HK1190444A - Shut-off device with automatically activatable locking - Google Patents

Description

The present invention relates to a plug-type closing device whose screwing allows for automatic locking, preventing spontaneous or premature unscrewing.

In aviation, an aircraft engine requires regular maintenance and very rigorous inspection procedures to ensure perfect reliability during operation. To be able to check the internal components and any potential wear, openings are provided in the engine crankcase. During maintenance operations, the plug sealing the opening is unscrewed, and an endoscope can be inserted to explore the internal cavities and observe the condition of the engine parts. This avoids opening the crankcase and completely disassembling the engine.

These types of plugs, also called "endoscopic plugs," usually have a thread and are screwed onto a housing with a corresponding thread using a torque wrench. When the engine is running, its operation generates vibrations that can cause the loosening of threaded parts, particularly the loosening of endoscopic plugs.

Of course, there are various methods to prevent such damage. These methods may involve placing an auxiliary part in contact with the plug, before or after tightening. The parts used are of the type of brake washer, or of the pin or locking wire type.

However, the accessibility of the plugs in an engine can be very poor, as tubing and other peripheral components occupy the space around the crankcase. Therefore, installing an additional braking or locking piece on a plug requires great dexterity and even some luck to avoid losing that piece. In certain cases, the plug is accessible only by means of a long tool, and direct manual access to the plug becomes even impossible when the plug is in place. A plug provided with a braking system to address this type of problem is also known from document PCT/FR95/01461.Such a system includes locking and unlocking means that are automatically activated by the rotation of the cap and its longitudinal movement along the axis of rotation. The locking and unlocking means consist of two crowns (or cups), each having a series of teeth directed axially towards the other crown. The teeth have a pointed (or triangular) profile and interpenetrate each other during the axial movement of the cap. One of the crowns is fixed to the housing, in this case press-fitted onto it so as to be prevented from rotating. The other crown is integrated into the cap and is rotated together with it when the cap is screwed into the housing's opening.This well-known plug requires the installation of a cover on the housing by means of a press fit. This operation requires specific tools.

It is particularly observed that the rotational coupling achieved between one of the crowns and the plug is obtained by conjugated shape formations, which are made partly on this crown and partly on the central body of the plug. In the case of the device described in this document, the crown includes keys that penetrate axially relative to the screwing direction into corresponding grooves formed on the central body of the plug; these keys being movable along this longitudinal axis. As an alternative, similar devices are known in which the crown is coupled on the periphery of the central body by a system of flats. These systems all require specific machining of the central body, which can mechanically weaken it in certain cases and/or not be suitable for the search for a compact (space-saving) and optimized plug.

In addition, the cap described in this document includes means (a helical compression spring that pushes the integrated crown of the cap away from the crankcase's crown, asymmetric tooth profiles shaped on the crowns, etc.), which, although already solving the problem of premature unscrewing, can still be optimized in terms of their shape and function.

The objective of the present invention is to propose an optimized variant of the cap as previously described, which more effectively meets the need to prevent unintended unscrewing while simplifying the manufacturing and assembly constraints of the cap. Therefore, the object of the invention is also to provide a closing device comprising a stop system that prevents any unintended unscrewing due to vibrations, particularly those produced by an aircraft engine, which is directly integrated into the closing device, perfectly compact, and which does not hinder or pose a risk during opening and closing operations, even in cases of poor accessibility.

To this end, the invention relates to a closing device comprising a plug intended to be mounted on a threaded opening of a housing, or removed therefrom, respectively by screwing and unscrewing. The plug includes a central body having a thread, and locking and unlocking means opposing the spontaneous unscrewing of the plug, which are automatically activated by the rotation of the plug and its corresponding advancement in the screwing direction along a longitudinal axis. The locking and unlocking means include two releasable coupling members, wherein a first coupling member is rotatably connected to the central body, and a second coupling member is rotatably fixed relative to the housing during screwing.characterized in that the plug comprises a skirt rigidly connected to the central body and having a support area adapted to directly cooperate with a corresponding support area of the second member, and in that the first member is rotationally coupled to the skirt via guiding means formed on the periphery of the first member and extending radially relative to the longitudinal axis, these guiding means penetrating into complementary-shaped grooves formed inside the skirt, which extend along the longitudinal axis in order to allow the displacement of the first member inside the skirt along the longitudinal axis.

The central body of the plug can thus have an external cylindrical profile that requires no specific machining for the rotational drive of the first component with the plug. The rotational driving means (or coupling) are located in the invention between the first component and the skirt, which is itself rigidly connected to the central body. The perfectly cylindrical profile of the central body allows for direct guidance of the return means on this central body. The dimensions of the central body can be increased, particularly its diameter, while maintaining the same external space requirement of the plug. Moreover, the rotating coupling ring associated with the plug is extremely compact since it lacks a longitudinal keyway or internal flat.

According to other advantageous features of the invention, the guiding means consist of at least two projections angularly distributed around the periphery of the second member, in particular in a diametrically opposite manner. Each projection is radially delimited by an outer cylindrical profile having a diameter greater than the outer cylindrical surface of the first member, and angularly delimited by longitudinal edges inscribed in planes forming an angular sector around the longitudinal axis.

In this way, the distribution of forces is optimal: during assembly or disassembly, the forces are always directed perpendicular to a line passing through the longitudinal axis of the first component. The forces are thus applied in a perfectly tangential manner, without any radial component (i.e., projected onto a radial axis relative to the longitudinal axis). This helps to avoid or limit "crushing" phenomena, or even blocking of the first component during assembly or disassembly phases. These phenomena can furthermore be amplified by an increase in the friction coefficient of the materials due to contamination and/or corrosion resulting from high-temperature operating cycles. Moreover, the forces are exerted as far away as possible from the longitudinal axis, which allows for the transmission of a larger torque while avoiding or limiting "crushing" phenomena.

According to still other advantageous features of the invention, the angular sector has an angle ranging from 10 to 45°, notably 30°.

According to other advantageous features of the invention, the radial height of the protrusions relative to the longitudinal axis is greater than 1 mm, and is particularly between 1 and 5 mm.

According to other advantageous features of the invention, the first member is movable relative to the central body along the longitudinal axis, between the second member and an inner base of the skirt, the first member being urged toward the second member by elastic return means housed in the skirt.

According to other advantageous features of the invention, the central body has an axial stop against which the second member is abutted under the action of the first member, which is pushed back by the elastic return means.

According to other advantageous features of the invention, the axial stop is formed by a machined collar on the central body.

According to other advantageous features of the invention, the elastic return means are composed of a flat wire corrugated compression spring.

According to other advantageous features of the invention, the first member and the second member have generally annular shapes, the second member further including a protrusion extending radially relative to the longitudinal axis, this protrusion carrying a locking tab directed parallel to the longitudinal axis, intended to penetrate into a corresponding locking hole formed in the housing.

According to other advantageous features of the invention, the first member and the second member have respective teeth designed to interpenetrate each other during screwing/unscrowing.

According to other advantageous features of the invention, the gears have teeth with a symmetrical profile, whose lateral faces are inclined, notably at 30°/30°.

According to other advantageous features of the invention, the teeth have an asymmetric profile, whose lateral faces are oriented, for example, at 30° / 60°.

According to other advantageous features of the invention, in a first embodiment, the central body has a rotational grip configuration for rotational driving using a screwing/unscrewing tool. This solution offers the advantage of easy and economical implementation.

According to further advantageous features of the invention, the skirt has a rotational engagement configuration for rotating drive using a screwing/unscrewing tool. This solution has the advantage of enabling the realization of a more compact closure device. This solution also has the advantage of allowing a greater rotational engagement configuration for the same size of the cap, and therefore also enables the production of smaller caps with the same rotational engagement configuration.

According to other characteristics of the invention, when the skirt has a rotational engagement configuration, the skirt extends on the side opposite to the thread beyond the central body and defines the engagement configuration inside it beyond the central body.

Other specific features and advantages of the invention will become apparent from the following description, which refers to non-limiting examples of the invention, and with reference to the accompanying drawings, wherein: - Figure 1 is a cross-sectional view of a first embodiment of a closure device according to the invention; - Figure 2 is a cross-sectional view of the device of Figure 1 along line D-D; - Figure 3 is an enlarged view of detail E of the closure device according to the invention as illustrated in Figure 4; - Figure 4 is an external view of the closure device according to the invention as seen from the direction of view F of Figure 1; and - Figure 5 is a cross-sectional view of a second embodiment of a closure device according to the invention.

Since these methods of implementation are in no way limiting, one may particularly imagine variations of the invention that include only a selection of characteristics described hereafter, isolated from the other characteristics described, provided that this selection of characteristics is sufficient to confer a technical advantage or to distinguish the invention from the prior art. This selection includes at least one functional preference characteristic without structural details, or with only part of the structural details if this part alone is sufficient to confer a technical advantage or to distinguish the invention from the prior art.

First, we will describe, with reference to figures 1 to 4, a first embodiment of the invention.

According to the invention, the closing device comprises a plug 1 intended to be placed on a threaded hole 2 of a housing 3, or removed therefrom, respectively by screwing and unscrewing. For example, the threaded hole 2 is formed in a boss of the housing 3 of an engine. The threads are standard and in particular do not include any kind of axial groove or flat. The plug 1 includes a central body 4 having a generally cylindrical shape, provided at one end with a thread 5, and at the opposite end with a rotational engagement feature or shape 6 for rotating the central body 4 using a screwing/un-screwing tool (not shown).In the example illustrated, the rotational engagement configuration is a four-sided female part designed to receive a corresponding four-sided male screwing and unscrewing key. Alternatively, and not shown, the rotational engagement configuration may be a six-sided female part designed to receive a corresponding six-sided male screwing and unscrewing key. A predetermined tightening torque can be ensured by using a torque wrench. In another variant not illustrated, this part may be replaced by a male configuration on the outside of the central body 1.

The plug 1 also includes locking and unlocking means that prevent the spontaneous unscrewing of the plug 1, automatically activated by the rotation of the plug 1 and its corresponding advancement in the screwing direction along a longitudinal axis (X). Thus, during the movement of the plug toward the closed position and from this position, the respective locking and unlocking means are gradually activated simultaneously with the movement, without any operator intervention. The locking and unlocking means include two releasable coupling members: a first member 7 is rotationally coupled with the plug 1, and a second member 8 is rotatable fixed relative to the housing 3 during the screwing process. Preferably, these coupling means are of the reversible ratchet type. By "reversible ratchet," it is meant a ratchet mechanism that can be released by applying a sufficient force on the plug in the unscrewing or reverse unscrewing direction.

In a particularly advantageous manner, the locking and unlocking are ensured by locking and unlocking means, specifically by releasable coupling members comprising a first member 7 coupled to rotate with the central body 4 of the plug 1, and a second member 8 capable of being prevented from rotating relative to the housing 3 when the central body 4 is screwed into the opening 2 of the housing 3. These locking and unlocking means are arranged around the central body 4.

The first and second parts 7, 8 each have a toothed profile directed toward the opposite part. The teeth are precisely shaped on the respective annular surfaces of the first 7 and second 8 parts, facing each other. In order to prevent unwanted loosening due to vibrations and to allow the operator to deliberately unscrew the cap, the toothed profile of the first part 7 is pressed by a spring 9 against the identical toothed profile of the second part 8. This results in an interpenetration of the teeth, which prevents the spontaneous rotation of the cap 1.

Moreover, the operator hears the device click during assembly or disassembly, and therefore can be reassured about the proper functioning of the locking system.

Notably, the first and second organs 7, 8 are both mounted on the cap and inseparable from it.

The plug 1 comprises a cylindrical protective skirt 10 rigidly attached to the central body 4. This skirt 10 is typically press-fitted or forced onto the central body 4 by its end having the rotational engagement feature 6, until a positioning and locking shoulder 11, shaped on the outer periphery of the central body 4. The term "rigidly attached" means a perfect fixation of the skirt to the central body, without any degree of freedom. In a variant embodiment not illustrated in the invention, the skirt may also be welded to the central body.

The skirt has a support area 12 capable of directly cooperating in support with a corresponding support area 13 of the second member 8. The first member 7 is rotatably coupled to the skirt 10 via guiding means 14, 15 shaped on the periphery of the first member 7, which extend radially relative to the longitudinal axis X. These guiding means 14, 15 penetrate into conjugate-shaped grooves 16 formed inside the skirt 10. The grooves 16 extend along the longitudinal axis X, allowing the first member 7 to move inside the skirt along the longitudinal axis X. As a result, the first member 7 is also referred to as a "movable part" or "movable cup" due to its degree of freedom along the X-axis. It should be noted that the first member 7 has a generally cup-like, ring-like, or annular shape.

The guiding means 14, 15 consist of at least two projections angularly distributed around the periphery of the first member 7. Each projection is radially delimited by an outer cylindrical profile having a diameter larger than the outer cylindrical surface of the first member 7, and angularly delimited by longitudinal edges inscribed in planes forming an angular sector around the longitudinal axis X. This angular sector defining the projections of the guiding means has a typical angle α ranging between 10 and 45°, for example 30° as illustrated in Figure 2. The height of these projections, measured radially with respect to the longitudinal axis X, is preferably greater than 1 mm.and is, for example, between 1 and 5 mm. The forces transmitted from the skirt 10 to these guiding means 14, 15 (acting on the central shaft 4 during tightening or loosening) are very advantageously directed along tangents to the first component 7, so that no radial component is induced during tightening or loosening. In the example illustrated in Figure 2, two diametrically opposed guiding means are provided. In this case, an angle β of typically 90° is observed between the directly loaded longitudinal edges either during tightening or during loosening. In variants of the invention not illustrated,More than two guidance means can be foreseen, for example three guidance means arranged angularly around the longitudinal axis X.

According to the invention, the first member 7 is translationally movable relative to the central body 4 between the second member 8 and the inner bottom of the skirt 10, the first member 7 being pushed toward the second member 8, toward the opening of the skirt 10, opposite the inner bottom, under the influence of a spring 9 located around the central body 4. The central body 4 includes an axial stop 18 against which the second member 8 cooperates as a stop under the stress of the first member pushed by the spring 9. In the illustrated example, this axial stop 18 is formed by a machined collar located at the periphery of the central body 4, against which an internal shoulder of the second member 8 comes into contact. In a variant not illustrated, it may be provided that the collar be replaced by an elastic ring.

The second member 8 is rotatable freely relative to the central body 4. However, it is immovable in rotation relative to the housing 3 during tightening. The second member 8 has a generally annular shape. It includes a protrusion 19 extending radially with respect to the longitudinal axis X. This protrusion 19 carries a locking tab 20 oriented parallel to the longitudinal axis X. The tab 20 is intended to enter a corresponding locking hole 21 formed in the housing 3.

When screwing the central body 4 into the threaded hole 2, the second member 8 initially follows the rotational movement of the plug 1. When the screwing reaches a certain stage, the lug comes into contact with the outer surface of the housing 3 while rotating, until it aligns with the locking hole 21. Any further axial movement of the plug along the longitudinal axis X during screwing causes the lug to advance correspondingly into the locking hole until the second member 8 conforms to the outer surface of the housing 3. Further axial movement of the central body 4 toward the housing along the longitudinal axis X during screwing causes the teeth of the first 7 and second 8 members to intermittently interlock.Indeed, the gear set (or tooth arrangement) of the first member 7 is rotated together with the plug, while the gear set (or tooth arrangement) of the second member 8 is, at this stage, rotationally fixed relative to the housing 3. During the relative rotation between the two gear sets, the teeth alternately find themselves in an interpenetrating configuration and a tip-to-tip configuration, the transition from one configuration to the other being achieved by the relative sliding of the respective adjacent faces of the two gear sets. Therefore, the first member 7 performs translations along the longitudinal axis X,Inside the skirt 10, towards the back (marking 6) and towards the front (tapped hole 2) during the screwing of the plug, which resembles an oscillating movement. Each translation is performed over a stroke corresponding to the height of the teeth, which is the distance between the tip of one tooth and the groove between two teeth, projected along the longitudinal axis X. Note that the teeth preferably have a symmetric profile, meaning that the sliding surfaces have identical angles acting during tightening or loosening, in order to optimize the system's lifetime and better control the friction coefficients. An appropriate symmetric tooth profile, for example, has angles of 30°/30° on either side of each tooth.These angles are considered with respect to a plane perpendicular to the longitudinal axis X (Figure 3). In another embodiment not shown, the teeth can have an asymmetric profile, especially to provide a higher friction coefficient in one direction than in the other. An appropriate asymmetric tooth profile, for example, has angles of 30° / 60° on either side of each tooth.

Spring 9 is preferably a flat wire wave spring. Such a spring has a very small footprint and significantly reduces the weight of the plug, compared to a similar plug equipped with a helical compression spring.

The plug is assembled as follows: the components are placed on the central body by its rear end, located on the side of the rotation grip imprint or shape 6. The second member 8 is first placed around the central body 4. Then the first member 7 is placed around the central body 4 and stacked on top of the second member 8, tooth against tooth. The spring 9 is then placed around the central body and pressed against the first member 7. The protective skirt 10 is then fixed by force or pressed around the central body and these elements 8,7, 9. The skirt 10 simultaneously provides protection by forming the outer casing of the plug and by providing a rotational (or driving) coupling between the central body 4 and the first member 7. It should be noted that the first member and the second member have very compact external shapes, especially along the longitudinal axis X. Their thickness in this direction can be less than 10-15 mm. For example, the first member may have a thickness ranging from 5 to 10 mm. These examples are in no way limiting. The type of spring used, the compactness of the first and second members, as well as the rotational driving means selected between the first member and the skirt contribute to making the plug particularly light and compact.capable of meeting very strict constraints.

We will now describe, with reference to Figure 5, a second embodiment of the invention, but only insofar as it differs from the first embodiment previously described.

The skirt 10 includes a rotational engagement feature 6 for rotational driving using a screwing/unscrewing tool. The feature 6 is formed at the center of the skirt 10 along the longitudinal axis (X) of the skirt. In the example illustrated, the rotational engagement feature is a four-sided female portion designed to receive a corresponding four-sided male screwing/unscrewing key.

In the example shown, on the side opposite to the thread of the central body 4, the skirt extends beyond the end of the central body 4. The portion of the skirt that extends beyond the central body 4 has a radially inner wall with a non-circular shape defining the rotational engagement feature 6. Advantageously, the bottom of the rotational engagement feature is hermetically sealed by the end of the central body 4.

This skirt 10 is typically mounted in a forced fit or pressed onto the central body 4 by the longitudinal end of the skirt 10 corresponding to the bottom of the rotating engagement configuration 6, until a positioning and locking shoulder 11, shaped on the outer periphery of the central body 4. Typically, the positioning and locking shoulder 11 has a geometric shape, notably substantially square as shown in the example of figure 5, which fits tightly onto a corresponding profile of the central body 4. The term "rigidly attached" means a perfect interference fit of the skirt onto the central body, without any degree of freedom. In a variant embodiment not illustrated in the invention, the skirt may also be welded onto the central body.

The invention is not limited to the embodiments described above and includes all technical equivalents of the means presented.

In particular, it was previously indicated that the invention relates to a sealing device comprising an endoscope plug, this device being intended to close an appropriate opening through which access to the interior of the housing can be made. The device of the invention generally relates to any sealing device comprising a plug as described above, whether or not this plug has other characteristics or functionalities. For example, such a sealing device according to the invention can itself constitute a thermal sensor, a vibration sensor, a particle detector (chip detector), or any other detection means.

Furthermore, the skirt 10 as described above is, for example, rigid, meaning it is non-deformable in compression along the longitudinal axis of the screw. The rigid skirt forms a spacer resting on the support area 13 of the second member 8. In another embodiment of the invention, the skirt can instead be elastic, meaning that its structure is designed to allow deformation, at least in compression along the longitudinal axis of the screw. For this purpose, it may include perforated, slitted, or pleated areas enabling deformation and allowing it to return to its original shape after release of the compressive forces. Such an elastic skirt further enhances the safety of the system by increasing the elastic reserve during tightening. It also helps reduce thread seizing phenomena by limiting or adjusting the tightening force to a predetermined value.

Moreover, the movement of the first organ 7 inside the skirt 10 can be adjusted as needed.

Claims (15)

1. Sealing device comprising a plug (1) intended to be placed in a threaded hole (2) in a case (3), or removed therefrom, respectively by screwing and unscrewing, the plug comprising a central body (4) provided with a screw thread (5), and locking and unlocking means opposing the spontaneous unscrewing of the plug, activated automatically by the rotation of the plug (1) and its corresponding movement in the direction of screwing along a longitudinal axis (X), the locking and unlocking means comprising two releasable coupling components (7, 8), a first component (7) of which is coupled in rotation with the central body (4) and a second component (8) of which can be immobilized in rotation with respect to the case (3) during screwing, characterized in that the plug (1) comprises a skirt (10) rigidly connected to the central body (4) and having a bearing zone (12) capable of cooperating directly with a corresponding bearing zone (13) of the second component (8), and in that the first component (7) is coupled in rotation with the skirt (10) via guide means (14, 15) configured on the periphery of the first component (7) and extending radially with respect to the longitudinal axis (X), said guide means (14, 15) entering mutually corresponding grooves (16) configured inside the skirt (10), which extend along the longitudinal axis (X) so as to allow the displacement of the first component (7) inside the skirt (10), along the longitudinal axis (X).
2. Sealing device according to claim 1, characterized in that the guide means (14, 15) are constituted by at least two protrusions angularly distributed on the periphery of the first component, about the longitudinal axis (X), in particular in a diametrically opposed manner, each protrusion being delimited, on the one hand radially by a cylindrical outer profile having a diameter greater than the outer cylindrical surface of the first component (7), and on the other hand angularly by longitudinal edges inscribed within planes forming an angular sector about the longitudinal axis (X).
3. Sealing device according to claim 2, characterized in that the angular sector has an angle comprised between 10 and 45°, particularly 30°.
4. Sealing device according to claim 2 or 3, characterized in that the radial height of the protrusions with respect to the longitudinal axis (X) is greater than 1 mm, and is in particular comprised between 1 and 5 mm.
5. Sealing device according to any one of claims 2 to 4, characterized in that the first component (7) is movable with respect to the central body (4) along the longitudinal axis (X), between the second component (8) and an inner base of the skirt (10), the first component (7) being urged towards the second component (8) by resilient return means (9) housed in the skirt (10).
6. Sealing device according to claim 5, characterized in that the central body (4) comprises an axial stop (18) against which the second component (8) abuts under the force of the first component (7) urged by the resilient return means (9).
7. Sealing device according to claim 6, characterized in that the axial stop (18) is constituted by a collar machined on the central body (4).
8. Sealing device according to any one of claims 5 to 7, characterized in that the resilient return means (9) are constituted by a flat wire wave compression spring.
9. Sealing device according to any one of claims 1 to 8, characterized in that the first component (7) and the second component (8) have generally annular shapes, the second component (8) also comprising a projection (19) extending radially with respect to the longitudinal axis (X), said projection carrying an immobilization lug (20) directed parallel to the longitudinal axis (X), intended to enter a corresponding immobilization hole (21) configured in the case (3).
10. Sealing device according to any one of claims 1 to 9, characterized in that the first component (7) and the second component (8) comprise respective sets of teeth intended to mesh together during screwing/unscrewing.
11. Sealing device according to claim 10, characterized in that the sets of teeth have teeth with a symmetrical profile, the lateral faces of which are inclined particularly at 30°/30°.
12. Sealing device according to claim 10, characterized in that the sets of teeth have teeth with an asymmetrical profile, the lateral faces of which are inclined particularly at 30°/60°.
13. Sealing device according to any one of claims 1 to 12, characterized in that the central body (4) comprises a rotary drive configuration (6) for driving in rotation using a tool for screwing/unscrewing.
14. Sealing device according to any one of claims 1 to 12, characterized in that the skirt (10) comprises a rotary drive configuration (6) for driving in rotation using a tool for screwing/unscrewing.
15. Sealing device according to claim 14, characterized in that the skirt is extended beyond the central body on the side remote from the screw thread and defines the drive configuration inside the skirt beyond the central body.