A high-precision servo motor

Abstract

The present invention belongs to the field of motors, and provides a high-precision servo motor, wherein the front end of the motor rotor is connected with an inner rotating shaft and an outer rotating shaft in sequence; the outer side of the outer rotating shaft is provided with a support sleeve with a gap between the two, and the outer side of the inner rotating shaft is provided with a rotating sleeve and is fitted and fixedly connected; the outer side of the support sleeve is provided with a grating, and the grating includes an inner hub, an outer hub and spokes, and the inner hub and the outer hub are both fixedly connected to the rotating sleeve, and the spokes are floatingly connected between the inner hub and the outer hub through a telescopic connection assembly; the light emitter and the receiver of the encoder are respectively arranged on both sides of the plane where the grating is located. The high-precision servo motor provided by the present invention adopts a split grating, and each spoke is independent of each other. When the spoke expands, it is ensured that each spoke has the same expansion direction and expansion elongation, and there will be no situation where it cannot expand and is distorted and deformed, which is convenient for using a temperature compensation circuit or algorithm to correct the rotor angle error caused by temperature changes, thereby improving the accuracy of the encoder.

Description

Technical Field

[0001] The invention relates to a motor, in particular to a high-precision servo motor. Background Art

[0002] Servo motors are motors that can control the direction and angle of rotation of the motor. They are often used in areas that require precise positioning, such as robots and conveying devices. Servo motors rely on their own encoders to detect the position of their rotors, making it easier for the servo motor driver to accurately control the rotation angle of the rotor. Photoelectric encoders are commonly used encoders. The laser emitted by their light emitters passes through a grating that rotates synchronously with the rotor and reaches the receiver. When the grating rotates, the laser passing through the grating will be intermittent, and the laser signal received by the receiver will also be intermittent. The receiver converts the intermittent laser signal into a voltage fluctuation signal and sends it to the driver, which allows the driver to accurately detect the rotation angle of the rotor.

[0003] In the prior art, the outer hub, spokes and inner hub of the grating are integrated as a whole, and there are light-transmitting through holes between adjacent spokes, such as Figure 1 After the motor starts, its temperature rises. Affected by thermal expansion and contraction, this integral grating will be distorted under the action of internal stress. The distortion of the spokes will cause the shapes of the light-transmitting holes to change and vary in size. The intermittent intervals of the laser received by the receiver will be inconsistent, which will eventually affect the encoder's detection accuracy of the rotor's rotation angle.

[0004] In view of the above situation, the prior art generally adopts a temperature compensation circuit or algorithm to correct the rotor angle error caused by temperature change. However, there is a certain randomness in the spoke distortion caused by the internal stress generated by thermal expansion and contraction. Even if the temperature is raised to the same, the distortion direction and distortion amount of the spoke are different each time. The existing compensation circuit or algorithm cannot adapt to all deformation modes. Summary of the invention

[0005] The purpose of the present invention is to overcome the existing defects and provide a high-precision servo motor to solve the problem that the encoder's detection accuracy of the rotor rotation angle decreases due to deformation of the grating caused by thermal expansion and contraction in the current servo motor.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A high-precision servo motor comprises a motor housing, a motor rotor is arranged inside the motor housing, the front end of the motor rotor is connected to an inner rotating shaft, the inner rotating shaft extends to the outside of the motor housing, the front end of the inner rotating shaft is connected to an outer rotating shaft, and the axes of the motor rotor, the inner rotating shaft and the outer rotating shaft are collinear; the outer side of the outer rotating shaft is sleeved with a support sleeve, the support sleeve is fixedly connected to the motor housing through a first bracket, a gap is left between the outer rotating shaft and the support sleeve, the outer side of the inner rotating shaft is sleeved with a rotating sleeve, the rotating sleeve is fitted and fixedly connected to the inner rotating shaft; the outer side of the support sleeve is sleeved with a rotating sleeve A grating is provided, which includes an inner hub, an outer hub and spokes, the inner hub is fixedly connected to the end of the rotating sleeve, the outer side of the rotating sleeve is provided with a second bracket parallel to the grating, the outer hub is fixedly connected to the second bracket through a first synchronization block, and the spokes are floatingly connected between the inner hub and the outer hub through a telescopic connection component; the light emitter and the receiver of the encoder are respectively provided on both sides of the plane where the grating is located, the light emitter and the receiver are fixedly connected to the motor housing through a connecting component, and the connecting line of the light emitter and the receiver passes through the plane where the spokes are located.

[0008] Furthermore, the first bracket is an L-shaped bracket, two in number, symmetrically arranged on both sides of the support sleeve and located outside the grating.

[0009] Further, the telescopic connection assembly includes a first connecting block, the inner end face of the first connecting block is connected to the outer end face of the inner hub, a first cylinder body of a first telescopic cylinder is arranged in the middle of the outer end face of the first connecting block, and a first piston of the first telescopic cylinder is fitted with an inner end face of the spoke; a guide block and a second telescopic cylinder are symmetrically arranged on both sides of the inner end of the spoke, the guide block is fixedly connected to the first connecting block through the second connecting block, the guide block is fitted with a side face of the inner end of the spoke, the second cylinder body of the second telescopic cylinder is fixedly connected to the first connecting block through a third connecting block, and the second piston of the second telescopic cylinder is fitted with the other side face of the inner end of the spoke; the outer end of the spoke matches and fits with the inner side face of the outer hub.

[0010] Furthermore, a first spring is arranged between the first piston and the inner bottom surface of the first cylinder, and a second spring is arranged between the second piston and the inner bottom surface of the second cylinder.

[0011] Furthermore, an oil inlet is provided on the support sleeve, a first oil circuit is provided inside the support sleeve, an oil outlet is provided on the contact surface between the support sleeve and the inner hub, the oil inlet is connected to an oil supply device, a plurality of first oil guide ports are provided on the inner hub, one end of the first oil guide port is communicated with the oil outlet, the other end of the first oil guide port is communicated with the second oil guide port on the first connecting block, a second oil circuit is provided inside the first connecting block, one outlet of the second oil circuit is communicated with the third oil guide port on the first cylinder body, and the other outlet of the second oil circuit is communicated with the fourth oil guide port on the second cylinder body via the oil delivery hole on the third connecting block; the connections through which the hydraulic oil passes are all sealed.

[0012] Furthermore, a switching sleeve is arranged between the support sleeve and the inner hub, the inner side of the switching sleeve is sealed and fixedly connected to the support sleeve, the outer side of the switching sleeve is sealed and rotatably connected to the inner hub, and the switching sleeve is circumferentially provided with side through holes, which extend along the circumference of the switching sleeve and are not connected at the beginning and the end; the setting positions of the light emitter and the receiver of the encoder are outside the radiation range corresponding to the side through holes.

[0013] Furthermore, the circumferential extension angle of the side through hole is 270 degrees.

[0014] Furthermore, two annular guide rings are arranged in parallel on both sides of the plane where the spokes are located on the inner side surface of the outer hub, and the two annular guide rings are fixedly connected to the outer hub and leave a gap with the plane where the spokes are located.

[0015] Furthermore, two annular limit rings are arranged in parallel between the inner hub and the outer hub on both sides of the plane where the spokes are located, and the two annular limit rings are fixedly connected by a plurality of second synchronization blocks inserted at the spoke intervals and leave gaps with the plane where the spokes are located. The annular limit ring close to the motor housing is fixedly connected to the second bracket through a third synchronization block.

[0016] Furthermore, the connecting component includes a third bracket, on which two arms are arranged in parallel, the two arms are respectively located on both sides of the plane of the grating, and the light emitter and the receiver are respectively arranged at the ends of the two arms opposite to each other.

[0017] The present invention discloses a high-precision servo motor, which adopts a split grating. Each spoke is independent of each other. When the spoke expands, it is ensured that each spoke has the same expansion direction and expansion elongation, and the situation of being unable to expand and twisting and deforming will not occur. It is convenient to use a temperature compensation circuit or algorithm to correct the rotor angle error caused by temperature change, thereby improving the accuracy of the encoder. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 It is a schematic diagram of the structure of an integrated grating in the prior art;

[0020] Figure 2 It is a three-dimensional schematic diagram of the present invention Figure 1 ;

[0021] Figure 3 It is a three-dimensional schematic diagram of the present invention Figure 2 ;

[0022] Figure 4 It is a three-dimensional schematic diagram of the present invention Figure 3 ;

[0023] Figure 5 It is a three-dimensional partial enlarged schematic diagram of the present invention;

[0024] Figure 6 is a side cross-sectional schematic diagram of the present invention;

[0025] Figure 7 is a schematic diagram of a switching sleeve in the present invention;

[0026] Figure 8 It is a structural schematic diagram of the telescopic connection assembly in the present invention;

[0027] Fig. 9 It is a schematic diagram of the internal structure of the first cylinder body and the second cylinder body in the present invention;

[0028] Fig.10 It is a structural schematic diagram of the oil supply device in the present invention. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0030] like Figure 2-10As shown, a high-precision servo motor comprises a motor housing 1, a motor rotor is arranged inside the motor housing 1, an inner shaft 2 is connected to the front end of the motor rotor, the inner shaft 2 extends to the outside of the motor housing 1, an outer shaft 3 is connected to the front end of the inner shaft 2, and the axes of the motor rotor, the inner shaft 2 and the outer shaft 3 are collinear; a support sleeve 4 is sleeved on the outer side of the outer shaft 3, and the support sleeve 4 is fixedly connected to the motor housing 1 through a first bracket 5, the first bracket 5 is an L-shaped bracket, the number is two, symmetrically arranged on both sides of the support sleeve 4 and located on the outside of the grating, a gap is left between the outer shaft 3 and the support sleeve 4, a rotating sleeve 6 is sleeved on the outer side of the inner shaft 2, and the rotating sleeve 6 and the inner shaft are connected. The shaft 2 is fitted and fixedly connected; the outer side of the support sleeve 4 is provided with a grating, which includes an inner hub 7, an outer hub 8 and spokes 9. The inner hub 7 is fixedly connected to the end of the rotating sleeve 6. The outer side of the rotating sleeve 6 is provided with a second bracket 10 parallel to the grating. The outer hub 8 is fixedly connected to the second bracket 10 through a first synchronization block 11. The spokes 9 are floatingly connected between the inner hub 7 and the outer hub 8 through a telescopic connection assembly; the light emitter 12 and the receiver 13 of the encoder are respectively provided on both sides of the plane where the grating is located. The light emitter 12 and the receiver 13 are fixedly connected to the motor housing 1 through a connection assembly, and the connection line of the light emitter 12 and the receiver 13 passes through the plane where the spokes 9 are located. The connection assembly includes a third bracket 14, on which two arms 15 are arranged in parallel. The two arms 15 are respectively located on both sides of the plane of the grating, and the ends of the two arms 15 are respectively provided with the light emitter 12 and the receiver 13 opposite to each other.

[0031] The telescopic connection assembly includes a first connection block 16, the inner end face of the first connection block 16 is connected to the outer end face of the inner hub 7, the first cylinder body 17 of the first telescopic cylinder is arranged in the middle of the outer end face of the first connection block 16, and the first piston 18 of the first telescopic cylinder is fitted with the inner end face of the spoke 9; the inner end of the spoke 9 is symmetrically provided with a guide block 19 and a second telescopic cylinder on both sides, the guide block 19 is fixedly connected to the first connection block 16 through the second connection block 20, the guide block 19 is fitted with the side face of the inner end of the spoke 9, the second cylinder body 21 of the second telescopic cylinder is fixedly connected to the first connection block 16 through the third connection block 22, and the second piston 23 of the second telescopic cylinder is fitted with the other side face of the inner end of the spoke 9; the outer end of the spoke 9 is matched and fitted with the inner side face of the outer hub 8.

[0032] A first spring 24 is provided between the first piston 18 and the inner bottom surface of the first cylinder 17 , and a second spring 25 is provided between the second piston 23 and the inner bottom surface of the second cylinder 21 .

[0033] A switching sleeve 26 is arranged between the support sleeve 4 and the inner hub 7. The inner side of the switching sleeve 26 is sealed and fixedly connected to the support sleeve 4, and the outer side of the switching sleeve 26 is sealed and rotatably connected to the inner hub 7. The switching sleeve 26 is circumferentially provided with side through holes 27, and the circumferential extension angle of the side through holes 27 is 270 degrees; the setting position of the encoder's light emitter 12 and the receiver 13 is within 90 degrees outside the radiation range corresponding to the side through holes 27.

[0034] The support sleeve 4 is provided with an oil inlet, which is connected to an oil supply device. A first oil circuit is provided inside the support sleeve 4. An oil outlet communicating with the side through hole 27 is provided on the contact surface between the support sleeve 4 and the switching sleeve 26. The inner hub 7 is provided with a first oil guide port which is the same in number as the spokes 9. When the inner hub 7 rotates relative to the switching sleeve 26, one end of the first oil guide port is intermittently connected with the side through hole 27, and the other end of the first oil guide port is communicated with the second oil guide port on the first connecting block 16 on one side of an adjacent spoke. A second oil circuit is provided inside the first connecting block 16, and one outlet of the second oil circuit is communicated with the third oil guide port on the first cylinder body 17, and the other outlet of the second oil circuit is communicated with the fourth oil guide port on the second cylinder body 21 via the oil delivery hole on the third connecting block 22. The hydraulic oil can enter the inner cavity between the first cylinder body 17 and the first piston 18 and the inner cavity between the second cylinder body 21 and the second piston 23 respectively; the joints through which the hydraulic oil passes are all sealed.

[0035] The oil supply device includes an oil pump 28, which is connected to the oil inlet through an oil delivery pipe 29. A pressure relief valve 30 is provided on the oil delivery pipe 29 to adjust the oil pressure in the oil delivery pipe 29. When the oil pressure is higher than a set value, the pressure relief valve 30 opens to return excess oil in the oil delivery pipe 29 to the oil tank 32 through an oil return pipe 31 on the pressure relief valve 30. When the oil pressure is lower than a set value, the pressure relief valve 30 closes and the oil pump 28 increases the pumping volume to ensure that the oil pressure at the oil delivery pipe 29 and the oil inlet is constant. When the oil pump 28 is working, it draws oil from the oil tank 32 through an oil suction pipe 33.

[0036] The inner side of the outer hub 8 is provided with two annular guide rings 34 in parallel on both sides of the plane where the spokes 9 are located. The two annular guide rings 34 are fixedly connected to the outer hub 8 and leave a set gap with the plane where the spokes 9 are located, such as 1-2mm. Two annular limiting rings 35 are provided in parallel on both sides of the plane where the spokes 9 are located between the inner hub 7 and the outer hub 8. The two annular limiting rings 35 are fixedly connected through a plurality of second synchronization blocks 36 inserted at the intervals of the spokes 9 and leave a set gap with the plane where the spokes 9 are located, such as 1-2mm. The annular limiting ring 35 close to the motor housing 1 is fixedly connected to the second bracket 10 through the third synchronization block 37. The annular guide ring 34 and the annular limiting ring 35 can rotate synchronously with the grating and limit the spokes 9 together.

[0037] Working principle:

[0038] Since the grating of the invention is not an integral structure, the spokes thereon are independently arranged, and the spokes and the spokes and other components of the grating are independent of each other, and do not affect each other during thermal expansion and contraction. When the motor rotates, the motor drives the inner shaft and the outer shaft to rotate through the rotor, and the front end of the outer shaft can be equipped with a gear to output the power of the motor to the outside, and the inner shaft can drive the rotating sleeve to rotate, and the rotating sleeve directly drives the inner hub to rotate and drives the outer hub, the annular guide ring, and the annular limit ring to rotate through the second bracket, the first synchronous block, and the second synchronous block respectively, and the inner hub drives the spokes to rotate through the telescopic connection assembly.

[0039] When the motor rotor rotates, the first synchronization block, the second bracket, the grating and the rotating sleeve rotate synchronously. The first synchronization block and the second bracket will pass between the light emitter and the receiver at the ends of the two arms. In order to avoid affecting the laser between the light emitter and the receiver, under the condition of ensuring the strength of the material, the width of the second bracket along the circumference of the motor rotor is made less than or equal to the width of the spoke, and the second bracket is aligned with one of the spokes along the axial direction of the motor, so that the laser will not be blocked by the second bracket, and the second bracket will not interfere with the laser between the light emitter and the receiver when passing between the two.

[0040] When each spoke rotates to within a range of 270 degrees where the switching sleeve is provided with side through holes in the circumferential direction, the hydraulic oil enters the inner cavities of the first cylinder body and the second cylinder body; the first piston clamps the two end walls of the spoke with the outer hub under the dual force of the oil pressure and the first spring; the second piston clamps the two side walls of the spoke with the guide block under the dual force of the oil pressure and the second spring; thereby driving the spoke to rotate synchronously with the inner and outer hubs.

[0041] During this process, if the temperature rises, the spoke expands. If the spoke stretches along its length, it will squeeze the first piston in the opposite direction. Since the first spring is compressible and the inner cavity of the first cylinder is connected to the external oil delivery pipe, when the first piston compresses the first spring to retreat, part of the oil in the first cylinder will flow in the opposite direction to the oil delivery pipe, so that the oil pressure in the oil delivery pipe increases, the pressure relief valve works and returns part of the oil to the oil tank through the return pipe, thereby maintaining the oil pressure in the oil delivery pipe stable. This process enables the expansion and elongation of the spoke along the length direction. If the spoke stretches along its width, it will squeeze the second piston in the opposite direction. Since the second spring is compressible and the inner cavity of the second cylinder is connected to the external oil delivery pipe, when the second piston compresses the second spring to retreat, part of the oil in the second cylinder will flow in the opposite direction to the oil delivery pipe, so that the oil pressure in the oil delivery pipe increases, the pressure relief valve works and returns part of the oil to the oil tank through the return pipe, thereby maintaining the oil pressure in the oil delivery pipe stable. This process enables the expansion and elongation of the spoke along the width direction. Since there is a gap between each spoke and the annular guide ring and the annular limit ring, when the spoke expands and elongates along its height direction, the gap can accommodate its elongation. Therefore, when the spoke expands, it will not be unable to expand and twist and deform, thereby ensuring that each spoke has the same expansion direction and expansion elongation, making it easier to use a temperature compensation circuit or algorithm to correct the rotor angle error caused by temperature changes, thereby improving the accuracy of the encoder.

[0042] Similarly, when the temperature drops, the spokes will shrink. When the spokes shrink along their length, the first piston pushes forward under the action of the first spring and oil pressure, and more oil from the oil pump will enter the inner cavity of the first cylinder, thereby ensuring the pressing force of the first piston on the spokes and the clamping effect of the first piston and the outer hub on the spokes. When the spokes shrink along their width, the second piston pushes forward under the action of the second spring and oil pressure, and more oil from the oil pump will enter the inner cavity of the second cylinder, thereby ensuring the pressing force of the second piston on the spokes and the clamping effect of the second piston and the guide block on the spokes. When the spokes shrink along their height, their shrinkage process is not affected.

[0043] In short, when each spoke rotates to within a range of 270 degrees in which the side through holes are provided in the circumferential direction of the switching sleeve, the thermal expansion and contraction of the spoke can be realized without restriction, and no distortion or deformation will occur.

[0044] When each spoke rotates to within a 90-degree range where there are no side through holes in the switching sleeve along the circumferential direction, the oil path between the inner hub and the support sleeve is blocked by the switching sleeve at this time, and thus the oil path between the inner cavities of the first cylinder body and the second cylinder body and the oil delivery pipe is cut off, and the oil in the inner cavities of the first cylinder body and the second cylinder body cannot flow in and out freely. Due to the incompressibility of the oil, the first piston and the second piston cannot retreat, and the vacuum in the inner cavities of the first cylinder body and the second cylinder body will also prevent the first piston and the second piston from pushing forward. At this time, the first piston and the second piston cannot move in the corresponding cylinder body, so that the clamping force on the spokes is constant, ensuring that the spokes are stable in shape when passing through the light emitter and the receiver, which is beneficial to improving the signal acquisition accuracy of the receiver.

[0045] In summary, during the rotation of each spoke, 270 degrees in each circle can expand and contract freely, while the other 90 degrees cannot expand and contract, which not only realizes the free expansion and contraction of the spokes to prevent them from twisting and deformation, but also ensures the stability of the receiver's signal collection, killing two birds with one stone. Therefore, during the rotation of each spoke, 75% of the time can achieve free expansion and contraction, which, compared with the existing technology, enables each spoke to have a longer self-adjustment time for expansion and contraction, further preventing the distortion and deformation of the spokes.

[0046] As a preference, the circumferential extension angle θ of the side through hole is in the range of 0<θ≤360°, which can realize the free thermal expansion and contraction of each spoke. The larger the extension angle θ is, the higher the available time proportion for thermal expansion and contraction is. Therefore, the extension angle θ can be set according to the working environment of the motor, such as temperature and vibration. The greater the temperature difference between working and non-working, the larger the extension angle θ is set, so that each spoke has a greater proportion of time to expand and contract. The greater the vibration during operation, the smaller the extension angle θ is set, and the greater the proportion of time that the clamping force on the spoke is constant, which is beneficial to reduce the impact of vibration on the spoke, making the spoke more stable in shape when passing through the light emitter and the receiver, further improving the signal acquisition accuracy of the receiver.

[0047] The present invention discloses a high-precision servo motor, which adopts a split grating. Each spoke is independent of each other. When the spoke expands, it is ensured that each spoke has the same expansion direction and expansion elongation, and the situation of being unable to expand and twisting and deforming will not occur. It is convenient to use a temperature compensation circuit or algorithm to correct the rotor angle error caused by temperature change, thereby improving the accuracy of the encoder.

[0048] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-precision servo motor, characterized in that: The motor housing comprises a motor rotor disposed inside the motor housing, the front end of the motor rotor is connected to an inner rotating shaft, the inner rotating shaft extends to the outside of the motor housing, the front end of the inner rotating shaft is connected to an outer rotating shaft, and the axes of the motor rotor, the inner rotating shaft and the outer rotating shaft are collinear; The outer side of the outer shaft is provided with a support sleeve, which is fixedly connected to the motor housing through a first bracket, and a gap is left between the outer shaft and the support sleeve. The outer side of the inner shaft is provided with a rotating sleeve, which is fixedly connected to the inner shaft. The outer sleeve of the support sleeve is provided with a grating, and the grating includes an inner hub, an outer hub and spokes. The inner hub is fixedly connected to the end of the rotating sleeve, and a second bracket parallel to the grating is provided on the outer side of the rotating sleeve. The outer hub is fixedly connected to the second bracket through a first synchronization block, and the spokes are floatingly connected between the inner hub and the outer hub through a telescopic connection assembly; The light emitter and receiver of the encoder are respectively arranged on both sides of the plane where the grating is located. The light emitter and the receiver are fixedly connected to the motor housing through a connecting component, and the connecting line of the light emitter and the receiver passes through the plane where the spokes are located; The telescopic connection assembly comprises a first connection block, the inner end surface of the first connection block is connected to the outer end surface of the inner hub, a first cylinder body of a first telescopic cylinder is arranged in the middle of the outer end surface of the first connection block, and a first piston of the first telescopic cylinder is fitted to the inner end surface of the spoke; A guide block and a second telescopic cylinder are symmetrically arranged on both sides of the inner end of the spoke, the guide block is fixedly connected to the first connecting block through the second connecting block, the guide block is in contact with the side surface of the inner end of the spoke, the second cylinder body of the second telescopic cylinder is fixedly connected to the first connecting block through the third connecting block, and the second piston of the second telescopic cylinder is in contact with the other side surface of the inner end of the spoke; The outer end of the spoke is fitted with the inner side of the outer hub; a first spring is arranged between the first piston and the inner bottom surface of the first cylinder, and a second spring is arranged between the second piston and the inner bottom surface of the second cylinder.

2. A high-precision servo motor according to claim 1, characterized in that: The first bracket is an L-shaped bracket, two in number, symmetrically arranged on both sides of the support sleeve and located outside the grating.

3. A high-precision servo motor according to claim 1, characterized in that: The support sleeve is provided with an oil inlet, a first oil circuit is provided inside the support sleeve, an oil outlet is provided on the contact surface between the support sleeve and the inner hub, the oil inlet is connected to an oil supply device, a plurality of first oil guide ports are provided on the inner hub, one end of the first oil guide port is communicated with the oil outlet, the other end of the first oil guide port is communicated with the second oil guide port on the first connecting block, a second oil circuit is provided inside the first connecting block, one outlet of the second oil circuit is communicated with the third oil guide port on the first cylinder body, and the other outlet of the second oil circuit is communicated with the fourth oil guide port on the second cylinder body via the oil delivery hole on the third connecting block; All connections through which the hydraulic oil passes are sealed.

4. A high-precision servo motor according to claim 3, characterized in that: A switching sleeve is arranged between the support sleeve and the inner wheel hub, the inner side of the switching sleeve is sealed and fixedly connected to the support sleeve, the outer side of the switching sleeve is sealed and rotatably connected to the inner wheel hub, and the switching sleeve is circumferentially provided with side through holes, which extend along the circumference of the switching sleeve and are not connected at the beginning and the end; The light emitter and the receiver of the encoder are arranged outside the radiation range corresponding to the side through hole.

5. A high-precision servo motor according to claim 4, characterized in that: The circumferential extension angle of the side through hole is 270 degrees.

6. A high-precision servo motor according to claim 1, characterized in that: The inner side surface of the outer hub is parallelly provided with two annular guide rings on both sides of the plane where the spokes are located. The two annular guide rings are fixedly connected to the outer hub and leave a gap with the plane where the spokes are located.

7. The high-precision servo motor according to claim 1, characterized in that: Two annular limit rings are arranged in parallel between the inner hub and the outer hub on both sides of the plane where the spokes are located. The two annular limit rings are fixedly connected by a plurality of second synchronization blocks inserted at the spoke intervals and leave gaps with the plane where the spokes are located. The annular limit ring close to the motor housing is fixedly connected to the second bracket through a third synchronization block.

8. The high-precision servo motor according to claim 1, characterized in that: The connecting component comprises a third bracket, on which two arms are arranged in parallel, the two arms are respectively located on two sides of the plane of the grating, and the light emitter and the receiver are respectively arranged at the ends of the two arms opposite to each other.

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