Abstract:
Herein disclosed is a seat slide device which comprises a lower rail including a channel portion with first and second side walls; an upper rail longitudinally slidably disposed on the lower rail, the upper rail having a major flat wall portion which faces the channel portion when the upper rail is properly disposed on the lower rail; and first and second lugs projected from the major flat wall portion of the upper rail into the channel portion of the lower rail. The first and second lugs are located in the vicinity of inner surfaces of the first and second side walls of the lower rail, respectively, so that undesired lateral play of the upper rail relative to the lower rail is suppressed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates in general to seat slide devices of a motor vehicle, and more particularly to seat slide devices of a type which comprises a pair of lower rails secured to a vehicle floor and a pair of upper rails slidably disposed on the lower rails and mounting thereon a seat. 
     2. Description of the Prior Art 
     Hitherto, various types of seat slide devices have been proposed and put into practical use particularly in the field of motor vehicles. In the devices, there is a type which comprises a pair of lower rails secured to a floor, a pair of upper rails slidably disposed on the lower rails and mounting thereon a seat mounted thereon, and a plurality of balls rotatably disposed between mated pairs of the lower and upper rails for smoothing the movement of the upper rails relative to the lower rails. 
     However, some of the seat slide devices of such type have suffered from a drawback due to their inherent constructions. 
     That is, some of the seat slide devices have been constructed without giving a considerable thought on the construction by which a lateral play of the upper rails relative to the lower rails is effectively suppressed. In fact, during movement of the vehicle, the seat slide devices of such type causes uncomfortable lateral play of the seat mounted thereon relative to the vehicle floor. Such play sometimes produces unpleasant noises. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a seat slide device which is free of the above-mentioned drawbacks. 
     According to the present invention, there is provided a seat slide device in which a structure is employed by which an uncomfortable lateral play of the upper rails relative to the lower rails is assuredly suppressed. 
     According to one aspect of the present invention, there is provided a seat slide device which comprises a lower rail including a channel portion with first and second side walls; an upper rail longitudinally slidably disposed on the lower rail, the upper rail having a major flat wall portion which faces the channel portion when the upper rail is properly disposed on the lower rail; and first and second lugs projected from the major flat wall portion of the upper rail into the channel portion of the lower rail, the first and second lugs being located in the vicinity of inner surfaces of the first and second side walls of the lower rail, respectively. 
     According to another aspect of the present invention, there is provided a seat slide device which comprises two slider units which are substantially the same in construction and arranged in parallel with each other, each slider unit including a lower rail including a channel portion with first and second side walls, an upper rail longitudinally slidably disposed on the lower rail, the upper rail having a major flat wall portion which faces the channel portion when the upper rail is properly disposed on the lower rail, and first and second lugs projected from the major flat wall portion of the upper rail into the channel portion of the lower rail, the first and second lugs being located in the vicinity of inner surfaces of the first and second side walls of the lower rail, respectively; and two locking mechanisms constructed to lock the upper rails relative to the lower rails; and a lock releaser incorporated with the two locking mechanisms and cancelling the locked condition of the upper rails when manipulated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a perspective view of a seat slide device according to the present invention; 
     FIG. 2 is a sectional, but enlarged, view taken along the line II--II of FIG. 1; 
     FIG. 3 is a sectional, but enlarged, view taken along the line III--III of FIG. 1; 
     FIG. 4 is a sectional, but enlarged, view taken along the line IV--IV of FIG. 1; and 
     FIG. 5 is a partially cut perspective view of the seat slide device showing a part where a measure according to the present invention is employed. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1 to 5, particularly FIG. 1, there is shown a seat slide device 10 according to the present invention. 
     As is seen from FIG. 1, the seat slide device 10 comprises generally two slider units 10a and 10b, lock mechanisms 50 respectively associated with the two slider units 10a and 10b and a lock releaser 10c. 
     Since the two slider units 10a and 10b are substantially the same in construction except for small things caused by the symmetrical arrangement therebetween, the following description of the slider units 10a and 10b will be made only with respect to the slider unit 10a which is to be positioned at right side when mounted on a vehicle floor. 
     The slider unit 10a comprises a lower rail 20 which is connected to the vehicle floor and an upper rail 30 which is slidably disposed on the lower rail 20 and mounts thereon a seat (not shown). As will become apparent as the description proceeds, the upper rail 30 is arranged to cover the lower rail 20. 
     As is seen from FIG. 1, the lower rail 20 has at its front and rear ends respective brackets 15 and 16 secured to the vehicle floor. 
     As is seen from FIGS. 2, 3 and 4, the lower rail 20 comprises a channel portion 23 having side walls 21 and 22, and outward flanges 24 and 27 extending outward from tops of the respective side walls 21 and 22. Each outward flange 24 or 27 includes an outwardly extending inclined portion 25 or 28 and a downwardly extending vertical portion 26 or 29. Thus, a longitudinally extending slot 24a or 27a is defined between the side wall 21 or 22 and the associated side flange 24 or 27. The outwardly extending inclined portion 25 or 28 is formed at its upper surface with a longitudinally extending shallow guide groove (no numeral) along which ball bearings 40 run as will be described in detail hereinafter. 
     The vertical portion 29 of the side flange 27 is formed with a plurality of notches 29a which constitute part of the lock mechanism 50 which will be described in detail hereinafter. 
     The upper rail 30 comprises a channel portion 33 having side walls 31 and 32. Each side wall 31 or 32 has an inwardly turned flange 31a or 32a. Each side wall 31 or 32 and the major flat wall portion (no numeral) of the upper rail 30 constitute at their joined curved portion a longitudinally extending guide way along which the ball bearings 40 run as will be described in the following. 
     As will be understood from FIGS. 2, 3 and 4, the upper rail 30 is slidably mounted on the lower rail 20 having the inwardly turned flanges 31a and 32a slidably disposed in the longitudinally extending slots 24a and 27a of the lower rail 20, and the ball bearings 40 are rotatably disposed between each guide groove of the lower rail 20 and the associated guide way of the upper rail 30, as shown. 
     Thus, the upper rail 30 can smoothly slide forward and rearward on and along the lower rail 20 by the provision of the ball bearings 40. 
     In accordance with the present invention, the following measure is further employed, which suppresses or at least minimizes undesired lateral play of the upper rail 30 relative to the lower rail 20. 
     That is, as is seen from FIG. 1, the flat major wall portion of the upper rail 30 has three longitudinally spaced apertured areas where respective parts of the major wall portion are partially cut and bent down to form front, middle and rear lugs 34, 35 and 36 which are projected into the inside of the upper rail 30. The lugs are shaped like a plate and the major surface (34a, 35a, 36a) of the plate faces the inner surface of the corresponding side wall (21, 22) of the lower rail (20) generally parallel. The front and rear lugs 34 and 36 are arranged to slidably contact with the side wall 21 of the lower rail 20, while the middle lug 35 is arranged to slidably contact with the other side wall 22 of the lower rail 20. Preferably, the three lugs 34, 35 and 36 are positioned at equally spaced intervals. 
     As will be seen from FIG. 5, each lug 34, 35 or 36 is shaped arcuate having a depressed middle part 37 which is in contact with the side wall 21 or 22 and raised side parts 38 and 38 which are spaced from the side wall 21 or 22. 
     If desired, each apertured area of the major flat wall of the upper rail 30 may be provided with mutually facing two lugs. In this modification, one lug is in contact with the side wall 21 and the other lug is in contact with the other side wall 22. 
     As is seen from FIG. 1, the lock mechanism 50 of each slider unit 10a or 10b comprises the notches 29a formed in the lower rail 20, a locking lever 51 pivotally supported through a boss 32a by the side wall 32 of the upper rail 30, a pawl (not shown) carried by the locking lever 51 and latchingly engageable with the notches 29a and a biasing spring 58 for biasing the locking lever 51 in a direction to achieve the latching engagement between the pawl and the notches 29a. 
     The lock releaser 10c is of a generally U-shaped bar 55, which has leg portions 55 and 55 each being secured to a base portion of the pivotally supported locking lever 51. Denoted by numeral 57 is a handle portion of the bar 55, which is to be manipulated by an operator (viz., a seat occupant) when a change of the seat position is required by him or her. 
     In the following, operation of the seat slide device 10 will be described with reference to the drawings. 
     For ease of understanding, the description will be commenced with respect to a locked condition of the seat slide device 10. 
     Under this condition, the pawl of the locking lever 51 of each lock mechanism 55 is in engagement with selected one of the notches 29a of each lower rail 20. Thus, the upper rails 30 and thus the seat mounted thereon is locked relative to the lower rails 20. 
     When, as is seen from FIG. 2, the upper rail 30 is applied with a considerable load in the direction of the arrow A, a part of the load is received through the ball bearings 40 by the outward flange 24 of the lower rail 20, and the other part of the load is received through the middle lug 35 by the side wall 22 of the lower rail 20. It is to be noted that the load is also received by the parts of the other slider unit 10b. In the other slide unit 10b, however, the load is received by the side wall 21 of the lower rail 20 through two, that is, front and rear, lugs 34 and 36. 
     Thus, the seat mounted on the upper rails 30 is suppressed from making uncomfortable lateral play relative to the fixed lower rails 20. 
     When, for the purpose of changing the position of the seat, the handle portion 57 of the lock releaser 10c is raised by an operator (viz., a seat occupant) against the force of the springs 58, the pawl of the locking lever 51 of each lock mechanism 50 is disengaged from the notch 29a of the lower rail 20 thereby cancelling the locked condition of the seat relative to the fixed lower rails 20. 
     Thus, when, with the handle portion 57 kept raised, the seat is pushed forward or rearward, the same is moved forward or rearward on the lower rails 20. During this movement, the ball bearings 40 roll on the shallow guide grooves formed on the outward flanges 24 and 27 of each lower rail 20, smoothing the movement of the seat. Due to provision of the front, middle and rear lugs 34, 34a, 35, 35a, 36 and 36a, the movement is carried out without suffering from undesired lateral play of the seat. 
     When the seat is moved to a desired position, the handle portion 57 of the lock releaser 10c is released by the operator&#39;s hand. With this, the pawl of the locking lever 51 of each lock mechanism 50 is brought into engagement with a newly selected one of the notches 29a of each lower rail 20 by the force of the spring 58. Thus, the seat becomes locked at a new position.