1 year ago

MDA Technologies 2/2014

MDA Technologies 2/2014

Measurement and Control

Measurement and Control Hitch control for use in emerging countries external gear pump control panel angle sensor Thierry Dumont Flexibility and productivity are qualities ready to be harvested for agriculture. Two additional aspects are efficiency and comfort. The Electrohydraulic Hitch Control meets these two requirements very well — also for use in emerging countries. controller force sensor Outlet Continuous advancements make working in the fields more comfortable today. The technology also saves fuel and reduces wear. Bosch Rexroth brought the first systems to market 30 years ago – and has now brought a solution tailored to use in emerging countries to production readiness together with an Indian tractor manufacturer. The established Electrohydraulic Hitch Control (EHC) demonstrates the fast pace of development in agricultural technology. It is used to set the height of agricultural implements. In the past, the farmer had to turn around in his seat while driving in order to control the depth of the plow by means of levers on the hydraulic valves. Today, thanks to the integration of control technology, the farmer can keep his eyes and hands forward. The mechatronic system equipped with control technology controls, among other things, the ratio between the position of the agricultural implement and the draft force by means of software. The farmer enters the basic data from his experience; the only things remaining are electronic comparisons between target value and actual value. The EHC Thierry Dumont, Mobile Electronics Sales and Product Management, Bosch Rexroth AG, Lohr, Germany from Bosch Rexroth continuously adjusts the depth of the implements in the soil by means of the hydraulic pressure at the hitch. Fast compensation of resistances is necessary so that soil of different hardness can be compensated by means of the working depth. Before the advent of electronics, the farmer had to continually look back while driving to ensure that the plow was optimally positioned and did not bounce due to excessive pressure. This added comfort was formerly reserved for the larger tractor classes. With the EHC-8, Bosch Rexroth has now developed an Electrohydraulic Hitch Control tailored to the power class up to 80 HP. This segment comprises about two thirds of all tractors produced worldwide. The EHC is especially intended to meet the requirements for economy, functionality, and robustness in emerging countries. Therefore, this new system for greater productivity, safety, and ease of use was developed by Bosch Rexroth in close cooperation with a leading Indian tractor manufacturer. The core of the collaboration was to adapt or redevelop the electronic and hydraulic components of the EHC-8 system solution in line with the local requirements. This includes the control valve, controller, angular and draft sensors, and control panel. The resulting system now automatically controls the preset working depth without driver intervention. The greater accuracy even enables soil cultivation at shallow depths, which is not possible with a wear-prone mechanical control. The EHC-8 will be introduced into the series production of Indian tractors in 2014. Robust construction outside the cab In order for this technology to be able to operate with high availability in emerging countries, it has to be noted that the 80 HP class in India is generally built without a comfortable cab. Therefore, the protection against rain and dust provided by a cab is not available for the installed controls. So Bosch Rexroth developed a control panel 01 The electronic and hydraulic components of the EHC-8 system solution, such as the controller, were brought in line with the local requirements 46 MDA Technologies 2/2014

Measurement and Control increased demand for comfort in the field. “Young farmers in particular no longer want to do without the resulting quality of life. But it‘s also about saving time and working efficiently.” Modern tractors in the lower power classes are much easier on the back during driving than tractors of the past and have technology “that goes beyond the automobile standard,” describes the son of the boss of the family-operated agricultural equipment company. “The development in agriculture over the last 30 years has been really extreme.” Demand for adapted systems 02 Protected against dirt, the newly developed, robust control panel (right) is installed in the armrest in tractors without a cab that is integrated into the armrest of the seat in the first series application. The driver operates the system with one hand by means of a few robust knobs. This means that the driver can concentrate on driving and no longer has to readjust the implements while turned backwards. In addition, the draft sensor of the top link control is attached so high that it is protected from water even during work in rice fields. European market profits from joint development For a global standpoint, the European market will also profit from this joint German-Indian development. The EHC-8 is designed for agriculture in emerging nations, but it still offers advantages that are extremely interesting for the small-tractor market. Because the heavy implements move the center of gravity far back when used with lightweight tractors of the 80 HP class, there are times when the driver can no longer steer his vehicle outside of the field – especially when there are poor road conditions. Thanks to integrated vibration damping, the EHC-8 actively prevents the well-known bouncing and thus improves driving safety in critical situations. Automatic adjustment gains ground Real savings – especially fuel savings – are an additional advantage of electronic control. If the draft load exceeds the optimal load due to different soil qualities, the wheels inevitably slip. The slippage causes the diesel consumption to increase proportionally and reduces the service life of the tires due to wear. And slippage has a negative ecological effect, because it compresses the Global trend: manufacturers are transferring functions that were used primarily in the upper power segment to the middle and lower segments soil and destroys the capillaries and thus the microcosm. In view of these advantages, Sebastian Steinbrink expects that systems such as the EHC-8 will become more and more established in small tractors. In connection with this, the master mechanic for agricultural machinery from the village of Bremke in Lower Saxony also speaks of a significantly In view of complex areas of application with their large regional differences in usage, Bosch Rexroth has used a modular design for the performance and range of functionality of the EHC. The range of solutions begins with the Automatic Hitch Control (AHC) for dynamic control between position and draft force. The advanced Pressure Relief Control (PRC) compensates for the ground contour for front hitches of large tractors, which protects material and soil during the mowing of grass or increases the controllability and thus the safety of a snowplow, for example. Finally, with the Hitch Lowering Support (HLS), hitches can be detached from the connected implements better from the perspective of ergonomics and quick changeovers thanks to active pressure build-up – an advantage particularly in the event of jammed connections and cold weather. About Company name: Bosch Rexroth Headquarters: Lohr, Germany Turnover: 52.5 bn € Employees: approx. 306.000 worldwide Products: Drive Technology, Electric Drives and Controls, Gear Technology, Industrial and Mobile Hydraulics, Pneumatics, Assembly Technology, Linear Motion Technology This Article is a contribution by MDA Technologies 2/2014 47


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