US3058146A

US3058146A - Pneumatic door check

Info

Publication number: US3058146A
Application number: US6297A
Authority: US
Inventors: Harrison Henry; Henry C Harrison
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-02-02
Filing date: 1960-02-02
Publication date: 1962-10-16
Anticipated expiration: 1979-10-16

Description

Oct. 16, 1962 H. HARRISON ETA]. 3,

PNEUMATIC DOOR CHECK Filed Feb. 2, 1960 2 Sheets-Sheet 1 Fig l Fig. 2. Fig-3v INVENTORS HENQT Hmrzlsw HENRY C. Hmmgou BYMMQQMZZ7 W ATTORNEYS Oct- 1 2 H. HARRISON ETAI.

PNEUMATIC DOOR CHECK 2 Sheets-Sheet 2 Filed Feb. 2, 1960 w o 6 m w 0 E m .m. WWW F. m m HC mm mm Hun Fig. 5 BYWQMfW ATTORNEYS 3,d58,146 Patented Oct. 16, 1962 3,058,146 PNEUMATIC DGDR QHECK Henry Harrison, R0. Box 117, Locust Valley, N.Y., and

Henry C. Harrison, 94 Bayview Ave, Port Washington, N.Y.

Filed Feb. 2, 1960, Ser. No. 6,297 16 Claims. (Cl. 16-66) This invention relates to pneumatic door checks and means for coupling pneumatic door checks with a door and an associated door frame. More particularly, this invention relates to an improved pneumatic door check which incorporates auxiliary means for allowing compressed gas to escape from the check at a pre-determined instant to assure proper closing of the door, and to an improved linkage between a door check and an associated door structure, which linkage allows for fully opening a door swingably mounted with respect to a door frame.

Various types of pneumatic door checks have heretobeen suggested for use in controlling closing movement of a door. Generally, the prior constructions provide a check cylinder with a piston reciprocally mounted therein. The cylinder is normally coupled to the door and the piston is normally coupled to the associated door frame so that the piston moves backward in the cylinder upon opening the door, and forward in the cylinder upon closing the door. Some means is provided, either as a part of the check or separate therefrom, for urging the door to closed position whereby once the door has been opened, it automatically swings toward closed position. The piston and cylinder arrangement, under the action of the means for urging the door closed, provides a compressed air cushion within the cylinder upon closing of the door which supposedly prevents the door from meeting the frame with a large impact. Normally, an adjustable outlet is also provided in the cylinder to allow air under compression to escape at a selected rate commensurate with the closing force applied to the door. When such arrangement is utilized for controlling a door, proper closing is, at best, achieved only when the door is opened to a position within a pre-determined rather small range of positions. If the door is opened further than the maximum position in the range to which the outlet has been adjusted, or not opened as far as the minimum position of the range to which the outlet has been adjusted, then either: (a) the door closes so slowly that it fails to operate an associated latch, locking device, or the like; or (b) the door swings shut so quickly that there is a severe impact of the door upon its frame; or (c) the door rebounds from a closing path of travel and then moves into the frame at an excessive speed. The adjustment of the outletv is a compromise for a limited range of opening positions. In addition to the above disadvantages of prior art constructions, the linkages heretofore suggested for coupling the door checks with the door frames commonly prevented opening the door beyond a position where the door is at right angles to the frame. In those cases where a coupling linkage permitting the door to open further is suggested, the structure of the linkage has been complicated or subject to buckling in improper directions which would prevent efficient functioning of the door check to which it was coupled.

Accordingly, primary objects of the present invention are: (a) to provide an improved pneumatic door check which assures proper control of door closing regardless of the position to which the door is opened, and (b) to provide an improved door check coupling which allows for opening the door through 180 and which prevents improper pivotal movement between coupled components.

In particular, a primary object of the present invention is to provide an improved pneumatic door check having a piston and cylinder arrangement as described above, and also incorporating valve means responsive to gas pressure within the housing, which valve means serves to relieve increased pressure at a pre-determined instant so as to assure proper closing of the door with which the check is used. Even more specifically, an object of this invention is to provide a door check as prescribed above and incorporating automatically-operable valve means which acts to relieve increased pressure in the cylinder at a predetermined door speed, so as to assure proper closing of the door with which the check is used.

Another object of the invention is to provide a door check in accordance with the preceding object, which check includes, as an integral part thereof, means for automatically urging the door to closed position, preferably in the form of a spring, and means for automatically taking into account the force of the spring so as to substantially eliminate acceleration of the door after the desired speed of closing has been reached, so that the door completes its closing at that predetermined desired speed.

A still further, and more specific object of this invention is to provide an improved door check as prescribed above, wherein the additional valve means for releasing increased pressure within the housing is carried within the door check and is operable upon selected movement between a piston of the check and a piston rod on which such piston is slidably mounted, which movement results from a change in pressure conditions within the housing.

Still another, and further object of the invention is to provide an improved door check in accordance with the preceding objects, which check is capable of being easily and inexpensively fabricated, and which check comprises relatively few components so as to assure extended trouble-free operation.

Another primary object of the present invention is to provide an improved door check coupling which allows for opening of an associated door through by pivota1 movement of coupled components, but which incorporates means for preventing improper pivotal movement of coupled components.

Still other specific objects of this invention with respect to the improved coupling are: (1) to provide a pivotal link having a cross-member adapted to bear against an edge of the door during opening and closing thereof; (2) to provide as a part of the coupling, a bracket adapted to be attached to the door frame, which bracket carries friction washers and pivot points engageable by legs of the pivotal link; and (3) to provide a link and bracket as prescribed in sub-paragraphs (1) and (2), which allow for springing the link into pivoting position on the bracket so as to avoid the necessity of utilizing tools to couple the components of the check together, or uncouple them. 7

Basically, and in its simplest aspects, the invention provides a door check comprising a housing preferably having an adjustable orifice, a piston reciprocal within the housing, means for coupling the housing to one portion of a door-door frame structure, and means for coupling the piston with the other portion of such structure, which components function to compress gas within the housing upon closing of the door. A valve means responsive to a selected pressure condition within the housing is incorporated as part of the check, and this valvemeans serves to relieve pressure Within the housing at a pre-determined door speed. The improved meansprovided by the invention for coupling the piston with the door structure-preferably comprises a bracket and associated pivotal link, which link has spaced apart arms adapted to be pivotally coupled with the bracket, and a cross-member carried between the arms which bears against a door edge during wide opening and clos- 3 ing operations and prevents improper pivoting between the link and a coupled piston rod.

The invention will be better understood, and objects other than those specifically set forth will become apparent, when consideration is given to the following detailed description of the exemplary embodiments of the invention. The description refers to the annexed drawings, wherein:

FIGURE 1 is a plan view of a door-door frame structure provided with the improved door check and door check coupling provided by this invention, and presents the door and check components in partially opened position;

FIGURE 2 is a plan view similar to FIGURE 1, but presents the door in fully opened position, and shows the disposition of check components under such condition;

FIGURE 3 is also a plan view similar to FIGURE 1, however, FIGURE 3 shows the door in closed position and the associated closed position of check components;

FIGURE 4 is a detailed fragmental view showing the operative relationship between (a) the coupling bracket, coupling link, and check piston rod constructed in accordance with the preferred embodiment of the invention, and (b) the associated components of the doordoor frame structure;

FIGURE 5 is a cross-sectional view of the improved door check provided by this invention, and presents the components thereof in the position occupied when the door to which the check is coupled is fully closed;

FIGURE 6 is a plan view, partially in section and similar to FIGURE 5, however, FIGURE 6 presents the components of the check in one of the positions they occupy when the door is moving from an open to a closed location;

FIGURE 7 is a detailed view of the valve means provided by this invention for releasing compressed gas from the check, and shows the position of the components of such valve means when it is open;

FIGURE 8 is a detailed fragmental view of the bracket and one end of a link which are parts of the improved coupling provided by the invention;

FIGURE 9 is a perspective view of a preferred form of link member provided by the invention;

FIGURE 10 is a plan view of a preferred form of washer utilized in the auxiliary valve means provided in accordance with the invention; and

FIGURE 11 is a perspective view of a preferred type of valve plug utilized in the auxiliary valve means of the invention.

Referring more particularly to the drawings, in FIGURE 1 the numeral 2 designates a door frame and the numeral 4 designates a door swingably mounted with respect to frame 2 by means of hinges such as that designated by numeral 66. The door 4 is movable from the fully closed position shown in FIGURE 3 to the fully open position shown in FIGURE 2.

Coupled between the door frame 2 and the door 4 is a door check device 8 comprising a check cylinder or housing 10 pivotally coupled with door 4 by means of hinge 18 and having a reciprocal check cylinder rod 12 extending beyond one end of the housing. The device also has a coupling linkage 14 and bracket 16 connecting the rod 12 with the frame 2. As is apparent from FIGURES l, 2 and '3, the check cylinder rod 12 moves into the housing as door 4 closes in on frame 2, and moves out of the housing as door 4 is moved to its open position. The coupling linkage 14 and associated bracket 16, and housing bracket 18 serve as means to operatively mount the check for the prescribed reciprocation of rod 12, and will be described in detail hereinafter. The important factor to understand initially is that the rod 12 moves in and out of the housing corresponding to closing and opening of the door respectively.

By referring to FIGURE 5, it will be seen that the rod 12 carries at its forward end 12 a piston 20 which has secured thereon a leather seal cup 22. The seal cup 22 has a skirt portion 24 which engages the side walls of the cylindrical housing 10 and slides therealong when the piston is moved within the housing 10. The detailed construction of piston components is explained more fully below, but it should be noted that the cup member 22 prevents gas from moving therepast rearwardly in the housing. Thus forward movement of the piston, and thereby the cup member, results in exerting a force on gas within the housing forward of the piston.

At the same time, it should be understood that withdrawal of the piston within the housing causes a flow of air past the skirt portion 24 of seal cup 22 into the space within the housing forward of the piston.

Communicating with the space between the piston and the forward end 10 of the housing, is a valve means 26. This valve means is preferably carried by the housin 10 at its forward end 10 and comprises a threaded aperture 28 and a screw 30 carrying threads cooperating with those on the aperture and having a recess 32 therein. Recess 32 which may be in the form of a slot, groove or diagonal hole extends through the threaded surface of the shank of screw 3% so that gas can pass out from housing 10 through the recess. Moreover, the size of the orifice defined by recess 32 can be adjusted by turning screw 30 so that its threaded shank moves into, or out from, the interior of housing 19.

While the door check provided by this invention can be operated with any fluid, it is suitable for compressible fluids, particularly air, which is preferred because sealing problems are avoided by using air.

In order to fully comprehend the invention, assume for the moment, contrary to the teachings of the invention, that the check plunger means, or piston 20, is rigidly secured on rod 12. If this construction is incorporated in a door check as described above, and such check is coupled with a door frame structure as shown in FIGURES 1-3, and the door is moving from open to closed position under the action of some urging means, then as the door closes the space between piston 20 and the forward wall 10' of the housing decreases. If the screw 30 is adjusted so that the air confined in such space can escape so rapidly that there is no substantial compression thereof, then the door meets the frame with severe impact, since the urging means, which usually takes the form of a spring, continuously accelerates the door during its closing travel, since no force is exerted on the door, or within the check, in opposition to the accelerating force of the urging means. On the other hand, if screw 30 is adjusted so that air cannot escape fast enough when the piston moves forward, then air is compressed between piston 20 and the forward end 10' of the housing, and such compressed air exerts a force opposing that exerted by the urging means. Assuming the outlet through recess 32 is sufliciently large to prevent compression of the air to an extent where it rebounds due to its elastic qualities, the door will shut relatively smoothly. However, the rate of compression and thereby degree of compression of the air depends on the extent to which the door was opened, because under the action of urging means, the velocity of closing of the door during compression depends on the time during which it is accelerated by the urging means and thereby the degree to which the door was opened. Accordingly, if the outlet through recess 32 is sufficiently large to prevent compression of air to an extent where it rebounds due to its elastic qualities, yet sufficiently small to allow for compression to a certain extent upon closing of a door that has been opened to a given position, then the same ad justment of the screw will not provide for proper escape and thereby proper limited compression when the door is opened to a substantially different position because the escape rate of the compressed air will have to be different. For example, if the door is opened further than the position to which screw 30 was adjusted, then the maximum closing velocity of the door during compression is increased, and the rate of compression is increased. Thus for proper closing, the outlet through recess 32 should be larger than when the door was opened to the previous position in order to allow entrapped gas to escape at a rate which prevents rebounding due to the elastic properties of the gas. However, the opening through recess 32 remains the same size, and thus the door will not properly shut regardless of the position to which it was opened.

Just as in the conventional door check action just described, a door check constructed according to the present invention compresses air by the closing action of the door, and exerts a reaction force against the door which opposes its closing motion. As long as the rate of closing of the door is high, the pressure of the entrapped air rises, and when the pressure gets sufficiently high, it slows the doors motion. However, eventually, as the door slows down, the rate of compression reaches a point where it drops below the rate at which air is escaping through the recess 32, and the pressure of the entrapped air within the cylinder begins to drop. For a given positioning of the orifice screw 30, the speed of the door at this point is substantially independent of the pressure of the entrapped air, because the volume rate of flow of air through an orifice is nearly independent of the pressure. In contrast to conventional door checks, the door check of the present invention provides a control system which automatically detects the condition when the pressure begins to drop and opens a valve which releases the entrapped gas or air so that the door can coast shut at a predetermined speed corresponding to the setting of the orifice screw 30.

Attention is now directed to the construction of piston 20 and piston rod 12. The control system or auxiliary valve means which releases the entrapped air in response to an incipient fall of pressure is preferably carried by piston 20 and cooperates with piston rod 12 as hereinafter explained. To fully comprehend the operation of the auxiliary valve means, a full understanding of the action of piston 20 in the construction illustrating this invention is helpful. Accordingly, attention is initially directed to the construction of piston 20 and piston rod 12 in the following paragraphs.

According to the preferred embodiment of the invention, piston 20 is not rigidly secured on rod 12, but is slidably mounted thereon. The rod 12 extends through a bore 34 in the piston, and abutment means 36, preferably in the form of an enlarged flared end, is provided on the piston rod 12. The piston 20 is provided with an outward bevel 38 at the forward end of bore 34 and this bevel cooperates with the flare 36 on the piston rod to prevent movement of the piston on the piston rod forwardly of the position shown in FIGURE 5. Spaced from the flare 36 carried at the forward end 12 of the piston rod, is a snap ring 40 which cooperates with a recess 42 in the rod. A washer 44 carried on rod 12 is disposed forwardly of ring 40, and a spring 46 extends between washer 44 and the circumferentially extending flange portion 21 of piston 20. The spring 46 continuously urges piston 20 forward on rod 12, however, when a pressure is applied to piston 29 in the direction of arrow A, the piston slides rearwardly on rod 12 and spring 46 is compressed as shown in FIGURE 6. Thus, it should be apparent that piston 20 is slidably or reciprocally mounted on rod 12, and that the piston can be displaced from its forward position on the rod when sufficient pressure is exerted on the piston to compress spring 46. As is evident from FIGURES 5' and 6, ring 40 serves as an abutment or stop means for preventing rearward movement of washer 44 along piston 12 beyond the forward face of the ring.

In addition to the spring 46, door checks constructed in accordance with the preferred embodiment of this invention include a spring 50 extending between washer 4 4 and the rearward end of housing 20. Spring 50 has a lower coeflicient of compression than spring 46 so that when pressure is applied to piston 2th in the direc- 6 tion of arrowA, washer 44 moves rearwardly and into engagement with ring 40 prior to the time that spring 4 6 is compressed.

It should be understood, however, that any suitable means may be used for urging the door closed without departing from the scope and spirit of the invention. For example, a spring separate from the door check may be coupled between the door and door frame to serve as the means for urging the door closed, and in such instance, the washer 44 might continuously engage ring 40, and different provision might be made to reduce the acceleration of the door, after release of the entrapped air, as will be hereinafter explained. However, preferably the urging means is an integral part of the check as presented in the drawings.

if the door check described above, and shown in FIG- URES 5 and 6, is coupled with a door and associated door frame as shown in FIGURES 1 through 3, then as the door is opened, piston rod 12 is drawn rearward-1y in housing 10. The flare 36 on end 12 of the piston rod engages the bevel 38 of piston 20 and piston 20 moves rearwardly with the rod. Similarly, washer 4 4- which is held in spaced relation from the flange portion 21. of the piston by spring 46, moves rearwardly, and as a result spring 50 is compressed between the washer 44 and the rearward end 10 of the housing. Preferably, the spring 50 is of suflicient size that it does not become fully compressed upon opening of the door to the maximum extent. Thus, spring 46 is not fully compressed during the door opening operation.

Once the door has been opened and released, the means for urging the door closed, namely, spring 50, pushes washer 44 and thereby piston 20 and rod 12 forward. This results in automatically moving the door to closed position. The forward force applied to piston 20 and piston rod 12, and through the coupling of housing 10, to the door, causes acceleration of the door as it moves to closed position. Thus, the piston 20 and rod 12 move forward in housing 10 at an accelerated rate. If the screw 31} is adjusted such that the opening through recess 3-2 is not suflicient to allow for escape of gas therefrom at a rate corresponding to the closing speed of the door, then the pressure of air compressed between piston 20 and the forward end 10' of housing 10 increases to a point where it is sufficient to push piston 20 rearwardly on rod 12 compressing spring 46. As soon as the door has been slowed to such a speed that the rate of escape of air is equal to the rate of compression, by the restraining force of the compressed gas in the housing as exerted between the coupling of the housing with the door and the coupling of the piston rod with the frame, the pressure of the compressed gas begins to drop, and thus piston 20 moves forwardly on rod 12.

As explained hereinbelow, the movement between the piston and the piston rod described in the preceding paragraph is used, according to the preferred embodiment of this invention, to operate the second or auxiliary valve means which releases the compressed gas as soon as the piston begins to move forward on the piston rod. Obviously, the instant at which the piston begins to move forwardly with respect to the piston rod is the instant at which the pressure of the entrapped gas begins to fall. As explained above, this instant corresponds to the time when the door has been slowed to a speed preselected by adjustment of the orifice 26 in housing 10.

Thus, it should be apparent that when the forward movement of piston 20 on rod 12 is utilized to open a valve, the compressed gas trapped in the housing will be released at the proper instant to allow the door to shut at a preselected speed. According to the invention, the second or auxiliary valve means is operated by such movement of the piston, so that the speed selected by adjusting screw 30 is the speed at which the door closes in upon its associated frame.

The auxiliary or second valve means which is responsive to a change in pressure within housing 10, or more specifically movement of the piston on the piston rod, includes, as shown in FIGURES 5, 6 and 7, an orifice member 52 having an aperture 54 centrally disposed therein, a support washer 56, a resilient U-shaped member 58, and a plug member 60. FIGURES l and 11 present the preferred form of

components

56 and 60 in detail.

As shown in FIGURES and 6, the orifice member 52 and support washer 56 are carried in an enlarged bore 62 in piston 20. Bore 62 is axially aligned with, and extends forwardly of, bore 34 with which piston rod 12 cooperates. The central portion of orifice member 52 is spaced from the central portion of support washer 56, and the outwardly flared ends 59, 59' of resilient U- member 58 extend through the aperture 57 in support washer 56. Plug member 60 floats within the resilient U-shaped member 53, and normally closes the aperture 54 in onifice member 52 because the flared ends 59, 59 of the resilient U-shaped member ride up within the aperture 57 in the washer 56. The flared ends 59, 59 of the U-shaped member preferably make a angle with the respective legs of the U, and extend to a point slightly below the underside of orifice member 52 so that there is some play between the tips of the ends and the underside of the orifice member.

The body of U-shaped resilient member 58 has a lateral dimension substantially equal to the diameter of a bore 70 centrally disposed in the forward end 12' of the piston rod 12, so that the valve means 80 functions as follows: when the piston 20 moves rearwardly on rod 12 to the position shown in FIGURE 6, the legs of the resilient U-member 58 frictionally engage the walls of bore 70 and the tips of the flared ends 59, 59' contact the underside of the orifice member. As the piston moves rearwardly, the support washer 56 no longer engages the flared ends 59, 59 of the resilient U-member 58, however, U-member 58 still retains the plug member 60 in closing engagement with the aperture 54- in orifice member 5 2 because of the frictional engagement of the legs of member 58 in bore 70.

After the components have moved rearwardly under the increased pressure, the pressure drops, and forward movement results as explained hereinabove. When piston 20 moves forwardly due to decrease in pressure of compressed gas, the resilient U'member 58 is frictionally engaged by the walls of bore 76, and thus does not initially move forward with the piston. The plug member 60 is freed of engagement with the aperture 52 so as to provide an escape outlet. The trapped air rushes out through the aperture 54-, and through the loose sliding fit of the piston on the rod. The effect of the escaping air is to move the piston still further forward, which opens the valve more and makes the escape of air more rapid. As should be apparent, the auxiliary valve means opens as soon as the pressure of compressed gas decreases. Thus, the valve is responsive to gas pressure within the housing, or a change thereof, so as to assure proper closing of the door. As should also be apparent, the opening of the valve is limited by the flared ends 59, 59 of the member 58, which ends engage the support washer 56. Thus, after releasing compressed gas, the valve closes as support washer 56 engages the flared ends 59, 59 of resilient member 58 and carries the member forward free of bore 70. The valve means thus closes prior tofinal closing of the door and is in condition for subsequent operation upon again opening the door. But equally important, is the fact that when the valve closes the rapid drop of air pressure ceases. This occurs when the pressure of entrapped air is approximately equal to the pressure exerted by the urging means, or spring 50, so that the force applied to the door for final closing is substantially zero. Accordingly, after the valve is closed, the door coasts shut at substantially constant speed.

Although the specific details of the housing construction, and the means by which the seal cup 22 is retained on the piston, form no part of the instant invention, the preferred construction is presented in FIGURES 5 and 6. The housing It) comprises a central tubular member 100, to which are secured

caps

102 and 164. Cap 102 has a crimp 106 in its skirt portion and cap 104 has a crimp 1118 in its skirt portion. These crimps cooperate with associated

crimps

110 and 112 in opposite ends of tubular member 108 to hold the caps in position at either end thereof. Cap 102 carries the orifice means 26, and cap 16 has an aperture therein through which piston rod 12 extends. The sealing relation between cap 102 and tubular member must be sufficient to prevent any substantial escape of air, however, the sealing relationship between cap 164 and member 190 can be loose.

The leather seal cup 22 is preferably retained on piston 28 by means of an L-shaped cup retainer 116 which has internal fingers which frictionally grip the adjacent wall of piston 20, and a ring-shaped surface bearing against a cup expander 118. The expander 118 serves to continuously press the skirt 24 of the cup outwardly and into engagement with the side walls of the housing.

he means for coupling the piston rod 12 with the door frame as provided by this invention is shown in detail in FIGURES 4 and 8. The coupling means comprises a bracket 16 having a U-shaped central portion 168, from which

feet

162, 162 laterally extend. Apertures 163 are provided in the feet to adapt the bracket for mounting on the frame by some suitable means such as screws 164-. A rivet shaft 166 projects from either leg of the U-shaped central portion 160 of the bracket, and

friction washers

168, 163 surround the associated ends of such shaft which project therebeyond. A pivotal link 170 which is preferably a tapered sheet metal

channel having legs

172, 172, and a cross-member 174, is pivoted about bracket 16. The

legs

172, 172 have apertures at either end thereof and are somewhat resilient. They are spaced apart so that one end of the link can be sprung onto the bracket with the apertures therein engaging the rivet 166 and the legs pressing against the friction washers 166, 168'. The opposite end of link 170 is coupled with the free end of piston rod 12 by means of a suitable bolt 173 extending through the apertures in that end of the link, as well as a bore in piston rod 12 spaced a short distance from the end of that rod.

The side of the link carrying cross-member 174 is tapered outwardly from its connection with piston rod 12 to its connection with bracket 16, as shown in FIG- URE 4, and the cross-member 174 of the link has a flat face 176 which is disposed adjacent the end of the door hinged to the frame via hinges such as that designated by numeral 6.

As is apparent from FIGURE 4, the door 4 is swingable with "respect to the door frame 2 about one edge 180 of the end 182 of the door. As the door opens, the link 170 acts first as a pure tension member. However, when the door approaches 90 open, the face 176 of crossmember 174 begins to bear against the back edge of the door, and the piston rod begins to turn out of line with the link. As the door opens further, the link continues to press and slide slowly on the back edge 184 of the door, and piston rod 12 pivots toward a right angle position with respect to link 170. The force of spring 50 increases as the door opens, however, the lever arm through which such force acts decreases so that the torque on the door stays within reasonable limits.

After the door is released and begins to swing shut, the piston rod 12 pivots in the direction of arrow B, and eventually moves to a position where the longitudinal axis of the link is aligned with the longitudinal axis of the rod. The friction exerted on the link by the friction washers 168, 168' presses the rod 12 into engagement with the cross-member 174 which serves as a stop means preventing improper pivoting of rod 12 past the crossmember in the direction of the arrow B. Accordingly,

the friction washers at the bracket, and cross-member 174 coact to maintain the rod in alignment with the link, and prevent buckling under the compression load of checking the doors closing motion.

It should be apparent that the cross-member extends along the link between arms 172 and 172' thereof a sufficient distance to prevent the free end of piston rod 12 from swinging therepast in the direction of arrow B, and that the spring clasping of the

legs

172, 172 of the link against the friction washers provides for smooth, noiseless friction-resisting pivoting of the legs about the axis of the rivet shaft 166 carried by the bracket. Moreover, with such spring clasping arrangement, the link can easily be detached from the brackets in the event it is desired to remove the door.

FIGURE 9 presents the link 14 in perspective, and by referring to that figure, it will be noted that the link is tapered outwardly from the end thereof adapted to cooperate with the piston rod to the end adapted to connect with the jamb bracket.

After reading the foregoing description of the exemplary embodiments of the invention, the fact that the stated objects have been successfully achieved should be apparent. Accordingly, I claim:

1. A door check for use with a door swingably mounted with respect to a frame therefor, comprising the combination of a housing, plunger means for compressing gas within said housing upon closing of said door, first valve means for allowing gas to at least leave said housing upon movement of said plunger means, second valve means operative to remain closed so long as gas pressure increases within said housing and independent of the magnitude of absolute pressure therein, but operative to open in response to a decreasing change in said housing pressure, and means for coupling said housing and said plunger with the door and the .door frame.

2. In a door check, the combination of a housing, plunger means reciprocal within said housing for compressing gas within said housing upon closing of said door, first valve means for allowing gas to at least leave said housing upon movement of said piston plunger means, and second valve means operative to remain closed so long as gas pressure increases within said housing and independent of the magnitude of absolute pressure therein but operative to open in response to a decreasing change in gas pressure within said housing for releasing gas from said housing.

3. In a door check, the combination defined in claim 2 wherein said plunger means comprises a piston rod, and a piston slidably coupled thereto, and wherein said second valve means is responsive to sliding movement between said piston and said rod in a given direction.

4. In a door check adapted for use with a swingably mounted door, the combination defined in claim 2 wherein said first valve means is adjustable and is carried by said housing, and wherein said second valve means is carried by said plunger means.

5. In a door check adapted for use with a door swingable between open and closed positions, the combination of a hollow housing, a piston reciprocal within said housing in response to opening and closing of the door, said piston co-operating with said housing to compress gas in a portion of said housing upon closing of the door, first valve means communicating with said portion of said housing for allowing gas to enter said portion of said housing upon opening of the door and for allowing gas to escape from said portion of said housing at a controlled rate upon closing of the door, and second valve means responsive to a decreasing change in pressure of compressed gas acting on said piston upon closing of the door for allowing said compressed gas to escape from said portion of said housing.

6. In a door check adapted for use with a door swingable between open and closed positions, the combination defined in claim 5 and further including a piston rod '10 for moving said piston in one direction upon opening of the door, and spring means carried within said housing for urging said piston in the opposite direction.

7. In a door check adapted for use with a door swingable between open and closed positions, the combination defined in claim 5 wherein said first valve means is adjustable to control the size of an orifice therein through which gas enters and escapes from said portion of said housing.

8. In a door check adapted for use with a door swingable between open and closed positions, the combination defined in claim 5 wherein said second valve means is carried by said piston.

9. In a .door check adapted for use with a door swingable between open and closed positions, the combination defined in claim 5 and further including a piston rod on which said piston is slidably engaged for moving said piston in one direction upon opening of the door, wherein said second valve means cooperates with said piston and said piston rod and is responsive to sliding movement of said piston on said piston rod in a direction opposite to said one direction.

10. In a door check adapted for use with a door swingable between open and closed positions, the combination defined in claim 5 and further including a piston rod for moving said piston in one direction upon opening of the door, and spring means carried within said housing for urging said piston in the opposite direction, wherein said first valve means is adjustable to control the size of an orifice through which gas enters and escapes from said portion of said housing, wherein said piston is slidably engaged on said piston rod, and wherein said second valve means cooperates with said piston and said piston rod and is responsive to sliding movement of said piston on said piston rod in a direction opposite to said one direction.

11. A door check for use with a door swingable with respect to an associated frame therefor, comprising a walled housing having a forward end and a rearward end, a piston engaging the walls of said housing and being reciprocal between said forward end and said rearward end of said housing, a piston rod cooperating at one end with said piston for sliding movement of said pison on said rod, and having the other end extending through the rearward end of said housing, first abutment means carried by said piston rod at a point spaced from said one end thereof, means cooperating with said abutment means and said piston for urging said piston toward said one end of said piston rod, second abutment means carried by said piston rod at said one end thereof, said piston cooperating with said second abutment means to prevent disengagement of said piston from said piston rod at said one end, an adjustable valve carried by said housing and communicating with the portion of said housing between said piston and said forward end of said housing, auxiliary valve means carried by said piston and cooperating with said piston rod for providing an outlet in the portion of said housing between said piston and said forward end of said housing in response to movement of said piston on said piston rod toward said one end of said piston rod, and means for coupling said housing and said other end of said piston rod with said door and the associated frame therefor.

12. A door check for use with a door swingable with respect to an associated frame therefor as defined in claim 11 wherein said piston has a portion thereof extending beyond said one end of said piston rod, said portion of said piston having a first bore therein, wherein said piston rod has a second bore therein aligned with the bore in said portion of said piston, and wherein said valve means comprises an orifice member having an aperture therein and disposed in said first bore, a support washer disposed in said first bore, at least the central portion of said washer being spaced from the central portion of said orifice member, a plug member adapted to open and close the aperture in said orifice member and extending through said support washer, and a resilient substantially U-shaped member having flared end-s disposed between said orifice member and said support washer, said resilient member normally urging said plug member into closing engagement with said aperture in said orifice member, said resilient member being engageable by said second bore when said piston slides on said piston rod away from said one end of said piston rod whereby when said piston slides toward said one end of said piston rod, said resilient member is frictionally held in said second bore and said plug member opens said aperture in said orifice member.

13. A connection between a door check having a reciprocal rod extending therefrom and an associated doordoor frame combination wherein the door is swingable through 180 about one edge of an end thereof into and out of closed position with respect to the frame and wherein said door check is coupled to said door; said connection comprising a bracket adapted to be mounted on the door frame; a link having one end adapted to be pivotally coupled to said bracket for pivotal movement about an axis parallel to said one edge of said door and having the other end adapted to be coupled to said rod; and a cross-member carried by said link and having an at least substantially fiat face disposed on the side of said link adjacent the frame, said cross-member extending a sufiicient distance along said link to prevent pivotal movement of said piston rod past said cross-member, and to bear against the edge of the end of the door opposite said one edge thereof when the door is moved from its closed position through an angle of more than 90.

14. A connection as defined in claim 13 wherein said link and said cross-member are a single unit comprising a tapered U-member with the legs of the U-member having apertures at their ends, and With the base of the U-member set back from the ends of the legs thereof, wherein said bracket carries friction Washers on opposite outer faces thereof and a shaft extending through and beyond said washers, wherein one end of each of the legs of said U-member springingly engage said washers, and the apertures therein cooperate with said shaft for pivotal movement of said U-member about said bracket, and wherein the other end of each of said legs is pivotally coupled with said rod.

15. In a door check assembly, the combination comprising a hollow casing, a piston reciprocal Within said housing in response to opening and closing the door, said piston cooperating with said housing to compress gas in a portion of said housing upon closing the door, first valve means communicating with said portion of said housing for allowing gas to enter said portion of said housing upon opening of the door and allowing gas to escape from said portion of said housing at a controlled rate upon closing of the door, second valve means responsive to a decrease in pressure of compressed gas acting on said piston upon closing the door for allowing said compressed gas to escape from said portion of said housing, means coupling said housing to the door, a bracket for mounting on the door frame, a link having one end pivotally coupled to said bracket for pivotal movement about the axis parallel to one edge of said door and the other end coupled to a piston rod operably secured to said piston, a cross-member carried by said link and having an at least substantially fiat face disposed on the side of said link adjacent to the door frame, said crossmember extending a sufficient distance along said link, to prevent pivotal movement of said piston rod past said cross-member, and to bear against the edge of the end of the door opposite said one edge thereof when the door is moved from the closed portion through an angle of more than whereby the door is swingable through 16. A door check for use with a door swingably mounted with respect to a frame therefor, comprising the combination of a housing, a piston reciprocally disposed within said housing for compressing gas within said housing upon closing of said door and a piston rod cooperating with said piston, first valve means for allowing gas at least to leave said housing upon movement of said piston, second valve means responsive to a change in gas pressure within said housing for releasing gas from said housing, means for coupling said housing with said .door, and means for coupling said piston rod with said door frame including a bracket adapted to be fastened to said door frame and a link pivotally coupled at one end to said bracket and pivotally coupled at its other end to said piston rod, said link having a stop means for preventing pivotal movement of said piston rod with respect to said link in one direction.

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