High-Speed 4-Way Rotary On/Off Valve for Virtually Variable Displacement Pump/Motor Applications

2011 ◽  
Author(s):  
Haink C. Tu ◽  
Michael B. Rannow ◽  
Meng Wang ◽  
Perry Y. Li ◽  
Thomas R. Chase ◽  
...  
Keyword(s):  
High Speed ◽  
Hydraulic Systems ◽  
Rotary Valve ◽  
Hydraulic Pump ◽  
Hydraulic Hybrid ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Pump Valve ◽  
Cycle Efficiency ◽  
Physical Displacement

The application of switched mode control to hydraulic systems has the potential of decreasing component complexity, size, and cost. This is accomplished by enabling variable pump or motor functionality using a single on/off valve paired with a compact, inexpensive fixed displacement machine. A 4-way tandem rotary on/off valve is presented in this paper that extends a novel rotary valve concept (experimentally validated for pump applications) to hydraulic pump/motors. The pump/valve system is referred to as a Virtually Variable Displacement Pump/Motor (VVDPM) since the effective displacement of the system is variable and not the physical displacement of the pump itself. This paper investigates the design and efficiency of the proposed rotary valve when utilizing the VVDPM on a light weight power-split hydraulic hybrid passenger vehicle that is driven over a standard federal drive cycle. Simulated VVDPM efficiency maps are presented for motoring and pumping and the cycle efficiency of an optimized VVDPM is compared to that of a typical bent axis unit. Vehicle fuel economy is also explored through simulation.

Design, Modeling, and Validation of a High-Speed Rotary Pulse-Width-Modulation On/Off Hydraulic Valve

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Haink C. Tu ◽  
Michael B. Rannow ◽  
Meng Wang ◽  
Perry Y. Li ◽  
Thomas R. Chase ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Pulse Width ◽  
High Speed ◽  
Pulse Width Modulation ◽  
Hydraulic Systems ◽  
Rotary Valve ◽  
Output Pressure ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Actuation Power

Efficient high-speed on/off valves are an enabling technology for applying digital control techniques such as pulse-width-modulation (PWM) to hydraulic systems. Virtually variable displacement pumps (VVDPs) are one application where variable displacement functionality is attained using a fixed-displacement pump paired with an on/off valve and an accumulator. High-speed valves increase system bandwidth and reduce output pressure ripple by enabling higher switching frequencies. In addition to fast switching, on/off valves should also have small pressure drop and low actuation power to be effective in these applications. In this paper, a new unidirectional rotary valve designed for PWM is proposed. The valve is unique in utilizing the hydraulic fluid flowing through it as a power source for rotation. An unoptimized prototype capable of high flow rate (40 lpm), high speed (2.8 ms transition time at 100 Hz PWM frequency), and low pressure drop (0.62 MPa), while consuming little actuation power (<0.5% full power or 30 W, scavenged from fluid stream), has been constructed and experimentally validated. This paper describes the valve design, analyzes its performance and losses, and develops mathematical models that can be used for design and simulation. The models are validated using experimental data from a proof-of-concept prototype. The valve efficiency is quantified and suggestions for improving the efficiency in future valves are provided.

Modeling and Validation of a High Speed Rotary PWM On/Off Valve

2009 ◽  
Author(s):  
Haink C. Tu ◽  
Michael B. Rannow ◽  
Meng Wang ◽  
Perry Y. Li ◽  
Thomas R. Chase
Keyword(s):  
High Speed ◽  
Pulse Width Modulation ◽  
Hydraulic Systems ◽  
Rotary Valve ◽  
Flow Area ◽  
Output Pressure ◽  
Critical Technology ◽  
Variable Displacement ◽  
Pressure Ripple ◽  
Actuation Power

Efficient high-speed on/off valves are a critical technology for enabling digital control of hydraulic systems via pulse-width-modulation (PWM). High-speed valves, when used in virtually variable displacement pumps (VVDP), increase system bandwidth and reduce output pressure ripple by enabling higher PWM frequencies. Our approach to achieving high speed and large flow area with low actuation power is a unidirectional rotary valve designed specifically for PWM. In comparison to conventional valves, the rotary valve reduces valve actuation power from a cubic dependence on PWM frequency to a square dependence by eliminating motion reversals during transition. This paper presents experimental data that validates the rotary valve concept, valve design equations, and dynamic model of a rotary valve based VVDP. Our unoptimized prototype exhibits 65% efficiency at 50% displacement and 15Hz PWM frequency while the validated model projects that an optimized valve is capable of achieving 85% efficiency at 15Hz and 73% at 75Hz.

scholarly journals Dynamic and efficiency characteristics of an inlet metering valve controlled fixed displacement pump

2016 ◽  
Author(s):  
◽  
Julie Kay Wisch
Keyword(s):  
Significant Loss ◽  
Hydraulic Systems ◽  
Hydraulic Pump ◽  
Pump Design ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Spool Valve ◽  
Complex Parts ◽  
Pressure Controlled ◽  
Variable Displacement Pumps

This project developed the inlet metering system. An inlet metering system represents a new option in hydraulic pump design. Traditional pressure controlled hydraulic pumps rely on either swashplate displacement (for variable displacement pumps) or bleed off valves (for fixed displacement pumps). Variable displacement pumps require mechanically complex parts which are expensive to machine and prone to break down. Bleed off valves represent a significant loss in system efficiency. In contrast, the inlet metering system is able to make use of a fixed displacement pump (which is relatively inexpensive and mechanically robust) and a two-way spool valve. This dissertation goes through the process of designing the valve and pump dimensions, presents a theoretical dynamic analysis, studies the control law associated with this pump, and examines the energy requirements associated with inlet metering system operation. A prototype of the design was constructed and experimental data was used to validate the efficiency analysis. The major finding associated with this work was that the inlet metering system can be designed to display a first order pressure response. This means that when the inlet metering system is operated, the actual pressure in the system will never exceed the desired pressure. In contrast, traditional hydraulic systems will display up to 60% pressure overshoot, meaning the systems must be designed to handle pressures significantly greater than operating pressures. Additionally it was found that the inlet metering system is more efficient than using a bleed off valve, but less efficient than using a variable displacement pump.

Switchmode Hydraulic Power Supply Theory

2005 ◽  
Author(s):  
Jianwei Cao ◽  
Linyi Gu ◽  
Feng Wang ◽  
Minxiu Qiu
Keyword(s):  
Flow Rate ◽  
Dynamic Characteristics ◽  
Power Supply ◽  
Power Loss ◽  
High Speed ◽  
Hydraulic Pressure ◽  
Hydraulic Systems ◽  
Hydraulic Pump ◽  
Hydraulic Power ◽  
Supply Pressure

Switchmode hydraulic power supply is a new kind of energy-saving pressure converting system, which is originally proposed by the authors. It is mainly applied in multiple-actuator hydraulic systems, and installed between hydraulic pump and actuators (one switchmode hydraulic power supply for one actuator). It can provide pressure or flow rate that is adapted to the consumption of each actuator in the system by boosting or bucking the pressure, with low power loss, and conveniently, through high-speed switch valves, just like a hydraulic pressure transformer. There are two basic types of switchmode hydraulic power supply: pressure boost and pressure buck. Their structures and working principles are introduced. The dynamic characteristics of two typical types of switchmode hydraulic power supply, the pressure boost type and the pressure buck type, were analyzed through simulations and experiments. The performances were evaluated, and improvements on the efficiency of switchmode hydraulic power supply were proposed.

Simulation and Field Experiments With an Agricultural Tractor of a Robust Control for a Complete Fluid Power Circuit Using a New Electro-Hydraulic Pump: Part II—Control

2010 ◽  
Author(s):  
Pandeli Borodani ◽  
Davide Colombo ◽  
Marco Forestello ◽  
Patrizio Turco ◽  
Riccardo Morselli
Keyword(s):  
Field Experiments ◽  
Optimization Techniques ◽  
Point Of View ◽  
Hydraulic Pump ◽  
Power Circuit ◽  
Control Approach ◽  
New Device ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Energetic Point

The plant under control is the hydraulic circuit arranged by CNH in a prototype agriculture tractor of medium segment, where instead of the conventional main hydraulic pump, a new device electronically piloted, is installed. The main purpose is basically to obtain some advantages according to the energetic point of view, by means of an appropriate control structure, managing the electronic variable displacement pump. The frontier of the new systems requires the employment of the advanced control techniques, in order to assure the levels of precision, reliability, robustness demanded from systems. The control design methodology employed in the present case is based on robust H∞ optimization techniques, where robust stability properties are guaranteed in presence of unaccountable dynamics and other destabilizing factors. The effectiveness of the proposed control approach is tested on the demonstrative tractor realized from the CNH Agriculture at Modena plants, in all real conditions.

Design and Testing of an Adjustable Linkage for a Variable Displacement Pump

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Shawn R. Wilhelm ◽  
James D. Van de Ven
Keyword(s):  
High Efficiency ◽  
Operating Conditions ◽  
The Novel ◽  
Hydraulic Pump ◽  
Low Friction ◽  
Transmission Angle ◽  
Displacement Pump ◽  
Order Of Magnitude ◽  
Variable Displacement ◽  
Design And Testing

A variable displacement hydraulic pump/motor with high efficiency at all operating conditions, including low displacement, is beneficial to multiple applications. Two major energy loss terms in conventional pumps are the friction and lubrication leakage in the kinematic joints. This paper presents the synthesis, analysis, and experimental validation of a variable displacement sixbar crank-rocker-slider mechanism that uses low friction pin joints instead of planar joints as seen in conventional variable pump/motor architectures. The novel linkage reaches true zero displacement with a constant top dead center position, further minimizing compressibility energy losses. The synthesis technique develops the range of motion for the base fourbar crank-rocker and creates a method of synthesizing the output slider dyad. It is shown that the mechanism can be optimized for minimum footprint and maximum stroke with a minimum base fourbar transmission angle of 30 deg and a resultant slider transmission angle of 52 deg. The synthesized linkage has a dimensionless stroke of 2.1 crank lengths with a variable timing ratio and velocity and acceleration profiles in the same order of magnitude as a comparable crank-slider mechanism. The kinematic and kinetic results from an experimental prototype linkage agree well with the model predictions.

scholarly journals A novel cutterhead off-stuck strategy for tunnel boring machine based on electro-hydraulic hybrid driving

2019 ◽  
Vol 11 (1) ◽  
pp. 168781401882417 ◽  
Author(s):  
Tong Liu ◽  
Guofang Gong ◽  
Huayong Yang ◽  
Yongliang Cheng ◽  
Yuxi Chen ◽  
...  
Keyword(s):  
Normal Load ◽  
Tunnel Boring Machine ◽  
Driving System ◽  
Tunnel Boring ◽  
Hydraulic Hybrid ◽  
Closed Type ◽  
Displacement Pump ◽  
Torque Capacity ◽  
Variable Displacement ◽  
Low Torque

The cutterhead driving system of a tunnel boring machine may easily get jammed in fault zones driven by electro-motors of low torque capacity. To improve the geological adaptability, this work presents a novel electro-hydraulic hybrid cutterhead driving system to control high-torque hydro-motors as followers under the torque master–slave strategy together with electro-motors. Specific half closed-type pump–motor system is designed, the work pressure of the hydro-motor is regulated by proportional overflow valve to track the torque of the main electro-motor, and a variable displacement pump is controlled to track the expected speed of the main electro-motor with stable overflow via the proportional overflow valve. Feed-forward control principles are derived via the inner mechanism analyses of the proportional overflow valve and variable displacement pump, and proportional and integral separated feedbacks are also introduced to build compound controllers for the tracking of pressure and pump displacement, respectively. The hybrid driving experiments on a Φ2.5 m tunnel boring machine rig indicate that the hydro-motor could track 1.5 times the main electro-motor torque with error within ±15.2 N m against load change and system oscillation, and the error ratios of hydro-motor and slave electro-motor are similar at normal load and fixed speed. Furthermore, jammed cutterhead could be restarted with each hydro-motor supplying double torque of the main electro-motor, and the required assembly power is only 25% of alternative electro-motors.

Design and Testing of Novel Hydraulic Pump/Motors to Improve the Efficiency of Agricultural Equipment

2017 ◽  
Vol 60 (6) ◽  
pp. 1809-1817
Author(s):  
Farid Breidi ◽  
Jordan Garrity ◽  
John Lumkes
Keyword(s):  
Agricultural Sector ◽  
Energy Savings ◽  
Fluid Power ◽  
System Level ◽  
Hydraulic Systems ◽  
Hydraulic Pump ◽  
Agricultural Equipment ◽  
Load Height ◽  
Variable Displacement ◽  
The Impact

Abstract. Hydraulic systems are prevalent in agricultural machinery and equipment and can be found transmitting power for vehicle drive wheels, powering attachments, and controlling motion (booms, steering, load height, etc.). Agricultural applications of fluid power have advanced in terms of capability and efficiency, but opportunities remain for significant improvements in efficiency, noise reduction, and reliability. The average system-level hydraulic efficiency of current mobile agricultural machines is only 21.1%. Because nearly all hydraulic systems use pumps to convert engine power to fluid power, improving the efficiency of the pumps (and motors when used as actuators) significantly impacts the system efficiency. This work examines the impact of using more efficient digital pump/motors to improve the overall efficiency of agricultural equipment, such as tractors, harvesters, planters, fertilizers, sprayers, and attachments. Maintaining higher pump/motor efficiency throughout the operating range is the central principal for the energy savings. Currently used variable-displacement pumps have low efficiencies at low displacement levels due to constant losses that do not scale with the power produced. Digital pump/motors minimize these inefficiencies because energy losses scale more closely with the power produced. Experimental results indicate an average efficiency of 85% when operating at 20% to 100% displacement. This efficiency is 15% to 20% higher on average than with current variable-displacement axial piston pumps. This study demonstrates that achieving this improvement in the efficiency of the pump/motors used in tractors and harvesters alone would conservatively save $61.7 million worth of energy annually for end users in the U.S. agricultural sector. Keywords: Agricultural equipment, Digital hydraulics, Efficiency improvement, Hydraulic pump/motor.

The Swashplate Angle Control of a Variable Displacement Pump with an Electro-Hydraulic Proportional Valve

2008 ◽  
Vol 594 ◽  
pp. 389-400 ◽  
Author(s):  
Ming Hwei Chu ◽  
Yuan Kang ◽  
Yi Wei Chen ◽  
Yeon Pun Chang
Keyword(s):  
Angular Displacement ◽  
Mathematic Model ◽  
Hydraulic Systems ◽  
Displacement Pump ◽  
Type Variable ◽  
Hydraulic Servo ◽  
Simulation And Experiment ◽  
Variable Displacement ◽  
Servo Controller ◽  
The Stability

In this paper, the mathematic model of the swashplate type variable displacement axial piston pump (VDAPP) is established. The VDAPP applied to an electro-hydraulic servo control system usually induces unstable performance, so that a servo controller is designed and analyzed to control the swashplate angular displacement and improve the stability and transient response of pump performance. The flow and pressure variations of pump with the proposed controller are investigated and analyzed by mathematic simulations and experiments. The simulation and experiment results show that the proposed controller can improve the stability of swashplate angular displacement, and easily applied to the energy saving hydraulic systems.

Software Enabled Variable Displacement Pumps

2005 ◽  
Author(s):  
Perry Y. Li ◽  
Cassie Y. Li ◽  
Thomas R. Chase
Keyword(s):  
Feedback Control ◽  
Response Time ◽  
Low Cost ◽  
Hydraulic Systems ◽  
Ongoing Research ◽  
Throttle Valve ◽  
System Pressure ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Variable Displacement Pumps

Direct pump control of hydraulic systems is more energy efficient than throttle valve based methods to control hydraulic systems. This requires variable displacement pumps that are responsive and capable of electronic control. Such Electronic Displacement Controlled (EDC) pumps tend to be significantly larger, heavier and more expensive than fixed displacement counterparts. In addition, achievable control bandwidths are typically lower than throttle valve based control approaches. We have recently begun a project to achieve the functionality of a variable displacement pump by combining a fixed displacement pump, a pulse width modulated (PWM) on/off valve under closed loop feedback control, and an accumulator. The proposed topology is the hydro-mechanical analog of the DC-DC boost converter in power electronics. Since on/off valves have little loss in either the on or the off state, this approach is potentially more efficient than throttle valve based control approaches. It has the small size/weight and low cost advantages of a fixed displacement pump. Faster response can be expected by eliminating the intervening inertias of the swash plate control system. The pump’s functionalities can also be easily programmed by controlling the PWM on/off valve in different manners. This paper presents some preliminary results from this ongoing research program. While the PWM valve based approach provides desirable features, it also introduces undesirable ripples to the system pressure and flow rate. It is shown that increasing the accumulator pre-charge pressure and the accumulator volume can decrease ripple size at the expense of response time. This apparent trade-off can be alleviated by feedback control to achieve fast response time while keeping ripple small. Feedback control using PWM control must be implemented with care since the conventional “state-space” model may not be valid when the PWM frequency is low. On the other hand, increasing PWM frequency reduces ripple size and enables the system to achieve high control bandwidths.

Sign in / Sign up

Export Citation Format

Share Document