Design of a Diaphragm Spring Clutch

Download Full-Text PDF Cite this Publication

Text Only Version

Design of a Diaphragm Spring Clutch

Tanmay Ajit Luniya

Department of Mechanical Engineering Rajarshi Shahu College of Engineering, Tathawade

Pune, India

Abstract Clutch is a very essential element in torque transmission process. The purpose of a clutch is to initiate motion in the automobile generally by transferring kinetic energy from another moving here which is the Engine. Clutches are designed to transfer maximum Torque form engine with Minimum Heat Generation. The present work deals with designing of (Ø310) Diaphragm Spring Clutch for a GVW of 8330kg with input parameters provided by the customer company.

Keywords Diaphragm Spring Clutch, Torque, Stress Generated, Clamp Loads, Heat Generated.

  1. INTRODUCTION

    In the Automotive Power Transmission the Clutch is designed after the Engine and Gear Box characteristics is finalized. The Customer has provided Input data comprising of the Engine Parameters (i.e. Engine Power, Max Engine Torque, RPM and Number of Engine Cylinders), Gear Box Parameters (i.e. Gear Ratios and Final Reduction), Vehicle Dimensions(i.e. Clutch Housing Diameter and Vehicle Weight) to design the Single Plate Diaphragm type Clutch for Medium Duty Vehicle. During the Clutch Design is necessary to ensure that,

    1. The Contact surfaces develop the frictional force that may pick up and hold the load with reasonable low pressure between the contact surfaces.

    2. The Heat of friction should be rapidly dissipated and tendency to grab should be at minimum.

    3. The surface should be backed by the material stiff enough to ensure reasonable uniform distribution pressure.

    4. Suitable Friction material forming the contact surfaces is to be selected.

    5. Clutch should not require any external force to maintain contact and the projection parts must be guarded.

      Clutch Components are to be designed using these all the necessary parameters.

      Fig.1. Automotive Transmission System Layout.

  2. WORKING OF CLUTCH

    The Diaphragm spring clutch uses a diaphragm or conical spring instead of coil spring to produce adequate pressure for engaging the clutch. The clutch cover is successfully secured to the engine flywheel. The pivot rings are held in clutch cover. The outer rim of the diaphragm spring is in contact with the pressure plate. In engaged position, the diaphragm spring keeps the pressure plate in firm contact with the flywheel.

    Fig.2. Working of Diaphragm Spring Clutch.

  3. DESIGN DETAILS

    Sr. No.

    Particulars

    Specification

    1.

    Vehicle : TD 3250 CR

    2.

    GVW (kg)

    8330

    3.

    RAW (kg)

    1710

    4

    Tyre

    3540

    5

    Dy. Radius (m)

    0.39

    6.

    Engine

    TD 3250 5CYL

    7

    Engine Power (kW)

    90

    8

    Max Engine Torque Nm

    320

    9

    Max Engine RPM

    2800

    10

    Max Torque RPM

    1800-2400

    11

    Gear Box Ratios

    Sr. No.

    Particulars

    Specification

    1.

    Vehicle : TD 3250 CR

    2.

    GVW (kg)

    8330

    3.

    RAW (kg)

    1710

    4

    Tyre

    3540

    5

    Dy. Radius (m)

    0.39

    6.

    Engine

    TD 3250 5CYL

    7

    Engine Power (kW)

    90

    8

    Max Engine Torque Nm

    320

    9

    Max Engine RPM

    2800

    10

    Max Torque RPM

    1800-2400

    11

    Gear Box Ratios

    Table I: Input for Ø 310 Clutch Design for TD 3250

    First

    5.053

    Second

    2.601

    Third

    1.512

    Fourth

    1

    Fifth

    0.784

    Reverse

    4.756

    Final Reduction

    4.375

    12

    Set Height

    62

    13

    Clutch Actuation

    Hydraulic

    14

    Pot Depth of Flywheel

    Flat

    15

    Clutch Mounting PCD

    314

    16

    Clutch Facing Inner Diameter (mm)

    170

    17

    Clutch Facing Outer Diameter (mm)

    310

    Table III: Nomenclature and Symbols

    Sr. No.

    Parameter

    Symbols

    1

    Gross Vehicle Weight

    GVW

    2

    Dynamic rolling radius

    m

    3

    Engine Torque

    T

    4

    Engine Speed

    N

    5

    Clutch Plate Inner Radius

    Ri

    6

    Clutch Plate Outer Radius

    RO

    7

    Coefficient of friction

    8

    Outside diameter of clutch

    D

    9

    Inside diameter of clutch

    Di

    10

    Slip Torque

    TS

    11

    Clamp load

    W

    12

    Mean radius

    Rm

    13

    Diameter ratio

    Dr

    14

    Load on flat

    Pflat

    15

    Thickness of diaphragm spring

    t

    16

    Height of diaphragm spring

    h

    17

    Stress on diaphragm spring

    18

    Deflection of spring

    19

    Spring rate

    K

    20

    Working load

    F

    21

    Working stress

    22

    Solid length of spring

    LS

    23

    Block load of spring

    FB

    24

    Block stress of spring

    25

    Total torque

    TT

    26

    Total load

    FT

    27

    Wire diameter

    d

    28

    Outer diameter of spring

    DO

    29

    Mean diameter of spring

    dm

    30

    Modulus of rigidity

    E

    31

    Torsional radius

    R

    32

    Torsional angle

    33

    No. of total coils of spring

    n

    34

    No. of active coils of spring

    na

    35

    Acceleration

    A

    36

    Force

    F

    37

    Velocity

    V

    38

    Slip time

    ts

    39

    Heat generated

    q

    40

    Specific heat

    Q

    41

    Thermal stress

    42

    Outside diameter of casing

    43

    Maximum diameter for bolt

    44

    Spline diameter

    45

    Maximum length required for spring

    46

    Length of slot for 1st stage

    47

    Outside diameter of hub

    48

    Diameter of stop pin

    49

    Outside diameter of diaphragm

    50

    Outer diameter of slot

    51

    Outside diameter of fulcrum

    52

    Inside diameter of fulcrum

    53

    Spring index

    C

    54

    Deflection Factor

    K1 ,k2, k3

    55

    Diaphragm angle

    A

      • Material Selection: 50CrV4

          1. Clamp load (W) Calculation:

      • The given values as per problem statement are:

        • Max Engine Torque (T) = 320 Nm

        • Outer radius ) = 155mm

        • Inner radius (Ri) = 87.5mm

      • To find

        Clamp load

        Stresses at various points

      • Slip torque calculations:

        Max Engine Torque (T) = 320 Nm

        Assume Slip Torque (Ts) is 1.7 times T Therefore Ts = (T) * (1.7)

        = 320*1.7

        Ts =544 Nm

      • To calculate mean radius (Rm):

        Mean Radius (According to uniform Pressure Theory)

        Mean Radius (Rm)

        Rm=0.12438 m

            1. To calculate the clamp load (W):

              Slip Torque Ts= 2 * * W* Rm 544= 2*0.27*W*0.1136

              W = 900 Kg

              Clamp Load (W) = 825.63 kg

      • To determine the stresses induced in the diaphragm spring

    Input Parameters

    Thickness of diaphragm (t): 3.65mm

    Outside diameter of diaphragm (Da): 289mm Slot outer diameter (Di'): 240mm

    Diaphragm angle (A): 13.833º Height of diaphragm (h): 5.857mm

    Outer fulcrum diameter (Dap): 284.5mm Inner fulcrum diameter (Dip): 236mm Poisons ratio (µ): 0.27

    Modulus of elasticity (E): 20500kgf/mm2

    To determine:

    i

    i

    1. Actual Diameter (Di ) = (D )-(2 * S * Sin(A))

      =217 2(3 x sin (14))

      Di= 238.34 mm

    2. Diameter Ratio (Dr) =

      =

      Dr =1.2130

    3. Alpha () =

      =

      =

    4. Load on flat (Pflat) =

      =

    5. Load on flat with Pf )*

    = (818.07) *

    Pf=1025.3524 N

    3

    3

        1. Stress Calculations:

    Fig.3. Stresses on Diaphragm Spring Thickness as, t =3.65mm

    Consider Deflection h = 5.857mm

    Calculation of deflection factor k1, k2, k3

    1. =

    = 0.3050

    2. = *

    = 1.096

    3. = *

    = 1.0535

    1. Stress at point 5:

      * ) * (

      = -72.523 N/mm2

    2. Stress at point 1:

      = -146.7N/mm2

    3. Stress at Point 2:

      =13.364 N/mm2

      = 1014.8897 N

    4. Stress at Point 3:

      = 123.66N/mm2

    5. Stress at Point 4:

    = -7.536N/mm2

    Safe Stress = 0.8* UTS

    = 0.8 * 180

    Safe Stress = 144 N/mm2

    As the Max Stress, 138.914 N/mm2 < Safe Stress 144 N/mm2 our design is safe

    Factor of safety = Factor of Safety = 1.295

    3.2 Design of Damper Spring

    As per the given data of damper dimensions we find out the deflections, spring rate, stress and torque on the spring.

    Material for damper spring: Spring Steel as per AS 4454 1975 Grade2D

    Damper Torque Calculation:

    Assume that Damper Torque is 1.3 to 1.45 times engine torque

    Damper Torque= 1.4* Engine Torque

    = 1.4*320

    Damper Torque = 448 N

    Now we find out deflection to determine working load and spring rate for inner and outer springs

    Fig.4. Inner and Outer Damper Spring

    PARAMETER

    UNIT

    SPECIFICATION

    Wire Dia

    Mm

    4.5

    No. of Total Coils

    5.5

    No. of Active Coils

    3.5

    O. D.

    23

    Material Grade

    2D

    UTS

    Kgf/mm2

    185

    Mean Dia(dm)

    18.5

    Length

    28

    Modulus Of Rigidity (G)

    Kg/mm2

    7500

    Number of springs

    8

    Engine Torque

    Nm

    320

    Torsion Angle

    Degree

    5.5

    Torsional Radius

    Mm

    53.3

    PARAMETER

    UNIT

    SPECIFICATION

    Wire Dia

    Mm

    4.5

    No. of Total Coils

    5.5

    No. of Active Coils

    3.5

    O. D.

    23

    Material Grade

    2D

    UTS

    Kgf/mm2

    185

    Mean Dia(dm)

    18.5

    Length

    28

    Modulus Of Rigidity (G)

    Kg/mm2

    7500

    Number of springs

    8

    Engine Torque

    Nm

    320

    Torsion Angle

    Degree

    5.5

    Torsional Radius

    Mm

    53.3

    Table III: Input parameters for outer spring

        1. Calculation for outer spring

          1. Deflection () = Angle x radius(r)

          = x x 57.3

          = 4.9087 mm

          F =

          Working Load (F) = 85.1538kgf

          1. Spring rate (K) = = 17.35kg/mm

          2. Working Stress ) =

            = 44.022kgf/mm2

          3. Solid Length ) = (n) x (d)

            = (6.16 x 2.8)

            = 23.65 mm

          4. Spare Length ={Length – Solid Length} {Deflection}

            = 28 23.65 – 4.9087

            Spare Length= -0.563 mm

          5. Block Load ) = Block Length x K

            =78.386kgf

          6. Block Stress ( ) =

            =

            =38.97kgf/mm2

          7. Total Load ( ) = No. Of springs x Working Load

            =631.2034kgf

          8. Total Torque ) = Load x Torsional Radius x 9.81

          =631.234 x 53.3 x 9.81

          =417.69 Nm

        2. Calculations for Inner Spring

    Table IV Input parameters for Inner Spring

    PARAMETER

    UNIT

    SPECIFICATI ON

    Wire Dia

    2.5

    No. of Total Coils

    9.5

    No. of Active Coils

    7.5

    O. D.

    13.5

    Material Grade

    2D

    UTS

    Kgf/m m2

    185

    Mean Dia (dm)

    12

    Length

    28

    Modulus Of Rigidity (G)

    Kg/m m2

    7500

    Number of springs

    8

    Engine Torque

    Nm

    320

    Torsion Angle

    Degre

    e

    5.5

    Torsional Radius

    Mm

    53.3

    UTS

    Kgf/m m2

    185

    Mean Dia (dm)

    12

    Length

    28

    Modulus Of Rigidity (G)

    Kg/m m2

    7500

    Number of springs

    8

    Engine Torque

    Nm

    320

    Torsion Angle

    Degre

    e

    5.5

    Torsional Radius

    Mm

    53.3

    1. Deflection () = Angle (in radian) x radius(r)

    = x x 57.3

    = 4.9087 mm

    F =

    Working Load (F) = 85.1538kgf

    1. Spring rate (K) = = 17.35kg/mm

    2. Working Stress ( )

      = 44.022kgf/mm2

    3. Solid Length ) = (n) x (d)

      = (6.16 x 2.8)

      = 23.65 mm

    4. Spare Length ={Length – Solid Length} {Deflection}

      = 28 23.65 – 4.9087

      Spare Length= -0.563 mm

    5. Block Load ) = Block Length x K

      =78.386kgf

    6. Block Stress ( ) =

      =

      =38.97kgf/mm2

    7. Total Load ( ) = No. Of springs x Working Load

      = 631.2034kgf

    8. Total Torque ) = Load x Torsional Radius x 9.81

    =631.2034 x 53.3 x 9.81

    = 417.69 Nm

      1. Calculations of Slip Time for 1st& 2ndGear :

        Table IV Input parameters for Slip Time Calculations

        S

        r.

        No.

        Particulars

        Specification

        1

        Gradability (%)

        15

        2

        GVW (kg)

        8330

        3

        Dy. Radius (m)

        0.339

        4

        Max Engine Torque Nm

        320

        5

        Max Torque RPM

        1400

        6

        Gear Box Ratios

        First

        5.053

        Second

        2.601

        7

        Differential ratio

        4.375

        8

        of transaxle )

        85

        9

        Road resistance constant (kg/ ton weight)

        20

        1. Slip Time for 1st Gear:

          1. Consider 15 Gradability with Indian roads Tan = (

            = 0.148radian

          2. Force (F) =B- (

            Force (F) = 298.687kg

          3. Force = (mass) * (Accln) Accln =

            a = 0.35 m/s2

          4. Velocity(v)=( *( )

            = ( ) * ( )

            v= 2.393 m/s

          5. V = u + at (By Newtons Laws of motion) 2.393 = 0 + (1.7305) * )

          Slip time ) = 6.8175 sec

        2. Slip Time for 2ndGear:

    1. Force(F)=B- (

      F= 665.85kgf

    2. Force = (mass) * (Accln) Accln =

      a = 0.7842 m/s2

    3. Velocity(v)=(*

      = ) * )

      v = 6.6435 m/s

    4. V = u + at

    6.6435= 0 + (0.0910) * (t)

    = 8.4772 sec

    As the slip time value of 2nd gear is Large, vehicle will not start in 2nd gear.

    • Heat generated for 1st gear: q =

      =46.98kJ/s

    • Specific Heat for 1st gear (Q) = (q) * )

    = (46.98) * (6.8175)

    Q = 0.319 MJ

    Thermal stress ( ) =

    = 1.5508 J/mm2

    *Maximum permissible thermal stress is 2 J/mm2 As 2J/mm2 the Design is Safe.

  4. CONCLUSION

    The Diaphragm type clutch is designed for TD 3250 as per the customer requirements. All the parts were modeled using CATIA and Finite Element Analysis in ANSYS is conducted to verify the results. All the results were found to be within the permissible limits. New designs of Diaphragm Spring have been suggested and should be considered for further investigation. Detailed study of manufacturing processes of Diaphragm spring was done and manufacturing process was suggested. All the parts were procured and assembled in the industry premises. Strict Quality Control and Inspection processes were devised and implemented on the clutch manufacturing.

  5. FUTURE SCOPE

The Diaphragm spring Design can be optimized to reduce its weight. A modified design has been suggested, but further study and analysis needs to be done to checks its feasibility. The deflection of the Diaphragm clutch can be reduced by introducing a strap plate. However more study and research

needs to be conducted. Pin fin can be used to increase heat transfer rate and prevent the overheating of the clutch. Clutch housing can be provided with a window to enhance air circulation for heat dissipation.

ACKNOWLEDGMENT

I take this opportunity to express our gratitude towards my guide Prof. D.P.Borse, who helped me in times of difficulty. He remains a pragmatist with his untiring efforts, and his technical critique helped me complete this project. I also wish to express my sincere thanks to my Mother and Father who have been an invaluable source of guidance and motivation in writing this paper to the best of my potential. I am deeply grateful to our sponsor Jaya Hind Industries Ltd, our guide Mr. A.B.Mulani, Sr. Mgr R&D for providing us valuable guidance whenever required.

REFERENCES

  1. Shigleys Mechanical Engineering Design, Richard G. Budynas, J. Keith Nisbett, TataMcgrawHill, Ninth Edition.

  2. Machine Design an Integrated Approach, Robert L. Norton, Pearson Education Inc., Second Edition.

  3. Clutches and Brakes Design and Selection Willium C. Orthwein Second Edition.

  4. Daikin Clutch Fundamentals and Product Guide Published by Exedy.

  5. The Physics of Diaphragm Spring Published by Hanssermans.

  6. Properties of Engineering Materials and Design Data for Machine Elements by Abdulla Shariff, Dhanpat Rai, et.al

  7. Finite Element Analysis and Optimal Design of Automobile Clutch Diaphragm Spring, Wook-Hee Nam, Choon-Yeol Lee, Young S. Chai, Jae-Do Kwon, June12-15, 2000.

  8. Increasing Stiffness of Diaphragm-Spring Fingers asa Part of System Approach Darko Danev1, Milan Kjosevski& Simeon Simeonovss Cyril and Methodius University in Skopje, International Journal of Automobile Engineering Research and Development Feb 2011-12

  9. Self-Energizing Clutch Actuator System: Basic Concept and Design, Jinsung Kim, SeibumB. Choi.

  10. A Study On Fatigue and Durability Characteristics Of Clutch Diaphragm Spring according to Tempering Condition, Wook-Hee Nam1) * Choon-Yeol Lee 2)

  11. The Correction Factor for Rate of Energy generated in the FrictionClutches under Uniform Pressure Condition, May, 2012 Centro UniversitárioDa Fei São Bernardo Do Campo Sp Brazil

  12. Engagement Characteristics of a Friction Pad for Commercial Vehicle Clutch System Aravind Vadiraj, Advanced Engineering,

    Ashok Leyland Technical Centre, 7 July 2010

  13. Observation and Optimization of The Characteristic of the Diaphragm Springs Used In Clutch Systems, Murat Ozbakis, July, 2008.

Leave a Reply

Your email address will not be published. Required fields are marked *