Hydrostatic Drive Clutch Control for Low-Noise Motor Switching
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Solution Overview
Problem
Existing hydrostatic travel drives for mobile work machines face inefficiencies in switching between hydraulic motors, leading to unnecessary torque synchronization at high speeds and audible noise, as previous strategies fail to ensure switching only occurs when necessary and at the lowest possible speeds.
Innovation Solution
A method for controlling a hydrostatic travel drive that involves detecting braking or reversing states, comparing braking performance with a limit value, and adjusting the clutch to connect or disconnect the second hydraulic machine based on driving speed and torque conditions, ensuring the second hydraulic machine is only engaged when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the second hydraulic motor is engaged at high speeds to increase tractive force, then the driving speed range is extended, but torque synchronization noise and audible noise increase significantly
Solution Approach 1:
The control method dynamically adjusts the engagement conditions of the second hydraulic motor based on multiple parameters including driving speed, tractive force requirements, and clutch state. By changing the operational parameters and engagement thresholds, the system avoids engaging the second motor at high speeds where noise would be problematic, while still enabling extended speed range when conditions are appropriate.
Solution Approach 2:
The system continuously monitors the actual driving speed, tractive force requirements, and clutch engagement state to determine whether to engage or disengage the second hydraulic motor. This feedback mechanism ensures that the second motor is only engaged when necessary for achieving required tractive force, and only at speeds where noise is not problematic, thereby resolving the contradiction between speed range extension and noise reduction.
2Force
If the second hydraulic motor is engaged frequently to maintain tractive force, then the tractive effort capability is improved, but the switching losses and energy inefficiency increase
Solution Approach 1:
The control method optimizes the engagement parameters by considering not only tractive force requirements but also the current driving speed and clutch state. This parameter optimization reduces unnecessary switching events while maintaining adequate tractive effort capability, thereby minimizing switching losses and energy inefficiency.
Solution Approach 2:
The system uses feedback from multiple sensors to continuously evaluate whether engagement of the second hydraulic motor is truly necessary. By monitoring tractive force requirements, driving speed, and clutch state in real-time, the system avoids unnecessary engagement-disengagement cycles that would cause switching losses, while still ensuring adequate tractive effort is available when needed.
3Ease of operation
If the clutch is controlled based only on accelerator pedal-dependent switching speeds, then the control simplicity is maintained, but the switching occurs at inappropriate times and speeds
Solution Approach 1:
The control method extends the clutch control functionality by incorporating multiple input parameters beyond just accelerator pedal position. The control unit now considers driving speed, tractive force requirements, and clutch state alongside accelerator pedal position, creating a multi-functional control strategy that improves switching timing accuracy while maintaining reasonable control simplicity through integrated decision-making logic.
Solution Approach 2:
The system enhances the control strategy by incorporating feedback from multiple sources including driving speed sensors, tractive force requirements, and clutch state monitoring. This multi-parameter feedback mechanism ensures that switching decisions are made at appropriate times and speeds, improving reliability while the control unit integrates these multiple inputs into a unified control decision that maintains operational simplicity.
Data Source
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AI summary
The present invention relates to a method for controlling a hydrostatic drive (1) of a mobile working machine, wherein the hydrostatic drive is provided with a first hydraulic machine (4) with adjustable displacement volume and with a second hydraulic machine (6) and a third hydraulic machine (8), each with adjustable displacement volume, wherein the first hydraulic machine can be coupled or coupled to a drive machine, wherein the second hydraulic machine (6) can be rotatably connected to at least one driven wheel or chain or axle by means of a coupling (38), wherein the third hydraulic machine (8) is rotatably connected to the at least one driven wheel or chain or axle, wherein the coupling (38) is controlled taking into account a travel speed of the mobile working machine, or a quantity that depends on it, wherein the method comprises the following steps: a.a. Detecting a braking state B or a reversing state R and that the clutch is open; b. Detecting a braking power of the hydrostatic drive (1); c. Comparing the braking power with a limit value; d. Requesting the clutch to close if the braking power is greater than the limit value.