WO2008107013A1

WO2008107013A1 - Screwing/unscrewing device with parallelepiped selector

Info

Publication number: WO2008107013A1
Application number: PCT/EP2007/051291
Authority: WO
Inventors: Emmanuel Thery
Original assignee: Georges Renault
Priority date: 2007-02-09
Filing date: 2007-02-09
Publication date: 2008-09-12
Also published as: ATE471795T1; EP2125297B1; EP2125297A1; DE602007007368D1

Abstract

The invention relates to a device for screwing/unscrewing a connection member, that comprises : a casing (30) for receiving a pneumatic engine (32) comprising a cylinder inside which a rotor is capable of rotation for rotatingly driving an end member; a handle (31) connected to said casing (30) and through which extends a means (33) for supplying said engine (32) with a pressurised fluid, and a means (34) for opening/closing said supply means; a means for selecting the rotation direction of said rotor, including a mobile member (36) movable between two positions each corresponding to a different rotation direction of said rotor. According to the invention, the mobile member (36) comprises at least two opposed planar faces (365, 366) that can be respectively pressed against a first bearing surface (322) formed on said cylinder and a second bearing surface (373) formed on a piston (37) movable along said supply means (33), said piston (37) being capable of pressing said mobile member (36) onto the first bearing surface (322).

Description

Screwdriver / unscrewing tool with parallelepipedic selector

1. Field of the invention

The field of the invention is that of the design and production of tools, for example portable, allowing the screwing and unscrewing of fasteners.

More specifically, the invention relates to pneumatic screwing / unscrewing tools, and in particular the sealing of the supply of compressed engine fluid that they implement.

2. Prior Art Pneumatic screwing / unscrewing tools, for example impact wrenches, generally comprise, as illustrated in FIG. 1, a casing 100 to which a handle 10 is secured. A pneumatic motor is housed inside. of the casing 100.

As shown in FIGS. 1 to 5, such a pneumatic motor conventionally comprises:

a body 1;

a front cheek 2 and a rear cheek 3 between which the body 1 is mounted;

- A rotor 4 carrying pallets 41 and rotatably mounted on the front and rear cheeks 2, 3 respectively through bearings 21 and 31.

The body has at its base an extension l i within which is mounted a cylindrical selector 5 can be moved axially and / or actuated in rotation by a lever.

The extension 11 has an air intake orifice 111 which communicates with an air inlet duct 101 formed in the handle 10 of the tool (an exhaust duct 102 also being provided in the handle 10). .

Actuation of the cylindrical selector 5 makes it possible to reverse the direction of rotation of the rotor and / or to regulate the speed of the latter.

The operation is as follows. When the drawer is in the position shown in Figure 1, the air admitted into the conduit 101 passes through the orifice 111, then into the orifice 12 (the orifice 13 being obstructed by the drawer) which communicates with the chamber 121 (extending from the side of the rear cheek 3) appearing in the sectional view of FIG. 3. When the engine is started, part of the air goes to the rear cheek 3 and the front cheek 2, which have recesses 32 for conveying air to the base of the pallets 41 so as to slide them radially outwardly of the rotor and to bring them into engagement with the air injected into the chamber 121. air exhaust (once the engine is started, that is to say after a rotation of the rotor of about 90 °) is effected by the chamber 131 (Figure 4) and the orifice 13 (and then by the duct 102 of the handle), a complementary exhaust through the orifices 14 formed in the walls of the body 1, so as to to compensate the compression of the air between the pallets when they move on the portion of the body which tends to decrease the volume between two pallets.

The reversal of the direction of rotation of the rotor is obtained by axially moving the cylindrical selector 5 so as to place the orifice 13 in communication with the inlet 111, the air then circulating first in the chamber 131 and then escaping through the chamber 121 (in addition to the complementary exhaust through the orifices 14).

Furthermore, with reference to FIG. 2, the angular position of the cylindrical selector 5 makes it possible to modify the air passage section in the orifice 12 (or in the orifice 13 as a function of the axial position of the slide) and, therefore, to vary the speed of rotation of the rotor.

In order to limit the pressure losses that may cause the tool to malfunction, the seal between the conduit 101 of the handle 10 and the extension 11 must be perfectly made. The seal between the cylindrical selector 5 and the casing 100 must also be ensured. In practice, the seal between these elements proves to be particularly difficult to ensure. In particular, the seal between the cylindrical selector 5 and the housing 100 is difficult to achieve because the selector has an annular section and moves in translation inside the casing 100. A technique of the prior art consists in interposing a seal 15 between the upper end of the duct 101 and a flat surface 1111 formed on a lower part of the extension 11 so as to seal between the duct 10 and the extension 11.

In addition, according to the prior art, the seal between the cylindrical selector 5 and the housing 100 is formed by means of an O-ring 16, and seals 17, 18 located on either side of the orifices of the cylindrical selector 5.

3. Disadvantages of prior art

However, it can be seen that this technique does not make it possible to ensure perfect sealing because leaks generally appear between the duct 101 and the extension 11, as well as between the cylindrical selector 5 and the casing 100.

The operation of such pneumatic screwing / unscrewing tools is therefore often disrupted by the appearance of leaks that affect the performance of the tool, especially in terms of available torque and output speed. Such a weakening of the capacities of a screwing / unscrewing tool can notably lead to a lowering of the productivity for example when it is used by an operator working along an assembly line.

Such leaks can also cause the appearance of whistles that can be noise nuisance for operators. 4. Objectives of the invention

The invention particularly aims to overcome these disadvantages of the prior art.

More specifically, an object of the invention is to propose a technique of inversion of the direction of rotation of the motor of a pneumatic tool of screwing / unscrewing which makes it possible to ensure perfect sealing of the engine's compressed fluid supply.

Another object of the invention is to provide such a technique which makes it possible to guarantee the performance of such a pneumatic screwing / unscrewing tool.

Another object of the invention is to provide such a technique that allows to maintain a high productivity rate.

The invention also aims to provide such a screwing / unscrewing tool which has good quality including ergonomically, while maintaining a perfect seal.

The invention also aims to provide such a technique that is simple, reliable and inexpensive to implement.

5. Presentation of the invention

These objectives, as well as others which will appear later, are achieved by means of a tool for screwing / unscrewing a fixing element, comprising:

- A casing housing a pneumatic motor comprising a cylinder within which a rotor is rotatable to rotate a terminal member;

a handle secured to said casing and traversed by means for supplying said motor with compressed fluid;

means for opening / closing said supply means;

means for selecting the direction of rotation of said rotor comprising a member movable between two positions each corresponding to a different direction of rotation of said rotor. According to the invention, said movable element has at least two opposite planar faces capable of being compressed respectively against a first bearing surface formed on said cylinder and against a second bearing surface formed on a movable piston along said means of rotation. supply, said piston being capable of pressing said movable element on said first bearing surface. Thus, the invention is based on a completely new and inventive approach for sealing the compressed air supply of an engine implemented in a pneumatic screwing / unscrewing tool.

This technique according to the invention consists in feeding the motor by means of a selector of particular shape so that it can be compressed between a piston and the cylinder of the engine under the effect of the pressure of the compressed air supplying the engine. engine. Thus, since the compressed air feeds the engine, the particular shapes and in particular the flat surfaces of the piston, the selector and the cylinder make it possible to ensure an automatic seal. We will talk about self sealing.

Sealing is therefore caused by the combination of the flat surfaces of the piston, the selector and the cylinder and by the pressure of the compressed air which allows to press these elements against each other, without the need for implement gaskets. This technique according to the invention thus makes it possible to obtain easily and effectively the tightness of the compressed air supply of the engine, that is to say of a zone of the screwing / unscrewing tool that the man the trade has difficulty sealing.

The implementation of the technique according to the invention thus prevents the appearance of leakage and loss of charge in the motor supply circuit. This technique therefore ensures the proper operation and performance of the screwing / unscrewing tool, particularly in terms of torque and speed available at the exit of the screwing / unscrewing tool.

According to an advantageous characteristic of the invention, said housing has guide means in translation of said movable element.

It is thus possible to easily move the movable element inside the housing so that it takes several positions. The movable element may preferably take two positions, each of its positions corresponding to opposite directions of rotation of the motor. Preferably, said movable member is slidably mounted along said first bearing surface and said second bearing surface.

It is thus possible to move the movable element from one position to the other, advantageously when the engine is not powered, which ensures excellent sealing when reversing the direction of rotation of the engine. This further allows a user to be able to reverse the direction of rotation of the engine without cutting off the supply of compressed air, and thus maintain a high productivity rate.

According to a preferred aspect of the invention, said first bearing surface is traversed by two holes for passing said fluid distributed along an axis oblique to the axis of rotation of said rotor, and said movable element is traversed by two lights. intake and two exhaust ports, said lights being arranged so that in each of said positions of said movable member, one of said intake ports and one of said exhaust ports respectively cooperate with one of said holes.

The fluid passage holes alternately provide an intake function and an exhaust function, depending on the direction of rotation of the engine. Thus, when the engine rotates clockwise, one hole allows the admission of the fluid while the other allows its escape. Conversely, when the motor rotates counter-clockwise, the function of the holes is reversed, the hole serving as intake when the engine rotates in a clockwise direction then allowing the exhaust, and the hole serving as an exhaust allowing admission .

In addition, the lights passing through the movable element are arranged such that in each of the positions of the movable element, an intake port and an exhaust port cooperate respectively with one of the holes of the first support surface. , while the other lights are closed. A change of position of the movable element thus makes it possible to reverse the function of the holes of the first bearing surface by making the previously closed holes cooperate with holes, this by closing off the lights previously cooperating with the holes. Preferably, said movable element is of substantially parallelepipedal shape.

The movable member thus has planar surfaces which, when pressed against the first and second bearing surfaces, which are flat, provide an effective seal.

According to an advantageous characteristic of the invention, said intake ports extend from an upper face and to a lower face of said movable member.

This makes it possible to easily and effectively ensure the admission of fluid under pressure into the engine without loss of load.

According to another characteristic of the invention, said exhaust ports each extend from the upper face to opposite side faces of said movable member.

This makes it possible to ensure simply and effectively the escape of the fluid from the engine and for example to direct it to elements allowing its evacuation outside the screwing / unscrewing tool.

According to a preferred aspect of the invention, said piston is traversed by two intake channels arranged so that in each of said positions of said movable element, one of said intake channels cooperates with one of said intake ports of said movable member, another intake channel being closed by said movable member.

The admission of fluid under pressure by each of these channels corresponds to a different direction of rotation of the engine.

Preferably, said piston has a peripheral groove in which is housed a seal.

This ensures a perfect seal between the piston and the feed means integrated in the handle, and thus prevent the occurrence of pressure loss, without implementing a complex means.

According to another advantageous characteristic of the invention, said opening / closing means comprise a movable valve between a position of closing said supply means and a closing position of said supply means.

Preferably, remote control means make it possible to modify the position of said valve. A user can then easily open or close the valve so as to start or stop the engine.

According to another advantageous aspect of the invention, said second bearing surface forms an angle with the axis of said piston substantially equal to the angle formed by the axis of said handle and the axis of said rotor. It can thus be provided that the handle is inclined relative to a vertical axis perpendicular to the axis of the motor without this disturbing the operation of the screwing / unscrewing tool according to the invention. This also makes it possible to give the screwing / unscrewing tool according to the invention ergonomic qualities and to improve its comfort of use. 6. List of figures

Other characteristics and advantages of the invention will emerge more clearly on reading the following description of a preferred embodiment of the invention, given by way of illustrative and nonlimiting example, and the appended drawings, among which: - Figure 1 illustrates the compressed air supply zone of a screwing / unscrewing tool according to the prior art; Figure 2 is a sectional view of the screwing / unscrewing tool illustrated in Figure 1; Figures 3 to 5 illustrate different views of the pneumatic motor shown in Figures 1 and 2; Figure 6 is a partial perspective view of a screwdriver according to the invention; Figure 7 is a partial exploded view of the piston, the selector and the cylinder implemented in a screwing / unscrewing tool according to the invention; Figure 8 is a perspective view of a selector according to the invention; Figures 9 and 10 illustrate two positions of the selector according to the invention relative to the piston.

7. Description of an embodiment of the invention 7.1. Recall of the principle of invention

The general principle of the invention is based on the implementation of a selector having at least two plane surfaces capable of being compressed between a piston and the cylinder of a pneumatic motor implemented in a screwing / unscrewing tool, under the effect of the pressure of the compressed air supplying the engine, so as to ensure a perfect self-sealing of the compressed air supply of the engine and to prevent the appearance of leakage.

7.2. Architecture example of a screwing / unscrewing tool according to the invention

FIGS. 6 to 10 show an embodiment of a pneumatic screwing / unscrewing tool according to the invention, which may for example be an impact wrench.

Such a screwing / unscrewing tool comprises a casing 30 to which is secured in a handle 31 (shown in dashed lines). A motor 32, housed inside the housing 30, is able to rotate a terminal member (not shown) to ensure the screwing or unscrewing of a fastener, for example a screw, a nut or any other fastener that can be screwed on / off.

Compressed air supply means are housed inside the handle 31. These supply means here take the form of a duct 33 which extends substantially along the handle 31. The duct 33 can be open or closed by means of a valve 34. For this purpose, the valve 34 is movable between a position in which it closes the conduit 33, and a position in which it releases the conduit 33 so as to prevent or allow the passage of compressed air in the motor 32. Means for controlling the position of the valve 34, here taking the form of a trigger 35 (shown in dashed lines), can be manipulated by a operator to act on the valve 34 and to open or close the conduit 33.

The lower part of this duct 33 has connecting means (not shown) to a source of production of compressed air such as a compressor. The connection to the compressor can for example be realized by means of a flexible hose.

A selector 36 is slidably mounted in the housing 30 so as to be translated along the longitudinal axis of the screwing / unscrewing tool. In another embodiment, the selector 36 may be movable in translation along an axis transverse to the screwing / unscrewing tool. This selector 36 is also slightly mobile in translation along a vertical axis substantially perpendicular to the axis of rotation of the motor 32. This degree of freedom may allow the selector 36 to be pressed against the bearing surface 322, as will be explained in more detail later. This selector 36 has a substantially parallelepiped shape defined by a rear face 361, a front face 362, a left face 363, a right face 364, an upper face 365 and a lower face 366.

The selector 36 is interposed between a piston 37 and an extension 321 of the motor casing 32 forming a bearing surface 322. The selector 36 is mounted so as to slide between the upper face 373 of the piston 37 and the bearing surface 322.

As will be explained in more detail later, the assembly formed by the selector 36, the piston 37 and the bearing surface 322 allows:

reversing the direction of rotation of the motor 32 according to the position that the selector 36 occupies;

- To ensure a self-sealing function of the compressed air supply circuit of the motor 32.

A pusher 38 is connected to the selector 36 by means of a connection rod

39. The selector 36 has a groove 367 inside which can be engaged one end of the connecting rod 39 which has a shape complementary to that of the groove 367 so that the rod 39 and the selector 36 are secured to one another.

A compression spring 40 acts on the selector 36 so as to maintain it in a rest position in which the motor rotates in a direction allowing the screwing of a fastener. A stud 377, formed on the front face 362 of the selector 36, makes it possible to secure the spring 40 to the selector 36. For this purpose, the stud 377 is inserted inside the spring 40.

FIG. 7 illustrates a partial exploded view of the motor 32, the selector 36 and the piston 37. As it appears more clearly, the cylinder of the motor 32 has an extension 321 in its lower part, which forms a bearing surface 322. The bearing surface 322 is substantially parallel to the axis of the motor 32 and is substantially perpendicular to the axis of the handle 31.

The extension 321 is traversed by two holes 323, 324 which allow, as will be explained more clearly later, alternately ensure the admission or the exhaust of the motor 32 according to the direction in which it rotates. These two holes 323, 324 are aligned along a substantially horizontal axis and oblique relative to the axis of rotation of the rotor, as shown in Figure 7. The selector 36 also has two intake ports 368, 369 which extend from its upper face 365 to its lower face 36, as shown in Figure 8. The inlet ports 368, 369 are aligned along a transverse axis of the selector 36 passing substantially through its middle . The selector 36 further has two exhaust ports 370, 371. The light 370 passes through the selector 36 from its upper face 365 to its left face 363, while the light 371 passes through the selector 36 from its upper face 365 to 364. The light 370 is formed in the left front part of the selector 36, while the light 371 is formed in the right rear part of the selector 36. Furthermore, the piston 37 has a substantially quadrangular contour whose lateral edges are joined by fillets. The lower faces 372 and upper 373 of the piston 37 are plane and form an angle which is substantially equal to the angle formed between the axis of the handle 31 and the axis of rotation of the motor 32. The implementation of a such angle between the upper 373 and lower 372 faces allows the piston 37 to bear against the lower face 366 of the selector 36 as it moves upwards along the axis of the handle 32.

Two inlet channels 374, 375 pass through the piston 37 and join its bottom faces 372 and 373. These two inlet channels 374, 375 are arranged at two diametrically opposite angles of the piston 37. This piston 37 is mounted to be movable in translation at the same time. Inside the handle 31 along the axis of the handle 31. The piston 37 has a groove 376 which extends along its circumference. This groove is intended to house an O-ring (not shown) so as to seal between the piston 37 and the handle 32. 7.3. Operating modes

Figures 9 and 10 illustrate two positions that may occupy the selector 36 according to an operator wishes to proceed to the screwing or unscrewing of a fastener. Each position of the selector corresponds to a different direction of rotation of the motor. 7.3.1. Operation clockwise

When the selector 36 is held against the effect of the compression spring 40, in the position illustrated in FIG.

the inlet channel 375, the hole 323 and the intake port 368 cooperate with each other; - The hole 324 of the motor 32 cooperates with the exhaust port 371 of the selector 36;

the admission channel 374 is closed by the selector 36;

the intake opening 369 is closed by the piston 37. When an operator actuates the trigger 35 so that the valve 34 releases the compressed air passage towards the motor 32, the compressed air enters the motor 32 through the intake channel 375, the intake port 368 and the hole 323. The motor 32 is then rotated clockwise. The air escapes from the motor 32 through the hole 324 and the exhaust port 371. 7.3.2. Counter clockwise operation

When an operator wishes to reverse the direction of rotation of the motor 32, he can actuate the pusher 38 so that the selector 36 is translated under the effect of the compression spring 40 towards the rear of the screwing tool until selector 36 reaches the position illustrated in FIG. 10. In this position: the inlet channel 374, the hole 324 and the intake port 369 cooperate with each other;

the hole 323 of the motor 32 cooperates with the exhaust port 370 of the selector 36;

the admission channel 375 is closed by the selector 36; - The intake port 368 is closed by the piston 37.

When an operator actuates the trigger 35 so that the valve 34 releases the passage of compressed air towards the motor 32, the compressed air enters the motor 32 through the intake channel 374, the intake port 369 and hole 324. The motor is then rotated counterclockwise. The air escapes from the motor 32 through the hole 323 and the exhaust port 370.

7.4. Auto sealing

The particular geometry of the piston 37, the selector 36 and the bearing surface 322, associated with the mobility of the piston 37 and the selector 36 along a substantially vertical axis and perpendicular to the axis of the motor 32 ensures self-sealing of the motor 32 compressed air supply.

Indeed, as soon as the valve 34 is open, the piston 37 moves upwards along the axis of the handle 32, under the effect of the pressure of the compressed air. It then comes to bear on the selector 36 and pushes it so it moves very slightly along a vertical axis to come against the bearing surface 322 of the motor cylinder 32 so as to seal.

In the present embodiment, the pressure of the compressed air is of the order of 6.3 bars. Other pressure values may be employed in other embodiments.

In such a compression position:

the upper face 373 of the piston is pressed against the lower face 366 of the selector 36, and

the upper face 365 of the selector 36 is compressed against the bearing surface 322 formed on the extension 321 of the motor 32.

The different flat surfaces that the piston 37, the selector 36 and the extension 321 present and which bear against each other and are compressed against each other under the effect of the pressure of the compressed air make it possible to ensure perfect sealing. and automatic between these different elements without leaks appear as soon as the engine is supplied with compressed air.

The particular geometry of the piston, the selector and the extension thus makes it possible to route the compressed air inside the motor 32 without leakage and therefore without loss of load. The technique according to the invention thus makes it possible to guarantee the proper operation of the engine and to maintain the performance of the screwing / unscrewing tool, in particular with regard to the torque and speed available at the output of the tool.

Claims

1. Tool for screwing / unscrewing a fastener, comprising:

- a housing (30) housing a pneumatic motor (32) comprising a cylinder within which a rotor is rotatable to rotate a terminal member;

- A handle (31) secured to said housing (30), and traversed by supply means (33) of said motor (31) compressed fluid;

- Opening / closing means (34) of said supply means (33); - means for selecting the direction of rotation of said rotor comprising a movable element (36) between two positions each corresponding to a different direction of rotation of said rotor, characterized in that said movable element (36) has at least two opposite planar faces ( 365, 366) respectively compressible against a first bearing surface (322) formed on said cylinder and against a second bearing surface (373) formed on a piston (37) movable along said supply means (33), said piston (37) being capable of pressing said movable member (36) on said first bearing surface (322).

2. screwing / unscrewing tool according to claim 1, characterized in that said housing (30) has means for guiding in translation of said movable member (36).

3. Screwing / unscrewing tool according to any one of claims 1 and

2, characterized in that said movable member (36) is slidably mounted along said first bearing surface (322) and said second bearing surface (373).

4. Screwing / unscrewing tool according to any one of claims 1 to

3, characterized in that said first bearing surface (322) is traversed by two holes (323, 324) for passing said fluid distributed along an axis oblique to the axis of rotation of said rotor, and in that said movable member (36) is traversed by two intake ports (368, 369) and two exhaust ports (370, 371), said slots (368, 369, 370, 371) being arranged such that in each of said positions of said movable member (36), one of said intake ports (368, 369) and one of said plurality of apertures exhaust (370, 371) respectively cooperate with one of said holes (323, 324).

5. screwing / unscrewing tool according to any one of claims 1 to 4, characterized in that said movable member (36) is substantially parallelepiped shape.

6. Screwing / unscrewing tool according to claims 4 and 5, characterized in that said intake ports (368, 369) extend from an upper face (365) and to a lower face (366) of said element mobile (36).

7. Screwing / unscrewing tool according to claims 4 and 5, characterized in that said exhaust ports (370, 371) each extend from the upper face (365) to opposite side faces (363, 364). ) of said movable member (36).

8. Screwing / unscrewing tool according to any one of claims 1 to

7, characterized in that said piston (37) is traversed by two inlet channels (374, 375) arranged such that in each of said positions of said movable member (36), one of said inlet channels (374, 375) cooperating with one of said intake ports (368, 369) of said movable member (36), the other intake channel (374, 375) being closed by said movable member (36).

Unscrewing screwing tool according to one of claims 1 to

8, characterized in that said piston (37) has a groove (376) peripheral in which is housed a seal.

10. Screwing / unscrewing tool according to any one of claims 1 to 9, characterized in that said opening / closing means comprise a valve (34) movable between a closed position of said supply means (33) and a closed position of said supply means (33).

11. Screwing / unscrewing tool according to claim 10, characterized in that it comprises remote control means (35) of the position of said valve (34).

12. screwing / unscrewing tool according to any one of claims 1 to 11, characterized in that said second bearing surface (373) forms an angle with the axis of said piston (37) substantially equal to the angle formed by the axis of said handle (31) and the axis of said rotor.