Tractor Drivetrain Clutch Torque Estimation Without Torque Sensors
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Solution Overview
Problem
Existing methods for determining torque in agricultural towing vehicles are complex and require expensive torque sensors, making them costly and technically cumbersome.
Innovation Solution
A method using two speed sensors to detect the speed difference across a clutch, which is compared to a predetermined limit value to determine the torque, allowing for clutch control via hydraulic or electrical means, and utilizing characteristic data to calculate the torque without the need for additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque sensors are used to determine torque, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical torque sensors with a control-based method that uses existing hydraulic control systems and readily available speed sensors. The torque is determined through control variables (hydraulic pressure, valve position) and speed measurements rather than direct mechanical sensing, eliminating the need for complex torque sensor installations.
Solution Approach 2:
The patent introduces control variables (hydraulic pressure, valve actuation position) as intermediaries to indirectly determine torque. Instead of directly measuring torque with sensors, the system measures these control variables and uses characteristic data to calculate torque, simplifying the measurement system while maintaining accuracy.
2Measurement precision
If torque sensors are used to determine torque, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent uses inexpensive speed sensors and existing hydraulic control components instead of expensive torque sensors. The method leverages already-present system components (hydraulic valves, speed sensors) to achieve torque determination, avoiding the need for costly specialized torque sensing equipment.
Solution Approach 2:
The patent replaces expensive mechanical torque sensors with a control-based calculation method using readily available components, significantly reducing system cost while maintaining measurement capability through indirect determination via control variables and speed measurements.
3Device complexity
If speed difference and control variables are used to determine torque, then device complexity is reduced, but measurement precision may be affected
Solution Approach 1:
The patent uses feedback from speed sensors and control variable measurements to continuously determine torque. The control variables (hydraulic pressure, valve position) and speed measurements provide feedback information that, when combined with characteristic data, enables accurate torque determination without complex additional hardware.
Solution Approach 2:
The patent changes the measurement parameters from direct torque sensing to measuring control variables (hydraulic pressure, valve actuation) and speed differences. By measuring these alternative parameters and using characteristic data relationships, the system achieves torque determination with simpler equipment while maintaining precision through the established relationships between these parameters.
Data Source
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AI summary
The invention relates to a method for determining a torque (M_g, M_va) acting at a position of a drive train (20) of an agricultural tractor (10), wherein a clutch (Ku_x, Ku_all) of the drive train (20) can be controlled between a closed and an open state. To determine the torque, the clutch (Ku_x, Ku_all) is controlled in the direction of the open state. During clutch control, a difference (Δn) between the rotational speeds (n1(x), n2(x); n1(all), n2(all)) detected on the input and output sides of the clutch (Ku_x, Ku_all) is determined. The difference (Δn) is compared with a predetermined difference limit value (Δn_lim). Depending on the comparison result, the value of a physical quantity (l_st, p_hy) that causes the clutch control is determined. Depending on the measured value of the physical quantity (l_st, p_hy), the torque (M_g, M_va) is determined.The invention further relates to a device (50) with a control unit (52) for carrying out such a method. The invention also relates to an agricultural tractor (10) comprising such a device (50).