阅读说明：本技术 一种汽车电动助力可变转向齿比转向齿条 (Automobile electric power-assisted variable steering gear ratio steering rack ) 是由 施伟 于 2021-06-30 设计创作，主要内容包括：本发明涉及一种汽车电动助力可变转向齿比转向齿条,该齿条包括变节距齿条本体,所述变节距齿条本体上设有一排啮合齿,所述的啮合齿的齿间距按疏、密、疏形式排布,包括中间的小传动比段(a)、对称设于所述小传动比段(a)两侧的过渡段(b)、以及对称设于所述过渡段(b)外侧的大传动比段(c)。本发明通过疏、密、疏形式排布,在高速时有助于保持驾驶稳定,低速时变道灵敏,从而使停车时具有更好的操控性。齿条中心部分的较低传动比可确保在转向操作初始阶段流畅转向动作,齿条两端较高的传动比确保在较大转向角时可在转向操作中获得快速响应,使极限转向角的操作更加容易。(The invention relates to an automobile electric power-assisted variable steering gear ratio steering rack which comprises a variable-pitch rack body, wherein a row of meshing teeth are arranged on the variable-pitch rack body, and the tooth spaces of the meshing teeth are distributed in a sparse, dense and sparse mode. The invention is arranged in a sparse, dense and sparse mode, is favorable for keeping driving stability at high speed, and is sensitive in lane at low speed, so that the invention has better controllability during parking. The lower gear ratio of the central portion of the rack ensures smooth steering action at the initial stage of the steering operation, and the higher gear ratio of the two ends of the rack ensures that a quick response can be obtained in the steering operation at a larger steering angle, so that the operation of the ultimate steering angle is easier.)

1. An automobile electric power-assisted variable steering gear ratio steering rack comprises a variable-pitch rack body, wherein a row of meshing teeth are arranged on the variable-pitch rack body, and the automobile electric power-assisted variable steering gear ratio steering rack is characterized in that the tooth spaces of the meshing teeth are distributed in a sparse, dense and sparse mode and comprises a middle small transmission ratio section (a), transition sections (b) symmetrically arranged at two sides of the small transmission ratio section (a) and large transmission ratio sections (c) symmetrically arranged at the outer side of the transition sections (b);

the tooth pressure angle of the meshing teeth of the small transmission ratio section (a) is 19-21 degrees;

the tooth pressure angle of the meshing teeth of the large transmission ratio section (c) is 31-33 degrees;

the tooth pressure angle of the meshing teeth of the transition section (b) is smoothly transited in the range of a large tooth pressure angle and a small tooth pressure angle.

2. An automotive electric power assisted variable steering gear ratio steering rack according to claim 1, characterized in that the tooth pressure angle of the meshing teeth of the small gear ratio section (a) is 20 °.

3. An automotive electrically assisted variable steering gear ratio steering rack according to claim 1, characterized in that the tooth pressure angle of the meshing teeth of the high ratio segment (c) is 32.487 °.

4. The automotive electric power-assisted variable steering gear ratio steering rack according to claim 1, characterized in that the transmission ratio of the small transmission ratio section (a) is a fixed value, and the transmission ratio is 56-58;

the transmission ratio of the large transmission ratio section (c) is a fixed value, and the transmission ratio is 63-65;

the transmission ratio of the transition section (b) is changed from the small transmission ratio section (a) to the large transmission ratio section (c) according to a sine law.

5. The electric power-assisted variable steering gear ratio steering rack for vehicle according to claim 4, wherein the small gear ratio section (a) has a rotation angle ± (0-60 °).

6. The electric power-assisted variable steering gear ratio steering rack for vehicle according to claim 4, wherein the transition section (b) has a rotation angle ± (60-210 °).

7. The electric power assisted variable steering gear ratio steering rack according to claim 4, characterized in that the large transmission ratio section (c) ranges from the rotation angle ± (210-500 °).

8. An automotive electrically assisted variable steering gear ratio steering rack according to claim 4, characterized in that the gear ratio of the small ratio section (a) is 57 and the gear ratio of the large ratio section (c) is 64.

9. An automotive electric-assisted variable steering gear ratio steering rack according to claim 1, characterized in that the meshing teeth are helical teeth.

10. The automotive electric-assisted variable steering gear ratio steering rack according to claim 1, characterized in that the meshing teeth are straight teeth.

Technical Field

The invention relates to automobile parts, in particular to an automobile electric power-assisted variable steering gear ratio (VGR) steering rack.

Background

An ideal steering gear ratio is provided to satisfy the automobile characteristics to be pursued, and a comfortable steering feeling can be obtained under various driving conditions. Only when different transmission ratios are provided for a steering system between large-angle steering and small-angle steering, optimal steering matched with the characteristics of the automobile can be realized. The VGR steering rack comprises a steering control variable transmission ratio (VGR) end and a driving power assisting end, and the driving rack is developed to be stable in driving at a high speed and sensitive in lane changing at a low speed, so that the driving rack has better controllability in parking.

Patent CN111267940A discloses an automotive electric power-assisted variable steering gear ratio steering rack, which comprises a variable-pitch rack and a gear, wherein the variable-pitch rack is engaged with each other, and a row of engaging teeth are arranged on the variable-pitch rack, and the engaging teeth comprise a small transmission ratio section, a large transmission ratio section and a transition section; the transition section is arranged between the large transmission ratio section and the small transmission ratio section, the included angle of the tooth sockets in the large transmission ratio section is 70-82 degrees, and the included angle of the tooth sockets in the small transmission ratio section is 35-45 degrees; the steering rack is suitable for engineering trucks such as forklifts and the like which often run at low speed and need frequent steering, therefore, a high transmission ratio section is arranged in the middle of the rack, which is beneficial to improving the steering sensitivity of the engineering truck when the engineering truck runs at normal low speed, however, the steering rack is not suitable for passenger vehicles such as cars, SUVs, MPVs and the like which are used at present and can be driven on different road conditions and different speeds such as highways and the like, The urban road and the rural lane are driven, and people at present have driving safety, driving convenience and driving pleasure.

In the development of an electric power-assisted variable steering gear ratio steering rack of an automobile, how to further improve the smoothness and reliability of a VGR steering system during lane changing in the high-speed driving process and how to perform the response timeliness of a larger angle during slow-speed driving still need further research.

Disclosure of Invention

The invention aims to solve the problems and provide a low-cost, reliable and stable electric power-assisted variable steering gear ratio steering rack for an automobile.

The purpose of the invention is realized by the following technical scheme:

the automotive electric power-assisted variable steering gear ratio steering rack comprises a variable-pitch rack body, wherein a row of meshing teeth are arranged on the variable-pitch rack body, and the tooth pitches of the meshing teeth are distributed in a sparse, dense and sparse mode, and the variable-pitch rack comprises a middle small transmission ratio section, transition sections symmetrically arranged at two sides of the small transmission ratio section, and large transmission ratio sections symmetrically arranged at the outer side of the transition sections;

the tooth pressure angle of the meshing teeth of the small transmission ratio section is 19-21 degrees;

the tooth pressure angle of the large transmission ratio section meshing teeth is 31-33 degrees;

the tooth pressure angle of the meshing teeth of the transition section is smoothly transited in the range of a large tooth pressure angle and a small tooth pressure angle.

According to the invention, by adjusting the tooth spacing of the variable-pitch rack, arranging in a sparse, dense and sparse mode and setting different tooth pressure angles, the transmission ratio of the gear coupled with the variable-pitch rack is changed in the meshing transmission process of the gear coupled with the variable-pitch rack.

Further, the tooth pressure angle of the small gear ratio step engaging teeth is 20 °.

Further, the tooth pressure angle of the large ratio stage meshing teeth is 32.487 °.

Further, the transmission ratio of the small transmission ratio section is a fixed value, and the size of the transmission ratio is 56-58;

the transmission ratio of the large transmission ratio section is a fixed value, and the transmission ratio is 63-65;

and the transmission ratio of the transition section is changed from a small transmission ratio section to a large transmission ratio section according to a sine law.

Furthermore, the range of the small transmission ratio section is +/- (0-60 degrees) of the rotation angle.

Furthermore, the range of the transition section is a rotating angle +/-plus or minus (60-210 degrees).

Furthermore, the range of the large transmission ratio section is +/- (210-500 degrees) of the rotation angle.

Further, the gear ratio of the small gear ratio section is 57, and the gear ratio of the large gear ratio section is 64.

Further, the meshing teeth are helical teeth.

Further, the meshing teeth are straight teeth.

The invention is arranged in a sparse, dense and sparse mode, is beneficial to keeping driving stability at high speed, and when normal straight line driving is kept, the micro correction angle of the steering wheel in the hand is not more than +/-60 degrees, and the transmission ratio of 57 is more in line with the driving habit, and the gear-rack transmission pair with large transmission ratio is designed to improve the lane change sensitivity under the premise of ensuring safety at low speed, so that the steering wheel has better controllability at parking.

Compared with the prior art, the invention has the following characteristics:

1) the rack can be suitable for the EPS steering system manufactured at present and has wider applicability;

2) the gear rack pair is prepared by adopting a friction welding process, so that the weight and the cost can be reduced;

3) the variable transmission ratio rack enables the individualized steering driving style of the vehicle to become possible, and realizes smoother and more reliable lane changing in the high-speed driving process and larger-angle response timeliness in the low-speed driving process.

Drawings

Fig. 1 is a schematic top view of a variable pitch rack according to the present invention.

FIG. 2 is a sectional view taken along line A-A of FIG. 1;

FIG. 3 is a schematic view of a portion of the high ratio section of the present invention;

FIG. 4 is a schematic view of a portion of the low ratio section of the present invention;

FIG. 5 is a gear ratio of steering rack to gear angle for an embodiment of the present invention;

FIG. 6 is data of tooth slots in an embodiment of the present invention;

fig. 7 is a schematic view of the rack and pinion engagement of the present invention.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

Referring to fig. 1 and 2, the automotive electric power-assisted variable steering gear ratio steering rack comprises a variable-pitch rack body 1, wherein a row of meshing teeth 2 are arranged on the variable-pitch rack body 1, and the tooth spaces of the meshing teeth 2 are distributed in a sparse, dense and sparse mode and comprise a middle small transmission ratio section a, transition sections b symmetrically arranged on two sides of the small transmission ratio section a and large transmission ratio sections c symmetrically arranged on the outer sides of the transition sections b, wherein the tooth pressure angle of the meshing teeth of the small transmission ratio section a is 19-21 degrees, the tooth pressure angle of the meshing teeth of the large transmission ratio section c is 31-33 degrees, and the tooth pressure angle of the meshing teeth of the transition sections b is in smooth transition within the range of the large tooth pressure angle and the small tooth pressure angle. By adjusting the tooth spacing of the variable-pitch rack and setting different tooth pressure angles, in the meshing transmission process of the gear 3 coupled with the variable-pitch rack on the variable-pitch rack, as shown in fig. 7, the transmission ratio between the variable-pitch rack and the variable-pitch rack is changed, the transmission ratio of the small transmission ratio section a is a fixed value, the transmission ratio is 56-58, the transmission ratio of the large transmission ratio section c is a fixed value, the transmission ratio is 63-65, and the transmission ratio of the transition section b is changed from the small transmission ratio section a to the large transmission ratio section c according to a sine law.

In the embodiment, as shown in fig. 4, the tooth pressure angle of the meshing teeth of the small transmission ratio section a is 20 °, as shown in fig. 3, the tooth pressure angle of the meshing teeth of the large transmission ratio section c is 32.487 °, as shown in fig. 5, the transmission ratio of the steering rack to the gear corner is shown, the range of the small transmission ratio section a is the corner ± 0-60 °, the range of the transition section b is the corner ± 60-210 °, the range of the large transmission ratio section c is the corner ± 210-500 °, the transmission ratio of the small transmission ratio section a is 57, and the transmission ratio of the large transmission ratio section c is 64.

In this embodiment, the total number of the meshing teeth 2 of the rack variable-pitch rack body 1 is 28, the two sides of the meshing teeth are symmetrically arranged, fig. 6 shows data of tooth grooves in a specific embodiment of the invention, the diameter of a measuring ball is 4mm, and the central distance between two balls in each adjacent tooth groove and the axial distance of the measuring ball rack refer to fig. 6.

The invention can ensure that the automobile keeps stable driving at high speed and has sensitive lane change at low speed through sparse, dense and sparse arrangement and the experiment of the process parameters, thereby having better controllability when parking. The lower gear ratio of the central portion of the rack ensures smooth steering action at the initial stage of the steering operation, while the higher gear ratio of the both ends of the rack ensures that a quick response can be obtained in the steering operation at a larger steering angle, making the operation of the limit steering angle easier.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.