Steering machine and nut

Abstract

The utility model provides a steering machine and a nut, the steering machine comprises a rotating rod, the nut and an output shaft, the rotating rod is sleeved with the nut, the nut can be driven by rotation of the rotating rod to move in the axial direction, a straight tooth rack is arranged on the nut in the axial direction, and the straight tooth rack is driven by rotation of the rotating rod to move in the axial direction. Paired straight teeth matched with the straight tooth rack are arranged in the circumferential direction of the output shaft, and the straight tooth rack is arranged in the mode that the modulus of the teeth of the straight tooth rack is gradually reduced from the tooth top to the tooth root. According to the steering engine, through the variable modulus design of the teeth on the nut, adjustment of the rotation ratio between the nut and the output shaft under different steering conditions is achieved; the steering torque is matched with different steering conditions only by changing a mechanical structure, the stability and accuracy of vehicle steering are improved, the cost is low, and application is convenient.

Description

Technical Field

[0001] This application relates to the field of vehicle steering technology, and more specifically, to a steering gear and a nut. Background Technology

[0002] Steering gears are important devices for enabling vehicles, especially large vehicles, to turn. They work by using a motor to drive a transmission device to output the motor's driving torque to the output shaft, thereby achieving the output of steering torque.

[0003] In known steering gears, power transmission is achieved between the transmission device and the output shaft through gear transmission. The output shaft is generally equipped with a helical gear that matches the transmission device in the circumferential direction. The transmission ratio between the transmission device and the output shaft remains constant under different steering conditions.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Utility Model Content

[0005] Depending on the specific circumstances, one of the technical problems this application aims to solve is how to adjust the transmission ratio of the steering gear mechanism to suit different steering conditions.

[0006] In addition, this application aims to solve or alleviate other technical problems existing in the prior art.

[0007] According to one aspect of this application, the following is provided:

[0008] A steering gear includes a rotating rod, a nut, and an output shaft. The nut is fitted onto the rotating rod and can be driven by the rotation of the rotating rod to move in an axial direction. A spur rack is provided on the nut in the axial direction. Paired spurs that cooperate with the spur rack are provided on the output shaft in the circumferential direction. The spur rack is configured such that the module of its teeth gradually decreases from the tooth tip to the tooth root.

[0009] According to another aspect of this application, this application provides a nut, wherein the nut is used to be fitted on the rotating rod of a steering gear and can be driven by the rotation of the rotating rod to move in the axial direction, and a spur rack is provided on the nut in the axial direction for cooperating with a matching spur gear provided on the output shaft of the steering gear to realize power transmission, and the spur rack is configured such that the module of its teeth gradually decreases from the tooth tip to the tooth root.

[0010] The advantages of this application include at least the following:

[0011] 1. In one embodiment of this application, the steering gear has a variable module design for the teeth of the spur rack on the nut, and the mating spurs on the output shaft are also set to have different pressure angles with the spur rack at different contact positions. By changing the mechanical structure, different transmission ratios are achieved between the nut and the output shaft under different steering wheel steering angles, so as to achieve more accurate output of matching steering torque for different steering conditions, thereby improving the accuracy and stability of vehicle steering.

[0012] 2. In one embodiment of this application, the housing cover of the steering gear is configured with an eccentric structure, and the free clearance of the output shaft can be adjusted by rotating the housing cover, thereby allowing the transmission ratio between the output shaft and the nut to be manually adjusted to a certain extent.

[0013] 3. In one embodiment of this application, the ball screw of the steering gear adopts an internal circulation structure to guide the movement of the balls, avoiding the use of a semi-tube structure outside the nut, preventing the semi-tube structure from cracking due to excessive external force, and at the same time enabling the balls to pass more smoothly in the return ball channel. Attached Figure Description

[0014] Referring to the accompanying drawings, the above and other features of this application will become apparent, wherein,

[0015] Figure 1 A schematic diagram of the overall structure of a steering gear according to one embodiment of this application is shown;

[0016] Figure 2 A cross-sectional view is shown at the meshing point of the spur rack of the nut and the paired spurs of the output shaft, according to one embodiment of the present application.

[0017] Figure 3 A schematic diagram of the structure of the housing cover of a steering gear according to one embodiment of this application is shown;

[0018] Figure 4 A schematic diagram of the structure of a ball screw for a steering gear according to one embodiment of this application is shown;

[0019] Figure 5 A schematic diagram of the structure of a steering gear return mechanism according to one embodiment of this application is shown. Detailed Implementation

[0020] It is readily understood that, based on the technical solution of this application, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of this application. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this application and should not be considered as the entirety of this application or as limitations or restrictions on the technical solution of this application.

[0021] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the structures shown in the accompanying drawings. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive. Furthermore, the terms "first," "second," "third," and similar expressions are used for descriptive and distinguishing purposes only and should not be construed as indicating or implying the relative importance of the corresponding components or the order of components or assembly sequence.

[0022] A vehicle's steering performance is closely related to both the steering wheel angle and vehicle speed. Under normal steering conditions, there is inevitably a certain correlation between the steering wheel angle and vehicle speed. For example, when the steering wheel is in the center position, i.e., the steering wheel angle is very small, the vehicle is generally traveling in a straight line at a relatively high speed, requiring only a small steering torque to steer. Conversely, when the steering wheel is at its limit (very large steering angle), i.e., the steering wheel angle is very large, the vehicle may be making a sharp turn or U-turn, requiring a larger steering torque to steer.

[0023] However, for known steering gears, although the torque output by the motor is determined by the steering wheel angle, the transmission ratio between the transmission device and the output shaft remains constant. In this case, the steering torque is generally a fixed function of the steering wheel angle, making it impossible to adjust the steering torque more appropriately in some extreme steering situations (when the steering wheel angle is very small or very large).

[0024] refer to Figure 1 and Figure 2 The diagrams show an overall structural schematic of a steering gear 10 according to one embodiment of the present application, and a cross-sectional view of the steering gear 10 at the meshing point of the spur rack 201 of the nut 200 and the mating spur gear 301 of the output shaft 300. The steering gear 10 in this embodiment includes a housing 400, an input shaft 500, and a sensor (arranged within the housing 400). Figure 1 and 2(Not specifically shown in the diagram) Controller 600, drive mechanism 700, transmission mechanism 800, rotating rod 100, nut 200, and output shaft 300. Input shaft 500 is coaxially arranged with rotating rod 100, and is connected to rotating rod 100 via a torsion spring. The input end of transmission mechanism 800 is connected to drive mechanism 700, and the output end is connected to rotating rod 100. Nut 200 is fitted onto rotating rod 100 and can be driven by rotation of rotating rod 100 to move axially. A spur rack 201 is provided on nut 200 axially, and a mating spur tooth 301 that engages with spur rack 201 is provided on output shaft 300 circumferentially.

[0025] When the vehicle steering wheel is turned, it drives the input shaft 500 to rotate, causing an angular deviation between the input shaft 500 and the rotating rod 100. The sensor collects this angular deviation and converts it into a corresponding electrical signal, which is then transmitted to the controller 600. The controller 600 controls the drive mechanism 700 to generate a corresponding drive torque based on this electrical signal. This torque is then transmitted through the transmission mechanism 800 to rotate the rotating rod 100, and further through the nut 200 to rotate the output shaft 300. Finally, the steering torque is output through the output shaft 300.

[0026] exist Figure 2In one embodiment, the spur rack 201 is configured such that the module of its teeth gradually decreases from the tooth tip to the tooth root. Further, in one embodiment, the paired spur teeth 301 and the spur rack 201 are configured such that the pressure angle between a single paired spur tooth 301 and the spur rack 201 gradually increases from a fully engaged state to a disengaged state. This variable module design of the spur rack 201 and the variable pressure angle design between the paired spur teeth 301 and the spur rack 201 cause a change in the transmission ratio during relative motion between the spur rack 201 and the paired spur teeth 301. When the rotation angle of the mating spur teeth 301 is small, the teeth are close to being fully engaged. The contact point between the teeth on the spur rack 201 and the mating spur teeth 301 is close to the root of the tooth with a smaller module. In this case, the pressure angle between the spur rack 201 and the mating spur teeth 301 is small, resulting in a smaller transmission ratio between them. Consequently, the final output steering torque is smaller than when the transmission ratio remains constant due to the smaller transmission ratio. When the rotation angle of the mating spur teeth 301 is large, the teeth are close to being disengaged. The contact point between the teeth on the spur rack 201 and the mating spur teeth 301 is close to the tip of the tooth with a larger module. In this case, the pressure angle between the spur rack 201 and the mating spur teeth 301 is large, resulting in a larger transmission ratio between them. Consequently, the final output steering torque is larger than when the transmission ratio remains constant due to the larger transmission ratio. This design enables a variable transmission ratio between the nut 200 and the output shaft 300, allowing for a more suitable steering torque to be achieved by changing the transmission ratio, compared to a steering gear with a known, constant transmission ratio, under extreme steering conditions.

[0027] refer to Figure 3 This shows a structural schematic diagram of the housing cover 310 of a steering gear 10 according to one embodiment of this application. Figure 1 In this embodiment, the output shaft 300 is supported on the housing 400 by two housing covers 310. Figure 3As can be seen, the housing cover 310 is configured as an annular structure through which the output shaft 300 can pass, with the inner ring 311 and outer ring 312 of the annular structure being eccentrically positioned. In one embodiment of this application, the inner ring 311 and outer ring 312 have an eccentricity of 0.5 to 1.5 mm, preferably 1 mm. Due to the eccentric structure of the housing cover 310, the free clearance between the output shaft 300 and the nut 200 can be adjusted by rotating the housing cover 310, thereby making the transmission ratio between the nut 200 and the output shaft 300 adjustable. In one embodiment of this application, two adjustment holes 313 are provided on the surface of the annular structure of the housing cover 310 facing away from the housing 400. An external adjustment mechanism (such as a screwdriver) can be inserted into the adjustment holes 313 to rotate the housing cover 310, thereby adjusting the free clearance between the nut 200 and the output shaft 300.

[0028] refer to Figure 4 This illustrates a schematic diagram of the structure of the ball screw of a steering gear 10 according to one embodiment of this application. Figure 4 In this embodiment, the rotating rod 100 is configured as a lead screw, and the nut 200 is provided with a helical groove 202 for accommodating balls 210. The nut 200 and the lead screw achieve relative movement through the balls 210, thereby allowing the nut 200 to move smoothly along the axial direction on the lead screw by screwing. (Reference) Figure 5 This diagram illustrates the structure of a return mechanism 220 of a steering gear 10 according to one embodiment of this application. The return mechanism 220 is arranged between the nut 200 and the lead screw, and is used to guide the movement of the balls 210 so that the nut 200 can move more smoothly on the lead screw via the balls 210. The movement of the balls 210 between the nut 200 and the return mechanism 220 is referred to as the inner circulation of the balls 210, because the balls 210 remain within the inner ring of the nut 200 during their movement and do not move to the outer ring. The return mechanism 220 is provided with parallel ball return channels 230. Preferably, the number of ball return channels 230 is the same as the number of helical grooves 202 of the nut 200, and each ball return channel 230 is connected to one helical groove 202 of the nut 200.

[0029] In a known steering gear, the ball screw uses an external circulation method, employing a half-tube to guide the movement of the balls. This half-tube is positioned outside the nut. When the nut is subjected to radial force deformation, the half-tube is susceptible to additional force, leading to cracking or damage. Furthermore, each half-tube typically connects to multiple helical grooves of the nut, resulting in numerous balls passing through each half-tube, potentially causing ball congestion. The return mechanism 220 solves these problems. The return mechanism 220 is positioned entirely between the inner ring of the nut 200 and the output shaft 300, minimizing the impact of nut 200 deformation. Additionally, the return mechanism 220 includes a return ball channel 230 that matches each helical groove 202, preventing ball congestion and jamming in the return ball channel 230 and allowing for smoother ball movement.

[0030] In one embodiment of this application, the return ball channel 230 includes a raceway section 231, a transition section 232, and a return ball section 233 connected in sequence (for ease of distinction, in...). Figure 5 The boundary between the transition section 232 and the return section 233 is only schematically shown by a dashed line. The raceway section 231 connects to the helical groove 202 of the nut 200. The depths of the raceway section 231, the transition section 232, and the return section 233 in the returner 230 increase sequentially, with the depth of the return section 233 being greater than or equal to the diameter of the ball 210. By setting three sections with progressively increasing depths, the return channel 230 enables smoother movement of the ball 210.

[0031] In one embodiment of this application, the drive mechanism 700 is configured as a motor, and the transmission mechanism 800 is configured as a worm gear transmission mechanism, with the worm coaxially connected to the output shaft of the motor, and the worm wheel coaxially connected to the lead screw. Thus, the transmission device of the entire steering gear 10 includes the aforementioned transmission mechanism 700, ball screw mechanism, and nut 200, and transmits the torque output by the motor to the output shaft 300 to output steering torque.

[0032] It should be understood that those skilled in the art may also choose any other suitable mechanical transmission mechanism as the aforementioned transmission mechanism, such as bevel gear transmission mechanism, gear and rack transmission mechanism, etc., which should also be included within the scope of protection of this application.

[0033] Another aspect of this application proposes a nut 200, which is fitted onto the rotating rod 100 of the steering gear 10 and can be driven by the rotation of the rotating rod 100 to move in the axial direction. A spur rack 201 is provided on the nut 200 in the axial direction to cooperate with a matching spur tooth 301 provided on the output shaft 300 of the steering gear 10, thereby realizing power transmission. The spur rack 201 is configured such that the module of its teeth gradually decreases from the tooth tip to the tooth root.

[0034] In one embodiment of this application, a spiral groove 202 for accommodating ball bearings 210 is provided on the inner ring of the nut 200, and the nut 200 achieves relative movement with the rotating rod 100 configured as a lead screw through the ball bearings 210.

[0035] In one embodiment of this application, a mounting groove 203 for mounting a reversing device 220 is provided on the inner ring of the nut 200.

[0036] One embodiment of this application proposes a steering gear that achieves adjustment of the rotation ratio between the nut and the output shaft under different steering conditions through the variable module design of the teeth on the nut. The steering torque is adapted to different steering conditions by only changing the mechanical structure, which improves the stability and accuracy of vehicle steering. Moreover, it is low in cost and easy to apply.

[0037] It should be understood that all the above preferred embodiments are exemplary and not restrictive, and various modifications or variations made by those skilled in the art to the specific embodiments described above under the concept of this application should be within the scope of legal protection of this application.

Claims

1. A steering gear, characterized in that, The steering gear includes a rotating rod, a nut, and an output shaft. The nut is fitted onto the rotating rod and can be driven by the rotation of the rotating rod to move in the axial direction. A spur rack is provided on the nut in the axial direction. Paired spurs that cooperate with the spur rack are provided in the circumferential direction of the output shaft. The spur rack is configured such that the module of its teeth gradually decreases from the tooth tip to the tooth root.

2. The steering gear according to claim 1, characterized in that, The paired spur teeth and spur rack are configured such that the pressure angle between a single paired spur tooth and the spur rack gradually increases from a fully engaged state to a disengaged state.

3. The steering gear according to claim 1, characterized in that, The steering gear also includes a housing, and the output shaft is supported on the housing by at least one housing cover, the housing cover being configured as an annular structure through which the output shaft can pass, the inner and outer rings of the annular structure being eccentrically arranged.

4. The steering gear according to claim 3, characterized in that, The inner ring and the outer ring have an eccentricity of 0.5 to 1.5 mm.

5. The steering gear according to claim 3, characterized in that, An adjustment hole is provided on the surface of the annular structure that faces away from the housing.

6. The steering gear according to claim 1, characterized in that, The rotating rod is configured as a lead screw, and the nut is provided with a helical groove for accommodating balls. The nut and the lead screw achieve relative movement through the balls.

7. The steering gear according to claim 6, characterized in that, A return device is provided between the nut and the lead screw, and a ball return channel is provided on the return device, with each ball return channel connected to a helical groove of the nut to realize the internal circulation of the ball screw.

8. The steering gear according to claim 7, characterized in that, The ball return channel includes a raceway section, a transition section, and a ball return section connected in sequence. The raceway section is connected to the helical groove of the nut. The depths of the raceway section, the transition section, and the ball return section in the return mechanism increase sequentially. The depth of the ball return section is greater than or equal to the diameter of the ball.

9. The steering gear according to claim 1, characterized in that, The steering gear also includes an input shaft, a sensor, a controller, a drive mechanism, and a transmission mechanism. The input shaft is coaxially arranged with the rotating rod via a torsion spring. The input end of the transmission mechanism is connected to the drive mechanism, and the output end is connected to the rotating rod. The sensor collects the angular deviation between the input shaft and the rotating rod and sends the corresponding sensor signal to the controller. The controller controls the drive mechanism to drive the rotating rod to rotate through the transmission mechanism, and further drives the output shaft to rotate through the transmission of the nut.

10. The steering gear according to claim 9, characterized in that, The driving mechanism is configured as a motor, and the transmission mechanism is configured as a worm gear transmission mechanism. The worm is coaxially connected to the output shaft of the motor, and the worm wheel is coaxially connected to the rotating rod.

11. A nut, characterized in that, The nut is used to be fitted onto the rotating rod of the steering gear and can be driven by the rotation of the rotating rod to move in the axial direction. A spur rack is provided on the nut in the axial direction to cooperate with the matching spurs provided on the output shaft of the steering gear, thereby realizing power transmission. The spur rack is configured such that the module of its teeth gradually decreases from the tooth tip to the tooth root.

12. The nut according to claim 11, characterized in that, The inner ring of the nut is provided with a helical groove for accommodating balls, and the nut achieves relative movement with the rotating rod configured as a lead screw through the balls.

13. The nut according to claim 12, characterized in that, A mounting groove for mounting a reversing device is provided on the inner ring of the nut.

Images