Electronic brake pedal assembly

Abstract

The invention discloses an electronic brake pedal assembly which comprises a support base made of plastic, a pedal arm assembly and a center shaft. The center shaft structurally comprises a step shaft composed of a main shaft body and a shaft neck, the main shaft body is sequentially divided into a rotary connecting part and an interference connecting part from the outer end to the shaft neck, the rotary connecting part and the shaft neck are in clearance fit with a shaft hole in the support base, and the interference connecting part is in interference fit with a shaft tube of the pedal arm assembly. A shaft body limiting piece is arranged at the outer end of the main shaft body; a pedal arm rotation angle position collector and a treading feeling simulator are arranged on the support base; complete decoupling with an automobile braking system can be achieved, and the technical compatibility is high; meanwhile, based on the load bearing characteristic of the electronic brake pedal, a lightweight design scheme is adopted, and the weight of a pedal assembly product can be obviously reduced.

Description

Technical Field

[0001] The invention belongs to the field of brake pedal assemblies, in particular to an electronic brake pedal assembly. Background Art

[0002] With the rapid development of new energy vehicles and autonomous driving technologies, the limitations of traditional hydraulic braking systems in terms of response speed, control accuracy, and system integration are becoming increasingly prominent, leading to a gradual shift towards brake-by-wire systems. As a core component of brake-by-wire systems, the electronic brake pedal meets the energy recovery and intelligent driving collaborative control requirements of electric vehicles, offering significant technical advantages and promising application prospects.

[0003] Compared to traditional brake pedals, electronic brake pedals must perform two inherent functions: signaling braking demand and providing brake feel. Therefore, the core structure of an electronic brake pedal must include a position sensor for signaling braking demand and a pedal simulator (also known as a damper) for providing brake feel. However, existing technical solutions still rely on traditional hydraulic brake systems for their pedal feel simulators. Typically, a hydraulic circuit is connected in parallel with the hydraulic brake system to provide pedal damping. This technical solution fails to fully decouple the electronic brake pedal from the braking system, significantly limiting the energy recovery efficiency of new energy vehicles. This solution also requires openings in the front compartment for the hydraulic lines, leading to difficulties in optimizing vehicle noise, complex system structure, numerous parts, and high costs.

[0004] In addition, as the automobile EHB (electronic hydraulic brake) system further develops into the EMB (electromechanical brake) system, the existing electronic brake pedal is also difficult to be compatible with EMB, has poor technical versatility, and is facing the risk of being upgraded and replaced. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes an electronic brake pedal assembly, which can achieve complete decoupling from the vehicle braking system and has strong technical compatibility. At the same time, based on the load-bearing characteristics of the electronic brake pedal, a lightweight design scheme is adopted, which can achieve significant weight reduction of the pedal assembly product.

[0006] In order to solve the above technical problems, the technical solution of the present invention is: an electronic brake pedal assembly, including a bracket base, a pedal arm assembly, a central shaft, a position collector and a pedaling feel simulator, characterized in that: the bracket base, the pedal arm assembly and the central shaft are all made of plastic; the structure of the central shaft: includes a stepped shaft composed of a main shaft body and a shaft neck, the main shaft body is divided into a rotary connection part and an interference connection part from the outer end to the shaft neck in sequence, the rotary connection part and the shaft neck are clearance-fitted with the shaft hole on the bracket base, the interference connection part and the shaft tube of the pedal arm assembly are interference-fitted, and a shaft body limiter is provided on the outer end of the main shaft body; the position collector is fixed on the bracket base, the position collector is used to collect the rotation angle of the pedal arm assembly, the pedaling feel simulator is fixed on the bracket base, and the damping end of the pedaling feel simulator is connected to the pedal arm assembly.

[0007] The above technical solution is further defined as follows: the interference fit connection portion of the central shaft is a strip-shaped convex rib, which is distributed in a circular pattern with the axis of the main shaft as the center, and the top surface of the convex rib is flush with the surface of the rotary connection portion; a convex rib groove is provided on the inner wall of the shaft tube in the pedal arm assembly, and the convex rib groove is distributed in a circular pattern with the axis of the shaft tube as the center.

[0008] The above technical solution is further defined as follows: the structure of the position collector includes a position sensor and a magnet, the position sensor is fixed on the bracket base, the magnet is located inside the outer end of the shaft neck, and the position sensor generates a corresponding induced electrical signal through the magnet; the distance between the sensing chip in the position sensor and the magnet is 15 to 10 mm.

[0009] The above technical solution is further limited. The structure of the pedaling feeling simulator includes: an outer shell, a guide column is provided in the bottom of the outer shell, a third spring is provided at the lower end of the guide column, a second pressure head is provided at the upper end of the guide shaft for sliding connection, a second spring is provided in the top end of the guide shaft, the top end of the second spring is limited in the cavity of the second pressure head, a middle support cover is provided on the second pressure head for sliding connection, the middle support cover is limited by the inner step of the outer shell, a first pressure head is provided in the open end of the outer shell, a first spring is provided between the bottom of the first pressure head and the top end of the middle support cover, a first pressure head limiting end cover is provided on the outer shell, the center hole of the first pressure head limiting end cover is slidably connected to the upper end of the first pressure head, and a ball push rod is provided at the upper end of the first pressure head; the outer shell is fixed on the bracket base, and the ball end of the ball push rod is connected to the pedal arm assembly.

[0010] Beneficial effects: 1) The electronic brake pedal assembly designed by the present invention can be completely decoupled from the braking system, is applicable to EHB and EMB wire control brake systems, and has strong technical compatibility; 2) The present invention applies a lightweight and integrated design method, which achieves a significant weight reduction of the entire brake pedal while meeting the pedal performance, while focusing on economic benefits, so that the entire pedal assembly has a lower cost; 3) The connection structure between the central shaft and the pedal arm designed by the present invention simplifies the parts structure, and forms reliable limits and constraints through assembly relationships, which can effectively prevent the central shaft from falling out. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural diagram of the present invention.

[0012] Figure 2 yes Figure 1 Explosion diagram.

[0013] Figure 3 It is a central axis structure diagram.

[0014] Figure 4 This is the structural diagram of the shaft tube.

[0015] Figure 5 This is a schematic diagram of the center shaft assembly.

[0016] Figure 6 This is a schematic diagram of the position collector assembly.

[0017] Figure 7 This is the structural diagram of the position sensor.

[0018] Figure 8 This is a diagram of a pedaling feeling simulator.

[0019] Figure 9 This is the traditional brake pedal characteristic curve.

[0020] Figure 10 It is the characteristic curve of the pedaling feeling simulator. DETAILED DESCRIPTION

[0021] like Figure 1 and Figure 2 As shown, an electronic brake pedal assembly includes a bracket base 1, a pedal arm assembly 2, a central shaft 3, a position collector 4 and a pedaling feeling simulator 5.

[0022] The functional structure of the bracket base 1 mainly includes the mounting boss and holes for connecting the whole vehicle, the center axis mounting hole, the position sensor mounting hole and the damper mounting cylindrical cavity; the material of the bracket base is selected from PP+GF or PA+GF, and is directly injection molded. The main body adopts a hollow structure to reduce the application of materials. The weak strength areas are strengthened by designing reinforcement ribs to meet the requirements of mechanical properties. The thickness of the reinforcement ribs is usually designed to be 1.5mm-3mm, and the thickness of the reinforcement ribs at each location is as equal as possible to reduce molding defects.

[0023] Similar to the bracket base, the pedal arm assembly 2 is also directly injection-molded using PP+GF or PA+GF. The main body features a hollow structure and complementary reinforcing ribs. Unlike traditional pedals, the pedal arm of the electronic brake pedal has no physical connection to the brake system and does not need to drive the electronic power pump or transmit braking force. Therefore, the pedal arm itself bears relatively little load (only the reaction force generated by the pedaling simulator). The lightweight plastic pedal arm meets the required strength and rigidity without the risk of breakage.

[0024] like Figure 2 As shown, the pedal arm assembly 2 is injection-molded together with the pedal plate 201, CVJ bracket 202, axle tube 203, and pedal arm 204 into a single component. This improves component integration and reduces mold and assembly costs. The plastic pedal plate itself provides an anti-slip function, and design enhancements can be incorporated during the injection molding process to enhance the anti-slip function and improve aesthetics. This eliminates the pedal cover component found in existing brake pedal solutions, reducing the manufacturing cost of the electronic brake pedal.

[0025] like Figure 3 and Figure 4As shown, the structure of the central shaft 3 comprises a stepped shaft consisting of a main shaft body 301 and a journal 302. The main shaft body is divided into a rotary connection portion 3010 and an interference connection portion 3011 from the outer end to the journal. The rotary connection portion and the journal are clearance-matched with the shaft hole on the bracket base. The interference connection portion is interference-fitted with the shaft tube of the pedal arm assembly. The central shaft is provided with a shaft body limiter 303 on the outer end of the main shaft body along the assembly direction, so that it cannot be dislodged along the positive assembly direction. The rotary connection portion 3010 of the central shaft is cylindrical, and the interference connection portion is a cylindrical body. The connection portion 3011 is a strip of ribs distributed circumferentially around the main shaft axis, with the top surface of the ribs flush with the surface of the rotary connection. The interference fit is similar to a splined shaft and can be understood as consisting of multiple grooves distributed circumferentially around the main shaft, with the cross-section of the main shaft interference fit exhibiting a convex-concave structure. The inner wall of the shaft tube 203 in the pedal arm assembly 2 is provided with rib grooves 205 extending axially through the shaft tube and distributed circumferentially around the shaft axis. The cross-section of the shaft tube exhibits a convex-concave structure. The center shaft body is injection molded from self-lubricating POM (polyoxymethylene) material to ensure smooth rotation of the center shaft within the side hole of the base.

[0026] Further explanation: If Figure 4 and Figure 5As shown, during assembly, the center shaft adopts a stepped shaft design to ensure the assembly direction, thereby achieving effective assembly error prevention. One of the axial holes on the bracket base is rotatably connected to the swivel connection of the center shaft, and the other axial hole on the bracket base is swivelly connected to the shaft neck of the center shaft. The swivel connection and the shaft neck are compatible with the aperture of the axial hole to which they are connected. After assembly, the pedal arm and the center shaft form an integrated assembly component with an interference fit, and the pedal arm shaft tube is limited by the two side walls containing the axial hole on the bracket base, so that the axial position of the pedal arm on the center shaft is also completely constrained. In this way, the pedal arm and the center shaft form a stable connection component. When the pedal force is applied to the pedal arm, the integrated component formed by the two can rotate together through the revolving pair formed by the center shaft and the pedal bracket. Even when the pedal arm is subjected to axial force, the center shaft will not dislodge in the direction opposite to assembly. Furthermore, during actual driving, the center shaft is not subject to axial force, much less any possibility of dislodging. The center shaft will only dislodge if, and only if, it is subjected to a significant axial force in the direction opposite to assembly, disrupting the interference fit between the center shaft and the pedal arm. This typically occurs when the electronic brake pedal requires disassembly and repair, requiring manual axial force. The ribs on the center shaft form an interference fit with the rib grooves within the pedal arm shaft tube, ensuring that the center shaft and pedal arm assembly do not experience radial relative movement when subjected to pedaling force. The assembly dimensions between the center shaft, the bracket base, and the pedal arm should be strictly controlled to ensure a transition fit that allows for relative rotation between the center shaft and the bracket base, while also creating a tight interference fit with the pedal arm shaft tube.

[0027] like Figure 6 and Figure 7As shown, the position collector 4 is fixed to the bracket base and is used to collect the rotation angle of the pedal arm assembly. The position collector structure includes a position sensor 401 and a magnet 402. The position sensor is fixed to the bracket base. The magnet is injection-molded around the central shaft body and located inside the outer end of the shaft neck. The position sensor generates a corresponding induced electrical signal through the magnet. The position sensor comprises a hardware circuit board 4010, a protective housing 4011, and a connector 4012. The hardware circuit board consists of peripheral circuits and a sensor chip. The sensor chip is a Hall effect chip HAR37. A single Hall effect chip can provide dual-path sensor signal outputs, meeting the redundant safety requirements of the electronic brake pedal and saving circuit layout space. The vehicle ECU communicates with the hardware circuit board via a connector. The hardware circuit board is fixed to the protective housing, which is screwed to the bracket base. When the position sensor is assembled, the center point of the sensor chip should coincide with the center point of the magnet's central axis, the outer end of the magnet should be parallel to the circuit board, and the distance between the magnet and the sensor chip should be maintained at 13 mm to ensure optimal sensing performance. When the pedal arm rotates due to the pedaling force, the magnet rotates along with the center axis, which will cause the magnetic field around the sensing chip to change. Under the action of the Hall effect, the sensing chip will generate a corresponding induced electrical signal and input it to the brake control unit, thereby effectively transmitting the driver's braking needs.

[0028] The characteristics of the traditional brake pedal during the pedaling process are as follows: Figure 9 The brake pedal characteristic curve shown is a nonlinear relationship, and its essence is a qualitative measure of "pedaling feel." To ensure that the pedaling feel of an electronic brake pedal is as consistent as possible with that of a traditional brake pedal, this paper has designed a pedaling feel simulator that uses a three-segment linear characteristic curve to approximate the nonlinear characteristics of a traditional brake pedal, achieving a superior braking feel.

[0029] The structure of the pedaling feeling simulator 5 includes an outer shell 501, a coaxial guide column 502 is provided in the bottom of the outer shell, a third spring 503 is sleeved on the lower end of the guide column, a second pressure head 504 is sleeved on the upper end of the guide shaft in a sliding connection, a second spring 505 is provided in the top end of the guide shaft, the top end of the second spring is limited in the cavity of the second pressure head, a middle support cover 506 is sleeved on the second pressure head in a sliding connection, and the middle support cover is limited by the inner step of the outer shell, a first pressure head 507 is provided in the open end of the outer shell, a first spring 508 is provided between the bottom of the first pressure head and the top end of the middle support cover, a first pressure head limiting end cover 509 is provided on the outer shell, the center hole of the first pressure head limiting end cover is slidably connected to the upper end of the first pressure head, the first Asia-Pacific limiting end cover is fixedly connected to the outer shell by fasteners, and a coaxial ball head push rod 510 is provided at the upper end of the first pressure head; the outer shell is fixed to the bracket base, and the ball head end of the ball head push rod is connected to the ball cage in the ball cage bracket in the pedal arm assembly. Further explanation: a boss is designed under the first pressure head, one end of the first spring is pressed under the first pressure head, and the other end of the first spring is pressed above the middle support cover; an annular protrusion structure is designed above the middle support cover for limiting the first spring, and a through-hole structure is designed for exposing the upper part of the second pressure head, and the lower part of the middle support cover is pressed against the diameter-changing structure of the outer shell (the inner step of the outer shell); the upper part of the second pressure head is exposed through the through-hole of the middle support cover, and a spring limiting structure is designed on the inner side of the upper part of the second pressure head, the upper part of the second spring is pressed against the inner side of the upper part of the second pressure head, and the lower part of the second spring is pressed against the groove at the top of the guide column inside the outer shell; at the initial position, due to the action of the second spring, the lower part of the second pressure head does not contact any component; the guide columns of the outer shell limit the second spring and the third spring respectively.

[0030] The pedaling feel simulator works as follows: When the pedal arm is subjected to a pedaling force, the ball push rod and first pressure head assembly moves downward, compressing the first spring and generating pedaling damping. When the boss structure below the first pressure head contacts the upper portion of the second pressure head, continued pedaling causes the second pressure head to move downward, compressing both the first and second springs, generating greater damping. When the second pressure head moves downward until its lower portion contacts the top of the third spring, continued pedaling compresses not only the first and second springs but also the third spring, further generating greater damping in the pedaling feel simulator. During this process, when the first spring is compressed to its limit or the first pressure head contacts the intermediate support cap, the pedaling feel simulator reaches its travel limit.

[0031] Based on the above working process, the characteristic curve of the pedaling feeling simulator will be Figure 10The pedaling simulator outputs the characteristic curve shown in the figure. In the figure, segment 0A corresponds to the operating stage where only the first spring is compressed; segment AB corresponds to the operating stage where the first and second springs are compressed simultaneously; and segment BC corresponds to the operating stage where the first, second, and third springs are compressed simultaneously. With appropriate design parameters such as the spring rate, internal component spacing, and component dimensions, the simulator can generate three straight-line characteristic curves to approximate the nonlinear characteristics of a traditional brake pedal, providing an ergonomic braking feel and a superior driving experience.

Claims

1. An electronic brake pedal assembly, comprising a bracket base, a pedal arm assembly, a central axis, a position collector, and a pedaling feeling simulator, characterized in that: The bracket base, pedal arm assembly and center shaft are all made of plastic; the structure of the center shaft includes a stepped shaft consisting of a main shaft body and a journal; the main shaft body is divided into a rotary connection part and an interference connection part from the outer end to the journal; the rotary connection part and the journal are clearance-matched with the shaft hole on the bracket base; the interference connection part is interference-fitted with the shaft tube of the pedal arm assembly; a shaft limiter is provided on the outer end of the main shaft body; the position collector is fixed on the bracket base, and the position collector is used to collect the rotation angle of the pedal arm assembly; the pedaling feel simulator is fixed on the bracket base, and the damping end of the pedaling feel simulator is connected to the pedal arm assembly.

2. The electronic brake pedal assembly according to claim 1, characterized in that: The interference fit connection portion of the central shaft is a strip-shaped convex rib, which is distributed in a circular pattern with the axis of the main shaft as the center, and the top surface of the convex rib is flush with the surface of the rotary connection portion; a convex rib groove is provided on the inner wall of the shaft tube in the pedal arm assembly, and the convex rib groove is distributed in a circular pattern with the axis of the shaft tube as the center.

3. The electronic brake pedal assembly according to claim 1 or 2, characterized in that: The structure of the position collector includes a position sensor and a magnet. The position sensor is fixed on the bracket base, and the magnet is located inside the outer end of the shaft neck. The position sensor generates a corresponding induced electrical signal through the magnet. The distance between the induction chip in the position sensor and the magnet is 15 to 10 mm.

4. The electronic brake pedal assembly according to claim 3, characterized in that: The structure of the pedaling feeling simulator includes an outer shell, a guide column is provided in the bottom of the outer shell, a third spring is provided at the lower end of the guide column, a second pressure head is provided at the upper end of the guide shaft in a sliding connection, a second spring is provided in the top end of the guide shaft, the top end of the second spring is limited in the cavity of the second pressure head, a middle support cover is provided on the second pressure head in a sliding connection, the middle support cover is limited by the inner step of the outer shell, a first pressure head is provided in the open end of the outer shell, a first spring is provided between the bottom of the first pressure head and the top end of the middle support cover, a first pressure head limiting end cover is provided on the outer shell, the center hole of the first pressure head limiting end cover is slidably connected to the upper end of the first pressure head, and a ball push rod is provided at the upper end of the first pressure head; the outer shell is fixed on the bracket base, and the ball end of the ball push rod is connected to the pedal arm assembly.

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