Search Results

Many existing electronic controls used in hydraulic systems utilize a microcontroller with associated electronic drive buffer and multiple closed loop feedback paths. One of the common feedback paths is through sensing the electrical current supplied to the solenoid for the proportional valve. Use of pulse-width-modulation (PWM) is typically utilized to minimize power dissipation in the electronic drive buffer and to facilitate integration with the microcontroller.

A distributed sensor is created to sense the rate of change in deflection of beam-like structures such as crane booms. This sensor will be useful in electrohydraulic compensation of boom deflections. The sensor is made of an array of strain-sensitive segments such as strain gages or piezoelectric film. In this example, segments of piezoelectric film convert strains on the surface of a vibrating beam into electrical outputs. These outputs are connected to low impedance signal conditioners. The output of the signal conditioners are then interpolated with a weighting vector that incorporates Lagrange polynomials, specified boundary conditions, and the desired location(s) of measurement. A simple linear combiner circuit combines the electrical outputs into the deflection velocity at the desired points.

Most fertilizer application systems are not capable of variable rate adjustments “on-the-fly”. To change the application rate, the farmer must dismount the tractor and change the gear ratio mechanically (i.e. via gears, chains, etc.). Air seeder manufacturers have come up with their own unique solutions to address this problem, usually involving electrohydraulics. At present there are older seeding units that perform adequately, but do not have the variable rate option. A retrofit is therefore very desirable for these units. In this paper, the feasibility of a simple hydraulic proportional valve and variable speed motor circuit is employed to replace the gears and chains. The unit is integrated with a microcontroller to provide compensation to the nonlinear properties of a proportional valve, and in turn provide a very accurate feedrate. In addition, direct user input from the cab of the tractor is possible, allowing on-the-go rate changes.

A four valve controller and electronic control circuits were developed to control the displacement of hydrostatic pump/motors (P/M's) utilized in an automobile with a hydrostatic transmission and hydropneumatic accumulator energy storage. Performance of the control system was evaluated. The controller uses four high-speed, two-way, single-stage poppet valves, functioning in the same manner as a 4-way, 3-position spool valve. Two such systems were used to control the displacement of two P/Ms, each system driving a front wheel of the vehicle. The valves were controlled electronically by a distributed-control dead-band circuit and valve driver boards. Testing showed that the control system's time response satisified driving demand needs, but that the control system's error was slightly larger than desired. This may lead to complications in some of the vehicle's operating modes.

SAE J1453 O-ring Face Seal (ORFS) Fittings have emerged as the premier fittings to eliminate fluid leakage. They utilize an elastomeric O-ring in a captive groove to prevent leakage at the fitting to tube/hose interface. A straight-sided groove had been used successfully for years, but it had the problem of not consistently retaining the O-ring in the groove until the fittings are assembled. A new dovetail groove, which positively retains the O-ring, has been designed and incorporated into the SAE J1453 standard. Several alternative designs were considered before agreeing to adopt the dovetail groove. This paper covers the development and testing conducted to adopt the dovetail groove in the SAE standard.

In mobile hydraulics pilot valves control pumps, motors and main stages. An influencing factor regarding the use of these valves is compact dimensions, which are realised in combining solenoids with the control pressure stage. Applied electrical power together with the corresponding pressure level will be explained in this presentation by showing two types of Proportional Pressure Reducing Valves (PPRV's). One will be a PPRV for various operating pressure levels and the other a High-Flow PPRV (HFPPRV) for high volume flows. Descriptions of function, design solutions, features and manufacturing techniques will follow as well as application of integrated electronics and simulation of solenoids.

There is a critical need for improved processes and systems mobility product life cycles and application of these improvements to vehicles on a global basis. As products expand to reach global markets, the need for globally harmonized test procedures, specifications and standards increase dramatically. According to Keith Termaat, Ford Motor Company, “as competitve and regulatory forces become increasingly global - worldwide standards development and deployment are essential for corporate survival.” The critical issue facing all Standards Developing Organizations (SDOs) will be facilitating this transformation quickly and efficiently and in a manner that will allow the automotive industry to expand into the global marketplace.

This paper will cover the importance of certification to individuals in the fluid power industry as well as the importance to industry in general. Fluid power is a world player in power transmission yet it is not a part of our school system curriculum. As an aid to remedy this the Fluid Power Society has developed a certification program with review training to establish several “benchmarks” that are recognized by industry nationally and internationally. The procedures for establishing fluid power certification have been approved by the American National Standards Institute and the Federal Government Department of Occupational titles has approved all the job descriptions.

This paper describes a new long life, heavy duty, air-to-air charge air cooler (CAC) which has particular application in heavy duty trucks, buses, off-highway vehicles and construction equipment. In this paper, it is proven through structural modeling and fatigue analysis on actual service histories that plastic flow and the resulting cumulative damage make it impossible for a typical brazed charge air cooler to meet minimum reliability requirements in at least some applications. Thermal expansion of the charge air cooler core, internal pressure, and external shock and vibration all contribute to a complex stress/strain response behavior in the area of the tube-to-header joint. Testing showed that the use of resilient tube-to-header joints, utilizing grommeted seals between the tubes and headers, eliminates the high stresses in this area and provides a theoretically infinite life.

Boosted Engine Systems components are those that supply and control the combustion air to the engine. The Boosted Engine Systems strategy is to optimize the air supply system to provide best efficiency for the actual intended duty cycle. This process involves measuring and analyzing the engine/vehicle duty cycle, and then optimizing the design of the system for best efficiency during that mode of operation. This approach can improve fuel efficiency, reduce emissions, reduce system weight and cost, and reduce the number of components in the system. Suggestions are made for optimum component design to meet system needs.

A model of the steering dynamics of an articulated loader is used to study the steering system instabilities and sensitivity to various parameters in the steering priority valve. The Taguchi method is used to evaluate the combinations. The study utilizes an L12 array with six parameters varied on two levels. A verification simulation is run which results in a stable, well-damped system. This study demonstrates that the Taguchi method is a viable approach to solving hydraulic system instabilities.

A track-type grapple log skidder was dynamically modeled to allow machine modification by computer to determine the effects of these modifications on the operation of the machine in the forest. The model consisted of an undercarriage, power train, log/drag force, and logging equipment (arch and grapple). This skidder had three types of logging attachments: winch, swinging boom (grapple), and single-function arch (grapple). Each was modeled and simulated under various conditions. The dynamic model of the skidder can be used to analyze its drawbar pull capability and lateral stability with various log weights and soil types on steep slopes. Validation of this model is needed later.

An electrohydraulic or a hydromechanical system used in a mobile or industrial application is comprised of many different elements such as controllers, sensors, solenoids, pumps, valves, actuators etc. Often the characteristics of these components are non-linear and the interaction complex when subjected to various kinds of inputs and load situations. In order to design a stable and responsive hydraulic system application that would continue to perform reliably, it is essential to have a simulation model of the system at the early stage of the inception of the design. The simulation would predict the expected performance of each of the components of the system and be useful if the actual hardware deviates from the desired performance. To make the simulation effort expedient and worthwhile a faster computer and an easy to use software is necessary.

A 3-dimensional, full-vehicle computer model was created of a conventional 218 tonne payload capacity mine haul truck. Simulations were performed of a number of situations typifying in-service operation to gain insight into various aspects of the dynamic response of the hauler. A 0.25 g lane change maneuver was simulated that can represent a wide range of haul truck movements in a mine, such as collision avoidance or following a change in haul road alignment. Peak wheel loads of approximately 100 tonne were recorded, and these are about 1.7 times greater than the rated capacity of the tire. Travel on an uneven haul road was also simulated and dynamic wheel loads were predicted that are 1.3 times tire static loads. The characteristics of the road surface used in the simulations were measured with an ARRB Transport Research Ltd. road profiler. Unevenness features of sealed and unsealed roads are presented and discussed.

A major objective of many of today's corporations is reducing time to market for new products. This goal, coupled with the fact that systems are only becoming more complex is driving many engineering organizations to employ the use of virtual prototyping, simulation and control system design software. Unfortunately, despite the promise of these tools, no single dynamic system modeling package allows the engineer to easily prototype all aspects of a complex system; mechanisms, hydraulics, pneumatics, thermodynamics, powertrains and electric drives, digital controllers, state machines and electronics. One solution to this problem is to integrate multiple CAE applications, allowing the end-user to create and manipulate a complete virtual prototype of their entire system. This paper focuses on the work The Boeing Company has done integrating its dynamic system model, simulation, and control tool set, called EASY5®, with other CAE applications.

Electronics content in off-highway machinery and vehicles is growing in size and complexity. Mr. Ronald K. Leonard, 1998 SAE President, recently gave a lecture titled “Electronics - A New Engine For Agricultural Machines” in London, UK[1] that described electronics as an enabler of new functionality and business solutions. Electronics is the term for both hardware and embedded software that enables manufacturers to optimize and expand performance of traditional mechanical and hydraulic machinery. This paper focuses on the development of the software that is involved in controlling devices such as an engine, a transmission or a hydraulic backhoe. The off-highway market is now looking at ways to improve productivity using advanced tools and methods. The tools available to the off-highway industry were first used by aerospace companies ten years ago. The automotive industry has just started to adopt these methods and the off-highway industry seems to be close behind.

Original equipment manufacturer's (OEM's) core competence is satisfying the needs of the end user. Supplier's core competence is satisfying OEM's and optimizing their area of expertise. Combining forces on projects creates synergies to produce Drive Line System's technical and cost results that are unattainable independently by either. State of the art examples include integration of multiple machine function and electronics to create interactive systems and redesign existing power trains to optimize functionality and to downsize the system. Close cooperation and excellent communication between the OEM and supplier is essential for project success.

This paper explores the history behind the use of fine filters on off-road transmissions, the evolution of coreless filter technology, and the introduction of new coreless filters suitable for high temperature powershift transmissions.

The Chain-Wave Transmission (CWT) is a new type of harmonic drives, which was created at the Armenian Agricultural Academy. In the paper is considered the motion of elements and are constructed motion trajectories of the chain's rollers center at various values of the waves number and multiplicity factor of the CWT. There are received also expressions for determination of displacements, speeds and accelerations of the chain's rollers center depending on rotation angle of the waves generator, is given their analysis and on their basis are specified the basic parameters of the CWT.

Hydrostatic drives offer many advantages in certain vehicle applications. In zero-turn-radius vehicles, advantages such as infinitely variable transmission, high torque transfer, transmission responsiveness, and non-clutching direction reversing make this system the transmission of choice. Currently, most hydrostatic transmissions use mechanical linkages to set the displacement of the hydrostatic pumps. The use of non-linear linkage connections and mechanical damping are used to give the required vehicle drive feel. The use of electrical actuators on hydrostatic pumps along with minimal use of sensors allows the design engineer to replace the conventional mechanical linkages on hydrostatic drive vehicles. In some instances the cost savings gained with the removal of the linkages offset the cost of the electronic circuitry, actuators and sensors.