Abstract:
An improved door closer is provided which has a back checking arrangement including a loosely held resilient cushion bar which is engaged by a metallic shield abutting sliding cam plates during a final few degrees of opening of a door to provide an increasing resistance against further opening of the door. The shield preferably engages the cushion bar approximately 4° prior to a normal full open position of the door. Selective thickness of the cushion bar provides either a 90° full open position of the door or a 150° full open position of the door without additional adjustment.

Description:
This is a continuation of application Ser. No. 376,401, filed July 6, 1989, which is a continuation-in-part of U.S. Ser. No. 070,024, filed on July 6, 1987, and both now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to closers for doors and, more particularly, to an automatic door closer with a back checking device. 
     There are currently available several types of door closing mechanisms which provide a means for regulating the opening movement of a door and to prevent an overextension of the door opening commonly referred to as back checking. For example, U.S. Pat. No. 4,064,589 to Bejarano et al discloses a door closer in which an adjustable valve 132 is provided to regulate the back checking of the door which provides an adjustable shock absorber for the door as it reaches the fully opened position. This patent also discloses the use of a cushioning pad 157 to cushion a rearward movement of the carrier plate against the rear wall of the cam housing upon abrupt opening of the door past a normal/full open position. However, no means of attachment for the cushioning pad are disclosed. 
     U.S. Pat. No. 3,675,220 to Jentsch discloses a hydraulic cushioning device screwed through the door closer housing at a rear wall of the door closer housing, wherein a door closer cam forces plate-like members against the hydraulic cushioning device to slow the final stages of opening of the door. Mechanical energy of the door is dissipated to slow the door opening by throttling hydraulic fluid passing from the hydraulic cushioning device into the door closer housing, during compression of the hydraulic cushioning device. 
     U.S. Pat. No. 3,701,180 to Jentsch et al discloses a door closer wherein a stud assembly comprising a compressible material replaces the hydraulic cushioning device disclosed in U.S. Pat. No. 3,675,220. Similar to U.S. Pat. No. 3,675,220, the stud assembly is screwed through the housing. 
     U.S. Pat. No. 3,246,362 to A. Jackson discloses a door closer which relies on a compression of springs 31 as a back checking restraint and also relies on engagement between a cam 51 and cam follower rollers 43, 44 and 45 to provide a stop at a full open position of the door. 
     A back checking device which comprises a loosely captured cushion bar which provides an increasing resistance to the opening of a door during the last few degrees of travel until reaching a normal full open position, is new to the art. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved means for back checking the opening of the door in a door closer of a type described above in which there is a cam plate which slides longitudinally within the body of the door closer as the door is open and closed. A cushion bar fabricated of a resilient material is easily, loosely captured at a rear wall of the housing. A metallic shield, which is engaged to two cam follower rollers and abuts the cam plates facing the cushion bar, compresses the cushion bar when the door is opened to within a few degrees of a normal full open position. Such a normal full open position generally is selected as either 90° or 105° relative to the plane of the door jam, or the door in a closed position. 
     When the door is opened to within the last few degrees of its permitted arc of travel, preferably approximately 4°, the shield will engage the cushion bar and further opening of the door will begin compression of the cushion bar. As the door is continued to be opened through its last few degrees of travel, resistance to such travel is increased due to compression of the cushion bar, thus, providing an effective back checking of the door movement. 
     This cushion bar arrangement provides the function of a back check valve without requiring expensive machining of the door closer body for the acceptance of a fluid-type valve and the necessary porting of hydraulic fluid as is required by the use of a reverse check valve such as that disclosed in U.S. Pat. No. 4,064,589, discussed above. 
     Also, the cushion bar arrangement of the present invention does not require expensive machining of the door closer body for the acceptance of screwed-in cushioning devices, such as disclosed in U.S. Pat. No. 3,675,220 and U.S. Pat. No. 3,701,180, discussed above. The deletion of devices which must be screwed into the door closure housing further provides the advantage of avoiding leakage problems, since the interior of the door closer housing is filled with a hydraulic fluid under pressure. Threaded connections into the door closer housing invite leakage problems. 
     As mentioned above, the cushion bar is loosely captured within the door closer housing at the rear wall of the housing. As opposed to adhesively or mechanically fixing the cushion bar to the rear wall of the housing, this arrangement provides an efficient and economical approach to assembly or to replacement of the cushion bar. Additionally, two interchangeable cushion bars are provided in the present invention which provide normal full open door angles of 90° or 105°. To select a normal full open door angle, no other adjustments are required beyond simply selecting the proper cushion bar. 
     The present invention can be utilized in any door closer in which the cam plates slide within the door closer body and have a position close to a wall of the closer body. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top view of a door closer embodying the principles of the present invention which is enclosed within a door header and communicates with a door; 
     FIG. 2 is a partial sectional view of a door closer embodying the principles of the present invention showing the position of the cam plates when the door is nearly in the full open position; 
     FIG. 3 is a partial sectional view of the door closer in the full open position; 
     FIG. 4 is a partial side sectional view taken generally along the lines IV--IV of FIG. 3; and 
     FIG. 5 is a partial side sectional view taken generally along the lines IV--IV of FIG. 3 showing an alternate embodiment of a cushion bar. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention consists of an improved door closer and is illustrated in an embodiment of the spring actuated, hydraulic-pot type, such as that disclosed in U.S. Pat. No. 3,246,362, which disclosure is incorporated herein by reference. The present invention provides for an improved back checking arrangement to provide a positive back checking function without the complexity and cost of a fluid-type valve. 
     A door closer embodying the principles of the present invention is shown generally at 10 in FIGS. 1-4; FIG. 1 illustrating the closer 10 mounted in a concealed manner in the header portion of a door frame and illustrating the closed, nearly full open and normal full open positions of the door. 
     FIGS. 2-4 show the closer in more detail where it is seen that the closer has a housing or body 12 formed of top and bottom walls 13 and 14, side walls 15, and a rear end or back wall 16, the other end wall being provided by a pair of plug members 17. The entire hollow portion within the housing forms a reservoir for a supply of oil or other hydraulic fluid. A central partition 18 extends partially in from one end, the partition and the side walls 15 forming a pair of hollow cylinders 19 for a pair of pistons 20. 
     The bottom wall 14 is provided with a threaded opening in which is engaged a threaded cover plate 21, the plate having a boss 22 with a central opening 23. Extending through the opening is the spindle or door pivot member 24, this member having a non-circular end portion 24a for attachment to a door, such as for reception in a non-circular hole in a door hinge arm 20. The member 24 also includes a cylindrical portion 25 journaled in a ball bearing 26, a pair of shoulder or collar portions 27 and 28, and an end cylindrical portion 29 journaled in a ball bearing 30. An annular oil seal 39 is provided around the portion 25. 
     The closer is provided with a pair of coiled springs 31, one end of each bearing against one of a pair of internal wall portions 32, the other end bearing against one of the pistons 20. Means are provided for operably connecting the springs to the spindle member 24 and, as shown in the drawings, these means may include a pair of spaced cam plate members 35 and 36, each provided with a slot 37, 38 within each of which is received the appropriate one of the shoulders 27 and 28. A piston rod 40 is connected at one end to each of the pistons 20 by means of a pin 41. The other ends of the rods 40 are secured to the plates 35 and 36 by means of pins 42. The plates 35 and 36 are further spaced apart by means of three cam follower rollers 43, 44 and 45 mounted for rotation on respective shafts 48, 49 and 50. A cam 51 is carried on a spindle member 24 between the shoulder portions 27 and 28, the cam having a cam surface 52 with a pair of hold-closed recesses 54. Valve means 55 are provided in the central partition 18 defining the cylinders 19 to regulate the door closing and latching speeds as is discussed in greater detail in U.S. Pat. No. 3,246,362. FIG. 2 shows two separate valve members utilized for regulating the closing and latching speeds, but the present invention can also be utilized in single valve closers. 
     The present invention provides an improvement in regulating the back checking of the door closer, that is, regulating the amount of travel of the door in the opening direction. 
     The back checking arrangement provided by the present invention is illustrated generally at 60 and comprises a cushion bar 62 which is in the form of a pad of elastomeric material which abuts the back wall 16 of the housing on one side and abuts a metallic shield 64 on another side opposite the back wall 16. A pair of short, opposed walls 68, 70 project inwardly from the side walls 15 of the closer body to provide a pocket 72 in which the cushion bar is captured. Separate retaining means are not required to hold the cushion bar 62 in place. 
     The metallic shield 64 is a generally C-shaped member and comprises a generally rectangular bearing portion 64a and arcuate clasp portions 64b, 64c formed of a resilient material, such as spring steel. The bearing portion 64a abuts a rear edge or face 74 of the plates 35, 36 and faces the cushion bar 62. The arcuate clasp portions 64b, 64c are connected to, or integral with, the bearing portion 64a, one at each end of bearing portion 64a. The arcuate clasp portion 64b surrounds an outward portion of a circumference of the cam follower roller 43 and the other arcuate clasp portion 64c surrounds an outward portion of a circumference of the cam follower roller 44. The arcuate clasp portions 64b, 64c surround the circumferences of the cam follower rollers 43, 44 to an engagement angle 64d, sufficiently greater than 90° to prevent the shield from inadvertently disengaging the cam follower rollers 43, 44. The engagement angle 64d is measured between a line drawn from the center of the cam follower roller 43 toward and perpendicular to the bearing portion 64a and a line from the center of the cam follower roller 43 to an extreme end 64e of the arcuate clasp portion 64b. A similar method is used to draw the angle 64d for the arcuate clasp portion 64c, as shown in FIG. 3. The engagement angle 64d is therein measured between a line drawn from the center of the cam follower roller 44 toward and perpendicular to the bearing portion 64a and a line from the center of the cam follower roller 44 to an extreme end 64f of the arcuate clasp portion 64c. The engagement angle 64d being greater than 90° but less than 180° permits the shield 64 to be snapped onto cam follower rollers 43, 44 and removably retained thereon. 
     The thickness of the cushion bar is selected such that as the door is moved to an open position, and as rotation of the cam 51 riding on the follower rollers 43 or 44 causes the plates 35 and 36 to move rearwardly, the shield 64 will engage the cushion bar 62 when the door reaches an opening angle α of approximately four degrees less than a full open position for the door. Such a nearly full open position is illustrated at 76 in FIG. 1. As the opening of the door continues, the continued rearward movement of the cam plates 35 and 36 and the shield 64 will cause the cushion bar 62 to compress, thus, increasing the resistance to further opening of the door. This resistance will increase through the final four degrees of opening until full compression occurs at the normal full open position, illustrated at 77, thus, preventing the door from opening any further. 
     Since the cam plates 35 and 36 are metallic, the metallic shield 64 is provided both to distribute the forces presented by the rear faces 74 of the cam plates across a larger surface area of the cushion bar as well as to prevent wear of the cushion bar by engagement with the plates. Since the cushion bar 62 is relatively loosely held in the pocket 72, it can be readily removed and replaced if excessive wear does occur. 
     A further inventive feature of the present invention is an interchangeability of cushion bars to modify a normal full open door angle β. The normal full open door angle β is an angle between the door closed position 76a and the normal full open position 77. Industry custom makes two maximum door opening angles desirable, 90° and 105°. 
     FIG. 4 shows the cushion bar 62 comprising a generally semi-circular or semi-oval cross section. The cushion bar 62 comprises a compression thickness which corresponds to a normal full open door angle of 105°. An alternate embodiment of the cushion bar 62 is shown in FIG. 5, wherein an alternate cushion bar 62a comprises a full circular or full oval cross section with a compression thickness corresponding to a normal full open door angle of 90°. The invention provides interchangeability of these two cushion bars 62, 62a for selection of normal full open door angles. No further adjustments of the back checking arrangement are required to select between 90° or 105°, thus, misadjustments are prevented. 
     Thus, it is seen that there is provided an improved door closer which has an effective back checking arrangement, which provides the functions of a back check valve without requiring the machining and cost of a fluid-type valve but which does provide a positive back checking function and which provides an increasing resistance to opening during the final few degrees of opening of a door. Such a back checking arrangement can be utilized in any door closer in which there is a sliding or moving member which can engage the resilient cushion bar during a final few degrees of opening movement. 
     As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.