Hill Start Assistance Using Master Cylinder Pressure
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Solution Overview
Problem
Current hill start assistance methods for vehicles are sensitive to clutch aging and wear, and struggle with optimal brake release timing due to noise sensitivity in pitch angle sensors, leading to potential vehicle recoil and reduced operational safety during hill maneuvers.
Innovation Solution
A method utilizing an electronic braking system with a master cylinder pressure sensor to maintain brake pressure when the pedal is released, based on the last recorded pressure value, ensuring the vehicle remains stationary until take-off conditions are met, and using a hydraulic braking system for dynamic stability control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pitch angle sensor is used to detect slope changes, then hill start assistance can be activated, but the measurement is very sensitive to noise from passenger movements and has high response time
Solution Approach 1:
The patent extracts the hill start assistance function from dependence on pitch angle sensors by using brake pressure sensor data instead. The system determines slope conditions through master cylinder pressure variations during brake application, eliminating the noisy pitch sensor requirement while maintaining assistance functionality.
Solution Approach 2:
The patent introduces brake pressure as an intermediary parameter to indirectly measure slope conditions. Instead of directly measuring pitch angle with noisy sensors, the system uses the master cylinder pressure response as a mediator to infer slope information, achieving reliable detection without pitch sensors.
2Reliability
If brake release timing is delayed to prevent vehicle recoil, then hill start safety is improved, but the vehicle may experience untimely braking or extended hold duration
Solution Approach 1:
The patent applies preliminary action by pre-charging the brake system and maintaining optimal brake pressure before the actual start moment. The system prepares the brakes in advance at the recorded pressure value, ensuring immediate readiness when the start condition is met, thereby preventing both recoil and excessive hold duration.
Solution Approach 2:
The patent implements feedback by continuously monitoring master cylinder pressure and using this information to determine when to release the brakes. The system records the pressure value and uses it as a reference for optimal release timing, creating a closed-loop control that adapts to actual brake system conditions rather than using fixed timing.
3Ease of operation
If torque-based brake release control is used, then hill start assistance can be provided, but the method is sensitive to clutch aging and wear
Solution Approach 1:
The patent replaces the mechanical torque-based control system with a pressure-based electronic control system. Instead of measuring and responding to clutch torque (which degrades with wear), the system uses electronic sensors to monitor brake pressure and control release timing, substituting mechanical sensing with electronic measurement that is not affected by clutch condition.
Solution Approach 2:
The patent introduces brake pressure as an intermediary parameter that mediates between the driver's brake application and the hill start assistance function. This intermediary measurement is independent of clutch characteristics, allowing the system to provide consistent assistance regardless of clutch aging or wear conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures smooth hill starts without recoil, enhances operational safety, and is less sensitive to clutch aging and wear, providing a more reliable hill start assistance.
Implementation Method 1
the pressure on each caliper of the vehicle can be controlled
Implementation Method 2
maintains, for a determined period, the pressure on the stirrups according to a pressure setpoint equal to the value of the last recorded information
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a hill start assistance method for the user of a vehicle having a braking system and an electronic braking control, provided with at least one master cylinder pressure sensor, whereby the pressure on each caliper of the vehicle can be controlled. The inventive method comprises the following steps in which: (a) the torque transmitted by the clutch is estimated, (b) information corresponding to the value of the master cylinder pressure resulting from a user's actuation of the brake pedal is recorded, and (c) the information recorded corresponding to the value of the master cylinder pressure is updated when the user actuates the brake pedal again by pressing harder on the pedal or partially releasing same. The invention is characterised in that, when the user releases the brake pedal fully, the braking system maintains the pressure on the calipers for a pre-determined period of time, as a function of a pressure set value equal to the value of the last item of information recorded.