Electric power circulating ball steering gear steering screw support structure

Abstract

The utility model discloses a kind of electric circulating ball steering gear steering screw support structure, including shell, steering screw, steering nut, screw steel ball and rocker shaft, the left side end of the shell is fixed with needle roller bearing, the right side end of the shell is installed with four-point contact ball bearing, the steering nut is rotatably connected in needle roller bearing and four-point contact ball bearing, the shell is in, and located four-point contact ball bearing right side end screw thread connection has adjusting screw plug, the rocker shaft is connected on shell, the steering nut is built in shell, and is engaged with rocker shaft connection, the screw steel ball is rotatably connected between steering nut and steering screw;The utility model has the advantages of simple structure, lower cost, small, little wear, higher supporting stiffness.

Description

Technical Field

[0001] This utility model relates to the field of electric steering technology, specifically to a steering screw support structure for an electric recirculating ball steering system. Background Technology

[0002] A typical electric recirculating ball steering system structure is as follows: Figure 1 As shown, within the cavity formed by the top cover 3, the housing 4, and the original shell 11, the original input shaft 1 is connected to the original steering screw 9 via the original torsion bar 2. The original steering nut 10 has a helical raceway that mates with the original steering screw 9, filled with steel balls to form a ball screw pair. Angular contact ball bearings 8 and 12 are installed at both ends of the original steering screw 9 to support it. The outer ring of the angular contact ball bearing 12 is positioned by a step on the original shell, and the outer ring of the angular contact ball bearing 8 is positioned by the original adjusting plug 7. The outer circle of the original adjusting plug 7 has an external thread, and the original shell 11 has a threaded hole that mates with it. By controlling the screwing length of the original adjusting plug 7, the clearance between the angular contact ball bearings 8 and 12 can be controlled. After adjustment, a locking nut 6 is installed on the external thread of the original adjusting plug 7 to fix it. An original worm gear 5, meshing with a worm 15, is installed on the original steering screw 9. One end of the original worm gear 15 is connected to the motor 14. The original steering nut 10 and the original rocker arm shaft 13 are respectively machined with meshing racks and gear sectors, forming a rack and gear sector pair. The working principle of the electric recirculating ball steering gear is as follows: when the driver turns the steering wheel, the steering torque acts on the input shaft 1, causing relative deformation at the upper and lower ends of the original torsion bar 2. The original sensor 16 determines the magnitude and direction of the input torque based on the magnitude of this deformation. The ECU then combines this with the vehicle speed signal to control the motor 14 to output the corresponding steering torque. This steering torque is amplified by the worm gear mechanism to drive the original steering screw 9. The original steering screw 9 converts the rotational motion into axial movement of the original steering nut 10 through a ball screw pair. In the rack and gear sector pair, the movement of the original steering nut 10 causes the original rocker arm shaft 13 to rotate, driving the steering drop arm to rotate, and then the wheels to rotate through the steering transmission mechanism.

[0003] The steering screw is one of the important transmission components in a recirculating ball steering system, and it is subjected to axial and radial forces. Unlike hydraulic recirculating ball steering systems, which use hydraulic pressure to push the steering nut to achieve power steering, electric recirculating ball steering systems use an electric motor to drive the steering screw through a worm gear mechanism to achieve power steering. The axial and radial forces acting on the steering screw are greater, thus requiring higher support stiffness and strength from the steering screw. Figure 1 This paper illustrates a commonly used steering screw support structure. The disadvantages of this design are as follows: (1) The original steering screw 9 is supported at both ends by an angular contact ball bearing or a tapered roller bearing. Angular contact ball bearings and tapered roller bearings can only withstand unidirectional axial forces. When steering, only one side of the bearing bears the axial force, while the other side does not bear the axial force. This requires a single bearing to be able to withstand all axial forces. In the electric steering system of medium and heavy-duty vehicles, the axial force on the steering screw is very large, which will result in a large bearing volume. Furthermore, the presence of two bearings leads to a large input axial dimension of the steering system, which is not conducive to the arrangement of the steering system on the vehicle. Moreover, the cost of using two angular contact ball bearings 2 or tapered roller bearings is relatively high.

[0004] (2) To adjust the axial clearance of the two angular contact ball bearings, the original adjusting plug 7 cannot be fully tightened. The original locking nut 6 is mainly used for axial fixation. Therefore, during assembly, the axial clearance is controlled when the bearing is not under load. However, when the steering gear is working, the bearing is subjected to a large axial load. The threaded connection between the adjusting plug and the housing will loosen, and the inner and outer rings of the bearing will rotate relative to the surfaces in contact with them. This will cause wear on the end faces of the inner and outer rings and the surfaces in contact with them, increasing the axial clearance between bearings 8 and 12. Ultimately, this will lead to reduced bearing life, transmission accuracy, and abnormal noise. In addition, due to the characteristics of angular contact ball bearings and tapered roller bearings, the axial clearance will cause radial clearance between the inner and outer rings, resulting in a decrease in the support stiffness of the screw.

[0005] (3) When the vehicle turns, the radial force on the original steering screw 9 mainly comes from the meshing transmission between the rack on the original steering nut 10 and the gear sector on the rocker arm shaft 13. Since the original steering nut 10 is a square nut and there is no contact between it and the original housing 11, the radial force will act on the original steering screw 9, causing the original steering screw 9 to undergo large bending deformation. After long-term operation, pitting will occur on the spiral raceway of the original steering screw 9 and the original steering nut 10, which will increase the friction of the ball screw pair and aggravate the wear of the bearing. Utility Model Content

[0006] The technical problem to be solved by this utility model is to provide a steering screw support structure for an electric recirculating ball steering gear, which has a simple structure, low cost, small size, low wear, and higher support rigidity.

[0007] To solve the above problems, the present invention adopts the following technical solution: An electric recirculating ball steering gear steering screw support structure includes a housing, a steering screw, a steering nut, a lead screw ball, and a rocker arm shaft. A needle roller bearing is interference-fitted to the left end of the housing, and a four-point contact ball bearing is installed on the right end of the housing. The steering nut is rotatably connected within the needle roller bearing and the four-point contact ball bearing. An adjusting plug is threadedly connected within the housing, located at the right end of the four-point contact ball bearing. The rocker arm shaft is connected to the housing. The steering nut is internally housed within the housing and meshes with the rocker arm shaft. The lead screw ball is rollingly connected between the steering nut and the steering screw.

[0008] A further technical solution is that the four-point contact ball bearing includes a disc-shaped boss, bearing steel balls, and two oppositely arranged bearing races. The disc-shaped boss is located at the right end of the steering screw, the bearing races are built into the housing and located to the left of the adjusting screw, and the bearing steel balls are located between the two bearing races and the disc-shaped boss.

[0009] A further technical solution is that the left end of the steering screw is machined with journals that mate with needle roller bearings, the disc-shaped boss is provided with an inner annular raceway, the middle end of the steering screw is provided with a helical raceway, and the bearing race is also provided with an outer annular raceway.

[0010] A further technical solution is that the contact angle B between the inner and outer annular raceways and the bearing steel balls is greater than or equal to 45°. The housing has housing cylinder holes distributed inside. The steering nut is located inside the housing cylinder holes and can be moved left and right. The radius of the contact point between the bearing steel balls and the outer annular raceway is greater than the radius of the housing cylinder holes inside the housing. The radius of the contact point between the bearing steel balls and the outer annular raceway refers to the radius distance L between the contact points of the bearing steel balls located on the upper and lower sides of the entire outer annular raceway and the outer annular raceway, as shown in Figure 2.

[0011] A further technical solution is that the disc-shaped boss and the steering screw are an integral structure, which facilitates production.

[0012] A further technical solution is that a turbine, a conventional component, is fixed to the right end of the steering screw.

[0013] A further technical solution is that the housing has housing seat holes and bearing seat holes distributed inside. The needle roller bearing is fixed in the housing seat hole by interference fit. The bearing race is built into the bearing seat hole. Threads are also distributed on the inner wall of the housing and on the right side of the bearing seat hole. The adjusting plug is threadedly connected to the thread on the right side of the bearing seat hole. The bearing race is installed in the corresponding bearing seat hole of the housing and is axially positioned by a step on the housing. The contact width between each bearing race and the bearing seat hole is not less than half the width of the bearing race. The left and right opposite small end faces of the two bearing races are in contact with each other.

[0014] The beneficial effects of the steering screw support structure for an electric recirculating ball steering system of this utility model are: 1. Since four-point contact ball bearings can withstand both bidirectional axial and radial forces simultaneously, only one is needed to meet the axial support requirements of the steering screw. The needle roller bearing on the other side only needs to provide a portion of the radial support. Furthermore, needle roller bearings have a large radial load capacity and a small size, which can make the overall structure more compact. 2. The two bearing races have a large contact width with the bearing housing holes on the housing, so they are completely positioned radially. The axial clearance of the four-point contact ball bearing is ensured by the bearing steel balls. The end faces of the two bearing races fit together. During assembly, the adjusting plug is tightened directly, and the two races are completely fixed. During the operation of the steering gear, the end faces of the races will hardly wear, and no additional anti-loosening measures are required for the adjusting plug. Therefore, assembly and adjustment are more convenient. 3. The outer ring of the needle roller bearing and the housing bore have a large interference fit. After pressing it into the housing bore, it does not need to be fixed by riveting or other parts, which simplifies the assembly process and product structure. In addition, the outer ring of the needle roller bearing is axially positioned by the step in the housing, which can accurately control the axial position of the bearing during the assembly process. 4. Most of the radial force on the steering screw comes from the radial force generated by the rack and pinion drive on the steering nut. With a piston-type steering nut, there is always contact between the steering nut and the housing during operation. The housing can withstand a portion of the radial force on the steering nut, reducing the radial force on the steering screw, thereby reducing the bending deformation of the steering screw and improving its service life. In addition, since the housing bears a portion of the radial force, the radial load capacity of the four-point contact ball bearing can also be slightly reduced. Therefore, in steering gears with large output torque, provided that the radial load capacity of the four-point contact ball bearing is sufficient, the contact angle of the four-point contact ball bearing is larger, which improves the axial load capacity. 5. Compared to two angular contact ball bearings or tapered roller bearings, four-point contact ball bearings plus needle roller bearings are cheaper and can eliminate the need for a lock nut, thus offering a cost advantage. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the accompanying drawings required for the work described in the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the original electric recirculating ball steering gear steering screw support structure. Figure 2This is a schematic diagram of the steering screw support structure of an electric recirculating ball steering gear according to the present invention; Figure 3 This utility model Figure 2 An enlarged schematic diagram of point A in the middle.

[0017] Figure 4 This is a schematic diagram of the steering screw in the steering screw support structure of an electric recirculating ball steering gear according to this utility model.

[0018] Figure 2-4 In the middle: 17-Cylinder bore of housing, 18-Outer annular raceway, 19-Bearing seat bore, 20-Housing seat bore, 21-Housing, 22-Needle roller bearing, 23-Steering screw, 24-Steering nut, 25-Rocker arm shaft, 26-Bearing seat ring, 27-Bearing steel ball, 28-Adjusting plug, 29-Screw steel ball, 30-Box body, 31-Top cover, 32-Input shaft, 33-Torsion bar, 34-Sensor, 231-Junior journal, 232-Helical raceway, 233-Disc boss, 234-Inner annular raceway. Detailed Implementation

[0019] The preferred embodiments of this utility model will be described in detail below so that the advantages and features of this utility model can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of this utility model.

[0020] See Figure 2 and Figure 4 As shown, an electric recirculating ball steering gear steering screw support structure includes a housing 21, a steering screw 23, a steering nut 24, a lead screw ball 29, and a rocker arm shaft 25. A needle roller bearing 22 is interference-fitted to the left end of the housing 21, and a four-point contact ball bearing is installed on the right end of the housing 21. The steering nut 24 is rotatably connected to the needle roller bearing 22 and the four-point contact ball bearing. An adjusting plug 28 is threadedly connected to the right end of the four-point contact ball bearing inside the housing 21. The rocker arm shaft 25 is connected to the housing 21. The steering nut 24 is built into the housing 21 and meshes with the rocker arm shaft 25. The lead screw ball 29 is rollingly connected between the steering nut 24 and the steering screw 23.

[0021] The four-point contact ball bearing includes a disc-shaped boss 233, bearing balls 27, and two opposing bearing races 26. The disc-shaped boss 234 is located at the right end of the steering screw 23. The bearing races 26 are housed within the housing 21 and located to the left of the adjusting plug 28. The bearing balls 27 are located between the two bearing races 26 and the disc-shaped boss 234. The left end of the steering screw 23 has journals 231 that mate with the needle roller bearing 22. The disc-shaped boss 234 has an inner annular raceway 234. The middle end of the steering screw 23 has a helical raceway 232. The bearing races 26 also have an outer annular raceway 18. The contact angle B between the inner annular raceway 234 and the outer annular raceway 18 and the bearing steel ball 27 is greater than or equal to 45°. The housing 21 has housing cylinder bores 17 distributed within it. The steering nut 24 is located within the housing cylinder bores 17 and can move left and right. The radius of the contact point between the bearing steel ball 27 and the outer annular raceway 18 is greater than the radius of the housing cylinder bores 17 within the housing 21. The radius of the contact point between the bearing steel ball 27 and the outer annular raceway 18 refers to the radial distance L between the contact points of the bearing steel balls 27 located on the upper and lower sides of the entire outer annular raceway 18 and the outer annular raceway 18. Figure 2 As shown. The disc-shaped boss 233 and the steering screw 23 are an integral structure, which facilitates production. The right end of the steering screw 23 is fixed with a turbine 29, a conventional component. The housing 21 has housing seat holes 20 and bearing seat holes 19. The needle roller bearing 22 is fixed in the housing seat hole 20 by interference fit. The bearing race 26 is built into the bearing seat hole 19. Threads 36 are also distributed on the inner wall of the housing 21 and on the right end of the bearing seat hole 19. The adjusting plug 28 is threadedly connected to the thread 36 on the right end of the bearing seat hole 19. The bearing race 26 is installed in the corresponding bearing seat hole 19 of the housing 21 and is axially positioned by the step on the housing 21. The contact width between each bearing race 26 and the bearing seat hole 19 is not less than half the width of the bearing race 26. The left and right opposite small end faces of the two bearing races 26 are in contact with each other.

[0022] In this embodiment, a housing 30 is bolted to the right side of the housing 21, and a top cover 31 is bolted to the right side of the housing 30. A sensor 34, an input shaft 32, and a torsion bar 33 are installed inside the top cover 31. These are all conventional components. When the driver turns the steering wheel, the steering torque acts on the input shaft 32, causing the upper and lower ends of the torsion bar 33 to deform relative to each other. The sensor 34 determines the magnitude and direction of the input torque based on the magnitude of this deformation. The ECU then combines the vehicle speed signal to control the motor and output the corresponding steering torque through the worm gear and turbine 29 on the motor. This drives the steering screw 23 to rotate. The rotational motion of the steering screw 23 through the lead screw ball 29 is converted into the axial movement of the steering nut 24. Since the steering nut 24 is engaged with the rocker arm shaft 25, the movement of the steering nut 24 will cause the rocker arm shaft 25 to rotate, which will drive the steering drop arm to rotate, and then the wheels will rotate through the steering transmission mechanism.

[0023] In this design, a four-point contact ball bearing structure is used on the steering screw 23 as axial and radial support to bear all the axial force and part of the radial force on the steering screw 23. The end face of the disc boss 233 has the function of limiting the maximum displacement of the steering nut 24. After the small end faces of the two bearing races 26 are put together, a complete outer annular raceway 18 is formed. The bearing races 26 are installed in the bearing seat holes 19 of the housing 21 and are axially positioned by the step between the housing cylinder hole 17 and the bearing seat hole 19 in the housing 21. The four-point contact ball bearing is fixed by adjusting the plug 28. The left end of the adjusting plug 28 is provided with a support foot that contacts the end face of the bearing race 26. After the adjusting plug 28 is screwed into the thread 36 of the housing 21 and tightened, the position of the steering screw 23 and the two bearing races 26 relative to the housing 1 is completely fixed.

[0024] At the lower end of the steering screw 23, a needle roller bearing 22 is used as a radial support to improve the radial support stiffness of the steering screw 23. The needle roller bearing 22 is axially positioned through the step at the housing seat hole 20 on the housing 21. The outer ring of the needle roller bearing 22 and the housing seat hole 20 of the housing 21 have a large interference fit. It is pressed into the housing seat hole 20 by pressure. Due to the large interference fit, it does not need to be fixed by riveting or other parts after being pressed into the housing seat hole 20, which simplifies the assembly process and product structure. The inner diameter of the needle roller bearing 22 and the journal 231 of the steering screw 23 have a clearance fit. The needle roller bearing 22 has a large radial load capacity and a small size, which is beneficial to shorten the overall size of the steering gear.

[0025] In the middle of the steering screw 23, a steering nut 24 provides radial support for the steering screw 23. The steering nut 24 is a piston type, and its outer contour is machined with an outer circular surface that mates with the housing cylinder bore 17 inside the housing 21. The outer circle of the steering nut 24 and the housing cylinder bore 17 inside the housing 21 are in clearance fit. When the steering gear is working, the housing cylinder bore 17 inside the housing 21 can provide radial support and guidance for the steering nut 24. Part of the radial force on the steering nut 24 is borne by the housing 21, which can further improve the radial support stiffness of the steering screw 23, reduce the radial force and bending deformation on the steering screw 23, and improve the service life of the steering screw 23. In addition, since the steering screw 24 bears part of the radial force, the radial load capacity of the four-point contact ball bearing can be slightly reduced. Therefore, the contact angle of the four-point contact ball bearing can be appropriately increased to improve the axial load capacity.

[0026] Similarly, the positions of the needle roller bearing 22 and the four-point contact ball bearing within the housing 21 can be interchanged. That is, the four-point contact ball bearing is located on the left side, and the adjusting plug 28 is threadedly connected within the housing 21 and located on the left side of the four-point contact ball bearing, while the needle roller bearing 22 is located on the right side within the housing 21, achieving the same effect.

[0027] The above description is only a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions that are conceived without creative effort should be covered by the protection scope of this utility model.

Claims

1. A steering screw support structure for an electric recirculating ball steering system, comprising a housing, a steering screw, a steering nut, a lead screw ball, and a rocker arm shaft, characterized in that: The left end of the housing is fixed with an interference fit needle roller bearing, the right end of the housing is installed with a four-point contact ball bearing, the steering nut is rotatably connected in the needle roller bearing and the four-point contact ball bearing, the housing is threaded with an adjusting plug located in the right end of the four-point contact ball bearing, the rocker arm shaft is connected to the housing, the steering nut is built into the housing and meshes with the rocker arm shaft, and the lead screw ball is rolled between the steering nut and the steering screw.

2. The steering screw support structure for an electric recirculating ball steering gear according to claim 1, characterized in that: The four-point contact ball bearing includes a disc-shaped boss, bearing steel balls, and two opposing bearing races. The disc-shaped boss is located at the right end of the steering screw. The bearing races are built into the housing and located to the left of the adjusting screw. The bearing steel balls are located between the two bearing races and the disc-shaped boss.

3. The steering screw support structure for an electric recirculating ball steering gear according to claim 2, characterized in that: The left end of the steering screw is machined with journals that mate with needle roller bearings, the disc-shaped boss is provided with an inner annular raceway, the middle end of the steering screw is provided with a helical raceway, and the bearing race is also provided with an outer annular raceway.

4. The steering screw support structure for an electric recirculating ball steering gear according to claim 3, characterized in that: The contact angle B between the inner and outer annular raceways and the bearing steel balls is greater than or equal to 45°. The housing has housing cylinder holes distributed inside. The steering nut is located inside the housing cylinder holes and can be moved left and right. The radius of the contact point between the bearing steel balls and the outer annular raceway is greater than the radius of the housing cylinder holes inside the housing.

5. The steering screw support structure for an electric recirculating ball steering gear according to claim 1, characterized in that: The disc-shaped boss and the steering screw are an integral structure.

6. The steering screw support structure for an electric recirculating ball steering gear according to claim 1, characterized in that: A turbine is fixed to the right end of the steering screw.

7. The steering screw support structure for an electric recirculating ball steering gear according to claim 1, characterized in that: The housing has housing seat holes and bearing seat holes distributed inside. The needle roller bearing is fixed in the housing seat hole by interference fit. The bearing race is built into the bearing seat hole. Threads are also distributed on the inner wall of the housing and on the right side of the bearing seat hole. The adjusting plug is threadedly connected to the thread on the right side of the bearing seat hole.

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