Screw jack including a drive unit with adjustable positioning

Abstract

A spike driver (100) comprising: a tip (35) adaptable to be rotated for screwing or unscrewing a railway track fastener (101) (102), a drive unit (1) comprising a drive shaft arranged at the output of the drive unit (1), a transmission connecting the drive unit (1) to the tip (35) and configured to propagate, in an operational configuration of the spike driver (100), a rotational movement of the drive shaft in order to rotate the tip (35). The transmission comprising, successively from the drive unit (1): a transmission mechanism (7), and a driven shaft coupled to the drive shaft via the transmission mechanism (7). The drive shaft being offset relative to the driven shaft. Figure to be published with the abbreviation: Fig. 2

Description

Title of the invention: Screw driver comprising a drive unit with an adapted position Technical field of the invention

[0001] The present invention relates to a screw driver, in particular intended for railway construction sites. In particular, the screw driver is designed to selectively screw or unscrew the fasteners which fix the rails to the railway sleepers. State of the prior art

[0002] In the field of railway construction sites, it is known to use a screw driver to screw or unscrew fasteners. The screw driver comprises a motor mechanically connected to a screw driving head equipped with a rotating tip for the desired screwing or unscrewing.

[0003] The mechanical coupling between the motor and the screw driving head is generally achieved using a transmission system arranged between the motor and the screw driving head in a longitudinal direction of the screw driving machine which then successively comprises, in this longitudinal direction, the motor, the transmission system and the screw driving head. This transmission system can be seen as the set of mechanical components by which a movement from an output shaft of the motor to the screw driving head is propagated.

[0004] This length structure of the screw driver is not suitable in all cases. Subject of the invention

[0005] The present invention aims to provide a screw jack structure allowing its manufacture to be adapted to different needs.

[0006] To this end, the invention relates to a screw driver comprising: • a tip capable of being rotated in order to screw or unscrew a railway track fastener; • a drive group comprising a drive shaft arranged at the output of the drive group; • a transmission connecting the drive group to the bit and configured to propagate, in an operational configuration of the screw driver, a rotational movement of the drive shaft in order to drive the bit in rotation; the transmission comprising successively from the drive group: • a transmission mechanism; • a driven shaft coupled to the drive shaft via the transmission mechanism; the drive shaft being offset from the driven shaft.

[0007] The offset of the driven shaft relative to the drive shaft in combination with the transmission mechanism, which allows coupling by adapting to the offset, has the advantage of allowing a large latitude of positioning of the drive group and in particular of a motor that the drive group includes. This makes it possible to reduce the size and make the screw driver more compact, or to adapt to a particular configuration of the drive group, or to specific balancing needs of the screw driver. In addition, the latitude of positioning makes it possible, where appropriate, to make the drive group more accessible to an operator, in particular during maintenance and servicing operations when using the screw driver if the drive group requires it, for example when the motor of the drive group is a thermal engine.

[0008] The screw driver may further comprise one or more of the following features.

[0009] According to a characteristic of the screw driver, the drive shaft comprises a portion which extends in a first direction in a first sense at the output of the drive group towards the transmission mechanism and the driven shaft comprises a portion which extends in a second direction in a second sense oriented towards the end piece along a propagation path of the rotational movement of the drive shaft within the transmission, the first sense and the second sense being opposite.

[0010] This arrangement of portions of the drive shaft and the driven shaft in two opposite directions makes it possible to reduce the size, to make the screw driver more compact and to facilitate access to the drive unit by the operator.

[0011] According to a characteristic of the screw driver, the drive group is arranged vertically above at least one part of the driven shaft.

[0012] This arrangement of the drive group relative to the driven shaft makes it possible to limit the longitudinal size of the screw driver.

[0013] According to a characteristic of the screw driver, the drive group, the transmission mechanism and the driven shaft are arranged according to a C-shaped architecture.

[0014] This architecture has advantages in relation to the size of the screw driver and the proximity of the drive unit to the operator who can more easily interact with the drive unit if necessary.

[0015] According to a characteristic of the screw driver, the axis of the drive shaft and the axis of the driven shaft are substantially parallel to each other and, when the screw driver is in the operational configuration: • the axis of the drive shaft and the axis of the driven shaft have between them a level offset in a vertical direction of between 10 mm and 400 mm, and preferably between 10 mm and 220 mm, and an offset in a lateral direction strictly greater than 0 mm and less than or equal to 400 mm, and preferably less than or equal to 220 mm; or • the axis of the drive shaft and the axis of the driven shaft have a level offset between them in a vertical direction of between 10 mm and 400 mm, and one of the drive shaft and the driven shaft is arranged vertically above the other of the drive shaft and the driven shaft.

[0016] This makes it possible to arrange the center of gravity of the screw driver in an appropriate manner and to ensure the compactness and balance of the screw driver.

[0017] According to a characteristic of the screw driver, the drive group comprises a casing crossed by the drive shaft: • the casing and the transmission mechanism are in contact; or • in a direction substantially parallel to the axis of the drive shaft, the casing and the transmission mechanism are separated by a distance strictly greater than 0 mm and less than or equal to 1000 mm, and preferably less than or equal to 500 mm.

[0018] This advantageously makes it possible to index the longitudinal position of the drive group according to the length of the screw driver, in particular to facilitate its tilting to cooperate with a corresponding attachment and / or to facilitate the interactions of an operator with the drive group.

[0019] According to a characteristic of the screw driver, the transmission comprises a reduction mechanism arranged between the driven shaft and the end piece.

[0020] The reduction mechanism makes it possible to present a reduction, in particular mechanical, of the rotational movement between the driven shaft and the end piece in order to limit the rotational speed of the end piece.

[0021] According to a feature of the screw driver, in the operational configuration of the screw driver, the drive group is positioned at a height level higher than the height level of the reduction mechanism relative to the ground.

[0022] This positioning of the drive group relative to the reduction mechanism makes it possible to position and orient the drive group to make it more accessible to the operator.

[0023] According to a characteristic of the screw driver, the reduction mechanism is a single-speed gearbox.

[0024] This embodiment with the single-speed gearbox makes it possible to simplify the mechanical design of the screw driver, to reduce the cost and to simplify use, in particular improving the comfort of use.

[0025] According to a characteristic of the screw driver, the reduction mechanism is a gearbox having at least two speeds having different transmission ratios.

[0026] This embodiment with a gearbox comprising two transmission ratios allows the use of a lower power engine. This has advantages in terms of engine costs and energy consumption and allows the screw driver to be made lighter (thus improving its ergonomics of use due to its lighter weight).

[0027] According to a characteristic of the screw driver, the screw driver comprises a casing and the transmission comprises: • an angle gear arranged in the casing; • a shaft connecting the angle gear to the end piece arranged outside the casing.

[0028] The angle transmission makes it possible to propagate the rotational movement to the end piece facing the ground, if necessary while ensuring a reduction in the movement.

[0029] According to a characteristic of the screw driver, the reduction mechanism is: • located in the crankcase; • fixed to the casing; or • located at a distance from the casing so that at least one transmission shaft connects the reduction mechanism to the bevel gear.

[0030] This allows a wide choice in the design of the screw driver. By integrating the reduction mechanism into the housing, this allows costs to be reduced by limiting the number of protective boxes (the housing acting as a protective box can accommodate several functions), to reduce weight, to simplify maintenance, and to have better performance thanks to the reduction in the number of components, particularly mechanical ones, in motion.

[0031] According to a characteristic of the screw driver, the screw driver comprises a flywheel for temporarily transmitting a torque to the end piece having a value greater than the value of a torque delivered by the drive shaft.

[0032] The flywheel does not allow a continuous demand for torque to be met but allows sufficient temporary torque to be obtained, linked to its inertia, to pass a hard point only, in particular at a predetermined speed of rotation of the tip.

[0033] According to a characteristic of the screw driver, the transmission mechanism comprises a continuously variable transmission.

[0034] A continuously variable transmission has the advantage of continuously varying the gear ratio of the drive shaft to the driven shaft coupled to the bit, resulting in an automatic adaptation of the rotation speed of the bit as a function of the resistance that the fastener opposes to the bit during the screwing or unscrewing of the fastener, thus facilitating the passage of a hard point (linked to the resistive torque caused by the cooperation of the bit with the fastener and propagating from the bit to the driven shaft). Brief description of the drawings

[0035] The invention will be better understood upon reading the detailed description which follows, given solely by way of non-limiting example and made with reference to the appended drawings listed below.

[0036] [Fig-1] [Fig.l] schematically represents a perspective view of the tire- molder of [Fig.l] according to a particular embodiment.

[0037] [Fig.2] [Fig.2] schematically represents the screw driver of [Fig.l] equipped with a trolley and arranged on a railway track and in particular in an operational configuration of the screw driver.

[0038] [Fig.3] [Fig.3] represents a side view of the screw driver of [Fig.l].

[0039] [Fig.4] [Fig.4] represents a sectional view of the screw tap practiced parallel aligned with the plane of [Fig.3] so that the cutting plane passes through a driven shaft of the screw driver.

[0040] [Fig.5] [Fig.5] shows a partial view of the screw driver of [Fig.3] where the screw driver includes a continuously variable transmission, said view showing in an exploded manner the mounting of the continuously variable transmission within the screw driver with a belt of the continuously variable transmission removed in order to more clearly show components of the continuously variable transmission.

[0041] [Fig.6] [Fig.6] represents a side view of the screw driver of [Fig.l] showing a parametric positioning of the drive shaft and the driven shaft.

[0042] [Fig.7] [Fig.7] represents a block diagram schematically describing a C-shaped architecture of the screw driver according to a particular embodiment.

[0043] [Fig.8] [Fig.8] represents a block diagram schematically describing a Z-shaped architecture of the screw driver according to a particular embodiment.

[0044] [Fig.9] [Fig.9] represents a block diagram schematically describing an L-shaped architecture of the screw driver according to a particular embodiment.

[0045] [Fig. 10] [Fig. 10] represents a block diagram schematically describing an architecture of the screw driver equipped with a flywheel according to a particular embodiment.

[0046] In these figures, the same references are used to designate the same elements. The elements represented in the different figures are not necessarily drawn to scale in order to facilitate understanding of the figures. Detailed description

[0047] In the present invention, two elements are "coupled" or "linked", for example mechanically, when they are associated with each other by a connection, for example mechanical, causing the behavior of one of the two elements to affect that of the other element. This connection can be direct when the two elements considered are in contact, or indirect when the two elements considered are linked via one or more intermediate elements such as drive shafts, drive mechanisms, or other.

[0048] In the present description, by "substantially parallel" is meant parallel or parallel to plus or minus 10 degrees.

[0049] By "between two values", it is understood in the present description that these two values ​​form the limits of a corresponding range for which the two values ​​are included.

[0050] A screw driver 100 according to the invention, a particular embodiment of which is illustrated by way of example in FIGS. 1 to 6, comprises a tip 35 capable of being rotated in order to screw or unscrew a fastener 101 of a railway track 102, a drive group 1 comprising a drive shaft 2 arranged at the output of the drive group 1 and a transmission connecting, for example mechanically, the drive group 1 to the tip 35 to propagate, in an operational configuration of the screw driver 100, a rotational movement of the drive shaft 2 in order to drive the tip 35 in rotation. Thus, the transmission is in particular linked, on the one hand, to the drive group 1 and, on the other hand, to the tip 35. The screw driver 100 may comprise a screw driving head 3 which comprises the tip 35.

[0051] The fastener 101 may be any type of mounting element used for fixing a rail 103 of the railway track 102, such as for example a lag screw or a threaded fastener, to a sleeper 104 of the railway track 102, as can be seen in [Fig.2].

[0052] The tip 35 may be a tightening key, for example hexagonal, having a shape adapted to cooperate with a head of the fastener 101.

[0053] The drive group 1 has the role in particular of generating mechanical energy which it transmits to the outside by means of the drive shaft 2, preferably rotary. The screw driver 100 can then be configured to exploit, in the operational configuration described in more detail below, the mechanical energy from the drive shaft 2 in order to ensure the appropriate rotation of the end piece 35 for the desired screwing or unscrewing of the fastener 101.

[0054] The transmission, connecting the drive group 1 to the end piece 35, successively comprises, from the drive group 1, a transmission mechanism 7 and a driven shaft 5 coupled, for example mechanically, to the drive shaft 2 via the transmission mechanism 7. The drive shaft 2 is offset relative to the driven shaft 5.

[0055] By “offset” when speaking of the drive shaft 2 and the driven shaft 5, it is understood that the drive shaft 2 and the driven shaft 5 are not aligned with each other. relative to each other or coinciding / coaxial.

[0056] By transmission mechanism 7, it is understood that the movement generated by the drive group 1 is in particular transmitted at a given moment via one or more members such as for example a belt, a gear or other. The transmission mechanism 7 may be entirely or partly mechanical or entirely or partly hydraulic. An advantage of the mechanical transmission mechanism 7 is that it is easier to maintain and less expensive than a hydraulic transmission for example (coupling using a fluid).

[0057] The drive group 1 may comprise a motor 18 whose motor shaft forms the drive shaft 2 mentioned above or may comprise the motor 18 and a reduction mechanism (not shown) coupled, for example mechanically, to the motor shaft of the motor 18 in order to present the drive shaft 2 with a predefined reduction in rotation, depending on the reduction mechanism, in the operational configuration of the screw driver 100.

[0058] The motor 18 may be an electric, thermal, hydraulic or hydrogen motor.

[0059] The offset of the driven shaft 5 relative to the drive shaft 2 in combination to the transmission mechanism 7, which allows the coupling of the drive shaft 2 to the driven shaft 5 by adapting to the offset, has the advantage of allowing a large latitude of positioning of the drive group 1 and in particular of the motor 18 of the drive group 1. This makes it possible to reduce the size of the screw driver 100 in order to make it more compact. In addition, the latitude of positioning makes it possible to make the drive group 1 more accessible to the operator, in particular during maintenance and servicing operations if the drive group 1 requires it, for example when the motor 18 is a thermal engine.

[0060] For example, the screw driver 100, as illustrated in [Fig. 2], is arranged on the railway track 102 to move along the latter in order to position it in a suitable manner to proceed with the screwing or unscrewing of a corresponding fastener 101. For this purpose, the screw driver 100 may comprise a rolling carriage 105 configured to roll on the railway track 102 and configured to allow a tilting of a part of the screw driver 100 in order to position it to allow cooperation of the end piece 35 with a corresponding fastener 101 to be screwed or unscrewed and / or to release it from the fastener 101 once this fastener 101 has been screwed. The rolling carriage 105 may comprise parts 105a, 105b each provided with wheels and positioned to roll on rails 103 of the railway track 102.The parts 105a, 105b of the carriage can be connected to each other by a crosspiece 105c of the carriage 105 on which said part of the screw driver 100 is mounted to tilt and rotate orthogonally to the tilting axis to allow fasteners 101 to be screwed or unscrewed on either side of the same rail 103.

[0061] In particular, and in order to facilitate its handling, the screw driver 100 may comprise a control station 34 comprising two guide arms each equipped with a handle 20, 21 allowing the handling of the screw driver 100 by an operator, and in particular allowing the tilting mentioned above to be guided.

[0062] In particular, in the operational configuration of the screw driver 100, the latter is positioned so that the end piece 35 is oriented towards the ground S ([Fig.2]), in particular so as to allow its cooperation with a corresponding fastener 101.

[0063] According to one embodiment, as can be seen in [Fig. 5], the drive shaft 2 comprises a portion 2a which extends in a first direction in a first sense s1 at the output of the drive group 1 towards the transmission mechanism 7 and in this case the driven shaft 5 comprises a portion 5a which extends in a second direction in a second sense s2 oriented towards the end piece 35 along a propagation path of the rotational movement of the drive shaft 2 within the transmission, the first sense s1 and the second sense s2 being opposite.

[0064] By "opposite directions", as illustrated in Figures 3 to 5, it is understood that the first direction s1 of propagation of the rotational movement of the drive shaft 2 is from the drive group 1 to the transmission mechanism 7, while the second direction s2 corresponds to the propagation of the rotational movement from the transmission mechanism 7 to the screw-driving head 3 to drive the end piece 35 in rotation.

[0065] In particular, the transmission mechanism 7 is preferably directly coupled, on the one hand, to the drive group 1, and, on the other hand, to the screw driving head 3 or at least to a part of the screw driving head 3 in order to ensure the rotation of the end piece 35 in the operational configuration of the screw driving machine 100. This defines the propagation path of the rotational movement of the drive shaft 2 from the drive group 1 to the end piece 35. The transmission mechanism 7 can be seen as the set of components, for example mechanical, by which the movement from the drive group 1 to the end piece 35 is propagated. A corresponding component can have an influence on the way in which the movement is propagated, for example by slowing it down or accelerating it, by changing the direction of rotation (depending on whether the fastener 101 is to be screwed or unscrewed).

[0066] According to one embodiment, at least the drive group 1 is arranged vertically above at least a portion of the driven shaft 5, in particular in the operational configuration where the end piece 35 is oriented towards the ground S. This arrangement is particularly advantageous with respect to the longitudinal size of the screw driver 100 and allows easy accessibility of the drive group 1, which becomes closer to the operator because the total length of the screw driver 100 is limited.

[0067] According to one embodiment, the drive group 1, the mechanism 7 of transmission and the driven shaft 5 are arranged according to a C-shaped architecture. For example, in figures 1 to 5, the screw driver 100 is such that the drive group 1, the transmission mechanism 7 and the driven shaft 5 form a C, in particular open in the direction of the control station 34; this makes it possible, for example, to bring the drive group 1 closer to the operator who can more easily interact with the drive group 1 and, for example: • with a launcher 31 of the training group 1 allowing the engine 18 of the training group 1 to be launched; • with a tank 32 of the drive group 1 to fill it with fuel if the engine 18 is a thermal engine supplied with fuel by the tank 32.

[0068] In other words, the drive group 1 can be rotated so that the launcher 31 which it comprises is oriented towards, or arranged on the side of, the control station 34. In this case, the drive shaft 2 and the launcher 31 are in particular arranged at the levels of opposite sides of the drive group 1 (see in particular [Fig. 3]).

[0069] According to other embodiments, the drive group 1, the transmission mechanism 7 and the driven shaft 5 can be mounted according to different architectures called Z or L. These two Z and L architectures of the screw driver 100 are illustrated in the form of block diagrams respectively in FIGS. 8 and 9. The locations of the drive group 1 and the transmission mechanism 7 vary according to the architecture considered.

[0070] For the C-shaped architecture, the drive group 1 can be directly above the driven shaft 5 in the operational configuration of the screw driver 100 and the transmission mechanism 7 connects the driven shaft 5 to the drive group 1. This architecture makes it possible to limit the length of the screw driver 100, for example measured between the transmission mechanism 7 and the screw driver head 3, the size of the screw driver 100 is thus limited.

[0071] For the Z-shaped architecture, as shown in [Fig.8], the location of the drive group 1 is such that the latter forms a first end of the screw driver 100 opposite a second end of the screw driver 100 formed by the screw driver head 3. We then find, depending on the length of the screw driver 100, the drive group 1, the transmission mechanism 7, the driven shaft 5 and the screw driver head 3.

[0072] For the L-shaped architecture, as shown in [Fig.9], the locations of the drive group 1, the transmission mechanism 7 and the driven shaft 5 are aligned in a direction given by the height in the operational configuration. Generally speaking, the Z-shaped and L-shaped architectures can have engineering advantages with respect to adjusting the positioning of the group 1 drive and represent alternatives to the C architecture, which remains the preferred architecture because it is very advantageous compared to the size of the 100 screw driver.

[0073] As can be seen in Figures 5 and 6, the axis of the drive shaft 2 and the axis of the driven shaft 5 may be substantially parallel to each other and, when the screw driver 100 is in the operational configuration: • the axis of the drive shaft 2 and the axis of the driven shaft 5 have between them a level offset in a vertical direction Dv of between 10 mm and 400 mm, and preferably between 10 mm and 220 mm, and an offset in a lateral direction DI strictly greater than 0 mm and less than or equal to 400 mm, and preferably less than or equal to 220 mm; or • the axis of the drive shaft 2 and the axis of the driven shaft 5 have between them a level offset in a vertical direction Dv of between 10 mm and 400 mm, and one of the drive shaft 2 and the driven shaft 5 is arranged vertically above the other of the drive shaft 2 and the driven shaft 5.

[0074] The vertical offset Dv and the lateral offset DI make it possible to define a preferred position of the drive shaft 2 and (therefore of the drive group 1) relative to that of the driven shaft 5 ensuring the balancing of the screw driver 100, its compactness and its optimal operation.

[0075] By “level offset in a vertical direction Dv”, is meant the distance separating two substantially parallel horizontal planes, the axis of the driven shaft 5 being included in one of the two horizontal planes and the axis of the drive shaft 2 being included in the other of the two horizontal planes.

[0076] As can be seen in Figures 1, 3, 4 and 5, the drive group 1 may comprise a casing 43 through which the drive shaft 2 passes. The casing 43 and the transmission mechanism 7 may be in contact. Alternatively, in a direction substantially parallel to the axis of the drive shaft 2, the casing 43 and the transmission mechanism 7 are separated by a distance strictly greater than 0 mm and less than or equal to 1000 mm, and preferably less than or equal to 500 mm. In other words, the casing 43 may comprise an edge facing an edge of the transmission mechanism 7, these two edges being arranged in said direction substantially parallel to the axis of the drive shaft 2 and being in contact or separated by said distance.

[0077] This advantageously makes it possible to index the longitudinal position of the drive group 1 according to the length of the screw driver 100, in particular to facilitate its tilting to cooperate with a corresponding attachment 101 and / or to facilitate the interactions of an operator with the drive group 1.

[0078] The transmission, connecting the drive group 1 to the end piece 35, may comprise a reduction mechanism 30, 40 arranged between the driven shaft 5 and the end piece 35. The reduction mechanism 30, 40 may comprise an input shaft formed by the driven shaft 5 or coupled, for example mechanically, to the driven shaft 5, and is coupled or intended to be coupled to an output shaft 6 located downstream of the transmission mechanism 30, 40 on the propagation path mentioned above. As illustrated in [Fig. 4], the output shaft 6 is connected, here mechanically, with the screw driving head 3 to drive the end piece 35 in rotation in the operational configuration. The purpose of the reduction mechanism 30, 40 is to allow at least part of the rotation speed of the end piece 35 to be conditioned.

[0079] Furthermore, the screw driver 100, and more particularly the transmission, may comprise a reverser 29 for the direction of rotation of the end piece 35. The reduction mechanism 30, 40 may then be associated with the reverser 29 configured to selectively present: • a first operating mode in which the driven shaft 5 is coupled, for example mechanically, to the output shaft 6 to drive the end piece 35 in a first direction F1 of rotation; • a second operating mode in which the driven shaft 5 is coupled, for example mechanically, to the output shaft 6 to drive the end piece 35 in a second direction F2 of rotation opposite to the first direction F1 of rotation.

[0080] The reverser 29 for the direction of rotation of the end piece 35 can be controlled from a selector, for example located at one of the control handles 20, 21 of the screw driver 100. The handles 20, 21 being each arranged at the end of a corresponding arm of the control station 34, one of the arms can be movable and thus forms the selector so that the position of said arm can induce the appropriate control of the direction reverser 29.

[0081] For example, the transmission comprises a transmission device 4 comprising the inverter 29 and the reduction mechanism 30, 40, for example arranged in the same housing. The input shaft of the reduction mechanism 30, 40 may form an input shaft of the transmission device 4 (i.e. the driven shaft 5 may form the input shaft of the transmission device 4) and the output shaft 6 may form the output of the transmission device 4. In particular, in [Fig. 4], in the operational configuration, the drive group 1 is located directly above the transmission device 4.

[0082] For example, in the context of the C-shaped architecture of [Fig.7], the drive group 1 is located directly above the transmission device 4. In this case, the output shaft 6 can be connected to the screw-driving head 3.

[0083] For example, in the operational configuration of the screw driver 100, the drive group 1 is positioned at a height level higher than the level of height of the mechanism 30, 40 of reduction relative to the ground S. This arrangement makes it possible to advantageously limit the longitudinal size of the screw driver 100 by staggering parts of the screw driver 100.

[0084] According to one embodiment, the drive group 1 is positioned directly above the reduction mechanism 30, 40 in the operational configuration of the screw driver 100.

[0085] According to one embodiment, the reduction mechanism 30, 40 is a single-speed gearbox 40. The gearbox 40 is integrated between the driven shaft 5 and the output shaft 6 so that, in the first and second operating modes mentioned above, the coupling between the driven shaft 5 and the output shaft 6 is made at least via the direction selector 29 and all or part of the gearbox 40. If the drive group 1 is powerful enough, the single-speed gearbox 40 may be sufficient for the use of the screw driver 100.

[0086] According to one embodiment, the single-speed gearbox 40 can be placed in the screw-driving head 3, for example to limit the size of the screw-driving machine 100.

[0087] According to one embodiment, the reduction mechanism 30, 40 is a gearbox 30 having at least two speeds having different transmission ratios. For example, the gearbox 30 may have a first transmission ratio and a second transmission ratio. The screw driver 100 is configured to selectively engage, either manually using a non-visible lever or automatically on command of an actuator, for example arranged on one of the handles 20, 21, the first ratio or the second ratio so as to influence the rotation speed of the end piece 35. The use of the gearbox 30 makes it possible to use a less powerful drive group 1, thus making it possible to lighten the screw driver 100.

[0088] According to one embodiment, it is possible to integrate the gearbox 30 into the screw driving head 3, for example to limit the size of the screw driving machine 100.

[0089] According to one embodiment, the screw driver 100 comprises a casing 38 and the transmission, connecting the drive group 1 to the end piece 35, comprises an angle gear 33 arranged in the casing 38, and a shaft 37 (in particular also called the output shaft of the screw driver head 3) connecting the angle gear 33 to the end piece 35 arranged outside the casing 38, as can be seen in the sectional view of the screw driver 100 in [Fig.4]. The angle gear 33 can, if necessary, provide a reduction, but above all makes it possible to propagate the rotational movement to the end piece 35 oriented towards the ground S in the operational configuration.

[0090] Where appropriate, any part of the screw-driving head 3 participating in the propagation of the rotational movement upstream of the end piece 35 on the propagation path is part of the transmission.

[0091] The reduction mechanism 30, 40 may be located in the casing 38; or fixed to the casing 38; or located at a distance from the casing 38 so that at least one transmission shaft connects the reduction mechanism 30, 40 to the angle transmission 33.

[0092] When the reduction mechanism 30, 40 is located in the casing 38, this advantageously makes it possible to reduce costs by pooling the casings and parts, to reduce the weight of the screw driver 100, to simplify (or even reduce) maintenance operations and to improve the efficiency of the screw driver 100, if necessary, thanks to the reduction in the number of components, in particular mechanical components in motion. For the same reasons, the inverter 29 can also be housed in the casing 38.

[0093] Thus, it follows from what has been described above that the drive group 1 can be located, in the operational configuration, directly above the casing 38.

[0094] According to an embodiment as illustrated in [Fig.4], the screw driving head 3 comprises an input shaft 36 making it possible to connect the reduction mechanism 30, 40 to the angle transmission 33, and is coupled, for example mechanically, to the output shaft 6 of the reduction mechanism 30, 40.

[0095] According to one embodiment, the screw driver 100 comprises, as shown schematically in [Fig. 10], a flywheel 50 for temporarily transmitting a torque to the end piece 35 having a value greater than the value of a torque delivered by the drive shaft 2.

[0096] The flywheel 50 does not allow a continuous demand for torque to be met but allows sufficient torque to be obtained, linked to its inertia, to overcome a hard point.

[0097] In [Fig. 10], the flywheel 50 is shown on the path of propagation of the movement between the drive group 1 and the transmission mechanism 7: at this level the flywheel 50 can benefit from a rotation speed equal to the rotation speed of the drive shaft 2. However, depending on the design requirements of the screw driver 100, the flywheel 50 can be placed elsewhere on the path of propagation of the movement, for example downstream of the transmission mechanism 7 (in particular after a possible reduction of the rotational movement); in this case, the flywheel 50 can be oversized so that its mass, then higher, compensates for its generally lower rotation speed at this level than directly at the output of the drive group 1 depending on the transmission mechanism 7 and / or the reduction. According to a variant, the drive group 1 comprises the flywheel 50.

[0098] According to one embodiment, the transmission mechanism 7 comprises, or is, a continuously variable transmission. The continuously variable transmission, as illustrated in more detail and by way of example in Figures 1 to 5, is coupled (for example mechanically), on the one hand, to the drive shaft 2 (in particular by direct coupling or via an intermediate shaft that the mechanism 7 comprises) transmission) and, on the other hand, to the driven shaft 5 (in particular by direct coupling) to ensure, in the operational configuration, the automatic adaptation of the rotation speed of the end piece 35. Of course, in the operational configuration, the driven shaft 5 is coupled, for example mechanically, to the screw driving head 3 and more particularly to the end piece 35. This thus results in an automatic adaptation of the rotation speed of the screw driving head 3 as a function of the resistance that the fastener 101 opposes to the end piece 35 of the screw driving head 3 during the screwing or unscrewing of the fastener 101, which facilitates the passage of a possible hard point. In other words, in the operational configuration of the screw driver 100, the continuously variable transmission ensures the automatic adaptation of the rotation speed of the bit 35 by continuously varying the gear ratio / transmission from the drive shaft 2 to the driven shaft 5.

[0099] Continuously variable transmission is also known as CVT, which stands for “Continuously Variable Transmission” in English.

[0100] Preferably, the continuously variable transmission is arranged at the output of the drive group 1 (i.e. the continuously variable transmission is directly coupled to the drive shaft 2 or to an intermediate shaft located in the extension of the drive shaft 2) to have a maximum centrifugal force (and therefore a maximum speed), which makes it possible to maximize the operation of the continuously variable transmission. The continuously variable transmission notably avoids the use of a flywheel as described above.

[0101] A particular embodiment of the transmission mechanism 7 forming the continuously variable transmission is visible in Figures 1 to 5. According to this embodiment, the continuously variable transmission comprises a driving pulley 8, a driven pulley 11, a first return member 14a, a second return member 14b and a belt 15 connecting the driving pulley 8 and the driven pulley 11. The driving pulley 8 is mounted on the drive shaft 2 and comprises a first flange 9 fixed relative to the drive shaft 2 and a second flange 10 movable in translation along the drive shaft 2. The driven pulley 11 is mounted on the driven shaft 5 and comprises a third flange 12 fixed relative to the driven shaft 5 and a fourth flange 13 movable in translation along the driven shaft 5.The first return member 14a constantly urges the second flange 10 in a direction opposite to the first flange 9, thus tending to move the second flange 10 away from the first flange 9; and the second return member 14b constantly urges the fourth flange 13 in the direction of the third flange 12, thus tending to move the fourth flange 13 closer to the third flange 12.

[0102] Such a continuously variable transmission called mechanical according to this arrangement has the following advantages, in particular in comparison with a hy draulic: the limitation of the manufacturing cost of the screw driver 100, the simplicity of maintenance of the screw driver 100, the cleanliness of the screw driver 100, as well as the lightness of the screw driver 100. In addition, thanks to this architectural arrangement, the size of the screw driver 100 is reduced, which facilitates its use by an operator.

[0103] The first return member 14a and the second return member 14b may be a compression spring or any type of return member controlled via an actuator.

[0104] The function of the first return member 14a is shown diagrammatically in [Fig.5], the first return member 14a being able to be in reality housed in a dome 41 of the drive pulley 8.

[0105] The belt 15 may be made of a flexible material such as, for example, rubber or synthetic polymers. The role of the belt 15 is to transmit the movement of the driving pulley 8 to the driven pulley 11 by connecting them together when the drive shaft 2 rotates along its axis.

[0106] The continuously variable transmission is advantageously configured to allow, in particular in the operational configuration, a variation in the transmission ratio as a function of a variation in the engine speed of the drive group 1 and / or of a resistive torque of the driven shaft 5. Indeed, in the operational configuration of the screw driver 100, both during the screwing and unscrewing of the fastener 101, a hard point, linked to the resistive torque caused by the cooperation of the end piece 35 with the fastener 101 and propagating from the end piece 35 to the driven shaft 5, may appear. To overcome this resistive torque (and therefore pass the hard point), it is conventional to increase the engine torque of the drive group 1.However, a large increase in torque can lead to a drop in the engine speed of drive group 1, hence the need to maintain the power of drive group 1 (proportional to the engine torque and rotational speed) at a substantially constant value: this is what the continuously variable transmission allows.

[0107] The continuously variable transmission described above is not limiting in the sense that its description applies to a particular and preferred embodiment of the screw driver 100. Some continuously variable transmissions may be smaller and more compact, and are simpler in their operation. These simplified systems are simply controlled by the variation in engine speed (the engine 18 will slow down in the event of a torque peak). Moreover, some continuously variable transmissions do not allow the belt 15 to be free when the engine speed is low; these systems must be coupled with a centrifugal clutch.

[0108] A particular example of the embodiment of the transmission mechanism 7 has been described above using a continuously variable belt transmission and in particular controlled internally via first and second return members of the type spring. Alternatively, the transmission mechanism 7 can be chosen from: • a continuously variable belt transmission with external control (using a pneumatic, electric or hydraulic actuator for example); • a hydraulic continuously variable transmission (the coupling of the drive shaft 2 to the driven shaft 5 is then hydraulic) for example with a viscous coupling or a torque converter; • a mechanical continuously variable transmission (the coupling of the drive shaft 2 to the driven shaft 5 is then mechanical) for example toroidal, conical, or by epicyclic gear train.

[0109] In the exemplary embodiment of the screw driver 100, shown in Figures 1 to 5, the inverter 29 makes it possible to choose the direction of rotation of the end piece 35 of the screw driver head 3 downstream of the continuously variable transmission according to the direction of propagation of the rotational movement between the drive group 1 and the screw driver head 3. This specific positioning makes it possible to avoid jolts linked to the reversal of the direction of rotation and thus to make the system more fluid.

[0110] Advantageously, by combining the continuously variable transmission with a two-speed gearbox, this makes it possible to increase the diversity of choice of usable engines. It will then be possible to reduce the power of the engine 18 of the drive group 1 in order to lighten the screw driver 100; this also makes it possible to reduce the costs of the engine and the energy consumption (petrol, electricity or other).

[0111] When the motor 18 is an electric or hydraulic motor, the latter can directly reverse its direction of rotation. Therefore, the inverter 29 mentioned above is no longer necessary and is therefore not present within the screw driver 100 downstream of the motor 18 along the path of propagation of the movement. In this case, the continuously variable transmission will be adapted to operate regardless of the direction of rotation of the drive shaft 2.

[0112] According to other embodiments, the transmission mechanism 7 may also be, for example, a gear train, a chain, or any type of transmission making it possible to propagate the rotational movement of the drive shaft 2 within the transmission and in the direction of the end piece 35.

[0113] The embodiments described above may, where appropriate, be combined.

[0114] The present invention finds an industrial application in the field of railways, in particular by allowing an operator to accelerate the screwing or unscrewing of fastener(s) 101.

Claims

Claims

1. A screw driver (100) comprising: • a tip (35) capable of being rotated in order to screw or unscrew a fastener (101) of a railway track (102); • a drive group (1) comprising a drive shaft (2) arranged at the output of the drive group (1); • a transmission connecting the drive group (1) to the tip (35) and configured to propagate, in an operational configuration of the screw driver (100), a rotational movement of the drive shaft (2) in order to drive the tip (35) in rotation; the transmission comprising successively from the drive group (1): • a transmission mechanism (7); • a driven shaft (5) coupled to the drive shaft (2) via the transmission mechanism (7);the drive shaft (2) being offset relative to the driven shaft (5), the drive shaft (2) comprising a portion (2a) which extends in a first direction in a first sense (si) at the output of the drive group (1) towards the transmission mechanism (7), the driven shaft (5) comprising a portion (5a) which extends in a second direction in a second sense (s2) oriented towards the end piece (35) along a propagation path of the rotational movement of the drive shaft (2) within the transmission, the first sense (si) and the second sense (s2) being opposite.;

2. A screw driver (100) according to claim 1, wherein the drive group (1) is arranged vertically above at least a portion of the driven shaft (5).

3. A screw driver (100) according to any one of claims 1 to 2, wherein the drive group (1), the transmission mechanism (7) and the driven shaft (5) are arranged according to an architecture in

4. A screw driver (100) according to any one of claims 1 to 3, in which the axis of the drive shaft (2) and the axis of the driven shaft (5) are substantially parallel to each other and in which, when the screw driver (100) is in the operational configuration: • the axis of the drive shaft (2) and the axis of the driven shaft (5) have between them a level offset in a vertical direction (Dv) of between 10 mm and 400 mm, and preferably between 10 mm and 220 mm, and an offset in a lateral direction (Dl) strictly greater than 0 mm and less than or equal to 400 mm, and preferably less than or equal to 220 mm; or • the axis of the drive shaft (2) and the axis of the driven shaft (5) have between them a level offset in a vertical direction (Dv) of between 10 mm and 400 mm, and one of the drive shaft (2) and the driven shaft (5) is arranged vertically above the other of the drive shaft (2) and the driven shaft (5).

5. A screw driver (100) according to any one of claims 1 to 4, in which the drive group (1) comprises a casing (43) through which the drive shaft (2) passes and in which: • the casing (43) and the transmission mechanism (7) are in contact; or • in a direction substantially parallel to the axis of the drive shaft (2), the casing (43) and the transmission mechanism (7) are separated by a distance strictly greater than 0 mm and less than or equal to 1000 mm, and preferably less than or equal to 500 mm.

6. A screw driver (100) according to any one of claims 1 to 5, wherein the transmission comprises a reduction mechanism (30, 40) arranged between the driven shaft (5) and the end piece (35).

7. A screw driver (100) according to claim 6, wherein, in the operational configuration of the screw driver (100), the drive group (1) is positioned at a height level higher than the height level of the reduction mechanism (30, 40) relative to the ground (S).

8. A screw driver (100) according to any one of claims 6 to 7, wherein the reduction mechanism (30, 40) is a single-speed gearbox (40).

9. A screw driver (100) according to any one of claims 6 to 7, wherein the reduction mechanism (30, 40) is a gearbox (30) having at least two speeds having different transmission ratios.

10. A screw driver (100) according to any one of claims 1 to 9, wherein the screw driver (100) comprises a casing (38) and wherein the transmission comprises: • an angle gear (33) arranged in the casing (38); • a shaft (37) connecting the angle gear (33) to the end piece (35) arranged outside the casing (38).

11. A screw driver (100) according to claim 10 and any one of claims 6 to 9, wherein the reduction mechanism (30, 40) is: • located in the casing (38); or • fixed to the casing (38); or • located at a distance from the casing (38) so that at least one transmission shaft connects the reduction mechanism (30, 40) to the angle transmission (33).

12. A screw driver (100) according to any one of claims 1 to 11, wherein the transmission mechanism (7) comprises a continuously variable transmission.

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