Effect of Friction Material on the Relative Contribution of Thin-Film Friction to Overall Friction in Clutches

Devlin, Mark T.; Tersigni, Samuel H.; Senn, Jeremy; Turner, Tu Lai; Jao, Tze‐Chi; Yatsunami, Kenji

doi:10.4271/2004-01-3025

Cited by 15 publications

(5 citation statements)

References 31 publications

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“…Void volume of the friction material surface is related to the fluid retention ability of the surface. Devlin, et al (10) proposed that the thin-film lubrication contributes more to overall friction in SAE No. 2 tests than in the VSFT test due to the better fluid flow in SAE No.…”

Section: Investigated Parametersmentioning

confidence: 99%

“…2 and VSFT tests. Devlin, et al (10) proposed an equation to link the contribution of friction coefficient of boundary lubrication part µ BND and the friction coefficient of thin-film lubrication µ TF in the overall friction and to show the relation between thin-film lubrication, boundary lubrication, and the overall friction measured in the test:…”

Section: Lubrication Comparison Between Vsft and Sae No 2 Testsmentioning

confidence: 99%

“…The understanding of the mechanisms by which the performance is delivered is evaluated by an assessment of the physical nature of the posttest surfaces as a result of friction material/ATF additive interactions. JASO established the M349 series standards in the 1990s, which were designed to reproduce conditions seen in the actual CSTCC and to improve the precision of anti-shudder durability testing (Murakami,et al (6); Devlin, et al (10)). Devlin, et al (10), (11) and Li, et al (12) have published a series of papers describing work that they performed on JASO SAE No.…”

Section: Introductionmentioning

confidence: 99%

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Anti-Shudder Properties of ATFs—An Investigation into Friction Modifying Mechanisms Using VSFT and SAE No. 2 Tests

Zhao

Morina

Neville

et al. 2010

Tribology Transactions

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In recent years, continuous slip torque converter clutches (CSTCCs) have been widely used in automatic transmissions, mainly to improve fuel efficiency. With the adoption of these devices the problem of shudder vibration has arisen. To help alleviate this problem, better anti-shudder characteristics are desired for automatic transmission fluids (ATFs). Positive µ-v curves are well recognized to correlate to the avoidance of shudder. A variable-speed friction tester (VSFT), which combines a low-velocity friction apparatus (LVFA)-type test with the ability to age an oil in situ, was used to determine friction characteristics of four model ATF formulations in a wet clutch tribosystem. The linear-defined multiple parameter spider chart ATF evaluation (LSAE) method was applied to present the ATF's overall friction results including anti-shudder performance and durability (Zhao, et al. (1)). One modified SAE No. 2 test was also used to test the four oils' friction behavior, to compare with the VSFT results. Similar performance rankings have been obtained from those two tests. Both test results and evaluation parameters will be discussed in this article and the response will be linked to the physical parameters defining the posttest surface. The oil absorption ability of post test friction material is shown to be important to the overall friction performance. The environmental scanning electron microscope (ESEM) images and 3D profiling results showed that some surface topographical parameters, such as V vc (void volume of the core) and V vv (void volume of valleys), can be linked with the friction modifying mechanisms in the ATF tests.

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Section: Investigated Parametersmentioning

confidence: 99%

Section: Lubrication Comparison Between Vsft and Sae No 2 Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Anti-Shudder Properties of ATFs—An Investigation into Friction Modifying Mechanisms Using VSFT and SAE No. 2 Tests

Zhao

Morina

Neville

et al. 2010

Tribology Transactions

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show abstract

“…The friction characteristics of the clutch material are influenced by different factors such as the clutch material structure, porosity, lubricant and permeability (Berglund, 2013;Marklund, 2010). Furthermore, the coefficient of friction may be affected by sliding speed, varying load, boundary friction, contact temperature of clutch plates and friction due to fluid flow through the friction material (thin-film friction) (Fatima et al, 2012;Devlin et al, 2004).…”

Section: Automatic Transmission Clutchesmentioning

confidence: 99%

On-board Clutch Slippage Detection and Diagnosis in Heavy Duty Machine

Källström

Olsson

Lindström

et al. 2020

IJPHM

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In order to reduce unnecessary stops and expensive downtime originating from clutch failure of construction equipment machines; adequate real time sensor data measured on the machine in combination with feature extraction and classification methods may be utilized.This paper presents a framework with feature extraction methods and an anomaly detection module combined with Case-Based Reasoning (CBR) for on-board clutch slippage detection and diagnosis in heavy duty equipment. The feature extraction methods used are Moving Average Square Value Filtering (MASVF) and a measure of the fourth order statistical properties of the signals implemented as continuous queries over data streams. The anomaly detection module has two components, the Gaussian Mixture Model (GMM) and the Logistics Regression classifier. CBR is a learning approach that classifies faults by creating a new solution for a new fault case from the solution of the previous fault cases. Through use of a data stream management system and continuous queries (CQs), the anomaly detection module continuously waits for a clutch slippage event detected by the feature extraction methods, the query returns a set of features, which activates the anomaly detection module. The first component of the anomaly detection module trains a GMM to extracted features while the second component uses a Logistic Regression classifier for classifying normal and anomalous data. When an anomaly is detected, the Case-Based diagnosis module is activated for fault severity estimation.

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“…Automatic transmission fluid (ATF) is vital for the whole engagement and driving quality in this wet clutch system as well as the lock-up clutch friction couple materials. However, this slipping motion can lead to an uncontrollable stick-slip phenomenon called shudder, which is one of the main problems in the current ATs [2,3,[5][6][7][8][9][10][11]. The shudder problem is becoming more and more important due to the design of clutch and friction plate sizes, which are shrinking for fuel economy reasons [10,12].…”

Section: Introductionmentioning

confidence: 99%

A new method to evaluate the overall anti-shudder property of automatic transmission fluids – multiple parameters spider chart evaluation

Zhao

Neville

Morina

et al. 2008

Proceedings of the Institution of Mechanical Engineers, Part J:

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Formulating automatic transmission fluids (ATFs) can pose some diverse challenges. The friction response should ensure a smooth engagement process with no shudder in the automatic transmission. Friction, as a function of velocity, must show a smooth and positive/plateau curve as velocity increases in the μ − v plots. In this study, the friction behaviour of some basic additive systems for ATFs was assessed by using a variable speed friction test (VSFT) rig. The test was used to mimic the clutch engagement process and to evaluate the friction response of different formulations. The focus was anti-shudder properties of the designated formulations. A new method of evaluating VSFT results was developed to assess the overall ATF friction behaviour in conjunction to the common friction-velocity curve analysis. X-ray photoelectron spectroscopy was used to check the different surface conditions before and after the test.

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Effect of Friction Material on the Relative Contribution of Thin-Film Friction to Overall Friction in Clutches

Cited by 15 publications

References 31 publications

Anti-Shudder Properties of ATFs—An Investigation into Friction Modifying Mechanisms Using VSFT and SAE No. 2 Tests

Anti-Shudder Properties of ATFs—An Investigation into Friction Modifying Mechanisms Using VSFT and SAE No. 2 Tests

On-board Clutch Slippage Detection and Diagnosis in Heavy Duty Machine

A new method to evaluate the overall anti-shudder property of automatic transmission fluids – multiple parameters spider chart evaluation

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