THE STRESS VARIATION BY CHANGING THE SUPPORTING POINT LOCATION IN THE MOTOR VEHICLE CLUTCH ASSEMBLEY

Transcription

1 THE STRESS VARIATION BY CHANGING THE SUPPORTING POINT LOCATION IN THE MOTOR VEHICLE CLUTCH ASSEMBLEY M.Sc.Sasko Milev 1)*, Ph.D. Simeon Simeonov 1)*, Ph.D. Petar Simonovski )*, PhD. Nikola Avramov )*, Ph.D. Sasko Dimitrov 1)*, and PhD. Slavco Cvetkov 1)* 1)* aculty o Mechanical Engineering - Goce Delcev University in Stip, Macedonia )* aculty o Mechanical Engineering Ss.Cyril and Metdius University in Skopje, Macedonia sasko.milev@ugd.edu.mk; Abstract: The diaphragm spring as one o the most important parts o the motor vehicles clutch assembly provides the compressive orce on the pressure disk. This orce is needed or generating riction between the coupling o the lywheel and the pressure disk and transmitting the torque rom the engine to the transmission. Thereore the diaphragm spring is subjected to complex loads. The nominal stress or dimensioning the spring is the tangential stress, which is calculated by the terms o Almen and Laszlo. The aim o this research is analyzing the location o the diaphragm spring supporting points o the clutch assembly and its eect on the caused stresses by using the inite Element Metd. Keywords: DIAPHRAGM SPRING, RICTION CLUTCH, EXPRESSIONS O ALMEN AND LASZLO, TANGENTIAL STRESS 1. Introduction The clutch coupling allows the engaging and disengaging o the vehicle transmission. The required compressive orce or creating the riction necessary or torque transmission is achieved by the diaphragm spring. When perorming its unction, the diaphragm spring is subjected to dynamic loadings. The stresses occurring at the spring are compression and extension, igure 1. [1],[]. А 4 stress in upper surace stress in centrl cone 1 А compression tension two points o interest. Point 1 where the orce acts (created by the spring delection) and the point where the spring is supported, where the orce is also equal to. When the spring is in the lat position, the compression orce allows the torque to be transmitted. Moving the release bearing or a certain path (delection) causes the clutch to disconnect [], [4].. Researching The purpose o this research is by using the inite element metd to determine the spring stress depending on the location o the supporting points in both the lat or mounted position and at the maximum deviation or disengaged position. The analysis were carried out on a diaphragm spring or commercial vehicles with next dimensions : internal diameter o a diaphragm spring Di = 1 [mm], outer diameter o a diaphragm spring Da = 95 [mm], spring thickness s = 5. [mm], Module o elasticity o the steel E = [N /mm ], Poison number o spring steel μ = 0., internal diameter o the diaphragm spring with supporting points Dip = 6 [mm], outer diameter o the diaphragm spring with supporting points Dap = 9 [mm], path o the clutch while disengaging l = 1 [mm], release bearing diameter d = 10 [mm]. [5], [6] igures and 4 sws the distribution o orces acting on the spring, with one and two supporting points used or the clutches. Dip stress in lower surace ig. 1 Spring stresses The diaphragm spring use the clutch assembly couplings has the location o the supporting points as swn on the picture or in the case o a vehicle tse are a supporting edges, igure. 4 1 α A max l Di Dap Da ig. Spring with one supporting point d ig. Diaphragm spring with its supporting points By mounting the clutch in the vehicle, the shape o the spring changes, rom its conical shape it becomes lat (it makes a deviation = ), and then the process o spring loading starts. The spring has

2 x A α Dap Da B max Dip l Di ig. 4 Spring with two supporting points In order to note the inluence o the supporting points, the spring calculation was perormed: - supporting point A, by moving the spring rom the initial or zero position to the lat position, the spring makes a deviation. d The supporting point A is stationary, and the release bearing moves the spring rom the lat position or the path l that disengages the spring (maximum deviation is achieved). - rom the two supporting points A and B, in the lat position o the spring, the supporting point B is stationary. The release bearing moves rom the lat position or the path l, and the point A travels the distance x, and within this displacement the pressure disk is raised and the clutch is disengaged. By using a inite Elements Metd (commercial sotware package), the spring cross-section is divided into 1 elements (ig. 5) in which the stress is calculated. rom the simulation results, the ollowing diagrams or the tangential stress or two cases (ig. 6 and 7) were obtained: The support point A is on a diameter o Ø9[mm], and the internal diameter Di = 1[mm] moves rom the initial position to the lat position () and to a maximum deviation o max. The support point A is on a diameter o Ø9, and the supporting point B is on the diameter o Ø6[mm]. rom the lat spring position, point B is stationary and point A moves in opposite direction rom the direction o the release bearing that travels the distance l, [7]. ig. 5 EM elements or stress calculation ig. 6 Diagram o tangential stresses with a support point A,

3 ig. 7 Diagram o tangential stresses with two supporting points, A and B Complex stresses are presented at igures 8 and 9 : ig.8 Complex stress at the lat and disengaged position Ø9/0 ig.9 Complex stress at the lat and disengaged position Ø9/6.Analisys o the results and discussion : The calculations were carried out by the EM and the obtained diagrams (ig. 6 and 7), or the change in the tangential stresses o the diaphragm spring body swn on the diagrams (ig. 10 and 14) and the tables (1and ) were analyzed [4], [7].

4 Table 1: Tangential stresses at the spring lat position 9,0 9,0 90, 81, 69, , 4,5,7 15 D(mm) 8,86 8,75 8,55 7,57 6,7 5,0,7,4 1,1 0, (mm) Ø9/6 σ(n/mm ) Ø9/0 σ(n/mm ) With one support, with two supports ig. 10 Distribution o the tangential stress at the lat position o the spring Table : Tangential stresses at the spring disengaged position 9,0 9,0 90, 81, 69, , 4,5,7 15 D(mm),8,,7 4, 5 5,6 6,5 8,1 9,8 (mm) Ø9/6 σ(n/mm ) 1,5 1, 1,0 10,57 8,77 7,0 5,15, 1,51 0,8 (mm) Ø9/0 σ(n/mm ) With one support, with two supports ig. 11 Distribution o the tangential stress at the disengaged position o the spring,

5 The highest tangential stress occurs in point (i the supporting point is placed on the location o point ), then it has the greatest deviation plus the deviation rom the displacement o the release bearing traveling the distance o l = 1mm (max = 7,85 + 4,9 = 1,7mm). This can be seen rom the picture o the complex stress (ig.1). ig.1 Complex stress at the disengaged position Ø9/ Ø1 4. Conclusion : The ollowing conclusions can be given: The stress at lat spring position with one and two supporting points has small deviation o one curve compared to the other. The stress at the maximum spring delection has the mutual variation o the curves. With one support, the maximum stress occurs in the region o the point, and with two supports around the location o the point. The reason or this is that in the irst case, the diaphragm spring is reclined like a beam ixed on one o its sides, and in the second case the spring is reclined on two supports. Reerences [1] Orthwein C.William Clutches and brakes : Design and Selection CRC Press; edition (004) [] Nam W., Lee H., Chai Y.C. and Kwon D.J. inite Element Analysis and Optimal Design o Automobile Clutch DiaphragmSpring. ISITA World Automotive Congress, Seoul, [] Mubea Disc Spring Handbook. (199), Catalogue. [4] Almen J.O. and Laszlo A. (196). The Uniorm Section Disk Spring. (196), ASME 58. [5] Kaya, N. Optimal design o an automotive diaphragmspring with atigue resistance. Internatonal Journal o Vehicle Design. (006) Vol.40. [6] Nunney, Malcom J. Light and Heavy Vehicle Technology 4 th ed. (001) Elsevier Ltd., London. [7] Cook D. Robert inite Element Modeling or Stress Analisys Wiley, 1 st edition (1995)