screwing / unscrewing device with rebounding impact mechanism and bidirectional freewheel

Abstract

An impact screwing and / or unscrewing device comprising a housing containing: - a rebounding impact mechanism, - a motor equipped with a rotor, - an output shaft capable of rotating a screwing element, said impact mechanism comprising: - a rotating cage, - at least one striking element carried by said rotating cage, and - at least one striking portion carried by said output shaft, such a device includes a bidirectional freewheel comprising: - an input shaft rotationally linked to said rotor, - a first transmission element rotationally linked to said cage, and - a second transmission element rotationally linked to said output shaft,said bidirectional freewheel being configured to: - free the rotation of said first transmission element relative to said second transmission element in one direction of rotation and to rotationally bind said first transmission element with said input shaft in said direction of rotation when said input shaft is driven in rotation in said direction of rotation by said rotor relative to said second transmission element; - to rotationally bind said first transmission element with said second transmission element when said input shaft is not driven in rotation by said rotor, so as to lock said first transmission element in rotation relative to said second transmission element during the rebounds of said cage following said impacts generated by said impact mechanism. Fig. 1,

Description

Title of the invention: Screwing / unscrewing device with rebounding impact mechanism and bidirectional freewheel 1. Scope of the invention

[0001] The field of the invention is that of tooling.

[0002] More specifically, the invention relates to the design and manufacture of portable tools enabling the screwing and unscrewing of fasteners.

[0003] The invention applies in particular to impact wrenches with a rebounding impact mechanism, with electric or pneumatic drive. 2. Prior art

[0004] Impact wrenches are commonly used in various technical sectors to perform screwing and / or unscrewing operations.

[0005] There are impact wrenches with a non-rebounding impact mechanism and impact wrenches with a rebounding impact mechanism.

[0006] Non-rebounding impact mechanisms are designed in such a way that the rotor of the impact wrench motor is not caused to rotate in the opposite direction of the screwing or unscrewing operation in progress under the effect of a rebound occurring at the end of each impact.

[0007] Conversely, the design of the rebounding impact mechanisms means that the rotor of the impact wrench motor is made to rotate in the opposite direction to the screwing or unscrewing operation in progress under the effect of a rebound occurring at the end of each impact.

[0008] The present invention relates to impact wrenches specifically implementing a rebounding impact mechanism, among which are in particular the "Twin Hammer", "Rocking Dog", "Two Jaws", "Pin Clutch"... in English.

[0009] When using an impact wrench equipped with a rebounding impact mechanism, the motor rotor is subjected, as indicated above, to a rebound after each impact.

[0010] These rotor rebounds induce, in particular, the following problems:

[0011] - when the motor is electric, the rotor rebounds, at the end of each impact, cause the motor to operate as a generator, and consequently lead to the appearance of unwanted currents at the motor's output;

[0012] - whether the motor is electric or pneumatic, the rotor rebound at each impact induces the need to brake the rotor during each rebound and then to re-accelerate it in the direction of the current operation to restart the impact mechanism. This leads to a decrease in overall efficiency, which translates into a decrease in productivity. This also consumes electrical or pneumatic energy.

[0013] Solutions have been devised to try to remedy, at least partially, these problems.

[0014] US-B2-7 607 492 patent document describes an impact wrench, which implements a rebounding impact mechanism called a "twin hammer" in English.

[0015] This impact wrench comprises an electric motor equipped with a rotor. This rotor is directly connected to the rotating cage of the impact mechanism, which carries the hammers. These hammers are capable of striking impact surfaces provided for this purpose on the output shaft, which is adapted to drive a screw-in element.

[0016] A unidirectional freewheel is disposed at the junction between the rotor and the rotating cage. This freewheel comprises an inner ring rotationally connected to the rotor and the rotating cage, and an outer ring rotationally connected to the impact wrench housing by means of a compression spring.

[0017] The free wheel is rotating when the rotor rotates in the direction of a screwing operation, and is locked in the opposite direction.

[0018] Therefore, when the motor rotor rotates in the direction of a screwing operation, it drives the rotating cage to generate impacts which are transmitted to the output shaft, but the outer ring of the freewheel is not driven into rotation.

[0019] When the rotor rebounds after each impact, the outer ring of the freewheel is driven into rotation in the direction of the rebound, which induces a compression of the spring.

[0020] When the rebound ends, the spring relaxes and restores its potential energy to the rotor by driving it in rotation, via the locked free wheel, in the direction of screwing during the re-acceleration of the rotor in the direction of screwing.

[0021] The technique described in this document not only helps to reduce the occurrence of unwanted currents at the motor output during rebounds, but also the need to brake the rotor during rebounds, due to the implementation of the spring and the freewheel.

[0022] However, the technique described in this document gives rise to two problems, namely:

[0023] - firstly, the system only works in the direction of screwing, and not in the The direction of unscrewing severely limits its application in an industrial production context where impact wrenches are used equally for tightening and loosening. The technique described in this document therefore assumes that operators have separate impact wrenches for tightening and loosening, which is impractical and expensive.

[0024] - secondly, because the spring has one end connected to the housing of the With an impact wrench, it's the housing, and therefore indirectly the operator, that is subjected to the counter-force of the rebound. Consequently, the operator must withstand a greater reaction torque and additional vibrations, which is detrimental from an ergonomic standpoint.

[0025] Therefore, rebounding mechanism impact wrenches can still be improved. 3. Objectives of the invention

[0026] The invention aims in particular to provide an effective solution to at least some of these different problems.

[0027] In particular, according to at least one embodiment, an objective of the invention is to provide an impact wrench with a rebounding impact mechanism, which reduces energy consumption.

[0028] In particular, an objective of the invention is to provide, in at least one embodiment, such an impact wrench, which can at least partially recover the energy of the rebounds to restart the impact mechanism at the following impacts.

[0029] Another objective of the invention is, according to at least one embodiment, to provide such an impact wrench which minimizes the angular rebound of the rotor in order to limit the unwanted currents generated by the motor acting as a generator.

[0030] Another objective of the invention is, according to at least one embodiment, to provide such an impact wrench that is more ergonomic.

[0031] In particular, an objective of the invention is to provide, in at least one embodiment, such an impact wrench, which minimizes the forces transmitted to the operator during rebounds.

[0032] Another objective of the invention is, according to at least one embodiment, to provide such an impact wrench which is reversible, i.e. which can function equally well in screwing mode as in unscrewing mode.

[0033] Another objective of the invention is, according to at least one embodiment, to provide such an impact wrench that is simple in design and / or robust and / or economical. 4. Presentation of the invention

[0034] To this end, the invention proposes an impact screwing and / or unscrewing device comprising a housing containing:

[0035] - a rebounding impact mechanism capable of generating impacts,

[0036] - a motor equipped with a rotor,

[0037] - an output shaft capable of rotating a screw-on element,

[0038] said impact mechanism comprising:

[0039] - a rotating cage,

[0040] - at least one striking element carried by said rotating cage, and

[0041] - at least one portion of the strike carried by said output tree, said at least one striking element being capable of successively colliding with said at least one striking portion so as to transmit successive torque impacts to it, each collision inducing a rebound of the rotating cage at the end of each of said torque impacts.

[0042] According to the invention, such a device comprises a bidirectional freewheel, said bidirectional freewheel comprising:

[0043] - an input shaft rotationally linked to said rotor,

[0044] - a first transmission element rotationally linked to said cage, and

[0045] - a second transmission element rotationally linked to said output shaft,

[0046] said bidirectional freewheel being configured for:

[0047] - to release said first transmission element in rotation relative to said second transmission element in a direction of rotation and link in rotation said first transmission element with said input shaft in said direction of rotation when said input shaft is driven in rotation in said direction of rotation by said rotor relative to said second transmission element;

[0048] - to link said first transmission element in rotation with said second element of transmission when said input shaft is not driven in rotation by said rotor,

[0049] so as to block in rotation said first transmission element with respect to said second transmission element during the rebounds of said cage at the end of said impacts generated by said impact mechanism.

[0050] Thus, according to this aspect, the invention consists of integrating into a screwing / unscrewing device with a rebounding impact mechanism, a bidirectional free wheel configured to avoid the rebound of the cage at the end of each impact and thus the rotation of the motor rotor in the opposite direction of the screwing or unscrewing operation in progress.

[0051] Such an implementation makes it possible, in particular, to:

[0052] - minimize the angular rebound of the rotor after each impact in order to limit the unwanted currents generated by the motor acting as a generator,

[0053] - minimize the effort required by the operator during the rebounds,

[0054] - to provide an impact wrench that is reversible, i.e. that can equally well to operate in both screwing and unscrewing modes.

[0055] According to one possible feature, said bidirectional freewheel comprises at least one first locking element and at least one second locking element disposed between said first and second transmission elements,

[0056] said first clamping element being able to take:

[0057] - a disengaged state in which said first transmission element is free in rotation relative to said second transmission element in a first direction of rotation;

[0058] - a transmission state in which it acts on said first transmission element and said second transmission element to link said first transmission element in rotation with said second transmission element in said first direction of rotation;

[0059] said second clamping element being able to take:

[0060] - a disengaged state in which said first transmission element is free in rotation relative to said second transmission element in a second direction of rotation opposite to said first direction of rotation;

[0061] - a transmission state in which it acts on said first transmission element and said second transmission element to link said first transmission element in rotation with said second transmission element in said second direction of rotation;

[0062] said input tree being configured for:

[0063] - act on said first jamming element to place it in the jammed state when it is driven in rotation in said first direction of rotation by said rotor, and

[0064] - act on said second jamming element to place it in the jammed state when it is driven in rotation in said second direction of rotation by said rotor

[0065] According to one possible feature, a device according to the invention includes holding means tending to maintain said first and second clamping elements in their transmission states when the input shaft is not driven in rotation by said rotor.

[0066] According to one possible feature, said input shaft is rotationally movable relative to said first transmission element over a predetermined angular range between:

[0067] - a first extreme position in which it is rotationally linked with said first transmission element in said first direction of rotation and in which the first jamming element is in its jammed state;

[0068] - a second extreme position in which it is rotationally linked with said first transmission element in said second direction of rotation and in which the second jamming element is in its jammed state.

[0069] According to one possible characteristic:

[0070] - said input shaft comprises at least one first rotational stop in said first direction of rotation and at least one first rotational stop in said second direction of rotation, and

[0071] - said first transmission element comprises at least a second stop a rotational joint in said first direction of rotation and at least a second rotational joint stop in said second direction of rotation,

[0072] said at least one first and second rotational link stops in said first direction of rotation being in contact in said first extreme position of said input shaft;

[0073] said at least one first and second rotational link stops in said second direction of rotation being in contact in said second extreme position of said input shaft.

[0074] According to one possible characteristic:

[0075] - said input shaft includes at least one first rotational stop in said first direction of rotation and at least one first rotational stop in said second direction of rotation, and

[0076] - said first transmission element comprises at least a second stop a rotational joint in said first direction of rotation and at least a second rotational joint stop in said second direction of rotation,

[0077] said at least one first clamping element being clamped between said first and second rotational connecting stops in said first direction of rotation, in said first extreme position of said input shaft, to link said input shaft and said first transmission element in rotation in said first direction of rotation,

[0078] said at least a second clamping element being clamped between said first and second rotational linking stops, in said second direction of rotation in said second extreme position of said input shaft, to link in rotation said input shaft and said first transmission element in said second direction of rotation.

[0079] According to one possible feature, said output shaft and said second transmission element are linked by an elastic connection along the axis of rotation of said output shaft.

[0080] According to one possible feature, said second transmission element and said output shaft are linked by a connection zone with which they form a single unit, said elastic connection being achieved by a reduction in the cross-section of said connection zone.

[0081] According to one possible feature, said second transmission element and said output shaft are linked by a torsional elastic element.

[0082] According to one possible feature, said rebounding striking mechanism belongs to the group comprising:

[0083] - Twin hammer,

[0084] - Pin clutch.

[0085] The invention also covers a method of screwing and / or unscrewing by impact using a device according to any one of the above variants, said method comprising successive phases of driving said impact mechanism in rotation by said rotor and of rebounding said impact mechanism:

[0086] - said first transmission element being free in rotation with respect to said second transmission element in one direction of rotation and said first transmission element being rotationally linked with said input shaft in said direction of rotation when said input shaft is driven in rotation in said direction of rotation by said rotor relative to said second transmission element during said drive phases of said impact mechanism,

[0087] - said first transmission element being rotationally linked with the second element of transmission during said rebound phases during which said rotor is not driven in rotation;

[0088] a rotation of said first transmission element with respect to said second transmission element being thus blocked when said cage rebounds following an impact generated by said impact mechanism. 5. Description of the figures

[0089] Other features and advantages of the invention will become apparent from the following description of particular embodiments, given by way of simple illustrative and non-limiting example, and the accompanying drawings, among which:

[0090] [Fig-1] [Fig.1] illustrates a longitudinal cross-sectional view of a device screwing / unscrewing according to a first variant of a first embodiment of the invention;

[0091] [Fig.2] [Fig.2] illustrates a cross-sectional view along axis CC of [Fig.1];

[0092] [Fig.3] [Fig.3] illustrates a partial perspective view of the device in [Fig.1];

[0093] [Fig.4] [Fig.5] [Fig.6] Figures 4, 5 and 6 illustrate cross-sectional views along the axes AA and BB of the device in [Fig.1] whose input shaft is in various positions;

[0094] [Fig.7] [Fig.7] illustrates a partial perspective view of a device screwing / unscrewing according to a second variant of a first embodiment of the invention;

[0095] [Fig.8] [Fig.9] Figures 8 and 9 illustrate cross-sectional views along axis AA of the device of [Fig.7] whose input shaft is in various positions;

[0096] [Fig. 10] [Fig. 10] illustrates a longitudinal cross-sectional view of a screwing / unscrewing device according to a second embodiment of the invention;

[0097] [Fig. 11] [Fig. 11] illustrates a partial perspective view of the device of [Fig. 10];

[0098] [Fig. 12] [Fig. 12] illustrates a cross-sectional view along axis CC of [Fig. 10].

[0099] 6. Description of particular embodiments

[0100] 6.1. First embodiment: “twin hammer” (in English)

[0101] A first embodiment of a screwing / unscrewing device according to the invention comprising an impact mechanism of the type "twin hammer" in English.

[0102] 6.1.1. First variant: first transmission element and input shaft equipped with protrusions and training fingers i. Architecture

[0103] Figures 1 to 6 illustrate a first variant in which the first transmission element and the input shaft are provided with drive zones, as will be described in more detail later.

[0104] As shown in the figures, such a screwing device 1 comprises a housing 10 and an actuating trigger 100.

[0105] This housing 10 accommodates an electric motor 11 equipped with a stator 110 and a rotor 111 with a rotor shaft 112.

[0106] The housing 10 also accommodates an output shaft 12, partially projecting from one end of the housing 10, which is capable of rotating a screw-on element. The output shaft 12 is mounted to rotate freely relative to the housing 10 about its longitudinal axis X.

[0107] The housing 10 contains a rebounding impact mechanism 13. More precisely, this is an impact mechanism known as a "twin hammer" in English. This impact mechanism is directly connected to the rotor shaft 112, as will become clearer later. In other words, the transmission ratio between the rotor shaft 112 and the impact mechanism 13 is equal to 1.

[0108] This impact mechanism 13 includes a rotating cage 130. This rotating cage 130 is mounted to rotate freely relative to the housing 10 along the X axis.

[0109] The rotating cage 130 carries at least one striking element 131. In this embodiment, it carries two striking elements 131.

[0110] Each striking element 131 is mounted movable in rotation relative to the rotating cage 130 on an axis 132 which extends parallel to the axis of rotation X. Each striking element 131 comprises two striking surfaces 1310 which extend essentially parallel to the axis X and in opposite directions.

[0111] The output shaft 12 comprises as many striking portions 120 as the impact mechanism 13 comprises striking elements 131. Each striking portion 120 comprises two striking surfaces 1200 which extend parallel to the axis of rotation X in opposite directions.

[0112] The striking surfaces 1310 of the striking elements 131 are intended, in a conventional manner, to come into successive contact with the striking surfaces 1200 The striking portions 120 transmit successive torque impacts to the output shaft 12, enabling the tightening or loosening of a screwed component. The striking elements 131 thus act as hammers, and the striking portions 120 act as anvils.

[0113] The structure and operation of a "twin hammer" type impact mechanism are known in themselves to a person skilled in the art and are therefore not described in further detail here.

[0114] The screwing device includes a bidirectional free wheel 14, also called an irreversible free wheel or bidirectional anti-rotation device.

[0115] This bidirectional freewheel 14 comprises:

[0116] - an input shaft 140 rotationally linked to the rotor shaft 112 along the X-axis,

[0117] - a first transmission element 141 rotationally linked to the cage 130 along the X axis, And

[0118] - a second transmission element 142 rotationally linked to the output shaft 12 along the X axis.

[0119] This 140 bidirectional freewheel is configured for:

[0120] - to link in rotation the first transmission element 141 with the second element of transmission 142 when the input shaft 140 is not driven in rotation by the rotor 111;

[0121] - to free the first transmission element 141 from rotation relative to the second transmission element 142 in one direction of rotation (screwing or unscrewing), and link in rotation the first transmission element 141 with the input shaft 140 in this direction of rotation, when the input shaft 140 is driven in rotation by the rotor 111 in this direction of rotation relative to the second transmission element 142.

[0122] As will be explained in more detail later, this architecture allows the first transmission element 141 to be locked in rotation relative to the second transmission element 142 during rebounds of the cage 130, in the opposite direction to the screwing or unscrewing operation in progress, at the end of the impacts generated by the impact mechanism 13.

[0123] The first transmission element 141 is traversed by an internal bore 1410.

[0124] The input shaft 140 is housed in the inner bore 1410 and is guided in rotation relative to the first transmission element 141 along the X axis.

[0125] The input shaft 140 includes a drive zone 1400 provided with radial projections 1404 separated by recesses 1407.

[0126] Each radial projection 1404 comprises two contact surfaces oriented in opposite directions and extending in planes parallel to the X-axis. These contact surfaces define a first rotational stop in a first direction of rotation 1405 and a first connecting stop in rotation in a second direction of rotation 1406.

[0127] The first direction here is the tightening direction and the second direction is the loosening direction. This convention could, however, be reversed.

[0128] The first drive element 141 is extended, at its end oriented towards the side of the input shaft 140, by drive fingers 1412. These drive fingers 1412 extend along the X-axis and are separated by recesses 1413. Each drive finger 1412 comprises two contact surfaces oriented in opposite directions and extending in planes parallel to the X-axis. These contact surfaces define a second rotational stop 1415 and a second rotational stop 1414.

[0129] Each projection 1404 is housed in a recess 1413 of the first transmission element 141, and each drive finger 1412 is housed in a recess 1407 of the input shaft 140.

[0130] The distance between the stops 1405 and 1406 of a radial projection 1404 is less than the distance between the stops 1414 and 1415 defining the recess 1413 in which the radial projection 1404 is housed. Similarly, the distance between the stops 1414 and 1415 of a drive finger 1412 is less than the distance between the stops 1405 and 1406 defining the recess 1407 in which the drive finger 1412 is housed.

[0131] Thus, the input shaft 140 is rotationally movable relative to the first transmission element 141 over a predetermined angular range between:

[0132] - a first extreme position in which the stops 1405 are supported against the stops 1415 so that the input shaft 140 is rotationally linked with the first transmission element 141 in the first direction of rotation;

[0133] - a second extreme position in which the stops 1406 are supported against the stops 1414 so that the input shaft 140 is rotationally linked with the first transmission element 141 in the second direction of rotation.

[0134] The inner bore 1410 of the first transmission element 141 does not have a cylindrical cross-section but is substantially elliptical or similar, for example resulting from a combination of a cylinder and an elliptical cylinder, or from two slightly offset cylinders, .... This conformation of the inner bore 1410 makes it possible to form clamping zones 1411 inside the bore 1410, the function of which will be described later.

[0135] The second transmission element 142 has a cylindrical section.

[0136] The bidirectional freewheel 14 includes at least one first locking element 143. In this embodiment, it includes two first locking elements 143.

[0137] The bidirectional freewheel 14 includes at least one second locking element 144. In this embodiment, it includes two second locking elements 144.

[0138] The inner bore 1410 includes as many jamming zones 1411 as the free wheel 14 includes first 143 and second 144 jamming elements.

[0139] The input shaft 140 is traversed by a through bore 1403 and includes, in addition to the drive zone 1400, a clamping zone 1401.

[0140] The clamping zone 1401 is crossed by two circumferential lights 1402 which open into the bore 1403.

[0141] These lights 1402 are separated by two unjamming pillars 1408 which extend along the X axis.

[0142] The clamping area 1401 of the input shaft 140 is housed in the inner bore 1410 of the first transmission element 141.

[0143] The second transmission element 142 is housed in the bore 1403 of the input shaft 140.

[0144] The first 143 and second 144 jamming elements are arranged between the first 141 and second 142 transmission elements.

[0145] More specifically, a first jamming element 143 and a second jamming element 144 are arranged in one of the lights 1402. A first jamming element 143 and a second jamming element 144 are also arranged in the other of the lights 1402.

[0146] Compression springs 145 are arranged between the first 143 and second 144 clamping elements housed in the same light 1402 and tend to move them away from each other.

[0147] Each first jamming element 143 comprises:

[0148] - a first contact surface 1430 with the first transmission element 141,

[0149] - a second contact surface 1431 with the second transmission element 142,

[0150] - a third contact surface 1432 with a bearing surface 14080 corresponding to one of the 1408 unjamming pillars, these surfaces extending parallel to the X axis.

[0151] Each second jamming element 144 comprises:

[0152] - a first contact surface 1440 with the first transmission element 141,

[0153] - a second contact surface 1441 with the second transmission element 142,

[0154] - a third contact surface 1442 with a bearing surface 14080 corresponding to one of the 1408 unjamming pillars, these surfaces extending parallel to the X axis.

[0155] The first 143 locking elements can take:

[0156] - a disengaged state in which the first transmission element 141 is free in rotation relative to the second transmission element 142 in the first direction of rotation;

[0157] - a transmission state in which they act on the first element of transmission 141 and on the second transmission element 142 to link the first transmission element 141 in rotation with the second transmission element 142 in the first direction of rotation.

[0158] In the transmission state of the first clamping elements 143, in which they are held by the compression springs 145, :

[0159] - the first contact surfaces 1430 are pressed against the areas of corresponding 1411 clamping of the first 141 transmission element,

[0160] - the second contact surfaces 1431 are pressed against the second 142 transmission element, and

[0161] - the input shaft 140 is free insofar as it is not driven by the motor. It can therefore be located, or even move, between the stops 1414 and 1415. The bearing surfaces 14080 of the jamming pillars 1408 can therefore potentially be close to or even in contact with the third contact surfaces 1432. However, since the input shaft 140 is not driven by the motor, it does not exert a jamming force that would be likely to unjam the first jamming elements 143, even if the jamming pillars 1408 and the third contact surfaces 1432 are in contact.

[0162] In the transmission state, the substantially elliptical (or non-cylindrical) shape of the bore 1410 of the first transmission element 141, combined with the complementary shape of the first clamping elements 143, results in a torque on the first transmission element 141 in the first direction of rotation causing the first clamping elements 143 to jam between the clamping zones 1411 and the second transmission element 142. This causes the first transmission element 141 to lock against the second transmission element 142 in the first direction of rotation.

[0163] In the unjammed state of the first jamming elements 143, :

[0164] - the bearing surfaces 14080 of the unjamming pillars 1408 are pressed against the third contact surfaces 1432 of the first clamping elements 143, and exert on them a force against the effect of the springs 145. This has the following two consequences:

[0165] - the first contact surfaces 1430 tend to move away from the pinching areas 1411 corresponding to the first 141 transmission element,

[0166] - the second contact surfaces 1431 tend to move radially away from the second transmission element 142, so that the first jamming elements 143 are no longer jammed between the jamming zones 1411 and the second transmission element 142, and can slide freely on the latter, thus freeing the rotation of the first transmission element 141 relative to the second transmission element 142 in the first direction of rotation.

[0167] The second set of jammers 144 can take:

[0168] - a disengaged state in which the first transmission element 141 is free in rotation relative to the second transmission element 142 in a second direction of rotation opposite to the first direction of rotation;

[0169] - a transmission state in which the second locking elements 144 act on the first transmission element 141 and on the second transmission element 142 to link the first transmission element 141 in rotation with the second transmission element 142 in the second direction of rotation.

[0170] In the transmission state, in which the second locking elements 144 are held by the compression springs 145, :

[0171] - the first contact surfaces 1440 are pressed against the areas of corresponding 1411 clamping of the first 141 transmission element,

[0172] - the second contact surfaces 1441 are pressed against the second 142 transmission element, and

[0173] - the input shaft 140 is free insofar as it is not driven by the motor. It can therefore be located, or even move, between the stops 1414 and 1415. The bearing surfaces 14080 of the jamming pillars 1408 can therefore potentially be close to or in contact with the third contact surfaces 1442. However, since the input shaft 140 is not driven by the motor, it does not exert a jamming force that would be likely to unjam the second jamming elements 144, even if the jamming pillars 1408 and the third contact surfaces 1442 are in contact.

[0174] In the transmission state, the substantially elliptical (or non-cylindrical) shape of the bore 1410 of the first transmission element 141, combined with the complementary shape of the second clamping elements 144, results in a torque on the first transmission element 141 in the second direction of rotation causing the second clamping elements 144 to jam between the jamming zones 1411 and the second transmission element 142. This leads to the rotational locking of the first transmission element 141 with the second transmission element 142 in the second direction of rotation.

[0175] In the unjammed state of the second jamming elements 144, :

[0176] - the bearing surfaces 14080 of the unjamming pillars 1408 are pressed against the third contact surfaces 1442 of the second locking elements 144, and exert on them a force against the effect of the springs 145. This has the following two consequences:

[0177] - the first contact surfaces 1440 tend to move away from the pinching areas 1411 corresponding to the first 141 transmission element,

[0178] - the second contact surfaces 1441 tend to move radially away from the second transmission element 142, so that the second jamming elements 144 are no longer jammed between the jamming zones 1411 and the second transmission element 142, and can slide freely on the latter, thus freeing the rotation of the first transmission element 141 relative to the second transmission element 142 in the second direction of rotation.

[0179] The input shaft 140, which is rotationally movable relative to the first transmission element 141, is configured to act:

[0180] - on the first jamming elements 143 to place them in the jammed state when The input shaft 140 is driven in rotation by the rotor in the first direction of rotation, and

[0181] - on the second jamming elements 144 to place them in the jammed state when the input shaft 140 is driven in rotation by the rotor in the second direction of rotation.

[0182] When input tree 140 occupies:

[0183] - its first extreme position, the first 143 jamming elements are in their state unblocked;

[0184] - its second extreme position, the second jamming elements 144 are in their state unblocked.

[0185] When the input shaft 140 occupies an intermediate position between its two extreme positions, the first clamping elements 143 and the second clamping elements 144 are then in their transmission state. They are held in this state by the springs 145.

[0186] It should be noted that the angular play due to the width of the radial projections 1404 and the drive fingers 1412, which allows passage from one to the other of the extreme positions of the input shaft 140 relative to the first transmission element 141, is large enough so that within this play, the jamming pillars 1409 have enough angular travel to jam the jamming elements 143, 144 before the radial projections 1404 and the drive fingers 1412 come into contact.

[0187] Optional elastic connection between the second transmission element and the output shaft

[0188] Optionally, the output shaft 12 and the second transmission element 142 are linked by an elastic link 15 along the axis of rotation X of the output shaft 12.

[0189] The second transmission element 142 and the output shaft 12 are connected by a connecting zone 1500 with which they form a single unit. The elastic connection 15 is achieved by reducing the cross-section of the connecting zone 1500 relative to the cross-sections of the second transmission element 142 and the output shaft 12.

[0190] Alternatively, the second transmission element 142 and the output shaft 12 are linked by a torsional elastic element which provides the function of the elastic connection, ii. Operation Screwing process

[0191] When the engine is stopped, the input shaft 140 is in an intermediate position between its two extreme positions. The first clamping elements 143 and the second clamping elements 144 are then in their transmission states.

[0192] To perform a screwing operation, an operator activates the trigger 100. The rotor 111 of the motor 11 then begins to rotate in the screwing direction. As a result, it drives the input shaft 140 in rotation in that direction.

[0193] The input shaft 140 rotates inside the first transmission element 141 from its intermediate position to its first extreme position. During this rotation:

[0194] - the 1408 unjamming pillars exert a force on the first elements jammer 143 against the effect of springs 145, so as to place the first jammer elements 143 in their unjammed state,

[0195] - then, when the input shaft 140 reaches its first extreme position, the projections radial 1404 of the input shaft 140 come into contact with the drive fingers 1412 of the first transmission element 141 so that the input shaft 140 drives the first transmission element 141 in rotation and therefore the rotating cage 130 in the direction of screwing.

[0196] Because the first locking elements 143 are in their unjammed state, the first drive element 141 is not then connected in rotation in the screwing direction with the second drive element 142, and the cage 130 is therefore driven in rotation relative to the output shaft 12.

[0197] The cage 130 rotates in the screwing direction until the hammers 131 strike the anvils 120. A torque impact is then transmitted to the shaft of output 12 which rotates in the direction of screwing and drives the element to be screwed with which it cooperates.

[0198] Several impacts thus occur successively until the screwed element is tightened to the desired tightening torque.

[0199] After each impact, the motor stops and the cage 130 tends to rebound, that is, to rotate in the unscrewing direction. However, since the rotor 111 is not driven in the unscrewing direction, the second locking elements 144 are in their transmission state. The first transmission element 141 and the second transmission element 142 are therefore rotationally linked in the unscrewing direction.

[0200] Like:

[0201] - the second transmission element 142 is blocked from rotation by the assembly in screwing course with which the output shaft 12 cooperates,

[0202] - the first transmission element 141 is rotationally linked with the second element of transmission 142 in the unscrewing direction, and

[0203] - the rotating cage 130 is rotationally linked with the first transmission element 141,

[0204] the rotating cage 130 is immobilized in rotation in the direction of unscrewing.

[0205] The motor is therefore not driven by the first transmission element 141 in the unscrewing direction since the assembly is blocked by the screwing element. It should be noted that the rebound torque is less than the tightening torque, so this blocking does not cause the screwing element to unscrew.

[0206] This prevents unwanted current from being generated in the motor.

[0207] This also allows another impact to be restarted from a stationary engine and therefore avoids "wasting" energy by braking the motor's rotation before restarting it in the direction of screwing.

[0208] Furthermore, during the rebounds, the first transmission element 141 locks onto the second transmission element 142, and not onto a portion of the housing. Consequently, this locking is not felt by the operator. Unscrewing procedure

[0209] A tool according to the invention is reversible and allows unscrewing operations to be carried out.

[0210] When the engine is stopped, the input shaft 140 is in its intermediate position between its two extreme positions. The first clamping elements 143 and the second clamping elements 144 are then in their transmission states.

[0211] To perform an unscrewing operation, an operator activates the trigger 100. The rotor 111 of the motor 11 then begins to rotate in the unscrewing direction. As a result, it drives the input shaft 140 in rotation in that direction.

[0212] The input shaft 140 rotates inside the first transmission element 141 from its intermediate position to its second extreme position in which:

[0213] - the input shaft 140 is rotationally linked with the first transmission element 141 and with the rotating cage 130 in the direction of unscrewing;

[0214] - the second jamming elements 144 are in their jammed state.

[0215] The first drive element 141 is then not rotationally linked in the unscrewing direction with the second drive element 142.

[0216] The cage 130 rotates in the unscrewing direction until the hammers 131 strike against the anvils 120. An impact of unscrewing torque is then transmitted to the output shaft 12 which rotates in the unscrewing direction and drives the element to be unscrewed with which it cooperates.

[0217] Several impacts occur successively until the element to be unscrewed is loosened.

[0218] After each impact, the motor stops and the cage 130 tends to rebound, that is, to rotate in the direction of tightening. However, since the rotor 111 does not rotate in the direction of tightening, the first clamping elements 143 are in their transmission state. The first transmission element 141 and the second transmission element 142 are therefore rotationally linked in the direction of tightening.

[0219] Like:

[0220] - the second transmission element 142 is blocked from rotation by the assembly in unscrewing course with which the output shaft 12 cooperates,

[0221] - the first transmission element 141 is rotationally linked with the second element of transmission 142 in the direction of screwing, and

[0222] - the rotating cage 130 is rotationally linked with the first transmission element 141,

[0223] The rotating cage 130 is prevented from rotating in the direction of screwing. The rotating cage 130 therefore cannot rebound in the direction of screwing.

[0224] The motor is therefore not driven by the first transmission element 141 in the direction of screwing since the assembly is blocked by the element to be unscrewed.

[0225] The advantages described in relation to screwing are identical during unscrewing.

[0226] Effect of the optional flexible connection between the second transmission element and the output shaft

[0227] When an elastic connection is made between the second transmission element 142 and the output shaft 12, this connection tends to deform in torsion and to store elastic potential energy during each attempt to rebound the first element transmission blocked in rotation, in the opposite direction to the screwing or unscrewing operation in progress, by the second transmission element 142.

[0228] At the end of each rebound attempt, this energy is returned to the first element 141, so as to impart an initial rotational speed to the cage 130 for the next impact. This saves even more electrical energy if the motor is electric, or pneumatic energy if the motor is in a pneumatic variant.

[0229] 6.1.2. Second variant: first transmission element equipped with stops training

[0230] A second variant of the first embodiment is presented in relation to figures 7, 8 and 9.

[0231] This second variant is identical to the first variant except that the input shaft 140 does not include a drive zone 1400 with radial projections 1404, and the first transmission element 141 does not include a drive zone with drive fingers 1412.

[0232] According to a different approach, the rotational linkage of the input shaft 140 with the first transmission element 141 in its first and second extreme positions is obtained in the following manner.

[0233] The input shaft includes at least one first rotational stop in the first direction of rotation 1405 and at least one first rotational stop in the second direction of rotation 1406. In the illustrated example, it includes two of each of these stops.

[0234] The first transmission element 141 comprises at least one second rotational connecting stop in the first direction of rotation 1415 and at least one second rotational connecting stop in the second direction of rotation 1414. In the illustrated example, it comprises two of each of these stops.

[0235] When the input shaft 140 occupies its first extreme position, the first clamping elements 143 are clamped between the first 1405 and second 1415 rotation link stops in the first direction of rotation, to link in rotation the input shaft 140 and the first transmission element 141 in the first direction of rotation.

[0236] When the input shaft 140 occupies its second extreme position, the second clamping elements 144 are clamped between the first 1406 and second 1414 rotation link stops, to link in rotation the input shaft 140 and the first transmission element 141 in the second direction of rotation.

[0237] The operation of a screwing / unscrewing device according to this variant is otherwise identical to that of the first variant. It also offers the same advantages as a device according to the first variant. It has the additional advantage of being more compact in length, since the rotational drive The first transmission element 141 via the input shaft 140 is done via the clamping elements 143, 144. The drive zone is therefore coincided with the clamping zone.

[0238] 6.2. Second embodiment: “pin clutch” (in English) i. Architecture

[0239] Figures 10, 11 and 12 illustrate a second embodiment of a screwing / unscrewing device according to the invention.

[0240] According to this second embodiment, a screwing / unscrewing device according to the invention is identical to that according to the first embodiment, and all its variants, except that the "twin hammer" type striking mechanism of the first embodiment is replaced in the second embodiment by a "pin clutch" type striking mechanism.

[0241] All variants of the first embodiment are applicable to the second embodiment.

[0242] A "pin clutch" type striking mechanism is known in itself to a person skilled in the art and is not described in further detail thereafter.

[0243] In this case, :

[0244] - the input shaft 140 is rotationally linked to the rotor shaft 112 along the X-axis,

[0245] - the first transmission element 141 is rotationally linked about the X-axis to the cage 130 carrying hammers 131, and

[0246] - the second transmission element 142 is rotationally linked along the X axis to the shaft exit 12 carrying the anvils 120. ii. Operation

[0247] The operation of a device according to this second embodiment is similar to that according to the first embodiment with regard to the object of the invention implementing the bi-directional freewheel.

Claims

Demands

1. An impact screwing and / or unscrewing device comprising a housing containing: - a rebounding impact mechanism capable of generating impacts, - a motor equipped with a rotor, - an output shaft capable of rotating a screwing element, said impact mechanism comprising: - a rotating cage, - at least one striking element carried by said rotating cage, and - at least one striking portion carried by said output shaft, said at least one striking element being capable of successively colliding with said at least one striking portion so as to transmit successive torque impacts to it, each collision inducing a rebound of the rotating cage at the end of each of said torque impacts, characterized in that it comprises a bidirectional freewheel, said bidirectional freewheel comprising: - an input shaft rotationally linked to said rotor, - a first transmission element rotationally linked to said cage,and - a second transmission element rotationally linked to said output shaft, said bidirectional freewheel being configured to: - release said first transmission element from rotation relative to said second transmission element in one direction of rotation and link said first transmission element from rotation with said input shaft in said direction of rotation when said input shaft is driven in rotation in said direction of rotation by said rotor relative to said second transmission element; - link said first transmission element from rotation with said second transmission element when said input shaft is not driven in rotation by said rotor, so as to lock said first transmission element from rotation relative to said second transmission element during the rebounds of said cage following said impacts generated by said impact mechanism.

2. Device according to claim 1 wherein said bidirectional freewheel comprises at least one first locking element and at least one second jamming element disposed between said first and second transmission elements, said first jamming element being able to take: - a jammed state in which said first transmission element is free in rotation relative to said second transmission element in a first direction of rotation; - a transmission state in which it acts on said first transmission element and said second transmission element to link said first transmission element in rotation with said second transmission element in said first direction of rotation; said second jamming element being able to take: - a jammed state in which said first transmission element is free in rotation relative to said second transmission element in a second direction of rotation opposite to said first direction of rotation;- a transmission state in which it acts on said first transmission element and said second transmission element to link said first transmission element in rotation with said second transmission element in said second direction of rotation; said input shaft being configured to: - act on said first jamming element to place it in the jammed state when it is driven in rotation in said first direction of rotation by said rotor, and - act on said second jamming element to place it in the jammed state when it is driven in rotation in said second direction of rotation by said rotor.

3. Device according to claim 2 comprising retaining means tending to maintain said first and second clamping elements in their transmission states when the input shaft is not driven in rotation by said rotor.

4. Device according to claim 2 or 3 wherein said input shaft is rotationally movable relative to said first transmission element over a predetermined angular range between: - a first extreme position in which it is rotationally linked with said first transmission element in said first direction of rotation and in which the first jamming element is in its jammed state; - a second extreme position in which it is linked in rotation with said first transmission element in said second direction of rotation and in which the second jamming element is in its jammed state.

5. Device according to claim 4 in which: - said input shaft comprises at least one first rotational stop in said first direction of rotation and at least one first rotational stop in said second direction of rotation, and - said first transmission element includes at least one second rotational connecting stop in said first direction of rotation and at least one second rotational connecting stop in said second direction of rotation, said at least one first and second rotational connecting stops in said first direction of rotation being in contact in said first extreme position of said input shaft; said at least one first and second rotational link stops in said second direction of rotation being in contact in said second extreme position of said input shaft.

6. Device according to claim 4 in which: - said input shaft comprises at least one first rotational stop in said first direction of rotation and at least one first rotational stop in said second direction of rotation, and - said first transmission element comprises at least one second rotational stop in said first direction of rotation and at least one second rotational stop in said second direction of rotation, said at least one first clamping element being clamped between said first and second rotational connecting stops in said first direction of rotation, in said first extreme position of said input shaft, to link said input shaft and said first transmission element in said first direction of rotation, said at least one second clamping element being clamped between said first and second rotational connecting stops, in said second direction of rotation in said second extreme position of said input shaft, to link said input shaft and said first transmission element in said second direction of rotation.

7. Device according to any one of claims 1 to 6 wherein said output shaft and said second transmission element are linked by an elastic connection along the axis of rotation of said output shaft.

8. Device according to claim 7 in which said second transmission element and said output shaft are linked by a connecting zone with which they form a single unit, said elastic connection being achieved by a reduction in the cross-section of said connecting zone.

9. Device according to claim 7 in which said second transmission element and said output shaft are linked by a torsional elastic element.

10. Device according to any one of claims 1 to 9 in which said rebounding striking mechanism belongs to the group comprising: - Twin hammer - Pin clutch.

11. A method for screwing and / or unscrewing by impact using a device according to any one of claims 1 to 10, said method comprising successive phases of driving said impact mechanism in rotation by said rotor and of rebounding said impact mechanism: - said first transmission element being free in rotation relative to said second transmission element in a direction of rotation and said first transmission element being rotationally linked with said input shaft in said direction of rotation when said input shaft is driven in rotation in said direction of rotation by said rotor relative to said second transmission element during said phases of driving said impact mechanism, - said first transmission element being rotationally linked with the second transmission element during said rebound phases during which said rotor is not driven in rotation;a rotation of said first transmission element relative to said second transmission element being thus blocked when said cage rebounds following an impact generated by said impact mechanism.;

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