Hydraulic door checking mechanism

BACKGROUND OF THE INVENTION

In prior hydraulic door checking mechanisms for providing a door checking action in both directions of movement of the door it has been known to have a pair of hydraulic cylinders, each with a piston and a piston rod, one cylinder and piston serving to check the door action in one direction, and the other cylinder and piston serving to check the door action in the other direction. See, for example, Ellis Pat. No. 2,866,224. In many such structures the hydraulic fluid is discharged from the cylinders into the housing of the door control device while in others there is a self-contained hydraulic fluid system. In all such structures the added cost, increase weight and increased size resulting from two pistons and cylinders present disadvantages.

Due to the fact that in current building construction there is less space available than formerly for door control devices, more narrow devices have been devised such as the Door Closer Mechanism of Ellis Pat. No. 3,040,372. That structure employs a self-contained hydraulic system having a pair of pistons working in unison in a pair of side by side cylinders which are interconnected and have associated fluid reservoirs. In one form of the device of that patent the reservoirs, which supply makeup fluid to fill the space vacated by the pistons as they leave the hydraulic cylinders during door opening movement, are shown as expandible and contractible. The pistons of that door closer mechanism each have a unidirectional check valve which is operative on door opening to allow ready door opening movement, and there is no back check provided by the hydraulic system.

In providing back check in the structure of the present invention which has a single double acting piston in a single cylinder of a self-contained hydraulic system, the piston must have no check valve in it. In using such piston and at the same time in permitting rapid opening of the door with back check, while also seeking to use a flexible reservoir, the problem of blowing out, or rupturing, the flexible reservoir was encountered, due particularly to heavy fluid surges distributed to the reservoir during door opening movements. Ultimately I was able to overcome the problem, while yet providing back check and also stroke and latch control with a compact double-acting piston in a self contained hydraulic system by inventing the structure described and claimed hereinafter.

Accordingly it is an object of this invention to provide a closed circuit hydraulic door checking mechanism which is compact and simple in construction while yet providing the desired functions of back check and stroke and latch control.

It is another object to provide such a mechanism in the form of a readily removable and replaceable component for a door control device.

It is yet another object to provide a hydraulic door checking mechanism having a single cylinder and single double-acting piston with a single piston rod, and with a self contained fluid system, which has greater reliability of performance under varying conditions.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a small scale diagrammatic plan view of a door control device with its cover plate removed showing the location of the hydraulic cylinder of a hydraulic door checking mechanism, a spring and spring housing, and interconnecting linkage which joins the spindle of the door closing mechanism with the spring and with the piston rod of the hydraulic cylinder;

FIG. 2 is a semi-diagrammatic sectional view showing the hydraulic cylinder and associated structure in larger scale with the piston being disposed in the hydraulic cylinder in a position corresponding to a closed door position;

FIG. 3 is a view similar to FIG. 2 but showing the piston in a different position corresponding to an opening movement of the door, with the arrows indicating the direction of fluid flow in response to piston movement;

FIG. 4 is a view similar to FIG. 2 but showing the piston in a position corresponding to that part of the door opening movement wherein back checking begins to take place and by-passing of fluid around the piston through the by-pass line has just terminated;

FIG. 5 shows the piston in a position corresponding to approximately the end of the door opening movement and checking of the door, the arrows showing the path of fluid flow from one side of the piston to the other through the metering valve and reservoir;

FIG. 6 shows the piston in a position corresponding to a door closing movement with the movement of the door being checked and the fluid flowing in the direction indirected by the arrows through a metering valve and the reservoir;

FIG. 7 shows the piston in a position corresponding to the nearly closed position of the door when the metering valve for checking the closing movement of the door has been closed off by the piston and fluid flow is shown by the arrows as passing through the latch metering valve and passageway;

FIG. 8 is a plan view, on smaller scale, of a modified flexible wall portion of the reservoir; and

FIG. 9 is a plan view, also on smaller scale, of the cover plate for the reservoir.

GENERAL DESCRIPTION OF THE STRUCTURE

While there will be described below an exemplary embodiment of the invention, it will be appreciated that the invention lends itself to other embodiments or modifications within the scope of the appended claims.

Referring now to FIG. 1 of the drawings there is shown, diagrammatically and on small scale, a door control unit, indicated generally by the reference numeral 10, which has a housing 12 the cover plate of which has been removed in order to show the internal components. Interiorly of the housing 12 is shown a spring housing 14 for a spring 16 which has one end abutting against a wall 18 within the housing. At the right hand end of the spring, as viewed in FIG. 1, there may be connected a shaft 20 which extends through the center of the spring 16 and housing 14 and passes through an aperture (not shown) in the abutting wall 18. Shaft 20, when moved toward the left, compresses spring 16.

The hydraulic door checking mechanism, indicated generally by the reference numeral 22 comprises a hydraulic housing 24 out of which extends a piston rod 26 which

3,584,331 also extends through the abutting wall 18. Linkage, indicated generally by the reference numeral 28 serves to connect both the shaft 20 and piston rod 26 to the spindle 30, which spindle in turn is connected to an driven by a door (not shown) which is to be controlled by the door control unit 10.

Details concerning the foregoing structural elements and the manner in which they are supported in the housing 12 can be found in the co-pending application of William A. Czapar, Ser. No. 790,089, filed Jan. 9, 1969, for Door Control Means.

Considering now in greater detail the hydraulic door checking mechanism, reference should be made to FIGS. 2 through 7. The housing 24 is closed at one end as at 32 and defines a bore 34 which extends the long way of housing 24. A piston 36 has a close sliding fit within the bore 34 and is connected by a pin 38 to a piston rod 40. The piston rod 40 extends outwardly of the end of the housing 24 opposite from its closed end 32 and in so doing passes through an end cap indicated generally by the reference number 42. Cap 42 has a threaded portion 44 adapted to be secured within the end of the housing 24 which is internally threaded, as at 46· An end flange 48 on cap 42 bears against an end surface 50 of the housing and sealing gasket 52 is compressed between the flange 48 and end of the housing. The end cap 42 has a passageway or opening 54 extending through it and in alignment with the piston rod 40. Piston rod 40 passes through the passageway or opening 54 in extending outwardly of the hydraulic cylinder.

At the left end, as viewed in FIGS. 2 and 7, the end cap 42 is recessed as at 56 and receives a seal 57 which is in engagement with the piston rod 40. Toward the right end of the end cap there is disposed internally of the cap a bearing 58 for the piston rod 40. That bearing, together with a radially inwardly directed flange 60 of the end cap confines an O-ring type of seal 42 which also engages the piston rod 40. The inner space of the end cap 42 which surrounds the piston rod 40 and lies between the low pressure seal 57 and the bearing 58 is a low pressure chamber 64 which, for example, might retain a pressure in the area of 10 pounds per square inch, whereas the pressure inside the bore 34 to the right of the end cap, as viewed in FIGS. 2 through 7, may be in the area of 1000 pounds per square inch. The low pressure chamber 64 communicates with a reservoir, indicated generally by the reference numeral 66, by a passageway 68 in the end cap 42 which passageway communicates with a passage 70 in the housing 24 leading to one end of the reservoir 66. Because of the high pressure within the bore 34 it may cause a slight amount of hydraulic fluid to pass along the piston rod 40 toward the exterior of the housing. However, the fluid does not escape from the housing because the fluid reaches the low pressure chamber 64 from which it may pass to the reservoir rather than escaping outwardly of the housing 24 and its bore 34.

The reservoir 66 is formed of a recess 72 in the side of the side of the housing 24 over which recess is disposed and sealed a cover plate indicated generally by the reference numeral 74. The recess extends generally along the side of the housing and almost from end to end thereof. It will be observed that the recess 72 lies alongside the bore 34 and in a generally parallel relationship to it. Recess 72 is deeper at its central portion and at that central portion there is disposed a flexible wall portion for the reservoir, that wall portion being indicated generally by the reference numeral 76. The resilient wall port 76 is formed as a shallow recessed member having a peripheral flange 78 by which it is secured to the inner side of the cover plate 74 and is adapted to be explained toward that cover plate when the reservoir 66 fills with added liquid when the piston rod 40 enters the hydraulic system during a door closing operation. Consequently the reservoir 66 is a variable volume reservoir. The cover plate 74 is aperture, generally in its central portion, where it lies over the resilient wall portion 76. As may be seen in FIG. 8, on smaller scale, the flexible wall portion 76 may have its shallow recessed structure divided by a rib 80 to give the wall portion greater rigidity. The apertured cover plate 74, as shown on smaller scale in FIG. 9, may have its apertured center portion 82 provided with a portion which overlies the rib 80.

The entire hydraulic system is filled with hydraulic fluid and no air is used or desired. Prior hydraulic systems for door closer mechanisms which have used an air cushion in the hydraulic fluid reservoir suffer from several disadvantages among which are the greater dimensions which are required, limitations on the position in which the door closer mechanism may be placed, and faulty operation due to air becoming distributed in the system when the mechanism is shipped or handled.

At each end of the bore 34 there are a pair of passageways, such as passageways 84 and 86 at one end, and 84' and 86’ at the other end, which extend between the bore 34 and opposite ends of the reservoir 66. Passageway 84 has a back check metering valve 88 which is adjustable to permit greater or lesser flow through the passageway 84, and passageway 84' has a stroke metering valve 90 which is also adjustable. Passageway 86 communiactes with an overpressure safety valve 92 in the wall of the housing 24 and also leads to a ball check valve 94. If the housing 24 is to be used in a position inverted from that shown, then valve 94 should be spring loaded. Similarly passageway 86' leads to an over-pressure safety valve 98' in the wall of housing 24 and to a spring loaded ball check valve 96. It will be seen that metered flow of hydraulic fluid may pass from one side of the piston 36 to the other (with the direction of fluid depending upon the direction of movement of said piston) with the liquid flow passing, in series, through the reservoir 66.

A separate bypass line 98 has two openings leading to opposite sides of the piston during initial movement of the piston in a door opening movement and a spring loaded ball check valve 100 is disposed in the bypass line 98 to prevent flow through said line when the piston 36 is moving in a door closing direction. Said ball check valve 100 is disposed in a countersunk bore 102 in the housing 24 and that bore is closed by a ball closure member 104 which also serves as a seat for the spring 101 of the spring loaded valve 100.

To the right of the passage way 86', as viewed in FIGS. 2 through 7, there is a latch passageway 106 leading from the bore 34 through the wall of the housing 24 and an opening 108 back to the bore 34. This latch passageway 106 has a latch metering valve 110 which is adjustable. Valve 110 and passageway 106 permit hydraulic fluid to pass around the piston during the final closing movement of the door, for latching it, after the piston 36 has moved to cover the passageway 84' which contains the metering valve 90. Usually latch valve 110 is so adjusted as to let the door move just a little faster than previously in order that it will be sure to latch.

OPERATION OF THE HYDRAULIC DOOR CHECKING MECHANISM

Assuming now that a door to be controlled by the door control unit 10 of FIG. 1 is in its closed position but is then moved toward an open position, the spindle 30 which will be connected with the door will be rotated and by means of the connected linkage 28 will pull both the piston rod 26 of the hydraulic door checking mechanism and also the shaft 20 which will serve to compress the spring 16. FIG. 2 of the drawings represents the position of the piston 36 within the bore 34 when the door is closed and FIG. 3 represents the position of the piston as the door is beginning its opening movement. It will be observed that piston 36 never covers passageway 86'.

As the piston 36 and piston rod 40 move to the left, as viewed in FIG. 3, and away from passageway 86', passageway 84' then becomes uncovered. Bypass line 98

3,584,331 permits the bulk of the fluid ahead of the moving piston 36 to readily flow around the piston from one side to the other since the ball check valve 100 in line 98 is only lightly loaded toward its closed position and is readily overcome by the movement of the hydraulic fluid in the direction indicated by the arrows of FIG. 3. In this way no surge of fluid into the reservoir will occur, so there is no danger of damaging or destroying the flexible wall 76. Furthermore it will be observed that the bypass line 98 does not incorporate any portion of the reservoir 66 but is entirely independent of it, and therefore there are no liquid surges of the fluid from bypass line 98 into the reservoir which might damage the flexible wall, or diaphragm, 76 of the reservoir. While some fluid may tend to move through the passageway 84 and the metering valve 88, the bulk of the flow will be through bypass line 98 and will so readily flow that there is little resistance from it to the opening movement of the door.

When the door has been opened sufficiently that the piston has reached the position shown in FIG. 4, the piston will close off the bypass line 98 and back checking of the door will occur as fluid is then required to flow through the passageway 84 and metering valve 88, the reservoir 66 and past the ball check valve 96 and up through passageway 86' into the bore 34 on the opposite side of piston 36, as indicated by the arrows. This backchecking action continues as the piston further moves to the left as represented in FIGS. 4 and 5. FIG. 5 represents the position of piston 36 corresponding to the substantially fully open and checked position of the door and it will be observed that the bypass line 98 is still closed off at its left end by the piston 36. In the fully open position of the door the piston 36 never closes off passageway 84 or 86.

When the person opening the door releases it, the spring 16 of the door closing unit 10 (FIG. 1) then acts through the linkage 28 to close the door and to move the piston rod toward the right. The piston then moves from its FIG. 5 position toward the right whereupon the hydraulic fluid will flow through passageway 84' and the metering valve 90, the reservoir 66 and then past the ball check valve 94 through passageway 86 to the bore 34 on the other side of the piston, as shown by the arrows of FIG. 6. No flow of hydraulic fluid in the opening 108 or passageway 106 will occur during the greater part of the door closing movement. But when the piston reaches the position shown in FIG. 7, a position corresponding to the door having nearly reached its closed position, the piston will close off passageway 84' and uncover opening 108. Hydraulic fluid will then pass from the right hand side of the piston out of bore 34 only through the passageway 106 which now permits the flow of fluid since the position of the piston in FIG. 7 has uncovered the opening 108 at the far end of the passageway 106. The latch metering valve 110 in latch passageway 106 is adjusted to permit a somewhat faster flow of fluid than through the metering valve 90 so that there will be a slightly faster movement of the piston and door to assure latching of the door as it reaches its final closed position.

Referring now to the reservoir 66 and particularly the flexible wall portion 76, it will be observed as one retraces the opening and closing of the door and the corresponding positions of the piston 36 and piston rod 40 that when the piston rod has its greatest inward position in the bore 34 a substantial space is occupied by that piston rod and that means that fluid in the closed system must be transferred elsewhere. With the door in its closed position as represented by FIG. 2 it will be seen that the hydraulic fluid which is “displaced” by the piston rod 40 has been accommodated in the reservoir 66 by the movement of the flexible wall portion 76 toward the cover plate 74 thereby automatically providing an enlarged reservoir. As the piston moves during door opening movement, the piston rod increasingly passes out of the bore 34 and fluid which is then drawn in behind the moving piston is extracted from the reservoir. The flexible wall portion of the reservoir finally assumes a position somewhat corresponding to that of FIG. 5 when there is the least volume of the piston rod within the bore 34. When the door then returns toward its closed position it will be seen that the flexible wall portion 76 again moves toward the cover plate 74 as more and more of the piston rod 40 re-enters the closed fluid circuit and takes up space previously occupied by the hydraulic fluid. The overlying portion 82 of cover plate 74 will prevent the flexible wall portion 76 from bulging excessively. It can be seen therefore that a variable volume reservoir is provided. Because the reservoir has a variable volume by reason of the flexible wall portion, the reservoir may be completely filled with fluid and requires no internal cushion of air.

Since the reservoir is located alongside and generally parallel to the bore 34 in housing 24 the overall hydraulic housing can be much shorter than if the reservoir were located at one end or the other of the housing. Furthermore, by forming the reservoir partially by the housing 24 fewer structural parts are required thereby reducing the cost of both construction and assembly. The manner in which the hydraulic door checking mechanism may be readily removed from the door control unit for either repair or easy replacement is disclosed in the aforementioned copending application of William A. Czapar, Ser. No. 790,089, filed Jan. 9, 1969.

From the foregoing it will be understood that an advantageous and improved hydraulic door checking mechanism has been provided by this invention.