Trailer Brake Control Using Hydrostatic PUSH Detection
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Solution Overview
Problem
Existing trailer braking systems struggle to accurately detect jack-knifing conditions, particularly in agricultural vehicles, due to complexities in torque measurement and reliance on engine speed differences which are influenced by secondary drives, leading to inadequate response times and safety concerns.
Innovation Solution
A trailer braking system utilizing a continuously variable hydrostatic transmission with a first pressure sensor and a rotation sensor to determine fluid pressure and rotational direction, coupled with an electronic control unit to identify PUSH conditions, and optionally a redundant system with additional sensors for enhanced safety and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If engine speed difference is used to detect PUSH condition, then detection can be implemented, but detection accuracy deteriorates due to influence from secondary drives
Solution Approach 1:
The patent extracts the torque measurement function from the complex engine control system and places it directly at the transmission output where torque is naturally available. The torque sensor directly measures torque at the transmission output shaft, eliminating the need to infer torque from engine speed differences that are confounded by secondary drives like PTO and hydraulic pumps.
2Measurement precision
If direct torque measurement is implemented, then PUSH condition detection accuracy is improved, but device complexity and manufacturing effort increase
Solution Approach 1:
The transmission system itself provides the measurement function. The torque sensor leverages the existing transmission output shaft rotation and the naturally occurring torque reactions during PUSH/PULL conditions. The system uses its own operational characteristics (rotation direction changes during jack-knife) to enable accurate detection without requiring complex external measurement systems.
3Reliability
If two pressure sensors are used to detect PUSH condition, then detection reliability is improved, but device complexity increases
Solution Approach 1:
The single torque sensor performs multiple functions: it detects both PUSH and PULL conditions, determines jack-knife states, and provides torque magnitude information. The rotation sensor similarly serves dual purposes by detecting both rotation direction for PUSH/PULL identification and rotation speed for operational monitoring, eliminating the need for separate dedicated sensors for each function.
4Measurement precision
If complex torque measurement systems are used, then PUSH condition detection accuracy is improved, but response time deteriorates due to processing complexity
Solution Approach 1:
The patent replaces complex mechanical torque measurement systems with direct electrical sensing. The torque sensor provides direct electrical signals proportional to torque, and the rotation sensor provides direct electrical signals about rotation direction and speed. This substitution eliminates complex mechanical linkages and analog signal conditioning, enabling faster digital processing and quicker response to PUSH conditions.
Data Source
AI summary
A trailer braking system comprises a vehicles having a continuously-variable hydrostatic transmission, and a trailer coupled for towing by the vehicle and having an associated braking system operable from the vehicle. The vehicle transmission includes a first pressure sensor arranged to measure a fluid pressure at a predetermined point within the transmission, and a rotation sensor arranged to determine a rotation direction of a predetermined component in a driveline of the vehicle. A control unit coupled to the first pressure sensor and rotation sensor determines when a PUSH condition exists based on a particular combination of pressure and rotational direction, and operates the trailer brakes in response. One or more back-up systems to confirm the existence of a PUSH condition may be provided.