Throughout 2008, OEM Off-Highway's Fluid Power Series has traveled through the mobile hydraulic system. In the March issue, the hydraulic system was described as a team that requires all members to be on the field in order to achieve success. Fortunately, from a safety standpoint, the team isn't a self-starter. Nothing happens with the cylinder, pump, or motor until it receives an input from the coach in command of the machine. Today, thanks to electronic control technology, communicating with the hydraulics team has never been easier or more effective.
"Electronic components themselves are generally more environmentally hardened than they were 10 years ago," says Dan Ricklefs, product portfolio manager - controls, Sauer-Danfoss, Ames, IA, "but more importantly, systems are being designed in a manner that is simply more robust. Control schemes that address error detection, proactive fault handling, and general machine safety are better understood and more widely employed. Advances in products like graphical displays can now provide significantly more system information to the operator, making the electronic control system less of a 'black box' and more of a benefit to getting the job done. All these advances help instill confidence in electronic control solutions."
Not only has the technology itself evolved, but so has the customer's acceptance and expectation of electronic content inside an off-highway machine.
"From a demographic point of view, most of the end users and engineers coming into the workforce today have never really known a time without electronics," says Joe Maher, vice president business and product development, Hydro Electronic Devices (HED) Inc., Hartford, WI. "In the past, people were skeptical, and that evolved into acceptance. Now customers expect to have it, and engineers expect to design it into a machine system."
Today, the demand for electronic controls in all areas of the machine — not just hydraulics — has a pull-through effect on sales. Getting the word out no longer involves the "missionary selling of electronics," says Maher. "It is a fun time to be in electronics, I can tell you that."
Technology has improved. "I often compare the evolution that we are going through in our market with what happened in the automotive industry more than 20 years ago," says Maher. "Back then, when you bought a car, you wanted to avoid one with a lot of electronics because you didn't understand or trust them. Today, in most cases, you wouldn't want one without the luxury, safety, and economy features that can only be achieved physically or economically with electronics."
It is the system, not just the electronic components themselves, that has improved. "There is certainly more trust than in the past," says Terry Hershberger, applications engineering manager, Bosch Rexroth Mobile Hydraulics, Wooster, OH. "In addition, the proven reliability of the electronics that are on machines today, and the ability to troubleshoot with the available tools, have bolstered the confidence factor.
"Another major development that has increased confidence is that wiring harnesses are understood to be an important component in the design of the machine. In many cases it was not the electronics failing, but the wire harness. That is an important point in any discussion on trust of the system."
Art Donaldson, systems engineering manager — North America Mobile Systems for Parker Hannifin, says the biggest change over the past decade is that the industry is "using electronics truly designed for mobile applications. In the past, OEMs were forced to use electronics designed for industrial applications and modified for the mobile world. Today, our electronics are designed from the ground up as mobile components and systems. This provides OEMs and end users with reliable electronics that address the specific requirements of mobile control systems. This was driven by the need for a level of control that can only be obtained with electronics."
"A load-sense and a piston pump have physical limitations if the controls are exclusively hydraulic," says Donaldson. "By adding electronics, however, it's possible to have displacement control of the pump when the operator activates a joystick. With such a control scheme, the pump strokes in anticipation of the request from the valve, giving the operator a far more responsive system. What we are seeing overall is electronics moving into all aspects of the system — from complete control of a vehicle system, down to intelligent valves or pumps."
Founded by Charles Arens in 1939, Arens Controls Co. LLC quickly became a respected supplier of control systems for everything from submarines to farm equipment. As designs evolved to include by-wire technology, Arens' controls became increasingly more sophisticated. The company provides electronic solutions for communication with hydraulic systems, engines and transmissions, and counts the largest OEMs and suppliers in the business among its customers.
"We started seeing electronic controls 15 years ago on farm tractors," says James Hoadley, vice-president, sales and marketing, Arens. "Electronic content continues to increase. We are also seeing a greater demand for precision controls, and electronics are the way to achieve that. You can only feather a mechanical cable so much."
Electronics for mobile equipment has evolved in many of the same ways consumer electronics have changed. "Today's products have significantly more processing power and more memory," says Ricklefs. "We applied CAN bus communication systems in some applications 10 years ago. Today, virtually every controller we produce has a CAN port. We've benefited from similar trends in the automotive industry, making components to implement these features readily available and affordable."
Elobau Sensor Technology Inc. offers a range of non-contact sensors, joysticks and switches. Francois Mortier, general manager for the firm's North American office in Lake Bluff, IL, says some of the common requests from customers include longer component life, system integration (complete solutions, with controls mounted, tested and delivered ready to go), sensor reliability and redundancy, and the specific shape, texture and color of the switches and joysticks themselves.
He cautions that while sensor technology and electronics in general may have come a long way, the mechanical components of items such as joysticks cannot be overlooked. "You can't place a Hall effect sensor in a poor design. The design of the joystick's internal components are still important. We could make the parts out of lighter material, but they wouldn't last in an off-highway environment."
Hoadley says that in many cases some intangibles came in to play, too. "That control becomes the customer's link — visually and operationally — to a major component that is deep inside the machine. This increases the demand on the supply base to develop a robust, reliable, smooth operation in the control because that relates directly to the perception of value to the component to which it is connected.
"We understand that a significant part of our assignment is to craft controls that not only deliver reliability but also have the look, feel and sound that exemplifies high quality."
New controllers offer higher speeds, increased safety
Electronic controls have increased the ability to ensure the safety of the operator as well as the machine itself, helping to prevent accidents and expensive downtime.
Eaton Corp. recently introduced two new, high-performance controllers to its F(x) electrohydraulic product portfolio. The new SFX 1000 and SFX 2000 controllers offer higher operating speeds than Eaton's EFX controllers, and meet Safety Integrity Level (SIL) 2 and 3 requirements of the off-highway industry.
"These new controllers are specifically designed for applications where control loop times are critical," says Eaton's A.J. Smith, marketing manager - strategic programs, Eden Prairie, MN. "In addition, both the SFX 1000 and SFX 2000 controllers have an internal Freescale HC 908 'watchdog CPU' and monitoring software that allows them to comply with the IEC 61508 safety standard. When used as stand-alone controllers they meet SIL 2 requirements for off-highway vehicle applications."
"The SFX 2000 has an additional TTP (time triggered protocol) controller that enables deterministic network bus communications," Smith says. "With this capability, a customer can network two SFX 2000 controllers together in an electrohydraulic application and achieve SIL 3 certification. SIL 3 is important because new technologies that have a higher degree of risk like steer-by-wire will want to achieve SIL 3 compliance."
CC Systems AB
High Country Tek
Hydro Electric Devices
J.R. Merritt Controls Inc.
TSD Integrated Controls