US3345712A

US3345712A - Buckle for seat belts

Info

Publication number: US3345712A
Application number: US528876A
Authority: US
Inventors: Lawrence H Smith; Gerald J Partridge
Original assignee: Jim Robbins Seat Belt Co
Current assignee: Jim Robbins Seat Belt Co
Priority date: 1966-02-21
Filing date: 1966-02-21
Publication date: 1967-10-10
Anticipated expiration: 1984-10-10

Description

Oct. 10 1967 $M|TH ET AL 3,345,712

BUCKLE FOR SEAT BELTS Filed Feb. 21, 1966 2 Sheets-Sheet 1 Y I I 1 i 7: l l I l I! 12H i I Z H INVENTORS I6 32 65mm J. PARTRIDGE LAWRENCE H- SMITH ATTORNEYS Oct. 10 1967 5M|TH ET AL BUCKLE FOR SEAT BELTS Filed Feb. 21, 1966 2 Sheets-Sheet 2 INVENTORS GERALD J. PARTRIDGE. LAWRENCE H. SMITH.

ATTORNEYS United States Patent 3,345,712 BUCKLE FOR SEAT BELTS Lawrence H. Smith, Bloomfield Hills, and Gerald J. Partridge, Detroit, Mich., assignors to Jim Robbins Seat Belt (10., Royal Oak, Mich.

Filed Feb. 21, 1966, Ser. No. 528,876 Claims. (Cl. 24230) This invention relates to a buckle for releasably securing the ends of two belt sections of a vehicle safety seat belt system and more particularly to a buckle of the type termed metal-to-meta wherein a male tongue member is secured to the end of one belt and a buckle member secured to the other is adapted to releasably retain the tongue member.

The buckle of the present invention is of the type which automatically locks the tongue in the buckle when the tongue is manually inserted through one side wall thereof and wherein the tongue may be released from the buckle by pressing a pushbutton formed in the outer surface of the buckle. While buckles of this type have been previously proposed, the present buckle structure is particularly convenient to use and trouble-free in operation as well as being simple so as to be economical to manufacture and highly reliable in operation.

As disclosed in the following detailed description of a preferred embodiment of the invention, the tongue member fitted to one of the belt ends consists of a flat section having a slot adjacent to its extreme end which extends transversely to the length of the belt. The tongue is adapted to be inserted into the base of the other buckle member. The base consists of a fiat bottom with a pair of upturned side walls. The side walls pivotably support a latching member having a lock section adapted to enter the slot in the tongue in order to retain the tongue within the base member. A spring biases the latch member into this downward, locked position and allows the latch member to be rocked into an unlocked position by the end of the tongue member as it is pressed into the buckle. When the latch member is in its closed position, with its lock section extending into the slot in the tongue, any retracting force exerted on the tongue simply tends to urge the latch member further in its locking direction. In order to open the belt, the latch member is pivoted out of its locked position by depressing a pushbutton slidably supported in a cover member for the base. The cover member extends over the top and sides of the base and provides a slot at one end for the entrance of the tongue member.

The pushbutton motion is transmitted to the latch member by a cam and lever arrangement which includes a cylindrical rod that extends across the width of the base and has a pair of cylindrical pins, smaller in diameter than the rod, projecting outwardly from the ends of the rod, with their axes displaced with respect to the central axis of the rod so as to act as eccentrics. These eccentric pins are rotatably supported by the upturned sides of the base. Accordingly, when the transverse rod rotates about its end pins, it does so in an eccentric manner. The transverse rod itself passes through a pair of holes formed in opposed points in upturned sidewalls of the lock member. These holes are just large enough to allow a rolling fit to the rod. An elongated lever is connected to one edge of the rod and has its other end abutting the lower side of the pushbutton. This allows the downward movement of the pushbutton to be converted into a rotation of the lever. When the pushbutton is depressed, the lever causes the rod to rotate in an eccentric manner about its end pins, so as to cause the latching member to rotate, in the manner of a cam, about its pivot point. This raises the lock section of the latching member allowing the belt tongue to be withdrawn. The extension of the lever arm between the center of the transverse rod and its contact point with the pushbutton is several times longer than the eccentric distance between the pins and the center of the rod, so as to provide a mechanical advantage to the opening action and also to require a relatively large button movement before opening will occur. The mechanical advantage tends to insure that the buckle will open after it has been subjected to heavy stresses, such as might occur in an accident, and represents an important safety feature, since if the buckle would not open after anaccident, the occupant of the seat may be trapped therein. The relatively large pushbutton movement before the buckle opens insures against accidental opening of the buckle. The upper surface of the button is recessed within the buckle top to provide additional assurance that an accidental force on the top will not depress the button.

It is therefore seen to be a primary object of the present invention to provide a simple and reliable construction for a belt retaining buckle wherein a spring biased latch member having a locking section which enters a slot in the buckle tongue may be released by a pushbutton which transmits its motion to the latch member by a lever and cam arrangement which increases the force and decreases the movement of the pushbutton motion when applying it to the latch.

Another object is to provide such a buckle wherein the latch member is pivotably supported with respect to the base member and is also rotatably supported with respect to a circular cam member, which is itself supported with respect to the base along an axis eccentric to its axis of support of the latch member, and means are provided for rotating the cam member as the pushbutton is depressed.

A further object is to provide such an arrangement wherein the cam member is rotated by a lever arm abutting the under side of the pushbutton and the length of the lever arm exceeds the eccentric distance of the cam so as to provide a mechanical advantage to the force exerted to lift the latch member.

Other objects, advantages and applications of the present invention will be made apparent by the following detailed description of a preferred embodiment to the invention. The description makes reference to the accompanying drawings in which:

FIGURE 1 is a top view of a buckle formed in accordance with the present invention along with the ends of its associated belt webbings;

FIGURE 2 is an elevation sectional view through the structure of the buckle taken along line 22 of FIG- URE 1;

FIGURE 3 is a plan view through the buckle with the cover member removed;

FIGURE 4 is a perspective view of the buckle and the retracted tongue with the cover again removed for purposes of illustration; and

FIGURE 5 is an elevation sectional view through the buckle assembly while the button is in a depressed condition taken along line 22 of FIGURE 1.

Referring to the drawings, the buckle of the present invention is applied at the ends of a pair of

webbing sections

10 and 12. The opposite ends of the webbing section are appropriately connected to the frame of the vehicle in which the belt system is employed so that when the two buckle sections are joined together a closed loop is formed securely retaining the occupant in his seat. The belt section 12 is joined to a main buckle member generally indicated at 14 in a manner which will be subsequently described. The belt section 112 is joined to a tongue member, generally indicated at 16 which is adapted to be locked within the buckle 14.

The tongue section 16 is formed of a relatively thin, flat metal plate, generally rectangular in shape, and having a widened section 18 at one end formed with a slot 20 across its width. A loop 22 is formed at the end of the belt 12 and is appropriately joined to the main belt section, as by sewing, in order to retain the tongue member 16 on the end of the belt 12. The forward end of the tongue 16 has rounded corners 24 and has a second, rectangular slot 26 formed across its width.

The main buckle member 14 is formed about a base member 28 which has a pair of opposed

upturned sides

30 and 32 which extend generally normally to the base. The base member and sides are preferably stamped out of high tensile alloy steel. At the end of the base member, adjacent to the belt (which will be termed the rear end of the base), the

side walls

30 and 32 are obliquely pierced at opposed points to form slots 34. A serrated roller 36, having a length slightly less than the distance between the interior opposed sides of the

walls

30 and 32, is supported in the slots by means of extending rectangular tabs 38 which project from its ends into but not through the slots. The tabs 38 are shorter and thinner than the slots so that the roller 36 may slide along the slots. The base 28 has a section 40 punched out of its bottom which allows the belt 10 to be brought up through the hole 40, brought around the roller 36, and returned through the slot. In this manner when a pull is exerted on the belt 10, the roller 36 tends to move downwardly in the slot 34 and thus lock the belt 10 to the buckle section 14 against retraction.

The forward end of the punched out section 40 is bent upwardly and forwardly into a tab 42 which acts as a stop for the forward end of the tongue 16 when that is inserted into the base. As may be best seen in FIGURE 2, the tongue is locked into the base by means of a latch member generally indicated at 44.

The latch member 44 is formed of a sheet of metal having a pair of upturned sides 46. The distance between the outer surfaces of the upturned sides 46 is slightly less than the distance between the internal surfaces of the

sides

30 and 32 of the base so that the latch member may be supported between the

sides

30 and 32 with its surfaces 46 adjacent to the interior sides of the

members

30 and 32.

A shaft 48 has its opposite ends fixed within holes pierced in opposed points on the

sides

30 and 32 adjacent to the forward ends thereof. The shaft extends laterally across the width of the base and passes through a pair of holes formed in the sides 46 of the latch so as to rotatably support the latch with respect to the base.

The latch member 44 has a forward section 58 which is bent generally upward with respect to the base 28. so that the tongue 16 may be easily inserted under the latch member by pressing it against the lower end of the section 58. The latch member has a downwardly bent locking tab 60 pierced out of and extending from its intermediate section which is normally disposed with its lower end just above the base member 28.

' The base is surrounded on its top and sides by a cover member generally indicated at 70 preferably formed of plastic and being generally rectangular in shape with a closedtop 72 and four downwardly projecting sides 74. The front side of the cover is cut away as at 75 and four downwardly projecting sides 74. The front side of the cover is cut away as at 75 to allow the tongue to be inserted in the buckle member and the remaining front of the cover prevents the tongue from being accidentally inserted over the top of the latch section 58 and giving a false latch condition. The cover passes over the side members of the

base

30 and 32 and snaps thereon by means of a protrusion 76 which extends inwardly from the top sides and mates with recesses 78 formed on the rear ends of the

side plates

30 and 32. The fit of the tabs in the recesses allows the cover to be pressed over the sides of the base member and locked in position and it may be removed for inspection by pulling the 4 downwardly turned rear end of the cover 70 away from the

sides

30 and 32.

A rectangular aperture 80 is formed in the top of the cover member adjacent to its front end. A plastic pushbutton 86 having outer dimensions which are complementary to the aperture 80 is disposed therein. The planar surface of the pushbutton 86 is surrounded by a downturned edge 88 and which fits within the side walls 84 of the aperture. The tabs 90 extend from the four corners of the sides of the pushbutton 86 in sideward directions and are journaled in appropriate slots formed in the side surfaces of the downturned edge 84. These slots guide the pushbutton for vertical motion within the aperture 80 and the upper ends of the slots limit the upward movement of the pushbutton within the aperture.

A coiled compression spring 94 is secured between the cover top 72 and the latch member 44. The lower end of the spring 94 is retained by an upwardly extending tab 96 which projects from the rearward end of the latch member 44 and is seated within the interior diameter of the spring. The upper end of the spring '94 is retained by a projection '98 which extends downwardly from the top 72 of the cover member and is seated in the ID. of the spring at its upper end. The spring tends to rotate the latch member 44 in a counter-clockwise direction as viewed in FIGURES 2 and 5, into what will be termed a locked position wherein the locking tab 60 is in close proximity to the upper surface of the base member 28.

When the tongue member 16 is inserted through the opening 75 in the cover and under the uplifted section 58 of the latch member, its forward end abuts the bottom of the locking tab 60 and tends to rotate the latch member in a clockwise direction so as to lift the lock member 60 and allow the tongue member to be inserted against the stop 42. When in this position, the locking tab 60 is in position over the slot 26 in the tongue and enters that slot allowing the latch to rotate, under the spring bias, into its locked position which is shown in FIGURE 2.

In order to release the tongue member, pressure is put on the pushbutton 86 and its motion is communicated to the latch member through a cam-lever arrangement which is built about a transversely extending cam rod 100. The rod 100 is circular in cross section and has a length approximately equal to the distance between opposed inner faces of the

side walls

30 and 32 of the base. It passes through a pair of holes 102 formed in opposed points on the upturned side walls 46 of the, latch member 44. The holes 102 are slightly larger than the diameter of the rod 100, making a loose sliding fit therewith.

The two ends of the rod 100 have projecting eccentric pins 104 formed thereon. The pins are cylindrical and are both formed about an axis which is displaced with respect to the central axis of the rod 100.

The pins 104 are journaled in slots 106 formed in opposed points on the

side walls

30 and 32 of the base. The slots 106 are formed from the upper edge of the side walls and extend slightly less than half way down their depth. Their lower edges are rounded to approximately the same diameter as the pins 104. The distance between the outer ends of the eccentric pins 104 is equal to that between the outer walls of the

side walls

30 and 32 so that the pins lay in the side walls without extending appreciably beyond them.

A generally flat, elongated lever member 110, formed out of sheet steel, has one of its ends disposed in a shallow slot 112 formed in one side of the center of the rod 100, and is retained within the slot as by welding. The lever 110 has a central stamped depression 114, formed for stifiening purposes. It is generally straight along its length and its end opposite to that which is retained to the rod 100 is curved downwardly as at 116.

The angle and position of the slot 112 with respect to the rod 100 is such that the lever 110 extends upwardly in an inclined angle, so that the upper convex side of the curved end 116 abuts the lower end of the pushbutton 80. In this manner, the spring 94 acts through the latch member 44 and the lever 110 to normally maintain the pushbutton 86 at its extreme upper position. In this position, it is just below the top surface of the cover.

When the pushbutton is depressed by applying a force to its upper surface, it tends to press the lever 116 of the lever 110 downwardly. The convex curvature of the upper end of the lever acts to smoothly transfer the downward motion of the pushbutton into a rotation of the cam. This rotation is transferred to the rod 100 and the eccentric pins 104 act as its center of the rotation. The resultant eccentric rotation of the rod 100 tends to rotate or lift the latch member in a clockwise direction as viewed in FIGURES 2 and 5, because of the extension of the rod 100 through the holes 102 in the sides of the latch member. This acts to lift the locking tab 60 out of the slot 26 and to free the tongue 16 for retraction. This action is performed against the bias of the spring 94 which is compressed as a result of the tab 106 lifting during the rotation of the latch member.

The cam 100 and lever 110 act together as a lever of the first class, that is, one point of application of the force 116, is on the first side of the fulcrum (the journal of the pins 104 in the bottom of the slots 106), and the second point of force application defined by the center of the rod 100 within the holes 102, is on the other side of this fulcrum. Because the distance between the fulcrum and the end 16 is larger than the distance between the fulcrum and the center of the rod 100, a mechanical advantage is realized and the force exerted downwardly on the pushbutton results in a proportionally higher force on the lifting tab. Conversely, a relatively long downward motion of the pushbutton results in a relatively short motion of the latch member. Thus, a relatively large downward motion of the push'buttton is required to lift the lock member to allow the tongue to be retracted, obviating the possibility of a slight accidental deflection of the pushbutton allowing the unit to become unlocked. The relatively high force applied to the latch increases the probability that the buckle will be able to open after the imposition of stress forces as a result of an accident. A standard test which is applied to such belts is to determine if they open after tension forces in excess of the rated strength of the buckle have been applied to the belts. The force multiplication arrangement has been found to easily allow buckles formed in accordance with the present invention to pass such tests.

It is thus seen that the tongue may be easily locked in the buckle and securely retained therein until a definite force, acting through a fairly large distance, depresses the pushbutton so as to rotate the latch out of its locked position.

Having thus described our invention, we claim:

1. A seat belt buckle of the type described, comprising: a base having a planar surface; a latch member pivotably supported with respect to the base for rotation about an axis extending parallel to and transversely across the base; a locking section on the latch member adapted to extend adjacent to the base at one extreme rotation of the latch member; spring means biasing said latch member toward said extreme rotation; a pushbutton supported with respect to the base for motion toward and away from said planar surface; a cam having an eccentric section rotatably supported with respect to the base, said eccentric section movably engaging said latch member in such a manner as to pivot the latch member against the bias of the spring means so as to move the locking section away from the base, at such time as the cam is rotated; and means, disposed between the pushbutton and the cam and movable with respect to said pushbutton, operative to cause the cam to rotate as the pushbutton is moved toward the base.

2. A seat belt buckle of claim 1 wherein the means for causing the cam to rotate as the pushbutton is moved toward the base consists of an elongated lever having a first end connected to the cam and a second end abutting the pushbutton so that said second end is moved toward the base as the pushbutton is moved toward the base, thereby rotating said cam.

3. The seat buckle of claim 2 wherein the lever is connected to the cam at a point separated from its axis of rotation and is connected to the pushbutton by abutting the underside thereof.

4. The seat belt buckle of claim 3 wherein the cam is supported for rotation with respect to the base about a first axis extending parallel to the base and is connected to the latch member by means of said eccentric section which is journaled within said latch member.

5. The seat belt buckle of claim 4 wherein the base has a pair of upturned sides which rotatably journal the cam and the latch member has a pair of upturned sides which are disposed between the sides of the base and which have holes formed which journal the eccentric section of said cam.

6. The seat belt buckle of claim 5 wherein the pushbutton is supported for rotation in a cover member which has a generally flat top with an aperture formed therein for the pushbutton and at least one pair of downturned sides which are adapted to be dispose-d on the outer sides of the upturned sides of the base.

7. The seat belt buckle of claim 6 wherein the spring means for biasing the latch member constitutes a coiled compression spring supported between a surface of the latch member and the opposed undersurface of the cover member.

8. The seat belt buckle of claim 2 wherein the distance between the point of abutment of the pushbutton with the lever and the axis of rotation of the cam is greater than the distance between the connection of the cam to the latch member and the axis of rotation of the cam, whereby a relatively large movement of the pushbutton results in a relatively small movement of the latch member.

9. The seat belt buckle of claim 1 wherein the cam is rotatably supported with respect to the base about an axis which extends parallel to the base, and said eccentric section is rotatably supported in the latch member.

10. The seat belt buckle of claim 9 wherein the con nection between the cam and the pushbutton is made by a lever member having one end fixed to the cam and the other end in abutment to the pushbutton.

References Cited UNITED STATES PATENTS 2,995,792 8/ 1961 Morton.

3,189,966 6/1965 Craven.

3,203,064 8/ 1965 Murphy.

3,242,547 3/ 1966 Krengel.

3,270,388 9/ 1966 Humphrey.

BERNARD A. GELAK, Primary Examiner.

Claims

1. A SEAT BELT BUCKLE OF THE TYPE DESCRIBED, COMPRISING: A BASE HAVING A PLANAR SURFACE; A LATCH MEMBER PIVOTABLE SUPPORTED WITH RESPECT TO THE BASE FOR ROTATION ABOUT AN AXIS EXTENDING PARALLEL TO AND TRANSVERSELY ACROSS THE BASE; A LOCKING SECTION ON THE LATCH MEMBER ADAPTED TO EXTEND ADJACENT TO THE BASE AT ONE EXTREME ROTATION OF THE LATCH MEMBER; SPRING MEANS BIASING SAID LATCH MEMBER TOWARD SAID EXTREME ROTATION; A PUSHBUTTON SUPPORTED WITH RESPECT TO THE BASE FOR MOTION TOWARD AND AWAY FROM SAID PLANAR SURFACE; A CAM HAVING AN ECCENTRIC SECTION ROTATABLY SUPPORTED WITH RESPECT TO THE BASE, SAID ECCEN-