Hydraulic Riding Trowel Automatic Load Sensing System
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Solution Overview
Problem
Hydraulic riding trowels face challenges in maintaining optimal engine horsepower and preventing stalling due to varying concrete surface friction and torque requirements, leading to reduced performance and potential surface damage.
Innovation Solution
A hydraulic unloader valve system with feedback circuitry that dynamically controls rotor RPM and pump flow based on sensed pressures, ensuring the internal combustion engine operates within its optimal horsepower range and preventing stalling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydraulic riding trowel operates at high power to finish large areas quickly, then productivity increases, but engine horsepower is exceeded and stalling occurs
Solution Approach 1:
The patent implements a hydraulic feedback system using pressure sensors and unloader valves that continuously monitor system pressure and automatically adjust pump flow to maintain optimal engine horsepower. When pressure sensors detect conditions approaching engine horsepower limits, the unloader valves reduce pump flow accordingly, preventing engine stalling while maximizing productivity within safe operating parameters.
2Manufacturing precision
If pump flow is increased to maintain rotor RPM under high friction conditions, then surface finishing quality is maintained, but engine horsepower is exceeded
Solution Approach 1:
The patent employs dynamic flow control through pressure-activated unloader valves that automatically adjust pump output in real-time based on system pressure conditions. This dynamic adjustment maintains adequate rotor RPM for surface finishing quality while preventing excessive power demand that would exceed engine horsepower capabilities under varying friction conditions.
3Power
If unloader valve is activated to reduce pump flow and prevent engine overload, then engine horsepower is protected, but rotor RPM decreases
Solution Approach 1:
The feedback-controlled unloader system selectively activates only when pressure sensors detect conditions approaching engine horsepower limits. This selective activation protects engine horsepower during critical overload conditions while minimizing rotor RPM reduction during normal operation, thereby balancing engine protection with maintenance of surface finishing performance.
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
The system stabilizes engine horsepower, reduces rotor RPM during high torque conditions, and minimizes surface damage by adjusting pump output in response to changing load conditions, maintaining efficient operation and preventing engine stalling.
Implementation Method 1
A hydraulic feedback circuit responsive to sensed pressures facilitates automatic control
Implementation Method 2
A hydraulic unloader valve system with feedback circuitry that dynamically controls rotor RPM and pump flow based on sensed pressures
Data Source
AI summary
A high performance, multiple rotor, hydraulically driven riding trowel for finishing concrete includes a rigid trowel frame with two or more downwardly-projecting, bladed rotor assemblies that frictionally engage the concrete surface. The rotor assemblies are tilted with double acting hydraulic cylinders to effectuate steering and control. Double acting hydraulic cylinders also control blade pitch. Hydraulic pressure to the rotors is monitored and controlled by an unloader valve system that monitors drive pump pressure with a shuttle valve to derive an unloader pilot signal. A sequence valve responds to the unloader pilot signal to control a pressure valve that bypasses the normal foot control valve in an overpressure situation. The pressure control head signal normally applied to the hydraulic drive motor control heads is modified with a feedback signal to automatically control the associated pump swash plates.