Patent Publication Number: US-6212827-B1

Title: Support arm

Description:
This application is a continuation of U.S. application Ser. No. 09/104,515, filed Jun. 25, 1998, now U.S. Pat. No. 6,041,548. 
    
    
     BACKGROUND 
     The present invention relates to linkages, and more particularly to pivoted linkages suitable for use with biasing elements such as gas struts. 
     Conventionally, lids or tops such as hoods, trunk lids or large container tops are provided with biasing elements that bias the lid or top to an open position. One such application is that of a lid that covers a pick-up truck bed. It is desirable to provide such a lid with a biasing element that assists the user in lifting the lid from a closed to an open position, and that supports the lid in the open position. 
     U.S. Pat. No. 5,556,403 discloses a lifting device for a spa cover. The spa cover is hinged along one side, and a gas strut is directly connected between the spa cover at one end and the spa frame at the other. 
     U.S. Pat. No. 4,452,015 discloses a device for balancing an automobile deck lid. In the disclosed device, a return lever includes two substantially perpendicular arms that are rigidly joined together. A gas strut connected at one end to the return lever and at the other end to the deck lid facilitates the opening and closing of the lid. 
     U.S. Pat. No. 3,561,161 discloses an automatic door closing device. In the disclosed device first and second pivoted links extend between a door frame and a sliding door. The link that is attached to the sliding door includes an extension that protrudes beyond the other link. A spring is mounted between the end of this extension and a bracket attached to the door frame to bias the sliding door closed. 
     SUMMARY 
     The present invention is defined by the following claims, and nothing in this section should be considered to be a limitation on those claims. 
     By way of introduction, the embodiment described below may be attached between the lid and the enclosed compartment of a truck bed to provide lifting forces tending to open and support the lid. The disclosed linkage includes first and second links that are interconnected at a pivot and are coupled to the lid and the compartment by first and second mounting elements, respectively. A biasing element such as a gas spring is secured to the first link at a first joint and to the second link at a second joint. The first and second joints are disposed on opposite sides of a line extending between the pivot and the second mounting element, and the second joint is disposed on the second link intermediate the pivot and the second mounting element. As described in detail below, by properly selecting the shape of the second link, lifting forces when the lid is closed can be adjusted with respect to lifting forces when the lid is open. Furthermore, the disclosed device is compact, and it allows the use of a relatively compact gas strut. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a first preferred embodiment of this invention. 
     FIG. 2 is a bottom view taken along line  2 — 2  of FIG.  1 . 
     FIG. 3 is a side view of the embodiment of FIGS. 1 and 2 installed on a lid in a closed position. 
     FIG. 4 is a side view corresponding to FIG. 3, showing the lid in an open position. 
    
    
     DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
     Turning now to the drawings, FIG. 1 shows a side view of a preferred embodiment of the support arm of this invention. The support arm  10  includes the first and second rigid links  12 ,  14  that are pivotably interconnected at a pivot  16  such that the links  12 ,  14  are free to rotate with respect to one another about the pivot axis P as shown in FIG.  2 . 
     A first mounting element  18  is secured to one end of the first link  12 , and a second mounting element  20  is secured to one end of the second link  14 . The term “mounting element” is intended broadly to encompass any suitable structure for securing the respective link to an adjacent structure. In this embodiment, the first mounting element  18  takes the form of a shaft and the second mounting element takes the form of an opening, though other mounting elements can be used. As best shown in FIG. 2, the first mounting element  18  secures the first link  12  to a mounting bracket  22  such that the first link  12  is free to pivot with respect to the mounting bracket  22  about an axis defined by the first mounting element  18 . The first mounting element  18  terminates in a ball  24  as discussed below. 
     As best shown in FIG. 1, the second link  14  includes a first portion  26  that extends to the pivot  16  and a second portion  28  that extends to the second mounting element  20 . The first and second portions  26 ,  28  meet at the second joint  34  described below. 
     A biasing element  30  which in this embodiment takes the form of a gas spring is mounted to the first and second links  12 ,  14  by first and second joints  32 ,  34 , respectively. In this embodiment, the first and second joints  32 ,  34  are both ball joints, and the first joint  32  includes the ball  24  of the first mounting element  18  described above. The biasing element  30  biases the first and second joints  32 ,  34  away from one another, and conventional gas springs are suitable. Other biasing elements including extension coil springs can be substituted. 
     As best shown in FIG. 1, the first portion  26  defines a first axis A 1  extending between the pivot access P and the second joint  34 . The second portion  28  defines a second axis A 2  extending between the second joint  34  and the second mounting element  20 . The first and second axes A 1 , A 2  form an obtuse angle α that faces the first link  12 . The obtuse angle α is preferably greater than 135° and more preferably about 150°. 
     Because the axes A 1 , A 2  are angled with respect to one another as shown in FIG. 1, the first and second joints  32 ,  34  are disposed on opposite sides of a line L extending between the pivot  16  and the second mounting element  20 . As shown in FIG. 2, the second joint  34  is positioned at an intermediate point along the length of the second link  14  generally between the pivot  16  and the second mounting element  20 . 
     As best shown in FIG. 2, a portion of the first link  12  is aligned with a first plane P 1 , a portion of the second link  14  is aligned with a second plane P 2 , and a portion of the biasing element  30  is aligned with a third plane P 3 . All three planes, P 1 , P 2 , P 3  are parallel to one another and perpendicular to the pivot axis P. As shown in FIG. 2, the plane P 3  is disposed intermediate the planes P 1  and P 2 . Thus, the biasing element  30  is disposed between the first and second links  12 ,  14 , both in a viewing direction perpendicular to the pivot axis P (FIG. 2) and in a viewing direction parallel to the pivot axis (FIG.  1 ). 
     As shown in FIGS. 3 and 4, the support arm  10  can be mounted to a pickup truck  50  including a truck bed  52  and a lid  54 . In this exemplary application, the lid  54  is pivotably connected to the truck bed  52  at a hinge  56 , the mounting bracket  22  is secured to the lid, and the second mounting element  20  is pivotably mounted to the truck bed  52  via a shaft  58 . For example, the lid  54  can have a length of six to eight feet. The biasing element  30  provides a biasing force tending to move the first and second joints  32 ,  34  away from one another, thereby tending to extend the support arm  10  to provide a lifting force tending to rotate the lid  54  about the hinge  56  to an open position. 
     The support arm  10  provides a number of significant advantages. First, because the biasing element  30  extends between the first and second links  12 ,  14  rather than between the truck bed  52  and the lid  54 , a shorter and therefore less expensive biasing element  30  can be used. Second, the support arm  10  with its pivot  16  provides support for the lid  54  and reduces stress on the hinge  56 . Third, the configuration of the second link  14  allows the designer to select the lifting force when the lid is in the closed position for a given lifting force when the lid is in the open position. Because the first and second portions  26 ,  28  are angled with respect to one another, and because the second joint  34  is positioned on the opposite side of the line L from the first joint  32 , the moment arm of the biasing element  30  about the pivot  16  is modified when the lid  54  is in the closed position and the support arm  10  is in the configuration shown in FIG.  3 . 
     As yet another advantage, because the biasing element  30  is positioned between the first and second links  12 ,  14  in both the viewing direction of FIG.  1  and the viewing direction of FIG. 2, a relatively compact assembly is provided that minimizes the space required for installation. Also, installation of the biasing element  30  on the truck  50  is simplified, because the biasing element  30  can be pre-installed on the links  12 ,  14 , as shown in FIGS. 1 and 2. 
     Simply by way of example, the following details of construction are provided in order to clarify the best mode of the invention. In this embodiment, the links  12 ,  14  are formed of stamped steel, for example, having a width of about 1 inch and thickness of about ¼ inch. Conventional nylon washers can be used at the pivot  16  and the first mounting element  18  adjacent the links  12 ,  14  and the mounting bracket  22 . Conventional steel washers can be used adjacent the nuts included in the pivot  16  and adjacent the mounting bracket  22 , and these nuts may be conventional {fraction (5/16)}-18, zinc-plated nylon insert lock nuts. The links  12 ,  14  and the mounting bracket  22  can be coated with any suitable finishing material. 
     Of course, many changes and modifications can be made to the preferred embodiment described above. For example, this embodiment is not restricted for use with truck bed lids, but can be used for a wide variety of applications where a lifting force is required. The links  12 ,  14  can be adapted in dimension and shape to fit the intended application, and various biasing elements can be used as described above. The ball joints may be replaced with other types of joints that allow the required movements, and the illustrated threaded fasteners can be replaced with other types of fasteners including riveted fasteners, adhesively secured fasteners, and the like. Of course, the mounting elements and the mounting bracket can be readily adapted as appropriate for the particular application. Materials, finishes, and details of construction such as the use of washers or nuts can all be modified as desired. 
     It is intended that the foregoing detailed description be regarded as an illustration of a few of the many forms that the present invention can take and not as a definition of the invention. It is only the following claims, including all equivalents, that are intended to define the scope of this invention.