US3811284A

US3811284A - Control system

Info

Publication number: US3811284A
Application number: US00269416A
Authority: US
Inventors: D Trussell; P Surette
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-07-06
Filing date: 1972-07-06
Publication date: 1974-05-21
Anticipated expiration: 1991-05-21

Abstract

A control system, suitable for use as a two-hand safety control system, for producing an output signal to operate a device comprising a first fluid pulse generator generating a first fluid pulse in response to a manual force (e.g., depressing a first push-button), a second fluid pulse generator generating a second fluid pulse in response to another manual force (e.g., depressing a second push-button), and a fluid-responsive switch responsive only to substantially simultaneous receipt of these pulses to produce the output signal.

Description

United States Patent [191 Trussell et al. p

[11] 3,811,284 May 21, 1974 l CONTROL SYSTEM [75] Inventors: Donald H. Trussell, 23 Princeton Rd., Burlington, Mass. 01803; Philip A Surette, Reading, Mass.

[73] Assignee: said Trussel, by said Surette [22] Filed: July 6, 1972 [21] Appl. No.: 269,416

f [52] US. Cl 60/533, 91/424, 60/407, 60/567 [51] Int. Cl. FlSb 13/04 [58] Field of Search 60/54.5 R, 62.5 R, 533,

[56] References Cited 7 UNITED STATES PATENT-S 1 W971 Wright 8/l92'5 Davis.....

3,553,967 l/l97l Porter et al. 60/54.5 R

Primary Exdminer-Edgar W. Geoghegan Assistant Examiner-A. M. Zupcic I Attorney, Agent, or FirmCharles Hieken; Jerry Cohen [57 ABSTRACT A control system, suitable for use as a two-hand safety control system, for producing an output signal to operate a device comprising a first fluid pulse generator generating a first fluid pulse in response to a manual force (e.g., depressing a first push-button), a second fluid pulse generator generating a second fluid pulse in response to another manual force (e.g., depressing a second push-button), and a fluid-responsive switch responsive only to substantially simultaneous receipt of these pulses to produce the output signal.

18 Claims, 3 Drawing Figures PATENTEDNAYRI M4 SHEET 1 OF 2 CONTROL SYSTEM FIELD .OF INVENTION ator employs both hands simultaneously, or substantially simultaneously in order to operate a device.

BACKGROUND OF INVENTION Recent federal safety legislation and regulations have made it a requirement that potentially dangerous inachinery, such as jigs, presses, and various other pinching-type devices, be equipped with two hand control systems, in order to occupy both of the operators hands while the machinery is operated. Such controls must also demand substantially simultaneous or concurrent operation, so that, for example, successively operating the two controls with one hand is ineffective to operate the machinery. In addition, the control must be readily retrofit to existing devices, and should be both reliable and not excessively costly to purchase or install.

SUMMARY OF INVENTION It is the object of the present invention to provide a novel, reliable and economical control system for operating devices.

Another object is to provide a tow hand safety control system which requires substantially simultaneous operation of a control with each of an operators hands, and which can be simply retrofit to existing devices, aswell as incorporated into new devices.

A further object is to provide a reliable and economical control system which requires no pneumatic, hydraulic, or electrical power sources other than the manual force resulting from an operators depressing a push button.

Another object is to provide a safety control system for operating pinching-type devices such as jigs, presses, and the like.

The invention features a control system for producing an output signal to operate a device comprising a first fluid pulse generator generating a first fluidpulse in responseto a manual force, a second fluid pulse generator generating a second fluid pulse in response to another manual force, and a fluid-responsive switch responsive only to substantially simultaneous receipt of these pulses to produce the output signal. The pulse generators are preferably spaced apart so that an oper-, ator can apply only'one manual force with each hand, and each'generator comprises a push button which is depressed to generate the pulse (by acting upon, e.g., a piston. or a flexible fluid-confining member such as a diaphragm), and. for repeated operation, is biased to return from its depressed position when the manual force is removed. The invention includesmeans for requiring an operator to substantially simultaneously effect first and second force changes, such as by depressing respective push buttons, to actuate the fluid responsive switch to assume a first condition for producing the output signal and to always assume a second condition preventing the occurrence of the output signal shortly after assuming the first condition, this means including the first and second pulse generators and means for releasing pressure following a change in applied manual force even when the manual force persists.

A preferred fluid-responsive switch comprises fluidsensitive sealing means (e.g., diaphragm means) having a fluid-responsive side. A pulse inlet port for first pulses and a pulse inlet port for second pulses are located on opposite sides of the sealing means. The switch also has a fluid outlet port, and the sealing means is responsive to the increase in pressure resulting from action of a fluid pulse on one side to cause an increase in pressure at the fluid outlet port, when a fluid pulse is received on its other side. Dissipating means (e.g., a bleed valve opening orifice, port or other suitable devices or mechanisms) may be provided to dissipate the increased pressure at the responsive side of the sealing means in a selected time interval. Unless pulses are received at both sides of the sealing means substantially simultaneously, no fluid output, i.e., no increase in pressure, results at the fluid outlet port. A fluid responsive output device is connected to the fluid outlet port to produce an output signal operating the device upon receiving a fluid output from the fluid outlet port. I

Thus,.the pulse" produced when a push-button is depressed causes ,a' pressure increase within the fluidresponsive switch. If, because of substantially simultaneous depression of the pushbuttons, this increase in pressure cannot be relieved, the pressure at the fluid output port will also increase, and the fluid-responsive output device, responsive to this increase in pressure at the fluid output port, will produce an output signal operating the device.

Other objects, features and advantages will be apparent to one skilled in the art from the following descrip-' tion of a preferred embodiment of the invention, taken together with the attached drawings thereof, inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF PREFERRED EMBODIMENTS FIG. l shows a two hand control system 10, which produces fluid pulses operable to interconnect a power supply PS to a device D, operated by substantially simultaneously depression by an operator of two spacedapart push buttons. In particular, control system 10 has a first pneumatic pulse generator 12, a second pneumatic pulse generator 14, and a pulse-responsive switching system comprising a fluid-responsive pneumatic switch 16 and an output device 18.

Pulse generator 12 includes a housing 20 containing an externally accessible'push button 22 connected to a piston rod 24, which carries on its end a piston head 26, slidably movable in a cylinder 28 against a biasing compression spring 29. Similarly, pulse generator 14 includes an identical housing 30, push button 32, piston rod 34, piston head 36, cylinder 38 and spring 40.

At the end of cylinder 28 of first pulse generator 12 is a first pulse outlet port 42, and at the end of cylinder 38 of second pulse generator 14 is a second pulse outlet port 44.

Pneumatic switch 16 has a housing 50, having a lower chamber 52 and an upper chamber 54, separated by a flexible diaphragm 56, which is secured at its periphery to housing 50. A barrier 58 is provided to define the opening 60, which is located substantially in the middle of the diaphragm 56. A first pulse inlet port 62 is connected, through pneumatic tube 64, to first pulse outlet port 42 of pulse generator 12, and opens into lower chamber 52. A second pulse inlet port 68 is connected, through pneumatic tube 70, to second pulse outlet port 44 of pulse generator 14, and is in communication through passage 72 with upper chamber 54. A vent port 74 also opens into chamber 54 between barrier 58 and diaphragm 56, and is, as shown, open to atmosphere. A bleed valve 76 establishes communication,

through bleed passage 78, between lower chamber 52 and, as shown, atmosphere. A fluid outlet port 80 is in communication with upper chamber 54, and, through pneumatic tube 82, with the inlet 84 of output device 18.

Output device 18, as illustrated, is an electric switch which has a housing 86 supporting a diaphragm 88, which is in turn connected through connector rod 90 to control member 92. Control member 92 is pivotally mounted at its end 94 on housing 86, carries a contact member 96 on its other end, and is biased by compression spring 97 so that Contact member 96 is normally separated from fixed contact member 98. For purposes of illustration, contact member 96 is electrically connected, through control member 92, to the power source PS, and contact member 98 is electrically connected to the device D to be operated. Thus, operating power is supplied to the device D only when the,

contact members

96, 98 are engaged, and no power is supplied-Le, the device'will not operate-when the contact members are separated, as in FIG. 1. In practice, the output device 18 can be any switching device, whether electrical, magnetic, fluid, or otherwise responsive to reception of a fluid output from pneumatic switch 16 to produce aosi'gnal operating or controlling or otherwise acting upon the device D, and may be independent of whether electrical, magnetic, fluid, or other power is utilized for operating the device.

The operation of the device is apparent from a comparison of FIGS. 1 and 2. Depressing push button 220! first pulse generator 12 generates a pneumatic pulse from cylinder 28 which by pneumatic communication through tube 64 and inlet 62 into chamber 52 causes an at least momentary increase in pressure in chamber 52. Since chamber 52 and chamber 53 are both normally at the same (atmospheric) pressure by reason of vent port 74 and bleed valve 76 respectively, as shown in FIG. 1 in their normal OFF" states, the increase in pressure in chamber 52 flexes or expands diaphragm 56 so that it seals opening 60, as shown in FIG. 2. If, while the diaphragm is expanded, push button 32 of second pulse generator 14 is depressed, a pneumatic pulse is thereby generated from cylinder 38. Since opening 60 is sealed by diaphragm 56, this second pneumatic pulse, through tube 70, inlet 68 and passage 72 increases the pressure in chamber 54 and therefore also by pneumatic communication through outlet port 80, tube 82, and inlet 84, increases the pressure upon diaphragm 88 of output device 18. This increase in pressure expands or flexes diaphragm 88, which in turn piv- 4 ots control member 92 against biasing spring 97 bringing contact member 96 into electrical contact with fixed contact 98, to supply power to the device D. If bleed valve 78 is open, as shown, to a low pressure source such as atmosphere, then the output device 18 will operate as a momentary electric unit, since, as soon as the increase in pressure due to the first pulse is dissipated from chamber 52 through valve 78, diaphragm 56 will begin to return to its unflexed position. The pressure on diaphragm 88 is then relieved through tube 82, port 80, opening 60 and vent port 74, and the

contacts

96, 98 are again disengaged, opening switch 18 through tube 82, port 80, opening 60, and vent port 74 to atmosphere.

The two-hand, substantially simultaneous operation of the system will now be apparent. If only push button 32 of pulse generator 14 is depressed, the increase in pressure in chamber 54 will be relieved through opening 60, and vent outlet 74. If only push button 22 of pulse generator 12 is depressed, the increase in pressure in chamber 52 will momentarily expand or flex diaphragm 56, and then be dissipated through bleed valve 78, returning the diaphragm to its FIG. 1 position. It is only when depressing push button 32 of pulse generator 14 produces an increase in pressure in chamber 54 which encounters an expanded diaphragm, and hence a sealed opening 60, that there will be an increase in pressure at outlet to be transmitted to output device 18. Although a slight delay between pushing button 32 and then button 22 may result in the pressure in upper chamber 54 being entirely relieved through vent port 74 before the diaphragm 56 expands to seal opening 60, the time delay due to lack of precise coordination by the operator in exactly simultaneously depressing the buttons it not normally of such duration as to prematurely relieve the pressure in chamber 54. The ordinarily coordinated operator can achievethe required substantial simultaneity repeatedly without difficulty. I

FIG. 3 shows another push-button arrangement in a control system otherwise identical in construction and operation to that of FIGS. 1 and 2. The difference resides in utilizing flexible diaphragms in lieu of the pneumatic pistons of FIGS. 1 and 2. In particular, pulse generator 1 12 (shown in the undepressed or OFF position) includes a housing havingacentral base 122, into which is press-fit an end plug 124 having a passage 126, which is in communication with tube 64. A shaft 128 is trapped by E-ring 130 and the shoulder 132 of bore 122 within bore 122. A flexible diaphragm 134 is secured between E-rings 136 and collar 138 to shaft 128. Biasing spring 140 is held within diaphragm 134 between housing 120 and collar 138. The shaft 128 has an outer threaded portion onto which is threadably secured push button 142. Collar 144 and the outer skirt 146 of diaphragm 134 are secured to housing 120 by hold-down screws 148, which extend into the housing (not shown).

Pulse generator 114 is'identically structured, like parts being indicated by primed numbers. Pulse generator 114 is shown with push button 142 depressed, which decreases the fluid (pneumatic) volume confined by diaphragm 134, to generate a fluid pulse in being produced when only one button is depressed, as shown in FIG. 3).

Other embodiments will occur to those skilled in the art and are within the following claims.

What is claimed is:

1. A control system for producing an output signal to operate a device comprising,

a first fluid pulse generator generating a first fluid pulse only in response to a first manual force change,

a second fluid pulse generator generating a second fluid pulse only in response to a second manual force change,

fluid responsive switching means for providing an output signal when actuated to assume a first condition,

first means coupled to said first and second pulse generators for requiring an operator to substantially simultaneously effect said first and second force changes to produce said first and second fluid pulses substantially simultaneously to actuate said fluid responsive switching means to assume said first condition,

and second means for causing said fluid responsive switch to always assume a second condition preventing the occurrence of said output signal shortly after assuming said first condition.

2. A control system according to claim 1 wherein said first and second fluid pulse generators are spaced apart in a manner allowing an operator to apply only onesaid manual force with each hand.

3. A control system according to claim 1 wherein each said fluid pulse generator "comprises a control member movable over a distance to generate said pulse. 7

4. A control system according to claim 3 wherein each said fluid pulse generator comprises a manually depressible pushbutton connected to said control member.

5. A control system according to claim 1 wherein at least one of said fluid pulse generators comprises a fluid cylinder having an outlet, a piston movable in said cylinder to displace fluid through said outlet, a manually depressible push button connected to said piston, and biasing means biasing said piston away from said outlet in the absence of manual force on said pushbutton.

6. A control system according to claim I wherein at least one of said fluid pulse generators comprises a fluid chamber having a flexible fluid-confining member and having a fluid outlet, and a manually depressible push button connected to said fluid-confining member, said button, when depressed, decreasing the fluid volume confined by said member to generate a fluid pulse at said outlet.

7. A control system according to claim wherein said flexible fluid-confining member is a flexible diaphragm.

8. A control system according to claim 6 including biasing means for expanding said fluid-confining member to contain a fluid volume, said push button being depressible against said biasing means to decrease said fluid volume.

9. A control system according to claim 1 wherein said fluid-responsive switch comprises dissipating means for dissipating the pressure increases due to at least one of said pulses after a selected time interval.

10. A control system according to claim 1 wherein said fluid pulses are pneumatic pulses.

11. A control system for producing an output signal to operate a device comprising a first fluid pulse generator generating a first fluid pulse in response to a manual force, a second fluid pulse generator generating a second fluid pulse in response to another manual force, and a fluid-responsive switch responsive only to substantially simultaneous receipt of said first pulse and said second pulse to produce said output,

wherein said fluid-responsive switch comprises a housing, a flexible sealing member dividing said housing into first and second pressure chambers, a first pulse inlet port, a fluid outlet port, a vent port, all of said first pulse inlet port, said fluid outlet port, and said vent port opening to said second pressure chamber, a second pulse inlet port opening to said second pressure chamber, a control port between said first pulse inlet port and said vent port, pressure dissipating means from said second pressure chamber, and signal means connected to said fluid outlet port and responsive to an increase in pressure at said outlet port to produce said output signal, said sealing member being, when unflexed, spaced from-said control port to allow the increase in pressure in said first pressure chamber due to receipt of a fluid pulse from said first pulse inlet port to be relieved by said vent port, said sealing member being flexed in response to an increase in pressure in said second pressurechamber due to receipt of a fluid pulse from said second pulse inlet port to close said control port, whereby the increase in pressure in said first pressure chamber produces a fluid output at said fluid outlet port, said pressure dissipating means dissipating the increase in pressure in said second pressure chamber after a selected time interval to enable said sealing member to return to its unflexed position.

12. A control system according to claim 11 wherein each said pulse generator comprises a manually depressible push button, and a control member, connected to said push button and movable over adistance when said push button is depressed to generate said fluid pulses.

13. A control system according to claim 12 including biasing means biasing said push button to a normally OFF position.

14. A control system according to claim 12 wherein said push buttons are spaced apart in a manner allowing an operator to push only one button with each hand.

15. A control system according to claim 12 wherein said control member comprises a piston movable over a distance to generate a pulse.

16. A control member according to claim 12 wherein said control member is a'flexible diaphragm confining a fluid volume and having a fluid outlet, said push button, when depressed, decreasing said fluid volume to generate a fluid pulse. 7

17. A control system according to claim 11 where said dissipating means comprises a bleed valve for bleeding the increase in pressure in said second pressure' chamber as soon as said second fluid pulse enters said second pulse inlet port.

18. A control system according to claim 12 wherein said fluid pulses are pneumaticpulses.

Claims

1. A control system for producing an output signal to operate a device comprising, a first fluid pulse generator generating a first fluid pulse only in response to a first manual force change, a second fluid pulse generator generating a second fluid pulse only in response to a second manual force change, fluid responsive switching means for providing an output signal when actuated to assume a first condition, first means coupled to said first and second pulse generators for requiring an operator to substantially simultaneously effect said first and second force changes to produce said first and second fluid pulses substantially simultaneously to actuate said fluid responsive switching means to assume said first condition, and second means for causing said fluid responsive switch to always assume a second condition preventing the occurrence of said output signal shortly after assuming said first condition.

2. A control system according to claim 1 wherein said first and second fluid pulse generators are spaced apart in a manner allowing an operator to apply only one said manual force with each hand.

3. A control system according to claim 1 wherein each said fluid pulse generator comprises a control member movable over a distance to generate said pulse.

5. A control system according to claim 1 wherein at least one of said fluid pulse generators comprises a fluid cylinder having an outlet, a piston movable in said cylinder to displace fluid through said outlet, a manually depressible push button connected to said piston, and biasing means biasing said piston away from said outlet in the absence of manual force on said push button.

6. A control system according to claim 1 wherein at least one of said fluid pulse generators comprises a fluid chamber having a flexible fluid-confining member and having a fluid outlet, and a manually depressible push button connected to said fluid-confining member, said button, when depressed, decreasing the fluid volume confined by said member to generate a fluid pulse at said outlet.

7. A control system according to claim 6 wherein said flexible fluid-confining member is a flexible diaphragm.

11. A control system for producing an output signal to operate a device comprising a first fluid pulse generator generating a first fluid pulse in response to a manual force, a second fluid pulse generator generating a second fluid pulse in response to another manual force, and a fluid-responsive switch responsive only to substantially simultaneous receipt of said first pulse and said second pulse to produce said output, wherein said fluid-responsive switch comprises a housing, a flexible sealing member dividing said housing into first and second pressure chambers, a first pulse inlet port, a fluid outlet port, a vent port, all of said first pulse inlet port, said fluid outlet port, and said vent port opening to said second pressure chamber, a second pulse inlet port opening to said second pressure chamber, a control port between said first pulse inlet port and said vent port, pressure dissipating means from said second pressure chamber, and signal means connected to said fluid outlet port and responsive to an increase in pressure at said outlet port to produce said output signal, said sealing member being, when unflexed, spaced from said control port to allow the increase in pressure in said first pressure chamber due to receipt of a fluid pulse from said first pulse inlet port to be relieved by said vent port, said sealing member being flexed in response to an increase in pressure in said second pressure chamber due to receipt of a fluid pulse from said second pulse inlet port to close said control port, whereby the increase in pressure in said first pressure chamber produces a fluid output at said fluid outlet port, said pressure dissipating means dissipating the increase in pressure in said second pressure chamber after a selected time interval to enable said sealing member to return to its unflexed position.

12. A control system according to claim 11 wherein each said pulse generator comprises a manually depressible push button, and a control member, connected to said push button and movable over a distance when said push button is depressed to generate said fluid pulses.

16. A control member according to claim 12 wherein said control member is a flexible diaphragm confining a fluid volume and having a fluid outlet, said push button, when depressed, decreasing said fluid volume to generate a fluid pulse.

17. A control system according to claim 11 where said dissipating means comprises a bleed valve for bleeding the increase in pressure in said second pressure chamber as soon as said second fluid pulse enters said second pulse inlet port.

18. A control system according to claim 12 wherein said fluid pulses are pneumatic pulses.