Frontal type safety airbag for motor vehicles

Abstract

The invention relates to a frontal airbag (10) for a motor vehicle, said airbag comprising a housing (11) designed to be housed inside the hub (5) of the steering wheel (3) of said vehicle, a gas generator (13) housed in said housing (11), and an airbag (12) housed in its folded state inside said housing and capable of deploying behind said steering wheel. The airbag further comprises a support airbag (14) housed in its folded state inside said housing and capable of deploying, simultaneously with said airbag (12), above said steering wheel. The support airbag (14) is further shaped so as to come into contact, in its deployed configuration, with the upper portion of said airbag (12) in its deployed configuration, thereby providing counter-support on this upper portion. Figure to be published with the abbreviation: Fig. 3

Description

Title of the invention: Frontal type safety airbag for motor vehicles technical field

[0001] The invention relates generally to safety airbags commonly referred to by the English name "airbag".

[0002] It relates in particular to such a safety airbag intended to be mounted in the hub of the steering wheel of a motor vehicle and configured to deploy in the event of a frontal collision to protect the driver of that vehicle. Prior art

[0003] Motor vehicles conventionally include a steering wheel operated by the driver and fixed to the top of a steering column to exert a rotation transmitted to a steering box located at its lower end, this box applying a steering angle to the two front wheels to ensure the direction of the vehicle.

[0004] The steering wheel generally includes in its central, bowl-shaped hub a frontal-type safety airbag.

[0005] Such a safety airbag conventionally comprises a casing, a gas generator housed in said casing and operable via an electronic computer connected to sensors for detecting shocks suffered by the vehicle, and a safety airbag housed in the folded state inside said casing and fluidly connected to said gas generator.

[0006] In the event of a violent frontal impact, particularly during an accident, the bag is suddenly pressurized by the gas generator and deploys behind the steering wheel in the passenger compartment of the vehicle to cushion the impact and protect the driver's torso, especially his head.

[0007] It should be noted that the counter-pressure exerted by the steering wheel on the bag deployed at the moment of impact with the driver's torso prevents the bag from moving towards the windshield and therefore greatly contributes to the cushioning of the shock.

[0008] For stylistic reasons, some motor vehicles are equipped with a steering wheel having a small diameter gripping and driving rim or without an upper spoke, which prevents the latter from exerting counter-pressure on a part of the airbag in deployed configuration and in particular its upper portion intended to receive the driver's head.

[0009] This instability of the upper portion of the airbag in the deployed configuration thus causes a loss of cushioning at the level of the head, resulting in a significant increase in the risk of injury to the driver.

[0010] In order to overcome this problem, the US patent document 2019 / 0161044 Al proposes to add to the safety airbag implanted in the steering wheel hub, a second support airbag implanted in the steering column of the vehicle and comprising an airbag configured to deploy upwards and backwards until it comes into contact with the upper portion of the airbag of the safety airbag.

[0011] The airbag of this second support airbag thus makes it possible to exert counter-pressure on the upper portion of the airbag of the safety airbag, so as to ensure more effective protection of the head of the driver of the vehicle.

[0012] The addition of such a support airbag unfortunately leads to a significant increase in the cost of production of the vehicle.

[0013] Furthermore, the installation of such a second support airbag is not feasible in vehicles equipped with a retractable steering column in the event of pressure being exerted against the steering wheel exceeding a predetermined threshold.

[0014] Such a retraction movement of the steering column would indeed cause a pinching of the airbag of this support cushion which could cause it to tear and / or disrupt the continuation of the retraction of this steering column. Description of the invention

[0015] The present invention therefore aims to improve the situation.

[0016] For this purpose, it proposes a front-type safety airbag for a motor vehicle, said airbag comprising a housing intended to be housed inside the hub of the steering wheel of said vehicle, a gas generator housed in said housing, and a safety airbag housed in the folded state inside said housing and fluidly connected to said gas generator, said safety airbag being capable of deploying at the rear of said steering wheel by passing through said housing at the level of a first exit opening provided on its rear face; characterized in that it further comprises a support airbag housed in its folded state inside said casing and fluidly connected to said gas generator, said support airbag being capable of deploying, simultaneously with said safety airbag, above said steering wheel by passing through said casing at a second exit opening provided on its upper face, said support airbag being further shaped so as to come, in its deployed configuration, into contact with the upper portion of said airbag in deployed configuration so as to exert a counter-support function on this upper portion.

[0017] The safety airbag according to the invention thus makes it possible to ensure more effective protection of the driver's head for vehicles equipped with a steering wheel having a gripping and driving rim of small diameter or without an upper spoke.

[0018] With a reasonable additional cost compared to a conventional frontal airbag since it does not require the addition of an extra generator, the airbag according to the invention also has the advantage of being able to be installed in vehicles equipped with a retractable steering column.

[0019] According to preferred characteristics of said safety airbag according to the invention: - said inflatable support bag is also shaped so that, in its deployed configuration, it rests on the top of the hub of said steering wheel; - said airbag support is shaped to present, in its deployed configuration, a boot shape comprising a leg intended to rest against the upper portion of said airbag, and a protruding foot at the front of said leg intended to bear against the top of the hub of said steering wheel and also on at least a portion of the top of the steering column of said vehicle; - said inflatable support bag comprises a central annular piece of fabric on the peripheral edges of which two lateral pieces of fabric are attached by sewing so as to present, in its deployed configuration, a substantially constant cross-section over its entire width; - said inflatable support bag is shaped so that, in its deployed configuration, it rests against the windshield of said vehicle; - said airbag also includes a guide element fixedly mounted inside said casing at its upper rear corner and forming a ramp extending diagonally between the first and second exit openings so as to guide the deployment of said airbags out of this casing; - said guiding element is made of a composite material or of a polypropylene foam having a density greater than or equal to 60 kg / m3; and / or - said airbag safety and said airbag support are each provided with at least one respective inflation port fluidically connected to the outlet of said gas generator by a corresponding conduit. The invention also relates, in a second aspect, to a steering wheel for a motor vehicle comprising a gripping and drive rim and a hub hollow integral with said rim, characterized in that it also includes such an airbag safety cushion housed in said hub.

[0020] The invention finally relates, in a third aspect, to a motor vehicle, characterized in that it comprises such a steering wheel. Brief description of the drawings

[0021] The description of the invention will now be continued by a detailed description of an exemplary embodiment, given below by way of illustration but not limitation, with reference to the accompanying drawings, on which:

[0022] [Fig.1] represents an axial cross-sectional view of a steering assembly comprising a steering wheel mounted on a steering column and a driver safety airbag according to the invention housed in the hub of this steering wheel;

[0023] [Fig.2] is an axial cross-sectional view of the steering assembly of [Fig.1] illustrating an intermediate stage of the deployment of the safety airbag according to the invention; and

[0024] [Fig. 3] shows an axial cross-sectional view of the steering assembly of [Fig. 1] after the complete deployment of the safety airbag according to the invention. Description of embodiments

[0025] The steering assembly 1 schematically represented in figures 1 to 3 essentially comprises a steering column 2 capable of being driven in rotation around its axis by a steering wheel 3 mounted at its top.

[0026] This steering column 2 rotates on bearings arranged inside a barrel or similar (not shown), allowing the steering assembly 1 to be mounted on the vehicle chassis in a way that is in itself conventional and therefore does not need to be described here.

[0027] The steering wheel 3 usually comprises a gripping and driving rim 4 without an upper spoke, and a hollow central hub 5 integral with the rim 4 and covered by an external cap 6.

[0028] The steering assembly 1 also includes a driver's front-type safety airbag 10 according to the invention, housed in its undeployed configuration inside the hub 5 of the steering wheel 3, so as to be concealed from the eyes of the vehicle's passengers by the outer cover 6.

[0029] In the description that follows and by convention, the terms "lower", "upper", "front" and "rear" will be defined in relation to the mounting position of the safety airbag 10 in the passenger compartment of the motor vehicle.

[0030] With reference to [Fig.1], this airbag 10 conventionally comprises a generally cylindrical housing 11 containing an airbag 12 in the folded state (this state being obtainable by folding, rolling or compression) as well as a gas generator 13 comprising a rigid pyrotechnic cartridge containing reagents enabling the generation of gas and an electrically controlled trigger.

[0031] The gas generator 13 includes at one of its ends an electrical connector, not shown, protruding outside the housing 11 and allowing the trigger to be electrically connected to the vehicle's electrical network in order to control the safety airbag 10.

[0032] According to the invention, the safety airbag 10 also includes a support airbag 14 housed in the folded state in the casing 11.

[0033] The safety airbag 12 and the support airbag 14 are each provided with at least one respective inflation port fluidically connected to the outlet of the gas generator 13 by a corresponding conduit.

[0034] The housing 11 has a first exit opening 15 provided on its rear face located opposite the external cover 6 of the steering wheel 3 so as to allow the deployment of the safety airbag 12 behind this steering wheel 3.

[0035] This housing 11 also has a second outlet opening 16 provided on its upper face so as to allow the deployment of the support airbag 14 above the steering wheel 3.

[0036] The safety airbag 10 further includes a guide element 17 fixedly mounted inside the housing 11 at its upper rear corner and forming a ramp extending diagonally between the two exit openings 15, 16 so as to guide the deployment of the two airbags 12, 14 out of this housing 11.

[0037] This guide element 17 is advantageously made of a composite material or of a polypropylene foam having a density greater than or equal to 60 kg / m3 and preferably equal to 80 kg / m3.

[0038] When the safety airbag 10 is triggered by the emission of an electrical signal generated during a frontal or oblique collision of the vehicle with another vehicle or an obstacle such as, for example, a pole, the gas generator 13 sends pressurized gas into the two airbags 12, 14 which deploy simultaneously outside the housing 11 by passing through respectively the first exit opening 15 and the second exit opening 16.

[0039] More specifically and with reference to [Fig.2], the safety airbag 12 is configured to deploy behind the steering wheel 3 by spreading its outer cover 6, while the support airbag 14 is configured to deploy above the steering wheel 3.

[0040] Fig. 3 shows the two airbags, safety 12 and support 14, in their deployed configuration.

[0041] On this [Fig.3], it can be noted that the upper portion of the safety airbag 12 extends clearly above the steering wheel 3, which therefore cannot act as a counter-support for this portion of the bag 12.

[0042] Still with reference to this [Fig.3], it can be noted that this counter-support function for this upper portion of the safety airbag 12 is, on the other hand, ensured by the support airbag 14 which is shaped to come in its deployed configuration into contact with the latter by also taking support on the top of the hub 5 of the steering wheel 3.

[0043] The inflatable support bag 14 is advantageously made up of a central annular piece of fabric on the peripheral edges of which two lateral pieces of fabric are attached by sewing so as to present, in its deployed configuration, a substantially constant cross-section over its entire width.

[0044] Such a conformation, commonly referred to as "three-dimensional" or "self-supporting", allows for better support of the inflatable support bag 14 in deployed configuration, but also optimizes the contact surface between this inflatable bag 14 and the safety inflatable bag 12.

[0045] In order to further optimize the holding of the support airbag 14, the latter is advantageously shaped to present, in deployed configuration, a boot shape comprising a leg 14A intended to rest against the upper portion of the safety airbag 12, as well as a foot 14B projecting forward of the leg 14A and intended to bear not only on the top of the hub 5 of the steering wheel 3 but also on at least a portion of the top of the steering column 2.

[0046] According to alternative embodiments not shown, it is possible to envisage, always with the aim of obtaining a better hold of this support airbag 14, that the latter be shaped to bear against the windshield of the vehicle in its deployed configuration.

[0047] Such a configuration will not however be preferred because of the risk of breakage of the windshield due to the pressure exerted by the support airbag 14 against this windshield in the event of the deployment of the safety airbag according to the invention.

[0048] Finally, it should be noted that the present invention is not limited to the embodiments described and represented, but also encompasses all variants of execution within the reach of a person skilled in the art.

Claims

Demands

1. Frontal type safety airbag (10) for motor vehicle, said airbag (10) comprising a housing (11) intended to be housed inside the hub (5) of the steering wheel (3) of said vehicle, a gas generator (13) housed in said housing (11), and a safety airbag (12) housed in the folded state inside said housing (11) and fluidly connected to said gas generator (13), said safety airbag (12) being capable of deploying at the rear of said steering wheel (3) by passing through said housing (11) at the level of a first exit opening (15) provided on its rear face;characterized in that it further comprises a support airbag (14) housed in the folded state inside said casing (11) and fluidly connected to said gas generator (13), said support airbag (14) being capable of deploying, simultaneously with said safety airbag (12), above said steering wheel (3) by passing through said casing (11) at the level of a second exit opening (16) provided on its upper face, said support airbag (14) further being shaped so as to come, in its deployed configuration, into contact with the upper portion of said safety airbag (12) in deployed configuration so as to exert a counter-support function on this upper portion and also to bear on the top of the hub (5) of said steering wheel (3);said airbag support (14) is shaped to present, in its deployed configuration, a boot shape comprising a leg (14A) intended to rest against the upper portion of said safety airbag (12), and a foot (14B) projecting from the front of said leg (14A) and intended to bear against the top of the hub (5) of said steering wheel (3) and also on at least a portion of the top of the steering column (2) of said vehicle.

2. Safety airbag (10) according to claim 1, characterized in that said support airbag (14) comprises a central annular piece of fabric on the peripheral edges of which two lateral pieces of fabric are attached by stitching so as to present, in its deployed configuration, a substantially constant cross-section over its entire width.

3. Safety airbag (10) according to any one of claims 1 to 2, characterized in that said support airbag (14) is shaped so that, in its deployed configuration, it would come to rest against the windshield of said vehicle.

4. Safety airbag (10) according to any one of claims 1 to 3, characterized in that it also comprises a guide member (17) fixedly mounted inside said housing (11) at its rear upper corner and forming a ramp extending diagonally between the first and second exit openings (15, 16) so as to guide the deployment of said airbags (12, 14) out of this housing (11).

5. Safety airbag (10) according to claim 4, characterized in that said guide member (17) is made of a composite material or of a polypropylene foam having a density greater than or equal to 60 kg / m3.

6. Safety airbag (10) according to any one of claims 1 to 5, characterized in that said safety airbag (12) and said support airbag (14) are each provided with at least one respective inflation port fluidically connected to the outlet of said gas generator (13) by a corresponding conduit.

7. Steering wheel (3) for a motor vehicle comprising a gripping and driving rim (4) and a hollow hub (5) integral with said rim (4), characterized in that it also comprises a safety airbag (10) according to any one of claims 1 to 6 housed in said hub (5).

8. Motor vehicle, characterized in that it comprises a steering wheel (3) according to claim 7.

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