# Investigations of the Friction Losses of Different Engine Concepts. Part 1: A Combined Approach for Applying Subassembly-Resolved Friction Loss Analysis on a Modern Passenger-Car Diesel Engine

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## Abstract

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## 1. Introduction

_{2}emission limits from the legislative side, changing customer preferences (away from product towards function, e.g., car sharing and car rental) and a general focus on the environmental impact, it is nowadays crucial to develop highly efficient vehicles.

## 2. Friction Losses Analysing Procedure: A Combined Approach Using Experiments and Predictive Journal-Bearing Simulation

## 3. Experimental Investigation

#### 3.1. The Dynamometer

#### 3.2. The Engine under Test and Necessary Engine Preparations

#### 3.2.1. Engine Preparations for Additional Torque Measurements

#### 3.2.2. Engine Preparations for Crankshaft Seals Measurements

#### 3.2.3. Engine Preparations for Crankshaft Measurements

#### 3.3. Testing Procedure

#### 3.3.1. Measurement Program Base Engine

#### 3.3.2. Additional Measurements: Strip-Test Procedure

_{F Strip-Test 0}which represents the basis for the determination of the valve train friction losses using the combined approach (see Equation (2)). In the next strip-test, stage 1 torque measurements are conducted without the valve train and the upper timing drive resulting in friction torque T

_{F Strip-Test 1}. Equation (6) is used to calculate the resulting friction torque of the valve train and upper timing drive.

_{F Strip-Test 2}was measured in strip test stage 2. The friction torque of the crankshaft seals are the results of using Equation (7) by a subtraction of the measured torques of strip-test stage 1 and strip-test stage 2.

_{F Strip-Test 3}of the crankshaft main bearings solely was measured. The friction losses of the lower timing drive are calculated using Equation (8).

#### 3.4. Measurement Results

#### 3.4.1. Results Base Engine

#### 3.4.2. Results Strip-Tests

## 4. Journal-Bearing Friction Loss Simulation

#### 4.1. Simulation Results

#### Simulation Results: Supplementary Torque Measurement Configuration (Strip-Test Stage 0)

## 5. Applying the Combined Approach: A Subassembly-Resolved Friction Loss Distribution

#### 5.1. Resulting Valve Train Friction Losses Using the Combined Friction Analysis Approach

#### 5.2. Subassembly-Resolved Friction Loss Distribution for the Base Engine

## 6. Conclusions

## Author Contributions

## Acknowledgments

## Conflicts of Interest

## Appendix A

**Figure A5.**The equivalent temperature for the isothermal journal-bearing simulation for main bearing 1 and 3 calculated using Equation (11).

**Figure A6.**The resulting FMEP using the journal-bearing simulation method for main bearings and big-end bearings: lubricant supply temperature 70 ${}^{\circ}$C.

**Figure A7.**The resulting FMEP using the journal-bearing simulation method for main bearings and big-end bearings: lubricant supply temperature 110 ${}^{\circ}$C.

**Figure A8.**A comparison between the measurement and journal-bearing simulation for a lubricant supply temperature of 70 ${}^{\circ}$C and 110 ${}^{\circ}$C.

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**Figure 2.**A detailed procedure to determine the subassembly-related friction losses using the combined approach.

**Figure 3.**An overview of the experimental test setup for the analysis of the engine friction losses.

**Figure 4.**The mounted capacitive top dead center (TDC)-sensor and crank angle encoder during the TDC determination.

**Figure 7.**The measurement position of the main bearing temperatures: (

**left**) A sectional view of the measuring point at the main bearing shell. (

**right**) The mounted temperature sensors with cable guiding at the main bearing brackets 1, 2, and 3.

**Figure 8.**The deactivated fuel pump: (

**left**) The adapted fuel pump chain sprocket. (

**right**) The mounted fuel pump chain sprocket.

**Figure 10.**The sealing plug to prevent an oil leakage on the front-end auxiliary drive (FEAD) side of the engine.

**Figure 14.**The measurement campaign for the additional torque measurements to determine the frictional losses of the subassemblies.

**Figure 15.**The resulting friction mean effective pressure (FMEP) maps for different engine media supply temperatures: (

**left**) Supply temperature = 70 ${}^{\circ}$C. (

**middle**) Supply temperature = 90 ${}^{\circ}$C. (

**right**) Supply temperature = 110 ${}^{\circ}$C.

**Figure 16.**The friction reduction potential at the base engine when increasing the engine media supply temperature.

**Figure 17.**Measured main bearing temperatures: (

**left**) Main bearing 1. (

**middle**) Main bearing 2. (

**right**) Main bearing 3.

**Figure 18.**The resulting friction torque for different engine media supply temperatures: The valve train and upper timing drive using Equation (6).

**Figure 19.**The resulting friction torque for different engine media supply temperatures: The crankshaft seals.

**Figure 20.**The resulting friction torque for different engine media supply temperatures: The lower timing drive.

**Figure 21.**The resulting friction torque for different engine media supply temperatures: The crankshaft main bearings.

**Figure 22.**The engine model for the journal-bearing simulation: (

**left**) The Finite Element model. (

**right**) The condensed model.

**Figure 24.**Lubricant viscosity dependences: (

**left**) The viscosity–temperature curve for different contact pressures. (

**right**) The viscosity–shear rate curves for different temperatures.

**Figure 25.**The equivalent temperatures for the isothermal journal-bearing simulation for main bearing 2 and big-end bearing 2 calculated using Equation (11).

**Figure 26.**The resulting FMEP using the journal-bearing simulation method: (

**left**) Main bearings. (

**right**) Big-end bearings.

**Figure 28.**The resulting friction torque using the journal-bearing simulation method: The strip-test stage 0 configuration.

**Figure 29.**A comparison between the measurement and journal-bearing simulation for a lubricant supply temperature of 90 ${}^{\circ}$C.

**Figure 30.**The resulting FMEP: The valve train (including the crankshaft seals and timing drive) for different engine media supply temperatures.

**Figure 31.**The friction loss distribution using the combined approach for different engine media supply temperatures—motored conditions.

**Figure 32.**The friction loss distribution using the combined approach for different engine media supply temperatures—engine speed n = 1200 rpm, load conditions.

**Figure 33.**The friction loss distribution using the combined approach for different engine media supply temperatures—engine speed n = 3500 rpm, load conditions.

Volume displacement | 1995 cm${}^{3}$ |

Compression ratio | 16.5:1 |

Bore | 84 mm |

Stroke | 90 mm |

Nominal torque | 380 Nm |

Nominal Power | 135 kW |

Maximum Speed | 4600 rpm |

Cylinder distance | 91 mm |

Conrod length | 138 mm |

Main bearing diameter | 55 mm |

Main bearing width | 25 mm |

Main bearing mounting clearance | 20 $\mathsf{\mu}$m |

Big-End bearing diameter | 50 mm |

Big-End bearing width | 24 mm |

Valve-train | DOHC |

Timing drive | chain |

Valve-train type | roller-type cam follower |

Valves | 4 per cylinder |

SAE class | 5W30 |

Density at 15 ${}^{\circ}$C | 853 kg/${\mathrm{m}}^{3}$ |

Dynamic viscosity at 40 ${}^{\circ}$C | 59.88 mPas |

Dynamic viscosity at 100 ${}^{\circ}$C | 9.98 mPas |

HTHS viscosity | 3.57 mPas |

**Table 3.**The rheological parameters for Equation (9) of the SAE 5W30 lubricant.

${\rho}_{0}$ | 853 | kg/${\mathrm{m}}^{3}$ |

${T}_{0}$ | 15 | ${}^{\circ}$C |

${f}_{1}$ | 0.001 | 1/MPa |

${f}_{2}$ | 0.003 | 1/MPa |

${f}_{3}$ | 8.5 × 10${}^{-4}$ | 1/${}^{\circ}$C |

**Table 4.**The rheological parameters for Equation (10) of the SAE 5W30 lubricant.

A | 0.064 | mPas |

B | 1124.7 | ${}^{\circ}$C |

C | 125.48 | ${}^{\circ}$C |

m | 0.79 | - |

$\alpha $ | 0.0009 | 1/bar |

r | 0.75 | - |

K | 3.5 × 10${}^{-7}$ | s |

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Knauder, C.; Allmaier, H.; Sander, D.E.; Sams, T.
Investigations of the Friction Losses of Different Engine Concepts. Part 1: A Combined Approach for Applying Subassembly-Resolved Friction Loss Analysis on a Modern Passenger-Car Diesel Engine. *Lubricants* **2019**, *7*, 39.
https://doi.org/10.3390/lubricants7050039

**AMA Style**

Knauder C, Allmaier H, Sander DE, Sams T.
Investigations of the Friction Losses of Different Engine Concepts. Part 1: A Combined Approach for Applying Subassembly-Resolved Friction Loss Analysis on a Modern Passenger-Car Diesel Engine. *Lubricants*. 2019; 7(5):39.
https://doi.org/10.3390/lubricants7050039

**Chicago/Turabian Style**

Knauder, Christoph, Hannes Allmaier, David E. Sander, and Theodor Sams.
2019. "Investigations of the Friction Losses of Different Engine Concepts. Part 1: A Combined Approach for Applying Subassembly-Resolved Friction Loss Analysis on a Modern Passenger-Car Diesel Engine" *Lubricants* 7, no. 5: 39.
https://doi.org/10.3390/lubricants7050039