An electronic brake pedal assembly

Abstract

The utility model discloses an electronic brake pedal assembly, including by the support base of plastic, pedal arm assembly, central shaft, central shaft's structure: including the step shaft that is constituted by main shaft body and axle neck, and the main shaft body is divided into rotary connection portion and interference fit portion in proper order from the outer end to axle neck, and rotary connection portion and axle neck are matched with the shaft hole clearance on the support base, and the interference fit portion is interference fit with the axle pipe of pedal arm assembly, and the outer end on main shaft body is equipped with the axle body stop piece, be equipped with pedal arm rotation angle position collector and tread feeling simulator on the support base, the utility model discloses can realize with the complete decoupling of car braking system, and the technical compatibility is strong, simultaneously, based on the bearing load characteristics of electronic brake pedal, has adopted the lightweight design scheme, can realize the remarkable weight reduction of pedal assembly product.

Description

Technical Field

[0001] This utility model belongs to the field of brake pedal assembly, and in particular an electronic brake pedal assembly. Background Technology

[0002] With the rapid development of new energy vehicles and autonomous driving technology, the limitations of traditional hydraulic braking systems in terms of response speed, control precision, and system integration are becoming increasingly apparent, leading to a gradual shift towards brake-by-wire systems. As a core component of brake-by-wire systems, electronic brake pedals meet the needs of electric vehicles for energy recovery and intelligent driving collaborative control, possessing significant technological advantages and promising application prospects.

[0003] Compared to traditional brake pedals, electronic brake pedals must possess two inherent functions: transmitting braking demand and providing braking feedback. Therefore, the core structure of an electronic brake pedal must include a position sensor for transmitting braking demand and a pedal simulator (also known as a damper) for providing braking feedback. However, in current technologies, the pedal feedback simulator for electronic brake pedals is still based on traditional hydraulic braking systems. The common practice is to connect a hydraulic circuit in parallel with the hydraulic braking system to provide pedal damping. With this approach, the electronic brake pedal and the braking system are not completely decoupled, significantly limiting the energy recovery efficiency of new energy vehicles. This solution also requires openings in the front compartment for hydraulic lines, leading to difficulties in optimizing vehicle noise, complex system structure, numerous parts, and high costs.

[0004] Furthermore, as automotive EHB (electrohydraulic braking) systems further evolve towards EMB (electromechanical braking) systems, existing electronic brake pedals are difficult to be compatible with EMB, have poor technical versatility, and are facing the risk of being upgraded and replaced. Utility Model Content

[0005] To address the aforementioned issues, this invention proposes an electronic brake pedal assembly that can achieve complete decoupling from the vehicle's braking system and boasts strong technical compatibility. Furthermore, based on the load-bearing characteristics of the electronic brake pedal, a lightweight design scheme is adopted, resulting in a significant weight reduction for the pedal assembly.

[0006] To solve the above-mentioned technical problems, the present invention provides an electronic brake pedal assembly, comprising a support base, a pedal arm assembly, a central shaft, a position acquisition device, and a pedal feel simulator. The central shaft is characterized by being made of plastic. The central shaft comprises a stepped shaft consisting of a main shaft body and a journal. The main shaft body is divided into a rotary connection portion and an interference fit portion from its outer end to the journal. The rotary connection portion and the journal are clearance-fitted with the shaft hole on the support base. The interference fit portion is interference-fitted with the shaft tube of the pedal arm assembly. A shaft body limiting component is provided on the outer end of the main shaft body. The position acquisition device is fixed to the support base and is used to acquire the rotation angle of the pedal arm assembly. The pedal feel simulator is fixed to the support base, and its damping end is connected to the pedal arm assembly.

[0007] Further defining the above technical solution, the interference fit of the central shaft is a strip-shaped rib, the rib is distributed in a circular pattern around the axis of the main shaft body, and the top surface of the rib is flush with the surface of the rotary connection; the inner wall of the shaft tube in the pedal arm assembly is provided with a rib groove, the rib groove is distributed in a circular pattern around the axis of the shaft tube.

[0008] Further defining the above technical solution, the structure of the position acquisition device includes a position sensor and a magnet. The position sensor is fixed on the support base, and the magnet is located inside the outer end of the journal. 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 15-10mm.

[0009] Further defining the above technical solution, the structure of the foot pedal feel simulator includes: an outer shell, a guide post inside the bottom of the outer shell, a third spring sleeved at the lower end of the guide post, a second pressure head slidably connected to the upper end of the guide shaft, a second spring inside the top end of the guide shaft, the top end of the second spring being confined within the cavity of the second pressure head, a central support cover slidably connected to the second pressure head, the central support cover being limited by an inner step of the outer shell, a first pressure head inside the open end of the outer shell, a first spring between the bottom of the first pressure head and the top end of the central support cover, a first pressure head limiting end cover on the outer shell, the central hole of the first pressure head limiting end cover being slidably connected to the upper end of the first pressure head, and a ball-head push rod at the upper end of the first pressure head; the outer shell is fixed to a support base, and the ball end of the ball-head push rod is connected to the pedal arm assembly.

[0010] Beneficial effects: 1) The electronic brake pedal assembly designed in this utility model can be completely decoupled from the braking system, and is suitable for EHB and EMB brake-by-wire systems, with strong technical compatibility; 2) This utility model applies a lightweight and integrated design method, which achieves a significant reduction in the weight of the entire brake pedal while meeting the performance requirements of the pedal, and also focuses on economic benefits, making the entire pedal assembly have a low cost; 3) The connection structure between the central shaft and the pedal arm designed in this utility model simplifies the component structure, and forms reliable limits and constraints through assembly relationships, which can effectively prevent the central shaft from coming off. Attached Figure Description

[0011] Figure 1 This is a structural diagram of the utility model.

[0012] Figure 2 yes Figure 1 An explosion diagram.

[0013] Figure 3 This is a diagram of the central axis structure.

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

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

[0016] Figure 6 This is a schematic diagram of the location acquisition unit assembly.

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

[0018] Figure 8 It's a simulation image of the feeling of being trampled.

[0019] Figure 9 It is a traditional brake pedal characteristic curve.

[0020] Figure 10 It is the characteristic curve of the foot-feeling simulator. Detailed Implementation

[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 acquisition device 4, and a pedal feel simulator 5.

[0022] The functional structure of the bracket base 1 mainly includes mounting bosses and holes for connecting the whole vehicle, central shaft mounting holes, position sensor mounting holes, and damper mounting cylindrical cavities. The material of the bracket base is selected as PP+GF or PA+GF, which is directly injection molded. Its main body adopts a hollow structure to reduce the application of materials. Reinforcing ribs are designed to strengthen weak areas to meet the mechanical performance requirements. The thickness of the reinforcing ribs is usually designed to be 1.5mm-3mm, and the thickness of the reinforcing ribs in various places 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, with a hollow structure and a complementary design of reinforcing ribs. Compared to traditional pedals, the pedal arm of an electronic brake pedal has no physical connection to the braking system and does not need to drive the electronic power-assisted pump or transmit braking force. Therefore, the pedal arm itself bears a relatively small load (only bearing the reaction force generated by the pedal simulator). The lightweight plastic pedal arm can meet the requirements of strength and rigidity without breaking.

[0024] like Figure 2 As shown, the pedal arm assembly 2 is a single injection-molded component consisting of the pedal plate 201, ball cage bracket 202, shaft tube 203, and other parts, along with the pedal arm 204. This improves the integration of the parts and saves on mold and assembly manufacturing costs. The plastic pedal plate itself has an anti-slip function, and the molding process can incorporate design elements to enhance the anti-slip function and improve aesthetics. This eliminates the need for the pedal sleeve component in existing brake pedal technologies, thereby reducing the manufacturing cost of electronic brake pedals.

[0025] like Figure 3 and Figure 4As shown, the structure of the central shaft 3 includes a stepped shaft composed of a main shaft body 301 and a journal 302. The main shaft body is divided into a rotary connection part 3010 and an interference fit part 3011 from the outer end to the journal. The rotary connection part and the journal are clearance-fitted with the shaft hole on the support base. The interference fit part is interference-fitted with the shaft tube of the pedal arm assembly. A shaft limiting member 303 is provided on the outer end of the main shaft body along the assembly direction, preventing it from dislodging along the positive assembly direction. The rotary connection part 3010 of the central shaft is cylindrical, and the interference fit part... The connecting part 3011 is a strip-shaped raised rib, which is distributed circumferentially around the axis of the main shaft. The top surface of the raised rib is flush with the surface of the rotary connection part. The interference connection part is similar to a spline shaft, which can also be understood as: multiple grooves are distributed circumferentially on the main shaft, and the cross-section of the interference connection part of the main shaft has an alternating convex and concave structure. The inner wall of the shaft tube 203 in the pedal arm assembly 2 is provided with a raised rib groove 205, which runs through the shaft tube axially and is distributed circumferentially around the axis of the shaft tube. The cross-section of the shaft tube has an alternating convex and concave structure. The central shaft body is injection molded from POM (polyoxymethylene resin) material with self-lubricating properties, which can ensure the smooth rotation of the central shaft in the side hole of the base.

[0026] Further explanation: such as Figure 4 and Figure 5As shown, during assembly, the central shaft adopts a stepped shaft design to ensure the assembly direction, thereby effectively preventing assembly errors. One shaft hole on the bracket base is rotatably connected to the swivel connection part of the central shaft, and the other shaft hole on the bracket base is rotatably connected to the journal of the central shaft. The swivel connection part and the journal are adapted to the diameter of their respective connected shaft holes. After assembly, because the pedal arm and the central shaft form an integrated assembly with an interference fit, and the pedal arm shaft tube is limited by the two side walls containing the shaft holes on the bracket base, the axial position of the pedal arm on the central shaft is also completely constrained. In this way, the pedal arm and the central shaft form a stable connection part. When a pedaling force is applied to the pedal arm, the integrated part formed by the two can rotate together through the rotating pair formed by the central shaft and the pedal bracket. Even when the pedal arm is subjected to axial force, the central shaft will not disengage in the opposite direction of assembly. Furthermore, during actual driving, the central shaft is not subjected to axial force, and therefore will not disengage. Disengagement only occurs when the central shaft is subjected to a large axial force in the opposite direction of assembly, disrupting the interference fit between the central shaft and the pedal arm. This usually happens when the electronic brake pedal needs to be disassembled for maintenance, where an axial force is intentionally applied. The rib structure on the central shaft and the rib groove structure within the pedal arm shaft tube form an interference fit, ensuring that the central shaft and pedal arm assembly do not experience radial relative movement when subjected to pedaling force. The assembly dimensions between the central shaft and the bracket base, and the pedal arm, should be strictly controlled to ensure a transition fit between the central shaft and the bracket base that allows for relative rotation, and a tight interference fit between the central shaft and the pedal arm shaft tube.

[0027] like Figure 6 and Figure 7As shown, the position acquisition device 4 is fixed on the bracket base and is used to acquire the rotation angle of the pedal arm assembly. The position acquisition device structure includes a position sensor 401 and a magnet 402. The position sensor is fixed on the bracket base, and the magnet is injection-molded and enveloped by the central shaft body. The magnet is located inside the outer end of the journal, and the position sensor generates a corresponding induced electrical signal through the magnet. The position sensor consists of a hardware circuit board 4010, a protective housing 4011, and a connector 4012. The hardware circuit board consists of peripheral circuitry and a sensing chip. The sensing chip is a Hall effect chip (HAR37), and a single Hall effect chip can provide dual-channel sensing signals for output, meeting the redundancy safety function requirements of the electronic brake pedal and saving circuit layout space. The vehicle ECU communicates with the hardware circuit board through the connector. The hardware circuit board is fixed inside the protective housing, which is mounted on the bracket base with screws. After the position sensor is assembled, the center point of its sensing chip should coincide with the center point of the magnet's central axis, the outer end face of the magnet should be parallel to the circuit board, and the distance between the magnet and the sensing chip should be maintained at 13mm. This ensures optimal sensing performance. When the pedal arm rotates under the force of being stepped on, the magnet rotates along with the central axis. This causes a change in the magnetic field around the sensor chip. Under the Hall effect, the sensor chip generates a corresponding induced electrical signal, which is then input to the brake control unit, thus effectively transmitting the driver's braking needs.

[0028] The characteristics of a traditional brake pedal during pedaling are as follows: Figure 9 The brake pedal characteristic curve shown is a non-linear relationship, and the essence of this characteristic is a qualitative measurement of the "pedaling feel". In order to make the pedaling feel of the electronic brake pedal as consistent as possible with that of the traditional brake pedal, this invention designs a pedaling feel simulator, which uses a three-segment linear characteristic curve to approximate the non-linear characteristics of the traditional brake pedal, thereby achieving a better braking feel.

[0029] The structure of the foot pedal feel simulator 5 includes: an outer shell 501, a guide post 502 with a coaxial axis inside the bottom of the outer shell, a third spring 503 sleeved at the lower end of the guide post, a second pressure head 504 slidably connected to the upper end of the guide shaft, a second spring 505 inside the top end of the guide shaft, the top end of the second spring being limited within the cavity of the second pressure head, a middle support cover 506 slidably connected to the second pressure head, the middle support cover being limited by the inner step of the outer shell, a first pressure head 507 inside the open end of the outer shell, a first spring 508 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 on the outer shell, the center hole of the first pressure head limiting end cover being slidably connected to the upper end of the first pressure head, the first pressure head limiting end cover being fixedly connected to the outer shell by fasteners, and a ball head push rod 510 with a coaxial axis at the upper end of the first pressure head; the outer shell is fixed to the support base, and the ball head end of the ball head push rod is connected to the ball cage in the ball cage bracket of the pedal arm assembly. Further explanation: A boss is designed below the first pressure head. One end of the first spring rests on the bottom of the first pressure head, and the other end rests on the top of the middle support cover. An annular protrusion is designed on the top of the middle support cover to limit the first spring, and a through hole is designed to expose the upper part of the second pressure head. The lower part of the middle support cover rests on the diameter change 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. 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 rests on the inner side of the upper part of the second pressure head, and the lower part of the second spring rests in the groove at the top of the guide post inside the outer shell. In 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 post of the outer shell limits the second spring and the third spring respectively.

[0030] The working principle of the pedal feel simulator is as follows: When the pedal arm is subjected to pedaling force, the combination of the ball joint push rod and the first pressure head will move downward, compressing the first spring and generating pedaling damping. When the boss structure below the first pressure head contacts the upper part of the second pressure head, if pedaling continues, the second pressure head will move downward, compressing both the first and second springs simultaneously, generating greater damping. When the second pressure head moves downward to its lower part contacting the top of the third spring, if pedaling continues, it will not only continue to compress the first and second springs but also the third spring, thus causing the pedal feel simulator to generate even greater damping. During this process, when the first spring is compressed to its limit or the first pressure head contacts the intermediate support cover, the pedal feel simulator reaches its travel limit.

[0031] Based on the above working process, the characteristic curve of the foot-feeling simulator will be based on... Figure 10The output is shown as a characteristic curve of the pedal simulator. In the figure, segment 0A corresponds to the working stage where only the first spring is compressed; segment AB corresponds to the working stage where the first and second springs are compressed simultaneously; and segment BC corresponds to the working stage where the first, second, and third springs are compressed simultaneously. With reasonable design of parameters such as spring stiffness coefficient, spacing between internal parts of the simulator, and part dimensions, it can generate three linear characteristic curves to approximate the nonlinear characteristics of a traditional brake pedal, providing a braking feel that meets ergonomic requirements and resulting in a better driving experience.

Claims

1. An electronic brake pedal assembly, comprising a bracket base, a pedal arm assembly, a central shaft, a position acquisition unit, and a pedal feel simulator, characterized in that: The support base, pedal arm assembly, and central shaft are all made of plastic. The central shaft has the following structure: it 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 fit part from the outer end to the journal. The rotary connection part and the journal are clearance-fitted with the shaft hole on the support base. The interference fit part is interference-fitted with the shaft tube of the pedal arm assembly. A shaft body limiting component is provided on the outer end of the main shaft body. The position acquisition device is fixed on the support base and is used to acquire the rotation angle of the pedal arm assembly. The pedal feel simulator is fixed on the support base and the damping end of the pedal 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 of the central shaft is a strip-shaped rib, which is distributed in a circular pattern around the axis of the main shaft body. The top surface of the rib is flush with the surface of the rotary connection. The inner wall of the shaft tube in the pedal arm assembly is provided with a rib groove, which is distributed in a circular pattern around the axis of the shaft tube.

3. An electronic brake pedal assembly according to claim 1 or 2, characterized in that: The position acquisition device has the following structure: it includes a position sensor and a magnet. The position sensor is fixed on the support base, and the magnet is located inside the outer end of the journal. 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 15-10mm.

4. The electronic brake pedal assembly according to claim 3, characterized in that: The structure of the pedal feel simulator includes: an outer shell, a guide post at the bottom of the outer shell, a third spring at the lower end of the guide post, a second pressure head slidably connected to the upper end of the guide shaft, a second spring at the top of the guide shaft, the top of the second spring being confined within the cavity of the second pressure head, a central support cover slidably connected to the second pressure head, the central support cover being limited by an inner step of the outer shell, a first pressure head at the open end of the outer shell, a first spring between the bottom of the first pressure head and the top of the central support cover, a first pressure head limiting end cover on the outer shell, the central hole of the first pressure head limiting end cover being slidably connected to the upper end of the first pressure head, and a ball-head push rod at the upper end of the first pressure head; the outer shell is fixed to a support base, and the ball end of the ball-head push rod is connected to the pedal arm assembly.

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