EP2716414A1 - Device for screwing with no reaction in the handle - Google Patents

Abstract

The device has a handle housing (10) including a handle (100), and receiving an electric motor (12). A gear reduction housing (11) receives a gear reduction unit (16) whose sun gear cooperates with a drive shaft (15) of the motor. The gear reduction unit includes a planet carrier cooperating with a rotating end element (17) that is configured for cooperating with an element to be screwed. The gear reduction housing is linked to the handle housing by a rotating link, which is configured such that a negligible reaction force is transmitted to the handle housing during a screwing operation.

Description

1. Field of the invention

The field of the invention is that of the design and manufacture of screwdrivers.

More specifically, the invention relates to a screwing tool whose housing comprises a portion having a gripping handle and a portion housing a reduction, these two portions being connected by a rotary junction.

2. Prior Art

The screwdrivers are currently used, mainly in industry, to allow operators to proceed to the screwing of connecting elements of the parts of an assembly.

The screwdrivers conventionally comprise a housing having a handle and housing motor means whose output is connected to the input of a reduction, the output of this reduction being itself connected to a terminal rotary member intended to cooperate with a screw element.

When screwing a screw element, the reaction torque of the tool is much higher than that which an operator is able to support. The screwdrivers therefore often include a reaction bar secured to the housing. This reaction bar is intended to be placed in abutment against a fixed element to absorb, during a screwing operation, the reaction torque of the tool.

In extreme and rare cases, the reaction bar may be ripe from the fulcrum against which it is blocked. In such a situation, if the operator continues to pull the trigger, this can cause injury.

To overcome this drawback, it has been observed the development of screwdrivers comprising on the one hand a gripper housing having a handle and housing the drive means, and on the other hand a reduction housing housing a reduction. The reduction casing is secured to the gripping casing by a rotary connection. In other words, the gripper and reduction casings are rotatable relative to each other.

Due to such an assembly, in the event of shifting, disengagement or rupture of the reaction bar during a screwing operation, the reduction casing and the gripping caster rotate relative to one another. other so that the reaction torque proportional to the output torque delivered by the screwdriver is not transmitted by the handle to the hand of the operator.

Moreover, such an assembly allows the operator to adjust the angular position of the handle relative to the reduction housing to find the working position that seems most comfortable for him to perform the screwing operation he has the charge.

Screwdrivers of this type therefore have the advantages of offering a high level of safety and good ergonomics. They can still be improved.

3. Disadvantages of prior art

Although the reaction transmitted by the handle to the hand of the operator during a screwing operation without reaction bar is relatively small, it is not completely negligible.

Indeed, the operator must in any case support the reaction torque generated by the internal transmission of the screwdriver at the rotational junction between the gripper housing and the reduction housing. This torque is in fact the torque of the motor means, that is to say the product of the engine torque by one or more reduction stages. Its value is generally around 10 Nm. Such levels of reaction torque are sufficient to constitute a source of fatigue for the operator.

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 improve, in at least one embodiment, the safety of use and the ergonomics of the screwdrivers with rotating gripping casing.

In particular, an object of the invention is to provide, in at least one embodiment, such a screwdriver which generates no reaction in the hand of the operator during a screwing operation, or at least which generates a reaction whose value is low enough not to cause him injury and / or fatigue.

Another object of the invention is to implement such a screwdriver which allows, in at least one embodiment, to control the tightening torque to which a fastener is screwed by means of the screwdriver.

The invention also aims to provide such a screwdriver which is, in at least one embodiment, simple design and / or reliable and / or cheap.

5. Presentation of the invention

These objectives, as well as others which will appear thereafter, are achieved by means of a screwing device comprising a gripping casing and a reduction casing, said gripping casing comprising a handle and housing motor means, said reduction casing housing a gear reduction whose input cooperates with the output of said motor means, said reduction comprising a single output cooperating with a rotary end member intended to cooperate with a screw element, said reduction casing being connected to said casing; gripping means by rotary connection means.

According to the invention, said rotary connection means are configured in such a way that a negligible reaction force is transmitted during a screwing operation to said gripping case.

Thus, the invention is based on a completely original approach which consists in linking the reduction casing and the gripping casing of a screwdriver by rotary connection means designed in such a way that only a negligible reaction force is transmitted during from a screwing operation to the gripping case. By negligible reaction effort is meant a force which is sufficiently small not to risk causing injury or discomfort to the operator. In practice, the value of such a torque is generally less than 5 Nm

When performing a screwing operation no reaction force is transmitted to the hand of the operator by the handle.

The implementation of the technique according to the invention thus makes it possible to improve the safety of use of a screwdriver and to improve its ergonomic qualities.

Preferably, said rotary connection means comprise means for transmitting to said gripping casing a reaction torque of substantially identical intensity and direction opposite to the reaction torque transmitted by said reduction to said motor means.

When these reaction torques have identical values, no reaction force is transmitted by the handle to the hand of the operator. When these couples have different values, a reaction force is transmitted by the handle to the operator. The transmission means will therefore be determined in such a way that the reaction forces transmitted to the operator are at most negligible, that is to say that they are sufficiently weak not to cause him injury or simply discomfort. In practice, the value of one of these reaction couples will be equal to that of the other at approximately 20%.

According to a particular embodiment, said reduction comprises a first epicyclic gear train having a first solar solid with said motor means, first satellites mounted on a first planet carrier, and a ring mounted free to rotate in said reduction case, said means for transmission comprising a second epicyclic gear train having a second sun rotatable with respect to said first sun and fixed to said gripping casing, second satellites mounted on a second planet carrier fixed to said reduction casing, and said ring gear.

This implementation makes it possible to ensure efficiently and simply that only a zero or negligible reaction force is transmitted to the handle during a screwing operation.

In this case, the numbers of teeth respectively of the solar, satellites and the ring gear of the first epicyclic gear are preferably identical to those of the solar, satellites and the ring of the second epicyclic gear

Considering that the input of the first epicyclic gear is the solar and that its output is the planet carrier, and that the input of the second epicyclic gear is the solar and its output is the planet carrier, said first and second trains have therefore identical reduction ratios.

No reaction effort is then transmitted to the handle.

A device according to the invention preferably comprises means for measuring information representative of the tightening torque of said element to be screwed, said measuring means comprising at least one torque sensor integrated in said transmission means.

It is thus possible to measure in the transmission a tightening reaction torque whose value is proportional to that of the torque at which the element to be screwed is tightened by means of the screwdriver.

Said torque sensor is preferably mounted on said second solar.

In a variant, the first satellite gate is directly linked to the rotary terminal member.

The transmission and measurement means are thus very close to the output of the transmission. The accuracy of the measurement of the tightening torque is then improved.

Said sensor advantageously incorporates strain gages.

These strain gauges are connected to an electronic card housed in the gripping case. This is made possible by the fact that the solar supporting the sensor is fixed on the gripper housing which allows the passage of power supply son of strain gauges and recovery of the signal.

In a particular variant, a device according to the invention comprises a gearbox interposed between said motor means and said reduction.

It is thus possible to implement screwing phases at different speeds, such as, for example, a rapid primer phase and a screwing slower.

In this case, a device according to the invention may comprise means for shifting by reversing the direction of rotation of said motor means.

The passage from one speed to another can then be obtained simply by reversing the direction of rotation of the motor.

In a particular variant, the axis of said gearbox and said reduction extends parallel and offset from the axis of said motor means.

It is thus possible to reduce the length of the screwdriver and to produce a tool that is more compact and more manoeuvrable.

A device according to the invention may comprise a reaction bar integral with said reduction casing.

An operator will thus be able to lock the screwdriver in rotation to ensure high torque screwing.

6. List of figures

• la figure 1 illustre une vue en coupe d'une visseuse selon l'invention selon un plan médian passant par son axe longitudinal ;
• la figure 2 illustre une vue de détail du carter de réduction et de sa jonction avec le carter de préhension de la visseuse illustrée à la figure 1 ;
• la figure 3 illustre une vue en perspective de la réduction et de sa jonction avec le carter de préhension de la visseuse illustrée aux figures 1 et 2.

Other characteristics and advantages of the invention will appear more clearly on reading the following description of a preferred embodiment, given as a simple illustrative and nonlimiting example, and the appended drawings, among which:

• the figure 1 illustrates a sectional view of a screwdriver according to the invention according to a median plane passing through its longitudinal axis;
• the figure 2 illustrates a detail view of the reduction housing and its connection with the gripper housing of the screwdriver illustrated in FIG. figure 1 ;
• the figure 3 illustrates a perspective view of the reduction and its junction with the gripper housing of the screwdriver illustrated in FIGS. Figures 1 and 2 .

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 rotary connection means, between the reduction casing and the gripping casing of a screwdriver, designed in such a way that no reaction force is transmitted during a screwing operation to the gripping case.

Thus, no reaction force is transmitted by the handle to the operator during a screwing operation. The operator then receives no reaction effort.

The invention thus provides an ergonomic screwdriver whose safety of use is increased.

7.2. Example of an embodiment of the invention 7.2.1. Architecture

We present, in relation with the Figures 1 to 3 , an embodiment of a screwdriver according to the invention.

As this is represented on the figure 1 such a screwdriver comprises a gripping casing 10 and a reduction casing 11.

• un moteur électrique 12 ;
• une boîte de vitesses 13 dont l'entrée 131 coopère avec la sortie 121 du moteur 12, et des moyens de changement de vitesse par une inversion du sens de rotation du moteur 12 ;
• des moyens d'inversion manuels 14 du sens de rotation de l'organe terminal 17.

The gripping casing 10 comprises a gripping handle 100 and an actuating trigger 101. It houses motor means, which in this embodiment comprise:

• an electric motor 12;
• a gearbox 13 whose input 131 cooperates with the output 121 of the motor 12, and gear change means by a reversal of the direction of rotation of the motor 12;
• manual reversing means 14 of the direction of rotation of the end member 17.

In this embodiment, the output 121 of the motor 12 cooperates with the input 131 of the gearbox 13 via an intermediate transmission comprising an epicyclic gear whose solar is integral with the output shaft of the motor 12, the crown is fixed, the planet carrier comprises an external toothing which meshes with gears which mesh themselves with the input 131 of the gearbox.

The gearbox with change of speed by reversing the direction of rotation of the engine is known in itself and is not described here in detail. Such a gearbox is for example described in the patent application FR-A1-2 913 361 .

The output of the gearbox is linked to a motor shaft 15 capable of being rotated in one direction by at least two speeds by the engine and the gearbox.

The inverting means 14, which are known to those skilled in the art and are therefore not described in detail, can allow an operator to reverse the direction of rotation of the motor shaft 15 to perform an operation of unscrewing.

The reduction housing 11 houses gear reduction 16. This reduction comprises a single output provided to cooperate with a terminal rotary member 17 intended to cooperate with a screw element.

The reduction casing 11 is connected to the gripping casing 10 by rotary connection means. For this, a sliding bearing is provided between the surface 111 of the reduction casing 11, the surface 102 of the gripping casing 10 and the plate 21 whose implementation is described later. The reduction casing 11 and the gripping casing 10 can thus rotate with respect to one another about the axis of rotation of the end member 17.

As will be explained in more detail below, these rotary connection means are configured in such a way that no reaction force is transmitted during a screwing operation to the gripping casing 10.

In a variant, the screwdriver may not include any gearbox or gear change means by reversing the direction of rotation of the motor. In this case, the motor output can be directly connected to the input of the reduction.

The reduction comprises a first epicyclic gear train. This first epicyclic gear includes a first solar 161 which is rotatably connected to the drive shaft 15. It also comprises first satellites 162 mounted for rotation on axes 163 integral with a first planet carrier 164, and a ring 160 The ring gear 160 is rotatably mounted inside the reduction casing 11.

In this embodiment, this reduction comprises another epicyclic gear train. It comprises a solar 165 which is secured to the first planet carrier 164, satellites 166 mounted rotatably on axes 167 integral with a planet carrier 168, and a ring 169, fixed relative to the reduction case 11 , and engraining with satellites 166.

The terminal member 17 is integral with the planet carrier 168.

In variants, other reduction elements could be implemented upstream of the reduction 16.

The rotary connection means comprise transmission means 20 to the gripping casing 10 of a reaction torque of identical intensity and direction opposite to the reaction torque transmitted by the reduction 16 to the motor means.

These transmission means 20 comprise a second epicyclic gear train. This second epicyclic gear includes a second solar 200. This solar 200 is rotatably mounted around a shaft formed in the extension of the first solar 161 and integral therewith. It is extended by a shaft portion 211 at the end of which is placed flange 210. This flange 210 is fixed to the gripping casing 10 via a plate 21. This second epicyclic gear comprises second satellites 201 rotatably mounted on wheels. 202 axes secured to a second planet carrier 203. This second planet carrier 203 is fixed to the reduction housing 11. The second satellites mesh with the ring gear 160.

The number of teeth of the solar 161 is identical to that of the solar 200. The number of teeth of the satellites 162 is identical to that of the satellites 201. The portion of the crown 160 in engagement with the satellites 162 has a number of teeth identical to the portion of the crown 160 in engagement with the satellites 201.

Considering that the input of the first epicyclic gear is the solar 161 and that its output is the planet carrier 164, and that the input of the second epicyclic gear is the solar 200 and its output is the planet carrier 203, the first and second epicyclic gear trains have identical gear ratios.

The second planet carrier 203 is fixed with respect to the reduction casing 11. The axes 202 are therefore fixed with respect to the reduction casing 11. The second satellites 201 can rotate about the axes 202. The ring gear 160 is thus stopped in rotation in the reduction casing 11 although it is mounted free to rotate, that is to say floating. The ring 200 being floating, the gripping casing 10 and the reduction casing 11 can rotate relative to each other.

The screwdriver comprises a reaction bar (not shown) which is integral with the reduction casing 11.

The screwdriver comprises means for measuring information representative of the tightening torque to which a screw-in element is screwed by means of the screwdriver. These measuring means comprise a torque sensor which comprises strain gauges integral with the second solar unit 200.

The screwdriver is connected to control means such as a control box (not shown).

7.2.2. Operation

In order to initiate a screwing operation, the operator grasps the screwdriver and makes the end rotary member 17 cooperate with the element to be screwed on. It then blocks the reaction bar against a fixed element for example integral with the assembly to be made. It finally actuates the trigger 101 to command the start of the engine 12.

The drive shaft 15 is then rotated by the engine and the gearbox clockwise from the rear of the engine, according to a first fast speed called speed of foresight.

The first solar 161 is rotated clockwise by the drive shaft 15. The first satellites 162 are driven counterclockwise by the first solar 161. Given that the ring 200 is kept stationary inside of the reduction casing 11 via the second epicyclic gear, the first planet carrier 164 rotates clockwise. The solar 165 then rotates clockwise and drives the satellites 166 counterclockwise while the planet carrier 168 turns clockwise. The end member 17 then rotates at a fast speed in the clockwise direction so that the element to be screwed undergoes a precleaning phase. The driver then delivers a given biasing torque.

During a screwing operation, the ring 160 exerts a reaction torque on the second satellites 201 tending to drive them counterclockwise. As the second satellite carrier 203 is stationary, the second satellites 201 exert a reaction torque tending to cause the second sun 200 to rotate in a clockwise direction. The second sun 200 therefore transmits a first reaction torque CR ₁ in the clockwise direction via the flange 210 to the gripping housing 10 which it is secured.

On the other hand, the reduction 16 transmits a second reaction torque CR ₂ counterclockwise to the drive shaft 15 via the first solar 161.

Since the reduction ratios of the first and second planetary gear trains are identical, the value of the first and second reaction couples is identical to the output friction.

During a screwing operation, the system formed by the gripping casing 10, the handle and the mechanical elements in question undergoes two pairs of reaction of opposite directions and of equal intensities. The sum of couples transmitted to the gripping case is therefore zero or at least negligible. The reaction torque transmitted to the hand of the operator by the handle 100 is therefore negligible. A screwdriver according to the invention therefore has great comfort and great safety of use.

The reaction torque transmitted to the gripping case 10 by the second solar 200 is measured by the torque sensor and the control box. This reaction torque is proportional to the tightening torque to which is screwed the element to be screwed.

When the control means, in this case the control box, detect that the value of this first reaction torque CR ₁ reaches a first predetermined threshold value corresponding generally to the moment when the element to be screwed lands against a piece of the assembly to be carried out, the control box controls the stopping of the precleaning phase and the beginning of the screwing phase.

The control box then actuates the means for reversing the direction of rotation of the motor. The direction of rotation of the motor 12 is thus reversed.

The drive shaft 15 is rotated clockwise at a second, slower speed called the screwing speed. The first solar 161 is rotated clockwise by the drive shaft 15. The first satellites 162 are driven counterclockwise by the first solar 161. Given that the ring 160 is kept stationary inside. of the reduction casing 11 via the second epicyclic gear, the first planet carrier 164 rotates clockwise. The solar 169 then rotates clockwise and drives the satellites 166 counterclockwise while the planet carrier 168 rotates clockwise. The end member 17 also rotates in the clockwise direction so that the screw member undergoes a screwing phase at a slower speed until the desired torque is reached. The screwdriver then delivers a tightening torque whose value is greater than that of the prying torque.

When the control unit detects that the first reaction torque CR ₁ reaches a second predetermined threshold value corresponding to the end of the screwing, it controls the stopping of the screwdriver.

Claims (13)

Screwing device comprising a gripping casing (10) and a reduction casing (11), said gripping casing (10) comprising a handle (100) and housing motor means (12, 121, 13, 14, 15), said reduction casing (11) accommodating a reduction (16) by gears whose input (161) cooperates with the output (15) of said motor means (12, 121, 13, 14, 15), said reduction (16) comprising a single output (168) cooperating with a rotary terminal member (17) for cooperating with a screw-in element, said reduction casing (11) being connected to said gripping casing (10) by rotary connection means,
characterized in that said rotary connection means are configured in such a way that a negligible reaction force is transmitted during a screwing operation to said gripping casing (10). Device according to Claim 1, characterized in that the said rotary linking means comprise means for transmitting to the said gripping casing (10) a reaction torque of substantially identical intensity and in the opposite direction to the reaction torque transmitted by the said reduction. (16) to said motor means (12, 121, 13, 14, 15). Device according to claim 2, characterized in that said reduction (16) comprises a first epicyclic gear train having a first sun (161) integral with said drive means, first satellites (162) mounted on a first planet carrier (164), and a ring gear (160) rotatably mounted in said reduction casing (11), said transmission means comprising a second epicyclic gear train having a second sun gear (200) movable in rotation relative to said first sun gear (161) and fixed to said sun gear casing; gripping (10), second satellites (201) mounted on a second planet carrier (203) fixed to said reduction housing (11), and said ring gear (160). Device according to claim 3, characterized in that the numbers of teeth respectively of the solar (161), satellites (162) and the ring gear (160) of the first epicyclic gear train being identical to those of the solar (200), satellites ( 201) and the ring gear (160) of the second epicyclic gear train. Device according to claim 3, characterized in that the input of the first epicyclic gear is said solar (161) and that its output is said carrier (164), in that the input of the second epicyclic gear is said solar ( 200) and its output is said planet carrier (203), and in that the first and second epicyclic gear trains have identical reduction ratios. Device according to any one of claims 3 to 5, characterized in that the first satellite carrier (164) is directly connected to the rotary terminal member (17). Device according to any one of claims 1 to 6, characterized in that it comprises means for measuring information representative of the tightening torque of said element to be screwed, said measuring means comprising at least one torque sensor integrated in said transmission means. Device according to claim 7, characterized in that said torque sensor is mounted on said second solar (200). Device according to claim 8, characterized in that said sensor integrates strain gages. Device according to any one of claims 1 to 9, characterized in that it comprises a gearbox (13) interposed between said motor means (12) and said reduction (16). Device according to claim 10, characterized in that it comprises means for shifting by reversing the direction of rotation of said motor means (12). Device according to claim 10 or 11, characterized in that the axis of said gearbox (13) and said reduction (16) extends parallel and offset from the axis of said drive means (12) . Device according to any one of claims 1 to 12, characterized in that it comprises a reaction bar integral with said reduction casing (11).

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