US 3268673 A
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Description (OCR text may contain errors)
Aug. 23, 1966 F. T. BILEK 3,268,673
HYDRAULIC PUSHBUTTON ASSEMBLY Filed May 1965 R\ m MLI a mi N j, INVENTOR. f5 67/ United States Patent O 3,268,673 HYDRAULIC PUSHBUTTON ASSEMBLY Frank Thomas Bilek, Downers Grove, Ill., assignor to This invention relates to pushbuttons generally and more particularly to hydraulic interlocking pushbutton assemblies.
Pushbuttons and related assemblies have many uses as, for example, on telephones, adding machines, coin control devices, and the like. As a generality, a designer of these pushbuttons faces two problems. A first problem is to exert restoring forces upon the buttons to return them to a normal position. A second problem is to provide mechanical interlocks so that only a specified number and no morebuttons may be depressed at any given time. Heretofore, these and other problems have been solved by interconnecting the pushbuttons by means of expensive and complex mechanical linkages. Among other things, this means that every different linkage requirement involves a redesign, new tooling, etc.
An object of the invention is to provide new and improved pushbutton assemblies. More particularly, an object is to provide interlocking pushbuttonsof a simple, inexpensive design. Yet-another object is to provide highly reliable devices having an interlocking pushbutton action which give a long, trouble-freev lifetime of service.
Another object is to provide pushbutton assemblies which may be constructed on standard machine tools from readily available commercial parts. Moreover, an object is to provide for the construction of a virtually unlimited number of interlocking arrangements with few or no changes of piece parts.
In accordance with one aspect of this invention, a pushbutton assembly includes a numberof pistons or other fluid displacement means individually associated with each pushbutton. Each displacement means is connected via a fluid passage to a reservoir. Before filling the reservoir, one or more of the pushbuttons are pressed. Then the reservoir isfilled to capacity with a noncompressible fluid such as hydraulic fluid. Thus, if one pushbutton was depressed when the reservoir was filled, :a depressed pushbutton must raise if any other pushbutton is pushed. If two pushbuttons were depressed when the reservoir was filled, two buttons raise if two are pushed simultaneously. One obvious advantage is that the same piece parts may be used for different assembliesthe only manufacturing differences are the number of pushbuttons that are depressed when the reservoir is filled. i
The above mentioned and other features of this invention and the manner of obtaining them will become more apparent, and the invention itself will be best understood by references to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a perspective view of a pushbutton assembly;
FIG. 2 is a fragmentary cross section view of a single pushbutton superstructure showing how contact springs may be actuated;
FIG. 3 shows, in cross section, a first embodiment of a pushbutton assembly; 7
FIG. 4 shows a cross section view of a two-step pushbutton;
FIG. 5 shows a cross section view of pushbuttons hav- 3,268,673 Patented August 23, 1966 ice FIG. 8 is a perspective view of a telephone subset incorporating an exemplary pushbutton assembly.
A manually operated pushbutton assembly is shown in FIG. 1 to illustrate a preferred embodiment exemplifying the principles of the invention. In general, this embodiment includes a plurality of pushbuttons 10 mounted on a reservoir 11. The reservoir 11 stores a noncompressible fluid-such as a hydraulic fluid, for example. Mounted on the reservoir 11 are a plurality of fluid displacement means 12, each containing a predetermined amount of the non-compressible fluid in direct communication with the fluid in the reservoir 11. In this exemplary embodiment, each of the fluid displacement means is a rubber or plastic bellows 13 sealed to the reservoir 11 by a device, such as a threaded collar 14. The bellows could also be made of a metal such as'a Phosphor bronze, for example. In addition, a device (not shown) such as an overcenter spring will snap down to hold a key when it is' depressed.
A fluid displacement means is individually associated with each of the pushbuttons. For example, an expanded bellows 13, individually associated with pushbutton 15, holds a predetermined volume of hydraulic fluid. On the other hand, 'the compressed bellows 16 has expelled a certain amount of hydraulic fluid into the reservoir 11. In doing so, it forced any other depressed pushbuttons to rise. FIG. 2 shows a fragment of a superstructure assembly for guiding and supporting the pushbuttons 10. In greater detail, the superstructure of FIG. 2 includes a base plate 20 having a number of guideway apertures formed therein (as at 21, for example) for supporting the stem 22 of pushbutton 23. Depending from base plate 29 are one or more sets of contact springs 24. The stem 22 carries a portion formed at the top to butt against the base plate 20 and limit upward pushbutton motion and at the bottom to provide for causing contact spring motion. That is, the lower edge of portion 25 and springs 24 have complementary cam surfaces which translate downward pushbutton motion into leftward (as viewed in FIG. 2) spring motion. The spring returns to normal under its own spring tension when the pushbutton raises- In a second embodiment of the invention, FIG. 3, the reservoir 30 has a number of upstanding cylinder walls formed therein, as shown at 31, for example. The lower portion 32 of each pushbutton is shaped in the form of a piston sealed against the cylinder wall by means of one or more piston rings 33which could be simple rubber 0 rings for example. The right-hand pushbutton controlled piston 34 is shown with three piston rings. One end of the reservoir 30 contains a filler plug 35 and the other end contains an-air vent 36.
To complete the embodiments of either FIG. 1 or FIG. 3, it is only necessary to be certain that the required number of pushbuttons are depressed and that all remain ing pushbuttons are fully raised. For example, pushbutton controlled piston 34 is depressed and pushbutton 32 is raised. Then, the filler plug 35 is removed and the reservoir 30 is filled to capacity with a hydraulic fluid. A second plug 36 may be opened slightly to bleed air from the system. By inspection, it should be obvious that if reservoir 30 is completely filled with a non-compressible fluid and if pushbutton 32 is pushed down, pushbutton 34 must rise. I
Those skilled in the art will readily perceive how various full-step and half-step contact operations may be provided by controlling the amount of fluid placed in the reservoir. To insure exact half-step operations, springs, retaining clips, catches, or other mechanical aids may be used to restrain or restrict pushbutton motion at not only the full but also the half-step. To illustrate one such aid, FIG. 4 shows a rubber O ring 40 adapted to restrain pushbutton motion at any one of three steps 41-43. That is the cylinder wall contains three circumferentially depressed rings into which the rubber O ring may expand to restrain motion.
. Moreover, by varying the volume of fluid displaced by each pushbutton some buttons may be interlocked so that 'a'single' pushbutton may be depressed at any given time, and others may be interlocked to allow a plurality of buttons to be depressed simultaneously. For example, FIG. shows a pushbutton controlled piston 45, which displaces twice as much fluid as the pushbutton controlled pistons 46, 47. Thus, if pushbutton 45 is down, it raises to a half-step when button 46 is pushed. If buttons 46, 47 are pushed simultaneously, button 45 raises to its whole step. If button 45 is then pushed both of the buttons 46, 47 raise.
A reset is provided by a free moving piston 48. If piston 48 is pushed as far as it will go in the direction of arrow 49, all pushbuttons must rise. When the pushbutton 46 is pushed down, the piston 48 slides rightward, as viewed in the drawing, to compensate for the displaced fluid. If pushbuttons 46 and 47 are both pushed down, the piston 48 slides rightward and hits a stop. If yet another pushbutton is'thereafter pushed, no further compression relief can result from movement -of piston 48. Thus, any new depression of a pushbutton (such as 45) will raise the buttons that are then lowered.
The embodiments of FIGS. 1 and 3 require precision piston ring seals, but they give a more accurate and close tolerance response. If such accuracy is not required, the embodiment of FIG. 6 offers a cost reduction. Here, the non-compressible fluid is sealed in a flexible bag 50. Then the bag is dropped into the reservoir housing 51 and a top is secured into position by any suitable means, such as bolts 52, 53. The bag of fluid 50 fills the reservoir 51 to the extent required so that one and only one pushbutton (or any other desired number) may be pushed down at any given time. For example, pushbutton 54 is shown in FIG. 6 as pushed down and pushbuttons 55, 56 are shown as raised. The downward pressure on the bag at 57 tensions the bag at 58 and raises the buttons 55, 56. Thus, if pushbutton 55 is pushed, the fluid in bag 50 moves to the side and forces pushbutton 54 to rise.
Means are provided for interlocking the pushbuttons by groups. More particularly, FIG. 7 shows the reservoir as divided into two distinct sections 60, 61 by a series of check valves 62. The check valves are here shown as a pair of spring loaded balls 63, 64 adapted to seat under the spring tension for the purpose of preventing fluid movement between sections 60, 61. If pushbutton 65 should be down when button 66 is pushed, button 65 raises. Neither pushbutton 67 nor pushbuttons 68 can be pushed because reservoir 61 is completely full and check valve 64 prevents the passage of fluid from section 61 to section 60.
If pushbutton 69 is pushed, two pins a, b push balls 63, 64 down, thus opening the check valves. The fluid that pushbutton 69 displaces raised the buttons 65 or 66. Now buttons 67, 68 can be pushed because the fluid that they displace flows through the check valves 63, 64 to section 60. Thereafter, pushbuttons 67, 68 can be operated, but pushbuttons 65, 66 are locked in a raised position until after pushbutton 69 is again depressed to open the check valves.
The pedadogics of this specification should be clear from a reading thereof. That is, I provide a series of fragmentary drawings, each explaining one or more distinct principles or features of the invention. Thus, FIG. 2 shows how to operate electrical contacts responsive to pushbutton motion. FIG. 3 shows how to seal pistons against cylinder walls. FIG. 5 shows howv to reset the pushbuttons and how pushbuttons may be given a differential motion to provide the well known two-step contact motion commonly called X or preliminary contacts in the automatic telephone art. FIG. 4 shows an exemplary 4 way of giving discrete positions to the two-step pushbutton motion of FIG. 5.
My invention relates to a way of providing mechanically interlocked push-buttons for selectively controlling electrical circuits. When so providing such interlocking pushbuttons, the design engineer will be expected to adapt any or all of these principles and features to his particular needs. He is not expected to treat the reset button 48 as applicable only to the differential motion pushbuttons of FIG. 5. Nor should he treat the discrete half-step positioning means as applicable only to FIG. 4. Quite the contrary, he is expected to use any combinations of the many features in conjunction with any of the various hydraulic systems. To emphasize this point, I have shown the reset button 48 not only in FIG. 5, but also in FIGS.
1 and 7I could also have shown a reset button in other figures. In like manner, to indicate that the differential pushbuttons are not limited to the FIG. 5 disclosure, I have shown the pushbutton 68 as controlling two pistons 46, 47, each piston displacing one-half the fluid that the piston 67 displaces. I could also show some of the bellows 13 as being larger than others, and button 54 could displace twice as much fluid as either of the buttons 55, 56.
Obviously, the argument could be extended to all of the features that I have shown. Therefore, no one should construe the separate feature drawings, which were dictated by the pedagogics of the specification, as an indication that the individual features are limited to any particular application of the invention.
Although those skilled in the art will readily perceive many uses for the pushbuttons, FIG. 8 shows one such assembly 70 used in conjunction with a telephone 71. The pushbuttons could also be used to replace the dial 72.
While the principles of the invention have been de scribed above in connection with specific apparatus and application, it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention.
1. An electrical control device comprising a multi-line telephone set, means including an assembly of pushbuttons for selectively connecting said telephone to any one of said telephone lines, said pushbutton assembly means comprising a reservoir holding a non-compressible hydraulic fluid, a plurality of communicating hydraulic cylinders also filled with said fluid, pushbutton actuated piston means for selectively displacing the fluid in any one of said cylinders into said reservoir and other of said cylinders, means responsive to said displacement of said fluid for restoring any previously actuated one of said piston means, and con-tact means controlled by each of said pushbuttons for completing said selective connection of said telephone to any one of said telephone lines.
2. The device of claim 1 wherein said cylinders comprise a plurality of bellows communicatingly sealing said cylinders into said reservoir, said bellows being individually associated with said pushbutton actuated piston so that said movement of each of said pushbuttons to a depressed position compresses an individually associated'one of said bellows to expel the fluid therein into said reservoir.
3. The device of claim 1 wherein said reservoir is shaped to provide the walls of said cylinders, said fluid displacement means comprising a plurality of pistons positioned in said cylinders and individually associated with said pushbuttons, and means for sealing said pistons against the walls of said cylinders.
4. In the device of claim 1, means associated with each of said pushbuttons for restraining pushbutton motion at at least one position between a fully lowered and fully raised position.
5. In the device of claim 1, a freely moving reset means for providing a limited compression relief whereby all of said pushbuttons may be raised simultaneously or one or more of said pushbuttons may be lowered.
6. The device of claim 5 wherein said reset compression 5 means comprises a piston for resetting said pushbuttons.
7. In the device of claim 5, means for interlocking said pushbuttons by groups whereby pushbuttons in a first group may be operated and pushbuttons in a second group may not be operated, and means for transferring said group. interlock from said first to said second group whereby the pushbuttons in said first group may not be operated and the pushbuttons in said second group may be operated.
8. In the device of claim 1, check valve means for dividing said reservoir into independent compartments, a plurality of said pushbuttons associated with each of said compartments, means whereby each of said pushbuttons displaces a predetermined volume of said fluid when depressed, and means for selectively operating said check valves to transfer fluid between said compartments to lock the pushbuttons associated with some of said compartments and unlock the pushbuttons associated with other of said compartments.
References Cited by the Examiner UNITED STATES PATENTS 2,240,287 4/1941 Croll 6054.5 2,800,034 7/1957 Seeger 2005 X 3,050,605 8/1962 Pollak 200-168 3,071,930 1/1963 Moulin 60-54.5
FOREIGN PATENTS 318,566 6/ 1902 France.
ROBERT K. SCHAEFER, Primary Examiner.
R. R. BUNEVICK, KATHLEEN H. CLAFFY, Examiners.
M. GINSBURG, Assistant Examiner.