DESC:FIELD OF INVENTION
[0001] The present invention generally relates to the field of brush electric motors, and more particularly to a brush assembly for detecting remaining life of a motor and alarming the user after a pre-determined life of the motor is consumed.
BACKGROUND OF THE INVENTION
[0002] Electric brush motors are known to be used for several years in different industrial fields. A brush direct current motor, as shown in Figs. 1A, 1B, 1C and 1D, typically comprises a stator, a rotor, a plurality of commutation segments connected to the rotor, and an end-cap with a plurality of carbon-graphite brushes. The brushes, as shown in Fig. 1D are used for electrical connection between the terminal and the commutation segments such that when the voltage is applied through the motor terminals which is electrically connected with the brushes, the electric circuit is completed through the collector segments which are connected to the rotor coil loops. A precious metal equivalent brush direct current motor is shown in Figs. 2A, 2B, 2C and 2D. As shown in Fig. 2D, the electrical contact between motor terminal and each winding segments is achieved through finger brushes comprising of specific precious metal material. The design of the motor is such that due to the odd number of collectors, there is an imbalance created between the two halves of the rotor, and the rotor rotates to compensate that imbalance. As a result of the rotation, the brush pair slides over the collector segments and connects with an adjacent segment, creating the imbalance again. Hence, the rotor keeps rotating, following the imbalance which is created in the circuit. The segments are attached to different rotor windings; therefore, a dynamic magnetic field is generated inside the motor when a voltage is applied across the brushes of the motor. However, due to mechanical friction between sliding contacts and electro-erosion caused by the voltage sparks taking place at the time of contact and separation of brushes and commutation segments, the brushes and commutator segments wear out over time, which eventually leads to failure of the motor with deterioration of the electrical contacts beyond a certain level. Further, in such motors, the end-cap is placed on the commutation segments in such a way that the brush, collectors and all the sub-systems are enclosed in a housing and are therefore not visible. As a result, the wear of the brushes cannot be seen from the outside. Moreover, miniature motors in sub-kW ranges are often placed inside the device using it. Hence, even if the brush design is altered, it would not be feasible to physically see the brushes in such devices. In large systems. employing more than few motors, it becomes critical to keep a centralized condition monitoring system which may detect the wear/failure of the motor based on the inputs from sensors mounted in the devices.
[0003] In large motors, several ways are known to measure wear rates by using specific sensors and electronics set as a part of the condition monitoring system. However, such monitoring techniques are generally costly and require large space to accommodate the complete measurement system, and therefore cannot be efficiently implemented in small sized motors. For instance, some of the large motors use strain gauges to measure the brush pressure over time and predict the near-end-of-life by observing the strain on these gauges. However, the solution is not reliable as change in temperature and EMI/EMC interference contributes to bridge imbalance and a full bridge is needed for compensation. Therefore, the techniques as known are only suitable for large sized motors and cannot be efficiently used for small sized motors. Miniature motors also do not allow for a larger spaces to package such mechanism and electronics.
[0004] Small sized motors such as miniature motors have various applications in fields such as medical, aerospace, robotics etc. The manufacturing of such electric motors is customized to various levels depending on application needs and customer demands. However, in addition to customization, product reliability in such motors, especially in such important fields of technology becomes very important. For example, in the surgical field, the device or instrument at all cost and means, should never fail while being used for surgery. Such requirements mandate condition monitoring of the motors used in the device and detect the possibility of failure, so that before the motor reaches its end-life, the user can replace/rectify the motor. Such replacements can be done as a preventive maintenance and without a long downtime of the application. However, due to space limitations in the end-cap assembly of the small sized motors, active monitoring of the brush/collector life has proven very difficult, expensive and unreliable in the past.
[0005] In view of the foregoing, there is a need for techniques that are capable of predicting actual remaining life of a brush of a motor and generating a trigger indicating early failure of the motor so that appropriate replacement/repair can be done or any other user dependent actions can be taken up well before the motor actually fails.
OBJECTS OF THE INVENTION
[0006] It is an object of the present invention to provide techniques that are capable of predicting the life of the motor by ascertaining whether a brush or collector has worn out to a pre-determined level.
[0007] It is another object of the present invention to provide a brush assembly for a motor that is capable of triggering an alarm to a user when a pre- determined level of wear of the motor has taken place.
[0008] It is yet another object of the present invention to provide a brush assembly for a motor that enables the user to be aware of the remaining life of the motor for timely replacement and/or repair of the motor or the brushes.
[0009] It is still another object of the present invention to provide a brush assembly for a motor that improves maintainability and reparability of the applications in which such motors are used.
[0010] It is yet another object of the present invention to provide a brush assembly for a motor capable of reducing down time of the motor.
[0011] It is yet another object of the present invention to provide a brush assembly for a motor that improves reliability of the motor and prevents the potential application failure.
SUMMARY OF THE INVENTION
[0012] An aspect of the present invention relates to a brush assembly for an electric brush motor for detecting remaining life of a motor and alarming the user after a pre-determined wear of the motor has taken place. The brush assembly includes a plurality of brushes adapted to conduct electrical current between at least one commutator segment of a rotor and a terminal of said motor, and a detector pin operatively coupled with a casing of said motor, said detector pin being adapted to trigger a signal when a pre-determined level of wear of any or a combination of at least one of the plurality of brushes and said at least one commutator segment is detected, wherein each of said plurality of brushes is attached to at least one extension, said at least one extension extends to said terminal of said motor, such that when a pre-determined level of wear of any or a combination of at least one of said plurality of brushes and said at least one commutator segment is reached, said at least one extension comes in contact with said detector pin to trigger the signal indicating the wear of any or a combination of said at least one of said plurality of brushes and said at least one commutator segment.
[0013] In an embodiment, the brush assembly includes at least one additional extension on the brushes such that when the pre-determined level of wear of any or a combination of at least one of the plurality of brushes and the at least one commutator segment is reached, the additional extension comes in contact with the detector pin to trigger a signal indicating the wear of said at least one of said plurality of brushes. The extension in such embodiment can be designed in such a way that the deflection on the free end of such extension touches the detector pin after certain level of wear has occurred between the brush-collector assembly. This embodiment is applicable to carbon -graphite or precious metal or any other brush systems.
[0014] In an embodiment, the detector pin allows the brush to move forward and conduct electrical current between the terminal and the at least one commutator segment of the rotor, even when the pre-determined level of wear is reached by allowing at least one extension to slide on the detector pin, thereby triggering the signal without affecting the functioning of the motor.
[0015] Another aspect of the invention relates to a brush assembly for an electric brush motor that includes a plurality of brushes adapted to conduct electrical current between at least one commutator segment of a rotor and a terminal of said motor, and a detector pin operatively coupled with a casing of the motor, said detector pin being adapted to trigger a signal when a pre-determined level of wear of any or a combination of said plurality of brushes and said at least one commutator segment is detected, wherein each of said plurality of brushes is connected to a spring having an extension by means of a conductive plate, such that when the pre-determined level of wear of any or a combination of at least one brush and said at least one collector segment is reached, the spring gets disconnected from the at least one brush, and an open electric circuit is formed between said spring and the at least one brush to which said spring is connected, thereby triggering the signal indicating wear of any or a combination of said at least one of said plurality of brushes and said at least one commutator segment.
[0016] In an embodiment, said plurality of brushes are in contact with an input terminal of said motor, and said spring is in contact with an outer terminal of said motor.
[0017] Another aspect of the present invention relates to a brush assembly for an electric brush motor, comprising a plurality of brushes, each brush of said plurality of brushes pivoted on a pivot axis and adapted to conduct electrical current between at least one commutator segment of a rotor and a terminal of said motor, and at least one spring with an extension in contact with each of said plurality of brushes, adapted to push each of said plurality of brushes towards the said at least one collector segment, wherein an insulated portion is provided on at least one brush of said plurality of brushes after a pre-determined length of said at least one brush, such that when a pre-determined level of wear of any or a combination of said at least one brush and said at least one commutator segment is reached, said spring comes in contact with said insulated portion to generate a trigger indicating early failure detection of said motor.
[0018] In an embodiment, when said at least one brush starts to wear out, the contact between said spring and said at least one brush shifts towards the pivot axis of said at least one brush.
[0019] In an embodiment, the plurality of brushes comprises any or a combination of hammer design or torsion design of carbon brushes, precious metal brushes having finger like projections or any other combination thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0021] In the figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.
[0022] Figs. 1A and 1B illustrate various perspective representations of a typical brushed Direct Current (DC) motor with a carbon brush commutation system;
[0023] Figs. 1C and 1D illustrates a typical brush used for electrical connection between the terminal and commutation segments of the motor for carbon brush designs;
[0024] Figs. 2A and 2B illustrate various perspective representations of a typical brushed Direct Current (DC) motor with a precious metal finger brush commutation system;
[0025] Fig. 2C and 2D illustrates a typical brush used for electrical connection between the terminal and commutation segments of the motor for precious metal designs;
[0026] Figs. 3A through 3C illustrate exemplary representations of the brush assembly of a brush DC motor, in accordance with an embodiment of the present invention for carbon brush design;
[0027] Fig 3D illustrates an exemplary representation showing the condition when the carbon brush wear has reached predetermined level and the extensions on the brush touches the detector pin, in accordance with an embodiment of the present invention;
[0028] Figs. 4A through 4C illustrate exemplary representations of the brush assembly incorporating a spring actuated mechanism for detection of wear in precious metal brushes, in accordance with an embodiment of the present invention;
[0029] Fig 4D illustrates an exemplary representation showing the condition when the precious metal brush wear has reached predetermined level and the extensions on the brush touches the detector pin, in accordance with an embodiment of the present invention;
[0030] Figs. 5A through 5C illustrate exemplary representations of the brush assembly incorporating the spring actuated mechanism for detection of wear in hammer design brushes, in accordance with an embodiment of the present invention;
[0031] Fig. 5D illustrates an exemplary representation showing the condition when the carbon brush wear has reached predetermined level and the spring contact with the brush is removed, thus providing electrical open signal, in accordance with an embodiment of the present invention;
[0032] Figs. 6A and 6C illustrate exemplary representations of a technique for determination of early failure in brushed DC motors, in accordance with an embodiment of the present invention for precious metal commutation system;
[0033] Fig. 6D illustrates an exemplary representation showing the condition when the precious metal brush wear has reached predetermined level and the spring contact with the brush is removed, thus providing electrical open signal, in accordance with an embodiment of the present invention;
[0034] Figs. 7A and 7C illustrate exemplary representations of constant force springs used for early failure detection in brushed DC motors, in accordance with an embodiment of the present invention. Fig. 7C shows the condition where brush wear took place without any mechanism to detect the level of wear, in accordance with an embodiment of the present invention; and
[0035] Figs. 7D and 7E illustrate exemplary representations showing disengagement of electrical contact between the constant force spring and the brush before and after a level of pre-determined wear of the brush, in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0036] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0037] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. This disclosure may however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the disclosure to those of ordinary skill in the art. Moreover, all statements herein reciting embodiments of the disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future.
[0038] In an embodiment of the present invention, an electric motor comprises an air-cored rotor which further comprises a motor shaft, air-cored hollow-cylindrical outer rotor windings with several winding terminations formed by the loops of the coil, and a commutation system comprising of a set of collectors disposed around a cylindrical lamella, electrically connected to the winding terminations of the outer rotor windings. The rotor is supported at the collector end with the help of plastic moulding or metal disc welded on the shaft, generally called the collector base support. The other end of the rotor is usually overhanging. The rotor is supported by means of a set of bearing on both ends and is connected to the input terminal by means of the set of collectors arranged cylindrically on one face of the rotor. The collector segments are soldered or welded to the end-terminals of rotor coil loops in a specific configuration. The other ends of collector segments are connected to input terminal with the help of brushes which slide on the surface of the collectors in such a way that electromagnetic imbalance is created between wound coil loops. The coil support is basically the plastic moulding between a knurling on the shaft and one end of the self-supported coil. The connection between coil loops and collectors are done with the help of annular groves in the moulding where the end terminals of each loop are soldered or brazed or welded with the collector segments. For higher torque application, plastic moulding is replaced with a metallic plate welded in the shaft and connected or bonded of the coil of the rotor by some means.
[0039] The electric motor according to invention, further comprises a stator includes either a multi-pole magnet or coil wound in the slots of lamination stacked together to rotate the magnetic field based on specific design and an assembly at the end-cap of the motor, comprising a set of brush pairs and a technique for determining the life span of the motor and triggering an alarm for the user. The number of brush pairs depending on the number of pole pairs is formed by the stator magnetic circuit. The rotor coil, according to an embodiment of the invention, is made so that it is located in the air-gap between the magnetic stator and a tube which completes the magnetic circuit. The tube is generally a low-carbon steel, highly permeable enclosure on the motor which is generally coated to prevent oxidation. Thus, the electromagnetic flux arising from the stator magnets/coils pass through the air gap in which the rotor floats with the help of end bearing supports, and completes the path through the magnetically permeable tube. The brush assembly, according to the invention, is configured to detect the mechanical wear of the brush such that when the brush is worn out to a pre-determined level, i.e. on the basis of change in the dimension/position of the brush; a trigger is initiated by the brush assembly, so as to intimate the user about the wear of the brushes and the nearing end-of-life of the motor. The user after receiving the signal can replace the motor before the actual failure of the motor takes place. The entire assembly of the motor is enclosed within a housing or outer enclosure and is closed with a top cover.
[0040] For the purposes of the invention, the stator described herein may be either permanent magnet based, or coils wound on a slotted lamination stack. The rotor described herein consists of a rotating or linearly moving part either enveloping or enveloped by the stator. The rotor is supported at two ends by means of bearings. The rotor may be either wound coils on slotted lamination stack or self-supported coils wound and bonded without the use of laminations. The rotor described herein is supported and connected mechanically at one end on the rotor shaft by plastic moulding or by metallic disc welded on shaft and glued on rotor circumference. The rotor is placed in the air-gap between stator and outside enclosure which is used to complete the magnetic circuit. The rotor is made of individual loops with plurality number of turns and layers connected in series, parallel or combination of series and parallel. The number of loops depend on the motor design and can be any odd combination, e.g., 3, 5, 7, 9,13,16,21…n, where n is any integer of odd value. Further, the rotor described herein is electrically connected with commutation segments by soldering/welding or any other electrical connection methods. Furthermore, the end-cap described herein is principally similar to most of the electric brush DC motors, which includes plurality of brush system arranged in pairs, 180 electrical degrees apart and equal to the number of poles in the stator achieved by means of either permanent magnet or coil windings. The brush may be either copper/graphite or precious metal alloy or a hybrid combination and is designed in such a way that the contact between static brushes and rotating commutation segment offers low friction and low electrical contact resistances. The design of the brushes used in the motor may be of any type such as hammer design, finger design etc. as known in the state of the art. The brush-collector contact is designed in such a way to maximize the performance and life of the motor; because in brush DC motors, the dominant failure mode occurs when the life of either brush or the collector ends due to mechanical and electrical wear.
In one embodiment of the present invention, the brush assembly of the motor includes at least one extension attached to each brush of the brush assembly. The extension may be welded from one end to the brush and free to move at the other end, acting like a cantilever. As mentioned earlier, brushes of different types and configuration may be used in the motor.
[0041] Fig. 1A to 1D illustrates several sectional views of a carbon brush DC motor in general. The shape of different component in the design can vary largely based on the designed parameters. The carbon brush design and shape can vary based on whether the spring mechanism is torsional or constant force or any other type.
[0042] Fig 2A to 2D illustrates several sectional views of a precious metal brush DC motor in general. The shape of different component in the design can vary largely based on the designed parameters. The precious metal brush design, number of fingers, gap between each finger and shape can vary based on whether motor specific parameters.
[0043] Figs. 3A to 3D illustrate the sectional views of a brush assembly with hammer design carbon brushes in a DC motor (1) according to an embodiment of the invention. The motor (1) comprises an air-cored rotor which further comprises a motor shaft (2), and a commutation system comprising of a set of collectors (4) disposed around a cylindrical lamella of a collector base plate (3), electrically connected to the winding terminations of the outer rotor windings. As shown, the assembly includes a pair of hammer design brushes (7) with cantilever like extensions (8) attached to each brush (7) and extending to the motor terminal (9). The brushes are supported and are fixed onto the brush support (5). The brush support (5) further includes a set of additional extensions (6) which are in contact with the cantilevers like extensions (8) of the brush assembly. The top cover (10) of the motor (1) is provided with a detector pin such that when the brushes (7) or collector segments (4) wear out, the metallic extension (8) comes in electrical contact with the detector pin, thereby completing an electric circuit which may trigger a signal or alarm. The invention may also be used for brushes having finger like projections. Fig. 3D shows the condition when the predetermined level of wear has already taken place in the commutation system and the cantilever like electrode projection (8) comes in electrical contact with the fixed, floating electrode (6), thereby generating a trigger.
[0044] Figs. 4A to 4D illustrate the brush assembly including finger projection brushes in a DC motor according to an embodiment of the invention. In this embodiment, the brush assembly includes a pair of precious metal brushes (7) with projections. Attached to the projections of each of the brush (7) is an extension (8) in the form of a bar which acts like cantilevers. Another set of extensions (6) is provided on the brush support (5), which on wearing of the brushes (7) or collector segments (4) come in electrical contact with the detector pin on the top cover (10), thereby completing an electric circuit and triggering a signal or an alarm for the user. This signal/alarm may be then electronically transmitted to the user to show the level of wear out and remaining life of the motor by means of an alarming means. The detector pin is further configured in such a way that even when the pre-determined level of wear is reached, the detector pin allows the brush (7) to move forward by allowing the cantilever (8) to slide on the detector pin, thus not affecting the functioning of the motor (1) and yet providing the trigger to the user. Thus, even when the alarm is triggered, the motor (1) does not stop to function as in case of the conventional wear detection devices. In Fig. 4D the condition, where maximum desired level of wear is reached, is shown.
[0045] In another embodiment of the invention, instead of the cantilever like extensions (8), the brush assembly may include a pair of springs (11) with extensions. The springs (11), at one end, are fixed at an inner edge of end-caps and from the other free–end, touch that surface of the brush (7) which is not in contact with the collector (4). The springs (11) are compressed to such a level that if a pre-determined level of wear of brushes (7) or collectors (4) occurs, then due to the inward movement of the brushes (7), the free end of the spring (11) disconnects with the brush (7). This causes an electrical open circuit between the spring (11) and the brush (7). Since, the brush (7) is directly in contact with the input terminal of the motor (1), a short-circuit signal is generated if the signals are taken from the body of the spring (11) and the outer terminal, initially. However, when the brush (7) wears out up to the pre-defined level, the signal between motor terminal and the spring (11) opens and a trigger/alarm is generated. Fig. 5A-5D shows several illustration of this method of detection for brush wear for carbon brush type brushed DC motor using springs (11) and hammer design brushes (7) in a DC motor. As shown, the brush assembly includes hammer design carbon brushes (7) with an end-cap. A spring (11) having an extension is attached to the end-cap of each of the brushes (7) through a conductive plate (12) (as shown in Fig. 5C). The spring compression is set to a pre-determined level in such a way that when pre-determined wear occurs, the spring-brush contact is disengaged, and circuit between spring extension and the detector pin on the top cover (10) is completed, thereby setting a trigger / alarm signal for the user.
[0046] Figs. 6A and 6D illustrate the sectional view of a brush assembly with precious metal brushes (7) and spring extensions (13) in a DC motor (1) according to the alternate embodiment of the invention. Fig. 6C illustrates the brush assembly with springs (13) attached to finger projection brushes (7). As shown, the brush assembly includes brushes with finger like projections (7) with an end-cap. A spring (13) having an extension is attached to the end-cap of each of the brushes (7) through a conductive plate (14) (as shown in Fig. 6C). The spring compression is set to a pre-determined value, decided in such a way that when pre-determined wear occurs, the spring-brush contact is disengaged, thereby, opening the circuit between spring (13) for setting a trigger for alarm. Advantageously, in brushes (7) having finger like projections, the spring (13) connects to all the fingers and hence are in uniform contact with the precious metal brush, thereby increasing life of the brush (7) as the current through the brushes is distributed uniformly. Further, the spring (13) also acts as a noise damping mechanism which reduces the overall noise of the motor. The brush assembly with springs (13) according to this embodiment may also be used with any type of brush such as carbon brush (7), precious metal brush (7) and the like, of any configuration and design thereof.
[0047] Figs. 7A and 7B illustrate exemplary representations of a technique for determination of early failure in brushed DC motors, in accordance with an embodiment of the present invention. The brush assembly may include constant force springs (15) positioned such that they push the hammer design carbon brushes (7) towards the collector segments (4) constantly with exactly the same force over the life of the motor (1) irrespective of wear pattern of the brush/collector junction. Fig. 7C shows the condition where the existing constant force spring (15) rolls over the brush (7) surface gradually to maintain the constant force on the brush (7) throughout its life.
[0048] In an embodiment of the present invention, the spiral constant force springs (15) may be designed such that they roll over the hammer design carbon brushes (7), which are pivoted on respective pivot axis, as the brushes (7) wear down during the life of the motor (1). The spiral springs (15) may be made up of metallic stainless steel or any other metal or alloy having similar strength.
[0049] Referring now to Figs. 7D and 7E, where disengagement of electrical contact between the spring (15) and the brush (7) before and after the pre-determined level of wear of the brush is shown. When the brush (7) wears, contact between the spiral portion of the spring (15) and the carbon brush (7) shifts towards the pivot axis (16) (as shown in Fig. 7D) of the brush. This movement allows the spring (15) to be in constant contact with the brush (7) for proper functioning of the commutation.
[0050] In an embodiment of the present invention, a set of terminals (17) emanating out of the fixed portion of the constant force spring (15), as shown in Figs. 7D and 7E, may be short-circuited to the terminals of the motor through which power is fed into the motor (1). Thus, electrical continuity is established between the two sets of terminals per pole pair of the brushed motor.
[0051] In an embodiment, a portion the carbon brush (7) may be electrically insulated after, for instance, 80, 90 or 95% of its active length by a coating of an insulated portion (18) (as clearly shown in Fig. 7E). When the spiral spring (15) rolls over to the insulated portion (18), electrical continuity between the two sets of terminals per pole pair of the motor breaks and a trigger is generated indicating the early failure of the motor.
[0052] In an embodiment of the present invention, various electronic components, such as, receiver, detector pin, etc. can be incorporated in the brush assembly to detect wear of the brushes and early failure of the motor, depending on the level of vibration of the brush-collector segment, motor speed and life expectancy.
[0053] In another embodiment of the invention, the brushes are provided with optical Light Emitting Diodes. The LEDs are mounted on each of the brush face. A receiver is placed on the top cover of the motor in such a way that a signal is received by the receiver only if the brush is displaced by a pre-determined distance. This distance is pre-determined based on the wear required to reach specific amount of life consumption. As the pre-determined level of wear and distance of the brush is reached, a signal from the LED is sent to the receiver. The receiver may be a transceiver capable of transmitting the signal to the user. Further, multiple receivers can be placed on the top cap such that multiple triggers can be set based on different amounts of life consumption.
[0054] The disclosed brush assembly allows the user to replace the motor during off-time, as soon as an alarm is triggered when the pre-determined level of wear of the brushes or collector has taken place, and prevents any failure during working of the applications and eliminating the down-time of the system. Moreover, in the current scenarios, where frequent motor changes are done due to the unpredictable remaining life of the motor, the disclosed mechanism would also help in preventing wastage caused by replacing motors much before end-time is reached, thereby reducing costs and ensuring reliability. The brush assembly as disclosed by the present invention is suitable for motors of all sizes with any combination of brush/collector arrangement and with any specification; replacing the scope of using physical strain sensors and other techniques currently used for large motors. However, it is best suited for small sized motors.
[0055] Various modifications to these embodiments are apparent to those skilled in the art from the description and drawings herein. The principles associated with the various embodiment defined herein may be applied to other embodiments. Therefore, the description is not intended to be limited to the embodiments shown along with the accompanying drawings but is to be provided broadest scope consistent with the principles and novel and inventive features describe/disclosed or suggested herein. Any modifications, equivalent substitutions, improvements etc. within the principle of the present invention shall all be included in the scope of protection of the present invention.
,CLAIMS:We Claim:
1. A brush assembly for an electric brush motor (1), comprising:
a plurality of brushes (7) adapted to conduct electrical current between at least one commutator segment (4) of a rotor and a terminal (9) of said motor (1); and
a detector pin operatively coupled with a casing (10) of said motor (1), said detector pin being adapted to trigger a signal when a pre-determined level of wear of any or a combination of at least one of the plurality of brushes (7) and said at least one commutator segment (4) is detected;
wherein each of said plurality of brushes (7) is attached to at least one extension (8), said at least one extension (8) extends to said terminal (9) of said motor (1), such that when a pre-determined level of wear of any or a combination of at least one of said plurality of brushes (7) and said at least one commutator segment (4) is reached, said at least one extension (8) comes in contact with said detector pin to trigger the signal indicating the wear of any or a combination of said at least one of said plurality of brushes (7) and said at least one commutator segment (4).
2. The brush assembly as claimed in claim 1, further comprising at least one additional extension (6) in contact with the at least one extension (8), such that when the pre-determined level of wear of any or a combination of at least one of the plurality of brushes (7) and the at least one commutator segment (9) is reached, the at least one additional extension (6) comes in contact with the detector pin to trigger the signal indicating the wear.
3. The brush assembly as claimed in claim 1, wherein the detector pin allows the brush (7) to move forward and conduct electrical current between the terminal (9) and the at least one commutator segment (4) of the rotor, even when the pre-determined level of wear is reached by allowing the at least one extension (8) to slide on the detector pin, thereby triggering the signal without affecting the functioning of the motor (1).
4. A brush assembly for an electric brush motor (1), comprising:
a plurality of brushes (7) adapted to conduct electrical current between at least one commutator segment (4) of a rotor and a terminal (9) of said motor (1); and
a detector pin operatively coupled with a casing (10) of the motor, said detector pin being adapted to trigger a signal when a pre-determined level of wear of any or a combination of at least one brush (7) of said plurality of brushes (7) and said at least one commutator segment (4) is detected;
wherein each of said plurality of brushes (7) is connected to a spring (11) having an extension by means of a conductive plate (12), such that when the pre-determined level of wear of any or a combination of at least one brush (7) and said at least one collector segment (4) is reached, the spring (11) gets disconnected from the at least one brush (7), and an open electric circuit is formed between said spring (11) and the at least one brush (7) to which said spring (11) is connected, thereby triggering the signal indicating wear of any or a combination of at least one of said plurality of brushes (7) and said at least one commutator segment (4).
5. The brush assembly as claimed in claim 4, wherein said plurality of brushes (7) are in contact with an input terminal of said motor (1), and said spring (11) is in contact with an outer terminal of said motor (1).
6. A brush assembly for an electric brush motor (1), comprising:
a plurality of brushes (7), each brush of said plurality of brushes (7) pivoted on a pivot axis (16) and adapted to conduct electrical current between at least one commutator segment (4) of a rotor and a terminal (9) of said motor (1); and
at least one spring (15) with an extension (17) in contact with each of said plurality of brushes (7), adapted to push each of said plurality of brushes (7) towards the said at least one collector segment (4),
wherein an insulated portion (18) is provided on at least one brush (7) of said plurality of brushes after a pre-determined length of said at least one brush (7), such that when a pre-determined level of wear of any or a combination of said at least one brush (7) and said at least one commutator segment (4) is reached, said spring (15) comes in contact with said insulated portion (18) to generate a trigger indicating early failure detection of said motor (1).
7. The brush assembly as claimed in claim 6, wherein when said at least one brush (7) starts to wear out, the contact between said spring (15) and said at least one brush (7) shifts towards the pivot axis (16) of said at least one brush (7).
8. The brush assembly as claimed in any of preceding claims, wherein said plurality of brushes (7) comprise any or a combination of hammer design carbon brushes, precious metal brushes, and brushes having finger like projections.
9. The brush assembly as claimed in any of the preceding claims, further comprising a receiver operatively coupled with the casing (10) of the motor (1) and operable to receive the signal indicating pre-determined level of wear of any or a combination of said at least one brush (7) and said at least one commutator segment (4).
Dated this 25th May 2018
[JAYANTA PAL]
IN/PA No. 172
Remfry & Sagar
ATTORNEY FOR THE APPLICANT[S]