Crank-Slider Spool Valve for Switch-Mode Circuits

2015 ◽  
Author(s):  
Alexander C. Yudell ◽  
Shaun E. Koktavy ◽  
James D. Van de Ven
Keyword(s):  
Duty Cycle ◽  
High Speed ◽  
Volumetric Flow Rate ◽  
Viscous Friction ◽  
Total Power ◽  
Design Solution ◽  
Switching Frequency ◽  
Trade Offs ◽  
Switch Mode ◽  
Transition Times

A key component of switch-mode hydraulic circuits is a high-speed two-position three-way valve with a variable duty cycle. This paper presents a new valve architecture that consists of two valve spools that are axially driven by crank-slider mechanisms. By phase shifting the two crank links, which are on a common crankshaft, the duty cycle of the valve is adjusted. The two spools split and re-combine flow such that two switching cycles occur per revolution of the crankshaft. Because the spools move in a near-sinusoidal trajectory, the peak spool velocities are achieved at mid-stroke where the valve land transitions across the ports, resulting in short valve transition times. The spool velocity is lower during the remainder of the cycle, reducing viscous friction losses. A dynamic model is constructed of this new valve operating at 120 Hz switching frequency in a switch-mode circuit. The model is used to illustrate design trade-offs and minimize energy losses in the valve. The resulting design solution transitions to the on-state in 5% of the switching period and the combined leakage and viscous friction in the valve dissipate 1.7% of the total power at a pressure of 34.5MPa and volumetric flow rate of 22.8L/min.

Design of a Crank-Slider Spool Valve for Switch-Mode Circuits With Experimental Validation

2017 ◽  
Vol 140 (6) ◽  
Author(s):  
Shaun E. Koktavy ◽  
Alexander C. Yudell ◽  
James D. Van de Ven
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Experimental Validation ◽  
Viscous Friction ◽  
Transition Time ◽  
Switching Frequency ◽  
Experimental Demonstration ◽  
High Switching Frequency ◽  
Switch Mode ◽  
Spool Valve

A challenge in realizing switch-mode hydraulic circuits is the need for a high-speed valve with fast transition time and high switching frequency. The work presented includes the design and modeling of a suitable valve and experimental demonstration of the prototype in a hydraulic boost converter. The design consists of two spools driven by crank-sliders, designed for 120 Hz maximum switching frequency at a flow rate of 22.7 lpm. The fully open throttling loss is designed for <2% of the rated pressure of 34.5 MPa. The transition time is less than 5% (0.42 ms at 120 Hz) of the total cycle and the duty cycle is adjustable from 0 to 1. Leakage and viscous friction losses in the design are less than 2% of the rated hydraulic energy per cycle. The experimental results agreed well with the model resulting in a 3% variation in transition time. The use of the high-speed valve in a pressure boosts converter demonstrated boost ratio capabilities of 1.08–2.06.

Phase-Shift High-Speed Valve for Switch-Mode Control

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
James D. Van de Ven ◽  
Allan Katz
Keyword(s):  
Phase Shift ◽  
High Speed ◽  
Viscous Friction ◽  
Duty Ratio ◽  
Switching Frequency ◽  
Full Potential ◽  
Hydraulic Actuator ◽  
Mode Control ◽  
Switch Mode ◽  
Variable Displacement

Hydraulic applications requiring a variation in the speed or torque of actuators have historically used throttling valve control or a variable displacement pump or motor. An alternative method is switch-mode control that uses a high-speed valve to rapidly switch between efficient on and off states, allowing any hydraulic actuator to have virtually variable displacement. An existing barrier to switch-mode control is a fast and efficient high-speed valve. A novel high-speed valve concept is proposed that uses a phase shift between two tiers of continuously rotating valve spools to achieve a pulse-width modulated flow with any desired duty ratio. An analysis of the major forms of energy loss, including throttling, compressibility, viscous friction, and internal leakage, is performed on a disk spool architecture. This analysis also explores the use of a hydrodynamic thrust bearing to maintain valve clearance. A nonoptimized design example of a phase-shift valve operating at 100 Hz switching frequency at 10 l/min demonstrates an efficiency of 73% at a duty ratio of 1 and 64% at 0.75 duty ratio. Numerous opportunities exist for improving this efficiency including design changes and formal optimization. The phase-shift valve has the potential to enable switch-mode hydraulic circuits. The valve has numerous benefits over existing technology yet requires further refinement to realize its full potential.

Development of a High-Speed On-Off Valve for Switch-Mode Control of Hydraulic Circuits With Four-Quadrant Control

2010 ◽  
Author(s):  
Jeslin J. Wu ◽  
James D. Van de Ven
Keyword(s):  
High Speed ◽  
Average Power ◽  
Viscous Friction ◽  
Valve Design ◽  
Rotating Disc ◽  
Mode Control ◽  
Switch Mode ◽  
Variable Displacement ◽  
Four Quadrant ◽  
Hydraulic Circuits

Hydraulic circuits are typically controlled by throttling valves or variable displacement pump/motors. The first method throttles fluid for a desired pressure output and excess energy is lost through heat. While variable displacement pumps are more efficient, they are often large and expensive. An alternate method is the switch-mode control of hydraulic circuits through high-speed on-off valves. The proposed on-off valve design makes use of a continuously rotating disc to modulate flow between on and off states; the average power output or pulse duration is determined by the relative phase shift between the input and output ports. The addition of a directional valve to the the high-speed three-way valve allows any fixed displacement actuator to behave like a virtually variable displacement unit that is capable of four-quadrant control. In this paper a mathematical model focusing on the throttling, compressibility, internal leakage and viscous friction losses is developed and utilized to optimize the valve design for highest efficiency.

Design of a High-Speed On-Off Valve

2009 ◽  
Author(s):  
Allan A. Katz ◽  
James D. Van de Ven
Keyword(s):  
High Speed ◽  
First Generation ◽  
Viscous Friction ◽  
Input Power ◽  
Future Research ◽  
Switching Frequency ◽  
Efficient Design ◽  
Output Pressure ◽  
Parameter Values ◽  
Valve Control

On-off control of hydraulic circuits enables significant improvements in efficiency compared with throttling valve control. A key enabling technology to on-off control is an efficient high-speed on-off valve. This paper documents the design of an on-off hydraulic valve that minimizes input power requirements and increases operating frequency over existing technology by utilizing a continuously rotating valve design. This is accomplished through use of spinning port discs, which divides the flow into pulses, with the relative phase between these discs determining the pulse duration. A mathematical model for determining system efficiency is developed with a focus on the throttling, leakage, compressibility, and viscous friction power losses of the valve. Parameters affecting these losses were optimized to produce the most efficient design under the chosen disc-style architecture. Using these optimum parameter values, a first generation prototype valve was developed and experimental data collected. The experimental valve matched predicted output pressure and flows well, but suffered from larger than expected torque requirements and leakage. In addition, due to motor limitations, the valve was only able to achieve a 64Hz switching frequency versus the designed 100Hz frequency. Future research will focus on improving the prototype valve and improving the analytical model based on the experimental results.

scholarly journals Reliability-Oriented Design of Inverter-Fed Low-Voltage Electrical Machines: Potential Solutions

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4144
Author(s):  
Yatai Ji ◽  
Paolo Giangrande ◽  
Vincenzo Madonna ◽  
Weiduo Zhao ◽  
Michael Galea
Keyword(s):  
Power Density ◽  
High Speed ◽  
High Performance ◽  
Low Voltage ◽  
Electrical Machines ◽  
Design Stage ◽  
Switching Frequency ◽  
Special Focus ◽  
Electrical Machine ◽  
Engineering Approach

Transportation electrification has kept pushing low-voltage inverter-fed electrical machines to reach a higher power density while guaranteeing appropriate reliability levels. Methods commonly adopted to boost power density (i.e., higher current density, faster switching frequency for high speed, and higher DC link voltage) will unavoidably increase the stress to the insulation system which leads to a decrease in reliability. Thus, a trade-off is required between power density and reliability during the machine design. Currently, it is a challenging task to evaluate reliability during the design stage and the over-engineering approach is applied. To solve this problem, physics of failure (POF) is introduced and its feasibility for electrical machine (EM) design is discussed through reviewing past work on insulation investigation. Then the special focus is given to partial discharge (PD) whose occurrence means the end-of-life of low-voltage EMs. The PD-free design methodology based on understanding the physics of PD is presented to substitute the over-engineering approach. Finally, a comprehensive reliability-oriented design (ROD) approach adopting POF and PD-free design strategy is given as a potential solution for reliable and high-performance inverter-fed low-voltage EM design.

scholarly journals On-CMOS Image Sensor Processing for Lane Detection

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3713
Author(s):  
Soyeon Lee ◽  
Bohyeok Jeong ◽  
Keunyeol Park ◽  
Minkyu Song ◽  
Soo Youn Kim
Keyword(s):  
Edge Detection ◽  
High Speed ◽  
Cmos Image Sensor ◽  
Image Sensor ◽  
Image Resolution ◽  
Lane Detection ◽  
Frame Rate ◽  
Total Power ◽  
Detection Accuracy ◽  
Total Power Consumption

This paper presents a CMOS image sensor (CIS) with built-in lane detection computing circuits for automotive applications. We propose on-CIS processing with an edge detection mask used in the readout circuit of the conventional CIS structure for high-speed lane detection. Furthermore, the edge detection mask can detect the edges of slanting lanes to improve accuracy. A prototype of the proposed CIS was fabricated using a 110 nm CIS process. It has an image resolution of 160 (H) × 120 (V) and a frame rate of 113, and it occupies an area of 5900 μm × 5240 μm. A comparison of its lane detection accuracy with that of existing edge detection algorithms shows that it achieves an acceptable accuracy. Moreover, the total power consumption of the proposed CIS is 9.7 mW at pixel, analog, and digital supply voltages of 3.3, 3.3, and 1.5 V, respectively.

scholarly journals Why Protect Ancient Woodland in the UK? Rethinking the Ecosystem Approach

2020 ◽  
pp. 1-24
Author(s):  
Jona Razzaque ◽  
Claire Lester
Keyword(s):  
High Speed ◽  
Biodiversity Loss ◽  
Ecosystem Approach ◽  
Lessons Learned ◽  
Value Systems ◽  
Ancient Woodland ◽  
Forestry Practices ◽  
Regulatory Frameworks ◽  
Trade Offs ◽  
The Uk

Abstract Sites of ancient woodland in the United Kingdom (UK) are diminishing rapidly and the multifunctional forest management system with its fragmented approach fails effectively to protect such woodland. In the face of reports on the destruction of ancient woodland, the HS2 High-Speed train project in the UK signifies the extent of trade-offs among the key stakeholders. Such large infrastructure projects typically come with high environmental and social costs, including deforestation, habitat fragmentation, biodiversity loss, and social disruption. This article examines the protection of ancient woodland in the UK and assesses the challenges in applying the ecosystem approach, an internationally recognized sustainability strategy, in the context of such protection. A better understanding of the ecosystem approach to manage ancient woodland is critical for promoting sustainable forestry practices in the UK and informs the discussion in this article of the importance of conserving ancient woodland globally. Lessons learned from UK woodland policies and certification schemes include the need to have in place strong regulatory frameworks, introduce clear indicators, and recognize pluralistic value systems alongside economic considerations. The article concludes that the protection of ancient woodland in the UK requires distinct and strong laws that reflect multiple values of this resource, acknowledge the trade-offs among stakeholders, and adopt an inclusive approach to reduce power asymmetries.

AND-OR-XOR NETWORK SYNTHESIS WITH AREA-POWER TRADE-OFF

2011 ◽  
Vol 20 (06) ◽  
pp. 1019-1035 ◽  
Author(s):  
SAMBHU NATH PRADHAN ◽  
M. TILAK KUMAR ◽  
SANTANU CHATTOPDHYAY
Keyword(s):  
Boolean Function ◽  
Solution Space ◽  
Leakage Power ◽  
Total Power ◽  
Synthesis Process ◽  
Network Synthesis ◽  
Trade Off ◽  
Delay Performance ◽  
Trade Offs ◽  
Power Trade

In this paper, a heuristic based on genetic algorithm to realize multi-output Boolean function as three-level AND-OR-XOR network performing area power trade-off is presented. All the previous works dealt with the minimization of number of product terms only in the two sum-of-product-expressions representing a Boolean function during AND-OR-XOR network synthesis. To the best of knowledge this is the first ever effort to incorporate total power, that is, dynamic and leakage power along with the area (in terms of number of product terms) during three-level AND-OR-XOR networks synthesis. The synthesis process, without changing the delay performance results in lesser number of product terms compared to those reported in the literature. It also enumerates the trade-offs present in the solution space for different weights associated with area, dynamic power, and leakage power of the resulting circuit.

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