US3037101A - Temperature compensated pneumatic time delay devices - Google Patents

Description

y 1962 F. A. KOMATAR ETAL 3,037,101

TEMPERATURE COMPENSATED PNEUMATIC TIME DELAY DEVICES Filed Feb. 9, 1959 2 Sheets-Sheet 1 fin nnn F G 2 Q INVENTORS FREDERICK A. KOMATAR BY FRANK ARTHUR PEARSON ATTORNEY May 29, 1962 F. A. KOMATAR ETAL 3,037,101

TEMPERATURE COMPENSATED PNEUMATIC TIME DELAY DEVICES Filed Feb. 9, 1959 2 Sheets-Sheet 2 T\\[\ P I FIG 4 I sa a 'i'g 20' o ///////////7/ FREDERICK A. KOMATAR FRANK ARTHUR PEARSON IN VENTORS.

ATTDRNEY United States Patent Ofifice 3,037,101 Patented May 29, 1962 TEMPERATURE COMPENSATED PNEUMATIC TIME DELAY DEVICES Frederick A. Komatar, East Moline, and Frank Arthur Pearson, Moline, 111., assignors, by mesne assignments, to The Gamewell Company, Newton, Mass, :1 corporation of Delaware Filed Feb. 9, 1959, Ser. No. 792,167 24 Claims. (Cl. 20083) The invention relates to devices which hold a manually or electrically actuated switch in actuated position for a fixed time.

More specifically, the invention relates to electrically or mechanically operated pneumatic timers which include means for compensating for atmospheric temperature change to maintain timing accuracy Within tolerance limits at all times.

The invention will be described as applied to manually operable short timing range pneumatic timers adapted to control one or more electric switches of the snap acting type. Other improvements to timing devices contemplated in the present invention include ease of manufacture, economy of parts, and low cost of assembly.

Timing by displacing a given volume of air which is then replaced through a metering device by atmospheric pressure is well known. What is believed to be new is to meter the return air through an orifice which changes its flow capacity with atmospheric temperature change to thereby compensate for temperature-viscosity changes in the air. In the past, as the temperature of the air increased, the timing interval decreased. As an analogy, the air may be compared to a liquid which becomes more fluid as its temperature is increased. Being more fluid, the air is more rapidly aspirated through the orifice thus reducing the timing interval.

Employment of a captive atmosphere in the timing chamber does not eliminate the problem because the timer is normally at or above ambient temperature because of the heating action of the operating solenoid or other control apparatus. This raises the temperature of the captive atmosphere, thereby decreasing the timing interval.

The invention compensates for change of air temperature by changing the cross sectional area of the orifice. This is accomplished by the use of materials having dissimilar temperature coefficients of expansion, one material forming the needle valve and another material forming the valve sleeve or housing.

Another feature of the invention permits adjustment of the needle in the sleeve without rotation. Thus the needle cannot scar the sleeve and the sleeve cannot groove the needle. Flats on the non-metering portions of the needle and the sleeve prevent rotation and allow only longitudinal movement. The needle and the sleeve have substantially identical tapers and thus do not injure each other.

Another feature of the invention provides that the needle valve cannot be forced into the valve orifice by continuously turning the adjustment knob. The knob merely backs off.

Another feature of the invention is the employment of approximately 90 percent captive air thus permitting the elimination of the filter normally required. Make-up air is admitted on the underside of the device around the stem thereby greatly reducing the amount of grit or dirt entering the chamber. An opening to the atmosphere is required so that pressure will not build up within the chamber as the temperature of the timer body is increased.

Another feature of the invention is the design of the needle valve adjustment means which permits partial withdrawal of the needle valve for eiiecting instantaneous time-out during an emergency or during set-up when the operator does not want to wait for the device to time out.

An additional advantage of the design is that during the power stroke' air is forced through both the check valve and the orifice thus providing a cleansing action for the orifice.

Other advantages will be evident as the invention is described in conjunction with the following figures of which:

FIGURE 1 is an exterior view of the timer shown in pers ective.

FIGURE 2 is a cross sectional view of the timer, having one form of metering orifice, shown in actuated position.

FIGURE 3 is an isometric view of the diaphragm retainer and diaphragm.

FEGURE 4 is a cross sectional view of an alternate form of the metering orifice.

FIGURE 5 is a plan view of the switch lever.

Description An exterior view of the timer is shown in FIGURE 1. The enclosure consists of a mounting plate 1, a base 2, and a cap 3. Each of these three pieces is die cast and is ready for assembly essentially as it comes from the die. Switch 4 may be any one of a variety of commercially available snap acting switches and is affixed to the base 2 with mounting screws 5. The switch 4 includes terminals 6, 7 which are normally open and are closed by the action of switch lever 9 when button 8 is depressed thereby energizing an external load circuit, not shown. After the preset delay period has transpired, switch lever 9 permits switch 4 to open the circuit between terminals 6 and 7 and the external load is deenergized. A reverse acting switch having normally closed contacts may be used in place of switch 4 which has normally open contacts. Then the load would be energized continuously and deenergized during timing. A double throw switch may be used to obtain either of the switching arrange,- ments described above.

A cross sectional View of the timer is shown in FIGURE 2. The section is taken through the centerline of the device and illustrates the simplicity of design.

Mounting plate 1 carries a raised flange portion 11 having a centerbore 12 which acts as a guide for button 8. Mounting plate 1 also has a fulcruma13 for switch lever 9. Four spacer posts 14 are cast integrally with mounting plate 1 and support the base 2 and the cap 3 of the timer. Rivet-like extensions, not shown, on posts 14 are expanded after assembly to rivet the cap, base, and mounting plate into an integral unit.

Timer base 2 forms one portion of the air chamber and has an integrally cast cavity 15 and air passage 16. Base 2 has a centrally located opening 17 for the stem 18 of the diaphragm retainer 20. Base 2 has a counterbore 21 adapted to seat one end of the switch actuator spring 22. Spring 22 is spaced from stem 18 and thus cannot cause wear or friction affecting timer accuracy. The spacing between stem 18 and opening 17 is sufi'icient to allow entrance of air during depression of button 8 thus permitting the partial vacuum formed in chamber 15 to be equalized with atmospheric pressure. Air compressed in chamber 23 moves through the check valve into chamber 15 during depression of button 8. A small portion of the air compressed in chamber 23 moves through the metering orifice and passage 15 into chamber 15 thus performing a slight cleansing action within the metering orifice.

Cap 3 forms and encloses the other portion of the air chamber 23 having a frusto conical interior which -con forms closely to the frusto conical exterior of the top of diaphragm retainer 20. Diaphragm 27 divides the chamber into two portions and is clamped around its periphery by base 2 and cap 3 by the compression action of the rivet extensions of posts 14. The diaphragm is set in a counter-bore 19 which prevents excessive compression of the diaphragm during the riveting operation.

Diaphragm 27 serves also as support for diaphragm retainer 20 which is retained thereon by ring 33 which forms also the check valve seat 25. Rivet-like projections 34 formed as part of diaphragm retainer 20 serve to hold the ring 33 to the retainer 29. The rivet-like projections 34 are superior to other fastening devices such as screws or rivets because they do not require a hole through retainer 20. They provide a positive seal and prevent air leakage from one portion of the chamber to the other.

There are openings 26 in the diaphragm 27 which are eflectively sealed by check valve assembly 24. A check valve cap 35 is supported by the diaphragm 27. The check valve washer 36 is drawn against the diaphragm 27 and check valve cap 35 by the rivet action of projection 37 which forms a part of check valve cap 35 and extends through the diaphragm and washer 36. The resiliency of the diaphragm 27 combined with the spring action of the check valve spring 38 maintains closure of the check valve. Check valve spring 38 is a simple leaf spring and exerts approximately one ounce of force tending to hold the diaphragm 27 against the check valve seat 25. Since the check valve seat is a ring having a conical cross section with a very small area impressed on the diaphragm, the small spring force creates a high seating pressure around the apex of the ring. Air is ex hausted from the chamber 23 to cavity 15 through openlugs 26 in the diaphragm 27 and thence through ports 30 in the retainer 20.

The diaphragm and retainer assembly is shown in isometric view in FIGURE 3. Referring to FIGURES 2 and 3, diagram 27 is in the preferred form a circular sheet of fiber glass reinforced silicone rubber. Diaphragm '27 is compressed between retainer 2-0 (not shown) and ring 33 by the action of rivet-like projections 34. The check valve cap 35 (not shown) is positioned below the diaphragm 27 in a recess in retainer 20. A washer 36 and a projection 37 on check valve cap .35 retain cap 35 on diaphragm 27. The check valve seat 25 is formed as an integral part of ring 33. There are a number of openings 26 in diaphragm 27 under the ring 33 and a number of ports 30 in the retainer 20 which permit passage of air from above to below the diaphragm 27 when the retainer stem 18 is forced upward.

Referring again to FIGURE 2, depression of button 8 forces stem 18 and diaphragm retainer 20 away from cavity 15 toward chamber 23 forcing the air in chamber 23 to displace the check valve portion of diaphragm 27 away from check valve seat 25 and pass through aperture 26 in diaphragm 27 around check valve spring 38, through ports 30 in diaphragm retainer 20 and into cavity 15. A small portion of the air compressed in chamber 23 moves out through the needle valve orifice 29 into valve housing 32, through passage 16 into chamber 15 at a high velocity. This cleans out any dust in the metering orifice 29.

During the timing portion of the cycle spring 22 forces button 8 and stem 18 of diaphragm retainer 20 forward creating a partial vacuum in cavity 23 and a pressure differential across the diaphragm. The pressure tends to equalize through passage 16, around the needle valve 31, and through the tapered orifice 29. Needle valve hous' ing 32 is die cast as part of cap 3 and has an interior of circular cross section and has a flat surface 43 along one side. The body of needle valve 31 is of circular cross section with a flat on one side. The two flats bear on each other and prevent the needle valve 31 from rotating when binding-type stop nut 44 is rotated for timing adjustment. This prevents the orifice surfaces from galling. As another precaution, the frusto conical surface 40 of needle valve 31 has burnished into the metal pores of its surface a graphite type lubricant. All surplus lubricant is removed from the surface to prevent stoppage of the air passage and erratic timing.

Needle valve 31 has preferably an elongated form with a slight taper at one end and a screw thread at the other end. Its means of attachment and adjustment is located at the extreme outer end to make its effective length as great as possible. in this way it expands and contracts substantially longitudinally with temperature change. Its high ratio of length to width is used to advantage in the invention. Prior art valves were attached near the needle end or near the center, rather than at the outboard end.

None of the timers on the market today, to our knowledge, offer temperature compensation.

The needle valve 31 is in the preferred form of the invention turned from bronze having a temperature coefficient of expansion of approximately 0.00000986 inch per inch per degree Fahrenheit. The valve housing 32 which forms a part of cap 3 is cast of brass having a temperature coefficient of expansion of approximately 0.00000957 inch per inch per degree Fahrenheit. The principle of the combination is that as the ambient temperature rises and the air becomes more fluid the needle 31 elongates and expands a greater amount than the housing 32 and decreases the orifice area. Various combinations of metallic or non-metallic materials may be selected to accomplish this change in orifice area. To eliminate casting the cap 3 of solid brass, a sleeve of brass may be inserted in an aluminum or zinc cap 3 as shown in FIGURE 4.

A screw thread is applied to the outer end of needle valve 31 to permit its axial adjustment. Needle valve bushing 46 is pressed into a counterbore 47 in valve housing 32 and acts as a guide for needle valve 31 and a stop for spring 48 which is seated around a raised flange on bushing 46. The other end of spring 48 is seated around a flange on needle valve 31. The intervening portion of the needle valve 31 is of smaller cross section to prevent wear. Spring 48 supplies sufficient compression to maintain needle valve 31 at any time setting.

It will be noted that continuous rotation of stop nut 44 in the counter clockwise direction will permit spring 48 to move the needle valve 31 further into the orifice 29 lengthening the timing interval. If stop nut 44 is turned until it is loose, spring 48 will limit the compression of the needle 31 in orifice 29. Since spring 48 exerts only a limited force, needle 31 cannot score or gal-l orifice 29- Continued rotation of stop nut 44 in the clockwise direction compresses spring 48 and moves needle valve 31 further out of orifice 29 and shortens the timing interval.

A snap acting switch 4 is afiixed to a flange 513 which is a part of die cast base 2. Self tapping screws 5 are used. A rectangular piece of insulating fabric (not shown) may be applied between the switch 4 and flange 50 to provide additional insulation between terminals 6, 7 and base 2 and cap 3.

Snap switch 4 is actuated by the action of switch lever 9 against actuator 51. The inside end of switch lever 9 resides in a groove 52 turned in button 8. A fulcrum 13 formed as part of mounting plate 1 serves as a pivot for switch lever 9 shown in plan view in FIGURE 5. Two raised portions 53 adjacent to fulcrum 13 coact with two notches 54 in switch lever 9 to give it lateral stability. The inner end of switch lever 9 is formed with two fingers 55 which coact with the groove 52 in button 8 to stabilize the lever and transmit force to it. Switch lever 9 is maintained in a vibration free state by the spring within switch 4 behind actuator 51 and by the spring 22. Rollpin 56 serves to retain stem 13 in engagement with button 8. A reduced section on stem 18 engages a bore in button 8 for proper alignment. Button 8, stem 18, diaphragm retainer 2'0 and diaphragm 27 act as a unitary structure.

The structure is retained by the guide 12 in mounting plate 1 and by diaphragm 27. Diaphragm 27 holds one end of the structure in alignment and guide 12 and button 8 hold the other end in alignment. The structure is thus restrained against all movement except axial translation.

Another form of the temperature compensating mechanism is shown in FIGURE 4. As stated above, the cost of die casting cap 3 may be reduced by casting it of zinc or aluminum rather than brass and by inserting a brass sleeve in housing 32 to produce the same temperature compensating effect.

As shown in FIGURE 4-, a sleeve 41 is inserted in the valve housing 32 which is cast as part of cap 3. Valve housing 32 has an interior of hexagonal cross section. The sleeve 41 has an exterior of hexagonal cross section to prevent rotation in housing 32 and has a keyway 42 out along one side. The body of needle valve 31 is of circular cross section with a radial bore fitted with a pin 49 projecting from one side for sliding in keyway 42. The pin 43 in the needle valve 31 fits into the keyway 42 on one side of valve sleeve 41 and prevents the needle valve 31 from rotating When knob 57 is rotated for timing adjustment. This prevents the orifice surfaces from galling.

The passage of air around the exterior of valve sleeve 41 is prevented by the quad ring 53. Quad ring 58 is compressed between the end of valve sleeve 41 and the end of valve housing 32. The sleeve 41 is retained in housing 32 by a bushing 59 pressed into the outer end of housing 32.

The sleeve 41 is in this embodiment bored from brass hex stock having a temperature coefiicient of expansion of approximately 0.00000957 inch per inch er degree Fahrenheit. The needle valve 31 is turned from bronze having a temperature coefiicient of expansion of approximately 0.00000986. As the ambient temperature rises and the air becomes more volatile the needle 31 expands a greater amount than the housing 32 and decreases the orifice area. Various combinations of metallic or nonmetallic materials may be employed to accomplish this change in orifice area. The remainder of the device is substantially identical with that described above.

One feature of the invention which contributes to increased timing accuracy for a pneumatic timer is the design of the air chamber 23 and the diaphragm retainer 20. As shown in FIGURE 2 with the button 8 fully depressed, retainer 20* and diaphragm 27 and associated parts completely fill the chamber 23 and expel all the air therefrom. Then, when the timed interval commences when the actuating force is removed from button 8 only the very small amount of air trapped in the passage above the chamber 23 expands into chamber 23. A good vacuum is thus obtained, the amount of vacuum depending on the force of spring 22'. Little travel of the retainer stem 18 is lost as the remaining air expands. This increases the linearity of the timing curve.

It is understood that a solenoid and plunger may be installed in place of pushbutton 8 to make the timer operable electrically and remotely. It is also understood that various sized models of the timer could be made to extend the range of timings available.

We claim:

1. A temperature compensated pneumatic time delay device comprising, a switch device adapted to be actuated after a fixed delay, a substantially airtight timing chamber, means for expelling substantially all of the air from said chamber, resilient means for drawing air into said chamber, a self compensating temperature compensated orifice determining the time required to replace the air, means to actuate the switch device when the air is substantially replaced.

2. A temperature compensated pneumatic timer consisting of a timing chamber having a frusto conical interior, a flexible diaphragm closing said chamber, a mating frusto conical means for moving said diaphragm to expel substantially all of the air from said chamber, a spring urging said means away from said interior thereby reducing the pressure in said chamber below atmospheric, and adjustable means for admitting atmosphere to said chamber having integral temperature compensation, said means comprising a frusto conical valve opening of one material and an elongated frustro conical needle valve of a different material having a somewhat greater temperature coefiicient of expansion.

3. A timer comprising a confined chamber having a frusto conical interior, means fitting into said chamber having a frusto conical exterior for pressurizing said chamber, a flexible diaphragm separating said means and said chamber, check valve means in said diaphragm for releasing the air in said chamber to atmosphere, means tending to draw said first named means out of said chamber, self temperature compensating air metering means between atmosphere and said chamber, said means comprising an orifice of variable cross sectional area, said orifice defined by a bore in a material having a given temperature coefiicient of expansion, and an elongated needle valve coextensive therewith of a material having a greater temperature coeflicient of expansion, said elongated needle valve adjustable at the outboard end thereof, the area of said orifice decreased as the temperature of said timer increases, and increased as the temperature of said timer decreases.

4. A timer comp-rising, a cap made of a material having a given thermal coeificient of expansion, a tapered bore in said cap, a correspondingly tapered needle valve having an elongated body made of a material having a somewhat greater thermal coefiicient of expansion supported at its exterior end by said cap and extending into said tapered bore and slidably movable therein under manual and thermal adjustment, manual adjustment means comprising a screw thread on the exterior end of said needle valve and a friction nut and spring cooperative with said cap to permit and retain manual adjustment of said needle valve, thermal adjustment comprising the lengthening and shortening of said needle valve with timer temperature increase and decrease, respectively, a diaphragm having one-way valve means therein, said diaphragm under external urging adapted to expel substantially all the air from said cap, spring means effective after release of said external urging adapted to said diaphragm means away from said cap to reduce the air pressure therein, an air passage from atmosphere into said cap including said needle valve and said tapered bore to meter atmosphere into said cap, and switch means actuated by said diaphragm means when the air pressure in said cap is substantially restored.

5. An interval timer consisting of a cap having an air chamber with a frusto conical interior, a diaphragm across the base of said frusto conical interior, a base having an air chamber with a cylindrical interior, said cap and said base secured together and securing the rim of said diaphragm, a diaphragm retainer secured to and centered on said diaphragm and having a conical forepart and a cylindrical aft part and a stem, means to urge said retainer and diaphragm forward into said conical air chamber to compress the air therein, one-way valve means in said diaphragm and retainer designed to permit the passage of air compressed in said conical chamber into said cylindrical chamber, an air passage between said chambers having a metering orifice therein, additional means to urge said retainer and diaphragm aftward to form a partial vacuum in said conical chamber, the air metered into said conical chamber permitting said retainer and diaphragm to move aftward at a rate governed by said metering orifice, the metering orifice manually preset to permit the conical chamber to fill in a fixed time, the fixed time maintained over a wide range of operating temperatures by the temperature compensating effect of said metering orifice, said metering orifice ineluding a tapered bore in said cap and a long needle valve having a correspondingly tapered end coextensive therewith, said temperature compensating efiect obtained from the temperature elongation of said needle, said needle being made of a material having a substantially greater temperature coetficient of expansion than said cap, the elongation of said needle being sufiicient to overcome both the temperature expansion of said orifice and the change of fluidity of the air with temperature, and an electric switch controlled by the forward and aftward movement of said stem.

6. In a timer of the class described, a unitary structure consisting of a mounting plate, a base, and a cap, said base and cap affixed to said mounting plate, said base and said cap having coaxial air chambers, a flexible diaphragm separating said chambers, said diaphragm compressed around its periphery between said cap and said base, a retainer atfixed to said diaphragm, said retainer held from all but axial. movement thereby, a stem on said retainer adapted to pass through a bore in said mounting plate, means to urge said stem and said retainer toward said cap to compress the air in said chamber in said cap, check valve means including said diaphragm to release said compressed air to the chamber in said base, resilient means to ur e said retainer toward said base to create a partial vacuum in said chamber in said cap, an air passage between said chambers, a metering orifice in said air passage, said metering orifice comprising a slightly tapered bore in said cap and a needle having a correspondingly tapered end, said needle having a fine screw thread on its opposite end, a bushing in said cap adapted to slidingly support said opposite end of said needle, a compression spring mounted on said bushing and adapted to urge the tapered portion of said needle into said tapered bore, nut means threaded on said fine screw thread exterior to said air passage adapted to regulate the excursion of said needle into said tapered bore, said needle having a flat on one portion of its length, said air passage in said cap having a corresponding flat to prevent rotation of said needle, said needle made of a material having a greater coefficient of thermal expansion than the material of said cap, the air moving through said orifice in one direction during compression and in the opposite direction during timing, the metering orifice kept free of dust by said air movement, and switch means actuated by said retainer.

7. In a new article of manufacture, a pneumatic time delay device having a body consisting of a die cast mounting plate, a base, and a cap, said base and said cap having centrally located apertures, a pushbutton adapted to be mounted in said plate and axially movable therein, a stem afiixed to the inside end of said pushbutton mounted in said base and axially movable therein, a helical compression spring around said stem and adapted to urge said pushbutton away from said base, a cylindrical chamber in said base, an air tight frusto conical chamber in said cap, a flexible diaphragm compressedly retained between said cap and said base, a corresponding frusto conical diaphragm retainer formed on one end of said stem, said diaphragm retainer and stem maintained against sideways motion by said diaphragm, a one-way valve in said diaphragm comprised of a ring rigidly fixed to said diaphragm retainer and having a conical shaped valve seat therein, a check valve cap fixed to said diaphragm, a check valve spring between said retainer and said valve cap for biasing said diaphragm against said check valve seat, ports in said diaphragm retainer and in said diaphragm beyond said check valve seat, said check valve adapted to release air from said chamber when the pressure therein is somewhat greater than atmospheric, an adjustable metering orifice between the two said chambers consisting of an elongated passage in said cap fitted with a sleeve having a given temperature coetficient of expansion and having a central bore and a tapered orifice therein, a needle valve having a greater temperature coefficient of expansion and having a correspondingly tapered. end, a radial bore in the center portion of said Cir needle, a pin fitted into said bore and projecting therefrom, a longitudinal slot in said sleeve adapted to take the projection of said pin, said needle having a threaded portion extending beyond said sleeve, an elastic nut threaded on said thread and abutting said sleeve, a compression spring between said needle and an interior ridge on said sleeve to maintain said needle in said orifice as far as said nut permits, a return passage from said orifice to said cavity, a two position snap acting switch aflixed to said base, an actuator a part of said switch, a switch lever adapted to pivot on a portion of said mounting plate, one end of said switch lever adapted to coact With said button, the other end of said switch lever adapted to bear on said actuator, said switch urged to one position when said button is depressed and to the other position a predetermined delay interval after said button is released, said delay remaining substantially constant within wide ambient temperature limits.

8. A pneumatic time delay device including a housing, first and second chambers in said housing, a diaphragm separating said chambers, an air passage between said chambers, a conical bore forming one portion of said passage, a cylindrical bore having a flat across one chord forming a second portion of said passage, a needle valve made of a material having a greater thermal coetlicient of expansion than said chamber and adapted for axial movement in said cylindrical and conical bores and having a flat along one side for cooperation with said flat in said cylindrical bore, a compression spring mounted around said needle and adapted to urge said needle toward said conical bore, a screw thread on the outboard end of said needle and a nut beyond said cylindrical bore for manual longitudinal adjustment of said needle, the thermal properties of said needle applying longitudinal adjustment of said needle with temperature change, said needle kept from turning by said flats to keep the conical surfaces from galling during adjustment, and means to create a partial vacuum in said first chamber, and means becoming effective when suflicient air has passed through said passage to reduce the vacuum and to actuate a switch.

9. A pneumatic time delay device including first and second air chambers, said diaphragm compressed between said chambers at its periphery, a gastight, flexible diaphra gm between said chambers, a diaphragm retainer compressed against the lower surface of said diaphragm, a ring having a circular central recess compressed against the upper surface of said diaphragm, rivet-like projections on said retainer extending through holes in said diaphragm and said ring for riveting said ring to said retainer, a check valve comprising additional holes in said diaphragm located within the confines of said recess, and a washer and spring urging said diaphragm against said ring, said retainer having holes substantially opposite said additional holes in said diaphragm, means to move the retainer and diaphragm assembly to create a pressure in said first chamber, said check valve operated by the resulting air pressure to reduce it to substantially atmospheric, a spring adapted to move said retainer and diaphragm assembly to create a partial vacuum in said first chamber, an integral temperature compensating metering orifice between said first and second chambers to meter air into said first chamber, and an electric switch actuated by said retainer when sufiicient air has been admitted to said chamber.

10. A temperature compensated time delay device in which one diaphragm serves as a timing diaphragm and a check valve diaphragm, including a irusto conical chamher and a cylindrical chamber, a flexible diaphragm of fiberglass reinforced silicone rubber separating said chambers, a cylindrical diaphragm retainer mounted on one side of said diaphragm, a frusto conical ring mounted on the other side of said diaphragm and aflixed to said retainer by leak-proof rivet-like projections on said retainer, said ring having an annular sealing flange and an annular recess adjacent to said flange, one or more ports in said diaphragm opposite said recess, a spring loaded valve disc urging said diaphragm against said sealing flange, one or more apertures in said retainer opposite said ports, the check valve portion of said diaphragm thus arranged to permit release of air compressed in said conical chamber, means to urge said diaphragm from said cylindrical chamber into said conical chamber to rapidly displace substantially all of the air from said conical chamber, means to urge said diaphragm slowly toward said cylindrical chamber, a passage containing a self temperature compensating metering orifice between said two chambers, and an electric switch actuated from said retainer after a time delay.

11. In a pneumatic time delay device having two chambers separated by an airtight diaphragm, a one-way air passage through the diaphragm between the two chambers, a restricted air passage between the two chambers, a non-self-damaging metering orifice comprising the restriction, the metering orifice consisting of a bore and a needle valve having a portion slidable therein, said needle valve having also an elongated threaded portion, a thumb nut adapted for threading onto said threaded portion, a sleeve a part of said device having an opening adapted to guide said needle valve longitudinally, a helical spring compressed between said sleeve and a flange on said needle valve urging said needle valve into said orifice, the needle valve limited in its travel by the adjustment of said thumb nut, continued untightening rotation of said thumb nut causing said thumb nut to unseat rather than said needle valve to scar said orifice, continued tightening rotation of said thumb nut causing said needle valve to withdraw from said orifice.

12. A temperature compensated pneumatic time delay device comprising, a switch actuated at the beginning of a delay period and at the end of the delay period, a substantially airtight timing chamber, externally operated means for expelling substantially all of the air from said chamber, spring means for drawing air into said chamber, a self temperature compensating elongated needle valve and orifice determining the rate of replacement of the air into said chamber, and lever means adapted to actuate the switch device as the air is substantially replaced.

13. A temperature compensated pneumatic timer consisting of a timing chamber having a frusto conical interior, a flexible diaphragm closing said chamber, a mating frusto conical means for moving said diaphragm to expel substantially all of the air from said chamber, a spring urging said means away from said interior thereby reducing the pressure in said chamber below atmospheric, and adjustable means for admitting atmosphere to said chamber having an integral temperature compensating orifice, said orifice comprising a tapered bore into said chamber and an elongated tapered needle anchored a substantial distance axially away from said tapered bore and adapted to expand and contract substantially axially into and out of said tapered bore, the axial movement of said needle resulting from the thermal expansion and contraction thereof, said thermal expansion and contraction being suflicient to compensate for the expansion and contraction of said bore and the increase and decrease in viscosity of the air with temperature changes materially large.

14. The safety feature in a pneumatic time delay device having an orifice, means for adjustably partially closing said orifice, said means including an elongated needle valve having adjusting means on its exterior end external to said device, spring means urging said needle valve into said orifice, said spring means cooperative with said adjusting means for maintaining said needle valve in its last adjusted position, said timing device immediately timing out upon manual withdrawal of said adjusting means.

15. A pneumatic timer having an orifice, means for adjustably partially closing said orifice, said means including an elongated needle valve having a fine adjusting screw thread on its exterior end at least partially external to said timer, spring means urging said needle valve into said orifice, said spring means cooperative with said adjusting means for maintaining said needle valve in its last adjusted position, and thumb nut means having a fine thread cooperative with said fine adjusting screw thread on the exterior end of said needle valve for obtaining fine adjustment thereof.

116. A pneumatic time delay device having a choice of two timing intervals, one being an adjustable, timed interval and the other being a very short untimed interval; said device comprising a gastight chamber having diaphragm means externally operated to substantially reduce the volume of said chamber, check valve means designed to Vent the gas compressed in said chamber, spring means adapted to urge said diaphragm means to increase the volume of said chamber, a metering orifice connected to said chamber through which entering gas is metered, adjustable means for metering said gas to determine the time required to substantially fill said chamber, said adjustable means capable of rapid withdrawal to permit filling said chamber in a very short time to reduce the waiting time on a mechanism controlled thereby, and electric switch means operable by said diaphragm means.

17. A pneumatic time delay device having a self-protecting orifice, means for adjustably partially closing said orifice, said means including a needle valve having adjusting means external to said device, a compression spring urging said needle valve into said orifice, said spring cooperative with said adjusting means for maintaining said needle valve in its last adjusted position, said adjusting means rotatable in one direction to withdraw said needle from said orifice to thereby shorten the timing interval, said adjusting means rotatable in the opposite direction to extend said needle into said orifice to thereby lengthen the timing interval, said adjusting means adapted to back ofi when said needle meets said orifice, and said compression spring effective to limit the force of said needle against said orifice.

18. In a timer of the class described, a unitary strac ture consisting of a mounting plate, a base, and a cap, said base and cap affixed to said mounting plate, said base and said cap having coaxial chambers, a flexible diaphragm separating said chambers, a counterbore in said cap coaxial with the chamber in said cap, said counterbore of lesser depth than the thickness of said diaphragm, said diaphragm positioned in said counterbore and compressed around its periphery between said cap and said base, a retainer 'aflixed to said diaphragm, sad retainer held from all but axial movement thereby, a stem on said retainer adapted to pass through a bore in said mounting plate, means to urge said stem and said retainer toward said cap to compress the gas in said chamber in said cap, check valve means including said diaphragm to release said compressed gas to the chamber in said base, resilient means to urge said retainer toward said base to create a partial vacuum in said chamber in said cap, a gas passage between said chambers, a metering orifice in said passage, and an electric switch operated by the axial movement of said stem.

19. In an article of manufacture, a pneumtic time delay device having a body consisting of a mounting plate, a base, and a cap, said plate and said base having centrally located apertures, a pushbutton adapted to be mounted in said plate and axially movable therein, a stem alfixe-d to said pushbutton, a compression spring around said stern and adapted to urge said push-button away from said base, a chamber in said base, an air tight chamber in said cap, a flexible diaphragm compressedly retained between said cap and said base, a diaphragm retainer afiixed to one end of said stem, said diaphragm retainer and stem maintained against sideways motion by said diaphragm, a one way valve in said diaphragm comprised of a ring rigidly fixed to said diaphragm retainer and having a valve seat therein a check valve cap fixed to said diaphragm, a check valve spring between said retainer and said valve cap for biasing said diaphragm against said check valve seat, ports in said diaphragm retainer and in said diaphragm beyond said check valve seat, said check valve adapted to release air from said chamber when the pressure therein is somewhat greater than atmospheric, an adjustable metering orifice between the two said chambers consisting of an elongated passage in said cap having a given temperature coefficient of expansion and including a central bore and a tapered orifice, a needle valve having a greater temperature coefficient of expansion and having a correspondingly tapered end, said needle adapted for only longitudinal movement in said passage, said needle having a threaded portion partially extending beyond said passage, a nut threaded on said thread and abutting said passage, a compression spring between said needle and an interior ridge in said passage to maintain said needle in said orifice as far as said nut permits, a return passage from said orifice to said cavity, a two position snap acting switch afiixed to said base, an actuator a part of said switch, a switch lever adapted to pivot on a portion of said mounting plate, one end of said switch lever adapted to coact with said button, the other end of said switch lever adapted to bear on said actuator, said switch urged to one position when said button is depressed and to the other position a predetermined delay interval after said button is released, said delay remaining substantially constant within wide ambient temperature limits.

20. A pneumatic time delay device consisting of a mounting plate, a base, and a cap, said plate and said base having coaxial bores therethrough, a timer actuator adapted to be mounted through said bore in said plate and axially movable therein, a spring adapted to urge said actuator away from said base, a chamber in said base coaxial with said bore, a coaxial chamber in said cap, a flexible diaphragm compressedy retained between said cap and said base, a diaphragm retainer in part of said actuator, said retainer and actuator retained from sideways motion by said diaphragm, a check valve in said diaphragm consisting of a ring affixed to said retainer and having a valve seat therein, a check valve cap fixed to said diaphragm, a check valve spring between said retainer and said valve cap for biasing said diaphragm against said check valve seat, holes in said retainer and in said diaphragm beneath said ring, said check valve adapted to release pressure from said chamber when the pressure therein is somewhat greater than without, an adjustable orifice consisting of a passage in said cap having a given temperature coefficient of expansion, a needle valve having a greater temperature coefficient of expansion, said needle adapted for non-rotational longitudinal movement in said passage, said needle having a threaded portion extending outside said passage, a correspondingly threaded adjustment means exterior to said passage, a spring between said passage and said needle for urging said needle into said orifice, a switch a part of said device, a switch actuator a part of said switch, a lever adapted to pivot on a portion of said device and coast with said actuator and said switch actuator, said switch urged to one position when said timer actuator is actuated and to the other position a preset delay interval after said timer actuator is released, said delay remaining substantially constant within wide ambient temperature limits.

21. A pneumatic time delay device consisting of a mounting plate, a base, and a cap, a rod adapted to protrude through said base and move axially therein, a spring adjacent said rod and adapted to urge said rod away from said base, a cylindrical chamber in said base, a frusto conical chamber in said cap, a flexible diaphragm compressedly retained between said cap and said base, a corresponding frusto conical diaphragm retainer formed on one end of said rod, said diaphragm retainer and rod maintained against sideways motion by said diaphragm, a one way valve in said diaphragm comprised of a ring rigidly fixed to said diaphragm retainer and having a valve seat therein, a check valve cap fixed to said diaphragm, a check valve spring between said retainer and said valve cap for biasing said diaphragm against said check valve seat, ports in said diaphragm retainer and in said diaphragm beyond said check valve seat, said check valve adapted to release air from said chamber when the pressure therein is somewhat greater than without, an adjustable metering orifice between the two said chambers consisting of an elongated passage in said cap having a given temperature coefi'icient of expansion and having a central bore and an orifice therein, a needle valve having a greater temperature coefficient of expansion, means to prevent rotation of said needle in said passage, said needle having a threaded portion extending beyond said chamber, means for longitudinal adjustment or" said needle, a spring adapted to urge said needle into said orifice as far as said adjustment means permits, a return passage from said orifice to said chamber in said base, a switch aflixed to said base, an actuator a part of said switch, a switch lever having one end adapted to coact with said rod and the other end adapted to bear on said switch actuator, said lever urged to one position when said rod is depressed and to the other position a predetermined delay interval after said rod is released, said relay remaining substantially constant within wide ambient temperature limits,

22. A pneumatic time delay device consisting of a mounting plate, a base, and a cap, said base and said cap having centrally located apertures, a pushbutton axially movable therein, a spring affixed to the end thereof and adapted to urge said pushbutton away from said base, a cylindrical chamber in said base, an air tight frusto conical chamber in said cap, a flexible diaphragm retained between said cap and said base, a corresponding frusto conical diaphragm retainer attached to one end of said stem, a one way valve in said diaphragm, a check valve cap fixed to said diaphragm, a check valve spring between said retainer and said valve cap for biasing said diaphragm against said check valve seat, ports in said diaphragm retainer and in said diaphragm beyond said check valve seat, said check valve adapted to release air from said chamher when the positive pressure therein is somewhat greater than atmospheric, an adjustable metering orifice between the two said chambers consisting of an elongated passage in said cap fitted with a sleeve having a given tempera ture coefficient of expansion and having a central bore and a tapered orifice therein, a needle valve having a greater temperature coefiicient of expansion and having a correspondingly tapered end, said needle having a threaded portion extending beyond said sleeve, adjustment means threaded into said thread and abutting said sleeve, a spring between said needle and said sleeve to maintain said needle in said orifice as far as said adjustment means permits, a return passage from said orifice to said cavity in said base, a snap acting switch affixed to said base, an actuator a part of said switch, a switch lever one end of which is adapted to coact with said button, the other end of which is adapted to bear on said actuator, said switch urged to one position when said button is depressed and to the other position a predetermined delay interval after said button is released, said delay remaining substantially constant within wide ambient temperature limits.

23. A temperature compensated pneumatic time delay device comprising, an electric switch, an airtight timing chamber having a flexible wall, means to both actuate said switch and expel air from said chamber, a spring tending to move said flexible wall back to its initial position, a temperature modified orifice which corrects for changes in air viscosity with temperature change permitting air to gradually flow back into said timing chamber, means to actuate the switch when the flexible wall of said timing chamber reaches its initial position.

24. A pneumatic time delay device that can readily be put out of action having, in combination, a chamber below atmospheric pressure, an orifice admitting air to 13 said chamber, an elongated needle extending into said orifice and partly restricting it, a spring holding said needle in said position in said orifice, externally accessible means to draw said needle out of said orifice against said spring to allow the chamber to fill With air without delay.

References Cited in the file of this patent UNITED STATES PATENTS 14 Ponstingl et al. Jan. 16, 1951 Lindahl Mar. 10, 1953 Schaefer July 14, 1953 Schaefer Dec. 15, 1953 Opsahl Dec. 4, 1956 Nadrowski et a1 Oct. 8, 1957 Bachi Dec. 30, 1958 Yarrick Apr. 14, 1959 Humim Apr. 14, 1959 FOREIGN PATENTS Germany June 30, 1957

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