US3302531A - Elevator control system - Google Patents

Description

Feb. 1967 D. J. ARBOGAST ETAL 3,302,531

ELEVATOR CONTROL SYSTEM Filed Aug. 5, 1964 I34 r gg 1 10 74 wn 1/ 105 10s 1/; I35 Fla ,3 1/5 10/ I36 I27 '5 I92 Fm, @Wr WV/L- L iheir ATTORNEYS United States Patent 3,392,531 ELEVATOR CONT RGL SYSTEM Duane I. Arhogast, Olive Branch, and Lawrence F. Jaseph and Richard W. Green, Memphis, Tenn, assignors to Dover Corporation, Memphis, Tenn., a corporation of Delaware Filed Aug. 3, 1964, Ser. No. 386,829 Claims. (Cl. 91-446) This invention relates to a constant flow control device and more particularly, to a control means to be used in a hydraulic elevator system for maintaining a constant lowering speed of the elevator car regardless of load variation in the car.

Hydraulic elevators are commonly equipped with a jack cylinder and an elevator car plunger reciprocable therein. For raising the elevator car, hydraulic fluid is supplied under pressure to the jack cylinder by means of a pump, and for lowering the car, the hydraulic fluid, which is under pressure due to the weight of the plunger and the loaded elevator car supported thereby, is con trollably returned from the jack cylinder to a reservoir through a lowering valve. In the past there has been considerable variation in the speed of descent of the elevator car in accordance with the load therein, inas' much as heavier loads force the hydraulic fluid through the lowering valve at a higher volumetric rate of flow. Furthermore, variations in speed of descent prevent the elevator car from stopping consistently level with the desired landing.

In Patent Nos. 3,020,891 and 3,020,892, both issued February 13, 1962, means are disclosed for overcoming the above-mentioned difficulties by providing two regulated speeds of descent, a normal lowering speed and a relatively slow levelling speed, the latter being used as the elevator car approaches a floor at which it is to stop. Both patents disclose the use of two principal valve assemblies: a controlled valve to open to one of two fixed positions, corresponding to the two speeds of descent, to throttle the flow of hydraulic fluid therethrough and cause a pressure drop which varies with the rate of the flow dependent upon the load of the elevator car; and a regulator valve controlled by this pressure drop to open or close to the degree necessary to maintain the desired flow. In both patents it is the controlled valve which closes to form a fluid-tight seal when no flow is desired, but the regulator valve, which senses the pressure upstream of the controlled valves, must also have zero leakage under steady state conditions. Furthermore, inasmuch as the fixed positions of the controlled valve are adjustable, this valve is of relatively complex construc tion.

The present invention overcomes the disadvantages of the above-mentioned patents by providing a controlled valve which never closes, but only assumes one of two fixed positions corresponding to the two speeds of descent. It is only the regulator valve, which is located downstream of the controlled valve, which makes a fluidtight seal. This permits the controlled valve to be of very simplified construction.

The invention is more fully explained in the following detailed description of an exemplary embodiment, this description being illustrated by the accompanying drawings, in which:

FIGURE 1 is a diagrammatic view of a hydraulic elevator system, including the control means of the present invention;

FIG. 2 is an enlarged sectional view of the control means of FIG. 1 taken on a vertical plane through the middle thereof; and

FIG. 3 is a sectional view of an alternative embodiment of one of the control elements of FIG. 2.

3,302,531 Patented Feb. 7, 1967 FIG. 1 illustrates a typical hydraulic elevator system with which a lowering control means 10 is adapted to be used in accordance with the present invention. An eleva tor car 11 is supported by a plunger 12 reciprocably mounted in a hydraulic jack cylinder 13, suitable packing means (not shown) being provided at the top of the cylinder 13 to prevent the escape of hydraulic fluid from between the cylinder 13 and the plunger 12. A conduit 14 communicates the interior of the jack cylinder 13 directly with the control means 10 and through a suitable check valve 16 with a hydraulicpump 15. The pump is driven by a prime mover 17 such as an electric motor or the like. A discharge conduit 18 connects the control means 10 with a reservoir 19. Hydraulic fluid may be supplied to the pump from the reservoir 19 through a conduit 20.

When the elevator car 11 is to be raised, hydraulic fluid is taken from the reservoir 19 by the pump 15 and forced through the check valve 16 and the conduit 14 to the jack cylinder 13, the lowering control means 10 being sealed against flow therethrough. When the elevator car is to be lowered, the hydraulic fluid in the jack cylinder 13 is permitted to flow through the control means 10 to the reservoir 19. As will be explained in detail hereinafter, the control means 10 may be controlled to permit the elevator car 11 to descend at a predetermined normal lowering speed or a predetermined relatively low levelling speed. Moreover, the control means 10 may be sealed against fluid flow therethrough to bring the elevator car to a complete stop.

Turning now to FIG. 2, the lowering control means 10 includes a casing 21 which forms an inlet chamber 22, an intermediate chamber 23, and a discharge chamber 24. There is an inlet port 25 by which the inlet chamber 22 may be connected to the conduit 14, and a discharge port 26 by which the discharge chamber 24 may be connected to the discharge conduit 18.

A speed control valve 27 includes a cylindrical plug 28 which is slidably mounted in and in close fitting engagement with port or passageway 29 between the inlet chamber 22 and the intermediate chamber 23. The plug 28 is provided with a plurality of shaped ports 30 extending from the lateral surface of the plug to its end surface exposed to the intermediate chamber 23, whereby axial movement of the plug 28 varies the size of the effective passageway between the inlet chamber 22 and the intermediate chamber 23. Connected to the plug 28 by a stem 31 is a piston 32 which is slidably mounted in a bore 33 formed in the casing 21. The surface of the piston 32 remote from the plug 28 is exposed to a chamber 3-, which is closed by a cap 35, a gasket 36 and a plurality of screws 37 providing a fluid-tight seal therefor. A compression spring 38 biases the valve 27 toward the closed position, or to the left as viewed in FIG. 2. An adjustable stop screw 39, mounted in the cap 35, limits the travel of the valve 27 in the opening direction. Another adjustable stop screw mounted in the casing 21 limits the travel of the valve 27 in the closing direction. The stop screws 39 and 40 are locked by the nuts 41 and 42, respectively, and are secured against fluid leakage by the gaskets 43 and 44 and cap nuts 45 and 46, respectively.

A regulator valve 47 includes a cylindrical plug 43 which is slidably mounted in a port or passageway 49 between the intermediate chamber 23 and the discharge chamber 24. The plug 43 is provided with a plurality of shaped ports 50 extending between the lateral surface of the plug and its end surface exposed to the discharge chamber 24. The port 49 is beveled to form a seat at 51, and the plug 48 is formed with a laterally extending flange 52 adapted to cooperate with the seat 51 to seal the port 49 against fluid flow from the intermediate chamber 23 to the discharge chamber 24. Connected to the plug 48 by a stem 53 is a piston 54 slidably mounted in and 1n sealed relation to a passageway 55 between the inlet chamber 22 and the intermediate chamber 23. Coaxial with the passageway 55 is an opening 56 formed in the casing 21. The opening 56 is closed by a plate 57, a gasket 58 and a plurality of screws 59 insuring a fluid-tightseal. A stop 60, which may be adjustable if desired, limits movement of the valve 47 in the opening direction (to the right as viewed in FIG. 2) when engaged by a recessed surface 61 in the piston 54. Access may be had to the valve 47 by removing the plate 57.

A chamber 62 communicates with the discharge chamber 24 through a bore 63 which is in spaced relation to the port 49. Slidably mounted in the bore 63 is a piston 64 having a boss 65 extending into the discharge chamber 24 and adapted to bear against the plug 48. The side of the piston 64 exposed to the chamber 62 is recessed at 65a to seat one end of a compression spring 66, which is preferably of a low rate, or limber. The chamber 62 is closed by a cover 67, a gasket (not shown) and a plurality of screws 68 insuring a fluid-tight seal. An adjusting screw 69, mounted in the cover 67, supports a spring carrier 70 by means of which the spring 66 is maintained in compression. The force of the spring 66 acting through the piston 64 urges the valve 47 in the opening direction. The adjusting screw 69 is locked by anut 71 and secured against leakage by a gasket 72 and a capiiut 73.

The speed control valve 27 may assume one of two fixed positions, as it abuts the stop screw 39 or 40, to provide two degrees of opening between the inlet chamber 22 and the intermediate chamber 23 to provide the normal lowering speed descent or the relatively slow levelling speed descent of the elevator car 11, respectively. The position taken'by the valve 27 is determined by the direc tion of the resultant force thereon of the forces produced by the pressures in the chambers 22, 23 and 34 as well as by the compression spring 38.

The valve 47 may be seated as illustrated in FIG. 2 to prevent the flow of hydraulic fluid through the control means 10, when the closing forces produced by the pressures in the chambers 22 and 23 exceed the opening forces produced by the compression spring 66 and the pressure in the chamber 62; or it may open to the degree necessary to balance the opening force provided by the compression spring 66 and the closing force due to the pressure differential in the chambers 22 and 23, as will be explained in detail hereinafter.

The desired positions for the valves 27 and 47 are selected by means of control elements or devices 74 and 75, respectively. Briefly, to place the valve 27 in the position of minimum opening as illustrated in FIG. 2 corresponding to elevator levelling speed, the control device 74 connects the chamber 34 with the inlet chamber 22. With the valve 47 open to permit fluid flow through the ports 30, the forces urging the valve 27 in the closing direction, resulting from the relatively high pressure in the chambers 22 and 34 as well as from the compression spring 38, exceed the opening force on the valve 27 resulting from the relatively low pressure in the chamber 23. When the valve 47 is in the closed position, the pressures in the chambers 22 and 23 are the same and the spring 38 tends to keep the valve 27 in the mini-mum opening position. The control device 74 causes the valve 27 to shift to a position against the adjusting screw 39, corresponding to the normal lowering speed of the elevator car 11, by connecting the chamber 34 with the discharge chamber 24. Under these conditions the opening force on the valve 27 resulting from the relatively high pressure in the chamber 23 exceeds the closing forces resulting from the relatively low pressure in the chamber 34 and from the compression spring 38.

The control device 75 normally causes the valve 47 to assume the closed position illustrated in FIG. 2 by connecting the chamber 62 with the discharge chamber 24.

The closing force on the valve 47 due to the relatively i pressure in the chambers 22 and 23 exceeds the openin forces due to the relatively low pressure in the chamber 62 and due to the compression spring 66- T0 Permlt the elevator car 11 to descend, the control device 75 connects the chamber 62 with the intermediate chamber 23. Under these conditions the valve 47 opens u t the Opening force due to the spring 66 is balance-d by the closing force d to the pressure differential between the chambers 22 and 23, inasmuch as there is zero resultant static force on the plug 48 and the piston 64 resulting from the pressures in the chambers 23, 24 and 62, notwithstanding the fact that, when there is flow through the control means 10, there will be dynamic forces on the plug 48 and the piston 64 in one direction or the other, which may be rendered insignificant by properly shaping the ports 50.

The control device 75 comprises a body 76 having two concentric chambers 77 and 78 of diiferent diameter to receive a spool valve 79, the larger end of Which forms a piston 80 slidably received in the chamber 77 and the smaller end of which is formed with two lands 81 and 82 slidably fitted in the chamber 78. An intermediate portion of the spool valve 79 is beveled to form a seating surface 83 adapted to make a fluid-tight seal between the chambers 77 and 78. The valve 79 is urged to its closed position illustrated in FIG. 2 by a compression spring 84. Hydraulic fluid may flow from the chamber 78 through a port 85 past an adjustable needle valve 86 through a conduit 87 to the chamber 62. Return flow from the chamber 62 may flow through the conduit 87 past a ball valve 88 to the port 85. Direct communication is provided from the chamber 78 through a port 89 to a conduit 90, while a port '91 in this chamber 78 leads past an adjustable needle valve 92 to the conduit 90. The conduit communicates through a conduit 93 with the discharge chamber 24. The ports 89 and 91 are on opposite sides of the land 81 when the valve 79 is in the position illustrated in FIG. 2. A port 94 in the end of the chamber 77 adjacent the chamber 78 communicates with the intermediate chamber 23 by a conduit 95. A port 96 at the opposite end of the chamber 77 communicates with the conduit through a restricted orifice 97, and is connected by a passage 98 past a solenoid valve means 100 having a plunger 99 to the conduit 93 leading to the discharge chamber 24.

The control device 74 includes a body 101 having two concentric chambers 102 and 103 of diflerent diameter to receive a spool valve 104, the small end of which is formed with a cylindrical land 105 which is received within the chamber 103. Projecting from the land 105 is a beveled surface 106 which is adapted to make a fluidtight seal at a port 107 in the chamber 103. The other end of the spool 104 is formed into a piston 108 which is slidably fitted in the chamber 102. A compression spring 109 urges the spool valve 104 to the closed position. The port 107 communicates past an adjustable needle valve 110 with the conduit 93 and then to the discharge chamber 24, while another port 111 in the chamber 103 communicates through the conduit 112 to the chamber 34. A port 113 in the end of the chamber 102 remote from the chamber 103 communicates by a passage 114 past a solenoid valve means 116 having a plunger to the conduit 93 leading to the discharge chamber 24. The other end of the chamber 102 communieates through a restricted orifice 117 to the passage 114, and by a passage 118 past an adjustable needle valve 119 through a conduit 119a to the inlet chamber 22.

FIG. 3 illustrates a control device 120 which may be susbtituted for the control device 74. A body 121 is formed with a chamber 122 within which is slidably mounted a spool valve 123. The spool valve 123 is formed with two lands 124 and 125 and has a beveled surface 126 adapted to make a fluid-tight seal at a port 127 in one end of the chamber 122, the port 127 communicating with the conduit 93. A compression spring 128 biases the valve 123 to the open position. Two ports 129 and 130 in the lateral wall of the chamber 122 communicate directly with the conduit 119a, and past an adjustable needle valve 131 to the conduit 112, respectively. A port 132 in the end of the chamber 122 remote from the port 127 communicates with a passage 133 which leads past a solenoid valve means 135 having a plunger 134 to the conduit 93, and a restricted orifice 136 in the lateral wall of the chamber 122 communicates this chamber with the passage 133.

In operation, when the elevator car 11 is to be lowered, both solenoid valve means 116 and 100 are energized by any suitable control means well known in the art. The plunger 115 is lifted from its seat relieving pressure from the passage 114 to the discharge chamber 24, whereby the pressure to the right of the piston 108 (as viewed in FIG. 2) becomes that of the discharge chamber. (When the plunger 115 is in its closed position as illustrated, the pressure in the passage 114 stabilizes by means of the restricted orifice 117 at the pressure in the chambers 22 and 34.) Inasmuch as the pressure to the left of the piston 168 (which is larger than the land 105), which has stabilized at the pressure of the inlet chamber 22 through the conduits 118 and 119a, is sufl'icient to overcome the bias of the spring 109, the spool valve 104 moves to the right and is unseated. As the land 105 moves past the port 111, the conduit 118 is cut off from the conduit 112, which may then drain the chamber 34 through the conduit 93 to the discharge chamber 24. Inasmuch as the cross-sectional area of the piston 32 is at least as large as that of the plug 28, and the pressure in the chamber 23 is that of the chamber 22 (the valve 47 being closed) and is always greater than the pressure in the discharge chamber 24 (which is also that of the chamber 34 after the solenoid valve means 116 has been energized), the net opening force on the speed control valve 27 overcomes the bias of the spring 38 and causes the valve 27 to open until the adjustable stop 39 is encountered.

When the solenoid valve means 100 is energized, the plunger 99 is lifted from its seat, whereby the pressure to the right of the piston 80 (as viewed in FIG. 2) is relieved to the discharge chamber 24. Inasmuch as the port 94 delivers pressure fluid from the chamber 23 by the conduit 95 to the left of the piston 80, the bias of the spring 84 is overcome and the spool valve 79 is unseated. The land 81 cuts off the port 91 from the port 85, while the land 82 is lifted out of its bore to connect the port 85 with the port 94, where-by the pressure fluid from the chamber 23 is permitted to flow through the port 85 past the adjustable needle valve 86 and through the conduit 87 to the chamber 62.

When the alternate control device 120 is used, the plunger 134 is caused to open, whereupon the fluid pressures on each end of the spool valve 123 are balanced. Under these conditions the spring 128 drives the valve 123 to the right (as viewed in FIG. 3), whereby communication between the ports 129 and 130 is cut off by the land 125. The pressure fluid in the chamber 34 is then permitted to drain through the conduit 112 and flow past the adjustable needle valve 131 and through the port 127 and conduit 93 to the discharge chamber 24.

After the chamber 23 has been connected with the chamber 62 by the control device 75, the forces on the valve 47 due to the pressures in the chambers 22, 23, 24 and 62 are balanced, and so the force exerted by the spring 66 lifts the valve 47 off its seat at a rate determined by the flow of hydraulic fluid past the adjustable needle valve 86. As the valve 47 opens, fluid flows from the chamber 22 through the ports 30 in the plug 28 to the chamber 23, and then through the ports 50 in the plug 48 to the discharge chamber 24 and on to the reservoir 19.

The rate of flow through the lowering control means increases as the valves 27 and 47 are opening, and the desired rate of flow corresponding to the normal lowering speed of the elevator car is attained after the valve 27 reaches the adjustable stop 39. This rate of flow causes a definite pressure differential between the chambers 22 and 23 as the fluid passes through the effective aperture caused by the ported plug 28 in the port 29. Inasmuch as the forces on the plug 48 and the piston 64 due to the pressure in the chambers 23 and 62 are balanced, the resultant force on the piston 54 due to the pressure differential between the chambers 22 and 23 opposes the bias of the spring 66, and the spring is adjusted by the adjusting screw 69 so that these two forces are balanced at the desired rate of flow.

This desired flow is maintained regardles of the actual value of the pressure in the chamber 22 due to the elevator load within wide limits. An increase in elevator load would tend to increase the fluid flow through the lowering control means 10 if the effective aperture through the port 49 remained constant, however the increased pressure in the chamber 22 caused by the increased load causes the valve 47 to move in its closing direction. This decreases the effective aperture through the port 49 and therefore the fluid flow therethrough until the pressure in the chamber 23 rises to a value diifering from that in the chamber 22 by the desired pressure diflerential, under which conditions the adjusted flow through the control means 10 is attained. Similarly, a decreased load in the elevator car reduces the pressure in the chamber 22, whereupon the valve 47 moves in the opening direction to maintain the same fluid flow rate under the reduced pressure conditions.

As the valve 47 opens, the spring 66 extends and exerts a smaller force. This would tend to reduce the pressure differential across the piston 54 and thereby produce a smaller flow than desired, were it not for the shaping of the ports 50 as indicated in FIG. 2 to compensate for the spring rate of the spring 66, and also the arrangement of the ports 50 in the plug 48, whereby the fluid passing through these ports is directed against the piston 64. The impact of the fluid on the piston 64 is less under wide open, low pressure flow than under restricted, high pressure flow of equal Volume, thereby compensating for the change of spring force with extension. Furthermore, the spring 66 preferably has a low rate, so that there is relatively slight change of force with changing length over the range employed.

When the elevator car 11 approaches a landing, it is desirable to reduce its speed to a low value in a smooth and controlled manner. Suitable control means well known in the art de-energize the solenoid valve means 116 at a proper point in the travel of the car 11 to so reduce its speed. The plunger 115 drops to its seat, preventing further escape of fluid from the passage 114. Fluid under pressure entering through the conduits 119a and 113 passes through the restricted orifice 117 and through the port 113, whereu on the spool valve 104 is driven to its seating position. The chamber 34 is now connected to the inlet chamber 22 through the conduits 112, 118 and 1191!, so that the speed control valve 27 is driven in its closing direction at a rate determined by the speed of fluid flow past the adjustable needle valve 119 until the stop 40 is met.

The gradually decreasing effective aperture through the port 29 causes an increased pressure drop between the chambers 22 and 23. The force of this increased pressure differential acting on the valve 47 exceeds that supplied by the spring 66, and therefore the valve 47 is moved toward its closed position at a relatively rapid rate, since fluid may leave the chamber 62 by way of the conduit 87, ball check valve 88, ports and 94, and conduit to the chamber 23. It is evident that there being no restriction in the path just described, the valve 47 may closely follow the movement of the valve 27 and thereby limit the fall of pressure in the chamber 23. This fall of pressure cannot be faster than the valve 27 can move, and the movement of this valve 27 is limited by the adjustment of the needle valves 111 and 119. When the speed control valve 27 is against the stop 40, the pressure drop for which the valve 47 is balanced will be obtained at a relatively small fluid flow rate through the plug 28, perhaps only th the rate attained when both solenoid valve means 100 and 116 are energized, for example.

As the valve 27 closes, the pressure differential between the chambers 22 and 23 is increased, so that the valve 47 is urged toward its closed position until the force on this valve 47 due to the pressure differential balances the force supplied by the spring 66. The valve 47 is balanced to provide a smaller effective aperture through the port 49, and the spring 66 is compressed to provide a slightly greater force than obtained under the conditions of normal lowering speed descent discussed above, but this spring characteristic is compensated by the manner in which the ports 50 are shaped and by the impact of the fluid discharged by these ports 50 on the piston 64.

The relatively slow levelling speed descent is regulated to be constant in the same way that the normal lowering speed descent is regulated, i.e. changes of load in the elevator car 11 cause corresponding changes in the effective aperture through the port 49, whereby a constant pressure differential between the chambers 22 and 23 is maintained producing a constant fluid flow through the fixed effective aperture caused by the plug 28 in the port 29.

If the control device 120 is substituted for the control device 74, the de-energiz ation of the solenoid valve means 135 permits the plunger 134 to seat, preventing the drain ing of fluid from the passage 133. High pressure fluid from the inlet chamber 22 enters the chamber 133 through the conduit 119a and the restricted orifice 136. The fluid flows through the port 132 and drives the spool valve 123 against the spring 128 until the beveled surface 126 seats to seal the port 127. The ports 129 and 130 are now connected so that the pressure fluid from the chamber 22 may pass through the conduits 119a and 112 to the chamber 34, whereupon the valve 27 is driven in its closed direction at a speed determined by the rate of fluid flow past the adjustable needle valve 131.

When the elevator car is within a fraction of an inch of its desired stopping level, well known control means de-energize the solenoid valve means 100 permitting the plunger 99 to seat and prevent the escape of fluid from the passage 98. Pressure fluid from the chamber 23 passes through the conduit 95 and the restricted orifice 97 to the port 96 and acts with the spring 84 to urge the spool valve 79 to its seated position. The chamber 62 is now cut off from the intermediate chamber 23 and is connected to the outlet chamber 24 through the conduits 87, 9t} and 93. The valve 47 is now unbalanced and will close promptly inasmuch as the forces due to the pressures in the chambers 22 and 23 exceed the force supplied by the spring 66. The valve 47 is therefore fully but gently closed at a rate determined by the adjustment of the needle valve 92, and the elevator car is brought to rest in the fraction of an inch of travel desired.

The lowering control means 10 according to the present invention provides two speeds of descent, both of which are regulated to be constant regardless of the load in the elevator car 11. The speed control valve 27 is not required to make a fluid-tight seal and assumes one of only two stable positions corresponding to the two speeds of descent. Moreover, should there be any leakage between the piston 54 and the port 55, there will be no slippage of the elevator car 11, inasmuch as the plug 43 makes a fluid-tight sea-l in the port 49 under steady state conditions. There can also be no leakage through the control devices 74, 75 and 120, since the plungers 115, 99 and 134, respectively, and the beveled surfaces 106, 83 and 126, respectively, all make fluidtight seals which are unattainable with ordinary spool valves.

While specific exemplary embodiments of the invention have been shown and described, it will be understood that various substitutions, changes and modifications in the form and details of the illustrated embodiments and their manner of operation may be made by those skilled in the art without departing from the spirit and scope of the invention. For example, the adjustable needle valve 110 could be omitted and the initial acceleration of the elevator car governed solely by the Opening rate of the valve 47, i.e. by the adjustable needle valve 86. Also the bore 63 could be made somewhat larger in cross-sectional area than the port 49, suitable adjustment being made in the shape of the ports 50 and in the force supplied by the spring 66 as necessary. Therefore, the invention is not deemed to be limited except as defined by the depending claims.

We claim:

1. A constant flow control device, comprising a valve casing including an inlet chamber, an intermediate chamber and a discharge chamber, said inlet chamber being in continuous communication with said intermediate chamber through a first passageway of variable effective size and said intermediate chamber being in selectively controllable intermittent communication with said discharge chamber through a second passageway, an inlet port in said inlet chamber adapted to be connected to a source of fluid under pressure, a discharge port in said discharge chamber adapted to be connected to a discharge conduit, control valve means disposed in said first passageway for controlling the variable effective size thereof, said control valve means having a plurality of operative positions corresponding to a plurality of different predetermined rates of fluid flow through said first passageway, regulator valve means disposed in said second passageway for regulating fluid flow therein, said regulator valve means including pressure responsive means associated therewith adapted to selectively seal said second passageway against fluid from said intermediate chamber to said discharge chamber to interrupt communication therebetween, and positioning means coupled to said regulator valve means and sensitive to the pressure differential between said inlet and intermediate chambers for adjusting said regulator valve means so that the fluid flow through said control valve means is substantially constant for said plurality of operative positions under varying pressure of the fluid supplied to said inlet chamber.

2. A constant flow control device, comprising a valve casing including an inlet chamber, an intermediate cham ber and a discharge chamber, said inlet chamber being in continuous communication with said intermediate chamber through a first apassageway of variable effective size and said intermediate chamber being in selectively controllable intermittent communication with said discharge chamber through a second passageway, an inlet port in said inlet chamber adapted to be connected to a source of fluid under pressure, a discharge port in said discharge chamber adapted to be connected to a discharge conduit, control valve means disposed in said first passageway for controlling the variable effective size thereof, said control valve means having a plurality of operative positions corresponding to a plurality of different predetermined rates of fluid flow through said first passageway regulator valve means disposed in said second passageway for regulating fluid flow therein, said regulator valve means including pressure responsive means associated therewith adapted to selectively seal said second passageway against fluid flow from said intermediate chamber to said discharge chamber to interrupt communication therebetween, positioning means coupled to said regulator valve means and sensitive to the pressure dilferential between said inlet and intermediate chambers for adjusting said regulator valve means so that the fluid flow through said control valve means is substantially constant for said plurality of operative positions under varying pressure of the fluid supplied to said inlet chamber, and first control means for selectively adjusting said control valve means to one of said plurality of operative positions.

3. A constant speed lowering control means for 'a hydraulic elevator system including a jack cylinder containing hydraulic fiuid, an elevator car plunger reciprocable therein, a pumpand a reservoir, comprising a valve casing including an inlet chamber, an intermediate cham ber and a discharge chamber, said inlet chamber being in continuous communication with said intermediate chamber through a first passageway of variable effective size and said intermediate chamber being in selectively controllable intermittent communication with said discharge chamber through a second passageway, an inlet port in said chamber adapted to be connected to the jack cylinder of a hydraulic elevator system with which the control means is adapted to be used, a discharge port in said discharge chamber adapted to be connected to the reservoir of a hydraulic elevator system, selectively operable speed control valve means disposed in said first passageway for controlling the variable effective size thereof, said control valve means having two operative positions corresponding to two lowering speeds of an elevator car plunger with which the control means is adapted to be used, regulator valve means disposed in said second passageway for regulating fluid flow therein, said regulator valve means including pressure responsive means associated therewith adapted to selectively seal said second passageway against hydraulic fluid flow from said intermediate chamber to said discharge chamber to interrupt communication therebetween, and positioning means coupled to said regulator valve means and sensitive to the pressure diiferential between said inlet and intermediate chambers for adjusting said regulator valve means to provide a pressure in said intermediate chamber such that the pressure differential between said inlet and intermediate chambers remains substantially constant under varying pressure conditions in said inlet chamber.

4. A constant speed lowering control means for a hydraulic elevator system including a jack cylinder containing hydraulic fluid, an elevator car plunger reciprocable therein, a pump and a reservoir, comprising a valve casing including an inlet chamber, an intermediate chamber and a discharge chamber, said inlet chamber being in continuous communication with said intermediate chamber through a first passageway and of variable effective size and said intermediate chamber being in selectively controllable intermittent communication with said discharge chamber through 'a second passageway, an inlet port in said inlet chamber adapted to be connected to the jack cylinder of a hydraulic elevator system with which the control means is adapted to be used, a discharge port in said discharge chamber adapted to be connected to the reservoir of 'a hydraulic elevator system, selectively operable speed control valve means disposed in said first passageway for controlling the variable effective size thereof, said control valve means having two operative positions corresponding to two lowering speeds of an elevator car plunger with which the control means is adapted to be used, regulator valve means disposed in said second passageway for regulating fluid flow therein, said regulator valve means including pressure responsive means associated therewith adapted to selectively seal said second passageway against hydraulic fluid flow from said intermediate chamber to said discharge chamber to interrupt communication therebetween, positioning means coupled to said regulator valve means and sensitive to the pressure differential between said inlet and intermediate chambers for adjusting said regulator valve means to provide a pressure in said intermediate chamber such that the pressure differential between said inlet and intermediate chambers remains substantially constant under varying pressure conditions in said inlet chamber, and first control means for selectively moving said speed control valve means between said two operative positions.

5. A constant speed lowering control means for a hydraulic elevator system including a jack cylinder containing hydraulic fluid, an elevator car plunger reciprocable therein, a pump and a reservoir, comprising a valve casing including an inlet chamber, an intermediate chamber and a discharge chamber, said inlet chamber being in continuous communication with said intermediate chamber through a first passageway of variable effective size and said intermediate chamber being in selectively controllable intermittent communication with said discharge chamber through a second passageway, an inlet port in said inlet chamber adapted to be connected to the jack cylinder of a hydraulic elevator system with which the control means is adapted to be used, a discharge port in said discharge chamber adapted to be connected to the reservoir of a hydraulic elevator system, selectively operable speed control valve means disposed in said first passageway for controlling the variable etfective size thereof, said control valve means having two operative positions corresponding to two lowering speeds of an elevator car plunger with which the control means is adapted to be used, regulator valve means disposed in said second passageway for regulating fluid flow therein and for selectively sealing said second passageway against hydraulic fluid flow from said intermediate chamber to said discharge chamber to interrupt communication therebetween, positioning means coupled to said regulator valve means and sensitive to the pressure differential between said inlet and intermediate chambers for adjusting said regulator valve means to provide a pressure in said intermediate chamber such that the pressure diiferential between said inlet and intermediate chambers remains substantially constant under varying pressure conditions in said inlet chamber, means forming a first chamber in communication with said inlet chamber through a first bore, said first bore being in spaced relation to said first passageway, a first piston slidably received in said first bore and connected to said speed control valve means, first adjustable stop means for limiting movement of said speed control valve means in a direction to increase the lowering speed of said elevator car plunger, said adjustable stop means for limiting movement of said speed control valve means in a direction to decrease the lowering speed of said elevator car plunger, first spring-actuated biasing means urging said speed control valve means in a direction to decrease the lowering speed of said elevator car plunger, and first control means for selectively moving said speed control valve means between said two operative positions.

6. The constant speed lowering control means of claim 5, wherein said first control means includes means for selectively communicating said first chamber with said inlet chamber and said discharge chamber.

7. A constant speed lowering control means for a hydraulic elevator system including a jack cylinder containing hydraulic fluid, an elevator car plunger reciprocable therein, a pump and a reservoir, comprising a valve casing including an inlet chamber, an intermediate chamber and a discharge chamber, said inlet chamber being in continuous communication with said intermediate chamber through a first passageway of variable effective size and said intermediate chamber being in selectively controllable intermittent communication with said discharge chamber through a second passageway, an inlet port in said inlet chamber adapted to be connected to the jack cylinder of a hydraulic elevator system with which the control means is adapted to be used, a discharge port in said discharge chamber adapted to be connected to the reservoir of a hydraulic elevator system, selectively operable speed control valve means disposed in said first passageway for controlling the variable elfective size thereof, said control valve means having two operative positions corresponding to two lowering speeds of an elevator car plunger with which the control means is adapted to be used, regulator valve means disposed in said second passageway for regulating fluid flow therein and for selectively sealing said second passageway against hydraulic fiuid flow from said intermediate chamber to said discharge chamber to interrupt communication therebetween, positioning means coupled to said regulator valve means and sensitive to the pressure differential between said inlet and intermediate chambers for adjusting said regulator valve means to provide a pressure in said intermediate chamber such that the pressure differential between said inlet and intermediate chambers remains substantially constant under varying pressure conditiorrs in said inlet chamber, wherein said second passageway in cludes a beveled seat on the intermediate chamber side thereof, and said regulator valve means includes a flange portion adapted to cooperate with said beveled seat to seal said second passageway against hydraulic fluid flow from said intermediate chamber to said discharge chamber.

8. The constant speed lowering control means of claim 7, wherein said pressure responsive means includes means forming a second chamber in communication with said discharge chamber through a second bore, said second bore being in spaced relation to said second passageway, a second piston slidably received in said second bore and coupled with said regulator valve means, second springactuated biasing means urging said regulator valve means in a direction to unseal said second passageway, and sec ond control means for moving said regulator valve means to selectively seal and unse al said second passageway.

9. The constant speed lowering control means of claim 12 8, wherein said second control means includes means for selectively communicating said second chamber with said intermediate chamber and said discharge chamber.

10. The constant speed lowering control means of claim 8, wherein said positioning means comprises a third bore between said inlet and intermediate chambers and in spaced relation with said second passageway, and a third piston having two opposite surfaces, slidably disposed in said third bore and rigidly connected to said regulator valve means, one of said two opposite surfaces being exposed to said inlet chamber and the other surface being exposed to said intermediate chamber, whereby the pressure differential between said inlet and intermediate chambers urges said regulator valve means in a direction to seal said second passageway.

References Cited by the Examiner UNITED STATES PATENTS 2,915,084 12/1959 Taylor 13750l 3,020,891 2/1962 Jaseph 91446 X 3,020,892 2/1962 Arbogast 91-446 3,125,319 3/1964 Arbogast 9l47 X MARTIN P. SCHWADRON, Primary Examiner.

SAMUEL LEVINE, Examiner.

P. T. COBRIN, B. L. ADAMS, Assistant Examiners.

Claims (1)

1. 3. A CONSTANT SPEED LOWERING CONTROL MEANS FOR A HYDRAULIC ELEVATOR SYSTEM INCLUDING A JACK CYLINDER CONTAINING HYDRAULIC FLUID, AN ELEVATOR CAR PLUNGER RECIPROCABLE THEREIN, A PUMP AND A RESERVOIR, COMPRISING A VALVE CASING INCLUDING AN INLET CHAMBER, AN INTERMEDIATE CHAMBER AND A DISCHARGE CHAMBER, SAID INLET CHAMBER BEING IN CONTINUOUS COMMUNICATION WITH SAID INTERMEDIATE CHAMBER THROUGH A FIRST PASSAGEWAY OF VARIABLE EFFECTIVE SIZE AND SAID INTERMEDIATE CHAMBER BEING IN SELECTIVELY CONTROLLABLE INTERMITTENT COMMUNICATION WITH SAID DISCHARGE CHAMBER THROUGH A SECOND PASSAGEWAY, AN INLET PORT IN SAID CHAMBER ADAPTED TO BE CONNECTED TO THE JACK CYLINDER OF A HYDRAULIC ELEVATOR SYSTEM WITH WHICH THE CONTROL MEANS IS ADAPTED TO BE USED, A DISCHARGE PORT IN SAID DISCHARGE CHAMBER ADAPTED TO BE CONNECTED TO THE RESERVOIR OF A HYDRAULIC ELEVATOR SYSTEM, SELECTIVELY OPERABLE SPEED CONTROL VALVE MEANS DISPOSED IN SAID FIRST PASSAGEWAY FOR CONTROLLING THE VARIABLE EFFECTIVE SIZE THEREOF, SAID CONTROL VALVE MEANS HAVING TWO OPERATIVE POSITIONS CORRESPONDING TO TWO LOWERING SPEEDS OF AN ELEVATOR CAR PLUNGER WITH WHICH THE CONTROL MEANS IS ADAPTED TO BE USED, REGULATOR VALVE MEANS DISPOSED IN SAID SECOND PASSAGEWAY FOR REGULATING FLUID FLOW THEREIN, SAID REGULATOR VALVE MEANS INCLUDING PRESSURE RESPONSIVE MEANS ASSOCIATED THEREWITH ADAPTED TO SELECTIVELY SEAL SAID SECOND PASSAGEWAY AGAINST HYDRAULIC FLUID FLOW FROM SAID INTERMEDIATE CHAMBER TO SAID DISCHARGE CHAMBER TO INTERRUPT COMMUNICATION THEREBETWEEN, AND POSITIONING MEANS COUPLED TO SAID REGULATOR VALVE MEANS AND SENSITIVE TO THE PRESSURE DIFFERENTIAL BETWEEN SAID INLET AND INTERMEDIATE CHAMBERS FOR ADJUSTING SAID REGULATOR VALVE MEANS TO PROVIDE A PRESSURE IN SAID INTERMEDIATE CHAMBER SUCH THAT THE PRESSURE DIFFERENTIAL BETWEEN SAID INLET AND INTERMEDIATE CHAMBERS REMAINS SUBSTANTIALLY CONSTANT UNDER VARYING PRESSURE CONDITIONS IN SAID INLET CHAMBER.

Images