External circulation type screw and nut structure for commercial vehicle

Abstract

The utility model discloses an external circulation type screw nut structure for commercial vehicles, which comprises a lead screw, a nut, a rocker arm shaft and a steering gear shell, the lead screw is arranged in the steering gear shell, the nut on the lead screw is meshed with one end of the rocker arm shaft, an external circulation type steel ball, a raceway and a guide pipe are arranged in the nut, and the rocker arm shaft is meshed with the guide pipe. A variable-pitch-diameter area is arranged at the joint of the roller path and the steel ball circulating inlet and outlet of the guide pipe; further, the variable pitch diameter of the variable pitch diameter area is phi D0-phi D0 + a, and a force release area is formed when the external circulation type steel ball passes through the variable pitch diameter area; a torsion bar is arranged at the upper end of the lead screw, and the lead screw is connected with an input shaft through the torsion bar. The variable pitch diameter area is arranged on the nut, the pitch diameter value phi D is gradually increased by phi D0 + a from the original pitch diameter value phi D0, a slow unloading area is formed, when the circulating steel ball reaches a guide pipe or a roller path, the load is slowly reduced or increased, and the guide pipe is prevented from failure caused by sudden change of the load.

Description

Technical Field

[0001] This utility model relates to the technical field of steering gear screw and nut, specifically to an external circulation screw and nut structure for commercial vehicles. Background Technology

[0002] With the increasing popularity of electric power steering in passenger vehicles, the power steering system in commercial vehicles is also shifting from hydraulic to pure electric. Due to the larger output torque of commercial vehicle products, the screw and nut in pure electric power steering bear a greater load. When the externally circulating steel ball enters the guide tube from the raceway or vice versa, the force on the steel ball suddenly decreases or increases because the guide tube diameter is larger than the steel ball. This sudden change in force often causes the guide tube to break, leading to product failure. Therefore, the original hydraulic screw and nut external circulation structure is insufficient to support the durable cyclic operation of the product. To address these issues, an external circulation screw and nut structure for commercial vehicles is proposed. Utility Model Content

[0003] The technical problem to be solved by this utility model is to overcome the existing defects and provide an external circulation screw nut structure for commercial vehicles. A variable pitch diameter area is set on the nut, and the pitch diameter value φD gradually increases from the original pitch diameter value φD0 to φD0+a, forming a slow unloading zone. When the circulating steel ball reaches the guide or raceway, the load decreases or increases slowly, so that the guide is free from failure caused by sudden load changes. This can effectively solve the problems in the background art.

[0004] To achieve the above objectives, this utility model provides the following technical solution: an external circulation screw and nut structure for commercial vehicles, comprising a lead screw, a nut, a rocker arm shaft, and a steering gear housing. The lead screw is disposed in the steering gear housing, and the nut on the lead screw meshes with one end of the rocker arm shaft. An external circulation steel ball, a raceway, and a guide tube are disposed inside the nut. A variable diameter area is provided at the connection between the steel ball circulation inlet and outlet of the raceway and the guide tube.

[0005] Furthermore, the variable mean diameter of the variable mean diameter region is φD0-φD0+a, where the value of a ranges from 0 to 0.5 mm. The external circulation steel ball forms a force release zone as it passes through the variable mean diameter region.

[0006] Furthermore, a torsion bar is provided at the upper end of the lead screw, and the lead screw is connected to an input shaft through the torsion bar. A sensor for monitoring the deformation of the torsion bar is provided in the steering gear housing.

[0007] Furthermore, it also includes a power steering mechanism, which includes a motor controller, a worm gear, and a worm wheel. The worm wheel is mounted on the top of the lead screw and meshes with the worm. The motor controller is located on the outside of the steering gear housing, and the worm gear is connected to the output shaft of an external motor.

[0008] Compared with the prior art, the beneficial effects of this utility model are:

[0009] A variable pitch diameter area is set on the nut, where the pitch diameter φD gradually increases from the original pitch diameter φD0 to φD0+a, forming a slow unloading zone. This allows the load to decrease or increase slowly when the circulating steel ball reaches the guide tube or raceway, preventing the guide tube from failing due to sudden load changes. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the internal structure of the electric steering system of this utility model;

[0011] Figure 2 This is a schematic diagram of the external circulation type screw and nut structure of this utility model;

[0012] Figure 3 This is a schematic diagram of the nut structure of this utility model;

[0013] Figure 4 This is a schematic diagram of the cross-sectional structure of the nut of this utility model;

[0014] Figure 5 This is a schematic diagram showing the position and force of the steel ball before the improvement of this utility model;

[0015] Figure 6 This is a schematic diagram showing the position and force of the improved steel ball in this utility model;

[0016] Figure 7 This is a schematic diagram of the variable mean diameter range of this utility model.

[0017] In the diagram: 1 Input shaft, 2 Torsion bar, 3 Sensor, 4 Motor controller, 5 Worm gear, 6 Worm wheel, 7 Lead screw, 8 Nut, 9 Rocker arm shaft, 10 External circulation steel ball, 11 Conduit, 12 Raceway, 13 Steering gear housing, 14 Variable pitch diameter area, 15 Force release area, 16 Steel ball circulation inlet / outlet. Detailed Implementation

[0018] In the description of this utility model, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0019] Please see Figure 1-7This utility model provides a technical solution: an external circulation screw and nut structure for commercial vehicles, including a lead screw 7, a nut 8, a rocker arm shaft 9, and a steering gear housing 13. The lead screw 7 is disposed in the steering gear housing 13, and the nut 8 on the lead screw 7 meshes with one end of the rocker arm shaft 9. An external circulation steel ball 10, a raceway 12, and a guide tube 11 are disposed inside the nut 8. A variable mean diameter region 14 is provided at the connection between the steel ball circulation inlet / outlet 16 of the raceway 12 and the guide tube 11. The variable mean diameter of the variable mean diameter region 14 is φD0-φD0+a, where a ranges from 0 to 0.5 mm. A force release zone 15 is formed where the external circulation steel ball 10 passes through the variable mean diameter region 14. Figure 7 As shown, the variable diameter region 14 has an angle range of 0-50° with respect to the steel ball circulation inlet / outlet 16.

[0020] A torsion bar 2 is provided at the upper end of the lead screw 7. The lead screw 7 is connected to the input shaft 1 through the torsion bar 2. A sensor 3 for monitoring the deformation of the torsion bar 2 is provided in the steering gear housing 13. The power assist mechanism includes a motor controller 4, a worm 5, and a worm wheel 6. The worm wheel 6 is installed at the top of the lead screw 7 and meshes with the worm 5. The motor controller 4 is located on the outside of the steering gear housing 13. The worm 5 is connected to the output shaft of an external motor.

[0021] Product working principle: The input shaft 1 rotates, causing the torsion bar 2 to deform. The sensor 3 detects the deformation and sends a signal to the motor controller 4. The motor controller 4 controls the motor to start assisting, driving the worm 5 to rotate. The worm 5 meshes with the worm wheel 6, causing the worm wheel 6 to rotate. The worm wheel 6 is rigidly connected to the lead screw 7. The rotation of the lead screw 7, according to the principle of ball screw, causes the nut 8 to move linearly. The nut 8 drives the rocker arm shaft 9 through tooth meshing to realize product output.

[0022] The outlet of the ball circulation inlet / outlet 16 is set to A, and the inlet is set to B, as follows. Figure 6 As shown, a schematic diagram of the position and forces acting on the steel ball before the improvement; Figure 7 As shown in the diagram, the improved position and force of the steel ball create a force release zone 15, forming a slow unloading zone. When the steel ball reaches the guide or raceway, the load slowly decreases or increases, preventing the guide from failing due to sudden load changes.

[0023] The foregoing has shown and described the basic principles, main features and advantages of this utility model. Various changes and modifications may be made to this utility model without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this utility model as claimed.

Claims

1. A commercial vehicle external circulation type screw and nut structure, comprising a lead screw (7), a nut (8), a rocker arm shaft (9), and a steering gear housing (13), characterized in that: The lead screw (7) is installed in the steering gear housing (13). The nut (8) on the lead screw (7) meshes with one end of the rocker arm shaft (9). The nut (8) is provided with an external circulation steel ball (10), a raceway (12) and a guide tube (11). A variable diameter area (14) is provided at the connection between the steel ball circulation inlet / outlet (16) of the raceway (12) and the guide tube (11).

2. The external circulation type screw and nut structure for commercial vehicles according to claim 1, characterized in that: The variable median diameter of the variable median diameter region (14) is φD0-φD0+a, and the external circulation steel ball (10) forms a force release zone (15) after passing through the variable median diameter region (14).

3. The external circulation type screw and nut structure for commercial vehicles according to claim 2, characterized in that: The value of 'a' ranges from 0 to 0.5 mm.

4. The external circulation type screw and nut structure for commercial vehicles according to claim 1, characterized in that: The upper end of the lead screw (7) is provided with a torsion bar (2), and the lead screw (7) is connected to the input shaft (1) through the torsion bar (2). A sensor (3) for monitoring the deformation of the torsion bar (2) is provided in the steering gear housing (13).

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