Off-Axis Vane Pump with Belleville Spring Preload
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hydraulic pumps in automatic transmissions face challenges in achieving high efficiency, compact size, self-priming capability, and effective operation under cold start conditions with high viscosity transmission fluid, particularly when mounted on-axis and driven by the engine.
Innovation Solution
A fixed displacement vane pump with an off-axis design, utilizing a rotor with radial slots and vanes constrained by vane rings, and a Belleville spring for preload, which reduces leakage and allows for flexible mounting and drive arrangements, including electric motor operation, to enhance efficiency and self-priming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the pump is mounted on-axis and driven by the engine, then the pump can be directly driven at engine speed, but the pump size increases significantly due to the large torque converter hub diameter
Solution Approach 1:
The patent transitions from an on-axis configuration to an off-axis configuration, changing the spatial arrangement from concentric to eccentric. This dimensional repositioning allows the pump to be driven by a small shaft (9-12mm) instead of a large torque converter hub, significantly reducing pump diameter while maintaining engine-speed driving capability through chain or gear drive arrangements.
2Productivity
If the pump is designed for high efficiency, then volumetric efficiency improves, but the pump becomes more sensitive to leakage which affects cold start performance
Solution Approach 1:
The patent applies a Belleville spring to apply axial preload to the port plates, changing the pressure parameter at the sealing interfaces. This preload increases the contact force between the port plates and pump body, reducing leakage paths. The spring mechanism dynamically adjusts to pressure changes, maintaining effective sealing during cold start conditions when fluid viscosity is high, while preserving high volumetric efficiency during normal operation.
3Loss of energy
If the pump uses a small shaft diameter, then rotational friction reduces and efficiency improves, but the drive arrangement becomes more complex requiring chain or gear trains
Solution Approach 1:
The patent separates the driving function from the pumping function by using an off-axis configuration with chain or gear drive arrangements. This segmentation allows the pump shaft to be optimized for minimal diameter (9-12mm) to reduce rotational friction and improve efficiency, while the chain or gear train handles the power transmission from the engine, providing the necessary speed increase or decrease relative to engine speed.
4Reliability
If the pump is designed for self-priming, then cold start capability improves, but the pump requires tighter tolerances that increase manufacturing difficulty
Solution Approach 1:
The patent uses the Belleville spring to apply preliminary axial preload to the port plates before the pump operates. This pre-compression ensures that the sealing interfaces between the port plates and pump body are already in effective contact, creating reliable sealing that enables self-priming capability. The preload mechanism establishes the necessary sealing pressure in advance, allowing the pump to prime itself during cold start without requiring excessively tight manufacturing tolerances.
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 off-axis design reduces rotational and sliding friction, improves volumetric efficiency, and ensures self-priming, enabling better performance at low speeds and cold start conditions, while allowing for flexible mounting and increased efficiency in both front and rear wheel drive transmissions.
Implementation Method 1
A Belleville spring or similar type of preload spring compresses the port plates against the pump body
Implementation Method 2
The rotor is eccentrically disposed in the cylindrical chamber and thus defines a crescent shaped pumping chamber
Implementation Method 3
The outer ends or edges of the vanes are in contact with the wall of the cylindrical chamber and the inner ends or edges are in contact with a pair of vane rings disposed within recesses in the rotor
Implementation Method 4
the outside (rear) surface of the rear port plate is exposed to the pressurized, pumped fluid and the resulting force further biases the port plates and pump body together, further reducing leakage
Data Source
AI summary
A vane pump for an automatic transmission includes a housing which may be spaced from the axis of the transmission input shaft axis and driven by a chain or gear train driven by the torque converter hub or disposed on and about the axis of the transmission input shaft and driven at engine speed. The vane pump includes a pair of port plates which reside on the end faces of a pump body having a cylindrical chamber which receives an eccentrically disposed rotor that is coupled to a stub shaft in an off-axis arrangement. The rotor includes a plurality of radial slots which receive a like plurality of vanes. The outer ends or edges of the vanes are in contact with the wall of the cylindrical chamber and the inner ends or edges are in contact with a pair of vane rings received within recesses in the ends of the rotor. The vanes are thus constrained between the wall of the chamber and the vane rings which positively determine their radial positions as they and the rotor rotate. Suitable inlet (suction) and outlet (pressure) ports in the port plates supply and collect hydraulic fluid to and from the cylindrical chamber. A compression spring biases the port plates and body together. The vane pump according to the present invention is self-priming and achieves high pumping efficiency.