Variable Displacement Pump Hydraulic Cam Ring Control
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Solution Overview
Problem
Conventional variable displacement pumps used in automotive engines are large due to the need for a strong spring biasing force to balance hydraulic pressure, which complicates their design and size.
Innovation Solution
The pump design eliminates the need for a strong spring by using two pressure chambers with different pressure receiving surfaces to control the eccentricity of the cam ring, allowing the hydraulic pressures within these chambers to balance the biasing force, thereby reducing the size of the pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a strong spring biasing force is used to balance hydraulic pressure in conventional variable displacement pumps, then the pump can maintain variable displacement capabilities, but the pump size increases unavoidably
Solution Approach 1:
The patent replaces the mechanical spring biasing system with a hydraulic pressure balancing system. Two pressure chambers are introduced that receive discharge pressure from the pump, and these hydraulic pressures balance each other to control the cam ring position, eliminating the need for a strong spring and reducing pump size while maintaining variable displacement capability
Solution Approach 2:
The patent substitutes the mechanical spring-based biasing system with a hydraulic pressure-based control system. The mechanical force of a spring is replaced by hydraulic pressure forces acting on the cam ring through two pressure chambers, achieving the same functional effect with a more compact design
2Force
If a strong spring is used to balance hydraulic pressure, then the cam ring can be biased in the correct direction, but the pump becomes large-sized
Solution Approach 1:
The patent uses hydraulic pressure from the pump's discharge to create balancing forces in two pressure chambers. These hydraulic forces replace the spring biasing force, providing the necessary cam ring biasing action without requiring a large spring, thus reducing pump size while maintaining the required force
3Stability of the object's composition
If the spring biasing force is increased to control eccentricity, then the cam ring positioning is improved, but the pump complexity and size increase
Solution Approach 1:
The patent introduces two pressure chambers that receive discharge pressure to create a hydraulic balancing system. This system provides stable cam ring positioning through pressure equilibrium, replacing the complex spring mechanism and achieving stable positioning with a more efficient hydraulic approach
Solution Approach 2:
The patent changes the control parameter from mechanical spring force to hydraulic pressure. By using discharge pressure as the control parameter in two pressure chambers, the system achieves cam ring positioning stability through pressure balancing, simplifying the overall structure while maintaining positioning accuracy
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
This design results in a smaller-sized pump that maintains variable displacement capabilities, improving engine efficiency and reducing power loss by allowing for simpler control of discharge pressure characteristics based on engine operating conditions.
Implementation Method 1
a discharge pressure being introduced into the first pressure chamber to allow the discharge pressure to be applied through the first pressure receiving surface to the cam ring to oppose to a biasing force of the biasing member so as to provide the cam ring with a swinging force in a direction to decrease the eccentricity amount of the cam ring
Implementation Method 2
a discharge pressure being introduced into the first pressure chamber to allow the discharge pressure to be applied through the second pressure receiving surface to the cam ring to assist the biasing force of the biasing member so as to provide the cam ring with a swinging force in a direction to increase the eccentricity amount of the cam ring
Data Source
AI summary
A variable displacement oil pump for an automotive engine. The oil pump includes a cam ring accommodating thereinside a pump element having a rotor. The cam ring is swingingly movably accommodated in a housing and biased in a direction to increase an eccentricity amount of the cam ring relative to the axis of the rotor by a biasing member. First and second pressure chambers are defined inside the housing by the outer peripheral section of the cam ring. The first pressure chamber is supplied with a discharge pressure to be applied to the cam ring to oppose to a biasing force of the biasing member. The second pressure chamber is supplied with the discharge pressure to be applied to the cam ring to assist the biasing force of the biasing member. Additionally, a control device is provided for controlling supply of the discharge pressure to the second pressure chamber.