Hydraulic Traction Control for Self-Propelled Construction Machines
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Solution Overview
Problem
Self-propelled construction machines face issues with insufficient traction, particularly on slippery surfaces, leading to slipping or spinning of drives, which reduces overall traction and affects the quality of work results, and existing solutions like hydraulic flow dividers are expensive and space-consuming.
Innovation Solution
A control system that adjusts the displacement volume of hydraulic motors to maintain constant partial volume flows, eliminating the need for hydraulic flow dividers, and accounts for steering angles and operating modes to optimize traction and cornering performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydraulic flow divider is used to maintain constant partial volume flows, then traction is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent replaces the mechanical hydraulic flow divider with an electronic control system that uses sensors to detect track speed and a control unit to calculate and adjust the volume flow distribution. This substitution of mechanical components with electronic control achieves the same traction control function while reducing device complexity and space requirements.
Solution Approach 2:
The control system automatically detects track slippage through speed sensors and autonomously adjusts the volume flow distribution without requiring manual intervention or complex mechanical flow division mechanisms. The system serves itself by using its own sensor data to make real-time control decisions.
2Reliability
If a hydraulic flow divider is used to maintain constant partial volume flows, then traction is improved, but space requirements increase
Solution Approach 1:
The patent replaces the space-consuming mechanical hydraulic flow divider with a compact electronic control system consisting of speed sensors, a control unit, and actuators. This electronic system achieves the same traction control function while occupying significantly less space in the construction machine.
Solution Approach 2:
The control system uses electronic signals and data processing to replicate the flow division function without requiring physical flow division components. The control unit calculates the desired volume flow distribution and sends control signals to actuators that adjust the hydraulic system, effectively copying the flow divider's function in the electronic domain.
3Reliability
If the total volume flow is distributed to multiple tracks, then overall traction is maintained, but individual track control is insufficient when slippage occurs
Solution Approach 1:
The patent implements a feedback control system where speed sensors continuously monitor the actual speed of each track, and this information is fed back to the control unit. The control unit compares the detected speeds with the desired speeds and automatically adjusts the volume flow distribution to correct slippage, providing both overall traction maintenance and individual track control.
Solution Approach 2:
The system dynamically adjusts the volume flow distribution to each track based on real-time operating conditions and detected slippage. The control unit continuously modifies the control signals to the actuators, enabling adaptive individual track control while maintaining overall traction across all tracks.
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
Significantly improves traction and work results by maintaining consistent partial volume flows, preventing backward movement on slopes, and ensuring smooth operation across the entire speed and steering range without the need for additional components, thus reducing costs and space requirements.
Implementation Method 1
at least one travel drive hydraulic pump (19) driven by a drive motor, in particular an internal combustion engine, for supplying the hydraulic motors (15, 16, 17, 18) with a volume flow of hydraulic fluid
Implementation Method 2
hydraulic motors (15, 16, 17, 18) assigned to the drivable undercarriages (10A, 10B, 11A, 11B), in particular adjustable hydraulic motors
Implementation Method 3
the product of the displacement Vg and the speed n of the hydraulic motor results in the volume flow Q, on which the travel speed v of the self-propelled construction machine depends
Implementation Method 4
when the speed (n) of an adjustable hydraulic motor increases as a result of slippage of the drive assigned to the adjustable hydraulic motor, the adjustment device of the adjustable hydraulic motor is controlled such that a displacement volume is set for the adjustable hydraulic motor at which the partial volume flow determined for the adjustable hydraulic motor is maintained or is established
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a self-propelled construction machine, in particular a road milling machine, stabilizer, recycler, or surface miner, comprising a machine frame 2 supported by at least three undercarriages 10A, 10B, 11A, 11B, a drive unit 14 for driving at least two undercarriages, and a work roller 4 arranged on the machine frame. The invention further relates to a method for controlling such a construction machine. The drive unit 14 comprises adjustable hydraulic motors 15, 16, 17, 18 associated with the driveable undercarriages, each with a displacement volume Vg that can be varied by means of an adjusting device 15A, 16A, 17A, 18A, and at least one adjustable drive hydraulic pump 19 driven by at least one drive motor for supplying the hydraulic motors with a variable total volume flow Q of hydraulic fluid.Furthermore, a control device 28 is provided, which is configured such that a partial volume flow Q1, Q2, Q3, Q4 is determined for each adjustable hydraulic motor 15, 16, 17, 18 from the total volume flow Q provided by the at least one drive hydraulic pump 19, with which the respective hydraulic motor is to be operated, and if the rotational speed n of an adjustable hydraulic motor increases due to slippage of the drive associated with the adjustable hydraulic motor, the adjustment device of the adjustable hydraulic motor is controlled such that a displacement volume Vg is set for the adjustable hydraulic motor at which the partial volume flow determined for the adjustable hydraulic motor is maintained. The self-propelled construction machine according to the invention is characterized in that a hydraulic flow divider is not required.