Expansion rivet

Abstract

An expansion rivet (10) comprising a body (200) including a support plate (120) forming a head with a passage hole (110) and two arms (130) rising from the support plate (120), and a pin (100) including a support head (20) with a bottom surface (22) and a stem (50) rising from the support head (20), the pin (100) being intended to be inserted into the body (200) through the hole (110) formed on the support plate (120), wherein each arm (130) includes a central lug (160) and two lateral lugs (140) separated by the central lug, the stem (50) includes fins (40) along the length of the stem, the central lug (160) is able to move away from each other in a radial plane in an outward direction by raised portions (62, 64, 66) separating the fins (40), and the lateral lugs (140) are able to deform in a radial plane by the fins (40) when the pin (100) is inserted into the body (200).

Description

Technical Field

[0001] This invention relates to a fastener, particularly a plastic rivet, and more specifically to an expansion rivet designed for fastening within fastening holes formed in at least two structures. For example, automotive trim pieces can be fastened to a vehicle body panel using the rivet of this invention. Background Technology

[0002] An expansion rivet basically consists of a pin and a body, which are typically made of a resilient material and thus capable of deforming and retracting for assembly and disassembly. This type of device is known from the prior art.

[0003] U.S. Patent No. 20150176621 A1 describes a rivet for a vehicle consisting of an inner part and an outer part. The outer part includes two spaced-apart split arms, each having a protrusion on its outer surface that serves as a snap-fit ​​protrusion. When the inner part is inserted between these arms, the arms deflect outwards. The snap-fit ​​protrusion performs engagement action on two radially opposing connection areas in a fastening hole, and is therefore exposed to the risk of vibration when moving in different directions. Another problem involves the risk of creep on thin portions of the structure to be fastened due to a gap between the two parts. Summary of the Invention

[0004] The present invention aims to overcome these disadvantages by proposing an expansion rivet that performs well in terms of locking and prevents creep even in thin sections of the structure.

[0005] For this purpose, the present invention relates to an expansion rivet comprising a body and a pin, the body comprising a support plate having a head having a channel hole and two arms extending from the support plate, the pin comprising a support head having a bottom surface and a rod extending from the support head, the pin being intended to be inserted into the body through a hole formed in the support plate.

[0006] According to one aspect of the invention, the rivet has the following characteristics:

[0007] - Each arm includes a central lug and two lateral lugs separated by the central lug;

[0008] - The rod includes fins along its length.

[0009] - When the pin is inserted into the body, the central lug can move away from each other in the radial direction in the outward direction through the protrusions of the spacer fins, and the lateral lugs can deform in the radial plane through the fins.

[0010] The invention is advantageously practiced according to the embodiments and alternative embodiments described below, which may be considered individually or in any technically possible combination.

[0011] In one embodiment, the central lug includes a primary retention protrusion, and the lateral lugs include lateral retention protrusions.

[0012] In one embodiment, the lateral lug is configured such that the lateral lug is guided by the fin during the insertion or removal of the pin.

[0013] In one embodiment, the support plate includes a recess designed to receive the support head of the pin.

[0014] In one embodiment, the hole is formed by a positioning ring, and the pin includes at least one first positioning stop and at least one second positioning stop, the positioning ring being held in the assembly position by the at least one first positioning stop and at least one second positioning stop.

[0015] In one embodiment, the pin includes at least one third positioning stop, and the distance between the at least one third positioning stop and the bottom surface of the support head corresponds to the thickness of the positioning ring.

[0016] In one embodiment, each central lug of the arm includes an inner surface designed to guide a pin into the body.

[0017] In one embodiment, the pin includes three steps formed by protrusions.

[0018] In one embodiment, the support plate includes at least one tool insertion arrangement into which a tool can be inserted to disengage the bottom surface of the support head from the support plate via a lifting movement.

[0019] In one embodiment, the main retention protrusion includes at least two different, staggered geometric configurations.

[0020] In one embodiment, the lateral retaining protrusion has an angle that facilitates rivet locking.

[0021] In one embodiment, the pin includes at least one protrusion that forms a clamping completion indicator.

[0022] In one embodiment, the body includes at least one slot window designed to receive the at least one clamping completion indicator.

[0023] In one embodiment, the pin includes four fins arranged at equal intervals along the circumference.

[0024] Advantageously, the central and lateral lugs of the arm allow for a greater radially distributed connection area between the rivet and the hole in the structure, enabling the rivet to exhibit isotropic behavior under mixed-activity conditions, thereby resulting in good vibration performance. Furthermore, the presence of multiple steps ensures good retention of structures of variable thickness (even thin structures) to be fastened and prevents creep. Therefore, the expansion rivet according to the invention is suitable for structures of varying thicknesses. Attached Figure Description

[0025] Other advantages, objects, and features of the present invention will become apparent upon reading the following description with reference to the accompanying drawings, which are for illustrative purposes only and in no way limit the invention, in which:

[0026] Figure 1 An exploded view of an expansion rivet according to one embodiment is shown;

[0027] Figure 2A A top view of the body of the rivet according to the present invention is shown;

[0028] Figure 2B A perspective view of the pin of the rivet according to the present invention is shown;

[0029] Figure 3A A perspective view of a rivet in its assembled position according to the present invention is shown;

[0030] Figure 3B It shows along Figure 3A A cross-sectional view of the cutting plane AA, in which the rivet is in the assembled position;

[0031] Figure 4A A side view of an expansion rivet according to one embodiment is shown, wherein the rivet is in the attached position;

[0032] Figure 4B It shows along Figure 4A A cross-sectional view of the cutting plane BB;

[0033] Figure 4C It shows along Figure 4A A cross-sectional view of the cutting plane CC;

[0034] Figure 4D It shows along Figure 4A A cross-sectional view of the cutting plane P-DD, in which structures 300 and 400 have been secured. Detailed Implementation

[0035] Different figures and parts within the same figure are not necessarily shown at the same scale. In all figures, the same parts have the same reference numerals.

[0036] The terminology used in this specification should not be interpreted in a restrictive or limiting manner under any circumstances, but only as it is used in conjunction with a detailed description of certain embodiments of the invention.

[0037] Figure 1 An exploded view of an expansion rivet 10 according to the invention is shown, which is essentially composed of a body 200 and a pin 100. This is for illustrative purposes only. Figure 4D As shown, the device 10 can be used to fasten, for example, a first structure 300 of an instrument panel to, for example, a second structure 400 of a vehicle body panel, which will be described in detail below. The first and second structures are each provided with through holes to allow for such fastening using expansion rivets 10.

[0038] The two basic components 100 and 200 of the rivet can be manufactured using known plastic molding methods, more specifically, using engineering plastics such as polyamide, acetal resin, or thermoplastic polyester. Preferably, components 100 and 200 are made of known materials that are resistant to aging and extreme temperatures.

[0039] In this specification, the “assembly position” of the expansion rivet 10 should be understood as the position in which the pin 100 and the body are pre-assembled so that the rivet is ready for fastening, and the pin 100 is in the open position; the “attachment position” of the expansion rivet 10 should be understood as the position in which the pin is fully received by the body 200, and the pin is in the locked position.

[0040] The main body 200 includes a support plate 120 forming a head and a plurality of expansion arms 130 connected to the support plate. The head has a channel hole 110. The arms 130 have a predetermined elasticity at least along a certain length. The pin 100 includes a support head 20 and a rod 50 connected to the support head 20, and can be inserted through the hole 110 in the main body 200 while moving the arms 130 away from each other. In the attached position, the outer surface of the arms 130 engages circumferentially with the through hole in the second structure 400.

[0041] In one embodiment, arm 130 has a reduced cross-section at its free end opposite to the support plate, for example, in the form of a truncated cone. This arrangement advantageously allows for compensation of the offset between the through-hole centers, or even allows for blind assembly.

[0042] In a preferred embodiment, the support plate 120 has a disc-shaped shape, including a recess 180 for receiving the support head 20 of the pin 100. In the attachment position, the top surface of the support head and the top surface of the support plate form the desired rivet appearance. The support plate 120 further constitutes a gripping area for the rivet to be assembled. The support head 20 includes a tool insertion arrangement 182 into which a tool can be inserted to disengage the bottom surface 22 from the support plate 120 via a lifting movement. Preferably, the insertion arrangement takes the form of a protrusion with a chamfer 182, through which a screwdriver can be inserted into the space formed between the support head 20 and the support plate 120 to pull out the lever 50. Therefore, this arrangement allows the rivet 10 to separate under load.

[0043] In an advantageous embodiment, the body 200 includes two arms 130 substantially perpendicular to the support plate and spaced apart by a space 150. A rod 50 is substantially perpendicular to the support head 20. The arms rise from the bottom surface of the support plate 120 and are arranged symmetrically with respect to the space 150 that separates them. Each arm includes a central lug 160 and two lateral lugs 140 spaced apart by the central lug 160. The rod 50 includes fins 40 spaced apart by spaces 60 or 80 along its length, these spaces receiving protrusions 62, 64, 66 or stops 84, 86, 90. When the pin 100 is inserted into the body through the channel hole 110, the expansion arms 130 are pushed outward by the rod 50, the central lugs move away from each other in a radially outward direction via the protrusions 62, 64, 66, and the lateral lugs 140 deform in a radially plane via the fins. Advantageously, the deformation of the lateral lug 140 and the central lug 160 allows for the formation of more radially distributed connection areas at the through-hole of the second structure 400.

[0044] Preferably, the lateral lug 140 is connected to the central lug 160 via a portion 170 at the free end opposite to the support plate 120. When the central lug 160 moves away from each other in an outward direction, the lateral lug 140 is pushed and deformed by the fins 40 of the rod 50; this deformation is preferably rotational deformation in the radial plane. The fact that the lateral lug 140 is connected to the central lug 160 at its free end makes this rotational deformation of the lateral lug in the radial plane possible. The arm 130 has outwardly projecting portions on its outer surface, particularly in the connection area with the structure, which will be described with reference to the other figures.

[0045] In one embodiment, the channel hole 110 is defined by a ring 186 having two opposing flexible sides 184. The pin 100 includes at least one first positioning stop 84 and at least one second positioning stop 86, and the ring 186 can be secured between the first stop 84 and the second stop 86. More specifically, when the pin 100 is inserted into or removed from the body 200, the elastic nature of the flexible sides 184 allows the stops to pass through the ring 186.

[0046] Figure 2A A top view of the body 200 according to one embodiment is shown. It can be seen that the disc-shaped support plate 120 has a recess 180 that passes through the top surface of the plate 120 and through the center of the disc. A ring 186 is located on the central portion of the recess 180 and provides passage to the space 150 that separates the arms 130. The support plate 120 includes a cavity 188 adjacent to the flexible side 184 of the ring, thereby allowing space for the flexible side 184 to bend outward relative to the ring. Two protrusions with chamfers 182 are also provided on two opposite sides of the channel hole 110, by means of which a tool can be used to disengage the pins 100 of the rivets in the attached position.

[0047] In one embodiment, a guide region 168 is provided on the inner surface of the central lug 160, while the lateral lugs 140 are arranged such that the fins 40 are guided, for example, by grooves 148 present on the inner surface. This will be described in more detail below.

[0048] Figure 2B A perspective view of the pin 100 of the rivet 10 is shown. The presented support head 20 has a shape that can mate with the recess 180 of the support plate. Figure 2B As can be seen, the rod 50, which rises from the bottom surface 22 of the support head, essentially comprises fins 40 that extend radially outward from the rod 50 and are spaced apart from each other. In one embodiment, four fins 40 are arranged at equal circumferential intervals. Stress steps 62, 64, and 66 are provided in the spaces 60 that respectively separate the first fin from the second fin and the third fin from the fourth fin. Positioning stops 84, 86, and 90 are also provided in adjacent spaces 80 that respectively separate the first fin from the fourth fin and the second fin from the third fin. In the described embodiment, the spaces 80 are positioned longitudinally along the rod 50. Advantageously, the rod 50 has a reduced cross-section at its free end opposite to the support head, thereby facilitating the insertion of the pin 100 into the ring 186 during the assembly of the rivet according to the invention.

[0049] During the assembly phase, the pin 100 is inserted into the body 200 through the hole 110 until the first positioning stop 84 protrudes from the ring, and then the ring is secured between the first stop 84 and the second positioning stop 86, thus positioning the rivet 10 in the assembled position, as shown. Figure 3A As shown. Figure 3B It shows along Figure 3A A cross-sectional view of the cutting plane AA, wherein the rivet is in the assembled position, in which the flexible side 184 is positioned between stops 84 and 86. Advantageously, once in the assembled position, the first stop 84 constitutes a stop (e.g., in the form of a platform) for sudden movement relative to the ring 186, thereby preventing the two parts from disengaging by simple traction, while if the pin continues to be pushed toward the body, the second stop 86 at this time allows for gentle movement relative to the positioning ring (e.g., having a substantially inclined surface). This arrangement, for example, provides resistance to various activities when moving the rivet to the assembled position. The fin 40 engages with the groove 148 present on the inner surface of the lateral lug 140, and thus the pin undergoes a guiding movement when the pin 100 is driven into the body 200.

[0050] To fasten the first structure 300 to the second structure 400, the expansion rivet 10, in its assembled position, is inserted into a through hole in the structure by pressing it against the body 200, and then a thrust is applied to the support head 20. The stress step contacts a guide region 168 present on the bottom surface of the central lug 160 of the arm 130. Advantageously, the guide region 168 (e.g., in the form of an inclined surface) reduces the resistance at the stress steps 62, 64, 66 of the pin 100 during insertion, thus limiting the force required to insert the pin 100. The arms 130, particularly the central lug 160, have moved away from each other, and the main retention protrusions 162, 164, 166 on their outer surfaces are thus expanded. The fins 40 guided in the groove 148 further repel the lateral lugs 140, which include protrusions forming lateral retention protrusions 142, 144 on their outer surfaces. In one embodiment, the lateral retaining protrusions 142, 144 have a predetermined angle that facilitates good retention at the circumference of the hole and secures the rivet in the structure to be fastened.

[0051] Continue driving the pin 100 into the body 200 until the bottom surface 22 of the support head 20 contacts the support plate 120 and until the support head 20 is fully received within the recess 180, as shown. Figure 4AAs shown in the figure, structures 300 and 400 to be fastened are not shown. During this assembly phase, the side 184 of the locating ring moves smoothly over the second locating stop 86 and is positioned between the bottom surface 22 of the support head and at least one third stop 90. In one embodiment, the distance between one or each third locating stop 90 and surface 22 approximately corresponds to the thickness of the locating ring, such that, according to... Figure 4A In the attachment position, the pin 100 is locked to the body 200 before a removal force is applied to it. Advantageously, once in the attachment position, the third positioning stop 90 constitutes a stop for sudden movement relative to the flexible ring, thus allowing the rivet to be unlocked.

[0052] The rivet according to the invention can be removed from the receiving structure by lifting using a tool inserted into an arrangement designed for separation of the rivet under load. Once the tool has been used to move the third locating stop 90 past the locating ring 186, the pin 100 is removed through the channel hole 160 under tension acting on the support head 20. Due to the specific elasticity of the arm, the arm 130 returns to a substantially parallel aligned position. In this position, the rivet 10 can be removed from the hole and reused.

[0053] Advantageously, the positioning stops 84, 86, 90 and the positioning ring 186 cooperate to manage the relative position between the main body and the pin.

[0054] In one embodiment, the pin 100 includes at least one protrusion 88 that provides the operator with a clamping sensation indicating that the rivet has been pressed into the attachment position. The protrusion 88 may be configured between the support head 20 and the second stop 86. Advantageously, this arrangement of the clamping completion indicator allows the operator to observe the end of the stroke and prevents the operator from continuing to press down, thereby improving the ergonomics of assembly. In one embodiment, the body 200 includes at least one locating window designed to receive the at least one clamping indicator 88.

[0055] When the expansion rivet 10 is in the attached position, steps 62, 64, and 66 at different heights on the rod 50 contact the central lug 160 by pushing it outward. Advantageously, the presence of multiple steps ensures good retention of the structure to be fastened (even a thin structure) and prevents creep. Therefore, the expansion rivet according to the invention is suitable for structures of different thicknesses.

[0056] The spacing between the lateral lug 140 and the central lug 160 forms a connection area at the through-hole of the second structure 400. These radially distributed connection areas exhibit isotropy when the rivet is exposed to various activities. Advantageously, the multiple connection areas between the rivet and the hole provide good retention for the structure, thus preventing noise, backlash, and even vibration.

[0057] The interaction between the stress steps 62, 64, 66 and the central lug 160, and between the fin 40 and the lateral lug 140, multiplies the connection area between the pin 100 and the body 200, thereby preventing any adverse detachment of the pin 100 even in a thin structure.

[0058] However, in Figure 4D Structures 300 and 400 are specifically shown to better illustrate the connection area between the rivet and the structure. Steps 62, 64, and 66, located at different heights along the pin 100, allow the arm 130 to move away from each other in an outward direction, and allow the inner surface of the body to bear stress over a certain length when the pin 100 is inserted into the body 200.

[0059] Advantageously, stress is applied via the steps, creating stress transfer regions F, G, and H on the inner surface of arm 130. These stress transfer regions allow stress to be transferred to the steps of structures of varying thicknesses and prevent creep. (Refer to...) Figure 4D Regions F, G, and H correspond to steps 62, 64, and 66, respectively. In the illustrated embodiment, the pin 100 is provided with three stress steps 62, 64, and 66.

[0060] Due to the space between the steps, the stepped shape of the protrusions 62, 64, and 66 facilitates the deformation of the expansion arm 130, which is even more advantageous for structures with large thicknesses. This arrangement allows for limiting the stress required to insert the pin without reducing the stiffness of the arm, which would otherwise risk being torn off the secured structure.

[0061] In one embodiment, the retaining protrusions 162, 164, and 166 on the outer surface of the central lug 160 have two different, staggered geometric configurations. Advantageously, this arrangement allows stress distribution in the region circumferentially connected to the through-hole. Figure 4B and Figure 4C The figure also shows cross-sections of the main retaining protrusions 162, 164, and 166 with different geometries, which respectively show the cross-sections along the main retaining protrusions 162, 164, and 166. Figure 4AThe cross-sectional views of the cutting planes BB and CC are shown. The inner surface of the fin 40 is configured such that the lateral lug 140 is guided by the fin 40 during the insertion or removal of the pin 100. In one embodiment, at least one lateral lug 140 is provided with a groove 48 along its length to receive the fin 40. Advantageously, this arrangement allows the pin 100 to be guided while sliding within the body 200, thereby preventing assembly that would hinder the fastening process between the two components 100, 200.

[0062] The fin 40 also forms a stress region through the lateral lug 140. (See reference...) Figure 4C During the insertion of the pin 100, the main retaining protrusion displaces along axis 1. Parallel to this axis, the pin 100 transmits radial displacement along axis 2, which is complementary to axis 1. The lateral retaining regions of the body are radially retained according to the contact point between the lateral lug and the body. In the described embodiment, six retaining regions exist on the outer periphery of the expansion rivet. These retaining regions are radially distributed such that, under mixed activity, the rivet exhibits isotropic behavior, thereby achieving good vibrational behavior.

[0063] List of reference numerals

[0064] Figure Labels name 10 Expansion rivets 100 pin 20 Support head 40 fins 50 rod 60 space 62、64、66 Stress steps 80 space 84、86 First positioning stop 86 Second positioning stop 88 Clamping indicator 90 Third positioning stop 200 main body 110 Channel hole 120 support plate 130 arm 140 Lateral lugs 142、144 Lateral retention protrusion 148 Longitudinal groove 150 Space of the arm 160 Central lug 162、164、166 Main retention protrusion 168 Guide Area 170 The part connecting the lugs 180 concavity 182 chamfer 184 The elastic edge of the positioning ring 186 Positioning ring 188 cavity F, G, H Connecting areas

Claims

1. An expansion rivet (10) comprising a body (200) and a pin (100), the body (200) comprising a support plate (120) forming a head having a channel hole (110) and two arms (130) erected from the support plate (120), the pin (100) comprising a support head (20) having a bottom surface (22) and a rod (50) erected from the support head (20), the pin (100) being intended to be inserted into the body (200) through the channel hole (110) formed in the support plate (120), characterized in that: - Each of the arms (130) includes a central lug (160) and two lateral lugs (140) separated by the central lug. - The rod (50) includes fins (40) along the length of the rod; - These central lugs (160) are able to move away from each other in the radial plane in an outward direction by means of the protrusions (62, 64, 66) that separate the fins (40), and these lateral lugs (140) are able to deform in the radial plane by means of the fins (40) when the pin (100) is inserted into the body (200).

2. The expansion rivet (10) according to claim 1, wherein, These central lugs (160) include primary retention protrusions (162, 164), and these lateral lugs (140) include lateral retention protrusions (142, 144).

3. The expansion rivet (10) according to claim 1, wherein, These lateral lugs (140) are configured such that during the insertion or removal of the pin (100), these lateral lugs (140) are guided by the fins (40).

4. The expansion rivet (10) according to claim 1, wherein, The support plate (120) includes a recess (180) designed to receive the support head (20) of the pin (100).

5. The expansion rivet (10) according to claim 1, wherein, The channel hole (110) is formed by a positioning ring, and the pin (100) includes at least one first positioning stop (84) and at least one second positioning stop (86), and the positioning ring is held in the assembly position by the at least one first positioning stop (84) and the at least one second positioning stop (86).

6. The expansion rivet (10) according to claim 5, wherein, The pin includes at least one third positioning stop (90), and the distance between the at least one third positioning stop (90) and the bottom surface (22) of the support head (20) corresponds to the thickness of the positioning ring.

7. The expansion rivet (10) according to claim 1, wherein, Each central lug (160) of these arms (130) includes an inner surface that guides the pin (100) into the body (200).

8. The expansion rivet (10) according to claim 7, wherein, The pin (100) includes three steps formed by these protrusions.

9. The expansion rivet (10) according to any one of claims 4 to 8, wherein, The support plate (120) includes at least one tool insertion arrangement (182) into which a tool can be inserted to disengage the bottom surface of the support head (20) from the support plate (120) via a lifting movement.

10. The expansion rivet (10) according to claim 2, wherein, These main retention protrusions (162, 164) include at least two different, staggered geometries.

11. The expansion rivet (10) according to claim 2, wherein, These lateral retaining protrusions (142, 144) have angles that are advantageous for securing the expansion rivet (10).

12. The expansion rivet (10) according to any one of claims 2 to 7, wherein, The pin (100) includes at least one protrusion (88) that forms a clamping completion indicator.

13. The expansion rivet (10) according to claim 11, wherein, The main body (200) includes at least one slot window designed to receive the at least one clamping completion indicator.

14. The expansion rivet (10) according to any one of claims 2-7, wherein, The pin (100) includes four fins (40) that are evenly spaced circumferentially.

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