Method for calculating radial contact stiffness of brush head of shaft current derivation device

Abstract

The invention relates to a brush head radial contact stiffness calculation method of a shaft current derivation device. The method comprises the following steps: calculating the radial contact stiffness of a single brush head; and then calculating the total radial contact stiffness of the brush head. Through the design method, the contact force of the brush head is continuous and stable, and the manufacturing cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of motor manufacturing, and more specifically, to a method for calculating the radial contact stiffness of a shaft current derivation device. Background Art

[0002] Electrical corrosion is one of the factors that cause premature failure of the motor shaft. In engineering applications, grounding carbon brushes are usually used to eliminate the potential difference between the inner and outer rings of the shaft to prevent electrical corrosion of the motor shaft. However, the commonly used grounding carbon brushes have the disadvantages of being worn and requiring regular maintenance and replacement, and producing carbon powder that affects the insulation environment of the motor. To address this problem, carbon fiber brushes with good conductivity and wear resistance came into being.

[0003] The radial contact stiffness refers to the contact force between the brush head and the rotating shaft, which is mainly used to evaluate the current extraction rate of the shaft current extraction device, that is, the current extraction stability. At present, there is no relevant calculation for the radial contact stiffness in the existing technology, and it is impossible to evaluate the stability of the shaft current extraction device for current extraction.

[0004] Prior art CN202311442921.9 discloses a method for calculating the fatigue life of a rolling bearing taking into account shaft current damage, comprising: obtaining bearing structure design parameters and working load; establishing a force balance equation for the inner ring of the bearing according to the bearing structure design parameters and the working load, and generating a generalized displacement of each rolling element at any point; establishing a rolling bearing early shaft current micro-damage characterization model according to the bearing structure design parameters and the working load, substituting the generalized displacement into the rolling bearing early shaft current micro-damage characterization model, and generating a bearing contact deformation when shaft current damage is considered; establishing a bearing rolling element and inner and outer ring contact deformation at any point according to the bearing structure design parameters and the working load. A life calculation model under the condition of shaft current damage is established, and the bearing contact deformation when considering shaft current damage and the bearing structural design parameters are substituted into the life calculation model under the contact between the bearing rolling element and the inner and outer rings at any point, so as to generate the fatigue life of the bearing rolling element with shaft current damage, the fatigue life of the bearing inner ring and the fatigue life of the bearing outer ring contact point; a fatigue life calculation model of the rolling bearing considering shaft current damage is established according to the bearing structural design parameters and the working load, and the fatigue life of the bearing rolling element with shaft current damage, the fatigue life of the bearing inner ring and the fatigue life of the bearing outer ring contact point are substituted into the fatigue life calculation model of the rolling bearing considering shaft current damage, so as to generate the fatigue life of the rolling bearing with shaft current damage.

[0005] The comparative document establishes a rolling bearing fatigue life calculation model that takes into account shaft current damage, generates the fatigue life of rolling bearings with shaft current damage, explores the mapping relationship between the bearing shaft current damage mechanism and the evolution of the bearing defect shape, size and morphological characteristics, and serves as a reference for the life prediction of bearings with shaft current damage. It is instructive for predicting the dynamic performance and reliability of mechanical system operation and improving the accuracy of early fault diagnosis of bearings. That is, the comparative document still cannot solve the calculation of radial contact stiffness and cannot evaluate the stability of the shaft current derivation device for current derivation. Summary of the invention

[0006] The invention discloses a method for calculating the radial contact stiffness of a brush head of an axial current derivation device.

[0007] In order to solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0008] A method for calculating the radial contact stiffness of a brush head of an axial current derivation device, the method specifically comprising the following steps:

[0009] S1: Calculate the radial contact stiffness of a single brush head;

[0010]

[0011] Wherein, Zk is the cross-sectional coefficient of the carbon fiber bundle; E is the elastic modulus of the carbon fiber bundle; I is the cross-sectional moment of inertia of the carbon fiber bundle; R is the radius of the brush head; Φ is the diameter of the carbon fiber bundle;

[0012] S2: According to the total number of brush heads m, calculate the total radial contact stiffness of the brush head. The calculation method of the total radial contact stiffness is: k m =m*k r .

[0013] Preferably, the calculation method further comprises calculating the maximum value of the number of brush heads m:

[0014]

[0015] Where R is the bending radius of the brush head; Φ is the diameter of the carbon fiber bundle; and D refers to the inner diameter of the fixing bracket.

[0016] Preferably, the calculation method further includes calculating the compression amount when the brush head contacts the shaft on the fixed structure:

[0017]

[0018] Wherein, R is the bending radius of the brush head; Φ is the diameter of the carbon fiber bundle; D is the inner diameter of the fixed bracket; d is the outer diameter of the rotating part. According to the method for calculating the radial contact stiffness of the brush head of the shaft current derivation device of claim 1, it is characterized in that an annular groove is provided on the arc-shaped outer wall of the fixed bracket; first through holes are provided in the annular groove at intervals, and the diameters of the first through holes and the annular groove are adapted to the diameter of the carbon fiber bundle.

[0019] Preferably, the shaft current extraction device includes a circular fixed bracket with good conductive performance and a continuous carbon fiber bundle; the carbon fiber bundle is bent and arranged on the fixed bracket, and the arc portion of the carbon fiber bundle protruding from the inner wall of the fixed bracket constitutes a brush head in contact with the rotating shaft, and the extraction device also includes a baffle for fixing the carbon fiber bundle, and the baffle is connected to the fixed bracket.

[0020] Preferably, an annular groove for fixing the carbon fiber bundle is provided on the arc-shaped outer wall of the fixing bracket; first through holes connected to the inner wall of the fixing bracket are arranged at intervals in the annular groove, and the diameter of the first through holes is adapted to the diameter of the carbon fiber bundle; and a second through hole for fixing the tail of the carbon fiber bundle is also provided in the annular groove.

[0021] Preferably, the number of first through holes is 18 and the number of brush heads is 9.

[0022] Preferably, the cross section of the annular groove is semicircular, and the diameter of the annular groove is adapted to the diameter of the carbon fiber bundle.

[0023] Preferably, the baffle comprises a bending piece arranged on the arc-shaped outer wall of the fixing bracket; and slots are arranged between the connected bending pieces.

[0024] Preferably, the guide device further comprises a circular ring which is sleeved in the fixed bracket, and a semicircular convex column is arranged around one end surface of the circular ring, and the diameter of the convex column is consistent with the diameter of the brush head.

[0025] Preferably, the number of first through holes is 18 and the number of brush heads is 9.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. By calculating the radial contact stiffness of the brush head, the stability of the current extraction of the shaft current extraction device can be accurately evaluated; ultimately, the continuous stability of the current extraction of the shaft current extraction device is guaranteed.

[0028] 2. The brush head of the present invention adopts arc line contact, with a large contact area, small contact resistance with the rotating shaft, low brush head loss, stable and reliable contact state, and sufficient restoring force to maintain a good contact effect at high speed.

[0029] 3. The device of the present invention adopts a simple flanging and pressing fixing method and a continuous conductive fiber bundle, has a simple structure, does not require additional fixing parts, is easy to mass produce, and significantly reduces manufacturing costs.

[0030] 4. A method for manufacturing a semicircular "arch bridge type" elastic carbon fiber structure is proposed. By adjusting the number of semicircular brush heads and the size of the arc, the contact stiffness can be easily adjusted.

[0031] 5. The present invention adopts a U-shaped groove fixing bracket + a continuous integral carbon fiber bundle to form a plurality of semicircular "arch bridge-type" brush heads, so that the brush heads do not diverge, have good overall rigidity, and have strong rebound ability when subjected to contact force. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of a method for calculating radial contact stiffness of a brush head of an axial current derivation device of the present invention;

[0033] Figure 2 It is a structural schematic diagram of a fixed bracket of a method for calculating radial contact stiffness of a brush head of an axial current derivation device of the present invention;

[0034] Figure 3 It is a schematic diagram of the bending state of the carbon fiber bundle in the method for calculating the radial contact stiffness of the brush head of the axial current deriving device of the present invention;

[0035] Figure 4 It is a structural schematic diagram of a circular ring in a method for calculating radial contact stiffness of a brush head of an axial current derivation device of the present invention;

[0036] Figure 5 It is a left view of a fixed bracket in a method for calculating radial contact stiffness of a brush head of an axial current derivation device of the present invention;

[0037] Figure 6 It is a left view of the combination of the fixed support and the fiber bundle in the method for calculating the radial contact stiffness of the brush head of the axial current derivation device of the present invention;

[0038] Figure 7 It is a schematic diagram of the cross-sectional structure of the combination of the fixed support and the fiber bundle in the method for calculating the radial contact stiffness of the brush head of the axial current derivation device of the present invention;

[0039] Figure 8 The present invention is a flowchart of a method for calculating the radial contact stiffness of a brush head of an axial current derivation device. DETAILED DESCRIPTION

[0040] In order to clearly illustrate the technical features of the present solution, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0041] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0042] In addition, in the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0043] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] In the present application, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0045] Example 1

[0046] A method for calculating the radial contact stiffness of a brush head of an axial current derivation device is disclosed. The specific calculation method includes the following steps:

[0047] S1: Calculate the radial contact stiffness of a single brush head;

[0048]

[0049] Wherein, Zk is the cross-sectional coefficient of the carbon fiber bundle; E is the elastic modulus of the carbon fiber bundle; I is the cross-sectional moment of inertia of the carbon fiber bundle; R is the radius of the brush head; Φ is the diameter of the carbon fiber bundle;

[0050] S2: According to the total number of brush heads m, calculate the total radial contact stiffness of the brush head. The calculation method of the total radial contact stiffness is: k m =m*k r

[0051] The calculation method also includes calculating the maximum value of the number of brush heads m.

[0052]

[0053] Where R is the brush head radius; Φ is the diameter of the carbon fiber bundle; and D refers to the inner diameter of the fixing bracket.

[0054] Specifically, it also includes the calculation of the compression amount when the brush head contacts the shaft on the fixed structure;

[0055]

[0056] Where R is the brush head radius; Φ is the diameter of the carbon fiber bundle; D is the inner diameter of the fixed bracket; and d is the outer diameter of the rotating part.

[0057] Through the above calculations, the stability of the shaft current extraction device for current extraction can be accurately evaluated, effectively preventing electrical corrosion.

[0058] Example 2

[0059] like Figures 1 to 4 As shown, a method for calculating the radial contact stiffness of a brush head of an axial current extraction device is disclosed, wherein the extraction device comprises an annular fixed bracket 1 and a carbon fiber bundle; the carbon fiber bundle is bent and arranged on the fixed bracket 1, and the arc portion of the carbon fiber bundle protruding from the inner wall of the fixed bracket 1 constitutes a brush head 2 in contact with the rotating shaft, and the extraction device also comprises a baffle for fixing the carbon fiber bundle, and the baffle is connected to the fixed bracket 1.

[0060] In this embodiment, the fixed bracket 1 is set to be in an arc shape, and the carbon fiber bundle is bent and set on the fixed bracket 1. The arc portion of the carbon fiber bundle protruding from the inner wall of the fixed bracket 1 communicates with the brush head 2 in contact with the rotating shaft, and the brush head 2 is in contact with the rotating shaft (rotating part), thereby conducting static electricity on the rotating shaft and effectively preventing electrical corrosion of the rotating shaft. Because the brush head 2 is in contact with the rotating shaft, in order to prevent the carbon fiber bundle from shifting relative to the fixed bracket 1 due to the contact force between the rotating shaft and the brush head when the rotating shaft rotates, a baffle can also be set on the fixed bracket 1, and the carbon fiber bundle is fixed by the baffle, thereby effectively preventing the carbon fiber bundle from shifting relative to the fixed bracket 1, and ensuring effective contact between the brush head 2 and the rotating shaft.

[0061] The brush head 2 of the present invention adopts arc line contact, has a large contact area, small contact resistance with the rotating shaft, stable and reliable contact state, and has sufficient restoring force to maintain a good contact effect at high rotation speed.

[0062] Example 3

[0063] Disclosed is a method for calculating radial contact stiffness of a brush head of an axial current derivation device. The derivation device comprises an annular fixed bracket 1 and a carbon fiber bundle. The carbon fiber bundle is bent and arranged on the fixed bracket 1. The arc portion of the carbon fiber bundle protruding from the inner wall of the fixed bracket 1 constitutes a brush head 2 in contact with a rotating shaft. The derivation device also comprises a baffle for fixing the carbon fiber bundle, and the baffle is connected to the fixed bracket 1.

[0064] The difference between this embodiment and embodiment 1 is that: in order to facilitate the fixing of the carbon fiber bundle on the fixed bracket 1, an annular groove can be specifically provided on the arc-shaped outer wall of the fixed bracket 1, and first through holes 3 are arranged at intervals in the annular groove, and the first through holes 3 connect the annular groove and the arc-shaped inner wall of the fixed bracket 1, and the first through holes 3 are arranged at intervals. One end of the carbon fiber bundle is placed in the annular groove, and the other end passes through the first through holes 3 arranged at intervals in sequence. Finally, the carbon fiber bundle located on the arc-shaped outer wall side is just fixed in the annular groove, and the carbon fiber bundle located on the arc-shaped inner wall side forms a plurality of semicircular arc parts, and the arc parts constitute the brush head 2 in contact with the rotating shaft. At the same time, the diameters of the first through hole 3 and the annular groove just match the diameter of the carbon fiber bundle. Through this design, a number of semicircular "arch bridge-type" brush heads 3 are formed, so that the brush head 3 does not diverge, has good overall rigidity, and has strong rebound ability when subjected to contact force. Since the diameters of the annular groove and the first through hole are consistent with the diameter of the carbon fiber bundle, the carbon fiber bundle can be well fixed, thereby preventing the carbon fiber bundle from sliding relative to the fixed bracket 1 and ensuring that the brush head 2 is in contact with the rotating shaft.

[0065] In this embodiment, in order to further fix the carbon fiber bundle, a second through hole 4 for fixing the tail of the carbon fiber bundle can be provided in the annular groove. Specifically, the number of the first through holes 3 can be set to 18, so that when the carbon fiber bundle is bent, 9 brush heads 2 can be formed.

[0066] The brush head 2 of the present invention adopts arc line contact, has a large contact area, small contact resistance with the rotating shaft, stable and reliable contact state, and has sufficient restoring force to maintain a good contact effect at high rotation speed.

[0067] Example 4

[0068] Disclosed is a method for calculating radial contact stiffness of a brush head of an axial current derivation device. The derivation device comprises an annular fixed bracket 1 and a carbon fiber bundle. The carbon fiber bundle is bent and arranged on the fixed bracket 1. The arc portion of the carbon fiber bundle protruding from the inner wall of the fixed bracket 1 constitutes a brush head 2 in contact with a rotating shaft. The derivation device also comprises a baffle for fixing the carbon fiber bundle, and the baffle is connected to the fixed bracket 1.

[0069] The difference between this embodiment and the above embodiment is that the baffle specifically includes an annular sheet 5 arranged on the arc-shaped outer wall of the fixed bracket, and notches 6 are arranged at intervals on the annular sheet 5. The annular sheet 5 can rotate relative to the fixed bracket 1 under the action of external force. Specifically, the annular sheet 5 and the fixed bracket 1 are integrally formed. The annular sheet 5 bends and deforms under the action of external force, thereby covering the carbon fiber bundle in the annular groove. The purpose of providing the notches 6 is to facilitate the bending of the annular sheet 5.

[0070] In this embodiment, in order to ensure that the size of each brush head 2 is consistent, the guide device can also include a ring 7 for winding the brush head, and the outer diameter of the ring 7 is consistent with the inner diameter of the fixed bracket 1. A semicircular boss 8 is arranged around one end face of the ring 7, and the diameter of the boss 8 is consistent with the diameter of the brush head 2. First, the ring 8 is put on the fixed bracket 1, and then when the carbon fiber bundle passes from the first through hole 3 to the inner side of the arc of the fixed bracket 1, it passes through the annular groove from the second first through hole 3 around the boss 8, and finally, the carbon fiber bundle is bent in sequence. It uses a simple flanging and pressing fixing method, with a simple structure, no additional fixing parts are required, and it is convenient for mass production.

[0071] By adding a circular ring as a mold that can be disassembled at any time, the size of each brush head 2 is ensured to be consistent. At the same time, the winding time of the carbon fiber bundle is greatly saved, thereby improving the manufacturing efficiency of the device.

[0072] The fixed bracket 1 is a full ring, which fixes m semicircular fiber brush heads. The fixing structure of the fiber bundle is located in a U-shaped groove outside the fixed bracket, and the radius r and depth of the groove match the outer diameter φ of the fiber bundle. 2m+1 holes are opened radially in the center of the groove, of which 2m holes are evenly distributed fiber bundle positioning holes, that is, the first through hole 3. The 2m+1th hole is a finishing process hole, that is, the second through hole. The aperture matches the outer diameter φ of the fiber bundle; the angle between each two holes of the 2m holes is α, which matches the span of the fiber brush head. At the same time, in order to fix the fiber bundle by flanging, a process notch (notch) is opened on the retaining edge (thickness t) of the fixed bracket, and the retaining edge is divided into 2m+1 ears, which are used to fix the fiber bundle after bending; among them, the brush head No. 1 2 directly above corresponds to two ears (a normal ear is divided into two), one of which is used to fix the starting end of the fiber bundle. After the fiber bundle enters the 2mth hole, it passes through the 2m+1th hole (finishing process hole) to complete the winding of the fiber bundle, and the remaining ear pieces are bent to compact the fiber bundle.

[0073] The specific production process is as follows:

[0074] The production process requires a ring 7 with an outer diameter of D that matches the inner circle of the fixed bracket. The ring 7 has m semicircular protrusions 8 with a diameter of R evenly distributed along the circumference to form a uniform shape when the fiber bundle is wound.

[0075] At the beginning of production, the retaining edge of the fixed bracket 1 is in an unbent state. At this time, one end of the fiber bundle is passed through the first first through hole above, and the fixed ear piece corresponding to the outer circle is flanged and bent, and then the starting head of the fiber bundle is fixed.

[0076] The circular ring 7 is installed in the fixed bracket, and the fiber bundle is passed through the fiber bundle positioning hole of the fixed bracket along the circular ring 7. After the winding is completed, all the remaining retaining edges are bent to fix the fiber bundle, and the production is completed.

[0077] The above-mentioned arch bridge type carbon fiber brush head with elastic structure is soft enough to contact the rotating part, and has enough rigidity to ensure stable contact force during movement. When different numbers m and R are set to form arch bridge type carbon fiber brush heads of different sizes, the initial contact rigidity can be set and adjusted.

[0078] The same or similar numbers in the drawings correspond to the same or similar parts; the positional relationships described in the drawings are only for illustrative purposes and should not be construed as limitations on this patent. Obviously, the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for calculating the radial contact stiffness of a brush head of an axial current derivation device, characterized in that: The calculation method specifically comprises the following steps: S1: Calculate the radial contact stiffness of a single brush head; Wherein, Zk is the cross-sectional coefficient of the carbon fiber bundle; E is the elastic modulus of the carbon fiber bundle; I is the cross-sectional moment of inertia of the carbon fiber bundle; R is the radius of the brush head; Φ is the diameter of the carbon fiber bundle; S2: According to the total number of brush heads m, calculate the total radial contact stiffness of the brush head. The calculation method of the total radial contact stiffness is: k m =m*k r .

2. The method for calculating the radial contact stiffness of the brush head of the shaft current derivation device according to claim 1, characterized in that: The calculation method also includes calculating the maximum value of the number of brush heads m: Where R is the bending radius of the brush head; Φ is the diameter of the carbon fiber bundle; and D refers to the inner diameter of the fixing bracket.

3. The method for calculating the radial contact stiffness of the brush head of the shaft current derivation device according to claim 1, characterized in that: The calculation method also includes the calculation of the compression amount when the brush head contacts the shaft on the fixed structure: Where R is the bending radius of the brush head; Φ is the diameter of the carbon fiber bundle; D is the inner diameter of the fixed bracket; and d is the outer diameter of the rotating part. According to the method for calculating the radial contact stiffness of the brush head of an axial current derivation device according to claim 1, it is characterized in that an annular groove is provided on the arc-shaped outer wall of the fixed bracket; first through holes are arranged at intervals in the annular groove, and the diameters of the first through holes and the annular groove are adapted to the diameter of the carbon fiber bundle.

4. The method for calculating the radial contact stiffness of the brush head of the shaft current derivation device according to claim 1, characterized in that: The shaft current extraction device includes a circular fixed bracket and a carbon fiber bundle; the carbon fiber bundle is bent and arranged on the fixed bracket, and the arc portion of the carbon fiber bundle protruding from the inner wall of the fixed bracket constitutes a brush head in contact with the rotating shaft. The extraction device also includes a baffle for fixing the carbon fiber bundle, and the baffle is connected to the fixed bracket.

5. The method for calculating the radial contact stiffness of the brush head of the shaft current derivation device according to claim 4, characterized in that: An annular groove for fixing the carbon fiber bundle is arranged on the arc-shaped outer wall of the fixing bracket; first through holes connected to the inner wall of the fixing bracket are arranged at intervals in the annular groove, and the diameter of the first through holes is adapted to the diameter of the carbon fiber bundle; a second through hole for fixing the tail of the carbon fiber bundle is also arranged in the annular groove.

6. The method for calculating the radial contact stiffness of the brush head of the shaft current derivation device according to claim 5, characterized in that: The number of first through holes is 18, and the number of brush heads is 9.

7. The method for calculating the radial contact stiffness of the brush head of the shaft current derivation device according to claim 4, characterized in that: The cross section of the annular groove is semicircular, and the diameter of the annular groove is adapted to the diameter of the carbon fiber bundle.

8. The method for calculating the radial contact stiffness of the brush head of the shaft current derivation device according to claim 4, characterized in that: The baffle comprises a bending piece arranged on the arc-shaped outer wall of the fixing bracket; and slots are arranged between the connected bending pieces.

9. The method for calculating the radial contact stiffness of the brush head of the shaft current derivation device according to claim 4, characterized in that: The guide device also includes a circular ring which is sleeved in the fixed bracket, and a semicircular convex column is arranged around one end surface of the circular ring, and the diameter of the convex column is consistent with the diameter of the brush head.

10. The method for calculating the radial contact stiffness of the brush head of the shaft current derivation device according to claim 4, characterized in that: The number of first through holes is 18, and the number of brush heads is 9.

Images