Vehicle Transmission Path Switching for Hydraulic Loss Reduction
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Solution Overview
Problem
Existing power transmission systems in wheel loaders face inefficiencies due to hydraulic power distribution during low and high-speed operations, particularly in vehicles with hydraulic mechanical continuously variable transmissions, leading to reduced transmission efficiency compared to torque converter vehicles with lockup mechanisms.
Innovation Solution
A power transmission device for vehicles, incorporating a planetary continuously variable transmission mechanism, a direct connecting mechanism, and a communication valve to stabilize clutch connections and releases by controlling hydraulic power flow, using synchromesh mechanism clutches to minimize heat generation and reduce transmission losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a torque converter is used for power transmission, then torque amplification is achieved in low-speed range, but transmission efficiency is reduced due to sliding
Solution Approach 1:
The power transmission system is divided into multiple independent transmission paths: a torque converter path for low-speed torque amplification and a direct connecting mechanism path for high-speed efficient transmission. The planetary gear mechanism provides additional gear ratio stages. This segmentation allows the system to select the most efficient path based on operating conditions, resolving the contradiction between torque amplification and transmission efficiency.
2Loss of energy
If a lockup mechanism is used to mechanically connect engine output shaft and transmission output shaft, then power transmission efficiency increases, but the system becomes more complex
Solution Approach 1:
The direct connecting mechanism merges the engine output shaft and transmission output shaft through a rigid mechanical connection, eliminating the need for a separate lockup clutch mechanism. This integration achieves high efficiency power transmission while reducing system complexity compared to traditional torque converter vehicles with lockup mechanisms.
3Adaptability or versatility
If hydraulic power transmission is used in high-speed range, then the system maintains hydraulic connection, but transmission efficiency is reduced
Solution Approach 1:
The system dynamically switches between hydraulic power transmission and direct mechanical connection based on operating speed and load conditions. The control mechanism activates the direct connecting mechanism in high-speed range to eliminate hydraulic losses, while maintaining hydraulic connection flexibility when needed. This dynamic adaptation resolves the contradiction between operational versatility and transmission efficiency.
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 device achieves stable and efficient power transmission by quickly switching between hydraulic and direct connecting mechanisms, enhancing efficiency during low-speed operations and high-speed forwarding, thereby optimizing power distribution and reducing heat loss.
Implementation Method 1
a hydraulic pump and/or a hydraulic motor in a hydrostatic continuously variable transmission are of variable displacement type. A vehicle with a hydrostatic continuously variable transmission changes its volume by controlling tilting of a variable displacement hydraulic pump or a hydraulic motor
Implementation Method 2
using synchromesh mechanism clutches to minimize heat generation and reduce transmission losses
Data Source
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AI summary
A transmission (21) as a power transmission device for a vehicle comprises an input shaft (22), an output shaft (23), a planetary continuously variable transmission mechanism (31), a direct connecting mechanism (27), and an idler gear (29). The direct connecting mechanism (27) comprises a direct connecting clutch (30). The planetary continuously variable transmission mechanism (31) comprises a planetary gear mechanism (32), a pump side clutch (33), a hydraulic pump (36), a hydraulic motor (38), and a motor side clutch (40). The hydraulic pump (36) and the hydraulic motor (38) are connected via a pair of main lines (37A, 37B). An electromagnetic on-off valve (41) capable of switching between a communicating state and a blocking state between the pair of main lines (37A, 37B) is provided between the pair of main lines (37A, 37B).