Abstract:
In an arrangement for a seat ( 2 ) in a vehicle, the seat is movable in a longitudinal direction along a plane ( 33 ) which slopes relative to the horizontal plane. The subframe of the seat ( 2 ) consists of devices ( 30, 31 ) fastened respectively to the vehicle and to the seat, which devices consist of two substantially similar triangular supporting frames. Resetting between a predetermined driving position and a likewise predetermined resting position is made possible by a control device ( 16 ) which is fastened to the device ( 30 ) which is itself fastened to the vehicle, which control device cooperates with a locking device fastened to the seat so that during a relocating movement between forward and rear positions of the seat the locking device ( 17 ) becomes free from at least one locking position between the vehicle seat and the device ( 30 ) fastened to the vehicle.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an arrangement for enabling a vehicle seat to be moved forward and rearwardly, to be locked in a forward operating position and to be readily unlocked for rearward movement and a subframe which is fastenable to the vehicle floor below it and to the seat above it, which permits the seat to slide forward and rearward, which enables. the seat to be locked in a forward position and which enables the seat to be moved rearwardlye. 
     STATE OF THE ART 
     A generally known arrangement is for vehicle seats, particularly driving seats, to be movable in the longitudinal direction of the vehicle in order to make convenient positioning possible for the seat user and/or create more clear space in the interior of the vehicle. In such cases the seat is usually mounted on longitudinal rails situated in a plane which either slopes somewhat upwards in the forward direction of the vehicle or substantially horizontally. This consequently makes it possible to move the seat along the corresponding plane. Such an arrangement does limit, however, the possibility of easily climbing into and out of the vehicle and getting into and out of the vehicle seat, particularly in vehicles of the truck and bus type. Operating the seat securing mechanism for manual setting of the seat in the longitudinal direction also involves control action during the whole setting movement and often entails one or more extra setting movements before the desired securing position is reached. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The object of the present invention is to provide a seat arrangement that manifestly reduces the abovementioned disadvantages of the state of the art. The invention aims at seat control which, particularly in truck cabs, makes it easy to reset the seat between a predetermined driving position and a likewise predetermined resting position not intended to be a driving position. The solution has also to make possible a simple form of control mechanism with simple and inexpensive components without having to disregard the safety requirement of reliable securing of the seat. 
     To this end, the invention is distinguished by a control device that cooperates with the seat locking device during relocation of the seat between the forward and rear positions, freeing the locking device from a locking position to free the seat to move to the rear position. The features therein indicated makes it possible for the seat to be provided with a longitudinal relocating movement between a forward (driving) position and a rear (resting) position by easy manual operation of a control which acts upon the seat locking device. Rail mechanisms of standard types which are simple, inexpensive but well-proven from the safety point of view can be used for the purpose. The co-operation according to the invention between control device and locking device also makes it possible to reset the seat quickly and safely between preselected forward and rear positions. This solution is particularly advantageous in the case of seats of the type which can be relocated along a plane which slopes downwards in the forward direction of the vehicle. Such seats are used with advantage in vehicles of the truck and bus type which are entered by climbing and in which it is possible to sit down in the seat from an almost standing position. 
     In an advantageous embodiment of the invention, the seat can be moved rearwards with the assistance of a first force to a rear (resting) position. This makes it possible for a person sitting in the seat to cause it to move to a rear position by simply lightening his weight on the seat and by operating manually the control which acts upon the securing mechanism. 
     In another embodiment, the seat can be moved forwards, i.e. from the rear position to a forward (driving) position, against the action of a second force. This means that in the case of seats of the aforesaid type which can be moved along a plane which slopes downwards in the forward direction of the vehicle, the movement can take place against the action of the second force so that when a person sits on the seat while it is at an upper resting position the seat will automatically, by a controlled movement, assume a driving position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred embodiment of the invention is described below with reference to the attached drawings, in wich: 
     FIG. 1 shows schematically a side view of a vehicle cab with a seat arrangement according to the invention, 
     FIG. 2 shows a perspective view of a seat subframe according to the invention, 
     FIG. 3 shows a schematic arrangement according to the invention for mutual locking of the subframe components, and 
     FIG. 4 shows the same view as FIG. 1 with the seat arrangement at a different height. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     A truck cab  1  is depicted schematically in FIG. 1. A driver&#39;s area contains a driving seat  2  with a subframe  3  which is fastened to the cab floor  4 . The seat  2  can be moved in the longitudinal direction of the vehicle from a forward (driving) position  5  to a rear (resting) position  6  which is not intended to be used when the vehicle is being driven. FIG. 1 shows only the subframe  3  in the resting position, but it is implicit that when moving to the rear position  6  the subframe  3  is accompanied by the seat  2  with its frame  35 . A pedal set  8 , a steering wheel  9  and an instrument panel  10  are situated in a conventional manner in front of the seat. A gear lever  11  and a lever  23  forming part of a securing device  15  (depicted in FIGS. 2 and 3) according to the invention are situated to the side of the seat. An engine cover  12  also protrudes into the cab and to some extent separates the driving side from the passenger side. 
     The subframe  3  is composed advantageously of two substantially similar elements  30 , 31 , each of which has a triangular shape in the vertical plane (see FIG.  2 ). Each element is composed of two triangular sideplates whose sides, which are short catheti, are joined together by an endplate  38  and, at the opposite end, by the corner sections of an angle plate  39 . The underside of the element  30 , which is a cathetus, is intended to be fastened to the vehicle floor, advantageously by undepicted screws or bolted connections. The hypotenuse side of the element  30  bears a rail device  32   a  in the form of a rail on each triangular sideplate. The rail device  32   a  forms a plane  33  which slopes relative to the horizontal plane and which is represented in FIG. 1 by a chain-dotted line. The subframe  3  and its elements  30 , 31  are so arranged that the sloping plane  33  slopes downwards in the forward direction of the vehicle. 
     The hypotenuse side of the upper element  31  correspondingly bears a rail device  32   b  for cooperation with the rail device  32   a  of the lower element  30 . The top of the upper element  31  supports a rail device  32   c  (depicted in FIG. 1) for co-operation with a corresponding rail device on the underside of the frame  35 . Said co-operation makes a longitudinal relocating movement possible along the horizontal plane  34  formed by these rail devices, which is represented in FIG. 1 by a chain-dotted line. All the rail devices  32   a ,  32   b  and  32   c  are of a conventional standard type which has toothed recesses for locking in various positions at will and which conform to stringent safety requirements but are described in no further detail here. FIG. 3 shows schematically the rail devices  32   a , 32   b  with roller devices  27  for easy frictionless longitudinal relocating movement between the elements  30 , 31 . 
     A return spring  40 , advantageously in the form of a gas spring as depicted in FIG. 2, is arranged between the forward end portion of the lower element  30  (as seen in the forward direction of the vehicle) and the rear end portion of the upper element  31 , preferably in a longitudinal symmetry plane between their angle plates  39 . When the upper element  31  is in the forward end position  5  (depicted in FIGS. 1 and 2) relative to the lower element  30 , the gas spring is in a compressed state. In that situation, the mechanical securing device  15  which locks the elements  30 , 31  to one another prevents the gas spring  40  from pushing the upper element  31  upwards and rearwards along the rails  32   a , 32   b.    
     In an advantageous embodiment of the securing device  15  according to FIGS. 2 and 3, a running track  16  fastened to the lower element  30  (which is itself fastened to the vehicle) co-operates with a rear end section  50  of a locking device  17 . The latter is supported for pivoting about a spindle  41  on the upper element  31  and incorporates on either side of the seat a locking part  44  and a yoke  43  which is fastened thereto by separate fastening devices  46  and which is entered by the rear end section  50 . The yoke  43  consequently extends between the two sides of the upper element  31 , and the two locking parts  44  are each supported for pivoting about the spindle  41 . The locking device  17  itself co-operates with a release device  18  which is mounted for pivoting about a spindle  45  on the upper element  31 . Manual operation of the substantially vertical lever  23  which is readily accessible to the driver and situated beside the seat, level with the seat cushion, will make the release device  18 , against the action of a spring  19 , cause the locking parts  44  and the yoke  43  of the locking device  17  to pivot clockwise, in FIG. 3, about the spindle  41 . The forward toothed ends  21  of the locking parts will thus be raised from a co-operating securing position relative to the toothed rails  32   a  which are fastened along both sides of the lower element  30  (which is itself fastened to the vehicle). This raising takes place against the action of a spring  24  whose ends are fastened to the respective locking part  44  and to the upper element  31 . The running track  16  is with advantage placed alongside a longitudinal symmetry plane of the elements  30 , 31 , and the yoke  43  has a more or less symmetrical extent as seen in a horizontal plane, resulting in substantially even distribution of the forces acting upon the rails. 
     Pivoting the lever  23  about its spindle  45  causes the yoke  43  to be acted upon so that the locking parts  44  can be raised from their securing positions. When this has taken place, the spring  40  urges the upper element  31  rearwards along the plane  33 . In cases where the plane  33  exhibits a definitely downward forward slope, this takes place against the action of the person sitting in the seat who, by slightly reducing his weight on the seat, makes the movement possible. The force exerted by the spring  40  has a component in the vertical direction which, depending on the slope of the plane  33 , constitutes a predetermined proportion of a statistical mean of the weight of adult persons. 
     The yoke  43  and its rear end section  50  which is provided with a roller and is intended to cooperate with the running track  16  are urged by the action exerted by the respective springs  40  of the locking parts  44  to bear on the running track  16  during the movement of the element  31  along the rails  32   a , 32   b  to a rear end position. This movement is limited by the maximum length of the gas spring  40  (see FIG. 2) and/or by a purely mechanical stop, e.g. in the form of a considerable downward bend (depicted in FIGS. 2 and 3) of the running track  16 . In this case, no seat position locking takes place at the upper end position, as the seat will slide down along the plane if the weight load exceeds the aforesaid vertical force component. Only when the rear end device  50  of the yoke leaves the upwardly rounded forward end of the running track  16  can the locking parts  44  assume a securing position relative to the lower element  30 . the invention thus makes possible a predetermined driving position of the seat which can be finely adjusted in a conventional manner by setting the seat in the longitudinal direction by means of the rails which are fastened in the horizontal plane  34  to the top of the upper element  31 . The seat can also be set in the vertical direction by means of a height setting device in the seat frame  35  in a manner shown in FIG. 4, where one can see the seat at a lowered height, as compared with FIG.  1 . 
     The lever  23  is so placed as to be operable not only by a person sitting in the seat but also by another person who is in the cab or interior of the vehicle and can accordingly easily act upon the lever, inter alia by means of his foot, to move the seat to either end position. In a truck cab the seat can thus be moved to the forward position to provide extra clear space in the cab, e.g. to make overnighting in it more comfortable. The lever  23  may also be provided with a securing arrangement to prevent inadvertent manual operation. The securing arrangement may consist of a recess  47  from which the lever  23  has to be raised by a tilting movement transverse to the forward direction of the seat, against the action of a spring (not depicted here), before the lever can be operated. 
     The securing device may of course take various different forms, e.g. with the possibility of a securing position in a rear (resting) position of the seat In driving seat applications, however, it is advantageous for it to be designed to only secure the lower (driving) position, while the resting position has no securing arrangement. This eliminates the risk of the driver being able to set the vehicle in motion while the seat is in the resting position. It has instead the advantageous effect that the driver glides in a controlled manner down the sloping plane as soon as the seat is sat on in its resting position, whereupon the preset driving position is automatically assumed. It is of course also possible to choose from among a number of alternative end positions below the end of the running track, which can be achieved by the release device being operated while at the same time the driver suitably increases the weight force on the seat in order to overcome said vertical force component. This will usually be unnecessary, however, since the seat still has the possibility of longitudinal setting by movement along the rails in the horizontal plane which are fastened to the top of the upper element  31 .