US3392754A

US3392754A - Hydraulic elevator by-pass valve

Info

Publication number: US3392754A
Application number: US508762A
Authority: US
Inventors: Daniel W Risk
Original assignee: COAST ELEVATOR CO
Current assignee: COAST ELEVATOR CO
Priority date: 1965-11-19
Filing date: 1965-11-19
Publication date: 1968-07-16
Anticipated expiration: 1985-07-16

Description

July 16, 1968 D. W. RISK HYDRAULIC ELEVATOR BY-PASS VALVE 2 Sheets-Sheet 1 Filed Nov. 19, 1965 A HIIIIIHHHIIHHII l HHHHHHHHBHHH INVENTOR. .panlel 4/. #1516 ATTORNEY July 16, 1968 w, 5 3,392,754

HYDRAULIC ELEVATOR BY-PASS VALVE 2 Sheets-Sheet 2 Filed Nov. 19, 1965 unm ll IHI INVENTOR.

ame/ 4/ 2 E6 I Q/W flTTO NEY United States Patent 3,392,754 HYDRAULIC ELEVATOR BY-PASS VALVE Daniel W. Risk, Los Angeles, Calif., assignor to Coast Elevator Company, Los Angeles, Calif., a corporation of California Filed Nov. 19, 1965, Ser. No. 508,762 7 Claims. (Cl. 137-637) ABSTRACT OF THE DISCLOSURE A control system for supplying hydraulic fluid to a pressure supply source is described in the following specification which includes an hydraulically operated valve and which finds particular utility as a by-pass in an hydraulic system. The valve is hydraulically operated to be opened and closed, and it includes an adjustment for controlling the size of the valve orifice when the valve is open.

This invention relates to hydraulic power devices in general, and more specifically to an hydraulic control system for supply of fluid under pressure for the upward movement of an elevator.

Hydraulic elevator systems generally employ positive displacement supply pumps, with a conduit from the pump to the elevator ram. The usual control practice is to provide a by-pass line, which is employed to dump a certain quantity of the fluid supplied by the pump, with the remainder directed to the hydraulic ram. Thus, the rate of speed is established, as well as the starting and stopping position of the ram.

Essentially, the system for controlling the upward movement of the elevator comprises a delivery conduit system from the pump to the elevator ram, and a by-pass line with a variable orifice valve in that by-pass line. Thus, whenever it is desired to begin upward movement of the elevator, the pump is actuated to produce a supply of drive fluid under pressure. The bypass valve is maintained at its fully-open position. Hence, the fluid under pressure will choose the path of least resistance and pass out to the sump through the by-pass valve. Thereafter, the bypass valve is caused to close and bring the by-pass line to a gradual close. The supply to the power device will be increased gradually, and finally all of the pump supply will go to the power device.

The by-pass valve has a rated capacity when fully opened, and at that capacity the elevator ram will not be driven.

To bring the elevator to a stop, the valve is caused to open rapidly from its fully-closed position to a partially open position. The partially-open position will allow a bypass of a large portion of the rated capacity, and this partially-open position is reached in a short period of time.

When the elevator does reach its goal, the flow of fluid to the elevator is stopped completely by stopping the pump or dumping the remaining supply.

Because all elevator systems differ for a particular installation, it is necessary to establish a given maximum flow for by-pass in each installation. It has been the practice, prior to this invention, to place, in the by-pass line, an orifice in the form of an elongated cylindrical sleeve having longitudinal V slots in the wall of the sleeve, with the slot size reducing in the direction of fluid flow. Then, an impervious sleeve gate cap is placed over the orifice sleeve and is movable to completely block off the V slots, or to open the slots to a selected degree.

In order to establish the maximum range of bypass, in such prior art structures, an adjustable stop is provided to limit the maximum open position of the gate cap.

This prior art system is satisfactory whenever the bypass valve device is used in systems requiring substantially Patented July 16, 1968 ice the maximum flow of such restricted orifice, but whenever the screw is tightened down to restrict the sleeve gate cap valve movement to only the small portion of the V slots, then the valving becomes critical. That is, if a valving action proides a .005 inch movement of the sleeve gate, this action is only a small percentage of the entire gating slot whenever the cap operates through the entire range of the slot, and has little effect on the total by-pass action. But, if the particular installation requires that the sleeve gate be held to a limit of movement which embraces only a part of the valve slot, then that .005 inch movement is a far greater portion of the total available range. An error of .005, or .010 inch of movement then becomes a critical factor in elevator control, and erratic results are usually experienced.

Accordingly, it is an object of this invent-ion to provide a by-pass valve assembly wherein a gate valve is always operative in its full range without restriction, and orifice manipulation is accomplished by means of adjustable orifice slots.

It is a further object of this invention to place a nested cylinder orifice device in the by-pass line, with one of the cylinders rotatable with respect to the other to produce elongated, variable-width orifice openings in the side wall of the nested cylinders, and to provide a gate valve in the form of a full range impervious cup cylinder telescopable over the nested orifice cylinders.

In accordance with these and other objects which will become apparent hereinafter, the best mode contemplated for the present invention is disclosed in the accompanying drawings wherein:

FIGURE 1 is a schematic illustration of an hydraulic system, embodying the preferred form of the valve of this invention;

FIGURE 2 is a partial section taken along the line 2-2 of FIGURE 1;

FIGURE 3 is an exploded perspective of the nested cylinder orifice control and gate valve of this invention;

FIGURE 4 is a side elevation, partially broken away, of the nested cylinder orifice control;

FIGURE 5 is a view taken along line 5--5 of FIG- URE 4;

FIGURE 6 is a view as in FIGURE 4 with the orifice parts moved to a position of maximum closed relationship;

FIGURE 7 is a view taken along line 7-7 of FIGURE 6; and

FIGURE 8 is an enlarged portion of a sect-ion taken along the line 8-8 of FIGURE 6.

In the FIGURE 1, a supply line 10 is a conduit to a responsive device, such as the ram motor of an hydraulic elevator. A positive displacement pump 12 is used as a source of fluid under pressure. The illustrated system is not a complete hydraulic elevator control, but is a portion only of a system which supplies fluid under pressure for the elevating direction of the elevator. A separate system, whether or not a portion of the illustrated parts are used in that system, controls descent of the elevator.

In this portion of an up control, the fluid from the pump is delivered to a block 16. Block 16 has a distribution chamber 18. The delivery line 10, and also a by-pass line 20, are supplied from chamber 18.

Not shown in the illustration, but capable of being incorporated in the block 16, are various other controls such for example as a control system as set forth in application Ser. No. 488,064 filed Sept. 17, 1965.

The up control for an hydraulic elevator i incorporated in a by-pass which will cause all supply from the pump 12 to dump when the elevator is to remain fixed at a station, and then is gradually closed to bring the ele vator into operation. The FIGURE 1 illustrates a by-pass valve structure 22, incorporating the improved valve device of this invention.

A sump line 24 provides an exit line from the valve structure 22 to a sump 26. A pump supply line 28 from sump 26 then supplies the pump 12 to complete the cycle.

The by-pass valve structure 22 includes a valve body 30 and a cylinder cap 31. A chamber 32 within the body 30 provides a housing for the orifice structure of this invention.

The orifice structure of this invention is best observed in the exploded perspective view of FIGURE 3. Here is illustrated a fixed orifice screen cylinder 34 having a base flange 36 which is secured within the chamber 32 by means of screws 38. Screws 38 may be seen only in the FIGURE 1, having been omitted from the FIGURE 3.

The orifice Screen 34 has a hollow cylindrical body and a plurality of longitudinal slots 40. Slots 40 extend in the direction of the longitudinal axis of cylinder 34.

A movable orifice screen cylinder 42 has an exterior dimension to fit closely within the screen 34. The closeness of this fit may be best observed by reference to FIGURES 5, 7, and 8. Longitudinal slots 44, extending in the direction of the axis of the screen 42, produce a series of ribs 46 therebetween. The ribs 46 are employed to act as blocking gates for the longitudinal slots 40 of orifice screen 34, as best illustrated in FIGURE 8.

The movable orifice screen 42 has a bearing flange 48 seated on the top surface of the block 16, around the mouth of the by-pass line 20 leading from the chamber 18. Thus, fluid is fed into the interior of the orifice screen 42 and out through the aligned

slots

44 and 40, or blocked from such exit by the placing of the ribs 46 over the slots 40, as the case may be.

In FIGURE 1 is illustrated the provision of a lug 50 attached to the top surface of the bearing flange 43. The FIGURE 3 is an illustration from the reverse side as shown in FIGURE 1, and, therefore, the lug 50 is not seen in FIGURE 3.

Screws 52, seen in section view FIGURE 2, are threadably engaged through the wall of the valve body 30, and are directed to contact the sides of the lug 50. Therefore, by retracting one of the :screws and advancing the other, a very careful control of the relative rotational position of the movable screen 42 within the fixed screen 34 may be obtained. In this manner, the exact orifice capacity through the slots 40 may be established. That is, the slots 40 establish the maximum flow through the side wall of the orifice screen 34. The ribs 46, of the movable orifice screen 42, either permit essentially the entire flow or reduce that flow by their position of adjustment.

In order to limit the amount of adjustment movement, in view of the fact that adjustment is made without op portunity to observe the relative position, a notch 54 is cut into the flange 36, and a pin 56 is secured in the flange 48. The pin 56 extends vertically into the notch 54 and thus establishes the rotational adjustment range for the movable orifice screen 42. These two positions of maximum adjustment are illustrated in the FIGURES and 7 respectively, where it is seen that the flange 48 has been driven to the two extremes permitted by the notch 54.

The movable relationship of the fixed and movable orifice screens thereby establishes the ability of the operator to adjust the maximum permitted flow through the side wall of the orifice screen to match the maximum desired by-pass capacity. Thus, the maximum range, from zero to maximum by-pass is established.

Within this maximum range as established, this invention provides for selecting the degree of fluid by-pass between a condition of complete blocking of flow and a complete free flow to the capacity of the screen. This control action is provided by an impervious wall cylinder 53 which is telescopable over the exterior surface of the fixed orifice screen 34. The closed position completely blocking flow is shown in FIGURE 1. A washer 59 provides a seal against which the end of the cylinder 58 may abut 4 to provide complete flow stoppage. Intermediate flow positions are shown in the FIGURES 4 and '6;

To drive the cylinder 58 to the desired position, a piston chamber 60 is provided in the cap 31, and a piston 62, attached to the cylinder 58, operates within the chamber 60.

It is desired that friction be kept to a minimum for accurate control, and, therefore, a rolling diaphragm 64 is secured between the valve body 30 and the cap body 31.

A clamp disc 66 is fitted to the top ofthe piston 62 by means of a lock and guide pin 68. The central portion of the rolling diaphragm 64 is located between the top of the piston 62 and the clamp 66. A guide bushing provides a track in which the pin 68 operates, to hold the piston 62 centered within the composite chambers 32 and 60. The rolling diaphragm 64 provides a low friction means vof sealing the piston in the combined chambers, but requires room for operation. The use of the guide pin 68 in the bushing 70 enables the piston 62 to be made considerably smaller than the piston diameter for thi purpose.

A spring 72 entwines the gate cylinder 58 and urges the gate to a fully-open maximum flow condition.

To counter the action of the spring 72, and to close the gate valve completely, fluid under pressure is supplied r into the piston chamber 60. The fluid pressure for this purpose is supplied through a line 74 having a restrictive orifice 76 therein. Line 74 leads from a high-pressure area within the distribution block 16. Therefore, whenever fluid under pressure is supplied by the pump 12, the fluid is also supplied through the orifice 76 into the chamber 60. The rate of flow, however, is restricted by the orifice. As long as fluid exit from the chamber 60 is closed, the pressure within the chamber will gradually build up as pressure is supplied from the pump 12, and the pressure in the chamber 60 will eventually be the substantial equal to line pressure available in the distribution block '16. Hence, because of the size of the piston 62, the force available from the spring 72 is easily overcome, and the impervious gate valve cylinder '58 is forced tightly into the sealing washer 59.

In FIGURE 1 the -by-pass valve is shown completely closed as described under the action of such fluid pressure. Under such circumstances, no fluid escapes through the by-pass line 24 and all fluid is passed through the line 10 to the operating device.

In order to first slow down the delivery through the conduit 10 and then stop flow altogether, the pressure within the chamber 60 is caused to bleed 01f at a controlled rate. An exhaust line 78 from the chamber 60 is directed to a variable valve 80, and thence through a solenoid-operated valve 82. Valve 82 is a valve which is either fully open or fully closed. From the valve 82, line 84 leads to the chamber 32 and, thence, to the sump.

When it is desired to begin the slowdown of delivery through line 10, the solenoid-operated valve 82 is caused to open. The valve is normally open, and flow to the chamber is restricted by orifice 76. This causes a quick reduction of pressure in the chamber 60, and allows .the gate valve cylinder 58 to move under the force of the spring 72. The orifices open to begin by-pass flow through line 20.

The variable valve 80 is employed in those instances where it is necessary to control the rate of slowdown of delivery through line 10. If stopping in a short period of time is the only desire, then the valve 80 is not needed. However, in hydraulic elevator control, it is desirable that the flow through the line 10 be continued until the elevator car reaches the proper elevation. Hence, it is desired that the speed of elevation be slowed rapidly at first, but thereafter maintained at a slow rate until the elevator levels out at its proper floor. The variable valve 80 is used to modulate and control the rate of delivery through the line 78 for this purpose. In fact, valve 80 can close entirely, if need be, and thus cause the pressure within the chamber 60 to build up and reverse the direction of piston 62 in the event the slowing has become too rapid by an over-rapid by-pass action.

Whereas the present invention has been shown and described herein in what is conceived to be the best mode contemplated, it is recognized that departures may be made therefrom within the scope of the invention which is, therefore, not to be limited to the details disclosed herein but is to be afforded the full scope of the invention as hereinafter claimed.

What is claimed is:

1. A control system for supplying hydraulic fluid to a responsive device from a pressure supply source, includmg:

a transport conduit adapted to be connected from said supply source to said device;

a by-pass line from said transport conduit to a lowpressure area, said by-pass line including a valve means for establishing a maximum flow of fluid therethrough,

said valve means including:

a valve body member interposed in said by-pass line and defining a chamber and having an inlet and an outlet;

a fixed hollow cylindrical screen member mounted in said chamber in position to surround said inlet, said fixed screen member having a plurality of longitudinal slots formed in the wall thereof extending in the direction of the longitudinal axis thereof;

a movable hollow cylindrical orifice screen member telescopically mounted with respect to said fixed screen member for rotational and longitudinal movement with respect thereto, said movable screen member having longitudinal slots therein corresponding to the slots in said fixed screen member to be aligned and misaligned with respect thereto upon rotational movement of said movable screen member with respect to said fixed screen member,

an impervious wall hollow gate cylinder longitudinally slidable over said screen members in telescopic relation therewith between a closed position in which fluid flow through said screen members is completely blocked and an open posion for fluid flow through the aforesaid slots in said screen members,

a piston attached to said gate cylinder and movable within said chamber,

resilient means sealing said piston to the inner wall of said chamber,

a spring member engaging said body member and said piston for biasing said gate cylinder to said open position, means for introducing fluid under pressure to a portion of said chamber on one side of said resilient sealing means to counter the action of said spring and move said gate cylinder to said closed position, restriction means upstream of said portion of said chamber, and

means for bleeding off the fluid from said first portion of said chamber to reduce the pressure therein and permit said spring to move said gate cylinder to said open position.

2. The combination defined in claim 1 in which said fixed screen member includes a base flange secured to said valve body member, and in which said movable screen member is positioned within said fixed screen member and includes a bearing flange engaging said body member around said inlet.

3. The combination defined in claim 2 and which includes a pin attached to one of said flanges and extending into a notch in the other of said flanges to limit relative rotation of said movable screen member with respect to said fixed screen member, a lug attached to said bearing flange, and a pair of adjustment screws thread-ably engaging the wall of said wall body member and contacting opposite sides of said lug to adjust the angular position of said movable screen member With respect to said fixed screen member so as to establish the orifice capacity of said valve means.

4. The combination defined in claim 1 and which includes an annular seal supported on said base flange of and fixed screen member to be engaged by the peripheral edge of said gate cylinder when said wall cylinder is in said closed condition.

5. The combination defined in claim 1 in which said resilient means comprises a rolling diaphragm.

6. The combination defined in claim -1 in which said bleeding means introduces said fluid to a second portion of said chamber on the other side of said resilient sealing means, and in which said outlet from said chamber extends to a sump from said second portion of said chamber.

7. The combination defined in claim 1 in which said bleeding means includes an exhaust pipe line, a variable valve and a solenoid-operated valve.

References Cited UNITED STATES PATENTS 2,553,045 5/1951 Jaseph 52 3,057,160 10/1962 Russell et a1 6052 3,037,527 6/1962 Elston et a1 137637.4 3,141,386 7/ 1964 .Loughridge 91-47 MARTIN P. SCHWADRON, Primary Examiner.

B. L. A DAMS, Assistant Examiner.