Detailed Description
The technical scheme of the invention is further described below by the specific embodiments with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof.
As shown in fig. 1 to 3, an embodiment of the present application provides a power-assisted braking device, including: booster 1, reduction gears 2 and cam mechanism 3, reduction gears 2 are connected between booster 1 and cam mechanism 3.
The booster 1 is a power source of a booster braking device, the speed reducing mechanism 2 can achieve speed reduction and torque increase of the output torque of the booster 1, the cam mechanism 3 can achieve the purpose of converting the rotation motion of the speed reducing mechanism 2 into linear translation motion, so that the cam mechanism 3 pushes the piston of the brake master cylinder 5 (for example, the piston rod 51 is pushed to drive the piston to move), the hydraulic pressure of the brake master cylinder 5 can be transmitted and distributed to each brake of a vehicle, the effect of braking and speed reduction is achieved, and the booster braking purpose is achieved.
Wherein, as shown in fig. 4, the cam mechanism 3 comprises a cam 31 and a push rod 32 which is propped against the outline of the cam 31, the outline profile of the cam 31 comprises a base circle involute 311, and the base circle center O of the base circle involute 311 is coincident with the rotation center of the cam 31; the push rod 32 is offset with respect to the rotation center of the cam 31, and the offset distance L between the central axis of the push rod 32 and the rotation center of the cam 31 is equal to the radius R of the base circle 310 of the base circle involute 311, i.e., l=r.
In the cam mechanism 3, the push rod 32 abuts against the contour of the cam 31 (the push rod 32 and the contour of the cam 31 can be in direct contact or not in direct contact), the cam 31 can rotate under the drive of the speed reducing mechanism 2, the push rod 32 is pushed to translate, and the push rod 32 can push the piston of the brake master cylinder 5 to move, so that braking and speed reduction are realized.
The profile line of the cam 31 comprises a base circle involute 311, and the offset distance L between the central axis of the push rod 32 and the convex rotation center is equal to the radius R of the base circle 310, so that the displacement S of the push rod 32 and the rotation angle theta of the cam 31 are in a linear function relationship, namely S=R=θ, the linear control of the displacement of the push rod 32 is realized, the control difficulty is low, the displacement of the piston pushed by the power-assisted braking device is convenient to control, and further the output of braking power according to the treading depth of a brake pedal is facilitated.
In some exemplary embodiments, as shown in fig. 2a and 3, the profile line of the cam 31 further includes a first line segment 312, the first line segment 312 being tangent to the starting end of the base circle involute 311.
In the profile line of the cam 31, the first straight line segment 312 is tangent to the initial end of the base circle involute 311, so that the first straight line segment 312 is in smooth transition connection with the initial end of the base circle involute 311. The radius of curvature of the starting end a of the base circle involute 311 is zero, and a straight line where the first straight line segment 312 tangent to the starting end of the base circle involute 311 is located passes through the base circle center O of the base circle involute 311, as shown in fig. 2a, an end point of one end of the first straight line segment 312 is the starting end a of the base circle involute 311, and an end point of the other end of the first straight line segment may be the base circle center O. Of course, the end point of the other end of the first straight line segment 312 may not extend to the base circle center O, or may extend beyond the base circle center O.
In the initial state (i.e., when the brake pedal is not depressed), the push rod 32 may abut against the starting end of the base involute 311, and the first straight line segment 312 is smoothly connected with the starting end of the base involute 311, so that the push rod 32 may be stably maintained in the initial state.
In some exemplary embodiments, as shown in fig. 2a and 3, the profile line of the cam 31 further includes a second straight line segment 313 and a third straight line segment 314, where the first straight line segment 312, the second straight line segment 313 and the third straight line segment 314 are sequentially disposed and connected, a curved line is formed between the first straight line segment 312 and the second straight line segment 313, between the second straight line segment 313 and the third straight line segment 314, the third straight line segment 314 is connected with the tail end of the base circle involute 311, and a smooth transition is formed between the first straight line segment 312 and the second straight line segment 313, between the second straight line segment 313 and the third straight line segment 314, and between the third straight line segment 314 and the tail end of the base circle involute 311. The straight line where the third straight line segment 314 is located is tangent to the base circle of the base circle involute 311 (as shown by the dashed line in fig. 2 a), the third straight line segment 314 is a straight line segment BC, the tangent point between the straight line where the third straight line segment 314 is located and the base circle of the base circle involute 311 is D, the straight line segment BD is the generating line of the base circle involute 311, and the second straight line segment 313 is a straight line segment OC.
During the booster braking, the push rod 32 is brought into contact with the profile of the base circle involute 311 portion of the cam 31 and moved by the pushing of the profile of the base circle involute 311 portion. The first, second and third straight line segments 312, 313 and 314 of the cam 31 may not contact the push rod 32, and thus, the design of the profile lines of the portions of the first, second and third straight line segments 312, 313 and 314 may satisfy the requirement of reducing the weight without interference with other components while ensuring the strength of the cam 31, and thus, the profile lines of the cam 31 are not limited to the above except the base circle involute 311.
In some exemplary embodiments, as shown in FIG. 2a, the base circle involute 311 corresponds to an expansion angle θ 0 (i.e., the angle between the straight line segment OA and the straight line segment OD) is not smaller than the rotation angle S of the cam 31 0 R, i.e. theta 0 ≥S 0 R, wherein S 0 Indicating the maximum displacement of the push rod 32 or the maximum stroke of the push rod 32. Such as: expansion angle theta corresponding to base circle involute 311 0 180 degrees to 270 degrees.
In the profile line of the cam 31, the base circle involute 311 corresponds to the expansion angle θ 0 The movement distance of the piston of the brake master cylinder 5 pushed by the push rod 32 under the pushing of the profile of the base circle involute 311 can meet the braking requirement in the range of 180-270 degrees.
It should be appreciated that the base circle involute 311 corresponds to the spread angle θ 0 The cam mechanism is not limited to 180-270 degrees, and can be adjusted according to requirements, for example, under the condition of meeting the same displacement of the push rod, the expansion angle of the involute of the base circle is increased, the radius of the base circle can be correspondingly reduced, and the linear transmission ratio of the cam mechanism can be increased, namely, the input torque required by the cam mechanism can be reduced.
In some exemplary embodiments, as shown in fig. 1-4, the cam mechanism 3 further includes a roller 33 provided at one end of the push rod 32, the outer peripheral surface of the roller 33 being in contact with the profile of the cam 31, the roller 33 including a rolling bearing or a sliding bearing.
One end of the push rod 32 is provided with a roller 33, the roller 33 can rotate relative to the push rod 32, and the roller 33 is in rolling friction contact with the cam 31, so that friction loss is reduced, and transmission efficiency is improved.
The cam mechanism 3 in the embodiment of the application adopts a disc cam and roller push rod mechanism, and belongs to a plane cam mechanism 3. Among them, the roller 33 may employ a rolling bearing or a sliding bearing, for example, a ball bearing, a cylindrical roller 33 bearing, or a needle bearing (the friction loss of the ball bearing and the cylindrical roller 33 bearing is small compared with that of the needle bearing), or the like may be employed.
In some exemplary embodiments, as shown in fig. 1 to 3, the reduction mechanism 2 includes a gear reduction mechanism including an input gear 21, a double gear 22, and an output gear 23, the input gear 21 is mounted on the output shaft of the booster 1, a large gear 221 in the double gear 22 is meshed with the input gear 21, the number of teeth of the large gear 221 in the double gear 22 is larger than the number of teeth of the input gear 21, a small gear 222 in the double gear 22 is meshed with the output gear 23, the number of teeth of the small gear 222 in the double gear 22 is smaller than the number of teeth of the output gear 23, and the cam 31 is fixed on the output gear 23.
In the gear reduction mechanism, an input gear 21 is arranged on an output shaft of a booster 1, and the booster 1 can drive the input gear 21 to rotate when working; the double gear 22 comprises a large gear and a small gear, the number of teeth of the large gear 221 is larger than that of the small gear 222, the large gear 221 and the small gear 222 are fixedly connected, the central axes are coincident, the large gear 221 in the double gear 22 is meshed with the input gear 21 for transmission, the small gear 222 is meshed with the output gear 23 for rotation, the cam 31 is fixed on the output gear 23, and the rotation center of the cam 31 is coincident with the central axis of the output gear 23. Therefore, when the booster 1 drives the input gear 21 to rotate, the input gear 21 can drive the cam 31 to rotate through the duplex gear 22 and the output gear 23, and the cam 31 can push the push rod 32 to move, so that the piston of the brake master cylinder 5 is driven to move, and the booster braking is realized.
In some exemplary embodiments, as shown in fig. 1-3, the gear reduction mechanism includes two output gears 23, the two output gears 23 are in meshing transmission, and one of the output gears 23 is in meshing transmission with a pinion gear 222 in the duplex gear 22, and the number of teeth of the two output gears 23 is equal. Wherein the two output gears 23 are identical in shape and size and symmetrically arranged.
The cam mechanisms 3 are provided in two, and the cams 31 of the two cam mechanisms 3 are fixed to the two output gears 23, respectively. Wherein the two cam mechanisms 3 are identical in structure and size and symmetrically arranged.
The booster brake device further includes: the slide bar mechanism 4, the push rods 32 of the two cam mechanisms 3 are connected with the slide bar mechanism 4 and are arranged to drive the slide bar mechanism 4 to slide.
The double output gears 23+ and the double cam mechanism 3 gear are used for pushing the slide bar mechanism 4 to slide, so that the slide bar mechanism 4 slides stably, the slide bar mechanism 4 pushes the piston to move stably, and the power-assisted braking device is stable in braking and good in effect.
It should be understood that not only the double output gear 23+double cam mechanism 3 gear may be used, but also the single output gear 23+single cam mechanism 3 may be used to drive the slide bar mechanism 4 to slide, thereby pushing the piston to move by the slide bar mechanism 4.
In some exemplary embodiments, as shown in fig. 1-3, the slide bar mechanism 4 includes a sliding bracket 41, an output push bar 43, and a push bar support base 42, both ends of the sliding bracket 41 are respectively connected with the push bars 32 of the two cam mechanisms 3, the push bar support base 42 is mounted on the sliding bracket 41, the output push bar 43 is mounted on the push bar support base 42, and the free end of the output push bar 43 is configured to move the piston of the master cylinder 5.
In the slide bar mechanism 4, both ends of the slide bracket 41 are fixedly connected with the push rods 32 of the two cam mechanisms 3 respectively and move under the pushing of the two push rods 32; the output push rod 43 is arranged on the sliding bracket 41 through the push rod supporting seat 42, and the output push rod 43 moves under the driving of the sliding bracket 41 and drives the piston of the brake master cylinder 5 to move, so that the power-assisted braking is realized.
In some exemplary embodiments, the power-assisted braking apparatus further includes a housing (not shown) in which the booster 1, the gear reduction mechanism, the cam mechanism 3, and the slide bar mechanism 4 are mounted.
As shown in fig. 1-3, the slide bar mechanism 4 further includes two sliding sleeves 44, and the two sliding sleeves 44 are respectively mounted at two ends of the sliding bracket 41. Correspondingly, two guide rods are arranged in the shell, and two sliding sleeves 44 are respectively sleeved outside the two guide rods in a sliding manner.
The sliding sleeves 44 are installed at two ends of the sliding support 41, and the two sliding sleeves 44 are respectively sleeved on the two guide rods in the shell, so that the sliding sleeves 44 can move along the guide rods, guide is provided for the movement of the sliding support 41, and the sliding support 41 can move smoothly.
In some exemplary embodiments, the booster 1 is an electric booster and includes a motor.
In the booster braking device of the embodiment of the application, the booster 1 includes a motor, and the output shaft of the brake may be a motor shaft of the motor. The booster 1 adopts a motor, so that the booster braking device is an electric booster braking device, and the electric booster braking device is suitable for booster braking of a pure electric vehicle.
The power-assisted brake device shown in fig. 1 to 4 is constructed and operated as follows.
The input gear 21 is assembled on the output shaft of the motor (booster 1), the large gear 221 of the duplex gear 22 is meshed with the input gear 21, the small gear 222 of the duplex gear 22 is meshed with one output gear 23, the two output gears 23 are meshed with each other, the two cams 31 are fixedly connected with the two output gears 23 respectively, the rolling bearings (rollers 33) are assembled on the push rods 32, the push rods 32 are fixedly connected with the sliding brackets 41, the push rod supporting seat 42 is assembled on the sliding brackets 41, the output push rods 43 are assembled on the push rod supporting seat 42, the brake master cylinder 5 is fixedly connected with the shell of the booster brake device, the output push rods 43 are propped against the pistons of the brake master cylinder 5, the two sliding sleeves 44 are fixedly connected to the two ends of the sliding brackets 41 respectively, the rollers 33 and the push rods 32 are combined to form roller push rods, and the profile lines of the cams 31 comprise base circle involute 311.
In the power-assisted braking device, a motor is a power source of the power-assisted braking device, and a double gear 22 transmits the torque of an input gear 21 to an output gear 23 to play a role in reducing speed and increasing torque; the output gear 23 drives the cam 31 to rotate, the cam 31, the roller 33 and the push rod 32 form a cam mechanism 3, the function is to convert the rotation motion of the cam 31 into the linear translation motion of the push rod 32, the roller 33 converts the sliding contact between the push rod 32 and the cam 31 into rolling contact, and the friction loss is reduced; the two sets of cam mechanisms 3 transmit the action load and the translational motion to the sliding support 41; the sliding bracket 41 is used for transmitting the force of the push rod 32 to the push rod supporting seat 42 and linearly moving, and maintaining the linear output direction of the force; the sliding sleeve 44 is used for positioning and guiding the sliding bracket 41, reducing friction, and the sliding sleeve 44 is assembled on a guide rod of the shell to perform sliding and translational movement; the push rod supporting seat 42 is used for positioning the output push rod 43 and transmitting the acting force of the sliding support 41 to the output push rod 43; the output push rod 43 pushes the piston of the brake master cylinder 5 to move; the master cylinder 5 converts the pressure input from the piston into hydraulic pressure and outputs the hydraulic pressure.
When the power-assisted braking device works, the motor generates rotation and outputs torque according to an instruction sent by the control module, and the rotation speed and the torque output by the motor are reduced and increased through a gear reduction mechanism consisting of the input gear 21, the duplex gear 22 and the output gear 23, so that the output torque is amplified; the cam mechanism 3 consisting of the cam 31, the roller 33 and the push rod 32 converts the rotation motion of the output gear 23 into the linear translation motion of the push rod 32, and converts the torque of the output gear 23 into the linear force output of the push rod 32; finally, the piston of the brake master cylinder 5 is pushed by the sliding support 41 and the output push rod 32 to compress the hydraulic oil in the brake master cylinder 5, and hydraulic pressure is output, so that power-assisted braking is realized.
In the power-assisted braking device, disc cam 31 and roller push rod mechanism transmission is adopted to convert rotary motion into linear translational motion of push rod 32, friction loss is low, and transmission efficiency is high (the transmission efficiency can reach more than 0.9); the profile line of the cam 31 adopts a base circle involute 311, the roller push rod is arranged in a biased manner relative to the rotation center of the cam 31, the offset distance is the radius R of the base circle 310, the linear function change relation between the displacement S of the push rod 32 and the rotation angle theta of the cam 31 is realized, namely S=R×theta, the linear control of the displacement of the push rod 32 is realized, and the control difficulty is low; the motor is adopted to drive, and the gear reduction mechanism and the cam mechanism 3 are combined to realize the amplification of the power assistance of the motor.
The embodiment of the application also provides a vehicle, which comprises the power-assisted braking device provided by any embodiment. Wherein, this vehicle can be the pure electric vehicle.
Of course, the power-assisted braking device of the embodiment of the application can also be applied to a pure fuel vehicle, or the power-assisted braking device can also be applied to a hybrid vehicle.
In the description of the embodiments of the present application, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the description of the present specification, a description of the terms "one embodiment," "some embodiments," "example embodiments," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
While the embodiments disclosed herein are described above, the descriptions are presented only to facilitate an understanding of the embodiments disclosed herein and are not intended to limit the scope of the present disclosure. Any person skilled in the art may make any modifications and variations in form and detail of the implementations without departing from the spirit and scope of the disclosure, but the scope of the claims herein shall be defined by the appended claims.