Dual-Stage Transmission Control for Smooth On-the-Move Gear Shifts
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Solution Overview
Problem
Existing transmission structures in work vehicles require auxiliary speed change operations to be performed when stopped, leading to inconvenient manipulation and reduced travel efficiency, and do not adequately prevent or reduce shift shocks during gear stage switching during travel.
Innovation Solution
A transmission structure with a main transmission unit and an auxiliary transmission unit that allows continuous speed changing and multi-stage gear shifting, utilizing a controller to manage clutch mechanisms and speed change devices to minimize shift shocks by controlling the engagement and disengagement of clutches during gear stage switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If auxiliary speed change operation is performed when the vehicle is stopped, then gear stage switching can be completed, but manipulation becomes troublesome and travel work efficiency is degraded
Solution Approach 1:
The controller performs preliminary speed adjustment of the HST before auxiliary transmission gear stage switching. Specifically, before the auxiliary transmission switches from low-speed stage to high-speed stage, the controller adjusts the HST output speed to match the speed that will result after the gear switch, thereby preventing speed drops and maintaining continuous travel work efficiency
2Ease of operation
If the forward/reverse switching mechanism is switched to neutral state for gear stage switching, then gear stage switching can be performed during travel, but speed change shock is not sufficiently prevented due to idle running state
Solution Approach 1:
The controller performs preliminary speed adjustment of the HST before auxiliary transmission gear stage switching. Specifically, before the auxiliary transmission switches from low-speed stage to high-speed stage, the controller adjusts the HST output speed to match the speed that will result after the gear switch, thereby preventing speed drops and maintaining continuous travel work efficiency
Solution Approach 2:
The controller continuously monitors the actual vehicle speed and compares it with the target speed. Based on this feedback, the controller dynamically adjusts the HST output speed to compensate for speed changes during gear stage switching, ensuring smooth transitions without shock
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 structure effectively prevents or reduces shift shocks during gear stage switching, enabling smooth gear transitions during vehicle travel and maintaining efficient operation.
Implementation Method 1
a planetary gear mechanism combining the reference rotary power and the transmission rotary power, and outputs combined output of the planetary gear mechanism as travel rotary power
Implementation Method 2
low-speed stage and high-speed stage clutch mechanisms that respectively engage/disengage the low-speed stage and high-speed stage transmission paths
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
[Problem] To provide a transmission structure that includes a main transmission unit performing continuous speed changing and an auxiliary transmission unit performing multi-stage gear shifting and that can prevent a shock at the time of switching a gear stage of the auxiliary transmission unit during travel as much as possible. [Solution] In the present invention, the controller is configured as follows. When a gear stage switching manipulation is performed by an auxiliary speed change manipulation member during the travel, the controller disengages a pre-switching engagement clutch mechanism in the auxiliary transmission unit to realize an idle running state, operates a speed change output device during the idle running state by setting, as a target, a vehicle speed that corresponds to an actual vehicle speed in a case where an engagement state of a post-switching engagement clutch mechanism is set as a reference, thereafter engages the post-switching engagement clutch mechanism, and controls the operation of the speed change output device by setting, as a target vehicle speed, a vehicle speed that is defined by a manipulation position of a main speed change manipulation member.