WO2011067525A1

WO2011067525A1 - Method for determining the energy consumption of a lubricating oil of an internal combustion engine

Info

Publication number: WO2011067525A1
Application number: PCT/FR2010/052557
Authority: WO
Inventors: Maxime Jullian; Mohammed El Bouchehati
Original assignee: Peugeot Citroën Automobiles SA
Priority date: 2009-12-04
Filing date: 2010-11-29
Publication date: 2011-06-09
Also published as: FR2953600A1; FR2953600B1

Abstract

The invention relates to a method for determining the energy consumption of a lubricating oil of an engine, for a predetermined dynamic operating cycle of the engine relative to a reference oil, said method being characterised in that the method includes the steps consisting of: determining a descriptor of the predetermined dynamic cycle; choosing a selection of operating points of the descriptor; testing the engine at the selected points a first time using the reference oil, a second time using the oil to be assessed and a third time using the reference oil, and measuring an output parameter of the engine each time; determining a first energy consumption according to the measurements of the output parameter obtained during the first and/or third test and a second energy consumption according to the measurements of the output parameter obtained during the second test; and determining the difference between the first and second energy consumptions.

Description

Method for determining the energy consumption of a lubricating oil of an internal combustion engine

Technical field of the invention

The present invention claims the priority of the French application 0958650 filed on December 04, 2009 whose content (text, drawings and claims) is hereby incorporated by reference.

The present invention relates to the determination of the portion of energy consumed by friction by a lubricating oil of an internal combustion engine in relation to a reference oil.

Technological background

The automotive industries are currently facing the major challenge of reducing the greenhouse effect due to the presence of greenhouse pollutants in the atmosphere. In addition, the tax incentives and European standards currently known as Euro V relating to the levels of pollutant emissions generated by the operation of internal combustion engines require manufacturers to apply innovative solutions to reduce vehicle emissions, especially in C0 _2. . To meet this challenge, one of the most effective ways is to reduce the fuel consumption of powertrains.

One approach to reduce this consumption is to optimize the engine lubricating oil to reduce energy losses by friction.

In order to quantify the effect of a lubricating oil of an internal combustion engine on the fuel consumption, it is known to use methods of measuring the consumption gain related to the use of an engine lubricant. Like the CEC L-54-T-96 standard engine test methodology, also called "M1 1 1 fuel economy", these methods are based on tests carried out on a predetermined dynamic cycle, ie ie comprising a succession of regime change and / or engine load over a given period of time, and generally involve a comparison between test results obtained with an oil to be evaluated and test results obtained on the same predetermined cycle with a reference oil. These dynamic cycle tests can be performed on a test bench receiving either the engine alone or a vehicle comprising the engine. However, these methods have the following drawbacks: they give consumption gain results dispersed from one test to another and therefore have a large measurement uncertainty. Moreover, these tests are not representative of homologation cycles, such as the MVEG cycle in Europe, of vehicles.

The invention therefore aims to overcome the drawback of the prior art by proposing a new method for quantifying the energy consumption of a lubricating oil of an internal combustion engine relative to a reference oil. The invention therefore relates to a method for determining the energy consumption of a lubricating oil of an internal combustion engine, said oil being evaluated for a predetermined dynamic cycle of operation of the engine relative to a reference lubricating oil. said method being characterized in that it comprises the steps of:

-Determining a descriptor of the evolution of a set of engine operating parameters during the predetermined dynamic cycle,

-Choose a selection of operating points of the descriptor,

-First run the engine at the test bench at the selected operating points, the engine including the reference lubricating oil, and for each of the selected operating points, measure an engine output parameter when operation is stabilized, - Pass the engine to the test bench a second time at the selected operating points, the engine including the lubricating oil to be evaluated, and for each of the selected operating points, measure the output parameter when said operating point is stabilized,

-Pull a third time the engine to the test bench at the selected operating points, the engine including the reference lubricating oil, and for each of the selected operating points, measure the output parameter when said operating point is stabilized,

-Determine a first energy consumption of the engine with the reference lubricating oil from measurements of the output parameter obtained during the first and / or third test bench run.

-Determine a second energy consumption of the engine with the lubricating oil to be evaluated from the measurements of the output parameter obtained during the second pass to the test bench.

-Determine the variation of energy consumption from the difference between the first and second energy consumption. In addition, the invention may include one or more of the following features:

Preferably, the set of operating parameters of the descriptor comprises at least one engine speed, one engine oil temperature.

Preferably, the method of the invention comprises a step of determining a measurement uncertainty of the first power consumption. The uncertainty of the measurements obtained by the process of the invention is improved compared with the prior art.

According to one variant, the engine is driven to the test bench.

Preferably, the output parameter of the motor is the resistive torque or the PMF. According to another variant the engine is passed to the test bench in combustion.

Preferably the operating parameter set of the descriptor further comprises a motor torque. Preferably, the output parameter of the engine is the fuel consumption.

Preferably, the method comprises a step of weighting the fuel consumption measurements. By this means, the method has the advantage of being applicable over the entire vehicle range using the engine chosen during the tests, vis-à-vis a predetermined dynamic cycle such as an approval cycle.

Preferably, the steps of determining the first and second energy consumptions each comprise a step of reconstructing the output parameter over the range of the predetermined dynamic cycle descriptor from the measurements of said output parameter carried out on the test bench on the selected operating points.

Preferably, the reconstruction step comprises determining the output parameter on the descriptor extent by extrapolation and / or interpolation of the measurements of said output parameter obtained on the test bench on the selected operating points. Brief description of the drawings

Other features and advantages will appear on reading the following description of a particular embodiment, not limiting of the invention, with reference to the figures in which:

- Figure 1 is a schematic representation of the steps of the method of the invention, according to a first variant made on the basis of engine driven tests.

FIG. 2 is a schematic representation of the steps of the method of the invention, according to a second variant, carried out on the basis of combustion engine tests.

detailed description

We now describe a first embodiment of the method of the invention for determining the energy consumption, more particularly by friction, of a lubricating oil of an internal combustion engine relative to a reference lubricating oil, on a predetermined driving cycle.

By predetermined driving cycle is meant here a dynamic operating cycle of the engine such as an approval cycle. For example, in the context of the approval of passenger cars and light commercial vehicles in Europe, the predetermined driving cycle is the MVEG (for Motor Vehicle Emissions Group) cycle. This test cycle is performed with a cold engine start and includes an urban cycle (ECE, for Economy Commission of Europe) consisting of four cycles (UDC, for Urban Driving Cycle) identical successive of a duration of 195 seconds each. The urban cycle is completed by an extra-urban cycle (EUDC, for Extra Urban Driving Cycle) lasting 400 seconds and comprising a driving phase up to 120 km / h. During this dynamic cycle, the engine conditions in water temperature, oil temperature are obviously not stabilized and the engine speed is variable. In the remainder of the description of this memo, we will take the MVEG European cycle as an example of a driving cycle, nevertheless the method of the invention is suitable for any other dynamic operating cycle, such as the US cycle.

This first embodiment is carried out according to the following main steps shown diagrammatically in FIG. Step 1 concerns the determination of a descriptor of the evolution of a set of engine operating parameters during the MVEG cycle. By cycle descriptor, here is meant a record of this evolution of the engine operating parameters during the predetermined dynamic cycle, in other words as a function of time. This recording can be performed beforehand during a combustion test of the engine on the predetermined dynamic cycle, the MVEG cycle in our example. The cycle descriptor can also be a numerical simulation of said set of engine operating parameters on the dynamic cycle as a function of time. Preferably, the set of operating parameters of the engine comprises at least one engine speed N, a temperature T _h of engine oil, and possibly a temperature T _e of engine water. Thus, this cycle descriptor can be in the form of a table or a computer file for which at each moment t of the MVEG cycle corresponds a regime N, a temperature T _h of engine oil, a temperature T _e of water engine. The descriptor is independent of the lubricating oil used because it is reasonable to assume that the evolution of the engine oil temperature T _h is decorrelated from the oil used.

Step 2 consists in selecting a selection of operating points of the MVEG cycle descriptor, a motor operating point being defined by the values of the set of operating parameters N, T _h , of the engine at a given instant t MVEG cycle.

This first embodiment of the method of the invention is based on results of tests carried out on the selected operating points and carried out on a test bench under stabilized conditions, that is to say for N, T _h constant, on an internal combustion engine arranged on an engine test bench with electric generator. The engine is in this first embodiment driven by the electric generator. In this first embodiment, the engine is not in combustion and therefore does not provide heat for heating the oil and water. The regulation of the oil temperature T _h and the water temperature T _e is therefore achieved by complementary heating or cooling circuits well known to the engine benches.

The rest of the procedure is as follows:

Step 3 is to first pass the engine to the test stand at the selected operating points, the engine including the reference lubricating oil. For each of the selected operating points, an operating output parameter of the motor is measured when said operating point is stabilized. Preferably, in this first embodiment, the measured output parameter is the resistive torque C _r .

Step 4 consists of passing the engine a second time on the test bench at the selected operating points, the engine having been rinsed with the reference oil and this time including the lubricating oil to be evaluated. For each of the selected operating points, when the operating point is stabilized, the resistive torque C _r is measured. Step 5 is to resume step 3 that is to say to pass a third time the engine to the test bench on the selected operating points, the engine having been rinsed with the oil to be evaluated and comprising again the reference oil. For each of the selected operating points, when the operating point is stabilized, the resistive torque C _r is measured. Thus if at this step 5 the resistant torque measurements C _r are consistent with those of step 3, it is ensured that there has been no drift between steps 3 to 5, which makes it possible to validate the results. of resistance torque measurements C _r for step 4. If there is a drift, this can be taken into account in the evaluation of the uncertainty of the measurement, which can be expressed in uncertainty on the gain in final consumption.

At this level of the procedure we therefore know the resistive torque C _r for all the selected operating points of the MVEG cycle, this for each of the passes to the test bench of the engine. Step 6 then consists in reconstructing, for each of the passes on the engine test stand, the resistive torque C _r on all the operating points of the MVEG cycle descriptor. For each of the passes to the engine test stand, the resistive torque C _r is reconstructed over the range of the MVEG cycle from the resistant torque measurements C _r carried out on the test bench at the selected operating points. Preferably, the reconstruction is advantageously performed by interpolation and / or extrapolation of the resistant torque measurements C _r obtained on the test bench at the selected operating points.

At this level of the procedure we therefore know the resistive torque C _r for the entire cycle MVEG, this for each of the passes to the test bench of the engine. Step 7 then consists in determining on the one hand a first energy consumption of the engine with the reference lubricating oil from the measurements of the resistant torque C _r obtained during the first and / or third pass on the test bench. tests (step 3 and / or step 5) and secondly a second energy consumption of the engine with the lubricating oil to be evaluated from the measurements of the resistant torque C _r obtained during the second test bench run. tests (step 4). In this first embodiment, the first and second energy consumption determined from the resistive torque C _r represent a dissipated energy E _d on the MVEG cycle, for each of the passes to the engine test stand. The dissipated energy E _d is obtained by integration as a function of time, over the extent of the MVEG cycle, of the dissipated power P:

And

PDC _r . (2)

30

With C _r the _load torque in Nm and the speed N in rpm.

Step 8 then consists in determining the variation in energy consumption from the difference between the first and second energy consumption, ie in our first embodiment of the method of the invention, from the difference DE _d between the dissipated energy E _d . _eva i on the MVEG cycle for the engine with the lubricating oil to be evaluated (step 4) and the dissipated energy E _d . _ref on the MVEG cycle for the engine with the reference lubricating oil (step 3 and / or step 5). Then, knowing the different engine efficiencies, the difference DE _d expressed in Joule is converted into an equivalent amount of fuel to give a G gain in fuel consumption. The conversion to CO ₂ emission is also possible via the fuel combustion equation.

In addition, this first embodiment of the method of the invention preferably comprises a step 9 of determining an uncertainty I of measuring the first energy consumption determined in step 7 from the tests carried out with the oil of reference to step 3 and / or step 5. The uncertainty I can for example be determined from the difference between the dissipated energy E _d . _ref on the MVEG cycle with the reference lubricating oil based on the first test bench test results (step 3) and the dissipated energy E _d . _ref on the MVEG cycle with the reference lubricating oil according to the test results of the third pass to the test bench (step 5). The uncertainty I can be, in the same way as for the gain G, expressed in another unit such as a quantity of fuel. This first embodiment of the method of the invention has the advantage of being able to discriminate the effect of the lubrication of a part of the engine, for example the distribution, on the gain in fuel consumption. Indeed tests can be made with parts of the engine removed to determine the resistant couples of each. This method allows to know the impact of the lubricant tested compared to a reference lubricant on a part of the engine during the driven engine tests.

This first embodiment of the method of the invention has been presented with a resistant torque measurement C _r . More preferably, for this first embodiment, the parameter measured for steps 3, 4 and 5 can be PMF (Mean Friction Pressure), which can be measured with one or more cylinder pressure sensors, which can then be measured deduce a power dissipated by the friction and therefore the energy E dissipated on the MVEG cycle.

We now describe a second embodiment of the method of the invention for determining the energy consumption of a lubricating oil of an internal combustion engine relative to a reference lubricating oil, on a MVEG cycle.

The main steps of this second embodiment are shown schematically in FIG. 2. The procedure is in this case the following:

Step 1 'is substantially identical to step 1 of the first embodiment of the method of the invention and therefore relates to the determination of a descriptor of the evolution of a set of operating parameters of the engine during the MVEG cycle. Preferably, the set of operating parameters of the engine comprises at least one engine speed N, a temperature T _h of engine oil, a driving torque C _m and possibly a temperature T _e of engine water. Thus, this descriptor may be in the form of a table or a computer file for which at each moment t of the predetermined dynamic cycle corresponds a regime N, a temperature T _h of engine oil, a torque C _m engine. Step 2 'is identical to step 2 of the first embodiment of the method of the invention and therefore consists in choosing a selection of operating points of the MVEG cycle descriptor. This second embodiment of the method of the invention is based on test results carried out on the operating points selected and made under stabilized conditions, that is to say for N, T _h , and T _e and C _m constant, the internal combustion engine being disposed on an engine test bench, the engine being in this second embodiment in combustion. In this second embodiment, the engine provides heat for heating the oil and water, however, the regulation of the oil temperature T _h and the water temperature T _e can be supplemented by additional heating or cooling circuits well known to the engine benches.

The rest of the procedure is as follows:

Step 10 is to first pass the engine to the test stand at the selected operating points, the engine including the reference lubricating oil. For each of the selected operating points, a motor output parameter is measured when said operating point is stabilized. Preferably, for this second embodiment, the engine operating output parameter measured is the fuel consumption C _c .

Step 1 1 consists of passing the engine a second time to the test bench at the selected operating points, the engine having been rinsed with the reference oil and this time including the lubricating oil to be evaluated. For each of the selected operating points, when the operating point is stabilized, the fuel consumption C _c is measured.

Step 12 is to resume step 10, that is to say to pass a third time the engine to the test bench on the selected operating points, the engine having been rinsed with the oil to be evaluated and comprising again the reference lubricating oil. For each of the selected operating points, when the operating point is stabilized, the fuel consumption C _c is measured. Thus, it is ensured that there has been no drift between steps 10 to 12, which makes it possible to validate the results of fuel consumption measurements. In addition, this helps to evaluate the uncertainty of fuel consumption measurements. The results of fuel consumption measurements obtained in steps 10, 11, and 12 can be filtered to remove the aberrant fuel consumption measurements. At this level of the procedure we therefore know the fuel consumption C _c for the selection of operating points of the MVEG cycle, this for each of the passes to the test bench of the engine.

Engine tests on combustion test bench thus provide a basis for engine-specific fuel consumption measurements. However, at this level of the procedure the consumption measurements are not yet entirely representative of a given vehicle application, that is to say of the association of the engine in a given vehicle. Preferably, the method of the invention therefore comprises, in step 13, a weighting operation of the fuel consumption measurements for a given vehicle application. This weighting operation is carried out using a weighting matrix which, applied to the engine test results, makes it possible, according to the engine operating parameters, to correct the fuel consumption measurements obtained from the engine tests. 10.1, and 12. Thus a vehicle application is modeled by a weighting matrix and therefore the results of fuel consumption measurements obtained on a given engine during steps 10, 1 1, and 12 allows the determining the energy consumption of a lubricating oil for a plurality of vehicle applications without having to perform additional tests for each vehicle application. At this stage of the procedure, the weighting matrix specific to each vehicle application makes it possible to calculate from the measurements made during the engine tests, the consumption for each configuration for a given application.

Step 14 consists in reconstructing, for each of the passes on the engine test stand, the fuel consumption C _c on all the operating points of the MVEG cycle descriptor. For each of the passes to the engine test stand, the fuel consumption C _c is reconstructed over the range of the MVEG cycle from the resistant torque measurements C _r performed at the test bench on the selected operating points. Preferably, the reconstruction is advantageously carried out by interpolation and / or extrapolation of the fuel consumption measurements C _c obtained from the selected operating points. Step 15 then consists in determining on the one hand a first energy consumption of the engine with the reference lubricating oil from the fuel consumption measurements C _c obtained during the first and / or the third bench run. test (step 10 and / or step 12) and secondly a second energy consumption of the engine with the lubricating oil to be evaluated from the consumption measurements C _c obtained during the second test bench run. tests (step 1 1). In this second embodiment, the first and second energy consumptions represent total fuel consumption over the range of the MVEG cycle obtained by integration over time of the fuel consumption C _c reconstructed over the extent of the operating points. the descriptor of the MVEG cycle.

At this stage, the consumptions for each configuration are known.

Step 16 then consists in determining the variation in energy consumption from the difference between the first and second energy consumption, ie in this second embodiment of the method of the invention, from the difference between the total fuel consumption on the MVEG cycle for the engine with the lubricating oil to be evaluated (step 1 1) and the total fuel consumption on the MVEG cycle for the engine with the reference lubricating oil (step 10 and / or step 12). The variation in energy consumption can be negative if the oil to be evaluated generates more friction losses than the reference oil and can still be converted into a quantity of C0 ₂ .

In addition, this second embodiment of the method of the invention preferably comprises a step 9 'for determining an uncertainty I for measuring the first energy consumption determined in step 15 from the tests carried out with the oil reference in step 10 and / or step 12.

The two embodiments of the method of the invention are not limiting of the invention. Indeed, in a third embodiment, the energy consumption can be reconstructed on the basis of a combination of measurements resulting from the first two embodiments of the method of the invention.

An example of a combination can be to reconstruct the beginning of the MVEG cycle from the test results obtained according to the first embodiment, as a driven motor, and the end of the MVEG cycle from the results obtained according to the second mode, which is a motor. combustion. This combination is possible because, in fact, the engine is cold at the beginning of the MVEG cycle and hot at the end of the MVEG cycle.

Moreover, the application of the first two embodiments of the method of the invention makes it possible to obtain information on gains or losses of energy consumption related to the lubricant in a given thermal environment relative to a reference oil. Indeed, in the case for example of a gain, by subtracting the gains obtained combustion engine and gains obtained motor driven, one can go back to the gain or the loss related to the load and the engine thermal. In other words, this method makes it possible to decouple the part of the gain linked to the driven engine friction torque from the gain associated with the combustion engine friction. We can then determine the impact of combustion.

The method of the invention is original in that it is based on the principle of a reconstruction of the consumption gain of a given engine test plane and applied to an MVEG descriptor, that is to say a recording or simulation of the driving cycle as a function of time.

This process has many advantages:

First of all, it is quite representative of a driving cycle such as the MVEG cycle. It also makes it possible to improve the accuracy of the evaluation of the fuel consumption gain relative to a reference oil, which is of the order of 0.1 to 0.5% of C0 ₂ . It allows application flexibility with respect to the customer use profile: This method can be applied to any vehicle and any target use. This method is suitable for any type of driving cycle with a view, for example, of approval or customer gain. The method provides flexibility of application with respect to the lubricant. Indeed, it makes it possible to quantify the energy consumption relative to a reference oil of any oil, whether new or used.

It also allows the understanding of consumption gain phenomena. Indeed, this method method makes it possible to identify the operating zones where the lubricant brings a gain or not, and then makes it possible to understand and improve the lubricant accordingly: gains on the friction in hydrodynamic and elastomeric regime hydrodynamics related essentially to the viscosity as a function of temperature, shear and pressure and gains on friction in boundary or mixed zone essentially related to the addition of additives such as friction modifiers for example.

IL finally allows the simulation of the gains: the application of this process also makes it possible to simulate the gains related to the rheological properties of the lubricants (viscosity function of the temperature, the shear rate and the pressure, friction coefficients, ...) . The method applied here to the lubricant can also be applied to any component of a powertrain comprising a motor and a gearbox and allows, for example, the evaluation of the consumption gain potential of a component integrated in the group. Transmissions.

Claims

claims

1. A method of determining the energy consumption of a lubricating oil of an internal combustion engine, said oil being evaluated for a predetermined dynamic cycle of engine operation relative to a reference lubricating oil, said method being characterized by it includes the steps of:

-Choose a selection of operating points of the descriptor,

-Determine the variation of energy consumption from the difference between the first and second energy consumption.

2. Method according to claim 1, characterized in that the set of operating parameters of the descriptor comprises at least one engine speed (N), an engine oil temperature (T _h ).

3. Method according to claim 1 or claim 2, characterized in that it comprises a step of determining an uncertainty (I) for measuring the first power consumption.

4. Method according to any one of the preceding claims, characterized in that the engine is passed to the test bench driven.

5. Method according to claim 4, characterized in that the output parameter of the motor is the resistive torque (C _r ) or the PMF.

6. Method according to any one of claims 1 to 3, characterized in that the engine is passed to the test bench in combustion.

7. Method according to claim 6, characterized in that the operating parameter set of the descriptor further comprises a motor torque (C _m ).

8. Method according to claim 6 or claim 7, characterized in that the output parameter of the engine is the fuel consumption (C _c ).

9. Method according to any one of claims 6 to 8, characterized in that it comprises a step of weighting the fuel consumption measurements.

10. Method according to any one of claims 4 to 9, characterized in that the steps of determining the first and second energy consumption each comprise a step of reconstructing the output parameter on the range of the predetermined dynamic cycle descriptor from measurements of said output parameter made at the test stand on the selected operating points.

1 1. A method according to claim 10, characterized in that the step of reconstructing comprises determining the output parameter on the extent of the descriptor by extrapolation and / or interpolation of the measurements of said output parameter obtained at the test stand on the points of selected operation.