Steel ball assembling device and method for ball screw pair nut of electric power steering gear

Abstract

The invention relates to an assembling device and method, in particular to a steel ball assembling device and method for a ball screw pair nut of an electric power steering gear. The assembling device comprises a machine table, a steel ball feeding mechanism and a steel ball temporary storage sleeve are arranged on the machine table up and down, and a detection sensor is arranged on the steel ball temporary storage sleeve; a steel ball counter is arranged on a connecting pipeline between the steel ball temporary storage sleeve and the steel ball feeding mechanism; a mistake-proof insertion plate is inserted into the bottom of the steel ball temporary storage sleeve; a pressing rod is inserted into the top of the steel ball temporary storage sleeve. And a positioning seat is arranged below the steel ball temporary storage sleeve. The assembling device can count the steel balls, can detect the stacking height of the steel balls, further confirm and effectively prevent errors of the assembling number of the steel balls, and not only can guarantee normal assembling of nuts, but also can guarantee normal operation of the nuts. The problem that an existing ball feeding device cannot detect the number and specification of the steel balls, and consequently the steel balls are prone to being assembled mistakenly is solved.

Description

Technical Field

[0001] This invention relates to an assembly device and method, specifically to a steel ball assembly device and method for the ball screw pair nut of an electric power steering system. Background Technology

[0002] With the development of new energy passenger vehicle technology, R-EPS (Rack and Screw Electric Power Steering) has been widely used in new energy heavy-load passenger vehicles due to its ability to provide greater steering assistance, improve driving comfort and safety. The power steering mechanism of the R-EPS electric steering system is a ball nut / rack and screw pair. The ball nut / rack and screw pair includes a screw, a nut connected to the screw via balls (steel balls), and a rack on the nut. The nut is connected to the steering input shaft via the rack. Patent application CN113606304A discloses a ball screw pair end face circulation structure in an automotive steering system. The ball nut has an axially arranged return ball hole, and the two ends of the ball nut are respectively provided with mounting ring grooves. A retainer is installed in the mounting ring groove through a snap ring, and a return mechanism is installed on the retainer. The two ends of the helical trajectory are respectively connected to the return ball hole through the return mechanism.

[0003] When installing the aforementioned nut, steel balls need to be inserted into the helical raceway between the nut and the lead screw. Patent application CN216421563U discloses an automatic ball screw sorting and feeding device, which includes a support mounting frame. The support mounting frame is equipped with a steel ball storage mechanism, a servo ball receiving mechanism, a ball feeding rotation mechanism, and a lead screw clamping mechanism. The steel ball storage mechanism includes multiple ball compartments, each connected to a ball storage block. A ball pushing mechanism is located above the servo ball receiving mechanism. The servo ball receiving mechanism includes a ball receiving servo cylinder, a guide rail, and a moving ball receiving device. The ball receiving servo cylinder drives the moving ball receiving device to move along the guide rail. The moving ball receiving device moves to below one of the ball storage blocks. The bottom of the ball storage block has a gate. The moving ball receiving device opens the gate and receives a steel ball. Then, the moving ball receiving device moves above the ball feeding rotation mechanism. The ball pushing mechanism pushes the steel ball received by the moving ball receiving device into the helical raceway of the nut. After all the steel balls have entered the helical raceway, the ball feeding rotation mechanism rotates the nut onto the lead screw. This invention enables rapid and accurate sorting and feeding of balls.

[0004] The aforementioned ball feeding device can install steel balls (ball bearings) into the nut, but during the installation process, the steel balls are easily installed incorrectly (in terms of quantity or size). There are strict requirements for the number of steel balls in the nut; too many or too large balls will prevent the installation of the nut return mechanism and cage; too few or too small balls will affect the normal rotation of the nut. Therefore, it is necessary to develop a steel ball assembly device and method for the ball screw pair nut of an electric power steering system to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a steel ball assembly device and method for the ball screw nut of an electric power steering system that ensures accurate steel ball quantity, proper installation of all components of the nut after steel ball installation, and normal rotation of the nut.

[0006] The technical solution of this invention is: A ball assembly device for a ball screw pair nut in an electric power steering system includes a machine base, a ball feeding mechanism, a lifting cylinder, a support plate, a ball buffer sleeve, an anti-misalignment insert, a pressing cylinder, a pressure rod, and a positioning seat. The device is characterized by: a ball feeding mechanism on the machine base; a support plate mounted on the machine base below the ball feeding mechanism via the lifting cylinder; a ball buffer sleeve mounted on the support plate; detection sensors mounted above and below the ball buffer sleeve; the bottom end of the ball buffer sleeve extending below the support plate; and branch joints arranged side-by-side on the top end of the ball buffer sleeve, connected to both sides of the ball feeding mechanism via connecting pipes; a ball counter mounted on the connecting pipes; an anti-misalignment insert mounted on the support plate via the anti-misalignment cylinder, which is inserted into the ball buffer sleeve; a pressing cylinder mounted above the support plate via a bracket; a pressure rod mounted on the piston rod of the pressing cylinder, which is inserted into the top end of the ball buffer sleeve; and a positioning seat mounted on the machine base below the support plate.

[0007] The steel ball feeding mechanism consists of a base, ball boxes, guide plates, and funnels. Ball boxes are evenly distributed on both sides of the base. A guide plate is installed on the base outside the ball boxes. A ball receiving funnel is installed on the base at the end of the guide plate. The ball receiving funnel is connected to the connecting pipeline.

[0008] The ball box consists of a box body, a lifting support block A, and a lifting support block B. The lifting support block A is movably inserted into one side of the box body on one side of the guide plate, and the lifting support block B is movably inserted into the other side of the box body on the other side of the guide plate.

[0009] The bases below the lifting blocks A and B are respectively equipped with lifting cylinders, and the piston rod end of the lifting cylinder is fixedly connected to the lifting block A or the lifting block B.

[0010] The top end faces of the guide plate, lifting block A and lifting block B are respectively provided with guide grooves, and the top end faces of the guide plate and lifting block A and lifting block B are respectively inclined.

[0011] The top end of the box above the guide plate is provided with a discharge hole.

[0012] A ball-stopping rod is provided at the bottom of the support plate.

[0013] The positioning seat consists of a positioning frame, a support bearing, and a guide shaft. The support bearing is mounted on the positioning frame, and the guide shaft is mounted on the positioning frame below the support bearing. The top end of the guide shaft extends above the support bearing. The positioning frame is movably connected to the machine tool via a slide rail.

[0014] A method for assembling steel balls in the ball screw pair nut of an electric power steering system, characterized by the following steps: 1) Move the positioning seat of the ball assembly device of the ball screw pair nut of the electric power steering system from the bottom of the ball buffer sleeve to the end of the slide rail to facilitate the installation of the nut in the positioning seat; insert the nut with the return device and retainer at the bottom into the support bearing of the positioning seat, and place the bottom of the nut against the positioning bracket; after the nut is inserted into place, push the positioning seat to reset, rotate the nut to align the return ball hole of the nut with the ball buffer sleeve; 2) Start the lifting cylinder of the steel ball feeding mechanism. The lifting cylinder pushes the lifting block A and lifting block B upward. The upward lifting block A and block B respectively lift the steel balls in the steel ball storage box into the guide plate. The length of the guide plate controls the number of steel balls fed each time. The lifting block A feeds 25 steel balls at a time, feeding 100 balls in 4 times. The lifting block B feeds 17 balls at a time, feeding once. When the end of the lifting block B rises to the discharge hole of the box, the steel balls roll on the guide plate in sequence through the discharge hole under their own gravity, passing through the lifting block A and lifting block B, and then through the guide plate, funnel, connecting pipe and branch joint into the steel ball buffer sleeve. 3) During the process of injecting steel balls into the steel ball buffer sleeve, a steel ball counter (CONTRIEX, DW-AV-623-M4-276 type) on the connecting pipeline counts the steel balls, and a detection sensor (brand: CONTRIEX, model DW-AV-623-M4-276) (two sensors, the height of the two sensors corresponds to 25 steel balls and 17 steel balls respectively, the contact signal of the sensor is controlled by the PLC of the equipment to prevent the number of steel balls from being missed / overfilled / double-proofed) detects the stacking height of the steel balls in the steel ball buffer sleeve. The number of steel balls is further determined by the stacking height. By detecting the number of steel balls, the assembly quantity of steel balls is controlled. If the number of steel balls is incorrect, the light and sound alarm are activated. After replenishing or removing the excess steel balls, the process proceeds to the next step. 4) After the detection sensor detects that the stacking height of the steel balls is qualified, the lifting cylinder is started. The lifting cylinder drives the steel ball buffer sleeve to move downward through the support plate, so that the bottom end of the steel ball buffer sleeve is connected with the return ball hole of the nut, and the ball blocking rod is blocked at the spiral ball trajectory exit of the nut. 5) Activate the error-proof cylinder, which pulls the error-proof insert plate, thus removing the error-proof insert plate from the steel ball buffer sleeve; 6) Start the press cylinder. The press cylinder presses down the steel ball in the steel ball buffer sleeve through the pressure rod, and presses the steel ball into the spiral trajectory of the nut in sequence through the return ball hole of the nut and the return device. 7) After the pressing cylinder descends to the lower position, that is, after the steel ball pressing is completed, the pressing cylinder and the lifting cylinder are reset respectively, so that the steel ball buffer sleeve is disengaged from the nut; after the pressing cylinder is reset, the error prevention cylinder is reset, and the error prevention plate is inserted into the steel ball buffer sleeve. 8) Push the positioning seat to remove the nut after pressing the steel ball from the bottom of the steel ball buffer sleeve, and install the return device and cage on the top of the nut; after the cage is installed, align the lead screw with the top end of the guide shaft, lift the nut, and transfer the nut onto the lead screw; after the nut is transferred, repeat the above process to enter the next assembly cycle.

[0015] The beneficial effects of this invention are as follows: This ball assembly device for the ball screw nut in an electric power steering system counts the balls using a ball counter on the connecting pipeline and detects the stacking height of the balls using a sensor on the ball buffer, further confirming the number of balls. This effectively prevents errors in ball assembly, ensuring the correct number of balls enters the nut, guaranteeing both proper assembly and operation. It solves the problem of existing ball feeding devices failing to detect the number and specifications of balls, leading to assembly errors. It is particularly suitable for ball assembly in ball screw nuts. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is an assembly diagram of the steel ball buffer sleeve of the present invention; Figure 3 This is an assembly diagram of the error-proof insert plate of the present invention; Figure 4 This is a schematic diagram of the steel ball feeding mechanism of the present invention; Figure 5 This is a schematic diagram of the structure of the ball box of the present invention; Figure 6 This is a schematic diagram of the positioning seat of the present invention.

[0017] In the diagram: 1. Machine base, 2. Lifting cylinder, 3. Support plate, 4. Steel ball buffer sleeve, 5. Anti-error insert plate, 6. Pressing cylinder, 7. Pressure rod, 8. Detection sensor, 9. Branch joint, 10. Connecting pipeline, 11. Steel ball counter, 12. Anti-error cylinder, 13. Base, 14. Guide plate, 15. Funnel, 16. Box body, 17. Lifting block A, 18. Lifting block B, 19. Lifting cylinder, 20. Guide groove, 21. Discharge hole, 22. Ball stop rod, 23. Positioning frame, 24. Support bearing, 25. Guide shaft, 26. Ball screw pair nut, 27. Steel ball. Detailed Implementation

[0018] The ball assembly device for the ball screw nut of the electric power steering system includes a machine base 1, a ball feeding mechanism, a lifting cylinder 2, a support plate 3, a ball buffer sleeve 4, an anti-misalignment insert plate 5, a pressing cylinder 6, a pressure rod 7, and a positioning seat. The machine base 1 is equipped with a ball feeding mechanism to feed the ball from its stored reserves, conveying the ball to the nut and installing it into the nut. Below the ball feeding mechanism, the machine base 1 is equipped with a lifting cylinder 2. A support plate 3 is mounted on the piston rod end of the lifting cylinder 2, and a ball buffer sleeve 4 is mounted on the support plate 3 to buffer the ball before installation. The function of the lifting cylinder 2 is to drive the support plate 3 to rise and fall, which in turn drives the steel ball buffer sleeve 4 to rise and fall during the lifting and falling process of the support plate 3. This allows the steel ball buffer sleeve 4 to descend and insert into the return ball hole of the nut, thereby pressing the steel ball into the return ball hole and allowing the steel ball to be pressed into the spiral trajectory of the nut through the return ball hole. The steel ball buffer sleeve 4 is equipped with detection sensors 8 at the top and bottom to detect the height of the steel balls in the steel ball buffer sleeve 4 and determine the number of steel balls based on the height, thus ensuring the correct number of steel balls assembled. The bottom end of the steel ball buffer sleeve 4 extends below the support plate 3, and the top end of the steel ball buffer sleeve 4 is provided with branch joints 9 side by side. The branch joints 9 are connected to both sides of the steel ball feeding mechanism through connecting pipes 10, and steel ball counters 11 are provided on the connecting pipes 10. The function of the steel ball counter 11 is to measure the number of steel balls being transported from the steel ball feeding mechanism to the steel ball buffer sleeve 4 through the connecting pipe 10, thereby controlling the amount of steel balls being transported based on the count and ensuring that the number of steel balls assembled is not prone to errors. An anti-error cylinder 12 is installed on the support plate 3, and an anti-error insert 5 is installed at the end of the piston rod of the anti-error cylinder 12. The anti-error insert 5 is inserted into the steel ball buffer sleeve 4. The function of the anti-error insert 5 is to block the bottom end of the steel ball buffer sleeve 4, thereby buffering the steel balls entering the steel ball buffer sleeve 4, facilitating the detection sensor 8 to detect the stacking height of the steel balls, and thus accurately determining the number of steel balls based on the stacking height. A pressing cylinder 6 is installed above the support plate 3 via a bracket. A pressure rod 7 is installed on the piston rod of the pressing cylinder 6, and the pressure rod 7 is inserted into the top port of the steel ball buffer sleeve 4. The function of the pressing cylinder 6 is to drive the pressing rod 7 downward, which in turn presses down the steel ball in the steel ball buffer sleeve 4, squeezing the steel ball into the nut, thereby assembling the steel ball into the nut. A positioning seat is provided on the machine base 1 below the support plate 3 to position the nut below the steel ball buffer sleeve 4, so that the bottom end of the steel ball buffer sleeve 4 can be inserted into the ball return hole of the nut, thereby assembling the steel ball into the nut.

[0019] The steel ball feeding mechanism consists of a base 13, ball boxes, a guide plate 14, and a funnel 15. Ball boxes are evenly distributed on both sides of the base 13 to feed steel balls stored in them. The diameter of the steel balls stored in each ball box is different, ensuring that the diameter of the steel balls matches the diameter of the nut's spiral trajectory. This guarantees that the nut's retainer and return mechanism can be properly assembled after the steel balls are assembled, and that the nut's normal rotation is not affected by the steel balls being too small. A guide plate 14 is installed on the base 13 outside the ball boxes, and a ball-receiving funnel 15 is installed at the end of the base 13 of the guide plate 14. The ball-receiving funnel 15 is connected to the connecting pipe 10. The function of the guide plate 14 is to guide the steel balls, allowing them to move towards the ball-receiving funnel 15, thereby ensuring that the steel balls enter the connecting pipe. The ball box consists of a box body 16, a lifting block A17, and a lifting block B18. A lifting block A17 is movably inserted into one side of the box body 16 on one side of the guide plate 14, and a lifting block B18 is movably inserted into the other side of the box body 16 on the other side of the guide plate 14. The function of the lifting blocks A17 and B18 is to lift the steel balls, specifically the steel balls on the top surface of the lifting blocks A17 or B18, thus raising the steel balls to the outside of the ball box 16 so that they can fall onto the guide plate 14. Because the lengths of the lifting blocks A17 and B18 are designed to lift a fixed number of steel balls, the assembly quantity of steel balls can be further controlled, ensuring the correct assembly quantity. The length of lifting block A17 is greater than that of lifting block B18. Lifting block A17 can lift 8 steel balls, and lifting block B18 can lift 7 steel balls. Lifting cylinders 19 are respectively installed on the base 13 below lifting blocks A17 and B18, with the piston rod end of the lifting cylinder 19 fixedly connected to either lifting block A17 or lifting block B18. The function of the lifting cylinder 19 is to drive the lifting blocks A17 or B18 to rise and fall, thereby lifting the steel balls in the box 16. Guide grooves 20 are respectively provided on the top end faces of the guide plate 14, lifting blocks A17, and lifting blocks B18 to guide the steel balls to roll on the guide plate 14, lifting blocks A17, or lifting blocks B18. The top surfaces of the guide plate 14, lifting blocks A17, and lifting blocks B18 are respectively inclined to guide the steel balls in the direction of rolling on the top surfaces of the guide plate 14, lifting blocks A17, or lifting blocks B18. This allows the steel balls to roll from lifting blocks A17 or B18 onto the guide plate 14, or from the end of the guide plate 14 towards the funnel 15. A discharge hole 21 is provided at the top end of the box 16 above the guide plate 14 to restrict the rolling of the steel balls, allowing each steel ball to roll one by one from lifting blocks A17 or B18 onto the guide plate 14.

[0020] The bottom of the support plate 3 is provided with a ball-stopping rod 22, which blocks the exit of the spiral trajectory of the nut and keeps the steel ball in the spiral trajectory, ensuring that the steel ball is assembled in the spiral trajectory.

[0021] The positioning seat consists of a positioning frame 23, a support bearing 24, and a guide shaft 25. The support bearing 24 is mounted on the positioning frame 23, and the guide shaft 25 is mounted on the positioning frame 23 below the support bearing 24. The top end of the guide shaft 25 extends above the support bearing 24. The positioning frame 23 is movably connected to the machine base 1 via a slide rail. The support bearing 24 serves two purposes: firstly, it positions the nut; secondly, it allows the nut mounted on the support bearing 24 to rotate easily, facilitating nut adjustment and ensuring that the position of the nut's ball return hole is accurately aligned with the steel ball buffer sleeve 4. The guide shaft 25 limits and guides the steel balls, allowing them to roll sequentially within the helical trajectory of the nut, thus filling the helical trajectory one by one for steel ball assembly.

[0022] The method for assembling the steel balls in the ball screw pair nut of the electric power steering system includes the following steps: The positioning seat of the ball assembly device for the ball screw pair nut of the electric power steering system is pushed from the bottom of the ball buffer sleeve 4 to the end of the slide rail, so that the nut can be installed in the positioning seat; the nut with the return device and retainer at the bottom is inserted into the support bearing 24 of the positioning seat, and the bottom of the nut is pressed against the positioning frame 23; after the nut is inserted into place, the positioning seat is pushed to reset, and the nut is rotated so that the return ball hole of the nut is aligned with the ball buffer sleeve 4; The lifting cylinder 19 of the steel ball feeding mechanism is activated. The lifting cylinder 19 pushes the lifting blocks A17 and B18 upward. The upward lifting blocks A17 and B18 lift the steel balls in the box 16. When the ends of the lifting blocks A17 and B18 reach the discharge hole 21 of the box 16, the steel balls, under their own gravity, pass through the discharge hole 21 from the lifting blocks A17 and B18 and roll onto the guide plate 14 in sequence. Then, they pass through the guide plate 14, the funnel 15, the connecting pipe 10, and the branch joint 9 in sequence and are injected into the steel ball buffer sleeve 4. During the process of injecting steel balls into the steel ball buffer sleeve 4, the steel balls are counted by the steel ball counter 11 on the connecting pipe 10, and the stacking height of the steel balls in the steel ball buffer sleeve 4 is detected by the detection sensor 8. The number of steel balls is further determined by the stacking height. The assembly quantity of steel balls is controlled by detecting the number of steel balls. If the number of steel balls is incorrect, the light and sound alarms are activated. After replenishing or removing the excess steel balls, the process proceeds to the next step. After the detection sensor detects that the stacking height of the steel balls is qualified, the lifting cylinder 2 is activated. The lifting cylinder 2 drives the steel ball buffer sleeve 4 to move downward through the support plate 3, so that the bottom end of the steel ball buffer sleeve 4 connects with the return ball hole of the nut, and blocks the ball stop rod 22 at the spiral ball trajectory exit of the nut. Activate the error prevention cylinder 12, which pulls the error prevention insert 5 and removes it from the steel ball buffer sleeve 4; Start the pressing cylinder 6. The pressing cylinder 6 presses down the steel ball in the steel ball buffer sleeve 4 through the pressing rod 7, and presses the steel ball into the spiral trajectory of the nut in sequence through the return ball hole of the nut and the return device. After the pressing cylinder 6 descends to its position, that is, after the steel ball pressing is completed, the pressing cylinder 6 and the lifting cylinder 2 are reset respectively, so that the steel ball buffer sleeve 4 is disengaged from the nut; after the pressing cylinder 6 is reset, the anti-error cylinder 12 is reset, and the anti-error insert 5 is inserted into the steel ball buffer sleeve 4. Push the positioning seat to remove the nut after pressing the steel ball from the bottom of the steel ball buffer sleeve 4, and install the return device and retainer on the top of the nut; after the retainer is installed, align the lead screw with the top end of the guide shaft 25, lift the nut, and transfer the nut onto the lead screw; after the nut is transferred, repeat the above process to enter the next assembly cycle.

[0023] This ball assembly device for the ball screw nut in an electric power steering system counts the balls using a ball counter on the connecting pipeline and detects the stacking height of the balls using a sensor on the ball buffer, further confirming the number of balls. This effectively prevents errors in ball assembly, ensuring the correct number of balls enters the nut, guaranteeing both proper assembly and operation. It solves the problem of existing ball feeding devices failing to detect the number and specifications of balls, leading to assembly errors. It is particularly suitable for ball assembly in ball screw nuts.

Claims

1. A ball assembly device for a ball screw pair nut in an electric power steering system, comprising a machine base (1), a ball feeding mechanism, a lifting cylinder (2), a support plate (3), a ball buffer sleeve (4), an anti-misalignment insert plate (5), a pressing cylinder (6), a pressure rod (7), and a positioning seat, characterized in that: A steel ball feeding mechanism is provided on the machine base (1). A support plate (3) is installed on the machine base (1) below the steel ball feeding mechanism via a lifting cylinder (2). A steel ball buffer sleeve (4) is provided on the support plate (3). Detection sensors (8) are installed on the upper and lower parts of the steel ball buffer sleeve (4). The bottom end of the steel ball buffer sleeve (4) extends to the bottom of the support plate (3). A branch connector (9) is provided side by side on the top end of the steel ball buffer sleeve (4). The branch connector (9) is connected to the steel ball via a connecting pipe (10). The material handling mechanism is connected on both sides; a steel ball counter (11) is installed on the connecting pipe (10); an anti-error insert (5) is installed on the support plate (3) through the anti-error cylinder (12), and the anti-error insert (5) is inserted into the steel ball buffer sleeve (4); a pressing cylinder (6) is installed above the support plate (3) through the bracket, and a pressure rod (7) is installed on the piston rod of the pressing cylinder (6), and the pressure rod (7) is inserted into the top port of the steel ball buffer sleeve (4); a positioning seat is installed on the machine base (1) below the support plate (3).

2. The ball assembly device for the ball screw pair nut of an electric power steering system according to claim 1, characterized in that: The steel ball feeding mechanism consists of a base (13), a ball box, a guide plate (14), and a funnel (15). Ball boxes are evenly distributed on both sides of the base (13). A guide plate (14) is provided on the base (13) outside the ball box. A ball receiving funnel (15) is provided on the base (13) at the end of the guide plate (14). The ball receiving funnel (15) is connected to the connecting pipe (10).

3. The ball assembly device for the ball screw pair nut of an electric power steering system according to claim 2, characterized in that: The ball box is composed of a box body (16), a lifting block A (17) and a lifting block B (18). The lifting block A (17) is movably inserted into one side of the box body (16) on one side of the guide plate (14), and the lifting block B (18) is movably inserted into the other side of the box body (16) on the other side of the guide plate (14).

4. The ball assembly device for the ball screw pair nut of an electric power steering system according to claim 3, characterized in that: The base (13) below the lifting block A (17) and the lifting block B (18) is provided with a lifting cylinder (19), and the piston rod end of the lifting cylinder (19) is fixedly connected to the lifting block A (17) or the lifting block B (18).

5. The ball assembly device for the ball screw pair nut of an electric power steering system according to claim 3, characterized in that: The top end faces of the guide plate (14), lifting block A (17) and lifting block B (18) are respectively provided with guide grooves (20), and the top end faces of the guide plate (14) and lifting block A (17) and lifting block B (18) are respectively inclined.

6. A ball assembly device for the ball screw pair nut of an electric power steering system according to any one of claims 3-5, characterized in that: The top end of the box (16) above the guide plate (14) is provided with a discharge hole (21).

7. The ball assembly device for the ball screw pair nut of an electric power steering system according to any one of claims 1, characterized in that: The bottom of the support plate (3) is provided with a ball-stopping rod (22).

8. The ball assembly device for the ball screw pair nut of an electric power steering system according to any one of claims 1, characterized in that: The positioning seat is composed of a positioning frame (23), a support bearing (24) and a guide shaft (25). The support bearing (24) is provided on the positioning frame (23), and the guide shaft (25) is provided on the positioning frame (23) below the support bearing (24). The top end of the guide shaft (25) extends above the support bearing (24). The positioning frame (23) is movably connected to the machine base (1) through a slide rail.

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