Wet clutch material screening
Use of UMT TriboLab screening clutch friction materials
Clutch automatic transmission in the smooth running, and the rate dependence of the coefficient of friction (COF package) are closely related.Full size clutch test is often used to obtain the friction data, such as JASO M348 or in any other SAE OEM test scheme of friction testing machine to run 2, these tests are generally costly and time consuming.In addition, the evaluation of each kind of new friction materials formula or process change, need to be manufactured and assembled a full-sized clutch parts.Before you perform a full size clutch test in the laboratory complete friction material selection, can greatly shorten the development time, reduce development costs.
Performance verification of the clutch
Automatic transmission clutch (also known as wet clutch) reduced in size is an increasing demand for higher specific torque capacity.In order to meet the demand of competition in the business environment, material and clutch design engineer designer can by using the analysis model to shorten product development time.Using these models, explore a lot of design and material change, and to assess their effect on system performance.Main performance characteristics of clutch and brake is called its roughness (HVN) response, vibration and noise.HVN with COF package sliding velocity dependence is strong.With the increase of sliding velocity, and a variety of contact pressure, COF package need to display a stable or increase slightly.It is well known that friction is a kind of system attributes, rather than the material properties.Therefore, the use of the convenience of analysis model in design for model validation requirements and reduced, especially the new clutch friction material behavior.In addition, compared with the full size equipment or systems, desktop test must meet the following performance the burden of proof.Automatic transmission clutch (also known as wet clutch) in smaller size, so the demand for high torque range is increasing day by day.In order to meet the needs of a competitive business environment, material and clutch design engineer designer can by using the analysis model to shorten product development time.Such a model can be used to explore a lot of design and material change, and to assess the impact of these changes on system performance.Clutch and brake has a key performance characteristics is the roughness of acoustic vibration and noise and vibration (HVN) response.HVN is closely related to the sliding velocity of COF package dependency.Ideally, COF package value in the process of sliding speed and in a series of contact pressure conditions remain stable or increase slightly.It is well known that friction is a kind of system attributes, rather than the material properties.As a result, the demand for model validation, especially the new clutch friction material performance, influence the use of the convenience of analysis model in the design work.In addition, compared with the full size equipment or systems, must meet the demand of the performance of the subsequent validation test bench test.
COF package performance evaluation
Mentioned earlier, to minimize HVN and guarantee the smooth performance of clutch, ideally, COF package value in the process of sliding speed remain stable or increase slightly.If the COF package value in the process of acceleration is reduced, will cause the clutch vibrate or vibration.Although some analysis model already contains the clutch system stiffness, material, rotor/stator contact pressure, temperature, sliding speed and COF package, but still need to COF package of experimental data, especially as a function of other variables.Full size clutch test is often used to obtain such data, such as JASO M348-2012 or any other in the SAE OEM test scheme of friction testing machine to run 2, but these tests cost is high, long time consuming, and the need to manufacture and assembly full size clutch parts.
If in choosing materials into parts and full-size test before the first screening test for simple test rig, on the material, is expected to save material development cost and time.Including clutch material itself, reaction plate and clutch oil operation, here refers to the automatic transmission oil (ATF).The purpose of this research is that a test bench test on materials selection and scheme design, to perform a full size on the material to carry on the preliminary screening before test.Measure whether the research and development, success will be test bench test whether can obtain the same as the full size test material ranking order.Its purpose is not completely copy the full size test plan (including more than 275 independent collocation speed, contact pressure and temperature conditions), but developed a can be used on desktop tester of simplified test sequence subset, and according to the relative rankings, determine the subset of the same material includes a variety of speed under the condition of dependence.
Simulation of size effect
Although in test bench friction materials testing, appropriate simulation obviously need to contact pressure and sliding speed and temperature, but the smallest size is also very important contact, the reason is that the clutch material have heterogeneity, need to include all ingredients and the surface roughness and porosity of the reservoir and channeling.By using the brook white light interferometer (index) to obtain three-dimensional topography, the picture on the right shows the change in the surface texture.If the interface is too small, uneven composition and the influence of surface roughness on friction loss, friction test bench test will not be able to correctly simulate the actual system.
Complete the simulation
The full size parameter is very important for simulation test bench tests:
- Under the given speed of clutch material bonding time
- Contact pressure loading rate
- Contact pressure loading rate
- The stop delay time between test conditions
At left shows the equipped with rotary actuation, the heating chamber and liquid pump system test bench test systemUMT TriboLabAnd small size clutch a close-up of test samples.
Screening test results
The picture on the right shows the UMT TriboLab test-bed system and full size test bench under the condition of 120 ° C to perform the pace of the clutch COF package material results.Two tests in the shape of the curve relative rankings, as the velocity function and COF package of the order of magnitude of each aspect are relatively consistent.
The COF package material B and the relation curve of speed were positively slope, therefore suitable for clutch design modeling.Other small size test sequence, including dependencies, COF package and speed also showed a good correlation with the full scale test data.
Test screening tool
UMT TriboLab screening tool is an excellent test rig, the appropriate application of full size clutch used in the test stand equal contact stress, acceleration, sliding velocity, flow condition and temperature, can provide the data for modeling, shorten the decision-making time at the same time, reduce the size of clutch test bench test validated materials used cost.
