Transmission of Fluid Power by Pulsating-Flow (P-F) Concept in Hydraulic Systems

1966 ◽  
Vol 88 (2) ◽  
pp. 316-321 ◽  
Author(s):  
Cheng-Kuo Weng
Keyword(s):  
Dynamic Response ◽  
Hydraulic System ◽  
Power Transmission ◽  
Pulsating Flow ◽  
Fluid Power ◽  
Experimental Investigations ◽  
System Efficiency ◽  
Test Results ◽  
Hydraulic Systems ◽  
Line Loss

Theoretical and experimental investigations have been made on fluid-power transmission in hydraulic systems by pulsating flow. In particular, the system efficiency and the viscosity effect on the dynamic response of pulsating flow in the fluid line have been studied. Test results on the fluid-line dynamic response and on the system efficiency that obtained from the line-loss test setup and the miniaturized P-F hydraulic system setup, respectively, are presented.

Soft Switching Approach to Reducing Transition Losses in an On/Off Hydraulic Valve

2009 ◽  
Author(s):  
Michael B. Rannow ◽  
Perry Y. Li
Keyword(s):  
Hydraulic System ◽  
Check Valve ◽  
Fluid Flows ◽  
Soft Switching ◽  
Total System ◽  
System Efficiency ◽  
Hydraulic Systems ◽  
Controlled Systems ◽  
Flow Through ◽  
Hydraulic Valve

A method for significantly reducing the losses associated with an on/off controlled hydraulic system is proposed. There has been a growing interest in the use of on/off valves to control hydraulic systems as a means of improving system efficiency. While on/off valves are efficient when they are fully open or fully closed, a significant amount of energy can be lost in throttling as the valve transitions between the two states. A soft switching approach is proposed as a method of eliminating the majority of these transition losses. The operating principle of soft switching is that fluid can temporarily flow through a check valve or into a small chamber while valve orifices are partially closed. The fluid can then flow out of the chamber once the valve has fully transitioned. Thus, fluid flows through the valve only when it is in its most efficient fully open state. A model of the system is derived and simulated, with results indicating that the soft switching approach can reduce transition and compressibility losses by 79%, and total system losses by 66%. Design equations are also derived. The soft switching approach has the potential to improve the efficiency of on/off controlled systems and is particularly important as switching frequencies are increased. The soft switching approach will also facilitate the use of slower on/off valves for effective on/off control; in simulation, a valve with soft switching matched the efficiency an on/off valve that was 5 times faster.

scholarly journals The Influence of Valve-Pump Weight Ratios on the Dynamic Response of Leaking Valve-Pump Parallel Control Hydraulic Systems

2018 ◽  
Vol 8 (7) ◽  
pp. 1201 ◽  
Author(s):  
Haigang Ding ◽  
Jiyun Zhao ◽  
Gang Cheng ◽  
Steve Wright ◽  
Yufeng Yao
Keyword(s):  
Dynamic Response ◽  
Hydraulic System ◽  
Weight Ratio ◽  
Open Loop ◽  
Hydraulic Systems ◽  
Variable Speed ◽  
Weight Factors ◽  
Wide Range ◽  
Parallel Control ◽  
Valve Control

A new leaking valve-pump parallel control (LVPC) oil hydraulic system is proposed to improve the performance of dynamic response of present variable speed pump control (VSPC) system, which is an oil hydraulic control system with saving energy. In the LVPC, a control valve is operating at leaking status, together with a variable speed pump, to regulate the system flow of hydraulic oil simultaneously. Therefore, the degree of valve control and pump control can be adjusted by regulating the valve-pump weight ratio. The LVPC system design, mathematical model development, system parameter and control performance analysis are carried out systematically followed by an experimental for validation process. Results have shown that after introducing the valve control, the total leakage coefficient increases significantly over a wide range with the operating point and this further increases damping ratios and reduces the velocity stiffness. As the valve-pump weight ratio determines the flow distribution between the valve and the pump and the weight factors of the valve and/or the pump controls determines the response speed of the LVPC system, thus if the weight factors are constrained properly, the LVPC system will eventually have a large synthetic open-loop gain and it will respond faster than the VSPC system. The LVPC will enrich the control schemes of oil hydraulic system and has potential value in application requiring of fast response.

Soft Switching Approach to Reducing Transition Losses in an On/Off Hydraulic Valve

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Michael B. Rannow ◽  
Perry Y. Li
Keyword(s):  
Hydraulic System ◽  
Check Valve ◽  
Fluid Flows ◽  
Soft Switching ◽  
Total System ◽  
System Efficiency ◽  
Hydraulic Systems ◽  
Controlled Systems ◽  
Flow Through ◽  
Hydraulic Valve

A method for significantly reducing the losses associated with an on/off controlled hydraulic system is proposed. There has been a growing interest in the use of on/off valves to control hydraulic systems as a means of improving system efficiency. While on/off valves are efficient when they are fully open or fully closed, a significant amount of energy can be lost in throttling as the valve transitions between the two states when the switching times are not negligible. A soft switching approach is proposed as a method of eliminating the majority of these transition losses. The operating principle of soft switching is that fluid can temporarily flow through a check valve or into a small chamber while valve orifices are partially closed. The fluid can then flow out of the chamber once the valve has fully transitioned. Thus, fluid flows through the valve only when it is in its most efficient fully open state. A model of the system is derived and simulated, with results indicating that the soft switching approach can reduce transition and compressibility losses by 81% and total system losses by 64%. The soft switching approach has the potential to improve the efficiency of on/off controlled systems and is particularly beneficial as switching frequencies are increased. The soft switching approach will also facilitate the use of slower on/off valves for effective on/off control; in simulation, a valve with soft switching matched the efficiency of an on/off valve that was 4.4 times faster.

Energy Consumption Model of the Force Application Hydraulic System for Friction Welding Machine

2014 ◽  
Vol 536-537 ◽  
pp. 1361-1364
Author(s):  
Zheng Qiang Yang ◽  
Sui Geng Du
Keyword(s):  
Energy Consumption ◽  
Friction Welding ◽  
Hydraulic System ◽  
System Efficiency ◽  
Hydraulic Systems ◽  
Operating Characteristics ◽  
Force Application ◽  
Welding Machine ◽  
Output Flow ◽  
Low Efficiency

For the problem of low efficiency of the ordinary hydraulic systems of the friction welding machine, operating characteristics and efficiency model of the force application hydraulic system of friction welding machine are studied. The energy consumption characteristics of traditional welding machine are simulated, the efficiency characteristics of the force application hydraulic system of friction welding machine is studied, and the energy consumption and efficiency model are deduced. According to theoretical analysis, the system efficiency can be improved by changing pump output flow and relief output flow. The simulation results show that the working efficiency of the new system can be enhanced to 24%. The new friction welding hydraulic system was used in actual production and the system efficiency can be improved to 22%.

Investigation of the pulsation-reduction characteristics of an expansion chamber attenuator in a hydraulic system

2017 ◽  
Vol 232 (5) ◽  
pp. 872-880 ◽  
Author(s):  
Jiabin Zhu ◽  
Hua Zhou ◽  
Huayong Yang
Keyword(s):  
Insertion Loss ◽  
Hydraulic System ◽  
Test Results ◽  
Hydraulic Systems ◽  
Expansion Chamber ◽  
Experimental Conditions ◽  
Advantages And Disadvantages ◽  
Investigation Methods ◽  
Aerodynamic Field ◽  
Reduction Characteristics

This paper investigates the expansion chamber attenuator utilized in marine hydraulic systems to determine the pulsation-reduction characteristics in hydraulic deck machinery applications. First, the background is briefly introduced. Next, the advantages and disadvantages of investigation methods borrowed from the aerodynamic field are discussed with regard to hydraulic use. Insertion loss is eventually selected to evaluate the performance of the attenuator. Finally, attenuator prototypes and a test rig that simulates an actual marine hydraulic system in a vessel are manufactured, and the experimental conditions are introduced in detail to calculate and measure the insertion loss. As indicated by the investigation conclusion, mathematic computation generally fits the test results. A better choice of length–diameter ratio ranges and other characteristics are discussed. This paper provides theoretical and experimental evidence regarding design expansion chamber attenuator use in hydraulic systems.

Danfoss Digital Displacement® Excavator: Test Results and Analysis

2019 ◽  
Author(s):  
Joseph J. Budden ◽  
Christopher Williamson
Keyword(s):  
Energy Efficiency ◽  
Dynamic Response ◽  
Hydraulic System ◽  
Pump Efficiency ◽  
Hydraulic Control ◽  
Test Results ◽  
Enabling Technology ◽  
Performance Gains ◽  
Efficiency And Productivity ◽  
Operator Assistance

Abstract There is a long trend in off-highway vehicles toward higher energy efficiency and electro-hydraulic control. Digital pumps and motors are poised to become a significant enabling technology in this trend. This paper analyzes a 20-tonne tracked excavator that was equipped with digital displacement pumps and evaluated for efficiency and productivity. Previous research by Artemis Intelligent Power demonstrated improvements compared to a conventional, negative flow control excavator hydraulic system. With support from Artemis, the Danfoss Digital Displacement Excavator (DDE) is a step forward in terms of technology and commercial readiness. DDE is based on a CAT 320 next-generation excavator with completely electronic controls and advanced sensor and operator-assistance features. In before/after testing, DDE showed 15% higher productivity (in meters of trench per hour) and 13% higher efficiency (in meters per liter of fuel) for a trench digging cycle. Static pump efficiency is only part of the story; dynamic response and controllability contributed to the measured performance gains. Potential causes for variation in measurement were analyzed including operator variation, flow variation, and machine response.

Development of an Extended Duration 1200 Deg F Torque Motor

1963 ◽  
Vol 85 (1) ◽  
pp. 123-128
Author(s):  
J. R. Farron
Keyword(s):  
Air Force ◽  
Hydraulic System ◽  
High Performance ◽  
Material Selection ◽  
Test Results ◽  
Hydraulic Systems ◽  
Flight Vehicles ◽  
Control Functions ◽  
Motor Design ◽  
Extended Duration

The application of high performance fluid power servos for attitude and engine control functions to advanced flight vehicles necessitates advancing the state-of-the-art of hydraulic systems in regard to their sensitivity to environmental conditions. In order to achieve this objective, the Air Force has sponsored the design and development of a 1000 deg F hydraulic system. This paper reviews the development and evaluation of an extended duration 1200 deg F torque motor representing the first component developed specifically for this system. Emphasis in the paper is placed on the approach to material selection, motor design, and the test results obtained.

Sign in / Sign up

Export Citation Format

Share Document