Tensioner for accessory drive of motor vehicle and accessory drive comprising such tensioner
By designing a tensioner with a rotatable arm and a stop device, the problem of changes in belt tensioning requirements in the reversible motor operation mode is solved, and the effect of stable tensioning and noise reduction is achieved, which improves the installation and operation convenience of the accessory driver.
Patent Information
- Application Number
- CN202380087987.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-12-23
- Filing Date
- 2023-12-20
- Publication Date
- 2025-08-05
AI Technical Summary
In traditional accessory drives, the use of reversible motors causes changes in the tensioning requirements of belt spans under different operating modes, and existing tensioners are difficult to effectively adjust, especially during installation and operation, where there is a problem of too small or too large angle limits.
A tensioner is designed, including rotatable first and second arms, equipped with elastic means and a stop means, adjusting the angle between arms through removable stop elements, ensuring proper tension of the belt in different operating modes, and reducing noise and impact through elastic buffers.
The stable tension of the belt under different operating modes is achieved, the installation process is simplified, noise and vibration are reduced, and the comfort and reliability of the vehicle are improved.
Smart Images
Figure CN120435628A_ABST
Abstract
Description
[0001] CROSS-REFERENCE TO RELATED APPLICATIONS
[0002] This patent application claims the benefit of Italian Patent Application No. 102022000026778, filed on December 23, 2022, the disclosure of which is incorporated herein by reference in its entirety. Technical Field
[0003] The invention relates to a tensioner for an accessory drive of a motor vehicle and an accessory drive comprising such a tensioner. Background Art
[0004] As is well known, an accessory drive for a prime mover (e.g., an internal combustion engine) includes a first pulley connected to the engine drive shaft, a second pulley connected to the motor shaft, and may include one or more pulleys for driving other accessories (e.g., a compressor for an air conditioning system). The accessory drive also includes a belt for transmitting motion between the pulleys, and a tensioner for ensuring the correct minimum tension level of the belt and preventing slippage between the belt and the pulleys.
[0005] In a conventional accessory drive, the motor is an alternator (electric generator) driven by the engine, and the tensioner acts on the slack span of the belt, i.e., the span downstream of the engine and upstream of the alternator relative to the direction of movement of the belt.
[0006] In motor vehicles, reversible electric machines are increasingly used to replace conventional alternators, which, in addition to the conventional generator mode, can also be operated in other modes, for example as regenerative braking (the so-called "recovery" mode) or as an auxiliary motor acting in conjunction with the prime mover (the so-called "boost" mode).
[0007] Using a reversible motor means that under operating conditions where the motor is driven by the engine, the span of the belt is taut, and when the motor provides driving torque, the span of the belt becomes a slack span.
[0008] Therefore, various solutions have been developed to ensure correct tensioning of both spans of the belt.
[0009] For example, one solution is to use a double-arm tensioner with corresponding tensioning pulleys.
[0010] In particular, according to the known solution, the tensioner comprises: a base configured to be fixed to a fixed support structure; a first arm rotatable relative to the base about a first axis; a second arm rotatable relative to the second axis; a first tensioning pulley carried by the first arm and rotatable relative to the first arm about its own axis; a second tensioning pulley carried by the second arm and rotatable relative to the second arm about its own axis; elastic means acting on the first arm and the second arm for urging the first tensioning pulley and the second tensioning pulley into contact with the corresponding spans of the belt.
[0011] The first arm and the second arm define an angle relative to each other, and the magnitude of this angle is preferably limited to a maximum value. However, limiting this maximum value may result in significantly different requirements. In particular, when the first arm and the second arm must maintain a sufficient angular separation from each other to install a belt, the maximum value acceptable for use with the tensioner may be unacceptably small.
[0012] The object of the present invention is to create a tensioner for an accessory drive which overcomes the above-mentioned problems. Summary of the Invention
[0013] The above object is achieved by a tensioner for an accessory drive according to claim 1 .
[0014] The invention also relates to an accessory drive as claimed in claim 17 . BRIEF DESCRIPTION OF THE DRAWINGS
[0015] For a better understanding of the present invention, preferred embodiments are described below by way of non-limiting examples with reference to the accompanying drawings, in which:
[0016] Figure 1 is a front view schematic diagram of an accessory driver with a tensioner according to a first embodiment of the present invention;
[0017] Figure 2 yes Figure 1 An exploded perspective view of the tensioner;
[0018] Figure 3 yes Figure 1 A front view of the tensioner;
[0019] Figure 4 is a front view schematic diagram of details of a tensioner according to a second embodiment of the present invention;
[0020] Figure 5 is a front view schematic diagram of details of a tensioner according to a third embodiment of the present invention;
[0021] Figure 6 is a front view schematic diagram of details of a tensioner according to a fourth embodiment of the present invention; and
[0022] Figure 7 FIG. 4 is a schematic front view of details of a tensioner according to a fifth embodiment of the present invention. DETAILED DESCRIPTION
[0023] refer to Figure 1 , denoted by 1 as an accessory drive of a prime mover (eg, internal combustion engine 2 ).
[0024] The accessory drive 1 comprises a first pulley 3 connected to a drive shaft 4 of the engine 2 and a second pulley 5 connected to a shaft 6 of an electric motor 7. Optionally, the accessory drive comprises further pulleys for driving further accessories of the engine 2, for example a third pulley 11 connected to a shaft 12 of a compressor 13 of an air conditioning system.
[0025] The accessory drive 1 further comprises a belt 14 which is wound around the pulleys 3 , 5 , 11 and thus has a first span 14 a between the first pulley 3 and the second pulley 5 , a second span 14 b between the second pulley 5 and the third pulley 11 , and a third span 14 c between the third pulley 11 and the first pulley 3 .
[0026] The accessory drive 1 also includes a tensioner 15, which includes a base 16 configured to be fixed to a fixed support structure 17, a first arm 21 rotatable relative to the base 16 about a first axis A1, a second arm 22 rotatable about a second axis A2, a first tensioning pulley 31 carried by the first arm 21 and rotatable relative to the first arm 21 about its own axis PA1, and a second tensioning pulley 32 carried by the second arm 22 and rotatable relative to the second arm 22 about its own axis PA2.
[0027] The support structure 17 may be a bracket fixed to the engine 2 in the inner region of the belt 14 , or a part of the engine 2 in this region, or a housing of the electric motor 7 .
[0028] Preferably, the first axis A1 and the second axis A2 coincide with each other and define a common rotation axis A of the two arms 21, 22. Therefore, the first arm 21 and the second arm 22 are rotatable relative to the base 16 around the common axis A. Specifically, the first arm 21 and the second arm 22 are hinged to the base 16 around the common axis A.
[0029] The pulleys 31 and 32 are configured to cooperate with the spans 14a and 14b of the belt 14, respectively, and the spans 14a and 14b are arranged in the direction of advance of the belt 14 (refer to FIG. Figure 1 , clockwise) are respectively arranged upstream and downstream of the second pulley 5.
[0030] In particular, the tensioner 15 comprises elastic means 41 acting on the first and second arms 21 , 22 for urging the first and second pulleys 31 , 32 into contact with the respective spans 14 a , 14 b of the belt 14 .
[0031] Advantageously, the elastic means 41 comprise a helical torsion spring 42 by which the arms 21 , 22 are loaded towards each other, and the pulleys 31 , 32 are configured to cooperate with respective outer surfaces of respective spans 14 a , 14 b of the belt 14 .
[0032] The tensioner 15 further includes a stop device 51 configured to limit the angular distance between the first arm 21 and the second arm 22 .
[0033] In particular, such an angular distance ( Figure 3 ) corresponds to a convex angle θ defined by two half lines S1 and S2, which have a common origin on the axis A, are orthogonal to the axis A, and pass through PA1 and PA2 respectively.
[0034] The stop device 51 includes at least one removable stop element 52 (see below for details) so as to define a first maximum angular distance between the two arms 21, 22 in the installed configuration of the belt 14 (in which the removable stop element 52 is not present) and to define a second maximum angular distance, which is smaller than the first maximum angular distance, in the operating configuration of the accessory drive 1 (in which the removable stop element 52 is present).
[0035] Base 16( Figure 2 ) comprises a base plate 61 preferably in the shape of a disk having an axis A, and a tubular axial pivot 62 having an axis A fixed to the plate 61.
[0036] The first arm 21 and the second arm 22 are hinged to the pivot 62 via anti-friction radial bushings 63 .
[0037] The first arm 21 is provided with a hub 64 having a substantially circular end and a protruding circumferential edge 65 on its surface, which edge is configured, in use, to surround the plate 61 of the base 16. Extending from the hub 64, in particular on the axially opposite side with respect to the edge 65, is an axial tubular sleeve 66 which is rotatable on the bushing 63 and has the dual purpose of resisting the overturning moment and providing an anchor for the inner end 67 of the spring 42.
[0038] The second arm 22 is provided with a generally cup-shaped hub 71, which is hinged to the bushing 63 and forms, with the hub 64 of the first arm 21, an annular cavity for housing the spring 42 and radially delimited by a cylindrical wall 72 extending axially cantilevered from the second arm 22 to the first arm 21. The wall 72 defines an anchoring point for the outer end 73 of the spring 42.
[0039] The detent device 51 further includes a first radial protrusion 81 extending from the first arm 21 and a second radial protrusion 82 extending from the second arm 22 .
[0040] In particular ( Figure 3 ), consider a plane containing axis A and line B bisecting convex angle θ. This plane divides the space into a first half-space and a second half-space. The first half-space includes half-line S1 but not half-line S2, while the second half-space includes half-line S2 but not half-line S1. First protrusion 81 extends in the first half-space, and second protrusion 82 extends in the second half-space. Therefore, when the angular distance between pulleys 31 and 32 decreases under the action of spring 42, the angular distance between protrusions 81 and 82 increases, and vice versa.
[0041] Advantageously, the first protrusion 81 extends radially from the hub 64 and the second protrusion 82 extends radially from the wall 72 .
[0042] The tensioner 15 also includes: a friction-reducing ring 91, which is axially arranged between one side of the first arm 21 and one side of the second arm 22 and the spring 42 to minimize the relative friction between the first arm 21 and the second arm 22; an axial locking ring 92, which is fixed to the free end of the pivot 62 by plastic deformation of the pivot 62; a pair of annular elements 93, 94 made of plastic, one of which is axially arranged between the plate 61 of the base 16 and the first arm 21, and the other is arranged between the second arm 22 and the locking ring 92, for limiting the damping characteristics of the vibration of the arms 21, 22; a cup spring 95 is arranged between the second arm 22 and the annular element 94, for keeping the assembly in an axially stretched state and restoring the gap.
[0043] The pulleys 31, 32 are mounted for free rotation on the respective free ends 96, 97 of the arms 21, 22 via respective bearings (not shown).
[0044] The tensioner 15 may be mounted on the support structure 17 by screws 98 passing through the pivot 62. Preferably, the plate 61 of the base 16 has teeth (not shown) configured to engage corresponding seats of the support structure 17 to prevent the base 16 from rotating about the axis A.
[0045] In the first embodiment ( Figure 1 、 Figure 2 、 Figure 3 ), Second embodiment ( Figure 4 )、Third embodiment ( Figure 5 ) and the fourth embodiment ( Figure 6 ), the removable stop element 52 is stationary relative to the base 16 in the operating configuration.
[0046] Specifically, considering a generic first element and a generic second element, stating that the first element is "stationary" relative to the second element (in a configuration) is equivalent to stating that for every pair of points belonging to the first element and the second element respectively, the distance between these points is constant (in this configuration).
[0047] In the first embodiment ( Figure 1 、 Figure 2 、 Figure 3 ) and the fourth embodiment ( Figure 6 ), the removable stop element 52 comprises a pin 101 which can be fixed to the support structure 17.
[0048] In particular, the pin 101 comprises a hollow cylindrical element 102 having an axis P parallel to the axis A, which cylindrical element is fixable to the support structure 17 by removable connection means, for example a screw 103 having axis P passing through the cylindrical element 102 and engaging with a corresponding threaded hole of the support structure 17 .
[0049] Advantageously, pin 101 comprises an elastic cap 104 . Specifically, elastic cap 104 is shaped as a hollow cylinder having axis P and having an end 105 opposite head 106 of screw 103 , end 105 being in contact with plate 61 of base 16 .
[0050] In the second embodiment ( Figure 4 ) and the third embodiment ( Figure 5 ), the removable stop element 52 includes an attachment device 111 that can be fixed to the base 16.
[0051] In particular, the attachment device 111 comprises a stop portion 112 having opposite ends 113 , 114 arranged to face the respective protrusions 81 , 82 .
[0052] Advantageously, the stop portion 112 extends along a circumferential arc centered on the axis A.
[0053] In the second embodiment ( Figure 4 ), the attachment device 111 includes a fastening portion 121 extending along a radius connecting the stop portion 112 to the axis A.
[0054] In particular, the length of the fastening portion 121 is smaller than the radius of the attachment stop portion 112 to the axis A. In this way, interference between the fastening portion 121 and the screw 62 can be prevented. Preferably, the plate 61 of the base 16 has a seat configured to receive the fastening portion 121 and hold it in place, for example, by a positive coupling in the operating configuration.
[0055] In the third embodiment ( Figure 5 ), the attachment device 111 includes a pair of fastening portions 131 , 132 extending parallel to a radius connecting the stop portion 112 to the axis A. The fastening portions 131 , 132 extend from opposite sides relative to the axis A.
[0056] In particular, the length of each fastening portion 131, 132 is greater than the radius of the coupling stop portion 112 to the axis A. The distance between the fastening portions 131, 132 is greater than the diameter of the screw 62. In this way, interference between the fastening portions 131, 132 and the screw 62 can be prevented. Preferably, the plate 61 of the base 16 has a pair of seats configured to receive the respective fastening portions 131, 132 and hold them in place, for example, by a form-fitting connection in the operational configuration.
[0057] In the fourth embodiment ( Figure 6 ) and the fifth embodiment ( Figure 7 ), the removable stop element 52 is configured to be restricted to one of the two arms 21 , 22 .
[0058] In particular, the removable stop element 52 is stationary relative to the arms 21 , 22 to which it is constrained.
[0059] In the fourth embodiment ( Figure 6 ) and the fifth embodiment ( Figure 7 ), the removable stop element 52 is configured to be restricted to one of the protrusions 81 , 82 .
[0060] In particular, the removable stop element 52 is carried by the first projection 81 and extends along a circumferential arc centered on the axis A towards the second projection 82. Advantageously, the removable stop element 52 can be fixed to the first projection 81 by removable connecting means, for example a screw 141 extending orthogonally to the axis A and engaging with a corresponding threaded hole of the first projection 81.
[0061] In embodiments (not shown) corresponding respectively to the fourth and fifth embodiments, the removable stop element 52 is carried by the second projection 82 and extends along a circumferential arc centered on the axis A towards the first projection 81 .
[0062] Advantageously, the removable stop element 51 comprises a resilient buffer 151 .
[0063] In particular, the elastic buffer 151 is stationary relative to the removable stop element 52 .
[0064] In the first embodiment ( Figure 1 、 Figure 2 、 Figure 3 ) and the fourth embodiment ( Figure 6 ), the removable stop element 52 comprises an elastic cover 104, which can be used as an elastic buffer 151, in particular a cylindrical buffer.
[0065] In the second embodiment ( Figure 4 ) and the third embodiment ( Figure 5), the removable stop element 52 comprises two elastic buffers 151 , which are respectively carried by the corresponding ends 113 , 114 of the stop portion 112 of the attachment device 111 .
[0066] In the fifth embodiment ( Figure 7 ), the removable stopping element 52 includes an elastic buffer 151, which is stationary relative to the first arm 21, in particular relative to the first protrusion 81, and is arranged facing the second protrusion 82.
[0067] In an embodiment corresponding to the fifth embodiment (not shown), the removable stop element 52 comprises a resilient buffer 151 which is stationary relative to the second arm 22 , in particular relative to the second protrusion 82 , and is arranged facing the first protrusion 81 .
[0068] Advantageously, the tensioner 15 comprises an elastic buffer 161 configured to cooperate with the removable stop element 52 .
[0069] In the fourth embodiment ( Figure 6 ), the pin 101 of the tensioner 15 includes an elastic cover 104, which can be used as an elastic buffer 161, in particular a cylindrical buffer, and is configured to cooperate with a removable stop element 52 constrained on the first arm 21 (in particular constrained on the first protrusion 81).
[0070] In a further embodiment (not shown), the tensioner 15 includes a resilient buffer 161 that is constrained to the first arm 21, for example, to the first protrusion 81, and is configured to cooperate with a removable stop element 52 that is stationary relative to the base 16 or the second arm 22, and / or the tensioner 15 includes a resilient buffer 161 that is constrained to the second arm 22, for example, to the second protrusion 82, and is configured to cooperate with a removable stop element 52 that is stationary relative to the base 16 or the first arm 21.
[0071] Advantageously, when the removable stop element 52 is absent, the angular distance between the two arms 21, 22 is less than or equal to the first maximum angular distance. To this end, corresponding elements can be used that are stationary relative to the arms 21, 22 and are configured to define the first maximum angular distance when these elements cooperate with each other. For example, these elements can be protrusions 81, 82, which are angularly arranged such that when the protrusions 81, 82 contact each other, the angular distance between the two arms 21, 22 is equal to the first maximum angular distance.
[0072] The first maximum angular distance between the two arms 21 , 22 is such that the corresponding deformation of the spring 42 is less than the yield point.
[0073] Advantageously, the removable stop element 52 is sized to take into account the element or elements with which it cooperates in the operative configuration.
[0074] In particular, in the operating state, the axial dimensions of the removable stop element 52 (e.g., the pin 101 and the attachment 111) stationary relative to the base 16 are set, for example, to act on the axial length of the pin 101 and the axial extension of the stop portion 112 of the attachment 111, respectively, while taking into account the axial extension of the arms 21, 22, in particular the axial extension of the protrusions 81, 82, wherein the removable stop element 52 is circumferentially arranged to the protrusions 81, 82. The removable stop element 52 is configured to be restrained on one of the two arms 21, 22, in particular on one of the protrusions 81, 82, and its axial dimensions take into account the other of the two arms 21, 22, in particular the other of the protrusions 81, 82.
[0075] Advantageously, the removable stop element 52 is dimensioned so that when it cooperates with the element or elements with which it is configured to cooperate in the operational configuration, the angular distance between the two arms 21 , 22 is equal to a second maximum angular distance which is smaller than the first maximum angular distance.
[0076] In particular, in the operating state, the angular dimensions of the removable stop element 52 (e.g., the pin 101 and the attachment 111) stationary relative to the base 16 are set, for example, to act on the diameter of the pin 101 and the angular extension of the stop portion 112 of the attachment 111, respectively, while taking into account the angular distance of the protrusions 81, 82, wherein the removable stop element 52 is arranged circumferentially to the protrusions 81, 82. The removable stop element 52 is configured to be restricted to one of the two arms 21, 22, in particular to one of the protrusions 81, 82, and its angular dimensions are determined taking into account the angular distance of the protrusions 81, 82.
[0077] Advantageously, the first arm 21 and / or the second arm 22 have a characteristic configured to define a minimum angular distance between the two arms 21, 22, regardless of the presence of the belt 14 and the presence of the removable stop element 52. For example, one of the two arms 21, 22 has a protrusion (not shown) along its portion axially intersecting the convex angle θ, the protrusion extending axially toward the other of the two arms 21, 22 and configured to cooperate therewith and overcome the action of the spring 42 to define an angular stop corresponding to the minimum angular distance between the two arms 21, 22.
[0078] The minimum angular distance between the two arms 21 , 22 is such that the pulleys 31 , 32 do not touch each other.
[0079] The operation of the tensioner 15 is as follows.
[0080] After the tensioner 15 is assembled, the arms 21, 22 are loaded towards each other by the spring 42. Advantageously, the angular distance between the two arms 21, 22 is not less than a minimum angular distance, so that the pulleys 31, 32 do not touch each other.
[0081] Tensioner 15 is mounted to support structure 17 via screws 98. The present configuration represents the installation configuration of belt 14 without the removable stop element 52. Consequently, arms 21, 22 can be spaced angularly apart from each other until a first maximum angular distance is reached. This allows belt 14 to be easily installed with pulleys 31, 32 positioned outside respective spans 14a, 14b while preventing spring 42 from yielding.
[0082] After the belt 14 is installed, the tensioner 15 is brought into a nominal position under the action of the spring 42 , which is defined by the balance between the tension of the belt 14 and the restoring force of the spring 42 .
[0083] Subsequently, the removable retaining element 52 is inserted. For example, the pin 101 is fixed to the support structure 17 by means of screws 103, the attachment device 111 is fixed to the base 16, or the removable retaining element 52 is restrained to one of the two arms 21, 22 by means of screws 141. The present configuration is the operating configuration of the accessory drive 1, in which the removable retaining element 52 is present.
[0084] Under normal operating conditions, the engine 2 provides driving torque, and the motor 7 is driven and operates as an AC generator. At this time, the span 14a of the belt 14 is a slack span, and the span 14b of the belt 14 is a taut span.
[0085] Under the urging force of the spring 42, the pulleys 31 and 32 tend to approach each other, with the pulley 31 acting on the slack span 14a to maintain a predetermined minimum tension value therein as the torque changes.
[0086] In boost mode, the motor 7 provides a driving force (positive torque) that is added to the driving force of the engine 2. This tends to reduce the tension in the span 14b of the belt 14 and increase the tension in the span 14a of the belt 14. Conversely, in recovery mode, the motor 7 absorbs mechanical power (negative torque), so the tension in the span 14a of the belt 14 tends to decrease.
[0087] Due to the presence of the removable stop element 52, the angular distance between the two arms 21, 22 can be no greater than the second maximum angular distance and less than the first maximum angular distance. This can limit the travel of the arms 21, 22 and the impact energy generated by their possible collision with the removable stop element 52. This energy is further absorbed by the elastic buffers 151, 161, thereby reducing noise.
[0088] By examining the characteristics of the tensioner 15, the advantages of the present invention become apparent.
[0089] In particular, the stop device 51 can improve the installation configuration of the belt 14 (in which the removable stop element 52 is not present) and the operating configuration of the accessory drive 1 (in which the removable stop element 52 is present). A first maximum angular distance between the two arms 21, 22 and a second maximum angular distance, which is smaller than the first maximum angular distance, can be defined and easily switched by the presence and absence of the removable stop element 52. This simplifies the installation of the belt 14 when the tensioner 15 is not in use and the removable stop element 52 is not present, and limits stresses and potential impacts when the tensioner 15 is in use and the removable stop element 52 is present, thereby improving vehicle comfort indicators such as noise, vibration, and harshness (NVH).
[0090] As in the fourth embodiment ( Figure 6 ), the tensioner 15 may include two removable stop elements 52. Thus, it is possible to act only on one removable stop element, only on the other removable stop element, or on both removable stop elements 52, thereby increasing the possibilities of choice and the final results that can be achieved.
[0091] Finally, it is obvious that modifications and variations may be made to the tensioner 15 without departing from the scope of protection defined by the claims.
[0092] For example, the internal combustion engine may be replaced by a prime mover of a different nature (eg, an electric motor).
[0093] The first axis A1 and the second axis A2 may be different from each other. For example, the first axis A1 may be stationary relative to the base 16, while the second axis A2 may be stationary relative to the first arm 21. In this case, the second arm 22, which is rotatable about the second axis A2, is rotatable relative to the first arm 21 and is preferably carried by the first arm 21.
[0094] The first arm 21 and the second arm 22 may be substantially annular.
[0095] The removable stop element 52 may be a radial protrusion extending from one of the two arms 21 , 22 .
Claims
1. A tensioner for an accessory drive of a prime mover (2), the accessory drive (1) comprising at least one first pulley (3) connected to a drive shaft (4) of the prime mover (2), at least one second pulley (5) connected to a motor (7), and a belt (14) wound around at least the first pulley (3) and the second pulley (5), the tensioner (15) comprising: a base (16) configured to be fixed to a fixed support structure (17); a first arm (21) rotatable relative to the base (16) about a first axis (A1); a second arm (22) rotatable about a second axis (A2); a first tensioning pulley (31), carried by the first arm (21) and rotatable relative to the first arm (21) about its own axis (PA1); a second tensioning pulley (32) carried by the second arm (22) and rotatable relative to the second arm (22) about its own axis (PA2); elastic means (41) acting on the first arm (21) and the second arm (22) to urge the first tensioning pulley (31) and the second tensioning pulley (32) into contact with the respective spans (14a, 14b) of the belt (14); and a stopper (51) configured to limit the angular distance between the first arm (21) and the second arm (22); Characterized in that the stop device (51) includes at least one removable stop element (52) so as to define a first maximum angular distance between the two arms (21, 22) in the installed configuration of the belt (14) and a second maximum angular distance smaller than the first maximum angular distance in the operating configuration of the accessory drive (1), wherein the removable stop element (52) is not present in the installed configuration of the belt (14) and is present in the operating configuration of the accessory drive (1).
2. The tensioner according to claim 1, wherein: The first axis (A1) and the second axis (A2) coincide and define a common axis of rotation (A) of the two arms (21, 22).
3. The tensioner according to claim 1 or 2, wherein: The stopper (51) includes a first protrusion (81) extending radially from the first arm (21) and a second protrusion (82) extending radially from the second arm (22).
4. A tensioner according to any one of the preceding claims, wherein: The removable stop element (52) is configured to be captured on one of the two arms (21, 22).
5. The tensioner according to claim 3 or 4, wherein: The removable stop element (52) is configured to be captured to one of the protrusions (81, 82).
6. The tensioner according to any one of claims 1 to 3, wherein: The removable stop element (52) is stationary relative to the base (16) in the operative configuration.
7. A tensioner according to any one of the preceding claims, wherein: The removable stop element (52) comprises a resilient buffer (151).
8. The tensioner according to any of the preceding claims, comprising a resilient buffer (161) configured to cooperate with the removable stop element (52).
9. The tensioner according to any one of claims 6 to 8, wherein: The removable stop element (52) comprises a pin (101) fixable to the support structure (17).
10. The tensioner according to claim 9, wherein: The pin (101) includes a resilient cover (104).
11. The tensioner according to any one of claims 6 to 8, wherein: The removable retaining element (52) comprises an attachment device (111) which is fixable to the base (16).
12. The tensioner according to claims 3 and 11, wherein The attachment device (111) comprises a stop portion (112) having opposite ends (113, 114) arranged to face the respective protrusions (81, 82).
13. The tensioner according to claims 2 and 12, wherein: The attachment device (111) includes a fastening portion (121) extending along a radius connecting the stop portion (112) to the common axis (A).
14. The tensioner according to claim 13, wherein: The length of the fastening portion (121) is less than the radius connecting the stop portion (112) to the common axis (A).
15. The tensioner according to claims 2 and 12, wherein: The attachment device (111) includes a pair of fastening portions (131, 132) extending parallel to a radius connecting the stop portion (112) to the common axis (A), the fastening portions (131, 132) extending from opposite sides relative to the common axis (A).
16. The tensioner according to claim 15, wherein The length of each fastening portion (131, 132) is greater than the radius connecting the stop portion (112) to the common axis (A).
17. An accessory drive for a prime mover (2), comprising: At least one first pulley (3) connected to the drive shaft (4) of the prime mover (2); at least one second pulley (5) connected to the motor (7); a belt (14) wound around at least the first pulley (3) and the second pulley (5); and a tensioner (15) according to any of the preceding claims.