Brake with integrated motor position sensor

Abstract

A brake includes a rotor rotatably coupled to a rotating body for rotation about an axis of rotation. The brake plate and the armature are arranged on opposite sides of the rotor. The spring and electromagnet urge the armature into and out of engagement with the rotor in opposite directions, thereby moving the rotor into and out of engagement with the brake plate and engaging and disengaging the brake. The brake disc and the electromagnet each define a central bore configured to receive the rotating body. The brake features a target supported on a radially extending face of the rotating body or rotor and a sensor aligned with the target through a central bore of the brake plate or electromagnet. A sensor generates a position signal indicative of a rotational position of the rotor and the rotating body in response to the target.

Description

Technical Field

[0001] The present disclosure relates to a brake for inhibiting the rotation of a rotating body, such as a motor output shaft, etc. In particular, the present disclosure relates to a brake integrated with a sensor assembly for determining the rotational position of the rotating body. Background Art

[0002] Brakes are often used to control the rotation of a driven body, such as a motor output shaft. In many applications, it is important to also monitor the position of the motor output shaft. The position is typically monitored using a resolver or rotary encoder having a wheel coupled to the motor output shaft and a position sensor that tracks the movement of the wheel as it rotates with the motor output shaft. However, conventional resolvers and encoders consume valuable space. When an encoder is used in combination with a brake, the encoder's wheel is typically spaced axially from the brake, requiring a relatively long motor output shaft to accommodate both the brake and the encoder.

[0003] The inventors herein have recognized a need for a brake that would minimize and / or eliminate one or more of the above-mentioned deficiencies. Summary of the invention

[0004] The present disclosure relates to a brake for inhibiting the rotation of a rotating body, such as a motor output shaft, etc. In particular, the present disclosure relates to a brake integrated with a sensor assembly for determining the rotational position of the rotating body.

[0005] A brake according to one embodiment includes a rotor configured to be coupled to a rotating body for rotating with the rotating body around an axis of rotation. An annular brake plate is disposed on a first side of the rotor around the axis of rotation and defines a central hole configured to receive the rotating body. An armature is disposed on a second side of the rotor around the axis of rotation. A spring is configured to push the armature toward the rotor and engage with the rotor in a first axial direction, thereby pushing the rotor toward the brake plate and engaging with the brake plate in a first axial direction, thereby braking the rotation of the rotor and the rotating body. An annular electromagnet is disposed on the opposite side of the armature relative to the rotor and defines a central hole configured to receive the rotating body. The electromagnet is configured to push the armature away from the rotor in a second axial direction and disengage from the rotor when current is delivered to the electromagnet. The brake is characterized in that a target is supported on a radially extending surface of one of the rotating body and the rotor and a sensor aligned with the target through one of the central holes of the brake plate and the central holes of the electromagnet and configured to generate a position signal indicating the rotational position of the rotor and the rotating body in response to the target.

[0006] A brake according to the present teachings is advantageous relative to conventional brakes. The brake integrates a sensor assembly in a relatively compact manner in the direction of the axis of rotation of a rotating body, such as a motor output shaft, etc. As a result, the brake allows the rotational position of the motor output shaft to be determined without substantially increasing the axial length of the motor output shaft.

[0007] The foregoing and other aspects, features, details, utilities and advantages of the present invention will become apparent from reading the following detailed description and claims and from reviewing the accompanying drawings which illustrate by way of example the features of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1-Figure 2 is an exploded perspective view of a brake according to one embodiment of the present teachings.

[0009] Figure 3 yes Figure 1-Figure 2 Cross-sectional view of the brake.

[0010] Figure 4 yes Figure 1-Figure 3 An enlarged cross-sectional view of a portion of a brake.

[0011] Figure 5-Figure 6 is an exploded perspective view of a brake according to another embodiment of the present teachings.

[0012] Figure 7 yes Figure 5-Figure 6 Cross-sectional view of the brake.

[0013] Figure 8-Figure 9 is an exploded perspective view of a brake according to another embodiment of the present teachings.

[0014] Fig.10 yes Figure 8-Figure 9 Cross-sectional view of the brake.

[0015] Fig.11 yes Figure 8-Figure 10 An enlarged cross-sectional view of a portion of a brake.

[0016] Figure 12-13 is an exploded perspective view of a brake according to another embodiment of the present teachings.

[0017] Fig.14 yes Figure 12-13 Cross-sectional view of the brake.

[0018] Fig.15 yes Figure 12-14 An enlarged cross-sectional view of a portion of a brake.

[0019] Fig.16is a cross-sectional view of a brake according to another embodiment of the present teachings.

[0020] Fig.17 yes Fig.16 An enlarged cross-sectional view of a portion of a brake.

[0021] Fig.18 is a cross-sectional view of a brake according to another embodiment of the present teachings.

[0022] Fig.19 yes Fig.18 An enlarged cross-sectional view of a portion of a brake. DETAILED DESCRIPTION

[0023] Referring now to the drawings, wherein like reference numerals are used to identify like parts throughout the several views, Figure 1-Figure 4 A brake 20 according to one embodiment of the present invention is shown. Figure 3 , a brake 20 is provided to generate a braking torque on a rotating body 22 such as a shaft, gear, pulley, blade, etc., so as to slow down or stop the rotation of the body 22 (i.e., a service brake) or prevent the rotation of the body 22 about the axis of rotation 24 (i.e., an emergency brake). It will be understood by those of ordinary skill in the art that the brake 20 can be used in various industrial and other applications where a brake is required. The body 22 can be solid or tubular. The body 22 can be driven by an electric motor, an engine, or other conventional power source (not shown). In the illustrated embodiment, the body 22 includes a radially extending flange 26 near one axial end of the body 22, which can include, for example, a gear configured to engage with another gear or a pulley configured to receive a belt or chain. The brake 20 can include a rotor 28, a brake plate 30, a spacer 32, an armature 34, a spring 36, and an electromagnet 38. According to the teachings herein, the brake 20 further includes a sensor assembly 40 for generating an indication of the rotational position of the body 22 and the rotor 28.

[0024] The rotor 28 is provided for selective engagement with the brake plate 30 and the armature 34 to transmit the braking torque to the body 22. The rotor 28 can be made of a variety of conventional materials including plastics and can be made by stamping, molding and / or machining. The rotor 28 is arranged about the axis 24 and can be centered about the axis 24 and coupled to the body 22 to rotate therewith about the axis 24. The rotor 28 can include a hub 42 and a rotor or coupling disc 44.

[0025] The hub 42 is tubular and defines a central bore into which the body 22 extends. Figure 2, the hub 42 may define an axially extending keyway 46 shaped to be complementary to a key (not shown) and configured to receive a key formed or received in a corresponding keyway of the body 22. Alternatively, the hub 42 may be shaped to have an integral, radially extending key configured to be received in a keyway in the body 22. The hub 42 defines a plurality of axially extending splines 48 on a radially outer surface for purposes described below.

[0026] The disk 44 is supported on the hub 42 and extends radially outward from the hub 42. The disk 44 is tubular and defines a central bore configured to receive the hub 42 and the body 22. The radially inner surface of the disk 44 may define a plurality of axially extending splines 50 configured to engage with the splines 48 of the hub 42 to prevent relative rotation of the hub 42 and the disk 44, but to allow the disk 44 to move axially relative to the hub 42 along the axis 24. See Figure 3 The radially outer portion of the disk 44 is configured to be axially received between the brake plate 30 and the armature 34 and defines an engagement surface on either axial side that is configured to engage the brake plate 30 and the armature 34. Each engagement surface of the disk 44 may support one or more friction pads 52 made of conventional friction material.

[0027] The brake plate 30 is configured to engage the rotor 28 during application of the brake 20 to transmit braking torque to the rotor 28. The brake plate 30 provides a reaction surface against which the armature 34 is pressed against the rotor 28 during application of the brake 20. The brake plate 30 can be made of conventional metal, plastic, or composite materials. The brake plate 30 is annular and can be disposed about the axis 24 and centered about the axis 24. The brake plate 30 defines a central hole 54 that is configured to receive a portion of the hub 42 of the body 22 and the rotor 28. See Figure 1 The brake plate 30 further defines a plurality of fastener holes 56 configured to receive fasteners 58, such as bolts, pins, screws, etc., extending therethrough for coupling the brake plate 30 to the electromagnet 38 and securing the brake plate 30 against rotation. One axial side of the brake plate 30 faces the rotor 28 and defines a brake engagement surface configured to engage the rotor 28 during application of the brake 20. The other axial side of the brake plate 30 defines an annular recess 60 surrounding the central hole 54 and configured to receive components of the sensor assembly 40, as discussed in more detail below.

[0028] The spacers 32 establish the axial spacing of the brake plate 30 and the electromagnet 38. The spacers 32 engage the opposing faces of the brake plate 30 and the electromagnet 39. The spacers 30 are tubular in shape and are configured to receive fasteners 58 extending from the brake plate 30 into the electromagnet 38. The axial length of each spacer 32 is greater than the combined axial length of the armature 34 and the disc 44 so that when the brake 20 is disengaged, there is an air gap between the brake plate 30 and the disc 44 and between the armature 34 and the disc 44. During the life of the brake 20, the axial spacing of the brake plate 30 and the electromagnet 38 can be adjusted using spacers 32 with different lengths to compensate for wear on the brake engagement surfaces of the brake plate 30, the armature 34 and the disc 44, and to result in an increase in the air gap between the brake plate 30 and the disc 44 and the armature 34 and the disc 44. The spacer 32 may be made of a material or materials, including non-magnetic materials, that have a relatively high magnetic reluctance to eliminate flux transfer from the electromagnet 38 to the brake plate 30 .

[0029] The armature 34 is configured to engage with the rotor 28 during the application of the brake 20 to transmit the braking torque to the rotor 28. The armature 34 can be made of a metal or metal alloy or other material with relatively low magnetic resistance (such as iron or steel, etc.). The armature 34 is annular in shape and can be arranged around the axis 24 and can be centered around the axis 24. The armature 34 is arranged on a side of the disk 44 opposite to the brake plate 30 and defines a brake engagement surface facing the disk 44. The armature 34 can move axially toward and away from the disk 44 and the brake plate 30 to allow engagement and disengagement of the brake 20. The armature 34 can define a plurality of recesses 62 in a radially outer surface or a hole extending through the armature 34, and the plurality of recesses 62 are configured to receive the spacer 32 and the fastener 58, thereby fixing the armature 34 to prevent rotation relative to the brake plate 30 and the electromagnet 38.

[0030] The spring 36 provides a means for biasing the armature 34 in one direction along the axis 24 toward the rotor 28 and the brake plate 30 and away from the electromagnet 38 to engage the brake 20. The spring 36 is seated between the armature 34 and the electromagnet 38 and exerts a biasing force on the armature 34, thereby urging the armature 34 and the rotor 28 toward the brake plate 30. The springs 36 can be received in recesses formed in the electromagnet 38 and arranged in an annular array around the axis 24 and circumferentially spaced equally around the axis 24. It should be understood that the brake 20 may alternatively include a single annular spring 36 in a corresponding annular recess in the electromagnet 38.

[0031] The electromagnet 38 provides a means for urging the armature 34 away from the disk 44 and the brake plate 30 in opposite directions along the axis 24 to disengage the brake 20. The electromagnet 38 also provides structural support and orients the other components of the brake 20, including the brake plate 30 and the spring 36. Figure 3 The electromagnet 38 is arranged on a side of the armature 34 opposite the disk 44 and includes a housing 64 or field shell and a conductor 66 .

[0032] The housing 64 is configured to house the conductor 66 and may also provide structural support and orientation for other components of the brake 20 including the brake plate 30 and the spring 36. The housing 64 also forms part of an electromagnetic circuit that attracts the armature 34 toward the housing 64 when current is provided to the conductor 66. The housing 64 may be made of a metal or metal alloy or other material having a relatively low magnetic resistance, such as iron or steel, etc. The housing 64 is fixed to prevent rotation. The housing 64 is annular in shape and may be arranged about the axis 24 and may be centered about the axis 24. The housing 64 defines a central hole 68 through which a portion of the body 22 and the rotor 28 may extend. The housing 64 may define a radially extending end wall 70 and an axially extending radially aligned inner wall 72 and outer wall 74 extending axially from the end wall 70 toward the armature 34. The inner wall 72 and the outer wall 74 define an annular recess therebetween that is configured to receive the conductor 66. The inner wall 72 may also define one or more closed holes configured to receive one end of each spring 36. The outer wall 74 may also define a plurality of circumferentially spaced closed holes configured to receive the fasteners 58 coupling the brake plate 30 to the electromagnet 38.

[0033] A conductor 66 is provided to create an electromagnetic circuit between the armature 34, the housing 64, and the conductor 66 to cause movement of the armature 34 away from the disk 44, thereby disengaging the brake 20. The conductor 66 may include a conventional wound coil or similar conductor configured to be received within the housing 64 between the walls 72, 74. The conductor 66 may be electrically connected to a power source (not shown), such as a battery or the like. The current provided to the conductor 66 creates an electromagnetic circuit including the armature 34, the housing 64, and the conductor 66, which pushes the armature 34 toward the housing 64 and away from the disk 44 to disengage the brake 20 against the biasing force of the spring 36.

[0034] According to the teachings herein, brake 20 further includes an integrated sensor assembly 40. Assembly 40 provides an indication of the rotational position of body 22 and rotor 28 and may be a resolver or an absolute or incremental rotary encoder. Figure 1-Figure 4, the assembly 40 may include a target member 76 , a sensor housing 78 , a printed circuit board 80 , and a sensor 82 configured to generate a position signal indicative of the rotational position of the body 22 and the rotor 28 in response to the target member 76 .

[0035] Target 76 causes sensor 82 to generate a signal indicative of the rotational position of body 22 and rotor 28. Figure 1 and Figure 4 , the target member 76 is supported on a radially extending face of the rotor 28, in particular, the hub 42 of the rotor 28. The target member 76 may include a thin plate made of metal (e.g., copper or aluminum) that is fixed to a face of the rotor 28 that is overmolded onto the rotor 28 (e.g., using an adhesive). The target member 76 must be made of a different material than the rotor 28 to enable the target member 76 to be detected by the sensor 82. The target member 76 may be partially disposed within the central hole 54 of the brake disc 30. See Figure 1 , the target member 76 may extend on a circumferential arc around a portion of the rotor 28 and the axis 24. In the illustrated embodiment, the target member 76 is semicircular in shape, extending over half of the circumference of the rotor 28 and, in particular, the hub 42.

[0036] See also Figure 1-Figure 2 , a sensor housing 78 is provided to protect the PCB 80 and sensor 82 from foreign objects and elements and to position and orient the PCB 80 and sensor 82 within the brake 20. In the illustrated embodiment, the housing 78 is annular in shape. However, it should be understood that the shape of the housing 78 may vary. The housing 78 may be arranged about the axis 24 and centered about the axis 24. See Figure 2 , the housing 78 includes an end wall 84 and inner and outer circumferential walls 86, 88 that project axially from the radially innermost edge and radially outermost edge of the end wall 84. The walls 84, 86, 88 together define a recess 90 that is configured to receive the PCB 80 and the sensor 82. One or more openings in the wall 88 can form an electrical connection between the PCB 80 and external electronic devices, including, for example, a controller (e.g., a motor controller), a visual display or other user interface element, and / or a monitoring device.

[0037] PCB 80 supports sensor 82. PCB 80 may further support other electronic circuit elements, including those used in pre-processing (e.g., amplification, conditioning, etc.) of signals generated by sensor 82 prior to transmission to external electronic devices. In the illustrated embodiment, PCB 80 is annular in shape. However, it should be understood that the shape of PCB 80 may vary. PCB 80 may define a central hole that is arranged about axis 24 and centered on axis 24 and is configured to receive body 22 therethrough. PCB 80 is configured to be received within recess 90 in sensor housing 78. See Figure 1 , the PCB 80 and sensor housing 78 may be further configured to be received within the recess 60 of the brake plate 30 to further protect the PCB 80 and sensor 82 from foreign objects and elements.

[0038] The sensor 82 generates a signal indicative of the rotational position of the body 22 and the rotor 28 in response to the target 76. The sensor 82 is supported on the PCB 80. In one embodiment, the sensor 82 comprises an inductive sensor including three coils printed as copper traces on the PCB 80. The coils include a transmitter coil and two receiver coils. The transmitter coil induces a voltage in the receiver coil, thereby generating a magnetic field that induces eddy currents in the target 76, thereby generating another magnetic field that interacts with the magnetic field generated by the coil (in an embodiment using an inductive sensor, the rotor 28 must be formed of a non-metallic material so that the rotor 28 does not affect the generated field). The interacting magnetic fields cause changes in the induced voltage in the receiver coil, which depends on the position and movement of the target 76. Although an inductive sensor is described herein, it should be understood that different types of optical sensors and magnetic sensors may be used (which in turn may result in different configurations of the target 76). The coil of the sensor 82 extends circumferentially around at least a portion of the PCB 80 and the axis 24, and in some embodiments, may completely surround the axis 24, so that the shape of the sensor 82 is annular. Sensor 82 is axially spaced from target 76 and aligned with target 76 through central aperture 54 of brake disc 30. The arrangement and positioning of target 76 and sensor 82 enables sensor assembly 40 to minimize the axial space required for assembly 40 and, therefore, the axial length of body 22.

[0039] See now Figure 5-Figure 7 , illustrates a brake 120 according to another embodiment of the present invention. The brake 120 is substantially similar to the brake 20, and similar reference numerals are used to identify similar components. The brake 120 differs from the brake 20 in that the rotor 128 does not include a separate hub and disc, but is an integral (one-piece) body. The rotor 128 includes a hub portion 142 and a disc portion 144.

[0040] See also Figure 7 , the hub portion 142 is tubular and defines a central bore into which the driven body 122 extends. Figure 5-Figure 6 The hub portion 142 may define a plurality of axially extending splines 150 configured to engage corresponding splines on the body 122 to prevent relative rotation of the rotor 128 and the body 122 , but to allow the rotor 128 to move axially relative to the body 122 along the axis 24 .

[0041] The disc portion 144 extends radially outward from the hub portion 142. The disc portion 144 is configured to be received axially between the brake plate 30 and the armature 34, and defines engagement surfaces on either axial side that are configured to engage with the brake plate 30 and the armature 34. Each engagement surface of the disc portion 142 may support one or more friction pads made of conventional friction material.

[0042] See also Figure 5 , the target member 76 is supported on a radially extending face of the hub portion 142 of the rotor 128. The target member 76 may again extend on a circumferential arc around a portion of the rotor 128 and the axis 24, and in the illustrated embodiment, the target member 76 is semicircular in shape, extending over half of the circumference of the hub portion 142 of the rotor 128. See Figure 7 , the target member 76 may be disposed within the central bore 54 of the brake disc 30. The sensor 82 is axially spaced from the target member 76 and aligned with the target member 76 through the central bore 54 of the brake disc 30. Again, the arrangement and positioning of the target member 76 and the sensor 82 results in a sensor assembly 40 that minimizes the axial space required for the assembly 40, and therefore minimizes the axial length of the body 22.

[0043] See now Figure 8-Figure 11 , illustrates a brake 220 according to another embodiment of the present invention. The brake 220 is substantially similar to the brake 20, and similar reference numerals are used to identify similar components. The brake 220 differs from the brake 20 in that the sensor assembly 40 is located on the opposite axial side of the brake 220 relative to the brake 20. See Fig. 9 and Fig.11, the target member 76 of the assembly 40 is again supported on a radially extending face of the rotor 228 (including the hub 242 and the disk 244), particularly the hub 242 of the rotor 228, but the face is located at the opposite axial end of the hub 242 relative to the brake 20 and can be at least partially disposed within the central bore 68 of the electromagnet 38. The sensor housing 78, PCB 80, and sensor 82 are configured to engage with the electromagnet 38, rather than the brake plate 30 in the brake 20. Although not shown in the illustrated embodiment, the electromagnet 38 can define a recess similar to the recess 60 in the brake plate 30 of the brake 20, which is configured to receive the sensor housing 78, PCB 80, and sensor 82. The sensor 82 is axially spaced from the target member 76 and is aligned with the target member 76 through the central bore 68 of the electromagnet 38. The arrangement and positioning of the target member 76 and the sensor 82 again produces a sensor assembly 40 that minimizes the axial space required for the assembly 40 and the axial length of the body 22.

[0044] See now Figure 12-Figure 15 , illustrates a brake 320 according to another embodiment of the present invention. The brake 320 is substantially similar to the brake 220, and similar reference numerals are used to identify similar components. The brake 320 differs from the brake 220 in that the rotor 328 does not include a spaced-apart hub and a disc, but is an integral (one-piece) body. The rotor 328 includes a hub portion 342 and a disc portion 344.

[0045] See also Fig.14 , the hub portion 342 is tubular and defines a central bore into which the driven body 22 extends. Figure 12-13 The hub portion 342 may define a plurality of axially extending splines 350 configured to engage with corresponding splines on the body 22 to prevent relative rotation of the rotor 328 and the body 22 but to allow axial movement of the rotor 328 relative to the body 22 along the axis 24.

[0046] The disc portion 344 extends radially outward from the hub portion 342. The disc portion 344 is configured to be received axially between the brake plate 30 and the armature 34 and defines engagement surfaces on either axial side that are configured to engage with the brake plate 30 and the armature 34. Each engagement surface of the disc portion 342 may support one or more friction pads made of conventional friction material.

[0047] See also Fig.12, the target member 76 is supported on a radially extending face of the hub portion 342 of the rotor 328. The target member 76 may again extend on a circumferential arc around a portion of the rotor 328 and the axis 24, and in the illustrated embodiment, the target member 76 is semicircular in shape, extending over half of the circumference of the hub portion 342 of the rotor 328. See Fig.14 , the target member 76 may be disposed within the central bore 68 of the electromagnet 38. The sensor 82 is axially spaced from the target member 76 and aligned with the target member 76 through the central bore 68 of the electromagnet 38. Again, the arrangement and positioning of the target member 76 and the sensor 82 produces a sensor assembly 40 that minimizes the axial space required for the assembly 40, and therefore minimizes the axial length of the body 22.

[0048] See now Figure 16-Figure 17 , illustrates a brake 420 according to another embodiment of the present invention. The brake 420 is substantially similar to the other brakes 20 discussed above, and similar reference numerals are again used to identify similar components. The brake 420 differs from the brake 20 in that the rotor 428 is an integral (one-piece) body similar to the rotor 228 of the brake 220 discussed above (however, it should be understood that the rotor 428 may alternatively include a spaced-apart hub and a disk, as in other embodiments discussed herein), and the target member 76 is supported on a driven body 422 rather than on the rotor 428. In particular, the body 422 is configured to define a radially extending face on which the target member 76 is supported. The body 422 includes a reduced diameter portion extending through the sensor housing 78 and the PCB 80 and into the central hole 54 of the pressure plate 30 and an increased diameter portion extending from the reduced diameter portion and the central hole 54 of the pressure plate 30 and into the central hole of the rotor 428. The increased diameter portion defines a radially extending surface at one axial end that faces the sensor 82 and is configured to support the target member 76. Again, the arrangement and positioning of the target member 76 and the sensor 82 produces a sensor assembly 40 that minimizes the axial space required for the assembly 40 and, therefore, minimizes the axial length of the body 22.

[0049] See now Figure 18-Figure 19, illustrates a brake 520 according to another embodiment of the present invention. The brake 520 is substantially similar to the brake 420 described above, and the same reference numerals are again used to identify similar components. The brake 520 differs from the brake 420 in that the sensor assembly 40 is located on the opposite axial side of the brake 520 relative to the brake 420. In particular, while the target member 76 is again supported on the driven body 522 (opposite the rotor 528), the target member 76 is supported on radially extending faces formed on or near opposite ends of the body 522 and may be at least partially disposed within the central bore 68 of the electromagnet 38 (although in the illustrated embodiment the target member 76 is supported on axial ends of the body 522, it should be understood that the body 522 may again be configured with sections of varying diameters as in the brake 422 such that the target member 76 is supported on radially extending faces formed between axial ends of the body 522). As in the brakes 220, 320, the sensor assembly 40 is located adjacent the electromagnet 38. Moreover, although not shown in the illustrated embodiment, the electromagnet 38 may define a recess similar to the recess 60 in the brake plate 30 of the brake 20 that is configured to receive the sensor housing 78, the PCB 80, and the sensor 82.

[0050] The brake 20, 120, 220, 320, 420 or 520 according to the teachings of the present invention is advantageous relative to conventional brakes. The brake 20, 120, 220, 320, 420 or 520 integrates the sensor assembly 40 in a relatively compact manner in the direction of the rotation axis 24 of a rotating body such as a motor output shaft. Therefore, the brake 20, 120, 220, 320, 420 or 520 allows the rotational position of the motor output shaft to be determined without significantly increasing the axial length of the motor output shaft.

[0051] While the invention has been shown and described with reference to one or more specific embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims

1. A brake, comprising: a rotor configured to be coupled to the rotating body for rotating together with the rotating body about a rotation axis; an annular brake plate disposed on a first side of the rotor about the rotational axis and defining a central aperture configured to receive the rotating body; an armature disposed on a second side of the rotor about the rotation axis; a spring configured to urge the armature toward the rotor in a first axial direction and engage with the rotor, thereby urging the rotor toward the brake plate in the first axial direction and engaging with the brake plate, thereby braking rotation of the rotor and the rotating body; an annular electromagnet disposed on an opposite side of the armature relative to the rotor and defining a central bore configured to receive the rotating body, the electromagnet configured to urge the armature away from and out of engagement with the rotor in a second axial direction when current is passed to the electromagnet; Features: a target part supported on a radially extending surface of one of the rotating body and the rotor; as well as, A sensor is aligned with the target through one of the central hole of the brake plate and the central hole of the electromagnet and is configured to generate a position signal indicative of a rotational position of the rotor and the rotating body in response to the target.

2. The brake according to claim 1, wherein: The target is at least partially disposed within one of the central aperture of the brake plate and the central aperture of the electromagnet.

3. The brake according to any one of claims 1 to 2, wherein: The radially extending surface is located on the rotor, and the sensor is aligned with the target through the central hole of the brake plate.

4. The brake according to any one of claims 1 to 2, wherein: The radially extending surface is located on the rotating body, and the sensor is aligned with the target through the central hole of the brake plate.

5. The brake according to any one of claims 1 to 2, wherein: The radially extending surface is located on the rotor, and the sensor is aligned with the target through the central hole of the electromagnet.

6. The brake according to any one of claims 1 to 2, wherein: The radially extending surface is located on the rotating body, and the sensor is aligned with the target through the central hole of the electromagnet.

7. The brake according to any one of claims 1 to 2, wherein: The rotor includes a first portion configured to engage a first side of the brake plate and a second portion extending into one of a central hole of the brake plate and a central hole of the electromagnet and supporting the target.

8. The brake according to any one of claims 1 to 2, wherein: The brake plate defines a recess on a side of the brake plate opposite the rotor, and the recess surrounds a central hole of the brake plate, and the sensor is supported on a printed circuit board received within the recess.

9. The brake according to claim 8, wherein: The printed circuit board defines a central hole disposed about the rotational axis.

10. The brake according to claim 8, wherein: The printed circuit board is configured to receive the rotating body therethrough.

11. The brake according to any one of claims 1 to 2, wherein: The target extends circumferentially around a portion of the rotational axis.

12. The brake according to any one of claims 1 to 2, wherein: The target piece is semicircular in shape.

13. The brake according to any one of claims 1 to 2, wherein: The sensor extends circumferentially around a portion of the rotational axis.

14. The brake according to any one of claims 1 to 2, wherein: The sensor is annular in shape.

15. The brake according to any one of claims 1 to 2, wherein: The sensor is axially spaced from the target.

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