Dual-Pump Hydraulic Control for DCT Cooling and Shift Stability
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Solution Overview
Problem
Current double-clutch automatic gearboxes face inefficiencies due to large mechanical pumps, which increase weight and reduce fuel economy, and are not optimized for hybrid-power vehicles, leading to heat-related issues and clutch failure.
Innovation Solution
A hydraulic controlling system with a combination of a mechanical and electronic pump, a selector valve, and pressure regulating valves to manage oil flow and pressure, reducing pump displacement and weight while maintaining efficient lubrication and cooling, and enabling quick and steady gear shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical pump of large displacement is used to supply the flow rate, then the cooling and lubricating requirement is met, but the volume and weight of the pump increase, resulting in low efficiency and poor fuel economy
Solution Approach 1:
The patent divides the pump system into two separate pumps: a first pump dedicated to cooling and lubrication functions, and a second pump dedicated to gear-shifting control functions. This segmentation allows each pump to be optimized for its specific function, enabling the use of a smaller-displacement pump for gear-shifting while maintaining adequate cooling and lubrication capacity.
Solution Approach 2:
The patent introduces a variable displacement mechanism for the second pump, allowing its displacement to be adjusted dynamically based on gear-shifting requirements. This dynamic adjustment enables the pump to provide sufficient flow rate during gear-shifting operations while reducing displacement during normal operation, thereby decreasing overall weight and improving fuel economy.
2Reliability
If a mechanical pump of large displacement is used to supply the flow rate, then the cooling and lubricating requirement is met, but the volume and weight of the pump increase, resulting in low efficiency and poor fuel economy
Solution Approach 1:
The patent divides the pump system into two separate pumps: a first pump dedicated to cooling and lubrication functions, and a second pump dedicated to gear-shifting control functions. This segmentation allows each pump to be optimized for its specific function, enabling the use of a smaller-displacement pump for gear-shifting while maintaining adequate cooling and lubrication capacity.
Solution Approach 2:
The patent introduces a variable displacement mechanism for the second pump, allowing its displacement to be adjusted dynamically based on gear-shifting requirements. This dynamic adjustment enables the pump to provide sufficient flow rate during gear-shifting operations while reducing displacement during normal operation, thereby decreasing overall volume and improving fuel economy.
3Speed
If the gear-shifting flow rate is increased quickly, then the gear-shifting speed is improved, but the gear-shifting quality deteriorates due to impact and instability
Solution Approach 1:
The patent introduces a pre-shifting stage before the main gear-shifting operation. During this preliminary stage, the second pump begins to build up pressure and flow rate in advance, so that when the actual gear-shifting occurs, the oil is already ready to be delivered, eliminating delays while avoiding sudden pressure spikes that would cause impact.
Solution Approach 2:
The patent implements a multi-stage gear-shifting process with distinct phases: pre-shifting, main shifting, and post-shifting. Each phase has specific pressure and flow rate characteristics, creating a periodic action pattern that ensures smooth transitions. The pre-shifting phase prepares the system, the main shifting phase executes the gear change, and the post-shifting phase stabilizes the system, thereby improving both speed and quality.
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 system reduces pump volume and weight, improves fuel efficiency, and enhances clutch reliability by optimizing oil flow and pressure management, supporting hybrid-power vehicle applications and reducing the risk of clutch failure.
Implementation Method 1
a first pump, wherein an inlet of the first pump is connected to the oil-liquid storage, and an outlet of the first pump is connected to the main controlling oil line; a second pump, wherein an inlet of the second pump is connected to the oil-liquid storage, and an outlet of the second pump selectively communicates with the cooling and lubricating oil line or the main controlling oil line
Implementation Method 2
the hydraulic controlling system is configured to, in a gear-shifting starting stage, maintain an outputted pressure of the gear-shifting-pressure regulating valve at a first preset pressure
Implementation Method 3
regulate gear-shifting flow rates by using the gear-shifting-flow-rate controlling valves
Implementation Method 4
the double clutches in wet double-clutch automatic gearboxes, in the process of engagement, generates a large amount of heat due to the sliding g friction, and if the heat is not dissipated timely, it results in the ablation of the double clutches
Implementation Method 5
the quality of the designing of the cooling and lubricating system of double-clutch automatic gearboxes directly decides the operating performance of the double-clutch automatic gearboxes
Data Source
Figure 1
AI summary
A hydraulic controlling system and a vehicle, wherein the hydraulic controlling system includes: a cooling and lubricating oil line and a main controlling oil line; an oil-liquid storage; a first pump, wherein an inlet of the first pump is connected to the oil-liquid storage, and an outlet of the first pump is connected to the main controlling oil line; a second pump, wherein an inlet of the second pump is connected to the oil-liquid storage, and an outlet of the second pump selectively communicates with the cooling and lubricating oil line or the main controlling oil line; and a gearbox-gear-shifting oil line, wherein the gearbox-gear-shifting oil line includes a gear-shifting-pressure regulating valve, a plurality of gear-shifting-flow-rate controlling valves and a plurality of gear-shifting selector valves, the gear-shifting-flow-rate controlling valves are connected to the main controlling oil line via the gear-shifting-pressure regulating valve, and at least some of the plurality of gear-shifting-flow-rate controlling valves are connected to a gear-shifting executing piston via the gear-shifting selector valves.