CN110615031A - Electric power steering gear - Google Patents

Abstract

The invention belongs to the technical field of electric formula racing cars, and discloses an electric power steering device, which includes a rack shaft, a gear and a motor. The ball nut matched with the rod part, the screw part and the ball nut are arranged inside the hollow motor shaft, the ball nut and the motor shaft transmit torque through the flat key, the rack part is provided with a rack that cooperates with the gear; the gear is provided with a gear Rotational speed sensor; a displacement sensor is provided on the steering gear housing, a positioning part for cooperating with the displacement sensor is provided on the rack shaft, and the signal output terminal of the gear rotational speed sensor and the signal output terminal of the displacement sensor are connected to the motor control module. The invention has a simple and compact structure and can be widely used in the field of electric formula racing cars.

Description

electric power steering

technical field

The invention belongs to the technical field of electric formula racing cars, and in particular relates to an electric power steering gear for college students' electric formula racing cars.

Background technique

Most of the steering gears of traditional student Formula Student racing cars do not have power assist systems, and are basically rack and pinion steering gears. In Formula Student racing, it is necessary to perform a series of figure-eight circles and high-speed obstacle avoidance, etc., which require the racer to perform multiple frequent steering operations. Since there is no power assist system, the racer needs to spend a lot of physical energy on the steering of the car, making it easier for the racer Feeling fatigue greatly affects subsequent project performance.

With the development of technology and the emergence of college students' electric formula competition, it is necessary to add some power steering mechanisms to improve the performance of the steering system of the racing car. Since the electric power steering system only needs electricity and not hydraulic pressure, compared with the hydraulic power steering system, many original parts are omitted, so the electric power steering system is convenient in layout and light in weight. And the event is an electric formula car, which can provide stable energy for the booster motor.

Contents of the invention

In order to save the physical exertion of racing drivers due to frequent steering manipulations in college students' electric formula competitions, thereby improving the performance of the competitions, the present invention overcomes the shortcomings of the prior art and provides an electric power steering for electric formula racing cars. The steering assist motor can be used to provide the auxiliary force required for steering, so as to achieve the effect of light steering and saving the physical strength of the racer.

In order to solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an electric power steering device, including a rack shaft, a gear and a motor, the rack shaft is provided with a screw part and a rack part, and the screw A ball nut that cooperates with the screw part is arranged on the outer circumference of the part. The screw part and the ball nut are arranged inside the hollow motor shaft. The ball nut and the motor shaft transmit torque through a flat key. There is a rack that cooperates with the gear; the gear is provided with a gear speed sensor; the steering gear housing is provided with a displacement sensor, and the rack shaft is provided with a positioning part for cooperating with the displacement sensor. The signal output terminal of the rotational speed sensor and the signal output terminal of the displacement sensor are connected to the motor control module, and the motor control module is used to turn on the motor power supply when the gear rotational speed sensor detects that the gear rotational speed is greater than the set value, and also uses It is used to control the rotation direction of the motor shaft according to the positive and negative conditions of the displacement detected by the displacement sensor.

The electric power steering device further includes a motor housing, the motor is arranged in the motor housing, and the two ends of the motor shaft are connected to the motor housing through bearings.

Both outer ends of the motor shaft are provided with shoulders for mounting bearings, and an oil deflecting ring is provided between the bearings and the shoulders of the motor shaft.

The electric power steering device also includes a gear housing and an end cover. Flanges are provided at both ends of the motor housing, and the flange at one end is connected to the end cover through uniformly distributed screws, and the flange at the other end is The flange is connected to the gear housing through uniformly distributed screws. The gear housing and the end cover close to the motor housing are provided with protrusions for pressing the bearings, and the end far away from the motor housing is provided with a The rack shaft support nut is provided with a through hole for the rack shaft to pass through inside the rack shaft support nut, and is provided with threads for connecting the gear housing or the end cover on the outside.

The motor is a three-phase brushless AC motor, the stator coils are three-phase double-star connection, the motor rotor is a permanent magnet type, and the motor coils are arranged outside the motor shaft.

The inside of the motor shaft is provided with a limit protrusion that matches one end of the ball nut, and the motor shaft is also provided with a compression nut that cooperates with the other end of the ball nut, and the compression nut is connected to the motor shaft through threads.

The positioning part is a cylindrical pin fixedly arranged on the rack shaft.

Both the rack portion and the gear are helical teeth.

The screw part is formed by processing a screw thread on the larger diameter part of the rack shaft.

Compared with the prior art, the present invention has the following beneficial effects:

1. Simple and compact structure: The present invention provides a power steering gear with a relatively simple structure and light weight. The power booster motor is concentric with the rack shaft, and the deceleration mechanism is located inside the steering power booster motor to connect the rack shaft, optimizing the space as much as possible. The structure and device are more compact; by setting a gear speed sensor and a displacement sensor, not only can the direction of power assist be controlled according to the movement of the rack shaft, but also misoperation caused by vibration can be avoided;

2. The steering is lighter and more flexible: in the college student formula competition, the turning radius is often relatively small, so the turning speed is relatively slow, and the steering resistance required for steering at low speed is relatively large, and the steering is relatively heavy. When equipped with electric power steering, it can provide a little steering force at low and medium speeds, so it is lighter and more flexible when turning than without power steering;

3. It can effectively save the physical strength of the racer: in the college student electric formula racing car, it is necessary to perform a series of 8-shaped circles and high-speed obstacle avoidance, etc., which require the racer to perform multiple frequent steering operations, so the racer is equipped with an electric booster motor when driving A better racing car can save more physical energy of the driver.

Description of drawings

Fig. 1 is a schematic structural diagram of an electric power steering gear provided by an embodiment of the present invention;

Fig. 2 is a schematic diagram of the internal structure of Fig. 1;

Fig. 3 is a partial structural schematic diagram of Fig. 2;

In the figure: 1-rack shaft, 2-positioning part, 3-displacement sensor, 4-motor housing, 5-motor coil, 6-oil deflector ring, 7-bearing, 8-rack support nut, 9-end Cover, 10-compression nut, 11-ordinary flat key, 12-ball nut, 13-motor shaft, 14-gear speed sensor, 15-gear shaft, 16-rack housing, 17-screw part, 18- Rack part, 19-limiting protrusion.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than All the embodiments; based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work all belong to the protection scope of the present invention.

As shown in FIGS. 1 to 3 , an embodiment of the present invention provides an electric power steering, including a rack shaft 1 , a gear 15 and a motor. The rack shaft 1 is provided with a screw part 17 and a rack part 18, and the outer circumference of the screw part 17 is provided with a ball nut 12 matched with the screw part 17, and the screw part 17 and the ball nut 12 Set inside the hollow motor shaft 13, the ball nut 12 and the motor shaft 13 transmit torque through the flat key 11, the rack portion 18 is provided with a rack that cooperates with the gear 15; the gear 15 is provided with There is a gear speed sensor 14; the steering gear housing is provided with a displacement sensor 3, the rack shaft 1 is provided with a positioning part 2 for cooperating with the displacement sensor 3, the signal output terminal of the gear speed sensor 14 and the displacement The signal output terminal of the sensor 3 is connected with the motor control module, and the motor control module is used to switch on the motor power supply when the gear speed sensor 14 detects that the gear speed is greater than the set value, and is also used to detect The positive and negative conditions of the displacement control the rotation direction of the motor shaft.

Specifically, as shown in Figures 1 and 2, an electric power steering gear provided by an embodiment of the present invention further includes a motor housing 4, a gear housing 16 and an end cover 9, and the motor is arranged in the motor housing Inside the body 4, and the two ends of the motor shaft 13 are connected with the motor housing 4 through the bearing 7. Both ends of the motor housing 4 are provided with flanges, the flange at one end is connected to the end cover 9 through uniformly distributed screws, and the flange at the other end is connected to the gear housing 16 through uniformly distributed screws. One end of the body 16 and the end cover 9 close to the motor housing 4 is provided with a protrusion for pressing the bearing 7, and the end far away from the motor housing 4 is provided with a rack shaft support nut 8, the rack The shaft support nut 8 is internally provided with a through hole for the rack shaft 1 to pass through, and externally provided with threads for connecting the gear housing 16 or the end cover 9 .

Specifically, as shown in FIG. 3 , both ends of the motor shaft 13 are provided with shoulders for mounting the bearing 7 , and an oil deflector ring 6 is arranged between the bearing 7 and the shoulder of the motor shaft 13 . The shoulder is formed by inward processing of the end of the motor shaft 13, and the shoulder can limit the other side of the bearing 7. In addition, the oil deflector ring 6 arranged between the shoulder and the bearing can seal the motor coil 5 The spaces at both ends prevent the grease on one side of the gear housing 16 and the grease on the deceleration portion formed between the ball nut 12 and the screw portion 17 from entering the motor coil.

Specifically, in this embodiment, the motor is a three-phase brushless AC motor, the stator coils are three-phase double-star connected, the motor rotor is a permanent magnet type, and the motor coils 5 are arranged outside the motor shaft 13 . This kind of motor is very convenient to change the direction of rotation, just switch between any two phases of the three-phase power supply to realize the rapid power steering operation. Therefore, the present invention can realize power assistance in different steering directions by simply controlling the forward and reverse rotation of the motor.

Specifically, as shown in FIG. 3 , the inside of the motor shaft 13 is provided with a limit protrusion 19 that cooperates with one end of the ball nut 12 , and the motor shaft 13 is also provided with a stop protrusion 19 that cooperates with the other end of the ball nut 12 . The compression nut 10 is connected with the motor shaft 13 through threads. The position limiting protrusion 19 and the compression nut 10 limit the ball nut from both ends, and fix it on the outer periphery of the screw part 17 to realize deceleration.

Specifically, as shown in FIG. 3 , the positioning portion 2 is a cylindrical pin fixedly arranged on the rack shaft 1 . Both the rack portion 18 and the gear 15 are helical teeth. The screw part 17 is formed by processing the larger diameter part on the rack shaft 2 .

The present invention provides an electric power steering gear. By processing the motor shaft 13 into a hollow structure, a reduction device formed by a ball nut and a screw part of the rack shaft is arranged inside, thereby ensuring that the motor shaft 13 and the rack shaft 1 The coaxiality reduces the error, and also makes the radial dimension of the steering gear not change greatly after the power-assisted motor is installed, making the structure more compact. In addition, the recirculating ball-type roller screw reduction device matched with the inner shell of the motor shaft 13 can reduce the rotation speed of the steering motor to obtain a larger torque, and convert the rotation of the motor into the linear motion of the rack shaft 1 . The extremely small steel balls roll and decelerate circularly in the extremely smooth raceway, and transmit the power to the rack shaft 1 for linear motion, thereby pushing the two steering wheels to swing left and right to drive the racing car to turn. And because the steel ball is extremely small and the guide groove is extremely smooth, the transmission noise is extremely small, there is no idle stroke in the reverse direction, no self-locking phenomenon, and the efficiency is high.

The working process of the present invention is as follows: when turning to needs, the steering device drives the gear shaft 16 to rotate, and the gear shaft drives the rack shaft to move in the axial direction through the gear, so that the vehicle is turned; the gear speed sensor 14 detects the gear on the gear shaft 15 With a certain range of speed, the motor control module turns on the main power switch of the power assist motor, and at the same time the displacement sensor 3 detects positive and negative changes in the displacement of the cylindrical pin 2, and the motor control module can judge the direction of motion of the rack shaft, thereby controlling the power of the power assist motor. For forward rotation or reverse rotation, the torque generated by the rotation of the power assist motor shaft 13 is transmitted to the ball nut 12 through the ordinary flat key 11, and then the roller screw of the reduction device converts the rotation of the power assist motor into linear motion, and reduces the speed, and finally transmits it to the screw nut 12. On the bar portion, that is, on the rack shaft 1, the rack shaft is axially displaced, thereby achieving a certain assist effect when turning. Considering that the ground may sometimes have a certain impact on the wheels, this impact may be transmitted through the steering mechanism, resulting in a small rotation of the steering gear. By setting the gear speed sensor 14, the motor is turned on when the gear speed reaches a certain value. Power supply, can avoid misoperation caused by vibration.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (9)

1. An electric power steering device, characterized in that it includes a rack shaft (1), a gear (15) and a motor, and the rack shaft (1) is provided with a screw part (17) and a rack part ( 18), the outer circumference of the screw part (17) is provided with a ball nut (12) that cooperates with the screw part (17), and the screw part (17) and the ball nut (12) are arranged on the hollow motor shaft (13) Inside, the ball nut (12) and the motor shaft (13) transmit torque through the flat key (11), and the rack part (18) is provided with a rack that cooperates with the gear (15); The gear (15) is provided with a gear rotation speed sensor (14); the steering gear housing is provided with a displacement sensor (3), and the rack shaft (1) is provided with a location for cooperating with the displacement sensor (3). part (2), the signal output terminal of the gear speed sensor (14) and the signal output terminal of the displacement sensor (3) are connected to the motor control module, and the motor control module is used for the gear speed sensor (14) When it is detected that the rotation speed of the gear is greater than the set value, the power supply of the motor is turned on, and it is also used to control the rotation direction of the motor shaft according to the positive or negative displacement detected by the displacement sensor (3). 2. The electric power steering according to claim 1, characterized in that it further comprises a motor housing (4), the motor is arranged in the motor housing (4), and the motor shaft (13) Both ends of the motor are connected with the motor housing (4) through bearings (7). 3. The electric power steering according to claim 2, characterized in that, both ends of the motor shaft (13) are provided with shoulders for mounting bearings (7), and the bearings (7) ) and the shoulder of the motor shaft (13) is provided with an oil deflector ring (6). 4. An electric power steering according to claim 2, characterized in that it further comprises a gear housing (16) and an end cover (9), and the two ends of the motor housing (4) are provided with flange, the flange at one end is connected to the end cover (9) through uniformly distributed screws, and the flange at the other end is connected to the gear housing (16) through uniformly distributed screws, and the gear housing (16) and the end cover (9) ) on the end close to the motor housing (4) is provided with a protrusion for pressing the bearing (7), and the end far away from the motor housing (4) is provided with a rack shaft support nut (8), so The rack shaft support nut (8) is internally provided with a through hole for the rack shaft (1) to pass through, and externally provided with threads for connecting the gear housing (16) or the end cover (9). 5. A kind of electric power steering according to claim 1, characterized in that, the motor is a three-phase brushless AC motor, the stator coils are three-phase double-star connection, the motor rotor is a permanent magnet type, and the motor coils ( 5) Set it outside the motor shaft (13). 6. The electric power steering device according to claim 1, characterized in that, the inside of the motor shaft (13) is provided with a limit protrusion (19) that fits with one end of the ball nut (12), and the motor A compression nut (10) cooperating with the other end of the ball nut (12) is also provided on the rotating shaft (13), and the compression nut (10) is connected with the motor shaft (13) through threads. 7. The electric power steering device according to claim 1, characterized in that, the positioning part (2) is a cylindrical pin fixedly arranged on the rack shaft (1). 8. The electric power steering device according to claim 1, characterized in that, both the rack portion (18) and the gear (15) are helical teeth. 9 . The electric power steering device according to claim 1 , characterized in that, the screw part ( 17 ) is formed by processing a screw thread on the larger diameter part of the rack shaft ( 2 ).