston may be maintained for a period of time. For example, a parking brake may be applied when the vehicle is not occupied. When the electromechanical actuation system is operated in the application direction, the motor may be operated until a predetermined load applied to one or more brake pads is reached. The motor may then cease operation and the load may be maintained until the electromechanical actuation system disengages and moves the one or more pistons in the release direction. The torque limit may be applied in the release direction while the load is maintained for a period of time.

[0087] The torque limit in the apply and / or release direction may 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.

[0088] The torque limit of one or more portions of the electromechanical actuation system may be the same as or different than the torque limit of one or more other portions of the electromechanical actuation system.

[0089] As described herein, the ring gear and / or preload member may include: a race having a serrated and / or wavy surface having a series of peaks and valleys; and a ball or roller located between the ring gear and the preload member, which is located in one or more races. Below the torque limit, the ball or roller may engage in the valleys of the serrated and / or wavy surface. At and above the torque limit, the ball or roller slides over the peaks of the serrated and / or wavy surface.

[0090] Each part of the electromechanical actuation system can act symmetrically on one or more pistons until the resistance to at least one piston causes the torque limit to be reached. At this point, due to the rotational freedom of the gear ring, the electromechanical actuation system can act asymmetrically on one or more pistons.

[0091] The torque limiter assembly may include a torque limiter drive shaft and a torque limiter drive gear. The torque limiter drive shaft may be used to transfer torque to the planetary gear set via the sun gear. The torque limiter drive gear may be used to receive torque from one or more other connecting rods and / or one or more gears of the motor drive shaft. The torque limiter drive gear may be fastened to the torque limiter drive shaft (e.g., via a keyway). The torque limiter drive shaft may be formed integrally with the torque limiter drive shaft (e.g., by casting a splined drive shaft).

[0092] The torque limiter drive shaft may include a sun gear. The sun gear may be used to transfer 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 fastened 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 mesh with the planetary gear set.

[0093] The torque limiter assembly may include a planetary gear set. The planetary gears may be used to selectively transfer torque from the torque limiter drive shaft to the output shaft. The planetary gears may orbit around the sun gear. The planetary gears may mesh with the sun gear and / or the ring gear. The planetary gears may be spur gears.

[0094] The torque limiter assembly may include a first plate frame and / or a second plate frame. The first plate frame and / or the second plate frame may be used to convert the orbital motion of the planetary gear into a torque provided to the output shaft. The first plate frame may be coupled to the second plate frame. The planetary gear may be fixed between the first plate frame and the second plate frame. The first plate frame may be disposed on a first side of the planetary gear, and the second plate frame may be disposed on an opposite second side of the planetary gear.

[0095] The first plate frame and / or the second plate frame may include one or more shafts. The planetary gears may be located on the shafts. The shafts may be distributed circumferentially around the first plate frame and / or the second plate frame. The planetary gears may rotate on the shafts.

[0096] One or more bushings may be located on the shaft, between the shaft and the planet gears. The bushings may assist the rotation of the planet gears. The bushings may provide a lower friction surface relative to a direct connection between the planet gears and the shaft.

[0097] 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 main shaft. The output shaft may be splined and the main shaft may include a groove to accommodate the spline, or vice versa.

[0098] The torque limiter assembly may include a ring gear. The ring gear may be configured to selectively rotate so that orbital movement of the planetary gears may be provided or excluded. The ring gear may be an internal gear. The ring gear may mesh with the planetary gear set.

[0099] When the ring gear is rotationally constrained, the planet gears can orbit around the sun gear, and when the ring gear is free to rotate, the torque provided by the sun gear to the planet gears can be transmitted to the ring gear, and the planet gears can be orbitally constrained. Thus, when the ring gear changes from rotational constraint to rotational freedom, the torque limit can be reached.

[0100] The ring gear may be rotationally constrained when the balls or rollers engage in the valleys of the ring gear's race. The ring gear may be rotationally free when the balls or rollers slide over the peaks of the ring gear's race.

[0101] The torque limiter assembly may include a preload member. The preload member may be used to apply a predetermined force to the ball or roller, to hold the ball or roller between the preload member and the ring gear, or both.

[0102] The preload member may include a groove. The groove may be used to receive a portion of the spring. The groove may be located on a first end of the preload member opposite the second end, the second end including the seat ring and adjacent to the gear ring.

[0103] The torque limiter assembly may include a spring. The spring may be used 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.

[0104] The force applied to the preload member may determine the torque limit. The force may be adjusted by selecting springs with different spring rates, changing the precompression of the spring (e.g., by changing the distance between the preload member and the spring retainer), or both. The preload of the spring may be fixed or adjustable. The preload of the spring may be actively adjustable.

[0105] The spring may be a coil spring, a washer spring, a spring assembly, an elastic element, etc., or any combination thereof.

[0106] The torque limiter assembly may include a spring retainer. The spring retaining member may be used to preload the spring. The spring retainer may be a snap ring. The snap ring may engage an inner surface of the motor gear unit housing. For example, the snap ring may fit into a groove formed in the inner surface of the motor gear unit housing. The spring retainer may be integrally formed with the motor gear unit housing, for example by molding, casting, machining, or any combination thereof.

[0107] The ring gear may include a first race. The first race may be used to receive balls or rollers, set a torque limit, or both. The first race may extend circumferentially around the ring gear.

[0108] The preload member may include a second race. The second race may be used to receive balls or rollers, set a torque limit, or both. The second race may extend circumferentially around the preload member.

[0109] The torque limiter assembly may include one or more balls or rollers. The balls or rollers may be used to selectively secure the 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.

[0110] The first race and / or the second race may include a wavy surface and / or a serrated surface. The wavy surface and the serrated surface may include peaks and valleys. The ball or roller may be constrained in the valley until the torque limit is reached. When the torque limit is reached or exceeded, the ball or roller may slide over the peak.

[0111] The height of the peak measured against the valley can determine the torque limit. The ball or roller can go up the ramp before reaching the peak and slide into the next valley. As the ball or roller passes through the height, the spring can be compressed.

[0112] The slope may extend between peaks and valleys. The slope may be defined by an angle and / or a curvature. A first portion of the slope may be defined by an angle and a second portion of the slope may be defined by a curvature.

[0113] The angle of the inclined plane can determine the torque limit. The angle of the inclined plane 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 parts of the inclined planes oriented in the same direction (i.e., the direction of application or release) can be defined by different angles or the same angle. One or more inclined planes oriented in the same rotational direction can be defined by different angles or the same angle. As described herein, relative to the race, the direction of rotation can refer to the clockwise or counterclockwise direction of the ball or roller relative to the race. The application operation can involve clockwise rotation, and the release operation can involve counterclockwise rotation, and vice versa.

[0114] The curvature of the ramp may determine the torque limit.One or more ramps oriented in the same rotational direction may be defined by different curvatures or by the same curvature.

[0115] The angle and / or curvature of the ramp that the ball or roller travels through in the release direction may be the same as the angle and / or curvature of the ramp that the ball or roller travels through 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.

[0116] The angle and / or curvature of the ramp that the ball or roller travels through in the release direction may be different from the angle and / or curvature of the ramp that the ball or roller travels through 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.

[0117] The angle and / or curvature of the inclined surface that the ball or roller travels through in the release direction may be greater than the angle and / or curvature of the inclined surface that the ball or roller travels through in the application direction by more than about 2%, more preferably more than about 5%, or even more preferably more than about 10%. The angle and / or curvature of the inclined surface that the ball or roller travels through in the release direction may be greater than the angle and / or curvature of the inclined surface that the ball or roller travels through in the application direction by less than about 25%, more preferably less than about 20%, or even more preferably less than about 15%.

[0118] Figures 1A to 1C A brake system 10 is shown. The brake system 10 includes a caliper 12 including an inner body portion 14 and an outer body portion 16. Extending on the caliper 12 is a bridge portion 18 extending from the body portion 20. Extending from the bridge portion 18 are three fingers 22 located adjacent the outer body portion 16, but the present teachings contemplate any number of fingers 22. Preferably, at least two fingers 22 are employed so that two opposite ends of the brake pad are acted upon. The brake system 10 includes a pair of brake pads 24 including an inner brake pad 26 and an outer brake pad 28. The inner body portion 14 and the inner brake pad 26 are located on the inner side of the rotor. The outer body portion 16 and the outer brake pad 28 are located on the outer side of the rotor. A floating caliper design is shown, however, the present teachings are also applicable to fixed caliper designs.

[0119] like Figure 1CAs shown, the brake system 10 includes two cylinders 30 defined in the body portion 20, with associated pistons 32 located therein and extending therefrom. The pistons 32 move within the cylinders 30 in an application direction and a release direction. The pistons 32 act on the inner brake pads 26. The present teachings contemplate that one or more cylinders 30 and associated pistons 32 may be located near one or both of the inner body portion 14 and the outer body portion 16. Actuation of the pistons 32 relative to the inner brake pads 26 causes the fingers 22 to act on the outer brake pads 28. This may be due to the body portion 20 and the attached bridge portion 18 being slidably fastened to the caliper 12, allowing movement of the bridge portion 18 relative to the caliper 12. Specifically, in an application operation, a load is applied to the pistons 32 by one or both of the electromechanical actuation system 34 and the hydraulic actuation system. As a result, the pistons 32 are caused to apply a load to the inner brake pads 26, which in turn applies a load to the rotor. Then, in response to the load applied by the piston 32, the bridge portion 18 and the fingers 22 are displaced axially inwardly relative to the caliper 12, whereby the fingers 22 press the outer brake pad 28 against the rotor. Thus, loads are applied to opposite sides of the rotor, resulting in braking.

[0120] The brake system 10 of the present teaching includes at least an electromechanical actuation system 34 and optionally a hydraulic actuation system. The torque limiter assembly of the present teaching is associated with the electromechanical actuation system 34. The electromechanical actuation system 34 and / or the hydraulic actuation system act on the piston 32, causing the piston 32 to move within the cylinder 30. Specifically, the electromechanical actuation system 34 causes the spindle 36 to rotate while maintaining an axial constraint to move the nut 38 axially toward and away from the inner brake pad 26, and the nut 38 engages and causes the piston 32 to move. The hydraulic actuation system causes the fluid 40 residing in the cylinder 30 to apply and release hydraulic pressure on the piston 32. During the application operation and the release operation, the electromechanical actuation system 34 and the hydraulic actuation system can work separately and / or cooperate with each other. Typically, the electromechanical actuation system 34 operates the parking brake and the hydraulic actuation system operates the service brake, but other arrangements are also contemplated by the present teaching.

[0121] The electromechanical actuation system 34 includes a motor-gear unit 42 coupled to the main body 20 of the brake system 10 . The motor-gear unit 42 includes a motor-gear unit housing 44 that covers and protects the internal mechanisms of the motor-gear unit 42 .

[0122] Figure 2A and Figure 2B The motor gear unit 42 is shown with the Figures 1A to 1CThe motor gear unit housing 44 is shown. The motor gear unit 42 includes a motor 46 and two torque limiter assemblies 48. The present teachings also contemplate one torque limiter assembly 48 or even three or more torque limiter assemblies 48. Typically, there is a torque limiter assembly 48 associated with each individual piston 32. The motor 46 includes a motor drive shaft 50, which includes a motor drive gear 52 acting on a bevel gear 54, and the bevel gear 54 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 bevel gear 54 and the pinion gear 56. The present disclosure contemplates that any number of connecting rods (e.g., gears) between the motor drive shaft 50 and the torque limiter assembly 48 can be employed. For example, the motor drive shaft 50 can be splined and directly engaged with the torque limiter assembly 48. The number and arrangement of the connecting rods can be guided by the desired packaging space of the components of the braking system 10. As Figure 2A and Figure 2B As shown, the bevel gear and pinion 56 allow the motor 46 to be packaged in Figure 1C Above the cylinder 30 shown in FIG.

[0123] Figure 2B Provided Figure 2A 4. An alternative view of the motor gear unit 42 depicted in FIG. 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 ( Figure 3A ), the sun gear 72 is associated with the torque limiter drive shaft 60. The ring gear 62 engages the ball 84 ( Figure 3A ). The preload member 64 is radially fixed to Figure 1C . The spring 66 engages the preload member 64 on a second side opposite thereto. The spring 66 is held in engagement with the preload member 64 by a spring retainer 68. The spring retainer 68 is coupled to Figures 1A to 1C The inner surface of the motor gear unit housing 44 shown in FIG. 4 and extending therefrom to provide a surface for the spring 66 to engage.

[0124] Figure 3AThe torque limiter assembly 48 is shown. The torque limiter assembly 48 includes a ring gear 62 that cooperates with three planet gears 70 driven by a sun gear 72. The sun gear 72 is splined on the torque limiter drive shaft 60. The sun gear 72 can be integrally formed with the torque limiter drive shaft 60 (e.g., by casting and / or machining) or fastened thereto (e.g., by keying). The sun gear 72 actuates the planet gears 70 relative to the ring gear 62. Three planet gears 70 are depicted, but the present teachings contemplate a fewer or greater number of planet gears 70.

[0125] The planetary gears 70 are secured between a first plate carrier 74 and a second plate carrier 76. The first plate carrier 74 includes three shafts 78 extending therefrom, the shafts 78 being provided with bushings 80 to facilitate rotation of the planetary gears 70. The present teachings contemplate that the shafts 78 extend from one or both of the first plate carrier 74 and the second plate carrier 76. The second plate carrier 76 includes an output shaft 82.

[0126] The ring gear 62 engages a ball 84 sandwiched between the ring gear 62 and a first side of the preload member 64. The spring 66 engages the preload member 64 on a second side opposite thereto. The spring 66 is retained in engagement with the preload member 64 by a spring retainer 68. The spring retainer 68 is located adjacent the torque limiter drive gear 58.

[0127] The ring gear 62 includes a first race 86 that extends circumferentially around the ring gear 62. Disposed adjacent the ring gear 62 is the preload member 64 that includes a second race 88 in opposing relationship to the first race 86.

[0128] The preload member 64 includes a groove 90 opposite the second race 88. A first end of the spring 66 is positioned within the groove 90. A second end of the spring 66 opposite the first end abuts against the spring retainer 68.

[0129] like Figure 3B and Figure 3C As shown, the first race 86 of the ring gear 62 includes a contoured surface 92. The present disclosure contemplates that the second race 88 associated with the preload member 64 may include a contoured surface 92 in addition to or in place of the first race 86. The contoured surface 92 includes a series of peaks 94 and valleys 96 and ramps 98 extending therebetween. A plurality of balls 84 may be located between and within the first race 86 and the second race 88, as shown in FIG. Figure 3A The number of balls 84 may correspond to the number of valleys 96 , or even the number of balls may be less relative to the number of valleys 96 .

[0130] Back to Figure 3A, the spring 66 applies a force to the preload member 64, thereby retaining the ball 84 in the valley 96. As described herein, the preload of the spring 66, the angle of the ramp 98, the number of balls 84, the size (e.g., diameter) of the balls 84, the height of the peaks 94 measured from the valleys 96, or any combination thereof may define the torque limit required to slide the ball 84 over the peaks 94 of the undulating surface 92. Other configurations for defining the torque limit may be appreciated through the present teachings.

[0131] Below the torque limit, the engagement of the balls 84 in the valleys 96 fixes the position of the ring gear 62 and prevents it from rotating. In this configuration, the planet gears 70 orbit around the sun gear 72. At and above the torque limit, the balls 84 slide over the peaks 94 and rotate the ring gear 62. In this configuration, the planet gears 70 rotate on their respective shafts 78, however, they do not orbit around the sun gear 72. The ring gear 62 orbits around the sun gear 72, rather than the planet gears orbiting around the sun gear 72.

[0132] The explanations and illustrations given herein are intended to familiarize those skilled in the art with the invention, its principles and its practical applications. Those skilled in the art may adapt and apply the invention in a variety of forms, which may best suit the requirements of a particular use.

[0133] It should be understood that the above description is intended to be illustrative rather than limiting. After reading the above description, those skilled in the art will appreciate many implementations and many applications in addition to the examples provided.

[0134] As can be seen from the accompanying claims, other combinations are possible, which are also incorporated into this written description by reference.

[0135] The scope of the invention should, therefore, be determined not with reference to the above 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.

[0136] The omission from the following claims of any aspect of the subject matter disclosed herein does not constitute a disclaimer of such subject matter and should not be regarded as an indication that the inventors did not consider such subject matter to be part of the disclosed inventive subject matter.

[0137] A single integrated element may provide multiple elements. Alternatively, a single element may be divided into separate multiple elements.

[0138] Disclosure of "a" or "an" to describe an element does not exclude other elements.

[0139] Although the term first, second, third etc. can be used herein to describe various elements, components, regions and / or parts, these elements, components, regions and / or parts should not be limited by these terms. These terms can be used to distinguish an element, component, region and / or part from another element, component, region and / or part. Unless the context clearly indicates, the terms such as "first", "second" and other numerical terms used in this article do not mean sequence or order. Therefore, without departing from this teaching, the first element, component, region and / or part discussed above or below can be referred to as the second element, component, region and / or part.

[0140] For ease of description, spatially relative terms such as "inside," "outside," "below," "below," "lower," "above," "upper," etc. may be used herein to describe the relationship of one element or feature to other elements or features, as shown in the figures. In addition to the orientations depicted in the figures, spatially relative terms may be intended to cover different orientations of the device in use or operation. For example, if the device in the figure is turned over, elements described as "below" or "below" other elements or features will be oriented to be "above" the other elements or features. Thus, the example term "below" can include orientations of above and below. The device can be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein can be interpreted accordingly.

[0141] The terms "substantially" or "substantially" used to describe angle measurements may refer to about + / - 10° or less, about + / - 5° or less, or even about + / - 1° or less. The terms "substantially" or "substantially" used to describe angle measurements may refer to about + / - 0.01° or more, about + / - 0.1° or more, or even about + / - 0.5° or more.

[0142] The use of "about" or "approximately" in connection with ranges applies to both ends of the range. Thus, "about 20 to 30" is intended to cover "about 20 to about 30", including at least the specified endpoints.

[0143] Unless otherwise stated, any numerical value described herein includes all values ​​from lower values ​​to higher values, and the increment is one unit, provided that there is at least an interval of 2 units between any lower value and any higher value. For example, if a value is specified to be, for example, 1 to 90, 20 to 80, or 30 to 70, it is meant that intermediate range values ​​(e.g., 15 to 85, 22 to 68, 43 to 51, 30 to 32, etc.) are within this teaching. For a value less than 1, a unit is considered to be 0.0001, 0.001, 0.01, or 0.1 (depending on the circumstances). These are only examples of specific intent, and all possible numerical combinations between the lowest and highest values ​​listed should be considered to be clearly stated in a similar manner in this application. Unless otherwise stated, all ranges include all numbers between two endpoints and the endpoints.

[0144] The term "consisting essentially of..." describing a combination shall include the identified elements or components as well as other elements or components that do not materially affect the basic and novel characteristics of the combination. The use of the terms "includes" or "comprising" to describe a combination of elements or components herein also encompasses embodiments consisting essentially of these elements or components.

[0145] The disclosures of all articles and references, including patent applications and publications, are incorporated herein by reference for all purposes.

[0146] Reference numerals

[0147] 10 Braking system

[0148] 12 Calipers

[0149] 14 Internal main part

[0150] 16 External body

[0151] 18 Bridge Section

[0152] 20 Main part

[0153] 22 Fingers

[0154] 24 A pair of brake pads

[0155] 26 Internal brake pad

[0156] 28 External brake pads

[0157] 30 Cylinders

[0158] 32 Piston

[0159] 34 Electromechanical Actuation System

[0160] 36 Spindle

[0161] 38 Nut

[0162] 40 Fluid

[0163] 42 Motor gear unit

[0164] 44 Motor gear unit housing

[0165] 46 Motor

[0166] 48 Torque limiter assembly

[0167] 50 Motor drive shaft

[0168] 52 Motor drive gear

[0169] 54 Helical gear

[0170] 56 Small gear

[0171] 58 Torque limiter drive gear

[0172] 60 Torque limiter drive shaft

[0173] 62 Ring gear

[0174] 64 Preload component

[0175] 66 Spring

[0176] 68 Spring retainer

[0177] 70 Planetary gear

[0178] 72 Sun gear

[0179] 74 First Plate Rack

[0180] 76 Second rack

[0181] 78 Axis

[0182] 80 Bushing

[0183] 82 Output shaft

[0184] 84 balls

[0185] 86 First Seat

[0186] 88 Second Seat Circle

[0187] 90 grooves

[0188] 92 corrugated surface

[0189] 94 Peak

[0190] 96 Valley

[0191] 98 bevel

Claims

1. A braking system, comprising: An electromechanical actuation system, the electromechanical actuation system comprising at least a first part and a second part, each part comprising: A torque limiter assembly that sets a torque limit and includes: a planetary gear set meshing with the sun gear, a ring gear meshing with the planetary gear set and comprising a first race extending circumferentially around the ring gear, a preload member including a second race extending circumferentially around the preload member; and a ball or roller engaged between the first race and the second race; wherein the first race and / or the second race comprises a series of peaks and valleys and a ramp extending between the peaks and valleys; wherein, below the torque limit, the balls or rollers engage within the valleys, causing the ring gear to remain rotationally restrained and the planetary gear sets to orbit about the sun gear; and Wherein, at and above the torque limit, the balls or rollers slide over the peaks, causing the ring gear to rotate and the planetary gear set to maintain orbital constraint.

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

3. The braking system according to claim 1 or 2, wherein: The angle at which the ball or roller travels across the ramp in the release direction may be the same as or different from the angle at which the ball or roller travels across the ramp in the apply direction.

4. A braking system according to any one of the preceding claims, wherein: The angle at which the ball or roller travels across the ramp in the release direction is approximately 2% to 25% greater than the angle at which the ball or roller travels across the ramp in the apply direction.

5. A braking system according to any one of the preceding claims, wherein: The torque limiter assembly comprises: A spring is generally circumferentially aligned with the first race and the second race and applies a force on the preload member such that the ball or roller is compressed between the preload member and the ring gear.

6. The braking system according to claim 5, wherein: The height of the peak measured from the valley at least partially determines the torque limit.

7. A braking system according to any one of the preceding claims, wherein: The peaks, the valleys, and the slopes are defined by wavy surfaces, serrated surfaces, or both.

8. A braking system according to any one of the preceding claims, wherein: Each part of the electromechanical actuation system includes: a first plate carrier engaging a first side of the planetary gear set such that orbiting of the planetary gear set causes the first plate carrier to rotate; and A second plate carrier engages a second side of the planetary gear set such that orbiting of the planetary gear set causes the second plate carrier to rotate, the second side being opposite the first side.

9. The braking system according to claim 8, wherein: The first plate carrier or the second plate carrier comprises an output shaft mechanically cooperating with a spindle; wherein the spindle cooperates with a nut as a ball screw mechanism or a normal screw mechanism; and wherein the nut engages a piston.

10. The brake system according to claim 9, wherein: Rotation of the spindle ultimately results in axial translation of the piston in an apply direction and / or a release direction.

11. A braking system according to any one of the preceding claims, wherein: The torque limit of the first portion is different from the torque limit of the second portion.

12. A braking system according to any one of the preceding claims, wherein: Both the first portion and the second portion of the electromechanical actuation system are actuated by the same motor.

13. A braking system according to any one of the preceding claims, wherein: The brake system includes a caliper including an inner body portion and an outer body portion; and wherein a bridge extends between the inner body portion and the outer body portion; and Therein, the bridge comprises one or more fingers acting on a brake pad associated with the outer body portion.

14. The braking system according to claim 13, wherein: The brake system includes two or more pistons located entirely on the inner body portion or the outer body portion, or on both the inner body portion and the outer body portion; Wherein, each of the first portion and the second portion of the electromechanical actuation system is associated with each of the two or more pistons.

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

16. An electromechanical actuation system for a vehicle brake, the electromechanical actuation system comprising: a nut and a spindle, wherein rotation of the spindle actuates the nut in an apply direction and a release direction; a motor in mechanical communication with the spindle; and a torque limiter assembly mechanically disposed downstream of the motor and mechanically disposed upstream of the spindle; Therein, the torque limiter assembly is set to a torque limit below which rotational motion is transmitted to the spindle and above which rotational motion cannot be transmitted to the spindle.

17. The electromechanical actuation system of claim 16, wherein: The torque limiter assembly is a ball and pawl type torque limiter.

18. An electromechanical actuation system according to claim 16 or 17, wherein: The torque limiter assembly includes 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; wherein, below the torque limit, the ring gear remains rotationally constrained and the planetary gear sets orbit around the sun gear; and Wherein, at and above the torque limit, the ring gear rotates and the planetary gear set maintains orbital constraint.

19. An electromechanical actuation system according to any one of claims 16 to 18, wherein: The gear ring includes a seat ring having a series of peaks and valleys and a ramp extending between the peaks and valleys; and the electromechanical actuation system includes a ball or roller engaged with the seat ring; wherein, below the torque limit, the ball or roller engages within the valleys; and wherein, at and above the torque limit, the ball or roller slides over the peaks.

20. An electromechanical actuation system according to any one of claims 16 to 19, wherein: The electromechanical actuation system includes two or more parts, each part being associated with a separate piston to engage the brake pad; And wherein each section is provided with said torque limiter assembly.

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