GB2369772A

GB2369772A - Motor vehicle safety seat arrangement

Info

Publication number: GB2369772A
Application number: GB0029931A
Authority: GB
Inventors: Patrick John Mulherin
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2000-12-08
Filing date: 2000-12-08
Publication date: 2002-06-12
Anticipated expiration: 2020-12-08
Also published as: GB2369772B; GB0029931D0

Abstract

A motor vehicle 1 has a specially adapted seat assembly 8 which has an attachment means 15 including a front support structure 16. A safety device in the form of an explosive bolt 23 is supported on structure 16 and is also used to hold the front of the seat assembly (108, fig 7) in position. In the event that the motor vehicle is involved in a serious collision at least one sensing means will actuate an electronic control means (fig 5) and an explosive bolt 23 is detonated. Seat assembly 8 is released and moves along slide rail 14, the front portion of which has a recess 41. A shaft forming part of the front support structure 16 drops in to recess 41 as the seat assembly (108) moves forward. As a result, the front of the seat assembly (108) is caused to move downwardly and rotate forwardly about a pivot axis which is defined by a position of abutment between a leaf spring 28 which supports the rear of the seat assembly (108), and the upper surface of the slide rail 14. Such motion of seat assembly 108, in addition to safety belt sensor arrangement 19, 20, 36 and an air bag sensor arrangement 18 reduce the contact between the head of the occupant and cross-rail 5 (which is part of the body structure 3) in the event of a serious collision.

Description

A Motor Vehicle

This invention relates to a motor vehicle and in particular to a safety seat arrangement for a motor vehicle.

It is well known to provide a motor vehicle with one or more seats attached to part of a body structure of the motor vehicle for use by an occupant of the vehicle.

It is further known to provide a motor vehicle with an airbag assembly to provide some protection to the occupant in the event of a serious collision for example see US patent number 4,620, 721.

It is well known to provide a motor vehicle with one or more safety belts to hold an occupant in position and resist forward movement of the occupant in the event of a serious collision. It has become increasingly popular in recent years to utilise a pyrotechnic pre-tensioner to take out any slack in the safety belt so as to maximise the performance of the safety belt in the event of a collision. Such a pyrotechnic pretensioner is shown in US patent number 6,139, 058.

In some motor vehicles, particularly those with a low roof line, it is a problem that, (in the event of a serious accident, ) if the occupant of the motor vehicle is not wearing a safety belt then the head of the occupant can contact a transverse member or crossrail defining an upper edge of a windscreen aperture. To try and minimise the risk of such contact it is known to attach the front seats of the motor vehicle by means of structure including a mechanical frangible fixing means in the form of shear pins. The shear pins being arranged to fail when a large load is applied to them so as to allow the front supports of the seat to collapse. This maximises the available distance between the cross-rail and the head of an occupant thereby reducing the risk of contact therebetween. However, it is difficult to design such shear pins to provide optimum performance for all occupants due to the large variation in occupant weight

that needs to be allowed for. For example, if the shear pins are designed to fail at the optimum load based upon a very light occupant then it is probable that they could fail during normal use due to fatigue if an occupant of maximum weight regularly occupies the seat. Similarly, if the shear pins are designed to fail at the optimum load based upon a very heavy occupant it is probable that they may not fail at all if the collision is not too severe.

It is therefore an object of this invention to provide a motor vehicle with an improved seating arrangement to overcome the problems described above.

According to the invention there is provided a motor vehicle having a body structure defining a passenger compartment, at least one seat for an occupant of the motor vehicle secured to part of the body structure by an attachment means within the passenger compartment, an electronic control means arranged to receive an input from at least one crash sensing means and to supply an actuation signal to a seat safety device forming part of the attachment means wherein when the input from the crash sensing means indicates that the vehicle is involved in a serious collision the control means is operable so as to send the actuation signal to the safety device thereby allowing at least part of the seat to move to a lower position.

The motor vehicle may further comprise at least one safety belt and a belt sensing means to provide a signal to the electronic control means indicative of whether the seat belt is in use, the electronic control means being arranged to send the actuation signal to the safety device only if the belt sensing means indicates that the safety belt is not in use.

The safety belt may be connected to a pyrotechnic pre-tensioner to apply a tension to the safety belt in response to a signal initiated by the electronic control means when the input from the sensing means indicates that the vehicle is involved in

a serious collision, the arrangement being such that the signal is only sent by the electronic control means if the safety belt sensing means indicates that the safety belt is in use.

Advantageously, the motor vehicle includes at least one airbag assembly actuated in response to a signal from the electronic control means when the input from the crash sensing means indicates that the vehicle is involved in a serious collision.

The seat may tilt forwardly upon actuation of the seat safety device, move in a forwardly direction upon actuation of the safety device or move forwardly and downwardly upon actuation of the seat safety device.

The seat safety device may include at least one explosively released fixing means which may be in the form of an explosive bolt.

The invention will now be described by way of example with reference to the accompanying drawings of which : Fig. 1 is a view of part of a motor vehicle according to the invention showing a first embodiment of a safety seat; Fig. 2 is a view in the direction of arrow"X"on Fig. 1 of the first embodiment of the safety seat; Fig. 3 is a close-up of the area"A"on Fig. 2 showing a safety device in a normal use condition; Fig. 4 is a view as shown in Fig. 3 but after the motor vehicle has been involved in a serious collision ;

Fig. 5 is a block diagram of an electronic control system forming part of a motor vehicle according to the invention; Fig. 6 is a flow chart showing some of the logic embedded in an electronic control unit forming part of the electronic control system shown in Fig. 5; Fig. 7 is a view of part of a motor vehicle according to the invention showing a second embodiment of a safety seat; Fig. 8 is a cross-section along the line P-P on Fig. 7 showing a safety device forming part of the second embodiment of a safety seat in a normal use condition; Fig. 9 is a view of part of a motor vehicle according to the invention showing a third embodiment of a safety seat; Fig. 10 is a close-up in the direction of arrow"Rt"on Fig. 9 showing a safety device forming part of the third embodiment of a safety seat in a normal use condition; Fig. 11 is a view of part of a motor vehicle according to the invention showing a fourth embodiment of a safety seat; Fig. 12 is a close-up in the direction of arrow"Q"on Fig. 11 showing a safety device forming part of the fourth embodiment of safety seat in a normal use condition; Fig. 13 is a view of part of a motor vehicle according to the invention showing a fifth embodiment of a safety seat; Fig. 14 is a cross-section on the line S-S on Fig. 13 showing a safety device forming part of the fifth embodiment of a safety seat in a normal use condition; and

Fig. 15 is a view of part of a motor vehicle according to the invention showing a sixth embodiment of a safety seat.

With particular reference to Figs. 1 to 6 there is shown a motor vehicle 1 having a body structure 3 defining a passenger compartment 2. The body structure 3 has a transverse member in the form of a cross-rail 5 defining the upper edge of an aperture in which is fitted a windscreen 6.

A seat assembly 8 is secured to a floor structure 7 by means of a pair of seat guide rails 12. The seat assembly 8 comprises a seat formed by a squab 9 and a backrest 10 pivotally connected together and an attachment means 15 used to connect the seat to the seat guide rails 12.

The attachment means 15 comprises a seat structure in the form of a seat pan 11 used to support the squab 9, a front support structure 16, a rear support structure 17 and a pair of slide rails 14 for sliding cooperation with the seat guide rails 12.

The front support structure 16 comprises a pair of spaced apart brackets 21 connected to the seat pan 11, a transversely extending support shaft 22 supported by the two brackets 21 and two safety devices 23 one at each end of the support shaft 22.

Each of the safety devices 23 comprises of an explosively releasable fixing means in the form of an explosive bolt. Each of the explosive bolts 23 has a shaft 24 with a threaded end portion for threaded engagement with a complimentary female thread form in the support shaft 22 and an actuator 25 containing a piston and an explosive charge (not shown). The actuator 25 has a pair of electrical connections in the form of wires 26 for connection of the actuator 25 to a source of electrical power. The rear support structure 17 comprises a pair of depending leaf springs 28 connected at one end to the seat pan 11 and in abut at a lower end thereof with an upper surface

of the slide rails 14 and a webbing tether 29 connecting the seat pan 11 to the floor structure 7.

The position of the seat is adjustable towards and away from the windscreen 6, the slide rails 14 sliding along the guide rails 12. Locking means (not shown) are provided to hold the seat in one of a number of pre-determined positions.

A control means in the form of a control system 30 is provided to control operation of the safety devices 23 and also any airbags 18 or safety belt pre-tensioners 20 fitted to the safety belts 19 of the motor vehicle 1.

The control system 30 comprises an electronic control unit 31, a crash detection signal processing unit 32 receiving inputs from a crash sensing means 33 and a vehicle speed sensor 35 and a safety belt sensing means 34.

The crash sensing means is in the form of an accelerometer 33 arranged to detect acceleration and deceleration of the motor vehicle 1 and send a signal indicative of the perceived acceleration to the signal processing unit 32. It will be appreciated that other means can be used to perform this task such as, for example, a contact switch or transducer arranged to send deformation of a front bumper of the motor vehicle. It is also envisaged that other means such as forward looking radar could also be used to provide a signal indicating that a serious collision is, or is about, to occur.

J".-, The signal processing unit 32 continuously receives a signal indicative of vehicle speed from the vehicle speed sensor 35 and monitors the output from the crash sensor 33. When the output from the crash sensor 33 indicates that a collision is occurring the signal processing unit 32 uses the input from the speed sensor 35 to determine whether the collision is serious. In general terms a collision at a vehicle

speed at or above 22. 5 kilometres per hour (14 miles per hour) is considered to be a serious collision.

If the collision is determined to be serious then the signal processing unit 32 indicates this to the electronic control unit 31. In practice the signal processing unit may form part of the electronic control unit itself but for ease of understanding they have been shown as separate entities on Fig. 5.

The electronic control unit 31 monitors the output from the safety belt sensing means which is in the form of a switch or proximity sensor 33 associated with a buckle 36 used to secure the safety belt 19 to the floor structure 7. If the safety belt is fastened to the buckle 35 then a corresponding output is generated which is supplied to the electronic control unit 31 to indicate that the seat belt is in use.

The electronic control unit 31 is connected on a output side to the safety devices 23, seat belt pre-tensioners 20 and airbags 18 fitted to the motor vehicle 1.

It will be appreciated that the output signals from the electronic control means 31 could be power signals having sufficient power to directly energise the safety devices 23, seat belt pre-tensioners 20 and airbags 18 or could be low power signals used to activate other devices (not shown or described) used to supply activation energy.

Operation of the electronic control unit 31 is as follows, when the input from the signal processing unit 32 indicates that a serious collision is occurring an activation signal is sent to the airbags 18 fitted to the motor vehicle 1 and either the safety devices 23 or the safety belt pre-tensioners 20 depending upon whether the safety belt sensing means 34 indicates that the safety belt 19 is in use.

It will be appreciated that in practice there will be safety devices 23 and a safety belt pre-tensioner 20 associated with both front seats of the motor vehicle but for ease

of understanding only one front seat with associated safety devices 23 and a seat belt pre-tensioner 20 are shown and described. The electronic control means would in practice control the safety devices and seat belt pre-tensioners of the two front seats separately depending upon whether the safety belts are in use.

If the safety belt 19 is in use then the electronic control unit 31 is operational to activate the safety belt pre-tensioner 20 so as to remove any slack from the safety belt 19 and no signal is sent to the safety devices 23.

If however, the safety belt 19 is detected not to be in use then the electronic control unit 31 is operational to send an actuation signal to the safety devices 23 but no signal to the safety belt pre-tensioner 20.

Receipt of the actuation signal by the safety devices 23 will cause the explosive charges in the actuators 25 to be detonated. This will result in a rapid movement of the pistons causing the threaded portions of the shafts 24 to fail due to the high tensile load applied to them by the explosion. The failure of the shafts 24 releases the support shaft 22 which is then able to move forwardly along guide ribs 40 into a recess 41 for abutment with an end stop 42. Prior to contact with the end stop 42 the webbing tether 29 becomes taut and acts as a shock absorber so as to reduce the impact of the shaft 22 against the end stop 42.

The forward motion of the seat is produced naturally by the force imparted thereto from the occupant undergoing rapid deceleration.

As the seat moves forwardly into the recess 41 it pivots forwardly about the two rear mounted leaf springs 28 and simultaneously the leaf springs 28 slide along the slide rails 14. This moves the centre of rotation of an occupant lower and forwardly

reducing the risk of contact with the cross-rail 5 and improving contact with the airbag 18.

With particular reference to Figs. 7 and 8 there is shown a second embodiment of a seat fitted to a motor vehicle according to the invention. Parts that are identical to those previously described with reference to the first embodiment of a seat are given the same reference numeral with the addition of 100.

A motor vehicle 101 has a body structure 103 defining a passenger compartment 102. The body structure 103 including a floor structure 107 to which is secured a seat assembly 108. The motor vehicle 101 has at least one airbag assembly and safety belts for the front seat occupants including pre-tensioners both controlled by an electronic control system for use in the event of a serious collision.

The seat assembly 108 is the same as that previously described with the exception of the attachment means used to attach the seat assembly 108 to the seat guide rails 112. The attachment means comprises a pair of slide rails 54, a pair of front support structures 51 and a pair of rear support structures 52. Only the slide rail 54 and support structures 51 and 52 on the left hand side of the seat assembly will be further described but apart from their location they are identical to those on the right hand side of the seat.

The front support structure 51 comprises a pair of spaced apart arms 55 pivotally connected at their upper ends to the seat pan 111 and joined together at their lower ends by a transverse shaft 57 engaged with a slot 58 in the slide rail 54 and a safety device in the form of an explosive bolt 59 connected to the slide rail 54 by a bracket 53. A slider 57A is mounted on the shaft 57 for sliding engagement with the slot 58.

During normal use the slider 57A is held up against a rear edge of the slot 58 by abutment against an end portion 59A of the explosive bolt 59.

The rear support structure 52 comprises a bracket 60 connected to the seat pan 111 and an upwardly extending flange 61 of the slide rail 54 which are pivotally connected together by means of a pivot pin 62.

Operation of the control system is as previously described and will not be further described. When the explosive bolts 59 receive an actuation signal from the control system indicating that actuation of the safety devices is required, the explosive bolts are detonated causing the end portions 59A of the explosive bolts 59 to break away.

The fracture of the explosive bolts 59 allows the slider 57A to move forwardly along the slot 58 causing rotation of the arms 55 about their upper ends in a clockwise direction as shown. This rotation reduces the distance between the front of the seat squab 109 and the floor 107 thereby lowering the front of the seat and causing the seat to tilt forwardly about the pivot pin 62.

No forward motion of the seat assembly can occur because the rear support structure 52 holds the seat firmly to the slide rail 54 which does not move.

With particular reference to Figs. 9 and 10 there is shown a third embodiment of a seat fitted to a motor vehicle according to the invention. Parts that are identical to those previously described with reference to the first embodiment are given the same reference numeral with the addition of 200.

A motor vehicle 201 has a body structure 203 defining a passenger compartment 202. The body structure 203 including a floor structure 207 to which is secured a seat assembly 208. The motor vehicle 201 has at least one airbag assembly and safety

belts for the front seat occupants including pre-tensioners both controlled by an electronic control system for use in the event of a serious collision.

The seat assembly 208 is the same as that previously described with the exception of the attachment means used to attach the seat assembly 208 to the seat guide rails 212.

The attachment means comprises a pair of slide rails 64, a pair of front support structures 71 and a pair of rear support structures 72. Only the slide rails 64 and the support structures 71 and 72 on the left hand side of the seat assembly 208 will be further described.

The front support structure 71 comprises a pair of spaced apart arms 65 rigidly connected at upper ends thereof to the seat pan 211 and joined together at lower ends thereof by a transverse shaft 67 engaged with an upwardly extending slot 68 in a flange 73 formed as part of the slide rail 64 and a safety device in the form of an explosive bolt 69 connected to one of the arms 65. During normal use the shaft 67 is held against the upper edge of the slot 68 by abutment of an end portion 69A of the explosive bolt 69 against an end face 73A of the flange 73. The rear support structure 72 comprises a bracket 80 connected to the seat pan 211 and an upwardly extending flange 81 of the slide rail 64 which are pivotally connected together by means of a pivot pin 82.

Operation of the control system is as previously described and will not be further described. When the explosive bolts 69 receive an actuation signal from the control system indicating that actuation of the safety devices is required the explosive bolts are detonated causing the end portions 69A to break away. This allows the shaft 67A to move downwardly in the slot 68 causing a reduction in the distance between the

front of the seat squab 209 and the floor 207 thereby lowering the front of the seat and causing the seat to tilt forwardly about the pivot pins 82.

No forward motion of the seat assembly 108 occurs as the rear support structure 72 holds the seat firmly to the slide rail 64 which does not move.

With particular reference to Figs. 11 and 12 there is shown a fourth embodiment of a seat fitted to a motor vehicle according to the invention. Parts that are identical to those previously described with respect to the first embodiment are given the same reference numeral with the addition of 300.

A motor vehicle 301 has a body structure 303 defining a passenger compartment 302. The body structure 303 including a floor structure 307 to which is secured a seat assembly 308. The motor vehicle 301 has at least one airbag assembly and safety belts for the front seat occupants including pre-tensioners both controlled by an electronic control system for use in the event of a serious collision.

The seat assembly 308 is the same as that previously described with the exception of the attachment means used to attach the seat assembly 308 to the seat guide rails 312.

The attachment means comprises a pair of slide rails 84, a pair of front support structures 91 and a pair of rear support structures 92. Only the slide rail 84 and the support structures 91 and 92 on the left hand side of the seat assembly 308 will be further described.

The front support structure 91 comprises a pair of arms 85A, 85B pivotally connected together by a pivot pin 87. One of the arms 85A is pivotally connected at an upper end to the seat pan 311 and the other arm 85B is pivotally connected at a lower

end to the slide rail 84. The lower arm 85B is"L"shaped and has an upwardly directed flange 83 to which is attached an explosive bolt 89.

During normal use the arms are held in the position shown by engagement of an end portion 89A of the explosive bolt 89 with an aperture in the upper 85A.

The rear support structure 92 comprises a bracket 93 connected to the seat pan 311 which is pivotally connected to the slide rail 84 by means of a pivot pin 94. Operation of the control system is as previously described and will not be further described.

When the explosive bolts 89 receive an actuation signal from the control system indicating that actuation of the safety devices is required the explosive bolts are detonated causing the end portions 89A to break away.

This failure of the explosive bolts 89 allows the two arms 85A, 85B to rotate relative to one another causing a reduction in the distance between the front of the seat squab 309 and the floor 307 thereby lowering the front of the seat and causing the seat to tilt forwardly about the pivot pins 94.

No forward motion of the seat assembly 308 occurs as the rear support structure 92 holds the seat firmly to the slide rail 84 which does not move.

With particular reference to Figs. 13 and 14 there is shown a fifth embodiment of a seat fitted to a motor vehicle according to the invention. Parts that are identical to those previously described with respect to the first embodiment are given the same reference numeral with the addition of 400.

A motor vehicle 401 has a body structure 403 defining a passenger compartment 402. The body structure 403 including a floor structure 407 to which is secured a seat

assembly 408. The motor vehicle 401 has at least one airbag assembly and safety belts for the front seat occupants including pre-tensioners both controlled by an electronic control system for use in the event of a serious collision.

The seat assembly 408 is the same as that previously described with the exception of the attachment means used to attach the seat assembly 408 to the seat guide rails 412.

The attachment means comprises a pair of slide rails 614, a pair of front support structures 611 and a pair of rear support structures 612. Only the slide rail 614 and the support structures 611 and 612 on the left hand side of the seat assembly 408 will be further described.

The front support structure 611 comprises an L-shaped arm 615 pivotally connected at an upper end thereof to the seat pan 411 and pivotally connected at a lower end to a flange 617 extending upwardly from the slide rail 614. An explosive bolt 619 is attached to the flange 617 and has an end portion 620 engaged with an aperture in the arm 615.

During normal use the arm 615 is held in the position shown by threaded engagement of the end portion 620 with the correspondingly threaded aperture in the arm 615.

The rear support structure 612 comprises a bracket 623 connected to the seat pan 411 and a pin 624 which is engaged with a slot 625 formed in part of the slide rail 614.

Operation of the control system is as previously described and will not be further ..' described.

When the explosive bolts 619 receive a signal from the control system indicating that actuation of the safety devices is required they are detonated causing the end portions 620 to break off. This allows the arm 615 to rotate relative to the flange 617 causing a reduction in the distance between the front of the seat squab 409 and the floor 407 thereby lowering the front of the seat and causing the seat to tilt forwardly about the pins 624 and move forwardly as the pins 624 slide along the slots 625.

With particular reference to Fig 15 there is shown a sixth embodiment of a seat fitted to a motor vehicle according to the invention which is in most respects the same as that described with reference to the fifth embodiment. The primary difference being that the rear support structure is different. Parts that are identical to those previously described with reference to the fifth embodiment are given the same reference numeral and will not be described again. The rear support structure 650 comprises an arm 651 pivotally connected at an upper end to the seat pan 411 and at a lower end of the flange 652 formed as part of the slide rail 618.

Operation of the control system is as previously described and will not be further described.

When the explosive bolts 619 receive a signal from the control system indicating that actuation of the safety devices is required they are detonated causing the end portion 620 to break away. This allows the arm 615 to rotate relative to the flange 617- causing reduction in the distance between the front of the seat squab 409 and the floor 107 and causes the seat to move forwardly, the arms 651 being free to rotate about their lower pivots.

Depending upon the respective orientation and lengths of the arms 615 and 651 the seat can move in various ways relative to the floor 407. It can move forwardly and downwardly or move forwardly and rotate in a forward direction.

Although the safety devices have been described herein as explosive bolts it will be appreciated that other fixing means that can be rapidly released in response to an electrical or electronic control signal could be used.

Claims

CLAIMS 1. A motor vehicle having a body structure defining a passenger compartment, at least one seat for an occupant of the motor vehicle secured to part of the body structure by an attachment means within the passenger compartment, an electronic control means arranged to receive an input from at least one crash sensing means and to supply an actuation signal to a seat safety device forming part of the attachment means wherein when the input from the crash sensing means indicates that the vehicle is involved in a serious collision the control means is operable so as to send the actuation signal to the safety device thereby allowing at least part of the seat to move to a lower position.
2. A motor vehicle as claimed in Claim 1 in which the motor vehicle further comprises at least one safety belt and a belt sensing means to provide a signal to the electronic control means indicative of whether the seat belt is in use, the electronic control means being arranged to send the actuation signal to the safety device only if the belt sensing means indicates that the safety belt is not in use.
3. A motor vehicle as claimed in Claim 2 in which the safety belt is connected to a pyrotechnic pre-tensioner to apply a tension to the safety belt in response to a signal initiated by the electronic control means when the input from crash sensing means indicates that the motor vehicle is involved in a serious collision, the arrangement being such that the signal is only sent by the electronic control means if the safety belt sensing means indicates that the safety belt is in use.
4. A motor vehicle as claimed in any of claims 1 to 3 in which the motor vehicle includes at least one airbag assembly actuated in response to a signal from the electronic control means when the input from the crash sensing means indicates that the vehicle is involved in a serious collision.
5. A motor vehicle as claimed in any preceding claim in which the seat tilts forwardly upon actuation of the seat safety device.
6. A motor vehicle as claimed in any of Claims 1 to 4 in which the seat moves in a forwardly direction upon actuation of the seat safety device,
7. A motor vehicle as claimed in any of Claims 1 to 4 in which the whole seat moves forwardly and downwardly upon actuation of the seat safety device.
8. A motor vehicle as claimed in any preceding claim in which the seat safety device includes at least one explosively released fixing means.)
9. A motor vehicle as claimed in Claim 7 in which the explosively released fixing means is an explosive bolt.
10. A seat adapted for use in a motor vehicle as claimed in any of Claims 1 to 9.
11. A motor vehicle as described herein with reference to the accompanying drawings.
12. A seat for a motor vehicle as described herein with reference to the accompanying drawings.