Torque limiter, transmission assembly and corresponding use
The torque limiter design with inner and outer holding elements and truncated cone surfaces addresses complexity and cost issues, enabling high torque transmission and easy re-engagement, ensuring efficient operation and maintenance.
Patent Information
- Application Number
- FR2023008177
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-07-26
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2043-07-26
AI Technical Summary
Existing torque limiters are complex and expensive, with relatively low transmission limit forces for given dimensions, and lack the ability to adjust the limit torque with low means and low tolerance.
A torque limiter design featuring inner and outer limiting holding elements with complementary truncated cone-shaped contact surfaces, allowing for a simple construction that maintains engagement below a limit torque and yields above it, using cartridges and pistons for easy adjustment and re-engagement.
The design achieves high limit torque transmission with adjustable settings, reducing complexity and cost while preventing damage by allowing free rotation when torque exceeds the limit, facilitating easy re-engagement and maintenance.
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Abstract
Description
Title of the invention: Torque limiter, transmission assembly and corresponding use
[0001] The present invention relates to a torque limiter, of the type comprising a first body, and a second body, the first body and the second body extending around a central axis, the first body carrying a first limiter toothing, the second body carrying a second limiter toothing, complementary to the first limiter toothing, the first limiter toothing and second limiter toothing defining an engaged configuration in which the first limiter toothing and second limiter toothing are adapted to transmit a rotational torque around the central axis of the first body to the second body and a release configuration, in which the first limiter toothing and second limiter toothing are incapable of transmitting a rotational torque between the first body and the second body,the torque limiter also comprising locking means adapted to oppose a transition of the first limiter toothing and the second limiter toothing from their release configuration to their engaged configuration, and limitation holding means adapted to maintain the first limiter toothing and the second limiter toothing in their engaged configuration when the rotational torque is less than a limit transmission torque and adapted to yield when the rotational torque exceeds the limit transmission torque.
[0002] Torque limiters are known that are adapted to limit the torque transmitted between a driving shaft and a driven shaft. A torque limiter is for example known from US9086096B2. This torque limiter comprises pistons that are radially movable relative to the central axis of the driving and driven shafts. These pistons are biased radially inwards by springs.
[0003] Another torque limiter is marketed by the company Ringspann ® under the name “SIKUMAT” ® SU. This torque limiter comprises balls arranged in axial housings and locked in abutment by Belleville springs. When the limit torque is reached, the balls slide out of their housing and roll to the next housing, repeating this process until the torque falls below the limit torque.
[0004] These torque limiters are relatively complex and therefore expensive. In addition, these torque limiters have relatively low transmission limit forces for given dimensions.
[0005] The aim of the invention is to propose a torque limiter which is of simple construction and which makes it possible to transmit a high limit torque for dimensions data. Another object of the invention is to provide a torque limiter which allows the limit torque to be adjusted with low means and preferably with a low tolerance.
[0006] For this purpose, the invention relates to a torque limiter as indicated above, characterized in that the limiting holding means comprise at least one inner limiting holding element having an outer contact surface, and at least one outer limiting holding element having an inner contact surface complementary to the outer contact surface, the inner and outer limiting holding elements having a holding configuration, in which the inner limiting holding element is clamped in the outer limiting holding element, and a yielded configuration in which the inner limiting holding element is loosened from the outer limiting holding element.
[0007] According to particular embodiments of the torque limiter, the latter may comprise one or more of the following characteristics:
[0008] - the outer contact surface is of truncated cone shape of revolution and in which inner contact surface is of truncated cone shape of revolution, in particular in which the opening angle (a) of the outer and inner contact surfaces is between 1° and 20°;
[0009] - the limitation maintaining means comprise at least one cartridge, each cartridge comprising one of the at least one outer limiting holding element and one of the at least one inner limiting holding element,
[0010] the outer limiting holding element is a sleeve, and
[0011] the internal limiting holding element is a punch provided with a piston, in part in particular the piston being adapted to extend through an opening in the cartridge opening cover;
[0012] - when the inner limiting holding element and the li holding element outer limitation are in the yielded configuration, the inner limiting holding element is offset along the central axis relative to the outer limiting holding element relative to their holding configuration;
[0013] - in their engaged configuration, the first toothing and the second toothing apply one to the other;
[0014] - the torque limiter comprises
[0015] - a first coupling flange fixed to the first body and provided with a first coupling teeth, and
[0016] - a second coupling flange fixed to the second body and provided with a second coupling teeth, and
[0017] the first coupling toothing is adapted to cooperate with a complementary coupling toothing, and
[0018] the second coupling toothing is adapted to cooperate with a complementary coupling toothing;
[0019] - either the second limiter toothing is fixed relative to the second body, or the second limiter toothing comprises tooth inserts axially movable relative to the second body between the engaged configuration and the release configuration; and
[0020] - the second body comprises two axially movable body parts, one by relative to each other and fixed in rotation relative to each other around the central axis.
[0021] The invention also relates to a transmission assembly, of the type comprising a driving shaft, a driven shaft, and a torque limiter, characterized in that the torque limiter is a torque limiter as defined above, in that the first body is fixed in rotation to the driving shaft, and the second body is fixed in rotation to the driven shaft.
[0022] According to particular embodiments of the transmission assembly, the latter may comprise one or more of the following characteristics:
[0023] the driving shaft comprises complementary coupling teeth and the driven shaft comprises complementary coupling teeth and the torque limiter is a torque limiter as defined above.
[0024] The invention also relates to a use of a transmission assembly as defined above, comprising the following successive steps:
[0025] providing the transmission assembly, the inner and outer limiting holding elements being in their assigned configuration; and
[0026] placing the inner and outer limiting holding members in their holding configuration by applying the outer contact surface to the inner contact surface, clamping the inner limiting holding member into the outer limiting holding member.
[0027] According to particular embodiments of the use of the transmission assembly, the latter may comprise one or more of the following characteristics:
[0028] the use further comprises the following successive steps, implemented after the step of placing the inner and outer limiting holding elements in their holding configuration:
[0029] - exceeding the limit transmission torque, thus causing the confi release configuration of the first limiter teeth and second limiter teeth,
[0030] - re-engagement of the torque limiter by placing the retaining elements of inner and outer limiting in their holding configuration by applying the outer contact surface to the inner contact surface, thereby clamping the inner limiting holding member into the outer limiting holding member.
[0031] The invention will be better understood upon reading the following description, given solely by way of example and made with reference to the accompanying drawings, in which:
[0032] [Fig.l] [Fig.l] shows a schematic view of an installation comprising a transmission assembly according to a first embodiment of the invention provided with a torque limiter, the torque limiter being in an engaged configuration;
[0033] [Fig.2] [Fig.2] shows the installation of [Fig.l], the torque limiter being in a release configuration;
[0034] [Fig.3] [Fig.3] shows a radial view of a portion of the torque limiter of the [Fig.l];
[0035] [Fig.4] [Fig.4] shows the radial view of a part of the torque limiter of the [Fig.2], the view corresponding to that of [Fig.3];
[0036] [Fig.5] [Fig.5] schematically shows a transmission assembly according to a second embodiment of the invention, the torque limiter being in the engaged configuration;
[0037] [Fig.6] [Fig.6] schematically shows a transmission assembly according to a third embodiment of the invention, the torque limiter being in the release configuration; and
[0038] [Fig.7] [Fig.7] schematically shows a transmission assembly according to a fourth embodiment of the invention, the torque limiter being in the engaged configuration;
[0039] [Fig.8] [Fig.8] shows the transmission assembly of [Fig.7], the limiter of couple being in the release configuration;
[0040] [Fig.9] [Fig.9] shows a radial view of a portion of the torque limiter of the [Fig.7] ;
[0041] [Fig. 10] [Fig. 10] shows the radial view of a part of the torque limiter of the [Fig.8], the view corresponding to that of [Fig.9].
[0042] In the following, the term "fixed" or "fixed" without further specification is used to designate a connection without any degree of freedom. The term "fixed" or "fixed" with the indication of the degree of freedom concerned is used to generally designate a connection fixed with respect to the degree of freedom indicated and free or not with respect to the other degrees of freedom. The person skilled in the art knows how to remove the degrees of freedom in order to arrive at a device having the necessary degrees of freedom.
[0043] [Fig. 1] shows a schematic view of an installation according to the invention designated by the general reference 2. The installation 2 comprises a driving device 4, such as a motor M, and a driven device 6, such as a reducer R or a grinder. The installation 2 comprises a transmission assembly 8 according to the invention connecting the driving device 4 to the driven device 6 for the purpose of driving it.
[0044] The transmission assembly 8 comprises a drive shaft 10, a driven shaft 12, and a torque limiter 14 connecting the drive shaft 10 to the driven shaft 12. The drive shaft 10 is for example the output shaft of the driving device 4 and the driven shaft 12 is for example the input shaft of the driven device 6. The driving shaft 10 is in this case an axially fixed shaft, while the driven shaft 12 is an axially movable shaft.
[0045] The torque limiter 14 is adapted to transmit a rotational torque from the drive shaft 10 to the driven shaft 12 when the rotational torque is less than a limit transmission torque. The torque limiter 14 is adapted to yield when the rotational torque reaches or exceeds the limit transmission torque and thus to allow free rotation of the drive shaft 10 relative to the driven shaft 12 when the rotational torque reaches or exceeds this limit transmission torque.
[0046] The torque limiter 14 defines a central axis XX, which is in this case coaxial with the driving shaft 10 and the driven shaft 12. Unless otherwise indicated, the expressions “axial”, “radial” and “circumferential” are used with respect to this central axis XX.
[0047] The torque limiter 14 is provided with a first body 18 and a second body 20, the first body and the second body extending around the central axis XX and being centered on this central axis XX.
[0048] The first body 18 is in this case an axially fixed body. The first body 18 is fixed axially, radially and circumferentially to the drive shaft 10.
[0049] The second body 20 is in this case an axially movable body. The second body 20 is fixed axially, radially and circumferentially to the driven shaft 12. The driven shaft 12, and therefore the second body 20, is axially movable relative to the drive shaft 10 and relative to the first body 18.
[0050] Generally speaking, the terms "axially fixed body" and "axially movable body" mean, in the context of the present invention, that the axial mobility of the axially movable body is greater than the axial mobility of the axially fixed body in order to allow the release configuration to be taken (see below). This axial mobility can be obtained by different technical means.
[0051] The first body 18 comprises in the present case a first fixing flange 22 to the driving shaft 10, a first connecting flange 24, an outer skirt 26, and a support ring 27. The first connecting flange 24 is axially arranged between the first connecting flange 22 and the outer skirt 26. The support ring 27 is fixed to the outer skirt 26. The shape of the first body 18 can vary from the shape of this first embodiment.
[0052] The first body 18 carries a first limiter toothing 28, in this case an axial toothing, and in this case fixed to the first connecting flange 24.
[0053] The second body 20 comprises in the present case a second fixing flange 30 to the driven shaft 12, a second connecting flange 32 and a thrust surface 34.
[0054] The second body 20 carries a second limiter toothing 36, in this case an axial toothing, and in this case fixed to the second connecting flange 32. In this case, the first and second limiter toothings 28, 36 each form a toothed ring whose teeth project axially. The first limiter toothing 28, respectively the second limiter toothing 36 may be integral with the first body 18, respectively with the second body 20 or be one or more separate parts.
[0055] The second limiter toothing 36 is complementary to the first limiter toothing 28. The first limiter toothing 28 and second limiter toothing 36 define an engaged configuration ([Fig.l]) in which the first limiter toothing 28 and second limiter toothing 36 are adapted to transmit a rotational torque about the central axis XX of the first body 18 to the second body 20. In this engaged configuration, during a rotation of the first body 18 about the central axis XX, the first limiter toothing 28 and second limiter toothing 36 transmit the rotational torque about the central axis XX of the first body 18 to the second body 20. This configuration is shown in Figures 1 and 3.
[0056] In the engaged configuration, the first limiter toothing 28 and the second limiter toothing 36 are applied to each other, that is to say, without the interposition of a limiting body. In the engaged configuration, the surface of the first limiter toothing 28 is therefore in contact with the surface of the second limiter toothing 36.
[0057] The first limiter teeth 28 and second limiter teeth 36 define a release configuration, in which these first limiter teeth 28 and second limiter teeth 36 are incapable of transmitting a rotational torque between the first body and the second body and therefore make the first body 18 and the second body 20 free to rotate relative to each other. In this release configuration, the first and second limiter teeth 28, 36 are axially spaced apart and apart from each other. This release configuration is shown in Figures 2 and 4.
[0058] The first and second limiter teeth 28, 36 are adapted to generate an axial force urging the first body 18 and the second body 20 from their engaged configuration to their release configuration under the effect of the transmitted torque. For this purpose, the flanks of the teeth of the first and second limiter teeth 28, 36 are for example oblique with respect to all the planes comprising the central axis XX. In this case, when a torque is transmitted, the second limiter tooth 36 is urged to the right in [Fig.l].
[0059] The first body 18 and the second body 20 define, in the present embodiment, an engaged configuration respectively a release configuration which correspond to the engaged configuration respectively to the release configuration. beration of the first and second teeth 28, 36.
[0060] The torque limiter 14 further comprises guide means 37 adapted to guide, and in particular guiding, the first body 18 relative to the second body 20 in rotation around the central axis XX when the first limiter toothing 28 and second limiter toothing 36 are in their release configuration.
[0061] In the present case, the guide means 37 are also adapted to guide the first body 18 relative to the second body 20 axially along the central axis XX and in rotation about the central axis XX when the first body 18 and the second body 20 are in their release configuration. In this case, these guide means 37 are schematically represented as complementary cylindrical bearing surfaces with a circular section. These guide means 37 have in this case axial freedom and allow an offset of the first body 18 relative to the second body 20 between their release configuration and their engaged configuration.
[0062] The torque limiter 14 further comprises locking means 38 adapted to oppose a transition of the first limiter toothing 28 and the second limiter toothing 36 from their release configuration to their engaged configuration. The locking means 38 are releasable.
[0063] In this case, these locking means 38 are adapted to oppose the transition of the first body 18 and the second body 20 from their release configuration to their engaged configuration.
[0064] These locking means 38 prevent untimely engagement of the engaged configuration of the first limiter toothing 28 and the second limiter toothing 36, and therefore in this case of the first body 18 and the second body 20.
[0065] In this case, the locking means 38 comprise means for urging the first body 18 and the second body 20 from their engaged configuration into their release configuration. These urging means comprise, for example, a spring 40, in particular arranged in a bore of the first body 18, pushing the first body and the second body 20 axially away from each other, in this case via a thrust cylinder 42.
[0066] In a variant not shown, the locking means 38 may comprise other locking elements, such as locking balls subjected to thrust springs, engaging in hollows, or even magnets cooperating with ferromagnetic parts.
[0067] The torque limiter 14 further comprises limitation holding means 44 for holding the first limiter toothing 28 and the second limiter toothing 36 in their engaged configuration when the rotational torque is less than a limit transmission torque and adapted to yield when the rotational torque exceeds the limit transmission torque. In this case, these limitation holding means limiting means 44 are adapted to maintain the first body 18 and the second body 20 in their engaged configuration when the rotational torque is less than the limit transmission torque and this against the axial force generated by the first limiter teeth 28 and second limiter teeth 36. Optionally, these limiting holding means 44 are further adapted to maintain the first body 18 and the second body 20 in their engaged configuration against the force of the locking means 38, although this force is generally negligible. The limiting holding means 44 are adapted to yield, and do yield, when the rotational torque reaches or exceeds the limit transmission torque. The limiting holding means 44 therefore define a yielding force which corresponds to the axial force generated by the first limiter teeth 28 and second limiter teeth 36 when the limit transmission torque is reached or exceeded.Where appropriate, the yield force additionally corresponds to the axial force of the locking means 38.
[0068] The limitation holding means 44 comprise at least one inner limitation holding element 50 and at least one outer limitation holding element 52, complementary to the inner limitation holding element 50.
[0069] In the following, a set of holding elements consisting of a single inner limiting holding element 50 and a single outer limiting holding element 52 will be described.
[0070] The inner limiting holding element 50 has an outer contact surface 56 and the outer limiting holding element 52 has an inner contact surface 58 complementary to the outer contact surface 56.
[0071] The inner limiting holding element 50 is therefore a male element and the outer limiting holding element 52 is a female element.
[0072] The inner 50 and outer 52 limiting holding elements have a holding configuration, in which the inner limiting holding element 50 is tightened, in particular by friction, in the outer limiting holding element 52 ([Fig.l]) and a yielded configuration in which the inner limiting holding element 50 is loosened from the outer limiting holding element ([Fig.2]).
[0073] All the inner limiting holding elements 50 and outer limiting holding elements 52 define, by their holding configuration, the yield force.
[0074] In the holding configuration, the outer limiting holding element 52 is only elastically deformed relative to the yielded configuration.
[0075] The inner 50 and outer 52 limiting holding elements are adapted to assume the holding configuration and the yielded configuration reversibly.
[0076] The inner limiting holding element 50 is preferably made of steel, in particular high-alloy steel. The outer limiting holding element 52 is preferably made of steel, especially high-alloy steel. The inner limiting holding element 50 and the outer limiting holding element 52 may have undergone a surface treatment, such as nitriding or carburizing.
[0077] In Figures 1 and 2, two sets of holding elements and thus two inner limiting holding elements 50 and two outer limiting holding elements 52 are shown. The number of inner limiting holding elements 50 and outer limiting holding elements 52 is a function of the required limit transmission torque and the maximum transmission force capacity of each set of holding elements.
[0078] Generally, the number of sets of holding elements can be between 6 and 36, in particular between 8 and 24.
[0079] In this case and preferably, the outer contact surface 56 is of a frustoconical shape of revolution. Similarly, the inner contact surface 58 is of a frustoconical shape of revolution. These truncated cones extend along a cone axis AA which extends parallel to the central axis XX.
[0080] The opening angle a of the outer 56 and inner 58 contact surfaces is between 1° and 20°, and preferably between 2° and 10°. The opening angle a is measured relative to the cone axis AA. The opening angles a of the outer and inner contact surfaces are preferably identical. The outer 56 and inner 58 contact surfaces flare in the direction from the engaged configuration to the release configuration (to the right in [Fig.l]).
[0081] In the holding configuration, the inner limiting holding element 50 is held in the outer limiting holding element 52 by static friction. In other words, in the holding configuration, this static friction opposes the assumption of the yielded configuration.
[0082] When the outer limiting holding element 52 begins to yield, the contact with the inner limiting holding element 50 transforms into a sliding friction contact, and therefore having a coefficient of friction lower than the coefficient of static friction, combined with a decrease in the pressure exerted on the inner limiting holding element 50. Accordingly, once the outer limiting holding element 52 begins to yield, the yielding process is self-perpetuating.
[0083] The inner limiting holding element 50 and the outer limiting holding element 52 are adapted to assume the holding configuration and the yielded configuration reversibly.
[0084] Thus, the torque limiter 14 can be re-engaged, reset or re-engaged.
[0085] Advantageously, the limitation holding means 44 comprise at least one cartridge 60. Each cartridge 60 comprises one of the limitation holding elements inner limitation 50 and one of the outer limiting holding elements 52. In this case, the cartridge 60 is provided with a single inner limiting holding element 50 and a single outer limiting holding element 52. The outer limiting holding element 52 is a sleeve 62. The cartridge 60 is provided with an opening cover 64. The inner limiting holding element 50 is a punch 66 provided with a piston 68 which is advantageously adapted to extend, and in particular which extends at least in the given configuration, through the opening of the opening cover 64.
[0086] The cartridge 60 is furthermore advantageously provided with a flange 70 for fixing the cartridge 60 to the first body 18, and more precisely to the support ring 27.
[0087] When the inner limiting holding element 50 and the outer limiting holding element 52 are in the yielded configuration ([Fig.2]), the inner limiting holding element 50 is offset along the central axis XX relative to the outer limiting holding element 52 with respect to their holding configuration ([Fig.l]). The inner limiting holding element 50 and the outer limiting holding element 52 together define a yielding direction, which is parallel to the central axis XX.
[0088] Advantageously, when the inner limiting holding element 50 and the outer limiting holding element 52 are in the yielded configuration ([Fig.2]), the piston 68 protrudes from the opening cover 64. Advantageously, when the inner limiting holding element 50 and the outer limiting holding element 52 are in the holding configuration ([Fig.l]), the piston 62 is retracted into the opening cover 64.
[0089] Advantageously, when the inner limiting holding element 50 and the outer limiting holding element 52 are in the yielded configuration ([Fig.2]), the outer contact surface 56 and the inner contact surface 58 are spaced apart from each other.
[0090] In the unassembled state of the cartridge 60, i.e. in the absence of the first body 18, the cartridge 60 can be handled as a single unit, without the inner limiting holding element 50 and the outer limiting holding element 52 becoming completely separated. Thus, the cartridge 60 is a module which can be delivered in a pre-assembled manner.
[0091] The torque limiter 14 may also be provided with triggering means 76 adapted to bring the inner limiting holding elements 50 and the outer limiting holding elements 52 from their holding configuration into their yielded configuration, when the torque limiter 14 is stopped. These triggering means 76 are adapted to allow movement, in this case by traction, of the inner limiting holding element 50 towards the yielded configuration. These triggering means 76 comprise, for example, a thread 78 provided in the internal limiting holding element 50 into which a traction element can engage. Thus, the torque limiter 14 is easy to maintain.
[0092] The torque limiter 14 according to the invention operates in the following manner.
[0093] We start from the situation shown in [Fig.2], that is to say the first and second limiter teeth 28, 36 are in their release configuration. All the inner 50 and outer 52 limiting holding elements are therefore in their released configuration.
[0094] The inner and outer limiting holding elements are brought into their holding configuration. Thus, each inner limiting holding element 50 is pushed so that this inner limiting holding element 50 is clamped in the associated outer limiting holding element 52. In this occasion, the outer contact surface comes into contact with the inner contact surface and is applied thereto.
[0095] In this instance, the first limiter toothing 28 and the second limiter toothing 36 are axially brought closer to each other until the first limiter toothing 28 and the second limiter toothing 36 are in their engaged configuration. In this instance, the first body 18 and the second body 20 are axially brought closer to each other until they are in the engaged configuration.
[0096] The first limiter toothing 28 is brought closer to the second limiter toothing 36 by crossing the blocking means 38, and in this case against the force exerted by the stressing means.
[0097] In this case, a defined axial force is applied to the piston 68 towards the first limiter toothing 28. The defined axial force is such that the axial retaining force of all the inner 50 and outer 52 limiting holding elements combined corresponds to the axial force generated by the first and second limiter toothings 28, 36 when reaching the limit of transmission of the limit transmission torque, if applicable including the force of the biasing means. This axial retaining force of all the inner 50 and outer 52 limiting holding elements combined is therefore identical to the yield force.
[0098] The torque limiter 14 then takes the engaged configuration shown in [Fig. 1].
[0099] Then, the driving shaft 10 is rotated around the central axis XX and rotates, via the torque limiter 14, the driven shaft 12.
[0100] When the transmission torque limit is reached or exceeded, the axial reaction force of the first limiter toothing 28 and the second limiter toothing 36 causes all the outer holding elements 52 to yield, which axially release the inner holding elements 50. This axial release takes place by overcoming the static friction force between the inner holding elements 50 and the external support elements 52.
[0101] The second limiter toothing 36 moves axially away from the first limiter toothing 28. The inner holding elements 50 also move axially away from the first body 18. In this case, the second body 20 moves axially away from the first body 18, under the effect of the axial reaction force of the first and second limiter toothings 28, 36. In this case, this movement is promoted by the force of the biasing means (spring 40).
[0102] The second body 20 and the inner 50 and outer 52 holding elements take the configuration shown in [Fig. 2]. In this configuration, the locking means 38 oppose a movement of the second limiter toothing 36 towards the first limiter toothing 28 and their taking the engaged configuration.
[0103] The driving shaft 10 can thus rotate freely around the driven shaft 12 and damage to the driven device 6, located downstream of the torque limiter 14, is prevented.
[0104] The torque limiter 14 again takes the configuration shown in [Fig.2]. Once the torque limiter 14 is in its release configuration, the locking means 38 oppose a movement of the second limiter toothing 36 towards the first limiter toothing 28 and their taking the engaged configuration.
[0105] In order to re-engage, re-engage or re-arm the torque limiter 14, the operations described above are repeated until the torque limiter 14 again assumes the engaged configuration shown in [Fig.l].
[0106] [Fig. 5] schematically shows a transmission assembly 8 according to a second embodiment of the invention, the torque limiter 14 being in its engaged configuration, similarly to the configuration shown in [Fig. 1]. In the following, only the differences from the first embodiment will be described. Similar elements bear the same references.
[0107] The driven shaft 12 is a shaft which is axially fixed relative to the driving shaft 10.
[0108] The torque limiter 14 comprises, on the one hand, a first coupling flange 80 provided with a first coupling toothing 82 and fixed to the first body 18 as well as, on the other hand, a second coupling flange 84 provided with a second coupling toothing 86 and fixed to the second body 20.
[0109] The drive shaft 10 is provided with complementary coupling teeth 88 which cooperate with the first coupling teeth 82. The first coupling teeth 82 and the complementary coupling teeth 88 connect the drive shaft 10 to the first body 18 in a fixed manner in rotation around the central axis XX, but free in axial translation and free in rotation around the break axes extending perpendicular to the central axis XX.
[0110] Similarly, the driven shaft 12 is provided with a complementary coupling toothing 90 which cooperates with the second coupling toothing 86. The second coupling toothing 86 and the complementary coupling toothing 90 connect the driven shaft 12 to the second body 20 in a fixed manner in rotation around the central axis, but free in axial translation and free in rotation around the break axes extending perpendicular to the central axis XX.
[0111] The torque limiter 14 comprises an axial stop 92 limiting the axial displacement of the first body 18 unilaterally relative to the driving shaft 10 towards the second body 20. The torque limiter 14 comprises an axial stop 94 limiting the axial displacement of the second body 20 unilaterally relative to the driven shaft 12 towards the first body 18.
[0112] This embodiment allows a radial offset of the driving shaft 10 and the driven shaft 12.
[0113] The device of [Fig.5] operates in the following manner.
[0114] When reaching or exceeding the limit transmission torque, the second body 20 moves axially away from the first body 18, under the effect of the axial reaction force of the first and second limiter teeth 28, 36 as in the first embodiment, however with the difference that the first and second coupling teeth 82, 86 and the complementary coupling teeth 88, 90 allow axial movement of the first body 18 and the second body 20 relative to the driving shaft 10 and relative to the driven shaft 12.
[0115] The axial position of the driven shaft 12 relative to the driving shaft 10 remains unchanged when the release configuration is taken from the engaged configuration.
[0116] [Fig.6] schematically shows a transmission assembly according to a third embodiment of the invention, the torque limiter 14 being in the release configuration, similarly to the configuration shown in [Fig.2]. In the following, only the differences from the first embodiment will be described. Similar elements bear the same references.
[0117] The driven shaft 12 is a shaft which is axially fixed relative to the driving shaft 10, in a manner similar to the second embodiment.
[0118] The second body 20 comprises two body parts 100, 102 axially movable relative to each other and fixed in rotation relative to each other around the central axis XX, in this case by external grooves 106 which cooperate with internal grooves 108.
[0119] The body part 100 comprises the connecting flange 32, the thrust surface 34 and carries the second toothing 36. The body part 100 comprises the external splines 106. The body part 100 is also in contact with the thrust cylinder 42.
[0120] The body part 102 forms the fixing flange 30 and includes the internal grooves 108.
[0121] When transitioning between the release configuration and the engaged configuration, the body part 100 moves axially relative to the body part 102, while the body part 102 remains axially stationary.
[0122] Figures 7 to 10 show a transmission assembly 8 according to a fourth embodiment. In the following, only the differences or particularities compared to the second embodiment ([Fig.5]) will be described. Similar elements bear the same references.
[0123] [Fig.7] schematically shows the transmission assembly 8, the torque limiter 14 being in its engaged configuration.
[0124] The guide means 37 have no axial degree of freedom along the central axis XX and therefore prevent an axial offset of the first body 18 relative to the second body 20 between the release configuration and the engaged configuration. The axial position of the first body 18 relative to the second body 20 in the release configuration and the engaged configuration is therefore identical.
[0125] The second limiter toothing 36 is carried by the second body 20 and is axially movable relative to the second body 20. The second limiter toothing 36 comprises tooth inserts 120 disposed on the second body 20. The tooth inserts 120 are axially movable relative to the second body 20 between the engaged configuration and the release configuration.
[0126] For this purpose, in this case each tooth insert 120 comprises a cylindrical guide surface and the second body 20 comprises a complementary cylindrical guide surface.
[0127] Each tooth insert 120 comprises in this case a single tooth 124. Each tooth insert 120 may comprise between one and three teeth 124 inclusive so that the number of teeth 124 of each tooth insert 120 is less than four.
[0128] Each tooth insert 120 comprises a thrust surface 34 on which one of the internal limiting holding elements 50 is applied.
[0129] Thus, each tooth insert 120 can be manufactured from a material with high mechanical strength and with low tolerances, while keeping the overall cost of the torque limiter acceptable. The maximum torque that can be transmitted by the torque limiter can thus also be easily adapted. Each tooth insert 120 is for example made of high-alloy steel, preferably having undergone a surface treatment such as nitriding, carburizing or quenching.
[0130] Advantageously, the number of tooth inserts 120 and the number of internal limiting holding elements 50 of the torque limiter 14 is identical.
[0131] The locking means 38 comprise snap-fastening means 130, such as a axial groove with a recessed end formed in the tooth insert 120 and a ratchet member, such as a ball (see [Fig. 10]).
[0132] [Fig.8] shows the installation of [Fig.7], with the torque limiter 14 in the release configuration. All of the tooth inserts 120 are spaced from the first limiter tooth 36.
[0133] In Figures 9 and 10 a detail of the torque limiter 14 is shown in a radial view. A portion of the first body 18, a portion of the second body 20, a part of the first limiter toothing 28 and a tooth insert 120 are seen.
[0134] Generally, the first and second limiter teeth 28, 36 may have any shape, provided that they are adapted to generate the axial force urging the first and second limiter teeth 28, 36 or the first body 18 and the second body 20 from their engaged configuration to their release configuration under the effect of the transmitted rotational torque. The first and second limiter teeth 28, 36 may for example be oblique teeth. The first and second limiter teeth 28, 36 may have a regular or repetitive profile or an irregular and non-repetitive profile. Alternatively, the torque limiter 14 may comprise limiting bodies, such as balls or rollers, interposed between the first and second limiter teeth 28, 36.
[0135] The foregoing description contains technical features of the invention. These technical features, although presented in a technical context and possibly in combination with other technical features, can be used individually each time, without the other technical features, as far as this is technically possible.
Claims
1. Claims Torque limiter (14), of the type comprising - a first body (18), and - a second body (20), the first body and the second body extending around a central axis (XX), the first body carrying a first limiter toothing (28) the second body carrying a second limiter toothing (36), complementary to the first limiter toothing, the first limiter toothing and second limiter toothing defining an engaged configuration in which the first limiter teeth and second limiter teeth are adapted to transmit a rotational torque about the central axis of the first body to the second body and a release configuration, in which the first limiter teeth (28) and second limiter teeth (36) are incapable of transmitting a rotational torque between the first body and the second body, the torque limiter also including locking means (38) adapted to oppose a transition of the first limiter toothing (28) and the second limiter toothing (36) from their release configuration to their engaged configuration, and limiting holding means (44) adapted to hold the first limiter toothing (28) and the second limiter toothing (36) in their engaged configuration when the rotational torque is less than a limit transmission torque and adapted to yield when the rotational torque exceeds the limit transmission torque, characterized in that the means of maintaining limitation include at least one inner limiting holding element (50) having an outer contact surface (56), and at least one outer limiting holding element (52) having an inner contact surface (58) complementary to the outer contact surface, the inner (50) and outer (52) limiting holding elements having - a holding configuration, in which the inner limiting holding element is clamped in the outer limiting holding element, and - a yielded configuration in which the inner limiting holding element (50) is loosened from the outer limiting holding element (52).
2. Torque limiter according to claim 1, in which the outer contact surface (56) is of frustoconical shape of revolution and in which the inner contact surface (58) is of frustoconical shape of revolution, in particular in which the opening angle (a) of the outer and inner contact surfaces is between 1° and 20°.
3. A torque limiter according to claim 1 or 2, wherein the limiting holding means (44) comprises at least one cartridge (60), each cartridge comprising one of the at least one outer limiting holding element (52) and one of the at least one inner limiting holding element (50), wherein the outer limiting holding element is a sleeve (62), and wherein the inner limiting holding element is a punch (66) provided with a piston (68), in particular the piston being adapted to extend through an opening in the opening cover (64) of the cartridge (60).
4. A torque limiter according to any preceding claim, wherein when the inner limiting holding member (50) and the outer limiting holding member (52) are in the yielded configuration, the inner limiting holding member is offset along the central axis (XX) relative to the outer limiting holding member from their holding configuration.
5. A torque limiter according to any preceding claim, wherein, in their engaged configuration, the first toothing (28) and the second toothing (36) engage each other.
6. Torque limiter according to any one of the preceding claims, wherein the torque limiter comprises - a first coupling flange (80) fixed to the first body and provided with a first coupling toothing (82), and - a second coupling flange (84) fixed to the second body and provided with a second coupling toothing (86), and wherein the first coupling toothing (82) is adapted to cooperate with a complementary coupling toothing (88), and the second coupling toothing (86) is adapted to cooperate with a complementary coupling toothing (90).
7. A torque limiter according to any preceding claim, wherein either the second limiter toothing (36) is fixed relative to the second body (20), or the second limiter toothing (36) comprises tooth inserts (120) axially movable relative to the second body (20) between the engaged configuration and the release configuration.
8. Torque limiter according to any one of the preceding claims, wherein the second body (20) comprises two body parts (100, 102) axially movable relative to each other and fixed in rotation relative to each other around the central axis (XX).
9. Transmission assembly (8), of the type comprising - a driving shaft (10), - a driven shaft (12), and - a torque limiter, characterized in that the torque limiter is a torque limiter (14) according to any one of the preceding claims, in that the first body (18) is rotatably fixed to the driving shaft, and the second body (20) is rotatably fixed to the driven shaft.
10. A transmission assembly according to claim 9, wherein the drive shaft (10) comprises complementary coupling teeth (88) and the driven shaft (12) comprises complementary coupling teeth (90) and wherein the torque limiter (14) is a torque limiter according to at least claim 6.
11. Use of a transmission assembly according to claim 9 or 10, comprising the following successive steps: providing the transmission assembly (8), the inner and outer limiting holding elements being in their yielded configuration; placing the inner and outer limiting holding elements in their holding configuration by applying the outer contact surface to the inner contact surface, clamping the inner limiting holding element into the outer limiting holding element.
12. Use according to claim 11, further comprising the steps successive following steps, implemented after the step of placing the interior and exterior limiting support elements in their support configuration: - exceeding the limit transmission torque, thus causing the first limiter toothing (28) and second limiter toothing (36) to be put into the release configuration, - re-engaging the torque limiter (14) by placing the inner and outer limiting holding elements in their holding configuration by applying the outer contact surface to the inner contact surface, thereby clamping the inner limiting holding element in the outer limiting holding element.