PTO Mode Shifting via Torque Perturbation
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Solution Overview
Problem
Driveline PTO transmissions face challenges with torque locking and gear grinding during mode shifts due to windage-generated torque, which complicates the process of switching between road and pump modes, especially when excessive torque is present, leading to mechanical complications and potential damage.
Innovation Solution
The system employs a controller to modulate the transmission between multiple neutral states, creating a calculated train of torque pulses to build and release internal inertial forces, allowing the shift collar to move freely and overcome friction, and uses additional clutches to brake the transmission output when shifting from pump to road mode to prevent gear grinding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the transmission is modulated between multiple neutral states to create torque pulses, then the shift collar can move freely without torque locking, but the control system complexity increases
Solution Approach 1:
The transmission is modulated between multiple neutral states in a periodic sequence to generate a train of torque pulses. This periodic modulation creates oscillating inertial forces that overcome the static friction and windage torque locking the shift collar, enabling smooth mode transitions without requiring excessive force.
Solution Approach 2:
The system dynamically changes the transmission's neutral state parameters (clutch engagement patterns, brake application sequences) to generate controlled torque pulses. By varying the timing and magnitude of these parameter changes, the system creates optimal inertial forces for collar movement while managing control complexity through programmed sequences.
2Reliability
If additional clutches are used to brake the transmission output during mode shifts, then gear grinding is prevented, but the device complexity and cost increase
Solution Approach 1:
Additional clutches are engaged in advance of the mode shift to apply braking force to the transmission output shaft. This preliminary anti-action counteracts the windage torque that would otherwise cause the pump to rotate during the shift, preventing the collar from being forced against stationary drive shaft components and eliminating gear grinding.
Solution Approach 2:
The additional clutches act as intermediary elements between the transmission output and the mode shift mechanism. These clutches provide controlled braking action that mediates the interaction between the rotating pump and the shifting collar, allowing the collar to move freely without dragging against stationary components.
3Adaptability or versatility
If the sliding collar is used to shift between road mode and pump mode, then the PTO can selectively direct power, but torque locking occurs when excessive torque is present
Solution Approach 1:
The system transitions from a static neutral state to a dynamic sequence of multiple neutral states. By modulating between different neutral configurations with varying inertial characteristics, the system creates time-varying torque pulses that dynamically overcome the torque locking force, enabling the sliding collar to shift smoothly even under high torque conditions.
Solution Approach 2:
The periodic modulation between multiple neutral states generates oscillating torque pulses that create mechanical vibration in the shift mechanism. This vibration superimposes on the steady-state torque, creating momentary windows where the instantaneous torque drops below the static friction threshold, allowing the collar to incrementally move through the shift range.
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 enables smooth and efficient mode shifts without torque locking, reducing mechanical stress and the risk of gear damage, allowing for seamless transitions between road and pump modes, thereby enhancing the longevity and ease of operation of machines equipped with driveline PTO systems.
Implementation Method 1
creating a calculated train of torque pulses to build and release internal inertial forces, allowing the shift collar to move freely
Implementation Method 2
uses additional clutches to brake the transmission output when shifting from pump to road mode to prevent gear grinding
Data Source
AI summary
A method of controlling a machine drive having a driveline PTO establishes a driveline torque perturbation via conversion of internal inertia through two transmission neutral conditions. In an example, when a request is received, e.g., from an operator, to shift the driveline PTO from a first mode to a second mode, the transmission is automatically modulated between its first neutral condition and its second neutral condition while the driveline PTO is shifted from the first mode to the second mode, thus minimizing torque lock and facilitating mode changes.