Call us: +86-137-2353-4866
The evolution of automotive braking technology from purely mechanical and hydraulic systems to advanced electronic controls has necessitated the integration of high-precision sensors. Force sensors are fundamental components in this advancement, providing the critical data required for modern safety and performance systems. They translate the driver’s mechanical input and the system’s hydraulic response into precise electrical signals for analysis and control by the vehicle’s electronic control unit (ECU).
This page details the function, mechanism, and benefits of integrating force sensing technology within automotive braking and hydraulic applications.
What is Defining the Role of Force Sensors in Braking Systems
In the context of automotive engineering, a force sensor within the braking system is a transducer that measures the physical force applied and converts it into a quantifiable electrical signal. These sensors are deployed at critical points to measure two primary parameters:
- Driver Input Force: Sensors integrated into the brake pedal assembly measure the precise amount of force the driver applies to the pedal. This measurement of “driver intent” is a primary input for various electronic control systems.
- Hydraulic Actuation Force (Pressure): Within the hydraulic lines and control units, pressure sensors (a type of force sensor measuring force over a specific area) monitor the hydraulic fluid pressure generated by the master cylinder and modulated by control units. This data reflects the actual braking force being applied at the wheels.
Our force sensors are engineered using technologies such as piezoresistive strain gauges and magnetoelastic materials to ensure high reliability and accuracy under the demanding conditions of automotive environments.
How System Integration and Mechanism of Action
The integration of force sensors is crucial for the closed-loop control required by modern braking systems. The mechanism follows a clear operational sequence:
- Brake-By-Wire: In next-generation brake-by-wire systems, the mechanical link is removed entirely. The pedal force sensor is the primary source of information for the BCU, which then actuates the brakes electronically or electro-hydraulically. This requires sensors with the highest levels of accuracy and functional safety (ASIL) compliance.
- Force Application: The driver depresses the brake pedal. A force sensor, often a load cell or a strain gauge-based sensor mounted on the pedal assembly, deforms minutely under the applied load.
- Signal Conversion: This mechanical deformation alters the electrical resistance of the sensor element. This change is converted into a precise voltage or digital signal (e.g., SENT protocol) that is directly proportional to the applied force.
- Data Transmission: The signal is transmitted to the vehicle’s central ECU or a dedicated Brake Control Unit (BCU).
- System Response & Modulation: The ECU processes this force data in conjunction with other inputs, such as wheel speed from ABS sensors. It then commands actuators within the hydraulic control unit to modulate the hydraulic pressure to each wheel. This enables functions like:
- Anti-lock Braking System (ABS): Preventing wheel lock-up during heavy braking by rapidly modulating brake pressure.
- Electronic Brakeforce Distribution (EBD): Optimizing the distribution of braking force between the front and rear axles based on vehicle load and dynamics.
- Electronic Stability Control (ESC): Applying individual brakes selectively to correct for understeer or oversteer.
Why The Engineering Benefits of Force Sensor Integration
The integration of force sensors into braking and hydraulic systems is not an incremental improvement but a foundational necessity for modern vehicle safety and performance. The primary engineering advantages include:
- System Diagnostics and Reliability: Continuous monitoring of pressure and force allows the ECU to detect anomalies in the braking system, such as fluid leaks or component wear, triggering diagnostic trouble codes and warning indicators to enhance long-term reliability.
- Enhanced Safety and Control: By providing real-time data on driver intent and system response, force sensors enable advanced driver-assistance systems (ADAS) like ABS and ESC to function with high precision. This leads to reduced stopping distances, improved vehicle stability during emergency maneuvers, and prevention of skids.
- Performance Optimization: Accurate force measurement allows for more nuanced and responsive braking. The system can differentiate between a gradual slowdown and a panic stop, adjusting brake feel and response accordingly. In performance vehicles, this allows for optimized trail braking and better cornering stability.
- Enabling Future Technologies: Force sensors are indispensable for the development of electro-mechanical and brake-by-wire systems. These systems reduce vehicle weight by eliminating heavy hydraulic components, improve fuel efficiency (especially in hybrid and electric vehicles through better regenerative braking integration), and allow for greater design flexibility in the vehicle cabin.
Display
FAQ
What is the typical measurement range for a brake pedal force sensor?
Brake pedal force sensors typically have a measurement range between 0 and 2.5 kN (kilonewtons). This range adequately covers the force exerted by a driver during normal and emergency braking scenarios. Our sensors are designed with overload protection to withstand forces exceeding this nominal range.
What type of output signal do your braking system sensors provide?
Our force sensors for braking applications can be configured to provide various output signals to meet different ECU requirements, including analog voltage (e.g., 0.5-4.5V), ratiometric signals, and digital outputs such as the Single Edge Nibble Transmission (SENT) protocol, which is common in automotive applications for its high resolution and error detection capabilities.
How do force sensors in braking systems comply with automotive safety standards?
Our components are designed and manufactured in adherence to stringent automotive standards. This includes developing sensors to be compliant with Automotive Safety Integrity Level (ASIL) ratings, such as ASIL-C, as defined by the ISO 26262 standard. This involves robust design, failure mode and effects analysis (FMEA), and rigorous testing for durability and reliability under extreme temperature and vibration conditions.
What is the difference between a force sensor and a pressure sensor in this application?
While related, they measure different aspects. A force sensor (e.g., a load cell on the brake pedal) measures the total load or force applied at a single point (measured in Newtons). A pressure sensor, typically installed in a hydraulic line, measures force distributed over a specific area (measured in Pascals or PSI). In braking systems, the pedal force sensor measures driver input, while pressure sensors measure the resulting hydraulic output.
Are force sensors used in Electronic Parking Brake (EPB) systems?
Yes, force and position sensors are integral to EPB systems. They are used to measure the clamping force applied by the brake caliper to ensure the vehicle is held securely. This allows for precise control over the application and release of the parking brake and enables features like automatic hill hold.