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Energy efficiency of agricultural tyres: Proposal for a standard test

Energy efficiency of agricultural tyres: Proposal for a standard test. Content. 1) Estimated impact of pneumatic tyres on tractor fuel consumption 2) Proposed test protocol 2.1) Necessity to remain simple 2.2) Mechanical conditions applied to the tyres, during the proposed test

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Energy efficiency of agricultural tyres: Proposal for a standard test

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  1. Energy efficiency of agricultural tyres: Proposal for a standard test

  2. Content 1) Estimated impact of pneumatic tyres on tractor fuel consumption 2) Proposed test protocol 2.1) Necessity to remain simple 2.2) Mechanical conditions applied to the tyres, during the proposed test 2.3) Soil conditions 2.4) Measured signals and testing devices 2.5) Specifications for the experimental test centres 3) Utilization of the standard test results by the farmers

  3. Content 1) Estimated impact of pneumatic tyres on tractor fuel consumption 2) Proposed test protocol 2.1) Necessity to remain simple 2.2) Mechanical conditions applied to the tyres, during the proposed test 2.3) Soil conditions 2.4) Measured signals and testing devices 2.5) Specifications for the experimental test centres 3) Utilization of the standard test results by the farmers

  4. Experiments on soft soil (field) • Test method: • Presented by Michelin at AgEng conference Hanover 11/2009 • Steady state pulling in a flat field • « iso service » : Stabilized speed. • Statistical significant difference : 1.8L.H-1 (1%) • Design of Experiment: • Tractor maximum PTO power = 132kW • Comparison of tyres “480” and “VF650” (etc…) • Front and rear tyres changed on the tested tractor • Soil: 64% sand, 26% loam, 10% clay ; moisture content = 23% • Measured results: • Unit : L.H-1. ; Can be converted in L.(hectare)-1. Test Configuration Service Fxdrawbar = 30000 Nground speed = 2m.s-1. Maize stubble (CI=0.5MPa) Tilled soil (CI=0.1MPa) 27.3 L.H-1 32.5 L.H-1 Tyre "480" -10% -14% Tyre "VF650" 24.7 L.H-1 27.8 L.H-1 In average : -12% (with respective rated inflation pressures)

  5. Experiments on hard soil (road) • Test method: • Presented by Michelin at AgEng conference Hanover 11/2009 • Steady state driving on a flat track • « iso service » : Stabilized speed (39 km.H-1). • Statistical significant difference : 0,3L.H-1 (1%) • Design of Experiment: • Tractor maximum PTO power = 80kW • Comparison of tyres (A and B) • Only the rear tyres of the tractor were changed ( ) • Measured results: • Unit : L.H-1. ; Can be converted in L.(100km)-1. Test Configuration Tractor alone With loaded trailor Service Fxdrawbar = 0.0 Nground speed = 39 km.h-1. Fxdrawbar = 1000 Nground speed = 39 km.h-1. 13.2 L.H-1 16.5 L.H-1 Tyre A Tyre B 12.7 L.H-1 15.6 L.H-1 In average : -5% (rear tyres only ; realistic prototypes) The fuel consumption reduction is likely to be larger, in case all tyres would be improved, instead of only the rear tyres of the tractor.

  6. Content 1) Estimated impact of pneumatic tyres on tractorfuel consumption 2) Proposed test protocol 2.1) Necessity to remain simple 2.2) Mechanical conditions applied to the tyres, during the proposed test 2.3) Soil conditions 2.4) Measured signals and testing devices 2.5) Specifications for the experimental test centres 3) Utilization of the standard test results by the farmers

  7. 2.1) Proposed test protocol: Necessity to remain simple… • The reality: • An infinite variety of usages conditions • The test: • "If only a very limited number of usage conditions had to be used in a standard test, what should they be? • Simplification… but virtuous for the tyre industry.

  8. 2.2) Proposed test protocol: Mechanical conditions applied • "Pull" • Net Traction = 0.4  Weight • 2 m.s-1; soft soil • "Carry" • Net Traction = 0 (but still an energy consumption…) • 2 m.s-1; soft soil • "Transport" • Free rolling • Constant speed 40 km.h-1; hard and horizontal soil

  9. Content 1) Estimated impact of pneumatic tyres on tractor fuel consumption 2) Proposed test protocol 2.1) Necessity to remain simple 2.2) Mechanical conditions applied to the tyres, during the proposed test 2.3) Soil conditions 2.4) Measured signals and testing devices 2.5) Specifications for the experimental test centres 3) Utilization of the standard test results by the farmers

  10. 2.3) Proposed test protocol / Soft soil. • "Pull" and "Carry" usages are concerned • Suggested approach : a unique type of soil • It is expected that several fields comply with the targeted type of soil • Targeted characteristics: • Moisture Content (mass based): MC = 25% • Soil strength: classical Cone Index CI0-0.15 = 0.7 MPa. • Texture (= granulometry) • Soil with no natural cover • Some tolerances about the targeted characteristics are proposed

  11. 2.3) Proposed test protocol / Hard soil. • Transport usage is concerned • Experience from passenger car and truck industry: • use of a drum machine • Measurement of the "tyre rolling resistance"

  12. Content 1) Estimated impact of pneumatic tyres on tractor fuel consumption 2) Proposed test protocol 2.1) Necessity to remain simple 2.2) Mechanical conditions applied to the tyres, during the proposed test 2.3) Soil conditions 2.4) Measured signals and testing devices 2.5) Specifications for the experimental test centres 3) Utilization of the standard test results by the farmers

  13. 2.4) Proposed test protocol / Measured signal and testing devices • Generally speaking: • No "fuel" consumption measured • Risk analysis if fuel consumption was measured = • Impact of motorization, transmission • Objective = to improve the tyres, not the vehicle for the test • If "fixed", unique tractor: - maintenance? - long term relevance? • Measure the mechanical efficiency instead.

  14. Proposed test protocol / Measured signal and testing devices • "Pull" usage: • Proposed net traction ratio = 0.4 • Quite realistic and common • A good balance between tractive efficiency (TE) and productivity. • Performance index • TE is a well known index : • Our purpose: Consider a common service (output power) for all tyres of a category • Suggested index • homogenous with other two indices • "the smaller, the better" • Numerical example : (TE = 75% => pull_index = 33%) TE Pull_index 0 0.4 NT/W Definitions of TE, NT, V, T,  : See [ASABE S296.5]

  15. Proposed test protocol / Measured signal and testing devices • "Carry" usage: • Proposed performance index: • The "output power" becomes difficult to define => notion of service:Transported mass  distance run • Depart from TE; go to • Homogenous with other 2 indices • Numerical example: carry_index = 12%

  16. Proposed test protocol / Measured signal and testing devices • Testing device for "pull" and "carry" usages: • Measured signals: • V : Travel speed (travel velocity) m.s-1 • W : Applied load on the tyre N • T : Driving torque (at wheel hub) N.m • NT : Net traction (at wheel hub) N •  : wheel hub rotation speed rad.s-1 • Necessity of an instrumented hub : • On tractor? • On "single wheel testers" • (Used in agricultural fields)

  17. Proposed test protocol / Measured signal and testing devices • "Transport" usage: • On road: • Some measurements are possible • Measurement accuracy may be insufficient • Availability of a good road ; traffic issue… • Wind ; slopes… • Small forces involved. • Suggested device: • Drum machines • Deceleration tests • Use existing calculation procedures • Typical test results: • "transport_index" = CRR = 0.017 = 1.7% = 17 kg/T • CRR less than 10 kg/T for passenger car and truck tyres. Definition of CRR : Coefficient of Tyre Rolling Resistance (=RR force / weigth).

  18. Content 1) Estimated impact of pneumatic tyres on tractor fuel consumption 2) Proposed test protocol 2.1) Necessity to remain simple 2.2) Mechanical conditions applied to the tyres, during the proposed test 2.3) Soil conditions 2.4) Measured signals and testing devices 2.5) Specifications for the experimental test centres 3) Utilization of the standard test results by the farmers

  19. 2.5) Specifications for the experimental test centres • "Pull" and "carry" usage: • Open agricultural field • Homologated testing device with measuring hub • For example : "Single wheel tester" • "Transport" usage: • Drum machine • The drum diameter and load capacity of the machine should comply with agricultural tyres.

  20. Content 1) Estimated impact of pneumatic tyres on tractor fuel consumption 2) Proposed test protocol 2.1) Necessity to remain simple 2.2) Mechanical conditions applied to the tyres, during the proposed test 2.3) Soil conditions 2.4) Measured signals and testing devices 2.5) Specifications for the experimental test centres 3) Utilization of the standard test results by the farmers

  21. 3) Utilization of the standard test results by the farmers • Homogeneity of the 3 performance indices • Why not use the ratio for all 3 indices? • Example for a given tyre: • Indexpull = 33%; Indexcarry = 12%; Indextransport = 1.6% • Possibility of some graphical representations? • Use of the indices: • Hand made calculation by the Farmers • Use of simulation softwares (account for usages' probabilities…) pull pull_index carry_index transport_index carry transport

  22. Thank you for your attention

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