Hydraulic Pump Clutch Control for Low-Drag Work Machines
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Solution Overview
Problem
Existing drive systems for work machines fail to adequately reduce energy consumption during tow load operations, as they typically maintain a residual towing output of 2-3 kW even when hydraulic power is not required.
Innovation Solution
A drive system with a controllable coupling that separates the output shaft from the hydraulic pumps during tow load operations, allowing for reduced or zero towing output, and an automatic clutch control mechanism that reduces energy consumption by disconnecting the hydraulic pumps from the drive unit using sensor data or mechanical structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the rotational speed of the drive unit is reduced during operation with trailing load, then energy consumption is reduced, but a residual drag power of 2-3 kW remains
Solution Approach 1:
The patent extracts the hydraulic pump from the power transmission path by using a controllable coupling (clutch) to disconnect the output shaft from the hydraulic pump during trailing load operations. This separation removes the source of residual drag power (2-3 kW) that persists in conventional systems where the pump remains mechanically connected to the drive unit.
Solution Approach 2:
The patent implements dynamic control of the power transmission path by using a controllable coupling that can engage or disengage based on operational conditions. During trailing load, the coupling disconnects the hydraulic pump from the drive unit, dynamically adapting the system configuration to eliminate unnecessary energy loss.
2Loss of energy
If the hydraulic pump is disconnected from the drive unit during trailing load, then drag power is reduced to zero, but the hydraulic supply for controlling the clutch must be maintained
Solution Approach 1:
The patent employs a multi-functional hydraulic pump that serves dual purposes: during normal operation, it provides hydraulic power to the clutch control system, and during trailing load when disconnected, it can still supply hydraulic pressure to other consumers (brakes, steering, ventilation) through a switching valve. This universal design ensures the hydraulic supply system supports multiple functions without requiring separate systems.
Solution Approach 2:
The patent introduces a switching valve as an intermediary element that redirects hydraulic flow between different consumers. When the clutch is disconnected during trailing load, the switching valve reroutes the hydraulic supply from the clutch control circuit to other system consumers, maintaining system functionality without requiring the clutch to remain engaged.
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 significantly reduces energy consumption in work machines by minimizing towing output to zero when hydraulic energy is not needed, enhancing operational efficiency, especially in machines like hydraulic excavators.
Implementation Method 1
a hydraulic actuator can be provided which opens or closes the clutch
Implementation Method 2
a centrifugal clutch can be used, which opens or closes automatically depending on the rotational speed of the drive unit
Data Source
Figure 1~2
AI summary
The machine has a drive unit (1) e.g. diesel engine and electric motor, for driving hydraulic pumps (2) of a hydraulic system of the machine over a driven shaft (1'). A controllable clutch (3) i.e. centrifugal clutch, is designed such that the clutch separates the shaft from the pumps during a dragging-loading operation. The clutch is opened or closed by a hydraulic actuator (5) based on speed of the drive unit. The pumps are driven via a transfer gearbox (4), where the clutch is arranged between the shaft and the gearbox. The pumps supply pressure to steering elements, brakes and ventilators. An independent claim is also included for a method for operating a work machine.