Maintenance-free hub bearing grease injection tool

Abstract

The maintenance-free hub bearing grease injection tool comprises a frame body and a lower seat, the lower seat is connected with the frame body, a grease injection cavity is formed in the lower seat in a hollow mode and communicated with a piston groove, the grease injection cavity is filled with lubricating grease, a plurality of insertion nozzles are arranged on the bottom wall of the lower seat, and large grease outlet holes are formed in the insertion nozzles. An upper cover which is used for being inserted into the piston groove and extruding the lubricating grease in the grease injection cavity to enable the lubricating grease to be discharged to the small end of a roller of an external hub bearing to be subjected to grease injection through the multiple insertion nozzles is movably arranged on the frame body, and a driving structure is arranged on the frame body; the top wall of the frame body is provided with a connecting structure which is used for being detachably connected with the output end of external hydraulic equipment so as to drive the frame body to move to enable the lower base to be inserted into an external hub bearing to be greased when the external hydraulic equipment is started. The maintenance-free hub bearing grease injection tool solves the problems that lubricating grease is difficult to accurately feed to the small end of a roller in the grease injection process, so that lubrication is insufficient, grease distribution is uneven in the grease injection process, and grease is prone to leakage in the grease injection process in a traditional maintenance-free hub bearing grease injection tool.

Description

Technical Field

[0001] This invention relates to the field of bearing tooling technology, specifically to a maintenance-free wheel hub bearing grease injection tooling. Background Technology

[0002] Maintenance-free wheel hub bearings are core load-bearing components of vehicle transmission systems. Their lubrication directly determines the bearing's service life and operational reliability. Grease injection fixtures, as key equipment in the assembly of these bearings, directly impact lubrication quality. Existing maintenance-free wheel hub bearing grease injection fixtures suffer from three major technical defects in practical applications: First, traditional grease injection paths typically involve injecting grease from the large end of the roller to the small end. Due to the tapered roller's cone angle structure and the centrifugal force during bearing rotation, grease tends to accumulate at the large end, while the small end, a critical lubrication area, often suffers from insufficient lubrication due to the difficulty in accurately delivering grease, leading to premature bearing wear and failure. Second, the pressure transmission in the grease injection chamber lacks stability, and the grease injection path design is unreasonable, resulting in uneven grease distribution within the bearing and failing to achieve full coverage of the roller contact surfaces, affecting the overall lubrication reliability of the bearing. Third, the sealing structure design of the fixture has shortcomings, making it prone to reverse leakage of grease during injection. This not only wastes lubricating materials but also contaminates the operating environment and reduces the stability of the injection pressure. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a maintenance-free wheel hub bearing grease injection fixture. This fixture solves the problems of insufficient lubrication caused by the difficulty in accurately delivering lubricating grease to the small end of the roller during grease injection, uneven grease distribution during the grease injection process, and easy grease leakage during grease injection in traditional maintenance-free wheel hub bearing grease injection fixtures.

[0004] To achieve the above objectives, the present invention provides a maintenance-free wheel hub bearing grease injection fixture, comprising a frame and a lower seat for inserting into the gap between the outer and inner rings of an external wheel hub bearing to be greased. The lower seat is connected to the frame, and the lower seat has a hollow grease injection cavity that is connected to a piston groove formed on the top wall of the lower seat. The grease injection cavity is filled with lubricating grease. The bottom wall of the lower seat is provided with several inserts for inserting into the small ends of the rollers of the external wheel hub bearing to be greased. Each insert has a grease outlet hole that is connected to the grease injection cavity. The frame is movably provided with a top cover for inserting into the piston groove and squeezing the lubricating grease in the grease injection cavity to discharge it through the several inserts to the small ends of the rollers of the external wheel hub bearing to be greased. The frame is provided with a drive structure for driving the top cover to move along the height direction of the frame. The top wall of the frame is provided with a connection structure for detachably connecting to the output end of an external hydraulic device so that when the external hydraulic device is started, it drives the frame to move and insert the lower seat into the external wheel hub bearing to be greased.

[0005] The advantages of adopting the above technical solution are as follows: The frame provides stable support for the overall tooling; the lower seat can be precisely inserted into the gap between the outer and inner rings of the bearing to be greased; the nozzle on its bottom wall can be directly inserted into the small end of the roller, achieving targeted grease injection from the small end to the large end, effectively solving the problem of insufficient lubrication at the small end caused by traditional grease injection paths; the grease injection chamber is connected to the grease outlet on the nozzle, providing a smooth delivery channel for lubricating grease, ensuring that the grease reaches the lubrication area efficiently; the upper cover can be inserted into the piston groove and, in conjunction with the drive structure, squeezes the grease, achieving controllable adjustment of the grease injection process and ensuring accurate and stable grease injection volume; the connecting structure on the top wall of the frame can be detachably connected to external hydraulic equipment, improving the compatibility of the tooling with different hydraulic equipment and reducing debugging time during equipment replacement; through the above overall structural design, the accuracy, uniformity, and sealing of grease injection are synergistically improved, avoiding grease waste and environmental pollution, significantly extending the service life of maintenance-free wheel bearings, and meeting the process requirements of large-scale production.

[0006] The present invention further provides that the insertion nozzle is arranged perpendicularly to or inclined relative to the bottom wall of the lower seat.

[0007] The advantages of adopting the above technical solution are as follows: When the nozzle is set perpendicularly to the bottom wall of the lower seat, it facilitates manufacturing and allows for precise alignment of the small end gap of the rollers, ensuring that the lubricating grease is directly injected into the core lubrication area and avoiding grease displacement. When a relatively inclined setting is adopted, it can adapt to the roller layout of bearings with different structural specifications, optimize the flow path of grease between the rollers and raceways, reduce grease retention, and improve the uniformity of lubrication coverage. At the same time, the inclined setting can also reduce the grease flow resistance, and together with the extrusion pressure of the grease injection chamber, further improve the grease injection efficiency, ensuring that the small end of the rollers and the contact surface are fully covered with grease, thus ensuring the reliability of bearing lubrication. The above two setting methods can be flexibly selected according to the actual bearing type and grease injection conditions, and diverse grease injection needs can be met without changing the entire set of tooling, enhancing the versatility and applicability of the tooling.

[0008] The present invention further comprises: the driving structure including a cylinder mounted on the frame, a first flange mounted on the output end of the cylinder, a plurality of first connecting bolts detachably connecting the first flange to the top wall of the upper cover, and a second flange mounted on the outer shell of the cylinder, a plurality of second connecting bolts detachably connecting the second flange to the bottom wall of the frame.

[0009] The advantages of adopting the above technical solution are: the cylinder can provide a stable and continuous driving force for the upper cover, ensuring that the pressure is evenly transmitted when the upper cover squeezes the grease in the grease injection chamber, avoiding fluctuations in the grease injection volume, and ensuring the stability of the grease injection process; the first flange is detachably connected to the upper cover through the first connecting bolt, which facilitates the disassembly, maintenance, and replacement of the upper cover, reducing maintenance costs; the second flange is detachably connected to the frame through the second connecting bolt, realizing the firm fixation of the cylinder and the frame, while facilitating the maintenance and specification change of the cylinder to adapt to different grease injection pressure requirements; the overall drive structure design is simple and efficient, effectively improving the automation level and production efficiency of the grease injection operation.

[0010] The present invention further comprises: an outer sealing ring provided on the outer peripheral wall of the lower seat for abutting against the inner peripheral wall of the outer ring of the external wheel hub bearing to be greased; and an inner sealing ring provided on the inner peripheral wall of the lower seat for abutting against the outer peripheral wall of the inner ring of the external wheel hub bearing to be greased. Both the outer sealing ring and the inner sealing ring are annular and both are made of rubber.

[0011] The advantages of adopting the above technical solution are as follows: In the above technology, the outer sealing ring of the lower bearing outer peripheral wall abuts against the inner peripheral wall of the bearing outer ring, and the inner sealing ring of the inner peripheral wall abuts against the outer peripheral wall of the bearing inner ring, forming a double-ring sealing structure that completely blocks the reverse leakage of grease during the grease injection process; wherein, the outer sealing ring and the inner sealing ring are made of rubber material, which has good elasticity and fit, and can closely fit the contours of the bearing inner and outer rings, eliminating sealing gaps and avoiding sealing blind spots; the above-mentioned double sealing structure greatly improves the sealing performance of the grease injection cavity, ensures stable pressure during the grease injection process, and provides support for the uniform distribution of grease; the oil resistance and wear resistance of the rubber material can extend the service life of the sealing ring, reduce grease waste and environmental pollution, reduce the use and maintenance costs of tooling, and improve the economy and environmental protection of the grease injection process. The present invention further comprises: a convex ring provided on the inner peripheral wall of the outer sealing ring; a slot provided on the outer peripheral wall of the lower seat; the slot engaging with the convex ring; and a plurality of third connecting bolts evenly distributed and threadedly connected circumferentially on the lower seat, each of the third connecting bolts passing through the slot and the convex ring.

[0012] The advantages of adopting the above technical solution are as follows: In the above technology, the convex ring on the inner circumferential wall of the outer sealing ring engages with the groove on the outer circumferential wall of the lower seat, achieving precise positioning of the outer sealing ring, avoiding displacement under the action of grease injection pressure, and ensuring stable sealing effect; while the circumferentially distributed third connecting bolts pass through the groove and the convex ring, firmly fixing the outer sealing ring to the lower seat, further enhancing the connection reliability and preventing the sealing ring from falling off; the above-mentioned double limiting structure of engagement and bolt fixing ensures the tight fit between the outer sealing ring and the lower seat and the outer ring of the bearing, improving the sealing redundancy, while the detachable design of the bolt connection facilitates the disassembly and replacement of the outer sealing ring, reducing maintenance difficulty and time consumption.

[0013] The present invention further includes: the connection structure including a connection seat disposed on the top wall of the frame, the connection seat being cylindrical, the top wall of the connection seat having a connection groove for the output end of an external hydraulic device to be inserted, and a fourth connection bolt being evenly distributed and bolted on the outer peripheral wall of the connection seat, the screw end of the fourth connection bolt being a connection end for inserting into the connection groove and being detachably connected to the output end of the external hydraulic device.

[0014] The advantages of adopting the above technical solution are as follows: the cylindrical connecting seat provides an installation reference for the output end of the external hydraulic equipment. The connecting groove can position and guide the output end of the hydraulic equipment, ensuring accurate alignment. The circumferentially distributed fourth connecting bolts can firmly fix the output end of the hydraulic equipment to the connecting seat, realizing a detachable connection. This improves the compatibility of tooling with hydraulic equipment of different specifications. The detachable structure facilitates quick replacement of hydraulic equipment, reduces equipment adaptation and debugging time, and shortens the production cycle. Furthermore, the circumferentially distributed design of the fourth connecting bolts ensures uniform force distribution, avoids local stress concentration, and ensures stable transmission of hydraulic driving force to the frame, allowing the lower seat to smoothly insert into the gap between the inner and outer rings of the bearing, thus improving the stability and safety of the grease injection operation.

[0015] The present invention further comprises: one end of the upper cover used for inserting into the piston groove is the insertion end; a first sealing groove is circumferentially formed on the outer peripheral wall of the insertion end; a first sealing O-ring is provided in the first sealing groove; the first sealing O-ring is made of sealing rubber material and its outer peripheral wall abuts against the inner wall of the grease injection cavity; a second sealing groove is circumferentially formed on the inner wall of the grease injection cavity; a second sealing O-ring is provided in the second sealing groove; the second sealing O-ring is made of sealing rubber material and its outer peripheral wall abuts against the inner peripheral wall of the insertion end.

[0016] The advantages of adopting the above technical solution are as follows: In the above technology, the first sealing O-ring at the insertion end of the upper cover abuts against the inner wall of the grease injection cavity, and the second sealing O-ring on the inner wall of the grease injection cavity abuts against the inner peripheral wall of the insertion end, forming a double O-ring sealing structure, which greatly improves the sealing protection level of the grease injection cavity and effectively prevents grease leakage; Among them, the first sealing groove and the second sealing groove provide precise installation positioning for the O-ring, avoiding displacement or deformation of the O-ring during the sealing process, and ensuring a continuous and stable sealing effect; The sealing O-ring is made of sealing rubber material, which has good elasticity, oil resistance and wear resistance, and is suitable for the sealing requirements under grease injection conditions, reducing wear of the sealing components; The above double sealing structure ensures stable pressure during the grease injection process, avoids insufficient grease injection due to pressure loss, ensures that the lubricating grease is evenly distributed on the roller contact surface, improves the reliability of bearing lubrication, and reduces grease waste.

[0017] The present invention further comprises: a plurality of guide groups evenly distributed around the outer peripheral wall of the upper cover, each guide group being composed of guide balls; a guide hole being provided on the outer peripheral wall of the upper cover corresponding to the position of each guide ball; each guide ball being movably disposed in the guide hole, and the diameter of the guide hole opening being smaller than the diameter of the guide ball; a plurality of guide grooves being provided on the inner peripheral wall of the frame along the moving direction of the upper cover; the plurality of guide grooves corresponding one-to-one with the plurality of guide groups, and the plurality of guide balls in each guide group being movably disposed in the corresponding guide groove; the radial cross-section of the guide groove being arc-shaped.

[0018] The advantages of adopting the above technical solution are as follows: In the above technology, the guide balls on the outer peripheral wall of the upper cover are movably set in the guide hole and cooperate with the guide groove on the inner peripheral wall of the frame, which greatly reduces the frictional resistance when the upper cover moves along the height direction of the frame, making the upper cover rise and fall more smoothly and improving the smoothness of the grease injection operation; and the guide group and the guide groove correspond one-to-one, providing precise guidance and limiting for the upper cover, avoiding deviation and tilting when the upper cover squeezes grease, ensuring that the grease injection pressure is evenly transmitted to all parts of the grease injection cavity, and the radial cross section of the guide groove is set in an arc shape to match the rolling trajectory of the guide balls, improve guiding stability, and prevent jamming. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of the present invention, showing the insertion nozzle and the lower seat in a relatively perpendicular state and in contact with the external wheel hub bearing to be greased. Figure 2 for Figure 1 A magnified view of part A in the middle; Figure 3 for Figure 2 A simplified view showing the middle insert and the lower seat at a relative angle; Figure 4 This is a simplified view of the engagement state between the guide ball and the guide groove in this invention. Detailed Implementation

[0020] This invention provides a maintenance-free wheel hub bearing grease injection fixture, comprising a frame 1 and a lower seat 2 for inserting into the gap between the outer and inner rings of an external wheel hub bearing to be greased. The lower seat 2 is connected to the frame 1. A grease injection cavity 21 is hollowed out in the lower seat 2, and the grease injection cavity 21 is connected to a piston groove 211 formed on the top wall of the lower seat 2. The grease injection cavity 21 is filled with lubricating grease 212. A plurality of inserts 22 are provided on the bottom wall of the lower seat 2 for inserting into the small ends of the rollers of the external wheel hub bearing to be greased. Each insert 22 has a grease outlet hole 221, which is connected to the grease injection cavity 21. A movable part is provided on the frame 1 for inserting into the piston groove 211 and squeezing the lubricating grease 212 in the grease injection cavity 21 so that it is discharged through the plurality of inserts 22. The upper cover 3 extends to the small end of the roller of the external wheel hub bearing to be greased. The frame 1 is equipped with a drive structure for moving the upper cover 3 along the height of the frame 1. The top wall of the frame 1 is equipped with a connection structure for detachably connecting to the output end of an external hydraulic device, so that when the external hydraulic device is started, it drives the frame 1 to move, causing the lower seat 2 to insert into the external wheel hub bearing to be greased. The insertion nozzle 22 is perpendicular or inclined to the bottom wall of the lower seat 2. The drive structure includes a cylinder 4 mounted on the frame 1. A first flange 41 is mounted on the output end of the cylinder 4. Several first connecting bolts 42 are detachably connected between the first flange 41 and the top wall of the upper cover 3. A second flange 43 is mounted on the outer shell of the cylinder 4. A plurality of second connecting bolts 44 are detachably connected between the lower seat 2 and the bottom wall of the frame 1. An outer sealing ring 23 is provided on the outer peripheral wall of the lower seat 2 for abutting against the inner peripheral wall of the outer ring of the external wheel hub bearing to be greased. An inner sealing ring 24 is provided on the inner peripheral wall of the lower seat 2 for abutting against the outer peripheral wall of the inner ring of the external wheel hub bearing to be greased. Both the outer sealing ring 23 and the inner sealing ring 24 are annular and made of rubber. A convex ring 231 is provided on the inner peripheral wall of the outer sealing ring 23. A slot 25 is provided on the outer peripheral wall of the lower seat 2, and the slot 25 engages with the convex ring 231. A plurality of third connecting bolts 251 are evenly distributed circumferentially and threadedly connected to the lower seat 2. Each of the third connecting bolts... All 251 are inserted into the slot 25 and provided with a protruding ring 231. The connection structure includes a connecting seat 11 disposed on the top wall of the frame 1. The connecting seat 11 is cylindrical. A connecting groove 111 for the output end of an external hydraulic device is opened on the top wall of the connecting seat 11. Fourth connecting bolts 112 are evenly distributed and bolted on the outer peripheral wall of the connecting seat 11. The screw end of the fourth connecting bolt 112 is a connecting end for inserting into the connecting groove 111 and detachably connecting to the output end of the external hydraulic device. The end of the upper cover 3 for inserting into the piston groove 211 is an insertion end 31. A first sealing groove 311 is circumferentially opened on the outer peripheral wall of the insertion end 31. A first sealing O-ring 312 is disposed in the first sealing groove 311.The first sealing O-ring 312 is made of sealing rubber material, and its outer peripheral wall abuts against the inner wall of the grease injection cavity 21. A second sealing groove 23 is circumferentially formed on the inner wall of the grease injection cavity 21, and a second sealing O-ring 231 is disposed in the second sealing groove 23. The second sealing O-ring 231 is made of sealing rubber material, and its outer peripheral wall abuts against the inner peripheral wall of the insertion end 31. Several guide groups are evenly distributed circumferentially on the outer peripheral wall of the upper cover 3, and each guide group consists of guide rollers. The upper cover 3 is composed of balls 32. A guide hole 33 is provided on the outer peripheral wall of the upper cover 3 corresponding to the position of each guide ball 32. Each guide ball 32 is movably disposed in the guide hole 33, and the diameter of the opening of the guide hole 33 is smaller than the diameter of the guide ball 32. A plurality of guide grooves 12 are provided on the inner peripheral wall of the frame 1 along the moving direction of the upper cover 3. Each guide groove 12 corresponds one-to-one with a plurality of guide groups, and a plurality of guide balls 32 in each guide group are movably disposed in the corresponding guide groove 12. The radial cross-section of the guide groove 12 is arc-shaped.

[0021] Overall operation process of maintenance-free wheel hub bearing grease injection fixture: 1. Equipment Adaptation and Connection: The tooling and the output end of the external hydraulic equipment are aligned and inserted through the connecting seat and connecting groove of the connecting structure on the top wall of the frame, and then fastened with the evenly distributed fourth connecting bolts in the ring to achieve detachable fixation; at the same time, the cylinder is fixed to the frame through the second flange and the second connecting bolt, and the cylinder output end is connected to the top cover through the first flange and the first connecting bolt to complete the assembly of the drive structure.

[0022] 2. Bearing positioning and tooling docking: Precisely position the wheel hub bearing to be greased and maintained, start the hydraulic equipment, drive the frame to move the lower seat towards the bearing, so that the lower seat is placed in the gap between the outer ring and the inner ring of the bearing. At this time, the outer sealing ring of the lower seat abuts against the inner circumferential wall of the outer ring of the bearing, and the inner sealing ring abuts against the outer circumferential wall of the inner ring of the bearing, forming an initial seal; several nozzles on the bottom wall of the lower seat are precisely inserted into the small end of the roller to complete the targeted positioning for grease injection.

[0023] 3. Grease preparation: Ensure that the grease injection chamber is filled with sufficient lubricating grease, align the insertion end of the upper cover with the piston groove on the top wall of the lower seat, and ensure that the first sealing O-ring on the outer periphery of the insertion end fits against the inner wall of the grease injection chamber, while the second sealing O-ring on the inner wall of the grease injection chamber fits against the inner peripheral wall of the insertion end, forming a double seal.

[0024] 4. Pressurized grease injection: The cylinder drive structure is activated, and the cylinder output end drives the upper cover to move smoothly down along the guide groove of the frame (the guide ball rolls along the guide groove to assist in guidance). After the upper cover is inserted into the piston groove, it applies uniform pressure to the lubricating grease in the grease injection chamber. Under pressure, the grease flows through the grease injection chamber into the grease outlet of each nozzle. Select the vertical or inclined nozzle as needed to accurately inject the grease into the small end of the roller and the gap between the roller and the raceway, so as to achieve uniform grease injection from the inside to the outside.

[0025] 5. Grease injection completion and reset: After the grease injection reaches the preset requirements, control the cylinder to drive the upper cover to reset in the reverse direction, shut down the hydraulic equipment, loosen the fourth connecting bolt to separate the tooling from the hydraulic equipment; remove the tooling, check the bearing grease injection effect, and complete a single grease injection operation; if maintenance is required, the components can be disassembled and replaced by removing each connecting bolt.

[0026] The external grease-injected wheel hub bearing described above is designated as 5 in the accompanying drawings, the outer ring of the external grease-injected wheel hub bearing is designated as 51 in the accompanying drawings, and the inner ring of the external grease-injected wheel hub bearing is designated as 52 in the accompanying drawings.

[0027] The external hydraulic drive equipment involved in the above technology is existing technology, such as conventional hydraulic drive components like hydraulic cylinders and hydraulic motors. These are mainly used to provide axial driving force to the frame to drive the lower seat into the gap between the inner and outer rings of the wheel hub bearing to be greased. Their specific structure and working principle are common knowledge in the field and will not be elaborated here. Meanwhile, the connection between the hydraulic cylinder and the tooling of this patent is achieved through the connection structure described in claim 6: the output end of the hydraulic cylinder is inserted into the connecting groove of the connecting seat on the top wall of the frame, and fourth connecting bolts evenly distributed around the circumference are inserted into the connecting groove and threadedly connected to or abutted against the output end of the hydraulic cylinder, achieving a detachable and fixed connection between the hydraulic cylinder and the frame. This connection method is firm, easy to assemble and disassemble, and ensures stable transmission of driving force.

[0028] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the present invention as claimed, which is defined by the appended claims and their equivalents.

Claims

1. A grease injection fixture for maintenance-free wheel hub bearings, characterized in that: The device includes a frame and a lower seat for inserting into the gap between the outer and inner rings of an external wheel hub bearing to be greased. The lower seat is connected to the frame and has a hollow grease injection chamber that connects to a piston groove formed on the top wall of the lower seat. The grease injection chamber is filled with lubricating grease. The bottom wall of the lower seat has several nozzles for inserting into the small ends of the rollers of the external wheel hub bearing to be greased. Each nozzle has a grease outlet hole that connects to the grease injection chamber. The frame has a movable upper cover for inserting into the piston groove and squeezing the lubricating grease in the grease injection chamber to discharge it through the nozzles to the small ends of the rollers of the external wheel hub bearing to be greased. The frame has a drive structure for driving the upper cover to move along the height of the frame. The top wall of the frame has a connection structure for detachably connecting to the output end of an external hydraulic device so that when the external hydraulic device is started, it drives the frame to move and insert the lower seat into the external wheel hub bearing to be greased.

2. The grease injection fixture for a maintenance-free wheel hub bearing according to claim 1, characterized in that: The plug is positioned perpendicularly to or inclined relative to the bottom wall of the lower seat.

3. The maintenance-free wheel hub bearing grease injection fixture according to claim 1, characterized in that: The drive structure includes a cylinder mounted on the frame, a first flange on the output end of the cylinder, a plurality of first connecting bolts detachably connecting the first flange to the top wall of the upper cover, and a second flange on the cylinder housing, a plurality of second connecting bolts detachably connecting the second flange to the bottom wall of the frame.

4. The grease injection fixture for a maintenance-free wheel hub bearing according to claim 1, characterized in that: The lower seat has an outer sealing ring on its outer peripheral wall for contacting the inner peripheral wall of the outer ring of the wheel hub bearing to be greased, and an inner sealing ring on its inner peripheral wall for contacting the outer peripheral wall of the inner ring of the wheel hub bearing to be greased. Both the outer and inner sealing rings are annular and are made of rubber.

5. The grease injection fixture for a maintenance-free wheel hub bearing according to claim 4, characterized in that: A convex ring is provided on the inner peripheral wall of the outer sealing ring, and a groove is provided on the outer peripheral wall of the lower seat. The groove is engaged with the convex ring. Several third connecting bolts are evenly distributed around the lower seat and threadedly connected. Each third connecting bolt passes through the groove and is provided with a convex ring.

6. The grease injection fixture for a maintenance-free wheel hub bearing according to claim 1, characterized in that: The connection structure includes a connecting seat disposed on the top wall of the frame. The connecting seat is cylindrical and has a connecting groove on its top wall for the output end of an external hydraulic device to be inserted. A fourth connecting bolt is evenly distributed and bolted on the outer peripheral wall of the connecting seat. The screw end of the fourth connecting bolt is a connecting end for inserting into the connecting groove and detachably connecting to the output end of the external hydraulic device.

7. The grease injection fixture for a maintenance-free wheel hub bearing according to claim 1, characterized in that: The end of the upper cover used for inserting into the piston groove is the insertion end. A first sealing groove is circumferentially formed on the outer peripheral wall of the insertion end. A first sealing O-ring is provided in the first sealing groove. The first sealing O-ring is made of sealing rubber material and its outer peripheral wall abuts against the inner wall of the grease injection cavity. A second sealing groove is circumferentially formed on the inner wall of the grease injection cavity. A second sealing O-ring is provided in the second sealing groove. The second sealing O-ring is made of sealing rubber material and its outer peripheral wall abuts against the inner peripheral wall of the insertion end.

8. The grease injection fixture for a maintenance-free wheel hub bearing according to claim 1, characterized in that: The outer peripheral wall of the upper cover is evenly distributed with several guide groups, each of which is composed of guide balls. The outer peripheral wall of the upper cover has a guide hole corresponding to the position of each guide ball. Each guide ball is movably disposed in the guide hole, and the diameter of the guide hole opening is smaller than the diameter of the guide ball. The inner peripheral wall of the frame is provided with several guide grooves along the movement direction of the upper cover. The several guide grooves correspond one-to-one with several guide groups, and the several guide balls in each guide group are movably disposed in the corresponding guide groove. The radial cross-section of the guide groove is arc-shaped.

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