GB1575668A

GB1575668A - Locking device for vehicle seat guides

Info

Publication number: GB1575668A
Application number: GB5289377A
Authority: GB
Original assignee: C Rob Hammerstein GmbH
Current assignee: Johnson Controls Metals and Mechanisms GmbH and Co KG
Priority date: 1977-01-07
Filing date: 1977-12-20
Publication date: 1980-09-24
Also published as: DE2700474A1; SE7713352L; FR2376772A1

Description

(54) A LOCKING DEVICE FOR VEHICLE SEAT GUIDES (71) We, C. ROB. HAMMERSTEIN OmbH, of 565 Sdlingen-Merscheld, Federal Republic of Germany, a company of the Federal Republic of Germany, do hereby .declare the invention, for which we pray that a -patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a locking device for vehicle seat guides composed of two rails which are movable relative to each other.

The purpose of such a locking device is to lock the two rails of the seat guide in case of an accident firmly against each other.

This locking function is in normal use of the seat guide of a motor vehicle taken over by an arresting device which is mostly actuated by hand.

There is a tendency in the automotive technology to attach the safety belt directly to the seat and not to the body of the vehicle. For that reason if the vehicle is involved in an accident the inertia forces generated on acceleration or deceleration of the passengers are transmitted via the safety belt and the seat in their entirety on to the seat guide. The seat guide is therefore exposed to much higher loading than is the case when the seat belts are attached to the body. It is known from experience that the highest inertia forces are generated by head-on collisions and by collisions of movement of the vehicle. The direction of displacement of the seat guide extends generally in the same direction. For this reason the arresting device of this seat guide is in the case of an accident exposed to particularly high stresses and are of decisive importance in the safety of the passengers.

The life of a passenger can depend on reliable arresting capability and function of this arresting device.

Seat guides can be formed by suitable di mentioning in such a way that they withstand the high inertia forces generated during an accident and that they transfer these forces on the chassis of the vehicle. li is disadvantagenous with the known structures that human error can be caused on operation of the arresting device. It can happen, for instance, that a passenger before an acci dent - or also during an acciednt -- oper- ates the arresting device of a seat guide of his seat and the seat guide is for this reason not arrested during -the accident. It can also happen that the arresting device is not sufficiently arrested so that it during an accident jumps out of its arresting posi tion. In case of grave accidents at high differential speeds of the vehicles involved the acceleration of the seat relative to the floor is so high that the arresting pro jections 'have not enough time to enter the arresting recesses by the action of a return spring. Also material defects and fatigue may exist, for instance, due to the previous accidents, which may cause that the arresting device of the seat guide cannot withstand the stresses caused during a serious accident.

Arresting devices which are not designed for safety belts attached to the seat have the disadvantage that they are so weak that they cannot withstand the inertia forces generated during a collision from a rear and neither can they withstand forces acting on passengers sitting in the back of the vehicle who are propelled in a head-on collision forward against an unoccupied seat.

It is the aim of the invention to devise a locking device which acts in addition to the arresting device and which has not the disadvantages of known arresting devices and which even in the case of incorrect and faulty eneagement, of accidental release of the arresting device during an accident, and of defective parts of the arresting device locks the seat guide rails reliablv against each other, and which may possibly be ad ditionally mounted to existing seat guides, is cheap in manufacture and does not re quire maintenance.

The invention provides a locking device for vehicle seat guides including a first rail and a second rail movable relative to each other, the locking device comprising a locking member which is connected to the first rail and is rockable about an axis and is provided on a first portion thereof with at least one first gripping edge, the distance of which from the axis is greater than the distance between the axis and a surface on the second rail which co-operates with the first gripping edge or edges, the locking member being held by a yieldable stop in neutral position in which the first portion is situated opposite to and spaced from the said surface, the yieldability of the stop, the mass of the locking member and the effective distance of the point of inertia from the axis being so selected that when acceleration or deceleration of the vehicle is below a preselected value, the locking member remains in the neutral position, and when the said value is exceeded the locking member rocks automatically into an engagement position in which the first gripping edge or one of the first gripping edges bears on said surface of the second rail, so that the edges as one of the edges penetrates into said surface when the second rail is displaced relative to the first rail.

The advantage of such a locking device resides particularly in that it engages automatically when it is needed and in normal situations does not hinder movement of the rails relative to each other. Due to its simple structure the locking device does not require maintenance and is reliable in function, can be added as an additional part to existing sea.t guides and may be easily mounted at an unobtrusive but protected place.

For the rocking of the locking member from the neutral position to the engagement position the inertia forces acting at the point of inertia must be able to overcome the strength of the stop so that the locking member can rock out of the neutral position.

When the acceleration or deceleration is high - that is during an accident -- the locking member is in the engagement position in which the locking teeth bear on to the rail which is not connected with the locking member. If at such a moment the arresting device is defective or is not arrested a relative movement between the two rails takes place. The rail which is not connected with the locking member moves in the same direction as the pendulous locking member. This ensures that the gripping edges of the locking member can penetrate into the rail end movement of this rail is thereby stopped. After the accident the locking device may again released by pressure applied on to the seat in the opposite direction.

The locking member penetrates in the described form by the gripping edge into the rail while it is supported via a pivot in the other rail. It is advantageous when the locking member in the maximum engaging position bears with one of its front faces, adiacent to the said surface, on the rail connected with the locking member. In that case the rocking movement of the locking member cannot exceed a rocking state in which the gripping edges have already penetrated in the other rail. This avoids pressing of the two rails of the seat guide away from each other. It is further advantageous that the locking member has on one of its front surfaces at least one gripping edge which cooperates with the rail connected with the locking member. Due to this the front surfaces not only contact each other but, they may penetrate by the gripping edges in the rail connected with the locking member. By mounting of the pivot in the rail connected with the locking member the pivot is released from stresses and does not have to be dimensioned to meet dynamic requirements during an accident. It may be made for instance from a plastics and may break during an accident without adversely influencing the function of the locking member during an accident. The pivot may be designed as a torsion spring, while the yieldable stop may be dispensed with.

In order to reliably allow engagement of the gripping edges it is suggested to provide the surfaces, which are situated against the gripping edges and co-operate therewith, with corrugations and make the gripping edges sharp. It is advantageous if in the engagement position first only a single gripping edge gets in contact with the appropriate rail and if it engages through the pivot in a smaller perpendicular distance to the vertical connection of the rails, so that the said distance during displacement of the rails in case of an accident crumples. During the displacement the following outer gripping edges come into engagement.

It is assumed in practice that the automatically operating locking device is held by the yieldable stop in non-operative position when the acceleration is below about 20 m/s2. If the spring and the locking member are symmetrical the locking member will always engage when the preselected value has been reached, irrespective whether the value is positive or negative. It is, however, also possible to arrange that the locking member engages only in case of positive acceleration, which differs from the negative one, and vice versa. It is suggested for this purpose to position the point of inertia of the locking member outside the axis of symmetry or to make the yieldability of the stop non symmetrical.

In order to reduce noise during driving it may be useful to make some of the structural parts of plastics or to coat them with plastics.

Various forms of locking device embodying the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings.

In the drawings: Figure 1 is a perspective view of a part of a seat guide in section provided with a locking device.

Figure 2 is a front elevation showing a first embodiment of a locking member, Figure 3 is a section along line III--III in Figure 2, Figure 4 is a front elevation of a second embodiment of a locking member, mounted ready for use, in neutral position, Figure 5 shows the locking member according to Figure 4 in locking position, Figure 6 is a front elevation of a third embodiment of a locking member, Figure 7 is a front elevation of a fourth embodiment of a locking member provided with a spring, Figure 8 is a perspective view of a fifth embodiment of a locking member, and Figure 9 is a perspective view of a part of a seat guide provided with a locking member according to Figure 8.

In Figure 1 is as a first embodiment of the invention arranged a locking device between the rails 5 and 6 of a seat guide.

The locking member 1 is by means of a pivot 2 connected with a fixed rail 5, the seat 7 is attached to a displaceably guided rail 6. Opposite to the inner side 19 of this rail 6 is the locking member 1 illustrated in neutral position a small gap remaining between the upper portion 9 of the locking member 1 and this inner side. The locking member is mounted to be rockable about the pivot 2 and is by means of a M-shaped spring 3 held in a neutral position.

If the direction 8 of displacement of the seat guide 5, 6 corresponds to the direction of movement of the vehicle the pivot 2 extends at right angles to the direction of movement. The centre 13 of inertia lies above this pivot 2 and consequently outside the plane containing the pivot 2 and the direction 8 of displacement. In a head-on collision the locking member 1 rocks in the direction to the front edge of the seat 7, i.e. in Figure 1 to the right. If the arresting device is defective or is not arrested the upper rail 6 moves in this direction. Due to this, the gripping edges 10 of the left part of the portion 9 bury themselves into the inner side 19 of this rail 6 and prevent further movement of the rail 6.

In such a case a force, acting in the displacement direction 8 of the seat guide 5, 6 to the right acts on the left part of the portion 9 nearly tanPentially and tends to turn the locking member 1 further about the pivot 2. Due to this the pivot 2 is pressed downwards and, in addition, the inner rail 6 bulls from inside unwards. As long as the pivot 2 remains unbroken and the rail 6 is not pressed out of the rail 5, a firm locking of the two rails 5 and 6 is ensured.

In the embodiment according to Figures 2 and 3 the gripping edges 10 extend at an acute angle and are sharp, so that a reliable engagement is ensured at all times. In a variant of this embodiment according to Figures 2 and 3 the gripping edges may naturally also be pointed.

The function of the locking device according to the invention is apparant particularly with reference to Figures 4 and 5, which, at the same time, show a further embodiment. The locking member 1 has gripping edges also on the bottom portion 17 and by their penetration into the rail 5 the rocking movement of the locking member 1 is limited. At the same time also the movement of the portion 9 directed upwards is limited and in this way the upper rail 6 is prevented from being pressed upwards and from being separated from the lower rail 15. By the limitation of the rocking movement the gripping edges 10 of the portion 9 may lie, in this embodiment, on a circular arc and come into engagement one after another as is shown in Figures 1 to 3 the gripping edges 10 are positioned on straight lines. The spring 3 ensures that the locking member 1 is held in the neutral position and the spring presses the locking member 1 in addition against the pivot 2 in such a way that the locking device cannot rattle even if the vehicle shakes.

A particularly advantageous embodiment of the locking member 1 is illustrated in Figure 6. This locking member 1 has the outer appearance of a rhombus. The figure shows where the rails 5 and 6 are positioned relative to the locking member 1 in neutral position and it also shows the position of the rails 15, 16 when the locking member 1 engages. In this embodiment the bore 4 and the pivot 2 are needed only for the pivotal mounting of the locking member 1. As soon as the locking member 1 is swung into the position of engagement, the pivot 2 is no longer needed, as the locking member 1 is buried in both rails 5, 6. The pivot may consequently be made of a cheap material as the requirements on its strength are small. It can also be made directly as a torsion spring and the spring 3 may be dispensed with.

In the embodiment according to Figure 7 three notches 11 are arranged in the vicinity of the bore 4. As soon as a sufficiently hit acceleration value is reached the locking member 1 swings and the spring 3 engages into one of the two outer notches 11. The angle between the notches is so chosen that the spring 3 bears alwavs on the inner flanks of the outer notch 11 when the locking member 1 is in the engagement position, that is to say when its locking teeth 10 contact the upper rail 6. This stricture ensures that the locking member 1 bears in its engaging posi tion on the upper rail 6 in a springing man ner. Consequently as soon as the acceleration value needed for the actuation of the lock ing device is achieved, the locking device is in the engagement position. This has the ad vantage that the locking device is during the whole duration of the accident in a posi tion ready for engagenient. Consequently if only during a later stage of the duration of the accident the arresting device of the seat guide becomes defective, the locking device can engage even in such a caste.

A further advantage of the locking de vice according to the invention resides in that 'in case of an engagement of the locking de vice the seat travels through a certain bra king path. As a braking path is reached by the deformation of crumpling zones also in this case an additional non-elastic path is Echi ved during the engagement of the lock ing device. When there is a small distance between the rails 5 and 6 it is necessary to adapt the locking member 1 to these re quirements. The locking member 1 accord ing to Figure 8 is connected with the fixed rail 5 by means of a snap spring 3 and its gripping edges 10 are positioned opposite to -the inner side 19 of the movable rail 6 at a small distance therefrom. The gripping edges 10 are therefore situated on two surfaces of the portion 9 separated by a step so that the engagement in the rounded inner side 19 is always ensured. The engagement begins with the inner corners of the higher surface. The gripping edges 101 are useful also for the co-operation with the fixed rail 5, on account of that the mounting of the locking member 1 in this rail 5 may be dispensed with and the locking member 1 is held only by the spring 3.

In the embodiment of the locking mem ber 1 according to Figures 8 and 9 the lock ing member 1 is composed of a rocking mass 20 and a gripper 21, which are connected with each other via the pivot 2. Spitting 'into a rocking mass 20 and a gripper 21 is advantageous particularly when there are small distances between the rails 5 and 6 of the seat guide.

In this embodiment the centre 13 of inertia acts on the pivot of the locking member 1 via a large rotatable arm so that the return force even of a harder spring 3 may be overcame. The gripper 21 is rela tively protected and the state of the locking device may be easily inspected from the position of the rocking mass 20.

In the embodiment according to Figure 1 the locking member 1 is situated inside be tween the rails 5 and 6. In this way it is pro tected. The locking device may also be situ ated outside 'the 'rails, ,this positioning is 'recommended for instance for additional application. -An automatically functioning locking device is preferably provided on both sides of each seat approximately in the medium zone thereof. The locking member 1 can be made by stamping and its thickness may be so chosen that even if the pivot breaks a safe locking is obtained, that is to say that the locking member cannot be pressed into an oblique position, for instance a diagonal position, which would make it non- effective.

WHAT WE CLAIM IS: 1. A locking device for vehicle seat guides including a first rail and a second rail movable relative to each other, the locking device comprising a locicing member which is connected to the first rail and is rockable about an axis and is provided on a first portion thereof with at least one first gripping edge, the distance of which from the axis is greater than the distance between the axis and a surface on the second rail which co-operates with the first gripping edge or edges, the locking member being held by a yieldable stop in a neutral position in which the first portion is situated opposite to and spaced from the said surface, the yieldability of the stop, the mass of the locking member and the effective distance of the point of inertia from the axis being so selected that when acceleration or deceleration of the vehicle is below a preselected value, the locking member remains in the neutral position, and when the said value is exceeded the locking member rocks automatically into an engagement position in which the first gripping edge or one of the first gripping edges bears on said surface of the second rail, so that the edges or one of the edges penetrates into said surface when the second rail is displaced relative to the first rail.

2. A locking device according to Claim 1 wherein addition to the first gripping edge or edges there is provided at least one second gripping edge, the second gripping edge or edges being at a greater distance from the axis than the first gripping edge or edges.

3. A locking device according to Claim 1 or 2 wherein the locking member is symmetrical and its axis of symmetry passes through the said axis of the said rocking movement and extends perpendicularly thereto.

4. A locking device according to any one Of Claims 1 to 3 wherein the locking member bears in its maximum engagement position with a second portion thereof on to the first rail connected with the locking member.

5. A locking device according to Claim 4 wherein the locking member has on said second portion at least one gripping edge which co-operates with the first rail con necked with the locking member.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. upper rail 6. This stricture ensures that the locking member 1 bears in its engaging posi tion on the upper rail 6 in a springing man ner. Consequently as soon as the acceleration value needed for the actuation of the lock ing device is achieved, the locking device is in the engagement position. This has the ad vantage that the locking device is during the whole duration of the accident in a posi tion ready for engagenient. Consequently if only during a later stage of the duration of the accident the arresting device of the seat guide becomes defective, the locking device can engage even in such a caste. A further advantage of the locking de vice according to the invention resides in that 'in case of an engagement of the locking de vice the seat travels through a certain bra king path. As a braking path is reached by the deformation of crumpling zones also in this case an additional non-elastic path is Echièved during the engagement of the lock ing device. When there is a small distance between the rails 5 and 6 it is necessary to adapt the locking member 1 to these re quirements. The locking member 1 accord ing to Figure 8 is connected with the fixed rail 5 by means of a snap spring 3 and its gripping edges 10 are positioned opposite to -the inner side 19 of the movable rail 6 at a small distance therefrom. The gripping edges 10 are therefore situated on two surfaces of the portion 9 separated by a step so that the engagement in the rounded inner side 19 is always ensured. The engagement begins with the inner corners of the higher surface. The gripping edges 101 are useful also for the co-operation with the fixed rail 5, on account of that the mounting of the locking member

1 in this rail 5 may be dispensed with and the locking member 1 is held only by the spring 3.

In the embodiment of the locking mem ber 1 according to Figures 8 and 9 the lock ing member 1 is composed of a rocking mass

20 and a gripper 21, which are connected with each other via the pivot 2. Spitting 'into a rocking mass 20 and a gripper 21 is advantageous particularly when there are small distances between the rails 5 and 6 of the seat guide.

6. A locking device according to any

one of claims 1 to 5 wherein the stop is a spring.

7. A locking device according to Claim 6 wherein the spring is shaped as a wave having two crests and a central trough and accommodates at its trough the part of the locking member near the axis and bears with its arms on to the first rail connected with the locking member.

8. A locking device according to Claim 6 wherein the spring is formed as a snap spring which, within a certain rocking angle facilitates further rocking movement.

9. A locking device according to any one of Claims 1 to 8 wherein the surfaces of the rails which lie against the gripping edges are ribbed.

10. A locking device according to any one of Claims 1 to 9 wherein the locking member is mounted in the first rail which is connected to the locking member by means of a pivot or bolt.

11. A locking device according to Claim 10 wherein the pivot or bolt and the stop are combined together as a torsion spring.

12. A locking device according to any one of Claims 1 to 11 wherein the locking member bears in its engagement position on to the first rail connected with the locking member.

13. A locking device according to any one of Claims 1 to 12 wherein the locking member is composed of a rocking mass and a gripper which are spaced apart and interconnected.

14. A locking device constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as shown in the accompanying drawings.

15. A vehicle seat guide including two rails movable relative to each other and comprising a locking device according to any one of the preceding claims.

16. A vehicle including a seat guide according to Claim 15.