A differential self-balancing carbon brush contact pressure adjusting mechanism, brush assembly and motor

Abstract

The application discloses a differential self-balancing carbon brush contact pressure adjusting mechanism, a connecting cap is arranged at the back of the carbon brush, and two groups of flange lugs are arranged on the connecting cap; a differential support part is rotatably arranged on an electric brush holder shell through a middle shaft, and the differential support part has two output ends; two connecting members are respectively connected between the two output ends of the differential support part and the two groups of flange lugs, so as to form two space-separated pressure transmission paths; a main pre-tightening elastic member is arranged between the electric brush holder shell and the differential support part, and is used for providing a common pre-tightening load to the differential support part, so that the differential support part transmits the pre-tightening force to two different load areas at the back of the carbon brush through the two connecting members; wherein, when the two load areas of the carbon brush produce relative displacement due to local geometric disturbance of a commutator, the differential support part can produce limited swing around the middle shaft, so that the two connecting members produce controlled differential displacement, so as to absorb the relative displacement of the two sides of the carbon brush and realize self-balancing of the contact pressure.

Description

Technical Field

[0001] This invention relates to the fields of brushed motors, brush assemblies, and sliding electrical contacts, and particularly to a carbon brush contact pressure regulating mechanism, brush assembly, and brushed motor that passively self-balances the contact pressure in different load areas of the same carbon brush using a common preload and a mechanical differential balancing structure. This mechanism is applicable to automotive brushed DC motors, pump motors, fan motors, wiper motors, actuator motors, seat motors, industrial DC motors, and other motor devices that use carbon brushes to form sliding electrical contacts with commutators or slip rings. Background Technology

[0002] Brushed motors typically use springs to press carbon brushes against the commutator directly or via force transmission components, maintaining stable sliding electrical contact between the brush contact surface and the rotating commutator. The normal pressure between the carbon brush and the commutator not only affects contact resistance and current transmission but also influences commutation sparking, brush runout, mechanical wear, noise, and the thermal load on the commutator surface. Traditional brush structures mostly use a single spring to apply pressure in the central or near-central region of the carbon brush back. While simple in structure, the pressure transmission path is essentially single-channel.

[0003] In actual motors, the carbon brush contact surfaces are not always perfectly parallel. There may be slight height differences between commutator segments, and the commutator surface may have localized roundness errors, waviness, wear grooves, or machining residue. There may also be assembly tilt between the rotor shaft and the brush holder, and the commutator may have axial taper or end deviations. After long-term operation, the carbon brushes may also experience contact surface wear. Furthermore, as the commutator segments alternately pass over the carbon brush contact surface, periodic local disturbances are created at different locations on the carbon brush contact surface. All of these factors can cause slight relative displacements or load biases in different areas of the carbon brush contact surface over short periods of time.

[0004] When traditional single-point or single-channel preload structures encounter the aforementioned local displacement, the carbon brush itself, the brush holder gap, and the spring system need to collectively absorb this displacement. If the force transmission location is too concentrated, local displacement can easily translate into changes in carbon brush posture, increased pressure at one contact edge, and decreased pressure at another contact edge. In severe cases, this can cause localized separation, carbon brush slapping, increased noise, or increased commutation sparks. To improve contact, some existing structures use multiple independent carbon blocks, separate carbon brushes, or multiple springs to load different carbon blocks separately. However, these structures increase the number of carbon blocks, conductive connections, and assembly interfaces. Furthermore, the manufacturing dispersion, assembly tolerances, and lifespan variations of multiple springs can introduce new pressure consistency issues.

[0005] Therefore, a mechanical structure is needed that can retain the electrical continuity and assembly simplicity of a single carbon brush, while simultaneously creating two spatially separated pressure paths on the back of the brush and allowing controlled differential displacement between the two pressure paths. This structure should also ensure that both pressure paths are driven by the same common preload source, thus avoiding the use of two completely independent pressure springs, and reducing the transient pressure difference between the two load areas through mechanical balancing. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention provides a differential self-balancing carbon brush contact pressure adjustment mechanism, a brush assembly, and a motor. This addresses the problems in existing technologies where single-point or single-channel preload structures cause relative displacement of different areas of the carbon brush contact surface due to local geometric disturbances in the commutator (such as commutator segment height difference, roundness error, wear grooves, assembly tilt, etc.), leading to pressure bias, increased pressure on one contact edge while decreasing pressure on the other, localized separation, carbon brush slapping, increased commutation sparks, and aggravated mechanical wear. Simultaneously, it avoids the problems of increased component quantity, complex assembly, discrete spring manufacturing, and poor pressure consistency resulting from using multiple independent carbon blocks and multiple springs for separate loading.

[0007] To solve the above technical problems, the present invention provides the following technical solution: a differential self-balancing carbon brush contact pressure regulating mechanism, comprising: a carbon brush, the carbon brush being a single continuous type, slidably disposed within a brush holder housing along the wear feed direction toward the commutator, the front end of the carbon brush being used for sliding contact with the commutator; a connecting cap, disposed on the back of the carbon brush, the connecting cap having two sets of flanged lugs, the two flanged lugs serving as load areas; a differential support portion, generating differential movement within a defined range relative to the brush holder housing via an intermediate shaft, the two ends of the differential support portion being output ends; and two connecting members, respectively connected to the two output ends of the differential support portion and the two sets of flanged lugs. Between the side lugs, two spatially separated pressure transmission paths are formed; the main preload elastic element is set between the brush holder housing and the differential support part to provide a common preload load to the differential support part, so that the differential support part transmits the preload force to two different load areas on the back of the carbon brush through two connecting parts; wherein, when the two load areas of the carbon brush are relatively displaced due to local geometric disturbance of the commutator, the differential support part can generate restricted oscillation around the intermediate axis, so that the two connecting parts generate controlled differential displacement to absorb the relative displacement on both sides of the carbon brush and achieve self-balancing of contact pressure; while during normal wear of the carbon brush, the carbon brush can move as a whole along the wear feed direction.

[0008] As a preferred embodiment of the present invention, the connecting member is a short connecting rod, and the two ends of the short connecting rod are respectively rotatably connected to the end of the differential support and the flange lug.

[0009] As a preferred embodiment of the present invention, the differential support is a rigid rocker arm structure, with the intermediate shaft passing through the middle of the differential support.

[0010] As a preferred technical solution of the present invention, the differential support is an integrated flexible equalizer with a central force-bearing area and two branch output arms. The two branch output arms are connected to the central force-bearing area through a thin-walled flexible area.

[0011] As a preferred embodiment of the present invention, it further includes a reset elastic element, which is disposed between the differential support portion and the intermediate shaft, and is used to provide a reset torque after the differential support portion swings.

[0012] As a preferred embodiment of the present invention, the brush holder housing is provided with two differential stroke limiters, and a guide slot is formed between the two differential stroke limiters. The carbon brush is installed between the two differential stroke limiters and can be displaced along the circumference of the commutator. An initial gap is maintained between the differential stroke limiters and the carbon brush to limit the excessive oscillation of the carbon brush during abnormal impacts.

[0013] As a preferred technical solution of the present invention, a guide groove is provided on the brush holder housing. The guide groove and the guide slot are arranged coaxially along the axial direction. The two ends of the intermediate shaft are respectively located in the guide groove and the guide slot. An angle limiting boss is provided at the end of the intermediate shaft located in the guide groove and the guide slot to limit the maximum differential rotation angle of the differential support part. A positioning sleeve is sleeved on the outside of the intermediate shaft to limit the axial movement of the differential support part relative to the intermediate shaft.

[0014] A brush assembly includes a brush holder housing, a carbon brush, and the aforementioned differential self-balancing carbon brush contact pressure adjustment mechanism.

[0015] As a preferred embodiment of the present invention, the flexible conductive connector of the carbon brush is led out from the guide slot. A brushed motor includes a rotor, a commutator disposed on the rotor, and the aforementioned brush assembly. The carbon brushes form sliding electrical contact with the commutator under the action of a main preload elastic member. The differential support is capable of reversible differential response to local disturbances in two directions.

[0016] A method for self-balancing carbon brush contact pressure in a brushed motor includes the following steps: applying a common preload to the differential support via a main preload elastic element; transmitting the common preload to two sets of flanged lugs on the connecting cap via two connectors through the two output ends of the differential support, so that the two spatially separated load areas on the back of the carbon brush are simultaneously subjected to preload force to maintain contact between the carbon brush and the commutator; when local geometric disturbances of the commutator cause relative displacement between the two load areas of the carbon brush, the differential support generates restricted oscillation around its central axis, causing the two connectors to generate controlled differential displacement to absorb the relative displacement on both sides of the carbon brush, thereby reducing the transient pressure difference between the two load areas and achieving passive self-balancing of contact pressure.

[0017] As a preferred embodiment of the present invention, the method further includes the following steps: after the differential support swings, a reverse reset torque is provided by the reset elastic element to return the differential support to the neutral position; after the carbon brush gradually wears and shortens, the main preload elastic element continuously applies a load to the differential support, pushing the carbon brush towards the commutator to compensate for the wear; when the contact surface of the carbon brush is subjected to local surface disturbance on one side, the connecting member on the corresponding side first retracts, causing the differential support to swing to the opposite side, so that the connecting member on the other side continues to fit.

[0018] Compared with the prior art, the beneficial effects that this invention can achieve are: 1. By setting a connecting cap and two sets of flanged lugs on the back of the same carbon brush, and using the differential support, connecting parts and main pre-tightening elastic parts to form a dual-path force transmission structure, differential self-balancing loading of two spatially separated load areas can be achieved while maintaining the electrical continuity and assembly simplicity of a single carbon brush. 2. Using the same main preload elastic element as a common preload load source to drive two pressure action paths avoids the problem of inconsistent pressure caused by manufacturing discreteness, assembly tolerance and life variation of multiple springs; 3. When the carbon brush contact surface is subjected to local geometric disturbance of the commutator and causes local displacement, the differential support can generate restricted oscillation around the intermediate shaft, so that the two connecting parts generate controlled differential displacement, thereby absorbing the relative displacement on both sides of the carbon brush, reducing the transient pressure difference between the two load areas, suppressing the carbon brush posture change and edge pressure concentration, which helps to reduce commutation sparks, noise and mechanical wear. 4. The differential self-balancing function of this invention does not conflict with the normal wear feed of the carbon brush. As the carbon brush gradually wears and shortens, the main preload elastic element continuously applies a load to the differential support, causing the carbon brush to move towards the commutator. The differential support mainly handles the small relative displacements of the two contact sides of the carbon brush, while the larger overall feed displacement during the carbon brush's lifespan is borne by the normal working stroke of the main preload elastic element, thus maintaining the differential self-balancing function throughout the entire lifespan of the carbon brush. Attached Figure Description

[0019] Figure 1 This is a three-dimensional schematic diagram of the brush assembly of the present invention; Figure 2 This is a partial cross-sectional perspective view of the brush assembly of the present invention; Figure 3 For the present invention Figure 2 Enlarged view of a portion of point A in the middle; Figure 4 This is a three-dimensional schematic diagram of the mating of the reset elastic element and the differential support part of the present invention; Figure 5 This is a three-dimensional schematic diagram of the carbon brush assembly of the present invention; Figure 6 This is a schematic diagram of the ideal working state of the brush assembly and commutator after assembly of the present invention; Figure 7 This is a schematic diagram of the commutator offset state after the brush assembly and commutator of the present invention are assembled. Figure 8 For the present invention Figure 7 Enlarged view of a portion of point B in the middle; Figure 9 This is a three-dimensional schematic diagram of the brush assembly with a thermal bimetallic strip according to the present invention; Figure 10 For the present invention Figure 9 Enlarged view of a portion of point C in the middle; Figure 11 This is a three-dimensional schematic diagram of the connection between the differential support and the connecting cap of the present invention; Figure 12 This is a three-dimensional schematic diagram of the thermal bimetallic strip of the present invention; The components include: 1. Brush holder housing; 2. Carbon brush; 3. Differential travel limit component; 4. Main preload elastic component; 5. Spring seat; 6. Intermediate shaft; 7. Guide slot; 8. Reset elastic component; 9. Differential support part; 10. Mounting groove; 11. Connector; 12. Connecting cap; 13. Flanged lug; 14. Angle limiting boss; 15. Positioning sleeve; 16. Guide groove; 17. Thermo-bimetallic strip; 18. Commutator. Detailed Implementation

[0020] To make the technical means, creative features, objectives, and effects of this invention easier to understand, the invention is further described below with reference to specific embodiments. However, the following embodiments are merely preferred embodiments of this invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are all within the protection scope of this invention.

[0021] Example 1: Integral Differential Self-Balancing Structure like Figures 1 to 12As shown, the present invention provides a differential self-balancing carbon brush contact pressure adjustment mechanism, which is applied to a brush assembly and a motor including a brush holder housing 1, a carbon brush 2, a commutator 18.

[0022] Two differential travel limiters 3 are provided on the side of the brush holder housing 1 near the commutator 18. The two differential travel limiters 3 are spaced apart to form a guide slot 7. The carbon brush 2 is installed between the two differential travel limiters 3. The distance between the inner wall of the differential travel limiter 3 and the brush holder housing 1 is adapted to the axial length of the carbon brush 2, thereby restricting the carbon brush 2 from moving axially. At the same time, the carbon brush 2 can generate a certain displacement in the circumferential direction between the two differential travel limiters 3, so that the carbon brush 2 can follow the commutator 18 after it is offset, preventing the end of the carbon brush 2 from being obliquely worn.

[0023] The carbon brush 2 remains a single continuous carbon body, with its front end forming a working surface that contacts the commutator 18, and its rear end serving as the force-bearing end connected to a connecting cap 12. The connecting cap 12 is preferably formed from a combination of wear-resistant metal, high-temperature resistant engineering plastic, or a metal skeleton and an insulating wear-resistant layer. The lower surface of the connecting cap 12 forms a large contact area with the back of the carbon brush 2, and the upper surface of the connecting cap 12 is provided with upwardly punched and flanged lugs 13. Two sets of flanged lugs 13 are symmetrically arranged on the top surface of the connecting cap 12. The flexible conductive connector of the carbon brush 2 extends from the guide slot 7 and connects to the brush circuit of the motor. The connecting cap 12 does not need to be fixedly mounted on the carbon brush 2; it can be prevented from falling off through shallow grooves, lateral limiting edges, or flexible clamping structures. This allows the localized force of the connector 11 to first act on the connecting cap 12, and then be transferred to the carbon brush 2 over a larger area, thereby reducing the risk of chipping and localized indentation on the back of the carbon brush.

[0024] The carbon brush 2 has a pressure regulating mechanism at its rear end, which includes a differential support 9. The two output ends (i.e., the two ends) of the differential support 9 are connected to the two sets of flanged lugs 13 via connectors 11. Connectors 11 use short connecting rods and a rotating connection at both ends to avoid significant lateral jamming when the differential support 9 swings at small angles. In products where space permits, the short connecting rod can also be replaced by a short-stroke push rod, a ball-head pressure post, a roller follower, or a flexible connecting piece.

[0025] A spring seat 5 is fixed on the brush holder housing 1. The spring seat 5 is connected to a main preload elastic element 4. The other end of the main preload elastic element 4 is connected to a reset elastic element 8. The reset elastic element 8 contacts the differential support part 9, thereby applying a preload load to the carbon brush 2 through the main preload elastic element 4. The main preload elastic element 4 can be a helical compression spring, torsion spring, coil spring, or constant force spring.

[0026] The differential support 9 has a mounting groove 10 on its top surface, and the two ends of the reset elastic member 8 are placed in the mounting groove 10. The width of the differential support 9 matches the width of the mounting groove 10, and the mounting groove 10 has a certain length, allowing the ends of the reset elastic member 8 to slide slightly within the mounting groove 10. The reset elastic member 8 spans between the differential support 9 and the intermediate shaft 6. In one specific implementation, the reset elastic member 8 is a leaf spring. When the differential support 9 swings in either direction, the reset elastic member 8 generates a small elastic deformation and provides a reverse reset force. This reset force is mainly used to eliminate free play and to return the differential support 9 to the neutral region after the disturbance disappears, without undertaking the main carbon brush preload function.

[0027] Two differential travel limiters 3 are respectively located near the allowable swing boundaries at both ends of the differential support 9. An initial gap is maintained between the differential travel limiters 3 and the carbon brush 2, and they do not contact each other during normal, small differential movements. The carbon brush 2 only contacts the differential travel limiters 3 when there is an abnormal step on the commutator 18, an external impact, or significant vibration to the brush holder. Small elastic pads can be provided on the limiting contact surfaces to prevent hard impacts.

[0028] A guide groove 16 is provided at the rear of the brush holder housing 1. The guide groove 16 has the same width as the guide slot 7, and the guide groove 16 and the guide slot 7 are arranged axially. An intermediate shaft 6 is fixed to both sides of the differential support part 9. The two ends of the intermediate shaft 6 are located in the guide groove 16 and the guide slot 7, respectively, allowing the differential support part 9 to rotate only along the intermediate shaft 6 and move radially. To prevent the differential support part 9 from rotating too much, an angle limiting boss 14 is provided at one end of the intermediate shaft 6 located in the guide groove 16 and the guide slot 7, allowing the differential support part 9 to rotate only within a limited angle range. To ensure the centering of the differential support part 9, a positioning sleeve 15 is fixed or fitted on the outside of the intermediate shaft 6 to limit the axial position of the differential support part 9. Two positioning sleeves 15 are provided: one located outside the intermediate shaft 6 between the differential support part 9 and the brush holder housing 1, and the other located outside the intermediate shaft 6 between the differential support part 9 and the differential stroke limiter 3.

[0029] like Figures 9 to 12As shown, in another alternative embodiment, the connector 11 can also be replaced by a thermo-bimetallic strip 17. This thermo-bimetallic strip 17 consists of connecting ends at both ends and a middle arc-shaped elastic segment, which is formed by laminating two metal layers with different coefficients of thermal expansion. At room temperature, the arc-shaped elastic segment maintains a preset curvature, providing a certain preload. When the ambient temperature rises, due to the different expansion amounts of the two metal layers, the arc-shaped elastic segment undergoes additional bending deformation in a preset direction (e.g., bulging outwards or contracting inwards), thereby changing the effective force transmission length of the connector 11. This causes the corresponding load area on the back of the carbon brush 2 to receive additional thrust or tension to compensate for the decrease in elasticity of the main preload elastic element 4 caused by temperature rise or the change in contact pressure caused by the thermal expansion of the brush holder. This thermo-bimetallic strip solution only serves as additional temperature compensation for the basic differential structure and does not affect the response of the differential support 9 to local displacement, nor does it constitute a necessary feature for achieving self-balancing functionality.

[0030] Example 2: Load Balancing under Ideal Operating Conditions like Figure 6 As shown, under ideal operating conditions, the axis of the commutator 18 is collinear with the axis of the brush holder housing 1. Since the contact end arc surface of the carbon brush 2 mates with the commutator 18, the carbon brush 2 does not tilt. At this time, the tilt angles of the two connecting parts 11 are the same, and they are subjected to the same force. The sum of the forces on the two connecting parts 11 is mainly determined by the elastic force of the main preload elastic element 4. Therefore, the total preload force required for the carbon brush 2 can be determined by controlling the main preload elastic element 4.

[0031] This invention does not require that the two connecting parts 11 have mathematically equal pressure at any given moment. Actual loads are affected by guide friction, contact surface morphology, the reset elastic element 8, and dynamic inertia. The purpose of this invention is to provide a mechanical degree of freedom capable of absorbing the difference between the two output positions and to limit long-term deviations between the two load paths through a common load source.

[0032] Example 3: Differential response along the commutator circumference like Figure 7 and Figure 8As shown, when an edge of a commutator segment of the commutator 18, a local height difference, or a local surface disturbance moving along the commutator circumference first passes the first contact side of the carbon brush 2, that side may experience a slight lift or reaction force change earlier than the other side. The corresponding connector 11 retracts slightly with the first contact side of the carbon brush 2, causing the differential support 9 to swing around the intermediate shaft 6 in a restricted manner, thus causing the connector 11 on the other side of the differential support 9 to displace in the opposite direction. During this process, the differential displacement is mainly borne by the angular displacement of the differential support 9, and the main preload elastic member 4 does not need to compress the relative displacement between the two connectors 11 at the same amplitude. The first contact side of the carbon brush 2 refers to the side that first contacts the commutator 18; for example, when the commutator 18 rotates counterclockwise, the right side of the carbon brush 2... (See diagram). Figure 8 The first contact side is the opposite of the first contact side.

[0033] When a local disturbance moves away from the first contact side and towards the other side as the commutator 18 rotates, the differential support 9 passes through the neutral position under the combined action of the reset elastic member 8 and the contact reaction force, and can generate a short-term oscillation in the opposite direction. Since the differential stroke is limited by the two differential stroke limiters 3, the carbon brush 2 will not oscillate indefinitely under abnormal commutator segment height differences or external impacts.

[0034] Example 4: Reverse Local Disturbance and Reversible Differential Operation When the second contact side of the carbon brush 2 is displaced relative to the first contact side due to local surface disturbance, the connector 11 on the second contact side first retracts, causing the differential support 9 to swing in the opposite direction to the aforementioned circumferential differential response. The differential support 9 then causes the connector 11 on the other side to follow accordingly. Since the force transmission paths of the two connectors 11 are structurally symmetrical or arranged according to a predetermined ratio, the adjustment mechanism can reversibly respond to local disturbances in both directions.

[0035] This reversible differential capability is particularly advantageous for brushed DC motors that can rotate in both directions. Regardless of the direction of the commutator 18's circumferential motion, the two load regions distributed along the circumferential direction can be either the side that is disturbed first or the side that is disturbed later, and the differential support 9 does not depend on a single direction of rotation to operate. For motors that rotate only in one direction, asymmetrical lever arms or different damping can be appropriately set according to the main disturbance direction to optimize dynamic performance.

[0036] Example 5: Load Balancing Along the Commutator Axis In another embodiment, two sets of flanged lugs 13 are arranged axially spaced along the commutator 18. This arrangement is mainly used to reduce load bias caused by the axial taper of the commutator 18, the slight tilt between the rotor axis and the brush holder mounting surface, the oblique wear of the carbon brush contact surface, and localized axial wear. In this case, the two sets of flanged lugs 13 are located on the back of the connecting cap 12 near the side, but still within the effective force-bearing area of ​​the carbon brush 2.

[0037] When one axial side of the carbon brush 2 contact surface first forms a high contact reaction force with the commutator 18, the corresponding connector 11 yields, and the differential support 9 allows the other connector 11 to continue to engage, thereby reducing the unilateral pressure concentration caused by rigid single-point loading. This embodiment still uses the same carbon brush 2 and does not require dividing the carbon brush into two relatively movable carbon blocks, left and right.

[0038] Example 6: Flexible Integrated Differential Equalizer In addition to the rigid differential support 9 shown in the figure, the differential support 9 can also employ an integrated flexible equalizer. In this embodiment, the differential support 9 is formed by spring steel, fatigue-resistant stainless steel, or high-performance engineering materials, creating a central stress zone and two branch output arms. The two output arms are connected to the central region via a thin-walled flexible area. The main preload elastic element 4 acts on the central stress zone, and the first and second output arms are respectively connected to two sets of flanged lugs 13.

[0039] When the two contact sides of carbon brush 2 experience relative displacement, the two flexible areas undergo elastic deformation in opposite directions or to different degrees, thus providing differential compliance. This structure reduces the need for shafts, pins, and lubrication, and lowers the risk of jamming caused by carbon powder entering the rotating pair.

[0040] Example 7: Continuous operation during carbon brush wear The differential function of this invention does not conflict with the normal wear feed of the carbon brush 2. As the carbon brush 2 gradually wears and shortens, the main preload elastic member 4 continuously applies a load to the differential support 9, causing the carbon brush 2 to advance towards the commutator 18. The differential support 9 mainly handles the small relative displacements of the two contact sides of the carbon brush 2, while the larger overall feed displacement during the life cycle of the carbon brush 2 is borne by the normal working stroke of the main preload elastic member 4.

[0041] Therefore, the present invention does not require a separate wear drive mechanism to maintain the differential self-balancing function. For products that require further control of the average carbon brush pressure over the entire lifespan, the present invention can be used in combination with a constant force spring, coil spring, or other lifespan pressure control structure, but the differential support 9 still functions as a local pressure equalization mechanism between two spatially separated load regions.

[0042] Example 8: Materials and Manufacturing The carbon brush 2 can be made of copper-graphite, electrographite, resin-bonded graphite, or other suitable brush materials, depending on the motor current density and commutation requirements. The differential support 9 and connector 11 can be made of spring steel, stainless steel, alloy steel, or heat-resistant engineering materials. If the differential support 9 is a rigid rocker arm formed by stamping, a reinforcing rib can be formed in the center and connecting holes can be formed at both ends; if a flexible integrated structure is used, it can be manufactured by stamping, laser cutting, precision etching, or injection molding. The intermediate shaft 6 can be made of a pin, knife-edge support, spherical support, or low-friction cylindrical support, the specific form selected based on space, cost, and toner environment.

[0043] Verification method To verify the technical effects of the present invention, a control brush assembly and a differential self-balancing brush assembly with the same structural dimensions and main preload can be fabricated. The control assembly uses single-point or rigid single-plate loading, while the test assembly uses the differential support 9, connector 11, and connector cap 12 of the present invention. Both sets of assemblies use carbon brushes 2 of the same brand, size, and pre-run-in state, and are installed on the same commutator test bench.

[0044] The first type of test is a quasi-static local displacement test. Known minute displacements are applied to the two contact sides of the carbon brush 2, and the reaction force of the connector 11 (a force detection probe can be placed in the middle of the connector 11), the total compression change of the main preload elastic element 4, and the swing angle of the differential support 9 are recorded. An ideal differential structure should exhibit the following characteristics: local displacement is mainly converted into changes in the posture of the differential support 9, while the increase in pressure difference between the two load areas is limited, and the change in total preload is less than that of a rigid single-plate structure.

[0045] The second type of test is the dynamic commutator test. Controlled commutator segment height differences, circumferential surface ripples, or repeatable local geometric disturbances can be set on the test commutator. At different speeds, carbon brush vibration acceleration, contact voltage fluctuations, commutation sparks, dynamic reaction forces of the two connectors 11, and the swing amplitude of the differential support 9 are recorded. By comparing with a control structure, the degree to which the differential structure improves local pressure peaks, carbon brush slapping, and contact instability can be evaluated.

[0046] The third type of test is the durability and contamination test. The brush assembly is operated under predetermined temperature, vibration, and toner conditions, and the differential support 9 is inspected for jamming, reset misalignment, or limit collision marks at multiple life stages. For implementations with flexible equalizers, fatigue in the flexible area should also be checked.

[0047] The above verification results should be based on actual prototype test data. This specification does not consider unconfirmed pressure improvement percentages, lifespan increases, or spark reductions as established technical effects. Through the above structure and testing methods, those skilled in the art can determine parameters such as differential stroke, pressure application point spacing, and main preload force according to the specific motor platform.

[0048] Without altering the core concept of this invention, the main preload elastic element 4 can be a helical compression spring, torsion spring, coil spring, constant force spring, or other elastic element capable of providing working preload for the carbon brush; the differential support part 9 can be a swing arm, a seesaw-type equalizer, a fork-shaped part, a flexible bridge, or an equivalent mechanical differential structure. Any of the above substitutions, as long as they still utilize a common load source and mutually separated output paths to form controlled differential loading on the same carbon brush, constitute a specific implementation of the technical concept of this invention.

[0049] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A differential self-balancing carbon brush contact pressure regulating mechanism, characterized in that: include: Carbon brush (2) is a single continuous type and is slidably disposed in the brush holder housing (1) along the wear feed direction toward the commutator (18). The front end of the carbon brush (2) is used to slide in contact with the commutator (18). A connecting cap (12) is set on the back of the carbon brush (2). The connecting cap (12) has two sets of flanged lugs (13) so that the two flanged lugs (13) can serve as load areas. The differential support (9) generates differential motion within a limited range relative to the brush holder housing (1) via the intermediate shaft (6), and the two ends of the differential support (9) are output ends; Two connectors (11) are respectively connected between the two output ends of the differential support (9) and the two sets of flanged lugs (13) to form two spatially separated pressure transmission paths; The main preload elastic element (4) is disposed between the brush holder housing (1) and the differential support (9) to provide a common preload load to the differential support (9), so that the differential support (9) transmits the preload force to two different load areas on the back of the carbon brush (2) through two connectors (11); When the two load areas of the carbon brush (2) are displaced relative to each other due to the local geometric disturbance of the commutator (18), the differential support (9) can swing around the intermediate shaft (6) in a restricted manner, so that the two connecting parts (11) can generate controlled differential displacement to absorb the relative displacement on both sides of the carbon brush (2) and achieve self-balancing of contact pressure; while when the carbon brush (2) is worn normally, the carbon brush (2) can move as a whole along the wear feed direction.

2. The differential self-balancing carbon brush contact pressure regulating mechanism according to claim 1, characterized in that: The connector (11) is a short connecting rod, and the two ends of the short connecting rod are rotatably connected to the end of the differential support (9) and the flanged lug (13), respectively.

3. The differential self-balancing carbon brush contact pressure regulating mechanism according to claim 1, characterized in that: The differential support (9) is a rigid rocker arm structure, and the intermediate shaft (6) passes through the middle of the differential support (9).

4. The differential self-balancing carbon brush contact pressure regulating mechanism according to claim 1, characterized in that: The differential support (9) is an integrated flexible equalizer with a central force-bearing area and two branch output arms. The two branch output arms are connected to the central force-bearing area through a thin-walled flexible area.

5. The differential self-balancing carbon brush contact pressure regulating mechanism according to claim 1, characterized in that: It also includes a reset elastic element (8), which is disposed between the differential support (9) and the intermediate shaft (6) to provide a reset torque after the differential support (9) swings.

6. The differential self-balancing carbon brush contact pressure regulating mechanism according to claim 5, characterized in that: The differential support (9) has a mounting groove (10) on its top surface. The two ends of the reset elastic member (8) are placed in the mounting groove (10) and can slide in the mounting groove (10).

7. The differential self-balancing carbon brush contact pressure regulating mechanism according to claim 1, characterized in that: Two differential stroke limiters (3) are provided on the brush holder housing (1). A guide slot (7) is formed between the two differential stroke limiters (3). The carbon brush (2) is installed between the two differential stroke limiters (3) and can be displaced along the circumference of the commutator (18). An initial gap is maintained between the differential stroke limiters (3) and the carbon brush (2) to limit the excessive swing of the carbon brush (2) during abnormal impact.

8. The differential self-balancing carbon brush contact pressure regulating mechanism according to claim 7, characterized in that: The brush holder housing (1) is provided with a guide groove (16). The guide groove (16) and the guide slot (7) are arranged coaxially along the axial direction. The two ends of the intermediate shaft (6) are located in the guide groove (16) and the guide slot (7) respectively. An angle limiting boss (14) is provided at the end of the intermediate shaft (6) located in the guide groove (16) and the guide slot (7) to limit the maximum differential rotation angle of the differential support part (9). A positioning sleeve (15) is sleeved on the outside of the intermediate shaft (6) to limit the axial movement of the differential support part (9) relative to the intermediate shaft (6).

9. A brush assembly, characterized in that: It includes a brush holder housing (1), a carbon brush (2), and a differential self-balancing carbon brush contact pressure adjustment mechanism as described in claims 1 to 8.

10. The brush assembly according to claim 9, characterized in that: The flexible conductive connector of the carbon brush (2) is led out from the guide slot (7).

11. A brushed motor, characterized in that: Includes a rotor, a commutator (18) disposed on the rotor, and a brush assembly as described in claim 9 or 10, wherein the carbon brush (2) forms a sliding electrical contact with the commutator (18) under the action of the main preload elastic member (4), and the differential support (9) is capable of reversible differential response to local disturbances in two directions.

12. A method for self-balancing carbon brush contact pressure in a brushed motor, characterized in that: Includes the following steps: A common preload is applied to the differential support (9) through the main preload elastic element (4); Through the two output ends of the differential support (9), the common preload is transmitted to the two sets of flanged lugs (13) of the connecting cap (12) via the two connectors (11), so that the two spatially separated load areas on the back of the carbon brush (2) are simultaneously subjected to preload force to maintain the contact between the carbon brush (2) and the commutator (18). When the local geometric disturbance of the commutator (18) causes relative displacement between the two load areas of the carbon brush (2), the differential support (9) swings around its central axis (6) in a restricted manner, causing the two connecting parts (11) to generate controlled differential displacement, so as to absorb the relative displacement between the two sides of the carbon brush (2), thereby reducing the transient pressure difference between the two load areas and realizing the passive self-balancing of the contact pressure.

13. The self-balancing method for carbon brush contact pressure of a brushed motor according to claim 12, characterized in that: It also includes the following steps: After the differential support (9) swings, a reverse reset torque is provided by the reset elastic element (8) to return the differential support (9) to the neutral position; As the carbon brush (2) gradually wears down and shortens, the main preload elastic element (4) continuously applies a load to the differential support (9), pushing the carbon brush (2) toward the commutator (18) to compensate for the wear. When the contact surface of the carbon brush (2) is disturbed by a local surface, the connector (11) on the corresponding side will first give way, causing the differential support (9) to swing to the opposite side, so that the connector (11) on the other side continues to fit.

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