Hydrostatic Travel Drive Monitoring for Unwanted Torque Detection
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Solution Overview
Problem
Existing electronic monitoring systems for hydrostatic travel drives in vehicles cannot reliably distinguish between unintentional movement due to active drive torque and movement caused by external forces, limiting their effectiveness, especially in dynamic vehicles like wheel loaders, and cannot detect faults outside the electronic control system.
Innovation Solution
The system incorporates a revolution rate sensor and at least one pressure sensor to detect motor and vehicle acceleration, and pressure signals from the hydrostatic pump's working lines, allowing for robust fault state detection, including external faults, and enabling 'Safe Direction' and 'Safe Reversing' functions by evaluating motor and vehicle states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only the revolution rate signal of the hydrostatic motor is used for monitoring, then the system structure remains simple, but the system cannot reliably distinguish between unintentional movement due to active drive torque and movement caused by external forces
Solution Approach 1:
The patent introduces a pressure sensor as an intermediary measurement device in the hydraulic working line. This pressure sensor detects pressure signals that serve as indicators of active drive torque generation, enabling the monitoring system to distinguish between movement caused by active drive torque and movement caused by external forces without directly measuring torque itself.
Solution Approach 2:
The monitoring system continuously compares the pressure signal from the pressure sensor with the standstill signal from the control element. When the control element indicates standstill but the pressure sensor detects significant pressure (indicating active drive torque), the system generates an error signal. This feedback mechanism enables reliable fault detection while maintaining system simplicity.
2Reliability
If monitoring is limited to the electronic control system, then the system remains simple, but faults outside the electronic control system cannot be detected
Solution Approach 1:
The patent places a pressure sensor directly in the hydraulic working line between the hydrostatic pump and hydrostatic motor. This physical intermediary position allows the sensor to detect pressure changes caused by mechanical faults in the hydraulic system itself, not just electronic control faults. The pressure signal serves as a direct indicator of active drive torque generation regardless of the source.
Solution Approach 2:
Instead of monitoring only electronic control signals, the patent uses a pressure sensor to directly monitor the mechanical/hydraulic state of the system. The pressure signal provides direct information about the physical state of the hydraulic circuit, enabling detection of mechanical faults that would not be apparent from electronic control signals alone.
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 solution enables reliable detection of fault states in challenging driving situations, such as rolling away on an incline, and detects faults outside the electronic control system, improving safety functions like 'Safe Standstill' and preventing unintentional vehicle movement.
Implementation Method 1
a revolution rate sensor for the direct or indirect detection of a motor revolution rate, from which according to the disclosure an acceleration of the motor and/or the vehicle can be detected
Implementation Method 2
at least a first pressure sensor, by means of which a first pressure signal of a first working line of the travel drive can be transmitted to the control unit
Data Source
AI summary
A monitoring system for a travel drive includes a rotational speed sensor of a hydrostatic motor. The rotational speed sensor is configured to determine acceleration. At least one signal from a pressure sensor mounted on at least one working line that connects a pump to the hydrostatic motor of a hydrostatic travel drive is evaluated. The pressure sensor is preferably arranged on at least one working connection of the pump. The system uses the additional pressure signal to evaluate in a reliable manner whether the hydrostatic travel drive generates an unwanted drive torque.