(19)
(11)EP 3 482 101 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
04.11.2020 Bulletin 2020/45

(21)Application number: 17733711.0

(22)Date of filing:  19.06.2017
(51)International Patent Classification (IPC): 
F16H 7/08(2006.01)
F02B 67/06(2006.01)
(86)International application number:
PCT/US2017/038080
(87)International publication number:
WO 2018/009331 (11.01.2018 Gazette  2018/02)

(54)

ROTARY TENSIONER

DREHSPANNER

TENDEUR ROTATIF


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 06.07.2016 US 201615203389

(43)Date of publication of application:
15.05.2019 Bulletin 2019/20

(73)Proprietor: Gates Corporation
Denver, CO 80202 (US)

(72)Inventors:
  • LEUCHT, Volker
    52249 Eschweiler (DE)
  • MARTINEZ, Arnaud
    52064 Aachen (DE)
  • DILTHEY, Jochen
    52074 Aachen (DE)

(74)Representative: Carpmaels & Ransford LLP 
One Southampton Row
London WC1B 5HA
London WC1B 5HA (GB)


(56)References cited: : 
WO-A1-2013/142951
US-A- 4 698 049
WO-A1-2015/196268
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    Field of the Invention



    [0001] The invention relates to a tensioner, and more particularly, to a rotary tensioner having a rotary arm pivotally engaged with a base, a center of rotation of the rotary arm aligned with a base aperture center, a swing arm pivotally engaged with the rotary arm about a shaft, the shaft and swing arm each having a cooperating frustoconical portion, a bushing having a frustoconical portion in frictional engagement with the swing arm frustoconical portion.

    Background of the Invention



    [0002] Most internal combustion engines comprise accessories such as power steering, an alternator and air conditioning to name a few. These accessories are typically driven by a belt. A tensioner is typically used to apply a preload to the belt in order to prevent slippage. The tensioner can be mounted to an engine mounting surface

    [0003] The engine may further comprise a start-stop system whereby the engine will shut down when the vehicle is not in motion, and when a driver command is received to proceed the engine will restart.

    [0004] The start-stop function will tend to reverse loading on the belt. Hence, tensioners are available to accommodate belt load reversals. The tensioner may comprise one or more components which independently pivot in order to properly apply a required belt preload force in both belt drive directions. The tensioner may also be mounted directly to an accessory such as an alternator in order to save space in the engine bay.

    [0005] Representative of the art is WO2014/100894 which discloses a tensioner for tensioning an endless drive member that is engaged with a rotary drive member on a shaft of a motive device. The tensioner includes a base that is mountable to the motive device, a ring that is rotatably supported by the base in surrounding relationship with the shaft of the motive device and which is rotatable about a ring axis, a tensioner arm pivotally mounted to the ring for pivotal movement about an arm pivot axis, and first and second tensioner pulleys. The first tensioner pulley is rotatably mounted to the tensioner arm. The tensioner arm is biased towards a first span of the endless drive member on one side of the rotary drive member. The second tensioner pulley is rotatably mounted at least indirectly to the ring and is biased towards a second span of the endless drive member on another side of the rotary drive member. The ring is rotatable in response to hub loads in the first and second tensioner pulleys that result from engagement with the first and second spans of the endless drive member.

    [0006] WO 2015/196268 A1 discloses a tensioner for tensioning a belt that is engaged with a rotary drive member on a shaft of a motive device. The tensioner includes a base that is mountable to the motive device, a ring that is rotatably supported by the base in surrounding relationship with the shaft of the motive device and which is rotatable about a ring axis, a tensioner arm pivotally mounted to the ring for pivotal movement about an arm pivot axis, and first and second tensioner pulleys. The first tensioner pulley is rotatably mounted to the tensioner arm. The tensioner arm is biased towards a first span of the belt on one side of the rotary drive member. The second tensioner pulley is rotatably mounted at least indirectly to the ring and is biased towards a second span of the belt on another side of the rotary drive member. The ring is rotatable in response to hub loads in the first and second tensioner pulleys that result from engagement with the first and second spans of the belt.

    [0007] US 4,698,049 discloses a belt tensioner in which the bearing for mounting the pulley carrying pivoted structure on the fixed structure comprises a frustoconical sleeve bearing having a frustoconical exterior surface and a frustoconical interior surface engaged between annular portions of the two structures. The frustoconical surface of one of the annular portions is (1) formed on the exterior periphery thereof and (2) disposed in engagement with the interior bearing frustoconical surface.

    [0008] What is needed is a tensioner having a rotary arm pivotally engaged with a base, a center of rotation of the rotary arm aligned with a base aperture center, a swing arm pivotally engaged with the rotary arm about a shaft, the shaft and swing arm each having a cooperating frustoconical portion, a bushing having a frustoconical portion in frictional engagement with the swing arm frustoconical portion. The present invention meets this need.

    Summary of the Invention



    [0009] The primary embodiment of the invention is to provide a tensioner having a rotary arm pivotally engaged with a base, a center of rotation of the rotary arm aligned with a base aperture center, a swing arm pivotally engaged with the rotary arm about a shaft, the shaft and swing arm each having a cooperating frustoconical portion, a bushing having a frustoconical portion in frictional engagement with the swing arm frustoconical portion.

    [0010] Other embodiments of the invention will be pointed out or made obvious by the following description of the invention and the accompanying drawings.

    [0011] The present invention comprises a tensioner as recited in the claims.

    Brief Description of the Drawings



    [0012] The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the present invention, and together with a description, serve to explain the principles of the invention.

    Figure 1 is a top perspective view.

    Figure 2 is a bottom perspective view.

    Figure 3 is an exploded view.

    Figure 4 is a cross-sectional view.

    Figure 5 is a detail of Figure 1.

    Figure 6 is a perspective view of the device mounted to a driven component.


    Detailed Description of the Preferred Embodiment



    [0013] Figure 1 is a top perspective view. Rotary tensioner 1000 comprises a base 100, rotary arm 202, and swing arm tensioner 300.

    [0014] Base 100 comprises holes 101 for attaching the tensioner to a mounting surface such as an engine alternator (not shown). Each hole 101 receives a fastener such as a bolt (not shown) . Base 100 comprises an aperture 102. Aperture 102 has a large enough diameter to accommodate and encircle a driven component such as an alternator pulley (not shown). A drive belt (not shown) engages the driven component, see Figure 6.

    [0015] Rotary arm 202 comprises a first radial projection 210 and a second radial projection 211. Rotary arm 202 further comprises an aperture 209. Aperture 209 is a large enough diameter to accommodate a driven component such as an alternator pulley (not shown). Aperture 102 and aperture 209 are coaxial. Rotary arm 202 pivots about base 100 and thereby aperture 102, namely, rotary arm 202 has an axis of rotation A-A that is aligned with the center (B) of the base aperture 102. The rotary arm axis of rotation also aligns with the axis of rotation of a driven pulley, such as an alternator pulley (not shown).

    [0016] Pulley 201 is journalled to rotary arm 202 on projection 210 by a bearing 207. Pulley 201 engages a drive belt (not shown) which drives a driven engine accessory, for example, an alternator pulley. Bolt 208 secures bearing 207 to projection 210. Dust cover 212 prevents debris from entering bearing 207.

    [0017] Tensioner 300 comprises a swing arm 301. Swing arm 301 pivots about shaft 304. Shaft 304 can be press fit or threaded into projection 211 on pivot arm 301. Shaft 304 is disposed radially outward from the base aperture. Pulley 302 is journalled to swing arm 301 on bearing 310. Pulley 302 engages a drive belt (not shown). Torsion spring 303 urges swing arm 301 into contact with the drive belt (not shown), thereby applying a belt load. A belt load is advantageous to prevent belt slippage, wear and noise during operation. Pivotal movement of swing arm 301 is coordinated with rotary movement of rotary arm 202.

    [0018] In operation swing arm 301 presses on a drive belt thereby applying a belt load. The swing arm load also causes a reaction whereby pulley 201 presses on the drive belt by pivotal movement of rotary arm 202. Movement of swing arm 301 and rotary arm 202 allows the inventive device to accommodate various system and belt operating characteristics. Pulley 201 and pulley 302 are coplanar with a driven pulley (not shown).

    [0019] Figure 2 is a bottom perspective view. In operation a drive belt (not shown) engages a driven pulley such as an alternator pulley that projects through aperture 209. The drive belt also engages pulleys 201 and 302.

    [0020] Figure 3 is an exploded view. Shaft 304 comprises a frustoconical portion 304a. Bushing 305 is disposed between shaft 304 and swing arm 301. Bushing 305 comprises a frustoconical portion 305a.

    [0021] Bushing 305 is held in fixed relation to shaft 304 by tabs 305b on bushing 305 which engage slots 304b in shaft 304. Swing arm 301 pivots about shaft 304 on bushing 305. A frictional relation between bushing 305 and swing arm 301 acts to damp pivotal movement of swing arm 301. In an alternate embodiment bushing 305 is held in fixed relation to the pivot arm. In yet another embodiment bushing 305 is not held in fixed relation to either the pivot arm or the shaft.

    [0022] Damping ring 203 is disposed between base 100 and rotary arm 202. Damping ring 204 is disposed opposite damping ring 203. Member 205 holds damping ring 204 to base 100. Belleville spring 206 applies a compressive normal force to member 205 which in turn applies a normal force to each damping ring 203, 204. The normal force multiplied by the frictional coefficient between the damping rings and the base creates a frictional force which in turn damps movement of rotary arm 202. Belleville spring 206 is held in a compressed state due to a material deformation based assembly process applied to base 100, which in turn holds the tensioner together.

    [0023] Each tab 203a engages a receiving portion 213 of rotary arm 202. Each tab 204a also engages receiving portion 213 of rotary arm 202. Therefore, each damping ring 203 and 204 move in fixed relation to rotary arm 202. Surface 203c frictionally engages surface 104 of base 100. Surface 205a frictionally engages surface 204c.

    [0024] Pin 308 engages rotary arm portion 214 and pivot arm 301. Pin 308 holds pivot arm 301 in a predetermined position in order to facilitate installation of a drive belt (not shown). Pin 308 is then removed once installation of the tensioner and belt are complete and the system is put into operation.

    [0025] Figure 4 is a cross-sectional view. Shaft 304 comprises a frustoconical portion 304a. A conical angle θ is in the range of >0 degrees to <90 degrees. By way of example, the instant embodiment comprises a conical angle θ of approximately 30 degrees.

    [0026] Bushing portion 305a has a frustoconical shape to cooperatively match the form of portion 304a. Bushing 305 is disposed between pivot arm 301 and shaft 304. Pivot arm 301 pivots on bushing 305. Cap 309 is affixed to pivot arm 301 and acts as a seal to prevent debris from entering between bushing 305 and pivot arm 301.

    [0027] In operation torsion spring 303 is in axial compression which creates an axial spring force Fspr. The axial spring force presses surface 305c of bushing 305 into surface 301b of pivot arm 301. The resulting frictional force between surface 301b and surface 305c damps pivotal movement of pivot arm 301. Depending on the axial spring force and the shape of the frustoconical portion, the damping torque can have a wide range for example, +/-1 to +20Nm. The preferred range is approximately 1Nm to approximately 8Nm. By way of example, a 850N axial spring force and 30 degree conical angle with a 36mm maximum and 16mm minimum diameter of portion 305a and a coefficient of friction of 0.16 gives a damping torque of approximately +/- 3.7Nm. Numbers provided herein are by way of example and are not intended to limit the scope of the invention.

    [0028] The apex of angle Δ of the frustoconical portion 305a projects in the direction opposite the axial spring force vector Fspr. This orientation firmly engages the pivot arm frustoconical portion 301b with the shaft conical portion 304a. This in turn is the basis of the reaction force Fcr, a normal of which to surface 305c causes the frictional damping force between the bushing 305 and surface 301b. For example, in this embodiment the apex angle Δ is 60°. Apex angle Δ = 2 x θ.

    [0029] The frustoconical form enhances damping durability due to the enlarged surface area of the bushing portion 305a as compared to a purely cylindrical bushing. It also optimizes the use of axial force due to the wedge effect: Fn = Fspr(sin θ). Fn is the normal force on surface 305c. Fspr is the spring force. It also provides improved alignment of pivot arm 301 on shaft 304 which in turn results in improved alignment of pulley 302 with a drive belt.

    [0030] Figure 5 is a detail of Figure 1. Bolt 306 secures bearing 310 to swing arm 301. Dust shield 307 protects bearing 310 from debris. Each tab 305b engages a slot 304b to prevent movement of bushing 305.

    [0031] Figure 6 is a perspective view of the device mounted to a driven component. Tensioner 1000 is mounted to a driven component DC. Driven component DC comprises a pulley P. Driven component DC may comprise an alternator, starter-generator, or other vehicle engine component. Fasteners F fix tensioner 1000 to the driven component. A belt (not shown) engages pulley 201, pulley 302 and pulley P. The belt drives component DC through pulley P.


    Claims

    1. A tensioner comprising:

    a base (100) having a base aperture (102), the base aperture (102) disposed to receive a driven component;

    a rotary arm (202) pivotally engaged with the base (100), an axis of rotation of the rotary arm (202) aligned with a base aperture center, a first pulley (201) journalled to the rotary arm (202);

    a swing arm (301) pivotally engaged with the rotary arm (202) about a shaft (304), a torsion spring (303) biasing the swing arm (301), a second pulley (302) journalled to the swing arm (301); and

    a first damping ring (203) frictionally engaged between the rotary arm (202) and the base (100), a Belleville spring (206) in pressing engagement whereby a normal force is applied to the first damping ring (203); and characterised by:
    the shaft (304) and swing arm (301) each having cooperating frustoconical portions (304a, 301b), and further comprising:
    a bushing (305) having a frustoconical portion (305a) in frictional engagement with the swing arm frustoconical portion (301b), the bushing (305) in fixed relation to the shaft (304) or swing arm (301).


     
    2. The tensioner as in claim 1, wherein the shaft frustoconical portion (304a) comprises an apex angle Δ which projects in the direction opposite a torsion spring axial spring force vector Fspr.
     
    3. The tensioner as in claim 1 further comprising a second damping ring (204) frictionally engaged between the rotary arm (202) and the base (100), the second damping ring (204) disposed opposite the first damping ring (203) relative to a base frictional surface (104).
     
    4. The tensioner as in claim 1, wherein the rotary arm (202) comprises a rotary arm aperture (209) aligned with the base aperture (102).
     
    5. The tensioner as in claim 1, wherein the bushing (305) is held in fixed relation to the shaft (304).
     
    6. The tensioner as in claim 1, wherein the bushing (305) is held in fixed relation to the swing arm (301).
     
    7. The tensioner as in claim 1, wherein the first damping ring (203) is held in fixed relation to the rotary arm (202).
     
    8. The tensioner as in claim 3, wherein the second damping ring (204) is held in fixed relation to the rotary arm (202).
     
    9. The tensioner as in claim 1, wherein the first damping ring (203) is held in fixed relation to the base (100).
     
    10. The tensioner as in claim 3, wherein the second damping ring (204) is held in fixed relation to the base (100).
     
    11. The tensioner of claim 2, wherein:

    the base aperture (102) is disposed to encircle the driven component;

    the rotary arm (202) comprises a rotary arm (209) aperture aligned with the base aperture (102); and

    the bushing (305) is in fixed relation to the shaft (304).


     


    Ansprüche

    1. Spannvorrichtung, umfassend:

    eine Basis (100) mit einer Basisöffnung (102), wobei die Basisöffnung (102) zur Aufnahme einer Abtriebskomponente angeordnet ist,

    einen Dreharm (202), der mit der Basis (100) in Schwenkeingriff steht, wobei eine Rotationsachse des Dreharms (202) mit einer Basisöffnungsmitte fluchtet, wobei eine erste Riemenscheibe (201) an dem Dreharm (202) gelagert ist,

    einen Schwingarm (301), der um einen Schaft (304) in Schwenkeingriff mit dem Dreharm (202) steht, wobei eine Torsionsfeder (303) den Schwingarm (301) vorspannt, wobei eine zweite Riemenscheibe (302) an dem Schwingarm (301) gelagert ist, und

    einen ersten Dämpfungsring (203), der zwischen dem Dreharm (202) und der Basis (100) in Reibeingriff steht, wobei eine Tellerfeder (206) in Pressungseingriff steht, wodurch eine Normalkraft auf den ersten Dämpfungsring (203) ausgeübt wird, dadurch gekennzeichnet, dass

    der Schaft (304) und der Schwingarm (301) jeweils zusammenwirkende kegelstumpfförmige Abschnitte (304a, 301b) haben, und ferner umfassend:
    eine Buchse (305) mit einem kegelstumpfförmigen Abschnitt (305a) in Reibeingriff mit dem kegelstumpfförmigen Abschnitt (301b) des Schwingarms, wobei die Buchse (305) in feststehender Beziehung zu dem Schaft (304) oder dem Schwingarm (301) steht.


     
    2. Spannvorrichtung nach Anspruch 1, wobei der kegelstumpfförmige Abschnitt (304a) des Schafts einen Scheitelwinkel Δ umfasst, der in die Richtung ragt, die einem axialen Federkraftvektor Fspr der Torsionsfeder entgegengesetzt ist.
     
    3. Spannvorrichtung nach Anspruch 1, ferner umfassend einen zweiten Dämpfungsring (204) in Reibeingriff zwischen dem Dreharm (202) und der Basis (100), wobei der zweite Dämpfungsring (204) bezüglich einer Reibfläche (104) gegenüber dem ersten Dämpfungsring (203) angeordnet ist.
     
    4. Spannvorrichtung nach Anspruch 1, wobei der Dreharm (202) eine Dreharmöffnung (209) umfasst, die mit der Basisöffnung (102) fluchtet.
     
    5. Spannvorrichtung nach Anspruch 1, wobei die Buchse (305) in feststehender Beziehung zu dem Schaft (304) gehalten wird.
     
    6. Spannvorrichtung nach Anspruch 1, wobei die Buchse (305) in feststehender Beziehung zu dem Schwingarm (301) gehalten wird.
     
    7. Spannvorrichtung nach Anspruch 1, wobei der erste Dämpfungsring (203) in feststehender Beziehung zu dem Dreharm (202) gehalten wird.
     
    8. Spannvorrichtung nach Anspruch 3, wobei der zweite Dämpfungsring (204) in feststehender Beziehung zu dem Dreharm (202) gehalten wird.
     
    9. Spannvorrichtung nach Anspruch 1, wobei der erste Dämpfungsring (203) in feststehender Beziehung zu der Basis (100) gehalten wird.
     
    10. Spannvorrichtung nach Anspruch 3, wobei der zweite Dämpfungsring (204) in feststehender Beziehung zu der Basis (100) gehalten wird.
     
    11. Spannvorrichtung nach Anspruch 2, wobei:

    die Basisöffnung (102) dazu angeordnet ist, die Abtriebskomponente zu umgeben,

    der Dreharm (202) eine Dreharmöffnung (209) umfasst,

    die mit der Basisöffnung (102) fluchtet, und

    die Buchse (305) in feststehender Beziehung zu dem Schaft (304) steht.


     


    Revendications

    1. Tendeur, comprenant :

    une base (100) ayant une ouverture de base (102), l'ouverture de base (102) étant prévue pour recevoir un composant entraîné ;

    un bras rotatif (202) en prise pivotante avec la base (100), un axe de rotation du bras rotatif (202) étant aligné avec un centre de l'ouverture de base, une première poulie (201) étant tourillonnée sur le bras rotatif (202) ;

    un bras oscillant (301) en prise pivotante avec le bras rotatif (202) autour d'un arbre (304), un ressort de torsion (303) sollicitant le bras oscillant (301), une deuxième poulie (302) étant tourillonnée sur le bras oscillant (301) ; et

    une première bague d'amortissement (203) en prise de friction entre le bras rotatif (202) et la base (100), un ressort Belleville (206) étant en prise de pression moyennant quoi une force normale est appliquée à la première bague d'amortissement (203) ; et caractérisé par :
    le fait que l'arbre (304) et le bras oscillant (301) présentent chacun des portions tronconiques coopérantes (304a, 301b), et comprenant en outre :

    une douille (305) ayant une portion tronconique (305a) en prise de friction avec la portion tronconique du bras oscillant (301b), la douille (305) étant en relation fixe par rapport à l'arbre (304) ou au bras oscillant (301).


     
    2. Tendeur selon la revendication 1, dans lequel la portion tronconique de l'arbre (304a) comprend un angle au sommet Δ qui se projette dans la direction opposée à un vecteur de force de ressort axial Fspr du ressort de torsion.
     
    3. Tendeur selon la revendication 1, comprenant en outre une deuxième bague d'amortissement (204) en prise de friction entre le bras rotatif (202) et la base (100), la deuxième bague d'amortissement (204) étant disposée à l'opposé de la première bague d'amortissement (203) par rapport à une surface de friction de base (104).
     
    4. Tendeur selon la revendication 1, dans lequel le bras rotatif (202) comprend une ouverture de bras rotatif (209) alignée avec l'ouverture de base (102) .
     
    5. Tendeur selon la revendication 1, dans lequel la douille (305) est retenue en relation fixe par rapport à l'arbre (304).
     
    6. Tendeur selon la revendication 1, dans lequel la douille (305) est retenu en relation fixe par rapport au bras oscillant (301).
     
    7. Tendeur selon la revendication 1, dans lequel la première bague d'amortissement (203) est retenue en relation fixe par rapport au bras rotatif (202) .
     
    8. Tendeur selon la revendication 3, dans lequel la deuxième bague d'amortissement (204) est retenue en relation fixe par rapport au bras rotatif (202) .
     
    9. Tendeur selon la revendication 1, dans lequel la première bague d'amortissement (203) est retenue en relation fixe par rapport à la base (100).
     
    10. Tendeur selon la revendication 3, dans lequel la deuxième bague d'amortissement (204) est retenue en relation fixe par rapport à la base (100).
     
    11. Tendeur selon la revendication 2, dans lequel :

    l'ouverture de base (102) est disposée de manière à encercler le composant entraîné ;

    le bras rotatif (202) comprend une ouverture de bras rotatif (209) alignée avec l'ouverture de base (102) ; et

    la douille (305) est en relation fixe par rapport à l'arbre (304).


     




    Drawing




















    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description