WO2013074002A1

WO2013074002A1 - A vehicle safety device actuator

Info

Publication number: WO2013074002A1
Application number: PCT/SE2011/051362
Authority: WO
Inventors: Stefan Kuntzsch
Original assignee: Autoliv Development Ab
Priority date: 2011-11-14
Filing date: 2011-11-14
Publication date: 2013-05-23

Abstract

The present invention relates to a vehicle safety device actuator (1) comprising a housing (2) and an extension element part (3) At least a part of the extension element part (3) is arranged to move towards an opening (5) at a first end (2a) of the housing (2) when the vehicle safety device actuator (1) is activated. The vehicle safety device actuator (1) comprises a lid part (8) having a first side (8a), facing away from the opening (5) and a second side (8b), facing the opening (5). The lid part in turn comprises engaging means (9; 9a, 9b) arranged to engage the housing (2), where the engaging means (9; 9a, 9b) are arranged to disengage the housing (2) when an external element (6) applies a certain pressure against at least a part of the first side (8a).

Description

Title

A vehicle safety device actuator

Description of invention

The present invention relates to a vehicle safety device actuator comprising a housing and an extension element part. At least a part of the extension element part is arranged to move towards an opening at a first end of the housing when the vehicle safety device actuator is activated.

Today, many vehicles are equipped with at least one pyrotechnically driven safety device, interior airbags, one or several, are well known in the art.

Furthermore, many vehicles are constructed to comprise at least one exterior airbag, intended to be inflated in the case of a collision with a pedestrian and to alleviate the collision force that the pedestrian is subject to.

It has also been proposed to use hood lifting arrangements. These arrangements are generally constructed such that the rear part of the hood, i.e. the part closest to the windscreen, is lifted in the event of a collision with a pedestrian. Thus a pedestrian that has been hit is protected from hard, non-flexible parts beneath the hood, e.g. an engine block, and is directed towards the windshield that has shock absorbing qualities.

Examples of other such safety devices are lifters to create a roll-over protection for convertibles, pistons to activate safety equipment in a vehicle such as pelvis pushers, emergency breaking rods and bumper extensions. All of the above arrangements are in most cases driven by a pyrotechnic device, which ensures a sufficiently quick inflation of airbags and/or displacement of a piston in for example a hood lifting arrangement in the event of an impact.

However, when handling these safety devices, comprising a pyrotechnic actuator with a pyrotechnic device, there is always a risk of undesired detonation of the pyrotechnic device, which could result in severe injuries. The risk is present both when handling the safety devices before mounting, during mounting and when service is required. For example, if the hood needs to be lifted for service, there is a risk that a pyrotechnic device of a hood lifting arrangement might detonate.

The object of the present invention is to provide a pyrotechnic actuator which is safe to handle, mount and to service, without the risk for reduced functionality in the event of a collision.

Said object is achieved by means of a vehicle safety device actuator comprising a housing and an extension element part. At least a part of the extension element part is arranged to move towards an opening at a first end of the housing when the vehicle safety device actuator is activated. The vehicle safety device actuator comprises a lid part having a first side, facing away from the opening, and a second side, facing the opening when the lid part is mounted to the housing. The lid part in turn comprises engaging means arranged to engage the housing, where the engaging means are arranged to disengage the housing when an external element applies a certain pressure against at least a part of the first side. According to an example, the lid part is pressed against the external element by means of the extension element part when it, after activation of the vehicle safety device actuator, moves towards the second side of the lid part and engage said second side in such a way that the external element is enabled to depress the part of the lid part that it contacts, such that the engaging means disengage the housing.

According to another example, at least a part of the first side of the lid follows a convex curve shape such that a central part of the first side is closest to the external element when the vehicle safety device actuator is mounted. Preferably, the engaging means disengage the housing when the external element applies a certain pressure against at least a part of the first side due to a change of at least a part of the convex curve shape to a concave curve shape, the disengaging means then being bent away from the housing.

According to another example, the extension element part is in the form of a piston or an airbag.

According to another example, when the vehicle safety device actuator is mounted, the external element is positioned at a first distance from the first side of the lid, the housing comprising an axially extending slot arrangement into which the engaging means may slide along a second distance.

Other examples are disclosed in the dependent claims. A number of advantages are provided by means of the present invention. For example:

- A reliable and uncomplicated way to secure a vehicle safety device actuator; _Λ

4

- Safe handling, mounting and service of the vehicle safety device actuator; and

- Normal functionality in the event of a collision. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described more in detail with reference to the appended drawings, where:

Figure 1 shows a schematic side view of a pyrotechnic actuator according to a first and second example of the present invention;

Figure 2 shows a schematic cross-sectional side view of a pyrotechnic actuator according to a first example of the present invention in a first position;

Figure 3 shows a schematic cross-sectional side view of a pyrotechnic actuator according to a first example of the present invention in a second position;

Figure 4 shows a schematic cross-sectional side view of a pyrotechnic actuator according to a first example of the present invention in a third position;

Figure 5 shows a schematic cross-sectional side view of a pyrotechnic actuator according to a first example of the present invention in a fourth position;

Figure 6 shows a schematic cross-sectional side view of a pyrotechnic actuator according to a second example of the present invention in the fourth position; Figure 7 shows a schematic side view of a pyrotechnic actuator according to a third example of the present invention ; Figure 8 shows a schematic cross-sectional side view of a pyrotechnic actuator according to the third example of the present invention in a first position;

Figure 9 shows a schematic side view of a pyrotechnic actuator according to a fourth example of the present invention ;

Figure 10 shows a schematic cross-sectional side view of a pyrotechnic actuator according to the fourth example of the present invention in a first position;

Figure 11 shows a schematic cross-sectional side view of a pyrotechnic actuator according to the fourth example of the present invention in a second position;

Figure 12 shows a schematic cross-sectional side view of a pyrotechnic actuator according to the fourth example of the present invention in a third position; and Figure 13 shows a schematic cross-sectional side view of a pyrotechnic actuator according to a fifth example of the present invention in the third position.

Detailed description

Figure 1 and Figure 2, Figure 2 showing a cross-section view of Figure 1, show a first example of a pyrotechnic actuator 1 comprising a circular housing 2 and a piston 3 which is movable in the housing 2, the piston 3 being shown in a rest position. The housing 2 further comprises a pyrotechnic device 4, which is arranged for connection to a vehicle control unit (not shown) . The housing 2 has a first end 2a and a second end 2b, where the pyrotechnic device 4 is placed at the first end 2a and where the piston 3 is arranged to move towards, and through, an opening 5 at the second end 2b when the pyrotechnic device 4 is activated as will be described later.

When mounted, the pyrotechnic actuator 1 is arranged to affect a hood lifting element 6 connected to a vehicle hood 7, when the pyrotechnic actuator 1 is actuated. The pyrotechnic actuator 1 is in this example arranged to be a part of a hood lifting arrangement.

According to the present invention, the pyrotechnic actuator 1 comprises a lid 8 which is mounted at the opening 5 in the housing 2. The lid 8 comprises a plurality of engaging hooks 9 which are engaging a circumferentially running slot 10 in the housing 2. For reasons of clarity, only a first engaging hook 9a and a second engaging hook 9b are shown in the cross- sectional Figure 2. For the same reason, only a first engaging hook and a second engaging hook are shown in the cross- sectional Figures 3-6 and 8-12. It is to be understood that the hooks 9 run circumferentially, mainly evenly distributed. The lid comprises a first side 8a, facing away from the opening 5 and a second side 8b, facing the opening 5 when the lid 8 is mounted. When the pyrotechnic actuator 1 is mounted, the hood lifting element 6 is in a rest position relatively close to the first side 8a of the lid 8, the first side 8a following a convex curve shape such that the central part of the first side 8a is closest to the hood lifting element 6. Figure 1 and Figure 2 also illustrate the pyrotechnic actuator 1 during transport and handling, and in that case the hood lifting element 6 is of course not present. With reference to Figure 3, the pyrotechnic actuator 1 is activated in its mounted position, the pyrotechnic device 4 being detonated, which is illustrated with an explosion symbol 11. The explosion and the released gases force the piston 3 to move towards, and through, the opening 5 the second end 2b such that an engaging part 3a of the piston 3 engages the second side 8b of the lid, pressing the lid towards the hood lifting element 6. The engaging part 3a has an engaging surface shape that mainly is concave, such that during engagement, the convex shape of the lid 8 is turned to a concave shape. During this deformation of the lid 8, the engaging hooks 9a, 9b are bent outwardly, away from the circumferentially running slot 10, which is indicated with respective arrows Al, A2. During the movement of the piston 3, the engaging hooks 9a, 9b are continuously bent outwardly such that they are released from the circumferentially running slot 10.

With reference to Figure 4, the engaging hooks 9a, 9b have been released from the circumferentially running slot 10, and the lid has followed in the continued movement of the piston 3, being sandwiched between the engaging part 3a of the piston 3 and the hood lifting element 6, the hood lifting element 6 lifting the hood 7 in a previously known manner, not shown in more detail here.

With reference to Figure 5, the pyrotechnic actuator 1 is activated in an un-mounted position, for example during transport, storage or service. Figure 5 is marked with "Section A-A", but it is to be noted that the hood lifting element 6 and the hood 7 are omitted here. It is assumed that the pyrotechnic device 4 has been detonated unintentionally, the detonation being indicated with is illustrated with an explosion symbol 17. The explosion 17 and the released gases force the piston 3 to move towards the lid such that the engaging part 3a of the piston 3 engages the second side 8b of the lid, pressing against the lid 8.

Since there is no part on the first side of the lid against which the lid may be pressed, the convex shape of the lid 8 is enhanced during engagement. During this deformation of the lid 8, the engaging hooks 9a, 9b are bent inwardly, towards the circumferentially running slot 10, which is indicated with respective arrows A3, A4. In this way, the lid is more and more locked to the housing 2 the more the piston 3 presses against the second side 8b of the lid 8. The piston is thus prevented from leaving the housing 2, and a possible accident due to the unintentional activation may be avoided. Figure 6 shows a second example of the pyrotechnic actuator 1' in a similar view as in Figure 5. Here, an intentional material weakness has been incorporated in the housing 2', the weakness being in the form of a thinner part of a side wall, which is indicated by an outwardly bent wall piece 12. In this way, when the cylinder moves following the explosion and is prevented from leaving the housing by the lid 8 as described above, a gas pressure has been built up in the housing 2 ' . It is here to understood that the Figures are of a schematic nature, and that the play between the cylinder 3 and the housing 2 ' is smaller than shown, offering quite small escaping possibilities for the expanding gases.

The thinner part of the wall 12 is, as shown, forced open such that the internal pressure is relieved, as indicated with an arrow A5. The thinner part of the wall 12 should be designed such that it is not affected by a normal activation of the pyrotechnic actuator 1' in its mounted position. With reference to Figure 7 and Figure 8, Figure 8 showing a cross-section of Figure 7, a third example of the pyrotechnic actuator 1' ' is shown. The pyrotechnic actuator 1' ' is shown in a mounted rest position. In this case, the hood lifting element 6 that is connected to the vehicle hood 7 is positioned at a first distance Dl from the lid 8'' . The housing 2'' comprises axially extending slots 13, 14, substituting the circumferentially running slot 10, into which elongated engaging hooks 9' ' ; 9a' ' , 9b' ' may slide along a second distance D2. The second distance D2 preferably exceeds the first distance Dl in order to allow the lid 8'' to reach the hood lifting element 6 in the event of an actuation, such that the lid 8'' may be released as described previously. The axially extending slots 13, 14 have an axial length that constitutes a third distance D3, the third distance D3 containing the second distance D2 and space for the engaging hooks 9a' ' , 9b" .

When mounting the lid to the housing, the lid 8'' should be oriented such that the engaging hooks 9a' ' , 9b' ' are fitted into the respective axially extending slot 13, 14. Alternative, the axially extending slots 13, 14 may be substituted by a circumferentially running slot having a height that corresponds to the third distance D3. With reference to Figure 9 and Figure 10, Figure 10 showing a cross-section of Figure 9, a fourth example of the pyrotechnic actuator ' ' ' is shown. The pyrotechnic actuator ' ' ' is shown in a mounted rest position. In this case, the pyrotechnic actuator i' ' ' comprises an airbag 15 which is schematically shown in a folded position in the housing. The airbag 15 is in connection with a pyrotechnic device 16 that is arranged to inflate the airbag 15 when detonated. Since there is no hood lifting element present in the case where the pyrotechnic actuator i' ' ' comprises an airbag 15, there is a need for a lid counter-pressing element 21. Here, such a counter-pressing element 21 is positioned in a rest position relatively close to the first side 8a of the lid 8, mainly in the same way as the previously described hood lifting element.

With reference to Figure 11, the pyrotechnic actuator ' ' ' is activated in an un-mounted position, for example during transport, storage or service. Figure 11 is marked with "Section C-C", but it is to be noted that Figure 11 is limited to the pyrotechnic actuator ' ' ' only. It is assumed that the pyrotechnic device 16 has been detonated unintentionally, the detonation being indicated with an explosion symbol 18. The explosion 18 and the released gases inflate the airbag 15 towards the lid 8 such that the second side 8b of the lid is engaged by the inflating airbag which presses against the lid 8.

Since there is no part on the first side of the lid against which the lid may be pressed, the convex shape of the lid 8 is enhanced during engagement. During this deformation of the lid 8, the engaging hooks 9a, 9b are bent inwardly, towards the circumferentially running slot 10, which is indicated with respective arrows A6, A7 s in the previous example with reference to Figure 5.

The airbag 15 is thus prevented from leaving the housing 2, and a possible accident due to the unintentional activation may be avoided. In Figure 12, the lid counter-pressing element 21 is positioned in a rest position relatively close to the first side 8a of the lid 8, in the same way as the previously described hood lifting element in order for the lid 8 to flip from a convex to a concave shape and be released, as will be described below.

The pyrotechnic actuator ' ' ' has activated, the pyrotechnic device 16 being detonated, the detonation being indicated with an explosion symbol 22. The inflating airbag 15 engages the second side 8b of the lid, pressing the lid 8 towards the counter-pressing element 21 which is attached such that it provides sufficient counter-pressure for the lid 8 to flip from a convex to a concave shape and be released, in the same way as shown in Figure 4. In this case, counter-pressing element 21 may follow the airbag 15 during inflation, or fall of, depending on how it is attached.

Figure 13 shows a fifth example of the pyrotechnic actuator ]_'''' in a similar view as in Figure 11. Here, an intentional material weakness has been incorporated in the housing 2 ' ' ' ' and in the airbag 19, the weakness in the housing 2 ' ' ' ' being in the form of a thinner part of a wall, which is indicated by an outwardly bent wall piece 20, and the weakness in the airbag 19 being in the form of a weakened seam (not explicitly indicated) . In this way, the gas pressure that has been built up due to the unintentional detonation 18 may be relieved, as indicated with an arrow A8, in a similar way as described with reference to Figure 6.

The thinner part of the wall 20 and the weakened seam should be designed such that it is not affected by a normal activation of the pyrotechnic actuator ' ' ' ' j__n its mounted position . „

12

The general idea of the present invention is that the lid part is released from the housing when the lid part is subject to a first force against the first side such that the lid part flips from an at least partly convex shape to an at least partly concave shape and is released.

The first force is acting on the first side by means of the external element being pressed against the first side of the lid part, preferably against a central part of the lid part. The external element itself does not move towards the first side, but the lid part is pressed against the external element such that the external element may apply the first force on the first side.

In the examples described, the lid part is pressed against the external element by means of an extension element part, such as a piston or an airbag, that moves towards the second side of the lid part in such a way that the external element still is allowed to depress the part of the lid part that it contacts such that the lid part flips according to the above.

For example, in the case of a piston acting as an extension element part, the engaging part of the piston is shaped accordingly, and in the case of an airbag acting as an extension element part, it exerts a pliable pressure on the second side of the lid, most force acting on an area on the second side surrounding an area on the first side where the where there the external element contacts the lid part. It is of course conceivable that the airbag presses a suitably shaped piston part or similar against the second side of the lid. The present invention is not limited to the examples described above, but may vary freely within the scope of the appended claims. For example, the pyrotechnic actuator may comprise other types of extension element parts such as the described piston and airbag.

The lid functions as a securing lid and is generally constituted by a lid part. The parts used may be made in any suitable material.

The hood lifting element 6 and the lid counter-pressing element 21 generally constitute an external element. The external element is arranged to apply a counter-pressure on an activating zone on the lid part in order to flip the lid part from a convex to a concave shape and be released. The activating zone is preferable a central zone of the lid part, more in detail a central part having less than half the area of the first side 6a.

The engaging hooks 9 may have any suitable shape, and may be of any suitable number while maintaining their desired function. For example, the hooks may be in the form of one rim that extends circumferentially, having an indent that engages the slot. The engaging hooks are generally constituted by engaging means .

The case where the housing comprises axially extending slots, an axially extending slots or similar, as described with reference to Figure 7 and Figure 8, is applicable for all examples of the present invention.

The circumferentially running slot 10 may be divided into separate slot parts. Generally, the slot or slots used in the housing constitute a slot arrangement. The case with at least one incorporated material weakness intended for reliving gas pressure at an unintentional activation of the pyrotechnic actuator is also applicable for all examples of the present invention. The pyrotechnic actuator is generally constituted by a vehicle safety device actuator, which not necessarily is pyrotechnically driven. For example, either one of a spring arrangement or compressed gas arrangement is conceivable. The first side 8a preferably follows a general convex curve shape such that the central part of the first side 8a is closest to the hood lifting element 6. However, the convex curve shape may be constituted by straight parts. For example, a peripheral part may have an inclination that extends away from the housing when the lid part 8 is mounted to the housing 2, and a central part, being closest to the hood lifting element 6, that is flat. The peripheral part then constitutes a ring surrounding the circular central part. However, the lid part 8 and the housing 2 do not have to have a circular cross-sectional shape, but may alternatively have an oval, square or polygonal cross-sectional shape. The shape of the lid part 8 is adapted to the shape of the housing 2.

Claims

1. A vehicle safety device actuator (1) comprising a housing (2) and an extension element part (3), at least a part of the extension element part (3) being arranged to move towards an opening (5) at a first end (2a) of the housing (2) when the vehicle safety device actuator (1) is activated, characterized in that the vehicle safety device actuator (1) comprises a lid part (8) having a first side (8a), facing away from the opening (5) and a second side (8b), facing the opening (5) when the lid part (8) is mounted to the housing

(2) , which lid part (8) in turn comprises engaging means (9; 9a, 9b) arranged to engage the housing (2), where the engaging means (9; 9a, 9b) are arranged to disengage the housing (2) when an external element (6) applies a certain pressure against at least a part of the first side (8a) .

2. A vehicle safety device actuator according to claiml, characterized in that the lid part (8) is pressed against the external element (6) by means of the extension element part

(3) when it, after activation of the vehicle safety device actuator (1), moves towards the second side (8b) of the lid part (8) and engage said second side (8b) in such a way that the external element (6) is enabled to depress the part of the lid part (8) that it contacts, such that the engaging means (9; 9a, 9b) disengage the housing (2) .

3. A vehicle safety device actuator according to any one of the claimsl or 2, characterized in that at least a part of the first side (8a) of the lid part (8) follows a convex curve shape such that a central part of the first side (8a) is closest to the external element (6) when the vehicle safety device actuator (1) is mounted.

4. A vehicle safety device actuator according claim 3, characterized in that the engaging means is arranged to disengage the housing (2) when the external element (6) applies a certain pressure against at least a part of the first side (8a) due to a change of at least a part of the convex curve shape to a concave curve shape, the disengaging means (9; 9a, 9b) then being bent away from the housing (2) .

5. A vehicle safety device actuator according to any one of the previous claims, characterized in that the extension element part (3) is in the form of a piston.

6. A vehicle safety device actuator according claim 5, characterized in that an engaging part (3a) of the piston (3) that is arranged to engage said second side (8b) has an engaging surface shape that mainly is concave.

7. A vehicle safety device actuator according to any one of the previous claims 1-4, characterized in that the extension element part (15, 19) is in the form of an airbag.

8. A vehicle safety device actuator according claim 7, characterized in that the airbag (19) comprises a weakened seam that is arranged to open if the vehicle safety device actuator {!'''') is activated without the engaging means (9; 9a, 9b) disengaging the housing {2'''') .

9. A vehicle safety device actuator according to any one of the previous claims, characterized in that the housing (2', 2'''') comprises a weakness (12, 20) in a side wall, the weakness (12, 20) being arranged to break such that a connection is formed through said side wall the housing (2', 2'''') if the vehicle safety device actuator (1', 1' ' ' ' ) is activated without the engaging means (9; 9a, 9b) disengaging the housing (2' , 2' ' ' ' ) .

10. A vehicle safety device actuator according claim 9, characterized in that the weakness (12, 20) is in the form of a part of said side wall having a reduced wall thickness.

11. A vehicle safety device actuator according to any one of the previous claims, characterized in that when the vehicle safety device actuator (1'') is mounted, the external element (6) is positioned at a first distance (Dl) from the first side of the lid (8''), the housing (2'') comprising an axially extending slot arrangement (13, 14) into which the engaging means (9''; 9a'', 9b'') may slide along a second distance (D2) when the vehicle safety device actuator (1'') is activated.

12. A vehicle safety device actuator according claim 11, characterized in that the second distance (D2) exceeds the first distance (Dl) .

13. A vehicle safety device actuator according to any one of the claims 11-12, characterized in that the axially extending slot arrangement (13, 14) has an axial length that constitutes a third distance (D3) , the third distance (D3) containing the second distance (D2) and space for the engaging means (9a" , 9b" ) .