Pressure Shifted Valve Timing in Hydraulic Pump-Motors
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Solution Overview
Problem
Conventional hydraulic pump-motors experience significant throttling losses due to poorly designed valve timing and area profiles, leading to inefficiencies, torque ripple, flow ripple, noise, and vibration, especially when handling pressure spikes and cavitation during pressure reversals.
Innovation Solution
The implementation of a pressure-shifted valve timing technique, which includes a timing adjustment actuator that dynamically adjusts the angular orientation of the fixed valve area profile relative to the cam based on pressure differentials between ports, reducing throttling by optimizing valve timing and area profiles for efficient operation across a wide pressure range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed valve area profile is used to control fluid flows, then the structure is simple, but throttling losses increase and efficiency decreases
Solution Approach 1:
The patent applies dynamics by making the valve timing adjustable rather than fixed. The timing adjustment actuator dynamically modifies the angular orientation of the fixed valve area profile relative to the cam based on operating conditions, allowing the valve timing to adapt to different pressure ranges and flow rates, thereby reducing throttling losses while maintaining structural simplicity.
Solution Approach 2:
The patent changes the parameter of valve timing (angular orientation) based on pressure differentials. The timing adjustment actuator modifies the timing parameter in response to varying operating conditions, enabling the system to optimize efficiency across different pressure ranges without changing the fundamental valve structure.
2Loss of energy
If valve timing is optimized to reduce throttling, then efficiency improves, but torque ripple and flow ripple increase
Solution Approach 1:
The dynamic adjustment of valve timing allows the system to optimize the balance between reducing throttling losses and minimizing torque ripple. By continuously adapting the timing based on pressure differentials, the system can maintain smooth operation across varying conditions rather than being locked into a fixed timing that may cause ripple under certain operating ranges.
Solution Approach 2:
The timing adjustment actuator uses feedback from pressure differential sensing to continuously optimize valve timing. This feedback mechanism allows the system to respond to changing operating conditions and adjust timing to minimize both throttling losses and torque ripple, achieving a balance that fixed timing cannot provide.
3Adaptability or versatility
If pressure shifted valve timing is implemented to reduce throttling, then efficiency improves across wide pressure range, but device complexity increases
Solution Approach 1:
The timing adjustment actuator is driven by the pressure differential itself, using the operating conditions to automatically adjust the valve timing without requiring external control systems. This self-service approach allows the system to adapt to different pressure ranges while minimizing the complexity of the control mechanism.
Solution Approach 2:
The patent uses pneumatic/hydraulic principles by employing the pressure differential between ports to drive the timing adjustment actuator. This approach leverages the existing fluid pressure in the system to control the valve timing, avoiding the need for separate electrical or mechanical control systems and thereby limiting the increase in device complexity.
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 approach significantly reduces throttling losses, improves operational efficiency, minimizes noise and vibration, and enhances the hydraulic pump-motor's ability to handle pressure spikes, resulting in more efficient energy use and reduced cooling requirements.
Implementation Method 1
a timing adjustment actuator configured to adjust an angular orientation of the fixed valve area profile relative to an angular orientation of the cam based on a pressure differential between a pressure at the first port and a pressure at the second port
Implementation Method 2
A non-zero pressure differential between the first and second ports creates a net pressure difference between the first and second actuator chambers and adjusts an angular orientation of the fixed valve area profile
Data Source
AI summary
A hydraulic pump-motor includes a cylinder block including a plurality of fluid chambers, a piston in each of the fluid chambers, a cam, a fixed valve area profile, and a timing adjustment actuator. The cam includes a cam surface that engages the pistons and drives movement of the pistons relative to the fluid chambers in response to relative rotation between the cam and the fluid chambers. The fixed valve area profile is configured to control fluid flows between the fluid chambers and first and second ports. The timing adjustment actuator is configured to adjust an angular orientation of the fixed valve area profile relative to an angular orientation of the cam based on a pressure differential between a pressure at the first port and a pressure at the second port.