Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D7/00—Slip couplings, e.g. slipping on overload, for absorbing shock
  • F16D7/04—Slip couplings, e.g. slipping on overload, for absorbing shock of the ratchet type

Definitions

• the invention relates to an overload clutch comprising a driving and a driven clutch part, between which is interposed an engagement mechanism consisting of a pawl carrying part and a pawl notch part.
• the pawls are kept in engagement with the pawl notches by means of springs and the pawl notches are constructed in such a manner that the pawls are capable of slipping out of engagement with the pawl notches, but are prevented from so doing by means of the springs until the torque being transferred exceeds a certain predetermined value at which the springs are no longer capable of keeping the pawls engaged , whereby disengagement takes place.
• Overload clutches of this kind have the drawback that it is difficult accurately to adjust the torque at which disengagement of the pawls takes place, because both frictional forces and spring forces have to be overcome to cause disengagement.
• prior art that may be pertinent, reference is made to the French patent specification No. 1304082, and to USA patent specifications Nos . 1714105 and 3831724 and the published Western German patent applica ⁇ tion No. 2805641 .
• the overload clutch according to the invention is characteriz ⁇ ed in that one of the clutch parts is connected with one of the parts of the engagement mechanism by means of at least one eiastically y ⁇ eidable element, and that the said one clutch part is rigidly connected with cam members which are adapted upon relative movement of the two clutch parts to disconnect the pawl engagement.
• the overload torque will be very well defined , because it will substantially depend on the spring characteristic of the yieldable element, and moreover it is possible to use a positive form of pawl-pawl notch-engagement, i . e. a form of engagement which positively retains the pawl irrespectively of the value of the torque being transferred .
• Fig. 1 shows an axial section through a first embodiment of the overload clutch according to the invention along the ;.- : . line 1-1 in Fig. 2,
• Fig. 2 the clutch of Fig. 1, as viewed from the right hand side, some parts having, however, been removed or cut through, Fig. 3 on a larger scale, an axial section through a hub part of the clutch of Figs. 1 and 2 along the line Ill-Ill in 10 Fig. 4,
• Fig. 4 an end view of the hub part as seen from the bottom in Fig. 3, Fig. 5 a housing part of the clutch of Figs. 1 and 2 as seen from one end, 15 Fig. 6 an axial section through the housing part of Fig. 5 along the line VI-VI, Fig. 7 a driving element of the clutch as viewed in the axial direction thereof, Fig. 8 the driving element of Fig. 7 as viewed from the left 20 in Fig. 7,
• Fig. 9 a spring belonging to the clutch
• Fig. 10 a driving disc of the clutch as seen in the axial di ⁇ rection thereof
• Fig. 11 an axial section of the driving disc of Fig. 10 along 25 the line XI -XI,
• Fig. 12 a sectional view of a pawl belonging to the clutch
• Fig. 13 the pawl of Fig. 12 as viewed from the left
• Fig. 14 an elast ⁇ cally yieldable transmission element of the clutch as viewed in the axial direction thereof
• Fig. 15 the transmission element of Fig. 14 as viewed from the bottom
• Fig. 16 an axial section of a second embodiment of the over ⁇ load clutch according to the invention, along the line XVI-XVI in Fig. 17, 35 Fig. 17 the clutch of Fig. 16 as viewed from the right hand side, some parts having, however, been removed and others cut through along the section line XV 11 -XV 11 in Fig. 16,
• FIG. 18 an end view of a hub part of the clutch of Figs . 16 and 17, Fig . 19 a pawl of the clutch of Figs. 16 and 17, partly in section , ' 5 Fig . 20 a side view of the pawl of Fig . 19,
• Fig . 21 a sectional view of an end cover of the clutch of
• Fig . 22 the cover of Fig . 21 as viewed from the left
• Fig . 23 a fraction of the cover of Fig . 22 along the sectional
• 1 is a driving clutch part in the form of a hub part having inner ribs 2 for engagement with a multi-groove shaft.
• a pawl notch part 3 with three pawl notches 4 for engagement with three pawls 5 (Fig . 2) is formed in one piece 15 with the hub part 1 .
• These pawls 5 are approximately in the middle rotatably mounted between two driving discs 7 and 8, Fig . 1 , by means of pins 6, each of said driving discs being mounted on the hub part 1 by means of a ball bearing 9 and 10, respectively.
• the driving discs 7 and 8 constitute a pawl carrying part of an engagement 20 mechanism which in addition to this pawl carrying part also comprises the pawl notch part 3.
• Each driving element 11 is attached between the driving discs 7 and 8, and each of the driving elements 11 is pierced by two pins 12, 13, the ends of which are attached to the driving discs 7 and 25 8, respectively.
• Each driving element 11 carries a driving nose 15 pro ⁇ truding beyond the driving discs 7 and 8.
• Each of these driving noses engages with an elastically yieldable transmission element 16 and each of these is received in a recess 17 in a housing part 18, which consti ⁇ tutes the driven clutch part of the clutch illustrated .
• Cam members 19 30 are formed in the housing part 18 between the recesses 17.
• Each pawl 5 is provided at each end with a rotatably mounted .roller 20 and 21 , respectively, of which the rollers 20 serve, in the engaged position of the clutch , for engagement with the pawl notches 4, while the rollers 21 serve to co-operate with the cam members 19 in 35 disengaging the clutch .
• Each of the rollers 21 additionally serves as an abutment for one end of a spring 22. The other end of each of these springs is held in the adjacent driving element 11 , each of the latter being provided with a slot 23 ( Figs. 7 and 8) for receiving the relevant end of the spring so that this engages with one of " the pins 13 of the
• the springs 22 have a small bias so that the pawls 5 are loaded by small torque in the clock-wise direction, as seen in Fig . 2, i .e. in direction to urge the rollers 20 into the corresponding pawl notches 4. 7.-5 -
• the housing part 18 is cup-shaped and has a smooth oute face, and the recesses 17 and the cam members 19 are formed on th inner face of its wall 25.
• the housing part 18 is closed at one end b means of a cover 26, which is secured by means of a spring ring 2 and is provided with a central opening through which the hub part 1
• a seal and a ball bearing 28 are provided between the cove 26 and the hub part.
• the bottom of the housing part 18 is constituted by a flang 29 with screw holes 30 for the attachment of e.g. a flange of a driven shaft.
• the opening formed by the flange 29 is closed by means of
• the clutch can b used for mounting on a through shaft, and instead of or in addition t the holes 30 the housing may be provided with a toothed ring or lugs for connection with a driven machine element.
• a ball bearing 32 i provided between the flange 29 and the hub part.
• Figs. 3 and 4 show the hub part 1 on a larger scale and serve for further illustrating the pawl notches 4. These are cylindrical with the generatrix direction extending in the axial direction of th clutch, and they are shaped as circular arcs along their bottom portion with a radius of curvature which is only slightly greater than th
• connection line 33 is shown in Fig . 4, but in this figure the path of this line is inverted as compared to Fig . 2, becaus in Fig . 4 the hub part is shown from the end facing down in the plan
• This line 33 forms an angle of about 60 with the radius 35 extending through the center 36 of the relevan pawl notch 4.
• the portion 37 of the wall of the notch extending fro the point of intersection between this wall and the line 33 to th terminal edge 34 is approximately plane and forms an angle of onl
• Figs . 5 and 6 show the housing part 18 on an enlarged scale and it will be seen that the recesses 17 for receiving the elastic transmission elements 16 are delimited at their side edges by arcuate side wails 40, 41 for engagement with the corresponding side edges of the transmission elements, cf. 42, 43 in Fig . 14. From Figs. 14 and 15 it will also be apparent that each transmission element 16 is provided with an axially extending groove 44 for engagement with the correspond ⁇ ing driving nose 15 of the corresponding driving element 11 so that portions of the elastic transmission elements are present between each side of the driving noses 15 and the side walls 40, 41 of the recesses of the transmission elements.
• the axial extension of the transmission element substantially corresponds to the axial distance between the inner face of the housing cover 26 and the inner face of the flange 29 of the housing part 18.
• the elastic transmission elements consist of an elastomer pla ⁇ stics material and they are consequently capable of being compressed in the circumferential direction of the clutch . They are preferably in ⁇ serted in the corresponding recesses 17 at a bias in the circumferential direction .
• the edge of each transmission element which in the mounted state of the clutch engages the side wall 40 is constituted , as is clear ⁇ ly apparent from Fig . 14, by a steel pin 46 having a threaded bottom hole 47 so that the transmission elements can easily be extracted from the corresponding recesses 17.
• a material for the transmission ele ⁇ ments one may e. g . use a highly elastic plastics material marketed by E . I . du Pont de Nemours and Company under the registered trademark ADI PRENE.
• each driving element comprises an arcu ⁇ ate body 48 integral therewith and through which the two holes extend by means of which the elements are held between the driving discs 7 and 8.
• the width of the body 48 corresponds to the distance between the driving discs 7 and 8 and the body thus serves as a spacing mem ⁇ ber.
• the nose 15 extends laterally with respect to the body 48 and thus has a length (in the axial direction of the clutch) which is only a little shorter than the distance between the inner face of the cover 26 and the inner face of the flange 29 and thus the driving noses 15 have substantially the same length as the grooves 44 of the transmission elements.
• One of the springs 22 is shown on an enlarged scale in Fig . 9, and it will be seen that it is shaped in such a manner as to be sui- table for engaging with the corresponding pawl roller 20, its holding pin 13, and the inner face of the corresponding driving element.
• the driving elements 11 in addition to their driving function , also serve as spacing members and as spring holders.
• Figs . 12 and 13 show on a larger scale one of the pawls 5.
• Each pawl consists of two cheek plates 50, 51 , which are kept at a spacing from one another by means of three spacing sleeves 53, the ends of which are received in corresponding recesses of the cheek plates 50 and 51 .
• the sleeve 53 in the middle serves to receive the corresponding pin 6, cf. Fig . 2, while the sleeves 53 at the ends receive bolts 54, which at their outer ends are riveted to the cheek plates 50, 51 .
• the sleeves 53 at the ends of the pawl serve as bearings for the two pawl rollers 20, 21 .
• the pawl has a width such that it can be received between the driving discs 7 and 8 with a suitable play.
• the parts 20, 21 , 53, 54 may consist of standard chain parts. As is apparent from Fig . 12, the distance between the sleeve
• Figs . 10 and 11 show one of the driving discs e. g . the disc 7 on an enlarged scale. Since the two discs 7 and 8 are identical , only one of them is shown on an enlarged scale.
• the disc is constructed on its inner side with a recess 56 for mounting of the corresponding bear-
• O PI ing 9 has fifteen holes 57 which are uniformly distri ⁇ ubbed in the circumferential direction and each of which is constructed with an inner shoulder 58, Fig . 11. These holes 57 serve for receiving the ends of the pawl mounting pins 6 and the attachment pins 12 and 13 for the driving elements. By virtue of the shoulders 58 these pins may just be introduced loosely at the mounting, whereby this is facilita ⁇ ted . From Fig .
• the clutch shown in Figs . 1 -15 operates as follows :
• the clutch may be constructed as a two-way clutch , seeing that it may be provided with two sets of pawls, one set of which is inclined in the opposite direction of the other, the corresponding disengaging cam members likewise being inversely oriented so that the disengagement of both sets of pawls may take place by relative turning of the housing part and the hub part.
• the clutch of Figs. 1 -15 also distinguishes itself by being capable of transmitting high torques at small dimensions owing to the positive pawl engagement referred to, so that the clutch according to the invention may be made small in relation to the driving shaft or other driving machine element.
• 61 is a driving clutch part in the form of a hub part having internal ribs 62 for engagement with a multi-groove shaft.
• a pawl notch part 63 which is integral with the hub part 61 , is constructed with three pawl notches 64 for engagement with three pawls 65 (Fig . 17) .
• These pawls 65 are approximately in the middle rotatably mounted between two driving discs 67 and 68, Fig . 16, by means of pins 66, the driving discs 67 and 68 being mounted on the hub part 61 by means of journal bearings 69 and 70, respectively.
• the driving discs 67 and 68 constitute a pawl carrying part of an engagement mechanism which in addition to this pawl carrying part also comprises the pawl notch part 63.
• each driving element 71 is attached, each being pierced by two pins 72, 73, the ends of which are attached to the respective driving discs 67, 68.
• Each driving element 71 carries a driving nose 75 protruding beyond the driving discs 67 and 68.
• Each of these driving noses engages with an elastically yieldable transmission element 76 and each of these is receiv-
• Each pawl 65 is provided at each end with a rotatably mounte - roller 80 and 81 , respectively, of which the rollers 80 serve, in the engaged position of the clutch, for engagement with the pawl notches 64, while the rollers 81 serve to co-operate with the cam members 79 in disengaging the clutch.
• Each of the rollers 81 additionally serves as an abutment for one end of a spring 82. The other end of each of 0 these springs is held in the adjacent driving element 71 .
• the springs 82 have a small bias so that the pawls 65 are loaded by a small torque in the clock-wise direction, as seen in Fig . 17, i . e. in a direction to urge the rollers 80 into the corresponding pawl notches 64. .
• the housing part 78 is cup-shaped and has a smooth outer face, and the recesses 77 and the cam members 79 are formed on the inner face of its wall 85.
• the housing part 78 is closed at one end by means of a cover 86, which is secured by means of a spring ring 87 and is provided with a central opening through which the hub part 61 extends.
• a seal and a journal bearing 88 are provided between the co- ver 86 and the hub part.
• the bottom of the housing part 78 is constituted by a flange 89 with screw holes 90 for the attachment of e.g. a flange of a driven shaft.
• the opening formed by the flange 89 is closed by means of a cover 91 , through which the hub part 61 extends, so that the clutch can be used for mounting on a through shaft, and instead of or in ad ⁇ dition to the holes 90 the housing may be provided with a toothed ring or lugs for connection with a driven machine element.
• a journal bearing 92 is provided between the cover 91 and the hub part 61 .
• Fig . 18 shows the hub part 61 in end view and serves for further illustrating the pawl notches 64.
• each transmission element 76 is provided with an axial ly extending groove 104 for engagement with the corresponding driving nose 75 of the corresponding driving element 71 so that portions of the elastic transmission elements are present between each side of the driving noses 75 and the side walls 100, 101 of the recesses of the transmission elements.
• the elastic transmission elements consist of an elastomer pla ⁇ stics material and they are consequently capable of being compressed in the circumferential direction of the clutch . They are preferably inserted in the corresponding recesses 77 at a bias in the circumferential direction .
• a material for the transmission elements one may e. g . use a highly elastic plastics material marketed by E. I . du Pont de Nemours and Company under the registered trademark ADI PRENE.
• Figs. 19 and 20 show on a larger scale one of the pawls 65.
• Each pawl consists of two cheek plates 110, 111 , which are kept at a spacing from one another by means of a middle sleeve 113, the ends of which are received in corresponding recesses of the cheek plates 110 and 111 .
• the middle sleeve 113 serves to receive the corresponding pin 66, cf. Figs. 16 and 17.
• the middle sleeve 113 is lined with a liner 114 in order to obtain a certain elasticity.
• Each pawl 65 has a width such that it can be received between the driving discs 67 and 68, and widened collars 115 of the form journalling collars between the pawl 65 and the driving discs 67 and 68.
• each cheek piate 110 and 111 facing the center line of the clutch a toothed sector 116 is provided, and about
• a synchronizing ring 117 is rotatably mounted at each side of " the pawl notch part 63. These synchronizing rings 117, 117 are mounted on lateral extensions of the journal bearings 69 and 70 of the driving discs 67 and 68. Each synchronizing ring 117 is provided with three toothed sectors 118, which are distributed at a mutual spacing of
• Each toothed sector 118 of a ring engages a toothed sector 116 of a pawl 65.
• the ring 117 at one side of the pawl notch part 63 engages with each of the cheek plates 110 which extend into a spacing between the driving disc 67 and the pawl notch part 63, and the ring 117 at the other side of the pawl notch part 63 engages with the cheek
• the end cover 86 is construct ⁇ ed on its inner side with three plateaus 121 which are uniformly distri ⁇ minded in the circumferential direction .
• the radial width of these pla ⁇ teaus corresponds to the radial width of the elastically yieldable element 76 and they are located at the same radial distance from the axis of
• the plateaus 121 protrude from an axially directed collar 122 of the cover.
• a bottom hole 123 is provided, as shown in Fig . 23 for engagement by a tool so that the cover 86 can be turned in the circumferential direction whereby the plateaus 121 can be turned between positions in which the
• O PI in the axial direction can be adjusted .
• the clutch shown in Figs. 16-23 operates as follows :
• the driving clutch part or hub part 61 is driven in the direction of the arrow 125 in Fig. 17, the pawl notch part 63 will take L . along the pawl rollers 80 engaged in the pawl notches, and by virtue of the engagement explained above the pawl rollers will transmit the force to the pawl mounting pins 66 which again by virtue of their connection with the driving discs 67 and 68 will rotate these and thereby also the driving elements 71 carried by .these discs.
• each spring 82 is provided with a bend 126, and the cheek plates of the pawls are provided with a nose 127 partly engaging the spring bend 126.
• the synchronizing rings will ensure that all the pawls are disengaged simultaneously, whereby it is avoided with certainty that during the disengagement movement a single pawl might be called upon momentanously to transmit the whole of the torque prevailing between the hub part 81 and the housing part 78 in the moment of disengage-
• the cam faces 79 are construct ⁇ ed symmetrically about a radially extending axis. This means that the . clutch may in a simple manner be re-set from one direction of rotation to the other, because the pawls 65 may, after their mounting pins 66
• the elastic liners 114, Fig . 19, of the pawls also contribute to compensate for possible manufacturing tolerances.
• the elastically yieldable elements 76 are compressed in the cir ⁇ cumferential direction which again means that at the same time they expand perpendicularly thereto, i . e. radially and axially.
• the play 124 may be adjusted and, if desired, entirely removed, whereby the freedom of the elastic elements 76 to expand in the axial direction is limited so that the elements when being compressed in the circumferential direction must look out for " Sr- other places in order to obtain space for the required lateral expansion . Consequently, a turning of the end cover 86 will cause a change of the torque, at which the elements 76 will yield to a degree sufficient to establish the disengagement movement.
• the maximum torque that may be transmitted by the clutch may be adjusted
• the elastically yieldable elements 76 may be replaced by elements having different elastic properties.
• the clutch of Figs. 16-23 also distinguishes itself by being capable of transmitting high torques at small dimensions, owing to the
• the hub part has been referred to as the driving part of the clutch, and the housing as the driven part. It
• the housing may constitute the driving part,_ and the hub part the driven part.
• the pawl engagement part has been described above as being rigidly connected with the hub part, and the elastically yieldable elements have been described as being connected with the housing . It will, however, also
• the inverse arrangement can also be used, meaning that the pawl engagement part is rigidly connected with the housing and the elastically yieldable elements may be connected with the hub part.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• One-Way And Automatic Clutches, And Combinations Of Different Clutches (AREA)
• Mechanical Operated Clutches (AREA)

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Publications (1)

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• 1978
  • 1978-08-21 DK DK369878A patent/DK369878A/da not_active Application Discontinuation
• 1979
  • 1979-08-21 WO PCT/DK1979/000024 patent/WO1980000477A1/en not_active Ceased
• 1980
  • 1980-03-25 EP EP19790901007 patent/EP0016192A1/en not_active Withdrawn
  • 1980-04-21 DK DK169180A patent/DK169180A/da not_active IP Right Cessation

Non-Patent Citations (1)

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