Motor shaft structure, motor and vehicle

Abstract

The utility model provides a motor shaft structure, a motor and a vehicle, and belongs to the technical field of vehicle parts, the motor shaft structure comprises a shaft body and a target wheel; one end of the shaft body is inserted into an inner ring of the bearing in the mounting cavity, and a preset gap is formed between the shaft body and the inner ring; the target wheel comprises a body and a detection part radially protruding out of the body, the body is in interference fit with the other end of the shaft body, and the detection part rotates along with the shaft body and is located on a detection path of the angle detection part in the mounting cavity. According to the motor shaft structure provided by the utility model, the preset gap is formed between the shaft body and the inner ring, thereby facilitating the reduction of the influence of the bearing clearance on the rotation of the target wheel, facilitating the prevention of the inclination of the shaft body and the target wheel on the shaft body, and facilitating the improvement of the detection precision of the angle detection part on the rotating speed of the shaft body. And the body of the target wheel is in interference connection with the other end of the shaft body, so that the mounting convenience of the target wheel is improved.

Description

Technical Field

[0001] This utility model relates to the field of vehicle technology, and in particular to a motor shaft structure; it also relates to a motor and a vehicle equipped with the motor shaft structure. Background Technology

[0002] Currently, to obtain the motor's rotational speed, angle sensors are needed to provide the motor's rotational angle position signal, and displacement sensors are needed to obtain the displacement signal. Commonly used angle sensors include Hall effect, magnetoresistive, eddy current, and resolver types. Among them, eddy current sensors are widely used due to their advantages such as strong anti-interference ability, high accuracy, simple structure, and small size, to provide feedback on the motor's rotational angle. Using an eddy current angle sensor requires a matching target wheel to be installed on the motor shaft.

[0003] However, in existing technologies, the target wheel is set on the motor shaft, and the runout of the target wheel is large, which makes it impossible for the eddy current sensor to obtain accurate angle information, thus affecting the accuracy of obtaining the motor speed. Utility Model Content

[0004] In view of this, the present invention aims to propose a motor shaft structure to reduce the runout of the target wheel.

[0005] To achieve the above objectives, the technical solution of this utility model is implemented as follows:

[0006] A motor shaft structure is disposed in the mounting cavity of a motor housing, the motor shaft structure comprising a shaft body and a target wheel;

[0007] One end of the shaft is inserted into the inner ring of the bearing in the mounting cavity, and a preset gap is formed between the shaft and the inner ring.

[0008] The target wheel includes a body and a detection portion that protrudes radially outward from the body. The body is interference-fitted to the other end of the shaft, and the detection portion rotates with the shaft and can be located on the detection path of the angle detection portion within the mounting cavity.

[0009] Furthermore, the shaft body is a hollow shaft; and / or, the body is press-fitted into the shaft body.

[0010] Furthermore, the body has a connecting portion that is press-fitted into the shaft body, and a limiting portion that protrudes radially outward relative to the connecting portion; the limiting portion is used to limit the displacement of the connecting portion within the shaft body.

[0011] Furthermore, the main body is provided with a plurality of detection portions spaced apart in the circumferential direction; the detection portions include fan-shaped blades.

[0012] Furthermore, the body has five blades spaced apart circumferentially; the central angle α of each blade satisfies: 50°≤α≤55°, and the central angle β of the interval region between two adjacent blades satisfies: 17°≤β≤22°.

[0013] Furthermore, one end of the shaft is provided with an axially outward protruding portion, and the shaft is connected to the inner ring through the protruding portion. The preset gap D is formed between the protruding portion and the inner ring. The end face of the shaft can abut against the inner ring, thereby restricting the displacement of the protruding portion in the inner ring.

[0014] Furthermore, the preset gap D is between 8μm and 12μm; and / or, the body is provided with a cavity that extends through both ends.

[0015] Compared with the prior art, this utility model has the following advantages:

[0016] The motor shaft structure described in this utility model, by forming a preset gap between the shaft and the inner ring, helps to reduce the influence of bearing clearance on the rotation of the target wheel. Furthermore, the windings of the motor stator generate a magnetic field, and the permanent magnets of the motor rotor mounted on the shaft cause the motor rotor to rotate in a centered position under the influence of this magnetic field. This, in turn, centers the shaft within the inner ring, preventing tilting of the shaft and the target wheel. This also improves the accuracy of the angle detection unit in detecting the shaft's rotational speed. Additionally, by setting an interference fit between the target wheel body and the other end of the shaft, compared to welding, the installation process of the target wheel is simplified, making it easier to install and avoiding thermal deformation caused by welding, thus ensuring the reliability of the target wheel.

[0017] Secondly, the shaft is hollow. The more uniform mass distribution of the hollow shaft stabilizes the centrifugal force generated during rotation, reducing shaft runout caused by mass imbalance. This, in turn, reduces errors in the angle detection unit. Furthermore, the hollow shaft reduces weight and provides more space for the installation of other components, while also improving heat dissipation. The main body is interference-fitted into the shaft, ensuring a more reliable connection and guaranteeing synchronous rotation between the target wheel and the shaft, thereby improving the stability and transmission accuracy of the motor shaft structure. The interference fit of the main body into the shaft via the connecting part facilitates an interference connection between the main body and the shaft. The inclusion of a limiting part to control the displacement of the connecting part within the shaft further enhances the connection stability and ensures the connecting part is properly installed within the shaft.

[0018] Furthermore, multiple detection sections are spaced apart circumferentially on the main body. When the shaft rotates, the angle detection unit can detect the passage of the detection sections more frequently. Each time a detection section passes the detection section, a corresponding detection signal is generated, allowing the angle detection unit to more accurately capture the rotational state of the shaft, thereby improving the detection accuracy of the shaft speed. The fan-shaped blades have a simple structure, are easy to form, and work well with the angle detection unit. The five blades, and the range of the central angle α of the blades and the range of the central angle of the interval area, allow each blade to generate a waveform with only a 17°-22° rotation. While ensuring that the blades have sufficient area and angle, this helps to reduce the influence of irregular movement of the target wheel. Moreover, the small jump caused by each small blade also helps to improve the quality of the waveform generated by the angle detection unit, thus improving the detection accuracy of the angle detection unit.

[0019] Furthermore, by providing a protruding portion on the shaft to connect with the inner ring, the connection between the shaft and the inner ring is facilitated, ensuring that the end face of the shaft abuts against the inner ring and that the protruding portion is properly inserted into the inner ring. When the preset gap D is in the range of 8μm-12μm, it provides sufficient space for the shaft to accommodate minor displacements caused by bearing clearance, while preventing excessive shaft wobble due to an excessively large preset gap D. If the preset gap D is less than 8μm, the shaft and inner ring will fit too tightly, leading to increased friction, energy loss, and even jamming due to heat expansion during operation. If the preset gap is greater than 12μm, the shaft's rotational stability will decrease, generating vibration and noise, and reducing rotational accuracy, thus affecting the overall performance of the motor. The hollow cavity within the main body not only facilitates connection but also allows for lightweight design of the target wheel.

[0020] In addition, another objective of this utility model is to provide an electric motor, including a motor housing with a mounting cavity, a bearing disposed in the mounting cavity, and a motor shaft structure as described above.

[0021] Furthermore, the motor housing is provided with a bearing mounting groove and a limiting nut that is screwed to the bearing mounting groove; the limiting nut is used to constrain the bearing in the bearing mounting groove.

[0022] The motor described in this utility model, by setting the motor shaft structure as described above, facilitates the detection of the motor speed and has high detection accuracy.

[0023] Furthermore, by setting a limit nut to constrain the bearing in the bearing mounting groove, the technical advantages of simple operation and easy bearing disassembly are achieved.

[0024] Furthermore, this utility model also proposes a vehicle equipped with the aforementioned motor.

[0025] The vehicle described in this utility model, by incorporating the aforementioned motor, improves the vehicle's performance. Attached Figure Description

[0026] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings:

[0027] Figure 1 This is a schematic diagram of the motor shaft structure described in Embodiment 1 of this utility model;

[0028] Figure 2 for Figure 1 Enlarged view of part A in the image;

[0029] Figure 3 This is a schematic diagram of the target wheel and angle detection unit described in Embodiment 1 of this utility model from one viewpoint;

[0030] Figure 4 This is a schematic diagram of the target wheel and angle detection unit described in Embodiment 1 of this utility model from another perspective.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. Shaft; 2. Target wheel; 3. Motor housing; 4. Bearing; 5. Limit nut; 6. Angle detection unit;

[0033] 101. Protruding part;

[0034] 201. Body; 2011. Connecting part; 2012. Limiting part; 202. Blade; 203. Spacing area;

[0035] 301. Installation cavity;

[0036] 401, Outer ring; 402, Inner ring. Detailed Implementation

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments of the present invention can be combined with each other.

[0038] In the description of this utility model, it should be noted that if terms such as "upper," "lower," "inner," or "back" appear, indicating orientation or positional relationship, they are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, if terms such as "first" or "second" appear, they are also used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] Example 1

[0041] This embodiment relates to a motor shaft structure, which optimizes its own structure to solve the problem of low detection accuracy of the angle detection unit 6 due to the large runout of the target wheel 2.

[0042] In terms of overall structure, the motor shaft structure is located within the mounting cavity 301 of the motor housing 3. The motor shaft structure includes a shaft body 1 and a target wheel 2. One end of the shaft body 1 is inserted into the inner ring 402 of the bearing 4 within the mounting cavity 301, and a preset gap D is formed between the shaft body 1 and the inner ring 402. The target wheel 2 includes a body 201 and a detection portion that protrudes radially outward from the body 201. The body 201 is interference-fitted with the other end of the shaft body 1, and the detection portion rotates with the shaft body 1, thus being positioned on the detection path of the angle detection portion 6 within the mounting cavity 301.

[0043] The motor shaft structure described in this embodiment forms a preset gap D between the shaft body 1 and the inner ring 402, which helps to reduce the influence of the bearing 4 clearance on the rotation of the target wheel 2. Furthermore, the windings of the motor stator generate a magnetic field, and the permanent magnet of the motor rotor set on the shaft body 1 rotates in a centered manner under the action of the magnetic field, thereby centering the shaft body 1 in the inner ring 402. This helps to prevent the shaft body 1 and the target wheel 2 on it from tilting, and thus improves the detection accuracy of the angle detection unit 6 in detecting the rotational speed of the shaft body 1. By setting the body 201 of the target wheel 2 to the other end of the shaft body 1 with an interference fit, compared with the welding connection method, the installation process of the target wheel 2 can be simplified, and the thermal deformation caused by welding can be avoided, thereby ensuring the reliability of the target wheel 2.

[0044] Based on the above overview, this embodiment presents an exemplary structure in which the motor shaft structure is arranged within the motor housing 3. Figure 1 As shown in the image.

[0045] In a preferred embodiment, the shaft 1 is a hollow shaft. The more uniform mass distribution of the hollow shaft makes the centrifugal force generated during rotation more stable, which helps to reduce the runout of the shaft 1 caused by mass imbalance, thereby reducing the error caused by the angle detection unit 6. Moreover, the hollow shaft not only reduces weight but also increases the space for the installation of other components. Furthermore, the hollow shaft design also helps to improve the heat dissipation effect of the shaft 1.

[0046] Reference Figure 1As shown in the diagram, in this embodiment, one end of the shaft 1 has an axially outwardly protruding portion 101. The shaft 1 is inserted and connected to the inner ring 402 through the protruding portion 101, and a preset gap D is formed between the protruding portion 101 and the inner ring 402. The end face of the shaft 1 can abut against the inner ring 402, thus limiting the displacement of the protruding portion 101 within the inner ring 402. In this embodiment, by providing a protruding portion 101 on the shaft 1 for insertion and connection with the inner ring 402, it is beneficial to ensure the ease of connection between the shaft 1 and the inner ring 402, so that the end face of the shaft 1 abuts against the inner ring 402, which helps to ensure that the protruding portion 101 is properly inserted into the inner ring 402.

[0047] The cross-sectional area of ​​the protruding portion 101 is smaller than the transverse area of ​​the shaft body 1. This ensures that the end face of the shaft body 1 can abut against the inner ring 402 of the bearing 4, thereby limiting the insertion depth of the protruding portion 101. In addition, to facilitate the insertion of the protruding portion 101 into the inner ring 402, a guide surface inclined along its circumference is provided at the free end of the protruding portion 101.

[0048] During motor operation, shaft 1 will expand and contract due to thermal effects from current and mechanical friction, and operational vibration will also cause deformation. The clearance of bearing 4 can absorb the expansion of shaft 1, buffer impacts, prevent jamming or excessive wear caused by changes in the dimensions of shaft 1, reduce runout error during shaft 1 rotation, and ensure stable motor operation. If the clearance is too small, bearing 4 will experience increased wear due to frictional heat during operation, and may even cause malfunctions; if the clearance is too large, it will cause greater vibration and noise during motor operation, and reduce rotational accuracy.

[0049] Combination Figure 1 and Figure 2 As shown, the preset gap D is between 8μm and 12μm. When the preset gap D is within the range of 8μm to 12μm, it provides sufficient room for the shaft 1 to accommodate the small displacements caused by the bearing 4 clearance, without causing excessive wobbling of the shaft 1 due to an excessively large preset gap D. In this embodiment, the setting of the preset gap D range also ensures that the shaft 1 and the inner ring 402 are subjected to uniform force. When the shaft 1 rotates, it will not generate excessive local pressure on the inner ring 402 due to an unreasonable preset gap D, thereby reducing the wear of the bearing 4.

[0050] Specifically, if the preset gap D is less than 8μm, the fit between the shaft 1 and the inner ring 402 will be too tight. During operation, the heat and expansion will increase friction, energy loss, and may even cause jamming. If the preset gap D is greater than 12μm, the rotational stability of the shaft 1 will decrease, generating vibration and noise, reducing rotational accuracy, and affecting the overall performance of the motor. In this embodiment, the value of the preset gap D can be, for example, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 10.5μm, 11μm, 11.5μm, or 12μm, etc. In specific implementation, the value of the preset gap D can be determined according to the usage requirements.

[0051] In a preferred embodiment, the body 201 is interference-fitted into the shaft 1. This interference fit ensures a more reliable connection, guaranteeing synchronous rotation between the target wheel 2 and the shaft 1, thereby improving the stability and transmission accuracy of the motor shaft structure. Secondly, the pressing process is relatively simple compared to complex processes such as welding, snap-fitting, bolting, and other methods. This reduces the number of parts and assembly steps, improves production efficiency, and lowers production costs. Furthermore, the interference fit ensures the concentricity of the body 201 and the shaft 1, promoting a uniform distribution of the internal magnetic field of the motor, reducing vibration and noise during operation, and improving motor performance and operating efficiency.

[0052] Reference Figure 1 and Figure 4 As shown, the body 201 has a connecting portion 2011 that is press-fitted into the shaft 1, and a limiting portion 2012 that protrudes radially outward relative to the connecting portion 2011. The limiting portion 2012 is used to limit the displacement of the connecting portion 2011 within the shaft 1. Here, the body 201 is press-fitted into the shaft 1 by the connecting portion 2011, which facilitates the interference connection between the body 201 and the shaft 1. By setting the limiting portion 2012 to limit the displacement of the connecting portion 2011 within the shaft 1, the connection stability between the body 201 and the shaft 1 is improved, and the connecting portion 2011 is properly installed within the shaft 1. Structurally, the limiting portion 2012 is a radially outward protrusion. The diameter of the connecting portion 2011 is smaller than the diameter of the limiting portion 2012, allowing the limiting portion 2012 to abut against the end face of the shaft 1, thereby limiting the connection length of the connecting portion 2011 within the shaft 1.

[0053] In a preferred embodiment, the body 201 has a cavity extending through both ends. This cavity in the body 201 not only facilitates connection but also promotes lightweight design. Furthermore, besides press-fitting the connecting portion 2011 into the shaft 1, the connecting portion 2011 can also be press-fitted onto the end of the shaft 1, as long as an interference fit is achieved between the connecting portion 2011 and the shaft 1.

[0054] In this embodiment, the arrangement relationship between the target wheel 2 and the angle detection unit 6 is as follows: Figure 3 and Figure 4As shown in the diagram, the main body 201 has multiple detection sections spaced apart circumferentially. Each detection section includes a fan-shaped blade 202. With multiple detection sections spaced apart circumferentially on the main body 201, the angle detection unit 6 can detect the passage of the detection sections more frequently when the shaft 1 rotates. Each time a detection section passes through a detection section, a corresponding detection signal is generated, allowing the angle detection unit 6 to more accurately capture the rotational state of the shaft 1, thereby improving the detection accuracy of the shaft 1's rotational speed. The fan-shaped blade 202 has a simple structure, is easy to mold, and works well with the angle detection unit 6.

[0055] Specifically, the arrangement of multiple blades 202 gives the target wheel 2 a petal-like shape. The multiple blades 202 are coplanar and parallel to the cross-section of the body 201. In this embodiment, the target wheel 2 is made entirely of metal, such as stainless steel or aluminum. The material of the target wheel 2 can be selected according to the specific application requirements. The angle detection unit 6 can use an eddy current sensor from the prior art. It has a ring-shaped main body and radially protruding protrusions from the main body. The detection part corresponds one-to-one with the main body in the axial direction of the shaft 1 to ensure that the eddy current sensor can accurately detect the detection part.

[0056] Eddy current sensors operate based on the principle of electromagnetic induction. When an alternating current flows through the coil of an eddy current sensor, an alternating magnetic field is generated around it. If there is a metal conductor nearby, i.e., the detection part, the alternating magnetic field will induce eddy currents in the metal conductor. These eddy currents will then generate their own magnetic fields, which interact with the magnetic field of the sensor coil, causing a change in the coil's impedance. By detecting the change in coil impedance, information related to the metal conductor can be obtained.

[0057] When shaft 1 drives target wheel 2 to rotate, the detection section passes sequentially through the eddy current sensor. Since target wheel 2 is made of metal (such as stainless steel or aluminum), when the detection section approaches the eddy current sensor, it causes a change in the magnetic field distribution around the sensor, generating eddy currents and resulting in a change in the coil impedance of the eddy current sensor. When the detection section moves away, the area without the detection section passes through the eddy current sensor, and the change in the magnetic field, eddy currents, and coil impedance is relatively small. Thus, as target wheel 2 rotates, the eddy current sensor periodically detects changes in coil impedance.

[0058] Specifically, the eddy current sensor converts the detected change in coil impedance into an electrical signal, the frequency of which is the same as the frequency at which the blade 202 passes the sensor. Since the detection components are evenly distributed on the target wheel 2, by measuring the frequency of the electrical signal, the number of times the blade 202 passes the sensor per unit time can be calculated, thus determining the rotational speed of the target wheel 2. Furthermore, because the target wheel 2 rotates synchronously with the shaft 1, the rotational speed of the shaft 1 can be indirectly obtained.

[0059] Since eddy current sensors require a certain metal area to generate a sufficient electromotive force for waveform feedback, an excessively small detection area or a small circumferential angle will affect the waveform quality. As a preferred embodiment, the body 201 has five blades 202 spaced circumferentially. The central angle α of each blade 202 satisfies: 50° ≤ α ≤ 55°, and the central angle β of the interval region 203 between adjacent blades 202 satisfies: 17° ≤ β ≤ 22°.

[0060] Specifically, the five blades 202 are arranged at equal angular intervals. In this embodiment, the careful setting of the range of the central angle α of the blades 202 and the range of the central angle β of the interval region 203 has significant advantages. The advantage is that each blade 202 only needs to rotate within an angle range of 17° to 22° to successfully generate a waveform. The setting of the angle range, while ensuring that the blades 202 have sufficient area and angle, is extremely beneficial in reducing the adverse effects caused by irregular movement of the target wheel 2.

[0061] Meanwhile, the relatively small runout amplitude caused by each small blade 202 during operation is a highly advantageous factor for improving the quality of the waveform generated by the angle detection unit 6. High-quality waveform generation significantly enhances the detection accuracy of the angle detection unit 6, ensuring more precise and reliable angle detection results throughout the system's operation, and providing a solid data foundation for subsequent work based on the angle detection data.

[0062] In specific implementations, the central angle α of each blade 202 can be, for example, 50°, 51°, 52°, 53°, 54°, or 54°, and the central angle β of the interval region 203 can be, for example, 17°, 18°, 19°, 20°, 21°, or 22°. Preferably, the central angle α of the blade 202 is 52°, and the central angle β of the interval region 203 is preferably 20°.

[0063] At this point, each blade 202 only needs to rotate 20° to generate a waveform. Because the rotation angle is small, the resulting fluctuation is minimal, greatly improving the quality of the waveform generated by the eddy current sensor. Therefore, in this embodiment, the target wheel 2, while ensuring sufficient area and optimizing the central angle of the blade 202, reduces the impact of irregular movement of the target wheel 2, thereby improving the detection accuracy of the eddy current sensor. Furthermore, the width of each blade 202 can be approximately 8mm, where the width of the blade 202 is equal to the difference between the outer radius of the blade 202 and the radius of the body 201. In specific implementations, the width of the blade 202 can also be adjusted according to usage requirements.

[0064] The motor shaft structure of this embodiment optimizes the structure of the shaft 1, the connection between the shaft 1 and the bearing 4, the setting of the preset gap D between the inner ring 402 and the shaft 1, and the setting of the target wheel 2 shape, which helps to reduce the runout error caused by the rotation of the shaft 1, improve the signal quality received by the eddy current sensor, and make the output waveform more accurate.

[0065] When an electric motor is used in an electro-hydraulic braking system, it helps reduce the rotational runout error of shaft 1, improves the signal quality of the eddy current sensor, and enables the eddy current sensor to output accurate waveforms. This helps the motor control system to accurately adjust parameters such as speed and torque. In braking scenarios, it achieves smooth braking, reduces the risk of vehicle loss of control, and thus improves the safety of the braking system.

[0066] Example 2

[0067] This embodiment relates to an electric motor, including a motor housing 3 with a mounting cavity 301, a bearing 4 disposed in the mounting cavity 301, and the motor shaft structure in Embodiment 1.

[0068] To facilitate the installation of bearing 4, a bearing mounting groove is provided on the motor housing 3, and a limiting nut 5 is screwed into the bearing mounting groove. The limiting nut 5 is used to constrain bearing 4 in the bearing mounting groove. (Referring to...) Figure 1 As shown, the end face of the outer ring 401 of the bearing 4 abuts against the bottom of the bearing mounting groove. The groove opening of the bearing mounting groove has an internal thread, and the outer peripheral wall of the limiting nut 5 has an external thread and is hollow inside. The limiting nut 5 is connected to the bearing mounting groove by a screw thread, allowing it to approach the outer ring 401 of the bearing 4.

[0069] When the limiting nut 5 abuts against the end face of the outer ring 401, it indicates that the limiting nut 5 is installed in place, and at this time, the outer ring 401 of the bearing 4 is fixed to the motor housing 3. The method of setting a bearing mounting groove to cooperate with the limiting nut 5 provides a good limiting effect for the installation of the bearing 4. Of course, in addition to using the limiting nut 5, other connection structures can also be used to fix the outer ring 401 of the bearing 4 to the motor housing 3, as long as the connection requirements are met.

[0070] Additionally, a limiting structure can be provided between the motor housing 3 and the shaft 1. This limiting structure is used to restrict the axial displacement of the shaft 1 away from the bearing 4. As one feasible implementation, the limiting structure includes a limiting protrusion radially protruding from the shaft 1 and a limiting boss located on the side of the limiting protrusion away from the bearing 4. A plurality of balls are provided on the limiting boss, arranged circumferentially around the shaft 1. The plurality of balls abut against the side of the limiting protrusion away from the bearing 4 to restrict the axial displacement of the shaft 1 away from the bearing 4.

[0071] In addition, by using ball bearings as part of the limiting structure, when the shaft 1 has an axial displacement tendency, the ball bearings and the limiting protrusions will have rolling friction. Compared with sliding friction, rolling friction has less frictional force, which can effectively reduce the frictional loss between the limiting structure and the shaft 1, which is conducive to reducing energy loss and thus improving the efficiency of the motor. It also helps to extend the service life of the limiting structure and the shaft 1.

[0072] The motor described in this embodiment, by setting the motor shaft structure as described above, facilitates the detection of the motor speed and has high detection accuracy.

[0073] Example 3

[0074] This embodiment relates to a vehicle equipped with the motor described in Embodiment 2.

[0075] In practical implementation, for example, the motor can be installed in the vehicle's electro-hydraulic braking system. In this case, the motor's location, installation method, and operating principle within the system can all refer to existing technologies. For instance, the ECU (Electronic Control Unit) of the electro-hydraulic braking system can obtain the motor's speed information through an eddy current sensor, thereby controlling the motor to complete the vehicle's braking operation. When the motor operates, the target wheel 2 on shaft 1 rotates together with the rotor. An alternating current is passed through the coil inside the eddy current sensor, generating an alternating magnetic field. The target wheel 2 generates eddy currents in the alternating magnetic field, and these eddy currents form their own magnetic fields, interacting with the sensor coil's magnetic field, causing a change in the coil's impedance. By detecting the periodic change frequency of the coil impedance, the ECU can accurately calculate the motor's speed.

[0076] In addition, the ECU, based on the vehicle's driving status (such as vehicle speed, acceleration, etc.) and the driver's braking intention (obtained through brake pedal travel sensors, etc.), combined with the motor speed information, sends precise control signals to the brushless motor after complex algorithm calculations, adjusts the motor's output torque in real time, and thus precisely controls the braking pressure of the electro-hydraulic braking system to complete the vehicle's braking operation and ensure driving safety.

[0077] The vehicle described in this embodiment, by incorporating the aforementioned motor, improves the vehicle's braking performance and safety.

[0078] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A motor shaft structure arranged in a mounting cavity (301) of a motor housing (3), characterized in that: the motor shaft structure comprises a shaft body (1) and a target wheel (2); one end of the shaft body (1) is inserted into an inner ring (402) of a bearing (4) in the mounting cavity (301), and a preset gap (D) is formed between the shaft body (1) and the inner ring (402); the target wheel (2) comprises a body (201) and a detection portion radially protruding from the body (201), the body (201) is interference connected with the other end of the shaft body (1), and the detection portion can be located on a detection path of an angle detection portion (6) in the mounting cavity (301) while rotating with the shaft body (1). 2.The motor shaft structure according to claim 1, characterized in that: the shaft body (1) is a hollow shaft; and / or, the body (201) is interference press-fitted in the shaft body (1). 3.The motor shaft structure according to claim 2, characterized in that: the body (201) has a connecting portion (2011) interference press-fitted in the shaft body (1), and a limiting portion (2012) radially protruding from the connecting portion (2011); and the limiting portion (2012) is used for limiting displacement of the connecting portion (2011) in the shaft body (1). 4.The motor shaft structure according to claim 1, characterized in that: a plurality of the detection portions are arranged at intervals in the circumferential direction of the body (201); and the detection portion comprises a fan-shaped blade (202). 5.The motor shaft structure according to claim 4, characterized in that: five blades (202) are arranged at intervals in the circumferential direction of the body (201); and a central angle α of each blade (202) satisfies 50°≤α≤55°, and a central angle β of an interval region (203) between adjacent two blades (202) satisfies 17°≤β≤22°. 6.The motor shaft structure according to claim 1, characterized in that: one end of the shaft body (1) is provided with an axially protruding protruding portion (101), the shaft body (1) is connected to the inner ring (402) through the protruding portion (101), and the preset gap (D) is formed between the protruding portion (101) and the inner ring (402); and an end surface of the shaft body (1) can abut on the inner ring (402) to limit displacement of the protruding portion (101) in the inner ring (402). 7.The motor shaft structure according to any one of claims 1 to 6, characterized in that: the preset gap (D) is between 8μm and 12μm; and / or, a cavity is arranged in the body (201) and extends through both ends. 8.A motor, characterized in that: it comprises a motor housing (3) having a mounting cavity (301), a bearing (4) arranged in the mounting cavity (301), and the motor shaft structure according to any one of claims 1 to 7. 9.The motor according to claim 8, characterized in that: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The motor housing (3) is provided with a bearing mounting groove, and a limiting nut (5) connected with the bearing mounting groove through screwing; The limiting nut (5) is used for restraining the bearing (4) in the bearing mounting groove.

10. A vehicle, characterized in that: The vehicle is provided with the motor of claim 8 or 9.

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